From 0a29fed31f05fdcaa8bfe95ae11ead8e5513ee81 Mon Sep 17 00:00:00 2001
From: David Majnemer <david.majnemer@gmail.com>
Date: Tue, 29 Dec 2015 11:45:58 +0000
Subject: [PATCH] [MS ABI] Cleanup our mangling of vector types

We used to produce a type which demangled to:
union __clang_vec8_F

That 'F' is the mangling for 'short' but it is present in the mangled
name in an inappropriate place, leading to it not getting demangled.

Instead, create a synthetic class type in a synthetic namespace called
__clang. With this, it now demangles to:
union __clang::__vector<short,8>

llvm-svn: 256556
---
 clang/lib/AST/MicrosoftMangle.cpp             | 23 +++++++++++--------
 .../CodeGenCXX/mangle-ms-vector-types.cpp     |  4 ++--
 2 files changed, 15 insertions(+), 12 deletions(-)

diff --git a/clang/lib/AST/MicrosoftMangle.cpp b/clang/lib/AST/MicrosoftMangle.cpp
index 9b1bdfa7f902..e4b043939fcc 100644
--- a/clang/lib/AST/MicrosoftMangle.cpp
+++ b/clang/lib/AST/MicrosoftMangle.cpp
@@ -2227,7 +2227,7 @@ void MicrosoftCXXNameMangler::mangleType(const VectorType *T, Qualifiers Quals,
   uint64_t Width = getASTContext().getTypeSize(T);
   // Pattern match exactly the typedefs in our intrinsic headers.  Anything that
   // doesn't match the Intel types uses a custom mangling below.
-  bool IsBuiltin = true;
+  size_t OutSizeBefore = Out.tell();
   llvm::Triple::ArchType AT =
       getASTContext().getTargetInfo().getTriple().getArch();
   if (AT == llvm::Triple::x86 || AT == llvm::Triple::x86_64) {
@@ -2240,22 +2240,25 @@ void MicrosoftCXXNameMangler::mangleType(const VectorType *T, Qualifiers Quals,
         mangleArtificalTagType(TTK_Union, "__m" + llvm::utostr(Width) + 'i');
       else if (ET->getKind() == BuiltinType::Double)
         mangleArtificalTagType(TTK_Struct, "__m" + llvm::utostr(Width) + 'd');
-      else
-        IsBuiltin = false;
-    } else {
-      IsBuiltin = false;
     }
-  } else {
-    IsBuiltin = false;
   }
 
+  bool IsBuiltin = Out.tell() != OutSizeBefore;
   if (!IsBuiltin) {
     // The MS ABI doesn't have a special mangling for vector types, so we define
     // our own mangling to handle uses of __vector_size__ on user-specified
     // types, and for extensions like __v4sf.
-    Out << "T__clang_vec" << T->getNumElements() << '_';
-    mangleType(ET, Quals, Range);
-    Out << "@@";
+
+    llvm::SmallString<64> TemplateMangling;
+    llvm::raw_svector_ostream Stream(TemplateMangling);
+    MicrosoftCXXNameMangler Extra(Context, Stream);
+    Stream << "?$";
+    Extra.mangleSourceName("__vector");
+    Extra.mangleType(QualType(ET, 0), Range, QMM_Escape);
+    Extra.mangleIntegerLiteral(llvm::APSInt::getUnsigned(T->getNumElements()),
+                               /*IsBoolean=*/false);
+
+    mangleArtificalTagType(TTK_Union, TemplateMangling, {"__clang"});
   }
 }
 
diff --git a/clang/test/CodeGenCXX/mangle-ms-vector-types.cpp b/clang/test/CodeGenCXX/mangle-ms-vector-types.cpp
index 5aca4551cebc..53a1a43fe4af 100644
--- a/clang/test/CodeGenCXX/mangle-ms-vector-types.cpp
+++ b/clang/test/CodeGenCXX/mangle-ms-vector-types.cpp
@@ -27,11 +27,11 @@ void foo256i(__m256i) {}
 
 // We have a custom mangling for vector types not standardized by Intel.
 void foov8hi(__v8hi) {}
-// CHECK: define void @"\01?foov8hi@@YAXT__clang_vec8_F@@@Z"
+// CHECK: define void @"\01?foov8hi@@YAXT?$__vector@F$07@__clang@@@Z"
 
 typedef __attribute__((ext_vector_type(4))) int vi4b;
 void foovi4b(vi4b) {}
-// CHECK: define void @"\01?foovi4b@@YAXT__clang_vec4_H@@@Z"
+// CHECK: define void @"\01?foovi4b@@YAXT?$__vector@H$03@__clang@@@Z"
 
 // Clang does not support vectors of complex types, so we can't test the
 // mangling of them.