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/InitializePasses.h" 25 #include "llvm/Pass.h" 26 #include "llvm/Transforms/Scalar.h" 27 #include "llvm/Transforms/Utils/GuardUtils.h" 28 29 using namespace llvm; 30 31 namespace { 32 struct LowerWidenableConditionLegacyPass : public FunctionPass { 33 static char ID; 34 LowerWidenableConditionLegacyPass() : FunctionPass(ID) { 35 initializeLowerWidenableConditionLegacyPassPass( 36 *PassRegistry::getPassRegistry()); 37 } 38 39 bool runOnFunction(Function &F) override; 40 }; 41 } 42 43 static bool lowerWidenableCondition(Function &F) { 44 // Check if we can cheaply rule out the possibility of not having any work to 45 // do. 46 auto *WCDecl = F.getParent()->getFunction( 47 Intrinsic::getName(Intrinsic::experimental_widenable_condition)); 48 if (!WCDecl || WCDecl->use_empty()) 49 return false; 50 51 using namespace llvm::PatternMatch; 52 SmallVector<CallInst *, 8> ToLower; 53 for (auto &I : instructions(F)) 54 if (match(&I, m_Intrinsic<Intrinsic::experimental_widenable_condition>())) 55 ToLower.push_back(cast<CallInst>(&I)); 56 57 if (ToLower.empty()) 58 return false; 59 60 for (auto *CI : ToLower) { 61 CI->replaceAllUsesWith(ConstantInt::getTrue(CI->getContext())); 62 CI->eraseFromParent(); 63 } 64 return true; 65 } 66 67 bool LowerWidenableConditionLegacyPass::runOnFunction(Function &F) { 68 return lowerWidenableCondition(F); 69 } 70 71 char LowerWidenableConditionLegacyPass::ID = 0; 72 INITIALIZE_PASS(LowerWidenableConditionLegacyPass, "lower-widenable-condition", 73 "Lower the widenable condition to default true value", false, 74 false) 75 76 Pass *llvm::createLowerWidenableConditionPass() { 77 return new LowerWidenableConditionLegacyPass(); 78 } 79 80 PreservedAnalyses LowerWidenableConditionPass::run(Function &F, 81 FunctionAnalysisManager &AM) { 82 if (lowerWidenableCondition(F)) 83 return PreservedAnalyses::none(); 84 85 return PreservedAnalyses::all(); 86 } 87