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Dec 14, 2021
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Make Objective-C protocol metadata weak hidden #40486

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7fd49f1
IRGen: Default to `weak hidden` instead of `internal` linkage for obj…
aschwaighofer Nov 30, 2021
0d3af14
IRGen: Fix using weak linkage to avoid duplicate metadata by only app…
aschwaighofer Dec 9, 2021
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157 changes: 87 additions & 70 deletions lib/IRGen/GenClass.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1319,22 +1319,25 @@ namespace {
assert(TheExtension && "can't emit category data for a class");
ConstantInitBuilder builder(IGM);
auto fields = builder.beginStruct();
auto internalLinkage = llvm::GlobalVariable::InternalLinkage;

// struct category_t {
// char const *name;
fields.add(IGM.getAddrOfGlobalString(CategoryName));
// const class_t *theClass;
fields.add(getClassMetadataRef());
// const method_list_t *instanceMethods;
emitAndAddMethodList(fields, MethodListKind::InstanceMethods);
emitAndAddMethodList(fields, MethodListKind::InstanceMethods,
internalLinkage);
// const method_list_t *classMethods;
emitAndAddMethodList(fields, MethodListKind::ClassMethods);
emitAndAddMethodList(fields, MethodListKind::ClassMethods,
internalLinkage);
// const protocol_list_t *baseProtocols;
fields.add(buildProtocolList());
fields.add(buildProtocolList(internalLinkage));
// const property_list_t *properties;
fields.add(buildPropertyList(ForClass));
fields.add(buildPropertyList(ForClass, internalLinkage));
// const property_list_t *classProperties;
fields.add(buildPropertyList(ForMetaClass));
fields.add(buildPropertyList(ForMetaClass, internalLinkage));
// uint32_t size;
// FIXME: Clang does this by using non-ad-hoc types for ObjC runtime
// structures.
Expand All @@ -1343,13 +1346,15 @@ namespace {
// };

assert(fields.getNextOffsetFromGlobal() == size);
return buildGlobalVariable(fields, "_CATEGORY_", /*const*/ true);
return buildGlobalVariable(fields, "_CATEGORY_", /*const*/ true,
internalLinkage);
}

llvm::Constant *emitProtocol() {
ConstantInitBuilder builder(IGM);
auto fields = builder.beginStruct();
llvm::SmallString<64> nameBuffer;
auto weakLinkage = llvm::GlobalVariable::WeakAnyLinkage;

assert(isBuildingProtocol() && "not emitting a protocol");

Expand All @@ -1359,17 +1364,20 @@ namespace {
// char const *name;
fields.add(IGM.getAddrOfGlobalString(getEntityName(nameBuffer)));
// const protocol_list_t *baseProtocols;
fields.add(buildProtocolList());
fields.add(buildProtocolList(weakLinkage));
// const method_list_t *requiredInstanceMethods;
emitAndAddMethodList(fields, MethodListKind::InstanceMethods);
emitAndAddMethodList(fields, MethodListKind::InstanceMethods,
weakLinkage);
// const method_list_t *requiredClassMethods;
emitAndAddMethodList(fields, MethodListKind::ClassMethods);
emitAndAddMethodList(fields, MethodListKind::ClassMethods, weakLinkage);
// const method_list_t *optionalInstanceMethods;
emitAndAddMethodList(fields, MethodListKind::OptionalInstanceMethods);
emitAndAddMethodList(fields, MethodListKind::OptionalInstanceMethods,
weakLinkage);
// const method_list_t *optionalClassMethods;
emitAndAddMethodList(fields, MethodListKind::OptionalClassMethods);
emitAndAddMethodList(fields, MethodListKind::OptionalClassMethods,
weakLinkage);
// const property_list_t *properties;
fields.add(buildPropertyList(ForClass));
fields.add(buildPropertyList(ForClass, weakLinkage));

// uint32_t size;
// FIXME: Clang does this by using non-ad-hoc types for ObjC runtime
Expand All @@ -1391,11 +1399,12 @@ namespace {
// const char *demangledName;
fields.addNullPointer(IGM.Int8PtrTy);
// const property_list_t *classProperties;
fields.add(buildPropertyList(ForMetaClass));
fields.add(buildPropertyList(ForMetaClass, weakLinkage));
// };

assert(fields.getNextOffsetFromGlobal() == size);
return buildGlobalVariable(fields, "_PROTOCOL_", /*const*/ true);
return buildGlobalVariable(fields, "_PROTOCOL_", /*const*/ true,
weakLinkage);
}

void emitRODataFields(ConstantStructBuilder &b,
Expand Down Expand Up @@ -1456,12 +1465,14 @@ namespace {
b.add(buildName());

// const method_list_t *baseMethods;
emitAndAddMethodList(b, forMeta ? MethodListKind::ClassMethods
: MethodListKind::InstanceMethods);
emitAndAddMethodList(b,
forMeta ? MethodListKind::ClassMethods
: MethodListKind::InstanceMethods,
llvm::GlobalVariable::InternalLinkage);

// const protocol_list_t *baseProtocols;
// Apparently, this list is the same in the class and the metaclass.
b.add(buildProtocolList());
b.add(buildProtocolList(llvm::GlobalVariable::InternalLinkage));

// const ivar_list_t *ivars;
if (forMeta) {
Expand All @@ -1475,7 +1486,7 @@ namespace {
b.addNullPointer(IGM.Int8PtrTy);

// const property_list_t *baseProperties;
b.add(buildPropertyList(forMeta));
b.add(buildPropertyList(forMeta, llvm::GlobalVariable::InternalLinkage));

// If hasUpdater is true, the metadata update callback goes here.
if (hasUpdater) {
Expand Down Expand Up @@ -1503,7 +1514,8 @@ namespace {
// statically. Otherwise, the ObjC runtime may slide the InstanceSize
// based on changing base class layout.
return buildGlobalVariable(fields, dataSuffix,
/*const*/ forMeta || FieldLayout->isFixedSize());
/*const*/ forMeta || FieldLayout->isFixedSize(),
llvm::GlobalVariable::InternalLinkage);
}

private:
Expand Down Expand Up @@ -1723,7 +1735,8 @@ namespace {

/// Emit the method list and add the pointer to the `builder`.
void emitAndAddMethodList(ConstantInitBuilder::StructBuilder &builder,
MethodListKind kind) {
MethodListKind kind,
llvm::GlobalValue::LinkageTypes linkage) {
ArrayRef<MethodDescriptor> methods;
StringRef namePrefix;
switch (kind) {
Expand All @@ -1748,7 +1761,8 @@ namespace {
namePrefix = "_PROTOCOL_INSTANCE_METHODS_OPT_";
break;
}
llvm::Constant *methodListPtr = buildMethodList(methods, namePrefix);
llvm::Constant *methodListPtr =
buildMethodList(methods, namePrefix, linkage);
builder.add(methodListPtr);
}

Expand All @@ -1768,12 +1782,9 @@ namespace {
return null();
}

auto *gv_as_const = buildGlobalVariable(array, "_PROTOCOL_METHOD_TYPES_",
/*const*/ true,
/*likage*/ llvm::GlobalVariable::WeakAnyLinkage);
llvm::GlobalValue *gv = (llvm::GlobalValue *)gv_as_const;
gv->setVisibility(llvm::GlobalValue::HiddenVisibility);
return gv;
return buildGlobalVariable(array, "_PROTOCOL_METHOD_TYPES_",
/*const*/ true,
llvm::GlobalVariable::WeakAnyLinkage);
}

void buildExtMethodTypes(ConstantArrayBuilder &array,
Expand All @@ -1796,13 +1807,14 @@ namespace {
///
/// This method does not return a value of a predictable type.
llvm::Constant *buildMethodList(ArrayRef<MethodDescriptor> methods,
StringRef name) {
return buildOptionalList(methods, 3 * IGM.getPointerSize(), name,
/*isConst*/ false,
[&](ConstantArrayBuilder &descriptors,
MethodDescriptor descriptor) {
buildMethod(descriptors, descriptor);
});
StringRef name,
llvm::GlobalValue::LinkageTypes linkage) {
return buildOptionalList(
methods, 3 * IGM.getPointerSize(), name,
/*isConst*/ false, linkage,
[&](ConstantArrayBuilder &descriptors, MethodDescriptor descriptor) {
buildMethod(descriptors, descriptor);
});
}

/*** Protocols *********************************************************/
Expand All @@ -1819,16 +1831,15 @@ namespace {
/// };
///
/// This method does not return a value of a predictable type.
llvm::Constant *buildProtocolList() {
return buildOptionalList(Protocols, Size(0),
chooseNamePrefix("_PROTOCOLS_",
"_CATEGORY_PROTOCOLS_",
"_PROTOCOL_PROTOCOLS_"),
/*isConst*/ true,
[&](ConstantArrayBuilder &descriptors,
ProtocolDecl *protocol) {
buildProtocol(descriptors, protocol);
});
llvm::Constant *buildProtocolList(llvm::GlobalValue::LinkageTypes linkage) {
return buildOptionalList(
Protocols, Size(0),
chooseNamePrefix("_PROTOCOLS_", "_CATEGORY_PROTOCOLS_",
"_PROTOCOL_PROTOCOLS_"),
/*isConst*/ true, linkage,
[&](ConstantArrayBuilder &descriptors, ProtocolDecl *protocol) {
buildProtocol(descriptors, protocol);
});
}

void buildProtocol(ConstantArrayBuilder &array, ProtocolDecl *protocol) {
Expand Down Expand Up @@ -1949,12 +1960,12 @@ namespace {
/// This method does not return a value of a predictable type.
llvm::Constant *buildIvarList() {
Size eltSize = 3 * IGM.getPointerSize() + Size(8);
return buildOptionalList(Ivars, eltSize, "_IVARS_",
/*constant*/ true,
[&](ConstantArrayBuilder &descriptors,
Field field) {
buildIvar(descriptors, field);
});
return buildOptionalList(
Ivars, eltSize, "_IVARS_",
/*constant*/ true, llvm::GlobalVariable::InternalLinkage,
[&](ConstantArrayBuilder &descriptors, Field field) {
buildIvar(descriptors, field);
});
}

/*** Properties ********************************************************/
Expand Down Expand Up @@ -2062,12 +2073,14 @@ namespace {
/// };
///
/// This method does not return a value of a predictable type.
llvm::Constant *buildPropertyList(ForMetaClass_t classOrMeta) {
llvm::Constant *buildPropertyList(ForMetaClass_t classOrMeta,
llvm::GlobalValue::LinkageTypes linkage) {
if (classOrMeta == ForClass) {
return buildPropertyList(InstanceProperties,
chooseNamePrefix("_PROPERTIES_",
"_CATEGORY_PROPERTIES_",
"_PROTOCOL_PROPERTIES_"));
"_PROTOCOL_PROPERTIES_"),
linkage);
}

// Older OSs' libobjcs can't handle class property data.
Expand All @@ -2079,18 +2092,20 @@ namespace {
return buildPropertyList(ClassProperties,
chooseNamePrefix("_CLASS_PROPERTIES_",
"_CATEGORY_CLASS_PROPERTIES_",
"_PROTOCOL_CLASS_PROPERTIES_"));
"_PROTOCOL_CLASS_PROPERTIES_"),
linkage);
}

llvm::Constant *buildPropertyList(ArrayRef<VarDecl*> properties,
StringRef namePrefix) {
llvm::Constant *buildPropertyList(ArrayRef<VarDecl *> properties,
StringRef namePrefix,
llvm::GlobalValue::LinkageTypes linkage) {
Size eltSize = 2 * IGM.getPointerSize();
return buildOptionalList(properties, eltSize, namePrefix,
/*constant*/ true,
[&](ConstantArrayBuilder &descriptors,
VarDecl *property) {
buildProperty(descriptors, property);
});
return buildOptionalList(
properties, eltSize, namePrefix,
/*constant*/ true, linkage,
[&](ConstantArrayBuilder &descriptors, VarDecl *property) {
buildProperty(descriptors, property);
});
}

/*** General ***********************************************************/
Expand All @@ -2102,10 +2117,9 @@ namespace {
/// \param optionalEltSize - if non-zero, a size which needs
/// to be placed in the list header
template <class C, class Fn>
llvm::Constant *buildOptionalList(const C &objects,
Size optionalEltSize,
StringRef nameBase,
bool isConst,
llvm::Constant *buildOptionalList(const C &objects, Size optionalEltSize,
StringRef nameBase, bool isConst,
llvm::GlobalValue::LinkageTypes linkage,
Fn &&buildElement) {
if (objects.empty())
return null();
Expand Down Expand Up @@ -2144,9 +2158,9 @@ namespace {

fields.fillPlaceholderWithInt(countPosition, countType, count);

return buildGlobalVariable(fields, nameBase, isConst);
return buildGlobalVariable(fields, nameBase, isConst, linkage);
}

/// Get the name of the class or protocol to mangle into the ObjC symbol
/// name.
StringRef getEntityName(llvm::SmallVectorImpl<char> &buffer) const {
Expand All @@ -2173,9 +2187,9 @@ namespace {
/// Build a private global variable as a structure containing the
/// given fields.
template <class B>
llvm::Constant *buildGlobalVariable(B &fields, StringRef nameBase, bool isConst,
llvm::GlobalValue::LinkageTypes linkage =
llvm::GlobalVariable::InternalLinkage) {
llvm::Constant *
buildGlobalVariable(B &fields, StringRef nameBase, bool isConst,
llvm::GlobalValue::LinkageTypes linkage) {
llvm::SmallString<64> nameBuffer;
auto var =
fields.finishAndCreateGlobal(Twine(nameBase)
Expand All @@ -2186,6 +2200,9 @@ namespace {
IGM.getPointerAlignment(),
/*constant*/ true,
linkage);
if (linkage == llvm::GlobalVariable::WeakAnyLinkage) {
var->setVisibility(llvm::GlobalValue::HiddenVisibility);
}

switch (IGM.TargetInfo.OutputObjectFormat) {
case llvm::Triple::MachO:
Expand Down
2 changes: 1 addition & 1 deletion test/Concurrency/objc_async_protocol_irgen.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -9,7 +9,7 @@ let anyObject: AnyObject = (MyAsyncProtocol.self as AnyObject) // or something l
// Make sure we don't emit 2 copies of methods, due to a completion-handler
// version and another due to an async based version.

// CHECK-LABEL: @_PROTOCOL_INSTANCE_METHODS_MyAsyncProtocol = internal constant
// CHECK-LABEL: @_PROTOCOL_INSTANCE_METHODS_MyAsyncProtocol = weak hidden constant
// CHECK-SAME: selector_data(myAsyncMethod:)
// CHECK-NOT: selector_data(myAsyncMethod:)
// CHECK-SAME: align [[ALIGNMENT]]
6 changes: 3 additions & 3 deletions test/IRGen/generic_casts.swift
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Expand Up @@ -8,11 +8,11 @@ import Foundation
import gizmo

// -- Protocol records for cast-to ObjC protocols
// CHECK: @_PROTOCOL__TtP13generic_casts10ObjCProto1_ = internal constant
// CHECK: @_PROTOCOL__TtP13generic_casts10ObjCProto1_ = weak hidden constant
// CHECK: @"\01l_OBJC_LABEL_PROTOCOL_$__TtP13generic_casts10ObjCProto1_" = weak hidden global i8* bitcast ({{.*}} @_PROTOCOL__TtP13generic_casts10ObjCProto1_ to i8*), section {{"__DATA,__objc_protolist,coalesced,no_dead_strip"|"objc_protolist"|".objc_protolist\$B"}}
// CHECK: @"\01l_OBJC_PROTOCOL_REFERENCE_$__TtP13generic_casts10ObjCProto1_" = weak hidden global i8* bitcast ({{.*}} @_PROTOCOL__TtP13generic_casts10ObjCProto1_ to i8*), section {{"__DATA,__objc_protorefs,coalesced,no_dead_strip"|"objc_protorefs"|".objc_protorefs\$B"}}

// CHECK: @_PROTOCOL_NSRuncing = internal constant
// CHECK: @_PROTOCOL_NSRuncing = weak hidden constant
// CHECK: @"\01l_OBJC_LABEL_PROTOCOL_$_NSRuncing" = weak hidden global i8* bitcast ({{.*}} @_PROTOCOL_NSRuncing to i8*), section {{"__DATA,__objc_protolist,coalesced,no_dead_strip"|"objc_protolist"|".objc_protolist\$B"}}
// CHECK: @"\01l_OBJC_PROTOCOL_REFERENCE_$_NSRuncing" = weak hidden global i8* bitcast ({{.*}} @_PROTOCOL_NSRuncing to i8*), section {{"__DATA,__objc_protorefs,coalesced,no_dead_strip"|"objc_protorefs"|".objc_protorefs\$B"}}

Expand All @@ -23,7 +23,7 @@ import gizmo

// CHECK: @_DATA__TtC13generic_casts10ObjCClass2 = internal constant {{.*}} @_PROTOCOLS__TtC13generic_casts10ObjCClass2

// CHECK: @_PROTOCOL_PROTOCOLS__TtP13generic_casts10ObjCProto2_ = internal constant { i64, [1 x i8*] } {
// CHECK: @_PROTOCOL_PROTOCOLS__TtP13generic_casts10ObjCProto2_ = weak hidden constant { i64, [1 x i8*] } {
// CHECK: i64 1,
// CHECK: @_PROTOCOL__TtP13generic_casts10ObjCProto1_
// CHECK: }
Expand Down
2 changes: 1 addition & 1 deletion test/IRGen/objc_async_metadata.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -23,7 +23,7 @@ class MyClass: NSObject {
}

// CHECK: [[ENCODE_ASYNC_STRING_PROTO:@.*]] = private unnamed_addr constant [15 x i8] c"v32@0:8@16@?24\00"
// CHECK-LABEL: @_PROTOCOL_INSTANCE_METHODS__TtP19objc_async_metadata7MyProto_ = internal constant
// CHECK-LABEL: @_PROTOCOL_INSTANCE_METHODS__TtP19objc_async_metadata7MyProto_ = weak hidden constant
// CHECK-SAME: _selector_data(myProtoRequirement:completionHandler:)
// CHECK-SAME: [15 x i8]* [[ENCODE_ASYNC_STRING_PROTO]]

Expand Down
6 changes: 3 additions & 3 deletions test/IRGen/objc_properties.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -269,7 +269,7 @@ class SomeWrapperTests {
// CHECK: i8* getelementptr inbounds ([11 x i8], [11 x i8]* [[SETTER_SIGNATURE]], i64 0, i64 0),
// CHECK: @"$s15objc_properties4TreeC6parentACSgvsTo{{(.ptrauth)?}}"

// CHECK: @_PROTOCOL__TtP15objc_properties5Proto_ = internal constant { {{.+}} } {
// CHECK: @_PROTOCOL__TtP15objc_properties5Proto_ = weak hidden constant { {{.+}} } {
// CHECK: i8* null,
// CHECK: i8* getelementptr inbounds ([{{.+}} x i8], [{{.+}} x i8]* {{@.+}}, i64 0, i64 0),
// CHECK: i8* null,
Expand All @@ -289,7 +289,7 @@ class SomeWrapperTests {
// CHECK: [[PROTOCOLPROPERTY_NAME:@.+]] = private unnamed_addr constant [6 x i8] c"value\00"
// CHECK: [[PROTOCOLPROPERTY_ATTRS:@.+]] = private unnamed_addr constant [7 x i8] c"Tq,N,R\00"

// CHECK: @_PROTOCOL_PROPERTIES__TtP15objc_properties5Proto_ = internal constant { {{.*}}] } {
// CHECK: @_PROTOCOL_PROPERTIES__TtP15objc_properties5Proto_ = weak hidden constant { {{.*}}] } {
// CHECK: i32 16,
// CHECK: i32 1,
// CHECK: [1 x { i8*, i8* }] [{
Expand All @@ -301,7 +301,7 @@ class SomeWrapperTests {
// CHECK-NEW: [[PROTOCOLCLASSPROPERTY_NAME:@.+]] = private unnamed_addr constant [15 x i8] c"sharedInstance\00"
// CHECK-NEW: [[PROTOCOLCLASSPROPERTY_ATTRS:@.+]] = private unnamed_addr constant [7 x i8] c"T@,N,&\00"

// CHECK-NEW: @_PROTOCOL_CLASS_PROPERTIES__TtP15objc_properties5Proto_ = internal constant { {{.*}}] } {
// CHECK-NEW: @_PROTOCOL_CLASS_PROPERTIES__TtP15objc_properties5Proto_ = weak hidden constant { {{.*}}] } {
// CHECK-NEW: i32 16,
// CHECK-NEW: i32 1,
// CHECK-NEW: [1 x { i8*, i8* }] [{
Expand Down
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