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//===- Utils.cpp - llvm-reduce utility functions --------------------------===//
//
// 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 file contains some utility functions supporting llvm-reduce.
//
//===----------------------------------------------------------------------===//
#include "Utils.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/GlobalAlias.h"
#include "llvm/IR/GlobalIFunc.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/Local.h"
using namespace llvm;
extern cl::OptionCategory LLVMReduceOptions;
cl::opt<bool> llvm::Verbose("verbose",
cl::desc("Print extra debugging information"),
cl::init(false), cl::cat(LLVMReduceOptions));
Value *llvm::getDefaultValue(Type *T) {
if (T->isVoidTy())
return PoisonValue::get(T);
if (auto *TET = dyn_cast<TargetExtType>(T)) {
if (TET->hasProperty(TargetExtType::HasZeroInit))
return ConstantTargetNone::get(TET);
return PoisonValue::get(TET);
}
return Constant::getNullValue(T);
}
bool llvm::hasAliasUse(Function &F) {
return any_of(F.users(), [](User *U) {
return isa<GlobalAlias>(U) || isa<GlobalIFunc>(U);
});
}
void llvm::simpleSimplifyCFG(Function &F, ArrayRef<BasicBlock *> BBs,
bool FoldBlockIntoPredecessor) {
for (BasicBlock *BB : BBs) {
ConstantFoldTerminator(BB);
if (FoldBlockIntoPredecessor)
MergeBlockIntoPredecessor(BB);
}
// Remove unreachable blocks
//
// removeUnreachableBlocks can't be used here, it will turn various undefined
// behavior into unreachables, but llvm-reduce was the thing that generated
// the undefined behavior, and we don't want it to kill the entire program.
SmallPtrSet<BasicBlock *, 16> Visited(llvm::from_range,
depth_first(&F.getEntryBlock()));
SmallVector<BasicBlock *, 16> Unreachable;
for (BasicBlock &BB : F) {
if (!Visited.count(&BB))
Unreachable.push_back(&BB);
}
// The dead BB's may be in a dead cycle or otherwise have references to each
// other. Because of this, we have to drop all references first, then delete
// them all at once.
for (BasicBlock *BB : Unreachable) {
for (BasicBlock *Successor : successors(&*BB))
if (Visited.count(Successor))
Successor->removePredecessor(&*BB, /*KeepOneInputPHIs=*/true);
BB->dropAllReferences();
}
for (BasicBlock *BB : Unreachable)
BB->eraseFromParent();
}
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