[MS ABI] Implement a mangling for _Atomic types

MSVC doesn't implement a mangling for C11's _Atomic so we must invent
our own.

For now, treating it like a class type called _Atomic in the __clang
namespace.

This means that 'void f(__Atomic(int))'
will demangle as: 'void f(struct __clang::_Atomic<int>)'

llvm-svn: 256557

2 files changed, 15 insertions, 5 deletions

diff --git a/clang/lib/AST/MicrosoftMangle.cpp b/clang/lib/AST/MicrosoftMangle.cpp
index e4b043939fc..1f3ba15a5bd 100644
--- a/clang/lib/AST/MicrosoftMangle.cpp
+++ b/clang/lib/AST/MicrosoftMangle.cpp
@@ -2391,11 +2391,16 @@ void MicrosoftCXXNameMangler::mangleType(const AutoType *T, Qualifiers,
 
 void MicrosoftCXXNameMangler::mangleType(const AtomicType *T, Qualifiers,
                                          SourceRange Range) {
-  DiagnosticsEngine &Diags = Context.getDiags();
-  unsigned DiagID = Diags.getCustomDiagID(DiagnosticsEngine::Error,
-    "cannot mangle this C11 atomic type yet");
-  Diags.Report(Range.getBegin(), DiagID)
-    << Range;
+  QualType ValueType = T->getValueType();
+
+  llvm::SmallString<64> TemplateMangling;
+  llvm::raw_svector_ostream Stream(TemplateMangling);
+  MicrosoftCXXNameMangler Extra(Context, Stream);
+  Stream << "?$";
+  Extra.mangleSourceName("_Atomic");
+  Extra.mangleType(ValueType, Range, QMM_Escape);
+
+  mangleArtificalTagType(TTK_Struct, TemplateMangling, {"__clang"});
 }
 
 void MicrosoftMangleContextImpl::mangleCXXName(const NamedDecl *D,
diff --git a/clang/test/CodeGenCXX/mangle-ms.cpp b/clang/test/CodeGenCXX/mangle-ms.cpp
index 98277dc9a30..5fe0974c87d 100644
--- a/clang/test/CodeGenCXX/mangle-ms.cpp
+++ b/clang/test/CodeGenCXX/mangle-ms.cpp
@@ -437,3 +437,8 @@ int foo(int *const i __attribute__((pass_object_size(0)))) { return 0; }
 // CHECK-DAG: define i32 @"\01?bar@PassObjectSize@@YAHQAHW4__pass_object_size1@__clang@@@Z"
 int bar(int *const i __attribute__((pass_object_size(1)))) { return 0; }
 }
+
+namespace Atomic {
+// CHECK-DAG: define void @"\01?f@Atomic@@YAXU?$_Atomic@H@__clang@@@Z"(
+void f(_Atomic(int)) {}
+}