[PATCH] D51500: [MS ABI] Fix mangling incompatibility with dynamic initializer stubs.
Zachary Turner via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Thu Aug 30 11:52:41 PDT 2018
zturner created this revision.
zturner added reviewers: rnk, majnemer.
Herald added a subscriber: erik.pilkington.
Given this code:
class Foo {
public:
public:
Foo() = default;
virtual ~Foo() = default;
};
class Bar : public Foo {
static Bar Shared;
Bar() = default;
public:
static Bar *get() { return &Shared; }
int X = 0;
};
Bar Bar::Shared;
int main(int argc, char **argv) {
return Bar::get()->X;
}
Compile and dump the dynamic initializer symbols with both clang-cl and cl. You get the following:
$ clang-cl /Z7 /EHsc /c foo.cpp && dumpbin /symbols foo.obj | grep __E
052 00000000 SECT1 notype () Static | ??__EShared at Bar@@0V1 at A@YAXXZ (??__EShared at Bar@@0V1 at A@YAXXZ)
$ cl /Z7 /EHsc /c foo.cpp && dumpbin /symbols foo.obj | grep __E
03B 00000000 SECT11 notype () Static | ??__E?Shared at Bar@@0V1 at A@@YAXXZ (void __cdecl `dynamic initializer for 'private: static class Bar Bar::Shared''(void))
As we can see, clang-cl produces a different mangling which cannot be demangled by `undname`. AFAICT, this was not done for compatibility with an old version, and is in fact just broken (I tested back to MSVC 2013).
It makes sense that they would put the `?` there, because it's a disambiguator between static data member and global. Previously my demangling code was a little hacky right here because I thought there was no disambiguator.
After this patch, we can run the same clang-cl command again and undname can demangle our symbol name.
$ clang-cl /Z7 /EHsc /c foo.cpp && dumpbin /symbols foo.obj | grep __E
052 00000000 SECT1 notype () Static | ??__E?Shared at Bar@@0V1 at A@@YAXXZ (void __cdecl `dynamic initializer for 'private: static class Bar Bar::Shared''(void))
https://reviews.llvm.org/D51500
Files:
clang/lib/AST/MicrosoftMangle.cpp
clang/test/CodeGenCXX/microsoft-abi-static-initializers.cpp
clang/test/CodeGenCXX/pragma-init_seg.cpp
Index: clang/test/CodeGenCXX/pragma-init_seg.cpp
===================================================================
--- clang/test/CodeGenCXX/pragma-init_seg.cpp
+++ clang/test/CodeGenCXX/pragma-init_seg.cpp
@@ -44,15 +44,15 @@
template <typename T> const int A<T>::x = f();
template struct A<int>;
// CHECK: @"?x@?$A at H@explicit_template_instantiation@@2HB" = weak_odr dso_local global i32 0, comdat, align 4
-// CHECK: @__cxx_init_fn_ptr.4 = private constant void ()* @"??__Ex@?$A at H@explicit_template_instantiation@@2HB at YAXXZ", section ".asdf", comdat($"?x@?$A at H@explicit_template_instantiation@@2HB")
+// CHECK: @__cxx_init_fn_ptr.4 = private constant void ()* @"??__E?x@?$A at H@explicit_template_instantiation@@2HB@@YAXXZ", section ".asdf", comdat($"?x@?$A at H@explicit_template_instantiation@@2HB")
}
namespace implicit_template_instantiation {
template <typename T> struct A { static const int x; };
template <typename T> const int A<T>::x = f();
int g() { return A<int>::x; }
// CHECK: @"?x@?$A at H@implicit_template_instantiation@@2HB" = linkonce_odr dso_local global i32 0, comdat, align 4
-// CHECK: @__cxx_init_fn_ptr.5 = private constant void ()* @"??__Ex@?$A at H@implicit_template_instantiation@@2HB at YAXXZ", section ".asdf", comdat($"?x@?$A at H@implicit_template_instantiation@@2HB")
+// CHECK: @__cxx_init_fn_ptr.5 = private constant void ()* @"??__E?x@?$A at H@implicit_template_instantiation@@2HB@@YAXXZ", section ".asdf", comdat($"?x@?$A at H@implicit_template_instantiation@@2HB")
}
// ... and here's where we emitted user level ctors.
Index: clang/test/CodeGenCXX/microsoft-abi-static-initializers.cpp
===================================================================
--- clang/test/CodeGenCXX/microsoft-abi-static-initializers.cpp
+++ clang/test/CodeGenCXX/microsoft-abi-static-initializers.cpp
@@ -3,8 +3,8 @@
// CHECK: @llvm.global_ctors = appending global [5 x { i32, void ()*, i8* }] [
// CHECK: { i32, void ()*, i8* } { i32 65535, void ()* @"??__Eselectany1@@YAXXZ", i8* getelementptr inbounds (%struct.S, %struct.S* @"?selectany1@@3US@@A", i32 0, i32 0) },
// CHECK: { i32, void ()*, i8* } { i32 65535, void ()* @"??__Eselectany2@@YAXXZ", i8* getelementptr inbounds (%struct.S, %struct.S* @"?selectany2@@3US@@A", i32 0, i32 0) },
-// CHECK: { i32, void ()*, i8* } { i32 65535, void ()* @"??__Es@?$ExportedTemplate at H@@2US@@A at YAXXZ", i8* getelementptr inbounds (%struct.S, %struct.S* @"?s@?$ExportedTemplate at H@@2US@@A", i32 0, i32 0) },
-// CHECK: { i32, void ()*, i8* } { i32 65535, void ()* @"??__Efoo@?$B at H@@2VA@@A at YAXXZ", i8* bitcast (%class.A* @"?foo@?$B at H@@2VA@@A" to i8*) },
+// CHECK: { i32, void ()*, i8* } { i32 65535, void ()* @"??__E?s@?$ExportedTemplate at H@@2US@@A@@YAXXZ", i8* getelementptr inbounds (%struct.S, %struct.S* @"?s@?$ExportedTemplate at H@@2US@@A", i32 0, i32 0) },
+// CHECK: { i32, void ()*, i8* } { i32 65535, void ()* @"??__E?foo@?$B at H@@2VA@@A@@YAXXZ", i8* bitcast (%class.A* @"?foo@?$B at H@@2VA@@A" to i8*) },
// CHECK: { i32, void ()*, i8* } { i32 65535, void ()* @_GLOBAL__sub_I_microsoft_abi_static_initializers.cpp, i8* null }
// CHECK: ]
@@ -231,18 +231,18 @@
DynamicDLLImportInitVSMangling::switch_test3();
}
-// CHECK: define linkonce_odr dso_local void @"??__Efoo@?$B at H@@2VA@@A at YAXXZ"() {{.*}} comdat
+// CHECK: define linkonce_odr dso_local void @"??__E?foo@?$B at H@@2VA@@A@@YAXXZ"() {{.*}} comdat
// CHECK-NOT: and
// CHECK-NOT: ?_Bfoo@
// CHECK: call x86_thiscallcc %class.A* @"??0A@@QAE at XZ"
-// CHECK: call i32 @atexit(void ()* @"??__Ffoo@?$B at H@@2VA@@A at YAXXZ")
+// CHECK: call i32 @atexit(void ()* @"??__F?foo@?$B at H@@2VA@@A@@YAXXZ")
// CHECK: ret void
// CHECK: define linkonce_odr dso_local x86_thiscallcc %class.A* @"??0A@@QAE at XZ"({{.*}}) {{.*}} comdat
// CHECK: define linkonce_odr dso_local x86_thiscallcc void @"??1A@@QAE at XZ"({{.*}}) {{.*}} comdat
-// CHECK: define internal void @"??__Ffoo@?$B at H@@2VA@@A at YAXXZ"
+// CHECK: define internal void @"??__F?foo@?$B at H@@2VA@@A@@YAXXZ"
// CHECK: call x86_thiscallcc void @"??1A@@QAE at XZ"{{.*}}foo
// CHECK: ret void
Index: clang/lib/AST/MicrosoftMangle.cpp
===================================================================
--- clang/lib/AST/MicrosoftMangle.cpp
+++ clang/lib/AST/MicrosoftMangle.cpp
@@ -3217,10 +3217,13 @@
msvc_hashing_ostream MHO(Out);
MicrosoftCXXNameMangler Mangler(*this, MHO);
Mangler.getStream() << "??__" << CharCode;
- Mangler.mangleName(D);
if (D->isStaticDataMember()) {
+ Mangler.getStream() << '?';
+ Mangler.mangleName(D);
Mangler.mangleVariableEncoding(D);
- Mangler.getStream() << '@';
+ Mangler.getStream() << "@@";
+ } else {
+ Mangler.mangleName(D);
}
// This is the function class mangling. These stubs are global, non-variadic,
// cdecl functions that return void and take no args.
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