1 //===- LowerGuardIntrinsic.cpp - Lower the guard intrinsic ---------------===//
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
7 //===----------------------------------------------------------------------===//
9 // This pass lowers the llvm.experimental.guard intrinsic to a conditional call
10 // to @llvm.experimental.deoptimize. Once this happens, the guard can no longer
13 //===----------------------------------------------------------------------===//
15 #include "llvm/Transforms/Scalar/LowerGuardIntrinsic.h"
16 #include "llvm/ADT/SmallVector.h"
17 #include "llvm/Analysis/GuardUtils.h"
18 #include "llvm/IR/BasicBlock.h"
19 #include "llvm/IR/Function.h"
20 #include "llvm/IR/InstIterator.h"
21 #include "llvm/IR/Instructions.h"
22 #include "llvm/IR/Intrinsics.h"
23 #include "llvm/IR/Module.h"
24 #include "llvm/InitializePasses.h"
25 #include "llvm/Pass.h"
26 #include "llvm/Transforms/Scalar.h"
27 #include "llvm/Transforms/Utils/GuardUtils.h"
32 struct LowerGuardIntrinsicLegacyPass : public FunctionPass {
34 LowerGuardIntrinsicLegacyPass() : FunctionPass(ID) {
35 initializeLowerGuardIntrinsicLegacyPassPass(
36 *PassRegistry::getPassRegistry());
39 bool runOnFunction(Function &F) override;
43 static bool lowerGuardIntrinsic(Function &F) {
44 // Check if we can cheaply rule out the possibility of not having any work to
46 auto *GuardDecl = F.getParent()->getFunction(
47 Intrinsic::getName(Intrinsic::experimental_guard));
48 if (!GuardDecl || GuardDecl->use_empty())
51 SmallVector<CallInst *, 8> ToLower;
52 for (auto &I : instructions(F))
54 ToLower.push_back(cast<CallInst>(&I));
59 auto *DeoptIntrinsic = Intrinsic::getDeclaration(
60 F.getParent(), Intrinsic::experimental_deoptimize, {F.getReturnType()});
61 DeoptIntrinsic->setCallingConv(GuardDecl->getCallingConv());
63 for (auto *CI : ToLower) {
64 makeGuardControlFlowExplicit(DeoptIntrinsic, CI, false);
65 CI->eraseFromParent();
71 bool LowerGuardIntrinsicLegacyPass::runOnFunction(Function &F) {
72 return lowerGuardIntrinsic(F);
75 char LowerGuardIntrinsicLegacyPass::ID = 0;
76 INITIALIZE_PASS(LowerGuardIntrinsicLegacyPass, "lower-guard-intrinsic",
77 "Lower the guard intrinsic to normal control flow", false,
80 Pass *llvm::createLowerGuardIntrinsicPass() {
81 return new LowerGuardIntrinsicLegacyPass();
84 PreservedAnalyses LowerGuardIntrinsicPass::run(Function &F,
85 FunctionAnalysisManager &AM) {
86 if (lowerGuardIntrinsic(F))
87 return PreservedAnalyses::none();
89 return PreservedAnalyses::all();