It's not necessary to do rounding for alloca operations when the requested
alignment is equal to the stack alignment.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@40004 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Scalar/CodeGenPrepare.cpp b/lib/Transforms/Scalar/CodeGenPrepare.cpp
new file mode 100644
index 0000000..2969df3
--- /dev/null
+++ b/lib/Transforms/Scalar/CodeGenPrepare.cpp
@@ -0,0 +1,988 @@
+//===- CodeGenPrepare.cpp - Prepare a function for code generation --------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file was developed by Chris Lattner and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This pass munges the code in the input function to better prepare it for
+// SelectionDAG-based code generation. This works around limitations in it's
+// basic-block-at-a-time approach. It should eventually be removed.
+//
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "codegenprepare"
+#include "llvm/Transforms/Scalar.h"
+#include "llvm/Constants.h"
+#include "llvm/DerivedTypes.h"
+#include "llvm/Function.h"
+#include "llvm/Instructions.h"
+#include "llvm/Pass.h"
+#include "llvm/Target/TargetAsmInfo.h"
+#include "llvm/Target/TargetData.h"
+#include "llvm/Target/TargetLowering.h"
+#include "llvm/Target/TargetMachine.h"
+#include "llvm/Transforms/Utils/BasicBlockUtils.h"
+#include "llvm/Transforms/Utils/Local.h"
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/SmallSet.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/Compiler.h"
+#include "llvm/Support/GetElementPtrTypeIterator.h"
+using namespace llvm;
+
+namespace {
+ class VISIBILITY_HIDDEN CodeGenPrepare : public FunctionPass {
+ /// TLI - Keep a pointer of a TargetLowering to consult for determining
+ /// transformation profitability.
+ const TargetLowering *TLI;
+ public:
+ static char ID; // Pass identification, replacement for typeid
+ CodeGenPrepare(const TargetLowering *tli = 0) : FunctionPass((intptr_t)&ID),
+ TLI(tli) {}
+ bool runOnFunction(Function &F);
+
+ private:
+ bool EliminateMostlyEmptyBlocks(Function &F);
+ bool CanMergeBlocks(const BasicBlock *BB, const BasicBlock *DestBB) const;
+ void EliminateMostlyEmptyBlock(BasicBlock *BB);
+ bool OptimizeBlock(BasicBlock &BB);
+ bool OptimizeLoadStoreInst(Instruction *I, Value *Addr,
+ const Type *AccessTy,
+ DenseMap<Value*,Value*> &SunkAddrs);
+ };
+}
+
+char CodeGenPrepare::ID = 0;
+static RegisterPass<CodeGenPrepare> X("codegenprepare",
+ "Optimize for code generation");
+
+FunctionPass *llvm::createCodeGenPreparePass(const TargetLowering *TLI) {
+ return new CodeGenPrepare(TLI);
+}
+
+
+bool CodeGenPrepare::runOnFunction(Function &F) {
+ bool EverMadeChange = false;
+
+ // First pass, eliminate blocks that contain only PHI nodes and an
+ // unconditional branch.
+ EverMadeChange |= EliminateMostlyEmptyBlocks(F);
+
+ bool MadeChange = true;
+ while (MadeChange) {
+ MadeChange = false;
+ for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
+ MadeChange |= OptimizeBlock(*BB);
+ EverMadeChange |= MadeChange;
+ }
+ return EverMadeChange;
+}
+
+/// EliminateMostlyEmptyBlocks - eliminate blocks that contain only PHI nodes
+/// and an unconditional branch. Passes before isel (e.g. LSR/loopsimplify)
+/// often split edges in ways that are non-optimal for isel. Start by
+/// eliminating these blocks so we can split them the way we want them.
+bool CodeGenPrepare::EliminateMostlyEmptyBlocks(Function &F) {
+ bool MadeChange = false;
+ // Note that this intentionally skips the entry block.
+ for (Function::iterator I = ++F.begin(), E = F.end(); I != E; ) {
+ BasicBlock *BB = I++;
+
+ // If this block doesn't end with an uncond branch, ignore it.
+ BranchInst *BI = dyn_cast<BranchInst>(BB->getTerminator());
+ if (!BI || !BI->isUnconditional())
+ continue;
+
+ // If the instruction before the branch isn't a phi node, then other stuff
+ // is happening here.
+ BasicBlock::iterator BBI = BI;
+ if (BBI != BB->begin()) {
+ --BBI;
+ if (!isa<PHINode>(BBI)) continue;
+ }
+
+ // Do not break infinite loops.
+ BasicBlock *DestBB = BI->getSuccessor(0);
+ if (DestBB == BB)
+ continue;
+
+ if (!CanMergeBlocks(BB, DestBB))
+ continue;
+
+ EliminateMostlyEmptyBlock(BB);
+ MadeChange = true;
+ }
+ return MadeChange;
+}
+
+/// CanMergeBlocks - Return true if we can merge BB into DestBB if there is a
+/// single uncond branch between them, and BB contains no other non-phi
+/// instructions.
+bool CodeGenPrepare::CanMergeBlocks(const BasicBlock *BB,
+ const BasicBlock *DestBB) const {
+ // We only want to eliminate blocks whose phi nodes are used by phi nodes in
+ // the successor. If there are more complex condition (e.g. preheaders),
+ // don't mess around with them.
+ BasicBlock::const_iterator BBI = BB->begin();
+ while (const PHINode *PN = dyn_cast<PHINode>(BBI++)) {
+ for (Value::use_const_iterator UI = PN->use_begin(), E = PN->use_end();
+ UI != E; ++UI) {
+ const Instruction *User = cast<Instruction>(*UI);
+ if (User->getParent() != DestBB || !isa<PHINode>(User))
+ return false;
+ // If User is inside DestBB block and it is a PHINode then check
+ // incoming value. If incoming value is not from BB then this is
+ // a complex condition (e.g. preheaders) we want to avoid here.
+ if (User->getParent() == DestBB) {
+ if (const PHINode *UPN = dyn_cast<PHINode>(User))
+ for (unsigned I = 0, E = UPN->getNumIncomingValues(); I != E; ++I) {
+ Instruction *Insn = dyn_cast<Instruction>(UPN->getIncomingValue(I));
+ if (Insn && Insn->getParent() == BB &&
+ Insn->getParent() != UPN->getIncomingBlock(I))
+ return false;
+ }
+ }
+ }
+ }
+
+ // If BB and DestBB contain any common predecessors, then the phi nodes in BB
+ // and DestBB may have conflicting incoming values for the block. If so, we
+ // can't merge the block.
+ const PHINode *DestBBPN = dyn_cast<PHINode>(DestBB->begin());
+ if (!DestBBPN) return true; // no conflict.
+
+ // Collect the preds of BB.
+ SmallPtrSet<BasicBlock*, 16> BBPreds;
+ if (const PHINode *BBPN = dyn_cast<PHINode>(BB->begin())) {
+ // It is faster to get preds from a PHI than with pred_iterator.
+ for (unsigned i = 0, e = BBPN->getNumIncomingValues(); i != e; ++i)
+ BBPreds.insert(BBPN->getIncomingBlock(i));
+ } else {
+ BBPreds.insert(pred_begin(BB), pred_end(BB));
+ }
+
+ // Walk the preds of DestBB.
+ for (unsigned i = 0, e = DestBBPN->getNumIncomingValues(); i != e; ++i) {
+ BasicBlock *Pred = DestBBPN->getIncomingBlock(i);
+ if (BBPreds.count(Pred)) { // Common predecessor?
+ BBI = DestBB->begin();
+ while (const PHINode *PN = dyn_cast<PHINode>(BBI++)) {
+ const Value *V1 = PN->getIncomingValueForBlock(Pred);
+ const Value *V2 = PN->getIncomingValueForBlock(BB);
+
+ // If V2 is a phi node in BB, look up what the mapped value will be.
+ if (const PHINode *V2PN = dyn_cast<PHINode>(V2))
+ if (V2PN->getParent() == BB)
+ V2 = V2PN->getIncomingValueForBlock(Pred);
+
+ // If there is a conflict, bail out.
+ if (V1 != V2) return false;
+ }
+ }
+ }
+
+ return true;
+}
+
+
+/// EliminateMostlyEmptyBlock - Eliminate a basic block that have only phi's and
+/// an unconditional branch in it.
+void CodeGenPrepare::EliminateMostlyEmptyBlock(BasicBlock *BB) {
+ BranchInst *BI = cast<BranchInst>(BB->getTerminator());
+ BasicBlock *DestBB = BI->getSuccessor(0);
+
+ DOUT << "MERGING MOSTLY EMPTY BLOCKS - BEFORE:\n" << *BB << *DestBB;
+
+ // If the destination block has a single pred, then this is a trivial edge,
+ // just collapse it.
+ if (DestBB->getSinglePredecessor()) {
+ // If DestBB has single-entry PHI nodes, fold them.
+ while (PHINode *PN = dyn_cast<PHINode>(DestBB->begin())) {
+ PN->replaceAllUsesWith(PN->getIncomingValue(0));
+ PN->eraseFromParent();
+ }
+
+ // Splice all the PHI nodes from BB over to DestBB.
+ DestBB->getInstList().splice(DestBB->begin(), BB->getInstList(),
+ BB->begin(), BI);
+
+ // Anything that branched to BB now branches to DestBB.
+ BB->replaceAllUsesWith(DestBB);
+
+ // Nuke BB.
+ BB->eraseFromParent();
+
+ DOUT << "AFTER:\n" << *DestBB << "\n\n\n";
+ return;
+ }
+
+ // Otherwise, we have multiple predecessors of BB. Update the PHIs in DestBB
+ // to handle the new incoming edges it is about to have.
+ PHINode *PN;
+ for (BasicBlock::iterator BBI = DestBB->begin();
+ (PN = dyn_cast<PHINode>(BBI)); ++BBI) {
+ // Remove the incoming value for BB, and remember it.
+ Value *InVal = PN->removeIncomingValue(BB, false);
+
+ // Two options: either the InVal is a phi node defined in BB or it is some
+ // value that dominates BB.
+ PHINode *InValPhi = dyn_cast<PHINode>(InVal);
+ if (InValPhi && InValPhi->getParent() == BB) {
+ // Add all of the input values of the input PHI as inputs of this phi.
+ for (unsigned i = 0, e = InValPhi->getNumIncomingValues(); i != e; ++i)
+ PN->addIncoming(InValPhi->getIncomingValue(i),
+ InValPhi->getIncomingBlock(i));
+ } else {
+ // Otherwise, add one instance of the dominating value for each edge that
+ // we will be adding.
+ if (PHINode *BBPN = dyn_cast<PHINode>(BB->begin())) {
+ for (unsigned i = 0, e = BBPN->getNumIncomingValues(); i != e; ++i)
+ PN->addIncoming(InVal, BBPN->getIncomingBlock(i));
+ } else {
+ for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI)
+ PN->addIncoming(InVal, *PI);
+ }
+ }
+ }
+
+ // The PHIs are now updated, change everything that refers to BB to use
+ // DestBB and remove BB.
+ BB->replaceAllUsesWith(DestBB);
+ BB->eraseFromParent();
+
+ DOUT << "AFTER:\n" << *DestBB << "\n\n\n";
+}
+
+
+/// SplitEdgeNicely - Split the critical edge from TI to it's specified
+/// successor if it will improve codegen. We only do this if the successor has
+/// phi nodes (otherwise critical edges are ok). If there is already another
+/// predecessor of the succ that is empty (and thus has no phi nodes), use it
+/// instead of introducing a new block.
+static void SplitEdgeNicely(TerminatorInst *TI, unsigned SuccNum, Pass *P) {
+ BasicBlock *TIBB = TI->getParent();
+ BasicBlock *Dest = TI->getSuccessor(SuccNum);
+ assert(isa<PHINode>(Dest->begin()) &&
+ "This should only be called if Dest has a PHI!");
+
+ /// TIPHIValues - This array is lazily computed to determine the values of
+ /// PHIs in Dest that TI would provide.
+ std::vector<Value*> TIPHIValues;
+
+ // Check to see if Dest has any blocks that can be used as a split edge for
+ // this terminator.
+ for (pred_iterator PI = pred_begin(Dest), E = pred_end(Dest); PI != E; ++PI) {
+ BasicBlock *Pred = *PI;
+ // To be usable, the pred has to end with an uncond branch to the dest.
+ BranchInst *PredBr = dyn_cast<BranchInst>(Pred->getTerminator());
+ if (!PredBr || !PredBr->isUnconditional() ||
+ // Must be empty other than the branch.
+ &Pred->front() != PredBr ||
+ // Cannot be the entry block; its label does not get emitted.
+ Pred == &(Dest->getParent()->getEntryBlock()))
+ continue;
+
+ // Finally, since we know that Dest has phi nodes in it, we have to make
+ // sure that jumping to Pred will have the same affect as going to Dest in
+ // terms of PHI values.
+ PHINode *PN;
+ unsigned PHINo = 0;
+ bool FoundMatch = true;
+ for (BasicBlock::iterator I = Dest->begin();
+ (PN = dyn_cast<PHINode>(I)); ++I, ++PHINo) {
+ if (PHINo == TIPHIValues.size())
+ TIPHIValues.push_back(PN->getIncomingValueForBlock(TIBB));
+
+ // If the PHI entry doesn't work, we can't use this pred.
+ if (TIPHIValues[PHINo] != PN->getIncomingValueForBlock(Pred)) {
+ FoundMatch = false;
+ break;
+ }
+ }
+
+ // If we found a workable predecessor, change TI to branch to Succ.
+ if (FoundMatch) {
+ Dest->removePredecessor(TIBB);
+ TI->setSuccessor(SuccNum, Pred);
+ return;
+ }
+ }
+
+ SplitCriticalEdge(TI, SuccNum, P, true);
+}
+
+/// OptimizeNoopCopyExpression - If the specified cast instruction is a noop
+/// copy (e.g. it's casting from one pointer type to another, int->uint, or
+/// int->sbyte on PPC), sink it into user blocks to reduce the number of virtual
+/// registers that must be created and coalesced.
+///
+/// Return true if any changes are made.
+static bool OptimizeNoopCopyExpression(CastInst *CI, const TargetLowering &TLI){
+ // If this is a noop copy,
+ MVT::ValueType SrcVT = TLI.getValueType(CI->getOperand(0)->getType());
+ MVT::ValueType DstVT = TLI.getValueType(CI->getType());
+
+ // This is an fp<->int conversion?
+ if (MVT::isInteger(SrcVT) != MVT::isInteger(DstVT))
+ return false;
+
+ // If this is an extension, it will be a zero or sign extension, which
+ // isn't a noop.
+ if (SrcVT < DstVT) return false;
+
+ // If these values will be promoted, find out what they will be promoted
+ // to. This helps us consider truncates on PPC as noop copies when they
+ // are.
+ if (TLI.getTypeAction(SrcVT) == TargetLowering::Promote)
+ SrcVT = TLI.getTypeToTransformTo(SrcVT);
+ if (TLI.getTypeAction(DstVT) == TargetLowering::Promote)
+ DstVT = TLI.getTypeToTransformTo(DstVT);
+
+ // If, after promotion, these are the same types, this is a noop copy.
+ if (SrcVT != DstVT)
+ return false;
+
+ BasicBlock *DefBB = CI->getParent();
+
+ /// InsertedCasts - Only insert a cast in each block once.
+ DenseMap<BasicBlock*, CastInst*> InsertedCasts;
+
+ bool MadeChange = false;
+ for (Value::use_iterator UI = CI->use_begin(), E = CI->use_end();
+ UI != E; ) {
+ Use &TheUse = UI.getUse();
+ Instruction *User = cast<Instruction>(*UI);
+
+ // Figure out which BB this cast is used in. For PHI's this is the
+ // appropriate predecessor block.
+ BasicBlock *UserBB = User->getParent();
+ if (PHINode *PN = dyn_cast<PHINode>(User)) {
+ unsigned OpVal = UI.getOperandNo()/2;
+ UserBB = PN->getIncomingBlock(OpVal);
+ }
+
+ // Preincrement use iterator so we don't invalidate it.
+ ++UI;
+
+ // If this user is in the same block as the cast, don't change the cast.
+ if (UserBB == DefBB) continue;
+
+ // If we have already inserted a cast into this block, use it.
+ CastInst *&InsertedCast = InsertedCasts[UserBB];
+
+ if (!InsertedCast) {
+ BasicBlock::iterator InsertPt = UserBB->begin();
+ while (isa<PHINode>(InsertPt)) ++InsertPt;
+
+ InsertedCast =
+ CastInst::create(CI->getOpcode(), CI->getOperand(0), CI->getType(), "",
+ InsertPt);
+ MadeChange = true;
+ }
+
+ // Replace a use of the cast with a use of the new cast.
+ TheUse = InsertedCast;
+ }
+
+ // If we removed all uses, nuke the cast.
+ if (CI->use_empty())
+ CI->eraseFromParent();
+
+ return MadeChange;
+}
+
+/// OptimizeCmpExpression - sink the given CmpInst into user blocks to reduce
+/// the number of virtual registers that must be created and coalesced. This is
+/// a clear win except on targets with multiple condition code registers (powerPC),
+/// where it might lose; some adjustment may be wanted there.
+///
+/// Return true if any changes are made.
+static bool OptimizeCmpExpression(CmpInst *CI){
+
+ BasicBlock *DefBB = CI->getParent();
+
+ /// InsertedCmp - Only insert a cmp in each block once.
+ DenseMap<BasicBlock*, CmpInst*> InsertedCmps;
+
+ bool MadeChange = false;
+ for (Value::use_iterator UI = CI->use_begin(), E = CI->use_end();
+ UI != E; ) {
+ Use &TheUse = UI.getUse();
+ Instruction *User = cast<Instruction>(*UI);
+
+ // Preincrement use iterator so we don't invalidate it.
+ ++UI;
+
+ // Don't bother for PHI nodes.
+ if (isa<PHINode>(User))
+ continue;
+
+ // Figure out which BB this cmp is used in.
+ BasicBlock *UserBB = User->getParent();
+
+ // If this user is in the same block as the cmp, don't change the cmp.
+ if (UserBB == DefBB) continue;
+
+ // If we have already inserted a cmp into this block, use it.
+ CmpInst *&InsertedCmp = InsertedCmps[UserBB];
+
+ if (!InsertedCmp) {
+ BasicBlock::iterator InsertPt = UserBB->begin();
+ while (isa<PHINode>(InsertPt)) ++InsertPt;
+
+ InsertedCmp =
+ CmpInst::create(CI->getOpcode(), CI->getPredicate(), CI->getOperand(0),
+ CI->getOperand(1), "", InsertPt);
+ MadeChange = true;
+ }
+
+ // Replace a use of the cmp with a use of the new cmp.
+ TheUse = InsertedCmp;
+ }
+
+ // If we removed all uses, nuke the cmp.
+ if (CI->use_empty())
+ CI->eraseFromParent();
+
+ return MadeChange;
+}
+
+/// EraseDeadInstructions - Erase any dead instructions
+static void EraseDeadInstructions(Value *V) {
+ Instruction *I = dyn_cast<Instruction>(V);
+ if (!I || !I->use_empty()) return;
+
+ SmallPtrSet<Instruction*, 16> Insts;
+ Insts.insert(I);
+
+ while (!Insts.empty()) {
+ I = *Insts.begin();
+ Insts.erase(I);
+ if (isInstructionTriviallyDead(I)) {
+ for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
+ if (Instruction *U = dyn_cast<Instruction>(I->getOperand(i)))
+ Insts.insert(U);
+ I->eraseFromParent();
+ }
+ }
+}
+
+
+/// ExtAddrMode - This is an extended version of TargetLowering::AddrMode which
+/// holds actual Value*'s for register values.
+struct ExtAddrMode : public TargetLowering::AddrMode {
+ Value *BaseReg;
+ Value *ScaledReg;
+ ExtAddrMode() : BaseReg(0), ScaledReg(0) {}
+ void dump() const;
+};
+
+static std::ostream &operator<<(std::ostream &OS, const ExtAddrMode &AM) {
+ bool NeedPlus = false;
+ OS << "[";
+ if (AM.BaseGV)
+ OS << (NeedPlus ? " + " : "")
+ << "GV:%" << AM.BaseGV->getName(), NeedPlus = true;
+
+ if (AM.BaseOffs)
+ OS << (NeedPlus ? " + " : "") << AM.BaseOffs, NeedPlus = true;
+
+ if (AM.BaseReg)
+ OS << (NeedPlus ? " + " : "")
+ << "Base:%" << AM.BaseReg->getName(), NeedPlus = true;
+ if (AM.Scale)
+ OS << (NeedPlus ? " + " : "")
+ << AM.Scale << "*%" << AM.ScaledReg->getName(), NeedPlus = true;
+
+ return OS << "]";
+}
+
+void ExtAddrMode::dump() const {
+ cerr << *this << "\n";
+}
+
+static bool TryMatchingScaledValue(Value *ScaleReg, int64_t Scale,
+ const Type *AccessTy, ExtAddrMode &AddrMode,
+ SmallVector<Instruction*, 16> &AddrModeInsts,
+ const TargetLowering &TLI, unsigned Depth);
+
+/// FindMaximalLegalAddressingMode - If we can, try to merge the computation of
+/// Addr into the specified addressing mode. If Addr can't be added to AddrMode
+/// this returns false. This assumes that Addr is either a pointer type or
+/// intptr_t for the target.
+static bool FindMaximalLegalAddressingMode(Value *Addr, const Type *AccessTy,
+ ExtAddrMode &AddrMode,
+ SmallVector<Instruction*, 16> &AddrModeInsts,
+ const TargetLowering &TLI,
+ unsigned Depth) {
+
+ // If this is a global variable, fold it into the addressing mode if possible.
+ if (GlobalValue *GV = dyn_cast<GlobalValue>(Addr)) {
+ if (AddrMode.BaseGV == 0) {
+ AddrMode.BaseGV = GV;
+ if (TLI.isLegalAddressingMode(AddrMode, AccessTy))
+ return true;
+ AddrMode.BaseGV = 0;
+ }
+ } else if (ConstantInt *CI = dyn_cast<ConstantInt>(Addr)) {
+ AddrMode.BaseOffs += CI->getSExtValue();
+ if (TLI.isLegalAddressingMode(AddrMode, AccessTy))
+ return true;
+ AddrMode.BaseOffs -= CI->getSExtValue();
+ } else if (isa<ConstantPointerNull>(Addr)) {
+ return true;
+ }
+
+ // Look through constant exprs and instructions.
+ unsigned Opcode = ~0U;
+ User *AddrInst = 0;
+ if (Instruction *I = dyn_cast<Instruction>(Addr)) {
+ Opcode = I->getOpcode();
+ AddrInst = I;
+ } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Addr)) {
+ Opcode = CE->getOpcode();
+ AddrInst = CE;
+ }
+
+ // Limit recursion to avoid exponential behavior.
+ if (Depth == 5) { AddrInst = 0; Opcode = ~0U; }
+
+ // If this is really an instruction, add it to our list of related
+ // instructions.
+ if (Instruction *I = dyn_cast_or_null<Instruction>(AddrInst))
+ AddrModeInsts.push_back(I);
+
+ switch (Opcode) {
+ case Instruction::PtrToInt:
+ // PtrToInt is always a noop, as we know that the int type is pointer sized.
+ if (FindMaximalLegalAddressingMode(AddrInst->getOperand(0), AccessTy,
+ AddrMode, AddrModeInsts, TLI, Depth))
+ return true;
+ break;
+ case Instruction::IntToPtr:
+ // This inttoptr is a no-op if the integer type is pointer sized.
+ if (TLI.getValueType(AddrInst->getOperand(0)->getType()) ==
+ TLI.getPointerTy()) {
+ if (FindMaximalLegalAddressingMode(AddrInst->getOperand(0), AccessTy,
+ AddrMode, AddrModeInsts, TLI, Depth))
+ return true;
+ }
+ break;
+ case Instruction::Add: {
+ // Check to see if we can merge in the RHS then the LHS. If so, we win.
+ ExtAddrMode BackupAddrMode = AddrMode;
+ unsigned OldSize = AddrModeInsts.size();
+ if (FindMaximalLegalAddressingMode(AddrInst->getOperand(1), AccessTy,
+ AddrMode, AddrModeInsts, TLI, Depth+1) &&
+ FindMaximalLegalAddressingMode(AddrInst->getOperand(0), AccessTy,
+ AddrMode, AddrModeInsts, TLI, Depth+1))
+ return true;
+
+ // Restore the old addr mode info.
+ AddrMode = BackupAddrMode;
+ AddrModeInsts.resize(OldSize);
+
+ // Otherwise this was over-aggressive. Try merging in the LHS then the RHS.
+ if (FindMaximalLegalAddressingMode(AddrInst->getOperand(0), AccessTy,
+ AddrMode, AddrModeInsts, TLI, Depth+1) &&
+ FindMaximalLegalAddressingMode(AddrInst->getOperand(1), AccessTy,
+ AddrMode, AddrModeInsts, TLI, Depth+1))
+ return true;
+
+ // Otherwise we definitely can't merge the ADD in.
+ AddrMode = BackupAddrMode;
+ AddrModeInsts.resize(OldSize);
+ break;
+ }
+ case Instruction::Or: {
+ ConstantInt *RHS = dyn_cast<ConstantInt>(AddrInst->getOperand(1));
+ if (!RHS) break;
+ // TODO: We can handle "Or Val, Imm" iff this OR is equivalent to an ADD.
+ break;
+ }
+ case Instruction::Mul:
+ case Instruction::Shl: {
+ // Can only handle X*C and X << C, and can only handle this when the scale
+ // field is available.
+ ConstantInt *RHS = dyn_cast<ConstantInt>(AddrInst->getOperand(1));
+ if (!RHS) break;
+ int64_t Scale = RHS->getSExtValue();
+ if (Opcode == Instruction::Shl)
+ Scale = 1 << Scale;
+
+ if (TryMatchingScaledValue(AddrInst->getOperand(0), Scale, AccessTy,
+ AddrMode, AddrModeInsts, TLI, Depth))
+ return true;
+ break;
+ }
+ case Instruction::GetElementPtr: {
+ // Scan the GEP. We check it if it contains constant offsets and at most
+ // one variable offset.
+ int VariableOperand = -1;
+ unsigned VariableScale = 0;
+
+ int64_t ConstantOffset = 0;
+ const TargetData *TD = TLI.getTargetData();
+ gep_type_iterator GTI = gep_type_begin(AddrInst);
+ for (unsigned i = 1, e = AddrInst->getNumOperands(); i != e; ++i, ++GTI) {
+ if (const StructType *STy = dyn_cast<StructType>(*GTI)) {
+ const StructLayout *SL = TD->getStructLayout(STy);
+ unsigned Idx =
+ cast<ConstantInt>(AddrInst->getOperand(i))->getZExtValue();
+ ConstantOffset += SL->getElementOffset(Idx);
+ } else {
+ uint64_t TypeSize = TD->getTypeSize(GTI.getIndexedType());
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(AddrInst->getOperand(i))) {
+ ConstantOffset += CI->getSExtValue()*TypeSize;
+ } else if (TypeSize) { // Scales of zero don't do anything.
+ // We only allow one variable index at the moment.
+ if (VariableOperand != -1) {
+ VariableOperand = -2;
+ break;
+ }
+
+ // Remember the variable index.
+ VariableOperand = i;
+ VariableScale = TypeSize;
+ }
+ }
+ }
+
+ // If the GEP had multiple variable indices, punt.
+ if (VariableOperand == -2)
+ break;
+
+ // A common case is for the GEP to only do a constant offset. In this case,
+ // just add it to the disp field and check validity.
+ if (VariableOperand == -1) {
+ AddrMode.BaseOffs += ConstantOffset;
+ if (ConstantOffset == 0 || TLI.isLegalAddressingMode(AddrMode, AccessTy)){
+ // Check to see if we can fold the base pointer in too.
+ if (FindMaximalLegalAddressingMode(AddrInst->getOperand(0), AccessTy,
+ AddrMode, AddrModeInsts, TLI,
+ Depth+1))
+ return true;
+ }
+ AddrMode.BaseOffs -= ConstantOffset;
+ } else {
+ // Check that this has no base reg yet. If so, we won't have a place to
+ // put the base of the GEP (assuming it is not a null ptr).
+ bool SetBaseReg = false;
+ if (AddrMode.HasBaseReg) {
+ if (!isa<ConstantPointerNull>(AddrInst->getOperand(0)))
+ break;
+ } else {
+ AddrMode.HasBaseReg = true;
+ AddrMode.BaseReg = AddrInst->getOperand(0);
+ SetBaseReg = true;
+ }
+
+ // See if the scale amount is valid for this target.
+ AddrMode.BaseOffs += ConstantOffset;
+ if (TryMatchingScaledValue(AddrInst->getOperand(VariableOperand),
+ VariableScale, AccessTy, AddrMode,
+ AddrModeInsts, TLI, Depth)) {
+ if (!SetBaseReg) return true;
+
+ // If this match succeeded, we know that we can form an address with the
+ // GepBase as the basereg. See if we can match *more*.
+ AddrMode.HasBaseReg = false;
+ AddrMode.BaseReg = 0;
+ if (FindMaximalLegalAddressingMode(AddrInst->getOperand(0), AccessTy,
+ AddrMode, AddrModeInsts, TLI,
+ Depth+1))
+ return true;
+ // Strange, shouldn't happen. Restore the base reg and succeed the easy
+ // way.
+ AddrMode.HasBaseReg = true;
+ AddrMode.BaseReg = AddrInst->getOperand(0);
+ return true;
+ }
+
+ AddrMode.BaseOffs -= ConstantOffset;
+ if (SetBaseReg) {
+ AddrMode.HasBaseReg = false;
+ AddrMode.BaseReg = 0;
+ }
+ }
+ break;
+ }
+ }
+
+ if (Instruction *I = dyn_cast_or_null<Instruction>(AddrInst)) {
+ assert(AddrModeInsts.back() == I && "Stack imbalance");
+ AddrModeInsts.pop_back();
+ }
+
+ // Worse case, the target should support [reg] addressing modes. :)
+ if (!AddrMode.HasBaseReg) {
+ AddrMode.HasBaseReg = true;
+ // Still check for legality in case the target supports [imm] but not [i+r].
+ if (TLI.isLegalAddressingMode(AddrMode, AccessTy)) {
+ AddrMode.BaseReg = Addr;
+ return true;
+ }
+ AddrMode.HasBaseReg = false;
+ }
+
+ // If the base register is already taken, see if we can do [r+r].
+ if (AddrMode.Scale == 0) {
+ AddrMode.Scale = 1;
+ if (TLI.isLegalAddressingMode(AddrMode, AccessTy)) {
+ AddrMode.ScaledReg = Addr;
+ return true;
+ }
+ AddrMode.Scale = 0;
+ }
+ // Couldn't match.
+ return false;
+}
+
+/// TryMatchingScaledValue - Try adding ScaleReg*Scale to the specified
+/// addressing mode. Return true if this addr mode is legal for the target,
+/// false if not.
+static bool TryMatchingScaledValue(Value *ScaleReg, int64_t Scale,
+ const Type *AccessTy, ExtAddrMode &AddrMode,
+ SmallVector<Instruction*, 16> &AddrModeInsts,
+ const TargetLowering &TLI, unsigned Depth) {
+ // If we already have a scale of this value, we can add to it, otherwise, we
+ // need an available scale field.
+ if (AddrMode.Scale != 0 && AddrMode.ScaledReg != ScaleReg)
+ return false;
+
+ ExtAddrMode InputAddrMode = AddrMode;
+
+ // Add scale to turn X*4+X*3 -> X*7. This could also do things like
+ // [A+B + A*7] -> [B+A*8].
+ AddrMode.Scale += Scale;
+ AddrMode.ScaledReg = ScaleReg;
+
+ if (TLI.isLegalAddressingMode(AddrMode, AccessTy)) {
+ // Okay, we decided that we can add ScaleReg+Scale to AddrMode. Check now
+ // to see if ScaleReg is actually X+C. If so, we can turn this into adding
+ // X*Scale + C*Scale to addr mode.
+ BinaryOperator *BinOp = dyn_cast<BinaryOperator>(ScaleReg);
+ if (BinOp && BinOp->getOpcode() == Instruction::Add &&
+ isa<ConstantInt>(BinOp->getOperand(1)) && InputAddrMode.ScaledReg ==0) {
+
+ InputAddrMode.Scale = Scale;
+ InputAddrMode.ScaledReg = BinOp->getOperand(0);
+ InputAddrMode.BaseOffs +=
+ cast<ConstantInt>(BinOp->getOperand(1))->getSExtValue()*Scale;
+ if (TLI.isLegalAddressingMode(InputAddrMode, AccessTy)) {
+ AddrModeInsts.push_back(BinOp);
+ AddrMode = InputAddrMode;
+ return true;
+ }
+ }
+
+ // Otherwise, not (x+c)*scale, just return what we have.
+ return true;
+ }
+
+ // Otherwise, back this attempt out.
+ AddrMode.Scale -= Scale;
+ if (AddrMode.Scale == 0) AddrMode.ScaledReg = 0;
+
+ return false;
+}
+
+
+/// IsNonLocalValue - Return true if the specified values are defined in a
+/// different basic block than BB.
+static bool IsNonLocalValue(Value *V, BasicBlock *BB) {
+ if (Instruction *I = dyn_cast<Instruction>(V))
+ return I->getParent() != BB;
+ return false;
+}
+
+/// OptimizeLoadStoreInst - Load and Store Instructions have often have
+/// addressing modes that can do significant amounts of computation. As such,
+/// instruction selection will try to get the load or store to do as much
+/// computation as possible for the program. The problem is that isel can only
+/// see within a single block. As such, we sink as much legal addressing mode
+/// stuff into the block as possible.
+bool CodeGenPrepare::OptimizeLoadStoreInst(Instruction *LdStInst, Value *Addr,
+ const Type *AccessTy,
+ DenseMap<Value*,Value*> &SunkAddrs) {
+ // Figure out what addressing mode will be built up for this operation.
+ SmallVector<Instruction*, 16> AddrModeInsts;
+ ExtAddrMode AddrMode;
+ bool Success = FindMaximalLegalAddressingMode(Addr, AccessTy, AddrMode,
+ AddrModeInsts, *TLI, 0);
+ Success = Success; assert(Success && "Couldn't select *anything*?");
+
+ // Check to see if any of the instructions supersumed by this addr mode are
+ // non-local to I's BB.
+ bool AnyNonLocal = false;
+ for (unsigned i = 0, e = AddrModeInsts.size(); i != e; ++i) {
+ if (IsNonLocalValue(AddrModeInsts[i], LdStInst->getParent())) {
+ AnyNonLocal = true;
+ break;
+ }
+ }
+
+ // If all the instructions matched are already in this BB, don't do anything.
+ if (!AnyNonLocal) {
+ DEBUG(cerr << "CGP: Found local addrmode: " << AddrMode << "\n");
+ return false;
+ }
+
+ // Insert this computation right after this user. Since our caller is
+ // scanning from the top of the BB to the bottom, reuse of the expr are
+ // guaranteed to happen later.
+ BasicBlock::iterator InsertPt = LdStInst;
+
+ // Now that we determined the addressing expression we want to use and know
+ // that we have to sink it into this block. Check to see if we have already
+ // done this for some other load/store instr in this block. If so, reuse the
+ // computation.
+ Value *&SunkAddr = SunkAddrs[Addr];
+ if (SunkAddr) {
+ DEBUG(cerr << "CGP: Reusing nonlocal addrmode: " << AddrMode << "\n");
+ if (SunkAddr->getType() != Addr->getType())
+ SunkAddr = new BitCastInst(SunkAddr, Addr->getType(), "tmp", InsertPt);
+ } else {
+ DEBUG(cerr << "CGP: SINKING nonlocal addrmode: " << AddrMode << "\n");
+ const Type *IntPtrTy = TLI->getTargetData()->getIntPtrType();
+
+ Value *Result = 0;
+ // Start with the scale value.
+ if (AddrMode.Scale) {
+ Value *V = AddrMode.ScaledReg;
+ if (V->getType() == IntPtrTy) {
+ // done.
+ } else if (isa<PointerType>(V->getType())) {
+ V = new PtrToIntInst(V, IntPtrTy, "sunkaddr", InsertPt);
+ } else if (cast<IntegerType>(IntPtrTy)->getBitWidth() <
+ cast<IntegerType>(V->getType())->getBitWidth()) {
+ V = new TruncInst(V, IntPtrTy, "sunkaddr", InsertPt);
+ } else {
+ V = new SExtInst(V, IntPtrTy, "sunkaddr", InsertPt);
+ }
+ if (AddrMode.Scale != 1)
+ V = BinaryOperator::createMul(V, ConstantInt::get(IntPtrTy,
+ AddrMode.Scale),
+ "sunkaddr", InsertPt);
+ Result = V;
+ }
+
+ // Add in the base register.
+ if (AddrMode.BaseReg) {
+ Value *V = AddrMode.BaseReg;
+ if (V->getType() != IntPtrTy)
+ V = new PtrToIntInst(V, IntPtrTy, "sunkaddr", InsertPt);
+ if (Result)
+ Result = BinaryOperator::createAdd(Result, V, "sunkaddr", InsertPt);
+ else
+ Result = V;
+ }
+
+ // Add in the BaseGV if present.
+ if (AddrMode.BaseGV) {
+ Value *V = new PtrToIntInst(AddrMode.BaseGV, IntPtrTy, "sunkaddr",
+ InsertPt);
+ if (Result)
+ Result = BinaryOperator::createAdd(Result, V, "sunkaddr", InsertPt);
+ else
+ Result = V;
+ }
+
+ // Add in the Base Offset if present.
+ if (AddrMode.BaseOffs) {
+ Value *V = ConstantInt::get(IntPtrTy, AddrMode.BaseOffs);
+ if (Result)
+ Result = BinaryOperator::createAdd(Result, V, "sunkaddr", InsertPt);
+ else
+ Result = V;
+ }
+
+ if (Result == 0)
+ SunkAddr = Constant::getNullValue(Addr->getType());
+ else
+ SunkAddr = new IntToPtrInst(Result, Addr->getType(), "sunkaddr",InsertPt);
+ }
+
+ LdStInst->replaceUsesOfWith(Addr, SunkAddr);
+
+ if (Addr->use_empty())
+ EraseDeadInstructions(Addr);
+ return true;
+}
+
+// In this pass we look for GEP and cast instructions that are used
+// across basic blocks and rewrite them to improve basic-block-at-a-time
+// selection.
+bool CodeGenPrepare::OptimizeBlock(BasicBlock &BB) {
+ bool MadeChange = false;
+
+ // Split all critical edges where the dest block has a PHI and where the phi
+ // has shared immediate operands.
+ TerminatorInst *BBTI = BB.getTerminator();
+ if (BBTI->getNumSuccessors() > 1) {
+ for (unsigned i = 0, e = BBTI->getNumSuccessors(); i != e; ++i)
+ if (isa<PHINode>(BBTI->getSuccessor(i)->begin()) &&
+ isCriticalEdge(BBTI, i, true))
+ SplitEdgeNicely(BBTI, i, this);
+ }
+
+
+ // Keep track of non-local addresses that have been sunk into this block.
+ // This allows us to avoid inserting duplicate code for blocks with multiple
+ // load/stores of the same address.
+ DenseMap<Value*, Value*> SunkAddrs;
+
+ for (BasicBlock::iterator BBI = BB.begin(), E = BB.end(); BBI != E; ) {
+ Instruction *I = BBI++;
+
+ if (CastInst *CI = dyn_cast<CastInst>(I)) {
+ // If the source of the cast is a constant, then this should have
+ // already been constant folded. The only reason NOT to constant fold
+ // it is if something (e.g. LSR) was careful to place the constant
+ // evaluation in a block other than then one that uses it (e.g. to hoist
+ // the address of globals out of a loop). If this is the case, we don't
+ // want to forward-subst the cast.
+ if (isa<Constant>(CI->getOperand(0)))
+ continue;
+
+ if (TLI)
+ MadeChange |= OptimizeNoopCopyExpression(CI, *TLI);
+ } else if (CmpInst *CI = dyn_cast<CmpInst>(I)) {
+ MadeChange |= OptimizeCmpExpression(CI);
+ } else if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
+ if (TLI)
+ MadeChange |= OptimizeLoadStoreInst(I, I->getOperand(0), LI->getType(),
+ SunkAddrs);
+ } else if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
+ if (TLI)
+ MadeChange |= OptimizeLoadStoreInst(I, SI->getOperand(1),
+ SI->getOperand(0)->getType(),
+ SunkAddrs);
+ } else if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(I)) {
+ if (GEPI->hasAllZeroIndices()) {
+ /// The GEP operand must be a pointer, so must its result -> BitCast
+ Instruction *NC = new BitCastInst(GEPI->getOperand(0), GEPI->getType(),
+ GEPI->getName(), GEPI);
+ GEPI->replaceAllUsesWith(NC);
+ GEPI->eraseFromParent();
+ MadeChange = true;
+ BBI = NC;
+ }
+ } else if (CallInst *CI = dyn_cast<CallInst>(I)) {
+ // If we found an inline asm expession, and if the target knows how to
+ // lower it to normal LLVM code, do so now.
+ if (TLI && isa<InlineAsm>(CI->getCalledValue()))
+ if (const TargetAsmInfo *TAI =
+ TLI->getTargetMachine().getTargetAsmInfo()) {
+ if (TAI->ExpandInlineAsm(CI))
+ BBI = BB.begin();
+ }
+ }
+ }
+
+ return MadeChange;
+}
+