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//===- ObjCARC.h - ObjC ARC Optimization --------------*- C++ -*-----------===//
//
// 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
//
//===----------------------------------------------------------------------===//
/// \file
/// This file defines common definitions/declarations used by the ObjC ARC
/// Optimizer. ARC stands for Automatic Reference Counting and is a system for
/// managing reference counts for objects in Objective C.
///
/// WARNING: This file knows about certain library functions. It recognizes them
/// by name, and hardwires knowledge of their semantics.
///
/// WARNING: This file knows about how certain Objective-C library functions are
/// used. Naive LLVM IR transformations which would otherwise be
/// behavior-preserving may break these assumptions.
///
//===----------------------------------------------------------------------===//
#ifndef LLVM_LIB_TRANSFORMS_OBJCARC_OBJCARC_H
#define LLVM_LIB_TRANSFORMS_OBJCARC_OBJCARC_H
#include "llvm/Analysis/ObjCARCAnalysisUtils.h"
#include "llvm/Transforms/Utils/Local.h"
namespace llvm {
namespace objcarc {
/// Erase the given instruction.
///
/// Many ObjC calls return their argument verbatim,
/// so if it's such a call and the return value has users, replace them with the
/// argument value.
///
static inline void EraseInstruction(Instruction *CI) {
Value *OldArg = cast<CallInst>(CI)->getArgOperand(0);
bool Unused = CI->use_empty();
if (!Unused) {
// Replace the return value with the argument.
assert((IsForwarding(GetBasicARCInstKind(CI)) ||
(IsNoopOnNull(GetBasicARCInstKind(CI)) &&
IsNullOrUndef(OldArg->stripPointerCasts()))) &&
"Can't delete non-forwarding instruction with users!");
CI->replaceAllUsesWith(OldArg);
}
CI->eraseFromParent();
if (Unused)
RecursivelyDeleteTriviallyDeadInstructions(OldArg);
}
/// If Inst is a ReturnRV and its operand is a call or invoke, return the
/// operand. Otherwise return null.
static inline const Instruction *getreturnRVOperand(const Instruction &Inst,
ARCInstKind Class) {
if (Class != ARCInstKind::RetainRV)
return nullptr;
const auto *Opnd = Inst.getOperand(0)->stripPointerCasts();
if (const auto *C = dyn_cast<CallInst>(Opnd))
return C;
return dyn_cast<InvokeInst>(Opnd);
}
/// Return the list of PHI nodes that are equivalent to PN.
template<class PHINodeTy, class VectorTy>
void getEquivalentPHIs(PHINodeTy &PN, VectorTy &PHIList) {
auto *BB = PN.getParent();
for (auto &P : BB->phis()) {
if (&P == &PN) // Do not add PN to the list.
continue;
unsigned I = 0, E = PN.getNumIncomingValues();
for (; I < E; ++I) {
auto *BB = PN.getIncomingBlock(I);
auto *PNOpnd = PN.getIncomingValue(I)->stripPointerCasts();
auto *POpnd = P.getIncomingValueForBlock(BB)->stripPointerCasts();
if (PNOpnd != POpnd)
break;
}
if (I == E)
PHIList.push_back(&P);
}
}
} // end namespace objcarc
} // end namespace llvm
#endif
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