diff options
Diffstat (limited to 'lib/Transforms/Utils/SimplifyCFG.cpp')
| -rw-r--r-- | lib/Transforms/Utils/SimplifyCFG.cpp | 1206 |
1 files changed, 818 insertions, 388 deletions
diff --git a/lib/Transforms/Utils/SimplifyCFG.cpp b/lib/Transforms/Utils/SimplifyCFG.cpp index 32d7fa1..f10c35f 100644 --- a/lib/Transforms/Utils/SimplifyCFG.cpp +++ b/lib/Transforms/Utils/SimplifyCFG.cpp @@ -13,18 +13,6 @@ #define DEBUG_TYPE "simplifycfg" #include "llvm/Transforms/Utils/Local.h" -#include "llvm/Constants.h" -#include "llvm/DerivedTypes.h" -#include "llvm/GlobalVariable.h" -#include "llvm/IRBuilder.h" -#include "llvm/Instructions.h" -#include "llvm/IntrinsicInst.h" -#include "llvm/LLVMContext.h" -#include "llvm/MDBuilder.h" -#include "llvm/Metadata.h" -#include "llvm/Module.h" -#include "llvm/Operator.h" -#include "llvm/Type.h" #include "llvm/ADT/DenseMap.h" #include "llvm/ADT/STLExtras.h" #include "llvm/ADT/SetVector.h" @@ -32,18 +20,31 @@ #include "llvm/ADT/SmallVector.h" #include "llvm/ADT/Statistic.h" #include "llvm/Analysis/InstructionSimplify.h" +#include "llvm/Analysis/TargetTransformInfo.h" #include "llvm/Analysis/ValueTracking.h" +#include "llvm/IR/Constants.h" +#include "llvm/IR/DataLayout.h" +#include "llvm/IR/DerivedTypes.h" +#include "llvm/IR/GlobalVariable.h" +#include "llvm/IR/IRBuilder.h" +#include "llvm/IR/Instructions.h" +#include "llvm/IR/IntrinsicInst.h" +#include "llvm/IR/LLVMContext.h" +#include "llvm/IR/MDBuilder.h" +#include "llvm/IR/Metadata.h" +#include "llvm/IR/Module.h" +#include "llvm/IR/Operator.h" +#include "llvm/IR/Type.h" #include "llvm/Support/CFG.h" #include "llvm/Support/CommandLine.h" #include "llvm/Support/ConstantRange.h" #include "llvm/Support/Debug.h" #include "llvm/Support/NoFolder.h" #include "llvm/Support/raw_ostream.h" -#include "llvm/Target/TargetData.h" #include "llvm/Transforms/Utils/BasicBlockUtils.h" #include <algorithm> -#include <set> #include <map> +#include <set> using namespace llvm; static cl::opt<unsigned> @@ -54,8 +55,14 @@ static cl::opt<bool> DupRet("simplifycfg-dup-ret", cl::Hidden, cl::init(false), cl::desc("Duplicate return instructions into unconditional branches")); -STATISTIC(NumSpeculations, "Number of speculative executed instructions"); +static cl::opt<bool> +SinkCommon("simplifycfg-sink-common", cl::Hidden, cl::init(true), + cl::desc("Sink common instructions down to the end block")); + +STATISTIC(NumBitMaps, "Number of switch instructions turned into bitmaps"); STATISTIC(NumLookupTables, "Number of switch instructions turned into lookup tables"); +STATISTIC(NumSinkCommons, "Number of common instructions sunk down to the end block"); +STATISTIC(NumSpeculations, "Number of speculative executed instructions"); namespace { /// ValueEqualityComparisonCase - Represents a case of a switch. @@ -70,10 +77,13 @@ namespace { // Comparing pointers is ok as we only rely on the order for uniquing. return Value < RHS.Value; } + + bool operator==(BasicBlock *RHSDest) const { return Dest == RHSDest; } }; class SimplifyCFGOpt { - const TargetData *const TD; + const TargetTransformInfo &TTI; + const DataLayout *const TD; Value *isValueEqualityComparison(TerminatorInst *TI); BasicBlock *GetValueEqualityComparisonCases(TerminatorInst *TI, @@ -93,7 +103,8 @@ class SimplifyCFGOpt { bool SimplifyCondBranch(BranchInst *BI, IRBuilder <>&Builder); public: - explicit SimplifyCFGOpt(const TargetData *td) : TD(td) {} + SimplifyCFGOpt(const TargetTransformInfo &TTI, const DataLayout *TD) + : TTI(TTI), TD(TD) {} bool run(BasicBlock *BB); }; } @@ -376,7 +387,7 @@ static bool DominatesMergePoint(Value *V, BasicBlock *BB, /// GetConstantInt - Extract ConstantInt from value, looking through IntToPtr /// and PointerNullValue. Return NULL if value is not a constant int. -static ConstantInt *GetConstantInt(Value *V, const TargetData *TD) { +static ConstantInt *GetConstantInt(Value *V, const DataLayout *TD) { // Normal constant int. ConstantInt *CI = dyn_cast<ConstantInt>(V); if (CI || !TD || !isa<Constant>(V) || !V->getType()->isPointerTy()) @@ -384,7 +395,7 @@ static ConstantInt *GetConstantInt(Value *V, const TargetData *TD) { // This is some kind of pointer constant. Turn it into a pointer-sized // ConstantInt if possible. - IntegerType *PtrTy = TD->getIntPtrType(V->getContext()); + IntegerType *PtrTy = cast<IntegerType>(TD->getIntPtrType(V->getType())); // Null pointer means 0, see SelectionDAGBuilder::getValue(const Value*). if (isa<ConstantPointerNull>(V)) @@ -410,7 +421,7 @@ static ConstantInt *GetConstantInt(Value *V, const TargetData *TD) { /// Values vector. static Value * GatherConstantCompares(Value *V, std::vector<ConstantInt*> &Vals, Value *&Extra, - const TargetData *TD, bool isEQ, unsigned &UsedICmps) { + const DataLayout *TD, bool isEQ, unsigned &UsedICmps) { Instruction *I = dyn_cast<Instruction>(V); if (I == 0) return 0; @@ -558,11 +569,7 @@ GetValueEqualityComparisonCases(TerminatorInst *TI, /// in the list that match the specified block. static void EliminateBlockCases(BasicBlock *BB, std::vector<ValueEqualityComparisonCase> &Cases) { - for (unsigned i = 0, e = Cases.size(); i != e; ++i) - if (Cases[i].Dest == BB) { - Cases.erase(Cases.begin()+i); - --i; --e; - } + Cases.erase(std::remove(Cases.begin(), Cases.end(), BB), Cases.end()); } /// ValuesOverlap - Return true if there are any keys in C1 that exist in C2 as @@ -667,13 +674,32 @@ SimplifyEqualityComparisonWithOnlyPredecessor(TerminatorInst *TI, DEBUG(dbgs() << "Threading pred instr: " << *Pred->getTerminator() << "Through successor TI: " << *TI); + // Collect branch weights into a vector. + SmallVector<uint32_t, 8> Weights; + MDNode* MD = SI->getMetadata(LLVMContext::MD_prof); + bool HasWeight = MD && (MD->getNumOperands() == 2 + SI->getNumCases()); + if (HasWeight) + for (unsigned MD_i = 1, MD_e = MD->getNumOperands(); MD_i < MD_e; + ++MD_i) { + ConstantInt* CI = dyn_cast<ConstantInt>(MD->getOperand(MD_i)); + assert(CI); + Weights.push_back(CI->getValue().getZExtValue()); + } for (SwitchInst::CaseIt i = SI->case_end(), e = SI->case_begin(); i != e;) { --i; if (DeadCases.count(i.getCaseValue())) { + if (HasWeight) { + std::swap(Weights[i.getCaseIndex()+1], Weights.back()); + Weights.pop_back(); + } i.getCaseSuccessor()->removePredecessor(TI->getParent()); SI->removeCase(i); } } + if (HasWeight && Weights.size() >= 2) + SI->setMetadata(LLVMContext::MD_prof, + MDBuilder(SI->getParent()->getContext()). + createBranchWeights(Weights)); DEBUG(dbgs() << "Leaving: " << *TI << "\n"); return true; @@ -752,38 +778,27 @@ static inline bool HasBranchWeights(const Instruction* I) { return false; } -/// Tries to get a branch weight for the given instruction, returns NULL if it -/// can't. Pos starts at 0. -static ConstantInt* GetWeight(Instruction* I, int Pos) { - MDNode* ProfMD = I->getMetadata(LLVMContext::MD_prof); - if (ProfMD && ProfMD->getOperand(0)) { - if (MDString* MDS = dyn_cast<MDString>(ProfMD->getOperand(0))) { - if (MDS->getString().equals("branch_weights")) { - assert(ProfMD->getNumOperands() >= 3); - return dyn_cast<ConstantInt>(ProfMD->getOperand(1 + Pos)); - } - } - } - - return 0; -} - -/// Scale the given weights based on the successor TI's metadata. Scaling is -/// done by multiplying every weight by the sum of the successor's weights. -static void ScaleWeights(Instruction* STI, MutableArrayRef<uint64_t> Weights) { - // Sum the successor's weights - assert(HasBranchWeights(STI)); - unsigned Scale = 0; - MDNode* ProfMD = STI->getMetadata(LLVMContext::MD_prof); - for (unsigned i = 1; i < ProfMD->getNumOperands(); ++i) { - ConstantInt* CI = dyn_cast<ConstantInt>(ProfMD->getOperand(i)); +/// Get Weights of a given TerminatorInst, the default weight is at the front +/// of the vector. If TI is a conditional eq, we need to swap the branch-weight +/// metadata. +static void GetBranchWeights(TerminatorInst *TI, + SmallVectorImpl<uint64_t> &Weights) { + MDNode* MD = TI->getMetadata(LLVMContext::MD_prof); + assert(MD); + for (unsigned i = 1, e = MD->getNumOperands(); i < e; ++i) { + ConstantInt* CI = dyn_cast<ConstantInt>(MD->getOperand(i)); assert(CI); - Scale += CI->getValue().getZExtValue(); + Weights.push_back(CI->getValue().getZExtValue()); } - // Skip default, as it's replaced during the folding - for (unsigned i = 1; i < Weights.size(); ++i) { - Weights[i] *= Scale; + // If TI is a conditional eq, the default case is the false case, + // and the corresponding branch-weight data is at index 2. We swap the + // default weight to be the first entry. + if (BranchInst* BI = dyn_cast<BranchInst>(TI)) { + assert(Weights.size() == 2); + ICmpInst *ICI = cast<ICmpInst>(BI->getCondition()); + if (ICI->getPredicate() == ICmpInst::ICMP_EQ) + std::swap(Weights.front(), Weights.back()); } } @@ -838,52 +853,28 @@ bool SimplifyCFGOpt::FoldValueComparisonIntoPredecessors(TerminatorInst *TI, // Update the branch weight metadata along the way SmallVector<uint64_t, 8> Weights; - uint64_t PredDefaultWeight = 0; bool PredHasWeights = HasBranchWeights(PTI); bool SuccHasWeights = HasBranchWeights(TI); if (PredHasWeights) { - MDNode* MD = PTI->getMetadata(LLVMContext::MD_prof); - assert(MD); - for (unsigned i = 1, e = MD->getNumOperands(); i < e; ++i) { - ConstantInt* CI = dyn_cast<ConstantInt>(MD->getOperand(i)); - assert(CI); - Weights.push_back(CI->getValue().getZExtValue()); - } - - // If the predecessor is a conditional eq, then swap the default weight - // to be the first entry. - if (BranchInst* BI = dyn_cast<BranchInst>(PTI)) { - assert(Weights.size() == 2); - ICmpInst *ICI = cast<ICmpInst>(BI->getCondition()); - - if (ICI->getPredicate() == ICmpInst::ICMP_EQ) { - std::swap(Weights.front(), Weights.back()); - } - } - - PredDefaultWeight = Weights.front(); - } else if (SuccHasWeights) { + GetBranchWeights(PTI, Weights); + // branch-weight metadata is inconsistent here. + if (Weights.size() != 1 + PredCases.size()) + PredHasWeights = SuccHasWeights = false; + } else if (SuccHasWeights) // If there are no predecessor weights but there are successor weights, // populate Weights with 1, which will later be scaled to the sum of // successor's weights Weights.assign(1 + PredCases.size(), 1); - PredDefaultWeight = 1; - } - uint64_t SuccDefaultWeight = 0; + SmallVector<uint64_t, 8> SuccWeights; if (SuccHasWeights) { - int Index = 0; - if (BranchInst* BI = dyn_cast<BranchInst>(TI)) { - ICmpInst* ICI = dyn_cast<ICmpInst>(BI->getCondition()); - assert(ICI); - - if (ICI->getPredicate() == ICmpInst::ICMP_EQ) - Index = 1; - } - - SuccDefaultWeight = GetWeight(TI, Index)->getValue().getZExtValue(); - } + GetBranchWeights(TI, SuccWeights); + // branch-weight metadata is inconsistent here. + if (SuccWeights.size() != 1 + BBCases.size()) + PredHasWeights = SuccHasWeights = false; + } else if (PredHasWeights) + SuccWeights.assign(1 + BBCases.size(), 1); if (PredDefault == BB) { // If this is the default destination from PTI, only the edges in TI @@ -896,7 +887,9 @@ bool SimplifyCFGOpt::FoldValueComparisonIntoPredecessors(TerminatorInst *TI, // The default destination is BB, we don't need explicit targets. std::swap(PredCases[i], PredCases.back()); - if (PredHasWeights) { + if (PredHasWeights || SuccHasWeights) { + // Increase weight for the default case. + Weights[0] += Weights[i+1]; std::swap(Weights[i+1], Weights.back()); Weights.pop_back(); } @@ -912,40 +905,46 @@ bool SimplifyCFGOpt::FoldValueComparisonIntoPredecessors(TerminatorInst *TI, NewSuccessors.push_back(BBDefault); } - if (SuccHasWeights) { - ScaleWeights(TI, Weights); - Weights.front() *= SuccDefaultWeight; - } else if (PredHasWeights) { - Weights.front() /= (1 + BBCases.size()); - } - + unsigned CasesFromPred = Weights.size(); + uint64_t ValidTotalSuccWeight = 0; for (unsigned i = 0, e = BBCases.size(); i != e; ++i) if (!PTIHandled.count(BBCases[i].Value) && BBCases[i].Dest != BBDefault) { PredCases.push_back(BBCases[i]); NewSuccessors.push_back(BBCases[i].Dest); - if (SuccHasWeights) { - Weights.push_back(PredDefaultWeight * - GetWeight(TI, i)->getValue().getZExtValue()); - } else if (PredHasWeights) { - // Split the old default's weight amongst the children - Weights.push_back(PredDefaultWeight / (1 + BBCases.size())); + if (SuccHasWeights || PredHasWeights) { + // The default weight is at index 0, so weight for the ith case + // should be at index i+1. Scale the cases from successor by + // PredDefaultWeight (Weights[0]). + Weights.push_back(Weights[0] * SuccWeights[i+1]); + ValidTotalSuccWeight += SuccWeights[i+1]; } } + if (SuccHasWeights || PredHasWeights) { + ValidTotalSuccWeight += SuccWeights[0]; + // Scale the cases from predecessor by ValidTotalSuccWeight. + for (unsigned i = 1; i < CasesFromPred; ++i) + Weights[i] *= ValidTotalSuccWeight; + // Scale the default weight by SuccDefaultWeight (SuccWeights[0]). + Weights[0] *= SuccWeights[0]; + } } else { - // FIXME: preserve branch weight metadata, similarly to the 'then' - // above. For now, drop it. - PredHasWeights = false; - SuccHasWeights = false; - // If this is not the default destination from PSI, only the edges // in SI that occur in PSI with a destination of BB will be // activated. std::set<ConstantInt*, ConstantIntOrdering> PTIHandled; + std::map<ConstantInt*, uint64_t> WeightsForHandled; for (unsigned i = 0, e = PredCases.size(); i != e; ++i) if (PredCases[i].Dest == BB) { PTIHandled.insert(PredCases[i].Value); + + if (PredHasWeights || SuccHasWeights) { + WeightsForHandled[PredCases[i].Value] = Weights[i+1]; + std::swap(Weights[i+1], Weights.back()); + Weights.pop_back(); + } + std::swap(PredCases[i], PredCases.back()); PredCases.pop_back(); --i; --e; @@ -956,6 +955,8 @@ bool SimplifyCFGOpt::FoldValueComparisonIntoPredecessors(TerminatorInst *TI, for (unsigned i = 0, e = BBCases.size(); i != e; ++i) if (PTIHandled.count(BBCases[i].Value)) { // If this is one we are capable of getting... + if (PredHasWeights || SuccHasWeights) + Weights.push_back(WeightsForHandled[BBCases[i].Value]); PredCases.push_back(BBCases[i]); NewSuccessors.push_back(BBCases[i].Dest); PTIHandled.erase(BBCases[i].Value);// This constant is taken care of @@ -966,6 +967,8 @@ bool SimplifyCFGOpt::FoldValueComparisonIntoPredecessors(TerminatorInst *TI, for (std::set<ConstantInt*, ConstantIntOrdering>::iterator I = PTIHandled.begin(), E = PTIHandled.end(); I != E; ++I) { + if (PredHasWeights || SuccHasWeights) + Weights.push_back(WeightsForHandled[*I]); PredCases.push_back(ValueEqualityComparisonCase(*I, BBDefault)); NewSuccessors.push_back(BBDefault); } @@ -980,7 +983,7 @@ bool SimplifyCFGOpt::FoldValueComparisonIntoPredecessors(TerminatorInst *TI, Builder.SetInsertPoint(PTI); // Convert pointer to int before we switch. if (CV->getType()->isPointerTy()) { - assert(TD && "Cannot switch on pointer without TargetData"); + assert(TD && "Cannot switch on pointer without DataLayout"); CV = Builder.CreatePtrToInt(CV, TD->getIntPtrType(CV->getContext()), "magicptr"); } @@ -1160,6 +1163,175 @@ HoistTerminator: return true; } +/// SinkThenElseCodeToEnd - Given an unconditional branch that goes to BBEnd, +/// check whether BBEnd has only two predecessors and the other predecessor +/// ends with an unconditional branch. If it is true, sink any common code +/// in the two predecessors to BBEnd. +static bool SinkThenElseCodeToEnd(BranchInst *BI1) { + assert(BI1->isUnconditional()); + BasicBlock *BB1 = BI1->getParent(); + BasicBlock *BBEnd = BI1->getSuccessor(0); + + // Check that BBEnd has two predecessors and the other predecessor ends with + // an unconditional branch. + pred_iterator PI = pred_begin(BBEnd), PE = pred_end(BBEnd); + BasicBlock *Pred0 = *PI++; + if (PI == PE) // Only one predecessor. + return false; + BasicBlock *Pred1 = *PI++; + if (PI != PE) // More than two predecessors. + return false; + BasicBlock *BB2 = (Pred0 == BB1) ? Pred1 : Pred0; + BranchInst *BI2 = dyn_cast<BranchInst>(BB2->getTerminator()); + if (!BI2 || !BI2->isUnconditional()) + return false; + + // Gather the PHI nodes in BBEnd. + std::map<Value*, std::pair<Value*, PHINode*> > MapValueFromBB1ToBB2; + Instruction *FirstNonPhiInBBEnd = 0; + for (BasicBlock::iterator I = BBEnd->begin(), E = BBEnd->end(); + I != E; ++I) { + if (PHINode *PN = dyn_cast<PHINode>(I)) { + Value *BB1V = PN->getIncomingValueForBlock(BB1); + Value *BB2V = PN->getIncomingValueForBlock(BB2); + MapValueFromBB1ToBB2[BB1V] = std::make_pair(BB2V, PN); + } else { + FirstNonPhiInBBEnd = &*I; + break; + } + } + if (!FirstNonPhiInBBEnd) + return false; + + + // This does very trivial matching, with limited scanning, to find identical + // instructions in the two blocks. We scan backward for obviously identical + // instructions in an identical order. + BasicBlock::InstListType::reverse_iterator RI1 = BB1->getInstList().rbegin(), + RE1 = BB1->getInstList().rend(), RI2 = BB2->getInstList().rbegin(), + RE2 = BB2->getInstList().rend(); + // Skip debug info. + while (RI1 != RE1 && isa<DbgInfoIntrinsic>(&*RI1)) ++RI1; + if (RI1 == RE1) + return false; + while (RI2 != RE2 && isa<DbgInfoIntrinsic>(&*RI2)) ++RI2; + if (RI2 == RE2) + return false; + // Skip the unconditional branches. + ++RI1; + ++RI2; + + bool Changed = false; + while (RI1 != RE1 && RI2 != RE2) { + // Skip debug info. + while (RI1 != RE1 && isa<DbgInfoIntrinsic>(&*RI1)) ++RI1; + if (RI1 == RE1) + return Changed; + while (RI2 != RE2 && isa<DbgInfoIntrinsic>(&*RI2)) ++RI2; + if (RI2 == RE2) + return Changed; + + Instruction *I1 = &*RI1, *I2 = &*RI2; + // I1 and I2 should have a single use in the same PHI node, and they + // perform the same operation. + // Cannot move control-flow-involving, volatile loads, vaarg, etc. + if (isa<PHINode>(I1) || isa<PHINode>(I2) || + isa<TerminatorInst>(I1) || isa<TerminatorInst>(I2) || + isa<LandingPadInst>(I1) || isa<LandingPadInst>(I2) || + isa<AllocaInst>(I1) || isa<AllocaInst>(I2) || + I1->mayHaveSideEffects() || I2->mayHaveSideEffects() || + I1->mayReadOrWriteMemory() || I2->mayReadOrWriteMemory() || + !I1->hasOneUse() || !I2->hasOneUse() || + MapValueFromBB1ToBB2.find(I1) == MapValueFromBB1ToBB2.end() || + MapValueFromBB1ToBB2[I1].first != I2) + return Changed; + + // Check whether we should swap the operands of ICmpInst. + ICmpInst *ICmp1 = dyn_cast<ICmpInst>(I1), *ICmp2 = dyn_cast<ICmpInst>(I2); + bool SwapOpnds = false; + if (ICmp1 && ICmp2 && + ICmp1->getOperand(0) != ICmp2->getOperand(0) && + ICmp1->getOperand(1) != ICmp2->getOperand(1) && + (ICmp1->getOperand(0) == ICmp2->getOperand(1) || + ICmp1->getOperand(1) == ICmp2->getOperand(0))) { + ICmp2->swapOperands(); + SwapOpnds = true; + } + if (!I1->isSameOperationAs(I2)) { + if (SwapOpnds) + ICmp2->swapOperands(); + return Changed; + } + + // The operands should be either the same or they need to be generated + // with a PHI node after sinking. We only handle the case where there is + // a single pair of different operands. + Value *DifferentOp1 = 0, *DifferentOp2 = 0; + unsigned Op1Idx = 0; + for (unsigned I = 0, E = I1->getNumOperands(); I != E; ++I) { + if (I1->getOperand(I) == I2->getOperand(I)) + continue; + // Early exit if we have more-than one pair of different operands or + // the different operand is already in MapValueFromBB1ToBB2. + // Early exit if we need a PHI node to replace a constant. + if (DifferentOp1 || + MapValueFromBB1ToBB2.find(I1->getOperand(I)) != + MapValueFromBB1ToBB2.end() || + isa<Constant>(I1->getOperand(I)) || + isa<Constant>(I2->getOperand(I))) { + // If we can't sink the instructions, undo the swapping. + if (SwapOpnds) + ICmp2->swapOperands(); + return Changed; + } + DifferentOp1 = I1->getOperand(I); + Op1Idx = I; + DifferentOp2 = I2->getOperand(I); + } + + // We insert the pair of different operands to MapValueFromBB1ToBB2 and + // remove (I1, I2) from MapValueFromBB1ToBB2. + if (DifferentOp1) { + PHINode *NewPN = PHINode::Create(DifferentOp1->getType(), 2, + DifferentOp1->getName() + ".sink", + BBEnd->begin()); + MapValueFromBB1ToBB2[DifferentOp1] = std::make_pair(DifferentOp2, NewPN); + // I1 should use NewPN instead of DifferentOp1. + I1->setOperand(Op1Idx, NewPN); + NewPN->addIncoming(DifferentOp1, BB1); + NewPN->addIncoming(DifferentOp2, BB2); + DEBUG(dbgs() << "Create PHI node " << *NewPN << "\n";); + } + PHINode *OldPN = MapValueFromBB1ToBB2[I1].second; + MapValueFromBB1ToBB2.erase(I1); + + DEBUG(dbgs() << "SINK common instructions " << *I1 << "\n";); + DEBUG(dbgs() << " " << *I2 << "\n";); + // We need to update RE1 and RE2 if we are going to sink the first + // instruction in the basic block down. + bool UpdateRE1 = (I1 == BB1->begin()), UpdateRE2 = (I2 == BB2->begin()); + // Sink the instruction. + BBEnd->getInstList().splice(FirstNonPhiInBBEnd, BB1->getInstList(), I1); + if (!OldPN->use_empty()) + OldPN->replaceAllUsesWith(I1); + OldPN->eraseFromParent(); + + if (!I2->use_empty()) + I2->replaceAllUsesWith(I1); + I1->intersectOptionalDataWith(I2); + I2->eraseFromParent(); + + if (UpdateRE1) + RE1 = BB1->getInstList().rend(); + if (UpdateRE2) + RE2 = BB2->getInstList().rend(); + FirstNonPhiInBBEnd = I1; + NumSinkCommons++; + Changed = true; + } + return Changed; +} + /// SpeculativelyExecuteBB - Given a conditional branch that goes to BB1 /// and an BB2 and the only successor of BB1 is BB2, hoist simple code /// (for now, restricted to a single instruction that's side effect free) from @@ -1243,7 +1415,7 @@ static bool SpeculativelyExecuteBB(BranchInst *BI, BasicBlock *BB1) { if (BB1V == BIParentV) continue; - // Check for saftey. + // Check for safety. if (ConstantExpr *CE = dyn_cast<ConstantExpr>(BB1V)) { // An unfolded ConstantExpr could end up getting expanded into // Instructions. Don't speculate this and another instruction at @@ -1339,7 +1511,7 @@ static bool BlockIsSimpleEnoughToThreadThrough(BasicBlock *BB) { /// that is defined in the same block as the branch and if any PHI entries are /// constants, thread edges corresponding to that entry to be branches to their /// ultimate destination. -static bool FoldCondBranchOnPHI(BranchInst *BI, const TargetData *TD) { +static bool FoldCondBranchOnPHI(BranchInst *BI, const DataLayout *TD) { BasicBlock *BB = BI->getParent(); PHINode *PN = dyn_cast<PHINode>(BI->getCondition()); // NOTE: we currently cannot transform this case if the PHI node is used @@ -1435,7 +1607,7 @@ static bool FoldCondBranchOnPHI(BranchInst *BI, const TargetData *TD) { /// FoldTwoEntryPHINode - Given a BB that starts with the specified two-entry /// PHI node, see if we can eliminate it. -static bool FoldTwoEntryPHINode(PHINode *PN, const TargetData *TD) { +static bool FoldTwoEntryPHINode(PHINode *PN, const DataLayout *TD) { // Ok, this is a two entry PHI node. Check to see if this is a simple "if // statement", which has a very simple dominance structure. Basically, we // are trying to find the condition that is being branched on, which @@ -1662,7 +1834,7 @@ static bool SimplifyCondBranchToTwoReturns(BranchInst *BI, /// parameters and return true, or returns false if no or invalid metadata was /// found. static bool ExtractBranchMetadata(BranchInst *BI, - APInt &ProbTrue, APInt &ProbFalse) { + uint64_t &ProbTrue, uint64_t &ProbFalse) { assert(BI->isConditional() && "Looking for probabilities on unconditional branch?"); MDNode *ProfileData = BI->getMetadata(LLVMContext::MD_prof); @@ -1670,35 +1842,11 @@ static bool ExtractBranchMetadata(BranchInst *BI, ConstantInt *CITrue = dyn_cast<ConstantInt>(ProfileData->getOperand(1)); ConstantInt *CIFalse = dyn_cast<ConstantInt>(ProfileData->getOperand(2)); if (!CITrue || !CIFalse) return false; - ProbTrue = CITrue->getValue(); - ProbFalse = CIFalse->getValue(); - assert(ProbTrue.getBitWidth() == 32 && ProbFalse.getBitWidth() == 32 && - "Branch probability metadata must be 32-bit integers"); + ProbTrue = CITrue->getValue().getZExtValue(); + ProbFalse = CIFalse->getValue().getZExtValue(); return true; } -/// MultiplyAndLosePrecision - Multiplies A and B, then returns the result. In -/// the event of overflow, logically-shifts all four inputs right until the -/// multiply fits. -static APInt MultiplyAndLosePrecision(APInt &A, APInt &B, APInt &C, APInt &D, - unsigned &BitsLost) { - BitsLost = 0; - bool Overflow = false; - APInt Result = A.umul_ov(B, Overflow); - if (Overflow) { - APInt MaxB = APInt::getMaxValue(A.getBitWidth()).udiv(A); - do { - B = B.lshr(1); - ++BitsLost; - } while (B.ugt(MaxB)); - A = A.lshr(BitsLost); - C = C.lshr(BitsLost); - D = D.lshr(BitsLost); - Result = A * B; - } - return Result; -} - /// checkCSEInPredecessor - Return true if the given instruction is available /// in its predecessor block. If yes, the instruction will be removed. /// @@ -1824,7 +1972,7 @@ bool llvm::FoldBranchToCommonDest(BranchInst *BI) { continue; // Determine if the two branches share a common destination. - Instruction::BinaryOps Opc; + Instruction::BinaryOps Opc = Instruction::BinaryOpsEnd; bool InvertPredCond = false; if (BI->isConditional()) { @@ -1923,14 +2071,53 @@ bool llvm::FoldBranchToCommonDest(BranchInst *BI) { New, "or.cond")); PBI->setCondition(NewCond); + uint64_t PredTrueWeight, PredFalseWeight, SuccTrueWeight, SuccFalseWeight; + bool PredHasWeights = ExtractBranchMetadata(PBI, PredTrueWeight, + PredFalseWeight); + bool SuccHasWeights = ExtractBranchMetadata(BI, SuccTrueWeight, + SuccFalseWeight); + SmallVector<uint64_t, 8> NewWeights; + if (PBI->getSuccessor(0) == BB) { + if (PredHasWeights && SuccHasWeights) { + // PBI: br i1 %x, BB, FalseDest + // BI: br i1 %y, TrueDest, FalseDest + //TrueWeight is TrueWeight for PBI * TrueWeight for BI. + NewWeights.push_back(PredTrueWeight * SuccTrueWeight); + //FalseWeight is FalseWeight for PBI * TotalWeight for BI + + // TrueWeight for PBI * FalseWeight for BI. + // We assume that total weights of a BranchInst can fit into 32 bits. + // Therefore, we will not have overflow using 64-bit arithmetic. + NewWeights.push_back(PredFalseWeight * (SuccFalseWeight + + SuccTrueWeight) + PredTrueWeight * SuccFalseWeight); + } AddPredecessorToBlock(TrueDest, PredBlock, BB); PBI->setSuccessor(0, TrueDest); } if (PBI->getSuccessor(1) == BB) { + if (PredHasWeights && SuccHasWeights) { + // PBI: br i1 %x, TrueDest, BB + // BI: br i1 %y, TrueDest, FalseDest + //TrueWeight is TrueWeight for PBI * TotalWeight for BI + + // FalseWeight for PBI * TrueWeight for BI. + NewWeights.push_back(PredTrueWeight * (SuccFalseWeight + + SuccTrueWeight) + PredFalseWeight * SuccTrueWeight); + //FalseWeight is FalseWeight for PBI * FalseWeight for BI. + NewWeights.push_back(PredFalseWeight * SuccFalseWeight); + } AddPredecessorToBlock(FalseDest, PredBlock, BB); PBI->setSuccessor(1, FalseDest); } + if (NewWeights.size() == 2) { + // Halve the weights if any of them cannot fit in an uint32_t + FitWeights(NewWeights); + + SmallVector<uint32_t, 8> MDWeights(NewWeights.begin(),NewWeights.end()); + PBI->setMetadata(LLVMContext::MD_prof, + MDBuilder(BI->getContext()). + createBranchWeights(MDWeights)); + } else + PBI->setMetadata(LLVMContext::MD_prof, NULL); } else { // Update PHI nodes in the common successors. for (unsigned i = 0, e = PHIs.size(); i != e; ++i) { @@ -1985,90 +2172,6 @@ bool llvm::FoldBranchToCommonDest(BranchInst *BI) { // TODO: If BB is reachable from all paths through PredBlock, then we // could replace PBI's branch probabilities with BI's. - // Merge probability data into PredBlock's branch. - APInt A, B, C, D; - if (PBI->isConditional() && BI->isConditional() && - ExtractBranchMetadata(PBI, C, D) && ExtractBranchMetadata(BI, A, B)) { - // Given IR which does: - // bbA: - // br i1 %x, label %bbB, label %bbC - // bbB: - // br i1 %y, label %bbD, label %bbC - // Let's call the probability that we take the edge from %bbA to %bbB - // 'a', from %bbA to %bbC, 'b', from %bbB to %bbD 'c' and from %bbB to - // %bbC probability 'd'. - // - // We transform the IR into: - // bbA: - // br i1 %z, label %bbD, label %bbC - // where the probability of going to %bbD is (a*c) and going to bbC is - // (b+a*d). - // - // Probabilities aren't stored as ratios directly. Using branch weights, - // we get: - // (a*c)% = A*C, (b+(a*d))% = A*D+B*C+B*D. - - // In the event of overflow, we want to drop the LSB of the input - // probabilities. - unsigned BitsLost; - - // Ignore overflow result on ProbTrue. - APInt ProbTrue = MultiplyAndLosePrecision(A, C, B, D, BitsLost); - - APInt Tmp1 = MultiplyAndLosePrecision(B, D, A, C, BitsLost); - if (BitsLost) { - ProbTrue = ProbTrue.lshr(BitsLost*2); - } - - APInt Tmp2 = MultiplyAndLosePrecision(A, D, C, B, BitsLost); - if (BitsLost) { - ProbTrue = ProbTrue.lshr(BitsLost*2); - Tmp1 = Tmp1.lshr(BitsLost*2); - } - - APInt Tmp3 = MultiplyAndLosePrecision(B, C, A, D, BitsLost); - if (BitsLost) { - ProbTrue = ProbTrue.lshr(BitsLost*2); - Tmp1 = Tmp1.lshr(BitsLost*2); - Tmp2 = Tmp2.lshr(BitsLost*2); - } - - bool Overflow1 = false, Overflow2 = false; - APInt Tmp4 = Tmp2.uadd_ov(Tmp3, Overflow1); - APInt ProbFalse = Tmp4.uadd_ov(Tmp1, Overflow2); - - if (Overflow1 || Overflow2) { - ProbTrue = ProbTrue.lshr(1); - Tmp1 = Tmp1.lshr(1); - Tmp2 = Tmp2.lshr(1); - Tmp3 = Tmp3.lshr(1); - Tmp4 = Tmp2 + Tmp3; - ProbFalse = Tmp4 + Tmp1; - } - - // The sum of branch weights must fit in 32-bits. - if (ProbTrue.isNegative() && ProbFalse.isNegative()) { - ProbTrue = ProbTrue.lshr(1); - ProbFalse = ProbFalse.lshr(1); - } - - if (ProbTrue != ProbFalse) { - // Normalize the result. - APInt GCD = APIntOps::GreatestCommonDivisor(ProbTrue, ProbFalse); - ProbTrue = ProbTrue.udiv(GCD); - ProbFalse = ProbFalse.udiv(GCD); - - MDBuilder MDB(BI->getContext()); - MDNode *N = MDB.createBranchWeights(ProbTrue.getZExtValue(), - ProbFalse.getZExtValue()); - PBI->setMetadata(LLVMContext::MD_prof, N); - } else { - PBI->setMetadata(LLVMContext::MD_prof, NULL); - } - } else { - PBI->setMetadata(LLVMContext::MD_prof, NULL); - } - // Copy any debug value intrinsics into the end of PredBlock. for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) if (isa<DbgInfoIntrinsic>(*I)) @@ -2223,6 +2326,33 @@ static bool SimplifyCondBranchToCondBranch(BranchInst *PBI, BranchInst *BI) { PBI->setSuccessor(0, CommonDest); PBI->setSuccessor(1, OtherDest); + // Update branch weight for PBI. + uint64_t PredTrueWeight, PredFalseWeight, SuccTrueWeight, SuccFalseWeight; + bool PredHasWeights = ExtractBranchMetadata(PBI, PredTrueWeight, + PredFalseWeight); + bool SuccHasWeights = ExtractBranchMetadata(BI, SuccTrueWeight, + SuccFalseWeight); + if (PredHasWeights && SuccHasWeights) { + uint64_t PredCommon = PBIOp ? PredFalseWeight : PredTrueWeight; + uint64_t PredOther = PBIOp ?PredTrueWeight : PredFalseWeight; + uint64_t SuccCommon = BIOp ? SuccFalseWeight : SuccTrueWeight; + uint64_t SuccOther = BIOp ? SuccTrueWeight : SuccFalseWeight; + // The weight to CommonDest should be PredCommon * SuccTotal + + // PredOther * SuccCommon. + // The weight to OtherDest should be PredOther * SuccOther. + SmallVector<uint64_t, 2> NewWeights; + NewWeights.push_back(PredCommon * (SuccCommon + SuccOther) + + PredOther * SuccCommon); + NewWeights.push_back(PredOther * SuccOther); + // Halve the weights if any of them cannot fit in an uint32_t + FitWeights(NewWeights); + + SmallVector<uint32_t, 2> MDWeights(NewWeights.begin(),NewWeights.end()); + PBI->setMetadata(LLVMContext::MD_prof, + MDBuilder(BI->getContext()). + createBranchWeights(MDWeights)); + } + // OtherDest may have phi nodes. If so, add an entry from PBI's // block that are identical to the entries for BI's block. AddPredecessorToBlock(OtherDest, PBI->getParent(), BB); @@ -2259,7 +2389,9 @@ static bool SimplifyCondBranchToCondBranch(BranchInst *PBI, BranchInst *BI) { // Also makes sure not to introduce new successors by assuming that edges to // non-successor TrueBBs and FalseBBs aren't reachable. static bool SimplifyTerminatorOnSelect(TerminatorInst *OldTerm, Value *Cond, - BasicBlock *TrueBB, BasicBlock *FalseBB){ + BasicBlock *TrueBB, BasicBlock *FalseBB, + uint32_t TrueWeight, + uint32_t FalseWeight){ // Remove any superfluous successor edges from the CFG. // First, figure out which successors to preserve. // If TrueBB and FalseBB are equal, only try to preserve one copy of that @@ -2288,10 +2420,15 @@ static bool SimplifyTerminatorOnSelect(TerminatorInst *OldTerm, Value *Cond, // We were only looking for one successor, and it was present. // Create an unconditional branch to it. Builder.CreateBr(TrueBB); - else + else { // We found both of the successors we were looking for. // Create a conditional branch sharing the condition of the select. - Builder.CreateCondBr(Cond, TrueBB, FalseBB); + BranchInst *NewBI = Builder.CreateCondBr(Cond, TrueBB, FalseBB); + if (TrueWeight != FalseWeight) + NewBI->setMetadata(LLVMContext::MD_prof, + MDBuilder(OldTerm->getContext()). + createBranchWeights(TrueWeight, FalseWeight)); + } } else if (KeepEdge1 && (KeepEdge2 || TrueBB == FalseBB)) { // Neither of the selected blocks were successors, so this // terminator must be unreachable. @@ -2328,8 +2465,23 @@ static bool SimplifySwitchOnSelect(SwitchInst *SI, SelectInst *Select) { BasicBlock *TrueBB = SI->findCaseValue(TrueVal).getCaseSuccessor(); BasicBlock *FalseBB = SI->findCaseValue(FalseVal).getCaseSuccessor(); + // Get weight for TrueBB and FalseBB. + uint32_t TrueWeight = 0, FalseWeight = 0; + SmallVector<uint64_t, 8> Weights; + bool HasWeights = HasBranchWeights(SI); + if (HasWeights) { + GetBranchWeights(SI, Weights); + if (Weights.size() == 1 + SI->getNumCases()) { + TrueWeight = (uint32_t)Weights[SI->findCaseValue(TrueVal). + getSuccessorIndex()]; + FalseWeight = (uint32_t)Weights[SI->findCaseValue(FalseVal). + getSuccessorIndex()]; + } + } + // Perform the actual simplification. - return SimplifyTerminatorOnSelect(SI, Condition, TrueBB, FalseBB); + return SimplifyTerminatorOnSelect(SI, Condition, TrueBB, FalseBB, + TrueWeight, FalseWeight); } // SimplifyIndirectBrOnSelect - Replaces @@ -2349,7 +2501,8 @@ static bool SimplifyIndirectBrOnSelect(IndirectBrInst *IBI, SelectInst *SI) { BasicBlock *FalseBB = FBA->getBasicBlock(); // Perform the actual simplification. - return SimplifyTerminatorOnSelect(IBI, SI->getCondition(), TrueBB, FalseBB); + return SimplifyTerminatorOnSelect(IBI, SI->getCondition(), TrueBB, FalseBB, + 0, 0); } /// TryToSimplifyUncondBranchWithICmpInIt - This is called when we find an icmp @@ -2369,9 +2522,9 @@ static bool SimplifyIndirectBrOnSelect(IndirectBrInst *IBI, SelectInst *SI) { /// /// We prefer to split the edge to 'end' so that there is a true/false entry to /// the PHI, merging the third icmp into the switch. -static bool TryToSimplifyUncondBranchWithICmpInIt(ICmpInst *ICI, - const TargetData *TD, - IRBuilder<> &Builder) { +static bool TryToSimplifyUncondBranchWithICmpInIt( + ICmpInst *ICI, IRBuilder<> &Builder, const TargetTransformInfo &TTI, + const DataLayout *TD) { BasicBlock *BB = ICI->getParent(); // If the block has any PHIs in it or the icmp has multiple uses, it is too @@ -2404,7 +2557,7 @@ static bool TryToSimplifyUncondBranchWithICmpInIt(ICmpInst *ICI, ICI->eraseFromParent(); } // BB is now empty, so it is likely to simplify away. - return SimplifyCFG(BB) | true; + return SimplifyCFG(BB, TTI, TD) | true; } // Ok, the block is reachable from the default dest. If the constant we're @@ -2420,7 +2573,7 @@ static bool TryToSimplifyUncondBranchWithICmpInIt(ICmpInst *ICI, ICI->replaceAllUsesWith(V); ICI->eraseFromParent(); // BB is now empty, so it is likely to simplify away. - return SimplifyCFG(BB) | true; + return SimplifyCFG(BB, TTI, TD) | true; } // The use of the icmp has to be in the 'end' block, by the only PHI node in @@ -2448,6 +2601,21 @@ static bool TryToSimplifyUncondBranchWithICmpInIt(ICmpInst *ICI, // the switch to the merge point on the compared value. BasicBlock *NewBB = BasicBlock::Create(BB->getContext(), "switch.edge", BB->getParent(), BB); + SmallVector<uint64_t, 8> Weights; + bool HasWeights = HasBranchWeights(SI); + if (HasWeights) { + GetBranchWeights(SI, Weights); + if (Weights.size() == 1 + SI->getNumCases()) { + // Split weight for default case to case for "Cst". + Weights[0] = (Weights[0]+1) >> 1; + Weights.push_back(Weights[0]); + + SmallVector<uint32_t, 8> MDWeights(Weights.begin(), Weights.end()); + SI->setMetadata(LLVMContext::MD_prof, + MDBuilder(SI->getContext()). + createBranchWeights(MDWeights)); + } + } SI->addCase(Cst, NewBB); // NewBB branches to the phi block, add the uncond branch and the phi entry. @@ -2461,7 +2629,7 @@ static bool TryToSimplifyUncondBranchWithICmpInIt(ICmpInst *ICI, /// SimplifyBranchOnICmpChain - The specified branch is a conditional branch. /// Check to see if it is branching on an or/and chain of icmp instructions, and /// fold it into a switch instruction if so. -static bool SimplifyBranchOnICmpChain(BranchInst *BI, const TargetData *TD, +static bool SimplifyBranchOnICmpChain(BranchInst *BI, const DataLayout *TD, IRBuilder<> &Builder) { Instruction *Cond = dyn_cast<Instruction>(BI->getCondition()); if (Cond == 0) return false; @@ -2542,7 +2710,7 @@ static bool SimplifyBranchOnICmpChain(BranchInst *BI, const TargetData *TD, Builder.SetInsertPoint(BI); // Convert pointer to int before we switch. if (CompVal->getType()->isPointerTy()) { - assert(TD && "Cannot switch on pointer without TargetData"); + assert(TD && "Cannot switch on pointer without DataLayout"); CompVal = Builder.CreatePtrToInt(CompVal, TD->getIntPtrType(CompVal->getContext()), "magicptr"); @@ -2861,9 +3029,28 @@ static bool TurnSwitchRangeIntoICmp(SwitchInst *SI, IRBuilder<> &Builder) { if (!Offset->isNullValue()) Sub = Builder.CreateAdd(Sub, Offset, Sub->getName()+".off"); Value *Cmp = Builder.CreateICmpULT(Sub, NumCases, "switch"); - Builder.CreateCondBr( + BranchInst *NewBI = Builder.CreateCondBr( Cmp, SI->case_begin().getCaseSuccessor(), SI->getDefaultDest()); + // Update weight for the newly-created conditional branch. + SmallVector<uint64_t, 8> Weights; + bool HasWeights = HasBranchWeights(SI); + if (HasWeights) { + GetBranchWeights(SI, Weights); + if (Weights.size() == 1 + SI->getNumCases()) { + // Combine all weights for the cases to be the true weight of NewBI. + // We assume that the sum of all weights for a Terminator can fit into 32 + // bits. + uint32_t NewTrueWeight = 0; + for (unsigned I = 1, E = Weights.size(); I != E; ++I) + NewTrueWeight += (uint32_t)Weights[I]; + NewBI->setMetadata(LLVMContext::MD_prof, + MDBuilder(SI->getContext()). + createBranchWeights(NewTrueWeight, + (uint32_t)Weights[0])); + } + } + // Prune obsolete incoming values off the successor's PHI nodes. for (BasicBlock::iterator BBI = SI->case_begin().getCaseSuccessor()->begin(); isa<PHINode>(BBI); ++BBI) { @@ -2894,15 +3081,33 @@ static bool EliminateDeadSwitchCases(SwitchInst *SI) { } } + SmallVector<uint64_t, 8> Weights; + bool HasWeight = HasBranchWeights(SI); + if (HasWeight) { + GetBranchWeights(SI, Weights); + HasWeight = (Weights.size() == 1 + SI->getNumCases()); + } + // Remove dead cases from the switch. for (unsigned I = 0, E = DeadCases.size(); I != E; ++I) { SwitchInst::CaseIt Case = SI->findCaseValue(DeadCases[I]); assert(Case != SI->case_default() && "Case was not found. Probably mistake in DeadCases forming."); + if (HasWeight) { + std::swap(Weights[Case.getCaseIndex()+1], Weights.back()); + Weights.pop_back(); + } + // Prune unused values from PHI nodes. Case.getCaseSuccessor()->removePredecessor(SI->getParent()); SI->removeCase(Case); } + if (HasWeight) { + SmallVector<uint32_t, 8> MDWeights(Weights.begin(), Weights.end()); + SI->setMetadata(LLVMContext::MD_prof, + MDBuilder(SI->getParent()->getContext()). + createBranchWeights(MDWeights)); + } return !DeadCases.empty(); } @@ -2991,26 +3196,95 @@ static bool ValidLookupTableConstant(Constant *C) { isa<UndefValue>(C); } -/// GetCaseResulsts - Try to determine the resulting constant values in phi -/// nodes at the common destination basic block for one of the case -/// destinations of a switch instruction. +/// LookupConstant - If V is a Constant, return it. Otherwise, try to look up +/// its constant value in ConstantPool, returning 0 if it's not there. +static Constant *LookupConstant(Value *V, + const SmallDenseMap<Value*, Constant*>& ConstantPool) { + if (Constant *C = dyn_cast<Constant>(V)) + return C; + return ConstantPool.lookup(V); +} + +/// ConstantFold - Try to fold instruction I into a constant. This works for +/// simple instructions such as binary operations where both operands are +/// constant or can be replaced by constants from the ConstantPool. Returns the +/// resulting constant on success, 0 otherwise. +static Constant *ConstantFold(Instruction *I, + const SmallDenseMap<Value*, Constant*>& ConstantPool) { + if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) { + Constant *A = LookupConstant(BO->getOperand(0), ConstantPool); + if (!A) + return 0; + Constant *B = LookupConstant(BO->getOperand(1), ConstantPool); + if (!B) + return 0; + return ConstantExpr::get(BO->getOpcode(), A, B); + } + + if (CmpInst *Cmp = dyn_cast<CmpInst>(I)) { + Constant *A = LookupConstant(I->getOperand(0), ConstantPool); + if (!A) + return 0; + Constant *B = LookupConstant(I->getOperand(1), ConstantPool); + if (!B) + return 0; + return ConstantExpr::getCompare(Cmp->getPredicate(), A, B); + } + + if (SelectInst *Select = dyn_cast<SelectInst>(I)) { + Constant *A = LookupConstant(Select->getCondition(), ConstantPool); + if (!A) + return 0; + if (A->isAllOnesValue()) + return LookupConstant(Select->getTrueValue(), ConstantPool); + if (A->isNullValue()) + return LookupConstant(Select->getFalseValue(), ConstantPool); + return 0; + } + + if (CastInst *Cast = dyn_cast<CastInst>(I)) { + Constant *A = LookupConstant(I->getOperand(0), ConstantPool); + if (!A) + return 0; + return ConstantExpr::getCast(Cast->getOpcode(), A, Cast->getDestTy()); + } + + return 0; +} + +/// GetCaseResults - Try to determine the resulting constant values in phi nodes +/// at the common destination basic block, *CommonDest, for one of the case +/// destionations CaseDest corresponding to value CaseVal (0 for the default +/// case), of a switch instruction SI. static bool GetCaseResults(SwitchInst *SI, + ConstantInt *CaseVal, BasicBlock *CaseDest, BasicBlock **CommonDest, SmallVector<std::pair<PHINode*,Constant*>, 4> &Res) { // The block from which we enter the common destination. BasicBlock *Pred = SI->getParent(); - // If CaseDest is empty, continue to its successor. - if (CaseDest->getFirstNonPHIOrDbg() == CaseDest->getTerminator() && - !isa<PHINode>(CaseDest->begin())) { - - TerminatorInst *Terminator = CaseDest->getTerminator(); - if (Terminator->getNumSuccessors() != 1) - return false; - - Pred = CaseDest; - CaseDest = Terminator->getSuccessor(0); + // If CaseDest is empty except for some side-effect free instructions through + // which we can constant-propagate the CaseVal, continue to its successor. + SmallDenseMap<Value*, Constant*> ConstantPool; + ConstantPool.insert(std::make_pair(SI->getCondition(), CaseVal)); + for (BasicBlock::iterator I = CaseDest->begin(), E = CaseDest->end(); I != E; + ++I) { + if (TerminatorInst *T = dyn_cast<TerminatorInst>(I)) { + // If the terminator is a simple branch, continue to the next block. + if (T->getNumSuccessors() != 1) + return false; + Pred = CaseDest; + CaseDest = T->getSuccessor(0); + } else if (isa<DbgInfoIntrinsic>(I)) { + // Skip debug intrinsic. + continue; + } else if (Constant *C = ConstantFold(I, ConstantPool)) { + // Instruction is side-effect free and constant. + ConstantPool.insert(std::make_pair(I, C)); + } else { + break; + } } // If we did not have a CommonDest before, use the current one. @@ -3027,10 +3301,17 @@ static bool GetCaseResults(SwitchInst *SI, if (Idx == -1) continue; - Constant *ConstVal = dyn_cast<Constant>(PHI->getIncomingValue(Idx)); + Constant *ConstVal = LookupConstant(PHI->getIncomingValue(Idx), + ConstantPool); if (!ConstVal) return false; + // Note: If the constant comes from constant-propagating the case value + // through the CaseDest basic block, it will be safe to remove the + // instructions in that block. They cannot be used (except in the phi nodes + // we visit) outside CaseDest, because that block does not dominate its + // successor. If it did, we would not be in this phi node. + // Be conservative about which kinds of constants we support. if (!ValidLookupTableConstant(ConstVal)) return false; @@ -3041,83 +3322,255 @@ static bool GetCaseResults(SwitchInst *SI, return true; } -/// BuildLookupTable - Build a lookup table with the contents of Results, using -/// DefaultResult to fill the holes in the table. If the table ends up -/// containing the same result in each element, set *SingleResult to that value -/// and return NULL. -static GlobalVariable *BuildLookupTable(Module &M, - uint64_t TableSize, - ConstantInt *Offset, - const SmallVector<std::pair<ConstantInt*, Constant*>, 4>& Results, - Constant *DefaultResult, - Constant **SingleResult) { - assert(Results.size() && "Need values to build lookup table"); - assert(TableSize >= Results.size() && "Table needs to hold all values"); +namespace { + /// SwitchLookupTable - This class represents a lookup table that can be used + /// to replace a switch. + class SwitchLookupTable { + public: + /// SwitchLookupTable - Create a lookup table to use as a switch replacement + /// with the contents of Values, using DefaultValue to fill any holes in the + /// table. + SwitchLookupTable(Module &M, + uint64_t TableSize, + ConstantInt *Offset, + const SmallVector<std::pair<ConstantInt*, Constant*>, 4>& Values, + Constant *DefaultValue, + const DataLayout *TD); + + /// BuildLookup - Build instructions with Builder to retrieve the value at + /// the position given by Index in the lookup table. + Value *BuildLookup(Value *Index, IRBuilder<> &Builder); + + /// WouldFitInRegister - Return true if a table with TableSize elements of + /// type ElementType would fit in a target-legal register. + static bool WouldFitInRegister(const DataLayout *TD, + uint64_t TableSize, + const Type *ElementType); + + private: + // Depending on the contents of the table, it can be represented in + // different ways. + enum { + // For tables where each element contains the same value, we just have to + // store that single value and return it for each lookup. + SingleValueKind, + + // For small tables with integer elements, we can pack them into a bitmap + // that fits into a target-legal register. Values are retrieved by + // shift and mask operations. + BitMapKind, + + // The table is stored as an array of values. Values are retrieved by load + // instructions from the table. + ArrayKind + } Kind; + + // For SingleValueKind, this is the single value. + Constant *SingleValue; + + // For BitMapKind, this is the bitmap. + ConstantInt *BitMap; + IntegerType *BitMapElementTy; + + // For ArrayKind, this is the array. + GlobalVariable *Array; + }; +} + +SwitchLookupTable::SwitchLookupTable(Module &M, + uint64_t TableSize, + ConstantInt *Offset, + const SmallVector<std::pair<ConstantInt*, Constant*>, 4>& Values, + Constant *DefaultValue, + const DataLayout *TD) { + assert(Values.size() && "Can't build lookup table without values!"); + assert(TableSize >= Values.size() && "Can't fit values in table!"); // If all values in the table are equal, this is that value. - Constant *SameResult = Results.begin()->second; + SingleValue = Values.begin()->second; // Build up the table contents. - std::vector<Constant*> TableContents(TableSize); - for (size_t I = 0, E = Results.size(); I != E; ++I) { - ConstantInt *CaseVal = Results[I].first; - Constant *CaseRes = Results[I].second; - - uint64_t Idx = (CaseVal->getValue() - Offset->getValue()).getLimitedValue(); + SmallVector<Constant*, 64> TableContents(TableSize); + for (size_t I = 0, E = Values.size(); I != E; ++I) { + ConstantInt *CaseVal = Values[I].first; + Constant *CaseRes = Values[I].second; + assert(CaseRes->getType() == DefaultValue->getType()); + + uint64_t Idx = (CaseVal->getValue() - Offset->getValue()) + .getLimitedValue(); TableContents[Idx] = CaseRes; - if (CaseRes != SameResult) - SameResult = NULL; + if (CaseRes != SingleValue) + SingleValue = 0; } // Fill in any holes in the table with the default result. - if (Results.size() < TableSize) { - for (unsigned i = 0; i < TableSize; ++i) { - if (!TableContents[i]) - TableContents[i] = DefaultResult; + if (Values.size() < TableSize) { + for (uint64_t I = 0; I < TableSize; ++I) { + if (!TableContents[I]) + TableContents[I] = DefaultValue; } - if (DefaultResult != SameResult) - SameResult = NULL; + if (DefaultValue != SingleValue) + SingleValue = 0; } - // Same result was used in the entire table; just return that. - if (SameResult) { - *SingleResult = SameResult; - return NULL; + // If each element in the table contains the same value, we only need to store + // that single value. + if (SingleValue) { + Kind = SingleValueKind; + return; } - ArrayType *ArrayTy = ArrayType::get(DefaultResult->getType(), TableSize); + // If the type is integer and the table fits in a register, build a bitmap. + if (WouldFitInRegister(TD, TableSize, DefaultValue->getType())) { + IntegerType *IT = cast<IntegerType>(DefaultValue->getType()); + APInt TableInt(TableSize * IT->getBitWidth(), 0); + for (uint64_t I = TableSize; I > 0; --I) { + TableInt <<= IT->getBitWidth(); + // Insert values into the bitmap. Undef values are set to zero. + if (!isa<UndefValue>(TableContents[I - 1])) { + ConstantInt *Val = cast<ConstantInt>(TableContents[I - 1]); + TableInt |= Val->getValue().zext(TableInt.getBitWidth()); + } + } + BitMap = ConstantInt::get(M.getContext(), TableInt); + BitMapElementTy = IT; + Kind = BitMapKind; + ++NumBitMaps; + return; + } + + // Store the table in an array. + ArrayType *ArrayTy = ArrayType::get(DefaultValue->getType(), TableSize); Constant *Initializer = ConstantArray::get(ArrayTy, TableContents); - GlobalVariable *GV = new GlobalVariable(M, ArrayTy, /*constant=*/ true, - GlobalVariable::PrivateLinkage, - Initializer, - "switch.table"); - GV->setUnnamedAddr(true); - return GV; + Array = new GlobalVariable(M, ArrayTy, /*constant=*/ true, + GlobalVariable::PrivateLinkage, + Initializer, + "switch.table"); + Array->setUnnamedAddr(true); + Kind = ArrayKind; +} + +Value *SwitchLookupTable::BuildLookup(Value *Index, IRBuilder<> &Builder) { + switch (Kind) { + case SingleValueKind: + return SingleValue; + case BitMapKind: { + // Type of the bitmap (e.g. i59). + IntegerType *MapTy = BitMap->getType(); + + // Cast Index to the same type as the bitmap. + // Note: The Index is <= the number of elements in the table, so + // truncating it to the width of the bitmask is safe. + Value *ShiftAmt = Builder.CreateZExtOrTrunc(Index, MapTy, "switch.cast"); + + // Multiply the shift amount by the element width. + ShiftAmt = Builder.CreateMul(ShiftAmt, + ConstantInt::get(MapTy, BitMapElementTy->getBitWidth()), + "switch.shiftamt"); + + // Shift down. + Value *DownShifted = Builder.CreateLShr(BitMap, ShiftAmt, + "switch.downshift"); + // Mask off. + return Builder.CreateTrunc(DownShifted, BitMapElementTy, + "switch.masked"); + } + case ArrayKind: { + Value *GEPIndices[] = { Builder.getInt32(0), Index }; + Value *GEP = Builder.CreateInBoundsGEP(Array, GEPIndices, + "switch.gep"); + return Builder.CreateLoad(GEP, "switch.load"); + } + } + llvm_unreachable("Unknown lookup table kind!"); +} + +bool SwitchLookupTable::WouldFitInRegister(const DataLayout *TD, + uint64_t TableSize, + const Type *ElementType) { + if (!TD) + return false; + const IntegerType *IT = dyn_cast<IntegerType>(ElementType); + if (!IT) + return false; + // FIXME: If the type is wider than it needs to be, e.g. i8 but all values + // are <= 15, we could try to narrow the type. + + // Avoid overflow, fitsInLegalInteger uses unsigned int for the width. + if (TableSize >= UINT_MAX/IT->getBitWidth()) + return false; + return TD->fitsInLegalInteger(TableSize * IT->getBitWidth()); +} + +/// ShouldBuildLookupTable - Determine whether a lookup table should be built +/// for this switch, based on the number of caes, size of the table and the +/// types of the results. +static bool ShouldBuildLookupTable(SwitchInst *SI, + uint64_t TableSize, + const TargetTransformInfo &TTI, + const DataLayout *TD, + const SmallDenseMap<PHINode*, Type*>& ResultTypes) { + if (SI->getNumCases() > TableSize || TableSize >= UINT64_MAX / 10) + return false; // TableSize overflowed, or mul below might overflow. + + bool AllTablesFitInRegister = true; + bool HasIllegalType = false; + for (SmallDenseMap<PHINode*, Type*>::const_iterator I = ResultTypes.begin(), + E = ResultTypes.end(); I != E; ++I) { + Type *Ty = I->second; + + // Saturate this flag to true. + HasIllegalType = HasIllegalType || !TTI.isTypeLegal(Ty); + + // Saturate this flag to false. + AllTablesFitInRegister = AllTablesFitInRegister && + SwitchLookupTable::WouldFitInRegister(TD, TableSize, Ty); + + // If both flags saturate, we're done. NOTE: This *only* works with + // saturating flags, and all flags have to saturate first due to the + // non-deterministic behavior of iterating over a dense map. + if (HasIllegalType && !AllTablesFitInRegister) + break; + } + + // If each table would fit in a register, we should build it anyway. + if (AllTablesFitInRegister) + return true; + + // Don't build a table that doesn't fit in-register if it has illegal types. + if (HasIllegalType) + return false; + + // The table density should be at least 40%. This is the same criterion as for + // jump tables, see SelectionDAGBuilder::handleJTSwitchCase. + // FIXME: Find the best cut-off. + return SI->getNumCases() * 10 >= TableSize * 4; } /// SwitchToLookupTable - If the switch is only used to initialize one or more /// phi nodes in a common successor block with different constant values, /// replace the switch with lookup tables. static bool SwitchToLookupTable(SwitchInst *SI, - IRBuilder<> &Builder) { + IRBuilder<> &Builder, + const TargetTransformInfo &TTI, + const DataLayout* TD) { assert(SI->getNumCases() > 1 && "Degenerate switch?"); - // FIXME: Handle unreachable cases. + + // Only build lookup table when we have a target that supports it. + if (!TTI.shouldBuildLookupTables()) + return false; // FIXME: If the switch is too sparse for a lookup table, perhaps we could // split off a dense part and build a lookup table for that. - // FIXME: If the results are all integers and the lookup table would fit in a - // target-legal register, we should store them as a bitmap and use shift/mask - // to look up the result. - // FIXME: This creates arrays of GEPs to constant strings, which means each // GEP needs a runtime relocation in PIC code. We should just build one big // string and lookup indices into that. - // Ignore the switch if the number of cases are too small. + // Ignore the switch if the number of cases is too small. // This is similar to the check when building jump tables in // SelectionDAGBuilder::handleJTSwitchCase. // FIXME: Determine the best cut-off. @@ -3131,7 +3584,7 @@ static bool SwitchToLookupTable(SwitchInst *SI, ConstantInt *MinCaseVal = CI.getCaseValue(); ConstantInt *MaxCaseVal = CI.getCaseValue(); - BasicBlock *CommonDest = NULL; + BasicBlock *CommonDest = 0; typedef SmallVector<std::pair<ConstantInt*, Constant*>, 4> ResultListTy; SmallDenseMap<PHINode*, ResultListTy> ResultLists; SmallDenseMap<PHINode*, Constant*> DefaultResults; @@ -3148,7 +3601,8 @@ static bool SwitchToLookupTable(SwitchInst *SI, // Resulting value at phi nodes for this case value. typedef SmallVector<std::pair<PHINode*, Constant*>, 4> ResultsTy; ResultsTy Results; - if (!GetCaseResults(SI, CI.getCaseSuccessor(), &CommonDest, Results)) + if (!GetCaseResults(SI, CaseVal, CI.getCaseSuccessor(), &CommonDest, + Results)) return false; // Append the result from this case to the list for each phi. @@ -3161,7 +3615,8 @@ static bool SwitchToLookupTable(SwitchInst *SI, // Get the resulting values for the default case. SmallVector<std::pair<PHINode*, Constant*>, 4> DefaultResultsList; - if (!GetCaseResults(SI, SI->getDefaultDest(), &CommonDest, DefaultResultsList)) + if (!GetCaseResults(SI, 0, SI->getDefaultDest(), &CommonDest, + DefaultResultsList)) return false; for (size_t I = 0, E = DefaultResultsList.size(); I != E; ++I) { PHINode *PHI = DefaultResultsList[I].first; @@ -3171,33 +3626,12 @@ static bool SwitchToLookupTable(SwitchInst *SI, } APInt RangeSpread = MaxCaseVal->getValue() - MinCaseVal->getValue(); - // The table density should be at lest 40%. This is the same criterion as for - // jump tables, see SelectionDAGBuilder::handleJTSwitchCase. - // FIXME: Find the best cut-off. - // Be careful to avoid overlow in the density computation. - if (RangeSpread.zextOrSelf(64).ugt(UINT64_MAX / 4 - 1)) - return false; uint64_t TableSize = RangeSpread.getLimitedValue() + 1; - if (SI->getNumCases() * 10 < TableSize * 4) + if (!ShouldBuildLookupTable(SI, TableSize, TTI, TD, ResultTypes)) return false; - // Build the lookup tables. - SmallDenseMap<PHINode*, GlobalVariable*> LookupTables; - SmallDenseMap<PHINode*, Constant*> SingleResults; - - Module &Mod = *CommonDest->getParent()->getParent(); - for (SmallVector<PHINode*, 4>::iterator I = PHIs.begin(), E = PHIs.end(); - I != E; ++I) { - PHINode *PHI = *I; - - Constant *SingleResult = NULL; - LookupTables[PHI] = BuildLookupTable(Mod, TableSize, MinCaseVal, - ResultLists[PHI], DefaultResults[PHI], - &SingleResult); - SingleResults[PHI] = SingleResult; - } - // Create the BB that does the lookups. + Module &Mod = *CommonDest->getParent()->getParent(); BasicBlock *LookupBB = BasicBlock::Create(Mod.getContext(), "switch.lookup", CommonDest->getParent(), @@ -3215,31 +3649,24 @@ static bool SwitchToLookupTable(SwitchInst *SI, // Populate the BB that does the lookups. Builder.SetInsertPoint(LookupBB); bool ReturnedEarly = false; - for (SmallVector<PHINode*, 4>::iterator I = PHIs.begin(), E = PHIs.end(); - I != E; ++I) { - PHINode *PHI = *I; - // There was a single result for this phi; just use that. - if (Constant *SingleResult = SingleResults[PHI]) { - PHI->addIncoming(SingleResult, LookupBB); - continue; - } + for (size_t I = 0, E = PHIs.size(); I != E; ++I) { + PHINode *PHI = PHIs[I]; - Value *GEPIndices[] = { Builder.getInt32(0), TableIndex }; - Value *GEP = Builder.CreateInBoundsGEP(LookupTables[PHI], GEPIndices, - "switch.gep"); - Value *Result = Builder.CreateLoad(GEP, "switch.load"); - - // If the result is only going to be used to return from the function, - // we want to do that right here. - if (PHI->hasOneUse() && isa<ReturnInst>(*PHI->use_begin())) { - if (CommonDest->getFirstNonPHIOrDbg() == CommonDest->getTerminator()) { - Builder.CreateRet(Result); - ReturnedEarly = true; - } + SwitchLookupTable Table(Mod, TableSize, MinCaseVal, ResultLists[PHI], + DefaultResults[PHI], TD); + + Value *Result = Table.BuildLookup(TableIndex, Builder); + + // If the result is used to return immediately from the function, we want to + // do that right here. + if (PHI->hasOneUse() && isa<ReturnInst>(*PHI->use_begin()) && + *PHI->use_begin() == CommonDest->getFirstNonPHIOrDbg()) { + Builder.CreateRet(Result); + ReturnedEarly = true; + break; } - if (!ReturnedEarly) - PHI->addIncoming(Result, LookupBB); + PHI->addIncoming(Result, LookupBB); } if (!ReturnedEarly) @@ -3258,46 +3685,44 @@ static bool SwitchToLookupTable(SwitchInst *SI, } bool SimplifyCFGOpt::SimplifySwitch(SwitchInst *SI, IRBuilder<> &Builder) { - // If this switch is too complex to want to look at, ignore it. - if (!isValueEqualityComparison(SI)) - return false; - BasicBlock *BB = SI->getParent(); - // If we only have one predecessor, and if it is a branch on this value, - // see if that predecessor totally determines the outcome of this switch. - if (BasicBlock *OnlyPred = BB->getSinglePredecessor()) - if (SimplifyEqualityComparisonWithOnlyPredecessor(SI, OnlyPred, Builder)) - return SimplifyCFG(BB) | true; + if (isValueEqualityComparison(SI)) { + // If we only have one predecessor, and if it is a branch on this value, + // see if that predecessor totally determines the outcome of this switch. + if (BasicBlock *OnlyPred = BB->getSinglePredecessor()) + if (SimplifyEqualityComparisonWithOnlyPredecessor(SI, OnlyPred, Builder)) + return SimplifyCFG(BB, TTI, TD) | true; - Value *Cond = SI->getCondition(); - if (SelectInst *Select = dyn_cast<SelectInst>(Cond)) - if (SimplifySwitchOnSelect(SI, Select)) - return SimplifyCFG(BB) | true; + Value *Cond = SI->getCondition(); + if (SelectInst *Select = dyn_cast<SelectInst>(Cond)) + if (SimplifySwitchOnSelect(SI, Select)) + return SimplifyCFG(BB, TTI, TD) | true; - // If the block only contains the switch, see if we can fold the block - // away into any preds. - BasicBlock::iterator BBI = BB->begin(); - // Ignore dbg intrinsics. - while (isa<DbgInfoIntrinsic>(BBI)) - ++BBI; - if (SI == &*BBI) - if (FoldValueComparisonIntoPredecessors(SI, Builder)) - return SimplifyCFG(BB) | true; + // If the block only contains the switch, see if we can fold the block + // away into any preds. + BasicBlock::iterator BBI = BB->begin(); + // Ignore dbg intrinsics. + while (isa<DbgInfoIntrinsic>(BBI)) + ++BBI; + if (SI == &*BBI) + if (FoldValueComparisonIntoPredecessors(SI, Builder)) + return SimplifyCFG(BB, TTI, TD) | true; + } // Try to transform the switch into an icmp and a branch. if (TurnSwitchRangeIntoICmp(SI, Builder)) - return SimplifyCFG(BB) | true; + return SimplifyCFG(BB, TTI, TD) | true; // Remove unreachable cases. if (EliminateDeadSwitchCases(SI)) - return SimplifyCFG(BB) | true; + return SimplifyCFG(BB, TTI, TD) | true; if (ForwardSwitchConditionToPHI(SI)) - return SimplifyCFG(BB) | true; + return SimplifyCFG(BB, TTI, TD) | true; - if (SwitchToLookupTable(SI, Builder)) - return SimplifyCFG(BB) | true; + if (SwitchToLookupTable(SI, Builder, TTI, TD)) + return SimplifyCFG(BB, TTI, TD) | true; return false; } @@ -3334,7 +3759,7 @@ bool SimplifyCFGOpt::SimplifyIndirectBr(IndirectBrInst *IBI) { if (SelectInst *SI = dyn_cast<SelectInst>(IBI->getAddress())) { if (SimplifyIndirectBrOnSelect(IBI, SI)) - return SimplifyCFG(BB) | true; + return SimplifyCFG(BB, TTI, TD) | true; } return Changed; } @@ -3342,6 +3767,9 @@ bool SimplifyCFGOpt::SimplifyIndirectBr(IndirectBrInst *IBI) { bool SimplifyCFGOpt::SimplifyUncondBranch(BranchInst *BI, IRBuilder<> &Builder){ BasicBlock *BB = BI->getParent(); + if (SinkCommon && SinkThenElseCodeToEnd(BI)) + return true; + // If the Terminator is the only non-phi instruction, simplify the block. BasicBlock::iterator I = BB->getFirstNonPHIOrDbgOrLifetime(); if (I->isTerminator() && BB != &BB->getParent()->getEntryBlock() && @@ -3355,7 +3783,7 @@ bool SimplifyCFGOpt::SimplifyUncondBranch(BranchInst *BI, IRBuilder<> &Builder){ for (++I; isa<DbgInfoIntrinsic>(I); ++I) ; if (I->isTerminator() && - TryToSimplifyUncondBranchWithICmpInIt(ICI, TD, Builder)) + TryToSimplifyUncondBranchWithICmpInIt(ICI, Builder, TTI, TD)) return true; } @@ -3364,7 +3792,7 @@ bool SimplifyCFGOpt::SimplifyUncondBranch(BranchInst *BI, IRBuilder<> &Builder){ // predecessor and use logical operations to update the incoming value // for PHI nodes in common successor. if (FoldBranchToCommonDest(BI)) - return SimplifyCFG(BB) | true; + return SimplifyCFG(BB, TTI, TD) | true; return false; } @@ -3379,7 +3807,7 @@ bool SimplifyCFGOpt::SimplifyCondBranch(BranchInst *BI, IRBuilder<> &Builder) { // switch. if (BasicBlock *OnlyPred = BB->getSinglePredecessor()) if (SimplifyEqualityComparisonWithOnlyPredecessor(BI, OnlyPred, Builder)) - return SimplifyCFG(BB) | true; + return SimplifyCFG(BB, TTI, TD) | true; // This block must be empty, except for the setcond inst, if it exists. // Ignore dbg intrinsics. @@ -3389,14 +3817,14 @@ bool SimplifyCFGOpt::SimplifyCondBranch(BranchInst *BI, IRBuilder<> &Builder) { ++I; if (&*I == BI) { if (FoldValueComparisonIntoPredecessors(BI, Builder)) - return SimplifyCFG(BB) | true; + return SimplifyCFG(BB, TTI, TD) | true; } else if (&*I == cast<Instruction>(BI->getCondition())){ ++I; // Ignore dbg intrinsics. while (isa<DbgInfoIntrinsic>(I)) ++I; if (&*I == BI && FoldValueComparisonIntoPredecessors(BI, Builder)) - return SimplifyCFG(BB) | true; + return SimplifyCFG(BB, TTI, TD) | true; } } @@ -3408,7 +3836,7 @@ bool SimplifyCFGOpt::SimplifyCondBranch(BranchInst *BI, IRBuilder<> &Builder) { // branches to us and one of our successors, fold the comparison into the // predecessor and use logical operations to pick the right destination. if (FoldBranchToCommonDest(BI)) - return SimplifyCFG(BB) | true; + return SimplifyCFG(BB, TTI, TD) | true; // We have a conditional branch to two blocks that are only reachable // from BI. We know that the condbr dominates the two blocks, so see if @@ -3417,7 +3845,7 @@ bool SimplifyCFGOpt::SimplifyCondBranch(BranchInst *BI, IRBuilder<> &Builder) { if (BI->getSuccessor(0)->getSinglePredecessor() != 0) { if (BI->getSuccessor(1)->getSinglePredecessor() != 0) { if (HoistThenElseCodeToIf(BI)) - return SimplifyCFG(BB) | true; + return SimplifyCFG(BB, TTI, TD) | true; } else { // If Successor #1 has multiple preds, we may be able to conditionally // execute Successor #0 if it branches to successor #1. @@ -3425,7 +3853,7 @@ bool SimplifyCFGOpt::SimplifyCondBranch(BranchInst *BI, IRBuilder<> &Builder) { if (Succ0TI->getNumSuccessors() == 1 && Succ0TI->getSuccessor(0) == BI->getSuccessor(1)) if (SpeculativelyExecuteBB(BI, BI->getSuccessor(0))) - return SimplifyCFG(BB) | true; + return SimplifyCFG(BB, TTI, TD) | true; } } else if (BI->getSuccessor(1)->getSinglePredecessor() != 0) { // If Successor #0 has multiple preds, we may be able to conditionally @@ -3434,7 +3862,7 @@ bool SimplifyCFGOpt::SimplifyCondBranch(BranchInst *BI, IRBuilder<> &Builder) { if (Succ1TI->getNumSuccessors() == 1 && Succ1TI->getSuccessor(0) == BI->getSuccessor(0)) if (SpeculativelyExecuteBB(BI, BI->getSuccessor(1))) - return SimplifyCFG(BB) | true; + return SimplifyCFG(BB, TTI, TD) | true; } // If this is a branch on a phi node in the current block, thread control @@ -3442,14 +3870,14 @@ bool SimplifyCFGOpt::SimplifyCondBranch(BranchInst *BI, IRBuilder<> &Builder) { if (PHINode *PN = dyn_cast<PHINode>(BI->getCondition())) if (PN->getParent() == BI->getParent()) if (FoldCondBranchOnPHI(BI, TD)) - return SimplifyCFG(BB) | true; + return SimplifyCFG(BB, TTI, TD) | true; // Scan predecessor blocks for conditional branches. for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI) if (BranchInst *PBI = dyn_cast<BranchInst>((*PI)->getTerminator())) if (PBI != BI && PBI->isConditional()) if (SimplifyCondBranchToCondBranch(PBI, BI)) - return SimplifyCFG(BB) | true; + return SimplifyCFG(BB, TTI, TD) | true; return false; } @@ -3460,11 +3888,12 @@ static bool passingValueIsAlwaysUndefined(Value *V, Instruction *I) { if (!C) return false; - if (!I->hasOneUse()) // Only look at single-use instructions, for compile time + if (I->use_empty()) return false; if (C->isNullValue()) { - Instruction *Use = I->use_back(); + // Only look at the first use, avoid hurting compile time with long uselists + User *Use = *I->use_begin(); // Now make sure that there are no instructions in between that can alter // control flow (eg. calls) @@ -3589,6 +4018,7 @@ bool SimplifyCFGOpt::run(BasicBlock *BB) { /// eliminates unreachable basic blocks, and does other "peephole" optimization /// of the CFG. It returns true if a modification was made. /// -bool llvm::SimplifyCFG(BasicBlock *BB, const TargetData *TD) { - return SimplifyCFGOpt(TD).run(BB); +bool llvm::SimplifyCFG(BasicBlock *BB, const TargetTransformInfo &TTI, + const DataLayout *TD) { + return SimplifyCFGOpt(TTI, TD).run(BB); } |