X-Git-Url: http://plrg.eecs.uci.edu/git/?p=oota-llvm.git;a=blobdiff_plain;f=lib%2FTransforms%2FScalar%2FLoopUnswitch.cpp;h=e21d41ac0a37b0cc825d6108a0b7f646a647cd0f;hp=842802e2175a075785df3d27cc8fcc2015d19706;hb=cd52a7a381a73c53ec4ef517ad87f19808cb1a28;hpb=aad9c3f17a73b3104f4a3673a2dc511a4878e20e diff --git a/lib/Transforms/Scalar/LoopUnswitch.cpp b/lib/Transforms/Scalar/LoopUnswitch.cpp index 842802e2175..e21d41ac0a3 100644 --- a/lib/Transforms/Scalar/LoopUnswitch.cpp +++ b/lib/Transforms/Scalar/LoopUnswitch.cpp @@ -26,32 +26,37 @@ // //===----------------------------------------------------------------------===// -#define DEBUG_TYPE "loop-unswitch" #include "llvm/Transforms/Scalar.h" -#include "llvm/Constants.h" -#include "llvm/DerivedTypes.h" -#include "llvm/Function.h" -#include "llvm/Instructions.h" +#include "llvm/ADT/STLExtras.h" +#include "llvm/ADT/SmallPtrSet.h" +#include "llvm/ADT/Statistic.h" +#include "llvm/Analysis/AssumptionCache.h" #include "llvm/Analysis/CodeMetrics.h" #include "llvm/Analysis/InstructionSimplify.h" #include "llvm/Analysis/LoopInfo.h" #include "llvm/Analysis/LoopPass.h" -#include "llvm/Analysis/Dominators.h" #include "llvm/Analysis/ScalarEvolution.h" -#include "llvm/Transforms/Utils/Cloning.h" -#include "llvm/Transforms/Utils/Local.h" -#include "llvm/Transforms/Utils/BasicBlockUtils.h" -#include "llvm/ADT/Statistic.h" -#include "llvm/ADT/SmallPtrSet.h" -#include "llvm/ADT/STLExtras.h" +#include "llvm/Analysis/TargetTransformInfo.h" +#include "llvm/IR/Constants.h" +#include "llvm/IR/DerivedTypes.h" +#include "llvm/IR/Dominators.h" +#include "llvm/IR/Function.h" +#include "llvm/IR/Instructions.h" +#include "llvm/IR/Module.h" +#include "llvm/IR/MDBuilder.h" #include "llvm/Support/CommandLine.h" #include "llvm/Support/Debug.h" #include "llvm/Support/raw_ostream.h" +#include "llvm/Transforms/Utils/BasicBlockUtils.h" +#include "llvm/Transforms/Utils/Cloning.h" +#include "llvm/Transforms/Utils/Local.h" #include #include #include using namespace llvm; +#define DEBUG_TYPE "loop-unswitch" + STATISTIC(NumBranches, "Number of branches unswitched"); STATISTIC(NumSwitches, "Number of switches unswitched"); STATISTIC(NumSelects , "Number of selects unswitched"); @@ -64,73 +69,75 @@ STATISTIC(TotalInsts, "Total number of instructions analyzed"); static cl::opt Threshold("loop-unswitch-threshold", cl::desc("Max loop size to unswitch"), cl::init(100), cl::Hidden); - + namespace { - + class LUAnalysisCache { typedef DenseMap > UnswitchedValsMap; - + typedef UnswitchedValsMap::iterator UnswitchedValsIt; - + struct LoopProperties { unsigned CanBeUnswitchedCount; unsigned SizeEstimation; UnswitchedValsMap UnswitchedVals; }; - - // Here we use std::map instead of DenseMap, since we need to keep valid + + // Here we use std::map instead of DenseMap, since we need to keep valid // LoopProperties pointer for current loop for better performance. typedef std::map LoopPropsMap; typedef LoopPropsMap::iterator LoopPropsMapIt; - + LoopPropsMap LoopsProperties; - UnswitchedValsMap* CurLoopInstructions; - LoopProperties* CurrentLoopProperties; - + UnswitchedValsMap *CurLoopInstructions; + LoopProperties *CurrentLoopProperties; + // Max size of code we can produce on remained iterations. unsigned MaxSize; - + public: - + LUAnalysisCache() : - CurLoopInstructions(NULL), CurrentLoopProperties(NULL), + CurLoopInstructions(nullptr), CurrentLoopProperties(nullptr), MaxSize(Threshold) {} - + // Analyze loop. Check its size, calculate is it possible to unswitch // it. Returns true if we can unswitch this loop. - bool countLoop(const Loop* L); - + bool countLoop(const Loop *L, const TargetTransformInfo &TTI, + AssumptionCache *AC); + // Clean all data related to given loop. - void forgetLoop(const Loop* L); - + void forgetLoop(const Loop *L); + // Mark case value as unswitched. // Since SI instruction can be partly unswitched, in order to avoid // extra unswitching in cloned loops keep track all unswitched values. - void setUnswitched(const SwitchInst* SI, const Value* V); - + void setUnswitched(const SwitchInst *SI, const Value *V); + // Check was this case value unswitched before or not. - bool isUnswitched(const SwitchInst* SI, const Value* V); - + bool isUnswitched(const SwitchInst *SI, const Value *V); + // Clone all loop-unswitch related loop properties. // Redistribute unswitching quotas. // Note, that new loop data is stored inside the VMap. - void cloneData(const Loop* NewLoop, const Loop* OldLoop, - const ValueToValueMapTy& VMap); + void cloneData(const Loop *NewLoop, const Loop *OldLoop, + const ValueToValueMapTy &VMap); }; - + class LoopUnswitch : public LoopPass { LoopInfo *LI; // Loop information LPPassManager *LPM; + AssumptionCache *AC; // LoopProcessWorklist - Used to check if second loop needs processing // after RewriteLoopBodyWithConditionConstant rewrites first loop. std::vector LoopProcessWorklist; LUAnalysisCache BranchesInfo; - + bool OptimizeForSize; bool redoLoop; @@ -138,9 +145,9 @@ namespace { DominatorTree *DT; BasicBlock *loopHeader; BasicBlock *loopPreheader; - + // LoopBlocks contains all of the basic blocks of the loop, including the - // preheader of the loop, the body of the loop, and the exit blocks of the + // preheader of the loop, the body of the loop, and the exit blocks of the // loop, in that order. std::vector LoopBlocks; // NewBlocks contained cloned copy of basic blocks from LoopBlocks. @@ -148,182 +155,182 @@ namespace { public: static char ID; // Pass ID, replacement for typeid - explicit LoopUnswitch(bool Os = false) : - LoopPass(ID), OptimizeForSize(Os), redoLoop(false), - currentLoop(NULL), DT(NULL), loopHeader(NULL), - loopPreheader(NULL) { + explicit LoopUnswitch(bool Os = false) : + LoopPass(ID), OptimizeForSize(Os), redoLoop(false), + currentLoop(nullptr), DT(nullptr), loopHeader(nullptr), + loopPreheader(nullptr) { initializeLoopUnswitchPass(*PassRegistry::getPassRegistry()); } - bool runOnLoop(Loop *L, LPPassManager &LPM); + bool runOnLoop(Loop *L, LPPassManager &LPM) override; bool processCurrentLoop(); /// This transformation requires natural loop information & requires that /// loop preheaders be inserted into the CFG. /// - virtual void getAnalysisUsage(AnalysisUsage &AU) const { + void getAnalysisUsage(AnalysisUsage &AU) const override { + AU.addRequired(); AU.addRequiredID(LoopSimplifyID); AU.addPreservedID(LoopSimplifyID); - AU.addRequired(); - AU.addPreserved(); + AU.addRequired(); + AU.addPreserved(); AU.addRequiredID(LCSSAID); AU.addPreservedID(LCSSAID); - AU.addPreserved(); + AU.addPreserved(); AU.addPreserved(); + AU.addRequired(); } private: - virtual void releaseMemory() { + void releaseMemory() override { BranchesInfo.forgetLoop(currentLoop); } - /// RemoveLoopFromWorklist - If the specified loop is on the loop worklist, - /// remove it. - void RemoveLoopFromWorklist(Loop *L) { - std::vector::iterator I = std::find(LoopProcessWorklist.begin(), - LoopProcessWorklist.end(), L); - if (I != LoopProcessWorklist.end()) - LoopProcessWorklist.erase(I); - } - void initLoopData() { loopHeader = currentLoop->getHeader(); loopPreheader = currentLoop->getLoopPreheader(); } - - /// HasIndirectBrsInPreds - Returns true if there are predecessors, that are - /// terminated with indirect branch instruction. - bool HasIndirectBrsInPreds(const SmallVectorImpl &ExitBlocks); /// Split all of the edges from inside the loop to their exit blocks. /// Update the appropriate Phi nodes as we do so. - void SplitExitEdges(Loop *L, const SmallVector &ExitBlocks); + void SplitExitEdges(Loop *L, const SmallVectorImpl &ExitBlocks); - bool UnswitchIfProfitable(Value *LoopCond, Constant *Val); + bool UnswitchIfProfitable(Value *LoopCond, Constant *Val, + TerminatorInst *TI = nullptr); void UnswitchTrivialCondition(Loop *L, Value *Cond, Constant *Val, - BasicBlock *ExitBlock); - bool UnswitchNontrivialCondition(Value *LIC, Constant *OnVal, Loop *L); + BasicBlock *ExitBlock, TerminatorInst *TI); + void UnswitchNontrivialCondition(Value *LIC, Constant *OnVal, Loop *L, + TerminatorInst *TI); void RewriteLoopBodyWithConditionConstant(Loop *L, Value *LIC, Constant *Val, bool isEqual); void EmitPreheaderBranchOnCondition(Value *LIC, Constant *Val, - BasicBlock *TrueDest, + BasicBlock *TrueDest, BasicBlock *FalseDest, - Instruction *InsertPt); + Instruction *InsertPt, + TerminatorInst *TI); void SimplifyCode(std::vector &Worklist, Loop *L); - void RemoveBlockIfDead(BasicBlock *BB, - std::vector &Worklist, Loop *l); - void RemoveLoopFromHierarchy(Loop *L); - bool IsTrivialUnswitchCondition(Value *Cond, Constant **Val = 0, - BasicBlock **LoopExit = 0); + bool IsTrivialUnswitchCondition(Value *Cond, Constant **Val = nullptr, + BasicBlock **LoopExit = nullptr); }; } // Analyze loop. Check its size, calculate is it possible to unswitch // it. Returns true if we can unswitch this loop. -bool LUAnalysisCache::countLoop(const Loop* L) { - - std::pair InsertRes = +bool LUAnalysisCache::countLoop(const Loop *L, const TargetTransformInfo &TTI, + AssumptionCache *AC) { + + LoopPropsMapIt PropsIt; + bool Inserted; + std::tie(PropsIt, Inserted) = LoopsProperties.insert(std::make_pair(L, LoopProperties())); - - LoopProperties& Props = InsertRes.first->second; - - if (InsertRes.second) { + + LoopProperties &Props = PropsIt->second; + + if (Inserted) { // New loop. // Limit the number of instructions to avoid causing significant code // expansion, and the number of basic blocks, to avoid loops with // large numbers of branches which cause loop unswitching to go crazy. // This is a very ad-hoc heuristic. - + + SmallPtrSet EphValues; + CodeMetrics::collectEphemeralValues(L, AC, EphValues); + // FIXME: This is overly conservative because it does not take into // consideration code simplification opportunities and code that can // be shared by the resultant unswitched loops. CodeMetrics Metrics; - for (Loop::block_iterator I = L->block_begin(), - E = L->block_end(); + for (Loop::block_iterator I = L->block_begin(), E = L->block_end(); I != E; ++I) - Metrics.analyzeBasicBlock(*I); + Metrics.analyzeBasicBlock(*I, TTI, EphValues); Props.SizeEstimation = std::min(Metrics.NumInsts, Metrics.NumBlocks * 5); Props.CanBeUnswitchedCount = MaxSize / (Props.SizeEstimation); MaxSize -= Props.SizeEstimation * Props.CanBeUnswitchedCount; - } - + + if (Metrics.notDuplicatable) { + DEBUG(dbgs() << "NOT unswitching loop %" + << L->getHeader()->getName() << ", contents cannot be " + << "duplicated!\n"); + return false; + } + } + if (!Props.CanBeUnswitchedCount) { DEBUG(dbgs() << "NOT unswitching loop %" - << L->getHeader()->getName() << ", cost too high: " - << L->getBlocks().size() << "\n"); - + << L->getHeader()->getName() << ", cost too high: " + << L->getBlocks().size() << "\n"); return false; } - + // Be careful. This links are good only before new loop addition. CurrentLoopProperties = &Props; CurLoopInstructions = &Props.UnswitchedVals; - + return true; } // Clean all data related to given loop. -void LUAnalysisCache::forgetLoop(const Loop* L) { - +void LUAnalysisCache::forgetLoop(const Loop *L) { + LoopPropsMapIt LIt = LoopsProperties.find(L); if (LIt != LoopsProperties.end()) { - LoopProperties& Props = LIt->second; + LoopProperties &Props = LIt->second; MaxSize += Props.CanBeUnswitchedCount * Props.SizeEstimation; LoopsProperties.erase(LIt); } - - CurrentLoopProperties = NULL; - CurLoopInstructions = NULL; + + CurrentLoopProperties = nullptr; + CurLoopInstructions = nullptr; } // Mark case value as unswitched. // Since SI instruction can be partly unswitched, in order to avoid // extra unswitching in cloned loops keep track all unswitched values. -void LUAnalysisCache::setUnswitched(const SwitchInst* SI, const Value* V) { +void LUAnalysisCache::setUnswitched(const SwitchInst *SI, const Value *V) { (*CurLoopInstructions)[SI].insert(V); } // Check was this case value unswitched before or not. -bool LUAnalysisCache::isUnswitched(const SwitchInst* SI, const Value* V) { - return (*CurLoopInstructions)[SI].count(V); +bool LUAnalysisCache::isUnswitched(const SwitchInst *SI, const Value *V) { + return (*CurLoopInstructions)[SI].count(V); } // Clone all loop-unswitch related loop properties. // Redistribute unswitching quotas. // Note, that new loop data is stored inside the VMap. -void LUAnalysisCache::cloneData(const Loop* NewLoop, const Loop* OldLoop, - const ValueToValueMapTy& VMap) { - - LoopProperties& NewLoopProps = LoopsProperties[NewLoop]; - LoopProperties& OldLoopProps = *CurrentLoopProperties; - UnswitchedValsMap& Insts = OldLoopProps.UnswitchedVals; - +void LUAnalysisCache::cloneData(const Loop *NewLoop, const Loop *OldLoop, + const ValueToValueMapTy &VMap) { + + LoopProperties &NewLoopProps = LoopsProperties[NewLoop]; + LoopProperties &OldLoopProps = *CurrentLoopProperties; + UnswitchedValsMap &Insts = OldLoopProps.UnswitchedVals; + // Reallocate "can-be-unswitched quota" --OldLoopProps.CanBeUnswitchedCount; unsigned Quota = OldLoopProps.CanBeUnswitchedCount; NewLoopProps.CanBeUnswitchedCount = Quota / 2; OldLoopProps.CanBeUnswitchedCount = Quota - Quota / 2; - + NewLoopProps.SizeEstimation = OldLoopProps.SizeEstimation; - + // Clone unswitched values info: // for new loop switches we clone info about values that was // already unswitched and has redundant successors. for (UnswitchedValsIt I = Insts.begin(); I != Insts.end(); ++I) { - const SwitchInst* OldInst = I->first; - Value* NewI = VMap.lookup(OldInst); - const SwitchInst* NewInst = cast_or_null(NewI); + const SwitchInst *OldInst = I->first; + Value *NewI = VMap.lookup(OldInst); + const SwitchInst *NewInst = cast_or_null(NewI); assert(NewInst && "All instructions that are in SrcBB must be in VMap."); - + NewLoopProps.UnswitchedVals[NewInst] = OldLoopProps.UnswitchedVals[OldInst]; } } @@ -331,30 +338,32 @@ void LUAnalysisCache::cloneData(const Loop* NewLoop, const Loop* OldLoop, char LoopUnswitch::ID = 0; INITIALIZE_PASS_BEGIN(LoopUnswitch, "loop-unswitch", "Unswitch loops", false, false) +INITIALIZE_PASS_DEPENDENCY(TargetTransformInfoWrapperPass) +INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker) INITIALIZE_PASS_DEPENDENCY(LoopSimplify) -INITIALIZE_PASS_DEPENDENCY(LoopInfo) +INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass) INITIALIZE_PASS_DEPENDENCY(LCSSA) INITIALIZE_PASS_END(LoopUnswitch, "loop-unswitch", "Unswitch loops", false, false) -Pass *llvm::createLoopUnswitchPass(bool Os) { - return new LoopUnswitch(Os); +Pass *llvm::createLoopUnswitchPass(bool Os) { + return new LoopUnswitch(Os); } /// FindLIVLoopCondition - Cond is a condition that occurs in L. If it is /// invariant in the loop, or has an invariant piece, return the invariant. /// Otherwise, return null. static Value *FindLIVLoopCondition(Value *Cond, Loop *L, bool &Changed) { - + // We started analyze new instruction, increment scanned instructions counter. ++TotalInsts; - + // We can never unswitch on vector conditions. if (Cond->getType()->isVectorTy()) - return 0; + return nullptr; // Constants should be folded, not unswitched on! - if (isa(Cond)) return 0; + if (isa(Cond)) return nullptr; // TODO: Handle: br (VARIANT|INVARIANT). @@ -373,14 +382,21 @@ static Value *FindLIVLoopCondition(Value *Cond, Loop *L, bool &Changed) { if (Value *RHS = FindLIVLoopCondition(BO->getOperand(1), L, Changed)) return RHS; } - - return 0; + + return nullptr; } bool LoopUnswitch::runOnLoop(Loop *L, LPPassManager &LPM_Ref) { - LI = &getAnalysis(); + if (skipOptnoneFunction(L)) + return false; + + AC = &getAnalysis().getAssumptionCache( + *L->getHeader()->getParent()); + LI = &getAnalysis().getLoopInfo(); LPM = &LPM_Ref; - DT = getAnalysisIfAvailable(); + DominatorTreeWrapperPass *DTWP = + getAnalysisIfAvailable(); + DT = DTWP ? &DTWP->getDomTree() : nullptr; currentLoop = L; Function *F = currentLoop->getHeader()->getParent(); bool Changed = false; @@ -393,33 +409,44 @@ bool LoopUnswitch::runOnLoop(Loop *L, LPPassManager &LPM_Ref) { if (Changed) { // FIXME: Reconstruct dom info, because it is not preserved properly. if (DT) - DT->runOnFunction(*F); + DT->recalculate(*F); } return Changed; } -/// processCurrentLoop - Do actual work and unswitch loop if possible +/// processCurrentLoop - Do actual work and unswitch loop if possible /// and profitable. bool LoopUnswitch::processCurrentLoop() { bool Changed = false; initLoopData(); - + // If LoopSimplify was unable to form a preheader, don't do any unswitching. if (!loopPreheader) return false; - + + // Loops with indirectbr cannot be cloned. + if (!currentLoop->isSafeToClone()) + return false; + + // Without dedicated exits, splitting the exit edge may fail. + if (!currentLoop->hasDedicatedExits()) + return false; + LLVMContext &Context = loopHeader->getContext(); - + // Probably we reach the quota of branches for this loop. If so // stop unswitching. - if (!BranchesInfo.countLoop(currentLoop)) + if (!BranchesInfo.countLoop( + currentLoop, getAnalysis().getTTI( + *currentLoop->getHeader()->getParent()), + AC)) return false; // Loop over all of the basic blocks in the loop. If we find an interior // block that is branching on a loop-invariant condition, we can unswitch this // loop. - for (Loop::block_iterator I = currentLoop->block_begin(), + for (Loop::block_iterator I = currentLoop->block_begin(), E = currentLoop->block_end(); I != E; ++I) { TerminatorInst *TI = (*I)->getTerminator(); if (BranchInst *BI = dyn_cast(TI)) { @@ -428,36 +455,36 @@ bool LoopUnswitch::processCurrentLoop() { if (BI->isConditional()) { // See if this, or some part of it, is loop invariant. If so, we can // unswitch on it if we desire. - Value *LoopCond = FindLIVLoopCondition(BI->getCondition(), + Value *LoopCond = FindLIVLoopCondition(BI->getCondition(), currentLoop, Changed); - if (LoopCond && UnswitchIfProfitable(LoopCond, - ConstantInt::getTrue(Context))) { + if (LoopCond && + UnswitchIfProfitable(LoopCond, ConstantInt::getTrue(Context), TI)) { ++NumBranches; return true; } - } + } } else if (SwitchInst *SI = dyn_cast(TI)) { - Value *LoopCond = FindLIVLoopCondition(SI->getCondition(), + Value *LoopCond = FindLIVLoopCondition(SI->getCondition(), currentLoop, Changed); - unsigned NumCases = SI->getNumCases(); + unsigned NumCases = SI->getNumCases(); if (LoopCond && NumCases) { // Find a value to unswitch on: // FIXME: this should chose the most expensive case! // FIXME: scan for a case with a non-critical edge? - Constant *UnswitchVal = NULL; - + Constant *UnswitchVal = nullptr; + // Do not process same value again and again. // At this point we have some cases already unswitched and // some not yet unswitched. Let's find the first not yet unswitched one. for (SwitchInst::CaseIt i = SI->case_begin(), e = SI->case_end(); i != e; ++i) { - Constant* UnswitchValCandidate = i.getCaseValue(); + Constant *UnswitchValCandidate = i.getCaseValue(); if (!BranchesInfo.isUnswitched(SI, UnswitchValCandidate)) { UnswitchVal = UnswitchValCandidate; break; } } - + if (!UnswitchVal) continue; @@ -467,14 +494,14 @@ bool LoopUnswitch::processCurrentLoop() { } } } - + // Scan the instructions to check for unswitchable values. - for (BasicBlock::iterator BBI = (*I)->begin(), E = (*I)->end(); + for (BasicBlock::iterator BBI = (*I)->begin(), E = (*I)->end(); BBI != E; ++BBI) if (SelectInst *SI = dyn_cast(BBI)) { - Value *LoopCond = FindLIVLoopCondition(SI->getCondition(), + Value *LoopCond = FindLIVLoopCondition(SI->getCondition(), currentLoop, Changed); - if (LoopCond && UnswitchIfProfitable(LoopCond, + if (LoopCond && UnswitchIfProfitable(LoopCond, ConstantInt::getTrue(Context))) { ++NumSelects; return true; @@ -497,14 +524,15 @@ static bool isTrivialLoopExitBlockHelper(Loop *L, BasicBlock *BB, // Already visited. Without more analysis, this could indicate an infinite // loop. return false; - } else if (!L->contains(BB)) { + } + if (!L->contains(BB)) { // Otherwise, this is a loop exit, this is fine so long as this is the // first exit. - if (ExitBB != 0) return false; + if (ExitBB) return false; ExitBB = BB; return true; } - + // Otherwise, this is an unvisited intra-loop node. Check all successors. for (succ_iterator SI = succ_begin(BB), E = succ_end(BB); SI != E; ++SI) { // Check to see if the successor is a trivial loop exit. @@ -517,20 +545,20 @@ static bool isTrivialLoopExitBlockHelper(Loop *L, BasicBlock *BB, for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) if (I->mayHaveSideEffects()) return false; - + return true; } /// isTrivialLoopExitBlock - Return true if the specified block unconditionally -/// leads to an exit from the specified loop, and has no side-effects in the +/// leads to an exit from the specified loop, and has no side-effects in the /// process. If so, return the block that is exited to, otherwise return null. static BasicBlock *isTrivialLoopExitBlock(Loop *L, BasicBlock *BB) { std::set Visited; Visited.insert(L->getHeader()); // Branches to header make infinite loops. - BasicBlock *ExitBB = 0; + BasicBlock *ExitBB = nullptr; if (isTrivialLoopExitBlockHelper(L, BB, ExitBB, Visited)) return ExitBB; - return 0; + return nullptr; } /// IsTrivialUnswitchCondition - Check to see if this unswitch condition is @@ -550,42 +578,42 @@ bool LoopUnswitch::IsTrivialUnswitchCondition(Value *Cond, Constant **Val, BasicBlock *Header = currentLoop->getHeader(); TerminatorInst *HeaderTerm = Header->getTerminator(); LLVMContext &Context = Header->getContext(); - - BasicBlock *LoopExitBB = 0; + + BasicBlock *LoopExitBB = nullptr; if (BranchInst *BI = dyn_cast(HeaderTerm)) { // If the header block doesn't end with a conditional branch on Cond, we // can't handle it. if (!BI->isConditional() || BI->getCondition() != Cond) return false; - - // Check to see if a successor of the branch is guaranteed to - // exit through a unique exit block without having any + + // Check to see if a successor of the branch is guaranteed to + // exit through a unique exit block without having any // side-effects. If so, determine the value of Cond that causes it to do // this. - if ((LoopExitBB = isTrivialLoopExitBlock(currentLoop, + if ((LoopExitBB = isTrivialLoopExitBlock(currentLoop, BI->getSuccessor(0)))) { if (Val) *Val = ConstantInt::getTrue(Context); - } else if ((LoopExitBB = isTrivialLoopExitBlock(currentLoop, + } else if ((LoopExitBB = isTrivialLoopExitBlock(currentLoop, BI->getSuccessor(1)))) { if (Val) *Val = ConstantInt::getFalse(Context); } } else if (SwitchInst *SI = dyn_cast(HeaderTerm)) { // If this isn't a switch on Cond, we can't handle it. if (SI->getCondition() != Cond) return false; - + // Check to see if a successor of the switch is guaranteed to go to the - // latch block or exit through a one exit block without having any + // latch block or exit through a one exit block without having any // side-effects. If so, determine the value of Cond that causes it to do - // this. + // this. // Note that we can't trivially unswitch on the default case or // on already unswitched cases. for (SwitchInst::CaseIt i = SI->case_begin(), e = SI->case_end(); i != e; ++i) { - BasicBlock* LoopExitCandidate; - if ((LoopExitCandidate = isTrivialLoopExitBlock(currentLoop, + BasicBlock *LoopExitCandidate; + if ((LoopExitCandidate = isTrivialLoopExitBlock(currentLoop, i.getCaseSuccessor()))) { // Okay, we found a trivial case, remember the value that is trivial. - ConstantInt* CaseVal = i.getCaseValue(); + ConstantInt *CaseVal = i.getCaseValue(); // Check that it was not unswitched before, since already unswitched // trivial vals are looks trivial too. @@ -602,9 +630,9 @@ bool LoopUnswitch::IsTrivialUnswitchCondition(Value *Cond, Constant **Val, // contains phi nodes, this isn't trivial. if (!LoopExitBB || isa(LoopExitBB->begin())) return false; // Can't handle this. - + if (LoopExit) *LoopExit = LoopExitBB; - + // We already know that nothing uses any scalar values defined inside of this // loop. As such, we just have to check to see if this loop will execute any // side-effecting instructions (e.g. stores, calls, volatile loads) in the @@ -619,26 +647,27 @@ bool LoopUnswitch::IsTrivialUnswitchCondition(Value *Cond, Constant **Val, /// UnswitchIfProfitable - We have found that we can unswitch currentLoop when /// LoopCond == Val to simplify the loop. If we decide that this is profitable, /// unswitch the loop, reprocess the pieces, then return true. -bool LoopUnswitch::UnswitchIfProfitable(Value *LoopCond, Constant *Val) { - +bool LoopUnswitch::UnswitchIfProfitable(Value *LoopCond, Constant *Val, + TerminatorInst *TI) { Function *F = loopHeader->getParent(); + Constant *CondVal = nullptr; + BasicBlock *ExitBlock = nullptr; - Constant *CondVal = 0; - BasicBlock *ExitBlock = 0; if (IsTrivialUnswitchCondition(LoopCond, &CondVal, &ExitBlock)) { // If the condition is trivial, always unswitch. There is no code growth // for this case. - UnswitchTrivialCondition(currentLoop, LoopCond, CondVal, ExitBlock); + UnswitchTrivialCondition(currentLoop, LoopCond, CondVal, ExitBlock, TI); return true; } // Check to see if it would be profitable to unswitch current loop. // Do not do non-trivial unswitch while optimizing for size. - if (OptimizeForSize || F->hasFnAttr(Attribute::OptimizeForSize)) + if (OptimizeForSize || F->hasFnAttribute(Attribute::OptimizeForSize)) return false; - return UnswitchNontrivialCondition(LoopCond, Val, currentLoop); + UnswitchNontrivialCondition(LoopCond, Val, currentLoop, TI); + return true; } /// CloneLoop - Recursively clone the specified loop and all of its children, @@ -652,7 +681,7 @@ static Loop *CloneLoop(Loop *L, Loop *PL, ValueToValueMapTy &VM, for (Loop::block_iterator I = L->block_begin(), E = L->block_end(); I != E; ++I) if (LI->getLoopFor(*I) == L) - New->addBasicBlockToLoop(cast(VM[*I]), LI->getBase()); + New->addBasicBlockToLoop(cast(VM[*I]), *LI); // Add all of the subloops to the new loop. for (Loop::iterator I = L->begin(), E = L->end(); I != E; ++I) @@ -661,71 +690,113 @@ static Loop *CloneLoop(Loop *L, Loop *PL, ValueToValueMapTy &VM, return New; } +static void copyMetadata(Instruction *DstInst, const Instruction *SrcInst, + bool Swapped) { + if (!SrcInst || !SrcInst->hasMetadata()) + return; + + SmallVector, 4> MDs; + SrcInst->getAllMetadata(MDs); + for (auto &MD : MDs) { + switch (MD.first) { + default: + break; + case LLVMContext::MD_prof: + if (Swapped && MD.second->getNumOperands() == 3 && + isa(MD.second->getOperand(0))) { + MDString *MDName = cast(MD.second->getOperand(0)); + if (MDName->getString() == "branch_weights") { + auto *ValT = cast_or_null( + MD.second->getOperand(1))->getValue(); + auto *ValF = cast_or_null( + MD.second->getOperand(2))->getValue(); + assert(ValT && ValF && "Invalid Operands of branch_weights"); + auto NewMD = + MDBuilder(DstInst->getParent()->getContext()) + .createBranchWeights(cast(ValF)->getZExtValue(), + cast(ValT)->getZExtValue()); + MD.second = NewMD; + } + } + // fallthrough. + case LLVMContext::MD_dbg: + DstInst->setMetadata(MD.first, MD.second); + } + } +} + /// EmitPreheaderBranchOnCondition - Emit a conditional branch on two values /// if LIC == Val, branch to TrueDst, otherwise branch to FalseDest. Insert the /// code immediately before InsertPt. void LoopUnswitch::EmitPreheaderBranchOnCondition(Value *LIC, Constant *Val, BasicBlock *TrueDest, BasicBlock *FalseDest, - Instruction *InsertPt) { + Instruction *InsertPt, + TerminatorInst *TI) { // Insert a conditional branch on LIC to the two preheaders. The original // code is the true version and the new code is the false version. Value *BranchVal = LIC; + bool Swapped = false; if (!isa(Val) || Val->getType() != Type::getInt1Ty(LIC->getContext())) BranchVal = new ICmpInst(InsertPt, ICmpInst::ICMP_EQ, LIC, Val); - else if (Val != ConstantInt::getTrue(Val->getContext())) + else if (Val != ConstantInt::getTrue(Val->getContext())) { // We want to enter the new loop when the condition is true. std::swap(TrueDest, FalseDest); + Swapped = true; + } // Insert the new branch. BranchInst *BI = BranchInst::Create(TrueDest, FalseDest, BranchVal, InsertPt); + copyMetadata(BI, TI, Swapped); // If either edge is critical, split it. This helps preserve LoopSimplify // form for enclosing loops. - SplitCriticalEdge(BI, 0, this); - SplitCriticalEdge(BI, 1, this); + auto Options = CriticalEdgeSplittingOptions(DT, LI).setPreserveLCSSA(); + SplitCriticalEdge(BI, 0, Options); + SplitCriticalEdge(BI, 1, Options); } /// UnswitchTrivialCondition - Given a loop that has a trivial unswitchable /// condition in it (a cond branch from its header block to its latch block, -/// where the path through the loop that doesn't execute its body has no +/// where the path through the loop that doesn't execute its body has no /// side-effects), unswitch it. This doesn't involve any code duplication, just /// moving the conditional branch outside of the loop and updating loop info. -void LoopUnswitch::UnswitchTrivialCondition(Loop *L, Value *Cond, - Constant *Val, - BasicBlock *ExitBlock) { +void LoopUnswitch::UnswitchTrivialCondition(Loop *L, Value *Cond, Constant *Val, + BasicBlock *ExitBlock, + TerminatorInst *TI) { DEBUG(dbgs() << "loop-unswitch: Trivial-Unswitch loop %" - << loopHeader->getName() << " [" << L->getBlocks().size() - << " blocks] in Function " << L->getHeader()->getParent()->getName() - << " on cond: " << *Val << " == " << *Cond << "\n"); - + << loopHeader->getName() << " [" << L->getBlocks().size() + << " blocks] in Function " + << L->getHeader()->getParent()->getName() << " on cond: " << *Val + << " == " << *Cond << "\n"); + // First step, split the preheader, so that we know that there is a safe place // to insert the conditional branch. We will change loopPreheader to have a // conditional branch on Cond. - BasicBlock *NewPH = SplitEdge(loopPreheader, loopHeader, this); + BasicBlock *NewPH = SplitEdge(loopPreheader, loopHeader, DT, LI); // Now that we have a place to insert the conditional branch, create a place // to branch to: this is the exit block out of the loop that we should // short-circuit to. - + // Split this block now, so that the loop maintains its exit block, and so // that the jump from the preheader can execute the contents of the exit block // without actually branching to it (the exit block should be dominated by the // loop header, not the preheader). assert(!L->contains(ExitBlock) && "Exit block is in the loop?"); - BasicBlock *NewExit = SplitBlock(ExitBlock, ExitBlock->begin(), this); - - // Okay, now we have a position to branch from and a position to branch to, + BasicBlock *NewExit = SplitBlock(ExitBlock, ExitBlock->begin(), DT, LI); + + // Okay, now we have a position to branch from and a position to branch to, // insert the new conditional branch. - EmitPreheaderBranchOnCondition(Cond, Val, NewExit, NewPH, - loopPreheader->getTerminator()); + EmitPreheaderBranchOnCondition(Cond, Val, NewExit, NewPH, + loopPreheader->getTerminator(), TI); LPM->deleteSimpleAnalysisValue(loopPreheader->getTerminator(), L); loopPreheader->getTerminator()->eraseFromParent(); // We need to reprocess this loop, it could be unswitched again. redoLoop = true; - + // Now that we know that the loop is never entered when this condition is a // particular value, rewrite the loop with this info. We know that this will // at least eliminate the old branch. @@ -733,28 +804,10 @@ void LoopUnswitch::UnswitchTrivialCondition(Loop *L, Value *Cond, ++NumTrivial; } -/// HasIndirectBrsInPreds - Returns true if there are predecessors, that are -/// terminated with indirect branch instruction. -bool LoopUnswitch::HasIndirectBrsInPreds( - const SmallVectorImpl &ExitBlocks){ - - for (unsigned i = 0, e = ExitBlocks.size(); i != e; ++i) { - const BasicBlock *ExitBlock = ExitBlocks[i]; - for (const_pred_iterator p = pred_begin(ExitBlock), e = pred_end(ExitBlock); - p != e; ++p) { - // Cannot split an edge from an IndirectBrInst - if (isa((*p)->getTerminator())) - return true; - - } - } - return false; -} - /// SplitExitEdges - Split all of the edges from inside the loop to their exit /// blocks. Update the appropriate Phi nodes as we do so. -void LoopUnswitch::SplitExitEdges(Loop *L, - const SmallVector &ExitBlocks){ +void LoopUnswitch::SplitExitEdges(Loop *L, + const SmallVectorImpl &ExitBlocks){ for (unsigned i = 0, e = ExitBlocks.size(); i != e; ++i) { BasicBlock *ExitBlock = ExitBlocks[i]; @@ -763,21 +816,17 @@ void LoopUnswitch::SplitExitEdges(Loop *L, // Although SplitBlockPredecessors doesn't preserve loop-simplify in // general, if we call it on all predecessors of all exits then it does. - if (!ExitBlock->isLandingPad()) { - SplitBlockPredecessors(ExitBlock, Preds, ".us-lcssa", this); - } else { - SmallVector NewBBs; - SplitLandingPadPredecessors(ExitBlock, Preds, ".us-lcssa", ".us-lcssa", - this, NewBBs); - } + SplitBlockPredecessors(ExitBlock, Preds, ".us-lcssa", + /*AliasAnalysis*/ nullptr, DT, LI, + /*PreserveLCSSA*/ true); } } -/// UnswitchNontrivialCondition - We determined that the loop is profitable -/// to unswitch when LIC equal Val. Split it into loop versions and test the +/// UnswitchNontrivialCondition - We determined that the loop is profitable +/// to unswitch when LIC equal Val. Split it into loop versions and test the /// condition outside of either loop. Return the loops created as Out1/Out2. -bool LoopUnswitch::UnswitchNontrivialCondition(Value *LIC, Constant *Val, - Loop *L) { +void LoopUnswitch::UnswitchNontrivialCondition(Value *LIC, Constant *Val, + Loop *L, TerminatorInst *TI) { Function *F = loopHeader->getParent(); DEBUG(dbgs() << "loop-unswitch: Unswitching loop %" << loopHeader->getName() << " [" << L->getBlocks().size() @@ -792,7 +841,7 @@ bool LoopUnswitch::UnswitchNontrivialCondition(Value *LIC, Constant *Val, // First step, split the preheader and exit blocks, and add these blocks to // the LoopBlocks list. - BasicBlock *NewPreheader = SplitEdge(loopPreheader, loopHeader, this); + BasicBlock *NewPreheader = SplitEdge(loopPreheader, loopHeader, DT, LI); LoopBlocks.push_back(NewPreheader); // We want the loop to come after the preheader, but before the exit blocks. @@ -800,8 +849,6 @@ bool LoopUnswitch::UnswitchNontrivialCondition(Value *LIC, Constant *Val, SmallVector ExitBlocks; L->getUniqueExitBlocks(ExitBlocks); - if (HasIndirectBrsInPreds(ExitBlocks)) - return false; // Split all of the edges from inside the loop to their exit blocks. Update // the appropriate Phi nodes as we do so. @@ -821,7 +868,7 @@ bool LoopUnswitch::UnswitchNontrivialCondition(Value *LIC, Constant *Val, ValueToValueMapTy VMap; for (unsigned i = 0, e = LoopBlocks.size(); i != e; ++i) { BasicBlock *NewBB = CloneBasicBlock(LoopBlocks[i], VMap, ".us", F); - + NewBlocks.push_back(NewBB); VMap[LoopBlocks[i]] = NewBB; // Keep the BB mapping. LPM->cloneBasicBlockSimpleAnalysis(LoopBlocks[i], NewBB, L); @@ -832,6 +879,10 @@ bool LoopUnswitch::UnswitchNontrivialCondition(Value *LIC, Constant *Val, F->getBasicBlockList().splice(NewPreheader, F->getBasicBlockList(), NewBlocks[0], F->end()); + // FIXME: We could register any cloned assumptions instead of clearing the + // whole function's cache. + AC->clear(); + // Now we create the new Loop object for the versioned loop. Loop *NewLoop = CloneLoop(L, L->getParentLoop(), VMap, LI, LPM); @@ -843,24 +894,23 @@ bool LoopUnswitch::UnswitchNontrivialCondition(Value *LIC, Constant *Val, if (ParentLoop) { // Make sure to add the cloned preheader and exit blocks to the parent loop // as well. - ParentLoop->addBasicBlockToLoop(NewBlocks[0], LI->getBase()); + ParentLoop->addBasicBlockToLoop(NewBlocks[0], *LI); } for (unsigned i = 0, e = ExitBlocks.size(); i != e; ++i) { BasicBlock *NewExit = cast(VMap[ExitBlocks[i]]); // The new exit block should be in the same loop as the old one. if (Loop *ExitBBLoop = LI->getLoopFor(ExitBlocks[i])) - ExitBBLoop->addBasicBlockToLoop(NewExit, LI->getBase()); - + ExitBBLoop->addBasicBlockToLoop(NewExit, *LI); + assert(NewExit->getTerminator()->getNumSuccessors() == 1 && "Exit block should have been split to have one successor!"); BasicBlock *ExitSucc = NewExit->getTerminator()->getSuccessor(0); // If the successor of the exit block had PHI nodes, add an entry for // NewExit. - PHINode *PN; - for (BasicBlock::iterator I = ExitSucc->begin(); isa(I); ++I) { - PN = cast(I); + for (BasicBlock::iterator I = ExitSucc->begin(); + PHINode *PN = dyn_cast(I); ++I) { Value *V = PN->getIncomingValueForBlock(ExitBlocks[i]); ValueToValueMapTy::iterator It = VMap.find(V); if (It != VMap.end()) V = It->second; @@ -868,8 +918,8 @@ bool LoopUnswitch::UnswitchNontrivialCondition(Value *LIC, Constant *Val, } if (LandingPadInst *LPad = NewExit->getLandingPadInst()) { - PN = PHINode::Create(LPad->getType(), 0, "", - ExitSucc->getFirstInsertionPt()); + PHINode *PN = PHINode::Create(LPad->getType(), 0, "", + ExitSucc->getFirstInsertionPt()); for (pred_iterator I = pred_begin(ExitSucc), E = pred_end(ExitSucc); I != E; ++I) { @@ -886,14 +936,15 @@ bool LoopUnswitch::UnswitchNontrivialCondition(Value *LIC, Constant *Val, for (BasicBlock::iterator I = NewBlocks[i]->begin(), E = NewBlocks[i]->end(); I != E; ++I) RemapInstruction(I, VMap,RF_NoModuleLevelChanges|RF_IgnoreMissingEntries); - + // Rewrite the original preheader to select between versions of the loop. BranchInst *OldBR = cast(loopPreheader->getTerminator()); assert(OldBR->isUnconditional() && OldBR->getSuccessor(0) == LoopBlocks[0] && "Preheader splitting did not work correctly!"); // Emit the new branch that selects between the two versions of this loop. - EmitPreheaderBranchOnCondition(LIC, Val, NewBlocks[0], LoopBlocks[0], OldBR); + EmitPreheaderBranchOnCondition(LIC, Val, NewBlocks[0], LoopBlocks[0], OldBR, + TI); LPM->deleteSimpleAnalysisValue(OldBR, L); OldBR->eraseFromParent(); @@ -905,7 +956,7 @@ bool LoopUnswitch::UnswitchNontrivialCondition(Value *LIC, Constant *Val, // the condition that we're unswitching on), we don't rewrite the second // iteration. WeakVH LICHandle(LIC); - + // Now we rewrite the original code to know that the condition is true and the // new code to know that the condition is false. RewriteLoopBodyWithConditionConstant(L, LIC, Val, false); @@ -916,26 +967,20 @@ bool LoopUnswitch::UnswitchNontrivialCondition(Value *LIC, Constant *Val, if (!LoopProcessWorklist.empty() && LoopProcessWorklist.back() == NewLoop && LICHandle && !isa(LICHandle)) RewriteLoopBodyWithConditionConstant(NewLoop, LICHandle, Val, true); - - return true; } /// RemoveFromWorklist - Remove all instances of I from the worklist vector /// specified. -static void RemoveFromWorklist(Instruction *I, +static void RemoveFromWorklist(Instruction *I, std::vector &Worklist) { - std::vector::iterator WI = std::find(Worklist.begin(), - Worklist.end(), I); - while (WI != Worklist.end()) { - unsigned Offset = WI-Worklist.begin(); - Worklist.erase(WI); - WI = std::find(Worklist.begin()+Offset, Worklist.end(), I); - } + + Worklist.erase(std::remove(Worklist.begin(), Worklist.end(), I), + Worklist.end()); } /// ReplaceUsesOfWith - When we find that I really equals V, remove I from the /// program, replacing all uses with V and update the worklist. -static void ReplaceUsesOfWith(Instruction *I, Value *V, +static void ReplaceUsesOfWith(Instruction *I, Value *V, std::vector &Worklist, Loop *L, LPPassManager *LPM) { DEBUG(dbgs() << "Replace with '" << *V << "': " << *I); @@ -946,9 +991,8 @@ static void ReplaceUsesOfWith(Instruction *I, Value *V, Worklist.push_back(Use); // Add users to the worklist which may be simplified now. - for (Value::use_iterator UI = I->use_begin(), E = I->use_end(); - UI != E; ++UI) - Worklist.push_back(cast(*UI)); + for (User *U : I->users()) + Worklist.push_back(cast(U)); LPM->deleteSimpleAnalysisValue(I, L); RemoveFromWorklist(I, Worklist); I->replaceAllUsesWith(V); @@ -956,128 +1000,6 @@ static void ReplaceUsesOfWith(Instruction *I, Value *V, ++NumSimplify; } -/// RemoveBlockIfDead - If the specified block is dead, remove it, update loop -/// information, and remove any dead successors it has. -/// -void LoopUnswitch::RemoveBlockIfDead(BasicBlock *BB, - std::vector &Worklist, - Loop *L) { - if (pred_begin(BB) != pred_end(BB)) { - // This block isn't dead, since an edge to BB was just removed, see if there - // are any easy simplifications we can do now. - if (BasicBlock *Pred = BB->getSinglePredecessor()) { - // If it has one pred, fold phi nodes in BB. - while (isa(BB->begin())) - ReplaceUsesOfWith(BB->begin(), - cast(BB->begin())->getIncomingValue(0), - Worklist, L, LPM); - - // If this is the header of a loop and the only pred is the latch, we now - // have an unreachable loop. - if (Loop *L = LI->getLoopFor(BB)) - if (loopHeader == BB && L->contains(Pred)) { - // Remove the branch from the latch to the header block, this makes - // the header dead, which will make the latch dead (because the header - // dominates the latch). - LPM->deleteSimpleAnalysisValue(Pred->getTerminator(), L); - Pred->getTerminator()->eraseFromParent(); - new UnreachableInst(BB->getContext(), Pred); - - // The loop is now broken, remove it from LI. - RemoveLoopFromHierarchy(L); - - // Reprocess the header, which now IS dead. - RemoveBlockIfDead(BB, Worklist, L); - return; - } - - // If pred ends in a uncond branch, add uncond branch to worklist so that - // the two blocks will get merged. - if (BranchInst *BI = dyn_cast(Pred->getTerminator())) - if (BI->isUnconditional()) - Worklist.push_back(BI); - } - return; - } - - DEBUG(dbgs() << "Nuking dead block: " << *BB); - - // Remove the instructions in the basic block from the worklist. - for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) { - RemoveFromWorklist(I, Worklist); - - // Anything that uses the instructions in this basic block should have their - // uses replaced with undefs. - // If I is not void type then replaceAllUsesWith undef. - // This allows ValueHandlers and custom metadata to adjust itself. - if (!I->getType()->isVoidTy()) - I->replaceAllUsesWith(UndefValue::get(I->getType())); - } - - // If this is the edge to the header block for a loop, remove the loop and - // promote all subloops. - if (Loop *BBLoop = LI->getLoopFor(BB)) { - if (BBLoop->getLoopLatch() == BB) { - RemoveLoopFromHierarchy(BBLoop); - if (currentLoop == BBLoop) { - currentLoop = 0; - redoLoop = false; - } - } - } - - // Remove the block from the loop info, which removes it from any loops it - // was in. - LI->removeBlock(BB); - - - // Remove phi node entries in successors for this block. - TerminatorInst *TI = BB->getTerminator(); - SmallVector Succs; - for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i) { - Succs.push_back(TI->getSuccessor(i)); - TI->getSuccessor(i)->removePredecessor(BB); - } - - // Unique the successors, remove anything with multiple uses. - array_pod_sort(Succs.begin(), Succs.end()); - Succs.erase(std::unique(Succs.begin(), Succs.end()), Succs.end()); - - // Remove the basic block, including all of the instructions contained in it. - LPM->deleteSimpleAnalysisValue(BB, L); - BB->eraseFromParent(); - // Remove successor blocks here that are not dead, so that we know we only - // have dead blocks in this list. Nondead blocks have a way of becoming dead, - // then getting removed before we revisit them, which is badness. - // - for (unsigned i = 0; i != Succs.size(); ++i) - if (pred_begin(Succs[i]) != pred_end(Succs[i])) { - // One exception is loop headers. If this block was the preheader for a - // loop, then we DO want to visit the loop so the loop gets deleted. - // We know that if the successor is a loop header, that this loop had to - // be the preheader: the case where this was the latch block was handled - // above and headers can only have two predecessors. - if (!LI->isLoopHeader(Succs[i])) { - Succs.erase(Succs.begin()+i); - --i; - } - } - - for (unsigned i = 0, e = Succs.size(); i != e; ++i) - RemoveBlockIfDead(Succs[i], Worklist, L); -} - -/// RemoveLoopFromHierarchy - We have discovered that the specified loop has -/// become unwrapped, either because the backedge was deleted, or because the -/// edge into the header was removed. If the edge into the header from the -/// latch block was removed, the loop is unwrapped but subloops are still alive, -/// so they just reparent loops. If the loops are actually dead, they will be -/// removed later. -void LoopUnswitch::RemoveLoopFromHierarchy(Loop *L) { - LPM->deleteLoopFromQueue(L); - RemoveLoopFromWorklist(L); -} - // RewriteLoopBodyWithConditionConstant - We know either that the value LIC has // the value specified by Val in the specified loop, or we know it does NOT have // that value. Rewrite any uses of LIC or of properties correlated to it. @@ -1085,20 +1007,19 @@ void LoopUnswitch::RewriteLoopBodyWithConditionConstant(Loop *L, Value *LIC, Constant *Val, bool IsEqual) { assert(!isa(LIC) && "Why are we unswitching on a constant?"); - + // FIXME: Support correlated properties, like: // for (...) // if (li1 < li2) // ... // if (li1 > li2) // ... - + // FOLD boolean conditions (X|LIC), (X&LIC). Fold conditional branches, // selects, switches. std::vector Worklist; LLVMContext &Context = Val->getContext(); - // If we know that LIC == Val, or that LIC == NotVal, just replace uses of LIC // in the loop with the appropriate one directly. if (IsEqual || (isa(Val) && @@ -1107,57 +1028,55 @@ void LoopUnswitch::RewriteLoopBodyWithConditionConstant(Loop *L, Value *LIC, if (IsEqual) Replacement = Val; else - Replacement = ConstantInt::get(Type::getInt1Ty(Val->getContext()), + Replacement = ConstantInt::get(Type::getInt1Ty(Val->getContext()), !cast(Val)->getZExtValue()); - - for (Value::use_iterator UI = LIC->use_begin(), E = LIC->use_end(); - UI != E; ++UI) { - Instruction *U = dyn_cast(*UI); - if (!U || !L->contains(U)) + + for (User *U : LIC->users()) { + Instruction *UI = dyn_cast(U); + if (!UI || !L->contains(UI)) continue; - Worklist.push_back(U); + Worklist.push_back(UI); } - - for (std::vector::iterator UI = Worklist.begin(); - UI != Worklist.end(); ++UI) - (*UI)->replaceUsesOfWith(LIC, Replacement); - + + for (std::vector::iterator UI = Worklist.begin(), + UE = Worklist.end(); UI != UE; ++UI) + (*UI)->replaceUsesOfWith(LIC, Replacement); + SimplifyCode(Worklist, L); return; } - + // Otherwise, we don't know the precise value of LIC, but we do know that it // is certainly NOT "Val". As such, simplify any uses in the loop that we // can. This case occurs when we unswitch switch statements. - for (Value::use_iterator UI = LIC->use_begin(), E = LIC->use_end(); - UI != E; ++UI) { - Instruction *U = dyn_cast(*UI); - if (!U || !L->contains(U)) + for (User *U : LIC->users()) { + Instruction *UI = dyn_cast(U); + if (!UI || !L->contains(UI)) continue; - Worklist.push_back(U); + Worklist.push_back(UI); - // TODO: We could do other simplifications, for example, turning + // TODO: We could do other simplifications, for example, turning // 'icmp eq LIC, Val' -> false. // If we know that LIC is not Val, use this info to simplify code. - SwitchInst *SI = dyn_cast(U); - if (SI == 0 || !isa(Val)) continue; - + SwitchInst *SI = dyn_cast(UI); + if (!SI || !isa(Val)) continue; + SwitchInst::CaseIt DeadCase = SI->findCaseValue(cast(Val)); // Default case is live for multiple values. if (DeadCase == SI->case_default()) continue; - - // Found a dead case value. Don't remove PHI nodes in the + + // Found a dead case value. Don't remove PHI nodes in the // successor if they become single-entry, those PHI nodes may // be in the Users list. BasicBlock *Switch = SI->getParent(); BasicBlock *SISucc = DeadCase.getCaseSuccessor(); BasicBlock *Latch = L->getLoopLatch(); - + BranchesInfo.setUnswitched(SI, Val); - + if (!SI->findCaseDest(SISucc)) continue; // Edge is critical. // If the DeadCase successor dominates the loop latch, then the // transformation isn't safe since it will delete the sole predecessor edge @@ -1169,7 +1088,7 @@ void LoopUnswitch::RewriteLoopBodyWithConditionConstant(Loop *L, Value *LIC, // and hooked up so as to preserve the loop structure, because // trying to update it is complicated. So instead we preserve the // loop structure and put the block on a dead code path. - SplitEdge(Switch, SISucc, this); + SplitEdge(Switch, SISucc, DT, LI); // Compute the successors instead of relying on the return value // of SplitEdge, since it may have split the switch successor // after PHI nodes. @@ -1197,7 +1116,7 @@ void LoopUnswitch::RewriteLoopBodyWithConditionConstant(Loop *L, Value *LIC, if (DT) DT->addNewBlock(Abort, NewSISucc); } - + SimplifyCode(Worklist, L); } @@ -1211,6 +1130,7 @@ void LoopUnswitch::RewriteLoopBodyWithConditionConstant(Loop *L, Value *LIC, /// pass. /// void LoopUnswitch::SimplifyCode(std::vector &Worklist, Loop *L) { + const DataLayout &DL = L->getHeader()->getModule()->getDataLayout(); while (!Worklist.empty()) { Instruction *I = Worklist.back(); Worklist.pop_back(); @@ -1218,7 +1138,7 @@ void LoopUnswitch::SimplifyCode(std::vector &Worklist, Loop *L) { // Simple DCE. if (isInstructionTriviallyDead(I)) { DEBUG(dbgs() << "Remove dead instruction '" << *I); - + // Add uses to the worklist, which may be dead now. for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) if (Instruction *Use = dyn_cast(I->getOperand(i))) @@ -1232,8 +1152,8 @@ void LoopUnswitch::SimplifyCode(std::vector &Worklist, Loop *L) { // See if instruction simplification can hack this up. This is common for // things like "select false, X, Y" after unswitching made the condition be - // 'false'. - if (Value *V = SimplifyInstruction(I, 0, 0, DT)) + // 'false'. TODO: update the domtree properly so we can pass it here. + if (Value *V = SimplifyInstruction(I, DL)) if (LI->replacementPreservesLCSSAForm(I, V)) { ReplaceUsesOfWith(I, V, Worklist, L, LPM); continue; @@ -1250,24 +1170,24 @@ void LoopUnswitch::SimplifyCode(std::vector &Worklist, Loop *L) { if (!SinglePred) continue; // Nothing to do. assert(SinglePred == Pred && "CFG broken"); - DEBUG(dbgs() << "Merging blocks: " << Pred->getName() << " <- " + DEBUG(dbgs() << "Merging blocks: " << Pred->getName() << " <- " << Succ->getName() << "\n"); - + // Resolve any single entry PHI nodes in Succ. while (PHINode *PN = dyn_cast(Succ->begin())) ReplaceUsesOfWith(PN, PN->getIncomingValue(0), Worklist, L, LPM); - + // If Succ has any successors with PHI nodes, update them to have // entries coming from Pred instead of Succ. Succ->replaceAllUsesWith(Pred); - + // Move all of the successor contents from Succ to Pred. Pred->getInstList().splice(BI, Succ->getInstList(), Succ->begin(), Succ->end()); LPM->deleteSimpleAnalysisValue(BI, L); BI->eraseFromParent(); RemoveFromWorklist(BI, Worklist); - + // Remove Succ from the loop tree. LI->removeBlock(Succ); LPM->deleteSimpleAnalysisValue(Succ, L); @@ -1275,24 +1195,7 @@ void LoopUnswitch::SimplifyCode(std::vector &Worklist, Loop *L) { ++NumSimplify; continue; } - - if (ConstantInt *CB = dyn_cast(BI->getCondition())){ - // Conditional branch. Turn it into an unconditional branch, then - // remove dead blocks. - continue; // FIXME: Enable. - - DEBUG(dbgs() << "Folded branch: " << *BI); - BasicBlock *DeadSucc = BI->getSuccessor(CB->getZExtValue()); - BasicBlock *LiveSucc = BI->getSuccessor(!CB->getZExtValue()); - DeadSucc->removePredecessor(BI->getParent(), true); - Worklist.push_back(BranchInst::Create(LiveSucc, BI)); - LPM->deleteSimpleAnalysisValue(BI, L); - BI->eraseFromParent(); - RemoveFromWorklist(BI, Worklist); - ++NumSimplify; - RemoveBlockIfDead(DeadSucc, Worklist, L); - } continue; } }