PR24595: Ignore calling convention modifiers for structors in MS ABI.

MS compiler ignores calling convention modifiers for structors. This patch makes
clang do the same (for MS ABI). This fixes PR24595 and makes vswriter.h header
(from Windows SDK 8.1) compilable.

Differential Revision: http://reviews.llvm.org/D12402

llvm-svn: 247619

clang/include/clang/Basic/DiagnosticSemaKinds.td

@@ -2375,6 +2375,9 @@ def err_cconv_varargs : Error<
 def warn_cconv_varargs : Warning<
   "%0 calling convention ignored on variadic function">,
   InGroup<IgnoredAttributes>;
+def warn_cconv_structors : Warning<
+  "%0 calling convention ignored on constructor/destructor">,
+  InGroup<IgnoredAttributes>;
 def err_regparm_mismatch : Error<"function declared with regparm(%0) "
   "attribute was previously declared "
   "%plural{0:without the regparm|:with the regparm(%1)}1 attribute">;

clang/include/clang/Sema/DeclSpec.h

@@ -2208,6 +2208,9 @@ public:
   /// redeclaration time if the decl is static.
   bool isStaticMember();
 
+  /// Returns true if this declares a constructor or a destructor.
+  bool isCtorOrDtor();
+
   void setRedeclaration(bool Val) { Redeclaration = Val; }
   bool isRedeclaration() const { return Redeclaration; }
 };

clang/include/clang/Sema/Sema.h

@@ -2919,7 +2919,8 @@ public:
   /// Adjust the calling convention of a method to be the ABI default if it
   /// wasn't specified explicitly.  This handles method types formed from
   /// function type typedefs and typename template arguments.
-  void adjustMemberFunctionCC(QualType &T, bool IsStatic);
+  void adjustMemberFunctionCC(QualType &T, bool IsStatic, bool IsCtorOrDtor,
+                              SourceLocation Loc);
 
   // Check if there is an explicit attribute, but only look through parens.
   // The intent is to look for an attribute on the current declarator, but not

clang/lib/Sema/DeclSpec.cpp

@@ -351,6 +351,11 @@ bool Declarator::isStaticMember() {
               getName().OperatorFunctionId.Operator));
 }
 
+bool Declarator::isCtorOrDtor() {
+  return (getName().getKind() == UnqualifiedId::IK_ConstructorName) ||
+         (getName().getKind() == UnqualifiedId::IK_DestructorName);
+}
+
 bool DeclSpec::hasTagDefinition() const {
   if (!TypeSpecOwned)
     return false;

clang/lib/Sema/SemaDecl.cpp

@@ -7244,7 +7244,8 @@ Sema::ActOnFunctionDeclarator(Scope *S, Declarator &D, DeclContext *DC,
       << DeclSpec::getSpecifierName(TSCS);
 
   if (D.isFirstDeclarationOfMember())
-    adjustMemberFunctionCC(R, D.isStaticMember());
+    adjustMemberFunctionCC(R, D.isStaticMember(), D.isCtorOrDtor(),
+                           D.getIdentifierLoc());
 
   bool isFriend = false;
   FunctionTemplateDecl *FunctionTemplate = nullptr;

clang/lib/Sema/SemaType.cpp

@@ -2269,8 +2269,11 @@ QualType Sema::BuildMemberPointerType(QualType T, QualType Class,
 
   // Adjust the default free function calling convention to the default method
   // calling convention.
+  bool IsCtorOrDtor =
+      (Entity.getNameKind() == DeclarationName::CXXConstructorName) ||
+      (Entity.getNameKind() == DeclarationName::CXXDestructorName);
   if (T->isFunctionType())
-    adjustMemberFunctionCC(T, /*IsStatic=*/false);
+    adjustMemberFunctionCC(T, /*IsStatic=*/false, IsCtorOrDtor, Loc);
 
   return Context.getMemberPointerType(T, Class.getTypePtr());
 }
@@ -5842,24 +5845,40 @@ bool Sema::hasExplicitCallingConv(QualType &T) {
   return false;
 }
 
-void Sema::adjustMemberFunctionCC(QualType &T, bool IsStatic) {
+void Sema::adjustMemberFunctionCC(QualType &T, bool IsStatic, bool IsCtorOrDtor,
+                                  SourceLocation Loc) {
   FunctionTypeUnwrapper Unwrapped(*this, T);
   const FunctionType *FT = Unwrapped.get();
   bool IsVariadic = (isa<FunctionProtoType>(FT) &&
                      cast<FunctionProtoType>(FT)->isVariadic());
-
-  // Only adjust types with the default convention.  For example, on Windows we
-  // should adjust a __cdecl type to __thiscall for instance methods, and a
-  // __thiscall type to __cdecl for static methods.
   CallingConv CurCC = FT->getCallConv();
-  CallingConv FromCC =
-      Context.getDefaultCallingConvention(IsVariadic, IsStatic);
   CallingConv ToCC = Context.getDefaultCallingConvention(IsVariadic, !IsStatic);
-  if (CurCC != FromCC || FromCC == ToCC)
+
+  if (CurCC == ToCC)
     return;
 
-  if (hasExplicitCallingConv(T))
-    return;
+  // MS compiler ignores explicit calling convention attributes on structors. We
+  // should do the same.
+  if (Context.getTargetInfo().getCXXABI().isMicrosoft() && IsCtorOrDtor) {
+    // Issue a warning on ignored calling convention -- except of __stdcall.
+    // Again, this is what MS compiler does.
+    if (CurCC != CC_X86StdCall)
+      Diag(Loc, diag::warn_cconv_structors)
+          << FunctionType::getNameForCallConv(CurCC);
+  // Default adjustment.
+  } else {
+    // Only adjust types with the default convention.  For example, on Windows
+    // we should adjust a __cdecl type to __thiscall for instance methods, and a
+    // __thiscall type to __cdecl for static methods.
+    CallingConv DefaultCC =
+        Context.getDefaultCallingConvention(IsVariadic, IsStatic);
+
+    if (CurCC != DefaultCC || DefaultCC == ToCC)
+      return;
+
+    if (hasExplicitCallingConv(T))
+      return;
+  }
 
   FT = Context.adjustFunctionType(FT, FT->getExtInfo().withCallingConv(ToCC));
   QualType Wrapped = Unwrapped.wrap(*this, FT);

clang/test/CodeGenCXX/microsoft-abi-structors.cpp

@@ -5,6 +5,7 @@
 // RUN: FileCheck --check-prefix DTORS %s < %t
 // RUN: FileCheck --check-prefix DTORS2 %s < %t
 // RUN: FileCheck --check-prefix DTORS3 %s < %t
+// RUN: FileCheck --check-prefix DTORS4 %s < %t
 //
 // RUN: %clang_cc1 -emit-llvm %s -o - -mconstructor-aliases -triple=x86_64-pc-win32 -fno-rtti | FileCheck --check-prefix DTORS-X64 %s
 
@@ -407,9 +408,7 @@ B::B(short *a) {}
 // CHECK:               (%"struct.test1::B"* returned %this, i32* %a, i32 %is_most_derived)
 // CHECK: define %"struct.test1::B"* @"\01??0B@test1@@QAA@PBDZZ"
 // CHECK:               (%"struct.test1::B"* returned %this, i32 %is_most_derived, i8* %a, ...)
-
-// FIXME: This should be x86_thiscallcc.  MSVC ignores explicit CCs on structors.
-// CHECK: define %"struct.test1::B"* @"\01??0B@test1@@QAA@PAF@Z"
+// CHECK: define x86_thiscallcc %"struct.test1::B"* @"\01??0B@test1@@QAE@PAF@Z"
 // CHECK:               (%"struct.test1::B"* returned %this, i16* %a, i32 %is_most_derived)
 
 void construct_b() {
@@ -458,3 +457,18 @@ void *getA() {
 // CHECK:               (%"struct.(anonymous namespace)::A"* %this, i32 %should_call_delete)
 // CHECK: define internal x86_thiscallcc void @"\01??1A@?A@@UAE@XZ"
 // CHECK:               (%"struct.(anonymous namespace)::A"* %this)
+
+// Check that we correctly transform __stdcall to __thiscall for ctors and
+// dtors.
+class G {
+ public:
+  __stdcall G() {};
+// DTORS4: define linkonce_odr x86_thiscallcc %class.G* @"\01??0G@@QAE@XZ"
+  __stdcall ~G() {};
+// DTORS4: define linkonce_odr x86_thiscallcc void @"\01??1G@@QAE@XZ"
+};
+
+extern void testG() {
+  G g;
+}
+

clang/test/SemaCXX/decl-microsoft-call-conv.cpp

@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -std=c++14 -triple i686-pc-win32 -fms-extensions -verify %s
+// RUN: %clang_cc1 -std=c++14 -triple i686-pc-win32 -fms-extensions -DMSABI -verify %s
 // RUN: %clang_cc1 -std=c++14 -triple i686-pc-mingw32 -verify %s
 // RUN: %clang_cc1 -std=c++14 -triple i686-pc-mingw32 -fms-extensions -verify %s
 
@@ -74,6 +74,11 @@ struct S {
 
   static void            static_member_variadic_default(int x, ...);
   static void __cdecl    static_member_variadic_cdecl(int x, ...);
+
+  // Structors can't be other than default in MS ABI environment
+#ifdef MSABI
+  __vectorcall S(); // expected-warning {{vectorcall calling convention ignored on constructor/destructor}}
+#endif
 };
 
 void __cdecl    S::member_default1() {} // expected-error {{function declared 'cdecl' here was previously declared without calling convention}}