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Diffstat (limited to 'lib/Transforms/Utils/LowerExpectIntrinsic.cpp')
| -rw-r--r-- | lib/Transforms/Utils/LowerExpectIntrinsic.cpp | 188 |
1 files changed, 0 insertions, 188 deletions
diff --git a/lib/Transforms/Utils/LowerExpectIntrinsic.cpp b/lib/Transforms/Utils/LowerExpectIntrinsic.cpp deleted file mode 100644 index ff89e74..0000000 --- a/lib/Transforms/Utils/LowerExpectIntrinsic.cpp +++ /dev/null @@ -1,188 +0,0 @@ -//===- LowerExpectIntrinsic.cpp - Lower expect intrinsic ------------------===// -// -// The LLVM Compiler Infrastructure -// -// This file is distributed under the University of Illinois Open Source -// License. See LICENSE.TXT for details. -// -//===----------------------------------------------------------------------===// -// -// This pass lowers the 'expect' intrinsic to LLVM metadata. -// -//===----------------------------------------------------------------------===// - -#include "llvm/Transforms/Scalar.h" -#include "llvm/ADT/Statistic.h" -#include "llvm/IR/BasicBlock.h" -#include "llvm/IR/Constants.h" -#include "llvm/IR/Function.h" -#include "llvm/IR/Instructions.h" -#include "llvm/IR/Intrinsics.h" -#include "llvm/IR/LLVMContext.h" -#include "llvm/IR/MDBuilder.h" -#include "llvm/IR/Metadata.h" -#include "llvm/Pass.h" -#include "llvm/Support/CommandLine.h" -#include "llvm/Support/Debug.h" -#include <vector> - -using namespace llvm; - -#define DEBUG_TYPE "lower-expect-intrinsic" - -STATISTIC(IfHandled, "Number of 'expect' intrinsic instructions handled"); - -static cl::opt<uint32_t> -LikelyBranchWeight("likely-branch-weight", cl::Hidden, cl::init(64), - cl::desc("Weight of the branch likely to be taken (default = 64)")); -static cl::opt<uint32_t> -UnlikelyBranchWeight("unlikely-branch-weight", cl::Hidden, cl::init(4), - cl::desc("Weight of the branch unlikely to be taken (default = 4)")); - -namespace { - - class LowerExpectIntrinsic : public FunctionPass { - - bool HandleSwitchExpect(SwitchInst *SI); - - bool HandleIfExpect(BranchInst *BI); - - public: - static char ID; - LowerExpectIntrinsic() : FunctionPass(ID) { - initializeLowerExpectIntrinsicPass(*PassRegistry::getPassRegistry()); - } - - bool runOnFunction(Function &F) override; - }; -} - - -bool LowerExpectIntrinsic::HandleSwitchExpect(SwitchInst *SI) { - CallInst *CI = dyn_cast<CallInst>(SI->getCondition()); - if (!CI) - return false; - - Function *Fn = CI->getCalledFunction(); - if (!Fn || Fn->getIntrinsicID() != Intrinsic::expect) - return false; - - Value *ArgValue = CI->getArgOperand(0); - ConstantInt *ExpectedValue = dyn_cast<ConstantInt>(CI->getArgOperand(1)); - if (!ExpectedValue) - return false; - - SwitchInst::CaseIt Case = SI->findCaseValue(ExpectedValue); - unsigned n = SI->getNumCases(); // +1 for default case. - std::vector<uint32_t> Weights(n + 1); - - Weights[0] = Case == SI->case_default() ? LikelyBranchWeight - : UnlikelyBranchWeight; - for (unsigned i = 0; i != n; ++i) - Weights[i + 1] = i == Case.getCaseIndex() ? LikelyBranchWeight - : UnlikelyBranchWeight; - - SI->setMetadata(LLVMContext::MD_prof, - MDBuilder(CI->getContext()).createBranchWeights(Weights)); - - SI->setCondition(ArgValue); - return true; -} - - -bool LowerExpectIntrinsic::HandleIfExpect(BranchInst *BI) { - if (BI->isUnconditional()) - return false; - - // Handle non-optimized IR code like: - // %expval = call i64 @llvm.expect.i64(i64 %conv1, i64 1) - // %tobool = icmp ne i64 %expval, 0 - // br i1 %tobool, label %if.then, label %if.end - // - // Or the following simpler case: - // %expval = call i1 @llvm.expect.i1(i1 %cmp, i1 1) - // br i1 %expval, label %if.then, label %if.end - - CallInst *CI; - - ICmpInst *CmpI = dyn_cast<ICmpInst>(BI->getCondition()); - if (!CmpI) { - CI = dyn_cast<CallInst>(BI->getCondition()); - } else { - if (CmpI->getPredicate() != CmpInst::ICMP_NE) - return false; - CI = dyn_cast<CallInst>(CmpI->getOperand(0)); - } - - if (!CI) - return false; - - Function *Fn = CI->getCalledFunction(); - if (!Fn || Fn->getIntrinsicID() != Intrinsic::expect) - return false; - - Value *ArgValue = CI->getArgOperand(0); - ConstantInt *ExpectedValue = dyn_cast<ConstantInt>(CI->getArgOperand(1)); - if (!ExpectedValue) - return false; - - MDBuilder MDB(CI->getContext()); - MDNode *Node; - - // If expect value is equal to 1 it means that we are more likely to take - // branch 0, in other case more likely is branch 1. - if (ExpectedValue->isOne()) - Node = MDB.createBranchWeights(LikelyBranchWeight, UnlikelyBranchWeight); - else - Node = MDB.createBranchWeights(UnlikelyBranchWeight, LikelyBranchWeight); - - BI->setMetadata(LLVMContext::MD_prof, Node); - - if (CmpI) - CmpI->setOperand(0, ArgValue); - else - BI->setCondition(ArgValue); - return true; -} - - -bool LowerExpectIntrinsic::runOnFunction(Function &F) { - for (Function::iterator I = F.begin(), E = F.end(); I != E;) { - BasicBlock *BB = I++; - - // Create "block_weights" metadata. - if (BranchInst *BI = dyn_cast<BranchInst>(BB->getTerminator())) { - if (HandleIfExpect(BI)) - IfHandled++; - } else if (SwitchInst *SI = dyn_cast<SwitchInst>(BB->getTerminator())) { - if (HandleSwitchExpect(SI)) - IfHandled++; - } - - // remove llvm.expect intrinsics. - for (BasicBlock::iterator BI = BB->begin(), BE = BB->end(); - BI != BE; ) { - CallInst *CI = dyn_cast<CallInst>(BI++); - if (!CI) - continue; - - Function *Fn = CI->getCalledFunction(); - if (Fn && Fn->getIntrinsicID() == Intrinsic::expect) { - Value *Exp = CI->getArgOperand(0); - CI->replaceAllUsesWith(Exp); - CI->eraseFromParent(); - } - } - } - - return false; -} - - -char LowerExpectIntrinsic::ID = 0; -INITIALIZE_PASS(LowerExpectIntrinsic, "lower-expect", "Lower 'expect' " - "Intrinsics", false, false) - -FunctionPass *llvm::createLowerExpectIntrinsicPass() { - return new LowerExpectIntrinsic(); -} |