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Emit calls to objc_unsafeClaimAutoreleasedReturnValue when 

reclaiming a call result in order to ignore it or assign it
to an __unsafe_unretained variable.  This avoids adding
an unwanted retain/release pair when the return value is
not actually returned autoreleased (e.g. when it is returned
from a nonatomic getter or a typical collection accessor).

This runtime function is only available on the latest Apple
OS releases; the backwards-compatibility story is that you
don't get the optimization unless your deployment target is
recent enough.  Sorry.

rdar://20530049

llvm-svn: 258962
This commit is contained in:
John McCall 2016-01-27 18:32:30 +00:00
parent 14bf877e6b
commit e399e5bd3d
7 changed files with 717 additions and 186 deletions
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17
clang/include/clang/Basic/ObjCRuntime.h
View File

@ -308,6 +308,23 @@ public:
}
}
/// Is objc_unsafeClaimAutoreleasedReturnValue available?
bool hasARCUnsafeClaimAutoreleasedReturnValue() const {
switch (getKind()) {
case MacOSX:
return getVersion() >= VersionTuple(10, 11);
case iOS:
return getVersion() >= VersionTuple(9);
case WatchOS:
return getVersion() >= VersionTuple(2);
case GNUstep:
return false;
default:
return false;
}
}
/// \brief Try to parse an Objective-C runtime specification from the given
/// string.
///

3
clang/lib/CodeGen/CGDecl.cpp
View File

@ -715,8 +715,7 @@ void CodeGenFunction::EmitScalarInit(const Expr *init, const ValueDecl *D,
llvm_unreachable("present but none");
case Qualifiers::OCL_ExplicitNone:
// nothing to do
value = EmitScalarExpr(init);
value = EmitARCUnsafeUnretainedScalarExpr(init);
break;
case Qualifiers::OCL_Strong: {

18
clang/lib/CodeGen/CGExprScalar.cpp
View File

@ -1366,8 +1366,9 @@ Value *ScalarExprEmitter::VisitCastExpr(CastExpr *CE) {
QualType DestTy = CE->getType();
CastKind Kind = CE->getCastKind();
if (!DestTy->isVoidType())
TestAndClearIgnoreResultAssign();
// These cases are generally not written to ignore the result of
// evaluating their sub-expressions, so we clear this now.
bool Ignored = TestAndClearIgnoreResultAssign();
// Since almost all cast kinds apply to scalars, this switch doesn't have
// a default case, so the compiler will warn on a missing case. The cases
@ -1494,11 +1495,8 @@ Value *ScalarExprEmitter::VisitCastExpr(CastExpr *CE) {
return CGF.EmitARCRetainScalarExpr(E);
case CK_ARCConsumeObject:
return CGF.EmitObjCConsumeObject(E->getType(), Visit(E));
case CK_ARCReclaimReturnedObject: {
llvm::Value *value = Visit(E);
value = CGF.EmitARCRetainAutoreleasedReturnValue(value);
return CGF.EmitObjCConsumeObject(E->getType(), value);
}
case CK_ARCReclaimReturnedObject:
return CGF.EmitARCReclaimReturnedObject(E, /*allowUnsafe*/ Ignored);
case CK_ARCExtendBlockObject:
return CGF.EmitARCExtendBlockObject(E);
@ -2993,15 +2991,17 @@ Value *ScalarExprEmitter::VisitBinAssign(const BinaryOperator *E) {
std::tie(LHS, RHS) = CGF.EmitARCStoreAutoreleasing(E);
break;
case Qualifiers::OCL_ExplicitNone:
std::tie(LHS, RHS) = CGF.EmitARCStoreUnsafeUnretained(E, Ignore);
break;
case Qualifiers::OCL_Weak:
RHS = Visit(E->getRHS());
LHS = EmitCheckedLValue(E->getLHS(), CodeGenFunction::TCK_Store);
RHS = CGF.EmitARCStoreWeak(LHS.getAddress(), RHS, Ignore);
break;
// No reason to do any of these differently.
case Qualifiers::OCL_None:
case Qualifiers::OCL_ExplicitNone:
// __block variables need to have the rhs evaluated first, plus
// this should improve codegen just a little.
RHS = Visit(E->getRHS());

625
clang/lib/CodeGen/CGObjC.cpp
View File

@ -1980,20 +1980,14 @@ llvm::Value *CodeGenFunction::EmitARCRetainBlock(llvm::Value *value,
return result;
}
/// Retain the given object which is the result of a function call.
/// call i8* \@objc_retainAutoreleasedReturnValue(i8* %value)
///
/// Yes, this function name is one character away from a different
/// call with completely different semantics.
llvm::Value *
CodeGenFunction::EmitARCRetainAutoreleasedReturnValue(llvm::Value *value) {
static void emitAutoreleasedReturnValueMarker(CodeGenFunction &CGF) {
// Fetch the void(void) inline asm which marks that we're going to
// retain the autoreleased return value.
// do something with the autoreleased return value.
llvm::InlineAsm *&marker
= CGM.getObjCEntrypoints().retainAutoreleasedReturnValueMarker;
= CGF.CGM.getObjCEntrypoints().retainAutoreleasedReturnValueMarker;
if (!marker) {
StringRef assembly
= CGM.getTargetCodeGenInfo()
= CGF.CGM.getTargetCodeGenInfo()
.getARCRetainAutoreleasedReturnValueMarker();
// If we have an empty assembly string, there's nothing to do.
@ -2001,9 +1995,9 @@ CodeGenFunction::EmitARCRetainAutoreleasedReturnValue(llvm::Value *value) {
// Otherwise, at -O0, build an inline asm that we're going to call
// in a moment.
} else if (CGM.getCodeGenOpts().OptimizationLevel == 0) {
} else if (CGF.CGM.getCodeGenOpts().OptimizationLevel == 0) {
llvm::FunctionType *type =
llvm::FunctionType::get(VoidTy, /*variadic*/false);
llvm::FunctionType::get(CGF.VoidTy, /*variadic*/false);
marker = llvm::InlineAsm::get(type, assembly, "", /*sideeffects*/ true);
@ -2012,25 +2006,50 @@ CodeGenFunction::EmitARCRetainAutoreleasedReturnValue(llvm::Value *value) {
// optimizer to pick up.
} else {
llvm::NamedMDNode *metadata =
CGM.getModule().getOrInsertNamedMetadata(
CGF.CGM.getModule().getOrInsertNamedMetadata(
"clang.arc.retainAutoreleasedReturnValueMarker");
assert(metadata->getNumOperands() <= 1);
if (metadata->getNumOperands() == 0) {
metadata->addOperand(llvm::MDNode::get(
getLLVMContext(), llvm::MDString::get(getLLVMContext(), assembly)));
auto &ctx = CGF.getLLVMContext();
metadata->addOperand(llvm::MDNode::get(ctx,
llvm::MDString::get(ctx, assembly)));
}
}
}
// Call the marker asm if we made one, which we do only at -O0.
if (marker)
Builder.CreateCall(marker);
CGF.Builder.CreateCall(marker);
}
/// Retain the given object which is the result of a function call.
/// call i8* \@objc_retainAutoreleasedReturnValue(i8* %value)
///
/// Yes, this function name is one character away from a different
/// call with completely different semantics.
llvm::Value *
CodeGenFunction::EmitARCRetainAutoreleasedReturnValue(llvm::Value *value) {
emitAutoreleasedReturnValueMarker(*this);
return emitARCValueOperation(*this, value,
CGM.getObjCEntrypoints().objc_retainAutoreleasedReturnValue,
CGM.getObjCEntrypoints().objc_retainAutoreleasedReturnValue,
"objc_retainAutoreleasedReturnValue");
}
/// Claim a possibly-autoreleased return value at +0. This is only
/// valid to do in contexts which do not rely on the retain to keep
/// the object valid for for all of its uses; for example, when
/// the value is ignored, or when it is being assigned to an
/// __unsafe_unretained variable.
///
/// call i8* \@objc_unsafeClaimAutoreleasedReturnValue(i8* %value)
llvm::Value *
CodeGenFunction::EmitARCUnsafeClaimAutoreleasedReturnValue(llvm::Value *value) {
emitAutoreleasedReturnValueMarker(*this);
return emitARCValueOperation(*this, value,
CGM.getObjCEntrypoints().objc_unsafeClaimAutoreleasedReturnValue,
"objc_unsafeClaimAutoreleasedReturnValue");
}
/// Release the given object.
/// call void \@objc_release(i8* %value)
void CodeGenFunction::EmitARCRelease(llvm::Value *value,
@ -2446,25 +2465,22 @@ static TryEmitResult tryEmitARCRetainLoadOfScalar(CodeGenFunction &CGF,
return tryEmitARCRetainLoadOfScalar(CGF, CGF.EmitLValue(e), type);
}
static llvm::Value *emitARCRetainAfterCall(CodeGenFunction &CGF,
llvm::Value *value);
typedef llvm::function_ref<llvm::Value *(CodeGenFunction &CGF,
llvm::Value *value)>
ValueTransform;
/// Given that the given expression is some sort of call (which does
/// not return retained), emit a retain following it.
static llvm::Value *emitARCRetainCall(CodeGenFunction &CGF, const Expr *e) {
llvm::Value *value = CGF.EmitScalarExpr(e);
return emitARCRetainAfterCall(CGF, value);
}
static llvm::Value *emitARCRetainAfterCall(CodeGenFunction &CGF,
llvm::Value *value) {
/// Insert code immediately after a call.
static llvm::Value *emitARCOperationAfterCall(CodeGenFunction &CGF,
llvm::Value *value,
ValueTransform doAfterCall,
ValueTransform doFallback) {
if (llvm::CallInst *call = dyn_cast<llvm::CallInst>(value)) {
CGBuilderTy::InsertPoint ip = CGF.Builder.saveIP();
// Place the retain immediately following the call.
CGF.Builder.SetInsertPoint(call->getParent(),
++llvm::BasicBlock::iterator(call));
value = CGF.EmitARCRetainAutoreleasedReturnValue(value);
value = doAfterCall(CGF, value);
CGF.Builder.restoreIP(ip);
return value;
@ -2474,7 +2490,7 @@ static llvm::Value *emitARCRetainAfterCall(CodeGenFunction &CGF,
// Place the retain at the beginning of the normal destination block.
llvm::BasicBlock *BB = invoke->getNormalDest();
CGF.Builder.SetInsertPoint(BB, BB->begin());
value = CGF.EmitARCRetainAutoreleasedReturnValue(value);
value = doAfterCall(CGF, value);
CGF.Builder.restoreIP(ip);
return value;
@ -2483,7 +2499,7 @@ static llvm::Value *emitARCRetainAfterCall(CodeGenFunction &CGF,
// the operand.
} else if (llvm::BitCastInst *bitcast = dyn_cast<llvm::BitCastInst>(value)) {
llvm::Value *operand = bitcast->getOperand(0);
operand = emitARCRetainAfterCall(CGF, operand);
operand = emitARCOperationAfterCall(CGF, operand, doAfterCall, doFallback);
bitcast->setOperand(0, operand);
return bitcast;
@ -2491,7 +2507,46 @@ static llvm::Value *emitARCRetainAfterCall(CodeGenFunction &CGF,
} else {
// Retain using the non-block variant: we never need to do a copy
// of a block that's been returned to us.
return CGF.EmitARCRetainNonBlock(value);
return doFallback(CGF, value);
}
}
/// Given that the given expression is some sort of call (which does
/// not return retained), emit a retain following it.
static llvm::Value *emitARCRetainCallResult(CodeGenFunction &CGF,
const Expr *e) {
llvm::Value *value = CGF.EmitScalarExpr(e);
return emitARCOperationAfterCall(CGF, value,
[](CodeGenFunction &CGF, llvm::Value *value) {
return CGF.EmitARCRetainAutoreleasedReturnValue(value);
},
[](CodeGenFunction &CGF, llvm::Value *value) {
return CGF.EmitARCRetainNonBlock(value);
});
}
/// Given that the given expression is some sort of call (which does
/// not return retained), perform an unsafeClaim following it.
static llvm::Value *emitARCUnsafeClaimCallResult(CodeGenFunction &CGF,
const Expr *e) {
llvm::Value *value = CGF.EmitScalarExpr(e);
return emitARCOperationAfterCall(CGF, value,
[](CodeGenFunction &CGF, llvm::Value *value) {
return CGF.EmitARCUnsafeClaimAutoreleasedReturnValue(value);
},
[](CodeGenFunction &CGF, llvm::Value *value) {
return value;
});
}
llvm::Value *CodeGenFunction::EmitARCReclaimReturnedObject(const Expr *E,
bool allowUnsafeClaim) {
if (allowUnsafeClaim &&
CGM.getLangOpts().ObjCRuntime.hasARCUnsafeClaimAutoreleasedReturnValue()) {
return emitARCUnsafeClaimCallResult(*this, E);
} else {
llvm::Value *value = emitARCRetainCallResult(*this, E);
return EmitObjCConsumeObject(E->getType(), value);
}
}
@ -2531,17 +2586,52 @@ static bool shouldEmitSeparateBlockRetain(const Expr *e) {
return true;
}
/// Try to emit a PseudoObjectExpr at +1.
namespace {
/// A CRTP base class for emitting expressions of retainable object
/// pointer type in ARC.
template <typename Impl, typename Result> class ARCExprEmitter {
protected:
CodeGenFunction &CGF;
Impl &asImpl() { return *static_cast<Impl*>(this); }
ARCExprEmitter(CodeGenFunction &CGF) : CGF(CGF) {}
public:
Result visit(const Expr *e);
Result visitCastExpr(const CastExpr *e);
Result visitPseudoObjectExpr(const PseudoObjectExpr *e);
Result visitBinaryOperator(const BinaryOperator *e);
Result visitBinAssign(const BinaryOperator *e);
Result visitBinAssignUnsafeUnretained(const BinaryOperator *e);
Result visitBinAssignAutoreleasing(const BinaryOperator *e);
Result visitBinAssignWeak(const BinaryOperator *e);
Result visitBinAssignStrong(const BinaryOperator *e);
// Minimal implementation:
// Result visitLValueToRValue(const Expr *e)
// Result visitConsumeObject(const Expr *e)
// Result visitExtendBlockObject(const Expr *e)
// Result visitReclaimReturnedObject(const Expr *e)
// Result visitCall(const Expr *e)
// Result visitExpr(const Expr *e)
//
// Result emitBitCast(Result result, llvm::Type *resultType)
// llvm::Value *getValueOfResult(Result result)
};
}
/// Try to emit a PseudoObjectExpr under special ARC rules.
///
/// This massively duplicates emitPseudoObjectRValue.
static TryEmitResult tryEmitARCRetainPseudoObject(CodeGenFunction &CGF,
const PseudoObjectExpr *E) {
template <typename Impl, typename Result>
Result
ARCExprEmitter<Impl,Result>::visitPseudoObjectExpr(const PseudoObjectExpr *E) {
SmallVector<CodeGenFunction::OpaqueValueMappingData, 4> opaques;
// Find the result expression.
const Expr *resultExpr = E->getResultExpr();
assert(resultExpr);
TryEmitResult result;
Result result;
for (PseudoObjectExpr::const_semantics_iterator
i = E->semantics_begin(), e = E->semantics_end(); i != e; ++i) {
@ -2557,8 +2647,9 @@ static TryEmitResult tryEmitARCRetainPseudoObject(CodeGenFunction &CGF,
// expression, try to evaluate the source as +1.
if (ov == resultExpr) {
assert(!OVMA::shouldBindAsLValue(ov));
result = tryEmitARCRetainScalarExpr(CGF, ov->getSourceExpr());
opaqueData = OVMA::bind(CGF, ov, RValue::get(result.getPointer()));
result = asImpl().visit(ov->getSourceExpr());
opaqueData = OVMA::bind(CGF, ov,
RValue::get(asImpl().getValueOfResult(result)));
// Otherwise, just bind it.
} else {
@ -2569,7 +2660,7 @@ static TryEmitResult tryEmitARCRetainPseudoObject(CodeGenFunction &CGF,
// Otherwise, if the expression is the result, evaluate it
// and remember the result.
} else if (semantic == resultExpr) {
result = tryEmitARCRetainScalarExpr(CGF, semantic);
result = asImpl().visit(semantic);
// Otherwise, evaluate the expression in an ignored context.
} else {
@ -2584,146 +2675,240 @@ static TryEmitResult tryEmitARCRetainPseudoObject(CodeGenFunction &CGF,
return result;
}
static TryEmitResult
tryEmitARCRetainScalarExpr(CodeGenFunction &CGF, const Expr *e) {
// We should *never* see a nested full-expression here, because if
// we fail to emit at +1, our caller must not retain after we close
// out the full-expression.
assert(!isa<ExprWithCleanups>(e));
template <typename Impl, typename Result>
Result ARCExprEmitter<Impl,Result>::visitCastExpr(const CastExpr *e) {
switch (e->getCastKind()) {
// The desired result type, if it differs from the type of the
// ultimate opaque expression.
llvm::Type *resultType = nullptr;
// No-op casts don't change the type, so we just ignore them.
case CK_NoOp:
return asImpl().visit(e->getSubExpr());
while (true) {
e = e->IgnoreParens();
// There's a break at the end of this if-chain; anything
// that wants to keep looping has to explicitly continue.
if (const CastExpr *ce = dyn_cast<CastExpr>(e)) {
switch (ce->getCastKind()) {
// No-op casts don't change the type, so we just ignore them.
case CK_NoOp:
e = ce->getSubExpr();
continue;
case CK_LValueToRValue: {
TryEmitResult loadResult
= tryEmitARCRetainLoadOfScalar(CGF, ce->getSubExpr());
if (resultType) {
llvm::Value *value = loadResult.getPointer();
value = CGF.Builder.CreateBitCast(value, resultType);
loadResult.setPointer(value);
}
return loadResult;
}
// These casts can change the type, so remember that and
// soldier on. We only need to remember the outermost such
// cast, though.
case CK_CPointerToObjCPointerCast:
case CK_BlockPointerToObjCPointerCast:
case CK_AnyPointerToBlockPointerCast:
case CK_BitCast:
if (!resultType)
resultType = CGF.ConvertType(ce->getType());
e = ce->getSubExpr();
assert(e->getType()->hasPointerRepresentation());
continue;
// For consumptions, just emit the subexpression and thus elide
// the retain/release pair.
case CK_ARCConsumeObject: {
llvm::Value *result = CGF.EmitScalarExpr(ce->getSubExpr());
if (resultType) result = CGF.Builder.CreateBitCast(result, resultType);
return TryEmitResult(result, true);
}
// Block extends are net +0. Naively, we could just recurse on
// the subexpression, but actually we need to ensure that the
// value is copied as a block, so there's a little filter here.
case CK_ARCExtendBlockObject: {
llvm::Value *result; // will be a +0 value
// If we can't safely assume the sub-expression will produce a
// block-copied value, emit the sub-expression at +0.
if (shouldEmitSeparateBlockRetain(ce->getSubExpr())) {
result = CGF.EmitScalarExpr(ce->getSubExpr());
// Otherwise, try to emit the sub-expression at +1 recursively.
} else {
TryEmitResult subresult
= tryEmitARCRetainScalarExpr(CGF, ce->getSubExpr());
result = subresult.getPointer();
// If that produced a retained value, just use that,
// possibly casting down.
if (subresult.getInt()) {
if (resultType)
result = CGF.Builder.CreateBitCast(result, resultType);
return TryEmitResult(result, true);
}
// Otherwise it's +0.
}
// Retain the object as a block, then cast down.
result = CGF.EmitARCRetainBlock(result, /*mandatory*/ true);
if (resultType) result = CGF.Builder.CreateBitCast(result, resultType);
return TryEmitResult(result, true);
}
// For reclaims, emit the subexpression as a retained call and
// skip the consumption.
case CK_ARCReclaimReturnedObject: {
llvm::Value *result = emitARCRetainCall(CGF, ce->getSubExpr());
if (resultType) result = CGF.Builder.CreateBitCast(result, resultType);
return TryEmitResult(result, true);
}
default:
break;
}
// Skip __extension__.
} else if (const UnaryOperator *op = dyn_cast<UnaryOperator>(e)) {
if (op->getOpcode() == UO_Extension) {
e = op->getSubExpr();
continue;
}
// For calls and message sends, use the retained-call logic.
// Delegate inits are a special case in that they're the only
// returns-retained expression that *isn't* surrounded by
// a consume.
} else if (isa<CallExpr>(e) ||
(isa<ObjCMessageExpr>(e) &&
!cast<ObjCMessageExpr>(e)->isDelegateInitCall())) {
llvm::Value *result = emitARCRetainCall(CGF, e);
if (resultType) result = CGF.Builder.CreateBitCast(result, resultType);
return TryEmitResult(result, true);
// Look through pseudo-object expressions.
} else if (const PseudoObjectExpr *pseudo = dyn_cast<PseudoObjectExpr>(e)) {
TryEmitResult result
= tryEmitARCRetainPseudoObject(CGF, pseudo);
if (resultType) {
llvm::Value *value = result.getPointer();
value = CGF.Builder.CreateBitCast(value, resultType);
result.setPointer(value);
}
return result;
}
// Conservatively halt the search at any other expression kind.
break;
// These casts can change the type.
case CK_CPointerToObjCPointerCast:
case CK_BlockPointerToObjCPointerCast:
case CK_AnyPointerToBlockPointerCast:
case CK_BitCast: {
llvm::Type *resultType = CGF.ConvertType(e->getType());
assert(e->getSubExpr()->getType()->hasPointerRepresentation());
Result result = asImpl().visit(e->getSubExpr());
return asImpl().emitBitCast(result, resultType);
}
// We didn't find an obvious production, so emit what we've got and
// tell the caller that we didn't manage to retain.
llvm::Value *result = CGF.EmitScalarExpr(e);
if (resultType) result = CGF.Builder.CreateBitCast(result, resultType);
return TryEmitResult(result, false);
// Handle some casts specially.
case CK_LValueToRValue:
return asImpl().visitLValueToRValue(e->getSubExpr());
case CK_ARCConsumeObject:
return asImpl().visitConsumeObject(e->getSubExpr());
case CK_ARCExtendBlockObject:
return asImpl().visitExtendBlockObject(e->getSubExpr());
case CK_ARCReclaimReturnedObject:
return asImpl().visitReclaimReturnedObject(e->getSubExpr());
// Otherwise, use the default logic.
default:
return asImpl().visitExpr(e);
}
}
template <typename Impl, typename Result>
Result
ARCExprEmitter<Impl,Result>::visitBinaryOperator(const BinaryOperator *e) {
switch (e->getOpcode()) {
case BO_Comma:
CGF.EmitIgnoredExpr(e->getLHS());
CGF.EnsureInsertPoint();
return asImpl().visit(e->getRHS());
case BO_Assign:
return asImpl().visitBinAssign(e);
default:
return asImpl().visitExpr(e);
}
}
template <typename Impl, typename Result>
Result ARCExprEmitter<Impl,Result>::visitBinAssign(const BinaryOperator *e) {
switch (e->getLHS()->getType().getObjCLifetime()) {
case Qualifiers::OCL_ExplicitNone:
return asImpl().visitBinAssignUnsafeUnretained(e);
case Qualifiers::OCL_Weak:
return asImpl().visitBinAssignWeak(e);
case Qualifiers::OCL_Autoreleasing:
return asImpl().visitBinAssignAutoreleasing(e);
case Qualifiers::OCL_Strong:
return asImpl().visitBinAssignStrong(e);
case Qualifiers::OCL_None:
return asImpl().visitExpr(e);
}
llvm_unreachable("bad ObjC ownership qualifier");
}
/// The default rule for __unsafe_unretained emits the RHS recursively,
/// stores into the unsafe variable, and propagates the result outward.
template <typename Impl, typename Result>
Result ARCExprEmitter<Impl,Result>::
visitBinAssignUnsafeUnretained(const BinaryOperator *e) {
// Recursively emit the RHS.
// For __block safety, do this before emitting the LHS.
Result result = asImpl().visit(e->getRHS());
// Perform the store.
LValue lvalue =
CGF.EmitCheckedLValue(e->getLHS(), CodeGenFunction::TCK_Store);
CGF.EmitStoreThroughLValue(RValue::get(asImpl().getValueOfResult(result)),
lvalue);
return result;
}
template <typename Impl, typename Result>
Result
ARCExprEmitter<Impl,Result>::visitBinAssignAutoreleasing(const BinaryOperator *e) {
return asImpl().visitExpr(e);
}
template <typename Impl, typename Result>
Result
ARCExprEmitter<Impl,Result>::visitBinAssignWeak(const BinaryOperator *e) {
return asImpl().visitExpr(e);
}
template <typename Impl, typename Result>
Result
ARCExprEmitter<Impl,Result>::visitBinAssignStrong(const BinaryOperator *e) {
return asImpl().visitExpr(e);
}
/// The general expression-emission logic.
template <typename Impl, typename Result>
Result ARCExprEmitter<Impl,Result>::visit(const Expr *e) {
// We should *never* see a nested full-expression here, because if
// we fail to emit at +1, our caller must not retain after we close
// out the full-expression. This isn't as important in the unsafe
// emitter.
assert(!isa<ExprWithCleanups>(e));
// Look through parens, __extension__, generic selection, etc.
e = e->IgnoreParens();
// Handle certain kinds of casts.
if (const CastExpr *ce = dyn_cast<CastExpr>(e)) {
return asImpl().visitCastExpr(ce);
// Handle the comma operator.
} else if (auto op = dyn_cast<BinaryOperator>(e)) {
return asImpl().visitBinaryOperator(op);
// TODO: handle conditional operators here
// For calls and message sends, use the retained-call logic.
// Delegate inits are a special case in that they're the only
// returns-retained expression that *isn't* surrounded by
// a consume.
} else if (isa<CallExpr>(e) ||
(isa<ObjCMessageExpr>(e) &&
!cast<ObjCMessageExpr>(e)->isDelegateInitCall())) {
return asImpl().visitCall(e);
// Look through pseudo-object expressions.
} else if (const PseudoObjectExpr *pseudo = dyn_cast<PseudoObjectExpr>(e)) {
return asImpl().visitPseudoObjectExpr(pseudo);
}
return asImpl().visitExpr(e);
}
namespace {
/// An emitter for +1 results.
struct ARCRetainExprEmitter :
public ARCExprEmitter<ARCRetainExprEmitter, TryEmitResult> {
ARCRetainExprEmitter(CodeGenFunction &CGF) : ARCExprEmitter(CGF) {}
llvm::Value *getValueOfResult(TryEmitResult result) {
return result.getPointer();
}
TryEmitResult emitBitCast(TryEmitResult result, llvm::Type *resultType) {
llvm::Value *value = result.getPointer();
value = CGF.Builder.CreateBitCast(value, resultType);
result.setPointer(value);
return result;
}
TryEmitResult visitLValueToRValue(const Expr *e) {
return tryEmitARCRetainLoadOfScalar(CGF, e);
}
/// For consumptions, just emit the subexpression and thus elide
/// the retain/release pair.
TryEmitResult visitConsumeObject(const Expr *e) {
llvm::Value *result = CGF.EmitScalarExpr(e);
return TryEmitResult(result, true);
}
/// Block extends are net +0. Naively, we could just recurse on
/// the subexpression, but actually we need to ensure that the
/// value is copied as a block, so there's a little filter here.
TryEmitResult visitExtendBlockObject(const Expr *e) {
llvm::Value *result; // will be a +0 value
// If we can't safely assume the sub-expression will produce a
// block-copied value, emit the sub-expression at +0.
if (shouldEmitSeparateBlockRetain(e)) {
result = CGF.EmitScalarExpr(e);
// Otherwise, try to emit the sub-expression at +1 recursively.
} else {
TryEmitResult subresult = asImpl().visit(e);
// If that produced a retained value, just use that.
if (subresult.getInt()) {
return subresult;
}
// Otherwise it's +0.
result = subresult.getPointer();
}
// Retain the object as a block.
result = CGF.EmitARCRetainBlock(result, /*mandatory*/ true);
return TryEmitResult(result, true);
}
/// For reclaims, emit the subexpression as a retained call and
/// skip the consumption.
TryEmitResult visitReclaimReturnedObject(const Expr *e) {
llvm::Value *result = emitARCRetainCallResult(CGF, e);
return TryEmitResult(result, true);
}
/// When we have an undecorated call, retroactively do a claim.
TryEmitResult visitCall(const Expr *e) {
llvm::Value *result = emitARCRetainCallResult(CGF, e);
return TryEmitResult(result, true);
}
// TODO: maybe special-case visitBinAssignWeak?
TryEmitResult visitExpr(const Expr *e) {
// We didn't find an obvious production, so emit what we've got and
// tell the caller that we didn't manage to retain.
llvm::Value *result = CGF.EmitScalarExpr(e);
return TryEmitResult(result, false);
}
};
}
static TryEmitResult
tryEmitARCRetainScalarExpr(CodeGenFunction &CGF, const Expr *e) {
return ARCRetainExprEmitter(CGF).visit(e);
}
static llvm::Value *emitARCRetainLoadOfScalar(CodeGenFunction &CGF,
@ -2807,6 +2992,96 @@ llvm::Value *CodeGenFunction::EmitObjCThrowOperand(const Expr *expr) {
return EmitScalarExpr(expr);
}
namespace {
/// An emitter for assigning into an __unsafe_unretained context.
struct ARCUnsafeUnretainedExprEmitter :
public ARCExprEmitter<ARCUnsafeUnretainedExprEmitter, llvm::Value*> {
ARCUnsafeUnretainedExprEmitter(CodeGenFunction &CGF) : ARCExprEmitter(CGF) {}
llvm::Value *getValueOfResult(llvm::Value *value) {
return value;
}
llvm::Value *emitBitCast(llvm::Value *value, llvm::Type *resultType) {
return CGF.Builder.CreateBitCast(value, resultType);
}
llvm::Value *visitLValueToRValue(const Expr *e) {
return CGF.EmitScalarExpr(e);
}
/// For consumptions, just emit the subexpression and perform the
/// consumption like normal.
llvm::Value *visitConsumeObject(const Expr *e) {
llvm::Value *value = CGF.EmitScalarExpr(e);
return CGF.EmitObjCConsumeObject(e->getType(), value);
}
/// No special logic for block extensions. (This probably can't
/// actually happen in this emitter, though.)
llvm::Value *visitExtendBlockObject(const Expr *e) {
return CGF.EmitARCExtendBlockObject(e);
}
/// For reclaims, perform an unsafeClaim if that's enabled.
llvm::Value *visitReclaimReturnedObject(const Expr *e) {
return CGF.EmitARCReclaimReturnedObject(e, /*unsafe*/ true);
}
/// When we have an undecorated call, just emit it without adding
/// the unsafeClaim.
llvm::Value *visitCall(const Expr *e) {
return CGF.EmitScalarExpr(e);
}
/// Just do normal scalar emission in the default case.
llvm::Value *visitExpr(const Expr *e) {
return CGF.EmitScalarExpr(e);
}
};
}
static llvm::Value *emitARCUnsafeUnretainedScalarExpr(CodeGenFunction &CGF,
const Expr *e) {
return ARCUnsafeUnretainedExprEmitter(CGF).visit(e);
}
/// EmitARCUnsafeUnretainedScalarExpr - Semantically equivalent to
/// immediately releasing the resut of EmitARCRetainScalarExpr, but
/// avoiding any spurious retains, including by performing reclaims
/// with objc_unsafeClaimAutoreleasedReturnValue.
llvm::Value *CodeGenFunction::EmitARCUnsafeUnretainedScalarExpr(const Expr *e) {
// Look through full-expressions.
if (const ExprWithCleanups *cleanups = dyn_cast<ExprWithCleanups>(e)) {
enterFullExpression(cleanups);
RunCleanupsScope scope(*this);
return emitARCUnsafeUnretainedScalarExpr(*this, cleanups->getSubExpr());
}
return emitARCUnsafeUnretainedScalarExpr(*this, e);
}
std::pair<LValue,llvm::Value*>
CodeGenFunction::EmitARCStoreUnsafeUnretained(const BinaryOperator *e,
bool ignored) {
// Evaluate the RHS first. If we're ignoring the result, assume
// that we can emit at an unsafe +0.
llvm::Value *value;
if (ignored) {
value = EmitARCUnsafeUnretainedScalarExpr(e->getRHS());
} else {
value = EmitScalarExpr(e->getRHS());
}
// Emit the LHS and perform the store.
LValue lvalue = EmitLValue(e->getLHS());
EmitStoreOfScalar(value, lvalue);
return std::pair<LValue,llvm::Value*>(std::move(lvalue), value);
}
std::pair<LValue,llvm::Value*>
CodeGenFunction::EmitARCStoreStrong(const BinaryOperator *e,
bool ignored) {

6
clang/lib/CodeGen/CodeGenFunction.h
View File

@ -2807,19 +2807,25 @@ public:
llvm::Value *EmitARCAutoreleaseReturnValue(llvm::Value *value);
llvm::Value *EmitARCRetainAutoreleaseReturnValue(llvm::Value *value);
llvm::Value *EmitARCRetainAutoreleasedReturnValue(llvm::Value *value);
llvm::Value *EmitARCUnsafeClaimAutoreleasedReturnValue(llvm::Value *value);
std::pair<LValue,llvm::Value*>
EmitARCStoreAutoreleasing(const BinaryOperator *e);
std::pair<LValue,llvm::Value*>
EmitARCStoreStrong(const BinaryOperator *e, bool ignored);
std::pair<LValue,llvm::Value*>
EmitARCStoreUnsafeUnretained(const BinaryOperator *e, bool ignored);
llvm::Value *EmitObjCThrowOperand(const Expr *expr);
llvm::Value *EmitObjCConsumeObject(QualType T, llvm::Value *Ptr);
llvm::Value *EmitObjCExtendObjectLifetime(QualType T, llvm::Value *Ptr);
llvm::Value *EmitARCExtendBlockObject(const Expr *expr);
llvm::Value *EmitARCReclaimReturnedObject(const Expr *e,
bool allowUnsafeClaim);
llvm::Value *EmitARCRetainScalarExpr(const Expr *expr);
llvm::Value *EmitARCRetainAutoreleaseScalarExpr(const Expr *expr);
llvm::Value *EmitARCUnsafeUnretainedScalarExpr(const Expr *expr);
void EmitARCIntrinsicUse(ArrayRef<llvm::Value*> values);

3
clang/lib/CodeGen/CodeGenModule.h
View File

@ -166,6 +166,9 @@ struct ObjCEntrypoints {
/// id objc_storeWeak(id*, id);
llvm::Constant *objc_storeWeak;
/// id objc_unsafeClaimAutoreleasedReturnValue(id);
llvm::Constant *objc_unsafeClaimAutoreleasedReturnValue;
/// A void(void) inline asm to use to mark that the return value of
/// a call will be immediately retain.
llvm::InlineAsm *retainAutoreleasedReturnValueMarker;

231
clang/test/CodeGenObjC/arc-unsafeclaim.m Normal file
View File

@ -0,0 +1,231 @@
// Make sure it works on x86-64.
// RUN: %clang_cc1 -triple x86_64-apple-darwin11 -fobjc-runtime=macosx-10.11 -fobjc-arc -emit-llvm -o - %s | FileCheck %s -check-prefix=CHECK -check-prefix=CHECK-UNOPTIMIZED
// Make sure it works on ARM.
// RUN: %clang_cc1 -triple arm64-apple-ios9 -fobjc-runtime=ios-9.0 -fobjc-arc -emit-llvm -o - %s | FileCheck %s -check-prefix=CHECK -check-prefix=CHECK-UNOPTIMIZED -check-prefix=CHECK-MARKED
// RUN: %clang_cc1 -triple arm64-apple-ios9 -fobjc-runtime=ios-9.0 -fobjc-arc -O -disable-llvm-optzns -emit-llvm -o - %s | FileCheck %s -check-prefix=CHECK -check-prefix=CHECK-OPTIMIZED
// Make sure it works on ARM64.
// RUN: %clang_cc1 -triple armv7-apple-ios9 -fobjc-runtime=ios-9.0 -fobjc-arc -emit-llvm -o - %s | FileCheck %s -check-prefix=CHECK -check-prefix=CHECK-UNOPTIMIZED -check-prefix=CHECK-MARKED
// RUN: %clang_cc1 -triple armv7-apple-ios9 -fobjc-runtime=ios-9.0 -fobjc-arc -O -disable-llvm-optzns -emit-llvm -o - %s | FileCheck %s -check-prefix=CHECK -check-prefix=CHECK-OPTIMIZED
// Make sure that it's implicitly disabled if the runtime version isn't high enough.
// RUN: %clang_cc1 -triple x86_64-apple-darwin10 -fobjc-runtime=macosx-10.10 -fobjc-arc -emit-llvm -o - %s | FileCheck %s -check-prefix=DISABLED
// RUN: %clang_cc1 -triple arm64-apple-ios8 -fobjc-runtime=ios-8 -fobjc-arc -emit-llvm -o - %s | FileCheck %s -check-prefix=DISABLED -check-prefix=DISABLED-MARKED
@class A;
A *makeA(void);
void test_assign() {
__unsafe_unretained id x;
x = makeA();
}
// CHECK-LABEL: define void @test_assign()
// CHECK: [[X:%.*]] = alloca i8*
// CHECK: [[T0:%.*]] = call [[A:.*]]* @makeA()
// CHECK-MARKED-NEXT: call void asm sideeffect
// CHECK-NEXT: [[T1:%.*]] = bitcast [[A]]* [[T0]] to i8*
// CHECK-NEXT: [[T2:%.*]] = call i8* @objc_unsafeClaimAutoreleasedReturnValue(i8* [[T1]])
// CHECK-NEXT: [[T3:%.*]] = bitcast i8* [[T2]] to [[A]]*
// CHECK-NEXT: [[T4:%.*]] = bitcast [[A]]* [[T3]] to i8*
// CHECK-NEXT: store i8* [[T4]], i8** [[X]]
// CHECK-OPTIMIZED-NEXT: bitcast
// CHECK-OPTIMIZED-NEXT: lifetime.end
// CHECK-NEXT: ret void
// DISABLED-LABEL: define void @test_assign()
// DISABLED: [[T0:%.*]] = call [[A:.*]]* @makeA()
// DISABLED-MARKED-NEXT: call void asm sideeffect
// DISABLED-NEXT: [[T1:%.*]] = bitcast [[A]]* [[T0]] to i8*
// DISABLED-NEXT: [[T2:%.*]] = call i8* @objc_retainAutoreleasedReturnValue(i8* [[T1]])
void test_assign_assign() {
__unsafe_unretained id x, y;
x = y = makeA();
}
// CHECK-LABEL: define void @test_assign_assign()
// CHECK: [[X:%.*]] = alloca i8*
// CHECK: [[Y:%.*]] = alloca i8*
// CHECK: [[T0:%.*]] = call [[A]]* @makeA()
// CHECK-MARKED-NEXT: call void asm sideeffect
// CHECK-NEXT: [[T1:%.*]] = bitcast [[A]]* [[T0]] to i8*
// CHECK-NEXT: [[T2:%.*]] = call i8* @objc_unsafeClaimAutoreleasedReturnValue(i8* [[T1]])
// CHECK-NEXT: [[T3:%.*]] = bitcast i8* [[T2]] to [[A]]*
// CHECK-NEXT: [[T4:%.*]] = bitcast [[A]]* [[T3]] to i8*
// CHECK-NEXT: store i8* [[T4]], i8** [[Y]]
// CHECK-NEXT: store i8* [[T4]], i8** [[X]]
// CHECK-OPTIMIZED-NEXT: bitcast
// CHECK-OPTIMIZED-NEXT: lifetime.end
// CHECK-OPTIMIZED-NEXT: bitcast
// CHECK-OPTIMIZED-NEXT: lifetime.end
// CHECK-NEXT: ret void
void test_strong_assign_assign() {
__strong id x;
__unsafe_unretained id y;
x = y = makeA();
}
// CHECK-LABEL: define void @test_strong_assign_assign()
// CHECK: [[X:%.*]] = alloca i8*
// CHECK: [[Y:%.*]] = alloca i8*
// CHECK: [[T0:%.*]] = call [[A]]* @makeA()
// CHECK-MARKED-NEXT: call void asm sideeffect
// CHECK-NEXT: [[T1:%.*]] = bitcast [[A]]* [[T0]] to i8*
// CHECK-NEXT: [[T2:%.*]] = call i8* @objc_retainAutoreleasedReturnValue(i8* [[T1]])
// CHECK-NEXT: [[T3:%.*]] = bitcast i8* [[T2]] to [[A]]*
// CHECK-NEXT: [[T4:%.*]] = bitcast [[A]]* [[T3]] to i8*
// CHECK-NEXT: store i8* [[T4]], i8** [[Y]]
// CHECK-NEXT: [[OLD:%.*]] = load i8*, i8** [[X]]
// CHECK-NEXT: store i8* [[T4]], i8** [[X]]
// CHECK-NEXT: call void @objc_release(i8* [[OLD]]
// CHECK-OPTIMIZED-NEXT: bitcast
// CHECK-OPTIMIZED-NEXT: lifetime.end
// CHECK-UNOPTIMIZED-NEXT: call void @objc_storeStrong(i8** [[X]], i8* null)
// CHECK-OPTIMIZED-NEXT: [[T0:%.*]] = load i8*, i8** [[X]]
// CHECK-OPTIMIZED-NEXT: call void @objc_release(i8* [[T0]])
// CHECK-OPTIMIZED-NEXT: bitcast
// CHECK-OPTIMIZED-NEXT: lifetime.end
// CHECK-NEXT: ret void
void test_assign_strong_assign() {
__unsafe_unretained id x;
__strong id y;
x = y = makeA();
}
// CHECK-LABEL: define void @test_assign_strong_assign()
// CHECK: [[X:%.*]] = alloca i8*
// CHECK: [[Y:%.*]] = alloca i8*
// CHECK: [[T0:%.*]] = call [[A]]* @makeA()
// CHECK-MARKED-NEXT: call void asm sideeffect
// CHECK-NEXT: [[T1:%.*]] = bitcast [[A]]* [[T0]] to i8*
// CHECK-NEXT: [[T2:%.*]] = call i8* @objc_retainAutoreleasedReturnValue(i8* [[T1]])
// CHECK-NEXT: [[T3:%.*]] = bitcast i8* [[T2]] to [[A]]*
// CHECK-NEXT: [[T4:%.*]] = bitcast [[A]]* [[T3]] to i8*
// CHECK-NEXT: [[OLD:%.*]] = load i8*, i8** [[Y]]
// CHECK-NEXT: store i8* [[T4]], i8** [[Y]]
// CHECK-NEXT: call void @objc_release(i8* [[OLD]]
// CHECK-NEXT: store i8* [[T4]], i8** [[X]]
// CHECK-UNOPTIMIZED-NEXT: call void @objc_storeStrong(i8** [[Y]], i8* null)
// CHECK-OPTIMIZED-NEXT: [[T0:%.*]] = load i8*, i8** [[Y]]
// CHECK-OPTIMIZED-NEXT: call void @objc_release(i8* [[T0]])
// CHECK-OPTIMIZED-NEXT: bitcast
// CHECK-OPTIMIZED-NEXT: lifetime.end
// CHECK-OPTIMIZED-NEXT: bitcast
// CHECK-OPTIMIZED-NEXT: lifetime.end
// CHECK-NEXT: ret void
void test_init() {
__unsafe_unretained id x = makeA();
}
// CHECK-LABEL: define void @test_init()
// CHECK: [[X:%.*]] = alloca i8*
// CHECK: [[T0:%.*]] = call [[A]]* @makeA()
// CHECK-MARKED-NEXT: call void asm sideeffect
// CHECK-NEXT: [[T1:%.*]] = bitcast [[A]]* [[T0]] to i8*
// CHECK-NEXT: [[T2:%.*]] = call i8* @objc_unsafeClaimAutoreleasedReturnValue(i8* [[T1]])
// CHECK-NEXT: [[T3:%.*]] = bitcast i8* [[T2]] to [[A]]*
// CHECK-NEXT: [[T4:%.*]] = bitcast [[A]]* [[T3]] to i8*
// CHECK-NEXT: store i8* [[T4]], i8** [[X]]
// CHECK-OPTIMIZED-NEXT: bitcast
// CHECK-OPTIMIZED-NEXT: lifetime.end
// CHECK-NEXT: ret void
void test_init_assignment() {
__unsafe_unretained id x;
__unsafe_unretained id y = x = makeA();
}
// CHECK-LABEL: define void @test_init_assignment()
// CHECK: [[X:%.*]] = alloca i8*
// CHECK: [[Y:%.*]] = alloca i8*
// CHECK: [[T0:%.*]] = call [[A]]* @makeA()
// CHECK-MARKED-NEXT: call void asm sideeffect
// CHECK-NEXT: [[T1:%.*]] = bitcast [[A]]* [[T0]] to i8*
// CHECK-NEXT: [[T2:%.*]] = call i8* @objc_unsafeClaimAutoreleasedReturnValue(i8* [[T1]])
// CHECK-NEXT: [[T3:%.*]] = bitcast i8* [[T2]] to [[A]]*
// CHECK-NEXT: [[T4:%.*]] = bitcast [[A]]* [[T3]] to i8*
// CHECK-NEXT: store i8* [[T4]], i8** [[X]]
// CHECK-NEXT: store i8* [[T4]], i8** [[Y]]
// CHECK-OPTIMIZED-NEXT: bitcast
// CHECK-OPTIMIZED-NEXT: lifetime.end
// CHECK-OPTIMIZED-NEXT: bitcast
// CHECK-OPTIMIZED-NEXT: lifetime.end
// CHECK-NEXT: ret void
void test_strong_init_assignment() {
__unsafe_unretained id x;
__strong id y = x = makeA();
}
// CHECK-LABEL: define void @test_strong_init_assignment()
// CHECK: [[X:%.*]] = alloca i8*
// CHECK: [[Y:%.*]] = alloca i8*
// CHECK: [[T0:%.*]] = call [[A]]* @makeA()
// CHECK-MARKED-NEXT: call void asm sideeffect
// CHECK-NEXT: [[T1:%.*]] = bitcast [[A]]* [[T0]] to i8*
// CHECK-NEXT: [[T2:%.*]] = call i8* @objc_retainAutoreleasedReturnValue(i8* [[T1]])
// CHECK-NEXT: [[T3:%.*]] = bitcast i8* [[T2]] to [[A]]*
// CHECK-NEXT: [[T4:%.*]] = bitcast [[A]]* [[T3]] to i8*
// CHECK-NEXT: store i8* [[T4]], i8** [[X]]
// CHECK-NEXT: store i8* [[T4]], i8** [[Y]]
// CHECK-UNOPTIMIZED-NEXT: call void @objc_storeStrong(i8** [[Y]], i8* null)
// CHECK-OPTIMIZED-NEXT: [[T0:%.*]] = load i8*, i8** [[Y]]
// CHECK-OPTIMIZED-NEXT: call void @objc_release(i8* [[T0]])
// CHECK-OPTIMIZED-NEXT: bitcast
// CHECK-OPTIMIZED-NEXT: lifetime.end
// CHECK-OPTIMIZED-NEXT: bitcast
// CHECK-OPTIMIZED-NEXT: lifetime.end
// CHECK-NEXT: ret void
void test_init_strong_assignment() {
__strong id x;
__unsafe_unretained id y = x = makeA();
}
// CHECK-LABEL: define void @test_init_strong_assignment()
// CHECK: [[X:%.*]] = alloca i8*
// CHECK: [[Y:%.*]] = alloca i8*
// CHECK: [[T0:%.*]] = call [[A]]* @makeA()
// CHECK-MARKED-NEXT: call void asm sideeffect
// CHECK-NEXT: [[T1:%.*]] = bitcast [[A]]* [[T0]] to i8*
// CHECK-NEXT: [[T2:%.*]] = call i8* @objc_retainAutoreleasedReturnValue(i8* [[T1]])
// CHECK-NEXT: [[T3:%.*]] = bitcast i8* [[T2]] to [[A]]*
// CHECK-NEXT: [[T4:%.*]] = bitcast [[A]]* [[T3]] to i8*
// CHECK-NEXT: [[OLD:%.*]] = load i8*, i8** [[X]]
// CHECK-NEXT: store i8* [[T4]], i8** [[X]]
// CHECK-NEXT: call void @objc_release(i8* [[OLD]])
// CHECK-NEXT: store i8* [[T4]], i8** [[Y]]
// CHECK-OPTIMIZED-NEXT: bitcast
// CHECK-OPTIMIZED-NEXT: lifetime.end
// CHECK-UNOPTIMIZED-NEXT: call void @objc_storeStrong(i8** [[X]], i8* null)
// CHECK-OPTIMIZED-NEXT: [[T0:%.*]] = load i8*, i8** [[X]]
// CHECK-OPTIMIZED-NEXT: call void @objc_release(i8* [[T0]])
// CHECK-OPTIMIZED-NEXT: bitcast
// CHECK-OPTIMIZED-NEXT: lifetime.end
// CHECK-NEXT: ret void
void test_ignored() {
makeA();
}
// CHECK-LABEL: define void @test_ignored()
// CHECK: [[T0:%.*]] = call [[A]]* @makeA()
// CHECK-MARKED-NEXT: call void asm sideeffect
// CHECK-NEXT: [[T1:%.*]] = bitcast [[A]]* [[T0]] to i8*
// CHECK-NEXT: [[T2:%.*]] = call i8* @objc_unsafeClaimAutoreleasedReturnValue(i8* [[T1]])
// CHECK-NEXT: bitcast i8* [[T2]] to [[A]]*
// CHECK-NEXT: ret void
void test_cast_to_void() {
(void) makeA();
}
// CHECK-LABEL: define void @test_cast_to_void()
// CHECK: [[T0:%.*]] = call [[A]]* @makeA()
// CHECK-MARKED-NEXT: call void asm sideeffect
// CHECK-NEXT: [[T1:%.*]] = bitcast [[A]]* [[T0]] to i8*
// CHECK-NEXT: [[T2:%.*]] = call i8* @objc_unsafeClaimAutoreleasedReturnValue(i8* [[T1]])
// CHECK-NEXT: bitcast i8* [[T2]] to [[A]]*
// CHECK-NEXT: ret void
// This is always at the end of the module.
// CHECK-OPTIMIZED: !clang.arc.retainAutoreleasedReturnValueMarker = !{!0}