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llvm-mirror/lib/Transforms/Scalar/LowerGuardIntrinsic.cpp
Chandler Carruth ae65e281f3 Update the file headers across all of the LLVM projects in the monorepo
to reflect the new license.

We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.

Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.

llvm-svn: 351636
2019-01-19 08:50:56 +00:00

90 lines
2.8 KiB
C++

//===- 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/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);
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();
}