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[clang][MSVC] Correct mangling of thread-safe static initialization variables. #85300

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Merged
merged 1 commit into from
Mar 15, 2024
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[clang][MSVC] Correct mangling of thread-safe static initialization variables. #85300

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6 changes: 6 additions & 0 deletions clang/docs/ReleaseNotes.rst
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Expand Up @@ -47,6 +47,12 @@ C++ Specific Potentially Breaking Changes

ABI Changes in This Version
---------------------------
- Fixed Microsoft name mangling of implicitly defined variables used for thread
safe static initialization of static local variables. This change resolves
incompatibilities with code compiled by MSVC but might introduce
incompatibilities with code compiled by earlier versions of Clang when an
inline member function that contains a static local variable with a dynamic
initializer is declared with ``__declspec(dllimport)``. (#GH83616).

AST Dumping Potentially Breaking Changes
----------------------------------------
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5 changes: 3 additions & 2 deletions clang/lib/AST/MicrosoftMangle.cpp
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Expand Up @@ -390,6 +390,7 @@ class MicrosoftCXXNameMangler {
const FunctionDecl *D = nullptr,
bool ForceThisQuals = false,
bool MangleExceptionSpec = true);
void mangleSourceName(StringRef Name);
void mangleNestedName(GlobalDecl GD);

private:
Expand All @@ -408,7 +409,6 @@ class MicrosoftCXXNameMangler {
mangleUnqualifiedName(GD, cast<NamedDecl>(GD.getDecl())->getDeclName());
}
void mangleUnqualifiedName(GlobalDecl GD, DeclarationName Name);
void mangleSourceName(StringRef Name);
void mangleOperatorName(OverloadedOperatorKind OO, SourceLocation Loc);
void mangleCXXDtorType(CXXDtorType T);
void mangleQualifiers(Qualifiers Quals, bool IsMember);
Expand Down Expand Up @@ -3920,7 +3920,8 @@ void MicrosoftMangleContextImpl::mangleThreadSafeStaticGuardVariable(
msvc_hashing_ostream MHO(Out);
MicrosoftCXXNameMangler Mangler(*this, MHO);

Mangler.getStream() << "?$TSS" << GuardNum << '@';
Mangler.getStream() << "?";
Mangler.mangleSourceName("$TSS" + llvm::utostr(GuardNum));
Mangler.mangleNestedName(VD);
Mangler.getStream() << "@4HA";
}
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17 changes: 17 additions & 0 deletions clang/test/CodeGenCXX/mangle-ms-back-references.cpp
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Expand Up @@ -83,3 +83,20 @@ class H;

void ManyParams(T01 &, T02 &, T03 &, T04 &, T05 &, T06 &, T07 &, T08 &, T09 &, T10 &, H<T11> &, H<T11> &) {}
// CHECK: "?ManyParams@@YAXAAVT01@@AAVT02@@AAVT03@@AAVT04@@AAVT05@@AAVT06@@AAVT07@@AAVT08@@AAVT09@@AAVT10@@AAV?$H@VT11@@@@AAV?$H@VT11@@@@@Z"

namespace NS {
// The name "TSS0" for the name of the class below has been specifically
// chosen to ensure that back reference lookup does not match against the
// implicitly generated "$TSS0" name of the thread safe static initialization
// variable.
struct __declspec(dllexport) TSS0 {
static TSS0& get();
__forceinline static TSS0& singleton() {
static TSS0& lsv = get();
return lsv;
}
};
}
// CHECK: "?singleton@TSS0@NS@@SAAAU12@XZ"
// CHECK: "?lsv@?1??singleton@TSS0@NS@@SAAAU23@XZ@4AAU23@A"
// CHECK: "?$TSS0@?1??singleton@TSS0@NS@@SAAAU23@XZ@4HA"