[ms-cxxabi] The 'most derived' ctor parameter usually comes last

Unlike Itanium's VTTs, the 'most derived' boolean or bitfield is the
last parameter for non-variadic constructors, rather than the second.
For variadic constructors, the 'most derived' parameter comes after the
'this' parameter.  This affects constructor calls and constructor decls
in a variety of places.

Reviewers: timurrrr

Differential Revision: http://llvm-reviews.chandlerc.com/D2405

llvm-svn: 197518

1 files changed, 31 insertions, 38 deletions

diff --git a/clang/lib/CodeGen/ItaniumCXXABI.cpp b/clang/lib/CodeGen/ItaniumCXXABI.cpp
index bb8b5362025..b5dc8195117 100644
--- a/clang/lib/CodeGen/ItaniumCXXABI.cpp
+++ b/clang/lib/CodeGen/ItaniumCXXABI.cpp
@@ -136,18 +136,15 @@ public:
 
   void EmitCXXDestructors(const CXXDestructorDecl *D);
 
-  void BuildInstanceFunctionParams(CodeGenFunction &CGF,
-                                   QualType &ResTy,
-                                   FunctionArgList &Params);
+  void addImplicitStructorParams(CodeGenFunction &CGF, QualType &ResTy,
+                                 FunctionArgList &Params);
 
   void EmitInstanceFunctionProlog(CodeGenFunction &CGF);
 
-  void EmitConstructorCall(CodeGenFunction &CGF,
-                           const CXXConstructorDecl *D, CXXCtorType Type,
-                           bool ForVirtualBase, bool Delegating,
-                           llvm::Value *This,
-                           CallExpr::const_arg_iterator ArgBeg,
-                           CallExpr::const_arg_iterator ArgEnd);
+  unsigned addImplicitConstructorArgs(CodeGenFunction &CGF,
+                                      const CXXConstructorDecl *D,
+                                      CXXCtorType Type, bool ForVirtualBase,
+                                      bool Delegating, CallArgList &Args);
 
   void EmitDestructorCall(CodeGenFunction &CGF, const CXXDestructorDecl *DD,
                           CXXDtorType Type, bool ForVirtualBase,
@@ -801,18 +798,19 @@ ItaniumCXXABI::GetVirtualBaseClassOffset(CodeGenFunction &CGF,
 
 /// The generic ABI passes 'this', plus a VTT if it's initializing a
 /// base subobject.
-void ItaniumCXXABI::BuildConstructorSignature(const CXXConstructorDecl *Ctor,
-                                              CXXCtorType Type,
-                                              CanQualType &ResTy,
-                                SmallVectorImpl<CanQualType> &ArgTys) {
+void
+ItaniumCXXABI::BuildConstructorSignature(const CXXConstructorDecl *Ctor,
+                                         CXXCtorType Type, CanQualType &ResTy,
+                                         SmallVectorImpl<CanQualType> &ArgTys) {
   ASTContext &Context = getContext();
 
-  // 'this' parameter is already there, as well as 'this' return if
-  // HasThisReturn(GlobalDecl(Ctor, Type)) is true
+  // All parameters are already in place except VTT, which goes after 'this'.
+  // These are Clang types, so we don't need to worry about sret yet.
 
   // Check if we need to add a VTT parameter (which has type void **).
   if (Type == Ctor_Base && Ctor->getParent()->getNumVBases() != 0)
-    ArgTys.push_back(Context.getPointerType(Context.VoidPtrTy));
+    ArgTys.insert(ArgTys.begin() + 1,
+                  Context.getPointerType(Context.VoidPtrTy));
 }
 
 void ItaniumCXXABI::EmitCXXConstructors(const CXXConstructorDecl *D) {
@@ -863,14 +861,11 @@ void ItaniumCXXABI::EmitCXXDestructors(const CXXDestructorDecl *D) {
     CGM.EmitGlobal(GlobalDecl(D, Dtor_Deleting));
 }
 
-void ItaniumCXXABI::BuildInstanceFunctionParams(CodeGenFunction &CGF,
-                                                QualType &ResTy,
-                                                FunctionArgList &Params) {
-  /// Create the 'this' variable.
-  BuildThisParam(CGF, Params);
-
+void ItaniumCXXABI::addImplicitStructorParams(CodeGenFunction &CGF,
+                                              QualType &ResTy,
+                                              FunctionArgList &Params) {
   const CXXMethodDecl *MD = cast<CXXMethodDecl>(CGF.CurGD.getDecl());
-  assert(MD->isInstance());
+  assert(isa<CXXConstructorDecl>(MD) || isa<CXXDestructorDecl>(MD));
 
   // Check if we need a VTT parameter as well.
   if (NeedsVTTParameter(CGF.CurGD)) {
@@ -881,7 +876,7 @@ void ItaniumCXXABI::BuildInstanceFunctionParams(CodeGenFunction &CGF,
     ImplicitParamDecl *VTTDecl
       = ImplicitParamDecl::Create(Context, 0, MD->getLocation(),
                                   &Context.Idents.get("vtt"), T);
-    Params.push_back(VTTDecl);
+    Params.insert(Params.begin() + 1, VTTDecl);
     getStructorImplicitParamDecl(CGF) = VTTDecl;
   }
 }
@@ -908,21 +903,19 @@ void ItaniumCXXABI::EmitInstanceFunctionProlog(CodeGenFunction &CGF) {
     CGF.Builder.CreateStore(getThisValue(CGF), CGF.ReturnValue);
 }
 
-void ItaniumCXXABI::EmitConstructorCall(CodeGenFunction &CGF,
-                                        const CXXConstructorDecl *D,
-                                        CXXCtorType Type,
-                                        bool ForVirtualBase, bool Delegating,
-                                        llvm::Value *This,
-                                        CallExpr::const_arg_iterator ArgBeg,
-                                        CallExpr::const_arg_iterator ArgEnd) {
-  llvm::Value *VTT = CGF.GetVTTParameter(GlobalDecl(D, Type), ForVirtualBase,
-                                         Delegating);
-  QualType VTTTy = getContext().getPointerType(getContext().VoidPtrTy);
-  llvm::Value *Callee = CGM.GetAddrOfCXXConstructor(D, Type);
+unsigned ItaniumCXXABI::addImplicitConstructorArgs(
+    CodeGenFunction &CGF, const CXXConstructorDecl *D, CXXCtorType Type,
+    bool ForVirtualBase, bool Delegating, CallArgList &Args) {
+  if (!NeedsVTTParameter(GlobalDecl(D, Type)))
+    return 0;
 
-  // FIXME: Provide a source location here.
-  CGF.EmitCXXMemberCall(D, SourceLocation(), Callee, ReturnValueSlot(), This,
-                        VTT, VTTTy, ArgBeg, ArgEnd);
+  // Insert the implicit 'vtt' argument as the second argument.
+  llvm::Value *VTT =
+      CGF.GetVTTParameter(GlobalDecl(D, Type), ForVirtualBase, Delegating);
+  QualType VTTTy = getContext().getPointerType(getContext().VoidPtrTy);
+  Args.insert(Args.begin() + 1,
+              CallArg(RValue::get(VTT), VTTTy, /*needscopy=*/false));
+  return 1;  // Added one arg.
 }
 
 void ItaniumCXXABI::EmitDestructorCall(CodeGenFunction &CGF,