| //===- 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 int %X, 1 |
| // %Z = add int %Y, 1 |
| // into: |
| // %Z = add int %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. SetCC instructions are converted from <,>,<=,>= to ==,!= if possible |
| // 4. All SetCC 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/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/PatternMatch.h" |
| #include "llvm/ADT/DepthFirstIterator.h" |
| #include "llvm/ADT/Statistic.h" |
| #include "llvm/ADT/STLExtras.h" |
| #include <algorithm> |
| using namespace llvm; |
| using namespace llvm::PatternMatch; |
| |
| namespace { |
| Statistic<> NumCombined ("instcombine", "Number of insts combined"); |
| Statistic<> NumConstProp("instcombine", "Number of constant folds"); |
| Statistic<> NumDeadInst ("instcombine", "Number of dead inst eliminated"); |
| Statistic<> NumSunkInst ("instcombine", "Number of instructions sunk"); |
| |
| class InstCombiner : public FunctionPass, |
| public InstVisitor<InstCombiner, Instruction*> { |
| // Worklist of all of the instructions that need to be simplified. |
| std::vector<Instruction*> WorkList; |
| TargetData *TD; |
| |
| /// 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(Instruction &I) { |
| for (Value::use_iterator UI = I.use_begin(), UE = I.use_end(); |
| UI != UE; ++UI) |
| WorkList.push_back(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))) |
| WorkList.push_back(Op); |
| } |
| |
| // removeFromWorkList - remove all instances of I from the worklist. |
| void removeFromWorkList(Instruction *I); |
| public: |
| virtual bool runOnFunction(Function &F); |
| |
| virtual void getAnalysisUsage(AnalysisUsage &AU) const { |
| AU.addRequired<TargetData>(); |
| 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 *visitDiv(BinaryOperator &I); |
| Instruction *visitRem(BinaryOperator &I); |
| Instruction *visitAnd(BinaryOperator &I); |
| Instruction *visitOr (BinaryOperator &I); |
| Instruction *visitXor(BinaryOperator &I); |
| Instruction *visitSetCondInst(SetCondInst &I); |
| Instruction *visitSetCondInstWithCastAndCast(SetCondInst &SCI); |
| |
| Instruction *FoldGEPSetCC(User *GEPLHS, Value *RHS, |
| Instruction::BinaryOps Cond, Instruction &I); |
| Instruction *visitShiftInst(ShiftInst &I); |
| Instruction *visitCastInst(CastInst &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); |
| |
| // 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 |
| WorkList.push_back(New); // Add to worklist |
| 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(Value *V, const Type *Ty, Instruction &Pos) { |
| if (V->getType() == Ty) return V; |
| |
| Instruction *C = new CastInst(V, Ty, V->getName(), &Pos); |
| WorkList.push_back(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; |
| } |
| } |
| |
| // 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(Value *V, const Type *DestTy, |
| Instruction *InsertBefore); |
| |
| // SimplifyCommutative - This performs a few simplifications for commutative |
| // operators. |
| bool SimplifyCommutative(BinaryOperator &I); |
| |
| |
| // 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 *OptAndOp(Instruction *Op, ConstantIntegral *OpRHS, |
| ConstantIntegral *AndRHS, BinaryOperator &TheAnd); |
| |
| Instruction *InsertRangeTest(Value *V, Constant *Lo, Constant *Hi, |
| bool Inside, Instruction &IB); |
| }; |
| |
| RegisterOpt<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) { |
| switch (Ty->getTypeID()) { |
| case Type::SByteTyID: |
| case Type::ShortTyID: return Type::IntTy; |
| case Type::UByteTyID: |
| case Type::UShortTyID: return Type::UIntTy; |
| case Type::FloatTyID: return Type::DoubleTy; |
| default: return Ty; |
| } |
| } |
| |
| // 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); |
| WorkList.push_back(New); |
| I.setOperand(0, New); |
| I.setOperand(1, Folded); |
| return true; |
| } |
| } |
| return Changed; |
| } |
| |
| // 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 (ConstantIntegral *C = dyn_cast<ConstantIntegral>(V)) |
| return ConstantExpr::getNot(C); |
| 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. |
| Constant *One = ConstantInt::get(V->getType(), 1); |
| CST = cast<ConstantInt>(ConstantExpr::getShl(One, CST)); |
| 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; |
| } |
| |
| // Log2 - Calculate the log base 2 for the specified value if it is exactly a |
| // power of 2. |
| static unsigned Log2(uint64_t Val) { |
| assert(Val > 1 && "Values 0 and 1 should be handled elsewhere!"); |
| unsigned Count = 0; |
| while (Val != 1) { |
| if (Val & 1) return 0; // Multiple bits set? |
| Val >>= 1; |
| ++Count; |
| } |
| return Count; |
| } |
| |
| // AddOne, SubOne - Add or subtract a constant one from an integer constant... |
| static ConstantInt *AddOne(ConstantInt *C) { |
| return cast<ConstantInt>(ConstantExpr::getAdd(C, |
| ConstantInt::get(C->getType(), 1))); |
| } |
| static ConstantInt *SubOne(ConstantInt *C) { |
| return cast<ConstantInt>(ConstantExpr::getSub(C, |
| ConstantInt::get(C->getType(), 1))); |
| } |
| |
| // isTrueWhenEqual - Return true if the specified setcondinst instruction is |
| // true when both operands are equal... |
| // |
| static bool isTrueWhenEqual(Instruction &I) { |
| return I.getOpcode() == Instruction::SetEQ || |
| I.getOpcode() == Instruction::SetGE || |
| I.getOpcode() == Instruction::SetLE; |
| } |
| |
| /// 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 new ShiftInst(Instruction::Shl, Add.getOperand(0), |
| ConstantInt::get(Type::UByteTy, 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 (isa<CastInst>(I)) { |
| if (Constant *SOC = dyn_cast<Constant>(SO)) |
| return ConstantExpr::getCast(SOC, I.getType()); |
| |
| return IC->InsertNewInstBefore(new CastInst(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 (ShiftInst *SI = dyn_cast<ShiftInst>(&I)) |
| New = new ShiftInst(SI->getOpcode(), Op0, Op1, SO->getName()+".sh"); |
| 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::BoolTy) 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 || |
| !isa<Constant>(PN->getIncomingValue(0))) return 0; |
| |
| // Check to see if all of the operands of the PHI are constants. If not, we |
| // cannot do the transformation. |
| for (unsigned i = 1; i != NumPHIValues; ++i) |
| if (!isa<Constant>(PN->getIncomingValue(i))) |
| return 0; |
| |
| // Okay, we can do the transformation: create the new PHI node. |
| PHINode *NewPN = new PHINode(I.getType(), I.getName()); |
| I.setName(""); |
| NewPN->reserveOperandSpace(PN->getNumOperands()/2); |
| InsertNewInstBefore(NewPN, *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) { |
| Constant *InV = cast<Constant>(PN->getIncomingValue(i)); |
| NewPN->addIncoming(ConstantExpr::get(I.getOpcode(), InV, C), |
| PN->getIncomingBlock(i)); |
| } |
| } else { |
| assert(isa<CastInst>(I) && "Unary op should be a cast!"); |
| const Type *RetTy = I.getType(); |
| for (unsigned i = 0; i != NumPHIValues; ++i) { |
| Constant *InV = cast<Constant>(PN->getIncomingValue(i)); |
| NewPN->addIncoming(ConstantExpr::getCast(InV, RetTy), |
| 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()->isFloatingPoint() && // -0 + +0 = +0, so it's not a noop |
| RHSC->isNullValue()) |
| return ReplaceInstUsesWith(I, LHS); |
| |
| // X + (signbit) --> X ^ signbit |
| if (ConstantInt *CI = dyn_cast<ConstantInt>(RHSC)) { |
| unsigned NumBits = CI->getType()->getPrimitiveSizeInBits(); |
| uint64_t Val = CI->getRawValue() & (1ULL << NumBits)-1; |
| if (Val == (1ULL << (NumBits-1))) |
| return BinaryOperator::createXor(LHS, RHS); |
| } |
| |
| if (isa<PHINode>(LHS)) |
| if (Instruction *NV = FoldOpIntoPhi(I)) |
| return NV; |
| } |
| |
| // X + X --> X << 1 |
| if (I.getType()->isInteger()) { |
| 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, ConstantExpr::getAdd(C1, C2)); |
| } |
| |
| // X + X*C --> X * (C+1) |
| if (dyn_castFoldableMul(RHS, C2) == LHS) |
| return BinaryOperator::createMul(LHS, AddOne(C2)); |
| |
| |
| // (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; |
| if (match(LHS, m_Not(m_Value(X)))) { // ~X + C --> (C-1) - X |
| Constant *C= ConstantExpr::getSub(CRHS, ConstantInt::get(I.getType(), 1)); |
| return BinaryOperator::createSub(C, X); |
| } |
| |
| // (X & FF00) + xx00 -> (X+xx00) & FF00 |
| if (LHS->hasOneUse() && match(LHS, m_And(m_Value(X), m_ConstantInt(C2)))) { |
| Constant *Anded = ConstantExpr::getAnd(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. |
| uint64_t AddRHSV = CRHS->getRawValue(); |
| |
| // Form a mask of all bits from the lowest bit added through the top. |
| uint64_t AddRHSHighBits = ~((AddRHSV & -AddRHSV)-1); |
| AddRHSHighBits &= ~0ULL >> (64-C2->getType()->getPrimitiveSizeInBits()); |
| |
| // See if the and mask includes all of these bits. |
| uint64_t AddRHSHighBitsAnd = AddRHSHighBits & C2->getRawValue(); |
| |
| 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; |
| } |
| |
| 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) { |
| unsigned NumBits = CI->getType()->getPrimitiveSizeInBits(); |
| return (CI->getRawValue() & (~0ULL >> (64-NumBits))) == (1ULL << (NumBits-1)); |
| } |
| |
| /// RemoveNoopCast - Strip off nonconverting casts from the value. |
| /// |
| static Value *RemoveNoopCast(Value *V) { |
| if (CastInst *CI = dyn_cast<CastInst>(V)) { |
| const Type *CTy = CI->getType(); |
| const Type *OpTy = CI->getOperand(0)->getType(); |
| if (CTy->isInteger() && OpTy->isInteger()) { |
| if (CTy->getPrimitiveSizeInBits() == OpTy->getPrimitiveSizeInBits()) |
| return RemoveNoopCast(CI->getOperand(0)); |
| } else if (isa<PointerType>(CTy) && isa<PointerType>(OpTy)) |
| return RemoveNoopCast(CI->getOperand(0)); |
| } |
| return V; |
| } |
| |
| 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, |
| ConstantExpr::getAdd(C, ConstantInt::get(I.getType(), 1))); |
| // -((uint)X >> 31) -> ((int)X >> 31) |
| // -((int)X >> 31) -> ((uint)X >> 31) |
| if (C->isNullValue()) { |
| Value *NoopCastedRHS = RemoveNoopCast(Op1); |
| if (ShiftInst *SI = dyn_cast<ShiftInst>(NoopCastedRHS)) |
| if (SI->getOpcode() == Instruction::Shr) |
| if (ConstantUInt *CU = dyn_cast<ConstantUInt>(SI->getOperand(1))) { |
| const Type *NewTy; |
| if (SI->getType()->isSigned()) |
| NewTy = SI->getType()->getUnsignedVersion(); |
| else |
| NewTy = SI->getType()->getSignedVersion(); |
| // Check to see if we are shifting out everything but the sign bit. |
| if (CU->getValue() == SI->getType()->getPrimitiveSizeInBits()-1) { |
| // Ok, the transformation is safe. Insert a cast of the incoming |
| // value, then the new shift, then the new cast. |
| Instruction *FirstCast = new CastInst(SI->getOperand(0), NewTy, |
| SI->getOperand(0)->getName()); |
| Value *InV = InsertNewInstBefore(FirstCast, I); |
| Instruction *NewShift = new ShiftInst(Instruction::Shr, FirstCast, |
| CU, SI->getName()); |
| if (NewShift->getType() == I.getType()) |
| return NewShift; |
| else { |
| InV = InsertNewInstBefore(NewShift, I); |
| return new CastInst(NewShift, I.getType()); |
| } |
| } |
| } |
| } |
| |
| // 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()->isFloatingPoint()) { |
| 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(ConstantExpr::getSub(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()->isFloatingPoint()) { |
| // 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); |
| } |
| |
| // -(X sdiv C) -> (X sdiv -C) |
| if (Op1I->getOpcode() == Instruction::Div) |
| if (ConstantSInt *CSI = dyn_cast<ConstantSInt>(Op0)) |
| if (CSI->isNullValue()) |
| if (Constant *DivRHS = dyn_cast<Constant>(Op1I->getOperand(1))) |
| return BinaryOperator::createDiv(Op1I->getOperand(0), |
| ConstantExpr::getNeg(DivRHS)); |
| |
| // X - X*C --> X * (1-C) |
| ConstantInt *C2 = 0; |
| if (dyn_castFoldableMul(Op1I, C2) == Op0) { |
| Constant *CP1 = |
| ConstantExpr::getSub(ConstantInt::get(I.getType(), 1), C2); |
| return BinaryOperator::createMul(Op0, CP1); |
| } |
| } |
| } |
| |
| if (!Op0->getType()->isFloatingPoint()) |
| 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) |
| Constant *CP1 = ConstantExpr::getSub(C1, ConstantInt::get(I.getType(),1)); |
| return BinaryOperator::createMul(Op1, CP1); |
| } |
| |
| ConstantInt *C2; // X*C1 - X*C2 -> X * (C1-C2) |
| if (X == dyn_castFoldableMul(Op1, C2)) |
| return BinaryOperator::createMul(Op1, ConstantExpr::getSub(C1, C2)); |
| } |
| return 0; |
| } |
| |
| /// isSignBitCheck - Given an exploded setcc instruction, return true if it is |
| /// really just returns true if the most significant (sign) bit is set. |
| static bool isSignBitCheck(unsigned Opcode, Value *LHS, ConstantInt *RHS) { |
| if (RHS->getType()->isSigned()) { |
| // True if source is LHS < 0 or LHS <= -1 |
| return Opcode == Instruction::SetLT && RHS->isNullValue() || |
| Opcode == Instruction::SetLE && RHS->isAllOnesValue(); |
| } else { |
| ConstantUInt *RHSC = cast<ConstantUInt>(RHS); |
| // True if source is LHS > 127 or LHS >= 128, where the constants depend on |
| // the size of the integer type. |
| if (Opcode == Instruction::SetGE) |
| return RHSC->getValue() == |
| 1ULL << (RHS->getType()->getPrimitiveSizeInBits()-1); |
| if (Opcode == Instruction::SetGT) |
| return RHSC->getValue() == |
| (1ULL << (RHS->getType()->getPrimitiveSizeInBits()-1))-1; |
| } |
| 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 (ShiftInst *SI = dyn_cast<ShiftInst>(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->isNullValue()) |
| 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()); |
| |
| int64_t Val = (int64_t)cast<ConstantInt>(CI)->getRawValue(); |
| if (uint64_t C = Log2(Val)) // Replace X*(2^C) with X << C |
| return new ShiftInst(Instruction::Shl, Op0, |
| ConstantUInt::get(Type::UByteTy, C)); |
| } 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' |
| } |
| |
| // 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 (CastInst *CI = dyn_cast<CastInst>(I.getOperand(0))) |
| if (CI->getOperand(0)->getType() == Type::BoolTy) |
| BoolCast = CI; |
| if (!BoolCast) |
| if (CastInst *CI = dyn_cast<CastInst>(I.getOperand(1))) |
| if (CI->getOperand(0)->getType() == Type::BoolTy) |
| BoolCast = CI; |
| if (BoolCast) { |
| if (SetCondInst *SCI = dyn_cast<SetCondInst>(BoolCast->getOperand(0))) { |
| Value *SCIOp0 = SCI->getOperand(0), *SCIOp1 = SCI->getOperand(1); |
| const Type *SCOpTy = SCIOp0->getType(); |
| |
| // If the setcc 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->getOpcode(), SCIOp0, cast<ConstantInt>(SCIOp1))) { |
| // Shift the X value right to turn it into "all signbits". |
| Constant *Amt = ConstantUInt::get(Type::UByteTy, |
| SCOpTy->getPrimitiveSizeInBits()-1); |
| if (SCIOp0->getType()->isUnsigned()) { |
| const Type *NewTy = SCIOp0->getType()->getSignedVersion(); |
| SCIOp0 = InsertNewInstBefore(new CastInst(SCIOp0, NewTy, |
| SCIOp0->getName()), I); |
| } |
| |
| Value *V = |
| InsertNewInstBefore(new ShiftInst(Instruction::Shr, 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()) |
| V = InsertNewInstBefore(new CastInst(V, I.getType(), V->getName()),I); |
| |
| Value *OtherOp = Op0 == BoolCast ? I.getOperand(1) : Op0; |
| return BinaryOperator::createAnd(V, OtherOp); |
| } |
| } |
| } |
| |
| return Changed ? &I : 0; |
| } |
| |
| Instruction *InstCombiner::visitDiv(BinaryOperator &I) { |
| Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); |
| |
| 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 |
| |
| if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) { |
| // div X, 1 == X |
| if (RHS->equalsInt(1)) |
| return ReplaceInstUsesWith(I, Op0); |
| |
| // div X, -1 == -X |
| if (RHS->isAllOnesValue()) |
| return BinaryOperator::createNeg(Op0); |
| |
| if (Instruction *LHS = dyn_cast<Instruction>(Op0)) |
| if (LHS->getOpcode() == Instruction::Div) |
| if (ConstantInt *LHSRHS = dyn_cast<ConstantInt>(LHS->getOperand(1))) { |
| // (X / C1) / C2 -> X / (C1*C2) |
| return BinaryOperator::createDiv(LHS->getOperand(0), |
| ConstantExpr::getMul(RHS, LHSRHS)); |
| } |
| |
| // Check to see if this is an unsigned division with an exact power of 2, |
| // if so, convert to a right shift. |
| if (ConstantUInt *C = dyn_cast<ConstantUInt>(RHS)) |
| if (uint64_t Val = C->getValue()) // Don't break X / 0 |
| if (uint64_t C = Log2(Val)) |
| return new ShiftInst(Instruction::Shr, Op0, |
| ConstantUInt::get(Type::UByteTy, C)); |
| |
| // -X/C -> X/-C |
| if (RHS->getType()->isSigned()) |
| if (Value *LHSNeg = dyn_castNegVal(Op0)) |
| return BinaryOperator::createDiv(LHSNeg, ConstantExpr::getNeg(RHS)); |
| |
| if (!RHS->isNullValue()) { |
| 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 this is 'udiv X, (Cond ? C1, C2)' where C1&C2 are powers of two, |
| // transform this into: '(Cond ? (udiv X, C1) : (udiv X, C2))'. |
| if (SelectInst *SI = dyn_cast<SelectInst>(Op1)) |
| if (ConstantUInt *STO = dyn_cast<ConstantUInt>(SI->getOperand(1))) |
| if (ConstantUInt *SFO = dyn_cast<ConstantUInt>(SI->getOperand(2))) { |
| if (STO->getValue() == 0) { // Couldn't be this argument. |
| I.setOperand(1, SFO); |
| return &I; |
| } else if (SFO->getValue() == 0) { |
| I.setOperand(1, STO); |
| return &I; |
| } |
| |
| uint64_t TVA = STO->getValue(), FVA = SFO->getValue(); |
| unsigned TSA = 0, FSA = 0; |
| if ((TVA == 1 || (TSA = Log2(TVA))) && // Log2 fails for 0 & 1. |
| (FVA == 1 || (FSA = Log2(FVA)))) { |
| Constant *TC = ConstantUInt::get(Type::UByteTy, TSA); |
| Instruction *TSI = new ShiftInst(Instruction::Shr, Op0, |
| TC, SI->getName()+".t"); |
| TSI = InsertNewInstBefore(TSI, I); |
| |
| Constant *FC = ConstantUInt::get(Type::UByteTy, FSA); |
| Instruction *FSI = new ShiftInst(Instruction::Shr, Op0, |
| FC, SI->getName()+".f"); |
| FSI = InsertNewInstBefore(FSI, I); |
| return new SelectInst(SI->getOperand(0), TSI, FSI); |
| } |
| } |
| |
| // 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::visitRem(BinaryOperator &I) { |
| Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); |
| if (I.getType()->isSigned()) |
| if (Value *RHSNeg = dyn_castNegVal(Op1)) |
| if (!isa<ConstantSInt>(RHSNeg) || |
| cast<ConstantSInt>(RHSNeg)->getValue() > 0) { |
| // X % -Y -> X % Y |
| AddUsesToWorkList(I); |
| I.setOperand(1, RHSNeg); |
| return &I; |
| } |
| |
| 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 |
| |
| if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) { |
| if (RHS->equalsInt(1)) // X % 1 == 0 |
| return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType())); |
| |
| // Check to see if this is an unsigned remainder with an exact power of 2, |
| // if so, convert to a bitwise and. |
| if (ConstantUInt *C = dyn_cast<ConstantUInt>(RHS)) |
| if (uint64_t Val = C->getValue()) // Don't break X % 0 (divide by zero) |
| if (!(Val & (Val-1))) // Power of 2 |
| return BinaryOperator::createAnd(Op0, |
| ConstantUInt::get(I.getType(), Val-1)); |
| |
| if (!RHS->isNullValue()) { |
| 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 this is 'urem X, (Cond ? C1, C2)' where C1&C2 are powers of two, |
| // transform this into: '(Cond ? (urem X, C1) : (urem X, C2))'. |
| if (SelectInst *SI = dyn_cast<SelectInst>(Op1)) |
| if (ConstantUInt *STO = dyn_cast<ConstantUInt>(SI->getOperand(1))) |
| if (ConstantUInt *SFO = dyn_cast<ConstantUInt>(SI->getOperand(2))) { |
| if (STO->getValue() == 0) { // Couldn't be this argument. |
| I.setOperand(1, SFO); |
| return &I; |
| } else if (SFO->getValue() == 0) { |
| I.setOperand(1, STO); |
| return &I; |
| } |
| |
| if (!(STO->getValue() & (STO->getValue()-1)) && |
| !(SFO->getValue() & (SFO->getValue()-1))) { |
| 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); |
| } |
| } |
| |
| // 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; |
| } |
| |
| // isMaxValueMinusOne - return true if this is Max-1 |
| static bool isMaxValueMinusOne(const ConstantInt *C) { |
| if (const ConstantUInt *CU = dyn_cast<ConstantUInt>(C)) { |
| // Calculate -1 casted to the right type... |
| unsigned TypeBits = C->getType()->getPrimitiveSizeInBits(); |
| uint64_t Val = ~0ULL; // All ones |
| Val >>= 64-TypeBits; // Shift out unwanted 1 bits... |
| return CU->getValue() == Val-1; |
| } |
| |
| const ConstantSInt *CS = cast<ConstantSInt>(C); |
| |
| // Calculate 0111111111..11111 |
| unsigned TypeBits = C->getType()->getPrimitiveSizeInBits(); |
| int64_t Val = INT64_MAX; // All ones |
| Val >>= 64-TypeBits; // Shift out unwanted 1 bits... |
| return CS->getValue() == Val-1; |
| } |
| |
| // isMinValuePlusOne - return true if this is Min+1 |
| static bool isMinValuePlusOne(const ConstantInt *C) { |
| if (const ConstantUInt *CU = dyn_cast<ConstantUInt>(C)) |
| return CU->getValue() == 1; |
| |
| const ConstantSInt *CS = cast<ConstantSInt>(C); |
| |
| // Calculate 1111111111000000000000 |
| unsigned TypeBits = C->getType()->getPrimitiveSizeInBits(); |
| int64_t Val = -1; // All ones |
| Val <<= TypeBits-1; // Shift over to the right spot |
| return CS->getValue() == Val+1; |
| } |
| |
| // isOneBitSet - Return true if there is exactly one bit set in the specified |
| // constant. |
| static bool isOneBitSet(const ConstantInt *CI) { |
| uint64_t V = CI->getRawValue(); |
| return V && (V & (V-1)) == 0; |
| } |
| |
| #if 0 // Currently unused |
| // isLowOnes - Return true if the constant is of the form 0+1+. |
| static bool isLowOnes(const ConstantInt *CI) { |
| uint64_t V = CI->getRawValue(); |
| |
| // There won't be bits set in parts that the type doesn't contain. |
| V &= ConstantInt::getAllOnesValue(CI->getType())->getRawValue(); |
| |
| uint64_t U = V+1; // If it is low ones, this should be a power of two. |
| return U && V && (U & V) == 0; |
| } |
| #endif |
| |
| // 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) { |
| uint64_t V = ~CI->getRawValue(); |
| |
| // There won't be bits set in parts that the type doesn't contain. |
| V &= ConstantInt::getAllOnesValue(CI->getType())->getRawValue(); |
| |
| uint64_t U = V+1; // If it is low ones, this should be a power of two. |
| return U && V && (U & V) == 0; |
| } |
| |
| |
| /// getSetCondCode - Encode a setcc opcode into a three bit mask. These bits |
| /// are carefully arranged to allow folding of expressions such as: |
| /// |
| /// (A < B) | (A > B) --> (A != B) |
| /// |
| /// Bit value '4' represents that the comparison is true if A > B, bit value '2' |
| /// represents that the comparison is true if A == B, and bit value '1' is true |
| /// if A < B. |
| /// |
| static unsigned getSetCondCode(const SetCondInst *SCI) { |
| switch (SCI->getOpcode()) { |
| // False -> 0 |
| case Instruction::SetGT: return 1; |
| case Instruction::SetEQ: return 2; |
| case Instruction::SetGE: return 3; |
| case Instruction::SetLT: return 4; |
| case Instruction::SetNE: return 5; |
| case Instruction::SetLE: return 6; |
| // True -> 7 |
| default: |
| assert(0 && "Invalid SetCC opcode!"); |
| return 0; |
| } |
| } |
| |
| /// getSetCCValue - This is the complement of getSetCondCode, which turns an |
| /// opcode and two operands into either a constant true or false, or a brand new |
| /// SetCC instruction. |
| static Value *getSetCCValue(unsigned Opcode, Value *LHS, Value *RHS) { |
| switch (Opcode) { |
| case 0: return ConstantBool::False; |
| case 1: return new SetCondInst(Instruction::SetGT, LHS, RHS); |
| case 2: return new SetCondInst(Instruction::SetEQ, LHS, RHS); |
| case 3: return new SetCondInst(Instruction::SetGE, LHS, RHS); |
| case 4: return new SetCondInst(Instruction::SetLT, LHS, RHS); |
| case 5: return new SetCondInst(Instruction::SetNE, LHS, RHS); |
| case 6: return new SetCondInst(Instruction::SetLE, LHS, RHS); |
| case 7: return ConstantBool::True; |
| default: assert(0 && "Illegal SetCCCode!"); return 0; |
| } |
| } |
| |
| // FoldSetCCLogical - Implements (setcc1 A, B) & (setcc2 A, B) --> (setcc3 A, B) |
| struct FoldSetCCLogical { |
| InstCombiner &IC; |
| Value *LHS, *RHS; |
| FoldSetCCLogical(InstCombiner &ic, SetCondInst *SCI) |
| : IC(ic), LHS(SCI->getOperand(0)), RHS(SCI->getOperand(1)) {} |
| bool shouldApply(Value *V) const { |
| if (SetCondInst *SCI = dyn_cast<SetCondInst>(V)) |
| return (SCI->getOperand(0) == LHS && SCI->getOperand(1) == RHS || |
| SCI->getOperand(0) == RHS && SCI->getOperand(1) == LHS); |
| return false; |
| } |
| Instruction *apply(BinaryOperator &Log) const { |
| SetCondInst *SCI = cast<SetCondInst>(Log.getOperand(0)); |
| if (SCI->getOperand(0) != LHS) { |
| assert(SCI->getOperand(1) == LHS); |
| SCI->swapOperands(); // Swap the LHS and RHS of the SetCC |
| } |
| |
| unsigned LHSCode = getSetCondCode(SCI); |
| unsigned RHSCode = getSetCondCode(cast<SetCondInst>(Log.getOperand(1))); |
| 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; |
| } |
| |
| Value *RV = getSetCCValue(Code, LHS, RHS); |
| if (Instruction *I = dyn_cast<Instruction>(RV)) |
| return I; |
| // Otherwise, it's a constant boolean value... |
| return IC.ReplaceInstUsesWith(Log, RV); |
| } |
| }; |
| |
| |
| /// MaskedValueIsZero - Return true if 'V & Mask' is known to be zero. We use |
| /// this predicate to simplify operations downstream. V and Mask are known to |
| /// be the same type. |
| static bool MaskedValueIsZero(Value *V, ConstantIntegral *Mask) { |
| // 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 |
| // to to 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. |
| if (Mask->isNullValue()) |
| return true; |
| if (ConstantIntegral *CI = dyn_cast<ConstantIntegral>(V)) |
| return ConstantExpr::getAnd(CI, Mask)->isNullValue(); |
| |
| if (Instruction *I = dyn_cast<Instruction>(V)) { |
| switch (I->getOpcode()) { |
| case Instruction::And: |
| // (X & C1) & C2 == 0 iff C1 & C2 == 0. |
| if (ConstantIntegral *CI = dyn_cast<ConstantIntegral>(I->getOperand(1))) |
| if (ConstantExpr::getAnd(CI, Mask)->isNullValue()) |
| return true; |
| break; |
| case Instruction::Or: |
| // If the LHS and the RHS are MaskedValueIsZero, the result is also zero. |
| return MaskedValueIsZero(I->getOperand(1), Mask) && |
| MaskedValueIsZero(I->getOperand(0), Mask); |
| case Instruction::Select: |
| // If the T and F values are MaskedValueIsZero, the result is also zero. |
| return MaskedValueIsZero(I->getOperand(2), Mask) && |
| MaskedValueIsZero(I->getOperand(1), Mask); |
| case Instruction::Cast: { |
| const Type *SrcTy = I->getOperand(0)->getType(); |
| if (SrcTy == Type::BoolTy) |
| return (Mask->getRawValue() & 1) == 0; |
| |
| if (SrcTy->isInteger()) { |
| // (cast <ty> X to int) & C2 == 0 iff <ty> could not have contained C2. |
| if (SrcTy->isUnsigned() && // Only handle zero ext. |
| ConstantExpr::getCast(Mask, SrcTy)->isNullValue()) |
| return true; |
| |
| // If this is a noop cast, recurse. |
| if ((SrcTy->isSigned() && SrcTy->getUnsignedVersion() == I->getType())|| |
| SrcTy->getSignedVersion() == I->getType()) { |
| Constant *NewMask = |
| ConstantExpr::getCast(Mask, I->getOperand(0)->getType()); |
| return MaskedValueIsZero(I->getOperand(0), |
| cast<ConstantIntegral>(NewMask)); |
| } |
| } |
| break; |
| } |
| case Instruction::Shl: |
| // (shl X, C1) & C2 == 0 iff (X & C2 >>u C1) == 0 |
| if (ConstantUInt *SA = dyn_cast<ConstantUInt>(I->getOperand(1))) |
| return MaskedValueIsZero(I->getOperand(0), |
| cast<ConstantIntegral>(ConstantExpr::getUShr(Mask, SA))); |
| break; |
| case Instruction::Shr: |
| // (ushr X, C1) & C2 == 0 iff (-1 >> C1) & C2 == 0 |
| if (ConstantUInt *SA = dyn_cast<ConstantUInt>(I->getOperand(1))) |
| if (I->getType()->isUnsigned()) { |
| Constant *C1 = ConstantIntegral::getAllOnesValue(I->getType()); |
| C1 = ConstantExpr::getShr(C1, SA); |
| C1 = ConstantExpr::getAnd(C1, Mask); |
| if (C1->isNullValue()) |
| return true; |
| } |
| break; |
| } |
| } |
| |
| return false; |
| } |
| |
| // 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 either a shift instruction or a binary operator. |
| Instruction *InstCombiner::OptAndOp(Instruction *Op, |
| ConstantIntegral *OpRHS, |
| ConstantIntegral *AndRHS, |
| BinaryOperator &TheAnd) { |
| Value *X = Op->getOperand(0); |
| Constant *Together = 0; |
| if (!isa<ShiftInst>(Op)) |
| Together = ConstantExpr::getAnd(AndRHS, OpRHS); |
| |
| switch (Op->getOpcode()) { |
| case Instruction::Xor: |
| if (Op->hasOneUse()) { |
| // (X ^ C1) & C2 --> (X & C2) ^ (C1&C2) |
| std::string OpName = Op->getName(); Op->setName(""); |
| Instruction *And = BinaryOperator::createAnd(X, AndRHS, OpName); |
| InsertNewInstBefore(And, TheAnd); |
| 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 |
| std::string Op0Name = Op->getName(); Op->setName(""); |
| Instruction *Or = BinaryOperator::createOr(X, Together, Op0Name); |
| InsertNewInstBefore(Or, TheAnd); |
| 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. |
| uint64_t AndRHSV = cast<ConstantInt>(AndRHS)->getRawValue(); |
| |
| // Clear bits that are not part of the constant. |
| AndRHSV &= ~0ULL >> (64-AndRHS->getType()->getPrimitiveSizeInBits()); |
| |
| // 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. |
| uint64_t AddRHS = cast<ConstantInt>(OpRHS)->getRawValue(); |
| |
| // 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 { |
| std::string Name = Op->getName(); Op->setName(""); |
| // Pull the XOR out of the AND. |
| Instruction *NewAnd = BinaryOperator::createAnd(X, AndRHS, Name); |
| InsertNewInstBefore(NewAnd, TheAnd); |
| 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! |
| // |
| Constant *AllOne = ConstantIntegral::getAllOnesValue(AndRHS->getType()); |
| Constant *ShlMask = ConstantExpr::getShl(AllOne, OpRHS); |
| Constant *CI = ConstantExpr::getAnd(AndRHS, ShlMask); |
| |
| if (CI == 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::Shr: |
| // 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! |
| // |
| if (AndRHS->getType()->isUnsigned()) { |
| Constant *AllOne = ConstantIntegral::getAllOnesValue(AndRHS->getType()); |
| Constant *ShrMask = ConstantExpr::getShr(AllOne, OpRHS); |
| Constant *CI = ConstantExpr::getAnd(AndRHS, ShrMask); |
| |
| if (CI == 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; |
| } |
| } else { // Signed shr. |
| // See if this is shifting in some sign extension, then masking it out |
| // with an and. |
| if (Op->hasOneUse()) { |
| Constant *AllOne = ConstantIntegral::getAllOnesValue(AndRHS->getType()); |
| Constant *ShrMask = ConstantExpr::getUShr(AllOne, OpRHS); |
| Constant *CI = ConstantExpr::getAnd(AndRHS, ShrMask); |
| if (CI == AndRHS) { // Masking out bits shifted in. |
| // Make the argument unsigned. |
| Value *ShVal = Op->getOperand(0); |
| ShVal = InsertCastBefore(ShVal, |
| ShVal->getType()->getUnsignedVersion(), |
| TheAnd); |
| ShVal = InsertNewInstBefore(new ShiftInst(Instruction::Shr, ShVal, |
| OpRHS, Op->getName()), |
| TheAnd); |
| Value *AndRHS2 = ConstantExpr::getCast(AndRHS, ShVal->getType()); |
| ShVal = InsertNewInstBefore(BinaryOperator::createAnd(ShVal, AndRHS2, |
| TheAnd.getName()), |
| TheAnd); |
| return new CastInst(ShVal, Op->getType()); |
| } |
| } |
| } |
| 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. IB is the location to |
| /// insert new instructions. |
| Instruction *InstCombiner::InsertRangeTest(Value *V, Constant *Lo, Constant *Hi, |
| bool Inside, Instruction &IB) { |
| assert(cast<ConstantBool>(ConstantExpr::getSetLE(Lo, Hi))->getValue() && |
| "Lo is not <= Hi in range emission code!"); |
| if (Inside) { |
| if (Lo == Hi) // Trivially false. |
| return new SetCondInst(Instruction::SetNE, V, V); |
| if (cast<ConstantIntegral>(Lo)->isMinValue()) |
| return new SetCondInst(Instruction::SetLT, V, Hi); |
| |
| Constant *AddCST = ConstantExpr::getNeg(Lo); |
| Instruction *Add = BinaryOperator::createAdd(V, AddCST,V->getName()+".off"); |
| InsertNewInstBefore(Add, IB); |
| // Convert to unsigned for the comparison. |
| const Type *UnsType = Add->getType()->getUnsignedVersion(); |
| Value *OffsetVal = InsertCastBefore(Add, UnsType, IB); |
| AddCST = ConstantExpr::getAdd(AddCST, Hi); |
| AddCST = ConstantExpr::getCast(AddCST, UnsType); |
| return new SetCondInst(Instruction::SetLT, OffsetVal, AddCST); |
| } |
| |
| if (Lo == Hi) // Trivially true. |
| return new SetCondInst(Instruction::SetEQ, V, V); |
| |
| Hi = SubOne(cast<ConstantInt>(Hi)); |
| if (cast<ConstantIntegral>(Lo)->isMinValue()) // V < 0 || V >= Hi ->'V > Hi-1' |
| return new SetCondInst(Instruction::SetGT, V, Hi); |
| |
| // Emit X-Lo > Hi-Lo-1 |
| Constant *AddCST = ConstantExpr::getNeg(Lo); |
| Instruction *Add = BinaryOperator::createAdd(V, AddCST, V->getName()+".off"); |
| InsertNewInstBefore(Add, IB); |
| // Convert to unsigned for the comparison. |
| const Type *UnsType = Add->getType()->getUnsignedVersion(); |
| Value *OffsetVal = InsertCastBefore(Add, UnsType, IB); |
| AddCST = ConstantExpr::getAdd(AddCST, Hi); |
| AddCST = ConstantExpr::getCast(AddCST, UnsType); |
| return new SetCondInst(Instruction::SetGT, OffsetVal, AddCST); |
| } |
| |
| |
| 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); |
| |
| if (ConstantIntegral *AndRHS = dyn_cast<ConstantIntegral>(Op1)) { |
| // and X, -1 == X |
| if (AndRHS->isAllOnesValue()) |
| return ReplaceInstUsesWith(I, Op0); |
| |
| if (MaskedValueIsZero(Op0, AndRHS)) // LHS & RHS == 0 |
| return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType())); |
| |
| // If the mask is not masking out any bits, there is no reason to do the |
| // and in the first place. |
| ConstantIntegral *NotAndRHS = |
| cast<ConstantIntegral>(ConstantExpr::getNot(AndRHS)); |
| if (MaskedValueIsZero(Op0, NotAndRHS)) |
| return ReplaceInstUsesWith(I, Op0); |
| |
| // Optimize a variety of ((val OP C1) & C2) combinations... |
| if (isa<BinaryOperator>(Op0) || isa<ShiftInst>(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: |
| // (X ^ V) & C2 --> (X & C2) iff (V & C2) == 0 |
| // (X | V) & C2 --> (X & C2) iff (V & C2) == 0 |
| if (MaskedValueIsZero(Op0LHS, AndRHS)) |
| return BinaryOperator::createAnd(Op0RHS, AndRHS); |
| if (MaskedValueIsZero(Op0RHS, AndRHS)) |
| return BinaryOperator::createAnd(Op0LHS, AndRHS); |
| |
| // 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>(NotAndRHS) && |
| 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::And: |
| // (X & V) & C2 --> 0 iff (V & C2) == 0 |
| if (MaskedValueIsZero(Op0LHS, AndRHS) || |
| MaskedValueIsZero(Op0RHS, AndRHS)) |
| return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType())); |
| 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)) { |
| const Type *SrcTy = CI->getOperand(0)->getType(); |
| |
| // If this is an integer sign or zero extension instruction. |
| if (SrcTy->isIntegral() && |
| SrcTy->getPrimitiveSizeInBits() < |
| CI->getType()->getPrimitiveSizeInBits()) { |
| |
| if (SrcTy->isUnsigned()) { |
| // See if this and is clearing out bits that are known to be zero |
| // anyway (due to the zero extension). |
| Constant *Mask = ConstantIntegral::getAllOnesValue(SrcTy); |
| Mask = ConstantExpr::getZeroExtend(Mask, CI->getType()); |
| Constant *Result = ConstantExpr::getAnd(Mask, AndRHS); |
| if (Result == Mask) // The "and" isn't doing anything, remove it. |
| return ReplaceInstUsesWith(I, CI); |
| if (Result != AndRHS) { // Reduce the and RHS constant. |
| I.setOperand(1, Result); |
| return &I; |
| } |
| |
| } else { |
| if (CI->hasOneUse() && SrcTy->isInteger()) { |
| // We can only do this if all of the sign bits brought in are masked |
| // out. Compute this by first getting 0000011111, then inverting |
| // it. |
| Constant *Mask = ConstantIntegral::getAllOnesValue(SrcTy); |
| Mask = ConstantExpr::getZeroExtend(Mask, CI->getType()); |
| Mask = ConstantExpr::getNot(Mask); // 1's in the new bits. |
| if (ConstantExpr::getAnd(Mask, AndRHS)->isNullValue()) { |
| // If the and is clearing all of the sign bits, change this to a |
| // zero extension cast. To do this, cast the cast input to |
| // unsigned, then to the requested size. |
| Value *CastOp = CI->getOperand(0); |
| Instruction *NC = |
| new CastInst(CastOp, CastOp->getType()->getUnsignedVersion(), |
| CI->getName()+".uns"); |
| NC = InsertNewInstBefore(NC, I); |
| // Finally, insert a replacement for CI. |
| NC = new CastInst(NC, CI->getType(), CI->getName()); |
| CI->setName(""); |
| NC = InsertNewInstBefore(NC, I); |
| WorkList.push_back(CI); // Delete CI later. |
| I.setOperand(0, NC); |
| return &I; // The AND operand was modified. |
| } |
| } |
| } |
| } |
| } |
| |
| // 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); |
| } |
| |
| if (SetCondInst *RHS = dyn_cast<SetCondInst>(Op1)) { |
| // (setcc1 A, B) & (setcc2 A, B) --> (setcc3 A, B) |
| if (Instruction *R = AssociativeOpt(I, FoldSetCCLogical(*this, RHS))) |
| return R; |
| |
| Value *LHSVal, *RHSVal; |
| ConstantInt *LHSCst, *RHSCst; |
| Instruction::BinaryOps LHSCC, RHSCC; |
| if (match(Op0, m_SetCond(LHSCC, m_Value(LHSVal), m_ConstantInt(LHSCst)))) |
| if (match(RHS, m_SetCond(RHSCC, m_Value(RHSVal), m_ConstantInt(RHSCst)))) |
| if (LHSVal == RHSVal && // Found (X setcc C1) & (X setcc C2) |
| // Set[GL]E X, CST is folded to Set[GL]T elsewhere. |
| LHSCC != Instruction::SetGE && LHSCC != Instruction::SetLE && |
| RHSCC != Instruction::SetGE && RHSCC != Instruction::SetLE) { |
| // Ensure that the larger constant is on the RHS. |
| Constant *Cmp = ConstantExpr::getSetGT(LHSCst, RHSCst); |
| SetCondInst *LHS = cast<SetCondInst>(Op0); |
| if (cast<ConstantBool>(Cmp)->getValue()) { |
| std::swap(LHS, RHS); |
| std::swap(LHSCst, RHSCst); |
| std::swap(LHSCC, RHSCC); |
| } |
| |
| // At this point, we know we have have two setcc instructions |
| // comparing a value against two constants and and'ing the result |
| // together. Because of the above check, we know that we only have |
| // SetEQ, SetNE, SetLT, and SetGT here. We also know (from the |
| // FoldSetCCLogical 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 Instruction::SetEQ: |
| switch (RHSCC) { |
| default: assert(0 && "Unknown integer condition code!"); |
| case Instruction::SetEQ: // (X == 13 & X == 15) -> false |
| case Instruction::SetGT: // (X == 13 & X > 15) -> false |
| return ReplaceInstUsesWith(I, ConstantBool::False); |
| case Instruction::SetNE: // (X == 13 & X != 15) -> X == 13 |
| case Instruction::SetLT: // (X == 13 & X < 15) -> X == 13 |
| return ReplaceInstUsesWith(I, LHS); |
| } |
| case Instruction::SetNE: |
| switch (RHSCC) { |
| default: assert(0 && "Unknown integer condition code!"); |
| case Instruction::SetLT: |
| if (LHSCst == SubOne(RHSCst)) // (X != 13 & X < 14) -> X < 13 |
| return new SetCondInst(Instruction::SetLT, LHSVal, LHSCst); |
| break; // (X != 13 & X < 15) -> no change |
| case Instruction::SetEQ: // (X != 13 & X == 15) -> X == 15 |
| case Instruction::SetGT: // (X != 13 & X > 15) -> X > 15 |
| return ReplaceInstUsesWith(I, RHS); |
| case Instruction::SetNE: |
| 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); |
| const Type *UnsType = Add->getType()->getUnsignedVersion(); |
| Value *OffsetVal = InsertCastBefore(Add, UnsType, I); |
| AddCST = ConstantExpr::getSub(RHSCst, LHSCst); |
| AddCST = ConstantExpr::getCast(AddCST, UnsType); |
| return new SetCondInst(Instruction::SetGT, OffsetVal, AddCST); |
| } |
| break; // (X != 13 & X != 15) -> no change |
| } |
| break; |
| case Instruction::SetLT: |
| switch (RHSCC) { |
| default: assert(0 && "Unknown integer condition code!"); |
| case Instruction::SetEQ: // (X < 13 & X == 15) -> false |
| case Instruction::SetGT: // (X < 13 & X > 15) -> false |
| return ReplaceInstUsesWith(I, ConstantBool::False); |
| case Instruction::SetNE: // (X < 13 & X != 15) -> X < 13 |
| case Instruction::SetLT: // (X < 13 & X < 15) -> X < 13 |
| return ReplaceInstUsesWith(I, LHS); |
| } |
| case Instruction::SetGT: |
| switch (RHSCC) { |
| default: assert(0 && "Unknown integer condition code!"); |
| case Instruction::SetEQ: // (X > 13 & X == 15) -> X > 13 |
| return ReplaceInstUsesWith(I, LHS); |
| case Instruction::SetGT: // (X > 13 & X > 15) -> X > 15 |
| return ReplaceInstUsesWith(I, RHS); |
| case Instruction::SetNE: |
| if (RHSCst == AddOne(LHSCst)) // (X > 13 & X != 14) -> X > 14 |
| return new SetCondInst(Instruction::SetGT, LHSVal, RHSCst); |
| break; // (X > 13 & X != 15) -> no change |
| case Instruction::SetLT: // (X > 13 & X < 15) -> (X-14) <u 1 |
| return InsertRangeTest(LHSVal, AddOne(LHSCst), RHSCst, true, I); |
| } |
| } |
| } |
| } |
| |
| return Changed ? &I : 0; |
| } |
| |
| Instruction *InstCombiner::visitOr(BinaryOperator &I) { |
| bool Changed = SimplifyCommutative(I); |
| Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); |
| |
| if (isa<UndefValue>(Op1)) |
| return ReplaceInstUsesWith(I, // X | undef -> -1 |
| ConstantIntegral::getAllOnesValue(I.getType())); |
| |
| // or X, X = X or X, 0 == X |
| if (Op0 == Op1 || Op1 == Constant::getNullValue(I.getType())) |
| return ReplaceInstUsesWith(I, Op0); |
| |
| // or X, -1 == -1 |
| if (ConstantIntegral *RHS = dyn_cast<ConstantIntegral>(Op1)) { |
| // If X is known to only contain bits that already exist in RHS, just |
| // replace this instruction with RHS directly. |
| if (MaskedValueIsZero(Op0, |
| cast<ConstantIntegral>(ConstantExpr::getNot(RHS)))) |
| return ReplaceInstUsesWith(I, RHS); |
| |
| ConstantInt *C1; Value *X; |
| // (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, Op0->getName()); |
| Op0->setName(""); |
| InsertNewInstBefore(Or, I); |
| return BinaryOperator::createAnd(Or, ConstantExpr::getOr(RHS, C1)); |
| } |
| |
| // (X ^ C1) | C2 --> (X | C2) ^ (C1&~C2) |
| if (match(Op0, m_Xor(m_Value(X), m_ConstantInt(C1))) && isOnlyUse(Op0)) { |
| std::string Op0Name = Op0->getName(); Op0->setName(""); |
| Instruction *Or = BinaryOperator::createOr(X, RHS, Op0Name); |
| InsertNewInstBefore(Or, I); |
| return BinaryOperator::createXor(Or, |
| ConstantExpr::getAnd(C1, ConstantExpr::getNot(RHS))); |
| } |
| |
| // 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, *B; ConstantInt *C1, *C2; |
| |
| 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); |
| |
| // (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)) { |
| Instruction *NOr = BinaryOperator::createOr(A, Op1, Op0->getName()); |
| Op0->setName(""); |
| return BinaryOperator::createXor(InsertNewInstBefore(NOr, I), 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)) { |
| Instruction *NOr = BinaryOperator::createOr(A, Op0, Op1->getName()); |
| Op0->setName(""); |
| return BinaryOperator::createXor(InsertNewInstBefore(NOr, I), C1); |
| } |
| |
| // (A & C1)|(A & C2) == A & (C1|C2) |
| if (match(Op0, m_And(m_Value(A), m_ConstantInt(C1))) && |
| match(Op1, m_And(m_Value(B), m_ConstantInt(C2))) && A == B) |
| return BinaryOperator::createAnd(A, ConstantExpr::getOr(C1, C2)); |
| |
| if (match(Op0, m_Not(m_Value(A)))) { // ~A | Op1 |
| if (A == Op1) // ~A | A == -1 |
| return ReplaceInstUsesWith(I, |
| ConstantIntegral::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, |
| ConstantIntegral::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); |
| } |
| } |
| |
| // (setcc1 A, B) | (setcc2 A, B) --> (setcc3 A, B) |
| if (SetCondInst *RHS = dyn_cast<SetCondInst>(I.getOperand(1))) { |
| if (Instruction *R = AssociativeOpt(I, FoldSetCCLogical(*this, RHS))) |
| return R; |
| |
| Value *LHSVal, *RHSVal; |
| ConstantInt *LHSCst, *RHSCst; |
| Instruction::BinaryOps LHSCC, RHSCC; |
| if (match(Op0, m_SetCond(LHSCC, m_Value(LHSVal), m_ConstantInt(LHSCst)))) |
| if (match(RHS, m_SetCond(RHSCC, m_Value(RHSVal), m_ConstantInt(RHSCst)))) |
| if (LHSVal == RHSVal && // Found (X setcc C1) | (X setcc C2) |
| // Set[GL]E X, CST is folded to Set[GL]T elsewhere. |
| LHSCC != Instruction::SetGE && LHSCC != Instruction::SetLE && |
| RHSCC != Instruction::SetGE && RHSCC != Instruction::SetLE) { |
| // Ensure that the larger constant is on the RHS. |
| Constant *Cmp = ConstantExpr::getSetGT(LHSCst, RHSCst); |
| SetCondInst *LHS = cast<SetCondInst>(Op0); |
| if (cast<ConstantBool>(Cmp)->getValue()) { |
| std::swap(LHS, RHS); |
| std::swap(LHSCst, RHSCst); |
| std::swap(LHSCC, RHSCC); |
| } |
| |
| // At this point, we know we have have two setcc instructions |
| // comparing a value against two constants and or'ing the result |
| // together. Because of the above check, we know that we only have |
| // SetEQ, SetNE, SetLT, and SetGT here. We also know (from the |
| // FoldSetCCLogical 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 Instruction::SetEQ: |
| switch (RHSCC) { |
| default: assert(0 && "Unknown integer condition code!"); |
| case Instruction::SetEQ: |
| 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); |
| const Type *UnsType = Add->getType()->getUnsignedVersion(); |
| Value *OffsetVal = InsertCastBefore(Add, UnsType, I); |
| AddCST = ConstantExpr::getSub(AddOne(RHSCst), LHSCst); |
| AddCST = ConstantExpr::getCast(AddCST, UnsType); |
| return new SetCondInst(Instruction::SetLT, OffsetVal, AddCST); |
| } |
| break; // (X == 13 | X == 15) -> no change |
| |
| case Instruction::SetGT: // (X == 13 | X > 14) -> no change |
| break; |
| case Instruction::SetNE: // (X == 13 | X != 15) -> X != 15 |
| case Instruction::SetLT: // (X == 13 | X < 15) -> X < 15 |
| return ReplaceInstUsesWith(I, RHS); |
| } |
| break; |
| case Instruction::SetNE: |
| switch (RHSCC) { |
| default: assert(0 && "Unknown integer condition code!"); |
| case Instruction::SetEQ: // (X != 13 | X == 15) -> X != 13 |
| case Instruction::SetGT: // (X != 13 | X > 15) -> X != 13 |
| return ReplaceInstUsesWith(I, LHS); |
| case Instruction::SetNE: // (X != 13 | X != 15) -> true |
| case Instruction::SetLT: // (X != 13 | X < 15) -> true |
| return ReplaceInstUsesWith(I, ConstantBool::True); |
| } |
| break; |
| case Instruction::SetLT: |
| switch (RHSCC) { |
| default: assert(0 && "Unknown integer condition code!"); |
| case Instruction::SetEQ: // (X < 13 | X == 14) -> no change |
| break; |
| case Instruction::SetGT: // (X < 13 | X > 15) -> (X-13) > 2 |
| return InsertRangeTest(LHSVal, LHSCst, AddOne(RHSCst), false, I); |
| case Instruction::SetNE: // (X < 13 | X != 15) -> X != 15 |
| case Instruction::SetLT: // (X < 13 | X < 15) -> X < 15 |
| return ReplaceInstUsesWith(I, RHS); |
| } |
| break; |
| case Instruction::SetGT: |
| switch (RHSCC) { |
| default: assert(0 && "Unknown integer condition code!"); |
| case Instruction::SetEQ: // (X > 13 | X == 15) -> X > 13 |
| case Instruction::SetGT: // (X > 13 | X > 15) -> X > 13 |
| return ReplaceInstUsesWith(I, LHS); |
| case Instruction::SetNE: // (X > 13 | X != 15) -> true |
| case Instruction::SetLT: // (X > 13 | X < 15) -> true |
| return ReplaceInstUsesWith(I, ConstantBool::True); |
| } |
| } |
| } |
| } |
| 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())); |
| } |
| |
| if (ConstantIntegral *RHS = dyn_cast<ConstantIntegral>(Op1)) { |
| // xor X, 0 == X |
| if (RHS->isNullValue()) |
| return ReplaceInstUsesWith(I, Op0); |
| |
| if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) { |
| // xor (setcc A, B), true = not (setcc A, B) = setncc A, B |
| if (SetCondInst *SCI = dyn_cast<SetCondInst>(Op0I)) |
| if (RHS == ConstantBool::True && SCI->hasOneUse()) |
| return new SetCondInst(SCI->getInverseCondition(), |
| SCI->getOperand(0), SCI->getOperand(1)); |
| |
| // ~(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); |
| } |
| |
| // ~(~X & Y) --> (X | ~Y) |
| if (Op0I->getOpcode() == Instruction::And && RHS->isAllOnesValue()) { |
| 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); |
| return BinaryOperator::createOr(Op0NotVal, NotY); |
| } |
| } |
| |
| if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1))) |
| switch (Op0I->getOpcode()) { |
| case 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)); |
| } |
| break; |
| case Instruction::And: |
| // (X & C1) ^ C2 --> (X & C1) | C2 iff (C1&C2) == 0 |
| if (ConstantExpr::getAnd(RHS, Op0CI)->isNullValue()) |
| return BinaryOperator::createOr(Op0, RHS); |
| break; |
| case Instruction::Or: |
| // (X | C1) ^ C2 --> (X | C1) & ~C2 iff (C1&C2) == C2 |
| if (ConstantExpr::getAnd(RHS, Op0CI) == RHS) |
| return BinaryOperator::createAnd(Op0, ConstantExpr::getNot(RHS)); |
| break; |
| default: break; |
| } |
| } |
| |
| // 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, |
| ConstantIntegral::getAllOnesValue(I.getType())); |
| |
| if (Value *X = dyn_castNotVal(Op1)) // A ^ ~A == -1 |
| if (X == Op0) |
| return ReplaceInstUsesWith(I, |
| ConstantIntegral::getAllOnesValue(I.getType())); |
| |
| if (Instruction *Op1I = dyn_cast<Instruction>(Op1)) |
| if (Op1I->getOpcode() == Instruction::Or) { |
| if (Op1I->getOperand(0) == Op0) { // B^(B|A) == (A|B)^B |
| cast<BinaryOperator>(Op1I)->swapOperands(); |
| I.swapOperands(); |
| std::swap(Op0, Op1); |
| } else if (Op1I->getOperand(1) == Op0) { // B^(A|B) == (A|B)^B |
| I.swapOperands(); |
| std::swap(Op0, Op1); |
| } |
| } else if (Op1I->getOpcode() == Instruction::Xor) { |
| if (Op0 == Op1I->getOperand(0)) // A^(A^B) == B |
| return ReplaceInstUsesWith(I, Op1I->getOperand(1)); |
| else if (Op0 == Op1I->getOperand(1)) // A^(B^A) == B |
| return ReplaceInstUsesWith(I, Op1I->getOperand(0)); |
| } |
| |
| if (Instruction *Op0I = dyn_cast<Instruction>(Op0)) |
| if (Op0I->getOpcode() == Instruction::Or && Op0I->hasOneUse()) { |
| if (Op0I->getOperand(0) == Op1) // (B|A)^B == (A|B)^B |
| cast<BinaryOperator>(Op0I)->swapOperands(); |
| if (Op0I->getOperand(1) == Op1) { // (A|B)^B == A & ~B |
| Value *NotB = InsertNewInstBefore(BinaryOperator::createNot(Op1, |
| Op1->getName()+".not"), I); |
| return BinaryOperator::createAnd(Op0I->getOperand(0), NotB); |
| } |
| } else if (Op0I->getOpcode() == Instruction::Xor) { |
| if (Op1 == Op0I->getOperand(0)) // (A^B)^A == B |
| return ReplaceInstUsesWith(I, Op0I->getOperand(1)); |
| else if (Op1 == Op0I->getOperand(1)) // (B^A)^A == B |
| return ReplaceInstUsesWith(I, Op0I->getOperand(0)); |
| } |
| |
| // (A & C1)^(B & C2) -> (A & C1)|(B & C2) iff C1&C2 == 0 |
| Value *A, *B; ConstantInt *C1, *C2; |
| if (match(Op0, m_And(m_Value(A), m_ConstantInt(C1))) && |
| match(Op1, m_And(m_Value(B), m_ConstantInt(C2))) && |
| ConstantExpr::getAnd(C1, C2)->isNullValue()) |
| return BinaryOperator::createOr(Op0, Op1); |
| |
| // (setcc1 A, B) ^ (setcc2 A, B) --> (setcc3 A, B) |
| if (SetCondInst *RHS = dyn_cast<SetCondInst>(I.getOperand(1))) |
| if (Instruction *R = AssociativeOpt(I, FoldSetCCLogical(*this, RHS))) |
| return R; |
| |
| return Changed ? &I : 0; |
| } |
| |
| /// MulWithOverflow - Compute Result = In1*In2, returning true if the result |
| /// overflowed for this type. |
| static bool MulWithOverflow(ConstantInt *&Result, ConstantInt *In1, |
| ConstantInt *In2) { |
| Result = cast<ConstantInt>(ConstantExpr::getMul(In1, In2)); |
| return !In2->isNullValue() && ConstantExpr::getDiv(Result, In2) != In1; |
| } |
| |
| static bool isPositive(ConstantInt *C) { |
| return cast<ConstantSInt>(C)->getValue() >= 0; |
| } |
| |
| /// AddWithOverflow - Compute Result = In1+In2, returning true if the result |
| /// overflowed for this type. |
| static bool AddWithOverflow(ConstantInt *&Result, ConstantInt *In1, |
| ConstantInt *In2) { |
| Result = cast<ConstantInt>(ConstantExpr::getAdd(In1, In2)); |
| |
| if (In1->getType()->isUnsigned()) |
| return cast<ConstantUInt>(Result)->getValue() < |
| cast<ConstantUInt>(In1)->getValue(); |
| if (isPositive(In1) != isPositive(In2)) |
| return false; |
| if (isPositive(In1)) |
| return cast<ConstantSInt>(Result)->getValue() < |
| cast<ConstantSInt>(In1)->getValue(); |
| return cast<ConstantSInt>(Result)->getValue() > |
| cast<ConstantSInt>(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 *UIntPtrTy = TD.getIntPtrType(); |
| const Type *SIntPtrTy = UIntPtrTy->getSignedVersion(); |
| Value *Result = Constant::getNullValue(SIntPtrTy); |
| |
| // Build a mask for high order bits. |
| uint64_t PtrSizeMask = ~0ULL; |
| PtrSizeMask >>= 64-(TD.getPointerSize()*8); |
| |
| for (unsigned i = 1, e = GEP->getNumOperands(); i != e; ++i, ++GTI) { |
| Value *Op = GEP->getOperand(i); |
| uint64_t Size = TD.getTypeSize(GTI.getIndexedType()) & PtrSizeMask; |
| Constant *Scale = ConstantExpr::getCast(ConstantUInt::get(UIntPtrTy, Size), |
| SIntPtrTy); |
| if (Constant *OpC = dyn_cast<Constant>(Op)) { |
| if (!OpC->isNullValue()) { |
| OpC = ConstantExpr::getCast(OpC, SIntPtrTy); |
| Scale = ConstantExpr::getMul(OpC, 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); |
| } |
| } |
| } else { |
| // Convert to correct type. |
| Op = IC.InsertNewInstBefore(new CastInst(Op, SIntPtrTy, |
| Op->getName()+".c"), I); |
| if (Size != 1) |
| // 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. |
| Result = IC.InsertNewInstBefore(BinaryOperator::createAdd(Op, Result, |
| GEP->getName()+".offs"), I); |
| } |
| } |
| return Result; |
| } |
| |
| /// FoldGEPSetCC - 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::FoldGEPSetCC(User *GEPLHS, Value *RHS, |
| Instruction::BinaryOps 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 seteq or setne comparison, just return whether each |
| // index is zero or not. |
| if (Cond == Instruction::SetEQ || Cond == Instruction::SetNE) { |
| 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. |
| ConstantBool::get(Cond == Instruction::SetNE)); |
| } |
| |
| if (EmitIt) { |
| Instruction *Comp = |
| new SetCondInst(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 == Instruction::SetNE) // 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 |
| ReplaceInstUsesWith(I, // No comparison is needed here, all indexes = 0 |
| ConstantBool::get(Cond == Instruction::SetEQ)); |
| } |
| |
| // Only lower this if the setcc 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 SetCondInst(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 SetCondInst(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 FoldGEPSetCC(GEPRHS, GEPLHS->getOperand(0), |
| SetCondInst::getSwappedCondition(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 FoldGEPSetCC(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. |
| ConstantBool::get(Cond == Instruction::SetEQ)); |
| else if (NumDifferences == 1) { |
| Value *LHSV = GEPLHS->getOperand(DiffOperand); |
| Value *RHSV = GEPRHS->getOperand(DiffOperand); |
| |
| // Convert the operands to signed values to make sure to perform a |
| // signed comparison. |
| const Type *NewTy = LHSV->getType()->getSignedVersion(); |
| if (LHSV->getType() != NewTy) |
| LHSV = InsertNewInstBefore(new CastInst(LHSV, NewTy, |
| LHSV->getName()), I); |
| if (RHSV->getType() != NewTy) |
| RHSV = InsertNewInstBefore(new CastInst(RHSV, NewTy, |
| RHSV->getName()), I); |
| return new SetCondInst(Cond, LHSV, RHSV); |
| } |
| } |
| |
| // Only lower this if the setcc 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 SetCondInst(Cond, L, R); |
| } |
| } |
| return 0; |
| } |
| |
| |
| Instruction *InstCombiner::visitSetCondInst(SetCondInst &I) { |
| bool Changed = SimplifyCommutative(I); |
| Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); |
| const Type *Ty = Op0->getType(); |
| |
| // setcc X, X |
| if (Op0 == Op1) |
| return ReplaceInstUsesWith(I, ConstantBool::get(isTrueWhenEqual(I))); |
| |
| if (isa<UndefValue>(Op1)) // X setcc undef -> undef |
| return ReplaceInstUsesWith(I, UndefValue::get(Type::BoolTy)); |
| |
| // setcc <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, ConstantBool::get(!isTrueWhenEqual(I))); |
| |
| // setcc's with boolean values can always be turned into bitwise operations |
| if (Ty == Type::BoolTy) { |
| switch (I.getOpcode()) { |
| default: assert(0 && "Invalid setcc instruction!"); |
| case Instruction::SetEQ: { // seteq bool %A, %B -> ~(A^B) |
| Instruction *Xor = BinaryOperator::createXor(Op0, Op1, I.getName()+"tmp"); |
| InsertNewInstBefore(Xor, I); |
| return BinaryOperator::createNot(Xor); |
| } |
| case Instruction::SetNE: |
| return BinaryOperator::createXor(Op0, Op1); |
| |
| case Instruction::SetGT: |
| std::swap(Op0, Op1); // Change setgt -> setlt |
| // FALL THROUGH |
| case Instruction::SetLT: { // setlt bool A, B -> ~X & Y |
| Instruction *Not = BinaryOperator::createNot(Op0, I.getName()+"tmp"); |
| InsertNewInstBefore(Not, I); |
| return BinaryOperator::createAnd(Not, Op1); |
| } |
| case Instruction::SetGE: |
| std::swap(Op0, Op1); // Change setge -> setle |
| // FALL THROUGH |
| case Instruction::SetLE: { // setle 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)) { |
| // Check to see if we are comparing against the minimum or maximum value... |
| if (CI->isMinValue()) { |
| if (I.getOpcode() == Instruction::SetLT) // A < MIN -> FALSE |
| return ReplaceInstUsesWith(I, ConstantBool::False); |
| if (I.getOpcode() == Instruction::SetGE) // A >= MIN -> TRUE |
| return ReplaceInstUsesWith(I, ConstantBool::True); |
| if (I.getOpcode() == Instruction::SetLE) // A <= MIN -> A == MIN |
| return BinaryOperator::createSetEQ(Op0, Op1); |
| if (I.getOpcode() == Instruction::SetGT) // A > MIN -> A != MIN |
| return BinaryOperator::createSetNE(Op0, Op1); |
| |
| } else if (CI->isMaxValue()) { |
| if (I.getOpcode() == Instruction::SetGT) // A > MAX -> FALSE |
| return ReplaceInstUsesWith(I, ConstantBool::False); |
| if (I.getOpcode() == Instruction::SetLE) // A <= MAX -> TRUE |
| return ReplaceInstUsesWith(I, ConstantBool::True); |
| if (I.getOpcode() == Instruction::SetGE) // A >= MAX -> A == MAX |
| return BinaryOperator::createSetEQ(Op0, Op1); |
| if (I.getOpcode() == Instruction::SetLT) // A < MAX -> A != MAX |
| return BinaryOperator::createSetNE(Op0, Op1); |
| |
| // Comparing against a value really close to min or max? |
| } else if (isMinValuePlusOne(CI)) { |
| if (I.getOpcode() == Instruction::SetLT) // A < MIN+1 -> A == MIN |
| return BinaryOperator::createSetEQ(Op0, SubOne(CI)); |
| if (I.getOpcode() == Instruction::SetGE) // A >= MIN-1 -> A != MIN |
| return BinaryOperator::createSetNE(Op0, SubOne(CI)); |
| |
| } else if (isMaxValueMinusOne(CI)) { |
| if (I.getOpcode() == Instruction::SetGT) // A > MAX-1 -> A == MAX |
| return BinaryOperator::createSetEQ(Op0, AddOne(CI)); |
| if (I.getOpcode() == Instruction::SetLE) // A <= MAX-1 -> A != MAX |
| return BinaryOperator::createSetNE(Op0, AddOne(CI)); |
| } |
| |
| // If we still have a setle or setge instruction, turn it into the |
| // appropriate setlt or setgt instruction. Since the border cases have |
| // already been handled above, this requires little checking. |
| // |
| if (I.getOpcode() == Instruction::SetLE) |
| return BinaryOperator::createSetLT(Op0, AddOne(CI)); |
| if (I.getOpcode() == Instruction::SetGE) |
| return BinaryOperator::createSetGT(Op0, SubOne(CI)); |
| |
| if (Instruction *LHSI = dyn_cast<Instruction>(Op0)) |
| switch (LHSI->getOpcode()) { |
| case Instruction::And: |
| if (LHSI->hasOneUse() && isa<ConstantInt>(LHSI->getOperand(1)) && |
| LHSI->getOperand(0)->hasOneUse()) { |
| // 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. |
| ShiftInst *Shift = dyn_cast<ShiftInst>(LHSI->getOperand(0)); |
| ConstantUInt *ShAmt; |
| ShAmt = Shift ? dyn_cast<ConstantUInt>(Shift->getOperand(1)) : 0; |
| ConstantInt *AndCST = cast<ConstantInt>(LHSI->getOperand(1)); |
| const Type *Ty = LHSI->getType(); |
| |
| // 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->getOpcode() != Instruction::Shr || |
| Shift->getType()->isUnsigned(); |
| 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. |
| int ShAmtVal = Ty->getPrimitiveSizeInBits()-ShAmt->getValue(); |
| if (ShAmtVal < 0) ShAmtVal = 0; // Out of range shift. |
| |
| Constant *OShAmt = ConstantUInt::get(Type::UByteTy, ShAmtVal); |
| Constant *ShVal = |
| ConstantExpr::getShl(ConstantInt::getAllOnesValue(Ty), OShAmt); |
| if (ConstantExpr::getAnd(ShVal, AndCST)->isNullValue()) |
| CanFold = true; |
| } |
| |
| if (CanFold) { |
| Constant *NewCst; |
| if (Shift->getOpcode() == Instruction::Shl) |
| NewCst = ConstantExpr::getUShr(CI, ShAmt); |
| else |
| NewCst = ConstantExpr::getShl(CI, ShAmt); |
| |
| // Check to see if we are shifting out any of the bits being |
| // compared. |
| if (ConstantExpr::get(Shift->getOpcode(), NewCst, ShAmt) != CI){ |
| // 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 (I.getOpcode() == Instruction::SetEQ) |
| return ReplaceInstUsesWith(I, ConstantBool::False); |
| if (I.getOpcode() == Instruction::SetNE) |
| return ReplaceInstUsesWith(I, ConstantBool::True); |
| } else { |
| I.setOperand(1, NewCst); |
| Constant *NewAndCST; |
| if (Shift->getOpcode() == Instruction::Shl) |
| NewAndCST = ConstantExpr::getUShr(AndCST, ShAmt); |
| else |
| NewAndCST = ConstantExpr::getShl(AndCST, ShAmt); |
| LHSI->setOperand(1, NewAndCST); |
| LHSI->setOperand(0, Shift->getOperand(0)); |
| WorkList.push_back(Shift); // Shift is dead. |
| AddUsesToWorkList(I); |
| return &I; |
| } |
| } |
| } |
| } |
| break; |
| |
| case Instruction::Shl: // (setcc (shl X, ShAmt), CI) |
| if (ConstantUInt *ShAmt = dyn_cast<ConstantUInt>(LHSI->getOperand(1))) { |
| switch (I.getOpcode()) { |
| default: break; |
| case Instruction::SetEQ: |
| case Instruction::SetNE: { |
| unsigned TypeBits = CI->getType()->getPrimitiveSizeInBits(); |
| |
| // 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->getValue() >= TypeBits) |
| break; |
| |
| // If we are comparing against bits always shifted out, the |
| // comparison cannot succeed. |
| Constant *Comp = |
| ConstantExpr::getShl(ConstantExpr::getShr(CI, ShAmt), ShAmt); |
| if (Comp != CI) {// Comparing against a bit that we know is zero. |
| bool IsSetNE = I.getOpcode() == Instruction::SetNE; |
| Constant *Cst = ConstantBool::get(IsSetNE); |
| return ReplaceInstUsesWith(I, Cst); |
| } |
| |
| if (LHSI->hasOneUse()) { |
| // Otherwise strength reduce the shift into an and. |
| unsigned ShAmtVal = (unsigned)ShAmt->getValue(); |
| uint64_t Val = (1ULL << (TypeBits-ShAmtVal))-1; |
| |
| Constant *Mask; |
| if (CI->getType()->isUnsigned()) { |
| Mask = ConstantUInt::get(CI->getType(), Val); |
| } else if (ShAmtVal != 0) { |
| Mask = ConstantSInt::get(CI->getType(), Val); |
| } else { |
| Mask = ConstantInt::getAllOnesValue(CI->getType()); |
| } |
| |
| Instruction *AndI = |
| BinaryOperator::createAnd(LHSI->getOperand(0), |
| Mask, LHSI->getName()+".mask"); |
| Value *And = InsertNewInstBefore(AndI, I); |
| return new SetCondInst(I.getOpcode(), And, |
| ConstantExpr::getUShr(CI, ShAmt)); |
| } |
| } |
| } |
| } |
| break; |
| |
| case Instruction::Shr: // (setcc (shr X, ShAmt), CI) |
| if (ConstantUInt *ShAmt = dyn_cast<ConstantUInt>(LHSI->getOperand(1))) { |
| switch (I.getOpcode()) { |
| default: break; |
| case Instruction::SetEQ: |
| case Instruction::SetNE: { |
| |
| // Check that the shift amount is in range. If not, don't perform |
| // undefined shifts. When the shift is visited it will be |
| // simplified. |
| unsigned TypeBits = CI->getType()->getPrimitiveSizeInBits(); |
| if (ShAmt->getValue() >= TypeBits) |
| break; |
| |
| // If we are comparing against bits always shifted out, the |
| // comparison cannot succeed. |
| Constant *Comp = |
| ConstantExpr::getShr(ConstantExpr::getShl(CI, ShAmt), ShAmt); |
| |
| if (Comp != CI) {// Comparing against a bit that we know is zero. |
| bool IsSetNE = I.getOpcode() == Instruction::SetNE; |
| Constant *Cst = ConstantBool::get(IsSetNE); |
| return ReplaceInstUsesWith(I, Cst); |
| } |
| |
| if (LHSI->hasOneUse() || CI->isNullValue()) { |
| unsigned ShAmtVal = (unsigned)ShAmt->getValue(); |
| |
| // Otherwise strength reduce the shift into an and. |
| uint64_t Val = ~0ULL; // All ones. |
| Val <<= ShAmtVal; // Shift over to the right spot. |
| |
| Constant *Mask; |
| if (CI->getType()->isUnsigned()) { |
| Val &= ~0ULL >> (64-TypeBits); |
| Mask = ConstantUInt::get(CI->getType(), Val); |
| } else { |
| Mask = ConstantSInt::get(CI->getType(), Val); |
| } |
| |
| Instruction *AndI = |
| BinaryOperator::createAnd(LHSI->getOperand(0), |
| Mask, LHSI->getName()+".mask"); |
| Value *And = InsertNewInstBefore(AndI, I); |
| return new SetCondInst(I.getOpcode(), And, |
| ConstantExpr::getShl(CI, ShAmt)); |
| } |
| break; |
| } |
| } |
| } |
| break; |
| |
| case Instruction::Div: |
| // Fold: (div X, C1) op C2 -> range check |
| if (ConstantInt *DivRHS = dyn_cast<ConstantInt>(LHSI->getOperand(1))) { |
| // 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. |
| bool LoOverflow = false, HiOverflow = 0; |
| ConstantInt *LoBound = 0, *HiBound = 0; |
| |
| ConstantInt *Prod; |
| bool ProdOV = MulWithOverflow(Prod, CI, DivRHS); |
| |
| Instruction::BinaryOps Opcode = I.getOpcode(); |
| |
| if (DivRHS->isNullValue()) { // Don't hack on divide by zeros. |
| } else if (LHSI->getType()->isUnsigned()) { // udiv |
| LoBound = Prod; |
| LoOverflow = ProdOV; |
| HiOverflow = ProdOV || AddWithOverflow(HiBound, LoBound, DivRHS); |
| } else if (isPositive(DivRHS)) { // Divisor is > 0. |
| if (CI->isNullValue()) { // (X / pos) op 0 |
| // Can't overflow. |
| LoBound = cast<ConstantInt>(ConstantExpr::getNeg(SubOne(DivRHS))); |
| HiBound = DivRHS; |
| } else if (isPositive(CI)) { // (X / pos) op pos |
| LoBound = Prod; |
| LoOverflow = ProdOV; |
| HiOverflow = ProdOV || AddWithOverflow(HiBound, Prod, DivRHS); |
| } else { // (X / pos) op neg |
| Constant *DivRHSH = ConstantExpr::getNeg(SubOne(DivRHS)); |
| LoOverflow = AddWithOverflow(LoBound, Prod, |
| cast<ConstantInt>(DivRHSH)); |
| HiBound = Prod; |
| HiOverflow = ProdOV; |
| } |
| } else { // Divisor is < 0. |
| if (CI->isNullValue()) { // (X / neg) op 0 |
| LoBound = AddOne(DivRHS); |
| HiBound = cast<ConstantInt>(ConstantExpr::getNeg(DivRHS)); |
| if (HiBound == DivRHS) |
| LoBound = 0; // - INTMIN = INTMIN |
| } else if (isPositive(CI)) { // (X / neg) op pos |
| HiOverflow = LoOverflow = ProdOV; |
| if (!LoOverflow) |
| LoOverflow = AddWithOverflow(LoBound, Prod, AddOne(DivRHS)); |
| HiBound = AddOne(Prod); |
| } else { // (X / neg) op neg |
| LoBound = Prod; |
| LoOverflow = HiOverflow = ProdOV; |
| HiBound = cast<ConstantInt>(ConstantExpr::getSub(Prod, DivRHS)); |
| } |
| |
| // Dividing by a negate swaps the condition. |
| Opcode = SetCondInst::getSwappedCondition(Opcode); |
| } |
| |
| if (LoBound) { |
| Value *X = LHSI->getOperand(0); |
| switch (Opcode) { |
| default: assert(0 && "Unhandled setcc opcode!"); |
| case Instruction::SetEQ: |
| if (LoOverflow && HiOverflow) |
| return ReplaceInstUsesWith(I, ConstantBool::False); |
| else if (HiOverflow) |
| return new SetCondInst(Instruction::SetGE, X, LoBound); |
| else if (LoOverflow) |
| return new SetCondInst(Instruction::SetLT, X, HiBound); |
| else |
| return InsertRangeTest(X, LoBound, HiBound, true, I); |
| case Instruction::SetNE: |
| if (LoOverflow && HiOverflow) |
| return ReplaceInstUsesWith(I, ConstantBool::True); |
| else if (HiOverflow) |
| return new SetCondInst(Instruction::SetLT, X, LoBound); |
| else if (LoOverflow) |
| return new SetCondInst(Instruction::SetGE, X, HiBound); |
| else |
| return InsertRangeTest(X, LoBound, HiBound, false, I); |
| case Instruction::SetLT: |
| if (LoOverflow) |
| return ReplaceInstUsesWith(I, ConstantBool::False); |
| return new SetCondInst(Instruction::SetLT, X, LoBound); |
| case Instruction::SetGT: |
| if (HiOverflow) |
| return ReplaceInstUsesWith(I, ConstantBool::False); |
| return new SetCondInst(Instruction::SetGE, X, HiBound); |
| } |
| } |
| } |
| break; |
| } |
| |
| // Simplify seteq and setne instructions... |
| if (I.getOpcode() == Instruction::SetEQ || |
| I.getOpcode() == Instruction::SetNE) { |
| bool isSetNE = I.getOpcode() == Instruction::SetNE; |
| |
| // If the first operand is (and|or|xor) with a constant, and the second |
| // operand is a constant, simplify a bit. |
| if (BinaryOperator *BO = dyn_cast<BinaryOperator>(Op0)) { |
| switch (BO->getOpcode()) { |
| case Instruction::Rem: |
| // If we have a signed (X % (2^c)) == 0, turn it into an unsigned one. |
| if (CI->isNullValue() && isa<ConstantSInt>(BO->getOperand(1)) && |
| BO->hasOneUse() && |
| cast<ConstantSInt>(BO->getOperand(1))->getValue() > 1) |
| if (unsigned L2 = |
| Log2(cast<ConstantSInt>(BO->getOperand(1))->getValue())) { |
| const Type *UTy = BO->getType()->getUnsignedVersion(); |
| Value *NewX = InsertNewInstBefore(new CastInst(BO->getOperand(0), |
| UTy, "tmp"), I); |
| Constant *RHSCst = ConstantUInt::get(UTy, 1ULL << L2); |
| Value *NewRem =InsertNewInstBefore(BinaryOperator::createRem(NewX, |
| RHSCst, BO->getName()), I); |
| return BinaryOperator::create(I.getOpcode(), NewRem, |
| Constant::getNullValue(UTy)); |
| } |
| 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 SetCondInst(I.getOpcode(), BO->getOperand(0), |
| ConstantExpr::getSub(CI, BOp1C)); |
| } else if (CI->isNullValue()) { |
| // 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 SetCondInst(I.getOpcode(), BOp0, NegVal); |
| else if (Value *NegVal = dyn_castNegVal(BOp0)) |
| return new SetCondInst(I.getOpcode(), NegVal, BOp1); |
| else if (BO->hasOneUse()) { |
| Instruction *Neg = BinaryOperator::createNeg(BOp1, BO->getName()); |
| BO->setName(""); |
| InsertNewInstBefore(Neg, I); |
| return new SetCondInst(I.getOpcode(), 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 BinaryOperator::create(I.getOpcode(), BO->getOperand(0), |
| ConstantExpr::getXor(CI, BOC)); |
| |
| // FALLTHROUGH |
| case Instruction::Sub: |
| // Replace (([sub|xor] A, B) != 0) with (A != B) |
| if (CI->isNullValue()) |
| return new SetCondInst(I.getOpcode(), 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(CI); |
| if (!ConstantExpr::getAnd(BOC, NotCI)->isNullValue()) |
| return ReplaceInstUsesWith(I, ConstantBool::get(isSetNE)); |
| } |
| 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 (!ConstantExpr::getAnd(CI, |
| ConstantExpr::getNot(BOC))->isNullValue()) |
| return ReplaceInstUsesWith(I, ConstantBool::get(isSetNE)); |
| |
| // If we have ((X & C) == C), turn it into ((X & C) != 0). |
| if (CI == BOC && isOneBitSet(CI)) |
| return new SetCondInst(isSetNE ? Instruction::SetEQ : |
| Instruction::SetNE, Op0, |
| Constant::getNullValue(CI->getType())); |
| |
| // Replace (and X, (1 << size(X)-1) != 0) with x < 0, converting X |
| // to be a signed value as appropriate. |
| if (isSignBit(BOC)) { |
| Value *X = BO->getOperand(0); |
| // If 'X' is not signed, insert a cast now... |
| if (!BOC->getType()->isSigned()) { |
| const Type *DestTy = BOC->getType()->getSignedVersion(); |
| X = InsertCastBefore(X, DestTy, I); |
| } |
| return new SetCondInst(isSetNE ? Instruction::SetLT : |
| Instruction::SetGE, X, |
| Constant::getNullValue(X->getType())); |
| } |
| |
| // ((X & ~7) == 0) --> X < 8 |
| if (CI->isNullValue() && isHighOnes(BOC)) { |
| Value *X = BO->getOperand(0); |
| Constant *NegX = ConstantExpr::getNeg(BOC); |
| |
| // If 'X' is signed, insert a cast now. |
| if (NegX->getType()->isSigned()) { |
| const Type *DestTy = NegX->getType()->getUnsignedVersion(); |
| X = InsertCastBefore(X, DestTy, I); |
| NegX = ConstantExpr::getCast(NegX, DestTy); |
| } |
| |
| return new SetCondInst(isSetNE ? Instruction::SetGE : |
| Instruction::SetLT, X, NegX); |
| } |
| |
| } |
| default: break; |
| } |
| } |
| } else { // Not a SetEQ/SetNE |
| // If the LHS is a cast from an integral value of the same size, |
| if (CastInst *Cast = dyn_cast<CastInst>(Op0)) { |
| Value *CastOp = Cast->getOperand(0); |
| const Type *SrcTy = CastOp->getType(); |
| unsigned SrcTySize = SrcTy->getPrimitiveSizeInBits(); |
| if (SrcTy != Cast->getType() && SrcTy->isInteger() && |
| SrcTySize == Cast->getType()->getPrimitiveSizeInBits()) { |
| assert((SrcTy->isSigned() ^ Cast->getType()->isSigned()) && |
| "Source and destination signednesses should differ!"); |
| if (Cast->getType()->isSigned()) { |
| // If this is a signed comparison, check for comparisons in the |
| // vicinity of zero. |
| if (I.getOpcode() == Instruction::SetLT && CI->isNullValue()) |
| // X < 0 => x > 127 |
| return BinaryOperator::createSetGT(CastOp, |
| ConstantUInt::get(SrcTy, (1ULL << (SrcTySize-1))-1)); |
| else if (I.getOpcode() == Instruction::SetGT && |
| cast<ConstantSInt>(CI)->getValue() == -1) |
| // X > -1 => x < 128 |
| return BinaryOperator::createSetLT(CastOp, |
| ConstantUInt::get(SrcTy, 1ULL << (SrcTySize-1))); |
| } else { |
| ConstantUInt *CUI = cast<ConstantUInt>(CI); |
| if (I.getOpcode() == Instruction::SetLT && |
| CUI->getValue() == 1ULL << (SrcTySize-1)) |
| // X < 128 => X > -1 |
| return BinaryOperator::createSetGT(CastOp, |
| ConstantSInt::get(SrcTy, -1)); |
| else if (I.getOpcode() == Instruction::SetGT && |
| CUI->getValue() == (1ULL << (SrcTySize-1))-1) |
| // X > 127 => X < 0 |
| return BinaryOperator::createSetLT(CastOp, |
| Constant::getNullValue(SrcTy)); |
| } |
| } |
| } |
| } |
| } |
| |
| // Handle setcc with constant RHS's that can be integer, FP or pointer. |
| if (Constant *RHSC = dyn_cast<Constant>(Op1)) { |
| if (Instruction *LHSI = dyn_cast<Instruction>(Op0)) |
| switch (LHSI->getOpcode()) { |
| case Instruction::GetElementPtr: |
| if (RHSC->isNullValue()) { |
| // Transform setcc GEP P, int 0, int 0, int 0, null -> setcc 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 SetCondInst(I.getOpcode(), 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::get(I.getOpcode(), C, RHSC); |
| // Insert a new SetCC of the other select operand. |
| Op2 = InsertNewInstBefore(new SetCondInst(I.getOpcode(), |
| 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::get(I.getOpcode(), C, RHSC); |
| // Insert a new SetCC of the other select operand. |
| Op1 = InsertNewInstBefore(new SetCondInst(I.getOpcode(), |
| LHSI->getOperand(1), RHSC, |
| I.getName()), I); |
| } |
| } |
| |
| if (Op1) |
| return new SelectInst(LHSI->getOperand(0), Op1, Op2); |
| break; |
| } |
| } |
| |
| // If we can optimize a 'setcc GEP, P' or 'setcc P, GEP', do so now. |
| if (User *GEP = dyn_castGetElementPtr(Op0)) |
| if (Instruction *NI = FoldGEPSetCC(GEP, Op1, I.getOpcode(), I)) |
| return NI; |
| if (User *GEP = dyn_castGetElementPtr(Op1)) |
| if (Instruction *NI = FoldGEPSetCC(GEP, Op0, |
| SetCondInst::getSwappedCondition(I.getOpcode()), I)) |
| return NI; |
| |
| // Test to see if the operands of the setcc are casted versions of other |
| // values. If the cast can be stripped off both arguments, we do so now. |
| if (CastInst *CI = dyn_cast<CastInst>(Op0)) { |
| Value *CastOp0 = CI->getOperand(0); |
| if (CastOp0->getType()->isLosslesslyConvertibleTo(CI->getType()) && |
| (isa<Constant>(Op1) || isa<CastInst>(Op1)) && |
| (I.getOpcode() == Instruction::SetEQ || |
| I.getOpcode() == Instruction::SetNE)) { |
| // We keep moving the cast from the left operand over to the right |
| // operand, where it can often be eliminated completely. |
| Op0 = CastOp0; |
| |
| // If operand #1 is a cast instruction, see if we can eliminate it as |
| // well. |
| if (CastInst *CI2 = dyn_cast<CastInst>(Op1)) |
| if (CI2->getOperand(0)->getType()->isLosslesslyConvertibleTo( |
| Op0->getType())) |
| Op1 = CI2->getOperand(0); |
| |
| // If Op1 is a constant, we can fold the cast into the constant. |
| if (Op1->getType() != Op0->getType()) |
| if (Constant *Op1C = dyn_cast<Constant>(Op1)) { |
| Op1 = ConstantExpr::getCast(Op1C, Op0->getType()); |
| } else { |
| // Otherwise, cast the RHS right before the setcc |
| Op1 = new CastInst(Op1, Op0->getType(), Op1->getName()); |
| InsertNewInstBefore(cast<Instruction>(Op1), I); |
| } |
| return BinaryOperator::create(I.getOpcode(), Op0, Op1); |
| } |
| |
| // Handle the special case of: setcc (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 = visitSetCondInstWithCastAndCast(I)) |
| return R; |
| } |
| return Changed ? &I : 0; |
| } |
| |
| // visitSetCondInstWithCastAndCast - Handle setcond (cast x to y), (cast/cst). |
| // We only handle extending casts so far. |
| // |
| Instruction *InstCombiner::visitSetCondInstWithCastAndCast(SetCondInst &SCI) { |
| Value *LHSCIOp = cast<CastInst>(SCI.getOperand(0))->getOperand(0); |
| const Type *SrcTy = LHSCIOp->getType(); |
| const Type *DestTy = SCI.getOperand(0)->getType(); |
| Value *RHSCIOp; |
| |
| if (!DestTy->isIntegral() || !SrcTy->isIntegral()) |
| return 0; |
| |
| unsigned SrcBits = SrcTy->getPrimitiveSizeInBits(); |
| unsigned DestBits = DestTy->getPrimitiveSizeInBits(); |
| if (SrcBits >= DestBits) return 0; // Only handle extending cast. |
| |
| // Is this a sign or zero extension? |
| bool isSignSrc = SrcTy->isSigned(); |
| bool isSignDest = DestTy->isSigned(); |
| |
| if (CastInst *CI = dyn_cast<CastInst>(SCI.getOperand(1))) { |
| // Not an extension from the same type? |
| RHSCIOp = CI->getOperand(0); |
| if (RHSCIOp->getType() != LHSCIOp->getType()) return 0; |
| } else if (ConstantInt *CI = dyn_cast<ConstantInt>(SCI.getOperand(1))) { |
| // Compute the constant that would happen if we truncated to SrcTy then |
| // reextended to DestTy. |
| Constant *Res = ConstantExpr::getCast(CI, SrcTy); |
| |
| if (ConstantExpr::getCast(Res, DestTy) == CI) { |
| RHSCIOp = Res; |
| } else { |
| // If the value cannot be represented in the shorter type, we cannot emit |
| // a simple comparison. |
| if (SCI.getOpcode() == Instruction::SetEQ) |
| return ReplaceInstUsesWith(SCI, ConstantBool::False); |
| if (SCI.getOpcode() == Instruction::SetNE) |
| return ReplaceInstUsesWith(SCI, ConstantBool::True); |
| |
| // Evaluate the comparison for LT. |
| Value *Result; |
| if (DestTy->isSigned()) { |
| // We're performing a signed comparison. |
| if (isSignSrc) { |
| // Signed extend and signed comparison. |
| if (cast<ConstantSInt>(CI)->getValue() < 0) // X < (small) --> false |
| Result = ConstantBool::False; |
| else |
| Result = ConstantBool::True; // X < (large) --> true |
| } else { |
| // Unsigned extend and signed comparison. |
| if (cast<ConstantSInt>(CI)->getValue() < 0) |
| Result = ConstantBool::False; |
| else |
| Result = ConstantBool::True; |
| } |
| } else { |
| // We're performing an unsigned comparison. |
| if (!isSignSrc) { |
| // Unsigned extend & compare -> always true. |
| Result = ConstantBool::True; |
| } else { |
| // We're performing an unsigned comp with a sign extended value. |
| // This is true if the input is >= 0. [aka >s -1] |
| Constant *NegOne = ConstantIntegral::getAllOnesValue(SrcTy); |
| Result = InsertNewInstBefore(BinaryOperator::createSetGT(LHSCIOp, |
| NegOne, SCI.getName()), SCI); |
| } |
| } |
| |
| // Finally, return the value computed. |
| if (SCI.getOpcode() == Instruction::SetLT) { |
| return ReplaceInstUsesWith(SCI, Result); |
| } else { |
| assert(SCI.getOpcode()==Instruction::SetGT &&"SetCC should be folded!"); |
| if (Constant *CI = dyn_cast<Constant>(Result)) |
| return ReplaceInstUsesWith(SCI, ConstantExpr::getNot(CI)); |
| else |
| return BinaryOperator::createNot(Result); |
| } |
| } |
| } else { |
| return 0; |
| } |
| |
| // Okay, just insert a compare of the reduced operands now! |
| return BinaryOperator::create(SCI.getOpcode(), LHSCIOp, RHSCIOp); |
| } |
| |
| Instruction *InstCombiner::visitShiftInst(ShiftInst &I) { |
| assert(I.getOperand(1)->getType() == Type::UByteTy); |
| Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); |
| bool isLeftShift = I.getOpcode() == Instruction::Shl; |
| |
| // shl X, 0 == X and shr X, 0 == X |
| // shl 0, X == 0 and shr 0, X == 0 |
| if (Op1 == Constant::getNullValue(Type::UByteTy) || |
| Op0 == Constant::getNullValue(Op0->getType())) |
| return ReplaceInstUsesWith(I, Op0); |
| |
| if (isa<UndefValue>(Op0)) { // undef >>s X -> undef |
| if (!isLeftShift && I.getType()->isSigned()) |
| return ReplaceInstUsesWith(I, Op0); |
| else // undef << X -> 0 AND undef >>u X -> 0 |
| return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType())); |
| } |
| if (isa<UndefValue>(Op1)) { |
| if (isLeftShift || I.getType()->isUnsigned())// X << undef, X >>u undef -> 0 |
| return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType())); |
| else |
| return ReplaceInstUsesWith(I, Op0); // X >>s undef -> X |
| } |
| |
| // shr int -1, X = -1 (for any arithmetic shift rights of ~0) |
| if (!isLeftShift) |
| if (ConstantSInt *CSI = dyn_cast<ConstantSInt>(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 (!isLeftShift && I.getType()->isSigned()) { |
| if (MaskedValueIsZero(Op0, ConstantInt::getMinValue(I.getType()))) { |
| Value *V = InsertCastBefore(Op0, I.getType()->getUnsignedVersion(), I); |
| V = InsertNewInstBefore(new ShiftInst(Instruction::Shr, V, Op1, |
| I.getName()), I); |
| return new CastInst(V, I.getType()); |
| } |
| } |
| |
| if (ConstantUInt *CUI = dyn_cast<ConstantUInt>(Op1)) { |
| // shl uint X, 32 = 0 and shr ubyte Y, 9 = 0, ... just don't eliminate shr |
| // of a signed value. |
| // |
| unsigned TypeBits = Op0->getType()->getPrimitiveSizeInBits(); |
| if (CUI->getValue() >= TypeBits) { |
| if (!Op0->getType()->isSigned() || isLeftShift) |
| return ReplaceInstUsesWith(I, Constant::getNullValue(Op0->getType())); |
| else { |
| I.setOperand(1, ConstantUInt::get(Type::UByteTy, 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, CUI)); |
| |
| // 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 this is a SHL of a sign-extending cast, see if we can turn the input |
| // into a zero extending cast (a simple strength reduction). |
| if (CastInst *CI = dyn_cast<CastInst>(Op0)) { |
| const Type *SrcTy = CI->getOperand(0)->getType(); |
| if (isLeftShift && SrcTy->isInteger() && SrcTy->isSigned() && |
| SrcTy->getPrimitiveSizeInBits() < |
| CI->getType()->getPrimitiveSizeInBits()) { |
| // We can change it to a zero extension if we are shifting out all of |
| // the sign extended bits. To check this, form a mask of all of the |
| // sign extend bits, then shift them left and see if we have anything |
| // left. |
| Constant *Mask = ConstantIntegral::getAllOnesValue(SrcTy); // 1111 |
| Mask = ConstantExpr::getZeroExtend(Mask, CI->getType()); // 00001111 |
| Mask = ConstantExpr::getNot(Mask); // 1's in the sign bits: 11110000 |
| if (ConstantExpr::getShl(Mask, CUI)->isNullValue()) { |
| // If the shift is nuking all of the sign bits, change this to a |
| // zero extension cast. To do this, cast the cast input to |
| // unsigned, then to the requested size. |
| Value *CastOp = CI->getOperand(0); |
| Instruction *NC = |
| new CastInst(CastOp, CastOp->getType()->getUnsignedVersion(), |
| CI->getName()+".uns"); |
| NC = InsertNewInstBefore(NC, I); |
| // Finally, insert a replacement for CI. |
| NC = new CastInst(NC, CI->getType(), CI->getName()); |
| CI->setName(""); |
| NC = InsertNewInstBefore(NC, I); |
| WorkList.push_back(CI); // Delete CI later. |
| I.setOperand(0, NC); |
| return &I; // The SHL operand was modified. |
| } |
| } |
| } |
| |
| // 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 (BinaryOperator *Op0BO = dyn_cast<BinaryOperator>(Op0)) |
| 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.getType()->isUnsigned()) { |
| uint64_t Val = Op0C->getRawValue(); |
| isValid = ((Val & (1 << (TypeBits-1))) != 0) == highBitSet; |
| } |
| |
| if (isValid) { |
| Constant *NewRHS = ConstantExpr::get(I.getOpcode(), Op0C, CUI); |
| |
| Instruction *NewShift = |
| new ShiftInst(I.getOpcode(), Op0BO->getOperand(0), CUI, |
| Op0BO->getName()); |
| Op0BO->setName(""); |
| InsertNewInstBefore(NewShift, I); |
| |
| return BinaryOperator::create(Op0BO->getOpcode(), NewShift, |
| NewRHS); |
| } |
| } |
| } |
| |
| // If this is a shift of a shift, see if we can fold the two together... |
| if (ShiftInst *Op0SI = dyn_cast<ShiftInst>(Op0)) |
| if (ConstantUInt *ShiftAmt1C = |
| dyn_cast<ConstantUInt>(Op0SI->getOperand(1))) { |
| unsigned ShiftAmt1 = (unsigned)ShiftAmt1C->getValue(); |
| unsigned ShiftAmt2 = (unsigned)CUI->getValue(); |
| |
| // Check for (A << c1) << c2 and (A >> c1) >> c2 |
| if (I.getOpcode() == Op0SI->getOpcode()) { |
| unsigned Amt = ShiftAmt1+ShiftAmt2; // Fold into one big shift... |
| if (Op0->getType()->getPrimitiveSizeInBits() < Amt) |
| Amt = Op0->getType()->getPrimitiveSizeInBits(); |
| return new ShiftInst(I.getOpcode(), Op0SI->getOperand(0), |
| ConstantUInt::get(Type::UByteTy, Amt)); |
| } |
| |
| // Check for (A << c1) >> c2 or visaversa. If we are dealing with |
| // signed types, we can only support the (A >> c1) << c2 configuration, |
| // because it can not turn an arbitrary bit of A into a sign bit. |
| if (I.getType()->isUnsigned() || isLeftShift) { |
| // Calculate bitmask for what gets shifted off the edge... |
| Constant *C = ConstantIntegral::getAllOnesValue(I.getType()); |
| if (isLeftShift) |
| C = ConstantExpr::getShl(C, ShiftAmt1C); |
| else |
| C = ConstantExpr::getShr(C, ShiftAmt1C); |
| |
| Instruction *Mask = |
| BinaryOperator::createAnd(Op0SI->getOperand(0), C, |
| Op0SI->getOperand(0)->getName()+".mask"); |
| InsertNewInstBefore(Mask, I); |
| |
| // Figure out what flavor of shift we should use... |
| if (ShiftAmt1 == ShiftAmt2) |
| return ReplaceInstUsesWith(I, Mask); // (A << c) >> c === A & c2 |
| else if (ShiftAmt1 < ShiftAmt2) { |
| return new ShiftInst(I.getOpcode(), Mask, |
| ConstantUInt::get(Type::UByteTy, ShiftAmt2-ShiftAmt1)); |
| } else { |
| return new ShiftInst(Op0SI->getOpcode(), Mask, |
| ConstantUInt::get(Type::UByteTy, ShiftAmt1-ShiftAmt2)); |
| } |
| } |
| } |
| } |
| |
| return 0; |
| } |
| |
| enum CastType { |
| Noop = 0, |
| Truncate = 1, |
| Signext = 2, |
| Zeroext = 3 |
| }; |
| |
| /// getCastType - In the future, we will split the cast instruction into these |
| /// various types. Until then, we have to do the analysis here. |
| static CastType getCastType(const Type *Src, const Type *Dest) { |
| assert(Src->isIntegral() && Dest->isIntegral() && |
| "Only works on integral types!"); |
| unsigned SrcSize = Src->getPrimitiveSizeInBits(); |
| unsigned DestSize = Dest->getPrimitiveSizeInBits(); |
| |
| if (SrcSize == DestSize) return Noop; |
| if (SrcSize > DestSize) return Truncate; |
| if (Src->isSigned()) return Signext; |
| return Zeroext; |
| } |
| |
| |
| // isEliminableCastOfCast - Return true if it is valid to eliminate the CI |
| // instruction. |
| // |
| static inline bool isEliminableCastOfCast(const Type *SrcTy, const Type *MidTy, |
| const Type *DstTy, TargetData *TD) { |
| |
| // It is legal to eliminate the instruction if casting A->B->A if the sizes |
| // are identical and the bits don't get reinterpreted (for example |
| // int->float->int would not be allowed). |
| if (SrcTy == DstTy && SrcTy->isLosslesslyConvertibleTo(MidTy)) |
| return true; |
| |
| // If we are casting between pointer and integer types, treat pointers as |
| // integers of the appropriate size for the code below. |
| if (isa<PointerType>(SrcTy)) SrcTy = TD->getIntPtrType(); |
| if (isa<PointerType>(MidTy)) MidTy = TD->getIntPtrType(); |
| if (isa<PointerType>(DstTy)) DstTy = TD->getIntPtrType(); |
| |
| // Allow free casting and conversion of sizes as long as the sign doesn't |
| // change... |
| if (SrcTy->isIntegral() && MidTy->isIntegral() && DstTy->isIntegral()) { |
| CastType FirstCast = getCastType(SrcTy, MidTy); |
| CastType SecondCast = getCastType(MidTy, DstTy); |
| |
| // Capture the effect of these two casts. If the result is a legal cast, |
| // the CastType is stored here, otherwise a special code is used. |
| static const unsigned CastResult[] = { |
| // First cast is noop |
| 0, 1, 2, 3, |
| // First cast is a truncate |
| 1, 1, 4, 4, // trunc->extend is not safe to eliminate |
| // First cast is a sign ext |
| 2, 5, 2, 4, // signext->zeroext never ok |
| // First cast is a zero ext |
| 3, 5, 3, 3, |
| }; |
| |
| unsigned Result = CastResult[FirstCast*4+SecondCast]; |
| switch (Result) { |
| default: assert(0 && "Illegal table value!"); |
| case 0: |
| case 1: |
| case 2: |
| case 3: |
| // FIXME: in the future, when LLVM has explicit sign/zeroextends and |
| // truncates, we could eliminate more casts. |
| return (unsigned)getCastType(SrcTy, DstTy) == Result; |
| case 4: |
| return false; // Not possible to eliminate this here. |
| case 5: |
| // Sign or zero extend followed by truncate is always ok if the result |
| // is a truncate or noop. |
| CastType ResultCast = getCastType(SrcTy, DstTy); |
| if (ResultCast == Noop || ResultCast == Truncate) |
| return true; |
| // Otherwise we are still growing the value, we are only safe if the |
| // result will match the sign/zeroextendness of the result. |
| return ResultCast == FirstCast; |
| } |
| } |
| return false; |
| } |
| |
| static bool ValueRequiresCast(const Value *V, const Type *Ty, TargetData *TD) { |
| if (V->getType() == Ty || isa<Constant>(V)) return false; |
| if (const CastInst *CI = dyn_cast<CastInst>(V)) |
| if (isEliminableCastOfCast(CI->getOperand(0)->getType(), CI->getType(), 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(Value *V, const Type *DestTy, |
| Instruction *InsertBefore) { |
| if (V->getType() == DestTy) return V; |
| if (Constant *C = dyn_cast<Constant>(V)) |
| return ConstantExpr::getCast(C, DestTy); |
| |
| CastInst *CI = new CastInst(V, DestTy, V->getName()); |
| InsertNewInstBefore(CI, *InsertBefore); |
| return CI; |
| } |
| |
| // CastInst simplification |
| // |
| Instruction *InstCombiner::visitCastInst(CastInst &CI) { |
| Value *Src = CI.getOperand(0); |
| |
| // If the user is casting a value to the same type, eliminate this cast |
| // instruction... |
| if (CI.getType() == Src->getType()) |
| return ReplaceInstUsesWith(CI, Src); |
| |
| if (isa<UndefValue>(Src)) // cast undef -> undef |
| return ReplaceInstUsesWith(CI, UndefValue::get(CI.getType())); |
| |
| // If casting the result of another cast instruction, try to eliminate this |
| // one! |
| // |
| if (CastInst *CSrc = dyn_cast<CastInst>(Src)) { // A->B->C cast |
| Value *A = CSrc->getOperand(0); |
| if (isEliminableCastOfCast(A->getType(), CSrc->getType(), |
| CI.getType(), TD)) { |
| // This instruction now refers directly to the cast's src operand. This |
| // has a good chance of making CSrc dead. |
| CI.setOperand(0, CSrc->getOperand(0)); |
| return &CI; |
| } |
| |
| // If this is an A->B->A cast, and we are dealing with integral types, try |
| // to convert this into a logical 'and' instruction. |
| // |
| if (A->getType()->isInteger() && |
| CI.getType()->isInteger() && CSrc->getType()->isInteger() && |
| CSrc->getType()->isUnsigned() && // B->A cast must zero extend |
| CSrc->getType()->getPrimitiveSizeInBits() < |
| CI.getType()->getPrimitiveSizeInBits()&& |
| A->getType()->getPrimitiveSizeInBits() == |
| CI.getType()->getPrimitiveSizeInBits()) { |
| assert(CSrc->getType() != Type::ULongTy && |
| "Cannot have type bigger than ulong!"); |
| uint64_t AndValue = ~0ULL>>(64-CSrc->getType()->getPrimitiveSizeInBits()); |
| Constant *AndOp = ConstantUInt::get(A->getType()->getUnsignedVersion(), |
| AndValue); |
| AndOp = ConstantExpr::getCast(AndOp, A->getType()); |
| Instruction *And = BinaryOperator::createAnd(CSrc->getOperand(0), AndOp); |
| if (And->getType() != CI.getType()) { |
| And->setName(CSrc->getName()+".mask"); |
| InsertNewInstBefore(And, CI); |
| And = new CastInst(And, CI.getType()); |
| } |
| return And; |
| } |
| } |
| |
| // If this is a cast to bool, turn it into the appropriate setne instruction. |
| if (CI.getType() == Type::BoolTy) |
| return BinaryOperator::createSetNE(CI.getOperand(0), |
| Constant::getNullValue(CI.getOperand(0)->getType())); |
| |
| // If casting the result of a getelementptr instruction with no offset, turn |
| // this into a cast of the original pointer! |
| // |
| if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Src)) { |
| bool AllZeroOperands = true; |
| for (unsigned i = 1, e = GEP->getNumOperands(); i != e; ++i) |
| if (!isa<Constant>(GEP->getOperand(i)) || |
| !cast<Constant>(GEP->getOperand(i))->isNullValue()) { |
| AllZeroOperands = false; |
| break; |
| } |
| if (AllZeroOperands) { |
| CI.setOperand(0, GEP->getOperand(0)); |
| return &CI; |
| } |
| } |
| |
| // 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 (AI->hasOneUse() && !AI->isArrayAllocation()) |
| if (const PointerType *PTy = dyn_cast<PointerType>(CI.getType())) { |
| // 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()) { |
| uint64_t AllocElTySize = TD->getTypeSize(AllocElTy); |
| uint64_t CastElTySize = TD->getTypeSize(CastElTy); |
| |
| // If the allocation is for an even multiple of the cast type size |
| if (CastElTySize && (AllocElTySize % CastElTySize == 0)) { |
| Value *Amt = ConstantUInt::get(Type::UIntTy, |
| AllocElTySize/CastElTySize); |
| std::string Name = AI->getName(); AI->setName(""); |
| AllocationInst *New; |
| if (isa<MallocInst>(AI)) |
| New = new MallocInst(CastElTy, Amt, Name); |
| else |
| New = new AllocaInst(CastElTy, Amt, Name); |
| InsertNewInstBefore(New, *AI); |
| return ReplaceInstUsesWith(CI, New); |
| } |
| } |
| } |
| |
| if (SelectInst *SI = dyn_cast<SelectInst>(Src)) |
| if (Instruction *NV = FoldOpIntoSelect(CI, SI, this)) |
| return NV; |
| if (isa<PHINode>(Src)) |
| if (Instruction *NV = FoldOpIntoPhi(CI)) |
| return NV; |
| |
| // If the source value is an instruction with only this use, we can attempt to |
| // propagate the cast into the instruction. Also, only handle integral types |
| // for now. |
| if (Instruction *SrcI = dyn_cast<Instruction>(Src)) |
| if (SrcI->hasOneUse() && Src->getType()->isIntegral() && |
| CI.getType()->isInteger()) { // Don't mess with casts to bool here |
| const Type *DestTy = CI.getType(); |
| unsigned SrcBitSize = Src->getType()->getPrimitiveSizeInBits(); |
| unsigned DestBitSize = DestTy->getPrimitiveSizeInBits(); |
| |
| 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, or just changing the sign, 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(Op1, DestTy,TD) || |
| !ValueRequiresCast(Op0, DestTy, TD)) { |
| Value *Op0c = InsertOperandCastBefore(Op0, DestTy, SrcI); |
| Value *Op1c = InsertOperandCastBefore(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 (SrcBitSize == 1 && SrcI->getOpcode() == Instruction::Xor && |
| Op1 == ConstantBool::True && |
| (!Op0->hasOneUse() || !isa<SetCondInst>(Op0))) { |
| Value *New = InsertOperandCastBefore(Op0, DestTy, &CI); |
| return BinaryOperator::createXor(New, |
| ConstantInt::get(CI.getType(), 1)); |
| } |
| 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 |
| // mush 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))) { |
| Value *Op0c = InsertOperandCastBefore(Op0, DestTy, SrcI); |
| return new ShiftInst(Instruction::Shl, Op0c, Op1); |
| } |
| break; |
| case Instruction::Shr: |
| // 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 && Src->getType()->isSigned() && |
| isa<ConstantInt>(Op1)) { |
| unsigned ShiftAmt = cast<ConstantUInt>(Op1)->getValue(); |
| if (SrcBitSize > ShiftAmt && SrcBitSize-ShiftAmt >= DestBitSize) { |
| // Convert to unsigned. |
| Value *N1 = InsertOperandCastBefore(Op0, |
| Op0->getType()->getUnsignedVersion(), &CI); |
| // Insert the new shift, which is now unsigned. |
| N1 = InsertNewInstBefore(new ShiftInst(Instruction::Shr, N1, |
| Op1, Src->getName()), CI); |
| return new CastInst(N1, CI.getType()); |
| } |
| } |
| break; |
| |
| case Instruction::SetNE: |
| if (ConstantInt *Op1C = dyn_cast<ConstantInt>(Op1)) { |
| if (Op1C->getRawValue() == 0) { |
| // If the input only has the low bit set, simplify directly. |
| Constant *Not1 = |
| ConstantExpr::getNot(ConstantInt::get(Op0->getType(), 1)); |
| // cast (X != 0) to int --> X if X&~1 == 0 |
| if (MaskedValueIsZero(Op0, cast<ConstantIntegral>(Not1))) { |
| if (CI.getType() == Op0->getType()) |
| return ReplaceInstUsesWith(CI, Op0); |
| else |
| return new CastInst(Op0, CI.getType()); |
| } |
| |
| // If the input is an and with a single bit, shift then simplify. |
| ConstantInt *AndRHS; |
| if (match(Op0, m_And(m_Value(), m_ConstantInt(AndRHS)))) |
| if (AndRHS->getRawValue() && |
| (AndRHS->getRawValue() & (AndRHS->getRawValue()-1)) == 0) { |
| unsigned ShiftAmt = Log2(AndRHS->getRawValue()); |
| // Perform an unsigned shr by shiftamt. Convert input to |
| // unsigned if it is signed. |
| Value *In = Op0; |
| if (In->getType()->isSigned()) |
| In = InsertNewInstBefore(new CastInst(In, |
| In->getType()->getUnsignedVersion(), In->getName()),CI); |
| // Insert the shift to put the result in the low bit. |
| In = InsertNewInstBefore(new ShiftInst(Instruction::Shr, In, |
| ConstantInt::get(Type::UByteTy, ShiftAmt), |
| In->getName()+".lobit"), CI); |
| if (CI.getType() == In->getType()) |
| return ReplaceInstUsesWith(CI, In); |
| else |
| return new CastInst(In, CI.getType()); |
| } |
| } |
| } |
| break; |
| case Instruction::SetEQ: |
| // We if we are just checking for a seteq of a single bit and casting it |
| // to an integer. If so, shift the bit to the appropriate place then |
| // cast to integer to avoid the comparison. |
| if (ConstantInt *Op1C = dyn_cast<ConstantInt>(Op1)) { |
| // Is Op1C a power of two or zero? |
| if ((Op1C->getRawValue() & Op1C->getRawValue()-1) == 0) { |
| // cast (X == 1) to int -> X iff X has only the low bit set. |
| if (Op1C->getRawValue() == 1) { |
| Constant *Not1 = |
| ConstantExpr::getNot(ConstantInt::get(Op0->getType(), 1)); |
| if (MaskedValueIsZero(Op0, cast<ConstantIntegral>(Not1))) { |
| if (CI.getType() == Op0->getType()) |
| return ReplaceInstUsesWith(CI, Op0); |
| else |
| return new CastInst(Op0, CI.getType()); |
| } |
| } |
| } |
| } |
| break; |
| } |
| } |
| 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::Shr: |
| 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: |
| return Constant::getNullValue(I->getType()); |
| case Instruction::Shl: |
| case Instruction::Shr: |
| return Constant::getNullValue(Type::UByteTy); |
| case Instruction::And: |
| return ConstantInt::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->getOpcode() == Instruction::Cast) { |
| 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 new CastInst(NewSI, TI->getType()); |
| } |
| |
| // Only handle binary operators here. |
| if (!isa<ShiftInst>(TI) && !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); |
| } else { |
| if (MatchIsOpZero) |
| return new ShiftInst(cast<ShiftInst>(TI)->getOpcode(), MatchOp, NewSI); |
| else |
| return new ShiftInst(cast<ShiftInst>(TI)->getOpcode(), NewSI, MatchOp); |
| } |
| } |
| |
| 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 (ConstantBool *C = dyn_cast<ConstantBool>(CondVal)) |
| if (C == ConstantBool::True) |
| return ReplaceInstUsesWith(SI, TrueVal); |
| else { |
| assert(C == ConstantBool::False); |
| return ReplaceInstUsesWith(SI, 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::BoolTy) |
| if (ConstantBool *C = dyn_cast<ConstantBool>(TrueVal)) { |
| if (C == ConstantBool::True) { |
| // 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 (ConstantBool *C = dyn_cast<ConstantBool>(FalseVal)) { |
| if (C == ConstantBool::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 -> cast C to int |
| if (FalseValC->isNullValue() && TrueValC->getRawValue() == 1) { |
| return new CastInst(CondVal, SI.getType()); |
| } else if (TrueValC->isNullValue() && FalseValC->getRawValue() == 1) { |
| // select C, 0, 1 -> cast !C to int |
| Value *NotCond = |
| InsertNewInstBefore(BinaryOperator::createNot(CondVal, |
| "not."+CondVal->getName()), SI); |
| return new CastInst(NotCond, SI.getType()); |
| } |
| |
| // If one of the constants is zero (we know they can't both be) and we |
| // have a setcc 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->isNullValue() || FalseValC->isNullValue()) |
| if (Instruction *IC = dyn_cast<Instruction>(SI.getCondition())) |
| if ((IC->getOpcode() == Instruction::SetEQ || |
| IC->getOpcode() == Instruction::SetNE) && |
| 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 setne or seteq and whether the true or |
| // false val is the zero. |
| bool ShouldNotVal = !TrueValC->isNullValue(); |
| ShouldNotVal ^= IC->getOpcode() == Instruction::SetNE; |
| 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 (SetCondInst *SCI = dyn_cast<SetCondInst>(CondVal)) { |
| if (SCI->getOperand(0) == TrueVal && SCI->getOperand(1) == FalseVal) { |
| // Transform (X == Y) ? X : Y -> Y |
| if (SCI->getOpcode() == Instruction::SetEQ) |
| return ReplaceInstUsesWith(SI, FalseVal); |
| // Transform (X != Y) ? X : Y -> X |
| if (SCI->getOpcode() == Instruction::SetNE) |
| return ReplaceInstUsesWith(SI, TrueVal); |
| // NOTE: if we wanted to, this is where to detect MIN/MAX/ABS/etc. |
| |
| } else if (SCI->getOperand(0) == FalseVal && SCI->getOperand(1) == TrueVal){ |
| // Transform (X == Y) ? Y : X -> X |
| if (SCI->getOpcode() == Instruction::SetEQ) |
| return ReplaceInstUsesWith(SI, FalseVal); |
| // Transform (X != Y) ? Y : X -> Y |
| if (SCI->getOpcode() == Instruction::SetNE) |
| 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()) { |
| bool isInverse = false; |
| 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: |
| // select C, (add X, Y), (sub X, ?) |
| // We can do the transform profitably if either 'Y' = '?' or '?' is |
| // a constant. |
| if (SubOp->getOperand(1) == AddOp || |
| isa<Constant>(SubOp->getOperand(1))) { |
| Value *NegVal; |
| if (Constant *C = dyn_cast<Constant>(SubOp->getOperand(1))) { |
| NegVal = ConstantExpr::getNeg(C); |
| } else { |
| NegVal = InsertNewInstBefore( |
| BinaryOperator::createNeg(SubOp->getOperand(1)), 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); |
| std::string Name = TVI->getName(); TVI->setName(""); |
| Instruction *NewSel = |
| new SelectInst(SI.getCondition(), TVI->getOperand(2-OpToFold), C, |
| Name); |
| InsertNewInstBefore(NewSel, SI); |
| if (BinaryOperator *BO = dyn_cast<BinaryOperator>(TVI)) |
| return BinaryOperator::create(BO->getOpcode(), FalseVal, NewSel); |
| else if (ShiftInst *SI = dyn_cast<ShiftInst>(TVI)) |
| return new ShiftInst(SI->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); |
| std::string Name = FVI->getName(); FVI->setName(""); |
| Instruction *NewSel = |
| new SelectInst(SI.getCondition(), C, FVI->getOperand(2-OpToFold), |
| Name); |
| InsertNewInstBefore(NewSel, SI); |
| if (BinaryOperator *BO = dyn_cast<BinaryOperator>(FVI)) |
| return BinaryOperator::create(BO->getOpcode(), TrueVal, NewSel); |
| else if (ShiftInst *SI = dyn_cast<ShiftInst>(FVI)) |
| return new ShiftInst(SI->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; |
| } |
| |
| |
| // CallInst simplification |
| // |
| Instruction *InstCombiner::visitCallInst(CallInst &CI) { |
| // Intrinsics cannot occur in an invoke, so handle them here instead of in |
| // visitCallSite. |
| if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(&CI)) { |
| 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); |
| |
| // FIXME: Increase alignment here. |
| |
| if (ConstantInt *CI = dyn_cast<ConstantInt>(NumBytes)) |
| if (CI->getRawValue() == 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>(MI)) |
| if (GlobalVariable *GVSrc = dyn_cast<GlobalVariable>(MMI->getSource())) |
| if (GVSrc->isConstant()) { |
| Module *M = CI.getParent()->getParent()->getParent(); |
| Function *MemCpy = M->getOrInsertFunction("llvm.memcpy", |
| CI.getCalledFunction()->getFunctionType()); |
| CI.setOperand(0, MemCpy); |
| Changed = true; |
| } |
| |
| if (Changed) return &CI; |
| } else if (DbgStopPointInst *SPI = dyn_cast<DbgStopPointInst>(&CI)) { |
| // If this stoppoint is at the same source location as the previous |
| // stoppoint in the chain, it is not needed. |
| if (DbgStopPointInst *PrevSPI = |
| dyn_cast<DbgStopPointInst>(SPI->getChain())) |
| if (SPI->getLineNo() == PrevSPI->getLineNo() && |
| SPI->getColNo() == PrevSPI->getColNo()) { |
| SPI->replaceAllUsesWith(PrevSPI); |
| return EraseInstFromFunction(CI); |
| } |
| } |
| |
| return visitCallSite(&CI); |
| } |
| |
| // 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(ConstantBool::True, |
| UndefValue::get(PointerType::get(Type::BoolTy)), 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(ConstantBool::True, |
| UndefValue::get(PointerType::get(Type::BoolTy)), |
| 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(), |
| ConstantBool::True, 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->getType()->isLosslesslyConvertibleTo(Op->getType())) { |
| *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::Cast || !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(); |
| |
| // Check to see if we are changing the return type... |
| if (OldRetTy != FT->getReturnType()) { |
| if (Callee->isExternal() && |
| !OldRetTy->isLosslesslyConvertibleTo(FT->getReturnType()) && |
| !Caller->use_empty()) |
| 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); |
| bool isConvertible = (*AI)->getType()->isLosslesslyConvertibleTo(ParamTy); |
| if (Callee->isExternal() && !isConvertible) return false; |
| } |
| |
| if (FT->getNumParams() < NumActualArgs && !FT->isVarArg() && |
| Callee->isExternal()) |
| 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 { |
| Args.push_back(InsertNewInstBefore(new CastInst(*AI, ParamTy, "tmp"), |
| *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()) { |
| std::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 *Cast = new CastInst(*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, Caller->getName(), Caller); |
| cast<InvokeInst>(II)->setCallingConv(II->getCallingConv()); |
| } else { |
| NC = new CallInst(Callee, Args, 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) { |
| NV = NC = new CastInst(NC, Caller->getType(), "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->getParent()->getInstList().erase(Caller); |
| removeFromWorkList(Caller); |
| 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; |
| if (isa<CastInst>(FirstInst)) { |
| CastSrcTy = FirstInst->getOperand(0)->getType(); |
| } else if (isa<BinaryOperator>(FirstInst) || isa<ShiftInst>(FirstInst)) { |
| // Can fold binop or shift if the RHS is a constant. |
| ConstantOp = dyn_cast<Constant>(FirstInst->getOperand(1)); |
| if (ConstantOp == 0) 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->getOpcode() != FirstInst->getOpcode()) |
| return 0; |
| if (CastSrcTy) { |
| if (I->getOperand(0)->getType() != CastSrcTy) |
| return 0; // Cast operation must match. |
| } 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 (isa<CastInst>(FirstInst)) |
| return new CastInst(PhiVal, PN.getType()); |
| else if (BinaryOperator *BinOp = dyn_cast<BinaryOperator>(FirstInst)) |
| return BinaryOperator::create(BinOp->getOpcode(), PhiVal, ConstantOp); |
| else |
| return new ShiftInst(cast<ShiftInst>(FirstInst)->getOpcode(), |
| PhiVal, ConstantOp); |
| } |
| |
| /// DeadPHICycle - Return true if this PHI node is only used by a PHI node cycle |
| /// that is dead. |
| static bool DeadPHICycle(PHINode *PN, std::set<PHINode*> &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).second) |
| 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 (Value *V = hasConstantValue(&PN)) { |
| // If V is an instruction, we have to be certain that it dominates PN. |
| // However, because we don't have dom info, we can't do a perfect job. |
| if (Instruction *I = dyn_cast<Instruction>(V)) { |
| // We know that the instruction dominates the PHI if there are no undef |
| // values coming in. If the instruction is defined in the entry block, |
| // and is not an invoke, we know it is ok. |
| if (I->getParent() != &I->getParent()->getParent()->front() || |
| isa<InvokeInst>(I)) |
| for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) |
| if (isa<UndefValue>(PN.getIncomingValue(i))) { |
| V = 0; |
| break; |
| } |
| } |
| |
| if (V) |
| return ReplaceInstUsesWith(PN, V); |
| } |
| |
| // If the only user of this instruction is a cast instruction, and all of the |
| // incoming values are constants, change this PHI to merge together the casted |
| // constants. |
| if (PN.hasOneUse()) |
| if (CastInst *CI = dyn_cast<CastInst>(PN.use_back())) |
| if (CI->getType() != PN.getType()) { // noop casts will be folded |
| bool AllConstant = true; |
| for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) |
| if (!isa<Constant>(PN.getIncomingValue(i))) { |
| AllConstant = false; |
| break; |
| } |
| if (AllConstant) { |
| // Make a new PHI with all casted values. |
| PHINode *New = new PHINode(CI->getType(), PN.getName(), &PN); |
| for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) { |
| Constant *OldArg = cast<Constant>(PN.getIncomingValue(i)); |
| New->addIncoming(ConstantExpr::getCast(OldArg, New->getType()), |
| PN.getIncomingBlock(i)); |
| } |
| |
| // Update the cast instruction. |
| CI->setOperand(0, New); |
| WorkList.push_back(CI); // revisit the cast instruction to fold. |
| WorkList.push_back(New); // Make sure to revisit the new Phi |
| return &PN; // PN is now dead! |
| } |
| } |
| |
| // 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()) |
| if (PHINode *PU = dyn_cast<PHINode>(PN.use_back())) { |
| std::set<PHINode*> PotentiallyDeadPHIs; |
| PotentiallyDeadPHIs.insert(&PN); |
| if (DeadPHICycle(PU, PotentiallyDeadPHIs)) |
| return ReplaceInstUsesWith(PN, UndefValue::get(PN.getType())); |
| } |
| |
| return 0; |
| } |
| |
| static Value *InsertSignExtendToPtrTy(Value *V, const Type *DTy, |
| Instruction *InsertPoint, |
| InstCombiner *IC) { |
| unsigned PS = IC->getTargetData().getPointerSize(); |
| const Type *VTy = V->getType(); |
| if (!VTy->isSigned() && VTy->getPrimitiveSize() < PS) |
| // We must insert a cast to ensure we sign-extend. |
| V = IC->InsertNewInstBefore(new CastInst(V, VTy->getSignedVersion(), |
| V->getName()), *InsertPoint); |
| return IC->InsertNewInstBefore(new CastInst(V, DTy, V->getName()), |
| *InsertPoint); |
| } |
| |
| |
| Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) { |
| Value *PtrOp = GEP.getOperand(0); |
| // Is it 'getelementptr %P, long 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))) { |
| Value *Src = CI->getOperand(0); |
| const Type *SrcTy = Src->getType(); |
| const Type *DestTy = CI->getType(); |
| if (Src->getType()->isInteger()) { |
| if (SrcTy->getPrimitiveSizeInBits() == |
| DestTy->getPrimitiveSizeInBits()) { |
| // We can always eliminate a cast from ulong or long to the other. |
| // We can always eliminate a cast from uint to int or the other on |
| // 32-bit pointer platforms. |
| if (DestTy->getPrimitiveSizeInBits() >= TD->getPointerSizeInBits()){ |
| MadeChange = true; |
| GEP.setOperand(i, Src); |
| } |
| } else if (SrcTy->getPrimitiveSize() < DestTy->getPrimitiveSize() && |
| SrcTy->getPrimitiveSize() == 4) { |
| // We can always eliminate a cast from int to [u]long. We can |
| // eliminate a cast from uint to [u]long iff the target is a 32-bit |
| // pointer target. |
| if (SrcTy->isSigned() || |
| SrcTy->getPrimitiveSizeInBits() >= TD->getPointerSizeInBits()) { |
| MadeChange = true; |
| GEP.setOperand(i, Src); |
| } |
| } |
| } |
| } |
| // 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 (Op->getType()->getPrimitiveSize() > TD->getPointerSize()) |
| if (Constant *C = dyn_cast<Constant>(Op)) { |
| GEP.setOperand(i, ConstantExpr::getCast(C, |
| TD->getIntPtrType()->getSignedVersion())); |
| MadeChange = true; |
| } else { |
| Op = InsertNewInstBefore(new CastInst(Op, TD->getIntPtrType(), |
| Op->getName()), GEP); |
| GEP.setOperand(i, Op); |
| MadeChange = true; |
| } |
| |
| // If this is a constant idx, make sure to canonicalize it to be a signed |
| // operand, otherwise CSE and other optimizations are pessimized. |
| if (ConstantUInt *CUI = dyn_cast<ConstantUInt>(Op)) { |
| GEP.setOperand(i, ConstantExpr::getCast(CUI, |
| CUI->getType()->getSignedVersion())); |
| MadeChange = true; |
| } |
| } |
| if (MadeChange) return &GEP; |
| |
| // 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. |
| // |
| std::vector<Value*> SrcGEPOperands; |
| if (User *Src = dyn_castGetElementPtr(PtrOp)) |
| SrcGEPOperands.assign(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. |
| |
| std::vector<Value *> 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::getCast(SO1C, GO1->getType()); |
| } else if (Constant *GO1C = dyn_cast<Constant>(GO1)) { |
| GO1 = ConstantExpr::getCast(GO1C, SO1->getType()); |
| } else { |
| unsigned PS = TD->getPointerSize(); |
| if (SO1->getType()->getPrimitiveSize() == PS) { |
| // Convert GO1 to SO1's type. |
| GO1 = InsertSignExtendToPtrTy(GO1, SO1->getType(), &GEP, this); |
| |
| } else if (GO1->getType()->getPrimitiveSize() == PS) { |
| // Convert SO1 to GO1's type. |
| SO1 = InsertSignExtendToPtrTy(SO1, GO1->getType(), &GEP, this); |
| } else { |
| const Type *PT = TD->getIntPtrType(); |
| SO1 = InsertSignExtendToPtrTy(SO1, PT, &GEP, this); |
| GO1 = InsertSignExtendToPtrTy(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, 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... |
| std::vector<Constant*> 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); |
| |
| // Replace all uses of the GEP with the new constexpr... |
| return ReplaceInstUsesWith(GEP, CE); |
| } |
| } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(PtrOp)) { |
| if (CE->getOpcode() == Instruction::Cast) { |
| 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[];" |
| // |
| Constant *X = CE->getOperand(0); |
| const PointerType *CPTy = cast<PointerType>(CE->getType()); |
| if (const PointerType *XTy = dyn_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 && |
| isa<PointerType>(CE->getOperand(0)->getType())) { |
| // Transform things like: |
| // %t = getelementptr ubyte* cast ([2 x sbyte]* %str to ubyte*), uint %V |
| // into: %t1 = getelementptr [2 x sbyte*]* %str, int 0, uint %V; cast |
| Constant *X = CE->getOperand(0); |
| const Type *SrcElTy = cast<PointerType>(X->getType())->getElementType(); |
| const Type *ResElTy =cast<PointerType>(CE->getType())->getElementType(); |
| if (isa<ArrayType>(SrcElTy) && |
| TD->getTypeSize(cast<ArrayType>(SrcElTy)->getElementType()) == |
| TD->getTypeSize(ResElTy)) { |
| Value *V = InsertNewInstBefore( |
| new GetElementPtrInst(X, Constant::getNullValue(Type::IntTy), |
| GEP.getOperand(1), GEP.getName()), GEP); |
| return new CastInst(V, 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 ConstantUInt *C = dyn_cast<ConstantUInt>(AI.getArraySize())) { |
| const Type *NewTy = ArrayType::get(AI.getAllocatedType(), C->getValue()); |
| AllocationInst *New = 0; |
| |
| // Create and insert the replacement instruction... |
| if (isa<MallocInst>(AI)) |
| New = new MallocInst(NewTy, 0, AI.getName()); |
| else { |
| assert(isa<AllocaInst>(AI) && "Unknown type of allocation inst!"); |
| New = new AllocaInst(NewTy, 0, 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::IntTy); |
| 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); |
| |
| // Change free <ty>* (cast <ty2>* X to <ty>*) into free <ty2>* X |
| if (CastInst *CI = dyn_cast<CastInst>(Op)) |
| if (isa<PointerType>(CI->getOperand(0)->getType())) { |
| FI.setOperand(0, CI->getOperand(0)); |
| return &FI; |
| } |
| |
| // free undef -> unreachable. |
| if (isa<UndefValue>(Op)) { |
| // Insert a new store to null because we cannot modify the CFG here. |
| new StoreInst(ConstantBool::True, |
| UndefValue::get(PointerType::get(Type::BoolTy)), &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); |
| |
| return 0; |
| } |
| |
| |
| /// GetGEPGlobalInitializer - Given a constant, and a getelementptr |
| /// constantexpr, return the constant value being addressed by the constant |
| /// expression, or null if something is funny. |
| /// |
| static Constant *GetGEPGlobalInitializer(Constant *C, ConstantExpr *CE) { |
| if (CE->getOperand(1) != Constant::getNullValue(CE->getOperand(1)->getType())) |
| return 0; // Do not allow stepping over the value! |
| |
| // Loop over all of the operands, tracking down which value we are |
| // addressing... |
| gep_type_iterator I = gep_type_begin(CE), E = gep_type_end(CE); |
| for (++I; I != E; ++I) |
| if (const StructType *STy = dyn_cast<StructType>(*I)) { |
| ConstantUInt *CU = cast<ConstantUInt>(I.getOperand()); |
| assert(CU->getValue() < STy->getNumElements() && |
| "Struct index out of range!"); |
| unsigned El = (unsigned)CU->getValue(); |
| if (ConstantStruct *CS = dyn_cast<ConstantStruct>(C)) { |
| C = CS->getOperand(El); |
| } else if (isa<ConstantAggregateZero>(C)) { |
| C = Constant::getNullValue(STy->getElementType(El)); |
| } else if (isa<UndefValue>(C)) { |
| C = UndefValue::get(STy->getElementType(El)); |
| } else { |
| return 0; |
| } |
| } else if (ConstantInt *CI = dyn_cast<ConstantInt>(I.getOperand())) { |
| const ArrayType *ATy = cast<ArrayType>(*I); |
| if ((uint64_t)CI->getRawValue() >= ATy->getNumElements()) return 0; |
| if (ConstantArray *CA = dyn_cast<ConstantArray>(C)) |
| C = CA->getOperand((unsigned)CI->getRawValue()); |
| else if (isa<ConstantAggregateZero>(C)) |
| C = Constant::getNullValue(ATy->getElementType()); |
| else if (isa<UndefValue>(C)) |
| C = UndefValue::get(ATy->getElementType()); |
| else |
| return 0; |
| } else { |
| return 0; |
| } |
| return C; |
| } |
| |
| /// 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)) { |
| // 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) { |
| std::vector<Value*> Idxs(2, Constant::getNullValue(Type::IntTy)); |
| CastOp = ConstantExpr::getGetElementPtr(CSrc, Idxs); |
| SrcTy = cast<PointerType>(CastOp->getType()); |
| SrcPTy = SrcTy->getElementType(); |
| } |
| |
| if ((SrcPTy->isInteger() || isa<PointerType>(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().getTypeSize(SrcPTy) == |
| IC.getTargetData().getTypeSize(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 CastInst(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 (CastInst *CI = dyn_cast<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 (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(Op)) |
| if (isa<ConstantPointerNull>(GEPI->getOperand(0)) || |
| isa<UndefValue>(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->isExternal()) |
| 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->isExternal()) |
| if (Constant *V = GetGEPGlobalInitializer(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->getOpcode() == Instruction::Cast) { |
| 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; |
| } |
| |
| } else if (PHINode *PN = dyn_cast<PHINode>(Op)) { |
| // load (phi (&V1, &V2, &V3)) --> phi(load &V1, load &V2, load &V3) |
| bool Safe = PN->getParent() == LI.getParent(); |
| |
| // Scan all of the instructions between the PHI and the load to make |
| // sure there are no instructions that might possibly alter the value |
| // loaded from the PHI. |
| if (Safe) { |
| BasicBlock::iterator I = &LI; |
| for (--I; !isa<PHINode>(I); --I) |
| if (isa<StoreInst>(I) || isa<CallInst>(I)) { |
| Safe = false; |
| break; |
| } |
| } |
| |
| for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e && Safe; ++i) |
| if (!isSafeToLoadUnconditionally(PN->getIncomingValue(i), |
| PN->getIncomingBlock(i)->getTerminator())) |
| Safe = false; |
| |
| if (Safe) { |
| // Create the PHI. |
| PHINode *NewPN = new PHINode(LI.getType(), PN->getName()); |
| InsertNewInstBefore(NewPN, *PN); |
| std::map<BasicBlock*,Value*> LoadMap; // Don't insert duplicate loads |
| |
| for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) { |
| BasicBlock *BB = PN->getIncomingBlock(i); |
| Value *&TheLoad = LoadMap[BB]; |
| if (TheLoad == 0) { |
| Value *InVal = PN->getIncomingValue(i); |
| TheLoad = InsertNewInstBefore(new LoadInst(InVal, |
| InVal->getName()+".val"), |
| *BB->getTerminator()); |
| } |
| NewPN->addIncoming(TheLoad, BB); |
| } |
| return ReplaceInstUsesWith(LI, NewPN); |
| } |
| } |
| } |
| 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) { |
| std::vector<Value*> Idxs(2, Constant::getNullValue(Type::IntTy)); |
| CastOp = ConstantExpr::getGetElementPtr(CSrc, Idxs); |
| SrcTy = cast<PointerType>(CastOp->getType()); |
| SrcPTy = SrcTy->getElementType(); |
| } |
| |
| if ((SrcPTy->isInteger() || isa<PointerType>(SrcPTy)) && |
| IC.getTargetData().getTypeSize(SrcPTy) == |
| IC.getTargetData().getTypeSize(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; |
| if (Constant *C = dyn_cast<Constant>(SI.getOperand(0))) |
| NewCast = ConstantExpr::getCast(C, SrcPTy); |
| else |
| NewCast = IC.InsertNewInstBefore(new CastInst(SI.getOperand(0), |
| SrcPTy, |
| SI.getOperand(0)->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) |
| removeFromWorkList(&SI); |
| SI.eraseFromParent(); |
| ++NumCombined; |
| return 0; |
| } |
| |
| if (SI.isVolatile()) return 0; // Don't hack volatile loads. |
| |
| // 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)) |
| WorkList.push_back(U); // Dropped a use. |
| ++NumCombined; |
| } |
| return 0; // Do not modify these! |
| } |
| |
| // store undef, Ptr -> noop |
| if (isa<UndefValue>(Val)) { |
| removeFromWorkList(&SI); |
| SI.eraseFromParent(); |
| ++NumCombined; |
| return 0; |
| } |
| |
| // If the pointer destination is a cast, see if we can fold the cast into the |
| // source instead. |
| if (CastInst *CI = dyn_cast<CastInst>(Ptr)) |
| if (Instruction *Res = InstCombineStoreToCast(*this, SI)) |
| return Res; |
| if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ptr)) |
| if (CE->getOpcode() == Instruction::Cast) |
| if (Instruction *Res = InstCombineStoreToCast(*this, SI)) |
| return Res; |
| |
| return 0; |
| } |
| |
| |
| 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 setne -> seteq |
| Instruction::BinaryOps Op; Value *Y; |
| if (match(&BI, m_Br(m_SetCond(Op, m_Value(X), m_Value(Y)), |
| TrueDest, FalseDest))) |
| if ((Op == Instruction::SetNE || Op == Instruction::SetLE || |
| Op == Instruction::SetGE) && BI.getCondition()->hasOneUse()) { |
| SetCondInst *I = cast<SetCondInst>(BI.getCondition()); |
| std::string Name = I->getName(); I->setName(""); |
| Instruction::BinaryOps NewOpcode = SetCondInst::getInverseCondition(Op); |
| Value *NewSCC = BinaryOperator::create(NewOpcode, X, Y, Name, I); |
| // Swap Destinations and condition... |
| BI.setCondition(NewSCC); |
| BI.setSuccessor(0, FalseDest); |
| BI.setSuccessor(1, TrueDest); |
| removeFromWorkList(I); |
| I->getParent()->getInstList().erase(I); |
| WorkList.push_back(cast<Instruction>(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)); |
| WorkList.push_back(I); |
| return &SI; |
| } |
| } |
| return 0; |
| } |
| |
| |
| void InstCombiner::removeFromWorkList(Instruction *I) { |
| WorkList.erase(std::remove(WorkList.begin(), WorkList.end(), I), |
| WorkList.end()); |
| } |
| |
| |
| /// 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 instructions. |
| if (isa<PHINode>(I) || isa<InvokeInst>(I) || isa<CallInst>(I)) return false; |
| |
| // Do not sink alloca instructions out of the entry block. |
| if (isa<AllocaInst>(I) && I->getParent() == &DestBlock->getParent()->front()) |
| 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)) { |
| if (LI->isVolatile()) return false; // Don't sink volatile loads. |
| |
| 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; |
| |
| BasicBlock *SrcBlock = I->getParent(); |
| DestBlock->getInstList().splice(InsertPos, SrcBlock->getInstList(), I); |
| ++NumSunkInst; |
| return true; |
| } |
| |
| bool InstCombiner::runOnFunction(Function &F) { |
| bool Changed = false; |
| TD = &getAnalysis<TargetData>(); |
| |
| { |
| // Populate the worklist with the reachable instructions. |
| std::set<BasicBlock*> Visited; |
| for (df_ext_iterator<BasicBlock*> BB = df_ext_begin(&F.front(), Visited), |
| E = df_ext_end(&F.front(), Visited); BB != E; ++BB) |
| for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) |
| WorkList.push_back(I); |
| |
| // 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; |
| |
| DEBUG(std::cerr << "IC: DCE: " << *I); |
| ++NumDeadInst; |
| |
| if (!I->use_empty()) |
| I->replaceAllUsesWith(UndefValue::get(I->getType())); |
| I->eraseFromParent(); |
| } |
| } |
| } |
| |
| while (!WorkList.empty()) { |
| Instruction *I = WorkList.back(); // Get an instruction from the worklist |
| WorkList.pop_back(); |
| |
| // Check to see if we can DCE or ConstantPropagate the instruction... |
| // Check to see if we can DIE the instruction... |
| if (isInstructionTriviallyDead(I)) { |
| // Add operands to the worklist... |
| if (I->getNumOperands() < 4) |
| AddUsesToWorkList(*I); |
| ++NumDeadInst; |
| |
| DEBUG(std::cerr << "IC: DCE: " << *I); |
| |
| I->eraseFromParent(); |
| removeFromWorkList(I); |
| continue; |
| } |
| |
| // Instruction isn't dead, see if we can constant propagate it... |
| if (Constant *C = ConstantFoldInstruction(I)) { |
| Value* Ptr = I->getOperand(0); |
| if (isa<GetElementPtrInst>(I) && |
| cast<Constant>(Ptr)->isNullValue() && |
| !isa<ConstantPointerNull>(C) && |
| cast<PointerType>(Ptr->getType())->getElementType()->isSized()) { |
| // If this is a constant expr gep that is effectively computing an |
| // "offsetof", fold it into 'cast int X to T*' instead of 'gep 0, 0, 12' |
| bool isFoldableGEP = true; |
| for (unsigned i = 1, e = I->getNumOperands(); i != e; ++i) |
| if (!isa<ConstantInt>(I->getOperand(i))) |
| isFoldableGEP = false; |
| if (isFoldableGEP) { |
| uint64_t Offset = TD->getIndexedOffset(Ptr->getType(), |
| std::vector<Value*>(I->op_begin()+1, I->op_end())); |
| C = ConstantUInt::get(Type::ULongTy, Offset); |
| C = ConstantExpr::getCast(C, TD->getIntPtrType()); |
| C = ConstantExpr::getCast(C, I->getType()); |
| } |
| } |
| |
| DEBUG(std::cerr << "IC: ConstFold to: " << *C << " from: " << *I); |
| |
| // Add operands to the worklist... |
| AddUsesToWorkList(*I); |
| ReplaceInstUsesWith(*I, C); |
| |
| ++NumConstProp; |
| I->getParent()->getInstList().erase(I); |
| 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... |
| if (Instruction *Result = visit(*I)) { |
| ++NumCombined; |
| // Should we replace the old instruction with a new one? |
| if (Result != I) { |
| DEBUG(std::cerr << "IC: Old = " << *I |
| << " New = " << *Result); |
| |
| // Everything uses the new instruction now. |
| I->replaceAllUsesWith(Result); |
| |
| // Push the new instruction and any users onto the worklist. |
| WorkList.push_back(Result); |
| AddUsersToWorkList(*Result); |
| |
| // Move the name to the new instruction first... |
| std::string OldName = I->getName(); I->setName(""); |
| Result->setName(OldName); |
| |
| // 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. |
| for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) |
| if (Instruction *OpI = dyn_cast<Instruction>(I->getOperand(i))) |
| WorkList.push_back(OpI); |
| |
| // 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 { |
| DEBUG(std::cerr << "IC: MOD = " << *I); |
| |
| // 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. |
| for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) |
| if (Instruction *OpI = dyn_cast<Instruction>(I->getOperand(i))) |
| WorkList.push_back(OpI); |
| |
| // Instructions may end up in the worklist more than once. Erase all |
| // occurrances of this instruction. |
| removeFromWorkList(I); |
| I->eraseFromParent(); |
| } else { |
| WorkList.push_back(Result); |
| AddUsersToWorkList(*Result); |
| } |
| } |
| Changed = true; |
| } |
| } |
| |
| return Changed; |
| } |
| |
| FunctionPass *llvm::createInstructionCombiningPass() { |
| return new InstCombiner(); |
| } |
| |