99 lines
3.2 KiB
C++
99 lines
3.2 KiB
C++
//===- ObjCARCExpand.cpp - ObjC ARC Optimization --------------------------===//
|
|
//
|
|
// 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 ObjC ARC optimizations. ARC stands for Automatic
|
|
/// Reference Counting and is a system for managing reference counts for objects
|
|
/// in Objective C.
|
|
///
|
|
/// This specific file deals with early optimizations which perform certain
|
|
/// cleanup operations.
|
|
///
|
|
/// 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.
|
|
///
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#include "llvm/Analysis/ObjCARCAnalysisUtils.h"
|
|
#include "llvm/IR/Function.h"
|
|
#include "llvm/IR/InstIterator.h"
|
|
#include "llvm/IR/Instruction.h"
|
|
#include "llvm/IR/Instructions.h"
|
|
#include "llvm/IR/PassManager.h"
|
|
#include "llvm/IR/Value.h"
|
|
#include "llvm/Support/Casting.h"
|
|
#include "llvm/Support/Debug.h"
|
|
#include "llvm/Support/raw_ostream.h"
|
|
#include "llvm/Transforms/ObjCARC.h"
|
|
|
|
#define DEBUG_TYPE "objc-arc-expand"
|
|
|
|
using namespace llvm;
|
|
using namespace llvm::objcarc;
|
|
|
|
namespace {
|
|
static bool runImpl(Function &F) {
|
|
if (!EnableARCOpts)
|
|
return false;
|
|
|
|
// If nothing in the Module uses ARC, don't do anything.
|
|
if (!ModuleHasARC(*F.getParent()))
|
|
return false;
|
|
|
|
bool Changed = false;
|
|
|
|
LLVM_DEBUG(dbgs() << "ObjCARCExpand: Visiting Function: " << F.getName()
|
|
<< "\n");
|
|
|
|
for (Instruction &Inst : instructions(&F)) {
|
|
LLVM_DEBUG(dbgs() << "ObjCARCExpand: Visiting: " << Inst << "\n");
|
|
|
|
switch (GetBasicARCInstKind(&Inst)) {
|
|
case ARCInstKind::Retain:
|
|
case ARCInstKind::RetainRV:
|
|
case ARCInstKind::Autorelease:
|
|
case ARCInstKind::AutoreleaseRV:
|
|
case ARCInstKind::FusedRetainAutorelease:
|
|
case ARCInstKind::FusedRetainAutoreleaseRV: {
|
|
// These calls return their argument verbatim, as a low-level
|
|
// optimization. However, this makes high-level optimizations
|
|
// harder. Undo any uses of this optimization that the front-end
|
|
// emitted here. We'll redo them in the contract pass.
|
|
Changed = true;
|
|
Value *Value = cast<CallInst>(&Inst)->getArgOperand(0);
|
|
LLVM_DEBUG(dbgs() << "ObjCARCExpand: Old = " << Inst
|
|
<< "\n"
|
|
" New = "
|
|
<< *Value << "\n");
|
|
Inst.replaceAllUsesWith(Value);
|
|
break;
|
|
}
|
|
default:
|
|
break;
|
|
}
|
|
}
|
|
|
|
LLVM_DEBUG(dbgs() << "ObjCARCExpand: Finished List.\n\n");
|
|
|
|
return Changed;
|
|
}
|
|
|
|
} // namespace
|
|
|
|
PreservedAnalyses ObjCARCExpandPass::run(Function &F,
|
|
FunctionAnalysisManager &AM) {
|
|
if (!runImpl(F))
|
|
return PreservedAnalyses::all();
|
|
PreservedAnalyses PA;
|
|
PA.preserveSet<CFGAnalyses>();
|
|
return PA;
|
|
}
|