| //===- IndVarSimplify.cpp - Induction Variable Elimination ----------------===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This transformation analyzes and transforms the induction variables (and |
| // computations derived from them) into simpler forms suitable for subsequent |
| // analysis and transformation. |
| // |
| // This transformation makes the following changes to each loop with an |
| // identifiable induction variable: |
| // 1. All loops are transformed to have a SINGLE canonical induction variable |
| // which starts at zero and steps by one. |
| // 2. The canonical induction variable is guaranteed to be the first PHI node |
| // in the loop header block. |
| // 3. Any pointer arithmetic recurrences are raised to use array subscripts. |
| // |
| // If the trip count of a loop is computable, this pass also makes the following |
| // changes: |
| // 1. The exit condition for the loop is canonicalized to compare the |
| // induction value against the exit value. This turns loops like: |
| // 'for (i = 7; i*i < 1000; ++i)' into 'for (i = 0; i != 25; ++i)' |
| // 2. Any use outside of the loop of an expression derived from the indvar |
| // is changed to compute the derived value outside of the loop, eliminating |
| // the dependence on the exit value of the induction variable. If the only |
| // purpose of the loop is to compute the exit value of some derived |
| // expression, this transformation will make the loop dead. |
| // |
| // This transformation should be followed by strength reduction after all of the |
| // desired loop transformations have been performed. Additionally, on targets |
| // where it is profitable, the loop could be transformed to count down to zero |
| // (the "do loop" optimization). |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #define DEBUG_TYPE "indvars" |
| #include "llvm/Transforms/Scalar.h" |
| #include "llvm/BasicBlock.h" |
| #include "llvm/Constants.h" |
| #include "llvm/Instructions.h" |
| #include "llvm/Type.h" |
| #include "llvm/Analysis/ScalarEvolutionExpander.h" |
| #include "llvm/Analysis/LoopInfo.h" |
| #include "llvm/Analysis/LoopPass.h" |
| #include "llvm/Support/CFG.h" |
| #include "llvm/Support/Compiler.h" |
| #include "llvm/Support/Debug.h" |
| #include "llvm/Support/GetElementPtrTypeIterator.h" |
| #include "llvm/Target/TargetData.h" |
| #include "llvm/Transforms/Utils/Local.h" |
| #include "llvm/Support/CommandLine.h" |
| #include "llvm/ADT/SmallVector.h" |
| #include "llvm/ADT/SetVector.h" |
| #include "llvm/ADT/SmallPtrSet.h" |
| #include "llvm/ADT/Statistic.h" |
| using namespace llvm; |
| |
| STATISTIC(NumRemoved , "Number of aux indvars removed"); |
| STATISTIC(NumInserted, "Number of canonical indvars added"); |
| STATISTIC(NumReplaced, "Number of exit values replaced"); |
| STATISTIC(NumLFTR , "Number of loop exit tests replaced"); |
| |
| namespace { |
| class VISIBILITY_HIDDEN IndVarSimplify : public LoopPass { |
| LoopInfo *LI; |
| TargetData *TD; |
| ScalarEvolution *SE; |
| bool Changed; |
| public: |
| |
| static char ID; // Pass identification, replacement for typeid |
| IndVarSimplify() : LoopPass(&ID) {} |
| |
| virtual bool runOnLoop(Loop *L, LPPassManager &LPM); |
| |
| virtual void getAnalysisUsage(AnalysisUsage &AU) const { |
| AU.addRequired<ScalarEvolution>(); |
| AU.addRequiredID(LCSSAID); |
| AU.addRequiredID(LoopSimplifyID); |
| AU.addRequired<LoopInfo>(); |
| AU.addRequired<TargetData>(); |
| AU.addPreserved<ScalarEvolution>(); |
| AU.addPreservedID(LoopSimplifyID); |
| AU.addPreservedID(LCSSAID); |
| AU.setPreservesCFG(); |
| } |
| |
| private: |
| |
| void RewriteNonIntegerIVs(Loop *L); |
| |
| void LinearFunctionTestReplace(Loop *L, SCEVHandle BackedgeTakenCount, |
| Value *IndVar, |
| BasicBlock *ExitingBlock, |
| BranchInst *BI, |
| SCEVExpander &Rewriter); |
| void RewriteLoopExitValues(Loop *L, const SCEV *BackedgeTakenCount); |
| |
| void DeleteTriviallyDeadInstructions(SmallPtrSet<Instruction*, 16> &Insts); |
| |
| void HandleFloatingPointIV(Loop *L, PHINode *PH, |
| SmallPtrSet<Instruction*, 16> &DeadInsts); |
| }; |
| } |
| |
| char IndVarSimplify::ID = 0; |
| static RegisterPass<IndVarSimplify> |
| X("indvars", "Canonicalize Induction Variables"); |
| |
| Pass *llvm::createIndVarSimplifyPass() { |
| return new IndVarSimplify(); |
| } |
| |
| /// DeleteTriviallyDeadInstructions - If any of the instructions is the |
| /// specified set are trivially dead, delete them and see if this makes any of |
| /// their operands subsequently dead. |
| void IndVarSimplify:: |
| DeleteTriviallyDeadInstructions(SmallPtrSet<Instruction*, 16> &Insts) { |
| while (!Insts.empty()) { |
| Instruction *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); |
| SE->deleteValueFromRecords(I); |
| DOUT << "INDVARS: Deleting: " << *I; |
| I->eraseFromParent(); |
| Changed = true; |
| } |
| } |
| } |
| |
| /// LinearFunctionTestReplace - This method rewrites the exit condition of the |
| /// loop to be a canonical != comparison against the incremented loop induction |
| /// variable. This pass is able to rewrite the exit tests of any loop where the |
| /// SCEV analysis can determine a loop-invariant trip count of the loop, which |
| /// is actually a much broader range than just linear tests. |
| void IndVarSimplify::LinearFunctionTestReplace(Loop *L, |
| SCEVHandle BackedgeTakenCount, |
| Value *IndVar, |
| BasicBlock *ExitingBlock, |
| BranchInst *BI, |
| SCEVExpander &Rewriter) { |
| // If the exiting block is not the same as the backedge block, we must compare |
| // against the preincremented value, otherwise we prefer to compare against |
| // the post-incremented value. |
| Value *CmpIndVar; |
| SCEVHandle RHS = BackedgeTakenCount; |
| if (ExitingBlock == L->getLoopLatch()) { |
| // Add one to the "backedge-taken" count to get the trip count. |
| // If this addition may overflow, we have to be more pessimistic and |
| // cast the induction variable before doing the add. |
| SCEVHandle Zero = SE->getIntegerSCEV(0, BackedgeTakenCount->getType()); |
| SCEVHandle N = |
| SE->getAddExpr(BackedgeTakenCount, |
| SE->getIntegerSCEV(1, BackedgeTakenCount->getType())); |
| if ((isa<SCEVConstant>(N) && !N->isZero()) || |
| SE->isLoopGuardedByCond(L, ICmpInst::ICMP_NE, N, Zero)) { |
| // No overflow. Cast the sum. |
| RHS = SE->getTruncateOrZeroExtend(N, IndVar->getType()); |
| } else { |
| // Potential overflow. Cast before doing the add. |
| RHS = SE->getTruncateOrZeroExtend(BackedgeTakenCount, |
| IndVar->getType()); |
| RHS = SE->getAddExpr(RHS, |
| SE->getIntegerSCEV(1, IndVar->getType())); |
| } |
| |
| // The BackedgeTaken expression contains the number of times that the |
| // backedge branches to the loop header. This is one less than the |
| // number of times the loop executes, so use the incremented indvar. |
| CmpIndVar = L->getCanonicalInductionVariableIncrement(); |
| } else { |
| // We have to use the preincremented value... |
| RHS = SE->getTruncateOrZeroExtend(BackedgeTakenCount, |
| IndVar->getType()); |
| CmpIndVar = IndVar; |
| } |
| |
| // Expand the code for the iteration count into the preheader of the loop. |
| BasicBlock *Preheader = L->getLoopPreheader(); |
| Value *ExitCnt = Rewriter.expandCodeFor(RHS, IndVar->getType(), |
| Preheader->getTerminator()); |
| |
| // Insert a new icmp_ne or icmp_eq instruction before the branch. |
| ICmpInst::Predicate Opcode; |
| if (L->contains(BI->getSuccessor(0))) |
| Opcode = ICmpInst::ICMP_NE; |
| else |
| Opcode = ICmpInst::ICMP_EQ; |
| |
| DOUT << "INDVARS: Rewriting loop exit condition to:\n" |
| << " LHS:" << *CmpIndVar // includes a newline |
| << " op:\t" |
| << (Opcode == ICmpInst::ICMP_NE ? "!=" : "==") << "\n" |
| << " RHS:\t" << *RHS << "\n"; |
| |
| Value *Cond = new ICmpInst(Opcode, CmpIndVar, ExitCnt, "exitcond", BI); |
| BI->setCondition(Cond); |
| ++NumLFTR; |
| Changed = true; |
| } |
| |
| /// RewriteLoopExitValues - Check to see if this loop has a computable |
| /// loop-invariant execution count. If so, this means that we can compute the |
| /// final value of any expressions that are recurrent in the loop, and |
| /// substitute the exit values from the loop into any instructions outside of |
| /// the loop that use the final values of the current expressions. |
| void IndVarSimplify::RewriteLoopExitValues(Loop *L, |
| const SCEV *BackedgeTakenCount) { |
| BasicBlock *Preheader = L->getLoopPreheader(); |
| |
| // Scan all of the instructions in the loop, looking at those that have |
| // extra-loop users and which are recurrences. |
| SCEVExpander Rewriter(*SE, *LI, *TD); |
| |
| // We insert the code into the preheader of the loop if the loop contains |
| // multiple exit blocks, or in the exit block if there is exactly one. |
| BasicBlock *BlockToInsertInto; |
| SmallVector<BasicBlock*, 8> ExitBlocks; |
| L->getUniqueExitBlocks(ExitBlocks); |
| if (ExitBlocks.size() == 1) |
| BlockToInsertInto = ExitBlocks[0]; |
| else |
| BlockToInsertInto = Preheader; |
| BasicBlock::iterator InsertPt = BlockToInsertInto->getFirstNonPHI(); |
| |
| bool HasConstantItCount = isa<SCEVConstant>(BackedgeTakenCount); |
| |
| SmallPtrSet<Instruction*, 16> InstructionsToDelete; |
| std::map<Instruction*, Value*> ExitValues; |
| |
| // Find all values that are computed inside the loop, but used outside of it. |
| // Because of LCSSA, these values will only occur in LCSSA PHI Nodes. Scan |
| // the exit blocks of the loop to find them. |
| for (unsigned i = 0, e = ExitBlocks.size(); i != e; ++i) { |
| BasicBlock *ExitBB = ExitBlocks[i]; |
| |
| // If there are no PHI nodes in this exit block, then no values defined |
| // inside the loop are used on this path, skip it. |
| PHINode *PN = dyn_cast<PHINode>(ExitBB->begin()); |
| if (!PN) continue; |
| |
| unsigned NumPreds = PN->getNumIncomingValues(); |
| |
| // Iterate over all of the PHI nodes. |
| BasicBlock::iterator BBI = ExitBB->begin(); |
| while ((PN = dyn_cast<PHINode>(BBI++))) { |
| |
| // Iterate over all of the values in all the PHI nodes. |
| for (unsigned i = 0; i != NumPreds; ++i) { |
| // If the value being merged in is not integer or is not defined |
| // in the loop, skip it. |
| Value *InVal = PN->getIncomingValue(i); |
| if (!isa<Instruction>(InVal) || |
| // SCEV only supports integer expressions for now. |
| (!isa<IntegerType>(InVal->getType()) && |
| !isa<PointerType>(InVal->getType()))) |
| continue; |
| |
| // If this pred is for a subloop, not L itself, skip it. |
| if (LI->getLoopFor(PN->getIncomingBlock(i)) != L) |
| continue; // The Block is in a subloop, skip it. |
| |
| // Check that InVal is defined in the loop. |
| Instruction *Inst = cast<Instruction>(InVal); |
| if (!L->contains(Inst->getParent())) |
| continue; |
| |
| // We require that this value either have a computable evolution or that |
| // the loop have a constant iteration count. In the case where the loop |
| // has a constant iteration count, we can sometimes force evaluation of |
| // the exit value through brute force. |
| SCEVHandle SH = SE->getSCEV(Inst); |
| if (!SH->hasComputableLoopEvolution(L) && !HasConstantItCount) |
| continue; // Cannot get exit evolution for the loop value. |
| |
| // Okay, this instruction has a user outside of the current loop |
| // and varies predictably *inside* the loop. Evaluate the value it |
| // contains when the loop exits, if possible. |
| SCEVHandle ExitValue = SE->getSCEVAtScope(Inst, L->getParentLoop()); |
| if (isa<SCEVCouldNotCompute>(ExitValue) || |
| !ExitValue->isLoopInvariant(L)) |
| continue; |
| |
| Changed = true; |
| ++NumReplaced; |
| |
| // See if we already computed the exit value for the instruction, if so, |
| // just reuse it. |
| Value *&ExitVal = ExitValues[Inst]; |
| if (!ExitVal) |
| ExitVal = Rewriter.expandCodeFor(ExitValue, PN->getType(), InsertPt); |
| |
| DOUT << "INDVARS: RLEV: AfterLoopVal = " << *ExitVal |
| << " LoopVal = " << *Inst << "\n"; |
| |
| PN->setIncomingValue(i, ExitVal); |
| |
| // If this instruction is dead now, schedule it to be removed. |
| if (Inst->use_empty()) |
| InstructionsToDelete.insert(Inst); |
| |
| // See if this is a single-entry LCSSA PHI node. If so, we can (and |
| // have to) remove |
| // the PHI entirely. This is safe, because the NewVal won't be variant |
| // in the loop, so we don't need an LCSSA phi node anymore. |
| if (NumPreds == 1) { |
| SE->deleteValueFromRecords(PN); |
| PN->replaceAllUsesWith(ExitVal); |
| PN->eraseFromParent(); |
| break; |
| } |
| } |
| } |
| } |
| |
| DeleteTriviallyDeadInstructions(InstructionsToDelete); |
| } |
| |
| void IndVarSimplify::RewriteNonIntegerIVs(Loop *L) { |
| // First step. Check to see if there are any floating-point recurrences. |
| // If there are, change them into integer recurrences, permitting analysis by |
| // the SCEV routines. |
| // |
| BasicBlock *Header = L->getHeader(); |
| |
| SmallPtrSet<Instruction*, 16> DeadInsts; |
| for (BasicBlock::iterator I = Header->begin(); isa<PHINode>(I); ++I) { |
| PHINode *PN = cast<PHINode>(I); |
| HandleFloatingPointIV(L, PN, DeadInsts); |
| } |
| |
| // If the loop previously had floating-point IV, ScalarEvolution |
| // may not have been able to compute a trip count. Now that we've done some |
| // re-writing, the trip count may be computable. |
| if (Changed) |
| SE->forgetLoopBackedgeTakenCount(L); |
| |
| if (!DeadInsts.empty()) |
| DeleteTriviallyDeadInstructions(DeadInsts); |
| } |
| |
| /// getEffectiveIndvarType - Determine the widest type that the |
| /// induction-variable PHINode Phi is cast to. |
| /// |
| static const Type *getEffectiveIndvarType(const PHINode *Phi, |
| const TargetData *TD) { |
| const Type *Ty = Phi->getType(); |
| |
| for (Value::use_const_iterator UI = Phi->use_begin(), UE = Phi->use_end(); |
| UI != UE; ++UI) { |
| const Type *CandidateType = NULL; |
| if (const ZExtInst *ZI = dyn_cast<ZExtInst>(UI)) |
| CandidateType = ZI->getDestTy(); |
| else if (const SExtInst *SI = dyn_cast<SExtInst>(UI)) |
| CandidateType = SI->getDestTy(); |
| if (CandidateType && |
| TD->getTypeSizeInBits(CandidateType) > TD->getTypeSizeInBits(Ty)) |
| Ty = CandidateType; |
| } |
| |
| return Ty; |
| } |
| |
| /// TestOrigIVForWrap - Analyze the original induction variable |
| /// that controls the loop's iteration to determine whether it |
| /// would ever undergo signed or unsigned overflow. Also, check |
| /// whether an induction variable in the same type that starts |
| /// at 0 would undergo signed overflow. |
| /// |
| /// In addition to setting the NoSignedWrap and NoUnsignedWrap |
| /// variables to true when appropriate (they are not set to false here), |
| /// return the PHI for this induction variable. Also record the initial |
| /// and final values and the increment; these are not meaningful unless |
| /// either NoSignedWrap or NoUnsignedWrap is true, and are always meaningful |
| /// in that case, although the final value may be 0 indicating a nonconstant. |
| /// |
| /// TODO: This duplicates a fair amount of ScalarEvolution logic. |
| /// Perhaps this can be merged with |
| /// ScalarEvolution::getBackedgeTakenCount |
| /// and/or ScalarEvolution::get{Sign,Zero}ExtendExpr. |
| /// |
| static const PHINode *TestOrigIVForWrap(const Loop *L, |
| const BranchInst *BI, |
| const Instruction *OrigCond, |
| const TargetData *TD, |
| bool &NoSignedWrap, |
| bool &NoUnsignedWrap, |
| const ConstantInt* &InitialVal, |
| const ConstantInt* &IncrVal, |
| const ConstantInt* &LimitVal) { |
| // Verify that the loop is sane and find the exit condition. |
| const ICmpInst *Cmp = dyn_cast<ICmpInst>(OrigCond); |
| if (!Cmp) return 0; |
| |
| const Value *CmpLHS = Cmp->getOperand(0); |
| const Value *CmpRHS = Cmp->getOperand(1); |
| const BasicBlock *TrueBB = BI->getSuccessor(0); |
| const BasicBlock *FalseBB = BI->getSuccessor(1); |
| ICmpInst::Predicate Pred = Cmp->getPredicate(); |
| |
| // Canonicalize a constant to the RHS. |
| if (isa<ConstantInt>(CmpLHS)) { |
| Pred = ICmpInst::getSwappedPredicate(Pred); |
| std::swap(CmpLHS, CmpRHS); |
| } |
| // Canonicalize SLE to SLT. |
| if (Pred == ICmpInst::ICMP_SLE) |
| if (const ConstantInt *CI = dyn_cast<ConstantInt>(CmpRHS)) |
| if (!CI->getValue().isMaxSignedValue()) { |
| CmpRHS = ConstantInt::get(CI->getValue() + 1); |
| Pred = ICmpInst::ICMP_SLT; |
| } |
| // Canonicalize SGT to SGE. |
| if (Pred == ICmpInst::ICMP_SGT) |
| if (const ConstantInt *CI = dyn_cast<ConstantInt>(CmpRHS)) |
| if (!CI->getValue().isMaxSignedValue()) { |
| CmpRHS = ConstantInt::get(CI->getValue() + 1); |
| Pred = ICmpInst::ICMP_SGE; |
| } |
| // Canonicalize SGE to SLT. |
| if (Pred == ICmpInst::ICMP_SGE) { |
| std::swap(TrueBB, FalseBB); |
| Pred = ICmpInst::ICMP_SLT; |
| } |
| // Canonicalize ULE to ULT. |
| if (Pred == ICmpInst::ICMP_ULE) |
| if (const ConstantInt *CI = dyn_cast<ConstantInt>(CmpRHS)) |
| if (!CI->getValue().isMaxValue()) { |
| CmpRHS = ConstantInt::get(CI->getValue() + 1); |
| Pred = ICmpInst::ICMP_ULT; |
| } |
| // Canonicalize UGT to UGE. |
| if (Pred == ICmpInst::ICMP_UGT) |
| if (const ConstantInt *CI = dyn_cast<ConstantInt>(CmpRHS)) |
| if (!CI->getValue().isMaxValue()) { |
| CmpRHS = ConstantInt::get(CI->getValue() + 1); |
| Pred = ICmpInst::ICMP_UGE; |
| } |
| // Canonicalize UGE to ULT. |
| if (Pred == ICmpInst::ICMP_UGE) { |
| std::swap(TrueBB, FalseBB); |
| Pred = ICmpInst::ICMP_ULT; |
| } |
| // For now, analyze only LT loops for signed overflow. |
| if (Pred != ICmpInst::ICMP_SLT && Pred != ICmpInst::ICMP_ULT) |
| return 0; |
| |
| bool isSigned = Pred == ICmpInst::ICMP_SLT; |
| |
| // Get the increment instruction. Look past casts if we will |
| // be able to prove that the original induction variable doesn't |
| // undergo signed or unsigned overflow, respectively. |
| const Value *IncrInst = CmpLHS; |
| if (isSigned) { |
| if (const SExtInst *SI = dyn_cast<SExtInst>(CmpLHS)) { |
| if (!isa<ConstantInt>(CmpRHS) || |
| !cast<ConstantInt>(CmpRHS)->getValue() |
| .isSignedIntN(TD->getTypeSizeInBits(IncrInst->getType()))) |
| return 0; |
| IncrInst = SI->getOperand(0); |
| } |
| } else { |
| if (const ZExtInst *ZI = dyn_cast<ZExtInst>(CmpLHS)) { |
| if (!isa<ConstantInt>(CmpRHS) || |
| !cast<ConstantInt>(CmpRHS)->getValue() |
| .isIntN(TD->getTypeSizeInBits(IncrInst->getType()))) |
| return 0; |
| IncrInst = ZI->getOperand(0); |
| } |
| } |
| |
| // For now, only analyze induction variables that have simple increments. |
| const BinaryOperator *IncrOp = dyn_cast<BinaryOperator>(IncrInst); |
| if (!IncrOp || IncrOp->getOpcode() != Instruction::Add) |
| return 0; |
| IncrVal = dyn_cast<ConstantInt>(IncrOp->getOperand(1)); |
| if (!IncrVal) |
| return 0; |
| |
| // Make sure the PHI looks like a normal IV. |
| const PHINode *PN = dyn_cast<PHINode>(IncrOp->getOperand(0)); |
| if (!PN || PN->getNumIncomingValues() != 2) |
| return 0; |
| unsigned IncomingEdge = L->contains(PN->getIncomingBlock(0)); |
| unsigned BackEdge = !IncomingEdge; |
| if (!L->contains(PN->getIncomingBlock(BackEdge)) || |
| PN->getIncomingValue(BackEdge) != IncrOp) |
| return 0; |
| if (!L->contains(TrueBB)) |
| return 0; |
| |
| // For now, only analyze loops with a constant start value, so that |
| // we can easily determine if the start value is not a maximum value |
| // which would wrap on the first iteration. |
| InitialVal = dyn_cast<ConstantInt>(PN->getIncomingValue(IncomingEdge)); |
| if (!InitialVal) |
| return 0; |
| |
| // The upper limit need not be a constant; we'll check later. |
| LimitVal = dyn_cast<ConstantInt>(CmpRHS); |
| |
| // We detect the impossibility of wrapping in two cases, both of |
| // which require starting with a non-max value: |
| // - The IV counts up by one, and the loop iterates only while it remains |
| // less than a limiting value (any) in the same type. |
| // - The IV counts up by a positive increment other than 1, and the |
| // constant limiting value + the increment is less than the max value |
| // (computed as max-increment to avoid overflow) |
| if (isSigned && !InitialVal->getValue().isMaxSignedValue()) { |
| if (IncrVal->equalsInt(1)) |
| NoSignedWrap = true; // LimitVal need not be constant |
| else if (LimitVal) { |
| uint64_t numBits = LimitVal->getValue().getBitWidth(); |
| if (IncrVal->getValue().sgt(APInt::getNullValue(numBits)) && |
| (APInt::getSignedMaxValue(numBits) - IncrVal->getValue()) |
| .sgt(LimitVal->getValue())) |
| NoSignedWrap = true; |
| } |
| } else if (!isSigned && !InitialVal->getValue().isMaxValue()) { |
| if (IncrVal->equalsInt(1)) |
| NoUnsignedWrap = true; // LimitVal need not be constant |
| else if (LimitVal) { |
| uint64_t numBits = LimitVal->getValue().getBitWidth(); |
| if (IncrVal->getValue().ugt(APInt::getNullValue(numBits)) && |
| (APInt::getMaxValue(numBits) - IncrVal->getValue()) |
| .ugt(LimitVal->getValue())) |
| NoUnsignedWrap = true; |
| } |
| } |
| return PN; |
| } |
| |
| static Value *getSignExtendedTruncVar(const SCEVAddRecExpr *AR, |
| ScalarEvolution *SE, |
| const Type *LargestType, Loop *L, |
| const Type *myType, |
| SCEVExpander &Rewriter, |
| BasicBlock::iterator InsertPt) { |
| SCEVHandle ExtendedStart = |
| SE->getSignExtendExpr(AR->getStart(), LargestType); |
| SCEVHandle ExtendedStep = |
| SE->getSignExtendExpr(AR->getStepRecurrence(*SE), LargestType); |
| SCEVHandle ExtendedAddRec = |
| SE->getAddRecExpr(ExtendedStart, ExtendedStep, L); |
| if (LargestType != myType) |
| ExtendedAddRec = SE->getTruncateExpr(ExtendedAddRec, myType); |
| return Rewriter.expandCodeFor(ExtendedAddRec, myType, InsertPt); |
| } |
| |
| static Value *getZeroExtendedTruncVar(const SCEVAddRecExpr *AR, |
| ScalarEvolution *SE, |
| const Type *LargestType, Loop *L, |
| const Type *myType, |
| SCEVExpander &Rewriter, |
| BasicBlock::iterator InsertPt) { |
| SCEVHandle ExtendedStart = |
| SE->getZeroExtendExpr(AR->getStart(), LargestType); |
| SCEVHandle ExtendedStep = |
| SE->getZeroExtendExpr(AR->getStepRecurrence(*SE), LargestType); |
| SCEVHandle ExtendedAddRec = |
| SE->getAddRecExpr(ExtendedStart, ExtendedStep, L); |
| if (LargestType != myType) |
| ExtendedAddRec = SE->getTruncateExpr(ExtendedAddRec, myType); |
| return Rewriter.expandCodeFor(ExtendedAddRec, myType, InsertPt); |
| } |
| |
| /// allUsesAreSameTyped - See whether all Uses of I are instructions |
| /// with the same Opcode and the same type. |
| static bool allUsesAreSameTyped(unsigned int Opcode, Instruction *I) { |
| const Type* firstType = NULL; |
| for (Value::use_iterator UI = I->use_begin(), UE = I->use_end(); |
| UI != UE; ++UI) { |
| Instruction *II = dyn_cast<Instruction>(*UI); |
| if (!II || II->getOpcode() != Opcode) |
| return false; |
| if (!firstType) |
| firstType = II->getType(); |
| else if (firstType != II->getType()) |
| return false; |
| } |
| return true; |
| } |
| |
| bool IndVarSimplify::runOnLoop(Loop *L, LPPassManager &LPM) { |
| LI = &getAnalysis<LoopInfo>(); |
| TD = &getAnalysis<TargetData>(); |
| SE = &getAnalysis<ScalarEvolution>(); |
| Changed = false; |
| |
| // If there are any floating-point recurrences, attempt to |
| // transform them to use integer recurrences. |
| RewriteNonIntegerIVs(L); |
| |
| BasicBlock *Header = L->getHeader(); |
| BasicBlock *ExitingBlock = L->getExitingBlock(); |
| SmallPtrSet<Instruction*, 16> DeadInsts; |
| |
| // Verify the input to the pass in already in LCSSA form. |
| assert(L->isLCSSAForm()); |
| |
| // Check to see if this loop has a computable loop-invariant execution count. |
| // If so, this means that we can compute the final value of any expressions |
| // that are recurrent in the loop, and substitute the exit values from the |
| // loop into any instructions outside of the loop that use the final values of |
| // the current expressions. |
| // |
| SCEVHandle BackedgeTakenCount = SE->getBackedgeTakenCount(L); |
| if (!isa<SCEVCouldNotCompute>(BackedgeTakenCount)) |
| RewriteLoopExitValues(L, BackedgeTakenCount); |
| |
| // Next, analyze all of the induction variables in the loop, canonicalizing |
| // auxillary induction variables. |
| std::vector<std::pair<PHINode*, SCEVHandle> > IndVars; |
| |
| for (BasicBlock::iterator I = Header->begin(); isa<PHINode>(I); ++I) { |
| PHINode *PN = cast<PHINode>(I); |
| if (PN->getType()->isInteger() || isa<PointerType>(PN->getType())) { |
| SCEVHandle SCEV = SE->getSCEV(PN); |
| // FIXME: It is an extremely bad idea to indvar substitute anything more |
| // complex than affine induction variables. Doing so will put expensive |
| // polynomial evaluations inside of the loop, and the str reduction pass |
| // currently can only reduce affine polynomials. For now just disable |
| // indvar subst on anything more complex than an affine addrec. |
| if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(SCEV)) |
| if (AR->getLoop() == L && AR->isAffine()) |
| IndVars.push_back(std::make_pair(PN, SCEV)); |
| } |
| } |
| |
| // Compute the type of the largest recurrence expression, and collect |
| // the set of the types of the other recurrence expressions. |
| const Type *LargestType = 0; |
| SmallSetVector<const Type *, 4> SizesToInsert; |
| if (!isa<SCEVCouldNotCompute>(BackedgeTakenCount)) { |
| LargestType = BackedgeTakenCount->getType(); |
| if (isa<PointerType>(LargestType)) |
| LargestType = TD->getIntPtrType(); |
| SizesToInsert.insert(LargestType); |
| } |
| for (unsigned i = 0, e = IndVars.size(); i != e; ++i) { |
| const PHINode *PN = IndVars[i].first; |
| const Type *PNTy = PN->getType(); |
| if (isa<PointerType>(PNTy)) PNTy = TD->getIntPtrType(); |
| SizesToInsert.insert(PNTy); |
| const Type *EffTy = getEffectiveIndvarType(PN, TD); |
| if (isa<PointerType>(EffTy)) EffTy = TD->getIntPtrType(); |
| SizesToInsert.insert(EffTy); |
| if (!LargestType || |
| TD->getTypeSizeInBits(EffTy) > |
| TD->getTypeSizeInBits(LargestType)) |
| LargestType = EffTy; |
| } |
| |
| // Create a rewriter object which we'll use to transform the code with. |
| SCEVExpander Rewriter(*SE, *LI, *TD); |
| |
| // Now that we know the largest of of the induction variables in this loop, |
| // insert a canonical induction variable of the largest size. |
| Value *IndVar = 0; |
| if (!SizesToInsert.empty()) { |
| IndVar = Rewriter.getOrInsertCanonicalInductionVariable(L,LargestType); |
| ++NumInserted; |
| Changed = true; |
| DOUT << "INDVARS: New CanIV: " << *IndVar; |
| } |
| |
| // If we have a trip count expression, rewrite the loop's exit condition |
| // using it. We can currently only handle loops with a single exit. |
| bool NoSignedWrap = false; |
| bool NoUnsignedWrap = false; |
| const ConstantInt* InitialVal, * IncrVal, * LimitVal; |
| const PHINode *OrigControllingPHI = 0; |
| if (!isa<SCEVCouldNotCompute>(BackedgeTakenCount) && ExitingBlock) |
| // Can't rewrite non-branch yet. |
| if (BranchInst *BI = dyn_cast<BranchInst>(ExitingBlock->getTerminator())) { |
| if (Instruction *OrigCond = dyn_cast<Instruction>(BI->getCondition())) { |
| // Determine if the OrigIV will ever undergo overflow. |
| OrigControllingPHI = |
| TestOrigIVForWrap(L, BI, OrigCond, TD, |
| NoSignedWrap, NoUnsignedWrap, |
| InitialVal, IncrVal, LimitVal); |
| |
| // We'll be replacing the original condition, so it'll be dead. |
| DeadInsts.insert(OrigCond); |
| } |
| |
| LinearFunctionTestReplace(L, BackedgeTakenCount, IndVar, |
| ExitingBlock, BI, Rewriter); |
| } |
| |
| // Now that we have a canonical induction variable, we can rewrite any |
| // recurrences in terms of the induction variable. Start with the auxillary |
| // induction variables, and recursively rewrite any of their uses. |
| BasicBlock::iterator InsertPt = Header->getFirstNonPHI(); |
| |
| // If there were induction variables of other sizes, cast the primary |
| // induction variable to the right size for them, avoiding the need for the |
| // code evaluation methods to insert induction variables of different sizes. |
| for (unsigned i = 0, e = SizesToInsert.size(); i != e; ++i) { |
| const Type *Ty = SizesToInsert[i]; |
| if (Ty != LargestType) { |
| Instruction *New = new TruncInst(IndVar, Ty, "indvar", InsertPt); |
| Rewriter.addInsertedValue(New, SE->getSCEV(New)); |
| DOUT << "INDVARS: Made trunc IV for type " << *Ty << ": " |
| << *New << "\n"; |
| } |
| } |
| |
| // Rewrite all induction variables in terms of the canonical induction |
| // variable. |
| while (!IndVars.empty()) { |
| PHINode *PN = IndVars.back().first; |
| const SCEVAddRecExpr *AR = cast<SCEVAddRecExpr>(IndVars.back().second); |
| Value *NewVal = Rewriter.expandCodeFor(AR, PN->getType(), InsertPt); |
| DOUT << "INDVARS: Rewrote IV '" << *AR << "' " << *PN |
| << " into = " << *NewVal << "\n"; |
| NewVal->takeName(PN); |
| |
| /// If the new canonical induction variable is wider than the original, |
| /// and the original has uses that are casts to wider types, see if the |
| /// truncate and extend can be omitted. |
| if (PN == OrigControllingPHI && PN->getType() != LargestType) |
| for (Value::use_iterator UI = PN->use_begin(), UE = PN->use_end(); |
| UI != UE; ++UI) { |
| Instruction *UInst = dyn_cast<Instruction>(*UI); |
| if (UInst && isa<SExtInst>(UInst) && NoSignedWrap) { |
| Value *TruncIndVar = getSignExtendedTruncVar(AR, SE, LargestType, L, |
| UInst->getType(), Rewriter, InsertPt); |
| UInst->replaceAllUsesWith(TruncIndVar); |
| DeadInsts.insert(UInst); |
| } |
| // See if we can figure out sext(i+constant) doesn't wrap, so we can |
| // use a larger add. This is common in subscripting. |
| if (UInst && UInst->getOpcode()==Instruction::Add && |
| allUsesAreSameTyped(Instruction::SExt, UInst) && |
| isa<ConstantInt>(UInst->getOperand(1)) && |
| NoSignedWrap && LimitVal) { |
| uint64_t oldBitSize = LimitVal->getValue().getBitWidth(); |
| uint64_t newBitSize = LargestType->getPrimitiveSizeInBits(); |
| ConstantInt* AddRHS = dyn_cast<ConstantInt>(UInst->getOperand(1)); |
| if (((APInt::getSignedMaxValue(oldBitSize) - IncrVal->getValue()) - |
| AddRHS->getValue()).sgt(LimitVal->getValue())) { |
| // We've determined this is (i+constant) and it won't overflow. |
| if (isa<SExtInst>(UInst->use_begin())) { |
| SExtInst* oldSext = dyn_cast<SExtInst>(UInst->use_begin()); |
| Value *TruncIndVar = getSignExtendedTruncVar(AR, SE, LargestType, |
| L, oldSext->getType(), Rewriter, |
| InsertPt); |
| APInt APcopy = APInt(AddRHS->getValue()); |
| ConstantInt* newAddRHS =ConstantInt::get(APcopy.sext(newBitSize)); |
| Value *NewAdd = |
| BinaryOperator::CreateAdd(TruncIndVar, newAddRHS, |
| UInst->getName()+".nosex", UInst); |
| for (Value::use_iterator UI2 = UInst->use_begin(), |
| UE2 = UInst->use_end(); UI2 != UE2; ++UI2) { |
| Instruction *II = dyn_cast<Instruction>(UI2); |
| II->replaceAllUsesWith(NewAdd); |
| DeadInsts.insert(II); |
| } |
| DeadInsts.insert(UInst); |
| } |
| } |
| } |
| // Try for sext(i | constant). This is safe as long as the |
| // high bit of the constant is not set. |
| if (UInst && UInst->getOpcode()==Instruction::Or && |
| allUsesAreSameTyped(Instruction::SExt, UInst) && NoSignedWrap && |
| isa<ConstantInt>(UInst->getOperand(1))) { |
| ConstantInt* RHS = dyn_cast<ConstantInt>(UInst->getOperand(1)); |
| if (!RHS->getValue().isNegative()) { |
| uint64_t newBitSize = LargestType->getPrimitiveSizeInBits(); |
| SExtInst* oldSext = dyn_cast<SExtInst>(UInst->use_begin()); |
| Value *TruncIndVar = getSignExtendedTruncVar(AR, SE, LargestType, |
| L, oldSext->getType(), Rewriter, |
| InsertPt); |
| APInt APcopy = APInt(RHS->getValue()); |
| ConstantInt* newRHS =ConstantInt::get(APcopy.sext(newBitSize)); |
| Value *NewAdd = |
| BinaryOperator::CreateOr(TruncIndVar, newRHS, |
| UInst->getName()+".nosex", UInst); |
| for (Value::use_iterator UI2 = UInst->use_begin(), |
| UE2 = UInst->use_end(); UI2 != UE2; ++UI2) { |
| Instruction *II = dyn_cast<Instruction>(UI2); |
| II->replaceAllUsesWith(NewAdd); |
| DeadInsts.insert(II); |
| } |
| DeadInsts.insert(UInst); |
| } |
| } |
| // A zext of a signed variable known not to overflow is still safe. |
| if (UInst && isa<ZExtInst>(UInst) && (NoUnsignedWrap || NoSignedWrap)) { |
| Value *TruncIndVar = getZeroExtendedTruncVar(AR, SE, LargestType, L, |
| UInst->getType(), Rewriter, InsertPt); |
| UInst->replaceAllUsesWith(TruncIndVar); |
| DeadInsts.insert(UInst); |
| } |
| // If we have zext(i&constant), it's always safe to use the larger |
| // variable. This is not common but is a bottleneck in Openssl. |
| // (RHS doesn't have to be constant. There should be a better approach |
| // than bottom-up pattern matching for this...) |
| if (UInst && UInst->getOpcode()==Instruction::And && |
| allUsesAreSameTyped(Instruction::ZExt, UInst) && |
| isa<ConstantInt>(UInst->getOperand(1))) { |
| uint64_t newBitSize = LargestType->getPrimitiveSizeInBits(); |
| ConstantInt* AndRHS = dyn_cast<ConstantInt>(UInst->getOperand(1)); |
| ZExtInst* oldZext = dyn_cast<ZExtInst>(UInst->use_begin()); |
| Value *TruncIndVar = getSignExtendedTruncVar(AR, SE, LargestType, |
| L, oldZext->getType(), Rewriter, InsertPt); |
| APInt APcopy = APInt(AndRHS->getValue()); |
| ConstantInt* newAndRHS = ConstantInt::get(APcopy.zext(newBitSize)); |
| Value *NewAnd = |
| BinaryOperator::CreateAnd(TruncIndVar, newAndRHS, |
| UInst->getName()+".nozex", UInst); |
| for (Value::use_iterator UI2 = UInst->use_begin(), |
| UE2 = UInst->use_end(); UI2 != UE2; ++UI2) { |
| Instruction *II = dyn_cast<Instruction>(UI2); |
| II->replaceAllUsesWith(NewAnd); |
| DeadInsts.insert(II); |
| } |
| DeadInsts.insert(UInst); |
| } |
| // If we have zext((i+constant)&constant), we can use the larger |
| // variable even if the add does overflow. This works whenever the |
| // constant being ANDed is the same size as i, which it presumably is. |
| // We don't need to restrict the expression being and'ed to i+const, |
| // but we have to promote everything in it, so it's convenient. |
| // zext((i | constant)&constant) is also valid and accepted here. |
| if (UInst && (UInst->getOpcode()==Instruction::Add || |
| UInst->getOpcode()==Instruction::Or) && |
| UInst->hasOneUse() && |
| isa<ConstantInt>(UInst->getOperand(1))) { |
| uint64_t newBitSize = LargestType->getPrimitiveSizeInBits(); |
| ConstantInt* AddRHS = dyn_cast<ConstantInt>(UInst->getOperand(1)); |
| Instruction *UInst2 = dyn_cast<Instruction>(UInst->use_begin()); |
| if (UInst2 && UInst2->getOpcode() == Instruction::And && |
| allUsesAreSameTyped(Instruction::ZExt, UInst2) && |
| isa<ConstantInt>(UInst2->getOperand(1))) { |
| ZExtInst* oldZext = dyn_cast<ZExtInst>(UInst2->use_begin()); |
| Value *TruncIndVar = getSignExtendedTruncVar(AR, SE, LargestType, |
| L, oldZext->getType(), Rewriter, InsertPt); |
| ConstantInt* AndRHS = dyn_cast<ConstantInt>(UInst2->getOperand(1)); |
| APInt APcopy = APInt(AddRHS->getValue()); |
| ConstantInt* newAddRHS = ConstantInt::get(APcopy.zext(newBitSize)); |
| Value *NewAdd = ((UInst->getOpcode()==Instruction::Add) ? |
| BinaryOperator::CreateAdd(TruncIndVar, newAddRHS, |
| UInst->getName()+".nozex", UInst2) : |
| BinaryOperator::CreateOr(TruncIndVar, newAddRHS, |
| UInst->getName()+".nozex", UInst2)); |
| APInt APcopy2 = APInt(AndRHS->getValue()); |
| ConstantInt* newAndRHS = ConstantInt::get(APcopy2.zext(newBitSize)); |
| Value *NewAnd = |
| BinaryOperator::CreateAnd(NewAdd, newAndRHS, |
| UInst->getName()+".nozex", UInst2); |
| for (Value::use_iterator UI2 = UInst2->use_begin(), |
| UE2 = UInst2->use_end(); UI2 != UE2; ++UI2) { |
| Instruction *II = dyn_cast<Instruction>(UI2); |
| II->replaceAllUsesWith(NewAnd); |
| DeadInsts.insert(II); |
| } |
| DeadInsts.insert(UInst); |
| DeadInsts.insert(UInst2); |
| } |
| } |
| } |
| |
| // Replace the old PHI Node with the inserted computation. |
| PN->replaceAllUsesWith(NewVal); |
| DeadInsts.insert(PN); |
| IndVars.pop_back(); |
| ++NumRemoved; |
| Changed = true; |
| } |
| |
| DeleteTriviallyDeadInstructions(DeadInsts); |
| assert(L->isLCSSAForm()); |
| return Changed; |
| } |
| |
| /// Return true if it is OK to use SIToFPInst for an inducation variable |
| /// with given inital and exit values. |
| static bool useSIToFPInst(ConstantFP &InitV, ConstantFP &ExitV, |
| uint64_t intIV, uint64_t intEV) { |
| |
| if (InitV.getValueAPF().isNegative() || ExitV.getValueAPF().isNegative()) |
| return true; |
| |
| // If the iteration range can be handled by SIToFPInst then use it. |
| APInt Max = APInt::getSignedMaxValue(32); |
| if (Max.getZExtValue() > static_cast<uint64_t>(abs(intEV - intIV))) |
| return true; |
| |
| return false; |
| } |
| |
| /// convertToInt - Convert APF to an integer, if possible. |
| static bool convertToInt(const APFloat &APF, uint64_t *intVal) { |
| |
| bool isExact = false; |
| if (&APF.getSemantics() == &APFloat::PPCDoubleDouble) |
| return false; |
| if (APF.convertToInteger(intVal, 32, APF.isNegative(), |
| APFloat::rmTowardZero, &isExact) |
| != APFloat::opOK) |
| return false; |
| if (!isExact) |
| return false; |
| return true; |
| |
| } |
| |
| /// HandleFloatingPointIV - If the loop has floating induction variable |
| /// then insert corresponding integer induction variable if possible. |
| /// For example, |
| /// for(double i = 0; i < 10000; ++i) |
| /// bar(i) |
| /// is converted into |
| /// for(int i = 0; i < 10000; ++i) |
| /// bar((double)i); |
| /// |
| void IndVarSimplify::HandleFloatingPointIV(Loop *L, PHINode *PH, |
| SmallPtrSet<Instruction*, 16> &DeadInsts) { |
| |
| unsigned IncomingEdge = L->contains(PH->getIncomingBlock(0)); |
| unsigned BackEdge = IncomingEdge^1; |
| |
| // Check incoming value. |
| ConstantFP *InitValue = dyn_cast<ConstantFP>(PH->getIncomingValue(IncomingEdge)); |
| if (!InitValue) return; |
| uint64_t newInitValue = Type::Int32Ty->getPrimitiveSizeInBits(); |
| if (!convertToInt(InitValue->getValueAPF(), &newInitValue)) |
| return; |
| |
| // Check IV increment. Reject this PH if increement operation is not |
| // an add or increment value can not be represented by an integer. |
| BinaryOperator *Incr = |
| dyn_cast<BinaryOperator>(PH->getIncomingValue(BackEdge)); |
| if (!Incr) return; |
| if (Incr->getOpcode() != Instruction::Add) return; |
| ConstantFP *IncrValue = NULL; |
| unsigned IncrVIndex = 1; |
| if (Incr->getOperand(1) == PH) |
| IncrVIndex = 0; |
| IncrValue = dyn_cast<ConstantFP>(Incr->getOperand(IncrVIndex)); |
| if (!IncrValue) return; |
| uint64_t newIncrValue = Type::Int32Ty->getPrimitiveSizeInBits(); |
| if (!convertToInt(IncrValue->getValueAPF(), &newIncrValue)) |
| return; |
| |
| // Check Incr uses. One user is PH and the other users is exit condition used |
| // by the conditional terminator. |
| Value::use_iterator IncrUse = Incr->use_begin(); |
| Instruction *U1 = cast<Instruction>(IncrUse++); |
| if (IncrUse == Incr->use_end()) return; |
| Instruction *U2 = cast<Instruction>(IncrUse++); |
| if (IncrUse != Incr->use_end()) return; |
| |
| // Find exit condition. |
| FCmpInst *EC = dyn_cast<FCmpInst>(U1); |
| if (!EC) |
| EC = dyn_cast<FCmpInst>(U2); |
| if (!EC) return; |
| |
| if (BranchInst *BI = dyn_cast<BranchInst>(EC->getParent()->getTerminator())) { |
| if (!BI->isConditional()) return; |
| if (BI->getCondition() != EC) return; |
| } |
| |
| // Find exit value. If exit value can not be represented as an interger then |
| // do not handle this floating point PH. |
| ConstantFP *EV = NULL; |
| unsigned EVIndex = 1; |
| if (EC->getOperand(1) == Incr) |
| EVIndex = 0; |
| EV = dyn_cast<ConstantFP>(EC->getOperand(EVIndex)); |
| if (!EV) return; |
| uint64_t intEV = Type::Int32Ty->getPrimitiveSizeInBits(); |
| if (!convertToInt(EV->getValueAPF(), &intEV)) |
| return; |
| |
| // Find new predicate for integer comparison. |
| CmpInst::Predicate NewPred = CmpInst::BAD_ICMP_PREDICATE; |
| switch (EC->getPredicate()) { |
| case CmpInst::FCMP_OEQ: |
| case CmpInst::FCMP_UEQ: |
| NewPred = CmpInst::ICMP_EQ; |
| break; |
| case CmpInst::FCMP_OGT: |
| case CmpInst::FCMP_UGT: |
| NewPred = CmpInst::ICMP_UGT; |
| break; |
| case CmpInst::FCMP_OGE: |
| case CmpInst::FCMP_UGE: |
| NewPred = CmpInst::ICMP_UGE; |
| break; |
| case CmpInst::FCMP_OLT: |
| case CmpInst::FCMP_ULT: |
| NewPred = CmpInst::ICMP_ULT; |
| break; |
| case CmpInst::FCMP_OLE: |
| case CmpInst::FCMP_ULE: |
| NewPred = CmpInst::ICMP_ULE; |
| break; |
| default: |
| break; |
| } |
| if (NewPred == CmpInst::BAD_ICMP_PREDICATE) return; |
| |
| // Insert new integer induction variable. |
| PHINode *NewPHI = PHINode::Create(Type::Int32Ty, |
| PH->getName()+".int", PH); |
| NewPHI->addIncoming(ConstantInt::get(Type::Int32Ty, newInitValue), |
| PH->getIncomingBlock(IncomingEdge)); |
| |
| Value *NewAdd = BinaryOperator::CreateAdd(NewPHI, |
| ConstantInt::get(Type::Int32Ty, |
| newIncrValue), |
| Incr->getName()+".int", Incr); |
| NewPHI->addIncoming(NewAdd, PH->getIncomingBlock(BackEdge)); |
| |
| ConstantInt *NewEV = ConstantInt::get(Type::Int32Ty, intEV); |
| Value *LHS = (EVIndex == 1 ? NewPHI->getIncomingValue(BackEdge) : NewEV); |
| Value *RHS = (EVIndex == 1 ? NewEV : NewPHI->getIncomingValue(BackEdge)); |
| ICmpInst *NewEC = new ICmpInst(NewPred, LHS, RHS, EC->getNameStart(), |
| EC->getParent()->getTerminator()); |
| |
| // Delete old, floating point, exit comparision instruction. |
| EC->replaceAllUsesWith(NewEC); |
| DeadInsts.insert(EC); |
| |
| // Delete old, floating point, increment instruction. |
| Incr->replaceAllUsesWith(UndefValue::get(Incr->getType())); |
| DeadInsts.insert(Incr); |
| |
| // Replace floating induction variable. Give SIToFPInst preference over |
| // UIToFPInst because it is faster on platforms that are widely used. |
| if (useSIToFPInst(*InitValue, *EV, newInitValue, intEV)) { |
| SIToFPInst *Conv = new SIToFPInst(NewPHI, PH->getType(), "indvar.conv", |
| PH->getParent()->getFirstNonPHI()); |
| PH->replaceAllUsesWith(Conv); |
| } else { |
| UIToFPInst *Conv = new UIToFPInst(NewPHI, PH->getType(), "indvar.conv", |
| PH->getParent()->getFirstNonPHI()); |
| PH->replaceAllUsesWith(Conv); |
| } |
| DeadInsts.insert(PH); |
| } |
| |