X-Git-Url: http://plrg.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FCodeGen%2FIfConversion.cpp;h=938c9cf603910d5eeca27c1ae57abfa0adae3ed7;hb=5ffc7bfc9a61b4c90d56c183fdcdc16836fa6600;hp=8cf68d660250dd481268246694e95889e1869bbb;hpb=2b33f4cbad43dcaca944d02a6ea67991ff9db9cf;p=oota-llvm.git diff --git a/lib/CodeGen/IfConversion.cpp b/lib/CodeGen/IfConversion.cpp index 8cf68d66025..938c9cf6039 100644 --- a/lib/CodeGen/IfConversion.cpp +++ b/lib/CodeGen/IfConversion.cpp @@ -11,27 +11,33 @@ // //===----------------------------------------------------------------------===// -#define DEBUG_TYPE "ifcvt" -#include "BranchFolding.h" -#include "llvm/Function.h" #include "llvm/CodeGen/Passes.h" -#include "llvm/CodeGen/MachineModuleInfo.h" +#include "BranchFolding.h" +#include "llvm/ADT/STLExtras.h" +#include "llvm/ADT/SmallSet.h" +#include "llvm/ADT/Statistic.h" +#include "llvm/CodeGen/LivePhysRegs.h" +#include "llvm/CodeGen/MachineBlockFrequencyInfo.h" +#include "llvm/CodeGen/MachineBranchProbabilityInfo.h" #include "llvm/CodeGen/MachineFunctionPass.h" -#include "llvm/CodeGen/MachineLoopInfo.h" +#include "llvm/CodeGen/MachineInstrBuilder.h" +#include "llvm/CodeGen/MachineModuleInfo.h" +#include "llvm/CodeGen/MachineRegisterInfo.h" +#include "llvm/CodeGen/TargetSchedule.h" #include "llvm/MC/MCInstrItineraries.h" -#include "llvm/Target/TargetInstrInfo.h" -#include "llvm/Target/TargetLowering.h" -#include "llvm/Target/TargetMachine.h" -#include "llvm/Target/TargetRegisterInfo.h" #include "llvm/Support/CommandLine.h" #include "llvm/Support/Debug.h" #include "llvm/Support/ErrorHandling.h" #include "llvm/Support/raw_ostream.h" -#include "llvm/ADT/SmallSet.h" -#include "llvm/ADT/Statistic.h" -#include "llvm/ADT/STLExtras.h" +#include "llvm/Target/TargetInstrInfo.h" +#include "llvm/Target/TargetLowering.h" +#include "llvm/Target/TargetRegisterInfo.h" +#include "llvm/Target/TargetSubtargetInfo.h" + using namespace llvm; +#define DEBUG_TYPE "ifcvt" + // Hidden options for help debugging. static cl::opt IfCvtFnStart("ifcvt-fn-start", cl::init(-1), cl::Hidden); static cl::opt IfCvtFnStop("ifcvt-fn-stop", cl::init(-1), cl::Hidden); @@ -62,6 +68,7 @@ STATISTIC(NumTriangleFRev, "Number of triangle (F/R) if-conversions performed"); STATISTIC(NumDiamonds, "Number of diamond if-conversions performed"); STATISTIC(NumIfConvBBs, "Number of if-converted blocks"); STATISTIC(NumDupBBs, "Number of duplicated blocks"); +STATISTIC(NumUnpred, "Number of true blocks of diamonds unpredicated"); namespace { class IfConverter : public MachineFunctionPass { @@ -121,7 +128,8 @@ namespace { IsAnalyzed(false), IsEnqueued(false), IsBrAnalyzable(false), HasFallThrough(false), IsUnpredicable(false), CannotBeCopied(false), ClobbersPred(false), NonPredSize(0), - ExtraCost(0), ExtraCost2(0), BB(0), TrueBB(0), FalseBB(0) {} + ExtraCost(0), ExtraCost2(0), BB(nullptr), TrueBB(nullptr), + FalseBB(nullptr) {} }; /// IfcvtToken - Record information about pending if-conversions to attempt: @@ -148,12 +156,19 @@ namespace { /// BBAnalysis - Results of if-conversion feasibility analysis indexed by /// basic block number. std::vector BBAnalysis; + TargetSchedModel SchedModel; - const TargetLowering *TLI; + const TargetLoweringBase *TLI; const TargetInstrInfo *TII; const TargetRegisterInfo *TRI; - const InstrItineraryData *InstrItins; - const MachineLoopInfo *MLI; + const MachineBlockFrequencyInfo *MBFI; + const MachineBranchProbabilityInfo *MBPI; + MachineRegisterInfo *MRI; + + LivePhysRegs Redefs; + LivePhysRegs DontKill; + + bool PreRegAlloc; bool MadeChange; int FnNum; public: @@ -161,22 +176,22 @@ namespace { IfConverter() : MachineFunctionPass(ID), FnNum(-1) { initializeIfConverterPass(*PassRegistry::getPassRegistry()); } - - virtual void getAnalysisUsage(AnalysisUsage &AU) const { - AU.addRequired(); + + void getAnalysisUsage(AnalysisUsage &AU) const override { + AU.addRequired(); + AU.addRequired(); MachineFunctionPass::getAnalysisUsage(AU); } - virtual bool runOnMachineFunction(MachineFunction &MF); - virtual const char *getPassName() const { return "If Converter"; } + bool runOnMachineFunction(MachineFunction &MF) override; private: bool ReverseBranchCondition(BBInfo &BBI); bool ValidSimple(BBInfo &TrueBBI, unsigned &Dups, - float Prediction, float Confidence) const; + const BranchProbability &Prediction) const; bool ValidTriangle(BBInfo &TrueBBI, BBInfo &FalseBBI, bool FalseBranch, unsigned &Dups, - float Prediction, float Confidence) const; + const BranchProbability &Prediction) const; bool ValidDiamond(BBInfo &TrueBBI, BBInfo &FalseBBI, unsigned &Dups1, unsigned &Dups2) const; void ScanInstructions(BBInfo &BBI); @@ -194,33 +209,32 @@ namespace { void PredicateBlock(BBInfo &BBI, MachineBasicBlock::iterator E, SmallVectorImpl &Cond, - SmallSet &Redefs); + SmallSet *LaterRedefs = nullptr); void CopyAndPredicateBlock(BBInfo &ToBBI, BBInfo &FromBBI, SmallVectorImpl &Cond, - SmallSet &Redefs, bool IgnoreBr = false); void MergeBlocks(BBInfo &ToBBI, BBInfo &FromBBI, bool AddEdges = true); bool MeetIfcvtSizeLimit(MachineBasicBlock &BB, unsigned Cycle, unsigned Extra, - float Prediction, float Confidence) const { + const BranchProbability &Prediction) const { return Cycle > 0 && TII->isProfitableToIfCvt(BB, Cycle, Extra, - Prediction, Confidence); + Prediction); } bool MeetIfcvtSizeLimit(MachineBasicBlock &TBB, unsigned TCycle, unsigned TExtra, MachineBasicBlock &FBB, unsigned FCycle, unsigned FExtra, - float Prediction, float Confidence) const { + const BranchProbability &Prediction) const { return TCycle > 0 && FCycle > 0 && TII->isProfitableToIfCvt(TBB, TCycle, TExtra, FBB, FCycle, FExtra, - Prediction, Confidence); + Prediction); } // blockAlwaysFallThrough - Block ends without a terminator. bool blockAlwaysFallThrough(BBInfo &BBI) const { - return BBI.IsBrAnalyzable && BBI.TrueBB == NULL; + return BBI.IsBrAnalyzable && BBI.TrueBB == nullptr; } // IfcvtTokenCmp - Used to sort if-conversion candidates. @@ -233,7 +247,7 @@ namespace { return true; else if (Incr1 == Incr2) { // Favors subsumption. - if (C1->NeedSubsumption == false && C2->NeedSubsumption == true) + if (!C1->NeedSubsumption && C2->NeedSubsumption) return true; else if (C1->NeedSubsumption == C2->NeedSubsumption) { // Favors diamond over triangle, etc. @@ -250,28 +264,36 @@ namespace { char IfConverter::ID = 0; } +char &llvm::IfConverterID = IfConverter::ID; + INITIALIZE_PASS_BEGIN(IfConverter, "if-converter", "If Converter", false, false) -INITIALIZE_PASS_DEPENDENCY(MachineLoopInfo) +INITIALIZE_PASS_DEPENDENCY(MachineBranchProbabilityInfo) INITIALIZE_PASS_END(IfConverter, "if-converter", "If Converter", false, false) -FunctionPass *llvm::createIfConverterPass() { return new IfConverter(); } - bool IfConverter::runOnMachineFunction(MachineFunction &MF) { - TLI = MF.getTarget().getTargetLowering(); - TII = MF.getTarget().getInstrInfo(); - TRI = MF.getTarget().getRegisterInfo(); - MLI = &getAnalysis(); - InstrItins = MF.getTarget().getInstrItineraryData(); + const TargetSubtargetInfo &ST = MF.getSubtarget(); + TLI = ST.getTargetLowering(); + TII = ST.getInstrInfo(); + TRI = ST.getRegisterInfo(); + MBFI = &getAnalysis(); + MBPI = &getAnalysis(); + MRI = &MF.getRegInfo(); + SchedModel.init(ST.getSchedModel(), &ST, TII); + if (!TII) return false; - // Tail merge tend to expose more if-conversion opportunities. - BranchFolder BF(true, false); - bool BFChange = BF.OptimizeFunction(MF, TII, - MF.getTarget().getRegisterInfo(), + PreRegAlloc = MRI->isSSA(); + + bool BFChange = false; + if (!PreRegAlloc) { + // Tail merge tend to expose more if-conversion opportunities. + BranchFolder BF(true, false, *MBFI, *MBPI); + BFChange = BF.OptimizeFunction(MF, TII, ST.getRegisterInfo(), getAnalysisIfAvailable()); + } DEBUG(dbgs() << "\nIfcvt: function (" << ++FnNum << ") \'" - << MF.getFunction()->getName() << "\'"); + << MF.getName() << "\'"); if (FnNum < IfCvtFnStart || (IfCvtFnStop != -1 && FnNum > IfCvtFnStop)) { DEBUG(dbgs() << " skipped\n"); @@ -312,8 +334,7 @@ bool IfConverter::runOnMachineFunction(MachineFunction &MF) { bool RetVal = false; switch (Kind) { - default: assert(false && "Unexpected!"); - break; + default: llvm_unreachable("Unexpected!"); case ICSimple: case ICSimpleFalse: { bool isFalse = Kind == ICSimpleFalse; @@ -399,9 +420,8 @@ bool IfConverter::runOnMachineFunction(MachineFunction &MF) { BBAnalysis.clear(); if (MadeChange && IfCvtBranchFold) { - BranchFolder BF(false, false); - BF.OptimizeFunction(MF, TII, - MF.getTarget().getRegisterInfo(), + BranchFolder BF(false, false, *MBFI, *MBPI); + BF.OptimizeFunction(MF, TII, MF.getSubtarget().getRegisterInfo(), getAnalysisIfAvailable()); } @@ -419,7 +439,7 @@ static MachineBasicBlock *findFalseBlock(MachineBasicBlock *BB, if (SuccBB != TrueBB) return SuccBB; } - return NULL; + return nullptr; } /// ReverseBranchCondition - Reverse the condition of the end of the block @@ -441,7 +461,7 @@ static inline MachineBasicBlock *getNextBlock(MachineBasicBlock *BB) { MachineFunction::iterator I = BB; MachineFunction::iterator E = BB->getParent()->end(); if (++I == E) - return NULL; + return nullptr; return I; } @@ -450,7 +470,7 @@ static inline MachineBasicBlock *getNextBlock(MachineBasicBlock *BB) { /// number of instructions that the ifcvt would need to duplicate if performed /// in Dups. bool IfConverter::ValidSimple(BBInfo &TrueBBI, unsigned &Dups, - float Prediction, float Confidence) const { + const BranchProbability &Prediction) const { Dups = 0; if (TrueBBI.IsBeingAnalyzed || TrueBBI.IsDone) return false; @@ -461,7 +481,7 @@ bool IfConverter::ValidSimple(BBInfo &TrueBBI, unsigned &Dups, if (TrueBBI.BB->pred_size() > 1) { if (TrueBBI.CannotBeCopied || !TII->isProfitableToDupForIfCvt(*TrueBBI.BB, TrueBBI.NonPredSize, - Prediction, Confidence)) + Prediction)) return false; Dups = TrueBBI.NonPredSize; } @@ -477,7 +497,7 @@ bool IfConverter::ValidSimple(BBInfo &TrueBBI, unsigned &Dups, /// if performed in 'Dups'. bool IfConverter::ValidTriangle(BBInfo &TrueBBI, BBInfo &FalseBBI, bool FalseBranch, unsigned &Dups, - float Prediction, float Confidence) const { + const BranchProbability &Prediction) const { Dups = 0; if (TrueBBI.IsBeingAnalyzed || TrueBBI.IsDone) return false; @@ -499,8 +519,7 @@ bool IfConverter::ValidTriangle(BBInfo &TrueBBI, BBInfo &FalseBBI, ++Size; } } - if (!TII->isProfitableToDupForIfCvt(*TrueBBI.BB, Size, - Prediction, Confidence)) + if (!TII->isProfitableToDupForIfCvt(*TrueBBI.BB, Size, Prediction)) return false; Dups = Size; } @@ -533,7 +552,7 @@ bool IfConverter::ValidDiamond(BBInfo &TrueBBI, BBInfo &FalseBBI, FT = getNextBlock(FalseBBI.BB); if (TT != FT) return false; - if (TT == NULL && (TrueBBI.IsBrAnalyzable || FalseBBI.IsBrAnalyzable)) + if (!TT && (TrueBBI.IsBrAnalyzable || FalseBBI.IsBrAnalyzable)) return false; if (TrueBBI.BB->pred_size() > 1 || FalseBBI.BB->pred_size() > 1) return false; @@ -573,12 +592,12 @@ bool IfConverter::ValidDiamond(BBInfo &TrueBBI, BBInfo &FalseBBI, // blocks, move the end iterators up past any branch instructions. while (TIE != TIB) { --TIE; - if (!TIE->getDesc().isBranch()) + if (!TIE->isBranch()) break; } while (FIE != FIB) { --FIE; - if (!FIE->getDesc().isBranch()) + if (!FIE->isBranch()) break; } @@ -621,13 +640,13 @@ void IfConverter::ScanInstructions(BBInfo &BBI) { if (BBI.IsDone) return; - bool AlreadyPredicated = BBI.Predicate.size() > 0; + bool AlreadyPredicated = !BBI.Predicate.empty(); // First analyze the end of BB branches. - BBI.TrueBB = BBI.FalseBB = NULL; + BBI.TrueBB = BBI.FalseBB = nullptr; BBI.BrCond.clear(); BBI.IsBrAnalyzable = !TII->AnalyzeBranch(*BBI.BB, BBI.TrueBB, BBI.FalseBB, BBI.BrCond); - BBI.HasFallThrough = BBI.IsBrAnalyzable && BBI.FalseBB == NULL; + BBI.HasFallThrough = BBI.IsBrAnalyzable && BBI.FalseBB == nullptr; if (BBI.BrCond.size()) { // No false branch. This BB must end with a conditional branch and a @@ -651,39 +670,34 @@ void IfConverter::ScanInstructions(BBInfo &BBI) { if (I->isDebugValue()) continue; - const MCInstrDesc &MCID = I->getDesc(); - if (MCID.isNotDuplicable()) + if (I->isNotDuplicable()) BBI.CannotBeCopied = true; bool isPredicated = TII->isPredicated(I); - bool isCondBr = BBI.IsBrAnalyzable && MCID.isConditionalBranch(); - - if (!isCondBr) { - if (!isPredicated) { - BBI.NonPredSize++; - unsigned ExtraPredCost = 0; - unsigned NumCycles = TII->getInstrLatency(InstrItins, &*I, - &ExtraPredCost); - if (NumCycles > 1) - BBI.ExtraCost += NumCycles-1; - BBI.ExtraCost2 += ExtraPredCost; - } else if (!AlreadyPredicated) { - // FIXME: This instruction is already predicated before the - // if-conversion pass. It's probably something like a conditional move. - // Mark this block unpredicable for now. - BBI.IsUnpredicable = true; - return; - } + bool isCondBr = BBI.IsBrAnalyzable && I->isConditionalBranch(); + + // A conditional branch is not predicable, but it may be eliminated. + if (isCondBr) + continue; + + if (!isPredicated) { + BBI.NonPredSize++; + unsigned ExtraPredCost = TII->getPredicationCost(&*I); + unsigned NumCycles = SchedModel.computeInstrLatency(&*I, false); + if (NumCycles > 1) + BBI.ExtraCost += NumCycles-1; + BBI.ExtraCost2 += ExtraPredCost; + } else if (!AlreadyPredicated) { + // FIXME: This instruction is already predicated before the + // if-conversion pass. It's probably something like a conditional move. + // Mark this block unpredicable for now. + BBI.IsUnpredicable = true; + return; } if (BBI.ClobbersPred && !isPredicated) { // Predicate modification instruction should end the block (except for // already predicated instructions and end of block branches). - if (isCondBr) { - // A conditional branch is not predicable, but it may be eliminated. - continue; - } - // Predicate may have been modified, the subsequent (currently) // unpredicated instructions cannot be correctly predicated. BBI.IsUnpredicable = true; @@ -712,9 +726,15 @@ bool IfConverter::FeasibilityAnalysis(BBInfo &BBI, if (BBI.IsDone || BBI.IsUnpredicable) return false; - // If it is already predicated, check if its predicate subsumes the new - // predicate. - if (BBI.Predicate.size() && !TII->SubsumesPredicate(BBI.Predicate, Pred)) + // If it is already predicated but we couldn't analyze its terminator, the + // latter might fallthrough, but we can't determine where to. + // Conservatively avoid if-converting again. + if (BBI.Predicate.size() && !BBI.IsBrAnalyzable) + return false; + + // If it is already predicated, check if the new predicate subsumes + // its predicate. + if (BBI.Predicate.size() && !TII->SubsumesPredicate(Pred, BBI.Predicate)) return false; if (BBI.BrCond.size()) { @@ -787,38 +807,18 @@ IfConverter::BBInfo &IfConverter::AnalyzeBlock(MachineBasicBlock *BB, unsigned Dups = 0; unsigned Dups2 = 0; - bool TNeedSub = TrueBBI.Predicate.size() > 0; - bool FNeedSub = FalseBBI.Predicate.size() > 0; + bool TNeedSub = !TrueBBI.Predicate.empty(); + bool FNeedSub = !FalseBBI.Predicate.empty(); bool Enqueued = false; - - // Try to predict the branch, using loop info to guide us. - // General heuristics are: - // - backedge -> 90% taken - // - early exit -> 20% taken - // - branch predictor confidence -> 90% - float Prediction = 0.5f; - float Confidence = 0.9f; - MachineLoop *Loop = MLI->getLoopFor(BB); - if (Loop) { - if (TrueBBI.BB == Loop->getHeader()) - Prediction = 0.9f; - else if (FalseBBI.BB == Loop->getHeader()) - Prediction = 0.1f; - - MachineLoop *TrueLoop = MLI->getLoopFor(TrueBBI.BB); - MachineLoop *FalseLoop = MLI->getLoopFor(FalseBBI.BB); - if (!TrueLoop || TrueLoop->getParentLoop() == Loop) - Prediction = 0.2f; - else if (!FalseLoop || FalseLoop->getParentLoop() == Loop) - Prediction = 0.8f; - } - + + BranchProbability Prediction = MBPI->getEdgeProbability(BB, TrueBBI.BB); + if (CanRevCond && ValidDiamond(TrueBBI, FalseBBI, Dups, Dups2) && MeetIfcvtSizeLimit(*TrueBBI.BB, (TrueBBI.NonPredSize - (Dups + Dups2) + TrueBBI.ExtraCost), TrueBBI.ExtraCost2, *FalseBBI.BB, (FalseBBI.NonPredSize - (Dups + Dups2) + FalseBBI.ExtraCost),FalseBBI.ExtraCost2, - Prediction, Confidence) && + Prediction) && FeasibilityAnalysis(TrueBBI, BBI.BrCond) && FeasibilityAnalysis(FalseBBI, RevCond)) { // Diamond: @@ -834,9 +834,9 @@ IfConverter::BBInfo &IfConverter::AnalyzeBlock(MachineBasicBlock *BB, Enqueued = true; } - if (ValidTriangle(TrueBBI, FalseBBI, false, Dups, Prediction, Confidence) && + if (ValidTriangle(TrueBBI, FalseBBI, false, Dups, Prediction) && MeetIfcvtSizeLimit(*TrueBBI.BB, TrueBBI.NonPredSize + TrueBBI.ExtraCost, - TrueBBI.ExtraCost2, Prediction, Confidence) && + TrueBBI.ExtraCost2, Prediction) && FeasibilityAnalysis(TrueBBI, BBI.BrCond, true)) { // Triangle: // EBB @@ -849,17 +849,17 @@ IfConverter::BBInfo &IfConverter::AnalyzeBlock(MachineBasicBlock *BB, Enqueued = true; } - if (ValidTriangle(TrueBBI, FalseBBI, true, Dups, Prediction, Confidence) && + if (ValidTriangle(TrueBBI, FalseBBI, true, Dups, Prediction) && MeetIfcvtSizeLimit(*TrueBBI.BB, TrueBBI.NonPredSize + TrueBBI.ExtraCost, - TrueBBI.ExtraCost2, Prediction, Confidence) && + TrueBBI.ExtraCost2, Prediction) && FeasibilityAnalysis(TrueBBI, BBI.BrCond, true, true)) { Tokens.push_back(new IfcvtToken(BBI, ICTriangleRev, TNeedSub, Dups)); Enqueued = true; } - if (ValidSimple(TrueBBI, Dups, Prediction, Confidence) && + if (ValidSimple(TrueBBI, Dups, Prediction) && MeetIfcvtSizeLimit(*TrueBBI.BB, TrueBBI.NonPredSize + TrueBBI.ExtraCost, - TrueBBI.ExtraCost2, Prediction, Confidence) && + TrueBBI.ExtraCost2, Prediction) && FeasibilityAnalysis(TrueBBI, BBI.BrCond)) { // Simple (split, no rejoin): // EBB @@ -875,29 +875,29 @@ IfConverter::BBInfo &IfConverter::AnalyzeBlock(MachineBasicBlock *BB, if (CanRevCond) { // Try the other path... if (ValidTriangle(FalseBBI, TrueBBI, false, Dups, - 1.0-Prediction, Confidence) && + Prediction.getCompl()) && MeetIfcvtSizeLimit(*FalseBBI.BB, FalseBBI.NonPredSize + FalseBBI.ExtraCost, - FalseBBI.ExtraCost2, 1.0-Prediction, Confidence) && + FalseBBI.ExtraCost2, Prediction.getCompl()) && FeasibilityAnalysis(FalseBBI, RevCond, true)) { Tokens.push_back(new IfcvtToken(BBI, ICTriangleFalse, FNeedSub, Dups)); Enqueued = true; } if (ValidTriangle(FalseBBI, TrueBBI, true, Dups, - 1.0-Prediction, Confidence) && + Prediction.getCompl()) && MeetIfcvtSizeLimit(*FalseBBI.BB, FalseBBI.NonPredSize + FalseBBI.ExtraCost, - FalseBBI.ExtraCost2, 1.0-Prediction, Confidence) && + FalseBBI.ExtraCost2, Prediction.getCompl()) && FeasibilityAnalysis(FalseBBI, RevCond, true, true)) { Tokens.push_back(new IfcvtToken(BBI, ICTriangleFRev, FNeedSub, Dups)); Enqueued = true; } - if (ValidSimple(FalseBBI, Dups, 1.0-Prediction, Confidence) && + if (ValidSimple(FalseBBI, Dups, Prediction.getCompl()) && MeetIfcvtSizeLimit(*FalseBBI.BB, FalseBBI.NonPredSize + FalseBBI.ExtraCost, - FalseBBI.ExtraCost2, 1.0-Prediction, Confidence) && + FalseBBI.ExtraCost2, Prediction.getCompl()) && FeasibilityAnalysis(FalseBBI, RevCond)) { Tokens.push_back(new IfcvtToken(BBI, ICSimpleFalse, FNeedSub, Dups)); Enqueued = true; @@ -928,7 +928,7 @@ void IfConverter::AnalyzeBlocks(MachineFunction &MF, /// next block). static bool canFallThroughTo(MachineBasicBlock *BB, MachineBasicBlock *ToBB) { MachineFunction::iterator PI = BB; - MachineFunction::iterator I = llvm::next(PI); + MachineFunction::iterator I = std::next(PI); MachineFunction::iterator TI = ToBB; MachineFunction::iterator E = BB->getParent()->end(); while (I != TI) { @@ -945,9 +945,8 @@ static bool canFallThroughTo(MachineBasicBlock *BB, MachineBasicBlock *ToBB) { /// to determine if it can be if-converted. If predecessor is already enqueued, /// dequeue it! void IfConverter::InvalidatePreds(MachineBasicBlock *BB) { - for (MachineBasicBlock::pred_iterator PI = BB->pred_begin(), - E = BB->pred_end(); PI != E; ++PI) { - BBInfo &PBBI = BBAnalysis[(*PI)->getNumber()]; + for (const auto &Predecessor : BB->predecessors()) { + BBInfo &PBBI = BBAnalysis[Predecessor->getNumber()]; if (PBBI.IsDone || PBBI.BB == BB) continue; PBBI.IsAnalyzed = false; @@ -961,76 +960,58 @@ static void InsertUncondBranch(MachineBasicBlock *BB, MachineBasicBlock *ToBB, const TargetInstrInfo *TII) { DebugLoc dl; // FIXME: this is nowhere SmallVector NoCond; - TII->InsertBranch(*BB, ToBB, NULL, NoCond, dl); + TII->InsertBranch(*BB, ToBB, nullptr, NoCond, dl); } /// RemoveExtraEdges - Remove true / false edges if either / both are no longer /// successors. void IfConverter::RemoveExtraEdges(BBInfo &BBI) { - MachineBasicBlock *TBB = NULL, *FBB = NULL; + MachineBasicBlock *TBB = nullptr, *FBB = nullptr; SmallVector Cond; if (!TII->AnalyzeBranch(*BBI.BB, TBB, FBB, Cond)) BBI.BB->CorrectExtraCFGEdges(TBB, FBB, !Cond.empty()); } -/// InitPredRedefs / UpdatePredRedefs - Defs by predicated instructions are -/// modeled as read + write (sort like two-address instructions). These -/// routines track register liveness and add implicit uses to if-converted -/// instructions to conform to the model. -static void InitPredRedefs(MachineBasicBlock *BB, SmallSet &Redefs, - const TargetRegisterInfo *TRI) { - for (MachineBasicBlock::livein_iterator I = BB->livein_begin(), - E = BB->livein_end(); I != E; ++I) { - unsigned Reg = *I; - Redefs.insert(Reg); - for (const unsigned *Subreg = TRI->getSubRegisters(Reg); - *Subreg; ++Subreg) - Redefs.insert(*Subreg); +/// Behaves like LiveRegUnits::StepForward() but also adds implicit uses to all +/// values defined in MI which are not live/used by MI. +static void UpdatePredRedefs(MachineInstr *MI, LivePhysRegs &Redefs) { + SmallVector, 4> Clobbers; + Redefs.stepForward(*MI, Clobbers); + + // Now add the implicit uses for each of the clobbered values. + for (auto Reg : Clobbers) { + const MachineOperand &Op = *Reg.second; + // FIXME: Const cast here is nasty, but better than making StepForward + // take a mutable instruction instead of const. + MachineInstr *OpMI = const_cast(Op.getParent()); + MachineInstrBuilder MIB(*OpMI->getParent()->getParent(), OpMI); + assert(Op.isReg() && "Register operand required"); + MIB.addReg(Reg.first, RegState::Implicit | RegState::Undef); } } -static void UpdatePredRedefs(MachineInstr *MI, SmallSet &Redefs, - const TargetRegisterInfo *TRI, - bool AddImpUse = false) { - SmallVector Defs; - for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) { - const MachineOperand &MO = MI->getOperand(i); - if (!MO.isReg()) - continue; - unsigned Reg = MO.getReg(); - if (!Reg) +/** + * Remove kill flags from operands with a registers in the @p DontKill set. + */ +static void RemoveKills(MachineInstr &MI, const LivePhysRegs &DontKill) { + for (MIBundleOperands O(&MI); O.isValid(); ++O) { + if (!O->isReg() || !O->isKill()) continue; - if (MO.isDef()) - Defs.push_back(Reg); - else if (MO.isKill()) { - Redefs.erase(Reg); - for (const unsigned *SR = TRI->getSubRegisters(Reg); *SR; ++SR) - Redefs.erase(*SR); - } - } - for (unsigned i = 0, e = Defs.size(); i != e; ++i) { - unsigned Reg = Defs[i]; - if (Redefs.count(Reg)) { - if (AddImpUse) - // Treat predicated update as read + write. - MI->addOperand(MachineOperand::CreateReg(Reg, false/*IsDef*/, - true/*IsImp*/,false/*IsKill*/)); - } else { - Redefs.insert(Reg); - for (const unsigned *SR = TRI->getSubRegisters(Reg); *SR; ++SR) - Redefs.insert(*SR); - } + if (DontKill.contains(O->getReg())) + O->setIsKill(false); } } -static void UpdatePredRedefs(MachineBasicBlock::iterator I, - MachineBasicBlock::iterator E, - SmallSet &Redefs, - const TargetRegisterInfo *TRI) { - while (I != E) { - UpdatePredRedefs(I, Redefs, TRI); - ++I; - } +/** + * Walks a range of machine instructions and removes kill flags for registers + * in the @p DontKill set. + */ +static void RemoveKills(MachineBasicBlock::iterator I, + MachineBasicBlock::iterator E, + const LivePhysRegs &DontKill, + const MCRegisterInfo &MCRI) { + for ( ; I != E; ++I) + RemoveKills(*I, DontKill); } /// IfConvertSimple - If convert a simple (split, no rejoin) sub-CFG. @@ -1053,23 +1034,37 @@ bool IfConverter::IfConvertSimple(BBInfo &BBI, IfcvtKind Kind) { return false; } + if (CvtBBI->BB->hasAddressTaken()) + // Conservatively abort if-conversion if BB's address is taken. + return false; + if (Kind == ICSimpleFalse) if (TII->ReverseBranchCondition(Cond)) - assert(false && "Unable to reverse branch condition!"); + llvm_unreachable("Unable to reverse branch condition!"); // Initialize liveins to the first BB. These are potentiall redefined by // predicated instructions. - SmallSet Redefs; - InitPredRedefs(CvtBBI->BB, Redefs, TRI); - InitPredRedefs(NextBBI->BB, Redefs, TRI); + Redefs.init(TRI); + Redefs.addLiveIns(CvtBBI->BB); + Redefs.addLiveIns(NextBBI->BB); + + // Compute a set of registers which must not be killed by instructions in + // BB1: This is everything live-in to BB2. + DontKill.init(TRI); + DontKill.addLiveIns(NextBBI->BB); if (CvtBBI->BB->pred_size() > 1) { BBI.NonPredSize -= TII->RemoveBranch(*BBI.BB); // Copy instructions in the true block, predicate them, and add them to // the entry block. - CopyAndPredicateBlock(BBI, *CvtBBI, Cond, Redefs); + CopyAndPredicateBlock(BBI, *CvtBBI, Cond); + + // RemoveExtraEdges won't work if the block has an unanalyzable branch, so + // explicitly remove CvtBBI as a successor. + BBI.BB->removeSuccessor(CvtBBI->BB); } else { - PredicateBlock(*CvtBBI, CvtBBI->BB->end(), Cond, Redefs); + RemoveKills(CvtBBI->BB->begin(), CvtBBI->BB->end(), DontKill, *TRI); + PredicateBlock(*CvtBBI, CvtBBI->BB->end(), Cond); // Merge converted block into entry block. BBI.NonPredSize -= TII->RemoveBranch(*BBI.BB); @@ -1105,6 +1100,28 @@ bool IfConverter::IfConvertSimple(BBInfo &BBI, IfcvtKind Kind) { return true; } +/// Scale down weights to fit into uint32_t. NewTrue is the new weight +/// for successor TrueBB, and NewFalse is the new weight for successor +/// FalseBB. +static void ScaleWeights(uint64_t NewTrue, uint64_t NewFalse, + MachineBasicBlock *MBB, + const MachineBasicBlock *TrueBB, + const MachineBasicBlock *FalseBB, + const MachineBranchProbabilityInfo *MBPI) { + uint64_t NewMax = (NewTrue > NewFalse) ? NewTrue : NewFalse; + uint32_t Scale = (NewMax / UINT32_MAX) + 1; + for (MachineBasicBlock::succ_iterator SI = MBB->succ_begin(), + SE = MBB->succ_end(); + SI != SE; ++SI) { + if (*SI == TrueBB) + MBB->setSuccWeight(SI, (uint32_t)(NewTrue / Scale)); + else if (*SI == FalseBB) + MBB->setSuccWeight(SI, (uint32_t)(NewFalse / Scale)); + else + MBB->setSuccWeight(SI, MBPI->getEdgeWeight(MBB, SI) / Scale); + } +} + /// IfConvertTriangle - If convert a triangle sub-CFG. /// bool IfConverter::IfConvertTriangle(BBInfo &BBI, IfcvtKind Kind) { @@ -1126,9 +1143,13 @@ bool IfConverter::IfConvertTriangle(BBInfo &BBI, IfcvtKind Kind) { return false; } + if (CvtBBI->BB->hasAddressTaken()) + // Conservatively abort if-conversion if BB's address is taken. + return false; + if (Kind == ICTriangleFalse || Kind == ICTriangleFRev) if (TII->ReverseBranchCondition(Cond)) - assert(false && "Unable to reverse branch condition!"); + llvm_unreachable("Unable to reverse branch condition!"); if (Kind == ICTriangleRev || Kind == ICTriangleFRev) { if (ReverseBranchCondition(*CvtBBI)) { @@ -1150,20 +1171,38 @@ bool IfConverter::IfConvertTriangle(BBInfo &BBI, IfcvtKind Kind) { // Initialize liveins to the first BB. These are potentially redefined by // predicated instructions. - SmallSet Redefs; - InitPredRedefs(CvtBBI->BB, Redefs, TRI); - InitPredRedefs(NextBBI->BB, Redefs, TRI); + Redefs.init(TRI); + Redefs.addLiveIns(CvtBBI->BB); + Redefs.addLiveIns(NextBBI->BB); + + DontKill.clear(); + + bool HasEarlyExit = CvtBBI->FalseBB != nullptr; + uint64_t CvtNext = 0, CvtFalse = 0, BBNext = 0, BBCvt = 0, SumWeight = 0; + uint32_t WeightScale = 0; + + if (HasEarlyExit) { + // Get weights before modifying CvtBBI->BB and BBI.BB. + CvtNext = MBPI->getEdgeWeight(CvtBBI->BB, NextBBI->BB); + CvtFalse = MBPI->getEdgeWeight(CvtBBI->BB, CvtBBI->FalseBB); + BBNext = MBPI->getEdgeWeight(BBI.BB, NextBBI->BB); + BBCvt = MBPI->getEdgeWeight(BBI.BB, CvtBBI->BB); + SumWeight = MBPI->getSumForBlock(CvtBBI->BB, WeightScale); + } - bool HasEarlyExit = CvtBBI->FalseBB != NULL; if (CvtBBI->BB->pred_size() > 1) { BBI.NonPredSize -= TII->RemoveBranch(*BBI.BB); // Copy instructions in the true block, predicate them, and add them to // the entry block. - CopyAndPredicateBlock(BBI, *CvtBBI, Cond, Redefs, true); + CopyAndPredicateBlock(BBI, *CvtBBI, Cond, true); + + // RemoveExtraEdges won't work if the block has an unanalyzable branch, so + // explicitly remove CvtBBI as a successor. + BBI.BB->removeSuccessor(CvtBBI->BB); } else { // Predicate the 'true' block after removing its branch. CvtBBI->NonPredSize -= TII->RemoveBranch(*CvtBBI->BB); - PredicateBlock(*CvtBBI, CvtBBI->BB->end(), Cond, Redefs); + PredicateBlock(*CvtBBI, CvtBBI->BB->end(), Cond); // Now merge the entry of the triangle with the true block. BBI.NonPredSize -= TII->RemoveBranch(*BBI.BB); @@ -1175,9 +1214,23 @@ bool IfConverter::IfConvertTriangle(BBInfo &BBI, IfcvtKind Kind) { SmallVector RevCond(CvtBBI->BrCond.begin(), CvtBBI->BrCond.end()); if (TII->ReverseBranchCondition(RevCond)) - assert(false && "Unable to reverse branch condition!"); - TII->InsertBranch(*BBI.BB, CvtBBI->FalseBB, NULL, RevCond, dl); + llvm_unreachable("Unable to reverse branch condition!"); + TII->InsertBranch(*BBI.BB, CvtBBI->FalseBB, nullptr, RevCond, dl); BBI.BB->addSuccessor(CvtBBI->FalseBB); + // Update the edge weight for both CvtBBI->FalseBB and NextBBI. + // New_Weight(BBI.BB, NextBBI->BB) = + // Weight(BBI.BB, NextBBI->BB) * getSumForBlock(CvtBBI->BB) + + // Weight(BBI.BB, CvtBBI->BB) * Weight(CvtBBI->BB, NextBBI->BB) + // New_Weight(BBI.BB, CvtBBI->FalseBB) = + // Weight(BBI.BB, CvtBBI->BB) * Weight(CvtBBI->BB, CvtBBI->FalseBB) + + uint64_t NewNext = BBNext * SumWeight + (BBCvt * CvtNext) / WeightScale; + uint64_t NewFalse = (BBCvt * CvtFalse) / WeightScale; + // We need to scale down all weights of BBI.BB to fit uint32_t. + // Here BBI.BB is connected to CvtBBI->FalseBB and will fall through to + // the next block. + ScaleWeights(NewNext, NewFalse, BBI.BB, getNextBlock(BBI.BB), + CvtBBI->FalseBB, MBPI); } // Merge in the 'false' block if the 'false' block has no other @@ -1190,7 +1243,8 @@ bool IfConverter::IfConvertTriangle(BBInfo &BBI, IfcvtKind Kind) { // block. By not merging them, we make it possible to iteratively // ifcvt the blocks. if (!HasEarlyExit && - NextBBI->BB->pred_size() == 1 && !NextBBI->HasFallThrough) { + NextBBI->BB->pred_size() == 1 && !NextBBI->HasFallThrough && + !NextBBI->BB->hasAddressTaken()) { MergeBlocks(BBI, *NextBBI); FalseBBDead = true; } else { @@ -1240,6 +1294,10 @@ bool IfConverter::IfConvertDiamond(BBInfo &BBI, IfcvtKind Kind, return false; } + if (TrueBBI.BB->hasAddressTaken() || FalseBBI.BB->hasAddressTaken()) + // Conservatively abort if-conversion if either BB has its address taken. + return false; + // Put the predicated instructions from the 'true' block before the // instructions from the 'false' block, unless the true block would clobber // the predicate, in which case, do the opposite. @@ -1247,7 +1305,7 @@ bool IfConverter::IfConvertDiamond(BBInfo &BBI, IfcvtKind Kind, BBInfo *BBI2 = &FalseBBI; SmallVector RevCond(BBI.BrCond.begin(), BBI.BrCond.end()); if (TII->ReverseBranchCondition(RevCond)) - assert(false && "Unable to reverse branch condition!"); + llvm_unreachable("Unable to reverse branch condition!"); SmallVector *Cond1 = &BBI.BrCond; SmallVector *Cond2 = &RevCond; @@ -1269,8 +1327,8 @@ bool IfConverter::IfConvertDiamond(BBInfo &BBI, IfcvtKind Kind, // Initialize liveins to the first BB. These are potentially redefined by // predicated instructions. - SmallSet Redefs; - InitPredRedefs(BBI1->BB, Redefs, TRI); + Redefs.init(TRI); + Redefs.addLiveIns(BBI1->BB); // Remove the duplicated instructions at the beginnings of both paths. MachineBasicBlock::iterator DI1 = BBI1->BB->begin(); @@ -1297,11 +1355,24 @@ bool IfConverter::IfConvertDiamond(BBInfo &BBI, IfcvtKind Kind, --NumDups1; } - UpdatePredRedefs(BBI1->BB->begin(), DI1, Redefs, TRI); + // Compute a set of registers which must not be killed by instructions in BB1: + // This is everything used+live in BB2 after the duplicated instructions. We + // can compute this set by simulating liveness backwards from the end of BB2. + DontKill.init(TRI); + for (MachineBasicBlock::reverse_iterator I = BBI2->BB->rbegin(), + E = MachineBasicBlock::reverse_iterator(DI2); I != E; ++I) { + DontKill.stepBackward(*I); + } + + for (MachineBasicBlock::const_iterator I = BBI1->BB->begin(), E = DI1; I != E; + ++I) { + SmallVector, 4> IgnoredClobbers; + Redefs.stepForward(*I, IgnoredClobbers); + } BBI.BB->splice(BBI.BB->end(), BBI1->BB, BBI1->BB->begin(), DI1); BBI2->BB->erase(BBI2->BB->begin(), DI2); - // Predicate the 'true' block after removing its branch. + // Remove branch from 'true' block and remove duplicated instructions. BBI1->NonPredSize -= TII->RemoveBranch(*BBI1->BB); DI1 = BBI1->BB->end(); for (unsigned i = 0; i != NumDups2; ) { @@ -1314,9 +1385,12 @@ bool IfConverter::IfConvertDiamond(BBInfo &BBI, IfcvtKind Kind, ++i; } BBI1->BB->erase(DI1, BBI1->BB->end()); - PredicateBlock(*BBI1, BBI1->BB->end(), *Cond1, Redefs); - // Predicate the 'false' block. + // Kill flags in the true block for registers living into the false block + // must be removed. + RemoveKills(BBI1->BB->begin(), BBI1->BB->end(), DontKill, *TRI); + + // Remove 'false' block branch and find the last instruction to predicate. BBI2->NonPredSize -= TII->RemoveBranch(*BBI2->BB); DI2 = BBI2->BB->end(); while (NumDups2 != 0) { @@ -1328,19 +1402,69 @@ bool IfConverter::IfConvertDiamond(BBInfo &BBI, IfcvtKind Kind, if (!DI2->isDebugValue()) --NumDups2; } - PredicateBlock(*BBI2, DI2, *Cond2, Redefs); + + // Remember which registers would later be defined by the false block. + // This allows us not to predicate instructions in the true block that would + // later be re-defined. That is, rather than + // subeq r0, r1, #1 + // addne r0, r1, #1 + // generate: + // sub r0, r1, #1 + // addne r0, r1, #1 + SmallSet RedefsByFalse; + SmallSet ExtUses; + if (TII->isProfitableToUnpredicate(*BBI1->BB, *BBI2->BB)) { + for (MachineBasicBlock::iterator FI = BBI2->BB->begin(); FI != DI2; ++FI) { + if (FI->isDebugValue()) + continue; + SmallVector Defs; + for (unsigned i = 0, e = FI->getNumOperands(); i != e; ++i) { + const MachineOperand &MO = FI->getOperand(i); + if (!MO.isReg()) + continue; + unsigned Reg = MO.getReg(); + if (!Reg) + continue; + if (MO.isDef()) { + Defs.push_back(Reg); + } else if (!RedefsByFalse.count(Reg)) { + // These are defined before ctrl flow reach the 'false' instructions. + // They cannot be modified by the 'true' instructions. + for (MCSubRegIterator SubRegs(Reg, TRI, /*IncludeSelf=*/true); + SubRegs.isValid(); ++SubRegs) + ExtUses.insert(*SubRegs); + } + } + + for (unsigned i = 0, e = Defs.size(); i != e; ++i) { + unsigned Reg = Defs[i]; + if (!ExtUses.count(Reg)) { + for (MCSubRegIterator SubRegs(Reg, TRI, /*IncludeSelf=*/true); + SubRegs.isValid(); ++SubRegs) + RedefsByFalse.insert(*SubRegs); + } + } + } + } + + // Predicate the 'true' block. + PredicateBlock(*BBI1, BBI1->BB->end(), *Cond1, &RedefsByFalse); + + // Predicate the 'false' block. + PredicateBlock(*BBI2, DI2, *Cond2); // Merge the true block into the entry of the diamond. - MergeBlocks(BBI, *BBI1, TailBB == 0); - MergeBlocks(BBI, *BBI2, TailBB == 0); + MergeBlocks(BBI, *BBI1, TailBB == nullptr); + MergeBlocks(BBI, *BBI2, TailBB == nullptr); // If the if-converted block falls through or unconditionally branches into // the tail block, and the tail block does not have other predecessors, then // fold the tail block in as well. Otherwise, unless it falls through to the // tail, add a unconditional branch to it. if (TailBB) { - BBInfo TailBBI = BBAnalysis[TailBB->getNumber()]; - bool CanMergeTail = !TailBBI.HasFallThrough; + BBInfo &TailBBI = BBAnalysis[TailBB->getNumber()]; + bool CanMergeTail = !TailBBI.HasFallThrough && + !TailBBI.BB->hasAddressTaken(); // There may still be a fall-through edge from BBI1 or BBI2 to TailBB; // check if there are any other predecessors besides those. unsigned NumPreds = TailBB->pred_size(); @@ -1376,55 +1500,88 @@ bool IfConverter::IfConvertDiamond(BBInfo &BBI, IfcvtKind Kind, return true; } +static bool MaySpeculate(const MachineInstr *MI, + SmallSet &LaterRedefs, + const TargetInstrInfo *TII) { + bool SawStore = true; + if (!MI->isSafeToMove(TII, nullptr, SawStore)) + return false; + + for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) { + const MachineOperand &MO = MI->getOperand(i); + if (!MO.isReg()) + continue; + unsigned Reg = MO.getReg(); + if (!Reg) + continue; + if (MO.isDef() && !LaterRedefs.count(Reg)) + return false; + } + + return true; +} + /// PredicateBlock - Predicate instructions from the start of the block to the /// specified end with the specified condition. void IfConverter::PredicateBlock(BBInfo &BBI, MachineBasicBlock::iterator E, SmallVectorImpl &Cond, - SmallSet &Redefs) { + SmallSet *LaterRedefs) { + bool AnyUnpred = false; + bool MaySpec = LaterRedefs != nullptr; for (MachineBasicBlock::iterator I = BBI.BB->begin(); I != E; ++I) { if (I->isDebugValue() || TII->isPredicated(I)) continue; + // It may be possible not to predicate an instruction if it's the 'true' + // side of a diamond and the 'false' side may re-define the instruction's + // defs. + if (MaySpec && MaySpeculate(I, *LaterRedefs, TII)) { + AnyUnpred = true; + continue; + } + // If any instruction is predicated, then every instruction after it must + // be predicated. + MaySpec = false; if (!TII->PredicateInstruction(I, Cond)) { #ifndef NDEBUG dbgs() << "Unable to predicate " << *I << "!\n"; #endif - llvm_unreachable(0); + llvm_unreachable(nullptr); } // If the predicated instruction now redefines a register as the result of // if-conversion, add an implicit kill. - UpdatePredRedefs(I, Redefs, TRI, true); + UpdatePredRedefs(I, Redefs); } - std::copy(Cond.begin(), Cond.end(), std::back_inserter(BBI.Predicate)); + BBI.Predicate.append(Cond.begin(), Cond.end()); BBI.IsAnalyzed = false; BBI.NonPredSize = 0; ++NumIfConvBBs; + if (AnyUnpred) + ++NumUnpred; } /// CopyAndPredicateBlock - Copy and predicate instructions from source BB to /// the destination block. Skip end of block branches if IgnoreBr is true. void IfConverter::CopyAndPredicateBlock(BBInfo &ToBBI, BBInfo &FromBBI, SmallVectorImpl &Cond, - SmallSet &Redefs, bool IgnoreBr) { MachineFunction &MF = *ToBBI.BB->getParent(); for (MachineBasicBlock::iterator I = FromBBI.BB->begin(), E = FromBBI.BB->end(); I != E; ++I) { - const MCInstrDesc &MCID = I->getDesc(); // Do not copy the end of the block branches. - if (IgnoreBr && MCID.isBranch()) + if (IgnoreBr && I->isBranch()) break; MachineInstr *MI = MF.CloneMachineInstr(I); ToBBI.BB->insert(ToBBI.BB->end(), MI); ToBBI.NonPredSize++; - unsigned ExtraPredCost = 0; - unsigned NumCycles = TII->getInstrLatency(InstrItins, &*I, &ExtraPredCost); + unsigned ExtraPredCost = TII->getPredicationCost(&*I); + unsigned NumCycles = SchedModel.computeInstrLatency(&*I, false); if (NumCycles > 1) ToBBI.ExtraCost += NumCycles-1; ToBBI.ExtraCost2 += ExtraPredCost; @@ -1434,20 +1591,24 @@ void IfConverter::CopyAndPredicateBlock(BBInfo &ToBBI, BBInfo &FromBBI, #ifndef NDEBUG dbgs() << "Unable to predicate " << *I << "!\n"; #endif - llvm_unreachable(0); + llvm_unreachable(nullptr); } } // If the predicated instruction now redefines a register as the result of // if-conversion, add an implicit kill. - UpdatePredRedefs(MI, Redefs, TRI, true); + UpdatePredRedefs(MI, Redefs); + + // Some kill flags may not be correct anymore. + if (!DontKill.empty()) + RemoveKills(*MI, DontKill); } if (!IgnoreBr) { std::vector Succs(FromBBI.BB->succ_begin(), FromBBI.BB->succ_end()); MachineBasicBlock *NBB = getNextBlock(FromBBI.BB); - MachineBasicBlock *FallThrough = FromBBI.HasFallThrough ? NBB : NULL; + MachineBasicBlock *FallThrough = FromBBI.HasFallThrough ? NBB : nullptr; for (unsigned i = 0, e = Succs.size(); i != e; ++i) { MachineBasicBlock *Succ = Succs[i]; @@ -1458,9 +1619,8 @@ void IfConverter::CopyAndPredicateBlock(BBInfo &ToBBI, BBInfo &FromBBI, } } - std::copy(FromBBI.Predicate.begin(), FromBBI.Predicate.end(), - std::back_inserter(ToBBI.Predicate)); - std::copy(Cond.begin(), Cond.end(), std::back_inserter(ToBBI.Predicate)); + ToBBI.Predicate.append(FromBBI.Predicate.begin(), FromBBI.Predicate.end()); + ToBBI.Predicate.append(Cond.begin(), Cond.end()); ToBBI.ClobbersPred |= FromBBI.ClobbersPred; ToBBI.IsAnalyzed = false; @@ -1474,13 +1634,16 @@ void IfConverter::CopyAndPredicateBlock(BBInfo &ToBBI, BBInfo &FromBBI, /// i.e., when FromBBI's branch is being moved, add those successor edges to /// ToBBI. void IfConverter::MergeBlocks(BBInfo &ToBBI, BBInfo &FromBBI, bool AddEdges) { + assert(!FromBBI.BB->hasAddressTaken() && + "Removing a BB whose address is taken!"); + ToBBI.BB->splice(ToBBI.BB->end(), FromBBI.BB, FromBBI.BB->begin(), FromBBI.BB->end()); std::vector Succs(FromBBI.BB->succ_begin(), FromBBI.BB->succ_end()); MachineBasicBlock *NBB = getNextBlock(FromBBI.BB); - MachineBasicBlock *FallThrough = FromBBI.HasFallThrough ? NBB : NULL; + MachineBasicBlock *FallThrough = FromBBI.HasFallThrough ? NBB : nullptr; for (unsigned i = 0, e = Succs.size(); i != e; ++i) { MachineBasicBlock *Succ = Succs[i]; @@ -1488,7 +1651,7 @@ void IfConverter::MergeBlocks(BBInfo &ToBBI, BBInfo &FromBBI, bool AddEdges) { if (Succ == FallThrough) continue; FromBBI.BB->removeSuccessor(Succ); - if (AddEdges) + if (AddEdges && !ToBBI.BB->isSuccessor(Succ)) ToBBI.BB->addSuccessor(Succ); } @@ -1496,8 +1659,7 @@ void IfConverter::MergeBlocks(BBInfo &ToBBI, BBInfo &FromBBI, bool AddEdges) { if (NBB && !FromBBI.BB->isSuccessor(NBB)) FromBBI.BB->addSuccessor(NBB); - std::copy(FromBBI.Predicate.begin(), FromBBI.Predicate.end(), - std::back_inserter(ToBBI.Predicate)); + ToBBI.Predicate.append(FromBBI.Predicate.begin(), FromBBI.Predicate.end()); FromBBI.Predicate.clear(); ToBBI.NonPredSize += FromBBI.NonPredSize;