mirror of https://github.com/microsoft/clang.git
Support noreturn in limited contexts on Objective-C message sends.
rdar://6198039 git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@247350 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
John McCall
parent
5e1234dd84
commit
6d73f26899
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@ -1029,6 +1029,7 @@ protected:
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bool IsSuper,
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const CallArgList &CallArgs,
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const ObjCMethodDecl *OMD,
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const ObjCInterfaceDecl *ClassReceiver,
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const ObjCCommonTypesHelper &ObjCTypes);
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/// EmitImageInfo - Emit the image info marker used to encode some module
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@ -1833,7 +1834,7 @@ CGObjCMac::GenerateMessageSendSuper(CodeGen::CodeGenFunction &CGF,
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return EmitMessageSend(CGF, Return, ResultType,
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EmitSelector(CGF, Sel),
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ObjCSuper.getPointer(), ObjCTypes.SuperPtrCTy,
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true, CallArgs, Method, ObjCTypes);
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true, CallArgs, Method, Class, ObjCTypes);
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}
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/// Generate code for a message send expression.
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@ -1848,7 +1849,16 @@ CodeGen::RValue CGObjCMac::GenerateMessageSend(CodeGen::CodeGenFunction &CGF,
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return EmitMessageSend(CGF, Return, ResultType,
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EmitSelector(CGF, Sel),
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Receiver, CGF.getContext().getObjCIdType(),
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false, CallArgs, Method, ObjCTypes);
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false, CallArgs, Method, Class, ObjCTypes);
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}
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static bool isWeakLinkedClass(const ObjCInterfaceDecl *ID) {
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do {
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if (ID->isWeakImported())
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return true;
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} while ((ID = ID->getSuperClass()));
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return false;
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}
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CodeGen::RValue
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@ -1861,6 +1871,7 @@ CGObjCCommonMac::EmitMessageSend(CodeGen::CodeGenFunction &CGF,
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bool IsSuper,
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const CallArgList &CallArgs,
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const ObjCMethodDecl *Method,
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const ObjCInterfaceDecl *ClassReceiver,
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const ObjCCommonTypesHelper &ObjCTypes) {
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CallArgList ActualArgs;
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if (!IsSuper)
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@ -1877,11 +1888,38 @@ CGObjCCommonMac::EmitMessageSend(CodeGen::CodeGenFunction &CGF,
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CGM.getContext().getCanonicalType(ResultType) &&
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"Result type mismatch!");
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bool ReceiverCanBeNull = true;
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// Super dispatch assumes that self is non-null; even the messenger
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// doesn't have a null check internally.
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if (IsSuper) {
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ReceiverCanBeNull = false;
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// If this is a direct dispatch of a class method, check whether the class,
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// or anything in its hierarchy, was weak-linked.
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} else if (ClassReceiver && Method && Method->isClassMethod()) {
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ReceiverCanBeNull = isWeakLinkedClass(ClassReceiver);
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// If we're emitting a method, and self is const (meaning just ARC, for now),
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// and the receiver is a load of self, then self is a valid object.
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} else if (auto CurMethod =
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dyn_cast_or_null<ObjCMethodDecl>(CGF.CurCodeDecl)) {
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auto Self = CurMethod->getSelfDecl();
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if (Self->getType().isConstQualified()) {
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if (auto LI = dyn_cast<llvm::LoadInst>(Arg0->stripPointerCasts())) {
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llvm::Value *SelfAddr = CGF.GetAddrOfLocalVar(Self).getPointer();
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if (SelfAddr == LI->getPointerOperand()) {
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ReceiverCanBeNull = false;
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}
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}
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}
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}
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NullReturnState nullReturn;
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llvm::Constant *Fn = nullptr;
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if (CGM.ReturnSlotInterferesWithArgs(MSI.CallInfo)) {
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if (!IsSuper) nullReturn.init(CGF, Arg0);
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if (ReceiverCanBeNull) nullReturn.init(CGF, Arg0);
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Fn = (ObjCABI == 2) ? ObjCTypes.getSendStretFn2(IsSuper)
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: ObjCTypes.getSendStretFn(IsSuper);
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} else if (CGM.ReturnTypeUsesFPRet(ResultType)) {
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@ -1898,22 +1936,33 @@ CGObjCCommonMac::EmitMessageSend(CodeGen::CodeGenFunction &CGF,
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Fn = (ObjCABI == 2) ? ObjCTypes.getSendFn2(IsSuper)
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: ObjCTypes.getSendFn(IsSuper);
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}
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bool requiresnullCheck = false;
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if (CGM.getLangOpts().ObjCAutoRefCount && Method)
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// Emit a null-check if there's a consumed argument other than the receiver.
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bool RequiresNullCheck = false;
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if (ReceiverCanBeNull && CGM.getLangOpts().ObjCAutoRefCount && Method) {
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for (const auto *ParamDecl : Method->params()) {
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if (ParamDecl->hasAttr<NSConsumedAttr>()) {
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if (!nullReturn.NullBB)
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nullReturn.init(CGF, Arg0);
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requiresnullCheck = true;
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RequiresNullCheck = true;
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break;
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}
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}
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}
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llvm::Instruction *CallSite;
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Fn = llvm::ConstantExpr::getBitCast(Fn, MSI.MessengerType);
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RValue rvalue = CGF.EmitCall(MSI.CallInfo, Fn, Return, ActualArgs);
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RValue rvalue = CGF.EmitCall(MSI.CallInfo, Fn, Return, ActualArgs,
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nullptr, &CallSite);
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// Mark the call as noreturn if the method is marked noreturn and the
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// receiver cannot be null.
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if (Method && Method->hasAttr<NoReturnAttr>() && !ReceiverCanBeNull) {
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llvm::CallSite(CallSite).setDoesNotReturn();
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}
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return nullReturn.complete(CGF, rvalue, ResultType, CallArgs,
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requiresnullCheck ? Method : nullptr);
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RequiresNullCheck ? Method : nullptr);
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}
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static Qualifiers::GC GetGCAttrTypeForType(ASTContext &Ctx, QualType FQT) {
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@ -6620,7 +6669,7 @@ CGObjCNonFragileABIMac::GenerateMessageSend(CodeGen::CodeGenFunction &CGF,
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: EmitMessageSend(CGF, Return, ResultType,
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EmitSelector(CGF, Sel),
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Receiver, CGF.getContext().getObjCIdType(),
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false, CallArgs, Method, ObjCTypes);
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false, CallArgs, Method, Class, ObjCTypes);
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}
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llvm::GlobalVariable *
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@ -6783,7 +6832,7 @@ CGObjCNonFragileABIMac::GenerateMessageSendSuper(CodeGen::CodeGenFunction &CGF,
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: EmitMessageSend(CGF, Return, ResultType,
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EmitSelector(CGF, Sel),
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ObjCSuper.getPointer(), ObjCTypes.SuperPtrCTy,
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true, CallArgs, Method, ObjCTypes);
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true, CallArgs, Method, Class, ObjCTypes);
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}
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llvm::Value *CGObjCNonFragileABIMac::EmitSelector(CodeGenFunction &CGF,
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@ -0,0 +1,99 @@
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// RUN: %clang_cc1 -triple x86_64-apple-darwin10 -emit-llvm -o - %s | FileCheck %s -check-prefix=CHECK -check-prefix=CHECK-MRC
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// RUN: %clang_cc1 -triple x86_64-apple-darwin10 -emit-llvm -fobjc-arc -o - %s | FileCheck %s -check-prefix=CHECK -check-prefix=CHECK-ARC
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__attribute__((objc_root_class))
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@interface Root
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- (instancetype) init;
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@end
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@interface Base : Root
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@end
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@interface Middle : Base
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+ (void) abort __attribute__((noreturn));
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- (void) fail __attribute__((noreturn));
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@end
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@interface Derived : Middle
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@end
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// An arbitrary instance pointer may be null.
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void testInstanceMethod(Derived *x) {
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[x fail];
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}
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// CHECK-LABEL: @testInstanceMethod
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// CHECK: call void bitcast (i8* (i8*, i8*, ...)* @objc_msgSend to void (i8*, i8*)*)(i8* {{.*}}, i8* {{.*}}){{$}}
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// A direct call of a class method will normally never have a null receiver.
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void testClassMethod() {
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[Derived abort];
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}
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// CHECK-LABEL: @testClassMethod
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// CHECK: call void bitcast (i8* (i8*, i8*, ...)* @objc_msgSend to void (i8*, i8*)*)(i8* {{.*}}, i8* {{.*}}) [[NORETURN:#[0-9]+]]
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__attribute__((weak_import))
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@interface WeakMiddle : Base
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@end
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@interface WeakDerived : WeakMiddle
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+ (void) abort __attribute__((noreturn));
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@end
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// The class pointer of a weakly-imported class may be null.
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void testWeakImport() {
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[WeakDerived abort];
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}
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// CHECK-LABEL: @testWeakImport
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// CHECK: call void bitcast (i8* (i8*, i8*, ...)* @objc_msgSend to void (i8*, i8*)*)(i8* {{.*}}, i8* {{.*}}){{$}}
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@interface Derived (MyMethods)
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@end
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@implementation Derived (MyMethods)
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// In general, self can be reassigned, so we can't make stronger assumptions.
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// But ARC makes self const in an ordinary method.
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// TODO: do the analysis to take advantage of the dominant case where
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// self is not reassigned.
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- (void) testSelfInstanceMethod {
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[self fail];
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}
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// CHECK-LABEL: [Derived(MyMethods) testSelfInstanceMethod]
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// CHECK-MRC: call void bitcast (i8* (i8*, i8*, ...)* @objc_msgSend to void (i8*, i8*)*)(i8* {{.*}}, i8* {{.*}}){{$}}
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// CHECK-ARC: call void bitcast (i8* (i8*, i8*, ...)* @objc_msgSend to void (i8*, i8*)*)(i8* {{.*}}, i8* {{.*}}) [[NORETURN]]
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// The ARC rule doesn't apply in -init methods.
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- (id) initWhileTestingSelfInstanceMethod {
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self = [super init];
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[self fail];
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return self;
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}
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// CHECK-LABEL: [Derived(MyMethods) initWhileTestingSelfInstanceMethod]
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// CHECK: call void bitcast (i8* (i8*, i8*, ...)* @objc_msgSend to void (i8*, i8*)*)(i8* {{.*}}, i8* {{.*}}){{$}}
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// Same thing applies to class methods.
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+ (void) testSelfClassMethod {
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[self abort];
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}
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// CHECK-LABEL: [Derived(MyMethods) testSelfClassMethod]
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// CHECK-MRC: call void bitcast (i8* (i8*, i8*, ...)* @objc_msgSend to void (i8*, i8*)*)(i8* {{.*}}, i8* {{.*}}){{$}}
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// CHECK-ARC: call void bitcast (i8* (i8*, i8*, ...)* @objc_msgSend to void (i8*, i8*)*)(i8* {{.*}}, i8* {{.*}}) [[NORETURN]]
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// Super invocations may never be used with a null pointer; this is a
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// constraint on user code when it isn't enforced by the ARC const-self
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// rule.
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- (void) testSuperInstanceMethod {
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[super fail];
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}
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// CHECK-LABEL: [Derived(MyMethods) testSuperInstanceMethod]
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// CHECK: call void bitcast (i8* ([[SUPER_T:%.*]]*, i8*, ...)* @objc_msgSendSuper2 to void ([[SUPER_T]]*, i8*)*)([[SUPER_T]]* {{.*}}, i8* {{.*}}) [[NORETURN]]
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+ (void) testSuperClassMethod {
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[super abort];
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}
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// CHECK-LABEL: [Derived(MyMethods) testSuperClassMethod]
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// CHECK: call void bitcast (i8* ([[SUPER_T]]*, i8*, ...)* @objc_msgSendSuper2 to void ([[SUPER_T]]*, i8*)*)([[SUPER_T]]* {{.*}}, i8* {{.*}}) [[NORETURN]]
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@end
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// CHECK: attributes [[NORETURN]] = { noreturn }
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