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//===- LowerWidenableCondition.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.widenable.condition intrinsic to default value
// which is i1 true.
//
//===----------------------------------------------------------------------===//
#include "llvm/Transforms/Scalar/LowerWidenableCondition.h"
#include "llvm/ADT/SmallVector.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/IR/PatternMatch.h"
#include "llvm/InitializePasses.h"
#include "llvm/Pass.h"
#include "llvm/Transforms/Scalar.h"
using namespace llvm;
namespace {
struct LowerWidenableConditionLegacyPass : public FunctionPass {
static char ID;
LowerWidenableConditionLegacyPass() : FunctionPass(ID) {
initializeLowerWidenableConditionLegacyPassPass(
*PassRegistry::getPassRegistry());
}
bool runOnFunction(Function &F) override;
};
}
static bool lowerWidenableCondition(Function &F) {
// Check if we can cheaply rule out the possibility of not having any work to
// do.
auto *WCDecl = F.getParent()->getFunction(
Intrinsic::getName(Intrinsic::experimental_widenable_condition));
if (!WCDecl || WCDecl->use_empty())
return false;
using namespace llvm::PatternMatch;
SmallVector<CallInst *, 8> ToLower;
// Traverse through the users of WCDecl.
// This is presumably cheaper than traversing all instructions in the
// function.
for (auto *U : WCDecl->users())
if (auto *CI = dyn_cast<CallInst>(U))
if (CI->getFunction() == &F)
ToLower.push_back(CI);
if (ToLower.empty())
return false;
for (auto *CI : ToLower) {
CI->replaceAllUsesWith(ConstantInt::getTrue(CI->getContext()));
CI->eraseFromParent();
}
return true;
}
bool LowerWidenableConditionLegacyPass::runOnFunction(Function &F) {
return lowerWidenableCondition(F);
}
char LowerWidenableConditionLegacyPass::ID = 0;
INITIALIZE_PASS(LowerWidenableConditionLegacyPass, "lower-widenable-condition",
"Lower the widenable condition to default true value", false,
false)
Pass *llvm::createLowerWidenableConditionPass() {
return new LowerWidenableConditionLegacyPass();
}
PreservedAnalyses LowerWidenableConditionPass::run(Function &F,
FunctionAnalysisManager &AM) {
if (lowerWidenableCondition(F))
return PreservedAnalyses::none();
return PreservedAnalyses::all();
}
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