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