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Don't use a global_ctors comdat for globals that aren't externally visible 

In particular, if you have two identical templates in different TUs in
anonymous namespaces, we would use the same global_ctors comdat key for
both. As a result, only one would be run.

llvm-svn: 219806
This commit is contained in:
Reid Kleckner 2014-10-15 16:38:00 +00:00
parent 8476abe288
commit 72d03bee64
2 changed files with 24 additions and 10 deletions
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18
clang/lib/CodeGen/CGDeclCXX.cpp
View File

@ -292,7 +292,8 @@ CodeGenModule::EmitCXXGlobalVarDeclInitFunc(const VarDecl *D,
CodeGenFunction(*this).GenerateCXXGlobalVarDeclInitFunc(Fn, D, Addr,
PerformInit);
llvm::GlobalVariable *Key = supportsCOMDAT() ? Addr : nullptr;
llvm::GlobalVariable *COMDATKey =
supportsCOMDAT() && D->isExternallyVisible() ? Addr : nullptr;
if (D->getTLSKind()) {
// FIXME: Should we support init_priority for thread_local?
@ -310,8 +311,7 @@ CodeGenModule::EmitCXXGlobalVarDeclInitFunc(const VarDecl *D,
OrderGlobalInits Key(IPA->getPriority(), PrioritizedCXXGlobalInits.size());
PrioritizedCXXGlobalInits.push_back(std::make_pair(Key, Fn));
DelayedCXXInitPosition.erase(D);
} else if (D->getTemplateSpecializationKind() != TSK_ExplicitSpecialization &&
D->getTemplateSpecializationKind() != TSK_Undeclared) {
} else if (isTemplateInstantiation(D->getTemplateSpecializationKind())) {
// C++ [basic.start.init]p2:
// Definitions of explicitly specialized class template static data
// members have ordered initialization. Other class template static data
@ -320,16 +320,16 @@ CodeGenModule::EmitCXXGlobalVarDeclInitFunc(const VarDecl *D,
//
// As a consequence, we can put them into their own llvm.global_ctors entry.
//
// In addition, put the initializer into a COMDAT group with the global
// being initialized. On most platforms, this is a minor startup time
// optimization. In the MS C++ ABI, there are no guard variables, so this
// COMDAT key is required for correctness.
AddGlobalCtor(Fn, 65535, Key);
// If the global is externally visible, put the initializer into a COMDAT
// group with the global being initialized. On most platforms, this is a
// minor startup time optimization. In the MS C++ ABI, there are no guard
// variables, so this COMDAT key is required for correctness.
AddGlobalCtor(Fn, 65535, COMDATKey);
DelayedCXXInitPosition.erase(D);
} else if (D->hasAttr<SelectAnyAttr>()) {
// SelectAny globals will be comdat-folded. Put the initializer into a COMDAT
// group associated with the global, so the initializers get folded too.
AddGlobalCtor(Fn, 65535, Key);
AddGlobalCtor(Fn, 65535, COMDATKey);
DelayedCXXInitPosition.erase(D);
} else {
llvm::DenseMap<const Decl *, unsigned>::iterator I =

16
clang/test/CodeGenCXX/static-member-variable-explicit-specialization.cpp
View File

@ -14,7 +14,7 @@ template<> int A<char>::a;
// ALL: @_ZN1AIbE1aE = global i32 10
template<> int A<bool>::a = 10;
// ALL: @llvm.global_ctors = appending global [7 x { i32, void ()*, i8* }]
// ALL: @llvm.global_ctors = appending global [8 x { i32, void ()*, i8* }]
// ELF: [{ i32, void ()*, i8* } { i32 65535, void ()* @[[unordered1:[^,]*]], i8* bitcast (i32* @_ZN1AIsE1aE to i8*) },
// MACHO: [{ i32, void ()*, i8* } { i32 65535, void ()* @[[unordered1:[^,]*]], i8* null },
@ -34,6 +34,8 @@ template<> int A<bool>::a = 10;
// ELF: { i32, void ()*, i8* } { i32 65535, void ()* @[[unordered6:[^,]*]], i8* @_Z1xIcE },
// MACHO: { i32, void ()*, i8* } { i32 65535, void ()* @[[unordered6:[^,]*]], i8* null },
// ALL: { i32, void ()*, i8* } { i32 65535, void ()* @[[unordered7:[^,]*]], i8* null },
// ALL: { i32, void ()*, i8* } { i32 65535, void ()* @_GLOBAL__sub_I_static_member_variable_explicit_specialization.cpp, i8* null }]
template int A<short>::a; // Unordered
@ -67,6 +69,13 @@ struct b {
template<typename T> T b::i = foo();
template int b::i<int>;
}
namespace {
template<typename T> struct Internal { static int a; };
template<typename T> int Internal<T>::a = foo();
}
int *use_internal_a = &Internal<int>::a;
// ALL: define internal void @[[unordered1]]
// ALL: call i32 @foo()
// ALL: store {{.*}} @_ZN1AIsE1aE
@ -97,6 +106,11 @@ template int b::i<int>;
// ALL: store {{.*}} @_Z1xIcE
// ALL: ret
// ALL: define internal void @[[unordered7]]
// ALL: call i32 @foo()
// ALL: store {{.*}} @_ZN12_GLOBAL__N_18InternalIiE1aE
// ALL: ret
// ALL: define internal void @_GLOBAL__sub_I_static_member_variable_explicit_specialization.cpp()
// We call unique stubs for every ordered dynamic initializer in the TU.
// ALL: call