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/IR/Function.h" 17 #include "llvm/IR/InstIterator.h" 18 #include "llvm/IR/Instructions.h" 19 #include "llvm/IR/Intrinsics.h" 20 #include "llvm/IR/Module.h" 21 #include "llvm/IR/PatternMatch.h" 22 #include "llvm/Transforms/Scalar.h" 23 24 using namespace llvm; 25 26 static bool lowerWidenableCondition(Function &F) { 27 // Check if we can cheaply rule out the possibility of not having any work to 28 // do. 29 auto *WCDecl = F.getParent()->getFunction( 30 Intrinsic::getName(Intrinsic::experimental_widenable_condition)); 31 if (!WCDecl || WCDecl->use_empty()) 32 return false; 33 34 using namespace llvm::PatternMatch; 35 SmallVector<CallInst *, 8> ToLower; 36 // Traverse through the users of WCDecl. 37 // This is presumably cheaper than traversing all instructions in the 38 // function. 39 for (auto *U : WCDecl->users()) 40 if (auto *CI = dyn_cast<CallInst>(U)) 41 if (CI->getFunction() == &F) 42 ToLower.push_back(CI); 43 44 if (ToLower.empty()) 45 return false; 46 47 for (auto *CI : ToLower) { 48 CI->replaceAllUsesWith(ConstantInt::getTrue(CI->getContext())); 49 CI->eraseFromParent(); 50 } 51 return true; 52 } 53 54 PreservedAnalyses LowerWidenableConditionPass::run(Function &F, 55 FunctionAnalysisManager &AM) { 56 if (lowerWidenableCondition(F)) 57 return PreservedAnalyses::none(); 58 59 return PreservedAnalyses::all(); 60 } 61