It's not necessary to do rounding for alloca operations when the requested
alignment is equal to the stack alignment.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@40004 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp
new file mode 100644
index 0000000..816a1c6
--- /dev/null
+++ b/lib/Transforms/Scalar/InstructionCombining.cpp
@@ -0,0 +1,10090 @@
+//===- InstructionCombining.cpp - Combine multiple instructions -----------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file was developed by the LLVM research group and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// InstructionCombining - Combine instructions to form fewer, simple
+// instructions. This pass does not modify the CFG This pass is where algebraic
+// simplification happens.
+//
+// This pass combines things like:
+// %Y = add i32 %X, 1
+// %Z = add i32 %Y, 1
+// into:
+// %Z = add i32 %X, 2
+//
+// This is a simple worklist driven algorithm.
+//
+// This pass guarantees that the following canonicalizations are performed on
+// the program:
+// 1. If a binary operator has a constant operand, it is moved to the RHS
+// 2. Bitwise operators with constant operands are always grouped so that
+// shifts are performed first, then or's, then and's, then xor's.
+// 3. Compare instructions are converted from <,>,<=,>= to ==,!= if possible
+// 4. All cmp instructions on boolean values are replaced with logical ops
+// 5. add X, X is represented as (X*2) => (X << 1)
+// 6. Multiplies with a power-of-two constant argument are transformed into
+// shifts.
+// ... etc.
+//
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "instcombine"
+#include "llvm/Transforms/Scalar.h"
+#include "llvm/IntrinsicInst.h"
+#include "llvm/Pass.h"
+#include "llvm/DerivedTypes.h"
+#include "llvm/GlobalVariable.h"
+#include "llvm/Analysis/ConstantFolding.h"
+#include "llvm/Target/TargetData.h"
+#include "llvm/Transforms/Utils/BasicBlockUtils.h"
+#include "llvm/Transforms/Utils/Local.h"
+#include "llvm/Support/CallSite.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/GetElementPtrTypeIterator.h"
+#include "llvm/Support/InstVisitor.h"
+#include "llvm/Support/MathExtras.h"
+#include "llvm/Support/PatternMatch.h"
+#include "llvm/Support/Compiler.h"
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/ADT/STLExtras.h"
+#include <algorithm>
+#include <sstream>
+using namespace llvm;
+using namespace llvm::PatternMatch;
+
+STATISTIC(NumCombined , "Number of insts combined");
+STATISTIC(NumConstProp, "Number of constant folds");
+STATISTIC(NumDeadInst , "Number of dead inst eliminated");
+STATISTIC(NumDeadStore, "Number of dead stores eliminated");
+STATISTIC(NumSunkInst , "Number of instructions sunk");
+
+namespace {
+ class VISIBILITY_HIDDEN InstCombiner
+ : public FunctionPass,
+ public InstVisitor<InstCombiner, Instruction*> {
+ // Worklist of all of the instructions that need to be simplified.
+ std::vector<Instruction*> Worklist;
+ DenseMap<Instruction*, unsigned> WorklistMap;
+ TargetData *TD;
+ bool MustPreserveLCSSA;
+ public:
+ static char ID; // Pass identification, replacement for typeid
+ InstCombiner() : FunctionPass((intptr_t)&ID) {}
+
+ /// AddToWorkList - Add the specified instruction to the worklist if it
+ /// isn't already in it.
+ void AddToWorkList(Instruction *I) {
+ if (WorklistMap.insert(std::make_pair(I, Worklist.size())))
+ Worklist.push_back(I);
+ }
+
+ // RemoveFromWorkList - remove I from the worklist if it exists.
+ void RemoveFromWorkList(Instruction *I) {
+ DenseMap<Instruction*, unsigned>::iterator It = WorklistMap.find(I);
+ if (It == WorklistMap.end()) return; // Not in worklist.
+
+ // Don't bother moving everything down, just null out the slot.
+ Worklist[It->second] = 0;
+
+ WorklistMap.erase(It);
+ }
+
+ Instruction *RemoveOneFromWorkList() {
+ Instruction *I = Worklist.back();
+ Worklist.pop_back();
+ WorklistMap.erase(I);
+ return I;
+ }
+
+
+ /// AddUsersToWorkList - When an instruction is simplified, add all users of
+ /// the instruction to the work lists because they might get more simplified
+ /// now.
+ ///
+ void AddUsersToWorkList(Value &I) {
+ for (Value::use_iterator UI = I.use_begin(), UE = I.use_end();
+ UI != UE; ++UI)
+ AddToWorkList(cast<Instruction>(*UI));
+ }
+
+ /// AddUsesToWorkList - When an instruction is simplified, add operands to
+ /// the work lists because they might get more simplified now.
+ ///
+ void AddUsesToWorkList(Instruction &I) {
+ for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
+ if (Instruction *Op = dyn_cast<Instruction>(I.getOperand(i)))
+ AddToWorkList(Op);
+ }
+
+ /// AddSoonDeadInstToWorklist - The specified instruction is about to become
+ /// dead. Add all of its operands to the worklist, turning them into
+ /// undef's to reduce the number of uses of those instructions.
+ ///
+ /// Return the specified operand before it is turned into an undef.
+ ///
+ Value *AddSoonDeadInstToWorklist(Instruction &I, unsigned op) {
+ Value *R = I.getOperand(op);
+
+ for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
+ if (Instruction *Op = dyn_cast<Instruction>(I.getOperand(i))) {
+ AddToWorkList(Op);
+ // Set the operand to undef to drop the use.
+ I.setOperand(i, UndefValue::get(Op->getType()));
+ }
+
+ return R;
+ }
+
+ public:
+ virtual bool runOnFunction(Function &F);
+
+ bool DoOneIteration(Function &F, unsigned ItNum);
+
+ virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+ AU.addRequired<TargetData>();
+ AU.addPreservedID(LCSSAID);
+ AU.setPreservesCFG();
+ }
+
+ TargetData &getTargetData() const { return *TD; }
+
+ // Visitation implementation - Implement instruction combining for different
+ // instruction types. The semantics are as follows:
+ // Return Value:
+ // null - No change was made
+ // I - Change was made, I is still valid, I may be dead though
+ // otherwise - Change was made, replace I with returned instruction
+ //
+ Instruction *visitAdd(BinaryOperator &I);
+ Instruction *visitSub(BinaryOperator &I);
+ Instruction *visitMul(BinaryOperator &I);
+ Instruction *visitURem(BinaryOperator &I);
+ Instruction *visitSRem(BinaryOperator &I);
+ Instruction *visitFRem(BinaryOperator &I);
+ Instruction *commonRemTransforms(BinaryOperator &I);
+ Instruction *commonIRemTransforms(BinaryOperator &I);
+ Instruction *commonDivTransforms(BinaryOperator &I);
+ Instruction *commonIDivTransforms(BinaryOperator &I);
+ Instruction *visitUDiv(BinaryOperator &I);
+ Instruction *visitSDiv(BinaryOperator &I);
+ Instruction *visitFDiv(BinaryOperator &I);
+ Instruction *visitAnd(BinaryOperator &I);
+ Instruction *visitOr (BinaryOperator &I);
+ Instruction *visitXor(BinaryOperator &I);
+ Instruction *visitShl(BinaryOperator &I);
+ Instruction *visitAShr(BinaryOperator &I);
+ Instruction *visitLShr(BinaryOperator &I);
+ Instruction *commonShiftTransforms(BinaryOperator &I);
+ Instruction *visitFCmpInst(FCmpInst &I);
+ Instruction *visitICmpInst(ICmpInst &I);
+ Instruction *visitICmpInstWithCastAndCast(ICmpInst &ICI);
+ Instruction *visitICmpInstWithInstAndIntCst(ICmpInst &ICI,
+ Instruction *LHS,
+ ConstantInt *RHS);
+ Instruction *FoldICmpDivCst(ICmpInst &ICI, BinaryOperator *DivI,
+ ConstantInt *DivRHS);
+
+ Instruction *FoldGEPICmp(User *GEPLHS, Value *RHS,
+ ICmpInst::Predicate Cond, Instruction &I);
+ Instruction *FoldShiftByConstant(Value *Op0, ConstantInt *Op1,
+ BinaryOperator &I);
+ Instruction *commonCastTransforms(CastInst &CI);
+ Instruction *commonIntCastTransforms(CastInst &CI);
+ Instruction *commonPointerCastTransforms(CastInst &CI);
+ Instruction *visitTrunc(TruncInst &CI);
+ Instruction *visitZExt(ZExtInst &CI);
+ Instruction *visitSExt(SExtInst &CI);
+ Instruction *visitFPTrunc(CastInst &CI);
+ Instruction *visitFPExt(CastInst &CI);
+ Instruction *visitFPToUI(CastInst &CI);
+ Instruction *visitFPToSI(CastInst &CI);
+ Instruction *visitUIToFP(CastInst &CI);
+ Instruction *visitSIToFP(CastInst &CI);
+ Instruction *visitPtrToInt(CastInst &CI);
+ Instruction *visitIntToPtr(CastInst &CI);
+ Instruction *visitBitCast(BitCastInst &CI);
+ Instruction *FoldSelectOpOp(SelectInst &SI, Instruction *TI,
+ Instruction *FI);
+ Instruction *visitSelectInst(SelectInst &CI);
+ Instruction *visitCallInst(CallInst &CI);
+ Instruction *visitInvokeInst(InvokeInst &II);
+ Instruction *visitPHINode(PHINode &PN);
+ Instruction *visitGetElementPtrInst(GetElementPtrInst &GEP);
+ Instruction *visitAllocationInst(AllocationInst &AI);
+ Instruction *visitFreeInst(FreeInst &FI);
+ Instruction *visitLoadInst(LoadInst &LI);
+ Instruction *visitStoreInst(StoreInst &SI);
+ Instruction *visitBranchInst(BranchInst &BI);
+ Instruction *visitSwitchInst(SwitchInst &SI);
+ Instruction *visitInsertElementInst(InsertElementInst &IE);
+ Instruction *visitExtractElementInst(ExtractElementInst &EI);
+ Instruction *visitShuffleVectorInst(ShuffleVectorInst &SVI);
+
+ // visitInstruction - Specify what to return for unhandled instructions...
+ Instruction *visitInstruction(Instruction &I) { return 0; }
+
+ private:
+ Instruction *visitCallSite(CallSite CS);
+ bool transformConstExprCastCall(CallSite CS);
+
+ public:
+ // InsertNewInstBefore - insert an instruction New before instruction Old
+ // in the program. Add the new instruction to the worklist.
+ //
+ Instruction *InsertNewInstBefore(Instruction *New, Instruction &Old) {
+ assert(New && New->getParent() == 0 &&
+ "New instruction already inserted into a basic block!");
+ BasicBlock *BB = Old.getParent();
+ BB->getInstList().insert(&Old, New); // Insert inst
+ AddToWorkList(New);
+ return New;
+ }
+
+ /// InsertCastBefore - Insert a cast of V to TY before the instruction POS.
+ /// This also adds the cast to the worklist. Finally, this returns the
+ /// cast.
+ Value *InsertCastBefore(Instruction::CastOps opc, Value *V, const Type *Ty,
+ Instruction &Pos) {
+ if (V->getType() == Ty) return V;
+
+ if (Constant *CV = dyn_cast<Constant>(V))
+ return ConstantExpr::getCast(opc, CV, Ty);
+
+ Instruction *C = CastInst::create(opc, V, Ty, V->getName(), &Pos);
+ AddToWorkList(C);
+ return C;
+ }
+
+ // ReplaceInstUsesWith - This method is to be used when an instruction is
+ // found to be dead, replacable with another preexisting expression. Here
+ // we add all uses of I to the worklist, replace all uses of I with the new
+ // value, then return I, so that the inst combiner will know that I was
+ // modified.
+ //
+ Instruction *ReplaceInstUsesWith(Instruction &I, Value *V) {
+ AddUsersToWorkList(I); // Add all modified instrs to worklist
+ if (&I != V) {
+ I.replaceAllUsesWith(V);
+ return &I;
+ } else {
+ // If we are replacing the instruction with itself, this must be in a
+ // segment of unreachable code, so just clobber the instruction.
+ I.replaceAllUsesWith(UndefValue::get(I.getType()));
+ return &I;
+ }
+ }
+
+ // UpdateValueUsesWith - This method is to be used when an value is
+ // found to be replacable with another preexisting expression or was
+ // updated. Here we add all uses of I to the worklist, replace all uses of
+ // I with the new value (unless the instruction was just updated), then
+ // return true, so that the inst combiner will know that I was modified.
+ //
+ bool UpdateValueUsesWith(Value *Old, Value *New) {
+ AddUsersToWorkList(*Old); // Add all modified instrs to worklist
+ if (Old != New)
+ Old->replaceAllUsesWith(New);
+ if (Instruction *I = dyn_cast<Instruction>(Old))
+ AddToWorkList(I);
+ if (Instruction *I = dyn_cast<Instruction>(New))
+ AddToWorkList(I);
+ return true;
+ }
+
+ // EraseInstFromFunction - When dealing with an instruction that has side
+ // effects or produces a void value, we can't rely on DCE to delete the
+ // instruction. Instead, visit methods should return the value returned by
+ // this function.
+ Instruction *EraseInstFromFunction(Instruction &I) {
+ assert(I.use_empty() && "Cannot erase instruction that is used!");
+ AddUsesToWorkList(I);
+ RemoveFromWorkList(&I);
+ I.eraseFromParent();
+ return 0; // Don't do anything with FI
+ }
+
+ private:
+ /// InsertOperandCastBefore - This inserts a cast of V to DestTy before the
+ /// InsertBefore instruction. This is specialized a bit to avoid inserting
+ /// casts that are known to not do anything...
+ ///
+ Value *InsertOperandCastBefore(Instruction::CastOps opcode,
+ Value *V, const Type *DestTy,
+ Instruction *InsertBefore);
+
+ /// SimplifyCommutative - This performs a few simplifications for
+ /// commutative operators.
+ bool SimplifyCommutative(BinaryOperator &I);
+
+ /// SimplifyCompare - This reorders the operands of a CmpInst to get them in
+ /// most-complex to least-complex order.
+ bool SimplifyCompare(CmpInst &I);
+
+ /// SimplifyDemandedBits - Attempts to replace V with a simpler value based
+ /// on the demanded bits.
+ bool SimplifyDemandedBits(Value *V, APInt DemandedMask,
+ APInt& KnownZero, APInt& KnownOne,
+ unsigned Depth = 0);
+
+ Value *SimplifyDemandedVectorElts(Value *V, uint64_t DemandedElts,
+ uint64_t &UndefElts, unsigned Depth = 0);
+
+ // FoldOpIntoPhi - Given a binary operator or cast instruction which has a
+ // PHI node as operand #0, see if we can fold the instruction into the PHI
+ // (which is only possible if all operands to the PHI are constants).
+ Instruction *FoldOpIntoPhi(Instruction &I);
+
+ // FoldPHIArgOpIntoPHI - If all operands to a PHI node are the same "unary"
+ // operator and they all are only used by the PHI, PHI together their
+ // inputs, and do the operation once, to the result of the PHI.
+ Instruction *FoldPHIArgOpIntoPHI(PHINode &PN);
+ Instruction *FoldPHIArgBinOpIntoPHI(PHINode &PN);
+
+
+ Instruction *OptAndOp(Instruction *Op, ConstantInt *OpRHS,
+ ConstantInt *AndRHS, BinaryOperator &TheAnd);
+
+ Value *FoldLogicalPlusAnd(Value *LHS, Value *RHS, ConstantInt *Mask,
+ bool isSub, Instruction &I);
+ Instruction *InsertRangeTest(Value *V, Constant *Lo, Constant *Hi,
+ bool isSigned, bool Inside, Instruction &IB);
+ Instruction *PromoteCastOfAllocation(BitCastInst &CI, AllocationInst &AI);
+ Instruction *MatchBSwap(BinaryOperator &I);
+ bool SimplifyStoreAtEndOfBlock(StoreInst &SI);
+
+ Value *EvaluateInDifferentType(Value *V, const Type *Ty, bool isSigned);
+ };
+
+ char InstCombiner::ID = 0;
+ RegisterPass<InstCombiner> X("instcombine", "Combine redundant instructions");
+}
+
+// getComplexity: Assign a complexity or rank value to LLVM Values...
+// 0 -> undef, 1 -> Const, 2 -> Other, 3 -> Arg, 3 -> Unary, 4 -> OtherInst
+static unsigned getComplexity(Value *V) {
+ if (isa<Instruction>(V)) {
+ if (BinaryOperator::isNeg(V) || BinaryOperator::isNot(V))
+ return 3;
+ return 4;
+ }
+ if (isa<Argument>(V)) return 3;
+ return isa<Constant>(V) ? (isa<UndefValue>(V) ? 0 : 1) : 2;
+}
+
+// isOnlyUse - Return true if this instruction will be deleted if we stop using
+// it.
+static bool isOnlyUse(Value *V) {
+ return V->hasOneUse() || isa<Constant>(V);
+}
+
+// getPromotedType - Return the specified type promoted as it would be to pass
+// though a va_arg area...
+static const Type *getPromotedType(const Type *Ty) {
+ if (const IntegerType* ITy = dyn_cast<IntegerType>(Ty)) {
+ if (ITy->getBitWidth() < 32)
+ return Type::Int32Ty;
+ }
+ return Ty;
+}
+
+/// getBitCastOperand - If the specified operand is a CastInst or a constant
+/// expression bitcast, return the operand value, otherwise return null.
+static Value *getBitCastOperand(Value *V) {
+ if (BitCastInst *I = dyn_cast<BitCastInst>(V))
+ return I->getOperand(0);
+ else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V))
+ if (CE->getOpcode() == Instruction::BitCast)
+ return CE->getOperand(0);
+ return 0;
+}
+
+/// This function is a wrapper around CastInst::isEliminableCastPair. It
+/// simply extracts arguments and returns what that function returns.
+static Instruction::CastOps
+isEliminableCastPair(
+ const CastInst *CI, ///< The first cast instruction
+ unsigned opcode, ///< The opcode of the second cast instruction
+ const Type *DstTy, ///< The target type for the second cast instruction
+ TargetData *TD ///< The target data for pointer size
+) {
+
+ const Type *SrcTy = CI->getOperand(0)->getType(); // A from above
+ const Type *MidTy = CI->getType(); // B from above
+
+ // Get the opcodes of the two Cast instructions
+ Instruction::CastOps firstOp = Instruction::CastOps(CI->getOpcode());
+ Instruction::CastOps secondOp = Instruction::CastOps(opcode);
+
+ return Instruction::CastOps(
+ CastInst::isEliminableCastPair(firstOp, secondOp, SrcTy, MidTy,
+ DstTy, TD->getIntPtrType()));
+}
+
+/// ValueRequiresCast - Return true if the cast from "V to Ty" actually results
+/// in any code being generated. It does not require codegen if V is simple
+/// enough or if the cast can be folded into other casts.
+static bool ValueRequiresCast(Instruction::CastOps opcode, const Value *V,
+ const Type *Ty, TargetData *TD) {
+ if (V->getType() == Ty || isa<Constant>(V)) return false;
+
+ // If this is another cast that can be eliminated, it isn't codegen either.
+ if (const CastInst *CI = dyn_cast<CastInst>(V))
+ if (isEliminableCastPair(CI, opcode, Ty, TD))
+ return false;
+ return true;
+}
+
+/// InsertOperandCastBefore - This inserts a cast of V to DestTy before the
+/// InsertBefore instruction. This is specialized a bit to avoid inserting
+/// casts that are known to not do anything...
+///
+Value *InstCombiner::InsertOperandCastBefore(Instruction::CastOps opcode,
+ Value *V, const Type *DestTy,
+ Instruction *InsertBefore) {
+ if (V->getType() == DestTy) return V;
+ if (Constant *C = dyn_cast<Constant>(V))
+ return ConstantExpr::getCast(opcode, C, DestTy);
+
+ return InsertCastBefore(opcode, V, DestTy, *InsertBefore);
+}
+
+// SimplifyCommutative - This performs a few simplifications for commutative
+// operators:
+//
+// 1. Order operands such that they are listed from right (least complex) to
+// left (most complex). This puts constants before unary operators before
+// binary operators.
+//
+// 2. Transform: (op (op V, C1), C2) ==> (op V, (op C1, C2))
+// 3. Transform: (op (op V1, C1), (op V2, C2)) ==> (op (op V1, V2), (op C1,C2))
+//
+bool InstCombiner::SimplifyCommutative(BinaryOperator &I) {
+ bool Changed = false;
+ if (getComplexity(I.getOperand(0)) < getComplexity(I.getOperand(1)))
+ Changed = !I.swapOperands();
+
+ if (!I.isAssociative()) return Changed;
+ Instruction::BinaryOps Opcode = I.getOpcode();
+ if (BinaryOperator *Op = dyn_cast<BinaryOperator>(I.getOperand(0)))
+ if (Op->getOpcode() == Opcode && isa<Constant>(Op->getOperand(1))) {
+ if (isa<Constant>(I.getOperand(1))) {
+ Constant *Folded = ConstantExpr::get(I.getOpcode(),
+ cast<Constant>(I.getOperand(1)),
+ cast<Constant>(Op->getOperand(1)));
+ I.setOperand(0, Op->getOperand(0));
+ I.setOperand(1, Folded);
+ return true;
+ } else if (BinaryOperator *Op1=dyn_cast<BinaryOperator>(I.getOperand(1)))
+ if (Op1->getOpcode() == Opcode && isa<Constant>(Op1->getOperand(1)) &&
+ isOnlyUse(Op) && isOnlyUse(Op1)) {
+ Constant *C1 = cast<Constant>(Op->getOperand(1));
+ Constant *C2 = cast<Constant>(Op1->getOperand(1));
+
+ // Fold (op (op V1, C1), (op V2, C2)) ==> (op (op V1, V2), (op C1,C2))
+ Constant *Folded = ConstantExpr::get(I.getOpcode(), C1, C2);
+ Instruction *New = BinaryOperator::create(Opcode, Op->getOperand(0),
+ Op1->getOperand(0),
+ Op1->getName(), &I);
+ AddToWorkList(New);
+ I.setOperand(0, New);
+ I.setOperand(1, Folded);
+ return true;
+ }
+ }
+ return Changed;
+}
+
+/// SimplifyCompare - For a CmpInst this function just orders the operands
+/// so that theyare listed from right (least complex) to left (most complex).
+/// This puts constants before unary operators before binary operators.
+bool InstCombiner::SimplifyCompare(CmpInst &I) {
+ if (getComplexity(I.getOperand(0)) >= getComplexity(I.getOperand(1)))
+ return false;
+ I.swapOperands();
+ // Compare instructions are not associative so there's nothing else we can do.
+ return true;
+}
+
+// dyn_castNegVal - Given a 'sub' instruction, return the RHS of the instruction
+// if the LHS is a constant zero (which is the 'negate' form).
+//
+static inline Value *dyn_castNegVal(Value *V) {
+ if (BinaryOperator::isNeg(V))
+ return BinaryOperator::getNegArgument(V);
+
+ // Constants can be considered to be negated values if they can be folded.
+ if (ConstantInt *C = dyn_cast<ConstantInt>(V))
+ return ConstantExpr::getNeg(C);
+ return 0;
+}
+
+static inline Value *dyn_castNotVal(Value *V) {
+ if (BinaryOperator::isNot(V))
+ return BinaryOperator::getNotArgument(V);
+
+ // Constants can be considered to be not'ed values...
+ if (ConstantInt *C = dyn_cast<ConstantInt>(V))
+ return ConstantInt::get(~C->getValue());
+ return 0;
+}
+
+// dyn_castFoldableMul - If this value is a multiply that can be folded into
+// other computations (because it has a constant operand), return the
+// non-constant operand of the multiply, and set CST to point to the multiplier.
+// Otherwise, return null.
+//
+static inline Value *dyn_castFoldableMul(Value *V, ConstantInt *&CST) {
+ if (V->hasOneUse() && V->getType()->isInteger())
+ if (Instruction *I = dyn_cast<Instruction>(V)) {
+ if (I->getOpcode() == Instruction::Mul)
+ if ((CST = dyn_cast<ConstantInt>(I->getOperand(1))))
+ return I->getOperand(0);
+ if (I->getOpcode() == Instruction::Shl)
+ if ((CST = dyn_cast<ConstantInt>(I->getOperand(1)))) {
+ // The multiplier is really 1 << CST.
+ uint32_t BitWidth = cast<IntegerType>(V->getType())->getBitWidth();
+ uint32_t CSTVal = CST->getLimitedValue(BitWidth);
+ CST = ConstantInt::get(APInt(BitWidth, 1).shl(CSTVal));
+ return I->getOperand(0);
+ }
+ }
+ return 0;
+}
+
+/// dyn_castGetElementPtr - If this is a getelementptr instruction or constant
+/// expression, return it.
+static User *dyn_castGetElementPtr(Value *V) {
+ if (isa<GetElementPtrInst>(V)) return cast<User>(V);
+ if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V))
+ if (CE->getOpcode() == Instruction::GetElementPtr)
+ return cast<User>(V);
+ return false;
+}
+
+/// AddOne - Add one to a ConstantInt
+static ConstantInt *AddOne(ConstantInt *C) {
+ APInt Val(C->getValue());
+ return ConstantInt::get(++Val);
+}
+/// SubOne - Subtract one from a ConstantInt
+static ConstantInt *SubOne(ConstantInt *C) {
+ APInt Val(C->getValue());
+ return ConstantInt::get(--Val);
+}
+/// Add - Add two ConstantInts together
+static ConstantInt *Add(ConstantInt *C1, ConstantInt *C2) {
+ return ConstantInt::get(C1->getValue() + C2->getValue());
+}
+/// And - Bitwise AND two ConstantInts together
+static ConstantInt *And(ConstantInt *C1, ConstantInt *C2) {
+ return ConstantInt::get(C1->getValue() & C2->getValue());
+}
+/// Subtract - Subtract one ConstantInt from another
+static ConstantInt *Subtract(ConstantInt *C1, ConstantInt *C2) {
+ return ConstantInt::get(C1->getValue() - C2->getValue());
+}
+/// Multiply - Multiply two ConstantInts together
+static ConstantInt *Multiply(ConstantInt *C1, ConstantInt *C2) {
+ return ConstantInt::get(C1->getValue() * C2->getValue());
+}
+
+/// ComputeMaskedBits - Determine which of the bits specified in Mask are
+/// known to be either zero or one and return them in the KnownZero/KnownOne
+/// bit sets. This code only analyzes bits in Mask, in order to short-circuit
+/// processing.
+/// NOTE: we cannot consider 'undef' to be "IsZero" here. The problem is that
+/// we cannot optimize based on the assumption that it is zero without changing
+/// it to be an explicit zero. If we don't change it to zero, other code could
+/// optimized based on the contradictory assumption that it is non-zero.
+/// Because instcombine aggressively folds operations with undef args anyway,
+/// this won't lose us code quality.
+static void ComputeMaskedBits(Value *V, const APInt &Mask, APInt& KnownZero,
+ APInt& KnownOne, unsigned Depth = 0) {
+ assert(V && "No Value?");
+ assert(Depth <= 6 && "Limit Search Depth");
+ uint32_t BitWidth = Mask.getBitWidth();
+ assert(cast<IntegerType>(V->getType())->getBitWidth() == BitWidth &&
+ KnownZero.getBitWidth() == BitWidth &&
+ KnownOne.getBitWidth() == BitWidth &&
+ "V, Mask, KnownOne and KnownZero should have same BitWidth");
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
+ // We know all of the bits for a constant!
+ KnownOne = CI->getValue() & Mask;
+ KnownZero = ~KnownOne & Mask;
+ return;
+ }
+
+ if (Depth == 6 || Mask == 0)
+ return; // Limit search depth.
+
+ Instruction *I = dyn_cast<Instruction>(V);
+ if (!I) return;
+
+ KnownZero.clear(); KnownOne.clear(); // Don't know anything.
+ APInt KnownZero2(KnownZero), KnownOne2(KnownOne);
+
+ switch (I->getOpcode()) {
+ case Instruction::And: {
+ // If either the LHS or the RHS are Zero, the result is zero.
+ ComputeMaskedBits(I->getOperand(1), Mask, KnownZero, KnownOne, Depth+1);
+ APInt Mask2(Mask & ~KnownZero);
+ ComputeMaskedBits(I->getOperand(0), Mask2, KnownZero2, KnownOne2, Depth+1);
+ assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
+ assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
+
+ // Output known-1 bits are only known if set in both the LHS & RHS.
+ KnownOne &= KnownOne2;
+ // Output known-0 are known to be clear if zero in either the LHS | RHS.
+ KnownZero |= KnownZero2;
+ return;
+ }
+ case Instruction::Or: {
+ ComputeMaskedBits(I->getOperand(1), Mask, KnownZero, KnownOne, Depth+1);
+ APInt Mask2(Mask & ~KnownOne);
+ ComputeMaskedBits(I->getOperand(0), Mask2, KnownZero2, KnownOne2, Depth+1);
+ assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
+ assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
+
+ // Output known-0 bits are only known if clear in both the LHS & RHS.
+ KnownZero &= KnownZero2;
+ // Output known-1 are known to be set if set in either the LHS | RHS.
+ KnownOne |= KnownOne2;
+ return;
+ }
+ case Instruction::Xor: {
+ ComputeMaskedBits(I->getOperand(1), Mask, KnownZero, KnownOne, Depth+1);
+ ComputeMaskedBits(I->getOperand(0), Mask, KnownZero2, KnownOne2, Depth+1);
+ assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
+ assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
+
+ // Output known-0 bits are known if clear or set in both the LHS & RHS.
+ APInt KnownZeroOut = (KnownZero & KnownZero2) | (KnownOne & KnownOne2);
+ // Output known-1 are known to be set if set in only one of the LHS, RHS.
+ KnownOne = (KnownZero & KnownOne2) | (KnownOne & KnownZero2);
+ KnownZero = KnownZeroOut;
+ return;
+ }
+ case Instruction::Select:
+ ComputeMaskedBits(I->getOperand(2), Mask, KnownZero, KnownOne, Depth+1);
+ ComputeMaskedBits(I->getOperand(1), Mask, KnownZero2, KnownOne2, Depth+1);
+ assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
+ assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
+
+ // Only known if known in both the LHS and RHS.
+ KnownOne &= KnownOne2;
+ KnownZero &= KnownZero2;
+ return;
+ case Instruction::FPTrunc:
+ case Instruction::FPExt:
+ case Instruction::FPToUI:
+ case Instruction::FPToSI:
+ case Instruction::SIToFP:
+ case Instruction::PtrToInt:
+ case Instruction::UIToFP:
+ case Instruction::IntToPtr:
+ return; // Can't work with floating point or pointers
+ case Instruction::Trunc: {
+ // All these have integer operands
+ uint32_t SrcBitWidth =
+ cast<IntegerType>(I->getOperand(0)->getType())->getBitWidth();
+ APInt MaskIn(Mask);
+ MaskIn.zext(SrcBitWidth);
+ KnownZero.zext(SrcBitWidth);
+ KnownOne.zext(SrcBitWidth);
+ ComputeMaskedBits(I->getOperand(0), MaskIn, KnownZero, KnownOne, Depth+1);
+ KnownZero.trunc(BitWidth);
+ KnownOne.trunc(BitWidth);
+ return;
+ }
+ case Instruction::BitCast: {
+ const Type *SrcTy = I->getOperand(0)->getType();
+ if (SrcTy->isInteger()) {
+ ComputeMaskedBits(I->getOperand(0), Mask, KnownZero, KnownOne, Depth+1);
+ return;
+ }
+ break;
+ }
+ case Instruction::ZExt: {
+ // Compute the bits in the result that are not present in the input.
+ const IntegerType *SrcTy = cast<IntegerType>(I->getOperand(0)->getType());
+ uint32_t SrcBitWidth = SrcTy->getBitWidth();
+
+ APInt MaskIn(Mask);
+ MaskIn.trunc(SrcBitWidth);
+ KnownZero.trunc(SrcBitWidth);
+ KnownOne.trunc(SrcBitWidth);
+ ComputeMaskedBits(I->getOperand(0), MaskIn, KnownZero, KnownOne, Depth+1);
+ assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
+ // The top bits are known to be zero.
+ KnownZero.zext(BitWidth);
+ KnownOne.zext(BitWidth);
+ KnownZero |= APInt::getHighBitsSet(BitWidth, BitWidth - SrcBitWidth);
+ return;
+ }
+ case Instruction::SExt: {
+ // Compute the bits in the result that are not present in the input.
+ const IntegerType *SrcTy = cast<IntegerType>(I->getOperand(0)->getType());
+ uint32_t SrcBitWidth = SrcTy->getBitWidth();
+
+ APInt MaskIn(Mask);
+ MaskIn.trunc(SrcBitWidth);
+ KnownZero.trunc(SrcBitWidth);
+ KnownOne.trunc(SrcBitWidth);
+ ComputeMaskedBits(I->getOperand(0), MaskIn, KnownZero, KnownOne, Depth+1);
+ assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
+ KnownZero.zext(BitWidth);
+ KnownOne.zext(BitWidth);
+
+ // If the sign bit of the input is known set or clear, then we know the
+ // top bits of the result.
+ if (KnownZero[SrcBitWidth-1]) // Input sign bit known zero
+ KnownZero |= APInt::getHighBitsSet(BitWidth, BitWidth - SrcBitWidth);
+ else if (KnownOne[SrcBitWidth-1]) // Input sign bit known set
+ KnownOne |= APInt::getHighBitsSet(BitWidth, BitWidth - SrcBitWidth);
+ return;
+ }
+ case Instruction::Shl:
+ // (shl X, C1) & C2 == 0 iff (X & C2 >>u C1) == 0
+ if (ConstantInt *SA = dyn_cast<ConstantInt>(I->getOperand(1))) {
+ uint64_t ShiftAmt = SA->getLimitedValue(BitWidth);
+ APInt Mask2(Mask.lshr(ShiftAmt));
+ ComputeMaskedBits(I->getOperand(0), Mask2, KnownZero, KnownOne, Depth+1);
+ assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
+ KnownZero <<= ShiftAmt;
+ KnownOne <<= ShiftAmt;
+ KnownZero |= APInt::getLowBitsSet(BitWidth, ShiftAmt); // low bits known 0
+ return;
+ }
+ break;
+ case Instruction::LShr:
+ // (ushr X, C1) & C2 == 0 iff (-1 >> C1) & C2 == 0
+ if (ConstantInt *SA = dyn_cast<ConstantInt>(I->getOperand(1))) {
+ // Compute the new bits that are at the top now.
+ uint64_t ShiftAmt = SA->getLimitedValue(BitWidth);
+
+ // Unsigned shift right.
+ APInt Mask2(Mask.shl(ShiftAmt));
+ ComputeMaskedBits(I->getOperand(0), Mask2, KnownZero,KnownOne,Depth+1);
+ assert((KnownZero & KnownOne) == 0&&"Bits known to be one AND zero?");
+ KnownZero = APIntOps::lshr(KnownZero, ShiftAmt);
+ KnownOne = APIntOps::lshr(KnownOne, ShiftAmt);
+ // high bits known zero.
+ KnownZero |= APInt::getHighBitsSet(BitWidth, ShiftAmt);
+ return;
+ }
+ break;
+ case Instruction::AShr:
+ // (ashr X, C1) & C2 == 0 iff (-1 >> C1) & C2 == 0
+ if (ConstantInt *SA = dyn_cast<ConstantInt>(I->getOperand(1))) {
+ // Compute the new bits that are at the top now.
+ uint64_t ShiftAmt = SA->getLimitedValue(BitWidth);
+
+ // Signed shift right.
+ APInt Mask2(Mask.shl(ShiftAmt));
+ ComputeMaskedBits(I->getOperand(0), Mask2, KnownZero,KnownOne,Depth+1);
+ assert((KnownZero & KnownOne) == 0&&"Bits known to be one AND zero?");
+ KnownZero = APIntOps::lshr(KnownZero, ShiftAmt);
+ KnownOne = APIntOps::lshr(KnownOne, ShiftAmt);
+
+ APInt HighBits(APInt::getHighBitsSet(BitWidth, ShiftAmt));
+ if (KnownZero[BitWidth-ShiftAmt-1]) // New bits are known zero.
+ KnownZero |= HighBits;
+ else if (KnownOne[BitWidth-ShiftAmt-1]) // New bits are known one.
+ KnownOne |= HighBits;
+ return;
+ }
+ break;
+ }
+}
+
+/// MaskedValueIsZero - Return true if 'V & Mask' is known to be zero. We use
+/// this predicate to simplify operations downstream. Mask is known to be zero
+/// for bits that V cannot have.
+static bool MaskedValueIsZero(Value *V, const APInt& Mask, unsigned Depth = 0) {
+ APInt KnownZero(Mask.getBitWidth(), 0), KnownOne(Mask.getBitWidth(), 0);
+ ComputeMaskedBits(V, Mask, KnownZero, KnownOne, Depth);
+ assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
+ return (KnownZero & Mask) == Mask;
+}
+
+/// ShrinkDemandedConstant - Check to see if the specified operand of the
+/// specified instruction is a constant integer. If so, check to see if there
+/// are any bits set in the constant that are not demanded. If so, shrink the
+/// constant and return true.
+static bool ShrinkDemandedConstant(Instruction *I, unsigned OpNo,
+ APInt Demanded) {
+ assert(I && "No instruction?");
+ assert(OpNo < I->getNumOperands() && "Operand index too large");
+
+ // If the operand is not a constant integer, nothing to do.
+ ConstantInt *OpC = dyn_cast<ConstantInt>(I->getOperand(OpNo));
+ if (!OpC) return false;
+
+ // If there are no bits set that aren't demanded, nothing to do.
+ Demanded.zextOrTrunc(OpC->getValue().getBitWidth());
+ if ((~Demanded & OpC->getValue()) == 0)
+ return false;
+
+ // This instruction is producing bits that are not demanded. Shrink the RHS.
+ Demanded &= OpC->getValue();
+ I->setOperand(OpNo, ConstantInt::get(Demanded));
+ return true;
+}
+
+// ComputeSignedMinMaxValuesFromKnownBits - Given a signed integer type and a
+// set of known zero and one bits, compute the maximum and minimum values that
+// could have the specified known zero and known one bits, returning them in
+// min/max.
+static void ComputeSignedMinMaxValuesFromKnownBits(const Type *Ty,
+ const APInt& KnownZero,
+ const APInt& KnownOne,
+ APInt& Min, APInt& Max) {
+ uint32_t BitWidth = cast<IntegerType>(Ty)->getBitWidth();
+ assert(KnownZero.getBitWidth() == BitWidth &&
+ KnownOne.getBitWidth() == BitWidth &&
+ Min.getBitWidth() == BitWidth && Max.getBitWidth() == BitWidth &&
+ "Ty, KnownZero, KnownOne and Min, Max must have equal bitwidth.");
+ APInt UnknownBits = ~(KnownZero|KnownOne);
+
+ // The minimum value is when all unknown bits are zeros, EXCEPT for the sign
+ // bit if it is unknown.
+ Min = KnownOne;
+ Max = KnownOne|UnknownBits;
+
+ if (UnknownBits[BitWidth-1]) { // Sign bit is unknown
+ Min.set(BitWidth-1);
+ Max.clear(BitWidth-1);
+ }
+}
+
+// ComputeUnsignedMinMaxValuesFromKnownBits - Given an unsigned integer type and
+// a set of known zero and one bits, compute the maximum and minimum values that
+// could have the specified known zero and known one bits, returning them in
+// min/max.
+static void ComputeUnsignedMinMaxValuesFromKnownBits(const Type *Ty,
+ const APInt& KnownZero,
+ const APInt& KnownOne,
+ APInt& Min,
+ APInt& Max) {
+ uint32_t BitWidth = cast<IntegerType>(Ty)->getBitWidth();
+ assert(KnownZero.getBitWidth() == BitWidth &&
+ KnownOne.getBitWidth() == BitWidth &&
+ Min.getBitWidth() == BitWidth && Max.getBitWidth() &&
+ "Ty, KnownZero, KnownOne and Min, Max must have equal bitwidth.");
+ APInt UnknownBits = ~(KnownZero|KnownOne);
+
+ // The minimum value is when the unknown bits are all zeros.
+ Min = KnownOne;
+ // The maximum value is when the unknown bits are all ones.
+ Max = KnownOne|UnknownBits;
+}
+
+/// SimplifyDemandedBits - This function attempts to replace V with a simpler
+/// value based on the demanded bits. When this function is called, it is known
+/// that only the bits set in DemandedMask of the result of V are ever used
+/// downstream. Consequently, depending on the mask and V, it may be possible
+/// to replace V with a constant or one of its operands. In such cases, this
+/// function does the replacement and returns true. In all other cases, it
+/// returns false after analyzing the expression and setting KnownOne and known
+/// to be one in the expression. KnownZero contains all the bits that are known
+/// to be zero in the expression. These are provided to potentially allow the
+/// caller (which might recursively be SimplifyDemandedBits itself) to simplify
+/// the expression. KnownOne and KnownZero always follow the invariant that
+/// KnownOne & KnownZero == 0. That is, a bit can't be both 1 and 0. Note that
+/// the bits in KnownOne and KnownZero may only be accurate for those bits set
+/// in DemandedMask. Note also that the bitwidth of V, DemandedMask, KnownZero
+/// and KnownOne must all be the same.
+bool InstCombiner::SimplifyDemandedBits(Value *V, APInt DemandedMask,
+ APInt& KnownZero, APInt& KnownOne,
+ unsigned Depth) {
+ assert(V != 0 && "Null pointer of Value???");
+ assert(Depth <= 6 && "Limit Search Depth");
+ uint32_t BitWidth = DemandedMask.getBitWidth();
+ const IntegerType *VTy = cast<IntegerType>(V->getType());
+ assert(VTy->getBitWidth() == BitWidth &&
+ KnownZero.getBitWidth() == BitWidth &&
+ KnownOne.getBitWidth() == BitWidth &&
+ "Value *V, DemandedMask, KnownZero and KnownOne \
+ must have same BitWidth");
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
+ // We know all of the bits for a constant!
+ KnownOne = CI->getValue() & DemandedMask;
+ KnownZero = ~KnownOne & DemandedMask;
+ return false;
+ }
+
+ KnownZero.clear();
+ KnownOne.clear();
+ if (!V->hasOneUse()) { // Other users may use these bits.
+ if (Depth != 0) { // Not at the root.
+ // Just compute the KnownZero/KnownOne bits to simplify things downstream.
+ ComputeMaskedBits(V, DemandedMask, KnownZero, KnownOne, Depth);
+ return false;
+ }
+ // If this is the root being simplified, allow it to have multiple uses,
+ // just set the DemandedMask to all bits.
+ DemandedMask = APInt::getAllOnesValue(BitWidth);
+ } else if (DemandedMask == 0) { // Not demanding any bits from V.
+ if (V != UndefValue::get(VTy))
+ return UpdateValueUsesWith(V, UndefValue::get(VTy));
+ return false;
+ } else if (Depth == 6) { // Limit search depth.
+ return false;
+ }
+
+ Instruction *I = dyn_cast<Instruction>(V);
+ if (!I) return false; // Only analyze instructions.
+
+ APInt LHSKnownZero(BitWidth, 0), LHSKnownOne(BitWidth, 0);
+ APInt &RHSKnownZero = KnownZero, &RHSKnownOne = KnownOne;
+ switch (I->getOpcode()) {
+ default: break;
+ case Instruction::And:
+ // If either the LHS or the RHS are Zero, the result is zero.
+ if (SimplifyDemandedBits(I->getOperand(1), DemandedMask,
+ RHSKnownZero, RHSKnownOne, Depth+1))
+ return true;
+ assert((RHSKnownZero & RHSKnownOne) == 0 &&
+ "Bits known to be one AND zero?");
+
+ // If something is known zero on the RHS, the bits aren't demanded on the
+ // LHS.
+ if (SimplifyDemandedBits(I->getOperand(0), DemandedMask & ~RHSKnownZero,
+ LHSKnownZero, LHSKnownOne, Depth+1))
+ return true;
+ assert((LHSKnownZero & LHSKnownOne) == 0 &&
+ "Bits known to be one AND zero?");
+
+ // If all of the demanded bits are known 1 on one side, return the other.
+ // These bits cannot contribute to the result of the 'and'.
+ if ((DemandedMask & ~LHSKnownZero & RHSKnownOne) ==
+ (DemandedMask & ~LHSKnownZero))
+ return UpdateValueUsesWith(I, I->getOperand(0));
+ if ((DemandedMask & ~RHSKnownZero & LHSKnownOne) ==
+ (DemandedMask & ~RHSKnownZero))
+ return UpdateValueUsesWith(I, I->getOperand(1));
+
+ // If all of the demanded bits in the inputs are known zeros, return zero.
+ if ((DemandedMask & (RHSKnownZero|LHSKnownZero)) == DemandedMask)
+ return UpdateValueUsesWith(I, Constant::getNullValue(VTy));
+
+ // If the RHS is a constant, see if we can simplify it.
+ if (ShrinkDemandedConstant(I, 1, DemandedMask & ~LHSKnownZero))
+ return UpdateValueUsesWith(I, I);
+
+ // Output known-1 bits are only known if set in both the LHS & RHS.
+ RHSKnownOne &= LHSKnownOne;
+ // Output known-0 are known to be clear if zero in either the LHS | RHS.
+ RHSKnownZero |= LHSKnownZero;
+ break;
+ case Instruction::Or:
+ // If either the LHS or the RHS are One, the result is One.
+ if (SimplifyDemandedBits(I->getOperand(1), DemandedMask,
+ RHSKnownZero, RHSKnownOne, Depth+1))
+ return true;
+ assert((RHSKnownZero & RHSKnownOne) == 0 &&
+ "Bits known to be one AND zero?");
+ // If something is known one on the RHS, the bits aren't demanded on the
+ // LHS.
+ if (SimplifyDemandedBits(I->getOperand(0), DemandedMask & ~RHSKnownOne,
+ LHSKnownZero, LHSKnownOne, Depth+1))
+ return true;
+ assert((LHSKnownZero & LHSKnownOne) == 0 &&
+ "Bits known to be one AND zero?");
+
+ // If all of the demanded bits are known zero on one side, return the other.
+ // These bits cannot contribute to the result of the 'or'.
+ if ((DemandedMask & ~LHSKnownOne & RHSKnownZero) ==
+ (DemandedMask & ~LHSKnownOne))
+ return UpdateValueUsesWith(I, I->getOperand(0));
+ if ((DemandedMask & ~RHSKnownOne & LHSKnownZero) ==
+ (DemandedMask & ~RHSKnownOne))
+ return UpdateValueUsesWith(I, I->getOperand(1));
+
+ // If all of the potentially set bits on one side are known to be set on
+ // the other side, just use the 'other' side.
+ if ((DemandedMask & (~RHSKnownZero) & LHSKnownOne) ==
+ (DemandedMask & (~RHSKnownZero)))
+ return UpdateValueUsesWith(I, I->getOperand(0));
+ if ((DemandedMask & (~LHSKnownZero) & RHSKnownOne) ==
+ (DemandedMask & (~LHSKnownZero)))
+ return UpdateValueUsesWith(I, I->getOperand(1));
+
+ // If the RHS is a constant, see if we can simplify it.
+ if (ShrinkDemandedConstant(I, 1, DemandedMask))
+ return UpdateValueUsesWith(I, I);
+
+ // Output known-0 bits are only known if clear in both the LHS & RHS.
+ RHSKnownZero &= LHSKnownZero;
+ // Output known-1 are known to be set if set in either the LHS | RHS.
+ RHSKnownOne |= LHSKnownOne;
+ break;
+ case Instruction::Xor: {
+ if (SimplifyDemandedBits(I->getOperand(1), DemandedMask,
+ RHSKnownZero, RHSKnownOne, Depth+1))
+ return true;
+ assert((RHSKnownZero & RHSKnownOne) == 0 &&
+ "Bits known to be one AND zero?");
+ if (SimplifyDemandedBits(I->getOperand(0), DemandedMask,
+ LHSKnownZero, LHSKnownOne, Depth+1))
+ return true;
+ assert((LHSKnownZero & LHSKnownOne) == 0 &&
+ "Bits known to be one AND zero?");
+
+ // If all of the demanded bits are known zero on one side, return the other.
+ // These bits cannot contribute to the result of the 'xor'.
+ if ((DemandedMask & RHSKnownZero) == DemandedMask)
+ return UpdateValueUsesWith(I, I->getOperand(0));
+ if ((DemandedMask & LHSKnownZero) == DemandedMask)
+ return UpdateValueUsesWith(I, I->getOperand(1));
+
+ // Output known-0 bits are known if clear or set in both the LHS & RHS.
+ APInt KnownZeroOut = (RHSKnownZero & LHSKnownZero) |
+ (RHSKnownOne & LHSKnownOne);
+ // Output known-1 are known to be set if set in only one of the LHS, RHS.
+ APInt KnownOneOut = (RHSKnownZero & LHSKnownOne) |
+ (RHSKnownOne & LHSKnownZero);
+
+ // If all of the demanded bits are known to be zero on one side or the
+ // other, turn this into an *inclusive* or.
+ // e.g. (A & C1)^(B & C2) -> (A & C1)|(B & C2) iff C1&C2 == 0
+ if ((DemandedMask & ~RHSKnownZero & ~LHSKnownZero) == 0) {
+ Instruction *Or =
+ BinaryOperator::createOr(I->getOperand(0), I->getOperand(1),
+ I->getName());
+ InsertNewInstBefore(Or, *I);
+ return UpdateValueUsesWith(I, Or);
+ }
+
+ // If all of the demanded bits on one side are known, and all of the set
+ // bits on that side are also known to be set on the other side, turn this
+ // into an AND, as we know the bits will be cleared.
+ // e.g. (X | C1) ^ C2 --> (X | C1) & ~C2 iff (C1&C2) == C2
+ if ((DemandedMask & (RHSKnownZero|RHSKnownOne)) == DemandedMask) {
+ // all known
+ if ((RHSKnownOne & LHSKnownOne) == RHSKnownOne) {
+ Constant *AndC = ConstantInt::get(~RHSKnownOne & DemandedMask);
+ Instruction *And =
+ BinaryOperator::createAnd(I->getOperand(0), AndC, "tmp");
+ InsertNewInstBefore(And, *I);
+ return UpdateValueUsesWith(I, And);
+ }
+ }
+
+ // If the RHS is a constant, see if we can simplify it.
+ // FIXME: for XOR, we prefer to force bits to 1 if they will make a -1.
+ if (ShrinkDemandedConstant(I, 1, DemandedMask))
+ return UpdateValueUsesWith(I, I);
+
+ RHSKnownZero = KnownZeroOut;
+ RHSKnownOne = KnownOneOut;
+ break;
+ }
+ case Instruction::Select:
+ if (SimplifyDemandedBits(I->getOperand(2), DemandedMask,
+ RHSKnownZero, RHSKnownOne, Depth+1))
+ return true;
+ if (SimplifyDemandedBits(I->getOperand(1), DemandedMask,
+ LHSKnownZero, LHSKnownOne, Depth+1))
+ return true;
+ assert((RHSKnownZero & RHSKnownOne) == 0 &&
+ "Bits known to be one AND zero?");
+ assert((LHSKnownZero & LHSKnownOne) == 0 &&
+ "Bits known to be one AND zero?");
+
+ // If the operands are constants, see if we can simplify them.
+ if (ShrinkDemandedConstant(I, 1, DemandedMask))
+ return UpdateValueUsesWith(I, I);
+ if (ShrinkDemandedConstant(I, 2, DemandedMask))
+ return UpdateValueUsesWith(I, I);
+
+ // Only known if known in both the LHS and RHS.
+ RHSKnownOne &= LHSKnownOne;
+ RHSKnownZero &= LHSKnownZero;
+ break;
+ case Instruction::Trunc: {
+ uint32_t truncBf =
+ cast<IntegerType>(I->getOperand(0)->getType())->getBitWidth();
+ DemandedMask.zext(truncBf);
+ RHSKnownZero.zext(truncBf);
+ RHSKnownOne.zext(truncBf);
+ if (SimplifyDemandedBits(I->getOperand(0), DemandedMask,
+ RHSKnownZero, RHSKnownOne, Depth+1))
+ return true;
+ DemandedMask.trunc(BitWidth);
+ RHSKnownZero.trunc(BitWidth);
+ RHSKnownOne.trunc(BitWidth);
+ assert((RHSKnownZero & RHSKnownOne) == 0 &&
+ "Bits known to be one AND zero?");
+ break;
+ }
+ case Instruction::BitCast:
+ if (!I->getOperand(0)->getType()->isInteger())
+ return false;
+
+ if (SimplifyDemandedBits(I->getOperand(0), DemandedMask,
+ RHSKnownZero, RHSKnownOne, Depth+1))
+ return true;
+ assert((RHSKnownZero & RHSKnownOne) == 0 &&
+ "Bits known to be one AND zero?");
+ break;
+ case Instruction::ZExt: {
+ // Compute the bits in the result that are not present in the input.
+ const IntegerType *SrcTy = cast<IntegerType>(I->getOperand(0)->getType());
+ uint32_t SrcBitWidth = SrcTy->getBitWidth();
+
+ DemandedMask.trunc(SrcBitWidth);
+ RHSKnownZero.trunc(SrcBitWidth);
+ RHSKnownOne.trunc(SrcBitWidth);
+ if (SimplifyDemandedBits(I->getOperand(0), DemandedMask,
+ RHSKnownZero, RHSKnownOne, Depth+1))
+ return true;
+ DemandedMask.zext(BitWidth);
+ RHSKnownZero.zext(BitWidth);
+ RHSKnownOne.zext(BitWidth);
+ assert((RHSKnownZero & RHSKnownOne) == 0 &&
+ "Bits known to be one AND zero?");
+ // The top bits are known to be zero.
+ RHSKnownZero |= APInt::getHighBitsSet(BitWidth, BitWidth - SrcBitWidth);
+ break;
+ }
+ case Instruction::SExt: {
+ // Compute the bits in the result that are not present in the input.
+ const IntegerType *SrcTy = cast<IntegerType>(I->getOperand(0)->getType());
+ uint32_t SrcBitWidth = SrcTy->getBitWidth();
+
+ APInt InputDemandedBits = DemandedMask &
+ APInt::getLowBitsSet(BitWidth, SrcBitWidth);
+
+ APInt NewBits(APInt::getHighBitsSet(BitWidth, BitWidth - SrcBitWidth));
+ // If any of the sign extended bits are demanded, we know that the sign
+ // bit is demanded.
+ if ((NewBits & DemandedMask) != 0)
+ InputDemandedBits.set(SrcBitWidth-1);
+
+ InputDemandedBits.trunc(SrcBitWidth);
+ RHSKnownZero.trunc(SrcBitWidth);
+ RHSKnownOne.trunc(SrcBitWidth);
+ if (SimplifyDemandedBits(I->getOperand(0), InputDemandedBits,
+ RHSKnownZero, RHSKnownOne, Depth+1))
+ return true;
+ InputDemandedBits.zext(BitWidth);
+ RHSKnownZero.zext(BitWidth);
+ RHSKnownOne.zext(BitWidth);
+ assert((RHSKnownZero & RHSKnownOne) == 0 &&
+ "Bits known to be one AND zero?");
+
+ // If the sign bit of the input is known set or clear, then we know the
+ // top bits of the result.
+
+ // If the input sign bit is known zero, or if the NewBits are not demanded
+ // convert this into a zero extension.
+ if (RHSKnownZero[SrcBitWidth-1] || (NewBits & ~DemandedMask) == NewBits)
+ {
+ // Convert to ZExt cast
+ CastInst *NewCast = new ZExtInst(I->getOperand(0), VTy, I->getName(), I);
+ return UpdateValueUsesWith(I, NewCast);
+ } else if (RHSKnownOne[SrcBitWidth-1]) { // Input sign bit known set
+ RHSKnownOne |= NewBits;
+ }
+ break;
+ }
+ case Instruction::Add: {
+ // Figure out what the input bits are. If the top bits of the and result
+ // are not demanded, then the add doesn't demand them from its input
+ // either.
+ uint32_t NLZ = DemandedMask.countLeadingZeros();
+
+ // If there is a constant on the RHS, there are a variety of xformations
+ // we can do.
+ if (ConstantInt *RHS = dyn_cast<ConstantInt>(I->getOperand(1))) {
+ // If null, this should be simplified elsewhere. Some of the xforms here
+ // won't work if the RHS is zero.
+ if (RHS->isZero())
+ break;
+
+ // If the top bit of the output is demanded, demand everything from the
+ // input. Otherwise, we demand all the input bits except NLZ top bits.
+ APInt InDemandedBits(APInt::getLowBitsSet(BitWidth, BitWidth - NLZ));
+
+ // Find information about known zero/one bits in the input.
+ if (SimplifyDemandedBits(I->getOperand(0), InDemandedBits,
+ LHSKnownZero, LHSKnownOne, Depth+1))
+ return true;
+
+ // If the RHS of the add has bits set that can't affect the input, reduce
+ // the constant.
+ if (ShrinkDemandedConstant(I, 1, InDemandedBits))
+ return UpdateValueUsesWith(I, I);
+
+ // Avoid excess work.
+ if (LHSKnownZero == 0 && LHSKnownOne == 0)
+ break;
+
+ // Turn it into OR if input bits are zero.
+ if ((LHSKnownZero & RHS->getValue()) == RHS->getValue()) {
+ Instruction *Or =
+ BinaryOperator::createOr(I->getOperand(0), I->getOperand(1),
+ I->getName());
+ InsertNewInstBefore(Or, *I);
+ return UpdateValueUsesWith(I, Or);
+ }
+
+ // We can say something about the output known-zero and known-one bits,
+ // depending on potential carries from the input constant and the
+ // unknowns. For example if the LHS is known to have at most the 0x0F0F0
+ // bits set and the RHS constant is 0x01001, then we know we have a known
+ // one mask of 0x00001 and a known zero mask of 0xE0F0E.
+
+ // To compute this, we first compute the potential carry bits. These are
+ // the bits which may be modified. I'm not aware of a better way to do
+ // this scan.
+ const APInt& RHSVal = RHS->getValue();
+ APInt CarryBits((~LHSKnownZero + RHSVal) ^ (~LHSKnownZero ^ RHSVal));
+
+ // Now that we know which bits have carries, compute the known-1/0 sets.
+
+ // Bits are known one if they are known zero in one operand and one in the
+ // other, and there is no input carry.
+ RHSKnownOne = ((LHSKnownZero & RHSVal) |
+ (LHSKnownOne & ~RHSVal)) & ~CarryBits;
+
+ // Bits are known zero if they are known zero in both operands and there
+ // is no input carry.
+ RHSKnownZero = LHSKnownZero & ~RHSVal & ~CarryBits;
+ } else {
+ // If the high-bits of this ADD are not demanded, then it does not demand
+ // the high bits of its LHS or RHS.
+ if (DemandedMask[BitWidth-1] == 0) {
+ // Right fill the mask of bits for this ADD to demand the most
+ // significant bit and all those below it.
+ APInt DemandedFromOps(APInt::getLowBitsSet(BitWidth, BitWidth-NLZ));
+ if (SimplifyDemandedBits(I->getOperand(0), DemandedFromOps,
+ LHSKnownZero, LHSKnownOne, Depth+1))
+ return true;
+ if (SimplifyDemandedBits(I->getOperand(1), DemandedFromOps,
+ LHSKnownZero, LHSKnownOne, Depth+1))
+ return true;
+ }
+ }
+ break;
+ }
+ case Instruction::Sub:
+ // If the high-bits of this SUB are not demanded, then it does not demand
+ // the high bits of its LHS or RHS.
+ if (DemandedMask[BitWidth-1] == 0) {
+ // Right fill the mask of bits for this SUB to demand the most
+ // significant bit and all those below it.
+ uint32_t NLZ = DemandedMask.countLeadingZeros();
+ APInt DemandedFromOps(APInt::getLowBitsSet(BitWidth, BitWidth-NLZ));
+ if (SimplifyDemandedBits(I->getOperand(0), DemandedFromOps,
+ LHSKnownZero, LHSKnownOne, Depth+1))
+ return true;
+ if (SimplifyDemandedBits(I->getOperand(1), DemandedFromOps,
+ LHSKnownZero, LHSKnownOne, Depth+1))
+ return true;
+ }
+ break;
+ case Instruction::Shl:
+ if (ConstantInt *SA = dyn_cast<ConstantInt>(I->getOperand(1))) {
+ uint64_t ShiftAmt = SA->getLimitedValue(BitWidth);
+ APInt DemandedMaskIn(DemandedMask.lshr(ShiftAmt));
+ if (SimplifyDemandedBits(I->getOperand(0), DemandedMaskIn,
+ RHSKnownZero, RHSKnownOne, Depth+1))
+ return true;
+ assert((RHSKnownZero & RHSKnownOne) == 0 &&
+ "Bits known to be one AND zero?");
+ RHSKnownZero <<= ShiftAmt;
+ RHSKnownOne <<= ShiftAmt;
+ // low bits known zero.
+ if (ShiftAmt)
+ RHSKnownZero |= APInt::getLowBitsSet(BitWidth, ShiftAmt);
+ }
+ break;
+ case Instruction::LShr:
+ // For a logical shift right
+ if (ConstantInt *SA = dyn_cast<ConstantInt>(I->getOperand(1))) {
+ uint64_t ShiftAmt = SA->getLimitedValue(BitWidth);
+
+ // Unsigned shift right.
+ APInt DemandedMaskIn(DemandedMask.shl(ShiftAmt));
+ if (SimplifyDemandedBits(I->getOperand(0), DemandedMaskIn,
+ RHSKnownZero, RHSKnownOne, Depth+1))
+ return true;
+ assert((RHSKnownZero & RHSKnownOne) == 0 &&
+ "Bits known to be one AND zero?");
+ RHSKnownZero = APIntOps::lshr(RHSKnownZero, ShiftAmt);
+ RHSKnownOne = APIntOps::lshr(RHSKnownOne, ShiftAmt);
+ if (ShiftAmt) {
+ // Compute the new bits that are at the top now.
+ APInt HighBits(APInt::getHighBitsSet(BitWidth, ShiftAmt));
+ RHSKnownZero |= HighBits; // high bits known zero.
+ }
+ }
+ break;
+ case Instruction::AShr:
+ // If this is an arithmetic shift right and only the low-bit is set, we can
+ // always convert this into a logical shr, even if the shift amount is
+ // variable. The low bit of the shift cannot be an input sign bit unless
+ // the shift amount is >= the size of the datatype, which is undefined.
+ if (DemandedMask == 1) {
+ // Perform the logical shift right.
+ Value *NewVal = BinaryOperator::createLShr(
+ I->getOperand(0), I->getOperand(1), I->getName());
+ InsertNewInstBefore(cast<Instruction>(NewVal), *I);
+ return UpdateValueUsesWith(I, NewVal);
+ }
+
+ // If the sign bit is the only bit demanded by this ashr, then there is no
+ // need to do it, the shift doesn't change the high bit.
+ if (DemandedMask.isSignBit())
+ return UpdateValueUsesWith(I, I->getOperand(0));
+
+ if (ConstantInt *SA = dyn_cast<ConstantInt>(I->getOperand(1))) {
+ uint32_t ShiftAmt = SA->getLimitedValue(BitWidth);
+
+ // Signed shift right.
+ APInt DemandedMaskIn(DemandedMask.shl(ShiftAmt));
+ // If any of the "high bits" are demanded, we should set the sign bit as
+ // demanded.
+ if (DemandedMask.countLeadingZeros() <= ShiftAmt)
+ DemandedMaskIn.set(BitWidth-1);
+ if (SimplifyDemandedBits(I->getOperand(0),
+ DemandedMaskIn,
+ RHSKnownZero, RHSKnownOne, Depth+1))
+ return true;
+ assert((RHSKnownZero & RHSKnownOne) == 0 &&
+ "Bits known to be one AND zero?");
+ // Compute the new bits that are at the top now.
+ APInt HighBits(APInt::getHighBitsSet(BitWidth, ShiftAmt));
+ RHSKnownZero = APIntOps::lshr(RHSKnownZero, ShiftAmt);
+ RHSKnownOne = APIntOps::lshr(RHSKnownOne, ShiftAmt);
+
+ // Handle the sign bits.
+ APInt SignBit(APInt::getSignBit(BitWidth));
+ // Adjust to where it is now in the mask.
+ SignBit = APIntOps::lshr(SignBit, ShiftAmt);
+
+ // If the input sign bit is known to be zero, or if none of the top bits
+ // are demanded, turn this into an unsigned shift right.
+ if (RHSKnownZero[BitWidth-ShiftAmt-1] ||
+ (HighBits & ~DemandedMask) == HighBits) {
+ // Perform the logical shift right.
+ Value *NewVal = BinaryOperator::createLShr(
+ I->getOperand(0), SA, I->getName());
+ InsertNewInstBefore(cast<Instruction>(NewVal), *I);
+ return UpdateValueUsesWith(I, NewVal);
+ } else if ((RHSKnownOne & SignBit) != 0) { // New bits are known one.
+ RHSKnownOne |= HighBits;
+ }
+ }
+ break;
+ }
+
+ // If the client is only demanding bits that we know, return the known
+ // constant.
+ if ((DemandedMask & (RHSKnownZero|RHSKnownOne)) == DemandedMask)
+ return UpdateValueUsesWith(I, ConstantInt::get(RHSKnownOne));
+ return false;
+}
+
+
+/// SimplifyDemandedVectorElts - The specified value producecs a vector with
+/// 64 or fewer elements. DemandedElts contains the set of elements that are
+/// actually used by the caller. This method analyzes which elements of the
+/// operand are undef and returns that information in UndefElts.
+///
+/// If the information about demanded elements can be used to simplify the
+/// operation, the operation is simplified, then the resultant value is
+/// returned. This returns null if no change was made.
+Value *InstCombiner::SimplifyDemandedVectorElts(Value *V, uint64_t DemandedElts,
+ uint64_t &UndefElts,
+ unsigned Depth) {
+ unsigned VWidth = cast<VectorType>(V->getType())->getNumElements();
+ assert(VWidth <= 64 && "Vector too wide to analyze!");
+ uint64_t EltMask = ~0ULL >> (64-VWidth);
+ assert(DemandedElts != EltMask && (DemandedElts & ~EltMask) == 0 &&
+ "Invalid DemandedElts!");
+
+ if (isa<UndefValue>(V)) {
+ // If the entire vector is undefined, just return this info.
+ UndefElts = EltMask;
+ return 0;
+ } else if (DemandedElts == 0) { // If nothing is demanded, provide undef.
+ UndefElts = EltMask;
+ return UndefValue::get(V->getType());
+ }
+
+ UndefElts = 0;
+ if (ConstantVector *CP = dyn_cast<ConstantVector>(V)) {
+ const Type *EltTy = cast<VectorType>(V->getType())->getElementType();
+ Constant *Undef = UndefValue::get(EltTy);
+
+ std::vector<Constant*> Elts;
+ for (unsigned i = 0; i != VWidth; ++i)
+ if (!(DemandedElts & (1ULL << i))) { // If not demanded, set to undef.
+ Elts.push_back(Undef);
+ UndefElts |= (1ULL << i);
+ } else if (isa<UndefValue>(CP->getOperand(i))) { // Already undef.
+ Elts.push_back(Undef);
+ UndefElts |= (1ULL << i);
+ } else { // Otherwise, defined.
+ Elts.push_back(CP->getOperand(i));
+ }
+
+ // If we changed the constant, return it.
+ Constant *NewCP = ConstantVector::get(Elts);
+ return NewCP != CP ? NewCP : 0;
+ } else if (isa<ConstantAggregateZero>(V)) {
+ // Simplify the CAZ to a ConstantVector where the non-demanded elements are
+ // set to undef.
+ const Type *EltTy = cast<VectorType>(V->getType())->getElementType();
+ Constant *Zero = Constant::getNullValue(EltTy);
+ Constant *Undef = UndefValue::get(EltTy);
+ std::vector<Constant*> Elts;
+ for (unsigned i = 0; i != VWidth; ++i)
+ Elts.push_back((DemandedElts & (1ULL << i)) ? Zero : Undef);
+ UndefElts = DemandedElts ^ EltMask;
+ return ConstantVector::get(Elts);
+ }
+
+ if (!V->hasOneUse()) { // Other users may use these bits.
+ if (Depth != 0) { // Not at the root.
+ // TODO: Just compute the UndefElts information recursively.
+ return false;
+ }
+ return false;
+ } else if (Depth == 10) { // Limit search depth.
+ return false;
+ }
+
+ Instruction *I = dyn_cast<Instruction>(V);
+ if (!I) return false; // Only analyze instructions.
+
+ bool MadeChange = false;
+ uint64_t UndefElts2;
+ Value *TmpV;
+ switch (I->getOpcode()) {
+ default: break;
+
+ case Instruction::InsertElement: {
+ // If this is a variable index, we don't know which element it overwrites.
+ // demand exactly the same input as we produce.
+ ConstantInt *Idx = dyn_cast<ConstantInt>(I->getOperand(2));
+ if (Idx == 0) {
+ // Note that we can't propagate undef elt info, because we don't know
+ // which elt is getting updated.
+ TmpV = SimplifyDemandedVectorElts(I->getOperand(0), DemandedElts,
+ UndefElts2, Depth+1);
+ if (TmpV) { I->setOperand(0, TmpV); MadeChange = true; }
+ break;
+ }
+
+ // If this is inserting an element that isn't demanded, remove this
+ // insertelement.
+ unsigned IdxNo = Idx->getZExtValue();
+ if (IdxNo >= VWidth || (DemandedElts & (1ULL << IdxNo)) == 0)
+ return AddSoonDeadInstToWorklist(*I, 0);
+
+ // Otherwise, the element inserted overwrites whatever was there, so the
+ // input demanded set is simpler than the output set.
+ TmpV = SimplifyDemandedVectorElts(I->getOperand(0),
+ DemandedElts & ~(1ULL << IdxNo),
+ UndefElts, Depth+1);
+ if (TmpV) { I->setOperand(0, TmpV); MadeChange = true; }
+
+ // The inserted element is defined.
+ UndefElts |= 1ULL << IdxNo;
+ break;
+ }
+ case Instruction::BitCast: {
+ // Vector->vector casts only.
+ const VectorType *VTy = dyn_cast<VectorType>(I->getOperand(0)->getType());
+ if (!VTy) break;
+ unsigned InVWidth = VTy->getNumElements();
+ uint64_t InputDemandedElts = 0;
+ unsigned Ratio;
+
+ if (VWidth == InVWidth) {
+ // If we are converting from <4 x i32> -> <4 x f32>, we demand the same
+ // elements as are demanded of us.
+ Ratio = 1;
+ InputDemandedElts = DemandedElts;
+ } else if (VWidth > InVWidth) {
+ // Untested so far.
+ break;
+
+ // If there are more elements in the result than there are in the source,
+ // then an input element is live if any of the corresponding output
+ // elements are live.
+ Ratio = VWidth/InVWidth;
+ for (unsigned OutIdx = 0; OutIdx != VWidth; ++OutIdx) {
+ if (DemandedElts & (1ULL << OutIdx))
+ InputDemandedElts |= 1ULL << (OutIdx/Ratio);
+ }
+ } else {
+ // Untested so far.
+ break;
+
+ // If there are more elements in the source than there are in the result,
+ // then an input element is live if the corresponding output element is
+ // live.
+ Ratio = InVWidth/VWidth;
+ for (unsigned InIdx = 0; InIdx != InVWidth; ++InIdx)
+ if (DemandedElts & (1ULL << InIdx/Ratio))
+ InputDemandedElts |= 1ULL << InIdx;
+ }
+
+ // div/rem demand all inputs, because they don't want divide by zero.
+ TmpV = SimplifyDemandedVectorElts(I->getOperand(0), InputDemandedElts,
+ UndefElts2, Depth+1);
+ if (TmpV) {
+ I->setOperand(0, TmpV);
+ MadeChange = true;
+ }
+
+ UndefElts = UndefElts2;
+ if (VWidth > InVWidth) {
+ assert(0 && "Unimp");
+ // If there are more elements in the result than there are in the source,
+ // then an output element is undef if the corresponding input element is
+ // undef.
+ for (unsigned OutIdx = 0; OutIdx != VWidth; ++OutIdx)
+ if (UndefElts2 & (1ULL << (OutIdx/Ratio)))
+ UndefElts |= 1ULL << OutIdx;
+ } else if (VWidth < InVWidth) {
+ assert(0 && "Unimp");
+ // If there are more elements in the source than there are in the result,
+ // then a result element is undef if all of the corresponding input
+ // elements are undef.
+ UndefElts = ~0ULL >> (64-VWidth); // Start out all undef.
+ for (unsigned InIdx = 0; InIdx != InVWidth; ++InIdx)
+ if ((UndefElts2 & (1ULL << InIdx)) == 0) // Not undef?
+ UndefElts &= ~(1ULL << (InIdx/Ratio)); // Clear undef bit.
+ }
+ break;
+ }
+ case Instruction::And:
+ case Instruction::Or:
+ case Instruction::Xor:
+ case Instruction::Add:
+ case Instruction::Sub:
+ case Instruction::Mul:
+ // div/rem demand all inputs, because they don't want divide by zero.
+ TmpV = SimplifyDemandedVectorElts(I->getOperand(0), DemandedElts,
+ UndefElts, Depth+1);
+ if (TmpV) { I->setOperand(0, TmpV); MadeChange = true; }
+ TmpV = SimplifyDemandedVectorElts(I->getOperand(1), DemandedElts,
+ UndefElts2, Depth+1);
+ if (TmpV) { I->setOperand(1, TmpV); MadeChange = true; }
+
+ // Output elements are undefined if both are undefined. Consider things
+ // like undef&0. The result is known zero, not undef.
+ UndefElts &= UndefElts2;
+ break;
+
+ case Instruction::Call: {
+ IntrinsicInst *II = dyn_cast<IntrinsicInst>(I);
+ if (!II) break;
+ switch (II->getIntrinsicID()) {
+ default: break;
+
+ // Binary vector operations that work column-wise. A dest element is a
+ // function of the corresponding input elements from the two inputs.
+ case Intrinsic::x86_sse_sub_ss:
+ case Intrinsic::x86_sse_mul_ss:
+ case Intrinsic::x86_sse_min_ss:
+ case Intrinsic::x86_sse_max_ss:
+ case Intrinsic::x86_sse2_sub_sd:
+ case Intrinsic::x86_sse2_mul_sd:
+ case Intrinsic::x86_sse2_min_sd:
+ case Intrinsic::x86_sse2_max_sd:
+ TmpV = SimplifyDemandedVectorElts(II->getOperand(1), DemandedElts,
+ UndefElts, Depth+1);
+ if (TmpV) { II->setOperand(1, TmpV); MadeChange = true; }
+ TmpV = SimplifyDemandedVectorElts(II->getOperand(2), DemandedElts,
+ UndefElts2, Depth+1);
+ if (TmpV) { II->setOperand(2, TmpV); MadeChange = true; }
+
+ // If only the low elt is demanded and this is a scalarizable intrinsic,
+ // scalarize it now.
+ if (DemandedElts == 1) {
+ switch (II->getIntrinsicID()) {
+ default: break;
+ case Intrinsic::x86_sse_sub_ss:
+ case Intrinsic::x86_sse_mul_ss:
+ case Intrinsic::x86_sse2_sub_sd:
+ case Intrinsic::x86_sse2_mul_sd:
+ // TODO: Lower MIN/MAX/ABS/etc
+ Value *LHS = II->getOperand(1);
+ Value *RHS = II->getOperand(2);
+ // Extract the element as scalars.
+ LHS = InsertNewInstBefore(new ExtractElementInst(LHS, 0U,"tmp"), *II);
+ RHS = InsertNewInstBefore(new ExtractElementInst(RHS, 0U,"tmp"), *II);
+
+ switch (II->getIntrinsicID()) {
+ default: assert(0 && "Case stmts out of sync!");
+ case Intrinsic::x86_sse_sub_ss:
+ case Intrinsic::x86_sse2_sub_sd:
+ TmpV = InsertNewInstBefore(BinaryOperator::createSub(LHS, RHS,
+ II->getName()), *II);
+ break;
+ case Intrinsic::x86_sse_mul_ss:
+ case Intrinsic::x86_sse2_mul_sd:
+ TmpV = InsertNewInstBefore(BinaryOperator::createMul(LHS, RHS,
+ II->getName()), *II);
+ break;
+ }
+
+ Instruction *New =
+ new InsertElementInst(UndefValue::get(II->getType()), TmpV, 0U,
+ II->getName());
+ InsertNewInstBefore(New, *II);
+ AddSoonDeadInstToWorklist(*II, 0);
+ return New;
+ }
+ }
+
+ // Output elements are undefined if both are undefined. Consider things
+ // like undef&0. The result is known zero, not undef.
+ UndefElts &= UndefElts2;
+ break;
+ }
+ break;
+ }
+ }
+ return MadeChange ? I : 0;
+}
+
+/// @returns true if the specified compare instruction is
+/// true when both operands are equal...
+/// @brief Determine if the ICmpInst returns true if both operands are equal
+static bool isTrueWhenEqual(ICmpInst &ICI) {
+ ICmpInst::Predicate pred = ICI.getPredicate();
+ return pred == ICmpInst::ICMP_EQ || pred == ICmpInst::ICMP_UGE ||
+ pred == ICmpInst::ICMP_SGE || pred == ICmpInst::ICMP_ULE ||
+ pred == ICmpInst::ICMP_SLE;
+}
+
+/// AssociativeOpt - Perform an optimization on an associative operator. This
+/// function is designed to check a chain of associative operators for a
+/// potential to apply a certain optimization. Since the optimization may be
+/// applicable if the expression was reassociated, this checks the chain, then
+/// reassociates the expression as necessary to expose the optimization
+/// opportunity. This makes use of a special Functor, which must define
+/// 'shouldApply' and 'apply' methods.
+///
+template<typename Functor>
+Instruction *AssociativeOpt(BinaryOperator &Root, const Functor &F) {
+ unsigned Opcode = Root.getOpcode();
+ Value *LHS = Root.getOperand(0);
+
+ // Quick check, see if the immediate LHS matches...
+ if (F.shouldApply(LHS))
+ return F.apply(Root);
+
+ // Otherwise, if the LHS is not of the same opcode as the root, return.
+ Instruction *LHSI = dyn_cast<Instruction>(LHS);
+ while (LHSI && LHSI->getOpcode() == Opcode && LHSI->hasOneUse()) {
+ // Should we apply this transform to the RHS?
+ bool ShouldApply = F.shouldApply(LHSI->getOperand(1));
+
+ // If not to the RHS, check to see if we should apply to the LHS...
+ if (!ShouldApply && F.shouldApply(LHSI->getOperand(0))) {
+ cast<BinaryOperator>(LHSI)->swapOperands(); // Make the LHS the RHS
+ ShouldApply = true;
+ }
+
+ // If the functor wants to apply the optimization to the RHS of LHSI,
+ // reassociate the expression from ((? op A) op B) to (? op (A op B))
+ if (ShouldApply) {
+ BasicBlock *BB = Root.getParent();
+
+ // Now all of the instructions are in the current basic block, go ahead
+ // and perform the reassociation.
+ Instruction *TmpLHSI = cast<Instruction>(Root.getOperand(0));
+
+ // First move the selected RHS to the LHS of the root...
+ Root.setOperand(0, LHSI->getOperand(1));
+
+ // Make what used to be the LHS of the root be the user of the root...
+ Value *ExtraOperand = TmpLHSI->getOperand(1);
+ if (&Root == TmpLHSI) {
+ Root.replaceAllUsesWith(Constant::getNullValue(TmpLHSI->getType()));
+ return 0;
+ }
+ Root.replaceAllUsesWith(TmpLHSI); // Users now use TmpLHSI
+ TmpLHSI->setOperand(1, &Root); // TmpLHSI now uses the root
+ TmpLHSI->getParent()->getInstList().remove(TmpLHSI);
+ BasicBlock::iterator ARI = &Root; ++ARI;
+ BB->getInstList().insert(ARI, TmpLHSI); // Move TmpLHSI to after Root
+ ARI = Root;
+
+ // Now propagate the ExtraOperand down the chain of instructions until we
+ // get to LHSI.
+ while (TmpLHSI != LHSI) {
+ Instruction *NextLHSI = cast<Instruction>(TmpLHSI->getOperand(0));
+ // Move the instruction to immediately before the chain we are
+ // constructing to avoid breaking dominance properties.
+ NextLHSI->getParent()->getInstList().remove(NextLHSI);
+ BB->getInstList().insert(ARI, NextLHSI);
+ ARI = NextLHSI;
+
+ Value *NextOp = NextLHSI->getOperand(1);
+ NextLHSI->setOperand(1, ExtraOperand);
+ TmpLHSI = NextLHSI;
+ ExtraOperand = NextOp;
+ }
+
+ // Now that the instructions are reassociated, have the functor perform
+ // the transformation...
+ return F.apply(Root);
+ }
+
+ LHSI = dyn_cast<Instruction>(LHSI->getOperand(0));
+ }
+ return 0;
+}
+
+
+// AddRHS - Implements: X + X --> X << 1
+struct AddRHS {
+ Value *RHS;
+ AddRHS(Value *rhs) : RHS(rhs) {}
+ bool shouldApply(Value *LHS) const { return LHS == RHS; }
+ Instruction *apply(BinaryOperator &Add) const {
+ return BinaryOperator::createShl(Add.getOperand(0),
+ ConstantInt::get(Add.getType(), 1));
+ }
+};
+
+// AddMaskingAnd - Implements (A & C1)+(B & C2) --> (A & C1)|(B & C2)
+// iff C1&C2 == 0
+struct AddMaskingAnd {
+ Constant *C2;
+ AddMaskingAnd(Constant *c) : C2(c) {}
+ bool shouldApply(Value *LHS) const {
+ ConstantInt *C1;
+ return match(LHS, m_And(m_Value(), m_ConstantInt(C1))) &&
+ ConstantExpr::getAnd(C1, C2)->isNullValue();
+ }
+ Instruction *apply(BinaryOperator &Add) const {
+ return BinaryOperator::createOr(Add.getOperand(0), Add.getOperand(1));
+ }
+};
+
+static Value *FoldOperationIntoSelectOperand(Instruction &I, Value *SO,
+ InstCombiner *IC) {
+ if (CastInst *CI = dyn_cast<CastInst>(&I)) {
+ if (Constant *SOC = dyn_cast<Constant>(SO))
+ return ConstantExpr::getCast(CI->getOpcode(), SOC, I.getType());
+
+ return IC->InsertNewInstBefore(CastInst::create(
+ CI->getOpcode(), SO, I.getType(), SO->getName() + ".cast"), I);
+ }
+
+ // Figure out if the constant is the left or the right argument.
+ bool ConstIsRHS = isa<Constant>(I.getOperand(1));
+ Constant *ConstOperand = cast<Constant>(I.getOperand(ConstIsRHS));
+
+ if (Constant *SOC = dyn_cast<Constant>(SO)) {
+ if (ConstIsRHS)
+ return ConstantExpr::get(I.getOpcode(), SOC, ConstOperand);
+ return ConstantExpr::get(I.getOpcode(), ConstOperand, SOC);
+ }
+
+ Value *Op0 = SO, *Op1 = ConstOperand;
+ if (!ConstIsRHS)
+ std::swap(Op0, Op1);
+ Instruction *New;
+ if (BinaryOperator *BO = dyn_cast<BinaryOperator>(&I))
+ New = BinaryOperator::create(BO->getOpcode(), Op0, Op1,SO->getName()+".op");
+ else if (CmpInst *CI = dyn_cast<CmpInst>(&I))
+ New = CmpInst::create(CI->getOpcode(), CI->getPredicate(), Op0, Op1,
+ SO->getName()+".cmp");
+ else {
+ assert(0 && "Unknown binary instruction type!");
+ abort();
+ }
+ return IC->InsertNewInstBefore(New, I);
+}
+
+// FoldOpIntoSelect - Given an instruction with a select as one operand and a
+// constant as the other operand, try to fold the binary operator into the
+// select arguments. This also works for Cast instructions, which obviously do
+// not have a second operand.
+static Instruction *FoldOpIntoSelect(Instruction &Op, SelectInst *SI,
+ InstCombiner *IC) {
+ // Don't modify shared select instructions
+ if (!SI->hasOneUse()) return 0;
+ Value *TV = SI->getOperand(1);
+ Value *FV = SI->getOperand(2);
+
+ if (isa<Constant>(TV) || isa<Constant>(FV)) {
+ // Bool selects with constant operands can be folded to logical ops.
+ if (SI->getType() == Type::Int1Ty) return 0;
+
+ Value *SelectTrueVal = FoldOperationIntoSelectOperand(Op, TV, IC);
+ Value *SelectFalseVal = FoldOperationIntoSelectOperand(Op, FV, IC);
+
+ return new SelectInst(SI->getCondition(), SelectTrueVal,
+ SelectFalseVal);
+ }
+ return 0;
+}
+
+
+/// FoldOpIntoPhi - Given a binary operator or cast instruction which has a PHI
+/// node as operand #0, see if we can fold the instruction into the PHI (which
+/// is only possible if all operands to the PHI are constants).
+Instruction *InstCombiner::FoldOpIntoPhi(Instruction &I) {
+ PHINode *PN = cast<PHINode>(I.getOperand(0));
+ unsigned NumPHIValues = PN->getNumIncomingValues();
+ if (!PN->hasOneUse() || NumPHIValues == 0) return 0;
+
+ // Check to see if all of the operands of the PHI are constants. If there is
+ // one non-constant value, remember the BB it is. If there is more than one
+ // or if *it* is a PHI, bail out.
+ BasicBlock *NonConstBB = 0;
+ for (unsigned i = 0; i != NumPHIValues; ++i)
+ if (!isa<Constant>(PN->getIncomingValue(i))) {
+ if (NonConstBB) return 0; // More than one non-const value.
+ if (isa<PHINode>(PN->getIncomingValue(i))) return 0; // Itself a phi.
+ NonConstBB = PN->getIncomingBlock(i);
+
+ // If the incoming non-constant value is in I's block, we have an infinite
+ // loop.
+ if (NonConstBB == I.getParent())
+ return 0;
+ }
+
+ // If there is exactly one non-constant value, we can insert a copy of the
+ // operation in that block. However, if this is a critical edge, we would be
+ // inserting the computation one some other paths (e.g. inside a loop). Only
+ // do this if the pred block is unconditionally branching into the phi block.
+ if (NonConstBB) {
+ BranchInst *BI = dyn_cast<BranchInst>(NonConstBB->getTerminator());
+ if (!BI || !BI->isUnconditional()) return 0;
+ }
+
+ // Okay, we can do the transformation: create the new PHI node.
+ PHINode *NewPN = new PHINode(I.getType(), "");
+ NewPN->reserveOperandSpace(PN->getNumOperands()/2);
+ InsertNewInstBefore(NewPN, *PN);
+ NewPN->takeName(PN);
+
+ // Next, add all of the operands to the PHI.
+ if (I.getNumOperands() == 2) {
+ Constant *C = cast<Constant>(I.getOperand(1));
+ for (unsigned i = 0; i != NumPHIValues; ++i) {
+ Value *InV;
+ if (Constant *InC = dyn_cast<Constant>(PN->getIncomingValue(i))) {
+ if (CmpInst *CI = dyn_cast<CmpInst>(&I))
+ InV = ConstantExpr::getCompare(CI->getPredicate(), InC, C);
+ else
+ InV = ConstantExpr::get(I.getOpcode(), InC, C);
+ } else {
+ assert(PN->getIncomingBlock(i) == NonConstBB);
+ if (BinaryOperator *BO = dyn_cast<BinaryOperator>(&I))
+ InV = BinaryOperator::create(BO->getOpcode(),
+ PN->getIncomingValue(i), C, "phitmp",
+ NonConstBB->getTerminator());
+ else if (CmpInst *CI = dyn_cast<CmpInst>(&I))
+ InV = CmpInst::create(CI->getOpcode(),
+ CI->getPredicate(),
+ PN->getIncomingValue(i), C, "phitmp",
+ NonConstBB->getTerminator());
+ else
+ assert(0 && "Unknown binop!");
+
+ AddToWorkList(cast<Instruction>(InV));
+ }
+ NewPN->addIncoming(InV, PN->getIncomingBlock(i));
+ }
+ } else {
+ CastInst *CI = cast<CastInst>(&I);
+ const Type *RetTy = CI->getType();
+ for (unsigned i = 0; i != NumPHIValues; ++i) {
+ Value *InV;
+ if (Constant *InC = dyn_cast<Constant>(PN->getIncomingValue(i))) {
+ InV = ConstantExpr::getCast(CI->getOpcode(), InC, RetTy);
+ } else {
+ assert(PN->getIncomingBlock(i) == NonConstBB);
+ InV = CastInst::create(CI->getOpcode(), PN->getIncomingValue(i),
+ I.getType(), "phitmp",
+ NonConstBB->getTerminator());
+ AddToWorkList(cast<Instruction>(InV));
+ }
+ NewPN->addIncoming(InV, PN->getIncomingBlock(i));
+ }
+ }
+ return ReplaceInstUsesWith(I, NewPN);
+}
+
+Instruction *InstCombiner::visitAdd(BinaryOperator &I) {
+ bool Changed = SimplifyCommutative(I);
+ Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
+
+ if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
+ // X + undef -> undef
+ if (isa<UndefValue>(RHS))
+ return ReplaceInstUsesWith(I, RHS);
+
+ // X + 0 --> X
+ if (!I.getType()->isFPOrFPVector()) { // NOTE: -0 + +0 = +0.
+ if (RHSC->isNullValue())
+ return ReplaceInstUsesWith(I, LHS);
+ } else if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHSC)) {
+ if (CFP->isExactlyValue(-0.0))
+ return ReplaceInstUsesWith(I, LHS);
+ }
+
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(RHSC)) {
+ // X + (signbit) --> X ^ signbit
+ const APInt& Val = CI->getValue();
+ uint32_t BitWidth = Val.getBitWidth();
+ if (Val == APInt::getSignBit(BitWidth))
+ return BinaryOperator::createXor(LHS, RHS);
+
+ // See if SimplifyDemandedBits can simplify this. This handles stuff like
+ // (X & 254)+1 -> (X&254)|1
+ if (!isa<VectorType>(I.getType())) {
+ APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
+ if (SimplifyDemandedBits(&I, APInt::getAllOnesValue(BitWidth),
+ KnownZero, KnownOne))
+ return &I;
+ }
+ }
+
+ if (isa<PHINode>(LHS))
+ if (Instruction *NV = FoldOpIntoPhi(I))
+ return NV;
+
+ ConstantInt *XorRHS = 0;
+ Value *XorLHS = 0;
+ if (isa<ConstantInt>(RHSC) &&
+ match(LHS, m_Xor(m_Value(XorLHS), m_ConstantInt(XorRHS)))) {
+ uint32_t TySizeBits = I.getType()->getPrimitiveSizeInBits();
+ const APInt& RHSVal = cast<ConstantInt>(RHSC)->getValue();
+
+ uint32_t Size = TySizeBits / 2;
+ APInt C0080Val(APInt(TySizeBits, 1ULL).shl(Size - 1));
+ APInt CFF80Val(-C0080Val);
+ do {
+ if (TySizeBits > Size) {
+ // If we have ADD(XOR(AND(X, 0xFF), 0x80), 0xF..F80), it's a sext.
+ // If we have ADD(XOR(AND(X, 0xFF), 0xF..F80), 0x80), it's a sext.
+ if ((RHSVal == CFF80Val && XorRHS->getValue() == C0080Val) ||
+ (RHSVal == C0080Val && XorRHS->getValue() == CFF80Val)) {
+ // This is a sign extend if the top bits are known zero.
+ if (!MaskedValueIsZero(XorLHS,
+ APInt::getHighBitsSet(TySizeBits, TySizeBits - Size)))
+ Size = 0; // Not a sign ext, but can't be any others either.
+ break;
+ }
+ }
+ Size >>= 1;
+ C0080Val = APIntOps::lshr(C0080Val, Size);
+ CFF80Val = APIntOps::ashr(CFF80Val, Size);
+ } while (Size >= 1);
+
+ // FIXME: This shouldn't be necessary. When the backends can handle types
+ // with funny bit widths then this whole cascade of if statements should
+ // be removed. It is just here to get the size of the "middle" type back
+ // up to something that the back ends can handle.
+ const Type *MiddleType = 0;
+ switch (Size) {
+ default: break;
+ case 32: MiddleType = Type::Int32Ty; break;
+ case 16: MiddleType = Type::Int16Ty; break;
+ case 8: MiddleType = Type::Int8Ty; break;
+ }
+ if (MiddleType) {
+ Instruction *NewTrunc = new TruncInst(XorLHS, MiddleType, "sext");
+ InsertNewInstBefore(NewTrunc, I);
+ return new SExtInst(NewTrunc, I.getType(), I.getName());
+ }
+ }
+ }
+
+ // X + X --> X << 1
+ if (I.getType()->isInteger() && I.getType() != Type::Int1Ty) {
+ if (Instruction *Result = AssociativeOpt(I, AddRHS(RHS))) return Result;
+
+ if (Instruction *RHSI = dyn_cast<Instruction>(RHS)) {
+ if (RHSI->getOpcode() == Instruction::Sub)
+ if (LHS == RHSI->getOperand(1)) // A + (B - A) --> B
+ return ReplaceInstUsesWith(I, RHSI->getOperand(0));
+ }
+ if (Instruction *LHSI = dyn_cast<Instruction>(LHS)) {
+ if (LHSI->getOpcode() == Instruction::Sub)
+ if (RHS == LHSI->getOperand(1)) // (B - A) + A --> B
+ return ReplaceInstUsesWith(I, LHSI->getOperand(0));
+ }
+ }
+
+ // -A + B --> B - A
+ if (Value *V = dyn_castNegVal(LHS))
+ return BinaryOperator::createSub(RHS, V);
+
+ // A + -B --> A - B
+ if (!isa<Constant>(RHS))
+ if (Value *V = dyn_castNegVal(RHS))
+ return BinaryOperator::createSub(LHS, V);
+
+
+ ConstantInt *C2;
+ if (Value *X = dyn_castFoldableMul(LHS, C2)) {
+ if (X == RHS) // X*C + X --> X * (C+1)
+ return BinaryOperator::createMul(RHS, AddOne(C2));
+
+ // X*C1 + X*C2 --> X * (C1+C2)
+ ConstantInt *C1;
+ if (X == dyn_castFoldableMul(RHS, C1))
+ return BinaryOperator::createMul(X, Add(C1, C2));
+ }
+
+ // X + X*C --> X * (C+1)
+ if (dyn_castFoldableMul(RHS, C2) == LHS)
+ return BinaryOperator::createMul(LHS, AddOne(C2));
+
+ // X + ~X --> -1 since ~X = -X-1
+ if (dyn_castNotVal(LHS) == RHS || dyn_castNotVal(RHS) == LHS)
+ return ReplaceInstUsesWith(I, Constant::getAllOnesValue(I.getType()));
+
+
+ // (A & C1)+(B & C2) --> (A & C1)|(B & C2) iff C1&C2 == 0
+ if (match(RHS, m_And(m_Value(), m_ConstantInt(C2))))
+ if (Instruction *R = AssociativeOpt(I, AddMaskingAnd(C2)))
+ return R;
+
+ if (ConstantInt *CRHS = dyn_cast<ConstantInt>(RHS)) {
+ Value *X = 0;
+ if (match(LHS, m_Not(m_Value(X)))) // ~X + C --> (C-1) - X
+ return BinaryOperator::createSub(SubOne(CRHS), X);
+
+ // (X & FF00) + xx00 -> (X+xx00) & FF00
+ if (LHS->hasOneUse() && match(LHS, m_And(m_Value(X), m_ConstantInt(C2)))) {
+ Constant *Anded = And(CRHS, C2);
+ if (Anded == CRHS) {
+ // See if all bits from the first bit set in the Add RHS up are included
+ // in the mask. First, get the rightmost bit.
+ const APInt& AddRHSV = CRHS->getValue();
+
+ // Form a mask of all bits from the lowest bit added through the top.
+ APInt AddRHSHighBits(~((AddRHSV & -AddRHSV)-1));
+
+ // See if the and mask includes all of these bits.
+ APInt AddRHSHighBitsAnd(AddRHSHighBits & C2->getValue());
+
+ if (AddRHSHighBits == AddRHSHighBitsAnd) {
+ // Okay, the xform is safe. Insert the new add pronto.
+ Value *NewAdd = InsertNewInstBefore(BinaryOperator::createAdd(X, CRHS,
+ LHS->getName()), I);
+ return BinaryOperator::createAnd(NewAdd, C2);
+ }
+ }
+ }
+
+ // Try to fold constant add into select arguments.
+ if (SelectInst *SI = dyn_cast<SelectInst>(LHS))
+ if (Instruction *R = FoldOpIntoSelect(I, SI, this))
+ return R;
+ }
+
+ // add (cast *A to intptrtype) B ->
+ // cast (GEP (cast *A to sbyte*) B) ->
+ // intptrtype
+ {
+ CastInst *CI = dyn_cast<CastInst>(LHS);
+ Value *Other = RHS;
+ if (!CI) {
+ CI = dyn_cast<CastInst>(RHS);
+ Other = LHS;
+ }
+ if (CI && CI->getType()->isSized() &&
+ (CI->getType()->getPrimitiveSizeInBits() ==
+ TD->getIntPtrType()->getPrimitiveSizeInBits())
+ && isa<PointerType>(CI->getOperand(0)->getType())) {
+ Value *I2 = InsertCastBefore(Instruction::BitCast, CI->getOperand(0),
+ PointerType::get(Type::Int8Ty), I);
+ I2 = InsertNewInstBefore(new GetElementPtrInst(I2, Other, "ctg2"), I);
+ return new PtrToIntInst(I2, CI->getType());
+ }
+ }
+
+ return Changed ? &I : 0;
+}
+
+// isSignBit - Return true if the value represented by the constant only has the
+// highest order bit set.
+static bool isSignBit(ConstantInt *CI) {
+ uint32_t NumBits = CI->getType()->getPrimitiveSizeInBits();
+ return CI->getValue() == APInt::getSignBit(NumBits);
+}
+
+Instruction *InstCombiner::visitSub(BinaryOperator &I) {
+ Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
+
+ if (Op0 == Op1) // sub X, X -> 0
+ return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
+
+ // If this is a 'B = x-(-A)', change to B = x+A...
+ if (Value *V = dyn_castNegVal(Op1))
+ return BinaryOperator::createAdd(Op0, V);
+
+ if (isa<UndefValue>(Op0))
+ return ReplaceInstUsesWith(I, Op0); // undef - X -> undef
+ if (isa<UndefValue>(Op1))
+ return ReplaceInstUsesWith(I, Op1); // X - undef -> undef
+
+ if (ConstantInt *C = dyn_cast<ConstantInt>(Op0)) {
+ // Replace (-1 - A) with (~A)...
+ if (C->isAllOnesValue())
+ return BinaryOperator::createNot(Op1);
+
+ // C - ~X == X + (1+C)
+ Value *X = 0;
+ if (match(Op1, m_Not(m_Value(X))))
+ return BinaryOperator::createAdd(X, AddOne(C));
+
+ // -(X >>u 31) -> (X >>s 31)
+ // -(X >>s 31) -> (X >>u 31)
+ if (C->isZero()) {
+ if (BinaryOperator *SI = dyn_cast<BinaryOperator>(Op1))
+ if (SI->getOpcode() == Instruction::LShr) {
+ if (ConstantInt *CU = dyn_cast<ConstantInt>(SI->getOperand(1))) {
+ // Check to see if we are shifting out everything but the sign bit.
+ if (CU->getLimitedValue(SI->getType()->getPrimitiveSizeInBits()) ==
+ SI->getType()->getPrimitiveSizeInBits()-1) {
+ // Ok, the transformation is safe. Insert AShr.
+ return BinaryOperator::create(Instruction::AShr,
+ SI->getOperand(0), CU, SI->getName());
+ }
+ }
+ }
+ else if (SI->getOpcode() == Instruction::AShr) {
+ if (ConstantInt *CU = dyn_cast<ConstantInt>(SI->getOperand(1))) {
+ // Check to see if we are shifting out everything but the sign bit.
+ if (CU->getLimitedValue(SI->getType()->getPrimitiveSizeInBits()) ==
+ SI->getType()->getPrimitiveSizeInBits()-1) {
+ // Ok, the transformation is safe. Insert LShr.
+ return BinaryOperator::createLShr(
+ SI->getOperand(0), CU, SI->getName());
+ }
+ }
+ }
+ }
+
+ // Try to fold constant sub into select arguments.
+ if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
+ if (Instruction *R = FoldOpIntoSelect(I, SI, this))
+ return R;
+
+ if (isa<PHINode>(Op0))
+ if (Instruction *NV = FoldOpIntoPhi(I))
+ return NV;
+ }
+
+ if (BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1)) {
+ if (Op1I->getOpcode() == Instruction::Add &&
+ !Op0->getType()->isFPOrFPVector()) {
+ if (Op1I->getOperand(0) == Op0) // X-(X+Y) == -Y
+ return BinaryOperator::createNeg(Op1I->getOperand(1), I.getName());
+ else if (Op1I->getOperand(1) == Op0) // X-(Y+X) == -Y
+ return BinaryOperator::createNeg(Op1I->getOperand(0), I.getName());
+ else if (ConstantInt *CI1 = dyn_cast<ConstantInt>(I.getOperand(0))) {
+ if (ConstantInt *CI2 = dyn_cast<ConstantInt>(Op1I->getOperand(1)))
+ // C1-(X+C2) --> (C1-C2)-X
+ return BinaryOperator::createSub(Subtract(CI1, CI2),
+ Op1I->getOperand(0));
+ }
+ }
+
+ if (Op1I->hasOneUse()) {
+ // Replace (x - (y - z)) with (x + (z - y)) if the (y - z) subexpression
+ // is not used by anyone else...
+ //
+ if (Op1I->getOpcode() == Instruction::Sub &&
+ !Op1I->getType()->isFPOrFPVector()) {
+ // Swap the two operands of the subexpr...
+ Value *IIOp0 = Op1I->getOperand(0), *IIOp1 = Op1I->getOperand(1);
+ Op1I->setOperand(0, IIOp1);
+ Op1I->setOperand(1, IIOp0);
+
+ // Create the new top level add instruction...
+ return BinaryOperator::createAdd(Op0, Op1);
+ }
+
+ // Replace (A - (A & B)) with (A & ~B) if this is the only use of (A&B)...
+ //
+ if (Op1I->getOpcode() == Instruction::And &&
+ (Op1I->getOperand(0) == Op0 || Op1I->getOperand(1) == Op0)) {
+ Value *OtherOp = Op1I->getOperand(Op1I->getOperand(0) == Op0);
+
+ Value *NewNot =
+ InsertNewInstBefore(BinaryOperator::createNot(OtherOp, "B.not"), I);
+ return BinaryOperator::createAnd(Op0, NewNot);
+ }
+
+ // 0 - (X sdiv C) -> (X sdiv -C)
+ if (Op1I->getOpcode() == Instruction::SDiv)
+ if (ConstantInt *CSI = dyn_cast<ConstantInt>(Op0))
+ if (CSI->isZero())
+ if (Constant *DivRHS = dyn_cast<Constant>(Op1I->getOperand(1)))
+ return BinaryOperator::createSDiv(Op1I->getOperand(0),
+ ConstantExpr::getNeg(DivRHS));
+
+ // X - X*C --> X * (1-C)
+ ConstantInt *C2 = 0;
+ if (dyn_castFoldableMul(Op1I, C2) == Op0) {
+ Constant *CP1 = Subtract(ConstantInt::get(I.getType(), 1), C2);
+ return BinaryOperator::createMul(Op0, CP1);
+ }
+ }
+ }
+
+ if (!Op0->getType()->isFPOrFPVector())
+ if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0))
+ if (Op0I->getOpcode() == Instruction::Add) {
+ if (Op0I->getOperand(0) == Op1) // (Y+X)-Y == X
+ return ReplaceInstUsesWith(I, Op0I->getOperand(1));
+ else if (Op0I->getOperand(1) == Op1) // (X+Y)-Y == X
+ return ReplaceInstUsesWith(I, Op0I->getOperand(0));
+ } else if (Op0I->getOpcode() == Instruction::Sub) {
+ if (Op0I->getOperand(0) == Op1) // (X-Y)-X == -Y
+ return BinaryOperator::createNeg(Op0I->getOperand(1), I.getName());
+ }
+
+ ConstantInt *C1;
+ if (Value *X = dyn_castFoldableMul(Op0, C1)) {
+ if (X == Op1) // X*C - X --> X * (C-1)
+ return BinaryOperator::createMul(Op1, SubOne(C1));
+
+ ConstantInt *C2; // X*C1 - X*C2 -> X * (C1-C2)
+ if (X == dyn_castFoldableMul(Op1, C2))
+ return BinaryOperator::createMul(Op1, Subtract(C1, C2));
+ }
+ return 0;
+}
+
+/// isSignBitCheck - Given an exploded icmp instruction, return true if the
+/// comparison only checks the sign bit. If it only checks the sign bit, set
+/// TrueIfSigned if the result of the comparison is true when the input value is
+/// signed.
+static bool isSignBitCheck(ICmpInst::Predicate pred, ConstantInt *RHS,
+ bool &TrueIfSigned) {
+ switch (pred) {
+ case ICmpInst::ICMP_SLT: // True if LHS s< 0
+ TrueIfSigned = true;
+ return RHS->isZero();
+ case ICmpInst::ICMP_SLE: // True if LHS s<= RHS and RHS == -1
+ TrueIfSigned = true;
+ return RHS->isAllOnesValue();
+ case ICmpInst::ICMP_SGT: // True if LHS s> -1
+ TrueIfSigned = false;
+ return RHS->isAllOnesValue();
+ case ICmpInst::ICMP_UGT:
+ // True if LHS u> RHS and RHS == high-bit-mask - 1
+ TrueIfSigned = true;
+ return RHS->getValue() ==
+ APInt::getSignedMaxValue(RHS->getType()->getPrimitiveSizeInBits());
+ case ICmpInst::ICMP_UGE:
+ // True if LHS u>= RHS and RHS == high-bit-mask (2^7, 2^15, 2^31, etc)
+ TrueIfSigned = true;
+ return RHS->getValue() ==
+ APInt::getSignBit(RHS->getType()->getPrimitiveSizeInBits());
+ default:
+ return false;
+ }
+}
+
+Instruction *InstCombiner::visitMul(BinaryOperator &I) {
+ bool Changed = SimplifyCommutative(I);
+ Value *Op0 = I.getOperand(0);
+
+ if (isa<UndefValue>(I.getOperand(1))) // undef * X -> 0
+ return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
+
+ // Simplify mul instructions with a constant RHS...
+ if (Constant *Op1 = dyn_cast<Constant>(I.getOperand(1))) {
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
+
+ // ((X << C1)*C2) == (X * (C2 << C1))
+ if (BinaryOperator *SI = dyn_cast<BinaryOperator>(Op0))
+ if (SI->getOpcode() == Instruction::Shl)
+ if (Constant *ShOp = dyn_cast<Constant>(SI->getOperand(1)))
+ return BinaryOperator::createMul(SI->getOperand(0),
+ ConstantExpr::getShl(CI, ShOp));
+
+ if (CI->isZero())
+ return ReplaceInstUsesWith(I, Op1); // X * 0 == 0
+ if (CI->equalsInt(1)) // X * 1 == X
+ return ReplaceInstUsesWith(I, Op0);
+ if (CI->isAllOnesValue()) // X * -1 == 0 - X
+ return BinaryOperator::createNeg(Op0, I.getName());
+
+ const APInt& Val = cast<ConstantInt>(CI)->getValue();
+ if (Val.isPowerOf2()) { // Replace X*(2^C) with X << C
+ return BinaryOperator::createShl(Op0,
+ ConstantInt::get(Op0->getType(), Val.logBase2()));
+ }
+ } else if (ConstantFP *Op1F = dyn_cast<ConstantFP>(Op1)) {
+ if (Op1F->isNullValue())
+ return ReplaceInstUsesWith(I, Op1);
+
+ // "In IEEE floating point, x*1 is not equivalent to x for nans. However,
+ // ANSI says we can drop signals, so we can do this anyway." (from GCC)
+ if (Op1F->getValue() == 1.0)
+ return ReplaceInstUsesWith(I, Op0); // Eliminate 'mul double %X, 1.0'
+ }
+
+ if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0))
+ if (Op0I->getOpcode() == Instruction::Add && Op0I->hasOneUse() &&
+ isa<ConstantInt>(Op0I->getOperand(1))) {
+ // Canonicalize (X+C1)*C2 -> X*C2+C1*C2.
+ Instruction *Add = BinaryOperator::createMul(Op0I->getOperand(0),
+ Op1, "tmp");
+ InsertNewInstBefore(Add, I);
+ Value *C1C2 = ConstantExpr::getMul(Op1,
+ cast<Constant>(Op0I->getOperand(1)));
+ return BinaryOperator::createAdd(Add, C1C2);
+
+ }
+
+ // Try to fold constant mul into select arguments.
+ if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
+ if (Instruction *R = FoldOpIntoSelect(I, SI, this))
+ return R;
+
+ if (isa<PHINode>(Op0))
+ if (Instruction *NV = FoldOpIntoPhi(I))
+ return NV;
+ }
+
+ if (Value *Op0v = dyn_castNegVal(Op0)) // -X * -Y = X*Y
+ if (Value *Op1v = dyn_castNegVal(I.getOperand(1)))
+ return BinaryOperator::createMul(Op0v, Op1v);
+
+ // If one of the operands of the multiply is a cast from a boolean value, then
+ // we know the bool is either zero or one, so this is a 'masking' multiply.
+ // See if we can simplify things based on how the boolean was originally
+ // formed.
+ CastInst *BoolCast = 0;
+ if (ZExtInst *CI = dyn_cast<ZExtInst>(I.getOperand(0)))
+ if (CI->getOperand(0)->getType() == Type::Int1Ty)
+ BoolCast = CI;
+ if (!BoolCast)
+ if (ZExtInst *CI = dyn_cast<ZExtInst>(I.getOperand(1)))
+ if (CI->getOperand(0)->getType() == Type::Int1Ty)
+ BoolCast = CI;
+ if (BoolCast) {
+ if (ICmpInst *SCI = dyn_cast<ICmpInst>(BoolCast->getOperand(0))) {
+ Value *SCIOp0 = SCI->getOperand(0), *SCIOp1 = SCI->getOperand(1);
+ const Type *SCOpTy = SCIOp0->getType();
+ bool TIS = false;
+
+ // If the icmp is true iff the sign bit of X is set, then convert this
+ // multiply into a shift/and combination.
+ if (isa<ConstantInt>(SCIOp1) &&
+ isSignBitCheck(SCI->getPredicate(), cast<ConstantInt>(SCIOp1), TIS) &&
+ TIS) {
+ // Shift the X value right to turn it into "all signbits".
+ Constant *Amt = ConstantInt::get(SCIOp0->getType(),
+ SCOpTy->getPrimitiveSizeInBits()-1);
+ Value *V =
+ InsertNewInstBefore(
+ BinaryOperator::create(Instruction::AShr, SCIOp0, Amt,
+ BoolCast->getOperand(0)->getName()+
+ ".mask"), I);
+
+ // If the multiply type is not the same as the source type, sign extend
+ // or truncate to the multiply type.
+ if (I.getType() != V->getType()) {
+ uint32_t SrcBits = V->getType()->getPrimitiveSizeInBits();
+ uint32_t DstBits = I.getType()->getPrimitiveSizeInBits();
+ Instruction::CastOps opcode =
+ (SrcBits == DstBits ? Instruction::BitCast :
+ (SrcBits < DstBits ? Instruction::SExt : Instruction::Trunc));
+ V = InsertCastBefore(opcode, V, I.getType(), I);
+ }
+
+ Value *OtherOp = Op0 == BoolCast ? I.getOperand(1) : Op0;
+ return BinaryOperator::createAnd(V, OtherOp);
+ }
+ }
+ }
+
+ return Changed ? &I : 0;
+}
+
+/// This function implements the transforms on div instructions that work
+/// regardless of the kind of div instruction it is (udiv, sdiv, or fdiv). It is
+/// used by the visitors to those instructions.
+/// @brief Transforms common to all three div instructions
+Instruction *InstCombiner::commonDivTransforms(BinaryOperator &I) {
+ Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
+
+ // undef / X -> 0
+ if (isa<UndefValue>(Op0))
+ return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
+
+ // X / undef -> undef
+ if (isa<UndefValue>(Op1))
+ return ReplaceInstUsesWith(I, Op1);
+
+ // Handle cases involving: div X, (select Cond, Y, Z)
+ if (SelectInst *SI = dyn_cast<SelectInst>(Op1)) {
+ // div X, (Cond ? 0 : Y) -> div X, Y. If the div and the select are in the
+ // same basic block, then we replace the select with Y, and the condition
+ // of the select with false (if the cond value is in the same BB). If the
+ // select has uses other than the div, this allows them to be simplified
+ // also. Note that div X, Y is just as good as div X, 0 (undef)
+ if (Constant *ST = dyn_cast<Constant>(SI->getOperand(1)))
+ if (ST->isNullValue()) {
+ Instruction *CondI = dyn_cast<Instruction>(SI->getOperand(0));
+ if (CondI && CondI->getParent() == I.getParent())
+ UpdateValueUsesWith(CondI, ConstantInt::getFalse());
+ else if (I.getParent() != SI->getParent() || SI->hasOneUse())
+ I.setOperand(1, SI->getOperand(2));
+ else
+ UpdateValueUsesWith(SI, SI->getOperand(2));
+ return &I;
+ }
+
+ // Likewise for: div X, (Cond ? Y : 0) -> div X, Y
+ if (Constant *ST = dyn_cast<Constant>(SI->getOperand(2)))
+ if (ST->isNullValue()) {
+ Instruction *CondI = dyn_cast<Instruction>(SI->getOperand(0));
+ if (CondI && CondI->getParent() == I.getParent())
+ UpdateValueUsesWith(CondI, ConstantInt::getTrue());
+ else if (I.getParent() != SI->getParent() || SI->hasOneUse())
+ I.setOperand(1, SI->getOperand(1));
+ else
+ UpdateValueUsesWith(SI, SI->getOperand(1));
+ return &I;
+ }
+ }
+
+ return 0;
+}
+
+/// This function implements the transforms common to both integer division
+/// instructions (udiv and sdiv). It is called by the visitors to those integer
+/// division instructions.
+/// @brief Common integer divide transforms
+Instruction *InstCombiner::commonIDivTransforms(BinaryOperator &I) {
+ Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
+
+ if (Instruction *Common = commonDivTransforms(I))
+ return Common;
+
+ if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
+ // div X, 1 == X
+ if (RHS->equalsInt(1))
+ return ReplaceInstUsesWith(I, Op0);
+
+ // (X / C1) / C2 -> X / (C1*C2)
+ if (Instruction *LHS = dyn_cast<Instruction>(Op0))
+ if (Instruction::BinaryOps(LHS->getOpcode()) == I.getOpcode())
+ if (ConstantInt *LHSRHS = dyn_cast<ConstantInt>(LHS->getOperand(1))) {
+ return BinaryOperator::create(I.getOpcode(), LHS->getOperand(0),
+ Multiply(RHS, LHSRHS));
+ }
+
+ if (!RHS->isZero()) { // avoid X udiv 0
+ if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
+ if (Instruction *R = FoldOpIntoSelect(I, SI, this))
+ return R;
+ if (isa<PHINode>(Op0))
+ if (Instruction *NV = FoldOpIntoPhi(I))
+ return NV;
+ }
+ }
+
+ // 0 / X == 0, we don't need to preserve faults!
+ if (ConstantInt *LHS = dyn_cast<ConstantInt>(Op0))
+ if (LHS->equalsInt(0))
+ return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
+
+ return 0;
+}
+
+Instruction *InstCombiner::visitUDiv(BinaryOperator &I) {
+ Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
+
+ // Handle the integer div common cases
+ if (Instruction *Common = commonIDivTransforms(I))
+ return Common;
+
+ // X udiv C^2 -> X >> C
+ // Check to see if this is an unsigned division with an exact power of 2,
+ // if so, convert to a right shift.
+ if (ConstantInt *C = dyn_cast<ConstantInt>(Op1)) {
+ if (C->getValue().isPowerOf2()) // 0 not included in isPowerOf2
+ return BinaryOperator::createLShr(Op0,
+ ConstantInt::get(Op0->getType(), C->getValue().logBase2()));
+ }
+
+ // X udiv (C1 << N), where C1 is "1<<C2" --> X >> (N+C2)
+ if (BinaryOperator *RHSI = dyn_cast<BinaryOperator>(I.getOperand(1))) {
+ if (RHSI->getOpcode() == Instruction::Shl &&
+ isa<ConstantInt>(RHSI->getOperand(0))) {
+ const APInt& C1 = cast<ConstantInt>(RHSI->getOperand(0))->getValue();
+ if (C1.isPowerOf2()) {
+ Value *N = RHSI->getOperand(1);
+ const Type *NTy = N->getType();
+ if (uint32_t C2 = C1.logBase2()) {
+ Constant *C2V = ConstantInt::get(NTy, C2);
+ N = InsertNewInstBefore(BinaryOperator::createAdd(N, C2V, "tmp"), I);
+ }
+ return BinaryOperator::createLShr(Op0, N);
+ }
+ }
+ }
+
+ // udiv X, (Select Cond, C1, C2) --> Select Cond, (shr X, C1), (shr X, C2)
+ // where C1&C2 are powers of two.
+ if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
+ if (ConstantInt *STO = dyn_cast<ConstantInt>(SI->getOperand(1)))
+ if (ConstantInt *SFO = dyn_cast<ConstantInt>(SI->getOperand(2))) {
+ const APInt &TVA = STO->getValue(), &FVA = SFO->getValue();
+ if (TVA.isPowerOf2() && FVA.isPowerOf2()) {
+ // Compute the shift amounts
+ uint32_t TSA = TVA.logBase2(), FSA = FVA.logBase2();
+ // Construct the "on true" case of the select
+ Constant *TC = ConstantInt::get(Op0->getType(), TSA);
+ Instruction *TSI = BinaryOperator::createLShr(
+ Op0, TC, SI->getName()+".t");
+ TSI = InsertNewInstBefore(TSI, I);
+
+ // Construct the "on false" case of the select
+ Constant *FC = ConstantInt::get(Op0->getType(), FSA);
+ Instruction *FSI = BinaryOperator::createLShr(
+ Op0, FC, SI->getName()+".f");
+ FSI = InsertNewInstBefore(FSI, I);
+
+ // construct the select instruction and return it.
+ return new SelectInst(SI->getOperand(0), TSI, FSI, SI->getName());
+ }
+ }
+ return 0;
+}
+
+Instruction *InstCombiner::visitSDiv(BinaryOperator &I) {
+ Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
+
+ // Handle the integer div common cases
+ if (Instruction *Common = commonIDivTransforms(I))
+ return Common;
+
+ if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
+ // sdiv X, -1 == -X
+ if (RHS->isAllOnesValue())
+ return BinaryOperator::createNeg(Op0);
+
+ // -X/C -> X/-C
+ if (Value *LHSNeg = dyn_castNegVal(Op0))
+ return BinaryOperator::createSDiv(LHSNeg, ConstantExpr::getNeg(RHS));
+ }
+
+ // If the sign bits of both operands are zero (i.e. we can prove they are
+ // unsigned inputs), turn this into a udiv.
+ if (I.getType()->isInteger()) {
+ APInt Mask(APInt::getSignBit(I.getType()->getPrimitiveSizeInBits()));
+ if (MaskedValueIsZero(Op1, Mask) && MaskedValueIsZero(Op0, Mask)) {
+ return BinaryOperator::createUDiv(Op0, Op1, I.getName());
+ }
+ }
+
+ return 0;
+}
+
+Instruction *InstCombiner::visitFDiv(BinaryOperator &I) {
+ return commonDivTransforms(I);
+}
+
+/// GetFactor - If we can prove that the specified value is at least a multiple
+/// of some factor, return that factor.
+static Constant *GetFactor(Value *V) {
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(V))
+ return CI;
+
+ // Unless we can be tricky, we know this is a multiple of 1.
+ Constant *Result = ConstantInt::get(V->getType(), 1);
+
+ Instruction *I = dyn_cast<Instruction>(V);
+ if (!I) return Result;
+
+ if (I->getOpcode() == Instruction::Mul) {
+ // Handle multiplies by a constant, etc.
+ return ConstantExpr::getMul(GetFactor(I->getOperand(0)),
+ GetFactor(I->getOperand(1)));
+ } else if (I->getOpcode() == Instruction::Shl) {
+ // (X<<C) -> X * (1 << C)
+ if (Constant *ShRHS = dyn_cast<Constant>(I->getOperand(1))) {
+ ShRHS = ConstantExpr::getShl(Result, ShRHS);
+ return ConstantExpr::getMul(GetFactor(I->getOperand(0)), ShRHS);
+ }
+ } else if (I->getOpcode() == Instruction::And) {
+ if (ConstantInt *RHS = dyn_cast<ConstantInt>(I->getOperand(1))) {
+ // X & 0xFFF0 is known to be a multiple of 16.
+ uint32_t Zeros = RHS->getValue().countTrailingZeros();
+ if (Zeros != V->getType()->getPrimitiveSizeInBits())
+ return ConstantExpr::getShl(Result,
+ ConstantInt::get(Result->getType(), Zeros));
+ }
+ } else if (CastInst *CI = dyn_cast<CastInst>(I)) {
+ // Only handle int->int casts.
+ if (!CI->isIntegerCast())
+ return Result;
+ Value *Op = CI->getOperand(0);
+ return ConstantExpr::getCast(CI->getOpcode(), GetFactor(Op), V->getType());
+ }
+ return Result;
+}
+
+/// This function implements the transforms on rem instructions that work
+/// regardless of the kind of rem instruction it is (urem, srem, or frem). It
+/// is used by the visitors to those instructions.
+/// @brief Transforms common to all three rem instructions
+Instruction *InstCombiner::commonRemTransforms(BinaryOperator &I) {
+ Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
+
+ // 0 % X == 0, we don't need to preserve faults!
+ if (Constant *LHS = dyn_cast<Constant>(Op0))
+ if (LHS->isNullValue())
+ return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
+
+ if (isa<UndefValue>(Op0)) // undef % X -> 0
+ return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
+ if (isa<UndefValue>(Op1))
+ return ReplaceInstUsesWith(I, Op1); // X % undef -> undef
+
+ // Handle cases involving: rem X, (select Cond, Y, Z)
+ if (SelectInst *SI = dyn_cast<SelectInst>(Op1)) {
+ // rem X, (Cond ? 0 : Y) -> rem X, Y. If the rem and the select are in
+ // the same basic block, then we replace the select with Y, and the
+ // condition of the select with false (if the cond value is in the same
+ // BB). If the select has uses other than the div, this allows them to be
+ // simplified also.
+ if (Constant *ST = dyn_cast<Constant>(SI->getOperand(1)))
+ if (ST->isNullValue()) {
+ Instruction *CondI = dyn_cast<Instruction>(SI->getOperand(0));
+ if (CondI && CondI->getParent() == I.getParent())
+ UpdateValueUsesWith(CondI, ConstantInt::getFalse());
+ else if (I.getParent() != SI->getParent() || SI->hasOneUse())
+ I.setOperand(1, SI->getOperand(2));
+ else
+ UpdateValueUsesWith(SI, SI->getOperand(2));
+ return &I;
+ }
+ // Likewise for: rem X, (Cond ? Y : 0) -> rem X, Y
+ if (Constant *ST = dyn_cast<Constant>(SI->getOperand(2)))
+ if (ST->isNullValue()) {
+ Instruction *CondI = dyn_cast<Instruction>(SI->getOperand(0));
+ if (CondI && CondI->getParent() == I.getParent())
+ UpdateValueUsesWith(CondI, ConstantInt::getTrue());
+ else if (I.getParent() != SI->getParent() || SI->hasOneUse())
+ I.setOperand(1, SI->getOperand(1));
+ else
+ UpdateValueUsesWith(SI, SI->getOperand(1));
+ return &I;
+ }
+ }
+
+ return 0;
+}
+
+/// This function implements the transforms common to both integer remainder
+/// instructions (urem and srem). It is called by the visitors to those integer
+/// remainder instructions.
+/// @brief Common integer remainder transforms
+Instruction *InstCombiner::commonIRemTransforms(BinaryOperator &I) {
+ Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
+
+ if (Instruction *common = commonRemTransforms(I))
+ return common;
+
+ if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
+ // X % 0 == undef, we don't need to preserve faults!
+ if (RHS->equalsInt(0))
+ return ReplaceInstUsesWith(I, UndefValue::get(I.getType()));
+
+ if (RHS->equalsInt(1)) // X % 1 == 0
+ return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
+
+ if (Instruction *Op0I = dyn_cast<Instruction>(Op0)) {
+ if (SelectInst *SI = dyn_cast<SelectInst>(Op0I)) {
+ if (Instruction *R = FoldOpIntoSelect(I, SI, this))
+ return R;
+ } else if (isa<PHINode>(Op0I)) {
+ if (Instruction *NV = FoldOpIntoPhi(I))
+ return NV;
+ }
+ // (X * C1) % C2 --> 0 iff C1 % C2 == 0
+ if (ConstantExpr::getSRem(GetFactor(Op0I), RHS)->isNullValue())
+ return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
+ }
+ }
+
+ return 0;
+}
+
+Instruction *InstCombiner::visitURem(BinaryOperator &I) {
+ Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
+
+ if (Instruction *common = commonIRemTransforms(I))
+ return common;
+
+ if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
+ // X urem C^2 -> X and C
+ // Check to see if this is an unsigned remainder with an exact power of 2,
+ // if so, convert to a bitwise and.
+ if (ConstantInt *C = dyn_cast<ConstantInt>(RHS))
+ if (C->getValue().isPowerOf2())
+ return BinaryOperator::createAnd(Op0, SubOne(C));
+ }
+
+ if (Instruction *RHSI = dyn_cast<Instruction>(I.getOperand(1))) {
+ // Turn A % (C << N), where C is 2^k, into A & ((C << N)-1)
+ if (RHSI->getOpcode() == Instruction::Shl &&
+ isa<ConstantInt>(RHSI->getOperand(0))) {
+ if (cast<ConstantInt>(RHSI->getOperand(0))->getValue().isPowerOf2()) {
+ Constant *N1 = ConstantInt::getAllOnesValue(I.getType());
+ Value *Add = InsertNewInstBefore(BinaryOperator::createAdd(RHSI, N1,
+ "tmp"), I);
+ return BinaryOperator::createAnd(Op0, Add);
+ }
+ }
+ }
+
+ // urem X, (select Cond, 2^C1, 2^C2) --> select Cond, (and X, C1), (and X, C2)
+ // where C1&C2 are powers of two.
+ if (SelectInst *SI = dyn_cast<SelectInst>(Op1)) {
+ if (ConstantInt *STO = dyn_cast<ConstantInt>(SI->getOperand(1)))
+ if (ConstantInt *SFO = dyn_cast<ConstantInt>(SI->getOperand(2))) {
+ // STO == 0 and SFO == 0 handled above.
+ if ((STO->getValue().isPowerOf2()) &&
+ (SFO->getValue().isPowerOf2())) {
+ Value *TrueAnd = InsertNewInstBefore(
+ BinaryOperator::createAnd(Op0, SubOne(STO), SI->getName()+".t"), I);
+ Value *FalseAnd = InsertNewInstBefore(
+ BinaryOperator::createAnd(Op0, SubOne(SFO), SI->getName()+".f"), I);
+ return new SelectInst(SI->getOperand(0), TrueAnd, FalseAnd);
+ }
+ }
+ }
+
+ return 0;
+}
+
+Instruction *InstCombiner::visitSRem(BinaryOperator &I) {
+ Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
+
+ if (Instruction *common = commonIRemTransforms(I))
+ return common;
+
+ if (Value *RHSNeg = dyn_castNegVal(Op1))
+ if (!isa<ConstantInt>(RHSNeg) ||
+ cast<ConstantInt>(RHSNeg)->getValue().isStrictlyPositive()) {
+ // X % -Y -> X % Y
+ AddUsesToWorkList(I);
+ I.setOperand(1, RHSNeg);
+ return &I;
+ }
+
+ // If the top bits of both operands are zero (i.e. we can prove they are
+ // unsigned inputs), turn this into a urem.
+ APInt Mask(APInt::getSignBit(I.getType()->getPrimitiveSizeInBits()));
+ if (MaskedValueIsZero(Op1, Mask) && MaskedValueIsZero(Op0, Mask)) {
+ // X srem Y -> X urem Y, iff X and Y don't have sign bit set
+ return BinaryOperator::createURem(Op0, Op1, I.getName());
+ }
+
+ return 0;
+}
+
+Instruction *InstCombiner::visitFRem(BinaryOperator &I) {
+ return commonRemTransforms(I);
+}
+
+// isMaxValueMinusOne - return true if this is Max-1
+static bool isMaxValueMinusOne(const ConstantInt *C, bool isSigned) {
+ uint32_t TypeBits = C->getType()->getPrimitiveSizeInBits();
+ if (!isSigned)
+ return C->getValue() == APInt::getAllOnesValue(TypeBits) - 1;
+ return C->getValue() == APInt::getSignedMaxValue(TypeBits)-1;
+}
+
+// isMinValuePlusOne - return true if this is Min+1
+static bool isMinValuePlusOne(const ConstantInt *C, bool isSigned) {
+ if (!isSigned)
+ return C->getValue() == 1; // unsigned
+
+ // Calculate 1111111111000000000000
+ uint32_t TypeBits = C->getType()->getPrimitiveSizeInBits();
+ return C->getValue() == APInt::getSignedMinValue(TypeBits)+1;
+}
+
+// isOneBitSet - Return true if there is exactly one bit set in the specified
+// constant.
+static bool isOneBitSet(const ConstantInt *CI) {
+ return CI->getValue().isPowerOf2();
+}
+
+// isHighOnes - Return true if the constant is of the form 1+0+.
+// This is the same as lowones(~X).
+static bool isHighOnes(const ConstantInt *CI) {
+ return (~CI->getValue() + 1).isPowerOf2();
+}
+
+/// getICmpCode - Encode a icmp predicate into a three bit mask. These bits
+/// are carefully arranged to allow folding of expressions such as:
+///
+/// (A < B) | (A > B) --> (A != B)
+///
+/// Note that this is only valid if the first and second predicates have the
+/// same sign. Is illegal to do: (A u< B) | (A s> B)
+///
+/// Three bits are used to represent the condition, as follows:
+/// 0 A > B
+/// 1 A == B
+/// 2 A < B
+///
+/// <=> Value Definition
+/// 000 0 Always false
+/// 001 1 A > B
+/// 010 2 A == B
+/// 011 3 A >= B
+/// 100 4 A < B
+/// 101 5 A != B
+/// 110 6 A <= B
+/// 111 7 Always true
+///
+static unsigned getICmpCode(const ICmpInst *ICI) {
+ switch (ICI->getPredicate()) {
+ // False -> 0
+ case ICmpInst::ICMP_UGT: return 1; // 001
+ case ICmpInst::ICMP_SGT: return 1; // 001
+ case ICmpInst::ICMP_EQ: return 2; // 010
+ case ICmpInst::ICMP_UGE: return 3; // 011
+ case ICmpInst::ICMP_SGE: return 3; // 011
+ case ICmpInst::ICMP_ULT: return 4; // 100
+ case ICmpInst::ICMP_SLT: return 4; // 100
+ case ICmpInst::ICMP_NE: return 5; // 101
+ case ICmpInst::ICMP_ULE: return 6; // 110
+ case ICmpInst::ICMP_SLE: return 6; // 110
+ // True -> 7
+ default:
+ assert(0 && "Invalid ICmp predicate!");
+ return 0;
+ }
+}
+
+/// getICmpValue - This is the complement of getICmpCode, which turns an
+/// opcode and two operands into either a constant true or false, or a brand
+/// new /// ICmp instruction. The sign is passed in to determine which kind
+/// of predicate to use in new icmp instructions.
+static Value *getICmpValue(bool sign, unsigned code, Value *LHS, Value *RHS) {
+ switch (code) {
+ default: assert(0 && "Illegal ICmp code!");
+ case 0: return ConstantInt::getFalse();
+ case 1:
+ if (sign)
+ return new ICmpInst(ICmpInst::ICMP_SGT, LHS, RHS);
+ else
+ return new ICmpInst(ICmpInst::ICMP_UGT, LHS, RHS);
+ case 2: return new ICmpInst(ICmpInst::ICMP_EQ, LHS, RHS);
+ case 3:
+ if (sign)
+ return new ICmpInst(ICmpInst::ICMP_SGE, LHS, RHS);
+ else
+ return new ICmpInst(ICmpInst::ICMP_UGE, LHS, RHS);
+ case 4:
+ if (sign)
+ return new ICmpInst(ICmpInst::ICMP_SLT, LHS, RHS);
+ else
+ return new ICmpInst(ICmpInst::ICMP_ULT, LHS, RHS);
+ case 5: return new ICmpInst(ICmpInst::ICMP_NE, LHS, RHS);
+ case 6:
+ if (sign)
+ return new ICmpInst(ICmpInst::ICMP_SLE, LHS, RHS);
+ else
+ return new ICmpInst(ICmpInst::ICMP_ULE, LHS, RHS);
+ case 7: return ConstantInt::getTrue();
+ }
+}
+
+static bool PredicatesFoldable(ICmpInst::Predicate p1, ICmpInst::Predicate p2) {
+ return (ICmpInst::isSignedPredicate(p1) == ICmpInst::isSignedPredicate(p2)) ||
+ (ICmpInst::isSignedPredicate(p1) &&
+ (p2 == ICmpInst::ICMP_EQ || p2 == ICmpInst::ICMP_NE)) ||
+ (ICmpInst::isSignedPredicate(p2) &&
+ (p1 == ICmpInst::ICMP_EQ || p1 == ICmpInst::ICMP_NE));
+}
+
+namespace {
+// FoldICmpLogical - Implements (icmp1 A, B) & (icmp2 A, B) --> (icmp3 A, B)
+struct FoldICmpLogical {
+ InstCombiner &IC;
+ Value *LHS, *RHS;
+ ICmpInst::Predicate pred;
+ FoldICmpLogical(InstCombiner &ic, ICmpInst *ICI)
+ : IC(ic), LHS(ICI->getOperand(0)), RHS(ICI->getOperand(1)),
+ pred(ICI->getPredicate()) {}
+ bool shouldApply(Value *V) const {
+ if (ICmpInst *ICI = dyn_cast<ICmpInst>(V))
+ if (PredicatesFoldable(pred, ICI->getPredicate()))
+ return (ICI->getOperand(0) == LHS && ICI->getOperand(1) == RHS ||
+ ICI->getOperand(0) == RHS && ICI->getOperand(1) == LHS);
+ return false;
+ }
+ Instruction *apply(Instruction &Log) const {
+ ICmpInst *ICI = cast<ICmpInst>(Log.getOperand(0));
+ if (ICI->getOperand(0) != LHS) {
+ assert(ICI->getOperand(1) == LHS);
+ ICI->swapOperands(); // Swap the LHS and RHS of the ICmp
+ }
+
+ ICmpInst *RHSICI = cast<ICmpInst>(Log.getOperand(1));
+ unsigned LHSCode = getICmpCode(ICI);
+ unsigned RHSCode = getICmpCode(RHSICI);
+ unsigned Code;
+ switch (Log.getOpcode()) {
+ case Instruction::And: Code = LHSCode & RHSCode; break;
+ case Instruction::Or: Code = LHSCode | RHSCode; break;
+ case Instruction::Xor: Code = LHSCode ^ RHSCode; break;
+ default: assert(0 && "Illegal logical opcode!"); return 0;
+ }
+
+ bool isSigned = ICmpInst::isSignedPredicate(RHSICI->getPredicate()) ||
+ ICmpInst::isSignedPredicate(ICI->getPredicate());
+
+ Value *RV = getICmpValue(isSigned, Code, LHS, RHS);
+ if (Instruction *I = dyn_cast<Instruction>(RV))
+ return I;
+ // Otherwise, it's a constant boolean value...
+ return IC.ReplaceInstUsesWith(Log, RV);
+ }
+};
+} // end anonymous namespace
+
+// OptAndOp - This handles expressions of the form ((val OP C1) & C2). Where
+// the Op parameter is 'OP', OpRHS is 'C1', and AndRHS is 'C2'. Op is
+// guaranteed to be a binary operator.
+Instruction *InstCombiner::OptAndOp(Instruction *Op,
+ ConstantInt *OpRHS,
+ ConstantInt *AndRHS,
+ BinaryOperator &TheAnd) {
+ Value *X = Op->getOperand(0);
+ Constant *Together = 0;
+ if (!Op->isShift())
+ Together = And(AndRHS, OpRHS);
+
+ switch (Op->getOpcode()) {
+ case Instruction::Xor:
+ if (Op->hasOneUse()) {
+ // (X ^ C1) & C2 --> (X & C2) ^ (C1&C2)
+ Instruction *And = BinaryOperator::createAnd(X, AndRHS);
+ InsertNewInstBefore(And, TheAnd);
+ And->takeName(Op);
+ return BinaryOperator::createXor(And, Together);
+ }
+ break;
+ case Instruction::Or:
+ if (Together == AndRHS) // (X | C) & C --> C
+ return ReplaceInstUsesWith(TheAnd, AndRHS);
+
+ if (Op->hasOneUse() && Together != OpRHS) {
+ // (X | C1) & C2 --> (X | (C1&C2)) & C2
+ Instruction *Or = BinaryOperator::createOr(X, Together);
+ InsertNewInstBefore(Or, TheAnd);
+ Or->takeName(Op);
+ return BinaryOperator::createAnd(Or, AndRHS);
+ }
+ break;
+ case Instruction::Add:
+ if (Op->hasOneUse()) {
+ // Adding a one to a single bit bit-field should be turned into an XOR
+ // of the bit. First thing to check is to see if this AND is with a
+ // single bit constant.
+ const APInt& AndRHSV = cast<ConstantInt>(AndRHS)->getValue();
+
+ // If there is only one bit set...
+ if (isOneBitSet(cast<ConstantInt>(AndRHS))) {
+ // Ok, at this point, we know that we are masking the result of the
+ // ADD down to exactly one bit. If the constant we are adding has
+ // no bits set below this bit, then we can eliminate the ADD.
+ const APInt& AddRHS = cast<ConstantInt>(OpRHS)->getValue();
+
+ // Check to see if any bits below the one bit set in AndRHSV are set.
+ if ((AddRHS & (AndRHSV-1)) == 0) {
+ // If not, the only thing that can effect the output of the AND is
+ // the bit specified by AndRHSV. If that bit is set, the effect of
+ // the XOR is to toggle the bit. If it is clear, then the ADD has
+ // no effect.
+ if ((AddRHS & AndRHSV) == 0) { // Bit is not set, noop
+ TheAnd.setOperand(0, X);
+ return &TheAnd;
+ } else {
+ // Pull the XOR out of the AND.
+ Instruction *NewAnd = BinaryOperator::createAnd(X, AndRHS);
+ InsertNewInstBefore(NewAnd, TheAnd);
+ NewAnd->takeName(Op);
+ return BinaryOperator::createXor(NewAnd, AndRHS);
+ }
+ }
+ }
+ }
+ break;
+
+ case Instruction::Shl: {
+ // We know that the AND will not produce any of the bits shifted in, so if
+ // the anded constant includes them, clear them now!
+ //
+ uint32_t BitWidth = AndRHS->getType()->getBitWidth();
+ uint32_t OpRHSVal = OpRHS->getLimitedValue(BitWidth);
+ APInt ShlMask(APInt::getHighBitsSet(BitWidth, BitWidth-OpRHSVal));
+ ConstantInt *CI = ConstantInt::get(AndRHS->getValue() & ShlMask);
+
+ if (CI->getValue() == ShlMask) {
+ // Masking out bits that the shift already masks
+ return ReplaceInstUsesWith(TheAnd, Op); // No need for the and.
+ } else if (CI != AndRHS) { // Reducing bits set in and.
+ TheAnd.setOperand(1, CI);
+ return &TheAnd;
+ }
+ break;
+ }
+ case Instruction::LShr:
+ {
+ // We know that the AND will not produce any of the bits shifted in, so if
+ // the anded constant includes them, clear them now! This only applies to
+ // unsigned shifts, because a signed shr may bring in set bits!
+ //
+ uint32_t BitWidth = AndRHS->getType()->getBitWidth();
+ uint32_t OpRHSVal = OpRHS->getLimitedValue(BitWidth);
+ APInt ShrMask(APInt::getLowBitsSet(BitWidth, BitWidth - OpRHSVal));
+ ConstantInt *CI = ConstantInt::get(AndRHS->getValue() & ShrMask);
+
+ if (CI->getValue() == ShrMask) {
+ // Masking out bits that the shift already masks.
+ return ReplaceInstUsesWith(TheAnd, Op);
+ } else if (CI != AndRHS) {
+ TheAnd.setOperand(1, CI); // Reduce bits set in and cst.
+ return &TheAnd;
+ }
+ break;
+ }
+ case Instruction::AShr:
+ // Signed shr.
+ // See if this is shifting in some sign extension, then masking it out
+ // with an and.
+ if (Op->hasOneUse()) {
+ uint32_t BitWidth = AndRHS->getType()->getBitWidth();
+ uint32_t OpRHSVal = OpRHS->getLimitedValue(BitWidth);
+ APInt ShrMask(APInt::getLowBitsSet(BitWidth, BitWidth - OpRHSVal));
+ Constant *C = ConstantInt::get(AndRHS->getValue() & ShrMask);
+ if (C == AndRHS) { // Masking out bits shifted in.
+ // (Val ashr C1) & C2 -> (Val lshr C1) & C2
+ // Make the argument unsigned.
+ Value *ShVal = Op->getOperand(0);
+ ShVal = InsertNewInstBefore(
+ BinaryOperator::createLShr(ShVal, OpRHS,
+ Op->getName()), TheAnd);
+ return BinaryOperator::createAnd(ShVal, AndRHS, TheAnd.getName());
+ }
+ }
+ break;
+ }
+ return 0;
+}
+
+
+/// InsertRangeTest - Emit a computation of: (V >= Lo && V < Hi) if Inside is
+/// true, otherwise (V < Lo || V >= Hi). In pratice, we emit the more efficient
+/// (V-Lo) <u Hi-Lo. This method expects that Lo <= Hi. isSigned indicates
+/// whether to treat the V, Lo and HI as signed or not. IB is the location to
+/// insert new instructions.
+Instruction *InstCombiner::InsertRangeTest(Value *V, Constant *Lo, Constant *Hi,
+ bool isSigned, bool Inside,
+ Instruction &IB) {
+ assert(cast<ConstantInt>(ConstantExpr::getICmp((isSigned ?
+ ICmpInst::ICMP_SLE:ICmpInst::ICMP_ULE), Lo, Hi))->getZExtValue() &&
+ "Lo is not <= Hi in range emission code!");
+
+ if (Inside) {
+ if (Lo == Hi) // Trivially false.
+ return new ICmpInst(ICmpInst::ICMP_NE, V, V);
+
+ // V >= Min && V < Hi --> V < Hi
+ if (cast<ConstantInt>(Lo)->isMinValue(isSigned)) {
+ ICmpInst::Predicate pred = (isSigned ?
+ ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT);
+ return new ICmpInst(pred, V, Hi);
+ }
+
+ // Emit V-Lo <u Hi-Lo
+ Constant *NegLo = ConstantExpr::getNeg(Lo);
+ Instruction *Add = BinaryOperator::createAdd(V, NegLo, V->getName()+".off");
+ InsertNewInstBefore(Add, IB);
+ Constant *UpperBound = ConstantExpr::getAdd(NegLo, Hi);
+ return new ICmpInst(ICmpInst::ICMP_ULT, Add, UpperBound);
+ }
+
+ if (Lo == Hi) // Trivially true.
+ return new ICmpInst(ICmpInst::ICMP_EQ, V, V);
+
+ // V < Min || V >= Hi -> V > Hi-1
+ Hi = SubOne(cast<ConstantInt>(Hi));
+ if (cast<ConstantInt>(Lo)->isMinValue(isSigned)) {
+ ICmpInst::Predicate pred = (isSigned ?
+ ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT);
+ return new ICmpInst(pred, V, Hi);
+ }
+
+ // Emit V-Lo >u Hi-1-Lo
+ // Note that Hi has already had one subtracted from it, above.
+ ConstantInt *NegLo = cast<ConstantInt>(ConstantExpr::getNeg(Lo));
+ Instruction *Add = BinaryOperator::createAdd(V, NegLo, V->getName()+".off");
+ InsertNewInstBefore(Add, IB);
+ Constant *LowerBound = ConstantExpr::getAdd(NegLo, Hi);
+ return new ICmpInst(ICmpInst::ICMP_UGT, Add, LowerBound);
+}
+
+// isRunOfOnes - Returns true iff Val consists of one contiguous run of 1s with
+// any number of 0s on either side. The 1s are allowed to wrap from LSB to
+// MSB, so 0x000FFF0, 0x0000FFFF, and 0xFF0000FF are all runs. 0x0F0F0000 is
+// not, since all 1s are not contiguous.
+static bool isRunOfOnes(ConstantInt *Val, uint32_t &MB, uint32_t &ME) {
+ const APInt& V = Val->getValue();
+ uint32_t BitWidth = Val->getType()->getBitWidth();
+ if (!APIntOps::isShiftedMask(BitWidth, V)) return false;
+
+ // look for the first zero bit after the run of ones
+ MB = BitWidth - ((V - 1) ^ V).countLeadingZeros();
+ // look for the first non-zero bit
+ ME = V.getActiveBits();
+ return true;
+}
+
+/// FoldLogicalPlusAnd - This is part of an expression (LHS +/- RHS) & Mask,
+/// where isSub determines whether the operator is a sub. If we can fold one of
+/// the following xforms:
+///
+/// ((A & N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == Mask
+/// ((A | N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == 0
+/// ((A ^ N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == 0
+///
+/// return (A +/- B).
+///
+Value *InstCombiner::FoldLogicalPlusAnd(Value *LHS, Value *RHS,
+ ConstantInt *Mask, bool isSub,
+ Instruction &I) {
+ Instruction *LHSI = dyn_cast<Instruction>(LHS);
+ if (!LHSI || LHSI->getNumOperands() != 2 ||
+ !isa<ConstantInt>(LHSI->getOperand(1))) return 0;
+
+ ConstantInt *N = cast<ConstantInt>(LHSI->getOperand(1));
+
+ switch (LHSI->getOpcode()) {
+ default: return 0;
+ case Instruction::And:
+ if (And(N, Mask) == Mask) {
+ // If the AndRHS is a power of two minus one (0+1+), this is simple.
+ if ((Mask->getValue().countLeadingZeros() +
+ Mask->getValue().countPopulation()) ==
+ Mask->getValue().getBitWidth())
+ break;
+
+ // Otherwise, if Mask is 0+1+0+, and if B is known to have the low 0+
+ // part, we don't need any explicit masks to take them out of A. If that
+ // is all N is, ignore it.
+ uint32_t MB = 0, ME = 0;
+ if (isRunOfOnes(Mask, MB, ME)) { // begin/end bit of run, inclusive
+ uint32_t BitWidth = cast<IntegerType>(RHS->getType())->getBitWidth();
+ APInt Mask(APInt::getLowBitsSet(BitWidth, MB-1));
+ if (MaskedValueIsZero(RHS, Mask))
+ break;
+ }
+ }
+ return 0;
+ case Instruction::Or:
+ case Instruction::Xor:
+ // If the AndRHS is a power of two minus one (0+1+), and N&Mask == 0
+ if ((Mask->getValue().countLeadingZeros() +
+ Mask->getValue().countPopulation()) == Mask->getValue().getBitWidth()
+ && And(N, Mask)->isZero())
+ break;
+ return 0;
+ }
+
+ Instruction *New;
+ if (isSub)
+ New = BinaryOperator::createSub(LHSI->getOperand(0), RHS, "fold");
+ else
+ New = BinaryOperator::createAdd(LHSI->getOperand(0), RHS, "fold");
+ return InsertNewInstBefore(New, I);
+}
+
+Instruction *InstCombiner::visitAnd(BinaryOperator &I) {
+ bool Changed = SimplifyCommutative(I);
+ Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
+
+ if (isa<UndefValue>(Op1)) // X & undef -> 0
+ return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
+
+ // and X, X = X
+ if (Op0 == Op1)
+ return ReplaceInstUsesWith(I, Op1);
+
+ // See if we can simplify any instructions used by the instruction whose sole
+ // purpose is to compute bits we don't care about.
+ if (!isa<VectorType>(I.getType())) {
+ uint32_t BitWidth = cast<IntegerType>(I.getType())->getBitWidth();
+ APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
+ if (SimplifyDemandedBits(&I, APInt::getAllOnesValue(BitWidth),
+ KnownZero, KnownOne))
+ return &I;
+ } else {
+ if (ConstantVector *CP = dyn_cast<ConstantVector>(Op1)) {
+ if (CP->isAllOnesValue()) // X & <-1,-1> -> X
+ return ReplaceInstUsesWith(I, I.getOperand(0));
+ } else if (isa<ConstantAggregateZero>(Op1)) {
+ return ReplaceInstUsesWith(I, Op1); // X & <0,0> -> <0,0>
+ }
+ }
+
+ if (ConstantInt *AndRHS = dyn_cast<ConstantInt>(Op1)) {
+ const APInt& AndRHSMask = AndRHS->getValue();
+ APInt NotAndRHS(~AndRHSMask);
+
+ // Optimize a variety of ((val OP C1) & C2) combinations...
+ if (isa<BinaryOperator>(Op0)) {
+ Instruction *Op0I = cast<Instruction>(Op0);
+ Value *Op0LHS = Op0I->getOperand(0);
+ Value *Op0RHS = Op0I->getOperand(1);
+ switch (Op0I->getOpcode()) {
+ case Instruction::Xor:
+ case Instruction::Or:
+ // If the mask is only needed on one incoming arm, push it up.
+ if (Op0I->hasOneUse()) {
+ if (MaskedValueIsZero(Op0LHS, NotAndRHS)) {
+ // Not masking anything out for the LHS, move to RHS.
+ Instruction *NewRHS = BinaryOperator::createAnd(Op0RHS, AndRHS,
+ Op0RHS->getName()+".masked");
+ InsertNewInstBefore(NewRHS, I);
+ return BinaryOperator::create(
+ cast<BinaryOperator>(Op0I)->getOpcode(), Op0LHS, NewRHS);
+ }
+ if (!isa<Constant>(Op0RHS) &&
+ MaskedValueIsZero(Op0RHS, NotAndRHS)) {
+ // Not masking anything out for the RHS, move to LHS.
+ Instruction *NewLHS = BinaryOperator::createAnd(Op0LHS, AndRHS,
+ Op0LHS->getName()+".masked");
+ InsertNewInstBefore(NewLHS, I);
+ return BinaryOperator::create(
+ cast<BinaryOperator>(Op0I)->getOpcode(), NewLHS, Op0RHS);
+ }
+ }
+
+ break;
+ case Instruction::Add:
+ // ((A & N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == AndRHS.
+ // ((A | N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == 0
+ // ((A ^ N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == 0
+ if (Value *V = FoldLogicalPlusAnd(Op0LHS, Op0RHS, AndRHS, false, I))
+ return BinaryOperator::createAnd(V, AndRHS);
+ if (Value *V = FoldLogicalPlusAnd(Op0RHS, Op0LHS, AndRHS, false, I))
+ return BinaryOperator::createAnd(V, AndRHS); // Add commutes
+ break;
+
+ case Instruction::Sub:
+ // ((A & N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == AndRHS.
+ // ((A | N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == 0
+ // ((A ^ N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == 0
+ if (Value *V = FoldLogicalPlusAnd(Op0LHS, Op0RHS, AndRHS, true, I))
+ return BinaryOperator::createAnd(V, AndRHS);
+ break;
+ }
+
+ if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1)))
+ if (Instruction *Res = OptAndOp(Op0I, Op0CI, AndRHS, I))
+ return Res;
+ } else if (CastInst *CI = dyn_cast<CastInst>(Op0)) {
+ // If this is an integer truncation or change from signed-to-unsigned, and
+ // if the source is an and/or with immediate, transform it. This
+ // frequently occurs for bitfield accesses.
+ if (Instruction *CastOp = dyn_cast<Instruction>(CI->getOperand(0))) {
+ if ((isa<TruncInst>(CI) || isa<BitCastInst>(CI)) &&
+ CastOp->getNumOperands() == 2)
+ if (ConstantInt *AndCI = dyn_cast<ConstantInt>(CastOp->getOperand(1)))
+ if (CastOp->getOpcode() == Instruction::And) {
+ // Change: and (cast (and X, C1) to T), C2
+ // into : and (cast X to T), trunc_or_bitcast(C1)&C2
+ // This will fold the two constants together, which may allow
+ // other simplifications.
+ Instruction *NewCast = CastInst::createTruncOrBitCast(
+ CastOp->getOperand(0), I.getType(),
+ CastOp->getName()+".shrunk");
+ NewCast = InsertNewInstBefore(NewCast, I);
+ // trunc_or_bitcast(C1)&C2
+ Constant *C3 = ConstantExpr::getTruncOrBitCast(AndCI,I.getType());
+ C3 = ConstantExpr::getAnd(C3, AndRHS);
+ return BinaryOperator::createAnd(NewCast, C3);
+ } else if (CastOp->getOpcode() == Instruction::Or) {
+ // Change: and (cast (or X, C1) to T), C2
+ // into : trunc(C1)&C2 iff trunc(C1)&C2 == C2
+ Constant *C3 = ConstantExpr::getTruncOrBitCast(AndCI,I.getType());
+ if (ConstantExpr::getAnd(C3, AndRHS) == AndRHS) // trunc(C1)&C2
+ return ReplaceInstUsesWith(I, AndRHS);
+ }
+ }
+ }
+
+ // Try to fold constant and into select arguments.
+ if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
+ if (Instruction *R = FoldOpIntoSelect(I, SI, this))
+ return R;
+ if (isa<PHINode>(Op0))
+ if (Instruction *NV = FoldOpIntoPhi(I))
+ return NV;
+ }
+
+ Value *Op0NotVal = dyn_castNotVal(Op0);
+ Value *Op1NotVal = dyn_castNotVal(Op1);
+
+ if (Op0NotVal == Op1 || Op1NotVal == Op0) // A & ~A == ~A & A == 0
+ return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
+
+ // (~A & ~B) == (~(A | B)) - De Morgan's Law
+ if (Op0NotVal && Op1NotVal && isOnlyUse(Op0) && isOnlyUse(Op1)) {
+ Instruction *Or = BinaryOperator::createOr(Op0NotVal, Op1NotVal,
+ I.getName()+".demorgan");
+ InsertNewInstBefore(Or, I);
+ return BinaryOperator::createNot(Or);
+ }
+
+ {
+ Value *A = 0, *B = 0, *C = 0, *D = 0;
+ if (match(Op0, m_Or(m_Value(A), m_Value(B)))) {
+ if (A == Op1 || B == Op1) // (A | ?) & A --> A
+ return ReplaceInstUsesWith(I, Op1);
+
+ // (A|B) & ~(A&B) -> A^B
+ if (match(Op1, m_Not(m_And(m_Value(C), m_Value(D))))) {
+ if ((A == C && B == D) || (A == D && B == C))
+ return BinaryOperator::createXor(A, B);
+ }
+ }
+
+ if (match(Op1, m_Or(m_Value(A), m_Value(B)))) {
+ if (A == Op0 || B == Op0) // A & (A | ?) --> A
+ return ReplaceInstUsesWith(I, Op0);
+
+ // ~(A&B) & (A|B) -> A^B
+ if (match(Op0, m_Not(m_And(m_Value(C), m_Value(D))))) {
+ if ((A == C && B == D) || (A == D && B == C))
+ return BinaryOperator::createXor(A, B);
+ }
+ }
+
+ if (Op0->hasOneUse() &&
+ match(Op0, m_Xor(m_Value(A), m_Value(B)))) {
+ if (A == Op1) { // (A^B)&A -> A&(A^B)
+ I.swapOperands(); // Simplify below
+ std::swap(Op0, Op1);
+ } else if (B == Op1) { // (A^B)&B -> B&(B^A)
+ cast<BinaryOperator>(Op0)->swapOperands();
+ I.swapOperands(); // Simplify below
+ std::swap(Op0, Op1);
+ }
+ }
+ if (Op1->hasOneUse() &&
+ match(Op1, m_Xor(m_Value(A), m_Value(B)))) {
+ if (B == Op0) { // B&(A^B) -> B&(B^A)
+ cast<BinaryOperator>(Op1)->swapOperands();
+ std::swap(A, B);
+ }
+ if (A == Op0) { // A&(A^B) -> A & ~B
+ Instruction *NotB = BinaryOperator::createNot(B, "tmp");
+ InsertNewInstBefore(NotB, I);
+ return BinaryOperator::createAnd(A, NotB);
+ }
+ }
+ }
+
+ if (ICmpInst *RHS = dyn_cast<ICmpInst>(Op1)) {
+ // (icmp1 A, B) & (icmp2 A, B) --> (icmp3 A, B)
+ if (Instruction *R = AssociativeOpt(I, FoldICmpLogical(*this, RHS)))
+ return R;
+
+ Value *LHSVal, *RHSVal;
+ ConstantInt *LHSCst, *RHSCst;
+ ICmpInst::Predicate LHSCC, RHSCC;
+ if (match(Op0, m_ICmp(LHSCC, m_Value(LHSVal), m_ConstantInt(LHSCst))))
+ if (match(RHS, m_ICmp(RHSCC, m_Value(RHSVal), m_ConstantInt(RHSCst))))
+ if (LHSVal == RHSVal && // Found (X icmp C1) & (X icmp C2)
+ // ICMP_[GL]E X, CST is folded to ICMP_[GL]T elsewhere.
+ LHSCC != ICmpInst::ICMP_UGE && LHSCC != ICmpInst::ICMP_ULE &&
+ RHSCC != ICmpInst::ICMP_UGE && RHSCC != ICmpInst::ICMP_ULE &&
+ LHSCC != ICmpInst::ICMP_SGE && LHSCC != ICmpInst::ICMP_SLE &&
+ RHSCC != ICmpInst::ICMP_SGE && RHSCC != ICmpInst::ICMP_SLE) {
+ // Ensure that the larger constant is on the RHS.
+ ICmpInst::Predicate GT = ICmpInst::isSignedPredicate(LHSCC) ?
+ ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT;
+ Constant *Cmp = ConstantExpr::getICmp(GT, LHSCst, RHSCst);
+ ICmpInst *LHS = cast<ICmpInst>(Op0);
+ if (cast<ConstantInt>(Cmp)->getZExtValue()) {
+ std::swap(LHS, RHS);
+ std::swap(LHSCst, RHSCst);
+ std::swap(LHSCC, RHSCC);
+ }
+
+ // At this point, we know we have have two icmp instructions
+ // comparing a value against two constants and and'ing the result
+ // together. Because of the above check, we know that we only have
+ // icmp eq, icmp ne, icmp [su]lt, and icmp [SU]gt here. We also know
+ // (from the FoldICmpLogical check above), that the two constants
+ // are not equal and that the larger constant is on the RHS
+ assert(LHSCst != RHSCst && "Compares not folded above?");
+
+ switch (LHSCC) {
+ default: assert(0 && "Unknown integer condition code!");
+ case ICmpInst::ICMP_EQ:
+ switch (RHSCC) {
+ default: assert(0 && "Unknown integer condition code!");
+ case ICmpInst::ICMP_EQ: // (X == 13 & X == 15) -> false
+ case ICmpInst::ICMP_UGT: // (X == 13 & X > 15) -> false
+ case ICmpInst::ICMP_SGT: // (X == 13 & X > 15) -> false
+ return ReplaceInstUsesWith(I, ConstantInt::getFalse());
+ case ICmpInst::ICMP_NE: // (X == 13 & X != 15) -> X == 13
+ case ICmpInst::ICMP_ULT: // (X == 13 & X < 15) -> X == 13
+ case ICmpInst::ICMP_SLT: // (X == 13 & X < 15) -> X == 13
+ return ReplaceInstUsesWith(I, LHS);
+ }
+ case ICmpInst::ICMP_NE:
+ switch (RHSCC) {
+ default: assert(0 && "Unknown integer condition code!");
+ case ICmpInst::ICMP_ULT:
+ if (LHSCst == SubOne(RHSCst)) // (X != 13 & X u< 14) -> X < 13
+ return new ICmpInst(ICmpInst::ICMP_ULT, LHSVal, LHSCst);
+ break; // (X != 13 & X u< 15) -> no change
+ case ICmpInst::ICMP_SLT:
+ if (LHSCst == SubOne(RHSCst)) // (X != 13 & X s< 14) -> X < 13
+ return new ICmpInst(ICmpInst::ICMP_SLT, LHSVal, LHSCst);
+ break; // (X != 13 & X s< 15) -> no change
+ case ICmpInst::ICMP_EQ: // (X != 13 & X == 15) -> X == 15
+ case ICmpInst::ICMP_UGT: // (X != 13 & X u> 15) -> X u> 15
+ case ICmpInst::ICMP_SGT: // (X != 13 & X s> 15) -> X s> 15
+ return ReplaceInstUsesWith(I, RHS);
+ case ICmpInst::ICMP_NE:
+ if (LHSCst == SubOne(RHSCst)){// (X != 13 & X != 14) -> X-13 >u 1
+ Constant *AddCST = ConstantExpr::getNeg(LHSCst);
+ Instruction *Add = BinaryOperator::createAdd(LHSVal, AddCST,
+ LHSVal->getName()+".off");
+ InsertNewInstBefore(Add, I);
+ return new ICmpInst(ICmpInst::ICMP_UGT, Add,
+ ConstantInt::get(Add->getType(), 1));
+ }
+ break; // (X != 13 & X != 15) -> no change
+ }
+ break;
+ case ICmpInst::ICMP_ULT:
+ switch (RHSCC) {
+ default: assert(0 && "Unknown integer condition code!");
+ case ICmpInst::ICMP_EQ: // (X u< 13 & X == 15) -> false
+ case ICmpInst::ICMP_UGT: // (X u< 13 & X u> 15) -> false
+ return ReplaceInstUsesWith(I, ConstantInt::getFalse());
+ case ICmpInst::ICMP_SGT: // (X u< 13 & X s> 15) -> no change
+ break;
+ case ICmpInst::ICMP_NE: // (X u< 13 & X != 15) -> X u< 13
+ case ICmpInst::ICMP_ULT: // (X u< 13 & X u< 15) -> X u< 13
+ return ReplaceInstUsesWith(I, LHS);
+ case ICmpInst::ICMP_SLT: // (X u< 13 & X s< 15) -> no change
+ break;
+ }
+ break;
+ case ICmpInst::ICMP_SLT:
+ switch (RHSCC) {
+ default: assert(0 && "Unknown integer condition code!");
+ case ICmpInst::ICMP_EQ: // (X s< 13 & X == 15) -> false
+ case ICmpInst::ICMP_SGT: // (X s< 13 & X s> 15) -> false
+ return ReplaceInstUsesWith(I, ConstantInt::getFalse());
+ case ICmpInst::ICMP_UGT: // (X s< 13 & X u> 15) -> no change
+ break;
+ case ICmpInst::ICMP_NE: // (X s< 13 & X != 15) -> X < 13
+ case ICmpInst::ICMP_SLT: // (X s< 13 & X s< 15) -> X < 13
+ return ReplaceInstUsesWith(I, LHS);
+ case ICmpInst::ICMP_ULT: // (X s< 13 & X u< 15) -> no change
+ break;
+ }
+ break;
+ case ICmpInst::ICMP_UGT:
+ switch (RHSCC) {
+ default: assert(0 && "Unknown integer condition code!");
+ case ICmpInst::ICMP_EQ: // (X u> 13 & X == 15) -> X > 13
+ return ReplaceInstUsesWith(I, LHS);
+ case ICmpInst::ICMP_UGT: // (X u> 13 & X u> 15) -> X u> 15
+ return ReplaceInstUsesWith(I, RHS);
+ case ICmpInst::ICMP_SGT: // (X u> 13 & X s> 15) -> no change
+ break;
+ case ICmpInst::ICMP_NE:
+ if (RHSCst == AddOne(LHSCst)) // (X u> 13 & X != 14) -> X u> 14
+ return new ICmpInst(LHSCC, LHSVal, RHSCst);
+ break; // (X u> 13 & X != 15) -> no change
+ case ICmpInst::ICMP_ULT: // (X u> 13 & X u< 15) ->(X-14) <u 1
+ return InsertRangeTest(LHSVal, AddOne(LHSCst), RHSCst, false,
+ true, I);
+ case ICmpInst::ICMP_SLT: // (X u> 13 & X s< 15) -> no change
+ break;
+ }
+ break;
+ case ICmpInst::ICMP_SGT:
+ switch (RHSCC) {
+ default: assert(0 && "Unknown integer condition code!");
+ case ICmpInst::ICMP_EQ: // (X s> 13 & X == 15) -> X s> 13
+ return ReplaceInstUsesWith(I, LHS);
+ case ICmpInst::ICMP_SGT: // (X s> 13 & X s> 15) -> X s> 15
+ return ReplaceInstUsesWith(I, RHS);
+ case ICmpInst::ICMP_UGT: // (X s> 13 & X u> 15) -> no change
+ break;
+ case ICmpInst::ICMP_NE:
+ if (RHSCst == AddOne(LHSCst)) // (X s> 13 & X != 14) -> X s> 14
+ return new ICmpInst(LHSCC, LHSVal, RHSCst);
+ break; // (X s> 13 & X != 15) -> no change
+ case ICmpInst::ICMP_SLT: // (X s> 13 & X s< 15) ->(X-14) s< 1
+ return InsertRangeTest(LHSVal, AddOne(LHSCst), RHSCst, true,
+ true, I);
+ case ICmpInst::ICMP_ULT: // (X s> 13 & X u< 15) -> no change
+ break;
+ }
+ break;
+ }
+ }
+ }
+
+ // fold (and (cast A), (cast B)) -> (cast (and A, B))
+ if (CastInst *Op0C = dyn_cast<CastInst>(Op0))
+ if (CastInst *Op1C = dyn_cast<CastInst>(Op1))
+ if (Op0C->getOpcode() == Op1C->getOpcode()) { // same cast kind ?
+ const Type *SrcTy = Op0C->getOperand(0)->getType();
+ if (SrcTy == Op1C->getOperand(0)->getType() && SrcTy->isInteger() &&
+ // Only do this if the casts both really cause code to be generated.
+ ValueRequiresCast(Op0C->getOpcode(), Op0C->getOperand(0),
+ I.getType(), TD) &&
+ ValueRequiresCast(Op1C->getOpcode(), Op1C->getOperand(0),
+ I.getType(), TD)) {
+ Instruction *NewOp = BinaryOperator::createAnd(Op0C->getOperand(0),
+ Op1C->getOperand(0),
+ I.getName());
+ InsertNewInstBefore(NewOp, I);
+ return CastInst::create(Op0C->getOpcode(), NewOp, I.getType());
+ }
+ }
+
+ // (X >> Z) & (Y >> Z) -> (X&Y) >> Z for all shifts.
+ if (BinaryOperator *SI1 = dyn_cast<BinaryOperator>(Op1)) {
+ if (BinaryOperator *SI0 = dyn_cast<BinaryOperator>(Op0))
+ if (SI0->isShift() && SI0->getOpcode() == SI1->getOpcode() &&
+ SI0->getOperand(1) == SI1->getOperand(1) &&
+ (SI0->hasOneUse() || SI1->hasOneUse())) {
+ Instruction *NewOp =
+ InsertNewInstBefore(BinaryOperator::createAnd(SI0->getOperand(0),
+ SI1->getOperand(0),
+ SI0->getName()), I);
+ return BinaryOperator::create(SI1->getOpcode(), NewOp,
+ SI1->getOperand(1));
+ }
+ }
+
+ return Changed ? &I : 0;
+}
+
+/// CollectBSwapParts - Look to see if the specified value defines a single byte
+/// in the result. If it does, and if the specified byte hasn't been filled in
+/// yet, fill it in and return false.
+static bool CollectBSwapParts(Value *V, SmallVector<Value*, 8> &ByteValues) {
+ Instruction *I = dyn_cast<Instruction>(V);
+ if (I == 0) return true;
+
+ // If this is an or instruction, it is an inner node of the bswap.
+ if (I->getOpcode() == Instruction::Or)
+ return CollectBSwapParts(I->getOperand(0), ByteValues) ||
+ CollectBSwapParts(I->getOperand(1), ByteValues);
+
+ uint32_t BitWidth = I->getType()->getPrimitiveSizeInBits();
+ // If this is a shift by a constant int, and it is "24", then its operand
+ // defines a byte. We only handle unsigned types here.
+ if (I->isShift() && isa<ConstantInt>(I->getOperand(1))) {
+ // Not shifting the entire input by N-1 bytes?
+ if (cast<ConstantInt>(I->getOperand(1))->getLimitedValue(BitWidth) !=
+ 8*(ByteValues.size()-1))
+ return true;
+
+ unsigned DestNo;
+ if (I->getOpcode() == Instruction::Shl) {
+ // X << 24 defines the top byte with the lowest of the input bytes.
+ DestNo = ByteValues.size()-1;
+ } else {
+ // X >>u 24 defines the low byte with the highest of the input bytes.
+ DestNo = 0;
+ }
+
+ // If the destination byte value is already defined, the values are or'd
+ // together, which isn't a bswap (unless it's an or of the same bits).
+ if (ByteValues[DestNo] && ByteValues[DestNo] != I->getOperand(0))
+ return true;
+ ByteValues[DestNo] = I->getOperand(0);
+ return false;
+ }
+
+ // Otherwise, we can only handle and(shift X, imm), imm). Bail out of if we
+ // don't have this.
+ Value *Shift = 0, *ShiftLHS = 0;
+ ConstantInt *AndAmt = 0, *ShiftAmt = 0;
+ if (!match(I, m_And(m_Value(Shift), m_ConstantInt(AndAmt))) ||
+ !match(Shift, m_Shift(m_Value(ShiftLHS), m_ConstantInt(ShiftAmt))))
+ return true;
+ Instruction *SI = cast<Instruction>(Shift);
+
+ // Make sure that the shift amount is by a multiple of 8 and isn't too big.
+ if (ShiftAmt->getLimitedValue(BitWidth) & 7 ||
+ ShiftAmt->getLimitedValue(BitWidth) > 8*ByteValues.size())
+ return true;
+
+ // Turn 0xFF -> 0, 0xFF00 -> 1, 0xFF0000 -> 2, etc.
+ unsigned DestByte;
+ if (AndAmt->getValue().getActiveBits() > 64)
+ return true;
+ uint64_t AndAmtVal = AndAmt->getZExtValue();
+ for (DestByte = 0; DestByte != ByteValues.size(); ++DestByte)
+ if (AndAmtVal == uint64_t(0xFF) << 8*DestByte)
+ break;
+ // Unknown mask for bswap.
+ if (DestByte == ByteValues.size()) return true;
+
+ unsigned ShiftBytes = ShiftAmt->getZExtValue()/8;
+ unsigned SrcByte;
+ if (SI->getOpcode() == Instruction::Shl)
+ SrcByte = DestByte - ShiftBytes;
+ else
+ SrcByte = DestByte + ShiftBytes;
+
+ // If the SrcByte isn't a bswapped value from the DestByte, reject it.
+ if (SrcByte != ByteValues.size()-DestByte-1)
+ return true;
+
+ // If the destination byte value is already defined, the values are or'd
+ // together, which isn't a bswap (unless it's an or of the same bits).
+ if (ByteValues[DestByte] && ByteValues[DestByte] != SI->getOperand(0))
+ return true;
+ ByteValues[DestByte] = SI->getOperand(0);
+ return false;
+}
+
+/// MatchBSwap - Given an OR instruction, check to see if this is a bswap idiom.
+/// If so, insert the new bswap intrinsic and return it.
+Instruction *InstCombiner::MatchBSwap(BinaryOperator &I) {
+ const IntegerType *ITy = dyn_cast<IntegerType>(I.getType());
+ if (!ITy || ITy->getBitWidth() % 16)
+ return 0; // Can only bswap pairs of bytes. Can't do vectors.
+
+ /// ByteValues - For each byte of the result, we keep track of which value
+ /// defines each byte.
+ SmallVector<Value*, 8> ByteValues;
+ ByteValues.resize(ITy->getBitWidth()/8);
+
+ // Try to find all the pieces corresponding to the bswap.
+ if (CollectBSwapParts(I.getOperand(0), ByteValues) ||
+ CollectBSwapParts(I.getOperand(1), ByteValues))
+ return 0;
+
+ // Check to see if all of the bytes come from the same value.
+ Value *V = ByteValues[0];
+ if (V == 0) return 0; // Didn't find a byte? Must be zero.
+
+ // Check to make sure that all of the bytes come from the same value.
+ for (unsigned i = 1, e = ByteValues.size(); i != e; ++i)
+ if (ByteValues[i] != V)
+ return 0;
+ const Type *Tys[] = { ITy, ITy };
+ Module *M = I.getParent()->getParent()->getParent();
+ Function *F = Intrinsic::getDeclaration(M, Intrinsic::bswap, Tys, 2);
+ return new CallInst(F, V);
+}
+
+
+Instruction *InstCombiner::visitOr(BinaryOperator &I) {
+ bool Changed = SimplifyCommutative(I);
+ Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
+
+ if (isa<UndefValue>(Op1)) // X | undef -> -1
+ return ReplaceInstUsesWith(I, Constant::getAllOnesValue(I.getType()));
+
+ // or X, X = X
+ if (Op0 == Op1)
+ return ReplaceInstUsesWith(I, Op0);
+
+ // See if we can simplify any instructions used by the instruction whose sole
+ // purpose is to compute bits we don't care about.
+ if (!isa<VectorType>(I.getType())) {
+ uint32_t BitWidth = cast<IntegerType>(I.getType())->getBitWidth();
+ APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
+ if (SimplifyDemandedBits(&I, APInt::getAllOnesValue(BitWidth),
+ KnownZero, KnownOne))
+ return &I;
+ } else if (isa<ConstantAggregateZero>(Op1)) {
+ return ReplaceInstUsesWith(I, Op0); // X | <0,0> -> X
+ } else if (ConstantVector *CP = dyn_cast<ConstantVector>(Op1)) {
+ if (CP->isAllOnesValue()) // X | <-1,-1> -> <-1,-1>
+ return ReplaceInstUsesWith(I, I.getOperand(1));
+ }
+
+
+
+ // or X, -1 == -1
+ if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
+ ConstantInt *C1 = 0; Value *X = 0;
+ // (X & C1) | C2 --> (X | C2) & (C1|C2)
+ if (match(Op0, m_And(m_Value(X), m_ConstantInt(C1))) && isOnlyUse(Op0)) {
+ Instruction *Or = BinaryOperator::createOr(X, RHS);
+ InsertNewInstBefore(Or, I);
+ Or->takeName(Op0);
+ return BinaryOperator::createAnd(Or,
+ ConstantInt::get(RHS->getValue() | C1->getValue()));
+ }
+
+ // (X ^ C1) | C2 --> (X | C2) ^ (C1&~C2)
+ if (match(Op0, m_Xor(m_Value(X), m_ConstantInt(C1))) && isOnlyUse(Op0)) {
+ Instruction *Or = BinaryOperator::createOr(X, RHS);
+ InsertNewInstBefore(Or, I);
+ Or->takeName(Op0);
+ return BinaryOperator::createXor(Or,
+ ConstantInt::get(C1->getValue() & ~RHS->getValue()));
+ }
+
+ // Try to fold constant and into select arguments.
+ if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
+ if (Instruction *R = FoldOpIntoSelect(I, SI, this))
+ return R;
+ if (isa<PHINode>(Op0))
+ if (Instruction *NV = FoldOpIntoPhi(I))
+ return NV;
+ }
+
+ Value *A = 0, *B = 0;
+ ConstantInt *C1 = 0, *C2 = 0;
+
+ if (match(Op0, m_And(m_Value(A), m_Value(B))))
+ if (A == Op1 || B == Op1) // (A & ?) | A --> A
+ return ReplaceInstUsesWith(I, Op1);
+ if (match(Op1, m_And(m_Value(A), m_Value(B))))
+ if (A == Op0 || B == Op0) // A | (A & ?) --> A
+ return ReplaceInstUsesWith(I, Op0);
+
+ // (A | B) | C and A | (B | C) -> bswap if possible.
+ // (A >> B) | (C << D) and (A << B) | (B >> C) -> bswap if possible.
+ if (match(Op0, m_Or(m_Value(), m_Value())) ||
+ match(Op1, m_Or(m_Value(), m_Value())) ||
+ (match(Op0, m_Shift(m_Value(), m_Value())) &&
+ match(Op1, m_Shift(m_Value(), m_Value())))) {
+ if (Instruction *BSwap = MatchBSwap(I))
+ return BSwap;
+ }
+
+ // (X^C)|Y -> (X|Y)^C iff Y&C == 0
+ if (Op0->hasOneUse() && match(Op0, m_Xor(m_Value(A), m_ConstantInt(C1))) &&
+ MaskedValueIsZero(Op1, C1->getValue())) {
+ Instruction *NOr = BinaryOperator::createOr(A, Op1);
+ InsertNewInstBefore(NOr, I);
+ NOr->takeName(Op0);
+ return BinaryOperator::createXor(NOr, C1);
+ }
+
+ // Y|(X^C) -> (X|Y)^C iff Y&C == 0
+ if (Op1->hasOneUse() && match(Op1, m_Xor(m_Value(A), m_ConstantInt(C1))) &&
+ MaskedValueIsZero(Op0, C1->getValue())) {
+ Instruction *NOr = BinaryOperator::createOr(A, Op0);
+ InsertNewInstBefore(NOr, I);
+ NOr->takeName(Op0);
+ return BinaryOperator::createXor(NOr, C1);
+ }
+
+ // (A & C)|(B & D)
+ Value *C = 0, *D = 0;
+ if (match(Op0, m_And(m_Value(A), m_Value(C))) &&
+ match(Op1, m_And(m_Value(B), m_Value(D)))) {
+ Value *V1 = 0, *V2 = 0, *V3 = 0;
+ C1 = dyn_cast<ConstantInt>(C);
+ C2 = dyn_cast<ConstantInt>(D);
+ if (C1 && C2) { // (A & C1)|(B & C2)
+ // If we have: ((V + N) & C1) | (V & C2)
+ // .. and C2 = ~C1 and C2 is 0+1+ and (N & C2) == 0
+ // replace with V+N.
+ if (C1->getValue() == ~C2->getValue()) {
+ if ((C2->getValue() & (C2->getValue()+1)) == 0 && // C2 == 0+1+
+ match(A, m_Add(m_Value(V1), m_Value(V2)))) {
+ // Add commutes, try both ways.
+ if (V1 == B && MaskedValueIsZero(V2, C2->getValue()))
+ return ReplaceInstUsesWith(I, A);
+ if (V2 == B && MaskedValueIsZero(V1, C2->getValue()))
+ return ReplaceInstUsesWith(I, A);
+ }
+ // Or commutes, try both ways.
+ if ((C1->getValue() & (C1->getValue()+1)) == 0 &&
+ match(B, m_Add(m_Value(V1), m_Value(V2)))) {
+ // Add commutes, try both ways.
+ if (V1 == A && MaskedValueIsZero(V2, C1->getValue()))
+ return ReplaceInstUsesWith(I, B);
+ if (V2 == A && MaskedValueIsZero(V1, C1->getValue()))
+ return ReplaceInstUsesWith(I, B);
+ }
+ }
+ V1 = 0; V2 = 0; V3 = 0;
+ }
+
+ // Check to see if we have any common things being and'ed. If so, find the
+ // terms for V1 & (V2|V3).
+ if (isOnlyUse(Op0) || isOnlyUse(Op1)) {
+ if (A == B) // (A & C)|(A & D) == A & (C|D)
+ V1 = A, V2 = C, V3 = D;
+ else if (A == D) // (A & C)|(B & A) == A & (B|C)
+ V1 = A, V2 = B, V3 = C;
+ else if (C == B) // (A & C)|(C & D) == C & (A|D)
+ V1 = C, V2 = A, V3 = D;
+ else if (C == D) // (A & C)|(B & C) == C & (A|B)
+ V1 = C, V2 = A, V3 = B;
+
+ if (V1) {
+ Value *Or =
+ InsertNewInstBefore(BinaryOperator::createOr(V2, V3, "tmp"), I);
+ return BinaryOperator::createAnd(V1, Or);
+ }
+
+ // (V1 & V3)|(V2 & ~V3) -> ((V1 ^ V2) & V3) ^ V2
+ if (isOnlyUse(Op0) && isOnlyUse(Op1)) {
+ // Try all combination of terms to find V3 and ~V3.
+ if (A->hasOneUse() && match(A, m_Not(m_Value(V3)))) {
+ if (V3 == B)
+ V1 = D, V2 = C;
+ else if (V3 == D)
+ V1 = B, V2 = C;
+ }
+ if (B->hasOneUse() && match(B, m_Not(m_Value(V3)))) {
+ if (V3 == A)
+ V1 = C, V2 = D;
+ else if (V3 == C)
+ V1 = A, V2 = D;
+ }
+ if (C->hasOneUse() && match(C, m_Not(m_Value(V3)))) {
+ if (V3 == B)
+ V1 = D, V2 = A;
+ else if (V3 == D)
+ V1 = B, V2 = A;
+ }
+ if (D->hasOneUse() && match(D, m_Not(m_Value(V3)))) {
+ if (V3 == A)
+ V1 = C, V2 = B;
+ else if (V3 == C)
+ V1 = A, V2 = B;
+ }
+ if (V1) {
+ A = InsertNewInstBefore(BinaryOperator::createXor(V1, V2, "tmp"), I);
+ A = InsertNewInstBefore(BinaryOperator::createAnd(A, V3, "tmp"), I);
+ return BinaryOperator::createXor(A, V2);
+ }
+ }
+ }
+ }
+
+ // (X >> Z) | (Y >> Z) -> (X|Y) >> Z for all shifts.
+ if (BinaryOperator *SI1 = dyn_cast<BinaryOperator>(Op1)) {
+ if (BinaryOperator *SI0 = dyn_cast<BinaryOperator>(Op0))
+ if (SI0->isShift() && SI0->getOpcode() == SI1->getOpcode() &&
+ SI0->getOperand(1) == SI1->getOperand(1) &&
+ (SI0->hasOneUse() || SI1->hasOneUse())) {
+ Instruction *NewOp =
+ InsertNewInstBefore(BinaryOperator::createOr(SI0->getOperand(0),
+ SI1->getOperand(0),
+ SI0->getName()), I);
+ return BinaryOperator::create(SI1->getOpcode(), NewOp,
+ SI1->getOperand(1));
+ }
+ }
+
+ if (match(Op0, m_Not(m_Value(A)))) { // ~A | Op1
+ if (A == Op1) // ~A | A == -1
+ return ReplaceInstUsesWith(I, Constant::getAllOnesValue(I.getType()));
+ } else {
+ A = 0;
+ }
+ // Note, A is still live here!
+ if (match(Op1, m_Not(m_Value(B)))) { // Op0 | ~B
+ if (Op0 == B)
+ return ReplaceInstUsesWith(I, Constant::getAllOnesValue(I.getType()));
+
+ // (~A | ~B) == (~(A & B)) - De Morgan's Law
+ if (A && isOnlyUse(Op0) && isOnlyUse(Op1)) {
+ Value *And = InsertNewInstBefore(BinaryOperator::createAnd(A, B,
+ I.getName()+".demorgan"), I);
+ return BinaryOperator::createNot(And);
+ }
+ }
+
+ // (icmp1 A, B) | (icmp2 A, B) --> (icmp3 A, B)
+ if (ICmpInst *RHS = dyn_cast<ICmpInst>(I.getOperand(1))) {
+ if (Instruction *R = AssociativeOpt(I, FoldICmpLogical(*this, RHS)))
+ return R;
+
+ Value *LHSVal, *RHSVal;
+ ConstantInt *LHSCst, *RHSCst;
+ ICmpInst::Predicate LHSCC, RHSCC;
+ if (match(Op0, m_ICmp(LHSCC, m_Value(LHSVal), m_ConstantInt(LHSCst))))
+ if (match(RHS, m_ICmp(RHSCC, m_Value(RHSVal), m_ConstantInt(RHSCst))))
+ if (LHSVal == RHSVal && // Found (X icmp C1) | (X icmp C2)
+ // icmp [us][gl]e x, cst is folded to icmp [us][gl]t elsewhere.
+ LHSCC != ICmpInst::ICMP_UGE && LHSCC != ICmpInst::ICMP_ULE &&
+ RHSCC != ICmpInst::ICMP_UGE && RHSCC != ICmpInst::ICMP_ULE &&
+ LHSCC != ICmpInst::ICMP_SGE && LHSCC != ICmpInst::ICMP_SLE &&
+ RHSCC != ICmpInst::ICMP_SGE && RHSCC != ICmpInst::ICMP_SLE &&
+ // We can't fold (ugt x, C) | (sgt x, C2).
+ PredicatesFoldable(LHSCC, RHSCC)) {
+ // Ensure that the larger constant is on the RHS.
+ ICmpInst *LHS = cast<ICmpInst>(Op0);
+ bool NeedsSwap;
+ if (ICmpInst::isSignedPredicate(LHSCC))
+ NeedsSwap = LHSCst->getValue().sgt(RHSCst->getValue());
+ else
+ NeedsSwap = LHSCst->getValue().ugt(RHSCst->getValue());
+
+ if (NeedsSwap) {
+ std::swap(LHS, RHS);
+ std::swap(LHSCst, RHSCst);
+ std::swap(LHSCC, RHSCC);
+ }
+
+ // At this point, we know we have have two icmp instructions
+ // comparing a value against two constants and or'ing the result
+ // together. Because of the above check, we know that we only have
+ // ICMP_EQ, ICMP_NE, ICMP_LT, and ICMP_GT here. We also know (from the
+ // FoldICmpLogical check above), that the two constants are not
+ // equal.
+ assert(LHSCst != RHSCst && "Compares not folded above?");
+
+ switch (LHSCC) {
+ default: assert(0 && "Unknown integer condition code!");
+ case ICmpInst::ICMP_EQ:
+ switch (RHSCC) {
+ default: assert(0 && "Unknown integer condition code!");
+ case ICmpInst::ICMP_EQ:
+ if (LHSCst == SubOne(RHSCst)) {// (X == 13 | X == 14) -> X-13 <u 2
+ Constant *AddCST = ConstantExpr::getNeg(LHSCst);
+ Instruction *Add = BinaryOperator::createAdd(LHSVal, AddCST,
+ LHSVal->getName()+".off");
+ InsertNewInstBefore(Add, I);
+ AddCST = Subtract(AddOne(RHSCst), LHSCst);
+ return new ICmpInst(ICmpInst::ICMP_ULT, Add, AddCST);
+ }
+ break; // (X == 13 | X == 15) -> no change
+ case ICmpInst::ICMP_UGT: // (X == 13 | X u> 14) -> no change
+ case ICmpInst::ICMP_SGT: // (X == 13 | X s> 14) -> no change
+ break;
+ case ICmpInst::ICMP_NE: // (X == 13 | X != 15) -> X != 15
+ case ICmpInst::ICMP_ULT: // (X == 13 | X u< 15) -> X u< 15
+ case ICmpInst::ICMP_SLT: // (X == 13 | X s< 15) -> X s< 15
+ return ReplaceInstUsesWith(I, RHS);
+ }
+ break;
+ case ICmpInst::ICMP_NE:
+ switch (RHSCC) {
+ default: assert(0 && "Unknown integer condition code!");
+ case ICmpInst::ICMP_EQ: // (X != 13 | X == 15) -> X != 13
+ case ICmpInst::ICMP_UGT: // (X != 13 | X u> 15) -> X != 13
+ case ICmpInst::ICMP_SGT: // (X != 13 | X s> 15) -> X != 13
+ return ReplaceInstUsesWith(I, LHS);
+ case ICmpInst::ICMP_NE: // (X != 13 | X != 15) -> true
+ case ICmpInst::ICMP_ULT: // (X != 13 | X u< 15) -> true
+ case ICmpInst::ICMP_SLT: // (X != 13 | X s< 15) -> true
+ return ReplaceInstUsesWith(I, ConstantInt::getTrue());
+ }
+ break;
+ case ICmpInst::ICMP_ULT:
+ switch (RHSCC) {
+ default: assert(0 && "Unknown integer condition code!");
+ case ICmpInst::ICMP_EQ: // (X u< 13 | X == 14) -> no change
+ break;
+ case ICmpInst::ICMP_UGT: // (X u< 13 | X u> 15) ->(X-13) u> 2
+ return InsertRangeTest(LHSVal, LHSCst, AddOne(RHSCst), false,
+ false, I);
+ case ICmpInst::ICMP_SGT: // (X u< 13 | X s> 15) -> no change
+ break;
+ case ICmpInst::ICMP_NE: // (X u< 13 | X != 15) -> X != 15
+ case ICmpInst::ICMP_ULT: // (X u< 13 | X u< 15) -> X u< 15
+ return ReplaceInstUsesWith(I, RHS);
+ case ICmpInst::ICMP_SLT: // (X u< 13 | X s< 15) -> no change
+ break;
+ }
+ break;
+ case ICmpInst::ICMP_SLT:
+ switch (RHSCC) {
+ default: assert(0 && "Unknown integer condition code!");
+ case ICmpInst::ICMP_EQ: // (X s< 13 | X == 14) -> no change
+ break;
+ case ICmpInst::ICMP_SGT: // (X s< 13 | X s> 15) ->(X-13) s> 2
+ return InsertRangeTest(LHSVal, LHSCst, AddOne(RHSCst), true,
+ false, I);
+ case ICmpInst::ICMP_UGT: // (X s< 13 | X u> 15) -> no change
+ break;
+ case ICmpInst::ICMP_NE: // (X s< 13 | X != 15) -> X != 15
+ case ICmpInst::ICMP_SLT: // (X s< 13 | X s< 15) -> X s< 15
+ return ReplaceInstUsesWith(I, RHS);
+ case ICmpInst::ICMP_ULT: // (X s< 13 | X u< 15) -> no change
+ break;
+ }
+ break;
+ case ICmpInst::ICMP_UGT:
+ switch (RHSCC) {
+ default: assert(0 && "Unknown integer condition code!");
+ case ICmpInst::ICMP_EQ: // (X u> 13 | X == 15) -> X u> 13
+ case ICmpInst::ICMP_UGT: // (X u> 13 | X u> 15) -> X u> 13
+ return ReplaceInstUsesWith(I, LHS);
+ case ICmpInst::ICMP_SGT: // (X u> 13 | X s> 15) -> no change
+ break;
+ case ICmpInst::ICMP_NE: // (X u> 13 | X != 15) -> true
+ case ICmpInst::ICMP_ULT: // (X u> 13 | X u< 15) -> true
+ return ReplaceInstUsesWith(I, ConstantInt::getTrue());
+ case ICmpInst::ICMP_SLT: // (X u> 13 | X s< 15) -> no change
+ break;
+ }
+ break;
+ case ICmpInst::ICMP_SGT:
+ switch (RHSCC) {
+ default: assert(0 && "Unknown integer condition code!");
+ case ICmpInst::ICMP_EQ: // (X s> 13 | X == 15) -> X > 13
+ case ICmpInst::ICMP_SGT: // (X s> 13 | X s> 15) -> X > 13
+ return ReplaceInstUsesWith(I, LHS);
+ case ICmpInst::ICMP_UGT: // (X s> 13 | X u> 15) -> no change
+ break;
+ case ICmpInst::ICMP_NE: // (X s> 13 | X != 15) -> true
+ case ICmpInst::ICMP_SLT: // (X s> 13 | X s< 15) -> true
+ return ReplaceInstUsesWith(I, ConstantInt::getTrue());
+ case ICmpInst::ICMP_ULT: // (X s> 13 | X u< 15) -> no change
+ break;
+ }
+ break;
+ }
+ }
+ }
+
+ // fold (or (cast A), (cast B)) -> (cast (or A, B))
+ if (CastInst *Op0C = dyn_cast<CastInst>(Op0))
+ if (CastInst *Op1C = dyn_cast<CastInst>(Op1))
+ if (Op0C->getOpcode() == Op1C->getOpcode()) {// same cast kind ?
+ const Type *SrcTy = Op0C->getOperand(0)->getType();
+ if (SrcTy == Op1C->getOperand(0)->getType() && SrcTy->isInteger() &&
+ // Only do this if the casts both really cause code to be generated.
+ ValueRequiresCast(Op0C->getOpcode(), Op0C->getOperand(0),
+ I.getType(), TD) &&
+ ValueRequiresCast(Op1C->getOpcode(), Op1C->getOperand(0),
+ I.getType(), TD)) {
+ Instruction *NewOp = BinaryOperator::createOr(Op0C->getOperand(0),
+ Op1C->getOperand(0),
+ I.getName());
+ InsertNewInstBefore(NewOp, I);
+ return CastInst::create(Op0C->getOpcode(), NewOp, I.getType());
+ }
+ }
+
+
+ return Changed ? &I : 0;
+}
+
+// XorSelf - Implements: X ^ X --> 0
+struct XorSelf {
+ Value *RHS;
+ XorSelf(Value *rhs) : RHS(rhs) {}
+ bool shouldApply(Value *LHS) const { return LHS == RHS; }
+ Instruction *apply(BinaryOperator &Xor) const {
+ return &Xor;
+ }
+};
+
+
+Instruction *InstCombiner::visitXor(BinaryOperator &I) {
+ bool Changed = SimplifyCommutative(I);
+ Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
+
+ if (isa<UndefValue>(Op1))
+ return ReplaceInstUsesWith(I, Op1); // X ^ undef -> undef
+
+ // xor X, X = 0, even if X is nested in a sequence of Xor's.
+ if (Instruction *Result = AssociativeOpt(I, XorSelf(Op1))) {
+ assert(Result == &I && "AssociativeOpt didn't work?");
+ return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
+ }
+
+ // See if we can simplify any instructions used by the instruction whose sole
+ // purpose is to compute bits we don't care about.
+ if (!isa<VectorType>(I.getType())) {
+ uint32_t BitWidth = cast<IntegerType>(I.getType())->getBitWidth();
+ APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
+ if (SimplifyDemandedBits(&I, APInt::getAllOnesValue(BitWidth),
+ KnownZero, KnownOne))
+ return &I;
+ } else if (isa<ConstantAggregateZero>(Op1)) {
+ return ReplaceInstUsesWith(I, Op0); // X ^ <0,0> -> X
+ }
+
+ // Is this a ~ operation?
+ if (Value *NotOp = dyn_castNotVal(&I)) {
+ // ~(~X & Y) --> (X | ~Y) - De Morgan's Law
+ // ~(~X | Y) === (X & ~Y) - De Morgan's Law
+ if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(NotOp)) {
+ if (Op0I->getOpcode() == Instruction::And ||
+ Op0I->getOpcode() == Instruction::Or) {
+ if (dyn_castNotVal(Op0I->getOperand(1))) Op0I->swapOperands();
+ if (Value *Op0NotVal = dyn_castNotVal(Op0I->getOperand(0))) {
+ Instruction *NotY =
+ BinaryOperator::createNot(Op0I->getOperand(1),
+ Op0I->getOperand(1)->getName()+".not");
+ InsertNewInstBefore(NotY, I);
+ if (Op0I->getOpcode() == Instruction::And)
+ return BinaryOperator::createOr(Op0NotVal, NotY);
+ else
+ return BinaryOperator::createAnd(Op0NotVal, NotY);
+ }
+ }
+ }
+ }
+
+
+ if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
+ // xor (icmp A, B), true = not (icmp A, B) = !icmp A, B
+ if (ICmpInst *ICI = dyn_cast<ICmpInst>(Op0))
+ if (RHS == ConstantInt::getTrue() && ICI->hasOneUse())
+ return new ICmpInst(ICI->getInversePredicate(),
+ ICI->getOperand(0), ICI->getOperand(1));
+
+ if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) {
+ // ~(c-X) == X-c-1 == X+(-c-1)
+ if (Op0I->getOpcode() == Instruction::Sub && RHS->isAllOnesValue())
+ if (Constant *Op0I0C = dyn_cast<Constant>(Op0I->getOperand(0))) {
+ Constant *NegOp0I0C = ConstantExpr::getNeg(Op0I0C);
+ Constant *ConstantRHS = ConstantExpr::getSub(NegOp0I0C,
+ ConstantInt::get(I.getType(), 1));
+ return BinaryOperator::createAdd(Op0I->getOperand(1), ConstantRHS);
+ }
+
+ if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1)))
+ if (Op0I->getOpcode() == Instruction::Add) {
+ // ~(X-c) --> (-c-1)-X
+ if (RHS->isAllOnesValue()) {
+ Constant *NegOp0CI = ConstantExpr::getNeg(Op0CI);
+ return BinaryOperator::createSub(
+ ConstantExpr::getSub(NegOp0CI,
+ ConstantInt::get(I.getType(), 1)),
+ Op0I->getOperand(0));
+ } else if (RHS->getValue().isSignBit()) {
+ // (X + C) ^ signbit -> (X + C + signbit)
+ Constant *C = ConstantInt::get(RHS->getValue() + Op0CI->getValue());
+ return BinaryOperator::createAdd(Op0I->getOperand(0), C);
+
+ }
+ } else if (Op0I->getOpcode() == Instruction::Or) {
+ // (X|C1)^C2 -> X^(C1|C2) iff X&~C1 == 0
+ if (MaskedValueIsZero(Op0I->getOperand(0), Op0CI->getValue())) {
+ Constant *NewRHS = ConstantExpr::getOr(Op0CI, RHS);
+ // Anything in both C1 and C2 is known to be zero, remove it from
+ // NewRHS.
+ Constant *CommonBits = And(Op0CI, RHS);
+ NewRHS = ConstantExpr::getAnd(NewRHS,
+ ConstantExpr::getNot(CommonBits));
+ AddToWorkList(Op0I);
+ I.setOperand(0, Op0I->getOperand(0));
+ I.setOperand(1, NewRHS);
+ return &I;
+ }
+ }
+ }
+
+ // Try to fold constant and into select arguments.
+ if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
+ if (Instruction *R = FoldOpIntoSelect(I, SI, this))
+ return R;
+ if (isa<PHINode>(Op0))
+ if (Instruction *NV = FoldOpIntoPhi(I))
+ return NV;
+ }
+
+ if (Value *X = dyn_castNotVal(Op0)) // ~A ^ A == -1
+ if (X == Op1)
+ return ReplaceInstUsesWith(I, Constant::getAllOnesValue(I.getType()));
+
+ if (Value *X = dyn_castNotVal(Op1)) // A ^ ~A == -1
+ if (X == Op0)
+ return ReplaceInstUsesWith(I, Constant::getAllOnesValue(I.getType()));
+
+
+ BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1);
+ if (Op1I) {
+ Value *A, *B;
+ if (match(Op1I, m_Or(m_Value(A), m_Value(B)))) {
+ if (A == Op0) { // B^(B|A) == (A|B)^B
+ Op1I->swapOperands();
+ I.swapOperands();
+ std::swap(Op0, Op1);
+ } else if (B == Op0) { // B^(A|B) == (A|B)^B
+ I.swapOperands(); // Simplified below.
+ std::swap(Op0, Op1);
+ }
+ } else if (match(Op1I, m_Xor(m_Value(A), m_Value(B)))) {
+ if (Op0 == A) // A^(A^B) == B
+ return ReplaceInstUsesWith(I, B);
+ else if (Op0 == B) // A^(B^A) == B
+ return ReplaceInstUsesWith(I, A);
+ } else if (match(Op1I, m_And(m_Value(A), m_Value(B))) && Op1I->hasOneUse()){
+ if (A == Op0) { // A^(A&B) -> A^(B&A)
+ Op1I->swapOperands();
+ std::swap(A, B);
+ }
+ if (B == Op0) { // A^(B&A) -> (B&A)^A
+ I.swapOperands(); // Simplified below.
+ std::swap(Op0, Op1);
+ }
+ }
+ }
+
+ BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0);
+ if (Op0I) {
+ Value *A, *B;
+ if (match(Op0I, m_Or(m_Value(A), m_Value(B))) && Op0I->hasOneUse()) {
+ if (A == Op1) // (B|A)^B == (A|B)^B
+ std::swap(A, B);
+ if (B == Op1) { // (A|B)^B == A & ~B
+ Instruction *NotB =
+ InsertNewInstBefore(BinaryOperator::createNot(Op1, "tmp"), I);
+ return BinaryOperator::createAnd(A, NotB);
+ }
+ } else if (match(Op0I, m_Xor(m_Value(A), m_Value(B)))) {
+ if (Op1 == A) // (A^B)^A == B
+ return ReplaceInstUsesWith(I, B);
+ else if (Op1 == B) // (B^A)^A == B
+ return ReplaceInstUsesWith(I, A);
+ } else if (match(Op0I, m_And(m_Value(A), m_Value(B))) && Op0I->hasOneUse()){
+ if (A == Op1) // (A&B)^A -> (B&A)^A
+ std::swap(A, B);
+ if (B == Op1 && // (B&A)^A == ~B & A
+ !isa<ConstantInt>(Op1)) { // Canonical form is (B&C)^C
+ Instruction *N =
+ InsertNewInstBefore(BinaryOperator::createNot(A, "tmp"), I);
+ return BinaryOperator::createAnd(N, Op1);
+ }
+ }
+ }
+
+ // (X >> Z) ^ (Y >> Z) -> (X^Y) >> Z for all shifts.
+ if (Op0I && Op1I && Op0I->isShift() &&
+ Op0I->getOpcode() == Op1I->getOpcode() &&
+ Op0I->getOperand(1) == Op1I->getOperand(1) &&
+ (Op1I->hasOneUse() || Op1I->hasOneUse())) {
+ Instruction *NewOp =
+ InsertNewInstBefore(BinaryOperator::createXor(Op0I->getOperand(0),
+ Op1I->getOperand(0),
+ Op0I->getName()), I);
+ return BinaryOperator::create(Op1I->getOpcode(), NewOp,
+ Op1I->getOperand(1));
+ }
+
+ if (Op0I && Op1I) {
+ Value *A, *B, *C, *D;
+ // (A & B)^(A | B) -> A ^ B
+ if (match(Op0I, m_And(m_Value(A), m_Value(B))) &&
+ match(Op1I, m_Or(m_Value(C), m_Value(D)))) {
+ if ((A == C && B == D) || (A == D && B == C))
+ return BinaryOperator::createXor(A, B);
+ }
+ // (A | B)^(A & B) -> A ^ B
+ if (match(Op0I, m_Or(m_Value(A), m_Value(B))) &&
+ match(Op1I, m_And(m_Value(C), m_Value(D)))) {
+ if ((A == C && B == D) || (A == D && B == C))
+ return BinaryOperator::createXor(A, B);
+ }
+
+ // (A & B)^(C & D)
+ if ((Op0I->hasOneUse() || Op1I->hasOneUse()) &&
+ match(Op0I, m_And(m_Value(A), m_Value(B))) &&
+ match(Op1I, m_And(m_Value(C), m_Value(D)))) {
+ // (X & Y)^(X & Y) -> (Y^Z) & X
+ Value *X = 0, *Y = 0, *Z = 0;
+ if (A == C)
+ X = A, Y = B, Z = D;
+ else if (A == D)
+ X = A, Y = B, Z = C;
+ else if (B == C)
+ X = B, Y = A, Z = D;
+ else if (B == D)
+ X = B, Y = A, Z = C;
+
+ if (X) {
+ Instruction *NewOp =
+ InsertNewInstBefore(BinaryOperator::createXor(Y, Z, Op0->getName()), I);
+ return BinaryOperator::createAnd(NewOp, X);
+ }
+ }
+ }
+
+ // (icmp1 A, B) ^ (icmp2 A, B) --> (icmp3 A, B)
+ if (ICmpInst *RHS = dyn_cast<ICmpInst>(I.getOperand(1)))
+ if (Instruction *R = AssociativeOpt(I, FoldICmpLogical(*this, RHS)))
+ return R;
+
+ // fold (xor (cast A), (cast B)) -> (cast (xor A, B))
+ if (CastInst *Op0C = dyn_cast<CastInst>(Op0))
+ if (CastInst *Op1C = dyn_cast<CastInst>(Op1))
+ if (Op0C->getOpcode() == Op1C->getOpcode()) { // same cast kind?
+ const Type *SrcTy = Op0C->getOperand(0)->getType();
+ if (SrcTy == Op1C->getOperand(0)->getType() && SrcTy->isInteger() &&
+ // Only do this if the casts both really cause code to be generated.
+ ValueRequiresCast(Op0C->getOpcode(), Op0C->getOperand(0),
+ I.getType(), TD) &&
+ ValueRequiresCast(Op1C->getOpcode(), Op1C->getOperand(0),
+ I.getType(), TD)) {
+ Instruction *NewOp = BinaryOperator::createXor(Op0C->getOperand(0),
+ Op1C->getOperand(0),
+ I.getName());
+ InsertNewInstBefore(NewOp, I);
+ return CastInst::create(Op0C->getOpcode(), NewOp, I.getType());
+ }
+ }
+
+ return Changed ? &I : 0;
+}
+
+/// AddWithOverflow - Compute Result = In1+In2, returning true if the result
+/// overflowed for this type.
+static bool AddWithOverflow(ConstantInt *&Result, ConstantInt *In1,
+ ConstantInt *In2, bool IsSigned = false) {
+ Result = cast<ConstantInt>(Add(In1, In2));
+
+ if (IsSigned)
+ if (In2->getValue().isNegative())
+ return Result->getValue().sgt(In1->getValue());
+ else
+ return Result->getValue().slt(In1->getValue());
+ else
+ return Result->getValue().ult(In1->getValue());
+}
+
+/// EmitGEPOffset - Given a getelementptr instruction/constantexpr, emit the
+/// code necessary to compute the offset from the base pointer (without adding
+/// in the base pointer). Return the result as a signed integer of intptr size.
+static Value *EmitGEPOffset(User *GEP, Instruction &I, InstCombiner &IC) {
+ TargetData &TD = IC.getTargetData();
+ gep_type_iterator GTI = gep_type_begin(GEP);
+ const Type *IntPtrTy = TD.getIntPtrType();
+ Value *Result = Constant::getNullValue(IntPtrTy);
+
+ // Build a mask for high order bits.
+ unsigned IntPtrWidth = TD.getPointerSize()*8;
+ uint64_t PtrSizeMask = ~0ULL >> (64-IntPtrWidth);
+
+ for (unsigned i = 1, e = GEP->getNumOperands(); i != e; ++i, ++GTI) {
+ Value *Op = GEP->getOperand(i);
+ uint64_t Size = TD.getTypeSize(GTI.getIndexedType()) & PtrSizeMask;
+ if (ConstantInt *OpC = dyn_cast<ConstantInt>(Op)) {
+ if (OpC->isZero()) continue;
+
+ // Handle a struct index, which adds its field offset to the pointer.
+ if (const StructType *STy = dyn_cast<StructType>(*GTI)) {
+ Size = TD.getStructLayout(STy)->getElementOffset(OpC->getZExtValue());
+
+ if (ConstantInt *RC = dyn_cast<ConstantInt>(Result))
+ Result = ConstantInt::get(RC->getValue() + APInt(IntPtrWidth, Size));
+ else
+ Result = IC.InsertNewInstBefore(
+ BinaryOperator::createAdd(Result,
+ ConstantInt::get(IntPtrTy, Size),
+ GEP->getName()+".offs"), I);
+ continue;
+ }
+
+ Constant *Scale = ConstantInt::get(IntPtrTy, Size);
+ Constant *OC = ConstantExpr::getIntegerCast(OpC, IntPtrTy, true /*SExt*/);
+ Scale = ConstantExpr::getMul(OC, Scale);
+ if (Constant *RC = dyn_cast<Constant>(Result))
+ Result = ConstantExpr::getAdd(RC, Scale);
+ else {
+ // Emit an add instruction.
+ Result = IC.InsertNewInstBefore(
+ BinaryOperator::createAdd(Result, Scale,
+ GEP->getName()+".offs"), I);
+ }
+ continue;
+ }
+ // Convert to correct type.
+ if (Op->getType() != IntPtrTy) {
+ if (Constant *OpC = dyn_cast<Constant>(Op))
+ Op = ConstantExpr::getSExt(OpC, IntPtrTy);
+ else
+ Op = IC.InsertNewInstBefore(new SExtInst(Op, IntPtrTy,
+ Op->getName()+".c"), I);
+ }
+ if (Size != 1) {
+ Constant *Scale = ConstantInt::get(IntPtrTy, Size);
+ if (Constant *OpC = dyn_cast<Constant>(Op))
+ Op = ConstantExpr::getMul(OpC, Scale);
+ else // We'll let instcombine(mul) convert this to a shl if possible.
+ Op = IC.InsertNewInstBefore(BinaryOperator::createMul(Op, Scale,
+ GEP->getName()+".idx"), I);
+ }
+
+ // Emit an add instruction.
+ if (isa<Constant>(Op) && isa<Constant>(Result))
+ Result = ConstantExpr::getAdd(cast<Constant>(Op),
+ cast<Constant>(Result));
+ else
+ Result = IC.InsertNewInstBefore(BinaryOperator::createAdd(Op, Result,
+ GEP->getName()+".offs"), I);
+ }
+ return Result;
+}
+
+/// FoldGEPICmp - Fold comparisons between a GEP instruction and something
+/// else. At this point we know that the GEP is on the LHS of the comparison.
+Instruction *InstCombiner::FoldGEPICmp(User *GEPLHS, Value *RHS,
+ ICmpInst::Predicate Cond,
+ Instruction &I) {
+ assert(dyn_castGetElementPtr(GEPLHS) && "LHS is not a getelementptr!");
+
+ if (CastInst *CI = dyn_cast<CastInst>(RHS))
+ if (isa<PointerType>(CI->getOperand(0)->getType()))
+ RHS = CI->getOperand(0);
+
+ Value *PtrBase = GEPLHS->getOperand(0);
+ if (PtrBase == RHS) {
+ // As an optimization, we don't actually have to compute the actual value of
+ // OFFSET if this is a icmp_eq or icmp_ne comparison, just return whether
+ // each index is zero or not.
+ if (Cond == ICmpInst::ICMP_EQ || Cond == ICmpInst::ICMP_NE) {
+ Instruction *InVal = 0;
+ gep_type_iterator GTI = gep_type_begin(GEPLHS);
+ for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i, ++GTI) {
+ bool EmitIt = true;
+ if (Constant *C = dyn_cast<Constant>(GEPLHS->getOperand(i))) {
+ if (isa<UndefValue>(C)) // undef index -> undef.
+ return ReplaceInstUsesWith(I, UndefValue::get(I.getType()));
+ if (C->isNullValue())
+ EmitIt = false;
+ else if (TD->getTypeSize(GTI.getIndexedType()) == 0) {
+ EmitIt = false; // This is indexing into a zero sized array?
+ } else if (isa<ConstantInt>(C))
+ return ReplaceInstUsesWith(I, // No comparison is needed here.
+ ConstantInt::get(Type::Int1Ty,
+ Cond == ICmpInst::ICMP_NE));
+ }
+
+ if (EmitIt) {
+ Instruction *Comp =
+ new ICmpInst(Cond, GEPLHS->getOperand(i),
+ Constant::getNullValue(GEPLHS->getOperand(i)->getType()));
+ if (InVal == 0)
+ InVal = Comp;
+ else {
+ InVal = InsertNewInstBefore(InVal, I);
+ InsertNewInstBefore(Comp, I);
+ if (Cond == ICmpInst::ICMP_NE) // True if any are unequal
+ InVal = BinaryOperator::createOr(InVal, Comp);
+ else // True if all are equal
+ InVal = BinaryOperator::createAnd(InVal, Comp);
+ }
+ }
+ }
+
+ if (InVal)
+ return InVal;
+ else
+ // No comparison is needed here, all indexes = 0
+ ReplaceInstUsesWith(I, ConstantInt::get(Type::Int1Ty,
+ Cond == ICmpInst::ICMP_EQ));
+ }
+
+ // Only lower this if the icmp is the only user of the GEP or if we expect
+ // the result to fold to a constant!
+ if (isa<ConstantExpr>(GEPLHS) || GEPLHS->hasOneUse()) {
+ // ((gep Ptr, OFFSET) cmp Ptr) ---> (OFFSET cmp 0).
+ Value *Offset = EmitGEPOffset(GEPLHS, I, *this);
+ return new ICmpInst(ICmpInst::getSignedPredicate(Cond), Offset,
+ Constant::getNullValue(Offset->getType()));
+ }
+ } else if (User *GEPRHS = dyn_castGetElementPtr(RHS)) {
+ // If the base pointers are different, but the indices are the same, just
+ // compare the base pointer.
+ if (PtrBase != GEPRHS->getOperand(0)) {
+ bool IndicesTheSame = GEPLHS->getNumOperands()==GEPRHS->getNumOperands();
+ IndicesTheSame &= GEPLHS->getOperand(0)->getType() ==
+ GEPRHS->getOperand(0)->getType();
+ if (IndicesTheSame)
+ for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i)
+ if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) {
+ IndicesTheSame = false;
+ break;
+ }
+
+ // If all indices are the same, just compare the base pointers.
+ if (IndicesTheSame)
+ return new ICmpInst(ICmpInst::getSignedPredicate(Cond),
+ GEPLHS->getOperand(0), GEPRHS->getOperand(0));
+
+ // Otherwise, the base pointers are different and the indices are
+ // different, bail out.
+ return 0;
+ }
+
+ // If one of the GEPs has all zero indices, recurse.
+ bool AllZeros = true;
+ for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i)
+ if (!isa<Constant>(GEPLHS->getOperand(i)) ||
+ !cast<Constant>(GEPLHS->getOperand(i))->isNullValue()) {
+ AllZeros = false;
+ break;
+ }
+ if (AllZeros)
+ return FoldGEPICmp(GEPRHS, GEPLHS->getOperand(0),
+ ICmpInst::getSwappedPredicate(Cond), I);
+
+ // If the other GEP has all zero indices, recurse.
+ AllZeros = true;
+ for (unsigned i = 1, e = GEPRHS->getNumOperands(); i != e; ++i)
+ if (!isa<Constant>(GEPRHS->getOperand(i)) ||
+ !cast<Constant>(GEPRHS->getOperand(i))->isNullValue()) {
+ AllZeros = false;
+ break;
+ }
+ if (AllZeros)
+ return FoldGEPICmp(GEPLHS, GEPRHS->getOperand(0), Cond, I);
+
+ if (GEPLHS->getNumOperands() == GEPRHS->getNumOperands()) {
+ // If the GEPs only differ by one index, compare it.
+ unsigned NumDifferences = 0; // Keep track of # differences.
+ unsigned DiffOperand = 0; // The operand that differs.
+ for (unsigned i = 1, e = GEPRHS->getNumOperands(); i != e; ++i)
+ if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) {
+ if (GEPLHS->getOperand(i)->getType()->getPrimitiveSizeInBits() !=
+ GEPRHS->getOperand(i)->getType()->getPrimitiveSizeInBits()) {
+ // Irreconcilable differences.
+ NumDifferences = 2;
+ break;
+ } else {
+ if (NumDifferences++) break;
+ DiffOperand = i;
+ }
+ }
+
+ if (NumDifferences == 0) // SAME GEP?
+ return ReplaceInstUsesWith(I, // No comparison is needed here.
+ ConstantInt::get(Type::Int1Ty,
+ Cond == ICmpInst::ICMP_EQ));
+ else if (NumDifferences == 1) {
+ Value *LHSV = GEPLHS->getOperand(DiffOperand);
+ Value *RHSV = GEPRHS->getOperand(DiffOperand);
+ // Make sure we do a signed comparison here.
+ return new ICmpInst(ICmpInst::getSignedPredicate(Cond), LHSV, RHSV);
+ }
+ }
+
+ // Only lower this if the icmp is the only user of the GEP or if we expect
+ // the result to fold to a constant!
+ if ((isa<ConstantExpr>(GEPLHS) || GEPLHS->hasOneUse()) &&
+ (isa<ConstantExpr>(GEPRHS) || GEPRHS->hasOneUse())) {
+ // ((gep Ptr, OFFSET1) cmp (gep Ptr, OFFSET2) ---> (OFFSET1 cmp OFFSET2)
+ Value *L = EmitGEPOffset(GEPLHS, I, *this);
+ Value *R = EmitGEPOffset(GEPRHS, I, *this);
+ return new ICmpInst(ICmpInst::getSignedPredicate(Cond), L, R);
+ }
+ }
+ return 0;
+}
+
+Instruction *InstCombiner::visitFCmpInst(FCmpInst &I) {
+ bool Changed = SimplifyCompare(I);
+ Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
+
+ // Fold trivial predicates.
+ if (I.getPredicate() == FCmpInst::FCMP_FALSE)
+ return ReplaceInstUsesWith(I, Constant::getNullValue(Type::Int1Ty));
+ if (I.getPredicate() == FCmpInst::FCMP_TRUE)
+ return ReplaceInstUsesWith(I, ConstantInt::get(Type::Int1Ty, 1));
+
+ // Simplify 'fcmp pred X, X'
+ if (Op0 == Op1) {
+ switch (I.getPredicate()) {
+ default: assert(0 && "Unknown predicate!");
+ case FCmpInst::FCMP_UEQ: // True if unordered or equal
+ case FCmpInst::FCMP_UGE: // True if unordered, greater than, or equal
+ case FCmpInst::FCMP_ULE: // True if unordered, less than, or equal
+ return ReplaceInstUsesWith(I, ConstantInt::get(Type::Int1Ty, 1));
+ case FCmpInst::FCMP_OGT: // True if ordered and greater than
+ case FCmpInst::FCMP_OLT: // True if ordered and less than
+ case FCmpInst::FCMP_ONE: // True if ordered and operands are unequal
+ return ReplaceInstUsesWith(I, ConstantInt::get(Type::Int1Ty, 0));
+
+ case FCmpInst::FCMP_UNO: // True if unordered: isnan(X) | isnan(Y)
+ case FCmpInst::FCMP_ULT: // True if unordered or less than
+ case FCmpInst::FCMP_UGT: // True if unordered or greater than
+ case FCmpInst::FCMP_UNE: // True if unordered or not equal
+ // Canonicalize these to be 'fcmp uno %X, 0.0'.
+ I.setPredicate(FCmpInst::FCMP_UNO);
+ I.setOperand(1, Constant::getNullValue(Op0->getType()));
+ return &I;
+
+ case FCmpInst::FCMP_ORD: // True if ordered (no nans)
+ case FCmpInst::FCMP_OEQ: // True if ordered and equal
+ case FCmpInst::FCMP_OGE: // True if ordered and greater than or equal
+ case FCmpInst::FCMP_OLE: // True if ordered and less than or equal
+ // Canonicalize these to be 'fcmp ord %X, 0.0'.
+ I.setPredicate(FCmpInst::FCMP_ORD);
+ I.setOperand(1, Constant::getNullValue(Op0->getType()));
+ return &I;
+ }
+ }
+
+ if (isa<UndefValue>(Op1)) // fcmp pred X, undef -> undef
+ return ReplaceInstUsesWith(I, UndefValue::get(Type::Int1Ty));
+
+ // Handle fcmp with constant RHS
+ if (Constant *RHSC = dyn_cast<Constant>(Op1)) {
+ if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
+ switch (LHSI->getOpcode()) {
+ case Instruction::PHI:
+ if (Instruction *NV = FoldOpIntoPhi(I))
+ return NV;
+ break;
+ case Instruction::Select:
+ // If either operand of the select is a constant, we can fold the
+ // comparison into the select arms, which will cause one to be
+ // constant folded and the select turned into a bitwise or.
+ Value *Op1 = 0, *Op2 = 0;
+ if (LHSI->hasOneUse()) {
+ if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(1))) {
+ // Fold the known value into the constant operand.
+ Op1 = ConstantExpr::getCompare(I.getPredicate(), C, RHSC);
+ // Insert a new FCmp of the other select operand.
+ Op2 = InsertNewInstBefore(new FCmpInst(I.getPredicate(),
+ LHSI->getOperand(2), RHSC,
+ I.getName()), I);
+ } else if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(2))) {
+ // Fold the known value into the constant operand.
+ Op2 = ConstantExpr::getCompare(I.getPredicate(), C, RHSC);
+ // Insert a new FCmp of the other select operand.
+ Op1 = InsertNewInstBefore(new FCmpInst(I.getPredicate(),
+ LHSI->getOperand(1), RHSC,
+ I.getName()), I);
+ }
+ }
+
+ if (Op1)
+ return new SelectInst(LHSI->getOperand(0), Op1, Op2);
+ break;
+ }
+ }
+
+ return Changed ? &I : 0;
+}
+
+Instruction *InstCombiner::visitICmpInst(ICmpInst &I) {
+ bool Changed = SimplifyCompare(I);
+ Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
+ const Type *Ty = Op0->getType();
+
+ // icmp X, X
+ if (Op0 == Op1)
+ return ReplaceInstUsesWith(I, ConstantInt::get(Type::Int1Ty,
+ isTrueWhenEqual(I)));
+
+ if (isa<UndefValue>(Op1)) // X icmp undef -> undef
+ return ReplaceInstUsesWith(I, UndefValue::get(Type::Int1Ty));
+
+ // icmp of GlobalValues can never equal each other as long as they aren't
+ // external weak linkage type.
+ if (GlobalValue *GV0 = dyn_cast<GlobalValue>(Op0))
+ if (GlobalValue *GV1 = dyn_cast<GlobalValue>(Op1))
+ if (!GV0->hasExternalWeakLinkage() || !GV1->hasExternalWeakLinkage())
+ return ReplaceInstUsesWith(I, ConstantInt::get(Type::Int1Ty,
+ !isTrueWhenEqual(I)));
+
+ // icmp <global/alloca*/null>, <global/alloca*/null> - Global/Stack value
+ // addresses never equal each other! We already know that Op0 != Op1.
+ if ((isa<GlobalValue>(Op0) || isa<AllocaInst>(Op0) ||
+ isa<ConstantPointerNull>(Op0)) &&
+ (isa<GlobalValue>(Op1) || isa<AllocaInst>(Op1) ||
+ isa<ConstantPointerNull>(Op1)))
+ return ReplaceInstUsesWith(I, ConstantInt::get(Type::Int1Ty,
+ !isTrueWhenEqual(I)));
+
+ // icmp's with boolean values can always be turned into bitwise operations
+ if (Ty == Type::Int1Ty) {
+ switch (I.getPredicate()) {
+ default: assert(0 && "Invalid icmp instruction!");
+ case ICmpInst::ICMP_EQ: { // icmp eq bool %A, %B -> ~(A^B)
+ Instruction *Xor = BinaryOperator::createXor(Op0, Op1, I.getName()+"tmp");
+ InsertNewInstBefore(Xor, I);
+ return BinaryOperator::createNot(Xor);
+ }
+ case ICmpInst::ICMP_NE: // icmp eq bool %A, %B -> A^B
+ return BinaryOperator::createXor(Op0, Op1);
+
+ case ICmpInst::ICMP_UGT:
+ case ICmpInst::ICMP_SGT:
+ std::swap(Op0, Op1); // Change icmp gt -> icmp lt
+ // FALL THROUGH
+ case ICmpInst::ICMP_ULT:
+ case ICmpInst::ICMP_SLT: { // icmp lt bool A, B -> ~X & Y
+ Instruction *Not = BinaryOperator::createNot(Op0, I.getName()+"tmp");
+ InsertNewInstBefore(Not, I);
+ return BinaryOperator::createAnd(Not, Op1);
+ }
+ case ICmpInst::ICMP_UGE:
+ case ICmpInst::ICMP_SGE:
+ std::swap(Op0, Op1); // Change icmp ge -> icmp le
+ // FALL THROUGH
+ case ICmpInst::ICMP_ULE:
+ case ICmpInst::ICMP_SLE: { // icmp le bool %A, %B -> ~A | B
+ Instruction *Not = BinaryOperator::createNot(Op0, I.getName()+"tmp");
+ InsertNewInstBefore(Not, I);
+ return BinaryOperator::createOr(Not, Op1);
+ }
+ }
+ }
+
+ // See if we are doing a comparison between a constant and an instruction that
+ // can be folded into the comparison.
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
+ switch (I.getPredicate()) {
+ default: break;
+ case ICmpInst::ICMP_ULT: // A <u MIN -> FALSE
+ if (CI->isMinValue(false))
+ return ReplaceInstUsesWith(I, ConstantInt::getFalse());
+ if (CI->isMaxValue(false)) // A <u MAX -> A != MAX
+ return new ICmpInst(ICmpInst::ICMP_NE, Op0,Op1);
+ if (isMinValuePlusOne(CI,false)) // A <u MIN+1 -> A == MIN
+ return new ICmpInst(ICmpInst::ICMP_EQ, Op0, SubOne(CI));
+ // (x <u 2147483648) -> (x >s -1) -> true if sign bit clear
+ if (CI->isMinValue(true))
+ return new ICmpInst(ICmpInst::ICMP_SGT, Op0,
+ ConstantInt::getAllOnesValue(Op0->getType()));
+
+ break;
+
+ case ICmpInst::ICMP_SLT:
+ if (CI->isMinValue(true)) // A <s MIN -> FALSE
+ return ReplaceInstUsesWith(I, ConstantInt::getFalse());
+ if (CI->isMaxValue(true)) // A <s MAX -> A != MAX
+ return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1);
+ if (isMinValuePlusOne(CI,true)) // A <s MIN+1 -> A == MIN
+ return new ICmpInst(ICmpInst::ICMP_EQ, Op0, SubOne(CI));
+ break;
+
+ case ICmpInst::ICMP_UGT:
+ if (CI->isMaxValue(false)) // A >u MAX -> FALSE
+ return ReplaceInstUsesWith(I, ConstantInt::getFalse());
+ if (CI->isMinValue(false)) // A >u MIN -> A != MIN
+ return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1);
+ if (isMaxValueMinusOne(CI, false)) // A >u MAX-1 -> A == MAX
+ return new ICmpInst(ICmpInst::ICMP_EQ, Op0, AddOne(CI));
+
+ // (x >u 2147483647) -> (x <s 0) -> true if sign bit set
+ if (CI->isMaxValue(true))
+ return new ICmpInst(ICmpInst::ICMP_SLT, Op0,
+ ConstantInt::getNullValue(Op0->getType()));
+ break;
+
+ case ICmpInst::ICMP_SGT:
+ if (CI->isMaxValue(true)) // A >s MAX -> FALSE
+ return ReplaceInstUsesWith(I, ConstantInt::getFalse());
+ if (CI->isMinValue(true)) // A >s MIN -> A != MIN
+ return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1);
+ if (isMaxValueMinusOne(CI, true)) // A >s MAX-1 -> A == MAX
+ return new ICmpInst(ICmpInst::ICMP_EQ, Op0, AddOne(CI));
+ break;
+
+ case ICmpInst::ICMP_ULE:
+ if (CI->isMaxValue(false)) // A <=u MAX -> TRUE
+ return ReplaceInstUsesWith(I, ConstantInt::getTrue());
+ if (CI->isMinValue(false)) // A <=u MIN -> A == MIN
+ return new ICmpInst(ICmpInst::ICMP_EQ, Op0, Op1);
+ if (isMaxValueMinusOne(CI,false)) // A <=u MAX-1 -> A != MAX
+ return new ICmpInst(ICmpInst::ICMP_NE, Op0, AddOne(CI));
+ break;
+
+ case ICmpInst::ICMP_SLE:
+ if (CI->isMaxValue(true)) // A <=s MAX -> TRUE
+ return ReplaceInstUsesWith(I, ConstantInt::getTrue());
+ if (CI->isMinValue(true)) // A <=s MIN -> A == MIN
+ return new ICmpInst(ICmpInst::ICMP_EQ, Op0, Op1);
+ if (isMaxValueMinusOne(CI,true)) // A <=s MAX-1 -> A != MAX
+ return new ICmpInst(ICmpInst::ICMP_NE, Op0, AddOne(CI));
+ break;
+
+ case ICmpInst::ICMP_UGE:
+ if (CI->isMinValue(false)) // A >=u MIN -> TRUE
+ return ReplaceInstUsesWith(I, ConstantInt::getTrue());
+ if (CI->isMaxValue(false)) // A >=u MAX -> A == MAX
+ return new ICmpInst(ICmpInst::ICMP_EQ, Op0, Op1);
+ if (isMinValuePlusOne(CI,false)) // A >=u MIN-1 -> A != MIN
+ return new ICmpInst(ICmpInst::ICMP_NE, Op0, SubOne(CI));
+ break;
+
+ case ICmpInst::ICMP_SGE:
+ if (CI->isMinValue(true)) // A >=s MIN -> TRUE
+ return ReplaceInstUsesWith(I, ConstantInt::getTrue());
+ if (CI->isMaxValue(true)) // A >=s MAX -> A == MAX
+ return new ICmpInst(ICmpInst::ICMP_EQ, Op0, Op1);
+ if (isMinValuePlusOne(CI,true)) // A >=s MIN-1 -> A != MIN
+ return new ICmpInst(ICmpInst::ICMP_NE, Op0, SubOne(CI));
+ break;
+ }
+
+ // If we still have a icmp le or icmp ge instruction, turn it into the
+ // appropriate icmp lt or icmp gt instruction. Since the border cases have
+ // already been handled above, this requires little checking.
+ //
+ switch (I.getPredicate()) {
+ default: break;
+ case ICmpInst::ICMP_ULE:
+ return new ICmpInst(ICmpInst::ICMP_ULT, Op0, AddOne(CI));
+ case ICmpInst::ICMP_SLE:
+ return new ICmpInst(ICmpInst::ICMP_SLT, Op0, AddOne(CI));
+ case ICmpInst::ICMP_UGE:
+ return new ICmpInst( ICmpInst::ICMP_UGT, Op0, SubOne(CI));
+ case ICmpInst::ICMP_SGE:
+ return new ICmpInst(ICmpInst::ICMP_SGT, Op0, SubOne(CI));
+ }
+
+ // See if we can fold the comparison based on bits known to be zero or one
+ // in the input. If this comparison is a normal comparison, it demands all
+ // bits, if it is a sign bit comparison, it only demands the sign bit.
+
+ bool UnusedBit;
+ bool isSignBit = isSignBitCheck(I.getPredicate(), CI, UnusedBit);
+
+ uint32_t BitWidth = cast<IntegerType>(Ty)->getBitWidth();
+ APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
+ if (SimplifyDemandedBits(Op0,
+ isSignBit ? APInt::getSignBit(BitWidth)
+ : APInt::getAllOnesValue(BitWidth),
+ KnownZero, KnownOne, 0))
+ return &I;
+
+ // Given the known and unknown bits, compute a range that the LHS could be
+ // in.
+ if ((KnownOne | KnownZero) != 0) {
+ // Compute the Min, Max and RHS values based on the known bits. For the
+ // EQ and NE we use unsigned values.
+ APInt Min(BitWidth, 0), Max(BitWidth, 0);
+ const APInt& RHSVal = CI->getValue();
+ if (ICmpInst::isSignedPredicate(I.getPredicate())) {
+ ComputeSignedMinMaxValuesFromKnownBits(Ty, KnownZero, KnownOne, Min,
+ Max);
+ } else {
+ ComputeUnsignedMinMaxValuesFromKnownBits(Ty, KnownZero, KnownOne, Min,
+ Max);
+ }
+ switch (I.getPredicate()) { // LE/GE have been folded already.
+ default: assert(0 && "Unknown icmp opcode!");
+ case ICmpInst::ICMP_EQ:
+ if (Max.ult(RHSVal) || Min.ugt(RHSVal))
+ return ReplaceInstUsesWith(I, ConstantInt::getFalse());
+ break;
+ case ICmpInst::ICMP_NE:
+ if (Max.ult(RHSVal) || Min.ugt(RHSVal))
+ return ReplaceInstUsesWith(I, ConstantInt::getTrue());
+ break;
+ case ICmpInst::ICMP_ULT:
+ if (Max.ult(RHSVal))
+ return ReplaceInstUsesWith(I, ConstantInt::getTrue());
+ if (Min.uge(RHSVal))
+ return ReplaceInstUsesWith(I, ConstantInt::getFalse());
+ break;
+ case ICmpInst::ICMP_UGT:
+ if (Min.ugt(RHSVal))
+ return ReplaceInstUsesWith(I, ConstantInt::getTrue());
+ if (Max.ule(RHSVal))
+ return ReplaceInstUsesWith(I, ConstantInt::getFalse());
+ break;
+ case ICmpInst::ICMP_SLT:
+ if (Max.slt(RHSVal))
+ return ReplaceInstUsesWith(I, ConstantInt::getTrue());
+ if (Min.sgt(RHSVal))
+ return ReplaceInstUsesWith(I, ConstantInt::getFalse());
+ break;
+ case ICmpInst::ICMP_SGT:
+ if (Min.sgt(RHSVal))
+ return ReplaceInstUsesWith(I, ConstantInt::getTrue());
+ if (Max.sle(RHSVal))
+ return ReplaceInstUsesWith(I, ConstantInt::getFalse());
+ break;
+ }
+ }
+
+ // Since the RHS is a ConstantInt (CI), if the left hand side is an
+ // instruction, see if that instruction also has constants so that the
+ // instruction can be folded into the icmp
+ if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
+ if (Instruction *Res = visitICmpInstWithInstAndIntCst(I, LHSI, CI))
+ return Res;
+ }
+
+ // Handle icmp with constant (but not simple integer constant) RHS
+ if (Constant *RHSC = dyn_cast<Constant>(Op1)) {
+ if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
+ switch (LHSI->getOpcode()) {
+ case Instruction::GetElementPtr:
+ if (RHSC->isNullValue()) {
+ // icmp pred GEP (P, int 0, int 0, int 0), null -> icmp pred P, null
+ bool isAllZeros = true;
+ for (unsigned i = 1, e = LHSI->getNumOperands(); i != e; ++i)
+ if (!isa<Constant>(LHSI->getOperand(i)) ||
+ !cast<Constant>(LHSI->getOperand(i))->isNullValue()) {
+ isAllZeros = false;
+ break;
+ }
+ if (isAllZeros)
+ return new ICmpInst(I.getPredicate(), LHSI->getOperand(0),
+ Constant::getNullValue(LHSI->getOperand(0)->getType()));
+ }
+ break;
+
+ case Instruction::PHI:
+ if (Instruction *NV = FoldOpIntoPhi(I))
+ return NV;
+ break;
+ case Instruction::Select: {
+ // If either operand of the select is a constant, we can fold the
+ // comparison into the select arms, which will cause one to be
+ // constant folded and the select turned into a bitwise or.
+ Value *Op1 = 0, *Op2 = 0;
+ if (LHSI->hasOneUse()) {
+ if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(1))) {
+ // Fold the known value into the constant operand.
+ Op1 = ConstantExpr::getICmp(I.getPredicate(), C, RHSC);
+ // Insert a new ICmp of the other select operand.
+ Op2 = InsertNewInstBefore(new ICmpInst(I.getPredicate(),
+ LHSI->getOperand(2), RHSC,
+ I.getName()), I);
+ } else if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(2))) {
+ // Fold the known value into the constant operand.
+ Op2 = ConstantExpr::getICmp(I.getPredicate(), C, RHSC);
+ // Insert a new ICmp of the other select operand.
+ Op1 = InsertNewInstBefore(new ICmpInst(I.getPredicate(),
+ LHSI->getOperand(1), RHSC,
+ I.getName()), I);
+ }
+ }
+
+ if (Op1)
+ return new SelectInst(LHSI->getOperand(0), Op1, Op2);
+ break;
+ }
+ case Instruction::Malloc:
+ // If we have (malloc != null), and if the malloc has a single use, we
+ // can assume it is successful and remove the malloc.
+ if (LHSI->hasOneUse() && isa<ConstantPointerNull>(RHSC)) {
+ AddToWorkList(LHSI);
+ return ReplaceInstUsesWith(I, ConstantInt::get(Type::Int1Ty,
+ !isTrueWhenEqual(I)));
+ }
+ break;
+ }
+ }
+
+ // If we can optimize a 'icmp GEP, P' or 'icmp P, GEP', do so now.
+ if (User *GEP = dyn_castGetElementPtr(Op0))
+ if (Instruction *NI = FoldGEPICmp(GEP, Op1, I.getPredicate(), I))
+ return NI;
+ if (User *GEP = dyn_castGetElementPtr(Op1))
+ if (Instruction *NI = FoldGEPICmp(GEP, Op0,
+ ICmpInst::getSwappedPredicate(I.getPredicate()), I))
+ return NI;
+
+ // Test to see if the operands of the icmp are casted versions of other
+ // values. If the ptr->ptr cast can be stripped off both arguments, we do so
+ // now.
+ if (BitCastInst *CI = dyn_cast<BitCastInst>(Op0)) {
+ if (isa<PointerType>(Op0->getType()) &&
+ (isa<Constant>(Op1) || isa<BitCastInst>(Op1))) {
+ // We keep moving the cast from the left operand over to the right
+ // operand, where it can often be eliminated completely.
+ Op0 = CI->getOperand(0);
+
+ // If operand #1 is a bitcast instruction, it must also be a ptr->ptr cast
+ // so eliminate it as well.
+ if (BitCastInst *CI2 = dyn_cast<BitCastInst>(Op1))
+ Op1 = CI2->getOperand(0);
+
+ // If Op1 is a constant, we can fold the cast into the constant.
+ if (Op0->getType() != Op1->getType())
+ if (Constant *Op1C = dyn_cast<Constant>(Op1)) {
+ Op1 = ConstantExpr::getBitCast(Op1C, Op0->getType());
+ } else {
+ // Otherwise, cast the RHS right before the icmp
+ Op1 = InsertCastBefore(Instruction::BitCast, Op1, Op0->getType(), I);
+ }
+ return new ICmpInst(I.getPredicate(), Op0, Op1);
+ }
+ }
+
+ if (isa<CastInst>(Op0)) {
+ // Handle the special case of: icmp (cast bool to X), <cst>
+ // This comes up when you have code like
+ // int X = A < B;
+ // if (X) ...
+ // For generality, we handle any zero-extension of any operand comparison
+ // with a constant or another cast from the same type.
+ if (isa<ConstantInt>(Op1) || isa<CastInst>(Op1))
+ if (Instruction *R = visitICmpInstWithCastAndCast(I))
+ return R;
+ }
+
+ if (I.isEquality()) {
+ Value *A, *B, *C, *D;
+ if (match(Op0, m_Xor(m_Value(A), m_Value(B)))) {
+ if (A == Op1 || B == Op1) { // (A^B) == A -> B == 0
+ Value *OtherVal = A == Op1 ? B : A;
+ return new ICmpInst(I.getPredicate(), OtherVal,
+ Constant::getNullValue(A->getType()));
+ }
+
+ if (match(Op1, m_Xor(m_Value(C), m_Value(D)))) {
+ // A^c1 == C^c2 --> A == C^(c1^c2)
+ if (ConstantInt *C1 = dyn_cast<ConstantInt>(B))
+ if (ConstantInt *C2 = dyn_cast<ConstantInt>(D))
+ if (Op1->hasOneUse()) {
+ Constant *NC = ConstantInt::get(C1->getValue() ^ C2->getValue());
+ Instruction *Xor = BinaryOperator::createXor(C, NC, "tmp");
+ return new ICmpInst(I.getPredicate(), A,
+ InsertNewInstBefore(Xor, I));
+ }
+
+ // A^B == A^D -> B == D
+ if (A == C) return new ICmpInst(I.getPredicate(), B, D);
+ if (A == D) return new ICmpInst(I.getPredicate(), B, C);
+ if (B == C) return new ICmpInst(I.getPredicate(), A, D);
+ if (B == D) return new ICmpInst(I.getPredicate(), A, C);
+ }
+ }
+
+ if (match(Op1, m_Xor(m_Value(A), m_Value(B))) &&
+ (A == Op0 || B == Op0)) {
+ // A == (A^B) -> B == 0
+ Value *OtherVal = A == Op0 ? B : A;
+ return new ICmpInst(I.getPredicate(), OtherVal,
+ Constant::getNullValue(A->getType()));
+ }
+ if (match(Op0, m_Sub(m_Value(A), m_Value(B))) && A == Op1) {
+ // (A-B) == A -> B == 0
+ return new ICmpInst(I.getPredicate(), B,
+ Constant::getNullValue(B->getType()));
+ }
+ if (match(Op1, m_Sub(m_Value(A), m_Value(B))) && A == Op0) {
+ // A == (A-B) -> B == 0
+ return new ICmpInst(I.getPredicate(), B,
+ Constant::getNullValue(B->getType()));
+ }
+
+ // (X&Z) == (Y&Z) -> (X^Y) & Z == 0
+ if (Op0->hasOneUse() && Op1->hasOneUse() &&
+ match(Op0, m_And(m_Value(A), m_Value(B))) &&
+ match(Op1, m_And(m_Value(C), m_Value(D)))) {
+ Value *X = 0, *Y = 0, *Z = 0;
+
+ if (A == C) {
+ X = B; Y = D; Z = A;
+ } else if (A == D) {
+ X = B; Y = C; Z = A;
+ } else if (B == C) {
+ X = A; Y = D; Z = B;
+ } else if (B == D) {
+ X = A; Y = C; Z = B;
+ }
+
+ if (X) { // Build (X^Y) & Z
+ Op1 = InsertNewInstBefore(BinaryOperator::createXor(X, Y, "tmp"), I);
+ Op1 = InsertNewInstBefore(BinaryOperator::createAnd(Op1, Z, "tmp"), I);
+ I.setOperand(0, Op1);
+ I.setOperand(1, Constant::getNullValue(Op1->getType()));
+ return &I;
+ }
+ }
+ }
+ return Changed ? &I : 0;
+}
+
+
+/// FoldICmpDivCst - Fold "icmp pred, ([su]div X, DivRHS), CmpRHS" where DivRHS
+/// and CmpRHS are both known to be integer constants.
+Instruction *InstCombiner::FoldICmpDivCst(ICmpInst &ICI, BinaryOperator *DivI,
+ ConstantInt *DivRHS) {
+ ConstantInt *CmpRHS = cast<ConstantInt>(ICI.getOperand(1));
+ const APInt &CmpRHSV = CmpRHS->getValue();
+
+ // FIXME: If the operand types don't match the type of the divide
+ // then don't attempt this transform. The code below doesn't have the
+ // logic to deal with a signed divide and an unsigned compare (and
+ // vice versa). This is because (x /s C1) <s C2 produces different
+ // results than (x /s C1) <u C2 or (x /u C1) <s C2 or even
+ // (x /u C1) <u C2. Simply casting the operands and result won't
+ // work. :( The if statement below tests that condition and bails
+ // if it finds it.
+ bool DivIsSigned = DivI->getOpcode() == Instruction::SDiv;
+ if (!ICI.isEquality() && DivIsSigned != ICI.isSignedPredicate())
+ return 0;
+ if (DivRHS->isZero())
+ return 0; // The ProdOV computation fails on divide by zero.
+
+ // Compute Prod = CI * DivRHS. We are essentially solving an equation
+ // of form X/C1=C2. We solve for X by multiplying C1 (DivRHS) and
+ // C2 (CI). By solving for X we can turn this into a range check
+ // instead of computing a divide.
+ ConstantInt *Prod = Multiply(CmpRHS, DivRHS);
+
+ // Determine if the product overflows by seeing if the product is
+ // not equal to the divide. Make sure we do the same kind of divide
+ // as in the LHS instruction that we're folding.
+ bool ProdOV = (DivIsSigned ? ConstantExpr::getSDiv(Prod, DivRHS) :
+ ConstantExpr::getUDiv(Prod, DivRHS)) != CmpRHS;
+
+ // Get the ICmp opcode
+ ICmpInst::Predicate Pred = ICI.getPredicate();
+
+ // Figure out the interval that is being checked. For example, a comparison
+ // like "X /u 5 == 0" is really checking that X is in the interval [0, 5).
+ // Compute this interval based on the constants involved and the signedness of
+ // the compare/divide. This computes a half-open interval, keeping track of
+ // whether either value in the interval overflows. After analysis each
+ // overflow variable is set to 0 if it's corresponding bound variable is valid
+ // -1 if overflowed off the bottom end, or +1 if overflowed off the top end.
+ int LoOverflow = 0, HiOverflow = 0;
+ ConstantInt *LoBound = 0, *HiBound = 0;
+
+
+ if (!DivIsSigned) { // udiv
+ // e.g. X/5 op 3 --> [15, 20)
+ LoBound = Prod;
+ HiOverflow = LoOverflow = ProdOV;
+ if (!HiOverflow)
+ HiOverflow = AddWithOverflow(HiBound, LoBound, DivRHS, false);
+ } else if (DivRHS->getValue().isPositive()) { // Divisor is > 0.
+ if (CmpRHSV == 0) { // (X / pos) op 0
+ // Can't overflow. e.g. X/2 op 0 --> [-1, 2)
+ LoBound = cast<ConstantInt>(ConstantExpr::getNeg(SubOne(DivRHS)));
+ HiBound = DivRHS;
+ } else if (CmpRHSV.isPositive()) { // (X / pos) op pos
+ LoBound = Prod; // e.g. X/5 op 3 --> [15, 20)
+ HiOverflow = LoOverflow = ProdOV;
+ if (!HiOverflow)
+ HiOverflow = AddWithOverflow(HiBound, Prod, DivRHS, true);
+ } else { // (X / pos) op neg
+ // e.g. X/5 op -3 --> [-15-4, -15+1) --> [-19, -14)
+ Constant *DivRHSH = ConstantExpr::getNeg(SubOne(DivRHS));
+ LoOverflow = AddWithOverflow(LoBound, Prod,
+ cast<ConstantInt>(DivRHSH), true) ? -1 : 0;
+ HiBound = AddOne(Prod);
+ HiOverflow = ProdOV ? -1 : 0;
+ }
+ } else { // Divisor is < 0.
+ if (CmpRHSV == 0) { // (X / neg) op 0
+ // e.g. X/-5 op 0 --> [-4, 5)
+ LoBound = AddOne(DivRHS);
+ HiBound = cast<ConstantInt>(ConstantExpr::getNeg(DivRHS));
+ if (HiBound == DivRHS) { // -INTMIN = INTMIN
+ HiOverflow = 1; // [INTMIN+1, overflow)
+ HiBound = 0; // e.g. X/INTMIN = 0 --> X > INTMIN
+ }
+ } else if (CmpRHSV.isPositive()) { // (X / neg) op pos
+ // e.g. X/-5 op 3 --> [-19, -14)
+ HiOverflow = LoOverflow = ProdOV ? -1 : 0;
+ if (!LoOverflow)
+ LoOverflow = AddWithOverflow(LoBound, Prod, AddOne(DivRHS), true) ?-1:0;
+ HiBound = AddOne(Prod);
+ } else { // (X / neg) op neg
+ // e.g. X/-5 op -3 --> [15, 20)
+ LoBound = Prod;
+ LoOverflow = HiOverflow = ProdOV ? 1 : 0;
+ HiBound = Subtract(Prod, DivRHS);
+ }
+
+ // Dividing by a negative swaps the condition. LT <-> GT
+ Pred = ICmpInst::getSwappedPredicate(Pred);
+ }
+
+ Value *X = DivI->getOperand(0);
+ switch (Pred) {
+ default: assert(0 && "Unhandled icmp opcode!");
+ case ICmpInst::ICMP_EQ:
+ if (LoOverflow && HiOverflow)
+ return ReplaceInstUsesWith(ICI, ConstantInt::getFalse());
+ else if (HiOverflow)
+ return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SGE :
+ ICmpInst::ICMP_UGE, X, LoBound);
+ else if (LoOverflow)
+ return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SLT :
+ ICmpInst::ICMP_ULT, X, HiBound);
+ else
+ return InsertRangeTest(X, LoBound, HiBound, DivIsSigned, true, ICI);
+ case ICmpInst::ICMP_NE:
+ if (LoOverflow && HiOverflow)
+ return ReplaceInstUsesWith(ICI, ConstantInt::getTrue());
+ else if (HiOverflow)
+ return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SLT :
+ ICmpInst::ICMP_ULT, X, LoBound);
+ else if (LoOverflow)
+ return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SGE :
+ ICmpInst::ICMP_UGE, X, HiBound);
+ else
+ return InsertRangeTest(X, LoBound, HiBound, DivIsSigned, false, ICI);
+ case ICmpInst::ICMP_ULT:
+ case ICmpInst::ICMP_SLT:
+ if (LoOverflow == +1) // Low bound is greater than input range.
+ return ReplaceInstUsesWith(ICI, ConstantInt::getTrue());
+ if (LoOverflow == -1) // Low bound is less than input range.
+ return ReplaceInstUsesWith(ICI, ConstantInt::getFalse());
+ return new ICmpInst(Pred, X, LoBound);
+ case ICmpInst::ICMP_UGT:
+ case ICmpInst::ICMP_SGT:
+ if (HiOverflow == +1) // High bound greater than input range.
+ return ReplaceInstUsesWith(ICI, ConstantInt::getFalse());
+ else if (HiOverflow == -1) // High bound less than input range.
+ return ReplaceInstUsesWith(ICI, ConstantInt::getTrue());
+ if (Pred == ICmpInst::ICMP_UGT)
+ return new ICmpInst(ICmpInst::ICMP_UGE, X, HiBound);
+ else
+ return new ICmpInst(ICmpInst::ICMP_SGE, X, HiBound);
+ }
+}
+
+
+/// visitICmpInstWithInstAndIntCst - Handle "icmp (instr, intcst)".
+///
+Instruction *InstCombiner::visitICmpInstWithInstAndIntCst(ICmpInst &ICI,
+ Instruction *LHSI,
+ ConstantInt *RHS) {
+ const APInt &RHSV = RHS->getValue();
+
+ switch (LHSI->getOpcode()) {
+ case Instruction::Xor: // (icmp pred (xor X, XorCST), CI)
+ if (ConstantInt *XorCST = dyn_cast<ConstantInt>(LHSI->getOperand(1))) {
+ // If this is a comparison that tests the signbit (X < 0) or (x > -1),
+ // fold the xor.
+ if (ICI.getPredicate() == ICmpInst::ICMP_SLT && RHSV == 0 ||
+ ICI.getPredicate() == ICmpInst::ICMP_SGT && RHSV.isAllOnesValue()) {
+ Value *CompareVal = LHSI->getOperand(0);
+
+ // If the sign bit of the XorCST is not set, there is no change to
+ // the operation, just stop using the Xor.
+ if (!XorCST->getValue().isNegative()) {
+ ICI.setOperand(0, CompareVal);
+ AddToWorkList(LHSI);
+ return &ICI;
+ }
+
+ // Was the old condition true if the operand is positive?
+ bool isTrueIfPositive = ICI.getPredicate() == ICmpInst::ICMP_SGT;
+
+ // If so, the new one isn't.
+ isTrueIfPositive ^= true;
+
+ if (isTrueIfPositive)
+ return new ICmpInst(ICmpInst::ICMP_SGT, CompareVal, SubOne(RHS));
+ else
+ return new ICmpInst(ICmpInst::ICMP_SLT, CompareVal, AddOne(RHS));
+ }
+ }
+ break;
+ case Instruction::And: // (icmp pred (and X, AndCST), RHS)
+ if (LHSI->hasOneUse() && isa<ConstantInt>(LHSI->getOperand(1)) &&
+ LHSI->getOperand(0)->hasOneUse()) {
+ ConstantInt *AndCST = cast<ConstantInt>(LHSI->getOperand(1));
+
+ // If the LHS is an AND of a truncating cast, we can widen the
+ // and/compare to be the input width without changing the value
+ // produced, eliminating a cast.
+ if (TruncInst *Cast = dyn_cast<TruncInst>(LHSI->getOperand(0))) {
+ // We can do this transformation if either the AND constant does not
+ // have its sign bit set or if it is an equality comparison.
+ // Extending a relational comparison when we're checking the sign
+ // bit would not work.
+ if (Cast->hasOneUse() &&
+ (ICI.isEquality() || AndCST->getValue().isPositive() &&
+ RHSV.isPositive())) {
+ uint32_t BitWidth =
+ cast<IntegerType>(Cast->getOperand(0)->getType())->getBitWidth();
+ APInt NewCST = AndCST->getValue();
+ NewCST.zext(BitWidth);
+ APInt NewCI = RHSV;
+ NewCI.zext(BitWidth);
+ Instruction *NewAnd =
+ BinaryOperator::createAnd(Cast->getOperand(0),
+ ConstantInt::get(NewCST),LHSI->getName());
+ InsertNewInstBefore(NewAnd, ICI);
+ return new ICmpInst(ICI.getPredicate(), NewAnd,
+ ConstantInt::get(NewCI));
+ }
+ }
+
+ // If this is: (X >> C1) & C2 != C3 (where any shift and any compare
+ // could exist), turn it into (X & (C2 << C1)) != (C3 << C1). This
+ // happens a LOT in code produced by the C front-end, for bitfield
+ // access.
+ BinaryOperator *Shift = dyn_cast<BinaryOperator>(LHSI->getOperand(0));
+ if (Shift && !Shift->isShift())
+ Shift = 0;
+
+ ConstantInt *ShAmt;
+ ShAmt = Shift ? dyn_cast<ConstantInt>(Shift->getOperand(1)) : 0;
+ const Type *Ty = Shift ? Shift->getType() : 0; // Type of the shift.
+ const Type *AndTy = AndCST->getType(); // Type of the and.
+
+ // We can fold this as long as we can't shift unknown bits
+ // into the mask. This can only happen with signed shift
+ // rights, as they sign-extend.
+ if (ShAmt) {
+ bool CanFold = Shift->isLogicalShift();
+ if (!CanFold) {
+ // To test for the bad case of the signed shr, see if any
+ // of the bits shifted in could be tested after the mask.
+ uint32_t TyBits = Ty->getPrimitiveSizeInBits();
+ int ShAmtVal = TyBits - ShAmt->getLimitedValue(TyBits);
+
+ uint32_t BitWidth = AndTy->getPrimitiveSizeInBits();
+ if ((APInt::getHighBitsSet(BitWidth, BitWidth-ShAmtVal) &
+ AndCST->getValue()) == 0)
+ CanFold = true;
+ }
+
+ if (CanFold) {
+ Constant *NewCst;
+ if (Shift->getOpcode() == Instruction::Shl)
+ NewCst = ConstantExpr::getLShr(RHS, ShAmt);
+ else
+ NewCst = ConstantExpr::getShl(RHS, ShAmt);
+
+ // Check to see if we are shifting out any of the bits being
+ // compared.
+ if (ConstantExpr::get(Shift->getOpcode(), NewCst, ShAmt) != RHS) {
+ // If we shifted bits out, the fold is not going to work out.
+ // As a special case, check to see if this means that the
+ // result is always true or false now.
+ if (ICI.getPredicate() == ICmpInst::ICMP_EQ)
+ return ReplaceInstUsesWith(ICI, ConstantInt::getFalse());
+ if (ICI.getPredicate() == ICmpInst::ICMP_NE)
+ return ReplaceInstUsesWith(ICI, ConstantInt::getTrue());
+ } else {
+ ICI.setOperand(1, NewCst);
+ Constant *NewAndCST;
+ if (Shift->getOpcode() == Instruction::Shl)
+ NewAndCST = ConstantExpr::getLShr(AndCST, ShAmt);
+ else
+ NewAndCST = ConstantExpr::getShl(AndCST, ShAmt);
+ LHSI->setOperand(1, NewAndCST);
+ LHSI->setOperand(0, Shift->getOperand(0));
+ AddToWorkList(Shift); // Shift is dead.
+ AddUsesToWorkList(ICI);
+ return &ICI;
+ }
+ }
+ }
+
+ // Turn ((X >> Y) & C) == 0 into (X & (C << Y)) == 0. The later is
+ // preferable because it allows the C<<Y expression to be hoisted out
+ // of a loop if Y is invariant and X is not.
+ if (Shift && Shift->hasOneUse() && RHSV == 0 &&
+ ICI.isEquality() && !Shift->isArithmeticShift() &&
+ isa<Instruction>(Shift->getOperand(0))) {
+ // Compute C << Y.
+ Value *NS;
+ if (Shift->getOpcode() == Instruction::LShr) {
+ NS = BinaryOperator::createShl(AndCST,
+ Shift->getOperand(1), "tmp");
+ } else {
+ // Insert a logical shift.
+ NS = BinaryOperator::createLShr(AndCST,
+ Shift->getOperand(1), "tmp");
+ }
+ InsertNewInstBefore(cast<Instruction>(NS), ICI);
+
+ // Compute X & (C << Y).
+ Instruction *NewAnd =
+ BinaryOperator::createAnd(Shift->getOperand(0), NS, LHSI->getName());
+ InsertNewInstBefore(NewAnd, ICI);
+
+ ICI.setOperand(0, NewAnd);
+ return &ICI;
+ }
+ }
+ break;
+
+ case Instruction::Shl: { // (icmp pred (shl X, ShAmt), CI)
+ ConstantInt *ShAmt = dyn_cast<ConstantInt>(LHSI->getOperand(1));
+ if (!ShAmt) break;
+
+ uint32_t TypeBits = RHSV.getBitWidth();
+
+ // Check that the shift amount is in range. If not, don't perform
+ // undefined shifts. When the shift is visited it will be
+ // simplified.
+ if (ShAmt->uge(TypeBits))
+ break;
+
+ if (ICI.isEquality()) {
+ // If we are comparing against bits always shifted out, the
+ // comparison cannot succeed.
+ Constant *Comp =
+ ConstantExpr::getShl(ConstantExpr::getLShr(RHS, ShAmt), ShAmt);
+ if (Comp != RHS) {// Comparing against a bit that we know is zero.
+ bool IsICMP_NE = ICI.getPredicate() == ICmpInst::ICMP_NE;
+ Constant *Cst = ConstantInt::get(Type::Int1Ty, IsICMP_NE);
+ return ReplaceInstUsesWith(ICI, Cst);
+ }
+
+ if (LHSI->hasOneUse()) {
+ // Otherwise strength reduce the shift into an and.
+ uint32_t ShAmtVal = (uint32_t)ShAmt->getLimitedValue(TypeBits);
+ Constant *Mask =
+ ConstantInt::get(APInt::getLowBitsSet(TypeBits, TypeBits-ShAmtVal));
+
+ Instruction *AndI =
+ BinaryOperator::createAnd(LHSI->getOperand(0),
+ Mask, LHSI->getName()+".mask");
+ Value *And = InsertNewInstBefore(AndI, ICI);
+ return new ICmpInst(ICI.getPredicate(), And,
+ ConstantInt::get(RHSV.lshr(ShAmtVal)));
+ }
+ }
+
+ // Otherwise, if this is a comparison of the sign bit, simplify to and/test.
+ bool TrueIfSigned = false;
+ if (LHSI->hasOneUse() &&
+ isSignBitCheck(ICI.getPredicate(), RHS, TrueIfSigned)) {
+ // (X << 31) <s 0 --> (X&1) != 0
+ Constant *Mask = ConstantInt::get(APInt(TypeBits, 1) <<
+ (TypeBits-ShAmt->getZExtValue()-1));
+ Instruction *AndI =
+ BinaryOperator::createAnd(LHSI->getOperand(0),
+ Mask, LHSI->getName()+".mask");
+ Value *And = InsertNewInstBefore(AndI, ICI);
+
+ return new ICmpInst(TrueIfSigned ? ICmpInst::ICMP_NE : ICmpInst::ICMP_EQ,
+ And, Constant::getNullValue(And->getType()));
+ }
+ break;
+ }
+
+ case Instruction::LShr: // (icmp pred (shr X, ShAmt), CI)
+ case Instruction::AShr: {
+ ConstantInt *ShAmt = dyn_cast<ConstantInt>(LHSI->getOperand(1));
+ if (!ShAmt) break;
+
+ if (ICI.isEquality()) {
+ // Check that the shift amount is in range. If not, don't perform
+ // undefined shifts. When the shift is visited it will be
+ // simplified.
+ uint32_t TypeBits = RHSV.getBitWidth();
+ if (ShAmt->uge(TypeBits))
+ break;
+ uint32_t ShAmtVal = (uint32_t)ShAmt->getLimitedValue(TypeBits);
+
+ // If we are comparing against bits always shifted out, the
+ // comparison cannot succeed.
+ APInt Comp = RHSV << ShAmtVal;
+ if (LHSI->getOpcode() == Instruction::LShr)
+ Comp = Comp.lshr(ShAmtVal);
+ else
+ Comp = Comp.ashr(ShAmtVal);
+
+ if (Comp != RHSV) { // Comparing against a bit that we know is zero.
+ bool IsICMP_NE = ICI.getPredicate() == ICmpInst::ICMP_NE;
+ Constant *Cst = ConstantInt::get(Type::Int1Ty, IsICMP_NE);
+ return ReplaceInstUsesWith(ICI, Cst);
+ }
+
+ if (LHSI->hasOneUse() || RHSV == 0) {
+ // Otherwise strength reduce the shift into an and.
+ APInt Val(APInt::getHighBitsSet(TypeBits, TypeBits - ShAmtVal));
+ Constant *Mask = ConstantInt::get(Val);
+
+ Instruction *AndI =
+ BinaryOperator::createAnd(LHSI->getOperand(0),
+ Mask, LHSI->getName()+".mask");
+ Value *And = InsertNewInstBefore(AndI, ICI);
+ return new ICmpInst(ICI.getPredicate(), And,
+ ConstantExpr::getShl(RHS, ShAmt));
+ }
+ }
+ break;
+ }
+
+ case Instruction::SDiv:
+ case Instruction::UDiv:
+ // Fold: icmp pred ([us]div X, C1), C2 -> range test
+ // Fold this div into the comparison, producing a range check.
+ // Determine, based on the divide type, what the range is being
+ // checked. If there is an overflow on the low or high side, remember
+ // it, otherwise compute the range [low, hi) bounding the new value.
+ // See: InsertRangeTest above for the kinds of replacements possible.
+ if (ConstantInt *DivRHS = dyn_cast<ConstantInt>(LHSI->getOperand(1)))
+ if (Instruction *R = FoldICmpDivCst(ICI, cast<BinaryOperator>(LHSI),
+ DivRHS))
+ return R;
+ break;
+ }
+
+ // Simplify icmp_eq and icmp_ne instructions with integer constant RHS.
+ if (ICI.isEquality()) {
+ bool isICMP_NE = ICI.getPredicate() == ICmpInst::ICMP_NE;
+
+ // If the first operand is (add|sub|and|or|xor|rem) with a constant, and
+ // the second operand is a constant, simplify a bit.
+ if (BinaryOperator *BO = dyn_cast<BinaryOperator>(LHSI)) {
+ switch (BO->getOpcode()) {
+ case Instruction::SRem:
+ // If we have a signed (X % (2^c)) == 0, turn it into an unsigned one.
+ if (RHSV == 0 && isa<ConstantInt>(BO->getOperand(1)) &&BO->hasOneUse()){
+ const APInt &V = cast<ConstantInt>(BO->getOperand(1))->getValue();
+ if (V.sgt(APInt(V.getBitWidth(), 1)) && V.isPowerOf2()) {
+ Instruction *NewRem =
+ BinaryOperator::createURem(BO->getOperand(0), BO->getOperand(1),
+ BO->getName());
+ InsertNewInstBefore(NewRem, ICI);
+ return new ICmpInst(ICI.getPredicate(), NewRem,
+ Constant::getNullValue(BO->getType()));
+ }
+ }
+ break;
+ case Instruction::Add:
+ // Replace ((add A, B) != C) with (A != C-B) if B & C are constants.
+ if (ConstantInt *BOp1C = dyn_cast<ConstantInt>(BO->getOperand(1))) {
+ if (BO->hasOneUse())
+ return new ICmpInst(ICI.getPredicate(), BO->getOperand(0),
+ Subtract(RHS, BOp1C));
+ } else if (RHSV == 0) {
+ // Replace ((add A, B) != 0) with (A != -B) if A or B is
+ // efficiently invertible, or if the add has just this one use.
+ Value *BOp0 = BO->getOperand(0), *BOp1 = BO->getOperand(1);
+
+ if (Value *NegVal = dyn_castNegVal(BOp1))
+ return new ICmpInst(ICI.getPredicate(), BOp0, NegVal);
+ else if (Value *NegVal = dyn_castNegVal(BOp0))
+ return new ICmpInst(ICI.getPredicate(), NegVal, BOp1);
+ else if (BO->hasOneUse()) {
+ Instruction *Neg = BinaryOperator::createNeg(BOp1);
+ InsertNewInstBefore(Neg, ICI);
+ Neg->takeName(BO);
+ return new ICmpInst(ICI.getPredicate(), BOp0, Neg);
+ }
+ }
+ break;
+ case Instruction::Xor:
+ // For the xor case, we can xor two constants together, eliminating
+ // the explicit xor.
+ if (Constant *BOC = dyn_cast<Constant>(BO->getOperand(1)))
+ return new ICmpInst(ICI.getPredicate(), BO->getOperand(0),
+ ConstantExpr::getXor(RHS, BOC));
+
+ // FALLTHROUGH
+ case Instruction::Sub:
+ // Replace (([sub|xor] A, B) != 0) with (A != B)
+ if (RHSV == 0)
+ return new ICmpInst(ICI.getPredicate(), BO->getOperand(0),
+ BO->getOperand(1));
+ break;
+
+ case Instruction::Or:
+ // If bits are being or'd in that are not present in the constant we
+ // are comparing against, then the comparison could never succeed!
+ if (Constant *BOC = dyn_cast<Constant>(BO->getOperand(1))) {
+ Constant *NotCI = ConstantExpr::getNot(RHS);
+ if (!ConstantExpr::getAnd(BOC, NotCI)->isNullValue())
+ return ReplaceInstUsesWith(ICI, ConstantInt::get(Type::Int1Ty,
+ isICMP_NE));
+ }
+ break;
+
+ case Instruction::And:
+ if (ConstantInt *BOC = dyn_cast<ConstantInt>(BO->getOperand(1))) {
+ // If bits are being compared against that are and'd out, then the
+ // comparison can never succeed!
+ if ((RHSV & ~BOC->getValue()) != 0)
+ return ReplaceInstUsesWith(ICI, ConstantInt::get(Type::Int1Ty,
+ isICMP_NE));
+
+ // If we have ((X & C) == C), turn it into ((X & C) != 0).
+ if (RHS == BOC && RHSV.isPowerOf2())
+ return new ICmpInst(isICMP_NE ? ICmpInst::ICMP_EQ :
+ ICmpInst::ICMP_NE, LHSI,
+ Constant::getNullValue(RHS->getType()));
+
+ // Replace (and X, (1 << size(X)-1) != 0) with x s< 0
+ if (isSignBit(BOC)) {
+ Value *X = BO->getOperand(0);
+ Constant *Zero = Constant::getNullValue(X->getType());
+ ICmpInst::Predicate pred = isICMP_NE ?
+ ICmpInst::ICMP_SLT : ICmpInst::ICMP_SGE;
+ return new ICmpInst(pred, X, Zero);
+ }
+
+ // ((X & ~7) == 0) --> X < 8
+ if (RHSV == 0 && isHighOnes(BOC)) {
+ Value *X = BO->getOperand(0);
+ Constant *NegX = ConstantExpr::getNeg(BOC);
+ ICmpInst::Predicate pred = isICMP_NE ?
+ ICmpInst::ICMP_UGE : ICmpInst::ICMP_ULT;
+ return new ICmpInst(pred, X, NegX);
+ }
+ }
+ default: break;
+ }
+ } else if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(LHSI)) {
+ // Handle icmp {eq|ne} <intrinsic>, intcst.
+ if (II->getIntrinsicID() == Intrinsic::bswap) {
+ AddToWorkList(II);
+ ICI.setOperand(0, II->getOperand(1));
+ ICI.setOperand(1, ConstantInt::get(RHSV.byteSwap()));
+ return &ICI;
+ }
+ }
+ } else { // Not a ICMP_EQ/ICMP_NE
+ // If the LHS is a cast from an integral value of the same size,
+ // then since we know the RHS is a constant, try to simlify.
+ if (CastInst *Cast = dyn_cast<CastInst>(LHSI)) {
+ Value *CastOp = Cast->getOperand(0);
+ const Type *SrcTy = CastOp->getType();
+ uint32_t SrcTySize = SrcTy->getPrimitiveSizeInBits();
+ if (SrcTy->isInteger() &&
+ SrcTySize == Cast->getType()->getPrimitiveSizeInBits()) {
+ // If this is an unsigned comparison, try to make the comparison use
+ // smaller constant values.
+ if (ICI.getPredicate() == ICmpInst::ICMP_ULT && RHSV.isSignBit()) {
+ // X u< 128 => X s> -1
+ return new ICmpInst(ICmpInst::ICMP_SGT, CastOp,
+ ConstantInt::get(APInt::getAllOnesValue(SrcTySize)));
+ } else if (ICI.getPredicate() == ICmpInst::ICMP_UGT &&
+ RHSV == APInt::getSignedMaxValue(SrcTySize)) {
+ // X u> 127 => X s< 0
+ return new ICmpInst(ICmpInst::ICMP_SLT, CastOp,
+ Constant::getNullValue(SrcTy));
+ }
+ }
+ }
+ }
+ return 0;
+}
+
+/// visitICmpInstWithCastAndCast - Handle icmp (cast x to y), (cast/cst).
+/// We only handle extending casts so far.
+///
+Instruction *InstCombiner::visitICmpInstWithCastAndCast(ICmpInst &ICI) {
+ const CastInst *LHSCI = cast<CastInst>(ICI.getOperand(0));
+ Value *LHSCIOp = LHSCI->getOperand(0);
+ const Type *SrcTy = LHSCIOp->getType();
+ const Type *DestTy = LHSCI->getType();
+ Value *RHSCIOp;
+
+ // Turn icmp (ptrtoint x), (ptrtoint/c) into a compare of the input if the
+ // integer type is the same size as the pointer type.
+ if (LHSCI->getOpcode() == Instruction::PtrToInt &&
+ getTargetData().getPointerSizeInBits() ==
+ cast<IntegerType>(DestTy)->getBitWidth()) {
+ Value *RHSOp = 0;
+ if (Constant *RHSC = dyn_cast<Constant>(ICI.getOperand(1))) {
+ RHSOp = ConstantExpr::getIntToPtr(RHSC, SrcTy);
+ } else if (PtrToIntInst *RHSC = dyn_cast<PtrToIntInst>(ICI.getOperand(1))) {
+ RHSOp = RHSC->getOperand(0);
+ // If the pointer types don't match, insert a bitcast.
+ if (LHSCIOp->getType() != RHSOp->getType())
+ RHSOp = InsertCastBefore(Instruction::BitCast, RHSOp,
+ LHSCIOp->getType(), ICI);
+ }
+
+ if (RHSOp)
+ return new ICmpInst(ICI.getPredicate(), LHSCIOp, RHSOp);
+ }
+
+ // The code below only handles extension cast instructions, so far.
+ // Enforce this.
+ if (LHSCI->getOpcode() != Instruction::ZExt &&
+ LHSCI->getOpcode() != Instruction::SExt)
+ return 0;
+
+ bool isSignedExt = LHSCI->getOpcode() == Instruction::SExt;
+ bool isSignedCmp = ICI.isSignedPredicate();
+
+ if (CastInst *CI = dyn_cast<CastInst>(ICI.getOperand(1))) {
+ // Not an extension from the same type?
+ RHSCIOp = CI->getOperand(0);
+ if (RHSCIOp->getType() != LHSCIOp->getType())
+ return 0;
+
+ // If the signedness of the two compares doesn't agree (i.e. one is a sext
+ // and the other is a zext), then we can't handle this.
+ if (CI->getOpcode() != LHSCI->getOpcode())
+ return 0;
+
+ // Likewise, if the signedness of the [sz]exts and the compare don't match,
+ // then we can't handle this.
+ if (isSignedExt != isSignedCmp && !ICI.isEquality())
+ return 0;
+
+ // Okay, just insert a compare of the reduced operands now!
+ return new ICmpInst(ICI.getPredicate(), LHSCIOp, RHSCIOp);
+ }
+
+ // If we aren't dealing with a constant on the RHS, exit early
+ ConstantInt *CI = dyn_cast<ConstantInt>(ICI.getOperand(1));
+ if (!CI)
+ return 0;
+
+ // Compute the constant that would happen if we truncated to SrcTy then
+ // reextended to DestTy.
+ Constant *Res1 = ConstantExpr::getTrunc(CI, SrcTy);
+ Constant *Res2 = ConstantExpr::getCast(LHSCI->getOpcode(), Res1, DestTy);
+
+ // If the re-extended constant didn't change...
+ if (Res2 == CI) {
+ // Make sure that sign of the Cmp and the sign of the Cast are the same.
+ // For example, we might have:
+ // %A = sext short %X to uint
+ // %B = icmp ugt uint %A, 1330
+ // It is incorrect to transform this into
+ // %B = icmp ugt short %X, 1330
+ // because %A may have negative value.
+ //
+ // However, it is OK if SrcTy is bool (See cast-set.ll testcase)
+ // OR operation is EQ/NE.
+ if (isSignedExt == isSignedCmp || SrcTy == Type::Int1Ty || ICI.isEquality())
+ return new ICmpInst(ICI.getPredicate(), LHSCIOp, Res1);
+ else
+ return 0;
+ }
+
+ // The re-extended constant changed so the constant cannot be represented
+ // in the shorter type. Consequently, we cannot emit a simple comparison.
+
+ // First, handle some easy cases. We know the result cannot be equal at this
+ // point so handle the ICI.isEquality() cases
+ if (ICI.getPredicate() == ICmpInst::ICMP_EQ)
+ return ReplaceInstUsesWith(ICI, ConstantInt::getFalse());
+ if (ICI.getPredicate() == ICmpInst::ICMP_NE)
+ return ReplaceInstUsesWith(ICI, ConstantInt::getTrue());
+
+ // Evaluate the comparison for LT (we invert for GT below). LE and GE cases
+ // should have been folded away previously and not enter in here.
+ Value *Result;
+ if (isSignedCmp) {
+ // We're performing a signed comparison.
+ if (cast<ConstantInt>(CI)->getValue().isNegative())
+ Result = ConstantInt::getFalse(); // X < (small) --> false
+ else
+ Result = ConstantInt::getTrue(); // X < (large) --> true
+ } else {
+ // We're performing an unsigned comparison.
+ if (isSignedExt) {
+ // We're performing an unsigned comp with a sign extended value.
+ // This is true if the input is >= 0. [aka >s -1]
+ Constant *NegOne = ConstantInt::getAllOnesValue(SrcTy);
+ Result = InsertNewInstBefore(new ICmpInst(ICmpInst::ICMP_SGT, LHSCIOp,
+ NegOne, ICI.getName()), ICI);
+ } else {
+ // Unsigned extend & unsigned compare -> always true.
+ Result = ConstantInt::getTrue();
+ }
+ }
+
+ // Finally, return the value computed.
+ if (ICI.getPredicate() == ICmpInst::ICMP_ULT ||
+ ICI.getPredicate() == ICmpInst::ICMP_SLT) {
+ return ReplaceInstUsesWith(ICI, Result);
+ } else {
+ assert((ICI.getPredicate()==ICmpInst::ICMP_UGT ||
+ ICI.getPredicate()==ICmpInst::ICMP_SGT) &&
+ "ICmp should be folded!");
+ if (Constant *CI = dyn_cast<Constant>(Result))
+ return ReplaceInstUsesWith(ICI, ConstantExpr::getNot(CI));
+ else
+ return BinaryOperator::createNot(Result);
+ }
+}
+
+Instruction *InstCombiner::visitShl(BinaryOperator &I) {
+ return commonShiftTransforms(I);
+}
+
+Instruction *InstCombiner::visitLShr(BinaryOperator &I) {
+ return commonShiftTransforms(I);
+}
+
+Instruction *InstCombiner::visitAShr(BinaryOperator &I) {
+ return commonShiftTransforms(I);
+}
+
+Instruction *InstCombiner::commonShiftTransforms(BinaryOperator &I) {
+ assert(I.getOperand(1)->getType() == I.getOperand(0)->getType());
+ Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
+
+ // shl X, 0 == X and shr X, 0 == X
+ // shl 0, X == 0 and shr 0, X == 0
+ if (Op1 == Constant::getNullValue(Op1->getType()) ||
+ Op0 == Constant::getNullValue(Op0->getType()))
+ return ReplaceInstUsesWith(I, Op0);
+
+ if (isa<UndefValue>(Op0)) {
+ if (I.getOpcode() == Instruction::AShr) // undef >>s X -> undef
+ return ReplaceInstUsesWith(I, Op0);
+ else // undef << X -> 0, undef >>u X -> 0
+ return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
+ }
+ if (isa<UndefValue>(Op1)) {
+ if (I.getOpcode() == Instruction::AShr) // X >>s undef -> X
+ return ReplaceInstUsesWith(I, Op0);
+ else // X << undef, X >>u undef -> 0
+ return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
+ }
+
+ // ashr int -1, X = -1 (for any arithmetic shift rights of ~0)
+ if (I.getOpcode() == Instruction::AShr)
+ if (ConstantInt *CSI = dyn_cast<ConstantInt>(Op0))
+ if (CSI->isAllOnesValue())
+ return ReplaceInstUsesWith(I, CSI);
+
+ // Try to fold constant and into select arguments.
+ if (isa<Constant>(Op0))
+ if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
+ if (Instruction *R = FoldOpIntoSelect(I, SI, this))
+ return R;
+
+ // See if we can turn a signed shr into an unsigned shr.
+ if (I.isArithmeticShift()) {
+ if (MaskedValueIsZero(Op0,
+ APInt::getSignBit(I.getType()->getPrimitiveSizeInBits()))) {
+ return BinaryOperator::createLShr(Op0, Op1, I.getName());
+ }
+ }
+
+ if (ConstantInt *CUI = dyn_cast<ConstantInt>(Op1))
+ if (Instruction *Res = FoldShiftByConstant(Op0, CUI, I))
+ return Res;
+ return 0;
+}
+
+Instruction *InstCombiner::FoldShiftByConstant(Value *Op0, ConstantInt *Op1,
+ BinaryOperator &I) {
+ bool isLeftShift = I.getOpcode() == Instruction::Shl;
+
+ // See if we can simplify any instructions used by the instruction whose sole
+ // purpose is to compute bits we don't care about.
+ uint32_t TypeBits = Op0->getType()->getPrimitiveSizeInBits();
+ APInt KnownZero(TypeBits, 0), KnownOne(TypeBits, 0);
+ if (SimplifyDemandedBits(&I, APInt::getAllOnesValue(TypeBits),
+ KnownZero, KnownOne))
+ return &I;
+
+ // shl uint X, 32 = 0 and shr ubyte Y, 9 = 0, ... just don't eliminate shr
+ // of a signed value.
+ //
+ if (Op1->uge(TypeBits)) {
+ if (I.getOpcode() != Instruction::AShr)
+ return ReplaceInstUsesWith(I, Constant::getNullValue(Op0->getType()));
+ else {
+ I.setOperand(1, ConstantInt::get(I.getType(), TypeBits-1));
+ return &I;
+ }
+ }
+
+ // ((X*C1) << C2) == (X * (C1 << C2))
+ if (BinaryOperator *BO = dyn_cast<BinaryOperator>(Op0))
+ if (BO->getOpcode() == Instruction::Mul && isLeftShift)
+ if (Constant *BOOp = dyn_cast<Constant>(BO->getOperand(1)))
+ return BinaryOperator::createMul(BO->getOperand(0),
+ ConstantExpr::getShl(BOOp, Op1));
+
+ // Try to fold constant and into select arguments.
+ if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
+ if (Instruction *R = FoldOpIntoSelect(I, SI, this))
+ return R;
+ if (isa<PHINode>(Op0))
+ if (Instruction *NV = FoldOpIntoPhi(I))
+ return NV;
+
+ if (Op0->hasOneUse()) {
+ if (BinaryOperator *Op0BO = dyn_cast<BinaryOperator>(Op0)) {
+ // Turn ((X >> C) + Y) << C -> (X + (Y << C)) & (~0 << C)
+ Value *V1, *V2;
+ ConstantInt *CC;
+ switch (Op0BO->getOpcode()) {
+ default: break;
+ case Instruction::Add:
+ case Instruction::And:
+ case Instruction::Or:
+ case Instruction::Xor: {
+ // These operators commute.
+ // Turn (Y + (X >> C)) << C -> (X + (Y << C)) & (~0 << C)
+ if (isLeftShift && Op0BO->getOperand(1)->hasOneUse() &&
+ match(Op0BO->getOperand(1),
+ m_Shr(m_Value(V1), m_ConstantInt(CC))) && CC == Op1) {
+ Instruction *YS = BinaryOperator::createShl(
+ Op0BO->getOperand(0), Op1,
+ Op0BO->getName());
+ InsertNewInstBefore(YS, I); // (Y << C)
+ Instruction *X =
+ BinaryOperator::create(Op0BO->getOpcode(), YS, V1,
+ Op0BO->getOperand(1)->getName());
+ InsertNewInstBefore(X, I); // (X + (Y << C))
+ uint32_t Op1Val = Op1->getLimitedValue(TypeBits);
+ return BinaryOperator::createAnd(X, ConstantInt::get(
+ APInt::getHighBitsSet(TypeBits, TypeBits-Op1Val)));
+ }
+
+ // Turn (Y + ((X >> C) & CC)) << C -> ((X & (CC << C)) + (Y << C))
+ Value *Op0BOOp1 = Op0BO->getOperand(1);
+ if (isLeftShift && Op0BOOp1->hasOneUse() &&
+ match(Op0BOOp1,
+ m_And(m_Shr(m_Value(V1), m_Value(V2)),m_ConstantInt(CC))) &&
+ cast<BinaryOperator>(Op0BOOp1)->getOperand(0)->hasOneUse() &&
+ V2 == Op1) {
+ Instruction *YS = BinaryOperator::createShl(
+ Op0BO->getOperand(0), Op1,
+ Op0BO->getName());
+ InsertNewInstBefore(YS, I); // (Y << C)
+ Instruction *XM =
+ BinaryOperator::createAnd(V1, ConstantExpr::getShl(CC, Op1),
+ V1->getName()+".mask");
+ InsertNewInstBefore(XM, I); // X & (CC << C)
+
+ return BinaryOperator::create(Op0BO->getOpcode(), YS, XM);
+ }
+ }
+
+ // FALL THROUGH.
+ case Instruction::Sub: {
+ // Turn ((X >> C) + Y) << C -> (X + (Y << C)) & (~0 << C)
+ if (isLeftShift && Op0BO->getOperand(0)->hasOneUse() &&
+ match(Op0BO->getOperand(0),
+ m_Shr(m_Value(V1), m_ConstantInt(CC))) && CC == Op1) {
+ Instruction *YS = BinaryOperator::createShl(
+ Op0BO->getOperand(1), Op1,
+ Op0BO->getName());
+ InsertNewInstBefore(YS, I); // (Y << C)
+ Instruction *X =
+ BinaryOperator::create(Op0BO->getOpcode(), V1, YS,
+ Op0BO->getOperand(0)->getName());
+ InsertNewInstBefore(X, I); // (X + (Y << C))
+ uint32_t Op1Val = Op1->getLimitedValue(TypeBits);
+ return BinaryOperator::createAnd(X, ConstantInt::get(
+ APInt::getHighBitsSet(TypeBits, TypeBits-Op1Val)));
+ }
+
+ // Turn (((X >> C)&CC) + Y) << C -> (X + (Y << C)) & (CC << C)
+ if (isLeftShift && Op0BO->getOperand(0)->hasOneUse() &&
+ match(Op0BO->getOperand(0),
+ m_And(m_Shr(m_Value(V1), m_Value(V2)),
+ m_ConstantInt(CC))) && V2 == Op1 &&
+ cast<BinaryOperator>(Op0BO->getOperand(0))
+ ->getOperand(0)->hasOneUse()) {
+ Instruction *YS = BinaryOperator::createShl(
+ Op0BO->getOperand(1), Op1,
+ Op0BO->getName());
+ InsertNewInstBefore(YS, I); // (Y << C)
+ Instruction *XM =
+ BinaryOperator::createAnd(V1, ConstantExpr::getShl(CC, Op1),
+ V1->getName()+".mask");
+ InsertNewInstBefore(XM, I); // X & (CC << C)
+
+ return BinaryOperator::create(Op0BO->getOpcode(), XM, YS);
+ }
+
+ break;
+ }
+ }
+
+
+ // If the operand is an bitwise operator with a constant RHS, and the
+ // shift is the only use, we can pull it out of the shift.
+ if (ConstantInt *Op0C = dyn_cast<ConstantInt>(Op0BO->getOperand(1))) {
+ bool isValid = true; // Valid only for And, Or, Xor
+ bool highBitSet = false; // Transform if high bit of constant set?
+
+ switch (Op0BO->getOpcode()) {
+ default: isValid = false; break; // Do not perform transform!
+ case Instruction::Add:
+ isValid = isLeftShift;
+ break;
+ case Instruction::Or:
+ case Instruction::Xor:
+ highBitSet = false;
+ break;
+ case Instruction::And:
+ highBitSet = true;
+ break;
+ }
+
+ // If this is a signed shift right, and the high bit is modified
+ // by the logical operation, do not perform the transformation.
+ // The highBitSet boolean indicates the value of the high bit of
+ // the constant which would cause it to be modified for this
+ // operation.
+ //
+ if (isValid && !isLeftShift && I.getOpcode() == Instruction::AShr) {
+ isValid = Op0C->getValue()[TypeBits-1] == highBitSet;
+ }
+
+ if (isValid) {
+ Constant *NewRHS = ConstantExpr::get(I.getOpcode(), Op0C, Op1);
+
+ Instruction *NewShift =
+ BinaryOperator::create(I.getOpcode(), Op0BO->getOperand(0), Op1);
+ InsertNewInstBefore(NewShift, I);
+ NewShift->takeName(Op0BO);
+
+ return BinaryOperator::create(Op0BO->getOpcode(), NewShift,
+ NewRHS);
+ }
+ }
+ }
+ }
+
+ // Find out if this is a shift of a shift by a constant.
+ BinaryOperator *ShiftOp = dyn_cast<BinaryOperator>(Op0);
+ if (ShiftOp && !ShiftOp->isShift())
+ ShiftOp = 0;
+
+ if (ShiftOp && isa<ConstantInt>(ShiftOp->getOperand(1))) {
+ ConstantInt *ShiftAmt1C = cast<ConstantInt>(ShiftOp->getOperand(1));
+ uint32_t ShiftAmt1 = ShiftAmt1C->getLimitedValue(TypeBits);
+ uint32_t ShiftAmt2 = Op1->getLimitedValue(TypeBits);
+ assert(ShiftAmt2 != 0 && "Should have been simplified earlier");
+ if (ShiftAmt1 == 0) return 0; // Will be simplified in the future.
+ Value *X = ShiftOp->getOperand(0);
+
+ uint32_t AmtSum = ShiftAmt1+ShiftAmt2; // Fold into one big shift.
+ if (AmtSum > TypeBits)
+ AmtSum = TypeBits;
+
+ const IntegerType *Ty = cast<IntegerType>(I.getType());
+
+ // Check for (X << c1) << c2 and (X >> c1) >> c2
+ if (I.getOpcode() == ShiftOp->getOpcode()) {
+ return BinaryOperator::create(I.getOpcode(), X,
+ ConstantInt::get(Ty, AmtSum));
+ } else if (ShiftOp->getOpcode() == Instruction::LShr &&
+ I.getOpcode() == Instruction::AShr) {
+ // ((X >>u C1) >>s C2) -> (X >>u (C1+C2)) since C1 != 0.
+ return BinaryOperator::createLShr(X, ConstantInt::get(Ty, AmtSum));
+ } else if (ShiftOp->getOpcode() == Instruction::AShr &&
+ I.getOpcode() == Instruction::LShr) {
+ // ((X >>s C1) >>u C2) -> ((X >>s (C1+C2)) & mask) since C1 != 0.
+ Instruction *Shift =
+ BinaryOperator::createAShr(X, ConstantInt::get(Ty, AmtSum));
+ InsertNewInstBefore(Shift, I);
+
+ APInt Mask(APInt::getLowBitsSet(TypeBits, TypeBits - ShiftAmt2));
+ return BinaryOperator::createAnd(Shift, ConstantInt::get(Mask));
+ }
+
+ // Okay, if we get here, one shift must be left, and the other shift must be
+ // right. See if the amounts are equal.
+ if (ShiftAmt1 == ShiftAmt2) {
+ // If we have ((X >>? C) << C), turn this into X & (-1 << C).
+ if (I.getOpcode() == Instruction::Shl) {
+ APInt Mask(APInt::getHighBitsSet(TypeBits, TypeBits - ShiftAmt1));
+ return BinaryOperator::createAnd(X, ConstantInt::get(Mask));
+ }
+ // If we have ((X << C) >>u C), turn this into X & (-1 >>u C).
+ if (I.getOpcode() == Instruction::LShr) {
+ APInt Mask(APInt::getLowBitsSet(TypeBits, TypeBits - ShiftAmt1));
+ return BinaryOperator::createAnd(X, ConstantInt::get(Mask));
+ }
+ // We can simplify ((X << C) >>s C) into a trunc + sext.
+ // NOTE: we could do this for any C, but that would make 'unusual' integer
+ // types. For now, just stick to ones well-supported by the code
+ // generators.
+ const Type *SExtType = 0;
+ switch (Ty->getBitWidth() - ShiftAmt1) {
+ case 1 :
+ case 8 :
+ case 16 :
+ case 32 :
+ case 64 :
+ case 128:
+ SExtType = IntegerType::get(Ty->getBitWidth() - ShiftAmt1);
+ break;
+ default: break;
+ }
+ if (SExtType) {
+ Instruction *NewTrunc = new TruncInst(X, SExtType, "sext");
+ InsertNewInstBefore(NewTrunc, I);
+ return new SExtInst(NewTrunc, Ty);
+ }
+ // Otherwise, we can't handle it yet.
+ } else if (ShiftAmt1 < ShiftAmt2) {
+ uint32_t ShiftDiff = ShiftAmt2-ShiftAmt1;
+
+ // (X >>? C1) << C2 --> X << (C2-C1) & (-1 << C2)
+ if (I.getOpcode() == Instruction::Shl) {
+ assert(ShiftOp->getOpcode() == Instruction::LShr ||
+ ShiftOp->getOpcode() == Instruction::AShr);
+ Instruction *Shift =
+ BinaryOperator::createShl(X, ConstantInt::get(Ty, ShiftDiff));
+ InsertNewInstBefore(Shift, I);
+
+ APInt Mask(APInt::getHighBitsSet(TypeBits, TypeBits - ShiftAmt2));
+ return BinaryOperator::createAnd(Shift, ConstantInt::get(Mask));
+ }
+
+ // (X << C1) >>u C2 --> X >>u (C2-C1) & (-1 >> C2)
+ if (I.getOpcode() == Instruction::LShr) {
+ assert(ShiftOp->getOpcode() == Instruction::Shl);
+ Instruction *Shift =
+ BinaryOperator::createLShr(X, ConstantInt::get(Ty, ShiftDiff));
+ InsertNewInstBefore(Shift, I);
+
+ APInt Mask(APInt::getLowBitsSet(TypeBits, TypeBits - ShiftAmt2));
+ return BinaryOperator::createAnd(Shift, ConstantInt::get(Mask));
+ }
+
+ // We can't handle (X << C1) >>s C2, it shifts arbitrary bits in.
+ } else {
+ assert(ShiftAmt2 < ShiftAmt1);
+ uint32_t ShiftDiff = ShiftAmt1-ShiftAmt2;
+
+ // (X >>? C1) << C2 --> X >>? (C1-C2) & (-1 << C2)
+ if (I.getOpcode() == Instruction::Shl) {
+ assert(ShiftOp->getOpcode() == Instruction::LShr ||
+ ShiftOp->getOpcode() == Instruction::AShr);
+ Instruction *Shift =
+ BinaryOperator::create(ShiftOp->getOpcode(), X,
+ ConstantInt::get(Ty, ShiftDiff));
+ InsertNewInstBefore(Shift, I);
+
+ APInt Mask(APInt::getHighBitsSet(TypeBits, TypeBits - ShiftAmt2));
+ return BinaryOperator::createAnd(Shift, ConstantInt::get(Mask));
+ }
+
+ // (X << C1) >>u C2 --> X << (C1-C2) & (-1 >> C2)
+ if (I.getOpcode() == Instruction::LShr) {
+ assert(ShiftOp->getOpcode() == Instruction::Shl);
+ Instruction *Shift =
+ BinaryOperator::createShl(X, ConstantInt::get(Ty, ShiftDiff));
+ InsertNewInstBefore(Shift, I);
+
+ APInt Mask(APInt::getLowBitsSet(TypeBits, TypeBits - ShiftAmt2));
+ return BinaryOperator::createAnd(Shift, ConstantInt::get(Mask));
+ }
+
+ // We can't handle (X << C1) >>a C2, it shifts arbitrary bits in.
+ }
+ }
+ return 0;
+}
+
+
+/// DecomposeSimpleLinearExpr - Analyze 'Val', seeing if it is a simple linear
+/// expression. If so, decompose it, returning some value X, such that Val is
+/// X*Scale+Offset.
+///
+static Value *DecomposeSimpleLinearExpr(Value *Val, unsigned &Scale,
+ int &Offset) {
+ assert(Val->getType() == Type::Int32Ty && "Unexpected allocation size type!");
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(Val)) {
+ Offset = CI->getZExtValue();
+ Scale = 1;
+ return ConstantInt::get(Type::Int32Ty, 0);
+ } else if (Instruction *I = dyn_cast<Instruction>(Val)) {
+ if (I->getNumOperands() == 2) {
+ if (ConstantInt *CUI = dyn_cast<ConstantInt>(I->getOperand(1))) {
+ if (I->getOpcode() == Instruction::Shl) {
+ // This is a value scaled by '1 << the shift amt'.
+ Scale = 1U << CUI->getZExtValue();
+ Offset = 0;
+ return I->getOperand(0);
+ } else if (I->getOpcode() == Instruction::Mul) {
+ // This value is scaled by 'CUI'.
+ Scale = CUI->getZExtValue();
+ Offset = 0;
+ return I->getOperand(0);
+ } else if (I->getOpcode() == Instruction::Add) {
+ // We have X+C. Check to see if we really have (X*C2)+C1,
+ // where C1 is divisible by C2.
+ unsigned SubScale;
+ Value *SubVal =
+ DecomposeSimpleLinearExpr(I->getOperand(0), SubScale, Offset);
+ Offset += CUI->getZExtValue();
+ if (SubScale > 1 && (Offset % SubScale == 0)) {
+ Scale = SubScale;
+ return SubVal;
+ }
+ }
+ }
+ }
+ }
+
+ // Otherwise, we can't look past this.
+ Scale = 1;
+ Offset = 0;
+ return Val;
+}
+
+
+/// PromoteCastOfAllocation - If we find a cast of an allocation instruction,
+/// try to eliminate the cast by moving the type information into the alloc.
+Instruction *InstCombiner::PromoteCastOfAllocation(BitCastInst &CI,
+ AllocationInst &AI) {
+ const PointerType *PTy = cast<PointerType>(CI.getType());
+
+ // Remove any uses of AI that are dead.
+ assert(!CI.use_empty() && "Dead instructions should be removed earlier!");
+
+ for (Value::use_iterator UI = AI.use_begin(), E = AI.use_end(); UI != E; ) {
+ Instruction *User = cast<Instruction>(*UI++);
+ if (isInstructionTriviallyDead(User)) {
+ while (UI != E && *UI == User)
+ ++UI; // If this instruction uses AI more than once, don't break UI.
+
+ ++NumDeadInst;
+ DOUT << "IC: DCE: " << *User;
+ EraseInstFromFunction(*User);
+ }
+ }
+
+ // Get the type really allocated and the type casted to.
+ const Type *AllocElTy = AI.getAllocatedType();
+ const Type *CastElTy = PTy->getElementType();
+ if (!AllocElTy->isSized() || !CastElTy->isSized()) return 0;
+
+ unsigned AllocElTyAlign = TD->getABITypeAlignment(AllocElTy);
+ unsigned CastElTyAlign = TD->getABITypeAlignment(CastElTy);
+ if (CastElTyAlign < AllocElTyAlign) return 0;
+
+ // If the allocation has multiple uses, only promote it if we are strictly
+ // increasing the alignment of the resultant allocation. If we keep it the
+ // same, we open the door to infinite loops of various kinds.
+ if (!AI.hasOneUse() && CastElTyAlign == AllocElTyAlign) return 0;
+
+ uint64_t AllocElTySize = TD->getTypeSize(AllocElTy);
+ uint64_t CastElTySize = TD->getTypeSize(CastElTy);
+ if (CastElTySize == 0 || AllocElTySize == 0) return 0;
+
+ // See if we can satisfy the modulus by pulling a scale out of the array
+ // size argument.
+ unsigned ArraySizeScale;
+ int ArrayOffset;
+ Value *NumElements = // See if the array size is a decomposable linear expr.
+ DecomposeSimpleLinearExpr(AI.getOperand(0), ArraySizeScale, ArrayOffset);
+
+ // If we can now satisfy the modulus, by using a non-1 scale, we really can
+ // do the xform.
+ if ((AllocElTySize*ArraySizeScale) % CastElTySize != 0 ||
+ (AllocElTySize*ArrayOffset ) % CastElTySize != 0) return 0;
+
+ unsigned Scale = (AllocElTySize*ArraySizeScale)/CastElTySize;
+ Value *Amt = 0;
+ if (Scale == 1) {
+ Amt = NumElements;
+ } else {
+ // If the allocation size is constant, form a constant mul expression
+ Amt = ConstantInt::get(Type::Int32Ty, Scale);
+ if (isa<ConstantInt>(NumElements))
+ Amt = Multiply(cast<ConstantInt>(NumElements), cast<ConstantInt>(Amt));
+ // otherwise multiply the amount and the number of elements
+ else if (Scale != 1) {
+ Instruction *Tmp = BinaryOperator::createMul(Amt, NumElements, "tmp");
+ Amt = InsertNewInstBefore(Tmp, AI);
+ }
+ }
+
+ if (int Offset = (AllocElTySize*ArrayOffset)/CastElTySize) {
+ Value *Off = ConstantInt::get(Type::Int32Ty, Offset, true);
+ Instruction *Tmp = BinaryOperator::createAdd(Amt, Off, "tmp");
+ Amt = InsertNewInstBefore(Tmp, AI);
+ }
+
+ AllocationInst *New;
+ if (isa<MallocInst>(AI))
+ New = new MallocInst(CastElTy, Amt, AI.getAlignment());
+ else
+ New = new AllocaInst(CastElTy, Amt, AI.getAlignment());
+ InsertNewInstBefore(New, AI);
+ New->takeName(&AI);
+
+ // If the allocation has multiple uses, insert a cast and change all things
+ // that used it to use the new cast. This will also hack on CI, but it will
+ // die soon.
+ if (!AI.hasOneUse()) {
+ AddUsesToWorkList(AI);
+ // New is the allocation instruction, pointer typed. AI is the original
+ // allocation instruction, also pointer typed. Thus, cast to use is BitCast.
+ CastInst *NewCast = new BitCastInst(New, AI.getType(), "tmpcast");
+ InsertNewInstBefore(NewCast, AI);
+ AI.replaceAllUsesWith(NewCast);
+ }
+ return ReplaceInstUsesWith(CI, New);
+}
+
+/// CanEvaluateInDifferentType - Return true if we can take the specified value
+/// and return it as type Ty without inserting any new casts and without
+/// changing the computed value. This is used by code that tries to decide
+/// whether promoting or shrinking integer operations to wider or smaller types
+/// will allow us to eliminate a truncate or extend.
+///
+/// This is a truncation operation if Ty is smaller than V->getType(), or an
+/// extension operation if Ty is larger.
+static bool CanEvaluateInDifferentType(Value *V, const IntegerType *Ty,
+ int &NumCastsRemoved) {
+ // We can always evaluate constants in another type.
+ if (isa<ConstantInt>(V))
+ return true;
+
+ Instruction *I = dyn_cast<Instruction>(V);
+ if (!I) return false;
+
+ const IntegerType *OrigTy = cast<IntegerType>(V->getType());
+
+ switch (I->getOpcode()) {
+ case Instruction::Add:
+ case Instruction::Sub:
+ case Instruction::And:
+ case Instruction::Or:
+ case Instruction::Xor:
+ if (!I->hasOneUse()) return false;
+ // These operators can all arbitrarily be extended or truncated.
+ return CanEvaluateInDifferentType(I->getOperand(0), Ty, NumCastsRemoved) &&
+ CanEvaluateInDifferentType(I->getOperand(1), Ty, NumCastsRemoved);
+
+ case Instruction::Shl:
+ if (!I->hasOneUse()) return false;
+ // If we are truncating the result of this SHL, and if it's a shift of a
+ // constant amount, we can always perform a SHL in a smaller type.
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(I->getOperand(1))) {
+ uint32_t BitWidth = Ty->getBitWidth();
+ if (BitWidth < OrigTy->getBitWidth() &&
+ CI->getLimitedValue(BitWidth) < BitWidth)
+ return CanEvaluateInDifferentType(I->getOperand(0), Ty,NumCastsRemoved);
+ }
+ break;
+ case Instruction::LShr:
+ if (!I->hasOneUse()) return false;
+ // If this is a truncate of a logical shr, we can truncate it to a smaller
+ // lshr iff we know that the bits we would otherwise be shifting in are
+ // already zeros.
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(I->getOperand(1))) {
+ uint32_t OrigBitWidth = OrigTy->getBitWidth();
+ uint32_t BitWidth = Ty->getBitWidth();
+ if (BitWidth < OrigBitWidth &&
+ MaskedValueIsZero(I->getOperand(0),
+ APInt::getHighBitsSet(OrigBitWidth, OrigBitWidth-BitWidth)) &&
+ CI->getLimitedValue(BitWidth) < BitWidth) {
+ return CanEvaluateInDifferentType(I->getOperand(0), Ty,NumCastsRemoved);
+ }
+ }
+ break;
+ case Instruction::Trunc:
+ case Instruction::ZExt:
+ case Instruction::SExt:
+ // If this is a cast from the destination type, we can trivially eliminate
+ // it, and this will remove a cast overall.
+ if (I->getOperand(0)->getType() == Ty) {
+ // If the first operand is itself a cast, and is eliminable, do not count
+ // this as an eliminable cast. We would prefer to eliminate those two
+ // casts first.
+ if (isa<CastInst>(I->getOperand(0)))
+ return true;
+
+ ++NumCastsRemoved;
+ return true;
+ }
+ break;
+ default:
+ // TODO: Can handle more cases here.
+ break;
+ }
+
+ return false;
+}
+
+/// EvaluateInDifferentType - Given an expression that
+/// CanEvaluateInDifferentType returns true for, actually insert the code to
+/// evaluate the expression.
+Value *InstCombiner::EvaluateInDifferentType(Value *V, const Type *Ty,
+ bool isSigned) {
+ if (Constant *C = dyn_cast<Constant>(V))
+ return ConstantExpr::getIntegerCast(C, Ty, isSigned /*Sext or ZExt*/);
+
+ // Otherwise, it must be an instruction.
+ Instruction *I = cast<Instruction>(V);
+ Instruction *Res = 0;
+ switch (I->getOpcode()) {
+ case Instruction::Add:
+ case Instruction::Sub:
+ case Instruction::And:
+ case Instruction::Or:
+ case Instruction::Xor:
+ case Instruction::AShr:
+ case Instruction::LShr:
+ case Instruction::Shl: {
+ Value *LHS = EvaluateInDifferentType(I->getOperand(0), Ty, isSigned);
+ Value *RHS = EvaluateInDifferentType(I->getOperand(1), Ty, isSigned);
+ Res = BinaryOperator::create((Instruction::BinaryOps)I->getOpcode(),
+ LHS, RHS, I->getName());
+ break;
+ }
+ case Instruction::Trunc:
+ case Instruction::ZExt:
+ case Instruction::SExt:
+ case Instruction::BitCast:
+ // If the source type of the cast is the type we're trying for then we can
+ // just return the source. There's no need to insert it because its not new.
+ if (I->getOperand(0)->getType() == Ty)
+ return I->getOperand(0);
+
+ // Some other kind of cast, which shouldn't happen, so just ..
+ // FALL THROUGH
+ default:
+ // TODO: Can handle more cases here.
+ assert(0 && "Unreachable!");
+ break;
+ }
+
+ return InsertNewInstBefore(Res, *I);
+}
+
+/// @brief Implement the transforms common to all CastInst visitors.
+Instruction *InstCombiner::commonCastTransforms(CastInst &CI) {
+ Value *Src = CI.getOperand(0);
+
+ // Casting undef to anything results in undef so might as just replace it and
+ // get rid of the cast.
+ if (isa<UndefValue>(Src)) // cast undef -> undef
+ return ReplaceInstUsesWith(CI, UndefValue::get(CI.getType()));
+
+ // Many cases of "cast of a cast" are eliminable. If it's eliminable we just
+ // eliminate it now.
+ if (CastInst *CSrc = dyn_cast<CastInst>(Src)) { // A->B->C cast
+ if (Instruction::CastOps opc =
+ isEliminableCastPair(CSrc, CI.getOpcode(), CI.getType(), TD)) {
+ // The first cast (CSrc) is eliminable so we need to fix up or replace
+ // the second cast (CI). CSrc will then have a good chance of being dead.
+ return CastInst::create(opc, CSrc->getOperand(0), CI.getType());
+ }
+ }
+
+ // If we are casting a select then fold the cast into the select
+ if (SelectInst *SI = dyn_cast<SelectInst>(Src))
+ if (Instruction *NV = FoldOpIntoSelect(CI, SI, this))
+ return NV;
+
+ // If we are casting a PHI then fold the cast into the PHI
+ if (isa<PHINode>(Src))
+ if (Instruction *NV = FoldOpIntoPhi(CI))
+ return NV;
+
+ return 0;
+}
+
+/// @brief Implement the transforms for cast of pointer (bitcast/ptrtoint)
+Instruction *InstCombiner::commonPointerCastTransforms(CastInst &CI) {
+ Value *Src = CI.getOperand(0);
+
+ if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Src)) {
+ // If casting the result of a getelementptr instruction with no offset, turn
+ // this into a cast of the original pointer!
+ if (GEP->hasAllZeroIndices()) {
+ // Changing the cast operand is usually not a good idea but it is safe
+ // here because the pointer operand is being replaced with another
+ // pointer operand so the opcode doesn't need to change.
+ AddToWorkList(GEP);
+ CI.setOperand(0, GEP->getOperand(0));
+ return &CI;
+ }
+
+ // If the GEP has a single use, and the base pointer is a bitcast, and the
+ // GEP computes a constant offset, see if we can convert these three
+ // instructions into fewer. This typically happens with unions and other
+ // non-type-safe code.
+ if (GEP->hasOneUse() && isa<BitCastInst>(GEP->getOperand(0))) {
+ if (GEP->hasAllConstantIndices()) {
+ // We are guaranteed to get a constant from EmitGEPOffset.
+ ConstantInt *OffsetV = cast<ConstantInt>(EmitGEPOffset(GEP, CI, *this));
+ int64_t Offset = OffsetV->getSExtValue();
+
+ // Get the base pointer input of the bitcast, and the type it points to.
+ Value *OrigBase = cast<BitCastInst>(GEP->getOperand(0))->getOperand(0);
+ const Type *GEPIdxTy =
+ cast<PointerType>(OrigBase->getType())->getElementType();
+ if (GEPIdxTy->isSized()) {
+ SmallVector<Value*, 8> NewIndices;
+
+ // Start with the index over the outer type. Note that the type size
+ // might be zero (even if the offset isn't zero) if the indexed type
+ // is something like [0 x {int, int}]
+ const Type *IntPtrTy = TD->getIntPtrType();
+ int64_t FirstIdx = 0;
+ if (int64_t TySize = TD->getTypeSize(GEPIdxTy)) {
+ FirstIdx = Offset/TySize;
+ Offset %= TySize;
+
+ // Handle silly modulus not returning values values [0..TySize).
+ if (Offset < 0) {
+ --FirstIdx;
+ Offset += TySize;
+ assert(Offset >= 0);
+ }
+ assert((uint64_t)Offset < (uint64_t)TySize &&"Out of range offset");
+ }
+
+ NewIndices.push_back(ConstantInt::get(IntPtrTy, FirstIdx));
+
+ // Index into the types. If we fail, set OrigBase to null.
+ while (Offset) {
+ if (const StructType *STy = dyn_cast<StructType>(GEPIdxTy)) {
+ const StructLayout *SL = TD->getStructLayout(STy);
+ if (Offset < (int64_t)SL->getSizeInBytes()) {
+ unsigned Elt = SL->getElementContainingOffset(Offset);
+ NewIndices.push_back(ConstantInt::get(Type::Int32Ty, Elt));
+
+ Offset -= SL->getElementOffset(Elt);
+ GEPIdxTy = STy->getElementType(Elt);
+ } else {
+ // Otherwise, we can't index into this, bail out.
+ Offset = 0;
+ OrigBase = 0;
+ }
+ } else if (isa<ArrayType>(GEPIdxTy) || isa<VectorType>(GEPIdxTy)) {
+ const SequentialType *STy = cast<SequentialType>(GEPIdxTy);
+ if (uint64_t EltSize = TD->getTypeSize(STy->getElementType())) {
+ NewIndices.push_back(ConstantInt::get(IntPtrTy,Offset/EltSize));
+ Offset %= EltSize;
+ } else {
+ NewIndices.push_back(ConstantInt::get(IntPtrTy, 0));
+ }
+ GEPIdxTy = STy->getElementType();
+ } else {
+ // Otherwise, we can't index into this, bail out.
+ Offset = 0;
+ OrigBase = 0;
+ }
+ }
+ if (OrigBase) {
+ // If we were able to index down into an element, create the GEP
+ // and bitcast the result. This eliminates one bitcast, potentially
+ // two.
+ Instruction *NGEP = new GetElementPtrInst(OrigBase, &NewIndices[0],
+ NewIndices.size(), "");
+ InsertNewInstBefore(NGEP, CI);
+ NGEP->takeName(GEP);
+
+ if (isa<BitCastInst>(CI))
+ return new BitCastInst(NGEP, CI.getType());
+ assert(isa<PtrToIntInst>(CI));
+ return new PtrToIntInst(NGEP, CI.getType());
+ }
+ }
+ }
+ }
+ }
+
+ return commonCastTransforms(CI);
+}
+
+
+
+/// Only the TRUNC, ZEXT, SEXT, and BITCAST can both operand and result as
+/// integer types. This function implements the common transforms for all those
+/// cases.
+/// @brief Implement the transforms common to CastInst with integer operands
+Instruction *InstCombiner::commonIntCastTransforms(CastInst &CI) {
+ if (Instruction *Result = commonCastTransforms(CI))
+ return Result;
+
+ Value *Src = CI.getOperand(0);
+ const Type *SrcTy = Src->getType();
+ const Type *DestTy = CI.getType();
+ uint32_t SrcBitSize = SrcTy->getPrimitiveSizeInBits();
+ uint32_t DestBitSize = DestTy->getPrimitiveSizeInBits();
+
+ // See if we can simplify any instructions used by the LHS whose sole
+ // purpose is to compute bits we don't care about.
+ APInt KnownZero(DestBitSize, 0), KnownOne(DestBitSize, 0);
+ if (SimplifyDemandedBits(&CI, APInt::getAllOnesValue(DestBitSize),
+ KnownZero, KnownOne))
+ return &CI;
+
+ // If the source isn't an instruction or has more than one use then we
+ // can't do anything more.
+ Instruction *SrcI = dyn_cast<Instruction>(Src);
+ if (!SrcI || !Src->hasOneUse())
+ return 0;
+
+ // Attempt to propagate the cast into the instruction for int->int casts.
+ int NumCastsRemoved = 0;
+ if (!isa<BitCastInst>(CI) &&
+ CanEvaluateInDifferentType(SrcI, cast<IntegerType>(DestTy),
+ NumCastsRemoved)) {
+ // If this cast is a truncate, evaluting in a different type always
+ // eliminates the cast, so it is always a win. If this is a noop-cast
+ // this just removes a noop cast which isn't pointful, but simplifies
+ // the code. If this is a zero-extension, we need to do an AND to
+ // maintain the clear top-part of the computation, so we require that
+ // the input have eliminated at least one cast. If this is a sign
+ // extension, we insert two new casts (to do the extension) so we
+ // require that two casts have been eliminated.
+ bool DoXForm;
+ switch (CI.getOpcode()) {
+ default:
+ // All the others use floating point so we shouldn't actually
+ // get here because of the check above.
+ assert(0 && "Unknown cast type");
+ case Instruction::Trunc:
+ DoXForm = true;
+ break;
+ case Instruction::ZExt:
+ DoXForm = NumCastsRemoved >= 1;
+ break;
+ case Instruction::SExt:
+ DoXForm = NumCastsRemoved >= 2;
+ break;
+ case Instruction::BitCast:
+ DoXForm = false;
+ break;
+ }
+
+ if (DoXForm) {
+ Value *Res = EvaluateInDifferentType(SrcI, DestTy,
+ CI.getOpcode() == Instruction::SExt);
+ assert(Res->getType() == DestTy);
+ switch (CI.getOpcode()) {
+ default: assert(0 && "Unknown cast type!");
+ case Instruction::Trunc:
+ case Instruction::BitCast:
+ // Just replace this cast with the result.
+ return ReplaceInstUsesWith(CI, Res);
+ case Instruction::ZExt: {
+ // We need to emit an AND to clear the high bits.
+ assert(SrcBitSize < DestBitSize && "Not a zext?");
+ Constant *C = ConstantInt::get(APInt::getLowBitsSet(DestBitSize,
+ SrcBitSize));
+ return BinaryOperator::createAnd(Res, C);
+ }
+ case Instruction::SExt:
+ // We need to emit a cast to truncate, then a cast to sext.
+ return CastInst::create(Instruction::SExt,
+ InsertCastBefore(Instruction::Trunc, Res, Src->getType(),
+ CI), DestTy);
+ }
+ }
+ }
+
+ Value *Op0 = SrcI->getNumOperands() > 0 ? SrcI->getOperand(0) : 0;
+ Value *Op1 = SrcI->getNumOperands() > 1 ? SrcI->getOperand(1) : 0;
+
+ switch (SrcI->getOpcode()) {
+ case Instruction::Add:
+ case Instruction::Mul:
+ case Instruction::And:
+ case Instruction::Or:
+ case Instruction::Xor:
+ // If we are discarding information, rewrite.
+ if (DestBitSize <= SrcBitSize && DestBitSize != 1) {
+ // Don't insert two casts if they cannot be eliminated. We allow
+ // two casts to be inserted if the sizes are the same. This could
+ // only be converting signedness, which is a noop.
+ if (DestBitSize == SrcBitSize ||
+ !ValueRequiresCast(CI.getOpcode(), Op1, DestTy,TD) ||
+ !ValueRequiresCast(CI.getOpcode(), Op0, DestTy, TD)) {
+ Instruction::CastOps opcode = CI.getOpcode();
+ Value *Op0c = InsertOperandCastBefore(opcode, Op0, DestTy, SrcI);
+ Value *Op1c = InsertOperandCastBefore(opcode, Op1, DestTy, SrcI);
+ return BinaryOperator::create(
+ cast<BinaryOperator>(SrcI)->getOpcode(), Op0c, Op1c);
+ }
+ }
+
+ // cast (xor bool X, true) to int --> xor (cast bool X to int), 1
+ if (isa<ZExtInst>(CI) && SrcBitSize == 1 &&
+ SrcI->getOpcode() == Instruction::Xor &&
+ Op1 == ConstantInt::getTrue() &&
+ (!Op0->hasOneUse() || !isa<CmpInst>(Op0))) {
+ Value *New = InsertOperandCastBefore(Instruction::ZExt, Op0, DestTy, &CI);
+ return BinaryOperator::createXor(New, ConstantInt::get(CI.getType(), 1));
+ }
+ break;
+ case Instruction::SDiv:
+ case Instruction::UDiv:
+ case Instruction::SRem:
+ case Instruction::URem:
+ // If we are just changing the sign, rewrite.
+ if (DestBitSize == SrcBitSize) {
+ // Don't insert two casts if they cannot be eliminated. We allow
+ // two casts to be inserted if the sizes are the same. This could
+ // only be converting signedness, which is a noop.
+ if (!ValueRequiresCast(CI.getOpcode(), Op1, DestTy, TD) ||
+ !ValueRequiresCast(CI.getOpcode(), Op0, DestTy, TD)) {
+ Value *Op0c = InsertOperandCastBefore(Instruction::BitCast,
+ Op0, DestTy, SrcI);
+ Value *Op1c = InsertOperandCastBefore(Instruction::BitCast,
+ Op1, DestTy, SrcI);
+ return BinaryOperator::create(
+ cast<BinaryOperator>(SrcI)->getOpcode(), Op0c, Op1c);
+ }
+ }
+ break;
+
+ case Instruction::Shl:
+ // Allow changing the sign of the source operand. Do not allow
+ // changing the size of the shift, UNLESS the shift amount is a
+ // constant. We must not change variable sized shifts to a smaller
+ // size, because it is undefined to shift more bits out than exist
+ // in the value.
+ if (DestBitSize == SrcBitSize ||
+ (DestBitSize < SrcBitSize && isa<Constant>(Op1))) {
+ Instruction::CastOps opcode = (DestBitSize == SrcBitSize ?
+ Instruction::BitCast : Instruction::Trunc);
+ Value *Op0c = InsertOperandCastBefore(opcode, Op0, DestTy, SrcI);
+ Value *Op1c = InsertOperandCastBefore(opcode, Op1, DestTy, SrcI);
+ return BinaryOperator::createShl(Op0c, Op1c);
+ }
+ break;
+ case Instruction::AShr:
+ // If this is a signed shr, and if all bits shifted in are about to be
+ // truncated off, turn it into an unsigned shr to allow greater
+ // simplifications.
+ if (DestBitSize < SrcBitSize &&
+ isa<ConstantInt>(Op1)) {
+ uint32_t ShiftAmt = cast<ConstantInt>(Op1)->getLimitedValue(SrcBitSize);
+ if (SrcBitSize > ShiftAmt && SrcBitSize-ShiftAmt >= DestBitSize) {
+ // Insert the new logical shift right.
+ return BinaryOperator::createLShr(Op0, Op1);
+ }
+ }
+ break;
+ }
+ return 0;
+}
+
+Instruction *InstCombiner::visitTrunc(TruncInst &CI) {
+ if (Instruction *Result = commonIntCastTransforms(CI))
+ return Result;
+
+ Value *Src = CI.getOperand(0);
+ const Type *Ty = CI.getType();
+ uint32_t DestBitWidth = Ty->getPrimitiveSizeInBits();
+ uint32_t SrcBitWidth = cast<IntegerType>(Src->getType())->getBitWidth();
+
+ if (Instruction *SrcI = dyn_cast<Instruction>(Src)) {
+ switch (SrcI->getOpcode()) {
+ default: break;
+ case Instruction::LShr:
+ // We can shrink lshr to something smaller if we know the bits shifted in
+ // are already zeros.
+ if (ConstantInt *ShAmtV = dyn_cast<ConstantInt>(SrcI->getOperand(1))) {
+ uint32_t ShAmt = ShAmtV->getLimitedValue(SrcBitWidth);
+
+ // Get a mask for the bits shifting in.
+ APInt Mask(APInt::getLowBitsSet(SrcBitWidth, ShAmt).shl(DestBitWidth));
+ Value* SrcIOp0 = SrcI->getOperand(0);
+ if (SrcI->hasOneUse() && MaskedValueIsZero(SrcIOp0, Mask)) {
+ if (ShAmt >= DestBitWidth) // All zeros.
+ return ReplaceInstUsesWith(CI, Constant::getNullValue(Ty));
+
+ // Okay, we can shrink this. Truncate the input, then return a new
+ // shift.
+ Value *V1 = InsertCastBefore(Instruction::Trunc, SrcIOp0, Ty, CI);
+ Value *V2 = InsertCastBefore(Instruction::Trunc, SrcI->getOperand(1),
+ Ty, CI);
+ return BinaryOperator::createLShr(V1, V2);
+ }
+ } else { // This is a variable shr.
+
+ // Turn 'trunc (lshr X, Y) to bool' into '(X & (1 << Y)) != 0'. This is
+ // more LLVM instructions, but allows '1 << Y' to be hoisted if
+ // loop-invariant and CSE'd.
+ if (CI.getType() == Type::Int1Ty && SrcI->hasOneUse()) {
+ Value *One = ConstantInt::get(SrcI->getType(), 1);
+
+ Value *V = InsertNewInstBefore(
+ BinaryOperator::createShl(One, SrcI->getOperand(1),
+ "tmp"), CI);
+ V = InsertNewInstBefore(BinaryOperator::createAnd(V,
+ SrcI->getOperand(0),
+ "tmp"), CI);
+ Value *Zero = Constant::getNullValue(V->getType());
+ return new ICmpInst(ICmpInst::ICMP_NE, V, Zero);
+ }
+ }
+ break;
+ }
+ }
+
+ return 0;
+}
+
+Instruction *InstCombiner::visitZExt(ZExtInst &CI) {
+ // If one of the common conversion will work ..
+ if (Instruction *Result = commonIntCastTransforms(CI))
+ return Result;
+
+ Value *Src = CI.getOperand(0);
+
+ // If this is a cast of a cast
+ if (CastInst *CSrc = dyn_cast<CastInst>(Src)) { // A->B->C cast
+ // If this is a TRUNC followed by a ZEXT then we are dealing with integral
+ // types and if the sizes are just right we can convert this into a logical
+ // 'and' which will be much cheaper than the pair of casts.
+ if (isa<TruncInst>(CSrc)) {
+ // Get the sizes of the types involved
+ Value *A = CSrc->getOperand(0);
+ uint32_t SrcSize = A->getType()->getPrimitiveSizeInBits();
+ uint32_t MidSize = CSrc->getType()->getPrimitiveSizeInBits();
+ uint32_t DstSize = CI.getType()->getPrimitiveSizeInBits();
+ // If we're actually extending zero bits and the trunc is a no-op
+ if (MidSize < DstSize && SrcSize == DstSize) {
+ // Replace both of the casts with an And of the type mask.
+ APInt AndValue(APInt::getLowBitsSet(SrcSize, MidSize));
+ Constant *AndConst = ConstantInt::get(AndValue);
+ Instruction *And =
+ BinaryOperator::createAnd(CSrc->getOperand(0), AndConst);
+ // Unfortunately, if the type changed, we need to cast it back.
+ if (And->getType() != CI.getType()) {
+ And->setName(CSrc->getName()+".mask");
+ InsertNewInstBefore(And, CI);
+ And = CastInst::createIntegerCast(And, CI.getType(), false/*ZExt*/);
+ }
+ return And;
+ }
+ }
+ }
+
+ if (ICmpInst *ICI = dyn_cast<ICmpInst>(Src)) {
+ // If we are just checking for a icmp eq of a single bit and zext'ing it
+ // to an integer, then shift the bit to the appropriate place and then
+ // cast to integer to avoid the comparison.
+ if (ConstantInt *Op1C = dyn_cast<ConstantInt>(ICI->getOperand(1))) {
+ const APInt &Op1CV = Op1C->getValue();
+
+ // zext (x <s 0) to i32 --> x>>u31 true if signbit set.
+ // zext (x >s -1) to i32 --> (x>>u31)^1 true if signbit clear.
+ if ((ICI->getPredicate() == ICmpInst::ICMP_SLT && Op1CV == 0) ||
+ (ICI->getPredicate() == ICmpInst::ICMP_SGT &&Op1CV.isAllOnesValue())){
+ Value *In = ICI->getOperand(0);
+ Value *Sh = ConstantInt::get(In->getType(),
+ In->getType()->getPrimitiveSizeInBits()-1);
+ In = InsertNewInstBefore(BinaryOperator::createLShr(In, Sh,
+ In->getName()+".lobit"),
+ CI);
+ if (In->getType() != CI.getType())
+ In = CastInst::createIntegerCast(In, CI.getType(),
+ false/*ZExt*/, "tmp", &CI);
+
+ if (ICI->getPredicate() == ICmpInst::ICMP_SGT) {
+ Constant *One = ConstantInt::get(In->getType(), 1);
+ In = InsertNewInstBefore(BinaryOperator::createXor(In, One,
+ In->getName()+".not"),
+ CI);
+ }
+
+ return ReplaceInstUsesWith(CI, In);
+ }
+
+
+
+ // zext (X == 0) to i32 --> X^1 iff X has only the low bit set.
+ // zext (X == 0) to i32 --> (X>>1)^1 iff X has only the 2nd bit set.
+ // zext (X == 1) to i32 --> X iff X has only the low bit set.
+ // zext (X == 2) to i32 --> X>>1 iff X has only the 2nd bit set.
+ // zext (X != 0) to i32 --> X iff X has only the low bit set.
+ // zext (X != 0) to i32 --> X>>1 iff X has only the 2nd bit set.
+ // zext (X != 1) to i32 --> X^1 iff X has only the low bit set.
+ // zext (X != 2) to i32 --> (X>>1)^1 iff X has only the 2nd bit set.
+ if ((Op1CV == 0 || Op1CV.isPowerOf2()) &&
+ // This only works for EQ and NE
+ ICI->isEquality()) {
+ // If Op1C some other power of two, convert:
+ uint32_t BitWidth = Op1C->getType()->getBitWidth();
+ APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
+ APInt TypeMask(APInt::getAllOnesValue(BitWidth));
+ ComputeMaskedBits(ICI->getOperand(0), TypeMask, KnownZero, KnownOne);
+
+ APInt KnownZeroMask(~KnownZero);
+ if (KnownZeroMask.isPowerOf2()) { // Exactly 1 possible 1?
+ bool isNE = ICI->getPredicate() == ICmpInst::ICMP_NE;
+ if (Op1CV != 0 && (Op1CV != KnownZeroMask)) {
+ // (X&4) == 2 --> false
+ // (X&4) != 2 --> true
+ Constant *Res = ConstantInt::get(Type::Int1Ty, isNE);
+ Res = ConstantExpr::getZExt(Res, CI.getType());
+ return ReplaceInstUsesWith(CI, Res);
+ }
+
+ uint32_t ShiftAmt = KnownZeroMask.logBase2();
+ Value *In = ICI->getOperand(0);
+ if (ShiftAmt) {
+ // Perform a logical shr by shiftamt.
+ // Insert the shift to put the result in the low bit.
+ In = InsertNewInstBefore(
+ BinaryOperator::createLShr(In,
+ ConstantInt::get(In->getType(), ShiftAmt),
+ In->getName()+".lobit"), CI);
+ }
+
+ if ((Op1CV != 0) == isNE) { // Toggle the low bit.
+ Constant *One = ConstantInt::get(In->getType(), 1);
+ In = BinaryOperator::createXor(In, One, "tmp");
+ InsertNewInstBefore(cast<Instruction>(In), CI);
+ }
+
+ if (CI.getType() == In->getType())
+ return ReplaceInstUsesWith(CI, In);
+ else
+ return CastInst::createIntegerCast(In, CI.getType(), false/*ZExt*/);
+ }
+ }
+ }
+ }
+ return 0;
+}
+
+Instruction *InstCombiner::visitSExt(SExtInst &CI) {
+ if (Instruction *I = commonIntCastTransforms(CI))
+ return I;
+
+ Value *Src = CI.getOperand(0);
+
+ // sext (x <s 0) -> ashr x, 31 -> all ones if signed
+ // sext (x >s -1) -> ashr x, 31 -> all ones if not signed
+ if (ICmpInst *ICI = dyn_cast<ICmpInst>(Src)) {
+ // If we are just checking for a icmp eq of a single bit and zext'ing it
+ // to an integer, then shift the bit to the appropriate place and then
+ // cast to integer to avoid the comparison.
+ if (ConstantInt *Op1C = dyn_cast<ConstantInt>(ICI->getOperand(1))) {
+ const APInt &Op1CV = Op1C->getValue();
+
+ // sext (x <s 0) to i32 --> x>>s31 true if signbit set.
+ // sext (x >s -1) to i32 --> (x>>s31)^-1 true if signbit clear.
+ if ((ICI->getPredicate() == ICmpInst::ICMP_SLT && Op1CV == 0) ||
+ (ICI->getPredicate() == ICmpInst::ICMP_SGT &&Op1CV.isAllOnesValue())){
+ Value *In = ICI->getOperand(0);
+ Value *Sh = ConstantInt::get(In->getType(),
+ In->getType()->getPrimitiveSizeInBits()-1);
+ In = InsertNewInstBefore(BinaryOperator::createAShr(In, Sh,
+ In->getName()+".lobit"),
+ CI);
+ if (In->getType() != CI.getType())
+ In = CastInst::createIntegerCast(In, CI.getType(),
+ true/*SExt*/, "tmp", &CI);
+
+ if (ICI->getPredicate() == ICmpInst::ICMP_SGT)
+ In = InsertNewInstBefore(BinaryOperator::createNot(In,
+ In->getName()+".not"), CI);
+
+ return ReplaceInstUsesWith(CI, In);
+ }
+ }
+ }
+
+ return 0;
+}
+
+Instruction *InstCombiner::visitFPTrunc(CastInst &CI) {
+ return commonCastTransforms(CI);
+}
+
+Instruction *InstCombiner::visitFPExt(CastInst &CI) {
+ return commonCastTransforms(CI);
+}
+
+Instruction *InstCombiner::visitFPToUI(CastInst &CI) {
+ return commonCastTransforms(CI);
+}
+
+Instruction *InstCombiner::visitFPToSI(CastInst &CI) {
+ return commonCastTransforms(CI);
+}
+
+Instruction *InstCombiner::visitUIToFP(CastInst &CI) {
+ return commonCastTransforms(CI);
+}
+
+Instruction *InstCombiner::visitSIToFP(CastInst &CI) {
+ return commonCastTransforms(CI);
+}
+
+Instruction *InstCombiner::visitPtrToInt(CastInst &CI) {
+ return commonPointerCastTransforms(CI);
+}
+
+Instruction *InstCombiner::visitIntToPtr(CastInst &CI) {
+ return commonCastTransforms(CI);
+}
+
+Instruction *InstCombiner::visitBitCast(BitCastInst &CI) {
+ // If the operands are integer typed then apply the integer transforms,
+ // otherwise just apply the common ones.
+ Value *Src = CI.getOperand(0);
+ const Type *SrcTy = Src->getType();
+ const Type *DestTy = CI.getType();
+
+ if (SrcTy->isInteger() && DestTy->isInteger()) {
+ if (Instruction *Result = commonIntCastTransforms(CI))
+ return Result;
+ } else if (isa<PointerType>(SrcTy)) {
+ if (Instruction *I = commonPointerCastTransforms(CI))
+ return I;
+ } else {
+ if (Instruction *Result = commonCastTransforms(CI))
+ return Result;
+ }
+
+
+ // Get rid of casts from one type to the same type. These are useless and can
+ // be replaced by the operand.
+ if (DestTy == Src->getType())
+ return ReplaceInstUsesWith(CI, Src);
+
+ if (const PointerType *DstPTy = dyn_cast<PointerType>(DestTy)) {
+ const PointerType *SrcPTy = cast<PointerType>(SrcTy);
+ const Type *DstElTy = DstPTy->getElementType();
+ const Type *SrcElTy = SrcPTy->getElementType();
+
+ // If we are casting a malloc or alloca to a pointer to a type of the same
+ // size, rewrite the allocation instruction to allocate the "right" type.
+ if (AllocationInst *AI = dyn_cast<AllocationInst>(Src))
+ if (Instruction *V = PromoteCastOfAllocation(CI, *AI))
+ return V;
+
+ // If the source and destination are pointers, and this cast is equivalent
+ // to a getelementptr X, 0, 0, 0... turn it into the appropriate gep.
+ // This can enhance SROA and other transforms that want type-safe pointers.
+ Constant *ZeroUInt = Constant::getNullValue(Type::Int32Ty);
+ unsigned NumZeros = 0;
+ while (SrcElTy != DstElTy &&
+ isa<CompositeType>(SrcElTy) && !isa<PointerType>(SrcElTy) &&
+ SrcElTy->getNumContainedTypes() /* not "{}" */) {
+ SrcElTy = cast<CompositeType>(SrcElTy)->getTypeAtIndex(ZeroUInt);
+ ++NumZeros;
+ }
+
+ // If we found a path from the src to dest, create the getelementptr now.
+ if (SrcElTy == DstElTy) {
+ SmallVector<Value*, 8> Idxs(NumZeros+1, ZeroUInt);
+ return new GetElementPtrInst(Src, &Idxs[0], Idxs.size());
+ }
+ }
+
+ if (ShuffleVectorInst *SVI = dyn_cast<ShuffleVectorInst>(Src)) {
+ if (SVI->hasOneUse()) {
+ // Okay, we have (bitconvert (shuffle ..)). Check to see if this is
+ // a bitconvert to a vector with the same # elts.
+ if (isa<VectorType>(DestTy) &&
+ cast<VectorType>(DestTy)->getNumElements() ==
+ SVI->getType()->getNumElements()) {
+ CastInst *Tmp;
+ // If either of the operands is a cast from CI.getType(), then
+ // evaluating the shuffle in the casted destination's type will allow
+ // us to eliminate at least one cast.
+ if (((Tmp = dyn_cast<CastInst>(SVI->getOperand(0))) &&
+ Tmp->getOperand(0)->getType() == DestTy) ||
+ ((Tmp = dyn_cast<CastInst>(SVI->getOperand(1))) &&
+ Tmp->getOperand(0)->getType() == DestTy)) {
+ Value *LHS = InsertOperandCastBefore(Instruction::BitCast,
+ SVI->getOperand(0), DestTy, &CI);
+ Value *RHS = InsertOperandCastBefore(Instruction::BitCast,
+ SVI->getOperand(1), DestTy, &CI);
+ // Return a new shuffle vector. Use the same element ID's, as we
+ // know the vector types match #elts.
+ return new ShuffleVectorInst(LHS, RHS, SVI->getOperand(2));
+ }
+ }
+ }
+ }
+ return 0;
+}
+
+/// GetSelectFoldableOperands - We want to turn code that looks like this:
+/// %C = or %A, %B
+/// %D = select %cond, %C, %A
+/// into:
+/// %C = select %cond, %B, 0
+/// %D = or %A, %C
+///
+/// Assuming that the specified instruction is an operand to the select, return
+/// a bitmask indicating which operands of this instruction are foldable if they
+/// equal the other incoming value of the select.
+///
+static unsigned GetSelectFoldableOperands(Instruction *I) {
+ switch (I->getOpcode()) {
+ case Instruction::Add:
+ case Instruction::Mul:
+ case Instruction::And:
+ case Instruction::Or:
+ case Instruction::Xor:
+ return 3; // Can fold through either operand.
+ case Instruction::Sub: // Can only fold on the amount subtracted.
+ case Instruction::Shl: // Can only fold on the shift amount.
+ case Instruction::LShr:
+ case Instruction::AShr:
+ return 1;
+ default:
+ return 0; // Cannot fold
+ }
+}
+
+/// GetSelectFoldableConstant - For the same transformation as the previous
+/// function, return the identity constant that goes into the select.
+static Constant *GetSelectFoldableConstant(Instruction *I) {
+ switch (I->getOpcode()) {
+ default: assert(0 && "This cannot happen!"); abort();
+ case Instruction::Add:
+ case Instruction::Sub:
+ case Instruction::Or:
+ case Instruction::Xor:
+ case Instruction::Shl:
+ case Instruction::LShr:
+ case Instruction::AShr:
+ return Constant::getNullValue(I->getType());
+ case Instruction::And:
+ return Constant::getAllOnesValue(I->getType());
+ case Instruction::Mul:
+ return ConstantInt::get(I->getType(), 1);
+ }
+}
+
+/// FoldSelectOpOp - Here we have (select c, TI, FI), and we know that TI and FI
+/// have the same opcode and only one use each. Try to simplify this.
+Instruction *InstCombiner::FoldSelectOpOp(SelectInst &SI, Instruction *TI,
+ Instruction *FI) {
+ if (TI->getNumOperands() == 1) {
+ // If this is a non-volatile load or a cast from the same type,
+ // merge.
+ if (TI->isCast()) {
+ if (TI->getOperand(0)->getType() != FI->getOperand(0)->getType())
+ return 0;
+ } else {
+ return 0; // unknown unary op.
+ }
+
+ // Fold this by inserting a select from the input values.
+ SelectInst *NewSI = new SelectInst(SI.getCondition(), TI->getOperand(0),
+ FI->getOperand(0), SI.getName()+".v");
+ InsertNewInstBefore(NewSI, SI);
+ return CastInst::create(Instruction::CastOps(TI->getOpcode()), NewSI,
+ TI->getType());
+ }
+
+ // Only handle binary operators here.
+ if (!isa<BinaryOperator>(TI))
+ return 0;
+
+ // Figure out if the operations have any operands in common.
+ Value *MatchOp, *OtherOpT, *OtherOpF;
+ bool MatchIsOpZero;
+ if (TI->getOperand(0) == FI->getOperand(0)) {
+ MatchOp = TI->getOperand(0);
+ OtherOpT = TI->getOperand(1);
+ OtherOpF = FI->getOperand(1);
+ MatchIsOpZero = true;
+ } else if (TI->getOperand(1) == FI->getOperand(1)) {
+ MatchOp = TI->getOperand(1);
+ OtherOpT = TI->getOperand(0);
+ OtherOpF = FI->getOperand(0);
+ MatchIsOpZero = false;
+ } else if (!TI->isCommutative()) {
+ return 0;
+ } else if (TI->getOperand(0) == FI->getOperand(1)) {
+ MatchOp = TI->getOperand(0);
+ OtherOpT = TI->getOperand(1);
+ OtherOpF = FI->getOperand(0);
+ MatchIsOpZero = true;
+ } else if (TI->getOperand(1) == FI->getOperand(0)) {
+ MatchOp = TI->getOperand(1);
+ OtherOpT = TI->getOperand(0);
+ OtherOpF = FI->getOperand(1);
+ MatchIsOpZero = true;
+ } else {
+ return 0;
+ }
+
+ // If we reach here, they do have operations in common.
+ SelectInst *NewSI = new SelectInst(SI.getCondition(), OtherOpT,
+ OtherOpF, SI.getName()+".v");
+ InsertNewInstBefore(NewSI, SI);
+
+ if (BinaryOperator *BO = dyn_cast<BinaryOperator>(TI)) {
+ if (MatchIsOpZero)
+ return BinaryOperator::create(BO->getOpcode(), MatchOp, NewSI);
+ else
+ return BinaryOperator::create(BO->getOpcode(), NewSI, MatchOp);
+ }
+ assert(0 && "Shouldn't get here");
+ return 0;
+}
+
+Instruction *InstCombiner::visitSelectInst(SelectInst &SI) {
+ Value *CondVal = SI.getCondition();
+ Value *TrueVal = SI.getTrueValue();
+ Value *FalseVal = SI.getFalseValue();
+
+ // select true, X, Y -> X
+ // select false, X, Y -> Y
+ if (ConstantInt *C = dyn_cast<ConstantInt>(CondVal))
+ return ReplaceInstUsesWith(SI, C->getZExtValue() ? TrueVal : FalseVal);
+
+ // select C, X, X -> X
+ if (TrueVal == FalseVal)
+ return ReplaceInstUsesWith(SI, TrueVal);
+
+ if (isa<UndefValue>(TrueVal)) // select C, undef, X -> X
+ return ReplaceInstUsesWith(SI, FalseVal);
+ if (isa<UndefValue>(FalseVal)) // select C, X, undef -> X
+ return ReplaceInstUsesWith(SI, TrueVal);
+ if (isa<UndefValue>(CondVal)) { // select undef, X, Y -> X or Y
+ if (isa<Constant>(TrueVal))
+ return ReplaceInstUsesWith(SI, TrueVal);
+ else
+ return ReplaceInstUsesWith(SI, FalseVal);
+ }
+
+ if (SI.getType() == Type::Int1Ty) {
+ if (ConstantInt *C = dyn_cast<ConstantInt>(TrueVal)) {
+ if (C->getZExtValue()) {
+ // Change: A = select B, true, C --> A = or B, C
+ return BinaryOperator::createOr(CondVal, FalseVal);
+ } else {
+ // Change: A = select B, false, C --> A = and !B, C
+ Value *NotCond =
+ InsertNewInstBefore(BinaryOperator::createNot(CondVal,
+ "not."+CondVal->getName()), SI);
+ return BinaryOperator::createAnd(NotCond, FalseVal);
+ }
+ } else if (ConstantInt *C = dyn_cast<ConstantInt>(FalseVal)) {
+ if (C->getZExtValue() == false) {
+ // Change: A = select B, C, false --> A = and B, C
+ return BinaryOperator::createAnd(CondVal, TrueVal);
+ } else {
+ // Change: A = select B, C, true --> A = or !B, C
+ Value *NotCond =
+ InsertNewInstBefore(BinaryOperator::createNot(CondVal,
+ "not."+CondVal->getName()), SI);
+ return BinaryOperator::createOr(NotCond, TrueVal);
+ }
+ }
+ }
+
+ // Selecting between two integer constants?
+ if (ConstantInt *TrueValC = dyn_cast<ConstantInt>(TrueVal))
+ if (ConstantInt *FalseValC = dyn_cast<ConstantInt>(FalseVal)) {
+ // select C, 1, 0 -> zext C to int
+ if (FalseValC->isZero() && TrueValC->getValue() == 1) {
+ return CastInst::create(Instruction::ZExt, CondVal, SI.getType());
+ } else if (TrueValC->isZero() && FalseValC->getValue() == 1) {
+ // select C, 0, 1 -> zext !C to int
+ Value *NotCond =
+ InsertNewInstBefore(BinaryOperator::createNot(CondVal,
+ "not."+CondVal->getName()), SI);
+ return CastInst::create(Instruction::ZExt, NotCond, SI.getType());
+ }
+
+ // FIXME: Turn select 0/-1 and -1/0 into sext from condition!
+
+ if (ICmpInst *IC = dyn_cast<ICmpInst>(SI.getCondition())) {
+
+ // (x <s 0) ? -1 : 0 -> ashr x, 31
+ if (TrueValC->isAllOnesValue() && FalseValC->isZero())
+ if (ConstantInt *CmpCst = dyn_cast<ConstantInt>(IC->getOperand(1))) {
+ if (IC->getPredicate() == ICmpInst::ICMP_SLT && CmpCst->isZero()) {
+ // The comparison constant and the result are not neccessarily the
+ // same width. Make an all-ones value by inserting a AShr.
+ Value *X = IC->getOperand(0);
+ uint32_t Bits = X->getType()->getPrimitiveSizeInBits();
+ Constant *ShAmt = ConstantInt::get(X->getType(), Bits-1);
+ Instruction *SRA = BinaryOperator::create(Instruction::AShr, X,
+ ShAmt, "ones");
+ InsertNewInstBefore(SRA, SI);
+
+ // Finally, convert to the type of the select RHS. We figure out
+ // if this requires a SExt, Trunc or BitCast based on the sizes.
+ Instruction::CastOps opc = Instruction::BitCast;
+ uint32_t SRASize = SRA->getType()->getPrimitiveSizeInBits();
+ uint32_t SISize = SI.getType()->getPrimitiveSizeInBits();
+ if (SRASize < SISize)
+ opc = Instruction::SExt;
+ else if (SRASize > SISize)
+ opc = Instruction::Trunc;
+ return CastInst::create(opc, SRA, SI.getType());
+ }
+ }
+
+
+ // If one of the constants is zero (we know they can't both be) and we
+ // have an icmp instruction with zero, and we have an 'and' with the
+ // non-constant value, eliminate this whole mess. This corresponds to
+ // cases like this: ((X & 27) ? 27 : 0)
+ if (TrueValC->isZero() || FalseValC->isZero())
+ if (IC->isEquality() && isa<ConstantInt>(IC->getOperand(1)) &&
+ cast<Constant>(IC->getOperand(1))->isNullValue())
+ if (Instruction *ICA = dyn_cast<Instruction>(IC->getOperand(0)))
+ if (ICA->getOpcode() == Instruction::And &&
+ isa<ConstantInt>(ICA->getOperand(1)) &&
+ (ICA->getOperand(1) == TrueValC ||
+ ICA->getOperand(1) == FalseValC) &&
+ isOneBitSet(cast<ConstantInt>(ICA->getOperand(1)))) {
+ // Okay, now we know that everything is set up, we just don't
+ // know whether we have a icmp_ne or icmp_eq and whether the
+ // true or false val is the zero.
+ bool ShouldNotVal = !TrueValC->isZero();
+ ShouldNotVal ^= IC->getPredicate() == ICmpInst::ICMP_NE;
+ Value *V = ICA;
+ if (ShouldNotVal)
+ V = InsertNewInstBefore(BinaryOperator::create(
+ Instruction::Xor, V, ICA->getOperand(1)), SI);
+ return ReplaceInstUsesWith(SI, V);
+ }
+ }
+ }
+
+ // See if we are selecting two values based on a comparison of the two values.
+ if (FCmpInst *FCI = dyn_cast<FCmpInst>(CondVal)) {
+ if (FCI->getOperand(0) == TrueVal && FCI->getOperand(1) == FalseVal) {
+ // Transform (X == Y) ? X : Y -> Y
+ if (FCI->getPredicate() == FCmpInst::FCMP_OEQ)
+ return ReplaceInstUsesWith(SI, FalseVal);
+ // Transform (X != Y) ? X : Y -> X
+ if (FCI->getPredicate() == FCmpInst::FCMP_ONE)
+ return ReplaceInstUsesWith(SI, TrueVal);
+ // NOTE: if we wanted to, this is where to detect MIN/MAX/ABS/etc.
+
+ } else if (FCI->getOperand(0) == FalseVal && FCI->getOperand(1) == TrueVal){
+ // Transform (X == Y) ? Y : X -> X
+ if (FCI->getPredicate() == FCmpInst::FCMP_OEQ)
+ return ReplaceInstUsesWith(SI, FalseVal);
+ // Transform (X != Y) ? Y : X -> Y
+ if (FCI->getPredicate() == FCmpInst::FCMP_ONE)
+ return ReplaceInstUsesWith(SI, TrueVal);
+ // NOTE: if we wanted to, this is where to detect MIN/MAX/ABS/etc.
+ }
+ }
+
+ // See if we are selecting two values based on a comparison of the two values.
+ if (ICmpInst *ICI = dyn_cast<ICmpInst>(CondVal)) {
+ if (ICI->getOperand(0) == TrueVal && ICI->getOperand(1) == FalseVal) {
+ // Transform (X == Y) ? X : Y -> Y
+ if (ICI->getPredicate() == ICmpInst::ICMP_EQ)
+ return ReplaceInstUsesWith(SI, FalseVal);
+ // Transform (X != Y) ? X : Y -> X
+ if (ICI->getPredicate() == ICmpInst::ICMP_NE)
+ return ReplaceInstUsesWith(SI, TrueVal);
+ // NOTE: if we wanted to, this is where to detect MIN/MAX/ABS/etc.
+
+ } else if (ICI->getOperand(0) == FalseVal && ICI->getOperand(1) == TrueVal){
+ // Transform (X == Y) ? Y : X -> X
+ if (ICI->getPredicate() == ICmpInst::ICMP_EQ)
+ return ReplaceInstUsesWith(SI, FalseVal);
+ // Transform (X != Y) ? Y : X -> Y
+ if (ICI->getPredicate() == ICmpInst::ICMP_NE)
+ return ReplaceInstUsesWith(SI, TrueVal);
+ // NOTE: if we wanted to, this is where to detect MIN/MAX/ABS/etc.
+ }
+ }
+
+ if (Instruction *TI = dyn_cast<Instruction>(TrueVal))
+ if (Instruction *FI = dyn_cast<Instruction>(FalseVal))
+ if (TI->hasOneUse() && FI->hasOneUse()) {
+ Instruction *AddOp = 0, *SubOp = 0;
+
+ // Turn (select C, (op X, Y), (op X, Z)) -> (op X, (select C, Y, Z))
+ if (TI->getOpcode() == FI->getOpcode())
+ if (Instruction *IV = FoldSelectOpOp(SI, TI, FI))
+ return IV;
+
+ // Turn select C, (X+Y), (X-Y) --> (X+(select C, Y, (-Y))). This is
+ // even legal for FP.
+ if (TI->getOpcode() == Instruction::Sub &&
+ FI->getOpcode() == Instruction::Add) {
+ AddOp = FI; SubOp = TI;
+ } else if (FI->getOpcode() == Instruction::Sub &&
+ TI->getOpcode() == Instruction::Add) {
+ AddOp = TI; SubOp = FI;
+ }
+
+ if (AddOp) {
+ Value *OtherAddOp = 0;
+ if (SubOp->getOperand(0) == AddOp->getOperand(0)) {
+ OtherAddOp = AddOp->getOperand(1);
+ } else if (SubOp->getOperand(0) == AddOp->getOperand(1)) {
+ OtherAddOp = AddOp->getOperand(0);
+ }
+
+ if (OtherAddOp) {
+ // So at this point we know we have (Y -> OtherAddOp):
+ // select C, (add X, Y), (sub X, Z)
+ Value *NegVal; // Compute -Z
+ if (Constant *C = dyn_cast<Constant>(SubOp->getOperand(1))) {
+ NegVal = ConstantExpr::getNeg(C);
+ } else {
+ NegVal = InsertNewInstBefore(
+ BinaryOperator::createNeg(SubOp->getOperand(1), "tmp"), SI);
+ }
+
+ Value *NewTrueOp = OtherAddOp;
+ Value *NewFalseOp = NegVal;
+ if (AddOp != TI)
+ std::swap(NewTrueOp, NewFalseOp);
+ Instruction *NewSel =
+ new SelectInst(CondVal, NewTrueOp,NewFalseOp,SI.getName()+".p");
+
+ NewSel = InsertNewInstBefore(NewSel, SI);
+ return BinaryOperator::createAdd(SubOp->getOperand(0), NewSel);
+ }
+ }
+ }
+
+ // See if we can fold the select into one of our operands.
+ if (SI.getType()->isInteger()) {
+ // See the comment above GetSelectFoldableOperands for a description of the
+ // transformation we are doing here.
+ if (Instruction *TVI = dyn_cast<Instruction>(TrueVal))
+ if (TVI->hasOneUse() && TVI->getNumOperands() == 2 &&
+ !isa<Constant>(FalseVal))
+ if (unsigned SFO = GetSelectFoldableOperands(TVI)) {
+ unsigned OpToFold = 0;
+ if ((SFO & 1) && FalseVal == TVI->getOperand(0)) {
+ OpToFold = 1;
+ } else if ((SFO & 2) && FalseVal == TVI->getOperand(1)) {
+ OpToFold = 2;
+ }
+
+ if (OpToFold) {
+ Constant *C = GetSelectFoldableConstant(TVI);
+ Instruction *NewSel =
+ new SelectInst(SI.getCondition(), TVI->getOperand(2-OpToFold), C);
+ InsertNewInstBefore(NewSel, SI);
+ NewSel->takeName(TVI);
+ if (BinaryOperator *BO = dyn_cast<BinaryOperator>(TVI))
+ return BinaryOperator::create(BO->getOpcode(), FalseVal, NewSel);
+ else {
+ assert(0 && "Unknown instruction!!");
+ }
+ }
+ }
+
+ if (Instruction *FVI = dyn_cast<Instruction>(FalseVal))
+ if (FVI->hasOneUse() && FVI->getNumOperands() == 2 &&
+ !isa<Constant>(TrueVal))
+ if (unsigned SFO = GetSelectFoldableOperands(FVI)) {
+ unsigned OpToFold = 0;
+ if ((SFO & 1) && TrueVal == FVI->getOperand(0)) {
+ OpToFold = 1;
+ } else if ((SFO & 2) && TrueVal == FVI->getOperand(1)) {
+ OpToFold = 2;
+ }
+
+ if (OpToFold) {
+ Constant *C = GetSelectFoldableConstant(FVI);
+ Instruction *NewSel =
+ new SelectInst(SI.getCondition(), C, FVI->getOperand(2-OpToFold));
+ InsertNewInstBefore(NewSel, SI);
+ NewSel->takeName(FVI);
+ if (BinaryOperator *BO = dyn_cast<BinaryOperator>(FVI))
+ return BinaryOperator::create(BO->getOpcode(), TrueVal, NewSel);
+ else
+ assert(0 && "Unknown instruction!!");
+ }
+ }
+ }
+
+ if (BinaryOperator::isNot(CondVal)) {
+ SI.setOperand(0, BinaryOperator::getNotArgument(CondVal));
+ SI.setOperand(1, FalseVal);
+ SI.setOperand(2, TrueVal);
+ return &SI;
+ }
+
+ return 0;
+}
+
+/// GetKnownAlignment - If the specified pointer has an alignment that we can
+/// determine, return it, otherwise return 0.
+static unsigned GetKnownAlignment(Value *V, TargetData *TD) {
+ if (GlobalVariable *GV = dyn_cast<GlobalVariable>(V)) {
+ unsigned Align = GV->getAlignment();
+ if (Align == 0 && TD)
+ Align = TD->getPrefTypeAlignment(GV->getType()->getElementType());
+ return Align;
+ } else if (AllocationInst *AI = dyn_cast<AllocationInst>(V)) {
+ unsigned Align = AI->getAlignment();
+ if (Align == 0 && TD) {
+ if (isa<AllocaInst>(AI))
+ Align = TD->getPrefTypeAlignment(AI->getType()->getElementType());
+ else if (isa<MallocInst>(AI)) {
+ // Malloc returns maximally aligned memory.
+ Align = TD->getABITypeAlignment(AI->getType()->getElementType());
+ Align =
+ std::max(Align,
+ (unsigned)TD->getABITypeAlignment(Type::DoubleTy));
+ Align =
+ std::max(Align,
+ (unsigned)TD->getABITypeAlignment(Type::Int64Ty));
+ }
+ }
+ return Align;
+ } else if (isa<BitCastInst>(V) ||
+ (isa<ConstantExpr>(V) &&
+ cast<ConstantExpr>(V)->getOpcode() == Instruction::BitCast)) {
+ User *CI = cast<User>(V);
+ if (isa<PointerType>(CI->getOperand(0)->getType()))
+ return GetKnownAlignment(CI->getOperand(0), TD);
+ return 0;
+ } else if (User *GEPI = dyn_castGetElementPtr(V)) {
+ unsigned BaseAlignment = GetKnownAlignment(GEPI->getOperand(0), TD);
+ if (BaseAlignment == 0) return 0;
+
+ // If all indexes are zero, it is just the alignment of the base pointer.
+ bool AllZeroOperands = true;
+ for (unsigned i = 1, e = GEPI->getNumOperands(); i != e; ++i)
+ if (!isa<Constant>(GEPI->getOperand(i)) ||
+ !cast<Constant>(GEPI->getOperand(i))->isNullValue()) {
+ AllZeroOperands = false;
+ break;
+ }
+ if (AllZeroOperands)
+ return BaseAlignment;
+
+ // Otherwise, if the base alignment is >= the alignment we expect for the
+ // base pointer type, then we know that the resultant pointer is aligned at
+ // least as much as its type requires.
+ if (!TD) return 0;
+
+ const Type *BasePtrTy = GEPI->getOperand(0)->getType();
+ const PointerType *PtrTy = cast<PointerType>(BasePtrTy);
+ if (TD->getABITypeAlignment(PtrTy->getElementType())
+ <= BaseAlignment) {
+ const Type *GEPTy = GEPI->getType();
+ const PointerType *GEPPtrTy = cast<PointerType>(GEPTy);
+ return TD->getABITypeAlignment(GEPPtrTy->getElementType());
+ }
+ return 0;
+ }
+ return 0;
+}
+
+
+/// visitCallInst - CallInst simplification. This mostly only handles folding
+/// of intrinsic instructions. For normal calls, it allows visitCallSite to do
+/// the heavy lifting.
+///
+Instruction *InstCombiner::visitCallInst(CallInst &CI) {
+ IntrinsicInst *II = dyn_cast<IntrinsicInst>(&CI);
+ if (!II) return visitCallSite(&CI);
+
+ // Intrinsics cannot occur in an invoke, so handle them here instead of in
+ // visitCallSite.
+ if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(II)) {
+ bool Changed = false;
+
+ // memmove/cpy/set of zero bytes is a noop.
+ if (Constant *NumBytes = dyn_cast<Constant>(MI->getLength())) {
+ if (NumBytes->isNullValue()) return EraseInstFromFunction(CI);
+
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(NumBytes))
+ if (CI->getZExtValue() == 1) {
+ // Replace the instruction with just byte operations. We would
+ // transform other cases to loads/stores, but we don't know if
+ // alignment is sufficient.
+ }
+ }
+
+ // If we have a memmove and the source operation is a constant global,
+ // then the source and dest pointers can't alias, so we can change this
+ // into a call to memcpy.
+ if (MemMoveInst *MMI = dyn_cast<MemMoveInst>(II)) {
+ if (GlobalVariable *GVSrc = dyn_cast<GlobalVariable>(MMI->getSource()))
+ if (GVSrc->isConstant()) {
+ Module *M = CI.getParent()->getParent()->getParent();
+ const char *Name;
+ if (CI.getCalledFunction()->getFunctionType()->getParamType(2) ==
+ Type::Int32Ty)
+ Name = "llvm.memcpy.i32";
+ else
+ Name = "llvm.memcpy.i64";
+ Constant *MemCpy = M->getOrInsertFunction(Name,
+ CI.getCalledFunction()->getFunctionType());
+ CI.setOperand(0, MemCpy);
+ Changed = true;
+ }
+ }
+
+ // If we can determine a pointer alignment that is bigger than currently
+ // set, update the alignment.
+ if (isa<MemCpyInst>(MI) || isa<MemMoveInst>(MI)) {
+ unsigned Alignment1 = GetKnownAlignment(MI->getOperand(1), TD);
+ unsigned Alignment2 = GetKnownAlignment(MI->getOperand(2), TD);
+ unsigned Align = std::min(Alignment1, Alignment2);
+ if (MI->getAlignment()->getZExtValue() < Align) {
+ MI->setAlignment(ConstantInt::get(Type::Int32Ty, Align));
+ Changed = true;
+ }
+ } else if (isa<MemSetInst>(MI)) {
+ unsigned Alignment = GetKnownAlignment(MI->getDest(), TD);
+ if (MI->getAlignment()->getZExtValue() < Alignment) {
+ MI->setAlignment(ConstantInt::get(Type::Int32Ty, Alignment));
+ Changed = true;
+ }
+ }
+
+ if (Changed) return II;
+ } else {
+ switch (II->getIntrinsicID()) {
+ default: break;
+ case Intrinsic::ppc_altivec_lvx:
+ case Intrinsic::ppc_altivec_lvxl:
+ case Intrinsic::x86_sse_loadu_ps:
+ case Intrinsic::x86_sse2_loadu_pd:
+ case Intrinsic::x86_sse2_loadu_dq:
+ // Turn PPC lvx -> load if the pointer is known aligned.
+ // Turn X86 loadups -> load if the pointer is known aligned.
+ if (GetKnownAlignment(II->getOperand(1), TD) >= 16) {
+ Value *Ptr = InsertCastBefore(Instruction::BitCast, II->getOperand(1),
+ PointerType::get(II->getType()), CI);
+ return new LoadInst(Ptr);
+ }
+ break;
+ case Intrinsic::ppc_altivec_stvx:
+ case Intrinsic::ppc_altivec_stvxl:
+ // Turn stvx -> store if the pointer is known aligned.
+ if (GetKnownAlignment(II->getOperand(2), TD) >= 16) {
+ const Type *OpPtrTy = PointerType::get(II->getOperand(1)->getType());
+ Value *Ptr = InsertCastBefore(Instruction::BitCast, II->getOperand(2),
+ OpPtrTy, CI);
+ return new StoreInst(II->getOperand(1), Ptr);
+ }
+ break;
+ case Intrinsic::x86_sse_storeu_ps:
+ case Intrinsic::x86_sse2_storeu_pd:
+ case Intrinsic::x86_sse2_storeu_dq:
+ case Intrinsic::x86_sse2_storel_dq:
+ // Turn X86 storeu -> store if the pointer is known aligned.
+ if (GetKnownAlignment(II->getOperand(1), TD) >= 16) {
+ const Type *OpPtrTy = PointerType::get(II->getOperand(2)->getType());
+ Value *Ptr = InsertCastBefore(Instruction::BitCast, II->getOperand(1),
+ OpPtrTy, CI);
+ return new StoreInst(II->getOperand(2), Ptr);
+ }
+ break;
+
+ case Intrinsic::x86_sse_cvttss2si: {
+ // These intrinsics only demands the 0th element of its input vector. If
+ // we can simplify the input based on that, do so now.
+ uint64_t UndefElts;
+ if (Value *V = SimplifyDemandedVectorElts(II->getOperand(1), 1,
+ UndefElts)) {
+ II->setOperand(1, V);
+ return II;
+ }
+ break;
+ }
+
+ case Intrinsic::ppc_altivec_vperm:
+ // Turn vperm(V1,V2,mask) -> shuffle(V1,V2,mask) if mask is a constant.
+ if (ConstantVector *Mask = dyn_cast<ConstantVector>(II->getOperand(3))) {
+ assert(Mask->getNumOperands() == 16 && "Bad type for intrinsic!");
+
+ // Check that all of the elements are integer constants or undefs.
+ bool AllEltsOk = true;
+ for (unsigned i = 0; i != 16; ++i) {
+ if (!isa<ConstantInt>(Mask->getOperand(i)) &&
+ !isa<UndefValue>(Mask->getOperand(i))) {
+ AllEltsOk = false;
+ break;
+ }
+ }
+
+ if (AllEltsOk) {
+ // Cast the input vectors to byte vectors.
+ Value *Op0 = InsertCastBefore(Instruction::BitCast,
+ II->getOperand(1), Mask->getType(), CI);
+ Value *Op1 = InsertCastBefore(Instruction::BitCast,
+ II->getOperand(2), Mask->getType(), CI);
+ Value *Result = UndefValue::get(Op0->getType());
+
+ // Only extract each element once.
+ Value *ExtractedElts[32];
+ memset(ExtractedElts, 0, sizeof(ExtractedElts));
+
+ for (unsigned i = 0; i != 16; ++i) {
+ if (isa<UndefValue>(Mask->getOperand(i)))
+ continue;
+ unsigned Idx=cast<ConstantInt>(Mask->getOperand(i))->getZExtValue();
+ Idx &= 31; // Match the hardware behavior.
+
+ if (ExtractedElts[Idx] == 0) {
+ Instruction *Elt =
+ new ExtractElementInst(Idx < 16 ? Op0 : Op1, Idx&15, "tmp");
+ InsertNewInstBefore(Elt, CI);
+ ExtractedElts[Idx] = Elt;
+ }
+
+ // Insert this value into the result vector.
+ Result = new InsertElementInst(Result, ExtractedElts[Idx], i,"tmp");
+ InsertNewInstBefore(cast<Instruction>(Result), CI);
+ }
+ return CastInst::create(Instruction::BitCast, Result, CI.getType());
+ }
+ }
+ break;
+
+ case Intrinsic::stackrestore: {
+ // If the save is right next to the restore, remove the restore. This can
+ // happen when variable allocas are DCE'd.
+ if (IntrinsicInst *SS = dyn_cast<IntrinsicInst>(II->getOperand(1))) {
+ if (SS->getIntrinsicID() == Intrinsic::stacksave) {
+ BasicBlock::iterator BI = SS;
+ if (&*++BI == II)
+ return EraseInstFromFunction(CI);
+ }
+ }
+
+ // If the stack restore is in a return/unwind block and if there are no
+ // allocas or calls between the restore and the return, nuke the restore.
+ TerminatorInst *TI = II->getParent()->getTerminator();
+ if (isa<ReturnInst>(TI) || isa<UnwindInst>(TI)) {
+ BasicBlock::iterator BI = II;
+ bool CannotRemove = false;
+ for (++BI; &*BI != TI; ++BI) {
+ if (isa<AllocaInst>(BI) ||
+ (isa<CallInst>(BI) && !isa<IntrinsicInst>(BI))) {
+ CannotRemove = true;
+ break;
+ }
+ }
+ if (!CannotRemove)
+ return EraseInstFromFunction(CI);
+ }
+ break;
+ }
+ }
+ }
+
+ return visitCallSite(II);
+}
+
+// InvokeInst simplification
+//
+Instruction *InstCombiner::visitInvokeInst(InvokeInst &II) {
+ return visitCallSite(&II);
+}
+
+// visitCallSite - Improvements for call and invoke instructions.
+//
+Instruction *InstCombiner::visitCallSite(CallSite CS) {
+ bool Changed = false;
+
+ // If the callee is a constexpr cast of a function, attempt to move the cast
+ // to the arguments of the call/invoke.
+ if (transformConstExprCastCall(CS)) return 0;
+
+ Value *Callee = CS.getCalledValue();
+
+ if (Function *CalleeF = dyn_cast<Function>(Callee))
+ if (CalleeF->getCallingConv() != CS.getCallingConv()) {
+ Instruction *OldCall = CS.getInstruction();
+ // If the call and callee calling conventions don't match, this call must
+ // be unreachable, as the call is undefined.
+ new StoreInst(ConstantInt::getTrue(),
+ UndefValue::get(PointerType::get(Type::Int1Ty)), OldCall);
+ if (!OldCall->use_empty())
+ OldCall->replaceAllUsesWith(UndefValue::get(OldCall->getType()));
+ if (isa<CallInst>(OldCall)) // Not worth removing an invoke here.
+ return EraseInstFromFunction(*OldCall);
+ return 0;
+ }
+
+ if (isa<ConstantPointerNull>(Callee) || isa<UndefValue>(Callee)) {
+ // This instruction is not reachable, just remove it. We insert a store to
+ // undef so that we know that this code is not reachable, despite the fact
+ // that we can't modify the CFG here.
+ new StoreInst(ConstantInt::getTrue(),
+ UndefValue::get(PointerType::get(Type::Int1Ty)),
+ CS.getInstruction());
+
+ if (!CS.getInstruction()->use_empty())
+ CS.getInstruction()->
+ replaceAllUsesWith(UndefValue::get(CS.getInstruction()->getType()));
+
+ if (InvokeInst *II = dyn_cast<InvokeInst>(CS.getInstruction())) {
+ // Don't break the CFG, insert a dummy cond branch.
+ new BranchInst(II->getNormalDest(), II->getUnwindDest(),
+ ConstantInt::getTrue(), II);
+ }
+ return EraseInstFromFunction(*CS.getInstruction());
+ }
+
+ const PointerType *PTy = cast<PointerType>(Callee->getType());
+ const FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
+ if (FTy->isVarArg()) {
+ // See if we can optimize any arguments passed through the varargs area of
+ // the call.
+ for (CallSite::arg_iterator I = CS.arg_begin()+FTy->getNumParams(),
+ E = CS.arg_end(); I != E; ++I)
+ if (CastInst *CI = dyn_cast<CastInst>(*I)) {
+ // If this cast does not effect the value passed through the varargs
+ // area, we can eliminate the use of the cast.
+ Value *Op = CI->getOperand(0);
+ if (CI->isLosslessCast()) {
+ *I = Op;
+ Changed = true;
+ }
+ }
+ }
+
+ return Changed ? CS.getInstruction() : 0;
+}
+
+// transformConstExprCastCall - If the callee is a constexpr cast of a function,
+// attempt to move the cast to the arguments of the call/invoke.
+//
+bool InstCombiner::transformConstExprCastCall(CallSite CS) {
+ if (!isa<ConstantExpr>(CS.getCalledValue())) return false;
+ ConstantExpr *CE = cast<ConstantExpr>(CS.getCalledValue());
+ if (CE->getOpcode() != Instruction::BitCast ||
+ !isa<Function>(CE->getOperand(0)))
+ return false;
+ Function *Callee = cast<Function>(CE->getOperand(0));
+ Instruction *Caller = CS.getInstruction();
+
+ // Okay, this is a cast from a function to a different type. Unless doing so
+ // would cause a type conversion of one of our arguments, change this call to
+ // be a direct call with arguments casted to the appropriate types.
+ //
+ const FunctionType *FT = Callee->getFunctionType();
+ const Type *OldRetTy = Caller->getType();
+
+ const FunctionType *ActualFT =
+ cast<FunctionType>(cast<PointerType>(CE->getType())->getElementType());
+
+ // If the parameter attributes don't match up, don't do the xform. We don't
+ // want to lose an sret attribute or something.
+ if (FT->getParamAttrs() != ActualFT->getParamAttrs())
+ return false;
+
+ // Check to see if we are changing the return type...
+ if (OldRetTy != FT->getReturnType()) {
+ if (Callee->isDeclaration() && !Caller->use_empty() &&
+ // Conversion is ok if changing from pointer to int of same size.
+ !(isa<PointerType>(FT->getReturnType()) &&
+ TD->getIntPtrType() == OldRetTy))
+ return false; // Cannot transform this return value.
+
+ // If the callsite is an invoke instruction, and the return value is used by
+ // a PHI node in a successor, we cannot change the return type of the call
+ // because there is no place to put the cast instruction (without breaking
+ // the critical edge). Bail out in this case.
+ if (!Caller->use_empty())
+ if (InvokeInst *II = dyn_cast<InvokeInst>(Caller))
+ for (Value::use_iterator UI = II->use_begin(), E = II->use_end();
+ UI != E; ++UI)
+ if (PHINode *PN = dyn_cast<PHINode>(*UI))
+ if (PN->getParent() == II->getNormalDest() ||
+ PN->getParent() == II->getUnwindDest())
+ return false;
+ }
+
+ unsigned NumActualArgs = unsigned(CS.arg_end()-CS.arg_begin());
+ unsigned NumCommonArgs = std::min(FT->getNumParams(), NumActualArgs);
+
+ CallSite::arg_iterator AI = CS.arg_begin();
+ for (unsigned i = 0, e = NumCommonArgs; i != e; ++i, ++AI) {
+ const Type *ParamTy = FT->getParamType(i);
+ const Type *ActTy = (*AI)->getType();
+ ConstantInt *c = dyn_cast<ConstantInt>(*AI);
+ //Some conversions are safe even if we do not have a body.
+ //Either we can cast directly, or we can upconvert the argument
+ bool isConvertible = ActTy == ParamTy ||
+ (isa<PointerType>(ParamTy) && isa<PointerType>(ActTy)) ||
+ (ParamTy->isInteger() && ActTy->isInteger() &&
+ ParamTy->getPrimitiveSizeInBits() >= ActTy->getPrimitiveSizeInBits()) ||
+ (c && ParamTy->getPrimitiveSizeInBits() >= ActTy->getPrimitiveSizeInBits()
+ && c->getValue().isStrictlyPositive());
+ if (Callee->isDeclaration() && !isConvertible) return false;
+
+ // Most other conversions can be done if we have a body, even if these
+ // lose information, e.g. int->short.
+ // Some conversions cannot be done at all, e.g. float to pointer.
+ // Logic here parallels CastInst::getCastOpcode (the design there
+ // requires legality checks like this be done before calling it).
+ if (ParamTy->isInteger()) {
+ if (const VectorType *VActTy = dyn_cast<VectorType>(ActTy)) {
+ if (VActTy->getBitWidth() != ParamTy->getPrimitiveSizeInBits())
+ return false;
+ }
+ if (!ActTy->isInteger() && !ActTy->isFloatingPoint() &&
+ !isa<PointerType>(ActTy))
+ return false;
+ } else if (ParamTy->isFloatingPoint()) {
+ if (const VectorType *VActTy = dyn_cast<VectorType>(ActTy)) {
+ if (VActTy->getBitWidth() != ParamTy->getPrimitiveSizeInBits())
+ return false;
+ }
+ if (!ActTy->isInteger() && !ActTy->isFloatingPoint())
+ return false;
+ } else if (const VectorType *VParamTy = dyn_cast<VectorType>(ParamTy)) {
+ if (const VectorType *VActTy = dyn_cast<VectorType>(ActTy)) {
+ if (VActTy->getBitWidth() != VParamTy->getBitWidth())
+ return false;
+ }
+ if (VParamTy->getBitWidth() != ActTy->getPrimitiveSizeInBits())
+ return false;
+ } else if (isa<PointerType>(ParamTy)) {
+ if (!ActTy->isInteger() && !isa<PointerType>(ActTy))
+ return false;
+ } else {
+ return false;
+ }
+ }
+
+ if (FT->getNumParams() < NumActualArgs && !FT->isVarArg() &&
+ Callee->isDeclaration())
+ return false; // Do not delete arguments unless we have a function body...
+
+ // Okay, we decided that this is a safe thing to do: go ahead and start
+ // inserting cast instructions as necessary...
+ std::vector<Value*> Args;
+ Args.reserve(NumActualArgs);
+
+ AI = CS.arg_begin();
+ for (unsigned i = 0; i != NumCommonArgs; ++i, ++AI) {
+ const Type *ParamTy = FT->getParamType(i);
+ if ((*AI)->getType() == ParamTy) {
+ Args.push_back(*AI);
+ } else {
+ Instruction::CastOps opcode = CastInst::getCastOpcode(*AI,
+ false, ParamTy, false);
+ CastInst *NewCast = CastInst::create(opcode, *AI, ParamTy, "tmp");
+ Args.push_back(InsertNewInstBefore(NewCast, *Caller));
+ }
+ }
+
+ // If the function takes more arguments than the call was taking, add them
+ // now...
+ for (unsigned i = NumCommonArgs; i != FT->getNumParams(); ++i)
+ Args.push_back(Constant::getNullValue(FT->getParamType(i)));
+
+ // If we are removing arguments to the function, emit an obnoxious warning...
+ if (FT->getNumParams() < NumActualArgs)
+ if (!FT->isVarArg()) {
+ cerr << "WARNING: While resolving call to function '"
+ << Callee->getName() << "' arguments were dropped!\n";
+ } else {
+ // Add all of the arguments in their promoted form to the arg list...
+ for (unsigned i = FT->getNumParams(); i != NumActualArgs; ++i, ++AI) {
+ const Type *PTy = getPromotedType((*AI)->getType());
+ if (PTy != (*AI)->getType()) {
+ // Must promote to pass through va_arg area!
+ Instruction::CastOps opcode = CastInst::getCastOpcode(*AI, false,
+ PTy, false);
+ Instruction *Cast = CastInst::create(opcode, *AI, PTy, "tmp");
+ InsertNewInstBefore(Cast, *Caller);
+ Args.push_back(Cast);
+ } else {
+ Args.push_back(*AI);
+ }
+ }
+ }
+
+ if (FT->getReturnType() == Type::VoidTy)
+ Caller->setName(""); // Void type should not have a name.
+
+ Instruction *NC;
+ if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
+ NC = new InvokeInst(Callee, II->getNormalDest(), II->getUnwindDest(),
+ &Args[0], Args.size(), Caller->getName(), Caller);
+ cast<InvokeInst>(II)->setCallingConv(II->getCallingConv());
+ } else {
+ NC = new CallInst(Callee, &Args[0], Args.size(), Caller->getName(), Caller);
+ if (cast<CallInst>(Caller)->isTailCall())
+ cast<CallInst>(NC)->setTailCall();
+ cast<CallInst>(NC)->setCallingConv(cast<CallInst>(Caller)->getCallingConv());
+ }
+
+ // Insert a cast of the return type as necessary.
+ Value *NV = NC;
+ if (Caller->getType() != NV->getType() && !Caller->use_empty()) {
+ if (NV->getType() != Type::VoidTy) {
+ const Type *CallerTy = Caller->getType();
+ Instruction::CastOps opcode = CastInst::getCastOpcode(NC, false,
+ CallerTy, false);
+ NV = NC = CastInst::create(opcode, NC, CallerTy, "tmp");
+
+ // If this is an invoke instruction, we should insert it after the first
+ // non-phi, instruction in the normal successor block.
+ if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
+ BasicBlock::iterator I = II->getNormalDest()->begin();
+ while (isa<PHINode>(I)) ++I;
+ InsertNewInstBefore(NC, *I);
+ } else {
+ // Otherwise, it's a call, just insert cast right after the call instr
+ InsertNewInstBefore(NC, *Caller);
+ }
+ AddUsersToWorkList(*Caller);
+ } else {
+ NV = UndefValue::get(Caller->getType());
+ }
+ }
+
+ if (Caller->getType() != Type::VoidTy && !Caller->use_empty())
+ Caller->replaceAllUsesWith(NV);
+ Caller->eraseFromParent();
+ RemoveFromWorkList(Caller);
+ return true;
+}
+
+/// FoldPHIArgBinOpIntoPHI - If we have something like phi [add (a,b), add(c,d)]
+/// and if a/b/c/d and the add's all have a single use, turn this into two phi's
+/// and a single binop.
+Instruction *InstCombiner::FoldPHIArgBinOpIntoPHI(PHINode &PN) {
+ Instruction *FirstInst = cast<Instruction>(PN.getIncomingValue(0));
+ assert(isa<BinaryOperator>(FirstInst) || isa<GetElementPtrInst>(FirstInst) ||
+ isa<CmpInst>(FirstInst));
+ unsigned Opc = FirstInst->getOpcode();
+ Value *LHSVal = FirstInst->getOperand(0);
+ Value *RHSVal = FirstInst->getOperand(1);
+
+ const Type *LHSType = LHSVal->getType();
+ const Type *RHSType = RHSVal->getType();
+
+ // Scan to see if all operands are the same opcode, all have one use, and all
+ // kill their operands (i.e. the operands have one use).
+ for (unsigned i = 0; i != PN.getNumIncomingValues(); ++i) {
+ Instruction *I = dyn_cast<Instruction>(PN.getIncomingValue(i));
+ if (!I || I->getOpcode() != Opc || !I->hasOneUse() ||
+ // Verify type of the LHS matches so we don't fold cmp's of different
+ // types or GEP's with different index types.
+ I->getOperand(0)->getType() != LHSType ||
+ I->getOperand(1)->getType() != RHSType)
+ return 0;
+
+ // If they are CmpInst instructions, check their predicates
+ if (Opc == Instruction::ICmp || Opc == Instruction::FCmp)
+ if (cast<CmpInst>(I)->getPredicate() !=
+ cast<CmpInst>(FirstInst)->getPredicate())
+ return 0;
+
+ // Keep track of which operand needs a phi node.
+ if (I->getOperand(0) != LHSVal) LHSVal = 0;
+ if (I->getOperand(1) != RHSVal) RHSVal = 0;
+ }
+
+ // Otherwise, this is safe to transform, determine if it is profitable.
+
+ // If this is a GEP, and if the index (not the pointer) needs a PHI, bail out.
+ // Indexes are often folded into load/store instructions, so we don't want to
+ // hide them behind a phi.
+ if (isa<GetElementPtrInst>(FirstInst) && RHSVal == 0)
+ return 0;
+
+ Value *InLHS = FirstInst->getOperand(0);
+ Value *InRHS = FirstInst->getOperand(1);
+ PHINode *NewLHS = 0, *NewRHS = 0;
+ if (LHSVal == 0) {
+ NewLHS = new PHINode(LHSType, FirstInst->getOperand(0)->getName()+".pn");
+ NewLHS->reserveOperandSpace(PN.getNumOperands()/2);
+ NewLHS->addIncoming(InLHS, PN.getIncomingBlock(0));
+ InsertNewInstBefore(NewLHS, PN);
+ LHSVal = NewLHS;
+ }
+
+ if (RHSVal == 0) {
+ NewRHS = new PHINode(RHSType, FirstInst->getOperand(1)->getName()+".pn");
+ NewRHS->reserveOperandSpace(PN.getNumOperands()/2);
+ NewRHS->addIncoming(InRHS, PN.getIncomingBlock(0));
+ InsertNewInstBefore(NewRHS, PN);
+ RHSVal = NewRHS;
+ }
+
+ // Add all operands to the new PHIs.
+ for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
+ if (NewLHS) {
+ Value *NewInLHS =cast<Instruction>(PN.getIncomingValue(i))->getOperand(0);
+ NewLHS->addIncoming(NewInLHS, PN.getIncomingBlock(i));
+ }
+ if (NewRHS) {
+ Value *NewInRHS =cast<Instruction>(PN.getIncomingValue(i))->getOperand(1);
+ NewRHS->addIncoming(NewInRHS, PN.getIncomingBlock(i));
+ }
+ }
+
+ if (BinaryOperator *BinOp = dyn_cast<BinaryOperator>(FirstInst))
+ return BinaryOperator::create(BinOp->getOpcode(), LHSVal, RHSVal);
+ else if (CmpInst *CIOp = dyn_cast<CmpInst>(FirstInst))
+ return CmpInst::create(CIOp->getOpcode(), CIOp->getPredicate(), LHSVal,
+ RHSVal);
+ else {
+ assert(isa<GetElementPtrInst>(FirstInst));
+ return new GetElementPtrInst(LHSVal, RHSVal);
+ }
+}
+
+/// isSafeToSinkLoad - Return true if we know that it is safe sink the load out
+/// of the block that defines it. This means that it must be obvious the value
+/// of the load is not changed from the point of the load to the end of the
+/// block it is in.
+///
+/// Finally, it is safe, but not profitable, to sink a load targetting a
+/// non-address-taken alloca. Doing so will cause us to not promote the alloca
+/// to a register.
+static bool isSafeToSinkLoad(LoadInst *L) {
+ BasicBlock::iterator BBI = L, E = L->getParent()->end();
+
+ for (++BBI; BBI != E; ++BBI)
+ if (BBI->mayWriteToMemory())
+ return false;
+
+ // Check for non-address taken alloca. If not address-taken already, it isn't
+ // profitable to do this xform.
+ if (AllocaInst *AI = dyn_cast<AllocaInst>(L->getOperand(0))) {
+ bool isAddressTaken = false;
+ for (Value::use_iterator UI = AI->use_begin(), E = AI->use_end();
+ UI != E; ++UI) {
+ if (isa<LoadInst>(UI)) continue;
+ if (StoreInst *SI = dyn_cast<StoreInst>(*UI)) {
+ // If storing TO the alloca, then the address isn't taken.
+ if (SI->getOperand(1) == AI) continue;
+ }
+ isAddressTaken = true;
+ break;
+ }
+
+ if (!isAddressTaken)
+ return false;
+ }
+
+ return true;
+}
+
+
+// FoldPHIArgOpIntoPHI - If all operands to a PHI node are the same "unary"
+// operator and they all are only used by the PHI, PHI together their
+// inputs, and do the operation once, to the result of the PHI.
+Instruction *InstCombiner::FoldPHIArgOpIntoPHI(PHINode &PN) {
+ Instruction *FirstInst = cast<Instruction>(PN.getIncomingValue(0));
+
+ // Scan the instruction, looking for input operations that can be folded away.
+ // If all input operands to the phi are the same instruction (e.g. a cast from
+ // the same type or "+42") we can pull the operation through the PHI, reducing
+ // code size and simplifying code.
+ Constant *ConstantOp = 0;
+ const Type *CastSrcTy = 0;
+ bool isVolatile = false;
+ if (isa<CastInst>(FirstInst)) {
+ CastSrcTy = FirstInst->getOperand(0)->getType();
+ } else if (isa<BinaryOperator>(FirstInst) || isa<CmpInst>(FirstInst)) {
+ // Can fold binop, compare or shift here if the RHS is a constant,
+ // otherwise call FoldPHIArgBinOpIntoPHI.
+ ConstantOp = dyn_cast<Constant>(FirstInst->getOperand(1));
+ if (ConstantOp == 0)
+ return FoldPHIArgBinOpIntoPHI(PN);
+ } else if (LoadInst *LI = dyn_cast<LoadInst>(FirstInst)) {
+ isVolatile = LI->isVolatile();
+ // We can't sink the load if the loaded value could be modified between the
+ // load and the PHI.
+ if (LI->getParent() != PN.getIncomingBlock(0) ||
+ !isSafeToSinkLoad(LI))
+ return 0;
+ } else if (isa<GetElementPtrInst>(FirstInst)) {
+ if (FirstInst->getNumOperands() == 2)
+ return FoldPHIArgBinOpIntoPHI(PN);
+ // Can't handle general GEPs yet.
+ return 0;
+ } else {
+ return 0; // Cannot fold this operation.
+ }
+
+ // Check to see if all arguments are the same operation.
+ for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
+ if (!isa<Instruction>(PN.getIncomingValue(i))) return 0;
+ Instruction *I = cast<Instruction>(PN.getIncomingValue(i));
+ if (!I->hasOneUse() || !I->isSameOperationAs(FirstInst))
+ return 0;
+ if (CastSrcTy) {
+ if (I->getOperand(0)->getType() != CastSrcTy)
+ return 0; // Cast operation must match.
+ } else if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
+ // We can't sink the load if the loaded value could be modified between
+ // the load and the PHI.
+ if (LI->isVolatile() != isVolatile ||
+ LI->getParent() != PN.getIncomingBlock(i) ||
+ !isSafeToSinkLoad(LI))
+ return 0;
+ } else if (I->getOperand(1) != ConstantOp) {
+ return 0;
+ }
+ }
+
+ // Okay, they are all the same operation. Create a new PHI node of the
+ // correct type, and PHI together all of the LHS's of the instructions.
+ PHINode *NewPN = new PHINode(FirstInst->getOperand(0)->getType(),
+ PN.getName()+".in");
+ NewPN->reserveOperandSpace(PN.getNumOperands()/2);
+
+ Value *InVal = FirstInst->getOperand(0);
+ NewPN->addIncoming(InVal, PN.getIncomingBlock(0));
+
+ // Add all operands to the new PHI.
+ for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
+ Value *NewInVal = cast<Instruction>(PN.getIncomingValue(i))->getOperand(0);
+ if (NewInVal != InVal)
+ InVal = 0;
+ NewPN->addIncoming(NewInVal, PN.getIncomingBlock(i));
+ }
+
+ Value *PhiVal;
+ if (InVal) {
+ // The new PHI unions all of the same values together. This is really
+ // common, so we handle it intelligently here for compile-time speed.
+ PhiVal = InVal;
+ delete NewPN;
+ } else {
+ InsertNewInstBefore(NewPN, PN);
+ PhiVal = NewPN;
+ }
+
+ // Insert and return the new operation.
+ if (CastInst* FirstCI = dyn_cast<CastInst>(FirstInst))
+ return CastInst::create(FirstCI->getOpcode(), PhiVal, PN.getType());
+ else if (isa<LoadInst>(FirstInst))
+ return new LoadInst(PhiVal, "", isVolatile);
+ else if (BinaryOperator *BinOp = dyn_cast<BinaryOperator>(FirstInst))
+ return BinaryOperator::create(BinOp->getOpcode(), PhiVal, ConstantOp);
+ else if (CmpInst *CIOp = dyn_cast<CmpInst>(FirstInst))
+ return CmpInst::create(CIOp->getOpcode(), CIOp->getPredicate(),
+ PhiVal, ConstantOp);
+ else
+ assert(0 && "Unknown operation");
+ return 0;
+}
+
+/// DeadPHICycle - Return true if this PHI node is only used by a PHI node cycle
+/// that is dead.
+static bool DeadPHICycle(PHINode *PN,
+ SmallPtrSet<PHINode*, 16> &PotentiallyDeadPHIs) {
+ if (PN->use_empty()) return true;
+ if (!PN->hasOneUse()) return false;
+
+ // Remember this node, and if we find the cycle, return.
+ if (!PotentiallyDeadPHIs.insert(PN))
+ return true;
+
+ if (PHINode *PU = dyn_cast<PHINode>(PN->use_back()))
+ return DeadPHICycle(PU, PotentiallyDeadPHIs);
+
+ return false;
+}
+
+// PHINode simplification
+//
+Instruction *InstCombiner::visitPHINode(PHINode &PN) {
+ // If LCSSA is around, don't mess with Phi nodes
+ if (MustPreserveLCSSA) return 0;
+
+ if (Value *V = PN.hasConstantValue())
+ return ReplaceInstUsesWith(PN, V);
+
+ // If all PHI operands are the same operation, pull them through the PHI,
+ // reducing code size.
+ if (isa<Instruction>(PN.getIncomingValue(0)) &&
+ PN.getIncomingValue(0)->hasOneUse())
+ if (Instruction *Result = FoldPHIArgOpIntoPHI(PN))
+ return Result;
+
+ // If this is a trivial cycle in the PHI node graph, remove it. Basically, if
+ // this PHI only has a single use (a PHI), and if that PHI only has one use (a
+ // PHI)... break the cycle.
+ if (PN.hasOneUse()) {
+ Instruction *PHIUser = cast<Instruction>(PN.use_back());
+ if (PHINode *PU = dyn_cast<PHINode>(PHIUser)) {
+ SmallPtrSet<PHINode*, 16> PotentiallyDeadPHIs;
+ PotentiallyDeadPHIs.insert(&PN);
+ if (DeadPHICycle(PU, PotentiallyDeadPHIs))
+ return ReplaceInstUsesWith(PN, UndefValue::get(PN.getType()));
+ }
+
+ // If this phi has a single use, and if that use just computes a value for
+ // the next iteration of a loop, delete the phi. This occurs with unused
+ // induction variables, e.g. "for (int j = 0; ; ++j);". Detecting this
+ // common case here is good because the only other things that catch this
+ // are induction variable analysis (sometimes) and ADCE, which is only run
+ // late.
+ if (PHIUser->hasOneUse() &&
+ (isa<BinaryOperator>(PHIUser) || isa<GetElementPtrInst>(PHIUser)) &&
+ PHIUser->use_back() == &PN) {
+ return ReplaceInstUsesWith(PN, UndefValue::get(PN.getType()));
+ }
+ }
+
+ return 0;
+}
+
+static Value *InsertCastToIntPtrTy(Value *V, const Type *DTy,
+ Instruction *InsertPoint,
+ InstCombiner *IC) {
+ unsigned PtrSize = DTy->getPrimitiveSizeInBits();
+ unsigned VTySize = V->getType()->getPrimitiveSizeInBits();
+ // We must cast correctly to the pointer type. Ensure that we
+ // sign extend the integer value if it is smaller as this is
+ // used for address computation.
+ Instruction::CastOps opcode =
+ (VTySize < PtrSize ? Instruction::SExt :
+ (VTySize == PtrSize ? Instruction::BitCast : Instruction::Trunc));
+ return IC->InsertCastBefore(opcode, V, DTy, *InsertPoint);
+}
+
+
+Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
+ Value *PtrOp = GEP.getOperand(0);
+ // Is it 'getelementptr %P, i32 0' or 'getelementptr %P'
+ // If so, eliminate the noop.
+ if (GEP.getNumOperands() == 1)
+ return ReplaceInstUsesWith(GEP, PtrOp);
+
+ if (isa<UndefValue>(GEP.getOperand(0)))
+ return ReplaceInstUsesWith(GEP, UndefValue::get(GEP.getType()));
+
+ bool HasZeroPointerIndex = false;
+ if (Constant *C = dyn_cast<Constant>(GEP.getOperand(1)))
+ HasZeroPointerIndex = C->isNullValue();
+
+ if (GEP.getNumOperands() == 2 && HasZeroPointerIndex)
+ return ReplaceInstUsesWith(GEP, PtrOp);
+
+ // Eliminate unneeded casts for indices.
+ bool MadeChange = false;
+
+ gep_type_iterator GTI = gep_type_begin(GEP);
+ for (unsigned i = 1, e = GEP.getNumOperands(); i != e; ++i, ++GTI) {
+ if (isa<SequentialType>(*GTI)) {
+ if (CastInst *CI = dyn_cast<CastInst>(GEP.getOperand(i))) {
+ if (CI->getOpcode() == Instruction::ZExt ||
+ CI->getOpcode() == Instruction::SExt) {
+ const Type *SrcTy = CI->getOperand(0)->getType();
+ // We can eliminate a cast from i32 to i64 iff the target
+ // is a 32-bit pointer target.
+ if (SrcTy->getPrimitiveSizeInBits() >= TD->getPointerSizeInBits()) {
+ MadeChange = true;
+ GEP.setOperand(i, CI->getOperand(0));
+ }
+ }
+ }
+ // If we are using a wider index than needed for this platform, shrink it
+ // to what we need. If the incoming value needs a cast instruction,
+ // insert it. This explicit cast can make subsequent optimizations more
+ // obvious.
+ Value *Op = GEP.getOperand(i);
+ if (TD->getTypeSize(Op->getType()) > TD->getPointerSize())
+ if (Constant *C = dyn_cast<Constant>(Op)) {
+ GEP.setOperand(i, ConstantExpr::getTrunc(C, TD->getIntPtrType()));
+ MadeChange = true;
+ } else {
+ Op = InsertCastBefore(Instruction::Trunc, Op, TD->getIntPtrType(),
+ GEP);
+ GEP.setOperand(i, Op);
+ MadeChange = true;
+ }
+ }
+ }
+ if (MadeChange) return &GEP;
+
+ // If this GEP instruction doesn't move the pointer, and if the input operand
+ // is a bitcast of another pointer, just replace the GEP with a bitcast of the
+ // real input to the dest type.
+ if (GEP.hasAllZeroIndices() && isa<BitCastInst>(GEP.getOperand(0)))
+ return new BitCastInst(cast<BitCastInst>(GEP.getOperand(0))->getOperand(0),
+ GEP.getType());
+
+ // Combine Indices - If the source pointer to this getelementptr instruction
+ // is a getelementptr instruction, combine the indices of the two
+ // getelementptr instructions into a single instruction.
+ //
+ SmallVector<Value*, 8> SrcGEPOperands;
+ if (User *Src = dyn_castGetElementPtr(PtrOp))
+ SrcGEPOperands.append(Src->op_begin(), Src->op_end());
+
+ if (!SrcGEPOperands.empty()) {
+ // Note that if our source is a gep chain itself that we wait for that
+ // chain to be resolved before we perform this transformation. This
+ // avoids us creating a TON of code in some cases.
+ //
+ if (isa<GetElementPtrInst>(SrcGEPOperands[0]) &&
+ cast<Instruction>(SrcGEPOperands[0])->getNumOperands() == 2)
+ return 0; // Wait until our source is folded to completion.
+
+ SmallVector<Value*, 8> Indices;
+
+ // Find out whether the last index in the source GEP is a sequential idx.
+ bool EndsWithSequential = false;
+ for (gep_type_iterator I = gep_type_begin(*cast<User>(PtrOp)),
+ E = gep_type_end(*cast<User>(PtrOp)); I != E; ++I)
+ EndsWithSequential = !isa<StructType>(*I);
+
+ // Can we combine the two pointer arithmetics offsets?
+ if (EndsWithSequential) {
+ // Replace: gep (gep %P, long B), long A, ...
+ // With: T = long A+B; gep %P, T, ...
+ //
+ Value *Sum, *SO1 = SrcGEPOperands.back(), *GO1 = GEP.getOperand(1);
+ if (SO1 == Constant::getNullValue(SO1->getType())) {
+ Sum = GO1;
+ } else if (GO1 == Constant::getNullValue(GO1->getType())) {
+ Sum = SO1;
+ } else {
+ // If they aren't the same type, convert both to an integer of the
+ // target's pointer size.
+ if (SO1->getType() != GO1->getType()) {
+ if (Constant *SO1C = dyn_cast<Constant>(SO1)) {
+ SO1 = ConstantExpr::getIntegerCast(SO1C, GO1->getType(), true);
+ } else if (Constant *GO1C = dyn_cast<Constant>(GO1)) {
+ GO1 = ConstantExpr::getIntegerCast(GO1C, SO1->getType(), true);
+ } else {
+ unsigned PS = TD->getPointerSize();
+ if (TD->getTypeSize(SO1->getType()) == PS) {
+ // Convert GO1 to SO1's type.
+ GO1 = InsertCastToIntPtrTy(GO1, SO1->getType(), &GEP, this);
+
+ } else if (TD->getTypeSize(GO1->getType()) == PS) {
+ // Convert SO1 to GO1's type.
+ SO1 = InsertCastToIntPtrTy(SO1, GO1->getType(), &GEP, this);
+ } else {
+ const Type *PT = TD->getIntPtrType();
+ SO1 = InsertCastToIntPtrTy(SO1, PT, &GEP, this);
+ GO1 = InsertCastToIntPtrTy(GO1, PT, &GEP, this);
+ }
+ }
+ }
+ if (isa<Constant>(SO1) && isa<Constant>(GO1))
+ Sum = ConstantExpr::getAdd(cast<Constant>(SO1), cast<Constant>(GO1));
+ else {
+ Sum = BinaryOperator::createAdd(SO1, GO1, PtrOp->getName()+".sum");
+ InsertNewInstBefore(cast<Instruction>(Sum), GEP);
+ }
+ }
+
+ // Recycle the GEP we already have if possible.
+ if (SrcGEPOperands.size() == 2) {
+ GEP.setOperand(0, SrcGEPOperands[0]);
+ GEP.setOperand(1, Sum);
+ return &GEP;
+ } else {
+ Indices.insert(Indices.end(), SrcGEPOperands.begin()+1,
+ SrcGEPOperands.end()-1);
+ Indices.push_back(Sum);
+ Indices.insert(Indices.end(), GEP.op_begin()+2, GEP.op_end());
+ }
+ } else if (isa<Constant>(*GEP.idx_begin()) &&
+ cast<Constant>(*GEP.idx_begin())->isNullValue() &&
+ SrcGEPOperands.size() != 1) {
+ // Otherwise we can do the fold if the first index of the GEP is a zero
+ Indices.insert(Indices.end(), SrcGEPOperands.begin()+1,
+ SrcGEPOperands.end());
+ Indices.insert(Indices.end(), GEP.idx_begin()+1, GEP.idx_end());
+ }
+
+ if (!Indices.empty())
+ return new GetElementPtrInst(SrcGEPOperands[0], &Indices[0],
+ Indices.size(), GEP.getName());
+
+ } else if (GlobalValue *GV = dyn_cast<GlobalValue>(PtrOp)) {
+ // GEP of global variable. If all of the indices for this GEP are
+ // constants, we can promote this to a constexpr instead of an instruction.
+
+ // Scan for nonconstants...
+ SmallVector<Constant*, 8> Indices;
+ User::op_iterator I = GEP.idx_begin(), E = GEP.idx_end();
+ for (; I != E && isa<Constant>(*I); ++I)
+ Indices.push_back(cast<Constant>(*I));
+
+ if (I == E) { // If they are all constants...
+ Constant *CE = ConstantExpr::getGetElementPtr(GV,
+ &Indices[0],Indices.size());
+
+ // Replace all uses of the GEP with the new constexpr...
+ return ReplaceInstUsesWith(GEP, CE);
+ }
+ } else if (Value *X = getBitCastOperand(PtrOp)) { // Is the operand a cast?
+ if (!isa<PointerType>(X->getType())) {
+ // Not interesting. Source pointer must be a cast from pointer.
+ } else if (HasZeroPointerIndex) {
+ // transform: GEP (cast [10 x ubyte]* X to [0 x ubyte]*), long 0, ...
+ // into : GEP [10 x ubyte]* X, long 0, ...
+ //
+ // This occurs when the program declares an array extern like "int X[];"
+ //
+ const PointerType *CPTy = cast<PointerType>(PtrOp->getType());
+ const PointerType *XTy = cast<PointerType>(X->getType());
+ if (const ArrayType *XATy =
+ dyn_cast<ArrayType>(XTy->getElementType()))
+ if (const ArrayType *CATy =
+ dyn_cast<ArrayType>(CPTy->getElementType()))
+ if (CATy->getElementType() == XATy->getElementType()) {
+ // At this point, we know that the cast source type is a pointer
+ // to an array of the same type as the destination pointer
+ // array. Because the array type is never stepped over (there
+ // is a leading zero) we can fold the cast into this GEP.
+ GEP.setOperand(0, X);
+ return &GEP;
+ }
+ } else if (GEP.getNumOperands() == 2) {
+ // Transform things like:
+ // %t = getelementptr ubyte* cast ([2 x int]* %str to uint*), uint %V
+ // into: %t1 = getelementptr [2 x int*]* %str, int 0, uint %V; cast
+ const Type *SrcElTy = cast<PointerType>(X->getType())->getElementType();
+ const Type *ResElTy=cast<PointerType>(PtrOp->getType())->getElementType();
+ if (isa<ArrayType>(SrcElTy) &&
+ TD->getTypeSize(cast<ArrayType>(SrcElTy)->getElementType()) ==
+ TD->getTypeSize(ResElTy)) {
+ Value *V = InsertNewInstBefore(
+ new GetElementPtrInst(X, Constant::getNullValue(Type::Int32Ty),
+ GEP.getOperand(1), GEP.getName()), GEP);
+ // V and GEP are both pointer types --> BitCast
+ return new BitCastInst(V, GEP.getType());
+ }
+
+ // Transform things like:
+ // getelementptr sbyte* cast ([100 x double]* X to sbyte*), int %tmp
+ // (where tmp = 8*tmp2) into:
+ // getelementptr [100 x double]* %arr, int 0, int %tmp.2
+
+ if (isa<ArrayType>(SrcElTy) &&
+ (ResElTy == Type::Int8Ty || ResElTy == Type::Int8Ty)) {
+ uint64_t ArrayEltSize =
+ TD->getTypeSize(cast<ArrayType>(SrcElTy)->getElementType());
+
+ // Check to see if "tmp" is a scale by a multiple of ArrayEltSize. We
+ // allow either a mul, shift, or constant here.
+ Value *NewIdx = 0;
+ ConstantInt *Scale = 0;
+ if (ArrayEltSize == 1) {
+ NewIdx = GEP.getOperand(1);
+ Scale = ConstantInt::get(NewIdx->getType(), 1);
+ } else if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP.getOperand(1))) {
+ NewIdx = ConstantInt::get(CI->getType(), 1);
+ Scale = CI;
+ } else if (Instruction *Inst =dyn_cast<Instruction>(GEP.getOperand(1))){
+ if (Inst->getOpcode() == Instruction::Shl &&
+ isa<ConstantInt>(Inst->getOperand(1))) {
+ ConstantInt *ShAmt = cast<ConstantInt>(Inst->getOperand(1));
+ uint32_t ShAmtVal = ShAmt->getLimitedValue(64);
+ Scale = ConstantInt::get(Inst->getType(), 1ULL << ShAmtVal);
+ NewIdx = Inst->getOperand(0);
+ } else if (Inst->getOpcode() == Instruction::Mul &&
+ isa<ConstantInt>(Inst->getOperand(1))) {
+ Scale = cast<ConstantInt>(Inst->getOperand(1));
+ NewIdx = Inst->getOperand(0);
+ }
+ }
+
+ // If the index will be to exactly the right offset with the scale taken
+ // out, perform the transformation.
+ if (Scale && Scale->getZExtValue() % ArrayEltSize == 0) {
+ if (isa<ConstantInt>(Scale))
+ Scale = ConstantInt::get(Scale->getType(),
+ Scale->getZExtValue() / ArrayEltSize);
+ if (Scale->getZExtValue() != 1) {
+ Constant *C = ConstantExpr::getIntegerCast(Scale, NewIdx->getType(),
+ true /*SExt*/);
+ Instruction *Sc = BinaryOperator::createMul(NewIdx, C, "idxscale");
+ NewIdx = InsertNewInstBefore(Sc, GEP);
+ }
+
+ // Insert the new GEP instruction.
+ Instruction *NewGEP =
+ new GetElementPtrInst(X, Constant::getNullValue(Type::Int32Ty),
+ NewIdx, GEP.getName());
+ NewGEP = InsertNewInstBefore(NewGEP, GEP);
+ // The NewGEP must be pointer typed, so must the old one -> BitCast
+ return new BitCastInst(NewGEP, GEP.getType());
+ }
+ }
+ }
+ }
+
+ return 0;
+}
+
+Instruction *InstCombiner::visitAllocationInst(AllocationInst &AI) {
+ // Convert: malloc Ty, C - where C is a constant != 1 into: malloc [C x Ty], 1
+ if (AI.isArrayAllocation()) // Check C != 1
+ if (const ConstantInt *C = dyn_cast<ConstantInt>(AI.getArraySize())) {
+ const Type *NewTy =
+ ArrayType::get(AI.getAllocatedType(), C->getZExtValue());
+ AllocationInst *New = 0;
+
+ // Create and insert the replacement instruction...
+ if (isa<MallocInst>(AI))
+ New = new MallocInst(NewTy, 0, AI.getAlignment(), AI.getName());
+ else {
+ assert(isa<AllocaInst>(AI) && "Unknown type of allocation inst!");
+ New = new AllocaInst(NewTy, 0, AI.getAlignment(), AI.getName());
+ }
+
+ InsertNewInstBefore(New, AI);
+
+ // Scan to the end of the allocation instructions, to skip over a block of
+ // allocas if possible...
+ //
+ BasicBlock::iterator It = New;
+ while (isa<AllocationInst>(*It)) ++It;
+
+ // Now that I is pointing to the first non-allocation-inst in the block,
+ // insert our getelementptr instruction...
+ //
+ Value *NullIdx = Constant::getNullValue(Type::Int32Ty);
+ Value *V = new GetElementPtrInst(New, NullIdx, NullIdx,
+ New->getName()+".sub", It);
+
+ // Now make everything use the getelementptr instead of the original
+ // allocation.
+ return ReplaceInstUsesWith(AI, V);
+ } else if (isa<UndefValue>(AI.getArraySize())) {
+ return ReplaceInstUsesWith(AI, Constant::getNullValue(AI.getType()));
+ }
+
+ // If alloca'ing a zero byte object, replace the alloca with a null pointer.
+ // Note that we only do this for alloca's, because malloc should allocate and
+ // return a unique pointer, even for a zero byte allocation.
+ if (isa<AllocaInst>(AI) && AI.getAllocatedType()->isSized() &&
+ TD->getTypeSize(AI.getAllocatedType()) == 0)
+ return ReplaceInstUsesWith(AI, Constant::getNullValue(AI.getType()));
+
+ return 0;
+}
+
+Instruction *InstCombiner::visitFreeInst(FreeInst &FI) {
+ Value *Op = FI.getOperand(0);
+
+ // free undef -> unreachable.
+ if (isa<UndefValue>(Op)) {
+ // Insert a new store to null because we cannot modify the CFG here.
+ new StoreInst(ConstantInt::getTrue(),
+ UndefValue::get(PointerType::get(Type::Int1Ty)), &FI);
+ return EraseInstFromFunction(FI);
+ }
+
+ // If we have 'free null' delete the instruction. This can happen in stl code
+ // when lots of inlining happens.
+ if (isa<ConstantPointerNull>(Op))
+ return EraseInstFromFunction(FI);
+
+ // Change free <ty>* (cast <ty2>* X to <ty>*) into free <ty2>* X
+ if (BitCastInst *CI = dyn_cast<BitCastInst>(Op)) {
+ FI.setOperand(0, CI->getOperand(0));
+ return &FI;
+ }
+
+ // Change free (gep X, 0,0,0,0) into free(X)
+ if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(Op)) {
+ if (GEPI->hasAllZeroIndices()) {
+ AddToWorkList(GEPI);
+ FI.setOperand(0, GEPI->getOperand(0));
+ return &FI;
+ }
+ }
+
+ // Change free(malloc) into nothing, if the malloc has a single use.
+ if (MallocInst *MI = dyn_cast<MallocInst>(Op))
+ if (MI->hasOneUse()) {
+ EraseInstFromFunction(FI);
+ return EraseInstFromFunction(*MI);
+ }
+
+ return 0;
+}
+
+
+/// InstCombineLoadCast - Fold 'load (cast P)' -> cast (load P)' when possible.
+static Instruction *InstCombineLoadCast(InstCombiner &IC, LoadInst &LI) {
+ User *CI = cast<User>(LI.getOperand(0));
+ Value *CastOp = CI->getOperand(0);
+
+ const Type *DestPTy = cast<PointerType>(CI->getType())->getElementType();
+ if (const PointerType *SrcTy = dyn_cast<PointerType>(CastOp->getType())) {
+ const Type *SrcPTy = SrcTy->getElementType();
+
+ if (DestPTy->isInteger() || isa<PointerType>(DestPTy) ||
+ isa<VectorType>(DestPTy)) {
+ // If the source is an array, the code below will not succeed. Check to
+ // see if a trivial 'gep P, 0, 0' will help matters. Only do this for
+ // constants.
+ if (const ArrayType *ASrcTy = dyn_cast<ArrayType>(SrcPTy))
+ if (Constant *CSrc = dyn_cast<Constant>(CastOp))
+ if (ASrcTy->getNumElements() != 0) {
+ Value *Idxs[2];
+ Idxs[0] = Idxs[1] = Constant::getNullValue(Type::Int32Ty);
+ CastOp = ConstantExpr::getGetElementPtr(CSrc, Idxs, 2);
+ SrcTy = cast<PointerType>(CastOp->getType());
+ SrcPTy = SrcTy->getElementType();
+ }
+
+ if ((SrcPTy->isInteger() || isa<PointerType>(SrcPTy) ||
+ isa<VectorType>(SrcPTy)) &&
+ // Do not allow turning this into a load of an integer, which is then
+ // casted to a pointer, this pessimizes pointer analysis a lot.
+ (isa<PointerType>(SrcPTy) == isa<PointerType>(LI.getType())) &&
+ IC.getTargetData().getTypeSizeInBits(SrcPTy) ==
+ IC.getTargetData().getTypeSizeInBits(DestPTy)) {
+
+ // Okay, we are casting from one integer or pointer type to another of
+ // the same size. Instead of casting the pointer before the load, cast
+ // the result of the loaded value.
+ Value *NewLoad = IC.InsertNewInstBefore(new LoadInst(CastOp,
+ CI->getName(),
+ LI.isVolatile()),LI);
+ // Now cast the result of the load.
+ return new BitCastInst(NewLoad, LI.getType());
+ }
+ }
+ }
+ return 0;
+}
+
+/// isSafeToLoadUnconditionally - Return true if we know that executing a load
+/// from this value cannot trap. If it is not obviously safe to load from the
+/// specified pointer, we do a quick local scan of the basic block containing
+/// ScanFrom, to determine if the address is already accessed.
+static bool isSafeToLoadUnconditionally(Value *V, Instruction *ScanFrom) {
+ // If it is an alloca or global variable, it is always safe to load from.
+ if (isa<AllocaInst>(V) || isa<GlobalVariable>(V)) return true;
+
+ // Otherwise, be a little bit agressive by scanning the local block where we
+ // want to check to see if the pointer is already being loaded or stored
+ // from/to. If so, the previous load or store would have already trapped,
+ // so there is no harm doing an extra load (also, CSE will later eliminate
+ // the load entirely).
+ BasicBlock::iterator BBI = ScanFrom, E = ScanFrom->getParent()->begin();
+
+ while (BBI != E) {
+ --BBI;
+
+ if (LoadInst *LI = dyn_cast<LoadInst>(BBI)) {
+ if (LI->getOperand(0) == V) return true;
+ } else if (StoreInst *SI = dyn_cast<StoreInst>(BBI))
+ if (SI->getOperand(1) == V) return true;
+
+ }
+ return false;
+}
+
+Instruction *InstCombiner::visitLoadInst(LoadInst &LI) {
+ Value *Op = LI.getOperand(0);
+
+ // load (cast X) --> cast (load X) iff safe
+ if (isa<CastInst>(Op))
+ if (Instruction *Res = InstCombineLoadCast(*this, LI))
+ return Res;
+
+ // None of the following transforms are legal for volatile loads.
+ if (LI.isVolatile()) return 0;
+
+ if (&LI.getParent()->front() != &LI) {
+ BasicBlock::iterator BBI = &LI; --BBI;
+ // If the instruction immediately before this is a store to the same
+ // address, do a simple form of store->load forwarding.
+ if (StoreInst *SI = dyn_cast<StoreInst>(BBI))
+ if (SI->getOperand(1) == LI.getOperand(0))
+ return ReplaceInstUsesWith(LI, SI->getOperand(0));
+ if (LoadInst *LIB = dyn_cast<LoadInst>(BBI))
+ if (LIB->getOperand(0) == LI.getOperand(0))
+ return ReplaceInstUsesWith(LI, LIB);
+ }
+
+ if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(Op))
+ if (isa<ConstantPointerNull>(GEPI->getOperand(0))) {
+ // Insert a new store to null instruction before the load to indicate
+ // that this code is not reachable. We do this instead of inserting
+ // an unreachable instruction directly because we cannot modify the
+ // CFG.
+ new StoreInst(UndefValue::get(LI.getType()),
+ Constant::getNullValue(Op->getType()), &LI);
+ return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType()));
+ }
+
+ if (Constant *C = dyn_cast<Constant>(Op)) {
+ // load null/undef -> undef
+ if ((C->isNullValue() || isa<UndefValue>(C))) {
+ // Insert a new store to null instruction before the load to indicate that
+ // this code is not reachable. We do this instead of inserting an
+ // unreachable instruction directly because we cannot modify the CFG.
+ new StoreInst(UndefValue::get(LI.getType()),
+ Constant::getNullValue(Op->getType()), &LI);
+ return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType()));
+ }
+
+ // Instcombine load (constant global) into the value loaded.
+ if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Op))
+ if (GV->isConstant() && !GV->isDeclaration())
+ return ReplaceInstUsesWith(LI, GV->getInitializer());
+
+ // Instcombine load (constantexpr_GEP global, 0, ...) into the value loaded.
+ if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Op))
+ if (CE->getOpcode() == Instruction::GetElementPtr) {
+ if (GlobalVariable *GV = dyn_cast<GlobalVariable>(CE->getOperand(0)))
+ if (GV->isConstant() && !GV->isDeclaration())
+ if (Constant *V =
+ ConstantFoldLoadThroughGEPConstantExpr(GV->getInitializer(), CE))
+ return ReplaceInstUsesWith(LI, V);
+ if (CE->getOperand(0)->isNullValue()) {
+ // Insert a new store to null instruction before the load to indicate
+ // that this code is not reachable. We do this instead of inserting
+ // an unreachable instruction directly because we cannot modify the
+ // CFG.
+ new StoreInst(UndefValue::get(LI.getType()),
+ Constant::getNullValue(Op->getType()), &LI);
+ return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType()));
+ }
+
+ } else if (CE->isCast()) {
+ if (Instruction *Res = InstCombineLoadCast(*this, LI))
+ return Res;
+ }
+ }
+
+ if (Op->hasOneUse()) {
+ // Change select and PHI nodes to select values instead of addresses: this
+ // helps alias analysis out a lot, allows many others simplifications, and
+ // exposes redundancy in the code.
+ //
+ // Note that we cannot do the transformation unless we know that the
+ // introduced loads cannot trap! Something like this is valid as long as
+ // the condition is always false: load (select bool %C, int* null, int* %G),
+ // but it would not be valid if we transformed it to load from null
+ // unconditionally.
+ //
+ if (SelectInst *SI = dyn_cast<SelectInst>(Op)) {
+ // load (select (Cond, &V1, &V2)) --> select(Cond, load &V1, load &V2).
+ if (isSafeToLoadUnconditionally(SI->getOperand(1), SI) &&
+ isSafeToLoadUnconditionally(SI->getOperand(2), SI)) {
+ Value *V1 = InsertNewInstBefore(new LoadInst(SI->getOperand(1),
+ SI->getOperand(1)->getName()+".val"), LI);
+ Value *V2 = InsertNewInstBefore(new LoadInst(SI->getOperand(2),
+ SI->getOperand(2)->getName()+".val"), LI);
+ return new SelectInst(SI->getCondition(), V1, V2);
+ }
+
+ // load (select (cond, null, P)) -> load P
+ if (Constant *C = dyn_cast<Constant>(SI->getOperand(1)))
+ if (C->isNullValue()) {
+ LI.setOperand(0, SI->getOperand(2));
+ return &LI;
+ }
+
+ // load (select (cond, P, null)) -> load P
+ if (Constant *C = dyn_cast<Constant>(SI->getOperand(2)))
+ if (C->isNullValue()) {
+ LI.setOperand(0, SI->getOperand(1));
+ return &LI;
+ }
+ }
+ }
+ return 0;
+}
+
+/// InstCombineStoreToCast - Fold store V, (cast P) -> store (cast V), P
+/// when possible.
+static Instruction *InstCombineStoreToCast(InstCombiner &IC, StoreInst &SI) {
+ User *CI = cast<User>(SI.getOperand(1));
+ Value *CastOp = CI->getOperand(0);
+
+ const Type *DestPTy = cast<PointerType>(CI->getType())->getElementType();
+ if (const PointerType *SrcTy = dyn_cast<PointerType>(CastOp->getType())) {
+ const Type *SrcPTy = SrcTy->getElementType();
+
+ if (DestPTy->isInteger() || isa<PointerType>(DestPTy)) {
+ // If the source is an array, the code below will not succeed. Check to
+ // see if a trivial 'gep P, 0, 0' will help matters. Only do this for
+ // constants.
+ if (const ArrayType *ASrcTy = dyn_cast<ArrayType>(SrcPTy))
+ if (Constant *CSrc = dyn_cast<Constant>(CastOp))
+ if (ASrcTy->getNumElements() != 0) {
+ Value* Idxs[2];
+ Idxs[0] = Idxs[1] = Constant::getNullValue(Type::Int32Ty);
+ CastOp = ConstantExpr::getGetElementPtr(CSrc, Idxs, 2);
+ SrcTy = cast<PointerType>(CastOp->getType());
+ SrcPTy = SrcTy->getElementType();
+ }
+
+ if ((SrcPTy->isInteger() || isa<PointerType>(SrcPTy)) &&
+ IC.getTargetData().getTypeSizeInBits(SrcPTy) ==
+ IC.getTargetData().getTypeSizeInBits(DestPTy)) {
+
+ // Okay, we are casting from one integer or pointer type to another of
+ // the same size. Instead of casting the pointer before
+ // the store, cast the value to be stored.
+ Value *NewCast;
+ Value *SIOp0 = SI.getOperand(0);
+ Instruction::CastOps opcode = Instruction::BitCast;
+ const Type* CastSrcTy = SIOp0->getType();
+ const Type* CastDstTy = SrcPTy;
+ if (isa<PointerType>(CastDstTy)) {
+ if (CastSrcTy->isInteger())
+ opcode = Instruction::IntToPtr;
+ } else if (isa<IntegerType>(CastDstTy)) {
+ if (isa<PointerType>(SIOp0->getType()))
+ opcode = Instruction::PtrToInt;
+ }
+ if (Constant *C = dyn_cast<Constant>(SIOp0))
+ NewCast = ConstantExpr::getCast(opcode, C, CastDstTy);
+ else
+ NewCast = IC.InsertNewInstBefore(
+ CastInst::create(opcode, SIOp0, CastDstTy, SIOp0->getName()+".c"),
+ SI);
+ return new StoreInst(NewCast, CastOp);
+ }
+ }
+ }
+ return 0;
+}
+
+Instruction *InstCombiner::visitStoreInst(StoreInst &SI) {
+ Value *Val = SI.getOperand(0);
+ Value *Ptr = SI.getOperand(1);
+
+ if (isa<UndefValue>(Ptr)) { // store X, undef -> noop (even if volatile)
+ EraseInstFromFunction(SI);
+ ++NumCombined;
+ return 0;
+ }
+
+ // If the RHS is an alloca with a single use, zapify the store, making the
+ // alloca dead.
+ if (Ptr->hasOneUse()) {
+ if (isa<AllocaInst>(Ptr)) {
+ EraseInstFromFunction(SI);
+ ++NumCombined;
+ return 0;
+ }
+
+ if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Ptr))
+ if (isa<AllocaInst>(GEP->getOperand(0)) &&
+ GEP->getOperand(0)->hasOneUse()) {
+ EraseInstFromFunction(SI);
+ ++NumCombined;
+ return 0;
+ }
+ }
+
+ // Do really simple DSE, to catch cases where there are several consequtive
+ // stores to the same location, separated by a few arithmetic operations. This
+ // situation often occurs with bitfield accesses.
+ BasicBlock::iterator BBI = &SI;
+ for (unsigned ScanInsts = 6; BBI != SI.getParent()->begin() && ScanInsts;
+ --ScanInsts) {
+ --BBI;
+
+ if (StoreInst *PrevSI = dyn_cast<StoreInst>(BBI)) {
+ // Prev store isn't volatile, and stores to the same location?
+ if (!PrevSI->isVolatile() && PrevSI->getOperand(1) == SI.getOperand(1)) {
+ ++NumDeadStore;
+ ++BBI;
+ EraseInstFromFunction(*PrevSI);
+ continue;
+ }
+ break;
+ }
+
+ // If this is a load, we have to stop. However, if the loaded value is from
+ // the pointer we're loading and is producing the pointer we're storing,
+ // then *this* store is dead (X = load P; store X -> P).
+ if (LoadInst *LI = dyn_cast<LoadInst>(BBI)) {
+ if (LI == Val && LI->getOperand(0) == Ptr) {
+ EraseInstFromFunction(SI);
+ ++NumCombined;
+ return 0;
+ }
+ // Otherwise, this is a load from some other location. Stores before it
+ // may not be dead.
+ break;
+ }
+
+ // Don't skip over loads or things that can modify memory.
+ if (BBI->mayWriteToMemory())
+ break;
+ }
+
+
+ if (SI.isVolatile()) return 0; // Don't hack volatile stores.
+
+ // store X, null -> turns into 'unreachable' in SimplifyCFG
+ if (isa<ConstantPointerNull>(Ptr)) {
+ if (!isa<UndefValue>(Val)) {
+ SI.setOperand(0, UndefValue::get(Val->getType()));
+ if (Instruction *U = dyn_cast<Instruction>(Val))
+ AddToWorkList(U); // Dropped a use.
+ ++NumCombined;
+ }
+ return 0; // Do not modify these!
+ }
+
+ // store undef, Ptr -> noop
+ if (isa<UndefValue>(Val)) {
+ EraseInstFromFunction(SI);
+ ++NumCombined;
+ return 0;
+ }
+
+ // If the pointer destination is a cast, see if we can fold the cast into the
+ // source instead.
+ if (isa<CastInst>(Ptr))
+ if (Instruction *Res = InstCombineStoreToCast(*this, SI))
+ return Res;
+ if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ptr))
+ if (CE->isCast())
+ if (Instruction *Res = InstCombineStoreToCast(*this, SI))
+ return Res;
+
+
+ // If this store is the last instruction in the basic block, and if the block
+ // ends with an unconditional branch, try to move it to the successor block.
+ BBI = &SI; ++BBI;
+ if (BranchInst *BI = dyn_cast<BranchInst>(BBI))
+ if (BI->isUnconditional())
+ if (SimplifyStoreAtEndOfBlock(SI))
+ return 0; // xform done!
+
+ return 0;
+}
+
+/// SimplifyStoreAtEndOfBlock - Turn things like:
+/// if () { *P = v1; } else { *P = v2 }
+/// into a phi node with a store in the successor.
+///
+/// Simplify things like:
+/// *P = v1; if () { *P = v2; }
+/// into a phi node with a store in the successor.
+///
+bool InstCombiner::SimplifyStoreAtEndOfBlock(StoreInst &SI) {
+ BasicBlock *StoreBB = SI.getParent();
+
+ // Check to see if the successor block has exactly two incoming edges. If
+ // so, see if the other predecessor contains a store to the same location.
+ // if so, insert a PHI node (if needed) and move the stores down.
+ BasicBlock *DestBB = StoreBB->getTerminator()->getSuccessor(0);
+
+ // Determine whether Dest has exactly two predecessors and, if so, compute
+ // the other predecessor.
+ pred_iterator PI = pred_begin(DestBB);
+ BasicBlock *OtherBB = 0;
+ if (*PI != StoreBB)
+ OtherBB = *PI;
+ ++PI;
+ if (PI == pred_end(DestBB))
+ return false;
+
+ if (*PI != StoreBB) {
+ if (OtherBB)
+ return false;
+ OtherBB = *PI;
+ }
+ if (++PI != pred_end(DestBB))
+ return false;
+
+
+ // Verify that the other block ends in a branch and is not otherwise empty.
+ BasicBlock::iterator BBI = OtherBB->getTerminator();
+ BranchInst *OtherBr = dyn_cast<BranchInst>(BBI);
+ if (!OtherBr || BBI == OtherBB->begin())
+ return false;
+
+ // If the other block ends in an unconditional branch, check for the 'if then
+ // else' case. there is an instruction before the branch.
+ StoreInst *OtherStore = 0;
+ if (OtherBr->isUnconditional()) {
+ // If this isn't a store, or isn't a store to the same location, bail out.
+ --BBI;
+ OtherStore = dyn_cast<StoreInst>(BBI);
+ if (!OtherStore || OtherStore->getOperand(1) != SI.getOperand(1))
+ return false;
+ } else {
+ // Otherwise, the other block ended with a conditional branch. If one of the
+ // destinations is StoreBB, then we have the if/then case.
+ if (OtherBr->getSuccessor(0) != StoreBB &&
+ OtherBr->getSuccessor(1) != StoreBB)
+ return false;
+
+ // Okay, we know that OtherBr now goes to Dest and StoreBB, so this is an
+ // if/then triangle. See if there is a store to the same ptr as SI that
+ // lives in OtherBB.
+ for (;; --BBI) {
+ // Check to see if we find the matching store.
+ if ((OtherStore = dyn_cast<StoreInst>(BBI))) {
+ if (OtherStore->getOperand(1) != SI.getOperand(1))
+ return false;
+ break;
+ }
+ // If we find something that may be using the stored value, or if we run
+ // out of instructions, we can't do the xform.
+ if (isa<LoadInst>(BBI) || BBI->mayWriteToMemory() ||
+ BBI == OtherBB->begin())
+ return false;
+ }
+
+ // In order to eliminate the store in OtherBr, we have to
+ // make sure nothing reads the stored value in StoreBB.
+ for (BasicBlock::iterator I = StoreBB->begin(); &*I != &SI; ++I) {
+ // FIXME: This should really be AA driven.
+ if (isa<LoadInst>(I) || I->mayWriteToMemory())
+ return false;
+ }
+ }
+
+ // Insert a PHI node now if we need it.
+ Value *MergedVal = OtherStore->getOperand(0);
+ if (MergedVal != SI.getOperand(0)) {
+ PHINode *PN = new PHINode(MergedVal->getType(), "storemerge");
+ PN->reserveOperandSpace(2);
+ PN->addIncoming(SI.getOperand(0), SI.getParent());
+ PN->addIncoming(OtherStore->getOperand(0), OtherBB);
+ MergedVal = InsertNewInstBefore(PN, DestBB->front());
+ }
+
+ // Advance to a place where it is safe to insert the new store and
+ // insert it.
+ BBI = DestBB->begin();
+ while (isa<PHINode>(BBI)) ++BBI;
+ InsertNewInstBefore(new StoreInst(MergedVal, SI.getOperand(1),
+ OtherStore->isVolatile()), *BBI);
+
+ // Nuke the old stores.
+ EraseInstFromFunction(SI);
+ EraseInstFromFunction(*OtherStore);
+ ++NumCombined;
+ return true;
+}
+
+
+Instruction *InstCombiner::visitBranchInst(BranchInst &BI) {
+ // Change br (not X), label True, label False to: br X, label False, True
+ Value *X = 0;
+ BasicBlock *TrueDest;
+ BasicBlock *FalseDest;
+ if (match(&BI, m_Br(m_Not(m_Value(X)), TrueDest, FalseDest)) &&
+ !isa<Constant>(X)) {
+ // Swap Destinations and condition...
+ BI.setCondition(X);
+ BI.setSuccessor(0, FalseDest);
+ BI.setSuccessor(1, TrueDest);
+ return &BI;
+ }
+
+ // Cannonicalize fcmp_one -> fcmp_oeq
+ FCmpInst::Predicate FPred; Value *Y;
+ if (match(&BI, m_Br(m_FCmp(FPred, m_Value(X), m_Value(Y)),
+ TrueDest, FalseDest)))
+ if ((FPred == FCmpInst::FCMP_ONE || FPred == FCmpInst::FCMP_OLE ||
+ FPred == FCmpInst::FCMP_OGE) && BI.getCondition()->hasOneUse()) {
+ FCmpInst *I = cast<FCmpInst>(BI.getCondition());
+ FCmpInst::Predicate NewPred = FCmpInst::getInversePredicate(FPred);
+ Instruction *NewSCC = new FCmpInst(NewPred, X, Y, "", I);
+ NewSCC->takeName(I);
+ // Swap Destinations and condition...
+ BI.setCondition(NewSCC);
+ BI.setSuccessor(0, FalseDest);
+ BI.setSuccessor(1, TrueDest);
+ RemoveFromWorkList(I);
+ I->eraseFromParent();
+ AddToWorkList(NewSCC);
+ return &BI;
+ }
+
+ // Cannonicalize icmp_ne -> icmp_eq
+ ICmpInst::Predicate IPred;
+ if (match(&BI, m_Br(m_ICmp(IPred, m_Value(X), m_Value(Y)),
+ TrueDest, FalseDest)))
+ if ((IPred == ICmpInst::ICMP_NE || IPred == ICmpInst::ICMP_ULE ||
+ IPred == ICmpInst::ICMP_SLE || IPred == ICmpInst::ICMP_UGE ||
+ IPred == ICmpInst::ICMP_SGE) && BI.getCondition()->hasOneUse()) {
+ ICmpInst *I = cast<ICmpInst>(BI.getCondition());
+ ICmpInst::Predicate NewPred = ICmpInst::getInversePredicate(IPred);
+ Instruction *NewSCC = new ICmpInst(NewPred, X, Y, "", I);
+ NewSCC->takeName(I);
+ // Swap Destinations and condition...
+ BI.setCondition(NewSCC);
+ BI.setSuccessor(0, FalseDest);
+ BI.setSuccessor(1, TrueDest);
+ RemoveFromWorkList(I);
+ I->eraseFromParent();;
+ AddToWorkList(NewSCC);
+ return &BI;
+ }
+
+ return 0;
+}
+
+Instruction *InstCombiner::visitSwitchInst(SwitchInst &SI) {
+ Value *Cond = SI.getCondition();
+ if (Instruction *I = dyn_cast<Instruction>(Cond)) {
+ if (I->getOpcode() == Instruction::Add)
+ if (ConstantInt *AddRHS = dyn_cast<ConstantInt>(I->getOperand(1))) {
+ // change 'switch (X+4) case 1:' into 'switch (X) case -3'
+ for (unsigned i = 2, e = SI.getNumOperands(); i != e; i += 2)
+ SI.setOperand(i,ConstantExpr::getSub(cast<Constant>(SI.getOperand(i)),
+ AddRHS));
+ SI.setOperand(0, I->getOperand(0));
+ AddToWorkList(I);
+ return &SI;
+ }
+ }
+ return 0;
+}
+
+/// CheapToScalarize - Return true if the value is cheaper to scalarize than it
+/// is to leave as a vector operation.
+static bool CheapToScalarize(Value *V, bool isConstant) {
+ if (isa<ConstantAggregateZero>(V))
+ return true;
+ if (ConstantVector *C = dyn_cast<ConstantVector>(V)) {
+ if (isConstant) return true;
+ // If all elts are the same, we can extract.
+ Constant *Op0 = C->getOperand(0);
+ for (unsigned i = 1; i < C->getNumOperands(); ++i)
+ if (C->getOperand(i) != Op0)
+ return false;
+ return true;
+ }
+ Instruction *I = dyn_cast<Instruction>(V);
+ if (!I) return false;
+
+ // Insert element gets simplified to the inserted element or is deleted if
+ // this is constant idx extract element and its a constant idx insertelt.
+ if (I->getOpcode() == Instruction::InsertElement && isConstant &&
+ isa<ConstantInt>(I->getOperand(2)))
+ return true;
+ if (I->getOpcode() == Instruction::Load && I->hasOneUse())
+ return true;
+ if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I))
+ if (BO->hasOneUse() &&
+ (CheapToScalarize(BO->getOperand(0), isConstant) ||
+ CheapToScalarize(BO->getOperand(1), isConstant)))
+ return true;
+ if (CmpInst *CI = dyn_cast<CmpInst>(I))
+ if (CI->hasOneUse() &&
+ (CheapToScalarize(CI->getOperand(0), isConstant) ||
+ CheapToScalarize(CI->getOperand(1), isConstant)))
+ return true;
+
+ return false;
+}
+
+/// Read and decode a shufflevector mask.
+///
+/// It turns undef elements into values that are larger than the number of
+/// elements in the input.
+static std::vector<unsigned> getShuffleMask(const ShuffleVectorInst *SVI) {
+ unsigned NElts = SVI->getType()->getNumElements();
+ if (isa<ConstantAggregateZero>(SVI->getOperand(2)))
+ return std::vector<unsigned>(NElts, 0);
+ if (isa<UndefValue>(SVI->getOperand(2)))
+ return std::vector<unsigned>(NElts, 2*NElts);
+
+ std::vector<unsigned> Result;
+ const ConstantVector *CP = cast<ConstantVector>(SVI->getOperand(2));
+ for (unsigned i = 0, e = CP->getNumOperands(); i != e; ++i)
+ if (isa<UndefValue>(CP->getOperand(i)))
+ Result.push_back(NElts*2); // undef -> 8
+ else
+ Result.push_back(cast<ConstantInt>(CP->getOperand(i))->getZExtValue());
+ return Result;
+}
+
+/// FindScalarElement - Given a vector and an element number, see if the scalar
+/// value is already around as a register, for example if it were inserted then
+/// extracted from the vector.
+static Value *FindScalarElement(Value *V, unsigned EltNo) {
+ assert(isa<VectorType>(V->getType()) && "Not looking at a vector?");
+ const VectorType *PTy = cast<VectorType>(V->getType());
+ unsigned Width = PTy->getNumElements();
+ if (EltNo >= Width) // Out of range access.
+ return UndefValue::get(PTy->getElementType());
+
+ if (isa<UndefValue>(V))
+ return UndefValue::get(PTy->getElementType());
+ else if (isa<ConstantAggregateZero>(V))
+ return Constant::getNullValue(PTy->getElementType());
+ else if (ConstantVector *CP = dyn_cast<ConstantVector>(V))
+ return CP->getOperand(EltNo);
+ else if (InsertElementInst *III = dyn_cast<InsertElementInst>(V)) {
+ // If this is an insert to a variable element, we don't know what it is.
+ if (!isa<ConstantInt>(III->getOperand(2)))
+ return 0;
+ unsigned IIElt = cast<ConstantInt>(III->getOperand(2))->getZExtValue();
+
+ // If this is an insert to the element we are looking for, return the
+ // inserted value.
+ if (EltNo == IIElt)
+ return III->getOperand(1);
+
+ // Otherwise, the insertelement doesn't modify the value, recurse on its
+ // vector input.
+ return FindScalarElement(III->getOperand(0), EltNo);
+ } else if (ShuffleVectorInst *SVI = dyn_cast<ShuffleVectorInst>(V)) {
+ unsigned InEl = getShuffleMask(SVI)[EltNo];
+ if (InEl < Width)
+ return FindScalarElement(SVI->getOperand(0), InEl);
+ else if (InEl < Width*2)
+ return FindScalarElement(SVI->getOperand(1), InEl - Width);
+ else
+ return UndefValue::get(PTy->getElementType());
+ }
+
+ // Otherwise, we don't know.
+ return 0;
+}
+
+Instruction *InstCombiner::visitExtractElementInst(ExtractElementInst &EI) {
+
+ // If vector val is undef, replace extract with scalar undef.
+ if (isa<UndefValue>(EI.getOperand(0)))
+ return ReplaceInstUsesWith(EI, UndefValue::get(EI.getType()));
+
+ // If vector val is constant 0, replace extract with scalar 0.
+ if (isa<ConstantAggregateZero>(EI.getOperand(0)))
+ return ReplaceInstUsesWith(EI, Constant::getNullValue(EI.getType()));
+
+ if (ConstantVector *C = dyn_cast<ConstantVector>(EI.getOperand(0))) {
+ // If vector val is constant with uniform operands, replace EI
+ // with that operand
+ Constant *op0 = C->getOperand(0);
+ for (unsigned i = 1; i < C->getNumOperands(); ++i)
+ if (C->getOperand(i) != op0) {
+ op0 = 0;
+ break;
+ }
+ if (op0)
+ return ReplaceInstUsesWith(EI, op0);
+ }
+
+ // If extracting a specified index from the vector, see if we can recursively
+ // find a previously computed scalar that was inserted into the vector.
+ if (ConstantInt *IdxC = dyn_cast<ConstantInt>(EI.getOperand(1))) {
+ unsigned IndexVal = IdxC->getZExtValue();
+ unsigned VectorWidth =
+ cast<VectorType>(EI.getOperand(0)->getType())->getNumElements();
+
+ // If this is extracting an invalid index, turn this into undef, to avoid
+ // crashing the code below.
+ if (IndexVal >= VectorWidth)
+ return ReplaceInstUsesWith(EI, UndefValue::get(EI.getType()));
+
+ // This instruction only demands the single element from the input vector.
+ // If the input vector has a single use, simplify it based on this use
+ // property.
+ if (EI.getOperand(0)->hasOneUse() && VectorWidth != 1) {
+ uint64_t UndefElts;
+ if (Value *V = SimplifyDemandedVectorElts(EI.getOperand(0),
+ 1 << IndexVal,
+ UndefElts)) {
+ EI.setOperand(0, V);
+ return &EI;
+ }
+ }
+
+ if (Value *Elt = FindScalarElement(EI.getOperand(0), IndexVal))
+ return ReplaceInstUsesWith(EI, Elt);
+
+ // If the this extractelement is directly using a bitcast from a vector of
+ // the same number of elements, see if we can find the source element from
+ // it. In this case, we will end up needing to bitcast the scalars.
+ if (BitCastInst *BCI = dyn_cast<BitCastInst>(EI.getOperand(0))) {
+ if (const VectorType *VT =
+ dyn_cast<VectorType>(BCI->getOperand(0)->getType()))
+ if (VT->getNumElements() == VectorWidth)
+ if (Value *Elt = FindScalarElement(BCI->getOperand(0), IndexVal))
+ return new BitCastInst(Elt, EI.getType());
+ }
+ }
+
+ if (Instruction *I = dyn_cast<Instruction>(EI.getOperand(0))) {
+ if (I->hasOneUse()) {
+ // Push extractelement into predecessor operation if legal and
+ // profitable to do so
+ if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) {
+ bool isConstantElt = isa<ConstantInt>(EI.getOperand(1));
+ if (CheapToScalarize(BO, isConstantElt)) {
+ ExtractElementInst *newEI0 =
+ new ExtractElementInst(BO->getOperand(0), EI.getOperand(1),
+ EI.getName()+".lhs");
+ ExtractElementInst *newEI1 =
+ new ExtractElementInst(BO->getOperand(1), EI.getOperand(1),
+ EI.getName()+".rhs");
+ InsertNewInstBefore(newEI0, EI);
+ InsertNewInstBefore(newEI1, EI);
+ return BinaryOperator::create(BO->getOpcode(), newEI0, newEI1);
+ }
+ } else if (isa<LoadInst>(I)) {
+ Value *Ptr = InsertCastBefore(Instruction::BitCast, I->getOperand(0),
+ PointerType::get(EI.getType()), EI);
+ GetElementPtrInst *GEP =
+ new GetElementPtrInst(Ptr, EI.getOperand(1), I->getName() + ".gep");
+ InsertNewInstBefore(GEP, EI);
+ return new LoadInst(GEP);
+ }
+ }
+ if (InsertElementInst *IE = dyn_cast<InsertElementInst>(I)) {
+ // Extracting the inserted element?
+ if (IE->getOperand(2) == EI.getOperand(1))
+ return ReplaceInstUsesWith(EI, IE->getOperand(1));
+ // If the inserted and extracted elements are constants, they must not
+ // be the same value, extract from the pre-inserted value instead.
+ if (isa<Constant>(IE->getOperand(2)) &&
+ isa<Constant>(EI.getOperand(1))) {
+ AddUsesToWorkList(EI);
+ EI.setOperand(0, IE->getOperand(0));
+ return &EI;
+ }
+ } else if (ShuffleVectorInst *SVI = dyn_cast<ShuffleVectorInst>(I)) {
+ // If this is extracting an element from a shufflevector, figure out where
+ // it came from and extract from the appropriate input element instead.
+ if (ConstantInt *Elt = dyn_cast<ConstantInt>(EI.getOperand(1))) {
+ unsigned SrcIdx = getShuffleMask(SVI)[Elt->getZExtValue()];
+ Value *Src;
+ if (SrcIdx < SVI->getType()->getNumElements())
+ Src = SVI->getOperand(0);
+ else if (SrcIdx < SVI->getType()->getNumElements()*2) {
+ SrcIdx -= SVI->getType()->getNumElements();
+ Src = SVI->getOperand(1);
+ } else {
+ return ReplaceInstUsesWith(EI, UndefValue::get(EI.getType()));
+ }
+ return new ExtractElementInst(Src, SrcIdx);
+ }
+ }
+ }
+ return 0;
+}
+
+/// CollectSingleShuffleElements - If V is a shuffle of values that ONLY returns
+/// elements from either LHS or RHS, return the shuffle mask and true.
+/// Otherwise, return false.
+static bool CollectSingleShuffleElements(Value *V, Value *LHS, Value *RHS,
+ std::vector<Constant*> &Mask) {
+ assert(V->getType() == LHS->getType() && V->getType() == RHS->getType() &&
+ "Invalid CollectSingleShuffleElements");
+ unsigned NumElts = cast<VectorType>(V->getType())->getNumElements();
+
+ if (isa<UndefValue>(V)) {
+ Mask.assign(NumElts, UndefValue::get(Type::Int32Ty));
+ return true;
+ } else if (V == LHS) {
+ for (unsigned i = 0; i != NumElts; ++i)
+ Mask.push_back(ConstantInt::get(Type::Int32Ty, i));
+ return true;
+ } else if (V == RHS) {
+ for (unsigned i = 0; i != NumElts; ++i)
+ Mask.push_back(ConstantInt::get(Type::Int32Ty, i+NumElts));
+ return true;
+ } else if (InsertElementInst *IEI = dyn_cast<InsertElementInst>(V)) {
+ // If this is an insert of an extract from some other vector, include it.
+ Value *VecOp = IEI->getOperand(0);
+ Value *ScalarOp = IEI->getOperand(1);
+ Value *IdxOp = IEI->getOperand(2);
+
+ if (!isa<ConstantInt>(IdxOp))
+ return false;
+ unsigned InsertedIdx = cast<ConstantInt>(IdxOp)->getZExtValue();
+
+ if (isa<UndefValue>(ScalarOp)) { // inserting undef into vector.
+ // Okay, we can handle this if the vector we are insertinting into is
+ // transitively ok.
+ if (CollectSingleShuffleElements(VecOp, LHS, RHS, Mask)) {
+ // If so, update the mask to reflect the inserted undef.
+ Mask[InsertedIdx] = UndefValue::get(Type::Int32Ty);
+ return true;
+ }
+ } else if (ExtractElementInst *EI = dyn_cast<ExtractElementInst>(ScalarOp)){
+ if (isa<ConstantInt>(EI->getOperand(1)) &&
+ EI->getOperand(0)->getType() == V->getType()) {
+ unsigned ExtractedIdx =
+ cast<ConstantInt>(EI->getOperand(1))->getZExtValue();
+
+ // This must be extracting from either LHS or RHS.
+ if (EI->getOperand(0) == LHS || EI->getOperand(0) == RHS) {
+ // Okay, we can handle this if the vector we are insertinting into is
+ // transitively ok.
+ if (CollectSingleShuffleElements(VecOp, LHS, RHS, Mask)) {
+ // If so, update the mask to reflect the inserted value.
+ if (EI->getOperand(0) == LHS) {
+ Mask[InsertedIdx & (NumElts-1)] =
+ ConstantInt::get(Type::Int32Ty, ExtractedIdx);
+ } else {
+ assert(EI->getOperand(0) == RHS);
+ Mask[InsertedIdx & (NumElts-1)] =
+ ConstantInt::get(Type::Int32Ty, ExtractedIdx+NumElts);
+
+ }
+ return true;
+ }
+ }
+ }
+ }
+ }
+ // TODO: Handle shufflevector here!
+
+ return false;
+}
+
+/// CollectShuffleElements - We are building a shuffle of V, using RHS as the
+/// RHS of the shuffle instruction, if it is not null. Return a shuffle mask
+/// that computes V and the LHS value of the shuffle.
+static Value *CollectShuffleElements(Value *V, std::vector<Constant*> &Mask,
+ Value *&RHS) {
+ assert(isa<VectorType>(V->getType()) &&
+ (RHS == 0 || V->getType() == RHS->getType()) &&
+ "Invalid shuffle!");
+ unsigned NumElts = cast<VectorType>(V->getType())->getNumElements();
+
+ if (isa<UndefValue>(V)) {
+ Mask.assign(NumElts, UndefValue::get(Type::Int32Ty));
+ return V;
+ } else if (isa<ConstantAggregateZero>(V)) {
+ Mask.assign(NumElts, ConstantInt::get(Type::Int32Ty, 0));
+ return V;
+ } else if (InsertElementInst *IEI = dyn_cast<InsertElementInst>(V)) {
+ // If this is an insert of an extract from some other vector, include it.
+ Value *VecOp = IEI->getOperand(0);
+ Value *ScalarOp = IEI->getOperand(1);
+ Value *IdxOp = IEI->getOperand(2);
+
+ if (ExtractElementInst *EI = dyn_cast<ExtractElementInst>(ScalarOp)) {
+ if (isa<ConstantInt>(EI->getOperand(1)) && isa<ConstantInt>(IdxOp) &&
+ EI->getOperand(0)->getType() == V->getType()) {
+ unsigned ExtractedIdx =
+ cast<ConstantInt>(EI->getOperand(1))->getZExtValue();
+ unsigned InsertedIdx = cast<ConstantInt>(IdxOp)->getZExtValue();
+
+ // Either the extracted from or inserted into vector must be RHSVec,
+ // otherwise we'd end up with a shuffle of three inputs.
+ if (EI->getOperand(0) == RHS || RHS == 0) {
+ RHS = EI->getOperand(0);
+ Value *V = CollectShuffleElements(VecOp, Mask, RHS);
+ Mask[InsertedIdx & (NumElts-1)] =
+ ConstantInt::get(Type::Int32Ty, NumElts+ExtractedIdx);
+ return V;
+ }
+
+ if (VecOp == RHS) {
+ Value *V = CollectShuffleElements(EI->getOperand(0), Mask, RHS);
+ // Everything but the extracted element is replaced with the RHS.
+ for (unsigned i = 0; i != NumElts; ++i) {
+ if (i != InsertedIdx)
+ Mask[i] = ConstantInt::get(Type::Int32Ty, NumElts+i);
+ }
+ return V;
+ }
+
+ // If this insertelement is a chain that comes from exactly these two
+ // vectors, return the vector and the effective shuffle.
+ if (CollectSingleShuffleElements(IEI, EI->getOperand(0), RHS, Mask))
+ return EI->getOperand(0);
+
+ }
+ }
+ }
+ // TODO: Handle shufflevector here!
+
+ // Otherwise, can't do anything fancy. Return an identity vector.
+ for (unsigned i = 0; i != NumElts; ++i)
+ Mask.push_back(ConstantInt::get(Type::Int32Ty, i));
+ return V;
+}
+
+Instruction *InstCombiner::visitInsertElementInst(InsertElementInst &IE) {
+ Value *VecOp = IE.getOperand(0);
+ Value *ScalarOp = IE.getOperand(1);
+ Value *IdxOp = IE.getOperand(2);
+
+ // Inserting an undef or into an undefined place, remove this.
+ if (isa<UndefValue>(ScalarOp) || isa<UndefValue>(IdxOp))
+ ReplaceInstUsesWith(IE, VecOp);
+
+ // If the inserted element was extracted from some other vector, and if the
+ // indexes are constant, try to turn this into a shufflevector operation.
+ if (ExtractElementInst *EI = dyn_cast<ExtractElementInst>(ScalarOp)) {
+ if (isa<ConstantInt>(EI->getOperand(1)) && isa<ConstantInt>(IdxOp) &&
+ EI->getOperand(0)->getType() == IE.getType()) {
+ unsigned NumVectorElts = IE.getType()->getNumElements();
+ unsigned ExtractedIdx =
+ cast<ConstantInt>(EI->getOperand(1))->getZExtValue();
+ unsigned InsertedIdx = cast<ConstantInt>(IdxOp)->getZExtValue();
+
+ if (ExtractedIdx >= NumVectorElts) // Out of range extract.
+ return ReplaceInstUsesWith(IE, VecOp);
+
+ if (InsertedIdx >= NumVectorElts) // Out of range insert.
+ return ReplaceInstUsesWith(IE, UndefValue::get(IE.getType()));
+
+ // If we are extracting a value from a vector, then inserting it right
+ // back into the same place, just use the input vector.
+ if (EI->getOperand(0) == VecOp && ExtractedIdx == InsertedIdx)
+ return ReplaceInstUsesWith(IE, VecOp);
+
+ // We could theoretically do this for ANY input. However, doing so could
+ // turn chains of insertelement instructions into a chain of shufflevector
+ // instructions, and right now we do not merge shufflevectors. As such,
+ // only do this in a situation where it is clear that there is benefit.
+ if (isa<UndefValue>(VecOp) || isa<ConstantAggregateZero>(VecOp)) {
+ // Turn this into shuffle(EIOp0, VecOp, Mask). The result has all of
+ // the values of VecOp, except then one read from EIOp0.
+ // Build a new shuffle mask.
+ std::vector<Constant*> Mask;
+ if (isa<UndefValue>(VecOp))
+ Mask.assign(NumVectorElts, UndefValue::get(Type::Int32Ty));
+ else {
+ assert(isa<ConstantAggregateZero>(VecOp) && "Unknown thing");
+ Mask.assign(NumVectorElts, ConstantInt::get(Type::Int32Ty,
+ NumVectorElts));
+ }
+ Mask[InsertedIdx] = ConstantInt::get(Type::Int32Ty, ExtractedIdx);
+ return new ShuffleVectorInst(EI->getOperand(0), VecOp,
+ ConstantVector::get(Mask));
+ }
+
+ // If this insertelement isn't used by some other insertelement, turn it
+ // (and any insertelements it points to), into one big shuffle.
+ if (!IE.hasOneUse() || !isa<InsertElementInst>(IE.use_back())) {
+ std::vector<Constant*> Mask;
+ Value *RHS = 0;
+ Value *LHS = CollectShuffleElements(&IE, Mask, RHS);
+ if (RHS == 0) RHS = UndefValue::get(LHS->getType());
+ // We now have a shuffle of LHS, RHS, Mask.
+ return new ShuffleVectorInst(LHS, RHS, ConstantVector::get(Mask));
+ }
+ }
+ }
+
+ return 0;
+}
+
+
+Instruction *InstCombiner::visitShuffleVectorInst(ShuffleVectorInst &SVI) {
+ Value *LHS = SVI.getOperand(0);
+ Value *RHS = SVI.getOperand(1);
+ std::vector<unsigned> Mask = getShuffleMask(&SVI);
+
+ bool MadeChange = false;
+
+ // Undefined shuffle mask -> undefined value.
+ if (isa<UndefValue>(SVI.getOperand(2)))
+ return ReplaceInstUsesWith(SVI, UndefValue::get(SVI.getType()));
+
+ // If we have shuffle(x, undef, mask) and any elements of mask refer to
+ // the undef, change them to undefs.
+ if (isa<UndefValue>(SVI.getOperand(1))) {
+ // Scan to see if there are any references to the RHS. If so, replace them
+ // with undef element refs and set MadeChange to true.
+ for (unsigned i = 0, e = Mask.size(); i != e; ++i) {
+ if (Mask[i] >= e && Mask[i] != 2*e) {
+ Mask[i] = 2*e;
+ MadeChange = true;
+ }
+ }
+
+ if (MadeChange) {
+ // Remap any references to RHS to use LHS.
+ std::vector<Constant*> Elts;
+ for (unsigned i = 0, e = Mask.size(); i != e; ++i) {
+ if (Mask[i] == 2*e)
+ Elts.push_back(UndefValue::get(Type::Int32Ty));
+ else
+ Elts.push_back(ConstantInt::get(Type::Int32Ty, Mask[i]));
+ }
+ SVI.setOperand(2, ConstantVector::get(Elts));
+ }
+ }
+
+ // Canonicalize shuffle(x ,x,mask) -> shuffle(x, undef,mask')
+ // Canonicalize shuffle(undef,x,mask) -> shuffle(x, undef,mask').
+ if (LHS == RHS || isa<UndefValue>(LHS)) {
+ if (isa<UndefValue>(LHS) && LHS == RHS) {
+ // shuffle(undef,undef,mask) -> undef.
+ return ReplaceInstUsesWith(SVI, LHS);
+ }
+
+ // Remap any references to RHS to use LHS.
+ std::vector<Constant*> Elts;
+ for (unsigned i = 0, e = Mask.size(); i != e; ++i) {
+ if (Mask[i] >= 2*e)
+ Elts.push_back(UndefValue::get(Type::Int32Ty));
+ else {
+ if ((Mask[i] >= e && isa<UndefValue>(RHS)) ||
+ (Mask[i] < e && isa<UndefValue>(LHS)))
+ Mask[i] = 2*e; // Turn into undef.
+ else
+ Mask[i] &= (e-1); // Force to LHS.
+ Elts.push_back(ConstantInt::get(Type::Int32Ty, Mask[i]));
+ }
+ }
+ SVI.setOperand(0, SVI.getOperand(1));
+ SVI.setOperand(1, UndefValue::get(RHS->getType()));
+ SVI.setOperand(2, ConstantVector::get(Elts));
+ LHS = SVI.getOperand(0);
+ RHS = SVI.getOperand(1);
+ MadeChange = true;
+ }
+
+ // Analyze the shuffle, are the LHS or RHS and identity shuffles?
+ bool isLHSID = true, isRHSID = true;
+
+ for (unsigned i = 0, e = Mask.size(); i != e; ++i) {
+ if (Mask[i] >= e*2) continue; // Ignore undef values.
+ // Is this an identity shuffle of the LHS value?
+ isLHSID &= (Mask[i] == i);
+
+ // Is this an identity shuffle of the RHS value?
+ isRHSID &= (Mask[i]-e == i);
+ }
+
+ // Eliminate identity shuffles.
+ if (isLHSID) return ReplaceInstUsesWith(SVI, LHS);
+ if (isRHSID) return ReplaceInstUsesWith(SVI, RHS);
+
+ // If the LHS is a shufflevector itself, see if we can combine it with this
+ // one without producing an unusual shuffle. Here we are really conservative:
+ // we are absolutely afraid of producing a shuffle mask not in the input
+ // program, because the code gen may not be smart enough to turn a merged
+ // shuffle into two specific shuffles: it may produce worse code. As such,
+ // we only merge two shuffles if the result is one of the two input shuffle
+ // masks. In this case, merging the shuffles just removes one instruction,
+ // which we know is safe. This is good for things like turning:
+ // (splat(splat)) -> splat.
+ if (ShuffleVectorInst *LHSSVI = dyn_cast<ShuffleVectorInst>(LHS)) {
+ if (isa<UndefValue>(RHS)) {
+ std::vector<unsigned> LHSMask = getShuffleMask(LHSSVI);
+
+ std::vector<unsigned> NewMask;
+ for (unsigned i = 0, e = Mask.size(); i != e; ++i)
+ if (Mask[i] >= 2*e)
+ NewMask.push_back(2*e);
+ else
+ NewMask.push_back(LHSMask[Mask[i]]);
+
+ // If the result mask is equal to the src shuffle or this shuffle mask, do
+ // the replacement.
+ if (NewMask == LHSMask || NewMask == Mask) {
+ std::vector<Constant*> Elts;
+ for (unsigned i = 0, e = NewMask.size(); i != e; ++i) {
+ if (NewMask[i] >= e*2) {
+ Elts.push_back(UndefValue::get(Type::Int32Ty));
+ } else {
+ Elts.push_back(ConstantInt::get(Type::Int32Ty, NewMask[i]));
+ }
+ }
+ return new ShuffleVectorInst(LHSSVI->getOperand(0),
+ LHSSVI->getOperand(1),
+ ConstantVector::get(Elts));
+ }
+ }
+ }
+
+ return MadeChange ? &SVI : 0;
+}
+
+
+
+
+/// TryToSinkInstruction - Try to move the specified instruction from its
+/// current block into the beginning of DestBlock, which can only happen if it's
+/// safe to move the instruction past all of the instructions between it and the
+/// end of its block.
+static bool TryToSinkInstruction(Instruction *I, BasicBlock *DestBlock) {
+ assert(I->hasOneUse() && "Invariants didn't hold!");
+
+ // Cannot move control-flow-involving, volatile loads, vaarg, etc.
+ if (isa<PHINode>(I) || I->mayWriteToMemory()) return false;
+
+ // Do not sink alloca instructions out of the entry block.
+ if (isa<AllocaInst>(I) && I->getParent() ==
+ &DestBlock->getParent()->getEntryBlock())
+ return false;
+
+ // We can only sink load instructions if there is nothing between the load and
+ // the end of block that could change the value.
+ if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
+ for (BasicBlock::iterator Scan = LI, E = LI->getParent()->end();
+ Scan != E; ++Scan)
+ if (Scan->mayWriteToMemory())
+ return false;
+ }
+
+ BasicBlock::iterator InsertPos = DestBlock->begin();
+ while (isa<PHINode>(InsertPos)) ++InsertPos;
+
+ I->moveBefore(InsertPos);
+ ++NumSunkInst;
+ return true;
+}
+
+
+/// AddReachableCodeToWorklist - Walk the function in depth-first order, adding
+/// all reachable code to the worklist.
+///
+/// This has a couple of tricks to make the code faster and more powerful. In
+/// particular, we constant fold and DCE instructions as we go, to avoid adding
+/// them to the worklist (this significantly speeds up instcombine on code where
+/// many instructions are dead or constant). Additionally, if we find a branch
+/// whose condition is a known constant, we only visit the reachable successors.
+///
+static void AddReachableCodeToWorklist(BasicBlock *BB,
+ SmallPtrSet<BasicBlock*, 64> &Visited,
+ InstCombiner &IC,
+ const TargetData *TD) {
+ std::vector<BasicBlock*> Worklist;
+ Worklist.push_back(BB);
+
+ while (!Worklist.empty()) {
+ BB = Worklist.back();
+ Worklist.pop_back();
+
+ // We have now visited this block! If we've already been here, ignore it.
+ if (!Visited.insert(BB)) continue;
+
+ for (BasicBlock::iterator BBI = BB->begin(), E = BB->end(); BBI != E; ) {
+ Instruction *Inst = BBI++;
+
+ // DCE instruction if trivially dead.
+ if (isInstructionTriviallyDead(Inst)) {
+ ++NumDeadInst;
+ DOUT << "IC: DCE: " << *Inst;
+ Inst->eraseFromParent();
+ continue;
+ }
+
+ // ConstantProp instruction if trivially constant.
+ if (Constant *C = ConstantFoldInstruction(Inst, TD)) {
+ DOUT << "IC: ConstFold to: " << *C << " from: " << *Inst;
+ Inst->replaceAllUsesWith(C);
+ ++NumConstProp;
+ Inst->eraseFromParent();
+ continue;
+ }
+
+ IC.AddToWorkList(Inst);
+ }
+
+ // Recursively visit successors. If this is a branch or switch on a
+ // constant, only visit the reachable successor.
+ TerminatorInst *TI = BB->getTerminator();
+ if (BranchInst *BI = dyn_cast<BranchInst>(TI)) {
+ if (BI->isConditional() && isa<ConstantInt>(BI->getCondition())) {
+ bool CondVal = cast<ConstantInt>(BI->getCondition())->getZExtValue();
+ Worklist.push_back(BI->getSuccessor(!CondVal));
+ continue;
+ }
+ } else if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) {
+ if (ConstantInt *Cond = dyn_cast<ConstantInt>(SI->getCondition())) {
+ // See if this is an explicit destination.
+ for (unsigned i = 1, e = SI->getNumSuccessors(); i != e; ++i)
+ if (SI->getCaseValue(i) == Cond) {
+ Worklist.push_back(SI->getSuccessor(i));
+ continue;
+ }
+
+ // Otherwise it is the default destination.
+ Worklist.push_back(SI->getSuccessor(0));
+ continue;
+ }
+ }
+
+ for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i)
+ Worklist.push_back(TI->getSuccessor(i));
+ }
+}
+
+bool InstCombiner::DoOneIteration(Function &F, unsigned Iteration) {
+ bool Changed = false;
+ TD = &getAnalysis<TargetData>();
+
+ DEBUG(DOUT << "\n\nINSTCOMBINE ITERATION #" << Iteration << " on "
+ << F.getNameStr() << "\n");
+
+ {
+ // Do a depth-first traversal of the function, populate the worklist with
+ // the reachable instructions. Ignore blocks that are not reachable. Keep
+ // track of which blocks we visit.
+ SmallPtrSet<BasicBlock*, 64> Visited;
+ AddReachableCodeToWorklist(F.begin(), Visited, *this, TD);
+
+ // Do a quick scan over the function. If we find any blocks that are
+ // unreachable, remove any instructions inside of them. This prevents
+ // the instcombine code from having to deal with some bad special cases.
+ for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
+ if (!Visited.count(BB)) {
+ Instruction *Term = BB->getTerminator();
+ while (Term != BB->begin()) { // Remove instrs bottom-up
+ BasicBlock::iterator I = Term; --I;
+
+ DOUT << "IC: DCE: " << *I;
+ ++NumDeadInst;
+
+ if (!I->use_empty())
+ I->replaceAllUsesWith(UndefValue::get(I->getType()));
+ I->eraseFromParent();
+ }
+ }
+ }
+
+ while (!Worklist.empty()) {
+ Instruction *I = RemoveOneFromWorkList();
+ if (I == 0) continue; // skip null values.
+
+ // Check to see if we can DCE the instruction.
+ if (isInstructionTriviallyDead(I)) {
+ // Add operands to the worklist.
+ if (I->getNumOperands() < 4)
+ AddUsesToWorkList(*I);
+ ++NumDeadInst;
+
+ DOUT << "IC: DCE: " << *I;
+
+ I->eraseFromParent();
+ RemoveFromWorkList(I);
+ continue;
+ }
+
+ // Instruction isn't dead, see if we can constant propagate it.
+ if (Constant *C = ConstantFoldInstruction(I, TD)) {
+ DOUT << "IC: ConstFold to: " << *C << " from: " << *I;
+
+ // Add operands to the worklist.
+ AddUsesToWorkList(*I);
+ ReplaceInstUsesWith(*I, C);
+
+ ++NumConstProp;
+ I->eraseFromParent();
+ RemoveFromWorkList(I);
+ continue;
+ }
+
+ // See if we can trivially sink this instruction to a successor basic block.
+ if (I->hasOneUse()) {
+ BasicBlock *BB = I->getParent();
+ BasicBlock *UserParent = cast<Instruction>(I->use_back())->getParent();
+ if (UserParent != BB) {
+ bool UserIsSuccessor = false;
+ // See if the user is one of our successors.
+ for (succ_iterator SI = succ_begin(BB), E = succ_end(BB); SI != E; ++SI)
+ if (*SI == UserParent) {
+ UserIsSuccessor = true;
+ break;
+ }
+
+ // If the user is one of our immediate successors, and if that successor
+ // only has us as a predecessors (we'd have to split the critical edge
+ // otherwise), we can keep going.
+ if (UserIsSuccessor && !isa<PHINode>(I->use_back()) &&
+ next(pred_begin(UserParent)) == pred_end(UserParent))
+ // Okay, the CFG is simple enough, try to sink this instruction.
+ Changed |= TryToSinkInstruction(I, UserParent);
+ }
+ }
+
+ // Now that we have an instruction, try combining it to simplify it...
+#ifndef NDEBUG
+ std::string OrigI;
+#endif
+ DEBUG(std::ostringstream SS; I->print(SS); OrigI = SS.str(););
+ if (Instruction *Result = visit(*I)) {
+ ++NumCombined;
+ // Should we replace the old instruction with a new one?
+ if (Result != I) {
+ DOUT << "IC: Old = " << *I
+ << " New = " << *Result;
+
+ // Everything uses the new instruction now.
+ I->replaceAllUsesWith(Result);
+
+ // Push the new instruction and any users onto the worklist.
+ AddToWorkList(Result);
+ AddUsersToWorkList(*Result);
+
+ // Move the name to the new instruction first.
+ Result->takeName(I);
+
+ // Insert the new instruction into the basic block...
+ BasicBlock *InstParent = I->getParent();
+ BasicBlock::iterator InsertPos = I;
+
+ if (!isa<PHINode>(Result)) // If combining a PHI, don't insert
+ while (isa<PHINode>(InsertPos)) // middle of a block of PHIs.
+ ++InsertPos;
+
+ InstParent->getInstList().insert(InsertPos, Result);
+
+ // Make sure that we reprocess all operands now that we reduced their
+ // use counts.
+ AddUsesToWorkList(*I);
+
+ // Instructions can end up on the worklist more than once. Make sure
+ // we do not process an instruction that has been deleted.
+ RemoveFromWorkList(I);
+
+ // Erase the old instruction.
+ InstParent->getInstList().erase(I);
+ } else {
+#ifndef NDEBUG
+ DOUT << "IC: Mod = " << OrigI
+ << " New = " << *I;
+#endif
+
+ // If the instruction was modified, it's possible that it is now dead.
+ // if so, remove it.
+ if (isInstructionTriviallyDead(I)) {
+ // Make sure we process all operands now that we are reducing their
+ // use counts.
+ AddUsesToWorkList(*I);
+
+ // Instructions may end up in the worklist more than once. Erase all
+ // occurrences of this instruction.
+ RemoveFromWorkList(I);
+ I->eraseFromParent();
+ } else {
+ AddToWorkList(I);
+ AddUsersToWorkList(*I);
+ }
+ }
+ Changed = true;
+ }
+ }
+
+ assert(WorklistMap.empty() && "Worklist empty, but map not?");
+ return Changed;
+}
+
+
+bool InstCombiner::runOnFunction(Function &F) {
+ MustPreserveLCSSA = mustPreserveAnalysisID(LCSSAID);
+
+ bool EverMadeChange = false;
+
+ // Iterate while there is work to do.
+ unsigned Iteration = 0;
+ while (DoOneIteration(F, Iteration++))
+ EverMadeChange = true;
+ return EverMadeChange;
+}
+
+FunctionPass *llvm::createInstructionCombiningPass() {
+ return new InstCombiner();
+}
+