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llvm-mirror/lib/Analysis/ObjCARCInstKind.cpp
Chandler Carruth ae65e281f3 Update the file headers across all of the LLVM projects in the monorepo
to reflect the new license.

We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.

Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.

llvm-svn: 351636
2019-01-19 08:50:56 +00:00

671 lines
22 KiB
C++

//===- ARCInstKind.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 several utility functions used by various ARC
/// optimizations which are IMHO too big to be in a header file.
///
/// 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/ObjCARCInstKind.h"
#include "llvm/ADT/StringSwitch.h"
#include "llvm/Analysis/ObjCARCAnalysisUtils.h"
#include "llvm/IR/Intrinsics.h"
using namespace llvm;
using namespace llvm::objcarc;
raw_ostream &llvm::objcarc::operator<<(raw_ostream &OS,
const ARCInstKind Class) {
switch (Class) {
case ARCInstKind::Retain:
return OS << "ARCInstKind::Retain";
case ARCInstKind::RetainRV:
return OS << "ARCInstKind::RetainRV";
case ARCInstKind::ClaimRV:
return OS << "ARCInstKind::ClaimRV";
case ARCInstKind::RetainBlock:
return OS << "ARCInstKind::RetainBlock";
case ARCInstKind::Release:
return OS << "ARCInstKind::Release";
case ARCInstKind::Autorelease:
return OS << "ARCInstKind::Autorelease";
case ARCInstKind::AutoreleaseRV:
return OS << "ARCInstKind::AutoreleaseRV";
case ARCInstKind::AutoreleasepoolPush:
return OS << "ARCInstKind::AutoreleasepoolPush";
case ARCInstKind::AutoreleasepoolPop:
return OS << "ARCInstKind::AutoreleasepoolPop";
case ARCInstKind::NoopCast:
return OS << "ARCInstKind::NoopCast";
case ARCInstKind::FusedRetainAutorelease:
return OS << "ARCInstKind::FusedRetainAutorelease";
case ARCInstKind::FusedRetainAutoreleaseRV:
return OS << "ARCInstKind::FusedRetainAutoreleaseRV";
case ARCInstKind::LoadWeakRetained:
return OS << "ARCInstKind::LoadWeakRetained";
case ARCInstKind::StoreWeak:
return OS << "ARCInstKind::StoreWeak";
case ARCInstKind::InitWeak:
return OS << "ARCInstKind::InitWeak";
case ARCInstKind::LoadWeak:
return OS << "ARCInstKind::LoadWeak";
case ARCInstKind::MoveWeak:
return OS << "ARCInstKind::MoveWeak";
case ARCInstKind::CopyWeak:
return OS << "ARCInstKind::CopyWeak";
case ARCInstKind::DestroyWeak:
return OS << "ARCInstKind::DestroyWeak";
case ARCInstKind::StoreStrong:
return OS << "ARCInstKind::StoreStrong";
case ARCInstKind::CallOrUser:
return OS << "ARCInstKind::CallOrUser";
case ARCInstKind::Call:
return OS << "ARCInstKind::Call";
case ARCInstKind::User:
return OS << "ARCInstKind::User";
case ARCInstKind::IntrinsicUser:
return OS << "ARCInstKind::IntrinsicUser";
case ARCInstKind::None:
return OS << "ARCInstKind::None";
}
llvm_unreachable("Unknown instruction class!");
}
ARCInstKind llvm::objcarc::GetFunctionClass(const Function *F) {
Intrinsic::ID ID = F->getIntrinsicID();
switch (ID) {
default:
return ARCInstKind::CallOrUser;
case Intrinsic::objc_autorelease:
return ARCInstKind::Autorelease;
case Intrinsic::objc_autoreleasePoolPop:
return ARCInstKind::AutoreleasepoolPop;
case Intrinsic::objc_autoreleasePoolPush:
return ARCInstKind::AutoreleasepoolPush;
case Intrinsic::objc_autoreleaseReturnValue:
return ARCInstKind::AutoreleaseRV;
case Intrinsic::objc_copyWeak:
return ARCInstKind::CopyWeak;
case Intrinsic::objc_destroyWeak:
return ARCInstKind::DestroyWeak;
case Intrinsic::objc_initWeak:
return ARCInstKind::InitWeak;
case Intrinsic::objc_loadWeak:
return ARCInstKind::LoadWeak;
case Intrinsic::objc_loadWeakRetained:
return ARCInstKind::LoadWeakRetained;
case Intrinsic::objc_moveWeak:
return ARCInstKind::MoveWeak;
case Intrinsic::objc_release:
return ARCInstKind::Release;
case Intrinsic::objc_retain:
return ARCInstKind::Retain;
case Intrinsic::objc_retainAutorelease:
return ARCInstKind::FusedRetainAutorelease;
case Intrinsic::objc_retainAutoreleaseReturnValue:
return ARCInstKind::FusedRetainAutoreleaseRV;
case Intrinsic::objc_retainAutoreleasedReturnValue:
return ARCInstKind::RetainRV;
case Intrinsic::objc_retainBlock:
return ARCInstKind::RetainBlock;
case Intrinsic::objc_storeStrong:
return ARCInstKind::StoreStrong;
case Intrinsic::objc_storeWeak:
return ARCInstKind::StoreWeak;
case Intrinsic::objc_clang_arc_use:
return ARCInstKind::IntrinsicUser;
case Intrinsic::objc_unsafeClaimAutoreleasedReturnValue:
return ARCInstKind::ClaimRV;
case Intrinsic::objc_retainedObject:
return ARCInstKind::NoopCast;
case Intrinsic::objc_unretainedObject:
return ARCInstKind::NoopCast;
case Intrinsic::objc_unretainedPointer:
return ARCInstKind::NoopCast;
case Intrinsic::objc_retain_autorelease:
return ARCInstKind::FusedRetainAutorelease;
case Intrinsic::objc_sync_enter:
return ARCInstKind::User;
case Intrinsic::objc_sync_exit:
return ARCInstKind::User;
case Intrinsic::objc_arc_annotation_topdown_bbstart:
case Intrinsic::objc_arc_annotation_topdown_bbend:
case Intrinsic::objc_arc_annotation_bottomup_bbstart:
case Intrinsic::objc_arc_annotation_bottomup_bbend:
// Ignore annotation calls. This is important to stop the
// optimizer from treating annotations as uses which would
// make the state of the pointers they are attempting to
// elucidate to be incorrect.
return ARCInstKind::None;
}
}
// A whitelist of intrinsics that we know do not use objc pointers or decrement
// ref counts.
static bool isInertIntrinsic(unsigned ID) {
// TODO: Make this into a covered switch.
switch (ID) {
case Intrinsic::returnaddress:
case Intrinsic::addressofreturnaddress:
case Intrinsic::frameaddress:
case Intrinsic::stacksave:
case Intrinsic::stackrestore:
case Intrinsic::vastart:
case Intrinsic::vacopy:
case Intrinsic::vaend:
case Intrinsic::objectsize:
case Intrinsic::prefetch:
case Intrinsic::stackprotector:
case Intrinsic::eh_return_i32:
case Intrinsic::eh_return_i64:
case Intrinsic::eh_typeid_for:
case Intrinsic::eh_dwarf_cfa:
case Intrinsic::eh_sjlj_lsda:
case Intrinsic::eh_sjlj_functioncontext:
case Intrinsic::init_trampoline:
case Intrinsic::adjust_trampoline:
case Intrinsic::lifetime_start:
case Intrinsic::lifetime_end:
case Intrinsic::invariant_start:
case Intrinsic::invariant_end:
// Don't let dbg info affect our results.
case Intrinsic::dbg_declare:
case Intrinsic::dbg_value:
case Intrinsic::dbg_label:
// Short cut: Some intrinsics obviously don't use ObjC pointers.
return true;
default:
return false;
}
}
// A whitelist of intrinsics that we know do not use objc pointers or decrement
// ref counts.
static bool isUseOnlyIntrinsic(unsigned ID) {
// We are conservative and even though intrinsics are unlikely to touch
// reference counts, we white list them for safety.
//
// TODO: Expand this into a covered switch. There is a lot more here.
switch (ID) {
case Intrinsic::memcpy:
case Intrinsic::memmove:
case Intrinsic::memset:
return true;
default:
return false;
}
}
/// Determine what kind of construct V is.
ARCInstKind llvm::objcarc::GetARCInstKind(const Value *V) {
if (const Instruction *I = dyn_cast<Instruction>(V)) {
// Any instruction other than bitcast and gep with a pointer operand have a
// use of an objc pointer. Bitcasts, GEPs, Selects, PHIs transfer a pointer
// to a subsequent use, rather than using it themselves, in this sense.
// As a short cut, several other opcodes are known to have no pointer
// operands of interest. And ret is never followed by a release, so it's
// not interesting to examine.
switch (I->getOpcode()) {
case Instruction::Call: {
const CallInst *CI = cast<CallInst>(I);
// See if we have a function that we know something about.
if (const Function *F = CI->getCalledFunction()) {
ARCInstKind Class = GetFunctionClass(F);
if (Class != ARCInstKind::CallOrUser)
return Class;
Intrinsic::ID ID = F->getIntrinsicID();
if (isInertIntrinsic(ID))
return ARCInstKind::None;
if (isUseOnlyIntrinsic(ID))
return ARCInstKind::User;
}
// Otherwise, be conservative.
return GetCallSiteClass(CI);
}
case Instruction::Invoke:
// Otherwise, be conservative.
return GetCallSiteClass(cast<InvokeInst>(I));
case Instruction::BitCast:
case Instruction::GetElementPtr:
case Instruction::Select:
case Instruction::PHI:
case Instruction::Ret:
case Instruction::Br:
case Instruction::Switch:
case Instruction::IndirectBr:
case Instruction::Alloca:
case Instruction::VAArg:
case Instruction::Add:
case Instruction::FAdd:
case Instruction::Sub:
case Instruction::FSub:
case Instruction::Mul:
case Instruction::FMul:
case Instruction::SDiv:
case Instruction::UDiv:
case Instruction::FDiv:
case Instruction::SRem:
case Instruction::URem:
case Instruction::FRem:
case Instruction::Shl:
case Instruction::LShr:
case Instruction::AShr:
case Instruction::And:
case Instruction::Or:
case Instruction::Xor:
case Instruction::SExt:
case Instruction::ZExt:
case Instruction::Trunc:
case Instruction::IntToPtr:
case Instruction::FCmp:
case Instruction::FPTrunc:
case Instruction::FPExt:
case Instruction::FPToUI:
case Instruction::FPToSI:
case Instruction::UIToFP:
case Instruction::SIToFP:
case Instruction::InsertElement:
case Instruction::ExtractElement:
case Instruction::ShuffleVector:
case Instruction::ExtractValue:
break;
case Instruction::ICmp:
// Comparing a pointer with null, or any other constant, isn't an
// interesting use, because we don't care what the pointer points to, or
// about the values of any other dynamic reference-counted pointers.
if (IsPotentialRetainableObjPtr(I->getOperand(1)))
return ARCInstKind::User;
break;
default:
// For anything else, check all the operands.
// Note that this includes both operands of a Store: while the first
// operand isn't actually being dereferenced, it is being stored to
// memory where we can no longer track who might read it and dereference
// it, so we have to consider it potentially used.
for (User::const_op_iterator OI = I->op_begin(), OE = I->op_end();
OI != OE; ++OI)
if (IsPotentialRetainableObjPtr(*OI))
return ARCInstKind::User;
}
}
// Otherwise, it's totally inert for ARC purposes.
return ARCInstKind::None;
}
/// Test if the given class is a kind of user.
bool llvm::objcarc::IsUser(ARCInstKind Class) {
switch (Class) {
case ARCInstKind::User:
case ARCInstKind::CallOrUser:
case ARCInstKind::IntrinsicUser:
return true;
case ARCInstKind::Retain:
case ARCInstKind::RetainRV:
case ARCInstKind::RetainBlock:
case ARCInstKind::Release:
case ARCInstKind::Autorelease:
case ARCInstKind::AutoreleaseRV:
case ARCInstKind::AutoreleasepoolPush:
case ARCInstKind::AutoreleasepoolPop:
case ARCInstKind::NoopCast:
case ARCInstKind::FusedRetainAutorelease:
case ARCInstKind::FusedRetainAutoreleaseRV:
case ARCInstKind::LoadWeakRetained:
case ARCInstKind::StoreWeak:
case ARCInstKind::InitWeak:
case ARCInstKind::LoadWeak:
case ARCInstKind::MoveWeak:
case ARCInstKind::CopyWeak:
case ARCInstKind::DestroyWeak:
case ARCInstKind::StoreStrong:
case ARCInstKind::Call:
case ARCInstKind::None:
case ARCInstKind::ClaimRV:
return false;
}
llvm_unreachable("covered switch isn't covered?");
}
/// Test if the given class is objc_retain or equivalent.
bool llvm::objcarc::IsRetain(ARCInstKind Class) {
switch (Class) {
case ARCInstKind::Retain:
case ARCInstKind::RetainRV:
return true;
// I believe we treat retain block as not a retain since it can copy its
// block.
case ARCInstKind::RetainBlock:
case ARCInstKind::Release:
case ARCInstKind::Autorelease:
case ARCInstKind::AutoreleaseRV:
case ARCInstKind::AutoreleasepoolPush:
case ARCInstKind::AutoreleasepoolPop:
case ARCInstKind::NoopCast:
case ARCInstKind::FusedRetainAutorelease:
case ARCInstKind::FusedRetainAutoreleaseRV:
case ARCInstKind::LoadWeakRetained:
case ARCInstKind::StoreWeak:
case ARCInstKind::InitWeak:
case ARCInstKind::LoadWeak:
case ARCInstKind::MoveWeak:
case ARCInstKind::CopyWeak:
case ARCInstKind::DestroyWeak:
case ARCInstKind::StoreStrong:
case ARCInstKind::IntrinsicUser:
case ARCInstKind::CallOrUser:
case ARCInstKind::Call:
case ARCInstKind::User:
case ARCInstKind::None:
case ARCInstKind::ClaimRV:
return false;
}
llvm_unreachable("covered switch isn't covered?");
}
/// Test if the given class is objc_autorelease or equivalent.
bool llvm::objcarc::IsAutorelease(ARCInstKind Class) {
switch (Class) {
case ARCInstKind::Autorelease:
case ARCInstKind::AutoreleaseRV:
return true;
case ARCInstKind::Retain:
case ARCInstKind::RetainRV:
case ARCInstKind::ClaimRV:
case ARCInstKind::RetainBlock:
case ARCInstKind::Release:
case ARCInstKind::AutoreleasepoolPush:
case ARCInstKind::AutoreleasepoolPop:
case ARCInstKind::NoopCast:
case ARCInstKind::FusedRetainAutorelease:
case ARCInstKind::FusedRetainAutoreleaseRV:
case ARCInstKind::LoadWeakRetained:
case ARCInstKind::StoreWeak:
case ARCInstKind::InitWeak:
case ARCInstKind::LoadWeak:
case ARCInstKind::MoveWeak:
case ARCInstKind::CopyWeak:
case ARCInstKind::DestroyWeak:
case ARCInstKind::StoreStrong:
case ARCInstKind::IntrinsicUser:
case ARCInstKind::CallOrUser:
case ARCInstKind::Call:
case ARCInstKind::User:
case ARCInstKind::None:
return false;
}
llvm_unreachable("covered switch isn't covered?");
}
/// Test if the given class represents instructions which return their
/// argument verbatim.
bool llvm::objcarc::IsForwarding(ARCInstKind Class) {
switch (Class) {
case ARCInstKind::Retain:
case ARCInstKind::RetainRV:
case ARCInstKind::ClaimRV:
case ARCInstKind::Autorelease:
case ARCInstKind::AutoreleaseRV:
case ARCInstKind::NoopCast:
return true;
case ARCInstKind::RetainBlock:
case ARCInstKind::Release:
case ARCInstKind::AutoreleasepoolPush:
case ARCInstKind::AutoreleasepoolPop:
case ARCInstKind::FusedRetainAutorelease:
case ARCInstKind::FusedRetainAutoreleaseRV:
case ARCInstKind::LoadWeakRetained:
case ARCInstKind::StoreWeak:
case ARCInstKind::InitWeak:
case ARCInstKind::LoadWeak:
case ARCInstKind::MoveWeak:
case ARCInstKind::CopyWeak:
case ARCInstKind::DestroyWeak:
case ARCInstKind::StoreStrong:
case ARCInstKind::IntrinsicUser:
case ARCInstKind::CallOrUser:
case ARCInstKind::Call:
case ARCInstKind::User:
case ARCInstKind::None:
return false;
}
llvm_unreachable("covered switch isn't covered?");
}
/// Test if the given class represents instructions which do nothing if
/// passed a null pointer.
bool llvm::objcarc::IsNoopOnNull(ARCInstKind Class) {
switch (Class) {
case ARCInstKind::Retain:
case ARCInstKind::RetainRV:
case ARCInstKind::ClaimRV:
case ARCInstKind::Release:
case ARCInstKind::Autorelease:
case ARCInstKind::AutoreleaseRV:
case ARCInstKind::RetainBlock:
return true;
case ARCInstKind::AutoreleasepoolPush:
case ARCInstKind::AutoreleasepoolPop:
case ARCInstKind::FusedRetainAutorelease:
case ARCInstKind::FusedRetainAutoreleaseRV:
case ARCInstKind::LoadWeakRetained:
case ARCInstKind::StoreWeak:
case ARCInstKind::InitWeak:
case ARCInstKind::LoadWeak:
case ARCInstKind::MoveWeak:
case ARCInstKind::CopyWeak:
case ARCInstKind::DestroyWeak:
case ARCInstKind::StoreStrong:
case ARCInstKind::IntrinsicUser:
case ARCInstKind::CallOrUser:
case ARCInstKind::Call:
case ARCInstKind::User:
case ARCInstKind::None:
case ARCInstKind::NoopCast:
return false;
}
llvm_unreachable("covered switch isn't covered?");
}
/// Test if the given class represents instructions which are always safe
/// to mark with the "tail" keyword.
bool llvm::objcarc::IsAlwaysTail(ARCInstKind Class) {
// ARCInstKind::RetainBlock may be given a stack argument.
switch (Class) {
case ARCInstKind::Retain:
case ARCInstKind::RetainRV:
case ARCInstKind::ClaimRV:
case ARCInstKind::AutoreleaseRV:
return true;
case ARCInstKind::Release:
case ARCInstKind::Autorelease:
case ARCInstKind::RetainBlock:
case ARCInstKind::AutoreleasepoolPush:
case ARCInstKind::AutoreleasepoolPop:
case ARCInstKind::FusedRetainAutorelease:
case ARCInstKind::FusedRetainAutoreleaseRV:
case ARCInstKind::LoadWeakRetained:
case ARCInstKind::StoreWeak:
case ARCInstKind::InitWeak:
case ARCInstKind::LoadWeak:
case ARCInstKind::MoveWeak:
case ARCInstKind::CopyWeak:
case ARCInstKind::DestroyWeak:
case ARCInstKind::StoreStrong:
case ARCInstKind::IntrinsicUser:
case ARCInstKind::CallOrUser:
case ARCInstKind::Call:
case ARCInstKind::User:
case ARCInstKind::None:
case ARCInstKind::NoopCast:
return false;
}
llvm_unreachable("covered switch isn't covered?");
}
/// Test if the given class represents instructions which are never safe
/// to mark with the "tail" keyword.
bool llvm::objcarc::IsNeverTail(ARCInstKind Class) {
/// It is never safe to tail call objc_autorelease since by tail calling
/// objc_autorelease: fast autoreleasing causing our object to be potentially
/// reclaimed from the autorelease pool which violates the semantics of
/// __autoreleasing types in ARC.
switch (Class) {
case ARCInstKind::Autorelease:
return true;
case ARCInstKind::Retain:
case ARCInstKind::RetainRV:
case ARCInstKind::ClaimRV:
case ARCInstKind::AutoreleaseRV:
case ARCInstKind::Release:
case ARCInstKind::RetainBlock:
case ARCInstKind::AutoreleasepoolPush:
case ARCInstKind::AutoreleasepoolPop:
case ARCInstKind::FusedRetainAutorelease:
case ARCInstKind::FusedRetainAutoreleaseRV:
case ARCInstKind::LoadWeakRetained:
case ARCInstKind::StoreWeak:
case ARCInstKind::InitWeak:
case ARCInstKind::LoadWeak:
case ARCInstKind::MoveWeak:
case ARCInstKind::CopyWeak:
case ARCInstKind::DestroyWeak:
case ARCInstKind::StoreStrong:
case ARCInstKind::IntrinsicUser:
case ARCInstKind::CallOrUser:
case ARCInstKind::Call:
case ARCInstKind::User:
case ARCInstKind::None:
case ARCInstKind::NoopCast:
return false;
}
llvm_unreachable("covered switch isn't covered?");
}
/// Test if the given class represents instructions which are always safe
/// to mark with the nounwind attribute.
bool llvm::objcarc::IsNoThrow(ARCInstKind Class) {
// objc_retainBlock is not nounwind because it calls user copy constructors
// which could theoretically throw.
switch (Class) {
case ARCInstKind::Retain:
case ARCInstKind::RetainRV:
case ARCInstKind::ClaimRV:
case ARCInstKind::Release:
case ARCInstKind::Autorelease:
case ARCInstKind::AutoreleaseRV:
case ARCInstKind::AutoreleasepoolPush:
case ARCInstKind::AutoreleasepoolPop:
return true;
case ARCInstKind::RetainBlock:
case ARCInstKind::FusedRetainAutorelease:
case ARCInstKind::FusedRetainAutoreleaseRV:
case ARCInstKind::LoadWeakRetained:
case ARCInstKind::StoreWeak:
case ARCInstKind::InitWeak:
case ARCInstKind::LoadWeak:
case ARCInstKind::MoveWeak:
case ARCInstKind::CopyWeak:
case ARCInstKind::DestroyWeak:
case ARCInstKind::StoreStrong:
case ARCInstKind::IntrinsicUser:
case ARCInstKind::CallOrUser:
case ARCInstKind::Call:
case ARCInstKind::User:
case ARCInstKind::None:
case ARCInstKind::NoopCast:
return false;
}
llvm_unreachable("covered switch isn't covered?");
}
/// Test whether the given instruction can autorelease any pointer or cause an
/// autoreleasepool pop.
///
/// This means that it *could* interrupt the RV optimization.
bool llvm::objcarc::CanInterruptRV(ARCInstKind Class) {
switch (Class) {
case ARCInstKind::AutoreleasepoolPop:
case ARCInstKind::CallOrUser:
case ARCInstKind::Call:
case ARCInstKind::Autorelease:
case ARCInstKind::AutoreleaseRV:
case ARCInstKind::FusedRetainAutorelease:
case ARCInstKind::FusedRetainAutoreleaseRV:
return true;
case ARCInstKind::Retain:
case ARCInstKind::RetainRV:
case ARCInstKind::ClaimRV:
case ARCInstKind::Release:
case ARCInstKind::AutoreleasepoolPush:
case ARCInstKind::RetainBlock:
case ARCInstKind::LoadWeakRetained:
case ARCInstKind::StoreWeak:
case ARCInstKind::InitWeak:
case ARCInstKind::LoadWeak:
case ARCInstKind::MoveWeak:
case ARCInstKind::CopyWeak:
case ARCInstKind::DestroyWeak:
case ARCInstKind::StoreStrong:
case ARCInstKind::IntrinsicUser:
case ARCInstKind::User:
case ARCInstKind::None:
case ARCInstKind::NoopCast:
return false;
}
llvm_unreachable("covered switch isn't covered?");
}
bool llvm::objcarc::CanDecrementRefCount(ARCInstKind Kind) {
switch (Kind) {
case ARCInstKind::Retain:
case ARCInstKind::RetainRV:
case ARCInstKind::Autorelease:
case ARCInstKind::AutoreleaseRV:
case ARCInstKind::NoopCast:
case ARCInstKind::FusedRetainAutorelease:
case ARCInstKind::FusedRetainAutoreleaseRV:
case ARCInstKind::IntrinsicUser:
case ARCInstKind::User:
case ARCInstKind::None:
return false;
// The cases below are conservative.
// RetainBlock can result in user defined copy constructors being called
// implying releases may occur.
case ARCInstKind::RetainBlock:
case ARCInstKind::Release:
case ARCInstKind::AutoreleasepoolPush:
case ARCInstKind::AutoreleasepoolPop:
case ARCInstKind::LoadWeakRetained:
case ARCInstKind::StoreWeak:
case ARCInstKind::InitWeak:
case ARCInstKind::LoadWeak:
case ARCInstKind::MoveWeak:
case ARCInstKind::CopyWeak:
case ARCInstKind::DestroyWeak:
case ARCInstKind::StoreStrong:
case ARCInstKind::CallOrUser:
case ARCInstKind::Call:
case ARCInstKind::ClaimRV:
return true;
}
llvm_unreachable("covered switch isn't covered?");
}