1 //===- LowerWidenableCondition.cpp - Lower the guard intrinsic ---------------===// 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 pass lowers the llvm.widenable.condition intrinsic to default value 10 // which is i1 true. 11 // 12 //===----------------------------------------------------------------------===// 13 14 #include "llvm/Transforms/Scalar/LowerWidenableCondition.h" 15 #include "llvm/ADT/SmallVector.h" 16 #include "llvm/Analysis/GuardUtils.h" 17 #include "llvm/IR/BasicBlock.h" 18 #include "llvm/IR/Function.h" 19 #include "llvm/IR/InstIterator.h" 20 #include "llvm/IR/Instructions.h" 21 #include "llvm/IR/Intrinsics.h" 22 #include "llvm/IR/Module.h" 23 #include "llvm/IR/PatternMatch.h" 24 #include "llvm/Pass.h" 25 #include "llvm/Transforms/Scalar.h" 26 #include "llvm/Transforms/Utils/GuardUtils.h" 27 28 using namespace llvm; 29 30 namespace { 31 struct LowerWidenableConditionLegacyPass : public FunctionPass { 32 static char ID; 33 LowerWidenableConditionLegacyPass() : FunctionPass(ID) { 34 initializeLowerWidenableConditionLegacyPassPass( 35 *PassRegistry::getPassRegistry()); 36 } 37 38 bool runOnFunction(Function &F) override; 39 }; 40 } 41 42 static bool lowerWidenableCondition(Function &F) { 43 // Check if we can cheaply rule out the possibility of not having any work to 44 // do. 45 auto *WCDecl = F.getParent()->getFunction( 46 Intrinsic::getName(Intrinsic::experimental_widenable_condition)); 47 if (!WCDecl || WCDecl->use_empty()) 48 return false; 49 50 using namespace llvm::PatternMatch; 51 SmallVector<CallInst *, 8> ToLower; 52 for (auto &I : instructions(F)) 53 if (match(&I, m_Intrinsic<Intrinsic::experimental_widenable_condition>())) 54 ToLower.push_back(cast<CallInst>(&I)); 55 56 if (ToLower.empty()) 57 return false; 58 59 for (auto *CI : ToLower) { 60 CI->replaceAllUsesWith(ConstantInt::getTrue(CI->getContext())); 61 CI->eraseFromParent(); 62 } 63 return true; 64 } 65 66 bool LowerWidenableConditionLegacyPass::runOnFunction(Function &F) { 67 return lowerWidenableCondition(F); 68 } 69 70 char LowerWidenableConditionLegacyPass::ID = 0; 71 INITIALIZE_PASS(LowerWidenableConditionLegacyPass, "lower-widenable-condition", 72 "Lower the widenable condition to default true value", false, 73 false) 74 75 Pass *llvm::createLowerWidenableConditionPass() { 76 return new LowerWidenableConditionLegacyPass(); 77 } 78 79 PreservedAnalyses LowerWidenableConditionPass::run(Function &F, 80 FunctionAnalysisManager &AM) { 81 if (lowerWidenableCondition(F)) 82 return PreservedAnalyses::none(); 83 84 return PreservedAnalyses::all(); 85 } 86