Add MS ABI mangling for operator<=>.

Thanks to Cameron DaCamara at Microsoft for letting us know what their
chosen mangling is here!

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@345330 91177308-0d34-0410-b5e6-96231b3b80d8

lib/AST/MicrosoftMangle.cpp

@@ -1240,15 +1240,8 @@ void MicrosoftCXXNameMangler::mangleOperatorName(OverloadedOperatorKind OO,
   case OO_Array_Delete: Out << "?_V"; break;
   // <operator-name> ::= ?__L # co_await
   case OO_Coawait: Out << "?__L"; break;
-
-  case OO_Spaceship: {
-    // FIXME: Once MS picks a mangling, use it.
-    DiagnosticsEngine &Diags = Context.getDiags();
-    unsigned DiagID = Diags.getCustomDiagID(DiagnosticsEngine::Error,
-      "cannot mangle this three-way comparison operator yet");
-    Diags.Report(Loc, DiagID);
-    break;
-  }
+  // <operator-name> ::= ?__M # <=>
+  case OO_Spaceship: Out << "?__M"; break;
 
   case OO_Conditional: {
     DiagnosticsEngine &Diags = Context.getDiags();

test/CodeGenCXX/cxx2a-three-way-comparison.cpp

@@ -1,24 +1,28 @@
-// RUN: %clang_cc1 -std=c++2a -emit-llvm %s -o - -triple %itanium_abi_triple | FileCheck %s --check-prefix=ITANIUM
-// RUN: not %clang_cc1 -std=c++2a -emit-llvm %s -o - -triple %ms_abi_triple 2>&1 | FileCheck %s --check-prefix=MSABI
+// RUN: %clang_cc1 -std=c++2a -emit-llvm %s -o - -triple %itanium_abi_triple | FileCheck %s --check-prefixes=CHECK,ITANIUM
+// RUN: %clang_cc1 -std=c++2a -emit-llvm %s -o - -triple %ms_abi_triple | FileCheck %s --check-prefixes=CHECK,MSABI
 // RUN: not %clang_cc1 -std=c++2a -emit-llvm %s -o - -triple %itanium_abi_triple -DBUILTIN 2>&1 | FileCheck %s --check-prefix=BUILTIN
-// MSABI: cannot mangle this three-way comparison operator yet
+// RUN: not %clang_cc1 -std=c++2a -emit-llvm %s -o - -triple %ms_abi_triple -DBUILTIN 2>&1 | FileCheck %s --check-prefix=BUILTIN
 
 struct A {
   void operator<=>(int);
 };
 
 // ITANIUM: define {{.*}}@_ZN1AssEi(
+// MSABI: define {{.*}}@"??__MA@@QEAAXH@Z"(
 void A::operator<=>(int) {}
 
 // ITANIUM: define {{.*}}@_Zssi1A(
+// MSABI: define {{.*}}@"??__M@YAXHUA@@@Z"(
 void operator<=>(int, A) {}
 
 int operator<=>(A, A);
 
 // ITANIUM: define {{.*}}_Z1f1A(
+// MSABI: define {{.*}}"?f@@YAHUA@@@Z"(
 int f(A a) {
   // ITANIUM: %[[RET:.*]] = call {{.*}}_Zss1AS_(
-  // ITANIUM: ret i32 %[[RET]]
+  // MSABI: %[[RET:.*]] = call {{.*}}"??__M@YAHUA@@0@Z"(
+  // CHECK: ret i32 %[[RET]]
   return a <=> a;
 }
 

test/CodeGenCXX/mangle-ms-cxx2a.cpp

@@ -0,0 +1,6 @@
+// RUN: %clang_cc1 -std=c++2a -fms-extensions -emit-llvm %s -o - -triple=i386-pc-win32 -fms-compatibility-version=19.00 | FileCheck %s
+
+struct A {};
+
+// CHECK-DAG: define {{.*}} @"??__M@YAXUA@@0@Z"
+void operator<=>(A, A) {}