[MS ABI] Delegating constructors should not assume they are most derived

A constructor needs to know whether or not it is most derived in order
to determine if it is responsible for virtual bases.  Delegating
constructors assumed they were most derived.

llvm-svn: 269465

1 files changed, 11 insertions, 9 deletions

diff --git a/clang/lib/CodeGen/MicrosoftCXXABI.cpp b/clang/lib/CodeGen/MicrosoftCXXABI.cpp
index 0e15f5054d8..2e41f934a2b 100644
--- a/clang/lib/CodeGen/MicrosoftCXXABI.cpp
+++ b/clang/lib/CodeGen/MicrosoftCXXABI.cpp
@@ -1467,16 +1467,18 @@ unsigned MicrosoftCXXABI::addImplicitConstructorArgs(
 
   // Add the 'most_derived' argument second if we are variadic or last if not.
   const FunctionProtoType *FPT = D->getType()->castAs<FunctionProtoType>();
-  llvm::Value *MostDerivedArg =
-      llvm::ConstantInt::get(CGM.Int32Ty, Type == Ctor_Complete);
-  RValue RV = RValue::get(MostDerivedArg);
-  if (MostDerivedArg) {
-    if (FPT->isVariadic())
-      Args.insert(Args.begin() + 1,
-                  CallArg(RV, getContext().IntTy, /*needscopy=*/false));
-    else
-      Args.add(RV, getContext().IntTy);
+  llvm::Value *MostDerivedArg;
+  if (Delegating) {
+    MostDerivedArg = getStructorImplicitParamValue(CGF);
+  } else {
+    MostDerivedArg = llvm::ConstantInt::get(CGM.Int32Ty, Type == Ctor_Complete);
   }
+  RValue RV = RValue::get(MostDerivedArg);
+  if (FPT->isVariadic())
+    Args.insert(Args.begin() + 1,
+                CallArg(RV, getContext().IntTy, /*needscopy=*/false));
+  else
+    Args.add(RV, getContext().IntTy);
 
   return 1;  // Added one arg.
 }