| //===- CodeGenPrepare.cpp - Prepare a function for code generation --------===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This pass munges the code in the input function to better prepare it for |
| // SelectionDAG-based code generation. This works around limitations in it's |
| // basic-block-at-a-time approach. It should eventually be removed. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "llvm/CodeGen/Passes.h" |
| #include "llvm/ADT/DenseMap.h" |
| #include "llvm/ADT/SmallSet.h" |
| #include "llvm/ADT/Statistic.h" |
| #include "llvm/Analysis/InstructionSimplify.h" |
| #include "llvm/Analysis/TargetLibraryInfo.h" |
| #include "llvm/Analysis/TargetTransformInfo.h" |
| #include "llvm/IR/CallSite.h" |
| #include "llvm/IR/Constants.h" |
| #include "llvm/IR/DataLayout.h" |
| #include "llvm/IR/DerivedTypes.h" |
| #include "llvm/IR/Dominators.h" |
| #include "llvm/IR/Function.h" |
| #include "llvm/IR/GetElementPtrTypeIterator.h" |
| #include "llvm/IR/IRBuilder.h" |
| #include "llvm/IR/InlineAsm.h" |
| #include "llvm/IR/Instructions.h" |
| #include "llvm/IR/IntrinsicInst.h" |
| #include "llvm/IR/MDBuilder.h" |
| #include "llvm/IR/PatternMatch.h" |
| #include "llvm/IR/Statepoint.h" |
| #include "llvm/IR/ValueHandle.h" |
| #include "llvm/IR/ValueMap.h" |
| #include "llvm/Pass.h" |
| #include "llvm/Support/CommandLine.h" |
| #include "llvm/Support/Debug.h" |
| #include "llvm/Support/raw_ostream.h" |
| #include "llvm/Target/TargetLowering.h" |
| #include "llvm/Target/TargetSubtargetInfo.h" |
| #include "llvm/Transforms/Utils/BasicBlockUtils.h" |
| #include "llvm/Transforms/Utils/BuildLibCalls.h" |
| #include "llvm/Transforms/Utils/BypassSlowDivision.h" |
| #include "llvm/Transforms/Utils/Local.h" |
| #include "llvm/Transforms/Utils/SimplifyLibCalls.h" |
| using namespace llvm; |
| using namespace llvm::PatternMatch; |
| |
| #define DEBUG_TYPE "codegenprepare" |
| |
| STATISTIC(NumBlocksElim, "Number of blocks eliminated"); |
| STATISTIC(NumPHIsElim, "Number of trivial PHIs eliminated"); |
| STATISTIC(NumGEPsElim, "Number of GEPs converted to casts"); |
| STATISTIC(NumCmpUses, "Number of uses of Cmp expressions replaced with uses of " |
| "sunken Cmps"); |
| STATISTIC(NumCastUses, "Number of uses of Cast expressions replaced with uses " |
| "of sunken Casts"); |
| STATISTIC(NumMemoryInsts, "Number of memory instructions whose address " |
| "computations were sunk"); |
| STATISTIC(NumExtsMoved, "Number of [s|z]ext instructions combined with loads"); |
| STATISTIC(NumExtUses, "Number of uses of [s|z]ext instructions optimized"); |
| STATISTIC(NumRetsDup, "Number of return instructions duplicated"); |
| STATISTIC(NumDbgValueMoved, "Number of debug value instructions moved"); |
| STATISTIC(NumSelectsExpanded, "Number of selects turned into branches"); |
| STATISTIC(NumAndCmpsMoved, "Number of and/cmp's pushed into branches"); |
| STATISTIC(NumStoreExtractExposed, "Number of store(extractelement) exposed"); |
| |
| static cl::opt<bool> DisableBranchOpts( |
| "disable-cgp-branch-opts", cl::Hidden, cl::init(false), |
| cl::desc("Disable branch optimizations in CodeGenPrepare")); |
| |
| static cl::opt<bool> |
| DisableGCOpts("disable-cgp-gc-opts", cl::Hidden, cl::init(false), |
| cl::desc("Disable GC optimizations in CodeGenPrepare")); |
| |
| static cl::opt<bool> DisableSelectToBranch( |
| "disable-cgp-select2branch", cl::Hidden, cl::init(false), |
| cl::desc("Disable select to branch conversion.")); |
| |
| static cl::opt<bool> AddrSinkUsingGEPs( |
| "addr-sink-using-gep", cl::Hidden, cl::init(false), |
| cl::desc("Address sinking in CGP using GEPs.")); |
| |
| static cl::opt<bool> EnableAndCmpSinking( |
| "enable-andcmp-sinking", cl::Hidden, cl::init(true), |
| cl::desc("Enable sinkinig and/cmp into branches.")); |
| |
| static cl::opt<bool> DisableStoreExtract( |
| "disable-cgp-store-extract", cl::Hidden, cl::init(false), |
| cl::desc("Disable store(extract) optimizations in CodeGenPrepare")); |
| |
| static cl::opt<bool> StressStoreExtract( |
| "stress-cgp-store-extract", cl::Hidden, cl::init(false), |
| cl::desc("Stress test store(extract) optimizations in CodeGenPrepare")); |
| |
| static cl::opt<bool> DisableExtLdPromotion( |
| "disable-cgp-ext-ld-promotion", cl::Hidden, cl::init(false), |
| cl::desc("Disable ext(promotable(ld)) -> promoted(ext(ld)) optimization in " |
| "CodeGenPrepare")); |
| |
| static cl::opt<bool> StressExtLdPromotion( |
| "stress-cgp-ext-ld-promotion", cl::Hidden, cl::init(false), |
| cl::desc("Stress test ext(promotable(ld)) -> promoted(ext(ld)) " |
| "optimization in CodeGenPrepare")); |
| |
| namespace { |
| typedef SmallPtrSet<Instruction *, 16> SetOfInstrs; |
| struct TypeIsSExt { |
| Type *Ty; |
| bool IsSExt; |
| TypeIsSExt(Type *Ty, bool IsSExt) : Ty(Ty), IsSExt(IsSExt) {} |
| }; |
| typedef DenseMap<Instruction *, TypeIsSExt> InstrToOrigTy; |
| class TypePromotionTransaction; |
| |
| class CodeGenPrepare : public FunctionPass { |
| /// TLI - Keep a pointer of a TargetLowering to consult for determining |
| /// transformation profitability. |
| const TargetMachine *TM; |
| const TargetLowering *TLI; |
| const TargetTransformInfo *TTI; |
| const TargetLibraryInfo *TLInfo; |
| |
| /// CurInstIterator - As we scan instructions optimizing them, this is the |
| /// next instruction to optimize. Xforms that can invalidate this should |
| /// update it. |
| BasicBlock::iterator CurInstIterator; |
| |
| /// Keeps track of non-local addresses that have been sunk into a block. |
| /// This allows us to avoid inserting duplicate code for blocks with |
| /// multiple load/stores of the same address. |
| ValueMap<Value*, Value*> SunkAddrs; |
| |
| /// Keeps track of all instructions inserted for the current function. |
| SetOfInstrs InsertedInsts; |
| /// Keeps track of the type of the related instruction before their |
| /// promotion for the current function. |
| InstrToOrigTy PromotedInsts; |
| |
| /// ModifiedDT - If CFG is modified in anyway. |
| bool ModifiedDT; |
| |
| /// OptSize - True if optimizing for size. |
| bool OptSize; |
| |
| /// DataLayout for the Function being processed. |
| const DataLayout *DL; |
| |
| public: |
| static char ID; // Pass identification, replacement for typeid |
| explicit CodeGenPrepare(const TargetMachine *TM = nullptr) |
| : FunctionPass(ID), TM(TM), TLI(nullptr), TTI(nullptr), DL(nullptr) { |
| initializeCodeGenPreparePass(*PassRegistry::getPassRegistry()); |
| } |
| bool runOnFunction(Function &F) override; |
| |
| const char *getPassName() const override { return "CodeGen Prepare"; } |
| |
| void getAnalysisUsage(AnalysisUsage &AU) const override { |
| AU.addPreserved<DominatorTreeWrapperPass>(); |
| AU.addRequired<TargetLibraryInfoWrapperPass>(); |
| AU.addRequired<TargetTransformInfoWrapperPass>(); |
| } |
| |
| private: |
| bool EliminateFallThrough(Function &F); |
| bool EliminateMostlyEmptyBlocks(Function &F); |
| bool CanMergeBlocks(const BasicBlock *BB, const BasicBlock *DestBB) const; |
| void EliminateMostlyEmptyBlock(BasicBlock *BB); |
| bool OptimizeBlock(BasicBlock &BB, bool& ModifiedDT); |
| bool OptimizeInst(Instruction *I, bool& ModifiedDT); |
| bool OptimizeMemoryInst(Instruction *I, Value *Addr, |
| Type *AccessTy, unsigned AS); |
| bool OptimizeInlineAsmInst(CallInst *CS); |
| bool OptimizeCallInst(CallInst *CI, bool& ModifiedDT); |
| bool MoveExtToFormExtLoad(Instruction *&I); |
| bool OptimizeExtUses(Instruction *I); |
| bool OptimizeSelectInst(SelectInst *SI); |
| bool OptimizeShuffleVectorInst(ShuffleVectorInst *SI); |
| bool OptimizeExtractElementInst(Instruction *Inst); |
| bool DupRetToEnableTailCallOpts(BasicBlock *BB); |
| bool PlaceDbgValues(Function &F); |
| bool sinkAndCmp(Function &F); |
| bool ExtLdPromotion(TypePromotionTransaction &TPT, LoadInst *&LI, |
| Instruction *&Inst, |
| const SmallVectorImpl<Instruction *> &Exts, |
| unsigned CreatedInstCost); |
| bool splitBranchCondition(Function &F); |
| bool simplifyOffsetableRelocate(Instruction &I); |
| }; |
| } |
| |
| char CodeGenPrepare::ID = 0; |
| INITIALIZE_TM_PASS(CodeGenPrepare, "codegenprepare", |
| "Optimize for code generation", false, false) |
| |
| FunctionPass *llvm::createCodeGenPreparePass(const TargetMachine *TM) { |
| return new CodeGenPrepare(TM); |
| } |
| |
| bool CodeGenPrepare::runOnFunction(Function &F) { |
| if (skipOptnoneFunction(F)) |
| return false; |
| |
| DL = &F.getParent()->getDataLayout(); |
| |
| bool EverMadeChange = false; |
| // Clear per function information. |
| InsertedInsts.clear(); |
| PromotedInsts.clear(); |
| |
| ModifiedDT = false; |
| if (TM) |
| TLI = TM->getSubtargetImpl(F)->getTargetLowering(); |
| TLInfo = &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI(); |
| TTI = &getAnalysis<TargetTransformInfoWrapperPass>().getTTI(F); |
| OptSize = F.hasFnAttribute(Attribute::OptimizeForSize); |
| |
| /// This optimization identifies DIV instructions that can be |
| /// profitably bypassed and carried out with a shorter, faster divide. |
| if (!OptSize && TLI && TLI->isSlowDivBypassed()) { |
| const DenseMap<unsigned int, unsigned int> &BypassWidths = |
| TLI->getBypassSlowDivWidths(); |
| for (Function::iterator I = F.begin(); I != F.end(); I++) |
| EverMadeChange |= bypassSlowDivision(F, I, BypassWidths); |
| } |
| |
| // Eliminate blocks that contain only PHI nodes and an |
| // unconditional branch. |
| EverMadeChange |= EliminateMostlyEmptyBlocks(F); |
| |
| // llvm.dbg.value is far away from the value then iSel may not be able |
| // handle it properly. iSel will drop llvm.dbg.value if it can not |
| // find a node corresponding to the value. |
| EverMadeChange |= PlaceDbgValues(F); |
| |
| // If there is a mask, compare against zero, and branch that can be combined |
| // into a single target instruction, push the mask and compare into branch |
| // users. Do this before OptimizeBlock -> OptimizeInst -> |
| // OptimizeCmpExpression, which perturbs the pattern being searched for. |
| if (!DisableBranchOpts) { |
| EverMadeChange |= sinkAndCmp(F); |
| EverMadeChange |= splitBranchCondition(F); |
| } |
| |
| bool MadeChange = true; |
| while (MadeChange) { |
| MadeChange = false; |
| for (Function::iterator I = F.begin(); I != F.end(); ) { |
| BasicBlock *BB = I++; |
| bool ModifiedDTOnIteration = false; |
| MadeChange |= OptimizeBlock(*BB, ModifiedDTOnIteration); |
| |
| // Restart BB iteration if the dominator tree of the Function was changed |
| if (ModifiedDTOnIteration) |
| break; |
| } |
| EverMadeChange |= MadeChange; |
| } |
| |
| SunkAddrs.clear(); |
| |
| if (!DisableBranchOpts) { |
| MadeChange = false; |
| SmallPtrSet<BasicBlock*, 8> WorkList; |
| for (BasicBlock &BB : F) { |
| SmallVector<BasicBlock *, 2> Successors(succ_begin(&BB), succ_end(&BB)); |
| MadeChange |= ConstantFoldTerminator(&BB, true); |
| if (!MadeChange) continue; |
| |
| for (SmallVectorImpl<BasicBlock*>::iterator |
| II = Successors.begin(), IE = Successors.end(); II != IE; ++II) |
| if (pred_begin(*II) == pred_end(*II)) |
| WorkList.insert(*II); |
| } |
| |
| // Delete the dead blocks and any of their dead successors. |
| MadeChange |= !WorkList.empty(); |
| while (!WorkList.empty()) { |
| BasicBlock *BB = *WorkList.begin(); |
| WorkList.erase(BB); |
| SmallVector<BasicBlock*, 2> Successors(succ_begin(BB), succ_end(BB)); |
| |
| DeleteDeadBlock(BB); |
| |
| for (SmallVectorImpl<BasicBlock*>::iterator |
| II = Successors.begin(), IE = Successors.end(); II != IE; ++II) |
| if (pred_begin(*II) == pred_end(*II)) |
| WorkList.insert(*II); |
| } |
| |
| // Merge pairs of basic blocks with unconditional branches, connected by |
| // a single edge. |
| if (EverMadeChange || MadeChange) |
| MadeChange |= EliminateFallThrough(F); |
| |
| EverMadeChange |= MadeChange; |
| } |
| |
| if (!DisableGCOpts) { |
| SmallVector<Instruction *, 2> Statepoints; |
| for (BasicBlock &BB : F) |
| for (Instruction &I : BB) |
| if (isStatepoint(I)) |
| Statepoints.push_back(&I); |
| for (auto &I : Statepoints) |
| EverMadeChange |= simplifyOffsetableRelocate(*I); |
| } |
| |
| return EverMadeChange; |
| } |
| |
| /// EliminateFallThrough - Merge basic blocks which are connected |
| /// by a single edge, where one of the basic blocks has a single successor |
| /// pointing to the other basic block, which has a single predecessor. |
| bool CodeGenPrepare::EliminateFallThrough(Function &F) { |
| bool Changed = false; |
| // Scan all of the blocks in the function, except for the entry block. |
| for (Function::iterator I = std::next(F.begin()), E = F.end(); I != E;) { |
| BasicBlock *BB = I++; |
| // If the destination block has a single pred, then this is a trivial |
| // edge, just collapse it. |
| BasicBlock *SinglePred = BB->getSinglePredecessor(); |
| |
| // Don't merge if BB's address is taken. |
| if (!SinglePred || SinglePred == BB || BB->hasAddressTaken()) continue; |
| |
| BranchInst *Term = dyn_cast<BranchInst>(SinglePred->getTerminator()); |
| if (Term && !Term->isConditional()) { |
| Changed = true; |
| DEBUG(dbgs() << "To merge:\n"<< *SinglePred << "\n\n\n"); |
| // Remember if SinglePred was the entry block of the function. |
| // If so, we will need to move BB back to the entry position. |
| bool isEntry = SinglePred == &SinglePred->getParent()->getEntryBlock(); |
| MergeBasicBlockIntoOnlyPred(BB, nullptr); |
| |
| if (isEntry && BB != &BB->getParent()->getEntryBlock()) |
| BB->moveBefore(&BB->getParent()->getEntryBlock()); |
| |
| // We have erased a block. Update the iterator. |
| I = BB; |
| } |
| } |
| return Changed; |
| } |
| |
| /// EliminateMostlyEmptyBlocks - eliminate blocks that contain only PHI nodes, |
| /// debug info directives, and an unconditional branch. Passes before isel |
| /// (e.g. LSR/loopsimplify) often split edges in ways that are non-optimal for |
| /// isel. Start by eliminating these blocks so we can split them the way we |
| /// want them. |
| bool CodeGenPrepare::EliminateMostlyEmptyBlocks(Function &F) { |
| bool MadeChange = false; |
| // Note that this intentionally skips the entry block. |
| for (Function::iterator I = std::next(F.begin()), E = F.end(); I != E;) { |
| BasicBlock *BB = I++; |
| |
| // If this block doesn't end with an uncond branch, ignore it. |
| BranchInst *BI = dyn_cast<BranchInst>(BB->getTerminator()); |
| if (!BI || !BI->isUnconditional()) |
| continue; |
| |
| // If the instruction before the branch (skipping debug info) isn't a phi |
| // node, then other stuff is happening here. |
| BasicBlock::iterator BBI = BI; |
| if (BBI != BB->begin()) { |
| --BBI; |
| while (isa<DbgInfoIntrinsic>(BBI)) { |
| if (BBI == BB->begin()) |
| break; |
| --BBI; |
| } |
| if (!isa<DbgInfoIntrinsic>(BBI) && !isa<PHINode>(BBI)) |
| continue; |
| } |
| |
| // Do not break infinite loops. |
| BasicBlock *DestBB = BI->getSuccessor(0); |
| if (DestBB == BB) |
| continue; |
| |
| if (!CanMergeBlocks(BB, DestBB)) |
| continue; |
| |
| EliminateMostlyEmptyBlock(BB); |
| MadeChange = true; |
| } |
| return MadeChange; |
| } |
| |
| /// CanMergeBlocks - Return true if we can merge BB into DestBB if there is a |
| /// single uncond branch between them, and BB contains no other non-phi |
| /// instructions. |
| bool CodeGenPrepare::CanMergeBlocks(const BasicBlock *BB, |
| const BasicBlock *DestBB) const { |
| // We only want to eliminate blocks whose phi nodes are used by phi nodes in |
| // the successor. If there are more complex condition (e.g. preheaders), |
| // don't mess around with them. |
| BasicBlock::const_iterator BBI = BB->begin(); |
| while (const PHINode *PN = dyn_cast<PHINode>(BBI++)) { |
| for (const User *U : PN->users()) { |
| const Instruction *UI = cast<Instruction>(U); |
| if (UI->getParent() != DestBB || !isa<PHINode>(UI)) |
| return false; |
| // If User is inside DestBB block and it is a PHINode then check |
| // incoming value. If incoming value is not from BB then this is |
| // a complex condition (e.g. preheaders) we want to avoid here. |
| if (UI->getParent() == DestBB) { |
| if (const PHINode *UPN = dyn_cast<PHINode>(UI)) |
| for (unsigned I = 0, E = UPN->getNumIncomingValues(); I != E; ++I) { |
| Instruction *Insn = dyn_cast<Instruction>(UPN->getIncomingValue(I)); |
| if (Insn && Insn->getParent() == BB && |
| Insn->getParent() != UPN->getIncomingBlock(I)) |
| return false; |
| } |
| } |
| } |
| } |
| |
| // If BB and DestBB contain any common predecessors, then the phi nodes in BB |
| // and DestBB may have conflicting incoming values for the block. If so, we |
| // can't merge the block. |
| const PHINode *DestBBPN = dyn_cast<PHINode>(DestBB->begin()); |
| if (!DestBBPN) return true; // no conflict. |
| |
| // Collect the preds of BB. |
| SmallPtrSet<const BasicBlock*, 16> BBPreds; |
| if (const PHINode *BBPN = dyn_cast<PHINode>(BB->begin())) { |
| // It is faster to get preds from a PHI than with pred_iterator. |
| for (unsigned i = 0, e = BBPN->getNumIncomingValues(); i != e; ++i) |
| BBPreds.insert(BBPN->getIncomingBlock(i)); |
| } else { |
| BBPreds.insert(pred_begin(BB), pred_end(BB)); |
| } |
| |
| // Walk the preds of DestBB. |
| for (unsigned i = 0, e = DestBBPN->getNumIncomingValues(); i != e; ++i) { |
| BasicBlock *Pred = DestBBPN->getIncomingBlock(i); |
| if (BBPreds.count(Pred)) { // Common predecessor? |
| BBI = DestBB->begin(); |
| while (const PHINode *PN = dyn_cast<PHINode>(BBI++)) { |
| const Value *V1 = PN->getIncomingValueForBlock(Pred); |
| const Value *V2 = PN->getIncomingValueForBlock(BB); |
| |
| // If V2 is a phi node in BB, look up what the mapped value will be. |
| if (const PHINode *V2PN = dyn_cast<PHINode>(V2)) |
| if (V2PN->getParent() == BB) |
| V2 = V2PN->getIncomingValueForBlock(Pred); |
| |
| // If there is a conflict, bail out. |
| if (V1 != V2) return false; |
| } |
| } |
| } |
| |
| return true; |
| } |
| |
| |
| /// EliminateMostlyEmptyBlock - Eliminate a basic block that have only phi's and |
| /// an unconditional branch in it. |
| void CodeGenPrepare::EliminateMostlyEmptyBlock(BasicBlock *BB) { |
| BranchInst *BI = cast<BranchInst>(BB->getTerminator()); |
| BasicBlock *DestBB = BI->getSuccessor(0); |
| |
| DEBUG(dbgs() << "MERGING MOSTLY EMPTY BLOCKS - BEFORE:\n" << *BB << *DestBB); |
| |
| // If the destination block has a single pred, then this is a trivial edge, |
| // just collapse it. |
| if (BasicBlock *SinglePred = DestBB->getSinglePredecessor()) { |
| if (SinglePred != DestBB) { |
| // Remember if SinglePred was the entry block of the function. If so, we |
| // will need to move BB back to the entry position. |
| bool isEntry = SinglePred == &SinglePred->getParent()->getEntryBlock(); |
| MergeBasicBlockIntoOnlyPred(DestBB, nullptr); |
| |
| if (isEntry && BB != &BB->getParent()->getEntryBlock()) |
| BB->moveBefore(&BB->getParent()->getEntryBlock()); |
| |
| DEBUG(dbgs() << "AFTER:\n" << *DestBB << "\n\n\n"); |
| return; |
| } |
| } |
| |
| // Otherwise, we have multiple predecessors of BB. Update the PHIs in DestBB |
| // to handle the new incoming edges it is about to have. |
| PHINode *PN; |
| for (BasicBlock::iterator BBI = DestBB->begin(); |
| (PN = dyn_cast<PHINode>(BBI)); ++BBI) { |
| // Remove the incoming value for BB, and remember it. |
| Value *InVal = PN->removeIncomingValue(BB, false); |
| |
| // Two options: either the InVal is a phi node defined in BB or it is some |
| // value that dominates BB. |
| PHINode *InValPhi = dyn_cast<PHINode>(InVal); |
| if (InValPhi && InValPhi->getParent() == BB) { |
| // Add all of the input values of the input PHI as inputs of this phi. |
| for (unsigned i = 0, e = InValPhi->getNumIncomingValues(); i != e; ++i) |
| PN->addIncoming(InValPhi->getIncomingValue(i), |
| InValPhi->getIncomingBlock(i)); |
| } else { |
| // Otherwise, add one instance of the dominating value for each edge that |
| // we will be adding. |
| if (PHINode *BBPN = dyn_cast<PHINode>(BB->begin())) { |
| for (unsigned i = 0, e = BBPN->getNumIncomingValues(); i != e; ++i) |
| PN->addIncoming(InVal, BBPN->getIncomingBlock(i)); |
| } else { |
| for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI) |
| PN->addIncoming(InVal, *PI); |
| } |
| } |
| } |
| |
| // The PHIs are now updated, change everything that refers to BB to use |
| // DestBB and remove BB. |
| BB->replaceAllUsesWith(DestBB); |
| BB->eraseFromParent(); |
| ++NumBlocksElim; |
| |
| DEBUG(dbgs() << "AFTER:\n" << *DestBB << "\n\n\n"); |
| } |
| |
| // Computes a map of base pointer relocation instructions to corresponding |
| // derived pointer relocation instructions given a vector of all relocate calls |
| static void computeBaseDerivedRelocateMap( |
| const SmallVectorImpl<User *> &AllRelocateCalls, |
| DenseMap<IntrinsicInst *, SmallVector<IntrinsicInst *, 2>> & |
| RelocateInstMap) { |
| // Collect information in two maps: one primarily for locating the base object |
| // while filling the second map; the second map is the final structure holding |
| // a mapping between Base and corresponding Derived relocate calls |
| DenseMap<std::pair<unsigned, unsigned>, IntrinsicInst *> RelocateIdxMap; |
| for (auto &U : AllRelocateCalls) { |
| GCRelocateOperands ThisRelocate(U); |
| IntrinsicInst *I = cast<IntrinsicInst>(U); |
| auto K = std::make_pair(ThisRelocate.getBasePtrIndex(), |
| ThisRelocate.getDerivedPtrIndex()); |
| RelocateIdxMap.insert(std::make_pair(K, I)); |
| } |
| for (auto &Item : RelocateIdxMap) { |
| std::pair<unsigned, unsigned> Key = Item.first; |
| if (Key.first == Key.second) |
| // Base relocation: nothing to insert |
| continue; |
| |
| IntrinsicInst *I = Item.second; |
| auto BaseKey = std::make_pair(Key.first, Key.first); |
| |
| // We're iterating over RelocateIdxMap so we cannot modify it. |
| auto MaybeBase = RelocateIdxMap.find(BaseKey); |
| if (MaybeBase == RelocateIdxMap.end()) |
| // TODO: We might want to insert a new base object relocate and gep off |
| // that, if there are enough derived object relocates. |
| continue; |
| |
| RelocateInstMap[MaybeBase->second].push_back(I); |
| } |
| } |
| |
| // Accepts a GEP and extracts the operands into a vector provided they're all |
| // small integer constants |
| static bool getGEPSmallConstantIntOffsetV(GetElementPtrInst *GEP, |
| SmallVectorImpl<Value *> &OffsetV) { |
| for (unsigned i = 1; i < GEP->getNumOperands(); i++) { |
| // Only accept small constant integer operands |
| auto Op = dyn_cast<ConstantInt>(GEP->getOperand(i)); |
| if (!Op || Op->getZExtValue() > 20) |
| return false; |
| } |
| |
| for (unsigned i = 1; i < GEP->getNumOperands(); i++) |
| OffsetV.push_back(GEP->getOperand(i)); |
| return true; |
| } |
| |
| // Takes a RelocatedBase (base pointer relocation instruction) and Targets to |
| // replace, computes a replacement, and affects it. |
| static bool |
| simplifyRelocatesOffABase(IntrinsicInst *RelocatedBase, |
| const SmallVectorImpl<IntrinsicInst *> &Targets) { |
| bool MadeChange = false; |
| for (auto &ToReplace : Targets) { |
| GCRelocateOperands MasterRelocate(RelocatedBase); |
| GCRelocateOperands ThisRelocate(ToReplace); |
| |
| assert(ThisRelocate.getBasePtrIndex() == MasterRelocate.getBasePtrIndex() && |
| "Not relocating a derived object of the original base object"); |
| if (ThisRelocate.getBasePtrIndex() == ThisRelocate.getDerivedPtrIndex()) { |
| // A duplicate relocate call. TODO: coalesce duplicates. |
| continue; |
| } |
| |
| Value *Base = ThisRelocate.getBasePtr(); |
| auto Derived = dyn_cast<GetElementPtrInst>(ThisRelocate.getDerivedPtr()); |
| if (!Derived || Derived->getPointerOperand() != Base) |
| continue; |
| |
| SmallVector<Value *, 2> OffsetV; |
| if (!getGEPSmallConstantIntOffsetV(Derived, OffsetV)) |
| continue; |
| |
| // Create a Builder and replace the target callsite with a gep |
| assert(RelocatedBase->getNextNode() && "Should always have one since it's not a terminator"); |
| |
| // Insert after RelocatedBase |
| IRBuilder<> Builder(RelocatedBase->getNextNode()); |
| Builder.SetCurrentDebugLocation(ToReplace->getDebugLoc()); |
| |
| // If gc_relocate does not match the actual type, cast it to the right type. |
| // In theory, there must be a bitcast after gc_relocate if the type does not |
| // match, and we should reuse it to get the derived pointer. But it could be |
| // cases like this: |
| // bb1: |
| // ... |
| // %g1 = call coldcc i8 addrspace(1)* @llvm.experimental.gc.relocate.p1i8(...) |
| // br label %merge |
| // |
| // bb2: |
| // ... |
| // %g2 = call coldcc i8 addrspace(1)* @llvm.experimental.gc.relocate.p1i8(...) |
| // br label %merge |
| // |
| // merge: |
| // %p1 = phi i8 addrspace(1)* [ %g1, %bb1 ], [ %g2, %bb2 ] |
| // %cast = bitcast i8 addrspace(1)* %p1 in to i32 addrspace(1)* |
| // |
| // In this case, we can not find the bitcast any more. So we insert a new bitcast |
| // no matter there is already one or not. In this way, we can handle all cases, and |
| // the extra bitcast should be optimized away in later passes. |
| Instruction *ActualRelocatedBase = RelocatedBase; |
| if (RelocatedBase->getType() != Base->getType()) { |
| ActualRelocatedBase = |
| cast<Instruction>(Builder.CreateBitCast(RelocatedBase, Base->getType())); |
| } |
| Value *Replacement = Builder.CreateGEP( |
| Derived->getSourceElementType(), ActualRelocatedBase, makeArrayRef(OffsetV)); |
| Instruction *ReplacementInst = cast<Instruction>(Replacement); |
| Replacement->takeName(ToReplace); |
| // If the newly generated derived pointer's type does not match the original derived |
| // pointer's type, cast the new derived pointer to match it. Same reasoning as above. |
| Instruction *ActualReplacement = ReplacementInst; |
| if (ReplacementInst->getType() != ToReplace->getType()) { |
| ActualReplacement = |
| cast<Instruction>(Builder.CreateBitCast(ReplacementInst, ToReplace->getType())); |
| } |
| ToReplace->replaceAllUsesWith(ActualReplacement); |
| ToReplace->eraseFromParent(); |
| |
| MadeChange = true; |
| } |
| return MadeChange; |
| } |
| |
| // Turns this: |
| // |
| // %base = ... |
| // %ptr = gep %base + 15 |
| // %tok = statepoint (%fun, i32 0, i32 0, i32 0, %base, %ptr) |
| // %base' = relocate(%tok, i32 4, i32 4) |
| // %ptr' = relocate(%tok, i32 4, i32 5) |
| // %val = load %ptr' |
| // |
| // into this: |
| // |
| // %base = ... |
| // %ptr = gep %base + 15 |
| // %tok = statepoint (%fun, i32 0, i32 0, i32 0, %base, %ptr) |
| // %base' = gc.relocate(%tok, i32 4, i32 4) |
| // %ptr' = gep %base' + 15 |
| // %val = load %ptr' |
| bool CodeGenPrepare::simplifyOffsetableRelocate(Instruction &I) { |
| bool MadeChange = false; |
| SmallVector<User *, 2> AllRelocateCalls; |
| |
| for (auto *U : I.users()) |
| if (isGCRelocate(dyn_cast<Instruction>(U))) |
| // Collect all the relocate calls associated with a statepoint |
| AllRelocateCalls.push_back(U); |
| |
| // We need atleast one base pointer relocation + one derived pointer |
| // relocation to mangle |
| if (AllRelocateCalls.size() < 2) |
| return false; |
| |
| // RelocateInstMap is a mapping from the base relocate instruction to the |
| // corresponding derived relocate instructions |
| DenseMap<IntrinsicInst *, SmallVector<IntrinsicInst *, 2>> RelocateInstMap; |
| computeBaseDerivedRelocateMap(AllRelocateCalls, RelocateInstMap); |
| if (RelocateInstMap.empty()) |
| return false; |
| |
| for (auto &Item : RelocateInstMap) |
| // Item.first is the RelocatedBase to offset against |
| // Item.second is the vector of Targets to replace |
| MadeChange = simplifyRelocatesOffABase(Item.first, Item.second); |
| return MadeChange; |
| } |
| |
| /// SinkCast - Sink the specified cast instruction into its user blocks |
| static bool SinkCast(CastInst *CI) { |
| BasicBlock *DefBB = CI->getParent(); |
| |
| /// InsertedCasts - Only insert a cast in each block once. |
| DenseMap<BasicBlock*, CastInst*> InsertedCasts; |
| |
| bool MadeChange = false; |
| for (Value::user_iterator UI = CI->user_begin(), E = CI->user_end(); |
| UI != E; ) { |
| Use &TheUse = UI.getUse(); |
| Instruction *User = cast<Instruction>(*UI); |
| |
| // Figure out which BB this cast is used in. For PHI's this is the |
| // appropriate predecessor block. |
| BasicBlock *UserBB = User->getParent(); |
| if (PHINode *PN = dyn_cast<PHINode>(User)) { |
| UserBB = PN->getIncomingBlock(TheUse); |
| } |
| |
| // Preincrement use iterator so we don't invalidate it. |
| ++UI; |
| |
| // If this user is in the same block as the cast, don't change the cast. |
| if (UserBB == DefBB) continue; |
| |
| // If we have already inserted a cast into this block, use it. |
| CastInst *&InsertedCast = InsertedCasts[UserBB]; |
| |
| if (!InsertedCast) { |
| BasicBlock::iterator InsertPt = UserBB->getFirstInsertionPt(); |
| InsertedCast = |
| CastInst::Create(CI->getOpcode(), CI->getOperand(0), CI->getType(), "", |
| InsertPt); |
| } |
| |
| // Replace a use of the cast with a use of the new cast. |
| TheUse = InsertedCast; |
| MadeChange = true; |
| ++NumCastUses; |
| } |
| |
| // If we removed all uses, nuke the cast. |
| if (CI->use_empty()) { |
| CI->eraseFromParent(); |
| MadeChange = true; |
| } |
| |
| return MadeChange; |
| } |
| |
| /// OptimizeNoopCopyExpression - If the specified cast instruction is a noop |
| /// copy (e.g. it's casting from one pointer type to another, i32->i8 on PPC), |
| /// sink it into user blocks to reduce the number of virtual |
| /// registers that must be created and coalesced. |
| /// |
| /// Return true if any changes are made. |
| /// |
| static bool OptimizeNoopCopyExpression(CastInst *CI, const TargetLowering &TLI, |
| const DataLayout &DL) { |
| // If this is a noop copy, |
| EVT SrcVT = TLI.getValueType(DL, CI->getOperand(0)->getType()); |
| EVT DstVT = TLI.getValueType(DL, CI->getType()); |
| |
| // This is an fp<->int conversion? |
| if (SrcVT.isInteger() != DstVT.isInteger()) |
| return false; |
| |
| // If this is an extension, it will be a zero or sign extension, which |
| // isn't a noop. |
| if (SrcVT.bitsLT(DstVT)) return false; |
| |
| // If these values will be promoted, find out what they will be promoted |
| // to. This helps us consider truncates on PPC as noop copies when they |
| // are. |
| if (TLI.getTypeAction(CI->getContext(), SrcVT) == |
| TargetLowering::TypePromoteInteger) |
| SrcVT = TLI.getTypeToTransformTo(CI->getContext(), SrcVT); |
| if (TLI.getTypeAction(CI->getContext(), DstVT) == |
| TargetLowering::TypePromoteInteger) |
| DstVT = TLI.getTypeToTransformTo(CI->getContext(), DstVT); |
| |
| // If, after promotion, these are the same types, this is a noop copy. |
| if (SrcVT != DstVT) |
| return false; |
| |
| return SinkCast(CI); |
| } |
| |
| /// CombineUAddWithOverflow - try to combine CI into a call to the |
| /// llvm.uadd.with.overflow intrinsic if possible. |
| /// |
| /// Return true if any changes were made. |
| static bool CombineUAddWithOverflow(CmpInst *CI) { |
| Value *A, *B; |
| Instruction *AddI; |
| if (!match(CI, |
| m_UAddWithOverflow(m_Value(A), m_Value(B), m_Instruction(AddI)))) |
| return false; |
| |
| Type *Ty = AddI->getType(); |
| if (!isa<IntegerType>(Ty)) |
| return false; |
| |
| // We don't want to move around uses of condition values this late, so we we |
| // check if it is legal to create the call to the intrinsic in the basic |
| // block containing the icmp: |
| |
| if (AddI->getParent() != CI->getParent() && !AddI->hasOneUse()) |
| return false; |
| |
| #ifndef NDEBUG |
| // Someday m_UAddWithOverflow may get smarter, but this is a safe assumption |
| // for now: |
| if (AddI->hasOneUse()) |
| assert(*AddI->user_begin() == CI && "expected!"); |
| #endif |
| |
| Module *M = CI->getParent()->getParent()->getParent(); |
| Value *F = Intrinsic::getDeclaration(M, Intrinsic::uadd_with_overflow, Ty); |
| |
| auto *InsertPt = AddI->hasOneUse() ? CI : AddI; |
| |
| auto *UAddWithOverflow = |
| CallInst::Create(F, {A, B}, "uadd.overflow", InsertPt); |
| auto *UAdd = ExtractValueInst::Create(UAddWithOverflow, 0, "uadd", InsertPt); |
| auto *Overflow = |
| ExtractValueInst::Create(UAddWithOverflow, 1, "overflow", InsertPt); |
| |
| CI->replaceAllUsesWith(Overflow); |
| AddI->replaceAllUsesWith(UAdd); |
| CI->eraseFromParent(); |
| AddI->eraseFromParent(); |
| return true; |
| } |
| |
| /// SinkCmpExpression - Sink the given CmpInst into user blocks to reduce |
| /// the number of virtual registers that must be created and coalesced. This is |
| /// a clear win except on targets with multiple condition code registers |
| /// (PowerPC), where it might lose; some adjustment may be wanted there. |
| /// |
| /// Return true if any changes are made. |
| static bool SinkCmpExpression(CmpInst *CI) { |
| BasicBlock *DefBB = CI->getParent(); |
| |
| /// InsertedCmp - Only insert a cmp in each block once. |
| DenseMap<BasicBlock*, CmpInst*> InsertedCmps; |
| |
| bool MadeChange = false; |
| for (Value::user_iterator UI = CI->user_begin(), E = CI->user_end(); |
| UI != E; ) { |
| Use &TheUse = UI.getUse(); |
| Instruction *User = cast<Instruction>(*UI); |
| |
| // Preincrement use iterator so we don't invalidate it. |
| ++UI; |
| |
| // Don't bother for PHI nodes. |
| if (isa<PHINode>(User)) |
| continue; |
| |
| // Figure out which BB this cmp is used in. |
| BasicBlock *UserBB = User->getParent(); |
| |
| // If this user is in the same block as the cmp, don't change the cmp. |
| if (UserBB == DefBB) continue; |
| |
| // If we have already inserted a cmp into this block, use it. |
| CmpInst *&InsertedCmp = InsertedCmps[UserBB]; |
| |
| if (!InsertedCmp) { |
| BasicBlock::iterator InsertPt = UserBB->getFirstInsertionPt(); |
| InsertedCmp = |
| CmpInst::Create(CI->getOpcode(), |
| CI->getPredicate(), CI->getOperand(0), |
| CI->getOperand(1), "", InsertPt); |
| } |
| |
| // Replace a use of the cmp with a use of the new cmp. |
| TheUse = InsertedCmp; |
| MadeChange = true; |
| ++NumCmpUses; |
| } |
| |
| // If we removed all uses, nuke the cmp. |
| if (CI->use_empty()) { |
| CI->eraseFromParent(); |
| MadeChange = true; |
| } |
| |
| return MadeChange; |
| } |
| |
| static bool OptimizeCmpExpression(CmpInst *CI) { |
| if (SinkCmpExpression(CI)) |
| return true; |
| |
| if (CombineUAddWithOverflow(CI)) |
| return true; |
| |
| return false; |
| } |
| |
| /// isExtractBitsCandidateUse - Check if the candidates could |
| /// be combined with shift instruction, which includes: |
| /// 1. Truncate instruction |
| /// 2. And instruction and the imm is a mask of the low bits: |
| /// imm & (imm+1) == 0 |
| static bool isExtractBitsCandidateUse(Instruction *User) { |
| if (!isa<TruncInst>(User)) { |
| if (User->getOpcode() != Instruction::And || |
| !isa<ConstantInt>(User->getOperand(1))) |
| return false; |
| |
| const APInt &Cimm = cast<ConstantInt>(User->getOperand(1))->getValue(); |
| |
| if ((Cimm & (Cimm + 1)).getBoolValue()) |
| return false; |
| } |
| return true; |
| } |
| |
| /// SinkShiftAndTruncate - sink both shift and truncate instruction |
| /// to the use of truncate's BB. |
| static bool |
| SinkShiftAndTruncate(BinaryOperator *ShiftI, Instruction *User, ConstantInt *CI, |
| DenseMap<BasicBlock *, BinaryOperator *> &InsertedShifts, |
| const TargetLowering &TLI, const DataLayout &DL) { |
| BasicBlock *UserBB = User->getParent(); |
| DenseMap<BasicBlock *, CastInst *> InsertedTruncs; |
| TruncInst *TruncI = dyn_cast<TruncInst>(User); |
| bool MadeChange = false; |
| |
| for (Value::user_iterator TruncUI = TruncI->user_begin(), |
| TruncE = TruncI->user_end(); |
| TruncUI != TruncE;) { |
| |
| Use &TruncTheUse = TruncUI.getUse(); |
| Instruction *TruncUser = cast<Instruction>(*TruncUI); |
| // Preincrement use iterator so we don't invalidate it. |
| |
| ++TruncUI; |
| |
| int ISDOpcode = TLI.InstructionOpcodeToISD(TruncUser->getOpcode()); |
| if (!ISDOpcode) |
| continue; |
| |
| // If the use is actually a legal node, there will not be an |
| // implicit truncate. |
| // FIXME: always querying the result type is just an |
| // approximation; some nodes' legality is determined by the |
| // operand or other means. There's no good way to find out though. |
| if (TLI.isOperationLegalOrCustom( |
| ISDOpcode, TLI.getValueType(DL, TruncUser->getType(), true))) |
| continue; |
| |
| // Don't bother for PHI nodes. |
| if (isa<PHINode>(TruncUser)) |
| continue; |
| |
| BasicBlock *TruncUserBB = TruncUser->getParent(); |
| |
| if (UserBB == TruncUserBB) |
| continue; |
| |
| BinaryOperator *&InsertedShift = InsertedShifts[TruncUserBB]; |
| CastInst *&InsertedTrunc = InsertedTruncs[TruncUserBB]; |
| |
| if (!InsertedShift && !InsertedTrunc) { |
| BasicBlock::iterator InsertPt = TruncUserBB->getFirstInsertionPt(); |
| // Sink the shift |
| if (ShiftI->getOpcode() == Instruction::AShr) |
| InsertedShift = |
| BinaryOperator::CreateAShr(ShiftI->getOperand(0), CI, "", InsertPt); |
| else |
| InsertedShift = |
| BinaryOperator::CreateLShr(ShiftI->getOperand(0), CI, "", InsertPt); |
| |
| // Sink the trunc |
| BasicBlock::iterator TruncInsertPt = TruncUserBB->getFirstInsertionPt(); |
| TruncInsertPt++; |
| |
| InsertedTrunc = CastInst::Create(TruncI->getOpcode(), InsertedShift, |
| TruncI->getType(), "", TruncInsertPt); |
| |
| MadeChange = true; |
| |
| TruncTheUse = InsertedTrunc; |
| } |
| } |
| return MadeChange; |
| } |
| |
| /// OptimizeExtractBits - sink the shift *right* instruction into user blocks if |
| /// the uses could potentially be combined with this shift instruction and |
| /// generate BitExtract instruction. It will only be applied if the architecture |
| /// supports BitExtract instruction. Here is an example: |
| /// BB1: |
| /// %x.extract.shift = lshr i64 %arg1, 32 |
| /// BB2: |
| /// %x.extract.trunc = trunc i64 %x.extract.shift to i16 |
| /// ==> |
| /// |
| /// BB2: |
| /// %x.extract.shift.1 = lshr i64 %arg1, 32 |
| /// %x.extract.trunc = trunc i64 %x.extract.shift.1 to i16 |
| /// |
| /// CodeGen will recoginze the pattern in BB2 and generate BitExtract |
| /// instruction. |
| /// Return true if any changes are made. |
| static bool OptimizeExtractBits(BinaryOperator *ShiftI, ConstantInt *CI, |
| const TargetLowering &TLI, |
| const DataLayout &DL) { |
| BasicBlock *DefBB = ShiftI->getParent(); |
| |
| /// Only insert instructions in each block once. |
| DenseMap<BasicBlock *, BinaryOperator *> InsertedShifts; |
| |
| bool shiftIsLegal = TLI.isTypeLegal(TLI.getValueType(DL, ShiftI->getType())); |
| |
| bool MadeChange = false; |
| for (Value::user_iterator UI = ShiftI->user_begin(), E = ShiftI->user_end(); |
| UI != E;) { |
| Use &TheUse = UI.getUse(); |
| Instruction *User = cast<Instruction>(*UI); |
| // Preincrement use iterator so we don't invalidate it. |
| ++UI; |
| |
| // Don't bother for PHI nodes. |
| if (isa<PHINode>(User)) |
| continue; |
| |
| if (!isExtractBitsCandidateUse(User)) |
| continue; |
| |
| BasicBlock *UserBB = User->getParent(); |
| |
| if (UserBB == DefBB) { |
| // If the shift and truncate instruction are in the same BB. The use of |
| // the truncate(TruncUse) may still introduce another truncate if not |
| // legal. In this case, we would like to sink both shift and truncate |
| // instruction to the BB of TruncUse. |
| // for example: |
| // BB1: |
| // i64 shift.result = lshr i64 opnd, imm |
| // trunc.result = trunc shift.result to i16 |
| // |
| // BB2: |
| // ----> We will have an implicit truncate here if the architecture does |
| // not have i16 compare. |
| // cmp i16 trunc.result, opnd2 |
| // |
| if (isa<TruncInst>(User) && shiftIsLegal |
| // If the type of the truncate is legal, no trucate will be |
| // introduced in other basic blocks. |
| && |
| (!TLI.isTypeLegal(TLI.getValueType(DL, User->getType())))) |
| MadeChange = |
| SinkShiftAndTruncate(ShiftI, User, CI, InsertedShifts, TLI, DL); |
| |
| continue; |
| } |
| // If we have already inserted a shift into this block, use it. |
| BinaryOperator *&InsertedShift = InsertedShifts[UserBB]; |
| |
| if (!InsertedShift) { |
| BasicBlock::iterator InsertPt = UserBB->getFirstInsertionPt(); |
| |
| if (ShiftI->getOpcode() == Instruction::AShr) |
| InsertedShift = |
| BinaryOperator::CreateAShr(ShiftI->getOperand(0), CI, "", InsertPt); |
| else |
| InsertedShift = |
| BinaryOperator::CreateLShr(ShiftI->getOperand(0), CI, "", InsertPt); |
| |
| MadeChange = true; |
| } |
| |
| // Replace a use of the shift with a use of the new shift. |
| TheUse = InsertedShift; |
| } |
| |
| // If we removed all uses, nuke the shift. |
| if (ShiftI->use_empty()) |
| ShiftI->eraseFromParent(); |
| |
| return MadeChange; |
| } |
| |
| // ScalarizeMaskedLoad() translates masked load intrinsic, like |
| // <16 x i32 > @llvm.masked.load( <16 x i32>* %addr, i32 align, |
| // <16 x i1> %mask, <16 x i32> %passthru) |
| // to a chain of basic blocks, whith loading element one-by-one if |
| // the appropriate mask bit is set |
| // |
| // %1 = bitcast i8* %addr to i32* |
| // %2 = extractelement <16 x i1> %mask, i32 0 |
| // %3 = icmp eq i1 %2, true |
| // br i1 %3, label %cond.load, label %else |
| // |
| //cond.load: ; preds = %0 |
| // %4 = getelementptr i32* %1, i32 0 |
| // %5 = load i32* %4 |
| // %6 = insertelement <16 x i32> undef, i32 %5, i32 0 |
| // br label %else |
| // |
| //else: ; preds = %0, %cond.load |
| // %res.phi.else = phi <16 x i32> [ %6, %cond.load ], [ undef, %0 ] |
| // %7 = extractelement <16 x i1> %mask, i32 1 |
| // %8 = icmp eq i1 %7, true |
| // br i1 %8, label %cond.load1, label %else2 |
| // |
| //cond.load1: ; preds = %else |
| // %9 = getelementptr i32* %1, i32 1 |
| // %10 = load i32* %9 |
| // %11 = insertelement <16 x i32> %res.phi.else, i32 %10, i32 1 |
| // br label %else2 |
| // |
| //else2: ; preds = %else, %cond.load1 |
| // %res.phi.else3 = phi <16 x i32> [ %11, %cond.load1 ], [ %res.phi.else, %else ] |
| // %12 = extractelement <16 x i1> %mask, i32 2 |
| // %13 = icmp eq i1 %12, true |
| // br i1 %13, label %cond.load4, label %else5 |
| // |
| static void ScalarizeMaskedLoad(CallInst *CI) { |
| Value *Ptr = CI->getArgOperand(0); |
| Value *Src0 = CI->getArgOperand(3); |
| Value *Mask = CI->getArgOperand(2); |
| VectorType *VecType = dyn_cast<VectorType>(CI->getType()); |
| Type *EltTy = VecType->getElementType(); |
| |
| assert(VecType && "Unexpected return type of masked load intrinsic"); |
| |
| IRBuilder<> Builder(CI->getContext()); |
| Instruction *InsertPt = CI; |
| BasicBlock *IfBlock = CI->getParent(); |
| BasicBlock *CondBlock = nullptr; |
| BasicBlock *PrevIfBlock = CI->getParent(); |
| Builder.SetInsertPoint(InsertPt); |
| |
| Builder.SetCurrentDebugLocation(CI->getDebugLoc()); |
| |
| // Bitcast %addr fron i8* to EltTy* |
| Type *NewPtrType = |
| EltTy->getPointerTo(cast<PointerType>(Ptr->getType())->getAddressSpace()); |
| Value *FirstEltPtr = Builder.CreateBitCast(Ptr, NewPtrType); |
| Value *UndefVal = UndefValue::get(VecType); |
| |
| // The result vector |
| Value *VResult = UndefVal; |
| |
| PHINode *Phi = nullptr; |
| Value *PrevPhi = UndefVal; |
| |
| unsigned VectorWidth = VecType->getNumElements(); |
| for (unsigned Idx = 0; Idx < VectorWidth; ++Idx) { |
| |
| // Fill the "else" block, created in the previous iteration |
| // |
| // %res.phi.else3 = phi <16 x i32> [ %11, %cond.load1 ], [ %res.phi.else, %else ] |
| // %mask_1 = extractelement <16 x i1> %mask, i32 Idx |
| // %to_load = icmp eq i1 %mask_1, true |
| // br i1 %to_load, label %cond.load, label %else |
| // |
| if (Idx > 0) { |
| Phi = Builder.CreatePHI(VecType, 2, "res.phi.else"); |
| Phi->addIncoming(VResult, CondBlock); |
| Phi->addIncoming(PrevPhi, PrevIfBlock); |
| PrevPhi = Phi; |
| VResult = Phi; |
| } |
| |
| Value *Predicate = Builder.CreateExtractElement(Mask, Builder.getInt32(Idx)); |
| Value *Cmp = Builder.CreateICmp(ICmpInst::ICMP_EQ, Predicate, |
| ConstantInt::get(Predicate->getType(), 1)); |
| |
| // Create "cond" block |
| // |
| // %EltAddr = getelementptr i32* %1, i32 0 |
| // %Elt = load i32* %EltAddr |
| // VResult = insertelement <16 x i32> VResult, i32 %Elt, i32 Idx |
| // |
| CondBlock = IfBlock->splitBasicBlock(InsertPt, "cond.load"); |
| Builder.SetInsertPoint(InsertPt); |
| |
| Value *Gep = |
| Builder.CreateInBoundsGEP(EltTy, FirstEltPtr, Builder.getInt32(Idx)); |
| LoadInst* Load = Builder.CreateLoad(Gep, false); |
| VResult = Builder.CreateInsertElement(VResult, Load, Builder.getInt32(Idx)); |
| |
| // Create "else" block, fill it in the next iteration |
| BasicBlock *NewIfBlock = CondBlock->splitBasicBlock(InsertPt, "else"); |
| Builder.SetInsertPoint(InsertPt); |
| Instruction *OldBr = IfBlock->getTerminator(); |
| BranchInst::Create(CondBlock, NewIfBlock, Cmp, OldBr); |
| OldBr->eraseFromParent(); |
| PrevIfBlock = IfBlock; |
| IfBlock = NewIfBlock; |
| } |
| |
| Phi = Builder.CreatePHI(VecType, 2, "res.phi.select"); |
| Phi->addIncoming(VResult, CondBlock); |
| Phi->addIncoming(PrevPhi, PrevIfBlock); |
| Value *NewI = Builder.CreateSelect(Mask, Phi, Src0); |
| CI->replaceAllUsesWith(NewI); |
| CI->eraseFromParent(); |
| } |
| |
| // ScalarizeMaskedStore() translates masked store intrinsic, like |
| // void @llvm.masked.store(<16 x i32> %src, <16 x i32>* %addr, i32 align, |
| // <16 x i1> %mask) |
| // to a chain of basic blocks, that stores element one-by-one if |
| // the appropriate mask bit is set |
| // |
| // %1 = bitcast i8* %addr to i32* |
| // %2 = extractelement <16 x i1> %mask, i32 0 |
| // %3 = icmp eq i1 %2, true |
| // br i1 %3, label %cond.store, label %else |
| // |
| // cond.store: ; preds = %0 |
| // %4 = extractelement <16 x i32> %val, i32 0 |
| // %5 = getelementptr i32* %1, i32 0 |
| // store i32 %4, i32* %5 |
| // br label %else |
| // |
| // else: ; preds = %0, %cond.store |
| // %6 = extractelement <16 x i1> %mask, i32 1 |
| // %7 = icmp eq i1 %6, true |
| // br i1 %7, label %cond.store1, label %else2 |
| // |
| // cond.store1: ; preds = %else |
| // %8 = extractelement <16 x i32> %val, i32 1 |
| // %9 = getelementptr i32* %1, i32 1 |
| // store i32 %8, i32* %9 |
| // br label %else2 |
| // . . . |
| static void ScalarizeMaskedStore(CallInst *CI) { |
| Value *Ptr = CI->getArgOperand(1); |
| Value *Src = CI->getArgOperand(0); |
| Value *Mask = CI->getArgOperand(3); |
| |
| VectorType *VecType = dyn_cast<VectorType>(Src->getType()); |
| Type *EltTy = VecType->getElementType(); |
| |
| assert(VecType && "Unexpected data type in masked store intrinsic"); |
| |
| IRBuilder<> Builder(CI->getContext()); |
| Instruction *InsertPt = CI; |
| BasicBlock *IfBlock = CI->getParent(); |
| Builder.SetInsertPoint(InsertPt); |
| Builder.SetCurrentDebugLocation(CI->getDebugLoc()); |
| |
| // Bitcast %addr fron i8* to EltTy* |
| Type *NewPtrType = |
| EltTy->getPointerTo(cast<PointerType>(Ptr->getType())->getAddressSpace()); |
| Value *FirstEltPtr = Builder.CreateBitCast(Ptr, NewPtrType); |
| |
| unsigned VectorWidth = VecType->getNumElements(); |
| for (unsigned Idx = 0; Idx < VectorWidth; ++Idx) { |
| |
| // Fill the "else" block, created in the previous iteration |
| // |
| // %mask_1 = extractelement <16 x i1> %mask, i32 Idx |
| // %to_store = icmp eq i1 %mask_1, true |
| // br i1 %to_load, label %cond.store, label %else |
| // |
| Value *Predicate = Builder.CreateExtractElement(Mask, Builder.getInt32(Idx)); |
| Value *Cmp = Builder.CreateICmp(ICmpInst::ICMP_EQ, Predicate, |
| ConstantInt::get(Predicate->getType(), 1)); |
| |
| // Create "cond" block |
| // |
| // %OneElt = extractelement <16 x i32> %Src, i32 Idx |
| // %EltAddr = getelementptr i32* %1, i32 0 |
| // %store i32 %OneElt, i32* %EltAddr |
| // |
| BasicBlock *CondBlock = IfBlock->splitBasicBlock(InsertPt, "cond.store"); |
| Builder.SetInsertPoint(InsertPt); |
| |
| Value *OneElt = Builder.CreateExtractElement(Src, Builder.getInt32(Idx)); |
| Value *Gep = |
| Builder.CreateInBoundsGEP(EltTy, FirstEltPtr, Builder.getInt32(Idx)); |
| Builder.CreateStore(OneElt, Gep); |
| |
| // Create "else" block, fill it in the next iteration |
| BasicBlock *NewIfBlock = CondBlock->splitBasicBlock(InsertPt, "else"); |
| Builder.SetInsertPoint(InsertPt); |
| Instruction *OldBr = IfBlock->getTerminator(); |
| BranchInst::Create(CondBlock, NewIfBlock, Cmp, OldBr); |
| OldBr->eraseFromParent(); |
| IfBlock = NewIfBlock; |
| } |
| CI->eraseFromParent(); |
| } |
| |
| bool CodeGenPrepare::OptimizeCallInst(CallInst *CI, bool& ModifiedDT) { |
| BasicBlock *BB = CI->getParent(); |
| |
| // Lower inline assembly if we can. |
| // If we found an inline asm expession, and if the target knows how to |
| // lower it to normal LLVM code, do so now. |
| if (TLI && isa<InlineAsm>(CI->getCalledValue())) { |
| if (TLI->ExpandInlineAsm(CI)) { |
| // Avoid invalidating the iterator. |
| CurInstIterator = BB->begin(); |
| // Avoid processing instructions out of order, which could cause |
| // reuse before a value is defined. |
| SunkAddrs.clear(); |
| return true; |
| } |
| // Sink address computing for memory operands into the block. |
| if (OptimizeInlineAsmInst(CI)) |
| return true; |
| } |
| |
| // Align the pointer arguments to this call if the target thinks it's a good |
| // idea |
| unsigned MinSize, PrefAlign; |
| if (TLI && TLI->shouldAlignPointerArgs(CI, MinSize, PrefAlign)) { |
| for (auto &Arg : CI->arg_operands()) { |
| // We want to align both objects whose address is used directly and |
| // objects whose address is used in casts and GEPs, though it only makes |
| // sense for GEPs if the offset is a multiple of the desired alignment and |
| // if size - offset meets the size threshold. |
| if (!Arg->getType()->isPointerTy()) |
| continue; |
| APInt Offset(DL->getPointerSizeInBits( |
| cast<PointerType>(Arg->getType())->getAddressSpace()), |
| 0); |
| Value *Val = Arg->stripAndAccumulateInBoundsConstantOffsets(*DL, Offset); |
| uint64_t Offset2 = Offset.getLimitedValue(); |
| if ((Offset2 & (PrefAlign-1)) != 0) |
| continue; |
| AllocaInst *AI; |
| if ((AI = dyn_cast<AllocaInst>(Val)) && AI->getAlignment() < PrefAlign && |
| DL->getTypeAllocSize(AI->getAllocatedType()) >= MinSize + Offset2) |
| AI->setAlignment(PrefAlign); |
| // Global variables can only be aligned if they are defined in this |
| // object (i.e. they are uniquely initialized in this object), and |
| // over-aligning global variables that have an explicit section is |
| // forbidden. |
| GlobalVariable *GV; |
| if ((GV = dyn_cast<GlobalVariable>(Val)) && GV->hasUniqueInitializer() && |
| !GV->hasSection() && GV->getAlignment() < PrefAlign && |
| DL->getTypeAllocSize(GV->getType()->getElementType()) >= |
| MinSize + Offset2) |
| GV->setAlignment(PrefAlign); |
| } |
| // If this is a memcpy (or similar) then we may be able to improve the |
| // alignment |
| if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(CI)) { |
| unsigned Align = getKnownAlignment(MI->getDest(), *DL); |
| if (MemTransferInst *MTI = dyn_cast<MemTransferInst>(MI)) |
| Align = std::min(Align, getKnownAlignment(MTI->getSource(), *DL)); |
| if (Align > MI->getAlignment()) |
| MI->setAlignment(ConstantInt::get(MI->getAlignmentType(), Align)); |
| } |
| } |
| |
| IntrinsicInst *II = dyn_cast<IntrinsicInst>(CI); |
| if (II) { |
| switch (II->getIntrinsicID()) { |
| default: break; |
| case Intrinsic::objectsize: { |
| // Lower all uses of llvm.objectsize.* |
| bool Min = (cast<ConstantInt>(II->getArgOperand(1))->getZExtValue() == 1); |
| Type *ReturnTy = CI->getType(); |
| Constant *RetVal = ConstantInt::get(ReturnTy, Min ? 0 : -1ULL); |
| |
| // Substituting this can cause recursive simplifications, which can |
| // invalidate our iterator. Use a WeakVH to hold onto it in case this |
| // happens. |
| WeakVH IterHandle(CurInstIterator); |
| |
| replaceAndRecursivelySimplify(CI, RetVal, |
| TLInfo, nullptr); |
| |
| // If the iterator instruction was recursively deleted, start over at the |
| // start of the block. |
| if (IterHandle != CurInstIterator) { |
| CurInstIterator = BB->begin(); |
| SunkAddrs.clear(); |
| } |
| return true; |
| } |
| case Intrinsic::masked_load: { |
| // Scalarize unsupported vector masked load |
| if (!TTI->isLegalMaskedLoad(CI->getType(), 1)) { |
| ScalarizeMaskedLoad(CI); |
| ModifiedDT = true; |
| return true; |
| } |
| return false; |
| } |
| case Intrinsic::masked_store: { |
| if (!TTI->isLegalMaskedStore(CI->getArgOperand(0)->getType(), 1)) { |
| ScalarizeMaskedStore(CI); |
| ModifiedDT = true; |
| return true; |
| } |
| return false; |
| } |
| case Intrinsic::aarch64_stlxr: |
| case Intrinsic::aarch64_stxr: { |
| ZExtInst *ExtVal = dyn_cast<ZExtInst>(CI->getArgOperand(0)); |
| if (!ExtVal || !ExtVal->hasOneUse() || |
| ExtVal->getParent() == CI->getParent()) |
| return false; |
| // Sink a zext feeding stlxr/stxr before it, so it can be folded into it. |
| ExtVal->moveBefore(CI); |
| // Mark this instruction as "inserted by CGP", so that other |
| // optimizations don't touch it. |
| InsertedInsts.insert(ExtVal); |
| return true; |
| } |
| } |
| |
| if (TLI) { |
| // Unknown address space. |
| // TODO: Target hook to pick which address space the intrinsic cares |
| // about? |
| unsigned AddrSpace = ~0u; |
| SmallVector<Value*, 2> PtrOps; |
| Type *AccessTy; |
| if (TLI->GetAddrModeArguments(II, PtrOps, AccessTy, AddrSpace)) |
| while (!PtrOps.empty()) |
| if (OptimizeMemoryInst(II, PtrOps.pop_back_val(), AccessTy, AddrSpace)) |
| return true; |
| } |
| } |
| |
| // From here on out we're working with named functions. |
| if (!CI->getCalledFunction()) return false; |
| |
| // Lower all default uses of _chk calls. This is very similar |
| // to what InstCombineCalls does, but here we are only lowering calls |
| // to fortified library functions (e.g. __memcpy_chk) that have the default |
| // "don't know" as the objectsize. Anything else should be left alone. |
| FortifiedLibCallSimplifier Simplifier(TLInfo, true); |
| if (Value *V = Simplifier.optimizeCall(CI)) { |
| CI->replaceAllUsesWith(V); |
| CI->eraseFromParent(); |
| return true; |
| } |
| return false; |
| } |
| |
| /// DupRetToEnableTailCallOpts - Look for opportunities to duplicate return |
| /// instructions to the predecessor to enable tail call optimizations. The |
| /// case it is currently looking for is: |
| /// @code |
| /// bb0: |
| /// %tmp0 = tail call i32 @f0() |
| /// br label %return |
| /// bb1: |
| /// %tmp1 = tail call i32 @f1() |
| /// br label %return |
| /// bb2: |
| /// %tmp2 = tail call i32 @f2() |
| /// br label %return |
| /// return: |
| /// %retval = phi i32 [ %tmp0, %bb0 ], [ %tmp1, %bb1 ], [ %tmp2, %bb2 ] |
| /// ret i32 %retval |
| /// @endcode |
| /// |
| /// => |
| /// |
| /// @code |
| /// bb0: |
| /// %tmp0 = tail call i32 @f0() |
| /// ret i32 %tmp0 |
| /// bb1: |
| /// %tmp1 = tail call i32 @f1() |
| /// ret i32 %tmp1 |
| /// bb2: |
| /// %tmp2 = tail call i32 @f2() |
| /// ret i32 %tmp2 |
| /// @endcode |
| bool CodeGenPrepare::DupRetToEnableTailCallOpts(BasicBlock *BB) { |
| if (!TLI) |
| return false; |
| |
| ReturnInst *RI = dyn_cast<ReturnInst>(BB->getTerminator()); |
| if (!RI) |
| return false; |
| |
| PHINode *PN = nullptr; |
| BitCastInst *BCI = nullptr; |
| Value *V = RI->getReturnValue(); |
| if (V) { |
| BCI = dyn_cast<BitCastInst>(V); |
| if (BCI) |
| V = BCI->getOperand(0); |
| |
| PN = dyn_cast<PHINode>(V); |
| if (!PN) |
| return false; |
| } |
| |
| if (PN && PN->getParent() != BB) |
| return false; |
| |
| // It's not safe to eliminate the sign / zero extension of the return value. |
| // See llvm::isInTailCallPosition(). |
| const Function *F = BB->getParent(); |
| AttributeSet CallerAttrs = F->getAttributes(); |
| if (CallerAttrs.hasAttribute(AttributeSet::ReturnIndex, Attribute::ZExt) || |
| CallerAttrs.hasAttribute(AttributeSet::ReturnIndex, Attribute::SExt)) |
| return false; |
| |
| // Make sure there are no instructions between the PHI and return, or that the |
| // return is the first instruction in the block. |
| if (PN) { |
| BasicBlock::iterator BI = BB->begin(); |
| do { ++BI; } while (isa<DbgInfoIntrinsic>(BI)); |
| if (&*BI == BCI) |
| // Also skip over the bitcast. |
| ++BI; |
| if (&*BI != RI) |
| return false; |
| } else { |
| BasicBlock::iterator BI = BB->begin(); |
| while (isa<DbgInfoIntrinsic>(BI)) ++BI; |
| if (&*BI != RI) |
| return false; |
| } |
| |
| /// Only dup the ReturnInst if the CallInst is likely to be emitted as a tail |
| /// call. |
| SmallVector<CallInst*, 4> TailCalls; |
| if (PN) { |
| for (unsigned I = 0, E = PN->getNumIncomingValues(); I != E; ++I) { |
| CallInst *CI = dyn_cast<CallInst>(PN->getIncomingValue(I)); |
| // Make sure the phi value is indeed produced by the tail call. |
| if (CI && CI->hasOneUse() && CI->getParent() == PN->getIncomingBlock(I) && |
| TLI->mayBeEmittedAsTailCall(CI)) |
| TailCalls.push_back(CI); |
| } |
| } else { |
| SmallPtrSet<BasicBlock*, 4> VisitedBBs; |
| for (pred_iterator PI = pred_begin(BB), PE = pred_end(BB); PI != PE; ++PI) { |
| if (!VisitedBBs.insert(*PI).second) |
| continue; |
| |
| BasicBlock::InstListType &InstList = (*PI)->getInstList(); |
| BasicBlock::InstListType::reverse_iterator RI = InstList.rbegin(); |
| BasicBlock::InstListType::reverse_iterator RE = InstList.rend(); |
| do { ++RI; } while (RI != RE && isa<DbgInfoIntrinsic>(&*RI)); |
| if (RI == RE) |
| continue; |
| |
| CallInst *CI = dyn_cast<CallInst>(&*RI); |
| if (CI && CI->use_empty() && TLI->mayBeEmittedAsTailCall(CI)) |
| TailCalls.push_back(CI); |
| } |
| } |
| |
| bool Changed = false; |
| for (unsigned i = 0, e = TailCalls.size(); i != e; ++i) { |
| CallInst *CI = TailCalls[i]; |
| CallSite CS(CI); |
| |
| // Conservatively require the attributes of the call to match those of the |
| // return. Ignore noalias because it doesn't affect the call sequence. |
| AttributeSet CalleeAttrs = CS.getAttributes(); |
| if (AttrBuilder(CalleeAttrs, AttributeSet::ReturnIndex). |
| removeAttribute(Attribute::NoAlias) != |
| AttrBuilder(CalleeAttrs, AttributeSet::ReturnIndex). |
| removeAttribute(Attribute::NoAlias)) |
| continue; |
| |
| // Make sure the call instruction is followed by an unconditional branch to |
| // the return block. |
| BasicBlock *CallBB = CI->getParent(); |
| BranchInst *BI = dyn_cast<BranchInst>(CallBB->getTerminator()); |
| if (!BI || !BI->isUnconditional() || BI->getSuccessor(0) != BB) |
| continue; |
| |
| // Duplicate the return into CallBB. |
| (void)FoldReturnIntoUncondBranch(RI, BB, CallBB); |
| ModifiedDT = Changed = true; |
| ++NumRetsDup; |
| } |
| |
| // If we eliminated all predecessors of the block, delete the block now. |
| if (Changed && !BB->hasAddressTaken() && pred_begin(BB) == pred_end(BB)) |
| BB->eraseFromParent(); |
| |
| return Changed; |
| } |
| |
| //===----------------------------------------------------------------------===// |
| // Memory Optimization |
| //===----------------------------------------------------------------------===// |
| |
| namespace { |
| |
| /// ExtAddrMode - This is an extended version of TargetLowering::AddrMode |
| /// which holds actual Value*'s for register values. |
| struct ExtAddrMode : public TargetLowering::AddrMode { |
| Value *BaseReg; |
| Value *ScaledReg; |
| ExtAddrMode() : BaseReg(nullptr), ScaledReg(nullptr) {} |
| void print(raw_ostream &OS) const; |
| void dump() const; |
| |
| bool operator==(const ExtAddrMode& O) const { |
| return (BaseReg == O.BaseReg) && (ScaledReg == O.ScaledReg) && |
| (BaseGV == O.BaseGV) && (BaseOffs == O.BaseOffs) && |
| (HasBaseReg == O.HasBaseReg) && (Scale == O.Scale); |
| } |
| }; |
| |
| #ifndef NDEBUG |
| static inline raw_ostream &operator<<(raw_ostream &OS, const ExtAddrMode &AM) { |
| AM.print(OS); |
| return OS; |
| } |
| #endif |
| |
| void ExtAddrMode::print(raw_ostream &OS) const { |
| bool NeedPlus = false; |
| OS << "["; |
| if (BaseGV) { |
| OS << (NeedPlus ? " + " : "") |
| << "GV:"; |
| BaseGV->printAsOperand(OS, /*PrintType=*/false); |
| NeedPlus = true; |
| } |
| |
| if (BaseOffs) { |
| OS << (NeedPlus ? " + " : "") |
| << BaseOffs; |
| NeedPlus = true; |
| } |
| |
| if (BaseReg) { |
| OS << (NeedPlus ? " + " : "") |
| << "Base:"; |
| BaseReg->printAsOperand(OS, /*PrintType=*/false); |
| NeedPlus = true; |
| } |
| if (Scale) { |
| OS << (NeedPlus ? " + " : "") |
| << Scale << "*"; |
| ScaledReg->printAsOperand(OS, /*PrintType=*/false); |
| } |
| |
| OS << ']'; |
| } |
| |
| #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) |
| void ExtAddrMode::dump() const { |
| print(dbgs()); |
| dbgs() << '\n'; |
| } |
| #endif |
| |
| /// \brief This class provides transaction based operation on the IR. |
| /// Every change made through this class is recorded in the internal state and |
| /// can be undone (rollback) until commit is called. |
| class TypePromotionTransaction { |
| |
| /// \brief This represents the common interface of the individual transaction. |
| /// Each class implements the logic for doing one specific modification on |
| /// the IR via the TypePromotionTransaction. |
| class TypePromotionAction { |
| protected: |
| /// The Instruction modified. |
| Instruction *Inst; |
| |
| public: |
| /// \brief Constructor of the action. |
| /// The constructor performs the related action on the IR. |
| TypePromotionAction(Instruction *Inst) : Inst(Inst) {} |
| |
| virtual ~TypePromotionAction() {} |
| |
| /// \brief Undo the modification done by this action. |
| /// When this method is called, the IR must be in the same state as it was |
| /// before this action was applied. |
| /// \pre Undoing the action works if and only if the IR is in the exact same |
| /// state as it was directly after this action was applied. |
| virtual void undo() = 0; |
| |
| /// \brief Advocate every change made by this action. |
| /// When the results on the IR of the action are to be kept, it is important |
| /// to call this function, otherwise hidden information may be kept forever. |
| virtual void commit() { |
| // Nothing to be done, this action is not doing anything. |
| } |
| }; |
| |
| /// \brief Utility to remember the position of an instruction. |
| class InsertionHandler { |
| /// Position of an instruction. |
| /// Either an instruction: |
| /// - Is the first in a basic block: BB is used. |
| /// - Has a previous instructon: PrevInst is used. |
| union { |
| Instruction *PrevInst; |
| BasicBlock *BB; |
| } Point; |
| /// Remember whether or not the instruction had a previous instruction. |
| bool HasPrevInstruction; |
| |
| public: |
| /// \brief Record the position of \p Inst. |
| InsertionHandler(Instruction *Inst) { |
| BasicBlock::iterator It = Inst; |
| HasPrevInstruction = (It != (Inst->getParent()->begin())); |
| if (HasPrevInstruction) |
| Point.PrevInst = --It; |
| else |
| Point.BB = Inst->getParent(); |
| } |
| |
| /// \brief Insert \p Inst at the recorded position. |
| void insert(Instruction *Inst) { |
| if (HasPrevInstruction) { |
| if (Inst->getParent()) |
| Inst->removeFromParent(); |
| Inst->insertAfter(Point.PrevInst); |
| } else { |
| Instruction *Position = Point.BB->getFirstInsertionPt(); |
| if (Inst->getParent()) |
| Inst->moveBefore(Position); |
| else |
| Inst->insertBefore(Position); |
| } |
| } |
| }; |
| |
| /// \brief Move an instruction before another. |
| class InstructionMoveBefore : public TypePromotionAction { |
| /// Original position of the instruction. |
| InsertionHandler Position; |
| |
| public: |
| /// \brief Move \p Inst before \p Before. |
| InstructionMoveBefore(Instruction *Inst, Instruction *Before) |
| : TypePromotionAction(Inst), Position(Inst) { |
| DEBUG(dbgs() << "Do: move: " << *Inst << "\nbefore: " << *Before << "\n"); |
| Inst->moveBefore(Before); |
| } |
| |
| /// \brief Move the instruction back to its original position. |
| void undo() override { |
| DEBUG(dbgs() << "Undo: moveBefore: " << *Inst << "\n"); |
| Position.insert(Inst); |
| } |
| }; |
| |
| /// \brief Set the operand of an instruction with a new value. |
| class OperandSetter : public TypePromotionAction { |
| /// Original operand of the instruction. |
| Value *Origin; |
| /// Index of the modified instruction. |
| unsigned Idx; |
| |
| public: |
| /// \brief Set \p Idx operand of \p Inst with \p NewVal. |
| OperandSetter(Instruction *Inst, unsigned Idx, Value *NewVal) |
| : TypePromotionAction(Inst), Idx(Idx) { |
| DEBUG(dbgs() << "Do: setOperand: " << Idx << "\n" |
| << "for:" << *Inst << "\n" |
| << "with:" << *NewVal << "\n"); |
| Origin = Inst->getOperand(Idx); |
| Inst->setOperand(Idx, NewVal); |
| } |
| |
| /// \brief Restore the original value of the instruction. |
| void undo() override { |
| DEBUG(dbgs() << "Undo: setOperand:" << Idx << "\n" |
| << "for: " << *Inst << "\n" |
| << "with: " << *Origin << "\n"); |
| Inst->setOperand(Idx, Origin); |
| } |
| }; |
| |
| /// \brief Hide the operands of an instruction. |
| /// Do as if this instruction was not using any of its operands. |
| class OperandsHider : public TypePromotionAction { |
| /// The list of original operands. |
| SmallVector<Value *, 4> OriginalValues; |
| |
| public: |
| /// \brief Remove \p Inst from the uses of the operands of \p Inst. |
| OperandsHider(Instruction *Inst) : TypePromotionAction(Inst) { |
| DEBUG(dbgs() << "Do: OperandsHider: " << *Inst << "\n"); |
| unsigned NumOpnds = Inst->getNumOperands(); |
| OriginalValues.reserve(NumOpnds); |
| for (unsigned It = 0; It < NumOpnds; ++It) { |
| // Save the current operand. |
| Value *Val = Inst->getOperand(It); |
| OriginalValues.push_back(Val); |
| // Set a dummy one. |
| // We could use OperandSetter here, but that would implied an overhead |
| // that we are not willing to pay. |
| Inst->setOperand(It, UndefValue::get(Val->getType())); |
| } |
| } |
| |
| /// \brief Restore the original list of uses. |
| void undo() override { |
| DEBUG(dbgs() << "Undo: OperandsHider: " << *Inst << "\n"); |
| for (unsigned It = 0, EndIt = OriginalValues.size(); It != EndIt; ++It) |
| Inst->setOperand(It, OriginalValues[It]); |
| } |
| }; |
| |
| /// \brief Build a truncate instruction. |
| class TruncBuilder : public TypePromotionAction { |
| Value *Val; |
| public: |
| /// \brief Build a truncate instruction of \p Opnd producing a \p Ty |
| /// result. |
| /// trunc Opnd to Ty. |
| TruncBuilder(Instruction *Opnd, Type *Ty) : TypePromotionAction(Opnd) { |
| IRBuilder<> Builder(Opnd); |
| Val = Builder.CreateTrunc(Opnd, Ty, "promoted"); |
| DEBUG(dbgs() << "Do: TruncBuilder: " << *Val << "\n"); |
| } |
| |
| /// \brief Get the built value. |
| Value *getBuiltValue() { return Val; } |
| |
| /// \brief Remove the built instruction. |
| void undo() override { |
| DEBUG(dbgs() << "Undo: TruncBuilder: " << *Val << "\n"); |
| if (Instruction *IVal = dyn_cast<Instruction>(Val)) |
| IVal->eraseFromParent(); |
| } |
| }; |
| |
| /// \brief Build a sign extension instruction. |
| class SExtBuilder : public TypePromotionAction { |
| Value *Val; |
| public: |
| /// \brief Build a sign extension instruction of \p Opnd producing a \p Ty |
| /// result. |
| /// sext Opnd to Ty. |
| SExtBuilder(Instruction *InsertPt, Value *Opnd, Type *Ty) |
| : TypePromotionAction(InsertPt) { |
| IRBuilder<> Builder(InsertPt); |
| Val = Builder.CreateSExt(Opnd, Ty, "promoted"); |
| DEBUG(dbgs() << "Do: SExtBuilder: " << *Val << "\n"); |
| } |
| |
| /// \brief Get the built value. |
| Value *getBuiltValue() { return Val; } |
| |
| /// \brief Remove the built instruction. |
| void undo() override { |
| DEBUG(dbgs() << "Undo: SExtBuilder: " << *Val << "\n"); |
| if (Instruction *IVal = dyn_cast<Instruction>(Val)) |
| IVal->eraseFromParent(); |
| } |
| }; |
| |
| /// \brief Build a zero extension instruction. |
| class ZExtBuilder : public TypePromotionAction { |
| Value *Val; |
| public: |
| /// \brief Build a zero extension instruction of \p Opnd producing a \p Ty |
| /// result. |
| /// zext Opnd to Ty. |
| ZExtBuilder(Instruction *InsertPt, Value *Opnd, Type *Ty) |
| : TypePromotionAction(InsertPt) { |
| IRBuilder<> Builder(InsertPt); |
| Val = Builder.CreateZExt(Opnd, Ty, "promoted"); |
| DEBUG(dbgs() << "Do: ZExtBuilder: " << *Val << "\n"); |
| } |
| |
| /// \brief Get the built value. |
| Value *getBuiltValue() { return Val; } |
| |
| /// \brief Remove the built instruction. |
| void undo() override { |
| DEBUG(dbgs() << "Undo: ZExtBuilder: " << *Val << "\n"); |
| if (Instruction *IVal = dyn_cast<Instruction>(Val)) |
| IVal->eraseFromParent(); |
| } |
| }; |
| |
| /// \brief Mutate an instruction to another type. |
| class TypeMutator : public TypePromotionAction { |
| /// Record the original type. |
| Type *OrigTy; |
| |
| public: |
| /// \brief Mutate the type of \p Inst into \p NewTy. |
| TypeMutator(Instruction *Inst, Type *NewTy) |
| : TypePromotionAction(Inst), OrigTy(Inst->getType()) { |
| DEBUG(dbgs() << "Do: MutateType: " << *Inst << " with " << *NewTy |
| << "\n"); |
| Inst->mutateType(NewTy); |
| } |
| |
| /// \brief Mutate the instruction back to its original type. |
| void undo() override { |
| DEBUG(dbgs() << "Undo: MutateType: " << *Inst << " with " << *OrigTy |
| << "\n"); |
| Inst->mutateType(OrigTy); |
| } |
| }; |
| |
| /// \brief Replace the uses of an instruction by another instruction. |
| class UsesReplacer : public TypePromotionAction { |
| /// Helper structure to keep track of the replaced uses. |
| struct InstructionAndIdx { |
| /// The instruction using the instruction. |
| Instruction *Inst; |
| /// The index where this instruction is used for Inst. |
| unsigned Idx; |
| InstructionAndIdx(Instruction *Inst, unsigned Idx) |
| : Inst(Inst), Idx(Idx) {} |
| }; |
| |
| /// Keep track of the original uses (pair Instruction, Index). |
| SmallVector<InstructionAndIdx, 4> OriginalUses; |
| typedef SmallVectorImpl<InstructionAndIdx>::iterator use_iterator; |
| |
| public: |
| /// \brief Replace all the use of \p Inst by \p New. |
| UsesReplacer(Instruction *Inst, Value *New) : TypePromotionAction(Inst) { |
| DEBUG(dbgs() << "Do: UsersReplacer: " << *Inst << " with " << *New |
| << "\n"); |
| // Record the original uses. |
| for (Use &U : Inst->uses()) { |
| Instruction *UserI = cast<Instruction>(U.getUser()); |
| OriginalUses.push_back(InstructionAndIdx(UserI, U.getOperandNo())); |
| } |
| // Now, we can replace the uses. |
| Inst->replaceAllUsesWith(New); |
| } |
| |
| /// \brief Reassign the original uses of Inst to Inst. |
| void undo() override { |
| DEBUG(dbgs() << "Undo: UsersReplacer: " << *Inst << "\n"); |
| for (use_iterator UseIt = OriginalUses.begin(), |
| EndIt = OriginalUses.end(); |
| UseIt != EndIt; ++UseIt) { |
| UseIt->Inst->setOperand(UseIt->Idx, Inst); |
| } |
| } |
| }; |
| |
| /// \brief Remove an instruction from the IR. |
| class InstructionRemover : public TypePromotionAction { |
| /// Original position of the instruction. |
| InsertionHandler Inserter; |
| /// Helper structure to hide all the link to the instruction. In other |
| /// words, this helps to do as if the instruction was removed. |
| OperandsHider Hider; |
| /// Keep track of the uses replaced, if any. |
| UsesReplacer *Replacer; |
| |
| public: |
| /// \brief Remove all reference of \p Inst and optinally replace all its |
| /// uses with New. |
| /// \pre If !Inst->use_empty(), then New != nullptr |
| InstructionRemover(Instruction *Inst, Value *New = nullptr) |
| : TypePromotionAction(Inst), Inserter(Inst), Hider(Inst), |
| Replacer(nullptr) { |
| if (New) |
| Replacer = new UsesReplacer(Inst, New); |
| DEBUG(dbgs() << "Do: InstructionRemover: " << *Inst << "\n"); |
| Inst->removeFromParent(); |
| } |
| |
| ~InstructionRemover() override { delete Replacer; } |
| |
| /// \brief Really remove the instruction. |
| void commit() override { delete Inst; } |
| |
| /// \brief Resurrect the instruction and reassign it to the proper uses if |
| /// new value was provided when build this action. |
| void undo() override { |
| DEBUG(dbgs() << "Undo: InstructionRemover: " << *Inst << "\n"); |
| Inserter.insert(Inst); |
| if (Replacer) |
| Replacer->undo(); |
| Hider.undo(); |
| } |
| }; |
| |
| public: |
| /// Restoration point. |
| /// The restoration point is a pointer to an action instead of an iterator |
| /// because the iterator may be invalidated but not the pointer. |
| typedef const TypePromotionAction *ConstRestorationPt; |
| /// Advocate every changes made in that transaction. |
| void commit(); |
| /// Undo all the changes made after the given point. |
| void rollback(ConstRestorationPt Point); |
| /// Get the current restoration point. |
| ConstRestorationPt getRestorationPoint() const; |
| |
| /// \name API for IR modification with state keeping to support rollback. |
| /// @{ |
| /// Same as Instruction::setOperand. |
| void setOperand(Instruction *Inst, unsigned Idx, Value *NewVal); |
| /// Same as Instruction::eraseFromParent. |
| void eraseInstruction(Instruction *Inst, Value *NewVal = nullptr); |
| /// Same as Value::replaceAllUsesWith. |
| void replaceAllUsesWith(Instruction *Inst, Value *New); |
| /// Same as Value::mutateType. |
| void mutateType(Instruction *Inst, Type *NewTy); |
| /// Same as IRBuilder::createTrunc. |
| Value *createTrunc(Instruction *Opnd, Type *Ty); |
| /// Same as IRBuilder::createSExt. |
| Value *createSExt(Instruction *Inst, Value *Opnd, Type *Ty); |
| /// Same as IRBuilder::createZExt. |
| Value *createZExt(Instruction *Inst, Value *Opnd, Type *Ty); |
| /// Same as Instruction::moveBefore. |
| void moveBefore(Instruction *Inst, Instruction *Before); |
| /// @} |
| |
| private: |
| /// The ordered list of actions made so far. |
| SmallVector<std::unique_ptr<TypePromotionAction>, 16> Actions; |
| typedef SmallVectorImpl<std::unique_ptr<TypePromotionAction>>::iterator CommitPt; |
| }; |
| |
| void TypePromotionTransaction::setOperand(Instruction *Inst, unsigned Idx, |
| Value *NewVal) { |
| Actions.push_back( |
| make_unique<TypePromotionTransaction::OperandSetter>(Inst, Idx, NewVal)); |
| } |
| |
| void TypePromotionTransaction::eraseInstruction(Instruction *Inst, |
| Value *NewVal) { |
| Actions.push_back( |
| make_unique<TypePromotionTransaction::InstructionRemover>(Inst, NewVal)); |
| } |
| |
| void TypePromotionTransaction::replaceAllUsesWith(Instruction *Inst, |
| Value *New) { |
| Actions.push_back(make_unique<TypePromotionTransaction::UsesReplacer>(Inst, New)); |
| } |
| |
| void TypePromotionTransaction::mutateType(Instruction *Inst, Type *NewTy) { |
| Actions.push_back(make_unique<TypePromotionTransaction::TypeMutator>(Inst, NewTy)); |
| } |
| |
| Value *TypePromotionTransaction::createTrunc(Instruction *Opnd, |
| Type *Ty) { |
| std::unique_ptr<TruncBuilder> Ptr(new TruncBuilder(Opnd, Ty)); |
| Value *Val = Ptr->getBuiltValue(); |
| Actions.push_back(std::move(Ptr)); |
| return Val; |
| } |
| |
| Value *TypePromotionTransaction::createSExt(Instruction *Inst, |
| Value *Opnd, Type *Ty) { |
| std::unique_ptr<SExtBuilder> Ptr(new SExtBuilder(Inst, Opnd, Ty)); |
| Value *Val = Ptr->getBuiltValue(); |
| Actions.push_back(std::move(Ptr)); |
| return Val; |
| } |
| |
| Value *TypePromotionTransaction::createZExt(Instruction *Inst, |
| Value *Opnd, Type *Ty) { |
| std::unique_ptr<ZExtBuilder> Ptr(new ZExtBuilder(Inst, Opnd, Ty)); |
| Value *Val = Ptr->getBuiltValue(); |
| Actions.push_back(std::move(Ptr)); |
| return Val; |
| } |
| |
| void TypePromotionTransaction::moveBefore(Instruction *Inst, |
| Instruction *Before) { |
| Actions.push_back( |
| make_unique<TypePromotionTransaction::InstructionMoveBefore>(Inst, Before)); |
| } |
| |
| TypePromotionTransaction::ConstRestorationPt |
| TypePromotionTransaction::getRestorationPoint() const { |
| return !Actions.empty() ? Actions.back().get() : nullptr; |
| } |
| |
| void TypePromotionTransaction::commit() { |
| for (CommitPt It = Actions.begin(), EndIt = Actions.end(); It != EndIt; |
| ++It) |
| (*It)->commit(); |
| Actions.clear(); |
| } |
| |
| void TypePromotionTransaction::rollback( |
| TypePromotionTransaction::ConstRestorationPt Point) { |
| while (!Actions.empty() && Point != Actions.back().get()) { |
| std::unique_ptr<TypePromotionAction> Curr = Actions.pop_back_val(); |
| Curr->undo(); |
| } |
| } |
| |
| /// \brief A helper class for matching addressing modes. |
| /// |
| /// This encapsulates the logic for matching the target-legal addressing modes. |
| class AddressingModeMatcher { |
| SmallVectorImpl<Instruction*> &AddrModeInsts; |
| const TargetMachine &TM; |
| const TargetLowering &TLI; |
| const DataLayout &DL; |
| |
| /// AccessTy/MemoryInst - This is the type for the access (e.g. double) and |
| /// the memory instruction that we're computing this address for. |
| Type *AccessTy; |
| unsigned AddrSpace; |
| Instruction *MemoryInst; |
| |
| /// AddrMode - This is the addressing mode that we're building up. This is |
| /// part of the return value of this addressing mode matching stuff. |
| ExtAddrMode &AddrMode; |
| |
| /// The instructions inserted by other CodeGenPrepare optimizations. |
| const SetOfInstrs &InsertedInsts; |
| /// A map from the instructions to their type before promotion. |
| InstrToOrigTy &PromotedInsts; |
| /// The ongoing transaction where every action should be registered. |
| TypePromotionTransaction &TPT; |
| |
| /// IgnoreProfitability - This is set to true when we should not do |
| /// profitability checks. When true, IsProfitableToFoldIntoAddressingMode |
| /// always returns true. |
| bool IgnoreProfitability; |
| |
| AddressingModeMatcher(SmallVectorImpl<Instruction *> &AMI, |
| const TargetMachine &TM, Type *AT, unsigned AS, |
| Instruction *MI, ExtAddrMode &AM, |
| const SetOfInstrs &InsertedInsts, |
| InstrToOrigTy &PromotedInsts, |
| TypePromotionTransaction &TPT) |
| : AddrModeInsts(AMI), TM(TM), |
| TLI(*TM.getSubtargetImpl(*MI->getParent()->getParent()) |
| ->getTargetLowering()), |
| DL(MI->getModule()->getDataLayout()), AccessTy(AT), AddrSpace(AS), |
| MemoryInst(MI), AddrMode(AM), InsertedInsts(InsertedInsts), |
| PromotedInsts(PromotedInsts), TPT(TPT) { |
| IgnoreProfitability = false; |
| } |
| public: |
| |
| /// Match - Find the maximal addressing mode that a load/store of V can fold, |
| /// give an access type of AccessTy. This returns a list of involved |
| /// instructions in AddrModeInsts. |
| /// \p InsertedInsts The instructions inserted by other CodeGenPrepare |
| /// optimizations. |
| /// \p PromotedInsts maps the instructions to their type before promotion. |
| /// \p The ongoing transaction where every action should be registered. |
| static ExtAddrMode Match(Value *V, Type *AccessTy, unsigned AS, |
| Instruction *MemoryInst, |
| SmallVectorImpl<Instruction*> &AddrModeInsts, |
| const TargetMachine &TM, |
| const SetOfInstrs &InsertedInsts, |
| InstrToOrigTy &PromotedInsts, |
| TypePromotionTransaction &TPT) { |
| ExtAddrMode Result; |
| |
| bool Success = AddressingModeMatcher(AddrModeInsts, TM, AccessTy, AS, |
| MemoryInst, Result, InsertedInsts, |
| PromotedInsts, TPT).MatchAddr(V, 0); |
| (void)Success; assert(Success && "Couldn't select *anything*?"); |
| return Result; |
| } |
| private: |
| bool MatchScaledValue(Value *ScaleReg, int64_t Scale, unsigned Depth); |
| bool MatchAddr(Value *V, unsigned Depth); |
| bool MatchOperationAddr(User *Operation, unsigned Opcode, unsigned Depth, |
| bool *MovedAway = nullptr); |
| bool IsProfitableToFoldIntoAddressingMode(Instruction *I, |
| ExtAddrMode &AMBefore, |
| ExtAddrMode &AMAfter); |
| bool ValueAlreadyLiveAtInst(Value *Val, Value *KnownLive1, Value *KnownLive2); |
| bool IsPromotionProfitable(unsigned NewCost, unsigned OldCost, |
| Value *PromotedOperand) const; |
| }; |
| |
| /// MatchScaledValue - Try adding ScaleReg*Scale to the current addressing mode. |
| /// Return true and update AddrMode if this addr mode is legal for the target, |
| /// false if not. |
| bool AddressingModeMatcher::MatchScaledValue(Value *ScaleReg, int64_t Scale, |
| unsigned Depth) { |
| // If Scale is 1, then this is the same as adding ScaleReg to the addressing |
| // mode. Just process that directly. |
| if (Scale == 1) |
| return MatchAddr(ScaleReg, Depth); |
| |
| // If the scale is 0, it takes nothing to add this. |
| if (Scale == 0) |
| return true; |
| |
| // If we already have a scale of this value, we can add to it, otherwise, we |
| // need an available scale field. |
| if (AddrMode.Scale != 0 && AddrMode.ScaledReg != ScaleReg) |
| return false; |
| |
| ExtAddrMode TestAddrMode = AddrMode; |
| |
| // Add scale to turn X*4+X*3 -> X*7. This could also do things like |
| // [A+B + A*7] -> [B+A*8]. |
| TestAddrMode.Scale += Scale; |
| TestAddrMode.ScaledReg = ScaleReg; |
| |
| // If the new address isn't legal, bail out. |
| if (!TLI.isLegalAddressingMode(DL, TestAddrMode, AccessTy, AddrSpace)) |
| return false; |
| |
| // It was legal, so commit it. |
| AddrMode = TestAddrMode; |
| |
| // Okay, we decided that we can add ScaleReg+Scale to AddrMode. Check now |
| // to see if ScaleReg is actually X+C. If so, we can turn this into adding |
| // X*Scale + C*Scale to addr mode. |
| ConstantInt *CI = nullptr; Value *AddLHS = nullptr; |
| if (isa<Instruction>(ScaleReg) && // not a constant expr. |
| match(ScaleReg, m_Add(m_Value(AddLHS), m_ConstantInt(CI)))) { |
| TestAddrMode.ScaledReg = AddLHS; |
| TestAddrMode.BaseOffs += CI->getSExtValue()*TestAddrMode.Scale; |
| |
| // If this addressing mode is legal, commit it and remember that we folded |
| // this instruction. |
| if (TLI.isLegalAddressingMode(DL, TestAddrMode, AccessTy, AddrSpace)) { |
| AddrModeInsts.push_back(cast<Instruction>(ScaleReg)); |
| AddrMode = TestAddrMode; |
| return true; |
| } |
| } |
| |
| // Otherwise, not (x+c)*scale, just return what we have. |
| return true; |
| } |
| |
| /// MightBeFoldableInst - This is a little filter, which returns true if an |
| /// addressing computation involving I might be folded into a load/store |
| /// accessing it. This doesn't need to be perfect, but needs to accept at least |
| /// the set of instructions that MatchOperationAddr can. |
| static bool MightBeFoldableInst(Instruction *I) { |
| switch (I->getOpcode()) { |
| case Instruction::BitCast: |
| case Instruction::AddrSpaceCast: |
| // Don't touch identity bitcasts. |
| if (I->getType() == I->getOperand(0)->getType()) |
| return false; |
| return I->getType()->isPointerTy() || I->getType()->isIntegerTy(); |
| case Instruction::PtrToInt: |
| // PtrToInt is always a noop, as we know that the int type is pointer sized. |
| return true; |
| case Instruction::IntToPtr: |
| // We know the input is intptr_t, so this is foldable. |
| return true; |
| case Instruction::Add: |
| return true; |
| case Instruction::Mul: |
| case Instruction::Shl: |
| // Can only handle X*C and X << C. |
| return isa<ConstantInt>(I->getOperand(1)); |
| case Instruction::GetElementPtr: |
| return true; |
| default: |
| return false; |
| } |
| } |
| |
| /// \brief Check whether or not \p Val is a legal instruction for \p TLI. |
| /// \note \p Val is assumed to be the product of some type promotion. |
| /// Therefore if \p Val has an undefined state in \p TLI, this is assumed |
| /// to be legal, as the non-promoted value would have had the same state. |
| static bool isPromotedInstructionLegal(const TargetLowering &TLI, |
| const DataLayout &DL, Value *Val) { |
| Instruction *PromotedInst = dyn_cast<Instruction>(Val); |
| if (!PromotedInst) |
| return false; |
| int ISDOpcode = TLI.InstructionOpcodeToISD(PromotedInst->getOpcode()); |
| // If the ISDOpcode is undefined, it was undefined before the promotion. |
| if (!ISDOpcode) |
| return true; |
| // Otherwise, check if the promoted instruction is legal or not. |
| return TLI.isOperationLegalOrCustom( |
| ISDOpcode, TLI.getValueType(DL, PromotedInst->getType())); |
| } |
| |
| /// \brief Hepler class to perform type promotion. |
| class TypePromotionHelper { |
| /// \brief Utility function to check whether or not a sign or zero extension |
| /// of \p Inst with \p ConsideredExtType can be moved through \p Inst by |
| /// either using the operands of \p Inst or promoting \p Inst. |
| /// The type of the extension is defined by \p IsSExt. |
| /// In other words, check if: |
| /// ext (Ty Inst opnd1 opnd2 ... opndN) to ConsideredExtType. |
| /// #1 Promotion applies: |
| /// ConsideredExtType Inst (ext opnd1 to ConsideredExtType, ...). |
| /// #2 Operand reuses: |
| /// ext opnd1 to ConsideredExtType. |
| /// \p PromotedInsts maps the instructions to their type before promotion. |
| static bool canGetThrough(const Instruction *Inst, Type *ConsideredExtType, |
| const InstrToOrigTy &PromotedInsts, bool IsSExt); |
| |
| /// \brief Utility function to determine if \p OpIdx should be promoted when |
| /// promoting \p Inst. |
| static bool shouldExtOperand(const Instruction *Inst, int OpIdx) { |
| if (isa<SelectInst>(Inst) && OpIdx == 0) |
| return false; |
| return true; |
| } |
| |
| /// \brief Utility function to promote the operand of \p Ext when this |
| /// operand is a promotable trunc or sext or zext. |
| /// \p PromotedInsts maps the instructions to their type before promotion. |
| /// \p CreatedInstsCost[out] contains the cost of all instructions |
| /// created to promote the operand of Ext. |
| /// Newly added extensions are inserted in \p Exts. |
| /// Newly added truncates are inserted in \p Truncs. |
| /// Should never be called directly. |
| /// \return The promoted value which is used instead of Ext. |
| static Value *promoteOperandForTruncAndAnyExt( |
| Instruction *Ext, TypePromotionTransaction &TPT, |
| InstrToOrigTy &PromotedInsts, unsigned &CreatedInstsCost, |
| SmallVectorImpl<Instruction *> *Exts, |
| SmallVectorImpl<Instruction *> *Truncs, const TargetLowering &TLI); |
| |
| /// \brief Utility function to promote the operand of \p Ext when this |
| /// operand is promotable and is not a supported trunc or sext. |
| /// \p PromotedInsts maps the instructions to their type before promotion. |
| /// \p CreatedInstsCost[out] contains the cost of all the instructions |
| /// created to promote the operand of Ext. |
| /// Newly added extensions are inserted in \p Exts. |
| /// Newly added truncates are inserted in \p Truncs. |
| /// Should never be called directly. |
| /// \return The promoted value which is used instead of Ext. |
| static Value *promoteOperandForOther(Instruction *Ext, |
| TypePromotionTransaction &TPT, |
| InstrToOrigTy &PromotedInsts, |
| unsigned &CreatedInstsCost, |
| SmallVectorImpl<Instruction *> *Exts, |
| SmallVectorImpl<Instruction *> *Truncs, |
| const TargetLowering &TLI, bool IsSExt); |
| |
| /// \see promoteOperandForOther. |
| static Value *signExtendOperandForOther( |
| Instruction *Ext, TypePromotionTransaction &TPT, |
| InstrToOrigTy &PromotedInsts, unsigned &CreatedInstsCost, |
| SmallVectorImpl<Instruction *> *Exts, |
| SmallVectorImpl<Instruction *> *Truncs, const TargetLowering &TLI) { |
| return promoteOperandForOther(Ext, TPT, PromotedInsts, CreatedInstsCost, |
| Exts, Truncs, TLI, true); |
| } |
| |
| /// \see promoteOperandForOther. |
| static Value *zeroExtendOperandForOther( |
| Instruction *Ext, TypePromotionTransaction &TPT, |
| InstrToOrigTy &PromotedInsts, unsigned &CreatedInstsCost, |
| SmallVectorImpl<Instruction *> *Exts, |
| SmallVectorImpl<Instruction *> *Truncs, const TargetLowering &TLI) { |
| return promoteOperandForOther(Ext, TPT, PromotedInsts, CreatedInstsCost, |
| Exts, Truncs, TLI, false); |
| } |
| |
| public: |
| /// Type for the utility function that promotes the operand of Ext. |
| typedef Value *(*Action)(Instruction *Ext, TypePromotionTransaction &TPT, |
| InstrToOrigTy &PromotedInsts, |
| unsigned &CreatedInstsCost, |
| SmallVectorImpl<Instruction *> *Exts, |
| SmallVectorImpl<Instruction *> *Truncs, |
| const TargetLowering &TLI); |
| /// \brief Given a sign/zero extend instruction \p Ext, return the approriate |
| /// action to promote the operand of \p Ext instead of using Ext. |
| /// \return NULL if no promotable action is possible with the current |
| /// sign extension. |
| /// \p InsertedInsts keeps track of all the instructions inserted by the |
| /// other CodeGenPrepare optimizations. This information is important |
| /// because we do not want to promote these instructions as CodeGenPrepare |
| /// will reinsert them later. Thus creating an infinite loop: create/remove. |
| /// \p PromotedInsts maps the instructions to their type before promotion. |
| static Action getAction(Instruction *Ext, const SetOfInstrs &InsertedInsts, |
| const TargetLowering &TLI, |
| const InstrToOrigTy &PromotedInsts); |
| }; |
| |
| bool TypePromotionHelper::canGetThrough(const Instruction *Inst, |
| Type *ConsideredExtType, |
| const InstrToOrigTy &PromotedInsts, |
| bool IsSExt) { |
| // The promotion helper does not know how to deal with vector types yet. |
| // To be able to fix that, we would need to fix the places where we |
| // statically extend, e.g., constants and such. |
| if (Inst->getType()->isVectorTy()) |
| return false; |
| |
| // We can always get through zext. |
| if (isa<ZExtInst>(Inst)) |
| return true; |
| |
| // sext(sext) is ok too. |
| if (IsSExt && isa<SExtInst>(Inst)) |
| return true; |
| |
| // We can get through binary operator, if it is legal. In other words, the |
| // binary operator must have a nuw or nsw flag. |
| const BinaryOperator *BinOp = dyn_cast<BinaryOperator>(Inst); |
| if (BinOp && isa<OverflowingBinaryOperator>(BinOp) && |
| ((!IsSExt && BinOp->hasNoUnsignedWrap()) || |
| (IsSExt && BinOp->hasNoSignedWrap()))) |
| return true; |
| |
| // Check if we can do the following simplification. |
| // ext(trunc(opnd)) --> ext(opnd) |
| if (!isa<TruncInst>(Inst)) |
| return false; |
| |
| Value *OpndVal = Inst->getOperand(0); |
| // Check if we can use this operand in the extension. |
| // If the type is larger than the result type of the extension, |
| // we cannot. |
| if (!OpndVal->getType()->isIntegerTy() || |
| OpndVal->getType()->getIntegerBitWidth() > |
| ConsideredExtType->getIntegerBitWidth()) |
| return false; |
| |
| // If the operand of the truncate is not an instruction, we will not have |
| // any information on the dropped bits. |
| // (Actually we could for constant but it is not worth the extra logic). |
| Instruction *Opnd = dyn_cast<Instruction>(OpndVal); |
| if (!Opnd) |
| return false; |
| |
| // Check if the source of the type is narrow enough. |
| // I.e., check that trunc just drops extended bits of the same kind of |
| // the extension. |
| // #1 get the type of the operand and check the kind of the extended bits. |
| const Type *OpndType; |
| InstrToOrigTy::const_iterator It = PromotedInsts.find(Opnd); |
| if (It != PromotedInsts.end() && It->second.IsSExt == IsSExt) |
| OpndType = It->second.Ty; |
| else if ((IsSExt && isa<SExtInst>(Opnd)) || (!IsSExt && isa<ZExtInst>(Opnd))) |
| OpndType = Opnd->getOperand(0)->getType(); |
| else |
| return false; |
| |
| // #2 check that the truncate just drop extended bits. |
| if (Inst->getType()->getIntegerBitWidth() >= OpndType->getIntegerBitWidth()) |
| return true; |
| |
| return false; |
| } |
| |
| TypePromotionHelper::Action TypePromotionHelper::getAction( |
| Instruction *Ext, const SetOfInstrs &InsertedInsts, |
| const TargetLowering &TLI, const InstrToOrigTy &PromotedInsts) { |
| assert((isa<SExtInst>(Ext) || isa<ZExtInst>(Ext)) && |
| "Unexpected instruction type"); |
| Instruction *ExtOpnd = dyn_cast<Instruction>(Ext->getOperand(0)); |
| Type *ExtTy = Ext->getType(); |
| bool IsSExt = isa<SExtInst>(Ext); |
| // If the operand of the extension is not an instruction, we cannot |
| // get through. |
| // If it, check we can get through. |
| if (!ExtOpnd || !canGetThrough(ExtOpnd, ExtTy, PromotedInsts, IsSExt)) |
| return nullptr; |
| |
| // Do not promote if the operand has been added by codegenprepare. |
| // Otherwise, it means we are undoing an optimization that is likely to be |
| // redone, thus causing potential infinite loop. |
| if (isa<TruncInst>(ExtOpnd) && InsertedInsts.count(ExtOpnd)) |
| return nullptr; |
| |
| // SExt or Trunc instructions. |
| // Return the related handler. |
| if (isa<SExtInst>(ExtOpnd) || isa<TruncInst>(ExtOpnd) || |
| isa<ZExtInst>(ExtOpnd)) |
| return promoteOperandForTruncAndAnyExt; |
| |
| // Regular instruction. |
| // Abort early if we will have to insert non-free instructions. |
| if (!ExtOpnd->hasOneUse() && !TLI.isTruncateFree(ExtTy, ExtOpnd->getType())) |
| return nullptr; |
| return IsSExt ? signExtendOperandForOther : zeroExtendOperandForOther; |
| } |
| |
| Value *TypePromotionHelper::promoteOperandForTruncAndAnyExt( |
| llvm::Instruction *SExt, TypePromotionTransaction &TPT, |
| InstrToOrigTy &PromotedInsts, unsigned &CreatedInstsCost, |
| SmallVectorImpl<Instruction *> *Exts, |
| SmallVectorImpl<Instruction *> *Truncs, const TargetLowering &TLI) { |
| // By construction, the operand of SExt is an instruction. Otherwise we cannot |
| // get through it and this method should not be called. |
| Instruction *SExtOpnd = cast<Instruction>(SExt->getOperand(0)); |
| Value *ExtVal = SExt; |
| bool HasMergedNonFreeExt = false; |
| if (isa<ZExtInst>(SExtOpnd)) { |
| // Replace s|zext(zext(opnd)) |
| // => zext(opnd). |
| HasMergedNonFreeExt = !TLI.isExtFree(SExtOpnd); |
| Value *ZExt = |
| TPT.createZExt(SExt, SExtOpnd->getOperand(0), SExt->getType()); |
| TPT.replaceAllUsesWith(SExt, ZExt); |
| TPT.eraseInstruction(SExt); |
| ExtVal = ZExt; |
| } else { |
| // Replace z|sext(trunc(opnd)) or sext(sext(opnd)) |
| // => z|sext(opnd). |
| TPT.setOperand(SExt, 0, SExtOpnd->getOperand(0)); |
| } |
| CreatedInstsCost = 0; |
| |
| // Remove dead code. |
| if (SExtOpnd->use_empty()) |
| TPT.eraseInstruction(SExtOpnd); |
| |
| // Check if the extension is still needed. |
| Instruction *ExtInst = dyn_cast<Instruction>(ExtVal); |
| if (!ExtInst || ExtInst->getType() != ExtInst->getOperand(0)->getType()) { |
| if (ExtInst) { |
| if (Exts) |
| Exts->push_back(ExtInst); |
| CreatedInstsCost = !TLI.isExtFree(ExtInst) && !HasMergedNonFreeExt; |
| } |
| return ExtVal; |
| } |
| |
| // At this point we have: ext ty opnd to ty. |
| // Reassign the uses of ExtInst to the opnd and remove ExtInst. |
| Value *NextVal = ExtInst->getOperand(0); |
| TPT.eraseInstruction(ExtInst, NextVal); |
| return NextVal; |
| } |
| |
| Value *TypePromotionHelper::promoteOperandForOther( |
| Instruction *Ext, TypePromotionTransaction &TPT, |
| InstrToOrigTy &PromotedInsts, unsigned &CreatedInstsCost, |
| SmallVectorImpl<Instruction *> *Exts, |
| SmallVectorImpl<Instruction *> *Truncs, const TargetLowering &TLI, |
| bool IsSExt) { |
| // By construction, the operand of Ext is an instruction. Otherwise we cannot |
| // get through it and this method should not be called. |
| Instruction *ExtOpnd = cast<Instruction>(Ext->getOperand(0)); |
| CreatedInstsCost = 0; |
| if (!ExtOpnd->hasOneUse()) { |
| // ExtOpnd will be promoted. |
| // All its uses, but Ext, will need to use a truncated value of the |
| // promoted version. |
| // Create the truncate now. |
| Value *Trunc = TPT.createTrunc(Ext, ExtOpnd->getType()); |
| if (Instruction *ITrunc = dyn_cast<Instruction>(Trunc)) { |
| ITrunc->removeFromParent(); |
| // Insert it just after the definition. |
| ITrunc->insertAfter(ExtOpnd); |
| if (Truncs) |
| Truncs->push_back(ITrunc); |
| } |
| |
| TPT.replaceAllUsesWith(ExtOpnd, Trunc); |
| // Restore the operand of Ext (which has been replace by the previous call |
| // to replaceAllUsesWith) to avoid creating a cycle trunc <-> sext. |
| TPT.setOperand(Ext, 0, ExtOpnd); |
| } |
| |
| // Get through the Instruction: |
| // 1. Update its type. |
| // 2. Replace the uses of Ext by Inst. |
| // 3. Extend each operand that needs to be extended. |
| |
| // Remember the original type of the instruction before promotion. |
| // This is useful to know that the high bits are sign extended bits. |
| PromotedInsts.insert(std::pair<Instruction *, TypeIsSExt>( |
| ExtOpnd, TypeIsSExt(ExtOpnd->getType(), IsSExt))); |
| // Step #1. |
| TPT.mutateType(ExtOpnd, Ext->getType()); |
| // Step #2. |
| TPT.replaceAllUsesWith(Ext, ExtOpnd); |
| // Step #3. |
| Instruction *ExtForOpnd = Ext; |
| |
| DEBUG(dbgs() << "Propagate Ext to operands\n"); |
| for (int OpIdx = 0, EndOpIdx = ExtOpnd->getNumOperands(); OpIdx != EndOpIdx; |
| ++OpIdx) { |
| DEBUG(dbgs() << "Operand:\n" << *(ExtOpnd->getOperand(OpIdx)) << '\n'); |
| if (ExtOpnd->getOperand(OpIdx)->getType() == Ext->getType() || |
| !shouldExtOperand(ExtOpnd, OpIdx)) { |
| DEBUG(dbgs() << "No need to propagate\n"); |
| continue; |
| } |
| // Check if we can statically extend the operand. |
| Value *Opnd = ExtOpnd->getOperand(OpIdx); |
| if (const ConstantInt *Cst = dyn_cast<ConstantInt>(Opnd)) { |
| DEBUG(dbgs() << "Statically extend\n"); |
| unsigned BitWidth = Ext->getType()->getIntegerBitWidth(); |
| APInt CstVal = IsSExt ? Cst->getValue().sext(BitWidth) |
| : Cst->getValue().zext(BitWidth); |
| TPT.setOperand(ExtOpnd, OpIdx, ConstantInt::get(Ext->getType(), CstVal)); |
| continue; |
| } |
| // UndefValue are typed, so we have to statically sign extend them. |
| if (isa<UndefValue>(Opnd)) { |
| DEBUG(dbgs() << "Statically extend\n"); |
| TPT.setOperand(ExtOpnd, OpIdx, UndefValue::get(Ext->getType())); |
| continue; |
| } |
| |
| // Otherwise we have to explicity sign extend the operand. |
| // Check if Ext was reused to extend an operand. |
| if (!ExtForOpnd) { |
| // If yes, create a new one. |
| DEBUG(dbgs() << "More operands to ext\n"); |
| Value *ValForExtOpnd = IsSExt ? TPT.createSExt(Ext, Opnd, Ext->getType()) |
| : TPT.createZExt(Ext, Opnd, Ext->getType()); |
| if (!isa<Instruction>(ValForExtOpnd)) { |
| TPT.setOperand(ExtOpnd, OpIdx, ValForExtOpnd); |
| continue; |
| } |
| ExtForOpnd = cast<Instruction>(ValForExtOpnd); |
| } |
| if (Exts) |
| Exts->push_back(ExtForOpnd); |
| TPT.setOperand(ExtForOpnd, 0, Opnd); |
| |
| // Move the sign extension before the insertion point. |
| TPT.moveBefore(ExtForOpnd, ExtOpnd); |
| TPT.setOperand(ExtOpnd, OpIdx, ExtForOpnd); |
| CreatedInstsCost += !TLI.isExtFree(ExtForOpnd); |
| // If more sext are required, new instructions will have to be created. |
| ExtForOpnd = nullptr; |
| } |
| if (ExtForOpnd == Ext) { |
| DEBUG(dbgs() << "Extension is useless now\n"); |
| TPT.eraseInstruction(Ext); |
| } |
| return ExtOpnd; |
| } |
| |
| /// IsPromotionProfitable - Check whether or not promoting an instruction |
| /// to a wider type was profitable. |
| /// \p NewCost gives the cost of extension instructions created by the |
| /// promotion. |
| /// \p OldCost gives the cost of extension instructions before the promotion |
| /// plus the number of instructions that have been |
| /// matched in the addressing mode the promotion. |
| /// \p PromotedOperand is the value that has been promoted. |
| /// \return True if the promotion is profitable, false otherwise. |
| bool AddressingModeMatcher::IsPromotionProfitable( |
| unsigned NewCost, unsigned OldCost, Value *PromotedOperand) const { |
| DEBUG(dbgs() << "OldCost: " << OldCost << "\tNewCost: " << NewCost << '\n'); |
| // The cost of the new extensions is greater than the cost of the |
| // old extension plus what we folded. |
| // This is not profitable. |
| if (NewCost > OldCost) |
| return false; |
| if (NewCost < OldCost) |
| return true; |
| // The promotion is neutral but it may help folding the sign extension in |
| // loads for instance. |
| // Check that we did not create an illegal instruction. |
| return isPromotedInstructionLegal(TLI, DL, PromotedOperand); |
| } |
| |
| /// MatchOperationAddr - Given an instruction or constant expr, see if we can |
| /// fold the operation into the addressing mode. If so, update the addressing |
| /// mode and return true, otherwise return false without modifying AddrMode. |
| /// If \p MovedAway is not NULL, it contains the information of whether or |
| /// not AddrInst has to be folded into the addressing mode on success. |
| /// If \p MovedAway == true, \p AddrInst will not be part of the addressing |
| /// because it has been moved away. |
| /// Thus AddrInst must not be added in the matched instructions. |
| /// This state can happen when AddrInst is a sext, since it may be moved away. |
| /// Therefore, AddrInst may not be valid when MovedAway is true and it must |
| /// not be referenced anymore. |
| bool AddressingModeMatcher::MatchOperationAddr(User *AddrInst, unsigned Opcode, |
| unsigned Depth, |
| bool *MovedAway) { |
| // Avoid exponential behavior on extremely deep expression trees. |
| if (Depth >= 5) return false; |
| |
| // By default, all matched instructions stay in place. |
| if (MovedAway) |
| *MovedAway = false; |
| |
| switch (Opcode) { |
| case Instruction::PtrToInt: |
| // PtrToInt is always a noop, as we know that the int type is pointer sized. |
| return MatchAddr(AddrInst->getOperand(0), Depth); |
| case Instruction::IntToPtr: { |
| auto AS = AddrInst->getType()->getPointerAddressSpace(); |
| auto PtrTy = MVT::getIntegerVT(DL.getPointerSizeInBits(AS)); |
| // This inttoptr is a no-op if the integer type is pointer sized. |
| if (TLI.getValueType(DL, AddrInst->getOperand(0)->getType()) == PtrTy) |
| return MatchAddr(AddrInst->getOperand(0), Depth); |
| return false; |
| } |
| case Instruction::BitCast: |
| // BitCast is always a noop, and we can handle it as long as it is |
| // int->int or pointer->pointer (we don't want int<->fp or something). |
| if ((AddrInst->getOperand(0)->getType()->isPointerTy() || |
| AddrInst->getOperand(0)->getType()->isIntegerTy()) && |
| // Don't touch identity bitcasts. These were probably put here by LSR, |
| // and we don't want to mess around with them. Assume it knows what it |
| // is doing. |
| AddrInst->getOperand(0)->getType() != AddrInst->getType()) |
| return MatchAddr(AddrInst->getOperand(0), Depth); |
| return false; |
| case Instruction::AddrSpaceCast: { |
| unsigned SrcAS |
| = AddrInst->getOperand(0)->getType()->getPointerAddressSpace(); |
| unsigned DestAS = AddrInst->getType()->getPointerAddressSpace(); |
| if (TLI.isNoopAddrSpaceCast(SrcAS, DestAS)) |
| return MatchAddr(AddrInst->getOperand(0), Depth); |
| return false; |
| } |
| case Instruction::Add: { |
| // Check to see if we can merge in the RHS then the LHS. If so, we win. |
| ExtAddrMode BackupAddrMode = AddrMode; |
| unsigned OldSize = AddrModeInsts.size(); |
| // Start a transaction at this point. |
| // The LHS may match but not the RHS. |
| // Therefore, we need a higher level restoration point to undo partially |
| // matched operation. |
| TypePromotionTransaction::ConstRestorationPt LastKnownGood = |
| TPT.getRestorationPoint(); |
| |
| if (MatchAddr(AddrInst->getOperand(1), Depth+1) && |
| MatchAddr(AddrInst->getOperand(0), Depth+1)) |
| return true; |
| |
| // Restore the old addr mode info. |
| AddrMode = BackupAddrMode; |
| AddrModeInsts.resize(OldSize); |
| TPT.rollback(LastKnownGood); |
| |
| // Otherwise this was over-aggressive. Try merging in the LHS then the RHS. |
| if (MatchAddr(AddrInst->getOperand(0), Depth+1) && |
| MatchAddr(AddrInst->getOperand(1), Depth+1)) |
| return true; |
| |
| // Otherwise we definitely can't merge the ADD in. |
| AddrMode = BackupAddrMode; |
| AddrModeInsts.resize(OldSize); |
| TPT.rollback(LastKnownGood); |
| break; |
| } |
| //case Instruction::Or: |
| // TODO: We can handle "Or Val, Imm" iff this OR is equivalent to an ADD. |
| //break; |
| case Instruction::Mul: |
| case Instruction::Shl: { |
| // Can only handle X*C and X << C. |
| ConstantInt *RHS = dyn_cast<ConstantInt>(AddrInst->getOperand(1)); |
| if (!RHS) |
| return false; |
| int64_t Scale = RHS->getSExtValue(); |
| if (Opcode == Instruction::Shl) |
| Scale = 1LL << Scale; |
| |
| return MatchScaledValue(AddrInst->getOperand(0), Scale, Depth); |
| } |
| case Instruction::GetElementPtr: { |
| // Scan the GEP. We check it if it contains constant offsets and at most |
| // one variable offset. |
| int VariableOperand = -1; |
| unsigned VariableScale = 0; |
| |
| int64_t ConstantOffset = 0; |
| gep_type_iterator GTI = gep_type_begin(AddrInst); |
| for (unsigned i = 1, e = AddrInst->getNumOperands(); i != e; ++i, ++GTI) { |
| if (StructType *STy = dyn_cast<StructType>(*GTI)) { |
| const StructLayout *SL = DL.getStructLayout(STy); |
| unsigned Idx = |
| cast<ConstantInt>(AddrInst->getOperand(i))->getZExtValue(); |
| ConstantOffset += SL->getElementOffset(Idx); |
| } else { |
| uint64_t TypeSize = DL.getTypeAllocSize(GTI.getIndexedType()); |
| if (ConstantInt *CI = dyn_cast<ConstantInt>(AddrInst->getOperand(i))) { |
| ConstantOffset += CI->getSExtValue()*TypeSize; |
| } else if (TypeSize) { // Scales of zero don't do anything. |
| // We only allow one variable index at the moment. |
| if (VariableOperand != -1) |
| return false; |
| |
| // Remember the variable index. |
| VariableOperand = i; |
| VariableScale = TypeSize; |
| } |
| } |
| } |
| |
| // A common case is for the GEP to only do a constant offset. In this case, |
| // just add it to the disp field and check validity. |
| if (VariableOperand == -1) { |
| AddrMode.BaseOffs += ConstantOffset; |
| if (ConstantOffset == 0 || |
| TLI.isLegalAddressingMode(DL, AddrMode, AccessTy, AddrSpace)) { |
| // Check to see if we can fold the base pointer in too. |
| if (MatchAddr(AddrInst->getOperand(0), Depth+1)) |
| return true; |
| } |
| AddrMode.BaseOffs -= ConstantOffset; |
| return false; |
| } |
| |
| // Save the valid addressing mode in case we can't match. |
| ExtAddrMode BackupAddrMode = AddrMode; |
| unsigned OldSize = AddrModeInsts.size(); |
| |
| // See if the scale and offset amount is valid for this target. |
| AddrMode.BaseOffs += ConstantOffset; |
| |
| // Match the base operand of the GEP. |
| if (!MatchAddr(AddrInst->getOperand(0), Depth+1)) { |
| // If it couldn't be matched, just stuff the value in a register. |
| if (AddrMode.HasBaseReg) { |
| AddrMode = BackupAddrMode; |
| AddrModeInsts.resize(OldSize); |
| return false; |
| } |
| AddrMode.HasBaseReg = true; |
| AddrMode.BaseReg = AddrInst->getOperand(0); |
| } |
| |
| // Match the remaining variable portion of the GEP. |
| if (!MatchScaledValue(AddrInst->getOperand(VariableOperand), VariableScale, |
| Depth)) { |
| // If it couldn't be matched, try stuffing the base into a register |
| // instead of matching it, and retrying the match of the scale. |
| AddrMode = BackupAddrMode; |
| AddrModeInsts.resize(OldSize); |
| if (AddrMode.HasBaseReg) |
| return false; |
| AddrMode.HasBaseReg = true; |
| AddrMode.BaseReg = AddrInst->getOperand(0); |
| AddrMode.BaseOffs += ConstantOffset; |
| if (!MatchScaledValue(AddrInst->getOperand(VariableOperand), |
| VariableScale, Depth)) { |
| // If even that didn't work, bail. |
| AddrMode = BackupAddrMode; |
| AddrModeInsts.resize(OldSize); |
| return false; |
| } |
| } |
| |
| return true; |
| } |
| case Instruction::SExt: |
| case Instruction::ZExt: { |
| Instruction *Ext = dyn_cast<Instruction>(AddrInst); |
| if (!Ext) |
| return false; |
| |
| // Try to move this ext out of the way of the addressing mode. |
| // Ask for a method for doing so. |
| TypePromotionHelper::Action TPH = |
| TypePromotionHelper::getAction(Ext, InsertedInsts, TLI, PromotedInsts); |
| if (!TPH) |
| return false; |
| |
| TypePromotionTransaction::ConstRestorationPt LastKnownGood = |
| TPT.getRestorationPoint(); |
| unsigned CreatedInstsCost = 0; |
| unsigned ExtCost = !TLI.isExtFree(Ext); |
| Value *PromotedOperand = |
| TPH(Ext, TPT, PromotedInsts, CreatedInstsCost, nullptr, nullptr, TLI); |
| // SExt has been moved away. |
| // Thus either it will be rematched later in the recursive calls or it is |
| // gone. Anyway, we must not fold it into the addressing mode at this point. |
| // E.g., |
| // op = add opnd, 1 |
| // idx = ext op |
| // addr = gep base, idx |
| // is now: |
| // promotedOpnd = ext opnd <- no match here |
| // op = promoted_add promotedOpnd, 1 <- match (later in recursive calls) |
| // addr = gep base, op <- match |
| if (MovedAway) |
| *MovedAway = true; |
| |
| assert(PromotedOperand && |
| "TypePromotionHelper should have filtered out those cases"); |
| |
| ExtAddrMode BackupAddrMode = AddrMode; |
| unsigned OldSize = AddrModeInsts.size(); |
| |
| if (!MatchAddr(PromotedOperand, Depth) || |
| // The total of the new cost is equals to the cost of the created |
| // instructions. |
| // The total of the old cost is equals to the cost of the extension plus |
| // what we have saved in the addressing mode. |
| !IsPromotionProfitable(CreatedInstsCost, |
| ExtCost + (AddrModeInsts.size() - OldSize), |
| PromotedOperand)) { |
| AddrMode = BackupAddrMode; |
| AddrModeInsts.resize(OldSize); |
| DEBUG(dbgs() << "Sign extension does not pay off: rollback\n"); |
| TPT.rollback(LastKnownGood); |
| return false; |
| } |
| return true; |
| } |
| } |
| return false; |
| } |
| |
| /// MatchAddr - If we can, try to add the value of 'Addr' into the current |
| /// addressing mode. If Addr can't be added to AddrMode this returns false and |
| /// leaves AddrMode unmodified. This assumes that Addr is either a pointer type |
| /// or intptr_t for the target. |
| /// |
| bool AddressingModeMatcher::MatchAddr(Value *Addr, unsigned Depth) { |
| // Start a transaction at this point that we will rollback if the matching |
| // fails. |
| TypePromotionTransaction::ConstRestorationPt LastKnownGood = |
| TPT.getRestorationPoint(); |
| if (ConstantInt *CI = dyn_cast<ConstantInt>(Addr)) { |
| // Fold in immediates if legal for the target. |
| AddrMode.BaseOffs += CI->getSExtValue(); |
| if (TLI.isLegalAddressingMode(DL, AddrMode, AccessTy, AddrSpace)) |
| return true; |
| AddrMode.BaseOffs -= CI->getSExtValue(); |
| } else if (GlobalValue *GV = dyn_cast<GlobalValue>(Addr)) { |
| // If this is a global variable, try to fold it into the addressing mode. |
| if (!AddrMode.BaseGV) { |
| AddrMode.BaseGV = GV; |
| if (TLI.isLegalAddressingMode(DL, AddrMode, AccessTy, AddrSpace)) |
| return true; |
| AddrMode.BaseGV = nullptr; |
| } |
| } else if (Instruction *I = dyn_cast<Instruction>(Addr)) { |
| ExtAddrMode BackupAddrMode = AddrMode; |
| unsigned OldSize = AddrModeInsts.size(); |
| |
| // Check to see if it is possible to fold this operation. |
| bool MovedAway = false; |
| if (MatchOperationAddr(I, I->getOpcode(), Depth, &MovedAway)) { |
| // This instruction may have been move away. If so, there is nothing |
| // to check here. |
| if (MovedAway) |
| return true; |
| // Okay, it's possible to fold this. Check to see if it is actually |
| // *profitable* to do so. We use a simple cost model to avoid increasing |
| // register pressure too much. |
| if (I->hasOneUse() || |
| IsProfitableToFoldIntoAddressingMode(I, BackupAddrMode, AddrMode)) { |
| AddrModeInsts.push_back(I); |
| return true; |
| } |
| |
| // It isn't profitable to do this, roll back. |
| //cerr << "NOT FOLDING: " << *I; |
| AddrMode = BackupAddrMode; |
| AddrModeInsts.resize(OldSize); |
| TPT.rollback(LastKnownGood); |
| } |
| } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Addr)) { |
| if (MatchOperationAddr(CE, CE->getOpcode(), Depth)) |
| return true; |
| TPT.rollback(LastKnownGood); |
| } else if (isa<ConstantPointerNull>(Addr)) { |
| // Null pointer gets folded without affecting the addressing mode. |
| return true; |
| } |
| |
| // Worse case, the target should support [reg] addressing modes. :) |
| if (!AddrMode.HasBaseReg) { |
| AddrMode.HasBaseReg = true; |
| AddrMode.BaseReg = Addr; |
| // Still check for legality in case the target supports [imm] but not [i+r]. |
| if (TLI.isLegalAddressingMode(DL, AddrMode, AccessTy, AddrSpace)) |
| return true; |
| AddrMode.HasBaseReg = false; |
| AddrMode.BaseReg = nullptr; |
| } |
| |
| // If the base register is already taken, see if we can do [r+r]. |
| if (AddrMode.Scale == 0) { |
| AddrMode.Scale = 1; |
| AddrMode.ScaledReg = Addr; |
| if (TLI.isLegalAddressingMode(DL, AddrMode, AccessTy, AddrSpace)) |
| return true; |
| AddrMode.Scale = 0; |
| AddrMode.ScaledReg = nullptr; |
| } |
| // Couldn't match. |
| TPT.rollback(LastKnownGood); |
| return false; |
| } |
| |
| /// IsOperandAMemoryOperand - Check to see if all uses of OpVal by the specified |
| /// inline asm call are due to memory operands. If so, return true, otherwise |
| /// return false. |
| static bool IsOperandAMemoryOperand(CallInst *CI, InlineAsm *IA, Value *OpVal, |
| const TargetMachine &TM) { |
| const Function *F = CI->getParent()->getParent(); |
| const TargetLowering *TLI = TM.getSubtargetImpl(*F)->getTargetLowering(); |
| const TargetRegisterInfo *TRI = TM.getSubtargetImpl(*F)->getRegisterInfo(); |
| TargetLowering::AsmOperandInfoVector TargetConstraints = |
| TLI->ParseConstraints(F->getParent()->getDataLayout(), TRI, |
| ImmutableCallSite(CI)); |
| for (unsigned i = 0, e = TargetConstraints.size(); i != e; ++i) { |
| TargetLowering::AsmOperandInfo &OpInfo = TargetConstraints[i]; |
| |
| // Compute the constraint code and ConstraintType to use. |
| TLI->ComputeConstraintToUse(OpInfo, SDValue()); |
| |
| // If this asm operand is our Value*, and if it isn't an indirect memory |
| // operand, we can't fold it! |
| if (OpInfo.CallOperandVal == OpVal && |
| (OpInfo.ConstraintType != TargetLowering::C_Memory || |
| !OpInfo.isIndirect)) |
| return false; |
| } |
| |
| return true; |
| } |
| |
| /// FindAllMemoryUses - Recursively walk all the uses of I until we find a |
| /// memory use. If we find an obviously non-foldable instruction, return true. |
| /// Add the ultimately found memory instructions to MemoryUses. |
| static bool FindAllMemoryUses( |
| Instruction *I, |
| SmallVectorImpl<std::pair<Instruction *, unsigned>> &MemoryUses, |
| SmallPtrSetImpl<Instruction *> &ConsideredInsts, const TargetMachine &TM) { |
| // If we already considered this instruction, we're done. |
| if (!ConsideredInsts.insert(I).second) |
| return false; |
| |
| // If this is an obviously unfoldable instruction, bail out. |
| if (!MightBeFoldableInst(I)) |
| return true; |
| |
| // Loop over all the uses, recursively processing them. |
| for (Use &U : I->uses()) { |
| Instruction *UserI = cast<Instruction>(U.getUser()); |
| |
| if (LoadInst *LI = dyn_cast<LoadInst>(UserI)) { |
| MemoryUses.push_back(std::make_pair(LI, U.getOperandNo())); |
| continue; |
| } |
| |
| if (StoreInst *SI = dyn_cast<StoreInst>(UserI)) { |
| unsigned opNo = U.getOperandNo(); |
| if (opNo == 0) return true; // Storing addr, not into addr. |
| MemoryUses.push_back(std::make_pair(SI, opNo)); |
| continue; |
| } |
| |
| if (CallInst *CI = dyn_cast<CallInst>(UserI)) { |
| InlineAsm *IA = dyn_cast<InlineAsm>(CI->getCalledValue()); |
| if (!IA) return true; |
| |
| // If this is a memory operand, we're cool, otherwise bail out. |
| if (!IsOperandAMemoryOperand(CI, IA, I, TM)) |
| return true; |
| continue; |
| } |
| |
| if (FindAllMemoryUses(UserI, MemoryUses, ConsideredInsts, TM)) |
| return true; |
| } |
| |
| return false; |
| } |
| |
| /// ValueAlreadyLiveAtInst - Retrn true if Val is already known to be live at |
| /// the use site that we're folding it into. If so, there is no cost to |
| /// include it in the addressing mode. KnownLive1 and KnownLive2 are two values |
| /// that we know are live at the instruction already. |
| bool AddressingModeMatcher::ValueAlreadyLiveAtInst(Value *Val,Value *KnownLive1, |
| Value *KnownLive2) { |
| // If Val is either of the known-live values, we know it is live! |
| if (Val == nullptr || Val == KnownLive1 || Val == KnownLive2) |
| return true; |
| |
| // All values other than instructions and arguments (e.g. constants) are live. |
| if (!isa<Instruction>(Val) && !isa<Argument>(Val)) return true; |
| |
| // If Val is a constant sized alloca in the entry block, it is live, this is |
| // true because it is just a reference to the stack/frame pointer, which is |
| // live for the whole function. |
| if (AllocaInst *AI = dyn_cast<AllocaInst>(Val)) |
| if (AI->isStaticAlloca()) |
| return true; |
| |
| // Check to see if this value is already used in the memory instruction's |
| // block. If so, it's already live into the block at the very least, so we |
| // can reasonably fold it. |
| return Val->isUsedInBasicBlock(MemoryInst->getParent()); |
| } |
| |
| /// IsProfitableToFoldIntoAddressingMode - It is possible for the addressing |
| /// mode of the machine to fold the specified instruction into a load or store |
| /// that ultimately uses it. However, the specified instruction has multiple |
| /// uses. Given this, it may actually increase register pressure to fold it |
| /// into the load. For example, consider this code: |
| /// |
| /// X = ... |
| /// Y = X+1 |
| /// use(Y) -> nonload/store |
| /// Z = Y+1 |
| /// load Z |
| /// |
| /// In this case, Y has multiple uses, and can be folded into the load of Z |
| /// (yielding load [X+2]). However, doing this will cause both "X" and "X+1" to |
| /// be live at the use(Y) line. If we don't fold Y into load Z, we use one |
| /// fewer register. Since Y can't be folded into "use(Y)" we don't increase the |
| /// number of computations either. |
| /// |
| /// Note that this (like most of CodeGenPrepare) is just a rough heuristic. If |
| /// X was live across 'load Z' for other reasons, we actually *would* want to |
| /// fold the addressing mode in the Z case. This would make Y die earlier. |
| bool AddressingModeMatcher:: |
| IsProfitableToFoldIntoAddressingMode(Instruction *I, ExtAddrMode &AMBefore, |
| ExtAddrMode &AMAfter) { |
| if (IgnoreProfitability) return true; |
| |
| // AMBefore is the addressing mode before this instruction was folded into it, |
| // and AMAfter is the addressing mode after the instruction was folded. Get |
| // the set of registers referenced by AMAfter and subtract out those |
| // referenced by AMBefore: this is the set of values which folding in this |
| // address extends the lifetime of. |
| // |
| // Note that there are only two potential values being referenced here, |
| // BaseReg and ScaleReg (global addresses are always available, as are any |
| // folded immediates). |
| Value *BaseReg = AMAfter.BaseReg, *ScaledReg = AMAfter.ScaledReg; |
| |
| // If the BaseReg or ScaledReg was referenced by the previous addrmode, their |
| // lifetime wasn't extended by adding this instruction. |
| if (ValueAlreadyLiveAtInst(BaseReg, AMBefore.BaseReg, AMBefore.ScaledReg)) |
| BaseReg = nullptr; |
| if (ValueAlreadyLiveAtInst(ScaledReg, AMBefore.BaseReg, AMBefore.ScaledReg)) |
| ScaledReg = nullptr; |
| |
| // If folding this instruction (and it's subexprs) didn't extend any live |
| // ranges, we're ok with it. |
| if (!BaseReg && !ScaledReg) |
| return true; |
| |
| // If all uses of this instruction are ultimately load/store/inlineasm's, |
| // check to see if their addressing modes will include this instruction. If |
| // so, we can fold it into all uses, so it doesn't matter if it has multiple |
| // uses. |
| SmallVector<std::pair<Instruction*,unsigned>, 16> MemoryUses; |
| SmallPtrSet<Instruction*, 16> ConsideredInsts; |
| if (FindAllMemoryUses(I, MemoryUses, ConsideredInsts, TM)) |
| return false; // Has a non-memory, non-foldable use! |
| |
| // Now that we know that all uses of this instruction are part of a chain of |
| // computation involving only operations that could theoretically be folded |
| // into a memory use, loop over each of these uses and see if they could |
| // *actually* fold the instruction. |
| SmallVector<Instruction*, 32> MatchedAddrModeInsts; |
| for (unsigned i = 0, e = MemoryUses.size(); i != e; ++i) { |
| Instruction *User = MemoryUses[i].first; |
| unsigned OpNo = MemoryUses[i].second; |
| |
| // Get the access type of this use. If the use isn't a pointer, we don't |
| // know what it accesses. |
| Value *Address = User->getOperand(OpNo); |
| PointerType *AddrTy = dyn_cast<PointerType>(Address->getType()); |
| if (!AddrTy) |
| return false; |
| Type *AddressAccessTy = AddrTy->getElementType(); |
| unsigned AS = AddrTy->getAddressSpace(); |
| |
| // Do a match against the root of this address, ignoring profitability. This |
| // will tell us if the addressing mode for the memory operation will |
| // *actually* cover the shared instruction. |
| ExtAddrMode Result; |
| TypePromotionTransaction::ConstRestorationPt LastKnownGood = |
| TPT.getRestorationPoint(); |
| AddressingModeMatcher Matcher(MatchedAddrModeInsts, TM, AddressAccessTy, AS, |
| MemoryInst, Result, InsertedInsts, |
| PromotedInsts, TPT); |
| Matcher.IgnoreProfitability = true; |
| bool Success = Matcher.MatchAddr(Address, 0); |
| (void)Success; assert(Success && "Couldn't select *anything*?"); |
| |
| // The match was to check the profitability, the changes made are not |
| // part of the original matcher. Therefore, they should be dropped |
| // otherwise the original matcher will not present the right state. |
| TPT.rollback(LastKnownGood); |
| |
| // If the match didn't cover I, then it won't be shared by it. |
| if (std::find(MatchedAddrModeInsts.begin(), MatchedAddrModeInsts.end(), |
| I) == MatchedAddrModeInsts.end()) |
| return false; |
| |
| MatchedAddrModeInsts.clear(); |
| } |
| |
| return true; |
| } |
| |
| } // end anonymous namespace |
| |
| /// IsNonLocalValue - Return true if the specified values are defined in a |
| /// different basic block than BB. |
| static bool IsNonLocalValue(Value *V, BasicBlock *BB) { |
| if (Instruction *I = dyn_cast<Instruction>(V)) |
| return I->getParent() != BB; |
| return false; |
| } |
| |
| /// OptimizeMemoryInst - Load and Store Instructions often have |
| /// addressing modes that can do significant amounts of computation. As such, |
| /// instruction selection will try to get the load or store to do as much |
| /// computation as possible for the program. The problem is that isel can only |
| /// see within a single block. As such, we sink as much legal addressing mode |
| /// stuff into the block as possible. |
| /// |
| /// This method is used to optimize both load/store and inline asms with memory |
| /// operands. |
| bool CodeGenPrepare::OptimizeMemoryInst(Instruction *MemoryInst, Value *Addr, |
| Type *AccessTy, unsigned AddrSpace) { |
| Value *Repl = Addr; |
| |
| // Try to collapse single-value PHI nodes. This is necessary to undo |
| // unprofitable PRE transformations. |
| SmallVector<Value*, 8> worklist; |
| SmallPtrSet<Value*, 16> Visited; |
| worklist.push_back(Addr); |
| |
| // Use a worklist to iteratively look through PHI nodes, and ensure that |
| // the addressing mode obtained from the non-PHI roots of the graph |
| // are equivalent. |
| Value *Consensus = nullptr; |
| unsigned NumUsesConsensus = 0; |
| bool IsNumUsesConsensusValid = false; |
| SmallVector<Instruction*, 16> AddrModeInsts; |
| ExtAddrMode AddrMode; |
| TypePromotionTransaction TPT; |
| TypePromotionTransaction::ConstRestorationPt LastKnownGood = |
| TPT.getRestorationPoint(); |
| while (!worklist.empty()) { |
| Value *V = worklist.back(); |
| worklist.pop_back(); |
| |
| // Break use-def graph loops. |
| if (!Visited.insert(V).second) { |
| Consensus = nullptr; |
| break; |
| } |
| |
| // For a PHI node, push all of its incoming values. |
| if (PHINode *P = dyn_cast<PHINode>(V)) { |
| for (Value *IncValue : P->incoming_values()) |
| worklist.push_back(IncValue); |
| continue; |
| } |
| |
| // For non-PHIs, determine the addressing mode being computed. |
| SmallVector<Instruction*, 16> NewAddrModeInsts; |
| ExtAddrMode NewAddrMode = AddressingModeMatcher::Match( |
| V, AccessTy, AddrSpace, MemoryInst, NewAddrModeInsts, *TM, |
| InsertedInsts, PromotedInsts, TPT); |
| |
| // This check is broken into two cases with very similar code to avoid using |
| // getNumUses() as much as possible. Some values have a lot of uses, so |
| // calling getNumUses() unconditionally caused a significant compile-time |
| // regression. |
| if (!Consensus) { |
| Consensus = V; |
| AddrMode = NewAddrMode; |
| AddrModeInsts = NewAddrModeInsts; |
| continue; |
| } else if (NewAddrMode == AddrMode) { |
| if (!IsNumUsesConsensusValid) { |
| NumUsesConsensus = Consensus->getNumUses(); |
| IsNumUsesConsensusValid = true; |
| } |
| |
| // Ensure that the obtained addressing mode is equivalent to that obtained |
| // for all other roots of the PHI traversal. Also, when choosing one |
| // such root as representative, select the one with the most uses in order |
| // to keep the cost modeling heuristics in AddressingModeMatcher |
| // applicable. |
| unsigned NumUses = V->getNumUses(); |
| if (NumUses > NumUsesConsensus) { |
| Consensus = V; |
| NumUsesConsensus = NumUses; |
| AddrModeInsts = NewAddrModeInsts; |
| } |
| continue; |
| } |
| |
| Consensus = nullptr; |
| break; |
| } |
| |
| // If the addressing mode couldn't be determined, or if multiple different |
| // ones were determined, bail out now. |
| if (!Consensus) { |
| TPT.rollback(LastKnownGood); |
| return false; |
| } |
| TPT.commit(); |
| |
| // Check to see if any of the instructions supersumed by this addr mode are |
| // non-local to I's BB. |
| bool AnyNonLocal = false; |
| for (unsigned i = 0, e = AddrModeInsts.size(); i != e; ++i) { |
| if (IsNonLocalValue(AddrModeInsts[i], MemoryInst->getParent())) { |
| AnyNonLocal = true; |
| break; |
| } |
| } |
| |
| // If all the instructions matched are already in this BB, don't do anything. |
| if (!AnyNonLocal) { |
| DEBUG(dbgs() << "CGP: Found local addrmode: " << AddrMode << "\n"); |
| return false; |
| } |
| |
| // Insert this computation right after this user. Since our caller is |
| // scanning from the top of the BB to the bottom, reuse of the expr are |
| // guaranteed to happen later. |
| IRBuilder<> Builder(MemoryInst); |
| |
| // Now that we determined the addressing expression we want to use and know |
| // that we have to sink it into this block. Check to see if we have already |
| // done this for some other load/store instr in this block. If so, reuse the |
| // computation. |
| Value *&SunkAddr = SunkAddrs[Addr]; |
| if (SunkAddr) { |
| DEBUG(dbgs() << "CGP: Reusing nonlocal addrmode: " << AddrMode << " for " |
| << *MemoryInst << "\n"); |
| if (SunkAddr->getType() != Addr->getType()) |
| SunkAddr = Builder.CreateBitCast(SunkAddr, Addr->getType()); |
| } else if (AddrSinkUsingGEPs || |
| (!AddrSinkUsingGEPs.getNumOccurrences() && TM && |
| TM->getSubtargetImpl(*MemoryInst->getParent()->getParent()) |
| ->useAA())) { |
| // By default, we use the GEP-based method when AA is used later. This |
| // prevents new inttoptr/ptrtoint pairs from degrading AA capabilities. |
| DEBUG(dbgs() << "CGP: SINKING nonlocal addrmode: " << AddrMode << " for " |
| << *MemoryInst << "\n"); |
| Type *IntPtrTy = DL->getIntPtrType(Addr->getType()); |
| Value *ResultPtr = nullptr, *ResultIndex = nullptr; |
| |
| // First, find the pointer. |
| if (AddrMode.BaseReg && AddrMode.BaseReg->getType()->isPointerTy()) { |
| ResultPtr = AddrMode.BaseReg; |
| AddrMode.BaseReg = nullptr; |
| } |
| |
| if (AddrMode.Scale && AddrMode.ScaledReg->getType()->isPointerTy()) { |
| // We can't add more than one pointer together, nor can we scale a |
| // pointer (both of which seem meaningless). |
| if (ResultPtr || AddrMode.Scale != 1) |
| return false; |
| |
| ResultPtr = AddrMode.ScaledReg; |
| AddrMode.Scale = 0; |
| } |
| |
| if (AddrMode.BaseGV) { |
| if (ResultPtr) |
| return false; |
| |
| ResultPtr = AddrMode.BaseGV; |
| } |
| |
| // If the real base value actually came from an inttoptr, then the matcher |
| // will look through it and provide only the integer value. In that case, |
| // use it here. |
| if (!ResultPtr && AddrMode.BaseReg) { |
| ResultPtr = |
| Builder.CreateIntToPtr(AddrMode.BaseReg, Addr->getType(), "sunkaddr"); |
| AddrMode.BaseReg = nullptr; |
| } else if (!ResultPtr && AddrMode.Scale == 1) { |
| ResultPtr = |
| Builder.CreateIntToPtr(AddrMode.ScaledReg, Addr->getType(), "sunkaddr"); |
| AddrMode.Scale = 0; |
| } |
| |
| if (!ResultPtr && |
| !AddrMode.BaseReg && !AddrMode.Scale && !AddrMode.BaseOffs) { |
| SunkAddr = Constant::getNullValue(Addr->getType()); |
| } else if (!ResultPtr) { |
| return false; |
| } else { |
| Type *I8PtrTy = |
| Builder.getInt8PtrTy(Addr->getType()->getPointerAddressSpace()); |
| Type *I8Ty = Builder.getInt8Ty(); |
| |
| // Start with the base register. Do this first so that subsequent address |
| // matching finds it last, which will prevent it from trying to match it |
| // as the scaled value in case it happens to be a mul. That would be |
| // problematic if we've sunk a different mul for the scale, because then |
| // we'd end up sinking both muls. |
| if (AddrMode.BaseReg) { |
| Value *V = AddrMode.BaseReg; |
| if (V->getType() != IntPtrTy) |
| V = Builder.CreateIntCast(V, IntPtrTy, /*isSigned=*/true, "sunkaddr"); |
| |
| ResultIndex = V; |
| } |
| |
| // Add the scale value. |
| if (AddrMode.Scale) { |
| Value *V = AddrMode.ScaledReg; |
| if (V->getType() == IntPtrTy) { |
| // done. |
| } else if (cast<IntegerType>(IntPtrTy)->getBitWidth() < |
| cast<IntegerType>(V->getType())->getBitWidth()) { |
| V = Builder.CreateTrunc(V, IntPtrTy, "sunkaddr"); |
| } else { |
| // It is only safe to sign extend the BaseReg if we know that the math |
| // required to create it did not overflow before we extend it. Since |
| // the original IR value was tossed in favor of a constant back when |
| // the AddrMode was created we need to bail out gracefully if widths |
| // do not match instead of extending it. |
| Instruction *I = dyn_cast_or_null<Instruction>(ResultIndex); |
| if (I && (ResultIndex != AddrMode.BaseReg)) |
| I->eraseFromParent(); |
| return false; |
| } |
| |
| if (AddrMode.Scale != 1) |
| V = Builder.CreateMul(V, ConstantInt::get(IntPtrTy, AddrMode.Scale), |
| "sunkaddr"); |
| if (ResultIndex) |
| ResultIndex = Builder.CreateAdd(ResultIndex, V, "sunkaddr"); |
| else |
| ResultIndex = V; |
| } |
| |
| // Add in the Base Offset if present. |
| if (AddrMode.BaseOffs) { |
| Value *V = ConstantInt::get(IntPtrTy, AddrMode.BaseOffs); |
| if (ResultIndex) { |
| // We need to add this separately from the scale above to help with |
| // SDAG consecutive load/store merging. |
| if (ResultPtr->getType() != I8PtrTy) |
| ResultPtr = Builder.CreateBitCast(ResultPtr, I8PtrTy); |
| ResultPtr = Builder.CreateGEP(I8Ty, ResultPtr, ResultIndex, "sunkaddr"); |
| } |
| |
| ResultIndex = V; |
| } |
| |
| if (!ResultIndex) { |
| SunkAddr = ResultPtr; |
| } else { |
| if (ResultPtr->getType() != I8PtrTy) |
| ResultPtr = Builder.CreateBitCast(ResultPtr, I8PtrTy); |
| SunkAddr = Builder.CreateGEP(I8Ty, ResultPtr, ResultIndex, "sunkaddr"); |
| } |
| |
| if (SunkAddr->getType() != Addr->getType()) |
| SunkAddr = Builder.CreateBitCast(SunkAddr, Addr->getType()); |
| } |
| } else { |
| DEBUG(dbgs() << "CGP: SINKING nonlocal addrmode: " << AddrMode << " for " |
| << *MemoryInst << "\n"); |
| Type *IntPtrTy = DL->getIntPtrType(Addr->getType()); |
| Value *Result = nullptr; |
| |
| // Start with the base register. Do this first so that subsequent address |
| // matching finds it last, which will prevent it from trying to match it |
| // as the scaled value in case it happens to be a mul. That would be |
| // problematic if we've sunk a different mul for the scale, because then |
| // we'd end up sinking both muls. |
| if (AddrMode.BaseReg) { |
| Value *V = AddrMode.BaseReg; |
| if (V->getType()->isPointerTy()) |
| V = Builder.CreatePtrToInt(V, IntPtrTy, "sunkaddr"); |
| if (V->getType() != IntPtrTy) |
| V = Builder.CreateIntCast(V, IntPtrTy, /*isSigned=*/true, "sunkaddr"); |
| Result = V; |
| } |
| |
| // Add the scale value. |
| if (AddrMode.Scale) { |
| Value *V = AddrMode.ScaledReg; |
| if (V->getType() == IntPtrTy) { |
| // done. |
| } else if (V->getType()->isPointerTy()) { |
| V = Builder.CreatePtrToInt(V, IntPtrTy, "sunkaddr"); |
| } else if (cast<IntegerType>(IntPtrTy)->getBitWidth() < |
| cast<IntegerType>(V->getType())->getBitWidth()) { |
| V = Builder.CreateTrunc(V, IntPtrTy, "sunkaddr"); |
| } else { |
| // It is only safe to sign extend the BaseReg if we know that the math |
| // required to create it did not overflow before we extend it. Since |
| // the original IR value was tossed in favor of a constant back when |
| // the AddrMode was created we need to bail out gracefully if widths |
| // do not match instead of extending it. |
| Instruction *I = dyn_cast_or_null<Instruction>(Result); |
| if (I && (Result != AddrMode.BaseReg)) |
| I->eraseFromParent(); |
| return false; |
| } |
| if (AddrMode.Scale != 1) |
| V = Builder.CreateMul(V, ConstantInt::get(IntPtrTy, AddrMode.Scale), |
| "sunkaddr"); |
| if (Result) |
| Result = Builder.CreateAdd(Result, V, "sunkaddr"); |
| else |
| Result = V; |
| } |
| |
| // Add in the BaseGV if present. |
| if (AddrMode.BaseGV) { |
| Value *V = Builder.CreatePtrToInt(AddrMode.BaseGV, IntPtrTy, "sunkaddr"); |
| if (Result) |
| Result = Builder.CreateAdd(Result, V, "sunkaddr"); |
| else |
| Result = V; |
| } |
| |
| // Add in the Base Offset if present. |
| if (AddrMode.BaseOffs) { |
| Value *V = ConstantInt::get(IntPtrTy, AddrMode.BaseOffs); |
| if (Result) |
| Result = Builder.CreateAdd(Result, V, "sunkaddr"); |
| else |
| Result = V; |
| } |
| |
| if (!Result) |
| SunkAddr = Constant::getNullValue(Addr->getType()); |
| else |
| SunkAddr = Builder.CreateIntToPtr(Result, Addr->getType(), "sunkaddr"); |
| } |
| |
| MemoryInst->replaceUsesOfWith(Repl, SunkAddr); |
| |
| // If we have no uses, recursively delete the value and all dead instructions |
| // using it. |
| if (Repl->use_empty()) { |
| // This can cause recursive deletion, which can invalidate our iterator. |
| // Use a WeakVH to hold onto it in case this happens. |
| WeakVH IterHandle(CurInstIterator); |
| BasicBlock *BB = CurInstIterator->getParent(); |
| |
| RecursivelyDeleteTriviallyDeadInstructions(Repl, TLInfo); |
| |
| if (IterHandle != CurInstIterator) { |
| // If the iterator instruction was recursively deleted, start over at the |
| // start of the block. |
| CurInstIterator = BB->begin(); |
| SunkAddrs.clear(); |
| } |
| } |
| ++NumMemoryInsts; |
| return true; |
| } |
| |
| /// OptimizeInlineAsmInst - If there are any memory operands, use |
| /// OptimizeMemoryInst to sink their address computing into the block when |
| /// possible / profitable. |
| bool CodeGenPrepare::OptimizeInlineAsmInst(CallInst *CS) { |
| bool MadeChange = false; |
| |
| const TargetRegisterInfo *TRI = |
| TM->getSubtargetImpl(*CS->getParent()->getParent())->getRegisterInfo(); |
| TargetLowering::AsmOperandInfoVector TargetConstraints = |
| TLI->ParseConstraints(*DL, TRI, CS); |
| unsigned ArgNo = 0; |
| for (unsigned i = 0, e = TargetConstraints.size(); i != e; ++i) { |
| TargetLowering::AsmOperandInfo &OpInfo = TargetConstraints[i]; |
| |
| // Compute the constraint code and ConstraintType to use. |
| TLI->ComputeConstraintToUse(OpInfo, SDValue()); |
| |
| if (OpInfo.ConstraintType == TargetLowering::C_Memory && |
| OpInfo.isIndirect) { |
| Value *OpVal = CS->getArgOperand(ArgNo++); |
| MadeChange |= OptimizeMemoryInst(CS, OpVal, OpVal->getType(), ~0u); |
| } else if (OpInfo.Type == InlineAsm::isInput) |
| ArgNo++; |
| } |
| |
| return MadeChange; |
| } |
| |
| /// \brief Check if all the uses of \p Inst are equivalent (or free) zero or |
| /// sign extensions. |
| static bool hasSameExtUse(Instruction *Inst, const TargetLowering &TLI) { |
| assert(!Inst->use_empty() && "Input must have at least one use"); |
| const Instruction *FirstUser = cast<Instruction>(*Inst->user_begin()); |
| bool IsSExt = isa<SExtInst>(FirstUser); |
| Type *ExtTy = FirstUser->getType(); |
| for (const User *U : Inst->users()) { |
| const Instruction *UI = cast<Instruction>(U); |
| if ((IsSExt && !isa<SExtInst>(UI)) || (!IsSExt && !isa<ZExtInst>(UI))) |
| return false; |
| Type *CurTy = UI->getType(); |
| // Same input and output types: Same instruction after CSE. |
| if (CurTy == ExtTy) |
| continue; |
| |
| // If IsSExt is true, we are in this situation: |
| // a = Inst |
| // b = sext ty1 a to ty2 |
| // c = sext ty1 a to ty3 |
| // Assuming ty2 is shorter than ty3, this could be turned into: |
| // a = Inst |
| // b = sext ty1 a to ty2 |
| // c = sext ty2 b to ty3 |
| // However, the last sext is not free. |
| if (IsSExt) |
| return false; |
| |
| // This is a ZExt, maybe this is free to extend from one type to another. |
| // In that case, we would not account for a different use. |
| Type *NarrowTy; |
| Type *LargeTy; |
| if (ExtTy->getScalarType()->getIntegerBitWidth() > |
| CurTy->getScalarType()->getIntegerBitWidth()) { |
| NarrowTy = CurTy; |
| LargeTy = ExtTy; |
| } else { |
| NarrowTy = ExtTy; |
| LargeTy = CurTy; |
| } |
| |
| if (!TLI.isZExtFree(NarrowTy, LargeTy)) |
| return false; |
| } |
| // All uses are the same or can be derived from one another for free. |
| return true; |
| } |
| |
| /// \brief Try to form ExtLd by promoting \p Exts until they reach a |
| /// load instruction. |
| /// If an ext(load) can be formed, it is returned via \p LI for the load |
| /// and \p Inst for the extension. |
| /// Otherwise LI == nullptr and Inst == nullptr. |
| /// When some promotion happened, \p TPT contains the proper state to |
| /// revert them. |
| /// |
| /// \return true when promoting was necessary to expose the ext(load) |
| /// opportunity, false otherwise. |
| /// |
| /// Example: |
| /// \code |
| /// %ld = load i32* %addr |
| /// %add = add nuw i32 %ld, 4 |
| /// %zext = zext i32 %add to i64 |
| /// \endcode |
| /// => |
| /// \code |
| /// %ld = load i32* %addr |
| /// %zext = zext i32 %ld to i64 |
| /// %add = add nuw i64 %zext, 4 |
| /// \encode |
| /// Thanks to the promotion, we can match zext(load i32*) to i64. |
| bool CodeGenPrepare::ExtLdPromotion(TypePromotionTransaction &TPT, |
| LoadInst *&LI, Instruction *&Inst, |
| const SmallVectorImpl<Instruction *> &Exts, |
| unsigned CreatedInstsCost = 0) { |
| // Iterate over all the extensions to see if one form an ext(load). |
| for (auto I : Exts) { |
| // Check if we directly have ext(load). |
| if ((LI = dyn_cast<LoadInst>(I->getOperand(0)))) { |
| Inst = I; |
| // No promotion happened here. |
| return false; |
| } |
| // Check whether or not we want to do any promotion. |
| if (!TLI || !TLI->enableExtLdPromotion() || DisableExtLdPromotion) |
| continue; |
| // Get the action to perform the promotion. |
| TypePromotionHelper::Action TPH = TypePromotionHelper::getAction( |
| I, InsertedInsts, *TLI, PromotedInsts); |
| // Check if we can promote. |
| if (!TPH) |
| continue; |
| // Save the current state. |
| TypePromotionTransaction::ConstRestorationPt LastKnownGood = |
| TPT.getRestorationPoint(); |
| SmallVector<Instruction *, 4> NewExts; |
| unsigned NewCreatedInstsCost = 0; |
| unsigned ExtCost = !TLI->isExtFree(I); |
| // Promote. |
| Value *PromotedVal = TPH(I, TPT, PromotedInsts, NewCreatedInstsCost, |
| &NewExts, nullptr, *TLI); |
| assert(PromotedVal && |
| "TypePromotionHelper should have filtered out those cases"); |
| |
| // We would be able to merge only one extension in a load. |
| // Therefore, if we have more than 1 new extension we heuristically |
| // cut this search path, because it means we degrade the code quality. |
| // With exactly 2, the transformation is neutral, because we will merge |
| // one extension but leave one. However, we optimistically keep going, |
| // because the new extension may be removed too. |
| long long TotalCreatedInstsCost = CreatedInstsCost + NewCreatedInstsCost; |
| TotalCreatedInstsCost -= ExtCost; |
| if (!StressExtLdPromotion && |
| (TotalCreatedInstsCost > 1 || |
| !isPromotedInstructionLegal(*TLI, *DL, PromotedVal))) { |
| // The promotion is not profitable, rollback to the previous state. |
| TPT.rollback(LastKnownGood); |
| continue; |
| } |
| // The promotion is profitable. |
| // Check if it exposes an ext(load). |
| (void)ExtLdPromotion(TPT, LI, Inst, NewExts, TotalCreatedInstsCost); |
| if (LI && (StressExtLdPromotion || NewCreatedInstsCost <= ExtCost || |
| // If we have created a new extension, i.e., now we have two |
| // extensions. We must make sure one of them is merged with |
| // the load, otherwise we may degrade the code quality. |
| (LI->hasOneUse() || hasSameExtUse(LI, *TLI)))) |
| // Promotion happened. |
| return true; |
| // If this does not help to expose an ext(load) then, rollback. |
| TPT.rollback(LastKnownGood); |
| } |
| // None of the extension can form an ext(load). |
| LI = nullptr; |
| Inst = nullptr; |
| return false; |
| } |
| |
| /// MoveExtToFormExtLoad - Move a zext or sext fed by a load into the same |
| /// basic block as the load, unless conditions are unfavorable. This allows |
| /// SelectionDAG to fold the extend into the load. |
| /// \p I[in/out] the extension may be modified during the process if some |
| /// promotions apply. |
| /// |
| bool CodeGenPrepare::MoveExtToFormExtLoad(Instruction *&I) { |
| // Try to promote a chain of computation if it allows to form |
| // an extended load. |
| TypePromotionTransaction TPT; |
| TypePromotionTransaction::ConstRestorationPt LastKnownGood = |
| TPT.getRestorationPoint(); |
| SmallVector<Instruction *, 1> Exts; |
| Exts.push_back(I); |
| // Look for a load being extended. |
| LoadInst *LI = nullptr; |
| Instruction *OldExt = I; |
| bool HasPromoted = ExtLdPromotion(TPT, LI, I, Exts); |
| if (!LI || !I) { |
| assert(!HasPromoted && !LI && "If we did not match any load instruction " |
| "the code must remain the same"); |
| I = OldExt; |
| return false; |
| } |
| |
| // If they're already in the same block, there's nothing to do. |
| // Make the cheap checks first if we did not promote. |
| // If we promoted, we need to check if it is indeed profitable. |
| if (!HasPromoted && LI->getParent() == I->getParent()) |
| return false; |
| |
| EVT VT = TLI->getValueType(*DL, I->getType()); |
| EVT LoadVT = TLI->getValueType(*DL, LI->getType()); |
| |
| // If the load has other users and the truncate is not free, this probably |
| // isn't worthwhile. |
| if (!LI->hasOneUse() && TLI && |
| (TLI->isTypeLegal(LoadVT) || !TLI->isTypeLegal(VT)) && |
| !TLI->isTruncateFree(I->getType(), LI->getType())) { |
| I = OldExt; |
| TPT.rollback(LastKnownGood); |
| return false; |
| } |
| |
| // Check whether the target supports casts folded into loads. |
| unsigned LType; |
| if (isa<ZExtInst>(I)) |
| LType = ISD::ZEXTLOAD; |
| else { |
| assert(isa<SExtInst>(I) && "Unexpected ext type!"); |
| LType = ISD::SEXTLOAD; |
| } |
| if (TLI && !TLI->isLoadExtLegal(LType, VT, LoadVT)) { |
| I = OldExt; |
| TPT.rollback(LastKnownGood); |
| return false; |
| } |
| |
| // Move the extend into the same block as the load, so that SelectionDAG |
| // can fold it. |
| TPT.commit(); |
| I->removeFromParent(); |
| I->insertAfter(LI); |
| ++NumExtsMoved; |
| return true; |
| } |
| |
| bool CodeGenPrepare::OptimizeExtUses(Instruction *I) { |
| BasicBlock *DefBB = I->getParent(); |
| |
| // If the result of a {s|z}ext and its source are both live out, rewrite all |
| // other uses of the source with result of extension. |
| Value *Src = I->getOperand(0); |
| if (Src->hasOneUse()) |
| return false; |
| |
| // Only do this xform if truncating is free. |
| if (TLI && !TLI->isTruncateFree(I->getType(), Src->getType())) |
| return false; |
| |
| // Only safe to perform the optimization if the source is also defined in |
| // this block. |
| if (!isa<Instruction>(Src) || DefBB != cast<Instruction>(Src)->getParent()) |
| return false; |
| |
| bool DefIsLiveOut = false; |
| for (User *U : I->users()) { |
| Instruction *UI = cast<Instruction>(U); |
| |
| // Figure out which BB this ext is used in. |
| BasicBlock *UserBB = UI->getParent(); |
| if (UserBB == DefBB) continue; |
| DefIsLiveOut = true; |
| break; |
| } |
| if (!DefIsLiveOut) |
| return false; |
| |
| // Make sure none of the uses are PHI nodes. |
| for (User *U : Src->users()) { |
| Instruction *UI = cast<Instruction>(U); |
| BasicBlock *UserBB = UI->getParent(); |
| if (UserBB == DefBB) continue; |
| // Be conservative. We don't want this xform to end up introducing |
| // reloads just before load / store instructions. |
| if (isa<PHINode>(UI) || isa<LoadInst>(UI) || isa<StoreInst>(UI)) |
| return false; |
| } |
| |
| // InsertedTruncs - Only insert one trunc in each block once. |
| DenseMap<BasicBlock*, Instruction*> InsertedTruncs; |
| |
| bool MadeChange = false; |
| for (Use &U : Src->uses()) { |
| Instruction *User = cast<Instruction>(U.getUser()); |
| |
| // Figure out which BB this ext is used in. |
| BasicBlock *UserBB = User->getParent(); |
| if (UserBB == DefBB) continue; |
| |
| // Both src and def are live in this block. Rewrite the use. |
| Instruction *&InsertedTrunc = InsertedTruncs[UserBB]; |
| |
| if (!InsertedTrunc) { |
| BasicBlock::iterator InsertPt = UserBB->getFirstInsertionPt(); |
| InsertedTrunc = new TruncInst(I, Src->getType(), "", InsertPt); |
| InsertedInsts.insert(InsertedTrunc); |
| } |
| |
| // Replace a use of the {s|z}ext source with a use of the result. |
| U = InsertedTrunc; |
| ++NumExtUses; |
| MadeChange = true; |
| } |
| |
| return MadeChange; |
| } |
| |
| /// isFormingBranchFromSelectProfitable - Returns true if a SelectInst should be |
| /// turned into an explicit branch. |
| static bool isFormingBranchFromSelectProfitable(SelectInst *SI) { |
| // FIXME: This should use the same heuristics as IfConversion to determine |
| // whether a select is better represented as a branch. This requires that |
| // branch probability metadata is preserved for the select, which is not the |
| // case currently. |
| |
| CmpInst *Cmp = dyn_cast<CmpInst>(SI->getCondition()); |
| |
| // If the branch is predicted right, an out of order CPU can avoid blocking on |
| // the compare. Emit cmovs on compares with a memory operand as branches to |
| // avoid stalls on the load from memory. If the compare has more than one use |
| // there's probably another cmov or setcc around so it's not worth emitting a |
| // branch. |
| if (!Cmp) |
| return false; |
| |
| Value *CmpOp0 = Cmp->getOperand(0); |
| Value *CmpOp1 = Cmp->getOperand(1); |
| |
| // We check that the memory operand has one use to avoid uses of the loaded |
| // value directly after the compare, making branches unprofitable. |
| return Cmp->hasOneUse() && |
| ((isa<LoadInst>(CmpOp0) && CmpOp0->hasOneUse()) || |
| (isa<LoadInst>(CmpOp1) && CmpOp1->hasOneUse())); |
| } |
| |
| |
| /// If we have a SelectInst that will likely profit from branch prediction, |
| /// turn it into a branch. |
| bool CodeGenPrepare::OptimizeSelectInst(SelectInst *SI) { |
| bool VectorCond = !SI->getCondition()->getType()->isIntegerTy(1); |
| |
| // Can we convert the 'select' to CF ? |
| if (DisableSelectToBranch || OptSize || !TLI || VectorCond) |
| return false; |
| |
| TargetLowering::SelectSupportKind SelectKind; |
| if (VectorCond) |
| SelectKind = TargetLowering::VectorMaskSelect; |
| else if (SI->getType()->isVectorTy()) |
| SelectKind = TargetLowering::ScalarCondVectorVal; |
| else |
| SelectKind = TargetLowering::ScalarValSelect; |
| |
| // Do we have efficient codegen support for this kind of 'selects' ? |
| if (TLI->isSelectSupported(SelectKind)) { |
| // We have efficient codegen support for the select instruction. |
| // Check if it is profitable to keep this 'select'. |
| if (!TLI->isPredictableSelectExpensive() || |
| !isFormingBranchFromSelectProfitable(SI)) |
| return false; |
| } |
| |
| ModifiedDT = true; |
| |
| // First, we split the block containing the select into 2 blocks. |
| BasicBlock *StartBlock = SI->getParent(); |
| BasicBlock::iterator SplitPt = ++(BasicBlock::iterator(SI)); |
| BasicBlock *NextBlock = StartBlock->splitBasicBlock(SplitPt, "select.end"); |
| |
| // Create a new block serving as the landing pad for the branch. |
| BasicBlock *SmallBlock = BasicBlock::Create(SI->getContext(), "select.mid", |
| NextBlock->getParent(), NextBlock); |
| |
| // Move the unconditional branch from the block with the select in it into our |
| // landing pad block. |
| StartBlock->getTerminator()->eraseFromParent(); |
| BranchInst::Create(NextBlock, SmallBlock); |
| |
| // Insert the real conditional branch based on the original condition. |
| BranchInst::Create(NextBlock, SmallBlock, SI->getCondition(), SI); |
| |
| // The select itself is replaced with a PHI Node. |
| PHINode *PN = PHINode::Create(SI->getType(), 2, "", NextBlock->begin()); |
| PN->takeName(SI); |
| PN->addIncoming(SI->getTrueValue(), StartBlock); |
| PN->addIncoming(SI->getFalseValue(), SmallBlock); |
| SI->replaceAllUsesWith(PN); |
| SI->eraseFromParent(); |
| |
| // Instruct OptimizeBlock to skip to the next block. |
| CurInstIterator = StartBlock->end(); |
| ++NumSelectsExpanded; |
| return true; |
| } |
| |
| static bool isBroadcastShuffle(ShuffleVectorInst *SVI) { |
| SmallVector<int, 16> Mask(SVI->getShuffleMask()); |
| int SplatElem = -1; |
| for (unsigned i = 0; i < Mask.size(); ++i) { |
| if (SplatElem != -1 && Mask[i] != -1 && Mask[i] != SplatElem) |
| return false; |
| SplatElem = Mask[i]; |
| } |
| |
| return true; |
| } |
| |
| /// Some targets have expensive vector shifts if the lanes aren't all the same |
| /// (e.g. x86 only introduced "vpsllvd" and friends with AVX2). In these cases |
| /// it's often worth sinking a shufflevector splat down to its use so that |
| /// codegen can spot all lanes are identical. |
| bool CodeGenPrepare::OptimizeShuffleVectorInst(ShuffleVectorInst *SVI) { |
| BasicBlock *DefBB = SVI->getParent(); |
| |
| // Only do this xform if variable vector shifts are particularly expensive. |
| if (!TLI || !TLI->isVectorShiftByScalarCheap(SVI->getType())) |
| return false; |
| |
| // We only expect better codegen by sinking a shuffle if we can recognise a |
| // constant splat. |
| if (!isBroadcastShuffle(SVI)) |
| return false; |
| |
| // InsertedShuffles - Only insert a shuffle in each block once. |
| DenseMap<BasicBlock*, Instruction*> InsertedShuffles; |
| |
| bool MadeChange = false; |
| for (User *U : SVI->users()) { |
| Instruction *UI = cast<Instruction>(U); |
| |
| // Figure out which BB this ext is used in. |
| BasicBlock *UserBB = UI->getParent(); |
| if (UserBB == DefBB) continue; |
| |
| // For now only apply this when the splat is used by a shift instruction. |
| if (!UI->isShift()) continue; |
| |
| // Everything checks out, sink the shuffle if the user's block doesn't |
| // already have a copy. |
| Instruction *&InsertedShuffle = InsertedShuffles[UserBB]; |
| |
| if (!InsertedShuffle) { |
| BasicBlock::iterator InsertPt = UserBB->getFirstInsertionPt(); |
| InsertedShuffle = new ShuffleVectorInst(SVI->getOperand(0), |
| SVI->getOperand(1), |
| SVI->getOperand(2), "", InsertPt); |
| } |
| |
| UI->replaceUsesOfWith(SVI, InsertedShuffle); |
| MadeChange = true; |
| } |
| |
| // If we removed all uses, nuke the shuffle. |
| if (SVI->use_empty()) { |
| SVI->eraseFromParent(); |
| MadeChange = true; |
| } |
| |
| return MadeChange; |
| } |
| |
| namespace { |
| /// \brief Helper class to promote a scalar operation to a vector one. |
| /// This class is used to move downward extractelement transition. |
| /// E.g., |
| /// a = vector_op <2 x i32> |
| /// b = extractelement <2 x i32> a, i32 0 |
| /// c = scalar_op b |
| /// store c |
| /// |
| /// => |
| /// a = vector_op <2 x i32> |
| /// c = vector_op a (equivalent to scalar_op on the related lane) |
| /// * d = extractelement <2 x i32> c, i32 0 |
| /// * store d |
| /// Assuming both extractelement and store can be combine, we get rid of the |
| /// transition. |
| class VectorPromoteHelper { |
| /// DataLayout associated with the current module. |
| const DataLayout &DL; |
| |
| /// Used to perform some checks on the legality of vector operations. |
| const TargetLowering &TLI; |
| |
| /// Used to estimated the cost of the promoted chain. |
| const TargetTransformInfo &TTI; |
| |
| /// The transition being moved downwards. |
| Instruction *Transition; |
| /// The sequence of instructions to be promoted. |
| SmallVector<Instruction *, 4> InstsToBePromoted; |
| /// Cost of combining a store and an extract. |
| unsigned StoreExtractCombineCost; |
| /// Instruction that will be combined with the transition. |
| Instruction *CombineInst; |
| |
| /// \brief The instruction that represents the current end of the transition. |
| /// Since we are faking the promotion until we reach the end of the chain |
| /// of computation, we need a way to get the current end of the transition. |
| Instruction *getEndOfTransition() const { |
| if (InstsToBePromoted.empty()) |
| return Transition; |
| return InstsToBePromoted.back(); |
| } |
| |
| /// \brief Return the index of the original value in the transition. |
| /// E.g., for "extractelement <2 x i32> c, i32 1" the original value, |
| /// c, is at index 0. |
| unsigned getTransitionOriginalValueIdx() const { |
| assert(isa<ExtractElementInst>(Transition) && |
| "Other kind of transitions are not supported yet"); |
| return 0; |
| } |
| |
| /// \brief Return the index of the index in the transition. |
| /// E.g., for "extractelement <2 x i32> c, i32 0" the index |
| /// is at index 1. |
| unsigned getTransitionIdx() const { |
| assert(isa<ExtractElementInst>(Transition) && |
| "Other kind of transitions are not supported yet"); |
| return 1; |
| } |
| |
| /// \brief Get the type of the transition. |
| /// This is the type of the original value. |
| /// E.g., for "extractelement <2 x i32> c, i32 1" the type of the |
| /// transition is <2 x i32>. |
| Type *getTransitionType() const { |
| return Transition->getOperand(getTransitionOriginalValueIdx())->getType(); |
| } |
| |
| /// \brief Promote \p ToBePromoted by moving \p Def downward through. |
| /// I.e., we have the following sequence: |
| /// Def = Transition <ty1> a to <ty2> |
| /// b = ToBePromoted <ty2> Def, ... |
| /// => |
| /// b = ToBePromoted <ty1> a, ... |
| /// Def = Transition <ty1> ToBePromoted to <ty2> |
| void promoteImpl(Instruction *ToBePromoted); |
| |
| /// \brief Check whether or not it is profitable to promote all the |
| /// instructions enqueued to be promoted. |
| bool isProfitableToPromote() { |
| Value *ValIdx = Transition->getOperand(getTransitionOriginalValueIdx()); |
| unsigned Index = isa<ConstantInt>(ValIdx) |
| ? cast<ConstantInt>(ValIdx)->getZExtValue() |
| : -1; |
| Type *PromotedType = getTransitionType(); |
| |
| StoreInst *ST = cast<StoreInst>(CombineInst); |
| unsigned AS = ST->getPointerAddressSpace(); |
| unsigned Align = ST->getAlignment(); |
| // Check if this store is supported. |
| if (!TLI.allowsMisalignedMemoryAccesses( |
| TLI.getValueType(DL, ST->getValueOperand()->getType()), AS, |
| Align)) { |
| // If this is not supported, there is no way we can combine |
| // the extract with the store. |
| return false; |
| } |
| |
| // The scalar chain of computation has to pay for the transition |
| // scalar to vector. |
| // The vector chain has to account for the combining cost. |
| uint64_t ScalarCost = |
| TTI.getVectorInstrCost(Transition->getOpcode(), PromotedType, Index); |
| uint64_t VectorCost = StoreExtractCombineCost; |
| for (const auto &Inst : InstsToBePromoted) { |
| // Compute the cost. |
| // By construction, all instructions being promoted are arithmetic ones. |
| // Moreover, one argument is a constant that can be viewed as a splat |
| // constant. |
| Value *Arg0 = Inst->getOperand(0); |
| bool IsArg0Constant = isa<UndefValue>(Arg0) || isa<ConstantInt>(Arg0) || |
| isa<ConstantFP>(Arg0); |
| TargetTransformInfo::OperandValueKind Arg0OVK = |
| IsArg0Constant ? TargetTransformInfo::OK_UniformConstantValue |
| : TargetTransformInfo::OK_AnyValue; |
| TargetTransformInfo::OperandValueKind Arg1OVK = |
| !IsArg0Constant ? TargetTransformInfo::OK_UniformConstantValue |
| : TargetTransformInfo::OK_AnyValue; |
| ScalarCost += TTI.getArithmeticInstrCost( |
| Inst->getOpcode(), Inst->getType(), Arg0OVK, Arg1OVK); |
| VectorCost += TTI.getArithmeticInstrCost(Inst->getOpcode(), PromotedType, |
| Arg0OVK, Arg1OVK); |
| } |
| DEBUG(dbgs() << "Estimated cost of computation to be promoted:\nScalar: " |
| << ScalarCost << "\nVector: " << VectorCost << '\n'); |
| return ScalarCost > VectorCost; |
| } |
| |
| /// \brief Generate a constant vector with \p Val with the same |
| /// number of elements as the transition. |
| /// \p UseSplat defines whether or not \p Val should be replicated |
| /// accross the whole vector. |
| /// In other words, if UseSplat == true, we generate <Val, Val, ..., Val>, |
| /// otherwise we generate a vector with as many undef as possible: |
| /// <undef, ..., undef, Val, undef, ..., undef> where \p Val is only |
| /// used at the index of the extract. |
| Value *getConstantVector(Constant *Val, bool UseSplat) const { |
| unsigned ExtractIdx = UINT_MAX; |
| if (!UseSplat) { |
| // If we cannot determine where the constant must be, we have to |
| // use a splat constant. |
| Value *ValExtractIdx = Transition->getOperand(getTransitionIdx()); |
| if (ConstantInt *CstVal = dyn_cast<ConstantInt>(ValExtractIdx)) |
| ExtractIdx = CstVal->getSExtValue(); |
| else |
| UseSplat = true; |
| } |
| |
| unsigned End = getTransitionType()->getVectorNumElements(); |
| if (UseSplat) |
| return ConstantVector::getSplat(End, Val); |
| |
| SmallVector<Constant *, 4> ConstVec; |
| UndefValue *UndefVal = UndefValue::get(Val->getType()); |
| for (unsigned Idx = 0; Idx != End; ++Idx) { |
| if (Idx == ExtractIdx) |
| ConstVec.push_back(Val); |
| else |
| ConstVec.push_back(UndefVal); |
| } |
| return ConstantVector::get(ConstVec); |
| } |
| |
| /// \brief Check if promoting to a vector type an operand at \p OperandIdx |
| /// in \p Use can trigger undefined behavior. |
| static bool canCauseUndefinedBehavior(const Instruction *Use, |
| unsigned OperandIdx) { |
| // This is not safe to introduce undef when the operand is on |
| // the right hand side of a division-like instruction. |
| if (OperandIdx != 1) |
| return false; |
| switch (Use->getOpcode()) { |
| default: |
| return false; |
| case Instruction::SDiv: |
| case Instruction::UDiv: |
| case Instruction::SRem: |
| case Instruction::URem: |
| return true; |
| case Instruction::FDiv: |
| case Instruction::FRem: |
| return !Use->hasNoNaNs(); |
| } |
| llvm_unreachable(nullptr); |
| } |
| |
| public: |
| VectorPromoteHelper(const DataLayout &DL, const TargetLowering &TLI, |
| const TargetTransformInfo &TTI, Instruction *Transition, |
| unsigned CombineCost) |
| : DL(DL), TLI(TLI), TTI(TTI), Transition(Transition), |
| StoreExtractCombineCost(CombineCost), CombineInst(nullptr) { |
| assert(Transition && "Do not know how to promote null"); |
| } |
| |
| /// \brief Check if we can promote \p ToBePromoted to \p Type. |
| bool canPromote(const Instruction *ToBePromoted) const { |
| // We could support CastInst too. |
| return isa<BinaryOperator>(ToBePromoted); |
| } |
| |
| /// \brief Check if it is profitable to promote \p ToBePromoted |
| /// by moving downward the transition through. |
| bool shouldPromote(const Instruction *ToBePromoted) const { |
| // Promote only if all the operands can be statically expanded. |
| // Indeed, we do not want to introduce any new kind of transitions. |
| for (const Use &U : ToBePromoted->operands()) { |
| const Value *Val = U.get(); |
| if (Val == getEndOfTransition()) { |
| // If the use is a division and the transition is on the rhs, |
| // we cannot promote the operation, otherwise we may create a |
| // division by zero. |
| if (canCauseUndefinedBehavior(ToBePromoted, U.getOperandNo())) |
| return false; |
| continue; |
| } |
| if (!isa<ConstantInt>(Val) && !isa<UndefValue>(Val) && |
| !isa<ConstantFP>(Val)) |
| return false; |
| } |
| // Check that the resulting operation is legal. |
| int ISDOpcode = TLI.InstructionOpcodeToISD(ToBePromoted->getOpcode()); |
| if (!ISDOpcode) |
| return false; |
| return StressStoreExtract || |
| TLI.isOperationLegalOrCustom( |
| ISDOpcode, TLI.getValueType(DL, getTransitionType(), true)); |
| } |
| |
| /// \brief Check whether or not \p Use can be combined |
| /// with the transition. |
| /// I.e., is it possible to do Use(Transition) => AnotherUse? |
| bool canCombine(const Instruction *Use) { return isa<StoreInst>(Use); } |
| |
| /// \brief Record \p ToBePromoted as part of the chain to be promoted. |
| void enqueueForPromotion(Instruction *ToBePromoted) { |
| InstsToBePromoted.push_back(ToBePromoted); |
| } |
| |
| /// \brief Set the instruction that will be combined with the transition. |
| void recordCombineInstruction(Instruction *ToBeCombined) { |
| assert(canCombine(ToBeCombined) && "Unsupported instruction to combine"); |
| CombineInst = ToBeCombined; |
| } |
| |
| /// \brief Promote all the instructions enqueued for promotion if it is |
| /// is profitable. |
| /// \return True if the promotion happened, false otherwise. |
| bool promote() { |
| // Check if there is something to promote. |
| // Right now, if we do not have anything to combine with, |
| // we assume the promotion is not profitable. |
| if (InstsToBePromoted.empty() || !CombineInst) |
| return false; |
| |
| // Check cost. |
| if (!StressStoreExtract && !isProfitableToPromote()) |
| return false; |
| |
| // Promote. |
| for (auto &ToBePromoted : InstsToBePromoted) |
| promoteImpl(ToBePromoted); |
| InstsToBePromoted.clear(); |
| return true; |
| } |
| }; |
| } // End of anonymous namespace. |
| |
| void VectorPromoteHelper::promoteImpl(Instruction *ToBePromoted) { |
| // At this point, we know that all the operands of ToBePromoted but Def |
| // can be statically promoted. |
| // For Def, we need to use its parameter in ToBePromoted: |
| // b = ToBePromoted ty1 a |
| // Def = Transition ty1 b to ty2 |
| // Move the transition down. |
| // 1. Replace all uses of the promoted operation by the transition. |
| // = ... b => = ... Def. |
| assert(ToBePromoted->getType() == Transition->getType() && |
| "The type of the result of the transition does not match " |
| "the final type"); |
| ToBePromoted->replaceAllUsesWith(Transition); |
| // 2. Update the type of the uses. |
| // b = ToBePromoted ty2 Def => b = ToBePromoted ty1 Def. |
| Type *TransitionTy = getTransitionType(); |
| ToBePromoted->mutateType(TransitionTy); |
| // 3. Update all the operands of the promoted operation with promoted |
| // operands. |
| // b = ToBePromoted ty1 Def => b = ToBePromoted ty1 a. |
| for (Use &U : ToBePromoted->operands()) { |
| Value *Val = U.get(); |
| Value *NewVal = nullptr; |
| if (Val == Transition) |
| NewVal = Transition->getOperand(getTransitionOriginalValueIdx()); |
| else if (isa<UndefValue>(Val) || isa<ConstantInt>(Val) || |
| isa<ConstantFP>(Val)) { |
| // Use a splat constant if it is not safe to use undef. |
| NewVal = getConstantVector( |
| cast<Constant>(Val), |
| isa<UndefValue>(Val) || |
| canCauseUndefinedBehavior(ToBePromoted, U.getOperandNo())); |
| } else |
| llvm_unreachable("Did you modified shouldPromote and forgot to update " |
| "this?"); |
| ToBePromoted->setOperand(U.getOperandNo(), NewVal); |
| } |
| Transition->removeFromParent(); |
| Transition->insertAfter(ToBePromoted); |
| Transition->setOperand(getTransitionOriginalValueIdx(), ToBePromoted); |
| } |
| |
| /// Some targets can do store(extractelement) with one instruction. |
| /// Try to push the extractelement towards the stores when the target |
| /// has this feature and this is profitable. |
| bool CodeGenPrepare::OptimizeExtractElementInst(Instruction *Inst) { |
| unsigned CombineCost = UINT_MAX; |
| if (DisableStoreExtract || !TLI || |
| (!StressStoreExtract && |
| !TLI->canCombineStoreAndExtract(Inst->getOperand(0)->getType(), |
| Inst->getOperand(1), CombineCost))) |
| return false; |
| |
| // At this point we know that Inst is a vector to scalar transition. |
| // Try to move it down the def-use chain, until: |
| // - We can combine the transition with its single use |
| // => we got rid of the transition. |
| // - We escape the current basic block |
| // => we would need to check that we are moving it at a cheaper place and |
| // we do not do that for now. |
| BasicBlock *Parent = Inst->getParent(); |
| DEBUG(dbgs() << "Found an interesting transition: " << *Inst << '\n'); |
| VectorPromoteHelper VPH(*DL, *TLI, *TTI, Inst, CombineCost); |
| // If the transition has more than one use, assume this is not going to be |
| // beneficial. |
| while (Inst->hasOneUse()) { |
| Instruction *ToBePromoted = cast<Instruction>(*Inst->user_begin()); |
| DEBUG(dbgs() << "Use: " << *ToBePromoted << '\n'); |
| |
| if (ToBePromoted->getParent() != Parent) { |
| DEBUG(dbgs() << "Instruction to promote is in a different block (" |
| << ToBePromoted->getParent()->getName() |
| << ") than the transition (" << Parent->getName() << ").\n"); |
| return false; |
| } |
| |
| if (VPH.canCombine(ToBePromoted)) { |
| DEBUG(dbgs() << "Assume " << *Inst << '\n' |
| << "will be combined with: " << *ToBePromoted << '\n'); |
| VPH.recordCombineInstruction(ToBePromoted); |
| bool Changed = VPH.promote(); |
| NumStoreExtractExposed += Changed; |
| return Changed; |
| } |
| |
| DEBUG(dbgs() << "Try promoting.\n"); |
| if (!VPH.canPromote(ToBePromoted) || !VPH.shouldPromote(ToBePromoted)) |
| return false; |
| |
| DEBUG(dbgs() << "Promoting is possible... Enqueue for promotion!\n"); |
| |
| VPH.enqueueForPromotion(ToBePromoted); |
| Inst = ToBePromoted; |
| } |
| return false; |
| } |
| |
| bool CodeGenPrepare::OptimizeInst(Instruction *I, bool& ModifiedDT) { |
| // Bail out if we inserted the instruction to prevent optimizations from |
| // stepping on each other's toes. |
| if (InsertedInsts.count(I)) |
| return false; |
| |
| if (PHINode *P = dyn_cast<PHINode>(I)) { |
| // It is possible for very late stage optimizations (such as SimplifyCFG) |
| // to introduce PHI nodes too late to be cleaned up. If we detect such a |
| // trivial PHI, go ahead and zap it here. |
| if (Value *V = SimplifyInstruction(P, *DL, TLInfo, nullptr)) { |
| P->replaceAllUsesWith(V); |
| P->eraseFromParent(); |
| ++NumPHIsElim; |
| return true; |
| } |
| return false; |
| } |
| |
| if (CastInst *CI = dyn_cast<CastInst>(I)) { |
| // If the source of the cast is a constant, then this should have |
| // already been constant folded. The only reason NOT to constant fold |
| // it is if something (e.g. LSR) was careful to place the constant |
| // evaluation in a block other than then one that uses it (e.g. to hoist |
| // the address of globals out of a loop). If this is the case, we don't |
| // want to forward-subst the cast. |
| if (isa<Constant>(CI->getOperand(0))) |
| return false; |
| |
| if (TLI && OptimizeNoopCopyExpression(CI, *TLI, *DL)) |
| return true; |
| |
| if (isa<ZExtInst>(I) || isa<SExtInst>(I)) { |
| /// Sink a zext or sext into its user blocks if the target type doesn't |
| /// fit in one register |
| if (TLI && |
| TLI->getTypeAction(CI->getContext(), |
| TLI->getValueType(*DL, CI->getType())) == |
| TargetLowering::TypeExpandInteger) { |
| return SinkCast(CI); |
| } else { |
| bool MadeChange = MoveExtToFormExtLoad(I); |
| return MadeChange | OptimizeExtUses(I); |
| } |
| } |
| return false; |
| } |
| |
| if (CmpInst *CI = dyn_cast<CmpInst>(I)) |
| if (!TLI || !TLI->hasMultipleConditionRegisters()) |
| return OptimizeCmpExpression(CI); |
| |
| if (LoadInst *LI = dyn_cast<LoadInst>(I)) { |
| if (TLI) { |
| unsigned AS = LI->getPointerAddressSpace(); |
| return OptimizeMemoryInst(I, I->getOperand(0), LI->getType(), AS); |
| } |
| return false; |
| } |
| |
| if (StoreInst *SI = dyn_cast<StoreInst>(I)) { |
| if (TLI) { |
| unsigned AS = SI->getPointerAddressSpace(); |
| return OptimizeMemoryInst(I, SI->getOperand(1), |
| SI->getOperand(0)->getType(), AS); |
| } |
| return false; |
| } |
| |
| BinaryOperator *BinOp = dyn_cast<BinaryOperator>(I); |
| |
| if (BinOp && (BinOp->getOpcode() == Instruction::AShr || |
| BinOp->getOpcode() == Instruction::LShr)) { |
| ConstantInt *CI = dyn_cast<ConstantInt>(BinOp->getOperand(1)); |
| if (TLI && CI && TLI->hasExtractBitsInsn()) |
| return OptimizeExtractBits(BinOp, CI, *TLI, *DL); |
| |
| return false; |
| } |
| |
| if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(I)) { |
| if (GEPI->hasAllZeroIndices()) { |
| /// The GEP operand must be a pointer, so must its result -> BitCast |
| Instruction *NC = new BitCastInst(GEPI->getOperand(0), GEPI->getType(), |
| GEPI->getName(), GEPI); |
| GEPI->replaceAllUsesWith(NC); |
| GEPI->eraseFromParent(); |
| ++NumGEPsElim; |
| OptimizeInst(NC, ModifiedDT); |
| return true; |
| } |
| return false; |
| } |
| |
| if (CallInst *CI = dyn_cast<CallInst>(I)) |
| return OptimizeCallInst(CI, ModifiedDT); |
| |
| if (SelectInst *SI = dyn_cast<SelectInst>(I)) |
| return OptimizeSelectInst(SI); |
| |
| if (ShuffleVectorInst *SVI = dyn_cast<ShuffleVectorInst>(I)) |
| return OptimizeShuffleVectorInst(SVI); |
| |
| if (isa<ExtractElementInst>(I)) |
| return OptimizeExtractElementInst(I); |
| |
| return false; |
| } |
| |
| // In this pass we look for GEP and cast instructions that are used |
| // across basic blocks and rewrite them to improve basic-block-at-a-time |
| // selection. |
| bool CodeGenPrepare::OptimizeBlock(BasicBlock &BB, bool& ModifiedDT) { |
| SunkAddrs.clear(); |
| bool MadeChange = false; |
| |
| CurInstIterator = BB.begin(); |
| while (CurInstIterator != BB.end()) { |
| MadeChange |= OptimizeInst(CurInstIterator++, ModifiedDT); |
| if (ModifiedDT) |
| return true; |
| } |
| MadeChange |= DupRetToEnableTailCallOpts(&BB); |
| |
| return MadeChange; |
| } |
| |
| // llvm.dbg.value is far away from the value then iSel may not be able |
| // handle it properly. iSel will drop llvm.dbg.value if it can not |
| // find a node corresponding to the value. |
| bool CodeGenPrepare::PlaceDbgValues(Function &F) { |
| bool MadeChange = false; |
| for (BasicBlock &BB : F) { |
| Instruction *PrevNonDbgInst = nullptr; |
| for (BasicBlock::iterator BI = BB.begin(), BE = BB.end(); BI != BE;) { |
| Instruction *Insn = BI++; |
| DbgValueInst *DVI = dyn_cast<DbgValueInst>(Insn); |
| // Leave dbg.values that refer to an alloca alone. These |
| // instrinsics describe the address of a variable (= the alloca) |
| // being taken. They should not be moved next to the alloca |
| // (and to the beginning of the scope), but rather stay close to |
| // where said address is used. |
| if (!DVI || (DVI->getValue() && isa<AllocaInst>(DVI->getValue()))) { |
| PrevNonDbgInst = Insn; |
| continue; |
| } |
| |
| Instruction *VI = dyn_cast_or_null<Instruction>(DVI->getValue()); |
| if (VI && VI != PrevNonDbgInst && !VI->isTerminator()) { |
| DEBUG(dbgs() << "Moving Debug Value before :\n" << *DVI << ' ' << *VI); |
| DVI->removeFromParent(); |
| if (isa<PHINode>(VI)) |
| DVI->insertBefore(VI->getParent()->getFirstInsertionPt()); |
| else |
| DVI->insertAfter(VI); |
| MadeChange = true; |
| ++NumDbgValueMoved; |
| } |
| } |
| } |
| return MadeChange; |
| } |
| |
| // If there is a sequence that branches based on comparing a single bit |
| // against zero that can be combined into a single instruction, and the |
| // target supports folding these into a single instruction, sink the |
| // mask and compare into the branch uses. Do this before OptimizeBlock -> |
| // OptimizeInst -> OptimizeCmpExpression, which perturbs the pattern being |
| // searched for. |
| bool CodeGenPrepare::sinkAndCmp(Function &F) { |
| if (!EnableAndCmpSinking) |
| return false; |
| if (!TLI || !TLI->isMaskAndBranchFoldingLegal()) |
| return false; |
| bool MadeChange = false; |
| for (Function::iterator I = F.begin(), E = F.end(); I != E; ) { |
| BasicBlock *BB = I++; |
| |
| // Does this BB end with the following? |
| // %andVal = and %val, #single-bit-set |
| // %icmpVal = icmp %andResult, 0 |
| // br i1 %cmpVal label %dest1, label %dest2" |
| BranchInst *Brcc = dyn_cast<BranchInst>(BB->getTerminator()); |
| if (!Brcc || !Brcc->isConditional()) |
| continue; |
| ICmpInst *Cmp = dyn_cast<ICmpInst>(Brcc->getOperand(0)); |
| if (!Cmp || Cmp->getParent() != BB) |
| continue; |
| ConstantInt *Zero = dyn_cast<ConstantInt>(Cmp->getOperand(1)); |
| if (!Zero || !Zero->isZero()) |
| continue; |
| Instruction *And = dyn_cast<Instruction>(Cmp->getOperand(0)); |
| if (!And || And->getOpcode() != Instruction::And || And->getParent() != BB) |
| continue; |
| ConstantInt* Mask = dyn_cast<ConstantInt>(And->getOperand(1)); |
| if (!Mask || !Mask->getUniqueInteger().isPowerOf2()) |
| continue; |
| DEBUG(dbgs() << "found and; icmp ?,0; brcc\n"); DEBUG(BB->dump()); |
| |
| // Push the "and; icmp" for any users that are conditional branches. |
| // Since there can only be one branch use per BB, we don't need to keep |
| // track of which BBs we insert into. |
| for (Value::use_iterator UI = Cmp->use_begin(), E = Cmp->use_end(); |
| UI != E; ) { |
| Use &TheUse = *UI; |
| // Find brcc use. |
| BranchInst *BrccUser = dyn_cast<BranchInst>(*UI); |
| ++UI; |
| if (!BrccUser || !BrccUser->isConditional()) |
| continue; |
| BasicBlock *UserBB = BrccUser->getParent(); |
| if (UserBB == BB) continue; |
| DEBUG(dbgs() << "found Brcc use\n"); |
| |
| // Sink the "and; icmp" to use. |
| MadeChange = true; |
| BinaryOperator *NewAnd = |
| BinaryOperator::CreateAnd(And->getOperand(0), And->getOperand(1), "", |
| BrccUser); |
| CmpInst *NewCmp = |
| CmpInst::Create(Cmp->getOpcode(), Cmp->getPredicate(), NewAnd, Zero, |
| "", BrccUser); |
| TheUse = NewCmp; |
| ++NumAndCmpsMoved; |
| DEBUG(BrccUser->getParent()->dump()); |
| } |
| } |
| return MadeChange; |
| } |
| |
| /// \brief Retrieve the probabilities of a conditional branch. Returns true on |
| /// success, or returns false if no or invalid metadata was found. |
| static bool extractBranchMetadata(BranchInst *BI, |
| uint64_t &ProbTrue, uint64_t &ProbFalse) { |
| assert(BI->isConditional() && |
| "Looking for probabilities on unconditional branch?"); |
| auto *ProfileData = BI->getMetadata(LLVMContext::MD_prof); |
| if (!ProfileData || ProfileData->getNumOperands() != 3) |
| return false; |
| |
| const auto *CITrue = |
| mdconst::dyn_extract<ConstantInt>(ProfileData->getOperand(1)); |
| const auto *CIFalse = |
| mdconst::dyn_extract<ConstantInt>(ProfileData->getOperand(2)); |
| if (!CITrue || !CIFalse) |
| return false; |
| |
| ProbTrue = CITrue->getValue().getZExtValue(); |
| ProbFalse = CIFalse->getValue().getZExtValue(); |
| |
| return true; |
| } |
| |
| /// \brief Scale down both weights to fit into uint32_t. |
| static void scaleWeights(uint64_t &NewTrue, uint64_t &NewFalse) { |
| uint64_t NewMax = (NewTrue > NewFalse) ? NewTrue : NewFalse; |
| uint32_t Scale = (NewMax / UINT32_MAX) + 1; |
| NewTrue = NewTrue / Scale; |
| NewFalse = NewFalse / Scale; |
| } |
| |
| /// \brief Some targets prefer to split a conditional branch like: |
| /// \code |
| /// %0 = icmp ne i32 %a, 0 |
| /// %1 = icmp ne i32 %b, 0 |
| /// %or.cond = or i1 %0, %1 |
| /// br i1 %or.cond, label %TrueBB, label %FalseBB |
| /// \endcode |
| /// into multiple branch instructions like: |
| /// \code |
| /// bb1: |
| /// %0 = icmp ne i32 %a, 0 |
| /// br i1 %0, label %TrueBB, label %bb2 |
| /// bb2: |
| /// %1 = icmp ne i32 %b, 0 |
| /// br i1 %1, label %TrueBB, label %FalseBB |
| /// \endcode |
| /// This usually allows instruction selection to do even further optimizations |
| /// and combine the compare with the branch instruction. Currently this is |
| /// applied for targets which have "cheap" jump instructions. |
| /// |
| /// FIXME: Remove the (equivalent?) implementation in SelectionDAG. |
| /// |
| bool CodeGenPrepare::splitBranchCondition(Function &F) { |
| if (!TM || !TM->Options.EnableFastISel || !TLI || TLI->isJumpExpensive()) |
| return false; |
| |
| bool MadeChange = false; |
| for (auto &BB : F) { |
| // Does this BB end with the following? |
| // %cond1 = icmp|fcmp|binary instruction ... |
| // %cond2 = icmp|fcmp|binary instruction ... |
| // %cond.or = or|and i1 %cond1, cond2 |
| // br i1 %cond.or label %dest1, label %dest2" |
| BinaryOperator *LogicOp; |
| BasicBlock *TBB, *FBB; |
| if (!match(BB.getTerminator(), m_Br(m_OneUse(m_BinOp(LogicOp)), TBB, FBB))) |
| continue; |
| |
| unsigned Opc; |
| Value *Cond1, *Cond2; |
| if (match(LogicOp, m_And(m_OneUse(m_Value(Cond1)), |
| m_OneUse(m_Value(Cond2))))) |
| Opc = Instruction::And; |
| else if (match(LogicOp, m_Or(m_OneUse(m_Value(Cond1)), |
| m_OneUse(m_Value(Cond2))))) |
| Opc = Instruction::Or; |
| else |
| continue; |
| |
| if (!match(Cond1, m_CombineOr(m_Cmp(), m_BinOp())) || |
| !match(Cond2, m_CombineOr(m_Cmp(), m_BinOp())) ) |
| continue; |
| |
| DEBUG(dbgs() << "Before branch condition splitting\n"; BB.dump()); |
| |
| // Create a new BB. |
| auto *InsertBefore = std::next(Function::iterator(BB)) |
| .getNodePtrUnchecked(); |
| auto TmpBB = BasicBlock::Create(BB.getContext(), |
| BB.getName() + ".cond.split", |
| BB.getParent(), InsertBefore); |
| |
| // Update original basic block by using the first condition directly by the |
| // branch instruction and removing the no longer needed and/or instruction. |
| auto *Br1 = cast<BranchInst>(BB.getTerminator()); |
| Br1->setCondition(Cond1); |
| LogicOp->eraseFromParent(); |
| |
| // Depending on the conditon we have to either replace the true or the false |
| // successor of the original branch instruction. |
| if (Opc == Instruction::And) |
| Br1->setSuccessor(0, TmpBB); |
| else |
| Br1->setSuccessor(1, TmpBB); |
| |
| // Fill in the new basic block. |
| auto *Br2 = IRBuilder<>(TmpBB).CreateCondBr(Cond2, TBB, FBB); |
| if (auto *I = dyn_cast<Instruction>(Cond2)) { |
| I->removeFromParent(); |
| I->insertBefore(Br2); |
| } |
| |
| // Update PHI nodes in both successors. The original BB needs to be |
| // replaced in one succesor's PHI nodes, because the branch comes now from |
| // the newly generated BB (NewBB). In the other successor we need to add one |
| // incoming edge to the PHI nodes, because both branch instructions target |
| // now the same successor. Depending on the original branch condition |
| // (and/or) we have to swap the successors (TrueDest, FalseDest), so that |
| // we perfrom the correct update for the PHI nodes. |
| // This doesn't change the successor order of the just created branch |
| // instruction (or any other instruction). |
| if (Opc == Instruction::Or) |
| std::swap(TBB, FBB); |
| |
| // Replace the old BB with the new BB. |
| for (auto &I : *TBB) { |
| PHINode *PN = dyn_cast<PHINode>(&I); |
| if (!PN) |
| break; |
| int i; |
| while ((i = PN->getBasicBlockIndex(&BB)) >= 0) |
| PN->setIncomingBlock(i, TmpBB); |
| } |
| |
| // Add another incoming edge form the new BB. |
| for (auto &I : *FBB) { |
| PHINode *PN = dyn_cast<PHINode>(&I); |
| if (!PN) |
| break; |
| auto *Val = PN->getIncomingValueForBlock(&BB); |
| PN->addIncoming(Val, TmpBB); |
| } |
| |
| // Update the branch weights (from SelectionDAGBuilder:: |
| // FindMergedConditions). |
| if (Opc == Instruction::Or) { |
| // Codegen X | Y as: |
| // BB1: |
| // jmp_if_X TBB |
| // jmp TmpBB |
| // TmpBB: |
| // jmp_if_Y TBB |
| // jmp FBB |
| // |
| |
| // We have flexibility in setting Prob for BB1 and Prob for NewBB. |
| // The requirement is that |
| // TrueProb for BB1 + (FalseProb for BB1 * TrueProb for TmpBB) |
| // = TrueProb for orignal BB. |
| // Assuming the orignal weights are A and B, one choice is to set BB1's |
| // weights to A and A+2B, and set TmpBB's weights to A and 2B. This choice |
| // assumes that |
| // TrueProb for BB1 == FalseProb for BB1 * TrueProb for TmpBB. |
| // Another choice is to assume TrueProb for BB1 equals to TrueProb for |
| // TmpBB, but the math is more complicated. |
| uint64_t TrueWeight, FalseWeight; |
| if (extractBranchMetadata(Br1, TrueWeight, FalseWeight)) { |
| uint64_t NewTrueWeight = TrueWeight; |
| uint64_t NewFalseWeight = TrueWeight + 2 * FalseWeight; |
| scaleWeights(NewTrueWeight, NewFalseWeight); |
| Br1->setMetadata(LLVMContext::MD_prof, MDBuilder(Br1->getContext()) |
| .createBranchWeights(TrueWeight, FalseWeight)); |
| |
| NewTrueWeight = TrueWeight; |
| NewFalseWeight = 2 * FalseWeight; |
| scaleWeights(NewTrueWeight, NewFalseWeight); |
| Br2->setMetadata(LLVMContext::MD_prof, MDBuilder(Br2->getContext()) |
| .createBranchWeights(TrueWeight, FalseWeight)); |
| } |
| } else { |
| // Codegen X & Y as: |
| // BB1: |
| // jmp_if_X TmpBB |
| // jmp FBB |
| // TmpBB: |
| // jmp_if_Y TBB |
| // jmp FBB |
| // |
| // This requires creation of TmpBB after CurBB. |
| |
| // We have flexibility in setting Prob for BB1 and Prob for TmpBB. |
| // The requirement is that |
| // FalseProb for BB1 + (TrueProb for BB1 * FalseProb for TmpBB) |
| // = FalseProb for orignal BB. |
| // Assuming the orignal weights are A and B, one choice is to set BB1's |
| // weights to 2A+B and B, and set TmpBB's weights to 2A and B. This choice |
| // assumes that |
| // FalseProb for BB1 == TrueProb for BB1 * FalseProb for TmpBB. |
| uint64_t TrueWeight, FalseWeight; |
| if (extractBranchMetadata(Br1, TrueWeight, FalseWeight)) { |
| uint64_t NewTrueWeight = 2 * TrueWeight + FalseWeight; |
| uint64_t NewFalseWeight = FalseWeight; |
| scaleWeights(NewTrueWeight, NewFalseWeight); |
| Br1->setMetadata(LLVMContext::MD_prof, MDBuilder(Br1->getContext()) |
| .createBranchWeights(TrueWeight, FalseWeight)); |
| |
| NewTrueWeight = 2 * TrueWeight; |
| NewFalseWeight = FalseWeight; |
| scaleWeights(NewTrueWeight, NewFalseWeight); |
| Br2->setMetadata(LLVMContext::MD_prof, MDBuilder(Br2->getContext()) |
| .createBranchWeights(TrueWeight, FalseWeight)); |
| } |
| } |
| |
| // Note: No point in getting fancy here, since the DT info is never |
| // available to CodeGenPrepare. |
| ModifiedDT = true; |
| |
| MadeChange = true; |
| |
| DEBUG(dbgs() << "After branch condition splitting\n"; BB.dump(); |
| TmpBB->dump()); |
| } |
| return MadeChange; |
| } |