1 //===- LazyBranchProbabilityInfo.cpp - Lazy Branch Probability Analysis ---===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 // 9 // This is an alternative analysis pass to BranchProbabilityInfoWrapperPass. 10 // The difference is that with this pass the branch probabilities are not 11 // computed when the analysis pass is executed but rather when the BPI results 12 // is explicitly requested by the analysis client. 13 // 14 //===----------------------------------------------------------------------===// 15 16 #include "llvm/Analysis/LazyBranchProbabilityInfo.h" 17 #include "llvm/Analysis/LoopInfo.h" 18 #include "llvm/Analysis/TargetLibraryInfo.h" 19 #include "llvm/IR/Dominators.h" 20 #include "llvm/InitializePasses.h" 21 22 using namespace llvm; 23 24 #define DEBUG_TYPE "lazy-branch-prob" 25 26 INITIALIZE_PASS_BEGIN(LazyBranchProbabilityInfoPass, DEBUG_TYPE, 27 "Lazy Branch Probability Analysis", true, true) 28 INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass) 29 INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass) 30 INITIALIZE_PASS_END(LazyBranchProbabilityInfoPass, DEBUG_TYPE, 31 "Lazy Branch Probability Analysis", true, true) 32 33 char LazyBranchProbabilityInfoPass::ID = 0; 34 35 LazyBranchProbabilityInfoPass::LazyBranchProbabilityInfoPass() 36 : FunctionPass(ID) { 37 initializeLazyBranchProbabilityInfoPassPass(*PassRegistry::getPassRegistry()); 38 } 39 40 void LazyBranchProbabilityInfoPass::print(raw_ostream &OS, 41 const Module *) const { 42 LBPI->getCalculated().print(OS); 43 } 44 45 void LazyBranchProbabilityInfoPass::getAnalysisUsage(AnalysisUsage &AU) const { 46 // We require DT so it's available when LI is available. The LI updating code 47 // asserts that DT is also present so if we don't make sure that we have DT 48 // here, that assert will trigger. 49 AU.addRequiredTransitive<DominatorTreeWrapperPass>(); 50 AU.addRequiredTransitive<LoopInfoWrapperPass>(); 51 AU.addRequiredTransitive<TargetLibraryInfoWrapperPass>(); 52 AU.setPreservesAll(); 53 } 54 55 void LazyBranchProbabilityInfoPass::releaseMemory() { LBPI.reset(); } 56 57 bool LazyBranchProbabilityInfoPass::runOnFunction(Function &F) { 58 LoopInfo &LI = getAnalysis<LoopInfoWrapperPass>().getLoopInfo(); 59 TargetLibraryInfo &TLI = 60 getAnalysis<TargetLibraryInfoWrapperPass>().getTLI(F); 61 LBPI = std::make_unique<LazyBranchProbabilityInfo>(&F, &LI, &TLI); 62 return false; 63 } 64 65 void LazyBranchProbabilityInfoPass::getLazyBPIAnalysisUsage(AnalysisUsage &AU) { 66 AU.addRequiredTransitive<LazyBranchProbabilityInfoPass>(); 67 AU.addRequiredTransitive<LoopInfoWrapperPass>(); 68 AU.addRequiredTransitive<TargetLibraryInfoWrapperPass>(); 69 } 70 71 void llvm::initializeLazyBPIPassPass(PassRegistry &Registry) { 72 INITIALIZE_PASS_DEPENDENCY(LazyBranchProbabilityInfoPass); 73 INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass); 74 INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass); 75 } 76