//===- LowerGuardIntrinsic.cpp - Lower the guard intrinsic ---------------===// // // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. // See https://llvm.org/LICENSE.txt for license information. // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception // //===----------------------------------------------------------------------===// // // This pass lowers the llvm.experimental.guard intrinsic to a conditional call // to @llvm.experimental.deoptimize. Once this happens, the guard can no longer // be widened. // //===----------------------------------------------------------------------===// #include "llvm/Transforms/Scalar/LowerGuardIntrinsic.h" #include "llvm/ADT/SmallVector.h" #include "llvm/Analysis/GuardUtils.h" #include "llvm/IR/BasicBlock.h" #include "llvm/IR/Function.h" #include "llvm/IR/InstIterator.h" #include "llvm/IR/Instructions.h" #include "llvm/IR/Intrinsics.h" #include "llvm/IR/Module.h" #include "llvm/InitializePasses.h" #include "llvm/Pass.h" #include "llvm/Transforms/Scalar.h" #include "llvm/Transforms/Utils/GuardUtils.h" using namespace llvm; namespace { struct LowerGuardIntrinsicLegacyPass : public FunctionPass { static char ID; LowerGuardIntrinsicLegacyPass() : FunctionPass(ID) { initializeLowerGuardIntrinsicLegacyPassPass( *PassRegistry::getPassRegistry()); } bool runOnFunction(Function &F) override; }; } static bool lowerGuardIntrinsic(Function &F) { // Check if we can cheaply rule out the possibility of not having any work to // do. auto *GuardDecl = F.getParent()->getFunction( Intrinsic::getName(Intrinsic::experimental_guard)); if (!GuardDecl || GuardDecl->use_empty()) return false; SmallVector<CallInst *, 8> ToLower; for (auto &I : instructions(F)) if (isGuard(&I)) ToLower.push_back(cast<CallInst>(&I)); if (ToLower.empty()) return false; auto *DeoptIntrinsic = Intrinsic::getDeclaration( F.getParent(), Intrinsic::experimental_deoptimize, {F.getReturnType()}); DeoptIntrinsic->setCallingConv(GuardDecl->getCallingConv()); for (auto *CI : ToLower) { makeGuardControlFlowExplicit(DeoptIntrinsic, CI, false); CI->eraseFromParent(); } return true; } bool LowerGuardIntrinsicLegacyPass::runOnFunction(Function &F) { return lowerGuardIntrinsic(F); } char LowerGuardIntrinsicLegacyPass::ID = 0; INITIALIZE_PASS(LowerGuardIntrinsicLegacyPass, "lower-guard-intrinsic", "Lower the guard intrinsic to normal control flow", false, false) Pass *llvm::createLowerGuardIntrinsicPass() { return new LowerGuardIntrinsicLegacyPass(); } PreservedAnalyses LowerGuardIntrinsicPass::run(Function &F, FunctionAnalysisManager &AM) { if (lowerGuardIntrinsic(F)) return PreservedAnalyses::none(); return PreservedAnalyses::all(); } |