94 lines
3.1 KiB
C
94 lines
3.1 KiB
C
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//===- ObjCARC.h - ObjC ARC Optimization --------------*- C++ -*-----------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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/// \file
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/// This file defines common definitions/declarations used by the ObjC ARC
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/// Optimizer. ARC stands for Automatic Reference Counting and is a system for
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/// managing reference counts for objects in Objective C.
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///
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/// WARNING: This file knows about certain library functions. It recognizes them
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/// by name, and hardwires knowledge of their semantics.
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///
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/// WARNING: This file knows about how certain Objective-C library functions are
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/// used. Naive LLVM IR transformations which would otherwise be
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/// behavior-preserving may break these assumptions.
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///
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_LIB_TRANSFORMS_OBJCARC_OBJCARC_H
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#define LLVM_LIB_TRANSFORMS_OBJCARC_OBJCARC_H
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#include "llvm/Analysis/ObjCARCAnalysisUtils.h"
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#include "llvm/Transforms/Utils/Local.h"
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namespace llvm {
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namespace objcarc {
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/// Erase the given instruction.
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///
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/// Many ObjC calls return their argument verbatim,
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/// so if it's such a call and the return value has users, replace them with the
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/// argument value.
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///
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static inline void EraseInstruction(Instruction *CI) {
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Value *OldArg = cast<CallInst>(CI)->getArgOperand(0);
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bool Unused = CI->use_empty();
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if (!Unused) {
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// Replace the return value with the argument.
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assert((IsForwarding(GetBasicARCInstKind(CI)) ||
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(IsNoopOnNull(GetBasicARCInstKind(CI)) &&
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IsNullOrUndef(OldArg->stripPointerCasts()))) &&
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"Can't delete non-forwarding instruction with users!");
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CI->replaceAllUsesWith(OldArg);
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}
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CI->eraseFromParent();
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if (Unused)
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RecursivelyDeleteTriviallyDeadInstructions(OldArg);
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}
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/// If Inst is a ReturnRV and its operand is a call or invoke, return the
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/// operand. Otherwise return null.
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static inline const Instruction *getreturnRVOperand(const Instruction &Inst,
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ARCInstKind Class) {
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if (Class != ARCInstKind::RetainRV)
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return nullptr;
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const auto *Opnd = Inst.getOperand(0)->stripPointerCasts();
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if (const auto *C = dyn_cast<CallInst>(Opnd))
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return C;
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return dyn_cast<InvokeInst>(Opnd);
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}
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/// Return the list of PHI nodes that are equivalent to PN.
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template<class PHINodeTy, class VectorTy>
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void getEquivalentPHIs(PHINodeTy &PN, VectorTy &PHIList) {
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auto *BB = PN.getParent();
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for (auto &P : BB->phis()) {
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if (&P == &PN) // Do not add PN to the list.
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continue;
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unsigned I = 0, E = PN.getNumIncomingValues();
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for (; I < E; ++I) {
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auto *BB = PN.getIncomingBlock(I);
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auto *PNOpnd = PN.getIncomingValue(I)->stripPointerCasts();
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auto *POpnd = P.getIncomingValueForBlock(BB)->stripPointerCasts();
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if (PNOpnd != POpnd)
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break;
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}
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if (I == E)
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PHIList.push_back(&P);
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}
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}
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} // end namespace objcarc
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} // end namespace llvm
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#endif
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