slavapestov updated this revision to Diff 192378.
slavapestov marked 2 inline comments as done.
slavapestov added a comment.
Second revision adds the following:
- Validation of the attribute in Sema
- Sema tests for the above
- Correct behavior of super method calls of a class with the attribute
- More comprehensive CodeGen tests
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D59628/new/
https://reviews.llvm.org/D59628
Files:
include/clang/Basic/Attr.td
include/clang/Basic/AttrDocs.td
include/clang/Basic/DiagnosticSemaKinds.td
include/clang/Basic/ObjCRuntime.h
lib/CodeGen/CGObjCMac.cpp
lib/Sema/SemaDeclAttr.cpp
lib/Sema/SemaDeclObjC.cpp
test/CodeGenObjC/class-stubs.m
test/Misc/pragma-attribute-supported-attributes-list.test
test/SemaObjC/class-stub-attr-unsupported.m
test/SemaObjC/class-stub-attr.m
Index: test/SemaObjC/class-stub-attr.m
===================================================================
--- /dev/null
+++ test/SemaObjC/class-stub-attr.m
@@ -0,0 +1,27 @@
+// RUN: %clang -target x86_64-apple-darwin -fsyntax-only -Xclang -verify %s
+// RUN: %clang -target x86_64-apple-darwin -x objective-c++ -fsyntax-only -Xclang -verify %s
+
+@interface NSObject
+@end
+
+__attribute__((objc_class_stub))
+@interface MissingSubclassingRestrictedAttribute : NSObject // expected-error {{'objc_class_stub' attribute cannot be specified on a class that does not have the 'objc_subclassing_restricted' attribute}}
+@end
+
+__attribute__((objc_class_stub))
+__attribute__((objc_subclassing_restricted))
+@interface ValidClassStubAttribute : NSObject
+@end
+
+@implementation ValidClassStubAttribute // expected-error {{cannot declare implementation of a class declared with the 'objc_class_stub' attribute}}
+@end
+
+@implementation ValidClassStubAttribute (MyCategory)
+@end
+
+__attribute__((objc_class_stub(123))) // expected-error {{'objc_class_stub' attribute takes no arguments}}
+@interface InvalidClassStubAttribute : NSObject
+@end
+
+__attribute__((objc_class_stub)) // expected-error {{'objc_class_stub' attribute only applies to Objective-C interfaces}}
+int cannotHaveObjCClassStubAttribute() {}
Index: test/SemaObjC/class-stub-attr-unsupported.m
===================================================================
--- /dev/null
+++ test/SemaObjC/class-stub-attr-unsupported.m
@@ -0,0 +1,10 @@
+// RUN: %clang -target i386-apple-darwin -fsyntax-only -Xclang -verify %s
+// RUN: %clang -target i386-apple-darwin -x objective-c++ -fsyntax-only -Xclang -verify %s
+
+@interface NSObject
+@end
+
+__attribute__((objc_class_stub))
+__attribute__((objc_subclassing_restricted))
+@interface StubClass : NSObject // expected-error {{'objc_class_stub' attribute is not supported for this target}}
+@end
Index: test/Misc/pragma-attribute-supported-attributes-list.test
===================================================================
--- test/Misc/pragma-attribute-supported-attributes-list.test
+++ test/Misc/pragma-attribute-supported-attributes-list.test
@@ -95,6 +95,7 @@
// CHECK-NEXT: ObjCBridge (SubjectMatchRule_record, SubjectMatchRule_type_alias)
// CHECK-NEXT: ObjCBridgeMutable (SubjectMatchRule_record)
// CHECK-NEXT: ObjCBridgeRelated (SubjectMatchRule_record)
+// CHECK-NEXT: ObjCClassStub (SubjectMatchRule_objc_interface)
// CHECK-NEXT: ObjCCompleteDefinition (SubjectMatchRule_objc_interface)
// CHECK-NEXT: ObjCDesignatedInitializer (SubjectMatchRule_objc_method)
// CHECK-NEXT: ObjCException (SubjectMatchRule_objc_interface)
Index: test/CodeGenObjC/class-stubs.m
===================================================================
--- /dev/null
+++ test/CodeGenObjC/class-stubs.m
@@ -0,0 +1,81 @@
+// RUN: %clang_cc1 -triple x86_64-apple-darwin10 -Wno-objc-root-class -emit-llvm -o - %s | \
+// RUN: FileCheck %s
+
+// -- classref for the message send in main()
+//
+// The class is declared with objc_class_stub, so LSB of the class pointer
+// must be set to 1.
+//
+// CHECK-LABEL: @"OBJC_CLASSLIST_REFERENCES_$_" = private global i8* getelementptr (i8, i8* bitcast (%struct._class_t* @"OBJC_CLASS_$_Base" to i8*), i32 1), section "__DATA,__objc_classrefs,regular,no_dead_strip", align 8
+
+// -- classref for the super message send in anotherClassMethod()
+//
+// Metaclasses do not use the "stub" mechanism and are referenced statically.
+//
+// CHECK-LABEL: @"OBJC_CLASSLIST_SUP_REFS_$_" = private global %struct._class_t* @"OBJC_METACLASS_$_Derived", section "__DATA,__objc_superrefs,regular,no_dead_strip", align 8
+
+// -- classref for the super message send in anotherInstanceMethod()
+//
+// The class is declared with objc_class_stub, so LSB of the class pointer
+// must be set to 1.
+//
+// CHECK-LABEL: @"OBJC_CLASSLIST_SUP_REFS_$_.1" = private global i8* getelementptr (i8, i8* bitcast (%struct._class_t* @"OBJC_CLASS_$_Derived" to i8*), i32 1), section "__DATA,__objc_superrefs,regular,no_dead_strip", align 8
+
+__attribute__((objc_class_stub))
+__attribute__((objc_subclassing_restricted))
+@interface Base
++ (void) classMethod;
+- (void) instanceMethod;
+@end
+
+__attribute__((objc_class_stub))
+__attribute__((objc_subclassing_restricted))
+@interface Derived : Base
+@end
+
+int main() {
+ [Base classMethod];
+}
+// CHECK-LABEL: define i32 @main()
+// CHECK-NEXT: entry:
+// CHECK-NEXT: [[CLASS:%.*]] = call %struct._class_t* @objc_loadClassref(i8** @"OBJC_CLASSLIST_REFERENCES_$_")
+// CHECK-NEXT: [[SELECTOR:%.*]] = load i8*, i8** @OBJC_SELECTOR_REFERENCES_
+// CHECK-NEXT: [[RECEIVER:%.*]] = bitcast %struct._class_t* [[CLASS]] to i8*
+// CHECK-NEXT: call void bitcast (i8* (i8*, i8*, ...)* @objc_msgSend to void (i8*, i8*)*)(i8* [[RECEIVER]], i8* [[SELECTOR]])
+// CHECK-NEXT: ret i32 0
+
+// CHECK-LABEL: declare %struct._class_t* @objc_loadClassref(i8**)
+// CHECK-SAME: [[ATTRLIST:#.*]]
+
+@implementation Derived (MyCategory)
+
++ (void) anotherClassMethod {
+ [super classMethod];
+}
+// CHECK-LABEL: define internal void @"\01+[Derived(MyCategory) anotherClassMethod]"(i8* %self, i8* %_cmd) #0 {
+// CHECK-NEXT: entry:
+// CHECK: [[SUPER:%.*]] = alloca %struct._objc_super, align 8
+// CHECK: [[METACLASS_REF:%.*]] = load %struct._class_t*, %struct._class_t** @"OBJC_CLASSLIST_SUP_REFS_$_", align 8
+// CHECK: [[CAST_METACLASS_REF:%.*]] = bitcast %struct._class_t* [[METACLASS_REF]] to i8*
+// CHECK: [[DEST:%.*]] = getelementptr inbounds %struct._objc_super, %struct._objc_super* [[SUPER]], i32 0, i32 1
+// CHECK: store i8* [[CAST_METACLASS_REF]], i8** [[DEST]], align 8
+// CHECK: call void bitcast (i8* (%struct._objc_super*, i8*, ...)* @objc_msgSendSuper2 to void (%struct._objc_super*, i8*)*)(%struct._objc_super* [[SUPER]], i8* {{%.*}})
+// CHECK: ret void
+
+- (void) anotherInstanceMethod {
+ [super instanceMethod];
+}
+// CHECK-LABEL: define internal void @"\01-[Derived(MyCategory) anotherInstanceMethod]"(%0* %self, i8* %_cmd) #0 {
+// CHECK-NEXT: entry:
+// CHECK: [[SUPER:%.*]] = alloca %struct._objc_super, align 8
+// CHECK: [[CLASS_REF:%.*]] = call %struct._class_t* @objc_loadClassref(i8** @"OBJC_CLASSLIST_SUP_REFS_$_.1")
+// CHECK: [[CAST_CLASS_REF:%.*]] = bitcast %struct._class_t* [[CLASS_REF]] to i8*
+// CHECK: [[DEST:%.*]] = getelementptr inbounds %struct._objc_super, %struct._objc_super* [[SUPER]], i32 0, i32 1
+// CHECK: store i8* [[CAST_CLASS_REF]], i8** [[DEST]], align 8
+// CHECK: call void bitcast (i8* (%struct._objc_super*, i8*, ...)* @objc_msgSendSuper2 to void (%struct._objc_super*, i8*)*)(%struct._objc_super* [[SUPER]], i8* {{%.*}})
+// CHECK: ret void
+
+@end
+
+// -- calls to objc_loadClassRef() are readnone
+// CHECK: attributes [[ATTRLIST]] = { nounwind nonlazybind readnone }
Index: lib/Sema/SemaDeclObjC.cpp
===================================================================
--- lib/Sema/SemaDeclObjC.cpp
+++ lib/Sema/SemaDeclObjC.cpp
@@ -4094,6 +4094,10 @@
}
}
+ if (IDecl->hasAttr<ObjCClassStubAttr>()) {
+ Diag(IC->getLocation(), diag::err_implementation_of_class_stub);
+ }
+
if (LangOpts.ObjCRuntime.isNonFragile()) {
while (IDecl->getSuperClass()) {
DiagnoseDuplicateIvars(IDecl, IDecl->getSuperClass());
@@ -4122,6 +4126,15 @@
Diag(Super->getLocation(), diag::note_class_declared);
}
}
+
+ if (IntfDecl->hasAttr<ObjCClassStubAttr>()) {
+ if (!getLangOpts().ObjCRuntime.allowsClassStubs()) {
+ Diag(IntfDecl->getLocation(), diag::err_class_stub_not_supported);
+ }
+ if (!IntfDecl->hasAttr<ObjCSubclassingRestrictedAttr>()) {
+ Diag(IntfDecl->getLocation(), diag::err_class_stub_subclassing_mismatch);
+ }
+ }
}
DiagnoseVariableSizedIvars(*this, OCD);
if (isInterfaceDeclKind) {
Index: lib/Sema/SemaDeclAttr.cpp
===================================================================
--- lib/Sema/SemaDeclAttr.cpp
+++ lib/Sema/SemaDeclAttr.cpp
@@ -7099,6 +7099,9 @@
case ParsedAttr::AT_ObjCSubclassingRestricted:
handleSimpleAttribute<ObjCSubclassingRestrictedAttr>(S, D, AL);
break;
+ case ParsedAttr::AT_ObjCClassStub:
+ handleSimpleAttribute<ObjCClassStubAttr>(S, D, AL);
+ break;
case ParsedAttr::AT_ObjCCompleteDefinition:
handleSimpleAttribute<ObjCCompleteDefinitionAttr>(S, D, AL);
break;
Index: lib/CodeGen/CGObjCMac.cpp
===================================================================
--- lib/CodeGen/CGObjCMac.cpp
+++ lib/CodeGen/CGObjCMac.cpp
@@ -726,6 +726,28 @@
"objc_begin_catch");
}
+ /// Class objc_loadClassref (void *)
+ ///
+ /// Loads from a classref. For Objective-C stub classes, this invokes the
+ /// initialization callback stored inside the stub. For all other classes
+ /// this simply dereferences the pointer.
+ llvm::Constant *getLoadClassrefFn() const {
+ // Add the non-lazy-bind attribute, since objc_loadClassref is likely to
+ // be called a lot.
+ //
+ // Also it is safe to make it readnone, since we never load or store the
+ // classref except by calling this function.
+ llvm::Type *params[] = { Int8PtrPtrTy };
+ return CGM.CreateRuntimeFunction(
+ llvm::FunctionType::get(ClassnfABIPtrTy, params, false),
+ "objc_loadClassref",
+ llvm::AttributeList::get(CGM.getLLVMContext(),
+ llvm::AttributeList::FunctionIndex,
+ {llvm::Attribute::NonLazyBind,
+ llvm::Attribute::ReadNone,
+ llvm::Attribute::NoUnwind}));
+ }
+
llvm::StructType *EHTypeTy;
llvm::Type *EHTypePtrTy;
@@ -1469,6 +1491,12 @@
bool isMetaclass,
ForDefinition_t isForDefinition);
+ llvm::Constant *GetClassGlobalForClassRef(const ObjCInterfaceDecl *ID);
+
+ llvm::Value *EmitLoadOfClassRef(CodeGenFunction &CGF,
+ const ObjCInterfaceDecl *ID,
+ llvm::GlobalVariable *Entry);
+
/// EmitClassRef - Return a Value*, of type ObjCTypes.ClassPtrTy,
/// for the given class reference.
llvm::Value *EmitClassRef(CodeGenFunction &CGF,
@@ -7236,31 +7264,62 @@
return llvm::ConstantExpr::getBitCast(GV, ObjCTypes.ClassnfABIPtrTy);
}
+llvm::Constant *
+CGObjCNonFragileABIMac::GetClassGlobalForClassRef(const ObjCInterfaceDecl *ID) {
+ auto *ClassGV = GetClassGlobal(ID, /*metaclass*/ false, NotForDefinition);
+
+ if (!ID->hasAttr<ObjCClassStubAttr>())
+ return ClassGV;
+
+ ClassGV = llvm::ConstantExpr::getPointerCast(ClassGV, ObjCTypes.Int8PtrTy);
+
+ // Stub classes are pointer-aligned. Classrefs pointing at stub classes
+ // must set the least significant bit set to 1.
+ auto *Idx = llvm::ConstantInt::get(CGM.Int32Ty, 1);
+ return llvm::ConstantExpr::getGetElementPtr(CGM.Int8Ty, ClassGV, Idx);
+}
+
+llvm::Value *
+CGObjCNonFragileABIMac::EmitLoadOfClassRef(CodeGenFunction &CGF,
+ const ObjCInterfaceDecl *ID,
+ llvm::GlobalVariable *Entry) {
+ if (ID && ID->hasAttr<ObjCClassStubAttr>()) {
+ // Classrefs pointing at Objective-C stub classes must be loaded by calling
+ // a special runtime function.
+ return CGF.EmitRuntimeCall(
+ ObjCTypes.getLoadClassrefFn(), Entry, "load_classref_result");
+ }
+
+ CharUnits Align = CGF.getPointerAlign();
+ return CGF.Builder.CreateAlignedLoad(Entry, Align);
+}
+
llvm::Value *
CGObjCNonFragileABIMac::EmitClassRefFromId(CodeGenFunction &CGF,
IdentifierInfo *II,
const ObjCInterfaceDecl *ID) {
- CharUnits Align = CGF.getPointerAlign();
llvm::GlobalVariable *&Entry = ClassReferences[II];
if (!Entry) {
llvm::Constant *ClassGV;
if (ID) {
- ClassGV = GetClassGlobal(ID, /*metaclass*/ false, NotForDefinition);
+ ClassGV = GetClassGlobalForClassRef(ID);
} else {
ClassGV = GetClassGlobal((getClassSymbolPrefix() + II->getName()).str(),
NotForDefinition);
+ assert(ClassGV->getType() == ObjCTypes.ClassnfABIPtrTy);
}
- Entry = new llvm::GlobalVariable(CGM.getModule(), ObjCTypes.ClassnfABIPtrTy,
+ Entry = new llvm::GlobalVariable(CGM.getModule(), ClassGV->getType(),
false, llvm::GlobalValue::PrivateLinkage,
ClassGV, "OBJC_CLASSLIST_REFERENCES_$_");
- Entry->setAlignment(Align.getQuantity());
+ Entry->setAlignment(CGF.getPointerAlign().getQuantity());
Entry->setSection(GetSectionName("__objc_classrefs",
"regular,no_dead_strip"));
CGM.addCompilerUsedGlobal(Entry);
}
- return CGF.Builder.CreateAlignedLoad(Entry, Align);
+
+ return EmitLoadOfClassRef(CGF, ID, Entry);
}
llvm::Value *CGObjCNonFragileABIMac::EmitClassRef(CodeGenFunction &CGF,
@@ -7282,20 +7341,20 @@
llvm::Value *
CGObjCNonFragileABIMac::EmitSuperClassRef(CodeGenFunction &CGF,
const ObjCInterfaceDecl *ID) {
- CharUnits Align = CGF.getPointerAlign();
llvm::GlobalVariable *&Entry = SuperClassReferences[ID->getIdentifier()];
if (!Entry) {
- auto ClassGV = GetClassGlobal(ID, /*metaclass*/ false, NotForDefinition);
- Entry = new llvm::GlobalVariable(CGM.getModule(), ObjCTypes.ClassnfABIPtrTy,
+ auto ClassGV = GetClassGlobalForClassRef(ID);
+ Entry = new llvm::GlobalVariable(CGM.getModule(), ClassGV->getType(),
false, llvm::GlobalValue::PrivateLinkage,
ClassGV, "OBJC_CLASSLIST_SUP_REFS_$_");
- Entry->setAlignment(Align.getQuantity());
+ Entry->setAlignment(CGF.getPointerAlign().getQuantity());
Entry->setSection(GetSectionName("__objc_superrefs",
"regular,no_dead_strip"));
CGM.addCompilerUsedGlobal(Entry);
}
- return CGF.Builder.CreateAlignedLoad(Entry, Align);
+
+ return EmitLoadOfClassRef(CGF, ID, Entry);
}
/// EmitMetaClassRef - Return a Value * of the address of _class_t
Index: include/clang/Basic/ObjCRuntime.h
===================================================================
--- include/clang/Basic/ObjCRuntime.h
+++ include/clang/Basic/ObjCRuntime.h
@@ -430,6 +430,20 @@
}
}
+ /// Returns true if this Objective-C runtime supports Objective-C class
+ /// stubs.
+ bool allowsClassStubs() const {
+ switch (getKind()) {
+ case FragileMacOSX: return false;
+ case GCC: return false;
+ case MacOSX: return true;
+ case GNUstep: return false;
+ case ObjFW: return false;
+ case iOS: return true;
+ case WatchOS: return true;
+ }
+ }
+
/// Try to parse an Objective-C runtime specification from the given
/// string.
///
Index: include/clang/Basic/DiagnosticSemaKinds.td
===================================================================
--- include/clang/Basic/DiagnosticSemaKinds.td
+++ include/clang/Basic/DiagnosticSemaKinds.td
@@ -894,6 +894,14 @@
def err_restricted_superclass_mismatch : Error<
"cannot subclass a class that was declared with the "
"'objc_subclassing_restricted' attribute">;
+def err_class_stub_subclassing_mismatch : Error<
+ "'objc_class_stub' attribute cannot be specified on a class that does not "
+ "have the 'objc_subclassing_restricted' attribute">;
+def err_implementation_of_class_stub : Error<
+ "cannot declare implementation of a class declared with the "
+ "'objc_class_stub' attribute">;
+def err_class_stub_not_supported : Error<
+ "'objc_class_stub' attribute is not supported for this target">;
def warn_objc_root_class_missing : Warning<
"class %0 defined without specifying a base class">,
InGroup<ObjCRootClass>;
Index: include/clang/Basic/AttrDocs.td
===================================================================
--- include/clang/Basic/AttrDocs.td
+++ include/clang/Basic/AttrDocs.td
@@ -1084,6 +1084,23 @@
}];
}
+def ObjCClassStubDocs : Documentation {
+ let Category = DocCatType;
+ let Content = [{
+This attribute specifies that the Objective-C class to which it applies is
+instantiated at runtime.
+
+Unlike ``__attribute__((objc_runtime_visible))``, a class having this attribute
+still has a "class stub" that is visible to the linker. This allows categories
+to be defined. Static message sends with the class as a receiver use a special
+access pattern to ensure the class is lazily instantiated from the class stub.
+
+Classes annotated with this attribute cannot be subclassed and cannot have
+implementations defined for them. This attribute is intended for use in
+Swift generated headers for classes defined in Swift.
+ }];
+}
+
def ObjCBoxableDocs : Documentation {
let Category = DocCatFunction;
let Content = [{
Index: include/clang/Basic/Attr.td
===================================================================
--- include/clang/Basic/Attr.td
+++ include/clang/Basic/Attr.td
@@ -1790,6 +1790,13 @@
let Documentation = [ObjCRuntimeVisibleDocs];
}
+def ObjCClassStub : Attr {
+ let Spellings = [Clang<"objc_class_stub">];
+ let Subjects = SubjectList<[ObjCInterface], ErrorDiag>;
+ let Documentation = [ObjCClassStubDocs];
+ let LangOpts = [ObjC];
+}
+
def ObjCBoxable : Attr {
let Spellings = [Clang<"objc_boxable">];
let Subjects = SubjectList<[Record], ErrorDiag>;
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