hiraditya updated this revision to Diff 71827.
hiraditya added a comment.
Added a test case (contributed by Eric).
https://reviews.llvm.org/D24682
Files:
clang/lib/CodeGen/CGCXX.cpp
clang/test/CodeGenCXX/alias-available-externally.cpp
Index: clang/test/CodeGenCXX/alias-available-externally.cpp
===================================================================
--- /dev/null
+++ clang/test/CodeGenCXX/alias-available-externally.cpp
@@ -0,0 +1,19 @@
+// RUN: %clang_cc1 -O1 -std=c++11 -emit-llvm -disable-llvm-passes -o - %s |
FileCheck %s
+// Clang should not generate alias to available_externally definitions.
+// Check that the destructor of Foo is defined.
+// CHECK: define linkonce_odr void @_ZN3FooD2Ev
+template <class CharT>
+struct String {
+ String() {}
+ ~String();
+};
+
+template <class CharT>
+inline __attribute__((visibility("hidden"), always_inline))
+String<CharT>::~String() {}
+
+extern template struct String<char>;
+
+struct Foo : public String<char> { Foo() { String<char> s; } };
+
+Foo f;
Index: clang/lib/CodeGen/CGCXX.cpp
===================================================================
--- clang/lib/CodeGen/CGCXX.cpp
+++ clang/lib/CodeGen/CGCXX.cpp
@@ -134,6 +134,16 @@
llvm::GlobalValue::LinkageTypes TargetLinkage =
getFunctionLinkage(TargetDecl);
+ // Disallow aliases to available_externally because available_externally
+ // will not be there in the end to allow the creation of the alias (PR30341).
+ // FIXME: An extern template instantiation will create functions with
+ // linkage "AvailableExternally". In libc++, some classes also define
+ // members with attribute "AlwaysInline" and expect no reference to
+ // be generated. It is desirable to reenable this optimisation after
+ // corresponding LLVM changes.
+ if (TargetLinkage == llvm::GlobalValue::AvailableExternallyLinkage)
+ return true;
+
// Check if we have it already.
StringRef MangledName = getMangledName(AliasDecl);
llvm::GlobalValue *Entry = GetGlobalValue(MangledName);
@@ -157,13 +167,7 @@
// Instead of creating as alias to a linkonce_odr, replace all of the uses
// of the aliasee.
if (llvm::GlobalValue::isDiscardableIfUnused(Linkage) &&
- (TargetLinkage != llvm::GlobalValue::AvailableExternallyLinkage ||
- !TargetDecl.getDecl()->hasAttr<AlwaysInlineAttr>())) {
- // FIXME: An extern template instantiation will create functions with
- // linkage "AvailableExternally". In libc++, some classes also define
- // members with attribute "AlwaysInline" and expect no reference to
- // be generated. It is desirable to reenable this optimisation after
- // corresponding LLVM changes.
+ !TargetDecl.getDecl()->hasAttr<AlwaysInlineAttr>()) {
addReplacement(MangledName, Aliasee);
return false;
}
Index: clang/test/CodeGenCXX/alias-available-externally.cpp
===================================================================
--- /dev/null
+++ clang/test/CodeGenCXX/alias-available-externally.cpp
@@ -0,0 +1,19 @@
+// RUN: %clang_cc1 -O1 -std=c++11 -emit-llvm -disable-llvm-passes -o - %s | FileCheck %s
+// Clang should not generate alias to available_externally definitions.
+// Check that the destructor of Foo is defined.
+// CHECK: define linkonce_odr void @_ZN3FooD2Ev
+template <class CharT>
+struct String {
+ String() {}
+ ~String();
+};
+
+template <class CharT>
+inline __attribute__((visibility("hidden"), always_inline))
+String<CharT>::~String() {}
+
+extern template struct String<char>;
+
+struct Foo : public String<char> { Foo() { String<char> s; } };
+
+Foo f;
Index: clang/lib/CodeGen/CGCXX.cpp
===================================================================
--- clang/lib/CodeGen/CGCXX.cpp
+++ clang/lib/CodeGen/CGCXX.cpp
@@ -134,6 +134,16 @@
llvm::GlobalValue::LinkageTypes TargetLinkage =
getFunctionLinkage(TargetDecl);
+ // Disallow aliases to available_externally because available_externally
+ // will not be there in the end to allow the creation of the alias (PR30341).
+ // FIXME: An extern template instantiation will create functions with
+ // linkage "AvailableExternally". In libc++, some classes also define
+ // members with attribute "AlwaysInline" and expect no reference to
+ // be generated. It is desirable to reenable this optimisation after
+ // corresponding LLVM changes.
+ if (TargetLinkage == llvm::GlobalValue::AvailableExternallyLinkage)
+ return true;
+
// Check if we have it already.
StringRef MangledName = getMangledName(AliasDecl);
llvm::GlobalValue *Entry = GetGlobalValue(MangledName);
@@ -157,13 +167,7 @@
// Instead of creating as alias to a linkonce_odr, replace all of the uses
// of the aliasee.
if (llvm::GlobalValue::isDiscardableIfUnused(Linkage) &&
- (TargetLinkage != llvm::GlobalValue::AvailableExternallyLinkage ||
- !TargetDecl.getDecl()->hasAttr<AlwaysInlineAttr>())) {
- // FIXME: An extern template instantiation will create functions with
- // linkage "AvailableExternally". In libc++, some classes also define
- // members with attribute "AlwaysInline" and expect no reference to
- // be generated. It is desirable to reenable this optimisation after
- // corresponding LLVM changes.
+ !TargetDecl.getDecl()->hasAttr<AlwaysInlineAttr>()) {
addReplacement(MangledName, Aliasee);
return false;
}
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