freebsd-dev/contrib/llvm/lib/Analysis/ObjCARCInstKind.cpp

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//===- ARCInstKind.cpp - ObjC ARC Optimization ----------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
/// \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/Analysis/ObjCARCAnalysisUtils.h"
#include "llvm/ADT/StringSwitch.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::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) {
Function::const_arg_iterator AI = F->arg_begin(), AE = F->arg_end();
// No (mandatory) arguments.
if (AI == AE)
return StringSwitch<ARCInstKind>(F->getName())
.Case("objc_autoreleasePoolPush", ARCInstKind::AutoreleasepoolPush)
.Case("clang.arc.use", ARCInstKind::IntrinsicUser)
.Default(ARCInstKind::CallOrUser);
// One argument.
const Argument *A0 = &*AI++;
if (AI == AE)
// Argument is a pointer.
if (PointerType *PTy = dyn_cast<PointerType>(A0->getType())) {
Type *ETy = PTy->getElementType();
// Argument is i8*.
if (ETy->isIntegerTy(8))
return StringSwitch<ARCInstKind>(F->getName())
.Case("objc_retain", ARCInstKind::Retain)
.Case("objc_retainAutoreleasedReturnValue", ARCInstKind::RetainRV)
.Case("objc_retainBlock", ARCInstKind::RetainBlock)
.Case("objc_release", ARCInstKind::Release)
.Case("objc_autorelease", ARCInstKind::Autorelease)
.Case("objc_autoreleaseReturnValue", ARCInstKind::AutoreleaseRV)
.Case("objc_autoreleasePoolPop", ARCInstKind::AutoreleasepoolPop)
.Case("objc_retainedObject", ARCInstKind::NoopCast)
.Case("objc_unretainedObject", ARCInstKind::NoopCast)
.Case("objc_unretainedPointer", ARCInstKind::NoopCast)
.Case("objc_retain_autorelease",
ARCInstKind::FusedRetainAutorelease)
.Case("objc_retainAutorelease", ARCInstKind::FusedRetainAutorelease)
.Case("objc_retainAutoreleaseReturnValue",
ARCInstKind::FusedRetainAutoreleaseRV)
.Case("objc_sync_enter", ARCInstKind::User)
.Case("objc_sync_exit", ARCInstKind::User)
.Default(ARCInstKind::CallOrUser);
// Argument is i8**
if (PointerType *Pte = dyn_cast<PointerType>(ETy))
if (Pte->getElementType()->isIntegerTy(8))
return StringSwitch<ARCInstKind>(F->getName())
.Case("objc_loadWeakRetained", ARCInstKind::LoadWeakRetained)
.Case("objc_loadWeak", ARCInstKind::LoadWeak)
.Case("objc_destroyWeak", ARCInstKind::DestroyWeak)
.Default(ARCInstKind::CallOrUser);
}
// Two arguments, first is i8**.
const Argument *A1 = &*AI++;
if (AI == AE)
if (PointerType *PTy = dyn_cast<PointerType>(A0->getType()))
if (PointerType *Pte = dyn_cast<PointerType>(PTy->getElementType()))
if (Pte->getElementType()->isIntegerTy(8))
if (PointerType *PTy1 = dyn_cast<PointerType>(A1->getType())) {
Type *ETy1 = PTy1->getElementType();
// Second argument is i8*
if (ETy1->isIntegerTy(8))
return StringSwitch<ARCInstKind>(F->getName())
.Case("objc_storeWeak", ARCInstKind::StoreWeak)
.Case("objc_initWeak", ARCInstKind::InitWeak)
.Case("objc_storeStrong", ARCInstKind::StoreStrong)
.Default(ARCInstKind::CallOrUser);
// Second argument is i8**.
if (PointerType *Pte1 = dyn_cast<PointerType>(ETy1))
if (Pte1->getElementType()->isIntegerTy(8))
return StringSwitch<ARCInstKind>(F->getName())
.Case("objc_moveWeak", ARCInstKind::MoveWeak)
.Case("objc_copyWeak", ARCInstKind::CopyWeak)
// 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.
.Case("llvm.arc.annotation.topdown.bbstart",
ARCInstKind::None)
.Case("llvm.arc.annotation.topdown.bbend",
ARCInstKind::None)
.Case("llvm.arc.annotation.bottomup.bbstart",
ARCInstKind::None)
.Case("llvm.arc.annotation.bottomup.bbend",
ARCInstKind::None)
.Default(ARCInstKind::CallOrUser);
}
// Anything else.
return ARCInstKind::CallOrUser;
}
// 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::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:
// 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;
}
}
/// \brief 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;
}
/// \brief 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:
return false;
}
llvm_unreachable("covered switch isn't covered?");
}
/// \brief 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:
return false;
}
llvm_unreachable("covered switch isn't covered?");
}
/// \brief 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::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?");
}
/// \brief 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::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?");
}
/// \brief 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::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?");
}
/// \brief 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::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?");
}
/// \brief 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::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?");
}
/// \brief 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::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::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:
return true;
}
llvm_unreachable("covered switch isn't covered?");
}