diff options
Diffstat (limited to 'contrib/llvm/lib/Transforms/Scalar/EarlyCSE.cpp')
| -rw-r--r-- | contrib/llvm/lib/Transforms/Scalar/EarlyCSE.cpp | 664 |
1 files changed, 398 insertions, 266 deletions
diff --git a/contrib/llvm/lib/Transforms/Scalar/EarlyCSE.cpp b/contrib/llvm/lib/Transforms/Scalar/EarlyCSE.cpp index 969b9a8f8df1..8b629eaca9d4 100644 --- a/contrib/llvm/lib/Transforms/Scalar/EarlyCSE.cpp +++ b/contrib/llvm/lib/Transforms/Scalar/EarlyCSE.cpp @@ -12,12 +12,14 @@ // //===----------------------------------------------------------------------===// -#include "llvm/Transforms/Scalar.h" +#include "llvm/Transforms/Scalar/EarlyCSE.h" #include "llvm/ADT/Hashing.h" #include "llvm/ADT/ScopedHashTable.h" #include "llvm/ADT/Statistic.h" #include "llvm/Analysis/AssumptionCache.h" #include "llvm/Analysis/InstructionSimplify.h" +#include "llvm/Analysis/TargetLibraryInfo.h" +#include "llvm/Analysis/TargetTransformInfo.h" #include "llvm/IR/DataLayout.h" #include "llvm/IR/Dominators.h" #include "llvm/IR/Instructions.h" @@ -26,7 +28,8 @@ #include "llvm/Pass.h" #include "llvm/Support/Debug.h" #include "llvm/Support/RecyclingAllocator.h" -#include "llvm/Target/TargetLibraryInfo.h" +#include "llvm/Support/raw_ostream.h" +#include "llvm/Transforms/Scalar.h" #include "llvm/Transforms/Utils/Local.h" #include <deque> using namespace llvm; @@ -40,59 +43,54 @@ STATISTIC(NumCSELoad, "Number of load instructions CSE'd"); STATISTIC(NumCSECall, "Number of call instructions CSE'd"); STATISTIC(NumDSE, "Number of trivial dead stores removed"); -static unsigned getHash(const void *V) { - return DenseMapInfo<const void*>::getHashValue(V); -} - //===----------------------------------------------------------------------===// // SimpleValue //===----------------------------------------------------------------------===// namespace { - /// SimpleValue - Instances of this struct represent available values in the - /// scoped hash table. - struct SimpleValue { - Instruction *Inst; +/// \brief Struct representing the available values in the scoped hash table. +struct SimpleValue { + Instruction *Inst; - SimpleValue(Instruction *I) : Inst(I) { - assert((isSentinel() || canHandle(I)) && "Inst can't be handled!"); - } + SimpleValue(Instruction *I) : Inst(I) { + assert((isSentinel() || canHandle(I)) && "Inst can't be handled!"); + } - bool isSentinel() const { - return Inst == DenseMapInfo<Instruction*>::getEmptyKey() || - Inst == DenseMapInfo<Instruction*>::getTombstoneKey(); - } + bool isSentinel() const { + return Inst == DenseMapInfo<Instruction *>::getEmptyKey() || + Inst == DenseMapInfo<Instruction *>::getTombstoneKey(); + } - static bool canHandle(Instruction *Inst) { - // This can only handle non-void readnone functions. - if (CallInst *CI = dyn_cast<CallInst>(Inst)) - return CI->doesNotAccessMemory() && !CI->getType()->isVoidTy(); - return isa<CastInst>(Inst) || isa<BinaryOperator>(Inst) || - isa<GetElementPtrInst>(Inst) || isa<CmpInst>(Inst) || - isa<SelectInst>(Inst) || isa<ExtractElementInst>(Inst) || - isa<InsertElementInst>(Inst) || isa<ShuffleVectorInst>(Inst) || - isa<ExtractValueInst>(Inst) || isa<InsertValueInst>(Inst); - } - }; -} + static bool canHandle(Instruction *Inst) { + // This can only handle non-void readnone functions. + if (CallInst *CI = dyn_cast<CallInst>(Inst)) + return CI->doesNotAccessMemory() && !CI->getType()->isVoidTy(); + return isa<CastInst>(Inst) || isa<BinaryOperator>(Inst) || + isa<GetElementPtrInst>(Inst) || isa<CmpInst>(Inst) || + isa<SelectInst>(Inst) || isa<ExtractElementInst>(Inst) || + isa<InsertElementInst>(Inst) || isa<ShuffleVectorInst>(Inst) || + isa<ExtractValueInst>(Inst) || isa<InsertValueInst>(Inst); + } +}; +} // namespace namespace llvm { -template<> struct DenseMapInfo<SimpleValue> { +template <> struct DenseMapInfo<SimpleValue> { static inline SimpleValue getEmptyKey() { - return DenseMapInfo<Instruction*>::getEmptyKey(); + return DenseMapInfo<Instruction *>::getEmptyKey(); } static inline SimpleValue getTombstoneKey() { - return DenseMapInfo<Instruction*>::getTombstoneKey(); + return DenseMapInfo<Instruction *>::getTombstoneKey(); } static unsigned getHashValue(SimpleValue Val); static bool isEqual(SimpleValue LHS, SimpleValue RHS); }; -} +} // namespace llvm unsigned DenseMapInfo<SimpleValue>::getHashValue(SimpleValue Val) { Instruction *Inst = Val.Inst; // Hash in all of the operands as pointers. - if (BinaryOperator* BinOp = dyn_cast<BinaryOperator>(Inst)) { + if (BinaryOperator *BinOp = dyn_cast<BinaryOperator>(Inst)) { Value *LHS = BinOp->getOperand(0); Value *RHS = BinOp->getOperand(1); if (BinOp->isCommutative() && BinOp->getOperand(0) > BinOp->getOperand(1)) @@ -101,8 +99,9 @@ unsigned DenseMapInfo<SimpleValue>::getHashValue(SimpleValue Val) { if (isa<OverflowingBinaryOperator>(BinOp)) { // Hash the overflow behavior unsigned Overflow = - BinOp->hasNoSignedWrap() * OverflowingBinaryOperator::NoSignedWrap | - BinOp->hasNoUnsignedWrap() * OverflowingBinaryOperator::NoUnsignedWrap; + BinOp->hasNoSignedWrap() * OverflowingBinaryOperator::NoSignedWrap | + BinOp->hasNoUnsignedWrap() * + OverflowingBinaryOperator::NoUnsignedWrap; return hash_combine(BinOp->getOpcode(), Overflow, LHS, RHS); } @@ -135,12 +134,13 @@ unsigned DenseMapInfo<SimpleValue>::getHashValue(SimpleValue Val) { assert((isa<CallInst>(Inst) || isa<BinaryOperator>(Inst) || isa<GetElementPtrInst>(Inst) || isa<SelectInst>(Inst) || isa<ExtractElementInst>(Inst) || isa<InsertElementInst>(Inst) || - isa<ShuffleVectorInst>(Inst)) && "Invalid/unknown instruction"); + isa<ShuffleVectorInst>(Inst)) && + "Invalid/unknown instruction"); // Mix in the opcode. - return hash_combine(Inst->getOpcode(), - hash_combine_range(Inst->value_op_begin(), - Inst->value_op_end())); + return hash_combine( + Inst->getOpcode(), + hash_combine_range(Inst->value_op_begin(), Inst->value_op_end())); } bool DenseMapInfo<SimpleValue>::isEqual(SimpleValue LHS, SimpleValue RHS) { @@ -149,22 +149,24 @@ bool DenseMapInfo<SimpleValue>::isEqual(SimpleValue LHS, SimpleValue RHS) { if (LHS.isSentinel() || RHS.isSentinel()) return LHSI == RHSI; - if (LHSI->getOpcode() != RHSI->getOpcode()) return false; - if (LHSI->isIdenticalTo(RHSI)) return true; + if (LHSI->getOpcode() != RHSI->getOpcode()) + return false; + if (LHSI->isIdenticalTo(RHSI)) + return true; // If we're not strictly identical, we still might be a commutable instruction if (BinaryOperator *LHSBinOp = dyn_cast<BinaryOperator>(LHSI)) { if (!LHSBinOp->isCommutative()) return false; - assert(isa<BinaryOperator>(RHSI) - && "same opcode, but different instruction type?"); + assert(isa<BinaryOperator>(RHSI) && + "same opcode, but different instruction type?"); BinaryOperator *RHSBinOp = cast<BinaryOperator>(RHSI); // Check overflow attributes if (isa<OverflowingBinaryOperator>(LHSBinOp)) { - assert(isa<OverflowingBinaryOperator>(RHSBinOp) - && "same opcode, but different operator type?"); + assert(isa<OverflowingBinaryOperator>(RHSBinOp) && + "same opcode, but different operator type?"); if (LHSBinOp->hasNoUnsignedWrap() != RHSBinOp->hasNoUnsignedWrap() || LHSBinOp->hasNoSignedWrap() != RHSBinOp->hasNoSignedWrap()) return false; @@ -172,16 +174,16 @@ bool DenseMapInfo<SimpleValue>::isEqual(SimpleValue LHS, SimpleValue RHS) { // Commuted equality return LHSBinOp->getOperand(0) == RHSBinOp->getOperand(1) && - LHSBinOp->getOperand(1) == RHSBinOp->getOperand(0); + LHSBinOp->getOperand(1) == RHSBinOp->getOperand(0); } if (CmpInst *LHSCmp = dyn_cast<CmpInst>(LHSI)) { - assert(isa<CmpInst>(RHSI) - && "same opcode, but different instruction type?"); + assert(isa<CmpInst>(RHSI) && + "same opcode, but different instruction type?"); CmpInst *RHSCmp = cast<CmpInst>(RHSI); // Commuted equality return LHSCmp->getOperand(0) == RHSCmp->getOperand(1) && - LHSCmp->getOperand(1) == RHSCmp->getOperand(0) && - LHSCmp->getSwappedPredicate() == RHSCmp->getPredicate(); + LHSCmp->getOperand(1) == RHSCmp->getOperand(0) && + LHSCmp->getSwappedPredicate() == RHSCmp->getPredicate(); } return false; @@ -192,57 +194,52 @@ bool DenseMapInfo<SimpleValue>::isEqual(SimpleValue LHS, SimpleValue RHS) { //===----------------------------------------------------------------------===// namespace { - /// CallValue - Instances of this struct represent available call values in - /// the scoped hash table. - struct CallValue { - Instruction *Inst; +/// \brief Struct representing the available call values in the scoped hash +/// table. +struct CallValue { + Instruction *Inst; - CallValue(Instruction *I) : Inst(I) { - assert((isSentinel() || canHandle(I)) && "Inst can't be handled!"); - } + CallValue(Instruction *I) : Inst(I) { + assert((isSentinel() || canHandle(I)) && "Inst can't be handled!"); + } - bool isSentinel() const { - return Inst == DenseMapInfo<Instruction*>::getEmptyKey() || - Inst == DenseMapInfo<Instruction*>::getTombstoneKey(); - } + bool isSentinel() const { + return Inst == DenseMapInfo<Instruction *>::getEmptyKey() || + Inst == DenseMapInfo<Instruction *>::getTombstoneKey(); + } - static bool canHandle(Instruction *Inst) { - // Don't value number anything that returns void. - if (Inst->getType()->isVoidTy()) - return false; + static bool canHandle(Instruction *Inst) { + // Don't value number anything that returns void. + if (Inst->getType()->isVoidTy()) + return false; - CallInst *CI = dyn_cast<CallInst>(Inst); - if (!CI || !CI->onlyReadsMemory()) - return false; - return true; - } - }; -} + CallInst *CI = dyn_cast<CallInst>(Inst); + if (!CI || !CI->onlyReadsMemory()) + return false; + return true; + } +}; +} // namespace namespace llvm { - template<> struct DenseMapInfo<CallValue> { - static inline CallValue getEmptyKey() { - return DenseMapInfo<Instruction*>::getEmptyKey(); - } - static inline CallValue getTombstoneKey() { - return DenseMapInfo<Instruction*>::getTombstoneKey(); - } - static unsigned getHashValue(CallValue Val); - static bool isEqual(CallValue LHS, CallValue RHS); - }; -} -unsigned DenseMapInfo<CallValue>::getHashValue(CallValue Val) { - Instruction *Inst = Val.Inst; - // Hash in all of the operands as pointers. - unsigned Res = 0; - for (unsigned i = 0, e = Inst->getNumOperands(); i != e; ++i) { - assert(!Inst->getOperand(i)->getType()->isMetadataTy() && - "Cannot value number calls with metadata operands"); - Res ^= getHash(Inst->getOperand(i)) << (i & 0xF); +template <> struct DenseMapInfo<CallValue> { + static inline CallValue getEmptyKey() { + return DenseMapInfo<Instruction *>::getEmptyKey(); + } + static inline CallValue getTombstoneKey() { + return DenseMapInfo<Instruction *>::getTombstoneKey(); } + static unsigned getHashValue(CallValue Val); + static bool isEqual(CallValue LHS, CallValue RHS); +}; +} // namespace llvm - // Mix in the opcode. - return (Res << 1) ^ Inst->getOpcode(); +unsigned DenseMapInfo<CallValue>::getHashValue(CallValue Val) { + Instruction *Inst = Val.Inst; + // Hash all of the operands as pointers and mix in the opcode. + return hash_combine( + Inst->getOpcode(), + hash_combine_range(Inst->value_op_begin(), Inst->value_op_end())); } bool DenseMapInfo<CallValue>::isEqual(CallValue LHS, CallValue RHS) { @@ -252,103 +249,104 @@ bool DenseMapInfo<CallValue>::isEqual(CallValue LHS, CallValue RHS) { return LHSI->isIdenticalTo(RHSI); } - //===----------------------------------------------------------------------===// -// EarlyCSE pass. +// EarlyCSE implementation //===----------------------------------------------------------------------===// namespace { - -/// EarlyCSE - This pass does a simple depth-first walk over the dominator -/// tree, eliminating trivially redundant instructions and using instsimplify -/// to canonicalize things as it goes. It is intended to be fast and catch -/// obvious cases so that instcombine and other passes are more effective. It -/// is expected that a later pass of GVN will catch the interesting/hard -/// cases. -class EarlyCSE : public FunctionPass { +/// \brief A simple and fast domtree-based CSE pass. +/// +/// This pass does a simple depth-first walk over the dominator tree, +/// eliminating trivially redundant instructions and using instsimplify to +/// canonicalize things as it goes. It is intended to be fast and catch obvious +/// cases so that instcombine and other passes are more effective. It is +/// expected that a later pass of GVN will catch the interesting/hard cases. +class EarlyCSE { public: - const DataLayout *DL; - const TargetLibraryInfo *TLI; - DominatorTree *DT; - AssumptionCache *AC; - typedef RecyclingAllocator<BumpPtrAllocator, - ScopedHashTableVal<SimpleValue, Value*> > AllocatorTy; - typedef ScopedHashTable<SimpleValue, Value*, DenseMapInfo<SimpleValue>, + Function &F; + const TargetLibraryInfo &TLI; + const TargetTransformInfo &TTI; + DominatorTree &DT; + AssumptionCache &AC; + typedef RecyclingAllocator< + BumpPtrAllocator, ScopedHashTableVal<SimpleValue, Value *>> AllocatorTy; + typedef ScopedHashTable<SimpleValue, Value *, DenseMapInfo<SimpleValue>, AllocatorTy> ScopedHTType; - /// AvailableValues - This scoped hash table contains the current values of - /// all of our simple scalar expressions. As we walk down the domtree, we - /// look to see if instructions are in this: if so, we replace them with what - /// we find, otherwise we insert them so that dominated values can succeed in - /// their lookup. - ScopedHTType *AvailableValues; - - /// AvailableLoads - This scoped hash table contains the current values - /// of loads. This allows us to get efficient access to dominating loads when - /// we have a fully redundant load. In addition to the most recent load, we - /// keep track of a generation count of the read, which is compared against - /// the current generation count. The current generation count is - /// incremented after every possibly writing memory operation, which ensures - /// that we only CSE loads with other loads that have no intervening store. - typedef RecyclingAllocator<BumpPtrAllocator, - ScopedHashTableVal<Value*, std::pair<Value*, unsigned> > > LoadMapAllocator; - typedef ScopedHashTable<Value*, std::pair<Value*, unsigned>, - DenseMapInfo<Value*>, LoadMapAllocator> LoadHTType; - LoadHTType *AvailableLoads; - - /// AvailableCalls - This scoped hash table contains the current values - /// of read-only call values. It uses the same generation count as loads. - typedef ScopedHashTable<CallValue, std::pair<Value*, unsigned> > CallHTType; - CallHTType *AvailableCalls; - - /// CurrentGeneration - This is the current generation of the memory value. + /// \brief A scoped hash table of the current values of all of our simple + /// scalar expressions. + /// + /// As we walk down the domtree, we look to see if instructions are in this: + /// if so, we replace them with what we find, otherwise we insert them so + /// that dominated values can succeed in their lookup. + ScopedHTType AvailableValues; + + /// \brief A scoped hash table of the current values of loads. + /// + /// This allows us to get efficient access to dominating loads when we have + /// a fully redundant load. In addition to the most recent load, we keep + /// track of a generation count of the read, which is compared against the + /// current generation count. The current generation count is incremented + /// after every possibly writing memory operation, which ensures that we only + /// CSE loads with other loads that have no intervening store. + typedef RecyclingAllocator< + BumpPtrAllocator, + ScopedHashTableVal<Value *, std::pair<Value *, unsigned>>> + LoadMapAllocator; + typedef ScopedHashTable<Value *, std::pair<Value *, unsigned>, + DenseMapInfo<Value *>, LoadMapAllocator> LoadHTType; + LoadHTType AvailableLoads; + + /// \brief A scoped hash table of the current values of read-only call + /// values. + /// + /// It uses the same generation count as loads. + typedef ScopedHashTable<CallValue, std::pair<Value *, unsigned>> CallHTType; + CallHTType AvailableCalls; + + /// \brief This is the current generation of the memory value. unsigned CurrentGeneration; - static char ID; - explicit EarlyCSE() : FunctionPass(ID) { - initializeEarlyCSEPass(*PassRegistry::getPassRegistry()); - } + /// \brief Set up the EarlyCSE runner for a particular function. + EarlyCSE(Function &F, const TargetLibraryInfo &TLI, + const TargetTransformInfo &TTI, DominatorTree &DT, + AssumptionCache &AC) + : F(F), TLI(TLI), TTI(TTI), DT(DT), AC(AC), CurrentGeneration(0) {} - bool runOnFunction(Function &F) override; + bool run(); private: - - // NodeScope - almost a POD, but needs to call the constructors for the - // scoped hash tables so that a new scope gets pushed on. These are RAII so - // that the scope gets popped when the NodeScope is destroyed. + // Almost a POD, but needs to call the constructors for the scoped hash + // tables so that a new scope gets pushed on. These are RAII so that the + // scope gets popped when the NodeScope is destroyed. class NodeScope { - public: - NodeScope(ScopedHTType *availableValues, - LoadHTType *availableLoads, - CallHTType *availableCalls) : - Scope(*availableValues), - LoadScope(*availableLoads), - CallScope(*availableCalls) {} - - private: - NodeScope(const NodeScope&) LLVM_DELETED_FUNCTION; - void operator=(const NodeScope&) LLVM_DELETED_FUNCTION; + public: + NodeScope(ScopedHTType &AvailableValues, LoadHTType &AvailableLoads, + CallHTType &AvailableCalls) + : Scope(AvailableValues), LoadScope(AvailableLoads), + CallScope(AvailableCalls) {} + + private: + NodeScope(const NodeScope &) = delete; + void operator=(const NodeScope &) = delete; ScopedHTType::ScopeTy Scope; LoadHTType::ScopeTy LoadScope; CallHTType::ScopeTy CallScope; }; - // StackNode - contains all the needed information to create a stack for - // doing a depth first tranversal of the tree. This includes scopes for - // values, loads, and calls as well as the generation. There is a child - // iterator so that the children do not need to be store spearately. + // Contains all the needed information to create a stack for doing a depth + // first tranversal of the tree. This includes scopes for values, loads, and + // calls as well as the generation. There is a child iterator so that the + // children do not need to be store spearately. class StackNode { - public: - StackNode(ScopedHTType *availableValues, - LoadHTType *availableLoads, - CallHTType *availableCalls, - unsigned cg, DomTreeNode *n, - DomTreeNode::iterator child, DomTreeNode::iterator end) : - CurrentGeneration(cg), ChildGeneration(cg), Node(n), - ChildIter(child), EndIter(end), - Scopes(availableValues, availableLoads, availableCalls), - Processed(false) {} + public: + StackNode(ScopedHTType &AvailableValues, LoadHTType &AvailableLoads, + CallHTType &AvailableCalls, unsigned cg, DomTreeNode *n, + DomTreeNode::iterator child, DomTreeNode::iterator end) + : CurrentGeneration(cg), ChildGeneration(cg), Node(n), ChildIter(child), + EndIter(end), Scopes(AvailableValues, AvailableLoads, AvailableCalls), + Processed(false) {} // Accessors. unsigned currentGeneration() { return CurrentGeneration; } @@ -365,9 +363,9 @@ private: bool isProcessed() { return Processed; } void process() { Processed = true; } - private: - StackNode(const StackNode&) LLVM_DELETED_FUNCTION; - void operator=(const StackNode&) LLVM_DELETED_FUNCTION; + private: + StackNode(const StackNode &) = delete; + void operator=(const StackNode &) = delete; // Members. unsigned CurrentGeneration; @@ -379,30 +377,77 @@ private: bool Processed; }; + /// \brief Wrapper class to handle memory instructions, including loads, + /// stores and intrinsic loads and stores defined by the target. + class ParseMemoryInst { + public: + ParseMemoryInst(Instruction *Inst, const TargetTransformInfo &TTI) + : Load(false), Store(false), Vol(false), MayReadFromMemory(false), + MayWriteToMemory(false), MatchingId(-1), Ptr(nullptr) { + MayReadFromMemory = Inst->mayReadFromMemory(); + MayWriteToMemory = Inst->mayWriteToMemory(); + if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(Inst)) { + MemIntrinsicInfo Info; + if (!TTI.getTgtMemIntrinsic(II, Info)) + return; + if (Info.NumMemRefs == 1) { + Store = Info.WriteMem; + Load = Info.ReadMem; + MatchingId = Info.MatchingId; + MayReadFromMemory = Info.ReadMem; + MayWriteToMemory = Info.WriteMem; + Vol = Info.Vol; + Ptr = Info.PtrVal; + } + } else if (LoadInst *LI = dyn_cast<LoadInst>(Inst)) { + Load = true; + Vol = !LI->isSimple(); + Ptr = LI->getPointerOperand(); + } else if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) { + Store = true; + Vol = !SI->isSimple(); + Ptr = SI->getPointerOperand(); + } + } + bool isLoad() { return Load; } + bool isStore() { return Store; } + bool isVolatile() { return Vol; } + bool isMatchingMemLoc(const ParseMemoryInst &Inst) { + return Ptr == Inst.Ptr && MatchingId == Inst.MatchingId; + } + bool isValid() { return Ptr != nullptr; } + int getMatchingId() { return MatchingId; } + Value *getPtr() { return Ptr; } + bool mayReadFromMemory() { return MayReadFromMemory; } + bool mayWriteToMemory() { return MayWriteToMemory; } + + private: + bool Load; + bool Store; + bool Vol; + bool MayReadFromMemory; + bool MayWriteToMemory; + // For regular (non-intrinsic) loads/stores, this is set to -1. For + // intrinsic loads/stores, the id is retrieved from the corresponding + // field in the MemIntrinsicInfo structure. That field contains + // non-negative values only. + int MatchingId; + Value *Ptr; + }; + bool processNode(DomTreeNode *Node); - // This transformation requires dominator postdominator info - void getAnalysisUsage(AnalysisUsage &AU) const override { - AU.addRequired<AssumptionCacheTracker>(); - AU.addRequired<DominatorTreeWrapperPass>(); - AU.addRequired<TargetLibraryInfo>(); - AU.setPreservesCFG(); + Value *getOrCreateResult(Value *Inst, Type *ExpectedType) const { + if (LoadInst *LI = dyn_cast<LoadInst>(Inst)) + return LI; + else if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) + return SI->getValueOperand(); + assert(isa<IntrinsicInst>(Inst) && "Instruction not supported"); + return TTI.getOrCreateResultFromMemIntrinsic(cast<IntrinsicInst>(Inst), + ExpectedType); } }; -} - -char EarlyCSE::ID = 0; - -// createEarlyCSEPass - The public interface to this file. -FunctionPass *llvm::createEarlyCSEPass() { - return new EarlyCSE(); -} - -INITIALIZE_PASS_BEGIN(EarlyCSE, "early-cse", "Early CSE", false, false) -INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker) -INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass) -INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfo) -INITIALIZE_PASS_END(EarlyCSE, "early-cse", "Early CSE", false, false) +} // namespace bool EarlyCSE::processNode(DomTreeNode *Node) { BasicBlock *BB = Node->getBlock(); @@ -416,21 +461,46 @@ bool EarlyCSE::processNode(DomTreeNode *Node) { if (!BB->getSinglePredecessor()) ++CurrentGeneration; + // If this node has a single predecessor which ends in a conditional branch, + // we can infer the value of the branch condition given that we took this + // path. We need the single predeccesor to ensure there's not another path + // which reaches this block where the condition might hold a different + // value. Since we're adding this to the scoped hash table (like any other + // def), it will have been popped if we encounter a future merge block. + if (BasicBlock *Pred = BB->getSinglePredecessor()) + if (auto *BI = dyn_cast<BranchInst>(Pred->getTerminator())) + if (BI->isConditional()) + if (auto *CondInst = dyn_cast<Instruction>(BI->getCondition())) + if (SimpleValue::canHandle(CondInst)) { + assert(BI->getSuccessor(0) == BB || BI->getSuccessor(1) == BB); + auto *ConditionalConstant = (BI->getSuccessor(0) == BB) ? + ConstantInt::getTrue(BB->getContext()) : + ConstantInt::getFalse(BB->getContext()); + AvailableValues.insert(CondInst, ConditionalConstant); + DEBUG(dbgs() << "EarlyCSE CVP: Add conditional value for '" + << CondInst->getName() << "' as " << *ConditionalConstant + << " in " << BB->getName() << "\n"); + // Replace all dominated uses with the known value + replaceDominatedUsesWith(CondInst, ConditionalConstant, DT, + BasicBlockEdge(Pred, BB)); + } + /// LastStore - Keep track of the last non-volatile store that we saw... for /// as long as there in no instruction that reads memory. If we see a store /// to the same location, we delete the dead store. This zaps trivial dead /// stores which can occur in bitfield code among other things. - StoreInst *LastStore = nullptr; + Instruction *LastStore = nullptr; bool Changed = false; + const DataLayout &DL = BB->getModule()->getDataLayout(); // See if any instructions in the block can be eliminated. If so, do it. If // not, add them to AvailableValues. - for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ) { + for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E;) { Instruction *Inst = I++; // Dead instructions should just be removed. - if (isInstructionTriviallyDead(Inst, TLI)) { + if (isInstructionTriviallyDead(Inst, &TLI)) { DEBUG(dbgs() << "EarlyCSE DCE: " << *Inst << '\n'); Inst->eraseFromParent(); Changed = true; @@ -449,7 +519,7 @@ bool EarlyCSE::processNode(DomTreeNode *Node) { // If the instruction can be simplified (e.g. X+0 = X) then replace it with // its simpler value. - if (Value *V = SimplifyInstruction(Inst, DL, TLI, DT, AC)) { + if (Value *V = SimplifyInstruction(Inst, DL, &TLI, &DT, &AC)) { DEBUG(dbgs() << "EarlyCSE Simplify: " << *Inst << " to: " << *V << '\n'); Inst->replaceAllUsesWith(V); Inst->eraseFromParent(); @@ -461,7 +531,7 @@ bool EarlyCSE::processNode(DomTreeNode *Node) { // If this is a simple instruction that we can value number, process it. if (SimpleValue::canHandle(Inst)) { // See if the instruction has an available value. If so, use it. - if (Value *V = AvailableValues->lookup(Inst)) { + if (Value *V = AvailableValues.lookup(Inst)) { DEBUG(dbgs() << "EarlyCSE CSE: " << *Inst << " to: " << *V << '\n'); Inst->replaceAllUsesWith(V); Inst->eraseFromParent(); @@ -471,14 +541,15 @@ bool EarlyCSE::processNode(DomTreeNode *Node) { } // Otherwise, just remember that this value is available. - AvailableValues->insert(Inst, Inst); + AvailableValues.insert(Inst, Inst); continue; } + ParseMemoryInst MemInst(Inst, TTI); // If this is a non-volatile load, process it. - if (LoadInst *LI = dyn_cast<LoadInst>(Inst)) { + if (MemInst.isValid() && MemInst.isLoad()) { // Ignore volatile loads. - if (!LI->isSimple()) { + if (MemInst.isVolatile()) { LastStore = nullptr; // Don't CSE across synchronization boundaries. if (Inst->mayWriteToMemory()) @@ -488,38 +559,48 @@ bool EarlyCSE::processNode(DomTreeNode *Node) { // If we have an available version of this load, and if it is the right // generation, replace this instruction. - std::pair<Value*, unsigned> InVal = - AvailableLoads->lookup(Inst->getOperand(0)); + std::pair<Value *, unsigned> InVal = + AvailableLoads.lookup(MemInst.getPtr()); if (InVal.first != nullptr && InVal.second == CurrentGeneration) { - DEBUG(dbgs() << "EarlyCSE CSE LOAD: " << *Inst << " to: " - << *InVal.first << '\n'); - if (!Inst->use_empty()) Inst->replaceAllUsesWith(InVal.first); - Inst->eraseFromParent(); - Changed = true; - ++NumCSELoad; - continue; + Value *Op = getOrCreateResult(InVal.first, Inst->getType()); + if (Op != nullptr) { + DEBUG(dbgs() << "EarlyCSE CSE LOAD: " << *Inst + << " to: " << *InVal.first << '\n'); + if (!Inst->use_empty()) + Inst->replaceAllUsesWith(Op); + Inst->eraseFromParent(); + Changed = true; + ++NumCSELoad; + continue; + } } // Otherwise, remember that we have this instruction. - AvailableLoads->insert(Inst->getOperand(0), - std::pair<Value*, unsigned>(Inst, CurrentGeneration)); + AvailableLoads.insert(MemInst.getPtr(), std::pair<Value *, unsigned>( + Inst, CurrentGeneration)); LastStore = nullptr; continue; } // If this instruction may read from memory, forget LastStore. - if (Inst->mayReadFromMemory()) + // Load/store intrinsics will indicate both a read and a write to + // memory. The target may override this (e.g. so that a store intrinsic + // does not read from memory, and thus will be treated the same as a + // regular store for commoning purposes). + if (Inst->mayReadFromMemory() && + !(MemInst.isValid() && !MemInst.mayReadFromMemory())) LastStore = nullptr; // If this is a read-only call, process it. if (CallValue::canHandle(Inst)) { // If we have an available version of this call, and if it is the right // generation, replace this instruction. - std::pair<Value*, unsigned> InVal = AvailableCalls->lookup(Inst); + std::pair<Value *, unsigned> InVal = AvailableCalls.lookup(Inst); if (InVal.first != nullptr && InVal.second == CurrentGeneration) { - DEBUG(dbgs() << "EarlyCSE CSE CALL: " << *Inst << " to: " - << *InVal.first << '\n'); - if (!Inst->use_empty()) Inst->replaceAllUsesWith(InVal.first); + DEBUG(dbgs() << "EarlyCSE CSE CALL: " << *Inst + << " to: " << *InVal.first << '\n'); + if (!Inst->use_empty()) + Inst->replaceAllUsesWith(InVal.first); Inst->eraseFromParent(); Changed = true; ++NumCSECall; @@ -527,8 +608,8 @@ bool EarlyCSE::processNode(DomTreeNode *Node) { } // Otherwise, remember that we have this instruction. - AvailableCalls->insert(Inst, - std::pair<Value*, unsigned>(Inst, CurrentGeneration)); + AvailableCalls.insert( + Inst, std::pair<Value *, unsigned>(Inst, CurrentGeneration)); continue; } @@ -538,17 +619,19 @@ bool EarlyCSE::processNode(DomTreeNode *Node) { if (Inst->mayWriteToMemory()) { ++CurrentGeneration; - if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) { + if (MemInst.isValid() && MemInst.isStore()) { // We do a trivial form of DSE if there are two stores to the same // location with no intervening loads. Delete the earlier store. - if (LastStore && - LastStore->getPointerOperand() == SI->getPointerOperand()) { - DEBUG(dbgs() << "EarlyCSE DEAD STORE: " << *LastStore << " due to: " - << *Inst << '\n'); - LastStore->eraseFromParent(); - Changed = true; - ++NumDSE; - LastStore = nullptr; + if (LastStore) { + ParseMemoryInst LastStoreMemInst(LastStore, TTI); + if (LastStoreMemInst.isMatchingMemLoc(MemInst)) { + DEBUG(dbgs() << "EarlyCSE DEAD STORE: " << *LastStore + << " due to: " << *Inst << '\n'); + LastStore->eraseFromParent(); + Changed = true; + ++NumDSE; + LastStore = nullptr; + } // fallthrough - we can exploit information about this store } @@ -557,12 +640,12 @@ bool EarlyCSE::processNode(DomTreeNode *Node) { // version of the pointer. It is safe to forward from volatile stores // to non-volatile loads, so we don't have to check for volatility of // the store. - AvailableLoads->insert(SI->getPointerOperand(), - std::pair<Value*, unsigned>(SI->getValueOperand(), CurrentGeneration)); + AvailableLoads.insert(MemInst.getPtr(), std::pair<Value *, unsigned>( + Inst, CurrentGeneration)); // Remember that this was the last store we saw for DSE. - if (SI->isSimple()) - LastStore = SI; + if (!MemInst.isVolatile()) + LastStore = Inst; } } } @@ -570,40 +653,20 @@ bool EarlyCSE::processNode(DomTreeNode *Node) { return Changed; } - -bool EarlyCSE::runOnFunction(Function &F) { - if (skipOptnoneFunction(F)) - return false; - - // Note, deque is being used here because there is significant performance gains - // over vector when the container becomes very large due to the specific access - // patterns. For more information see the mailing list discussion on this: +bool EarlyCSE::run() { + // Note, deque is being used here because there is significant performance + // gains over vector when the container becomes very large due to the + // specific access patterns. For more information see the mailing list + // discussion on this: // http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20120116/135228.html std::deque<StackNode *> nodesToProcess; - DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>(); - DL = DLP ? &DLP->getDataLayout() : nullptr; - TLI = &getAnalysis<TargetLibraryInfo>(); - DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree(); - AC = &getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F); - - // Tables that the pass uses when walking the domtree. - ScopedHTType AVTable; - AvailableValues = &AVTable; - LoadHTType LoadTable; - AvailableLoads = &LoadTable; - CallHTType CallTable; - AvailableCalls = &CallTable; - - CurrentGeneration = 0; bool Changed = false; // Process the root node. - nodesToProcess.push_back( - new StackNode(AvailableValues, AvailableLoads, AvailableCalls, - CurrentGeneration, DT->getRootNode(), - DT->getRootNode()->begin(), - DT->getRootNode()->end())); + nodesToProcess.push_back(new StackNode( + AvailableValues, AvailableLoads, AvailableCalls, CurrentGeneration, + DT.getRootNode(), DT.getRootNode()->begin(), DT.getRootNode()->end())); // Save the current generation. unsigned LiveOutGeneration = CurrentGeneration; @@ -627,11 +690,9 @@ bool EarlyCSE::runOnFunction(Function &F) { // Push the next child onto the stack. DomTreeNode *child = NodeToProcess->nextChild(); nodesToProcess.push_back( - new StackNode(AvailableValues, - AvailableLoads, - AvailableCalls, - NodeToProcess->childGeneration(), child, - child->begin(), child->end())); + new StackNode(AvailableValues, AvailableLoads, AvailableCalls, + NodeToProcess->childGeneration(), child, child->begin(), + child->end())); } else { // It has been processed, and there are no more children to process, // so delete it and pop it off the stack. @@ -645,3 +706,74 @@ bool EarlyCSE::runOnFunction(Function &F) { return Changed; } + +PreservedAnalyses EarlyCSEPass::run(Function &F, + AnalysisManager<Function> *AM) { + auto &TLI = AM->getResult<TargetLibraryAnalysis>(F); + auto &TTI = AM->getResult<TargetIRAnalysis>(F); + auto &DT = AM->getResult<DominatorTreeAnalysis>(F); + auto &AC = AM->getResult<AssumptionAnalysis>(F); + + EarlyCSE CSE(F, TLI, TTI, DT, AC); + + if (!CSE.run()) + return PreservedAnalyses::all(); + + // CSE preserves the dominator tree because it doesn't mutate the CFG. + // FIXME: Bundle this with other CFG-preservation. + PreservedAnalyses PA; + PA.preserve<DominatorTreeAnalysis>(); + return PA; +} + +namespace { +/// \brief A simple and fast domtree-based CSE pass. +/// +/// This pass does a simple depth-first walk over the dominator tree, +/// eliminating trivially redundant instructions and using instsimplify to +/// canonicalize things as it goes. It is intended to be fast and catch obvious +/// cases so that instcombine and other passes are more effective. It is +/// expected that a later pass of GVN will catch the interesting/hard cases. +class EarlyCSELegacyPass : public FunctionPass { +public: + static char ID; + + EarlyCSELegacyPass() : FunctionPass(ID) { + initializeEarlyCSELegacyPassPass(*PassRegistry::getPassRegistry()); + } + + bool runOnFunction(Function &F) override { + if (skipOptnoneFunction(F)) + return false; + + auto &TLI = getAnalysis<TargetLibraryInfoWrapperPass>().getTLI(); + auto &TTI = getAnalysis<TargetTransformInfoWrapperPass>().getTTI(F); + auto &DT = getAnalysis<DominatorTreeWrapperPass>().getDomTree(); + auto &AC = getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F); + + EarlyCSE CSE(F, TLI, TTI, DT, AC); + + return CSE.run(); + } + + void getAnalysisUsage(AnalysisUsage &AU) const override { + AU.addRequired<AssumptionCacheTracker>(); + AU.addRequired<DominatorTreeWrapperPass>(); + AU.addRequired<TargetLibraryInfoWrapperPass>(); + AU.addRequired<TargetTransformInfoWrapperPass>(); + AU.setPreservesCFG(); + } +}; +} // namespace + +char EarlyCSELegacyPass::ID = 0; + +FunctionPass *llvm::createEarlyCSEPass() { return new EarlyCSELegacyPass(); } + +INITIALIZE_PASS_BEGIN(EarlyCSELegacyPass, "early-cse", "Early CSE", false, + false) +INITIALIZE_PASS_DEPENDENCY(TargetTransformInfoWrapperPass) +INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker) +INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass) +INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass) +INITIALIZE_PASS_END(EarlyCSELegacyPass, "early-cse", "Early CSE", false, false) |