MS ABI: Implement copy-ctor closures, finish implementing throw

This adds support for copy-constructor closures.  These are generated
when the C++ runtime has to call a copy-constructor with a particular
calling convention or with default arguments substituted in to the call.

Because the runtime has no mechanism to call the function with a
different calling convention or know-how to evaluate the default
arguments at run-time, we create a thunk which will do all the
appropriate work and package it in a way the runtime can use.

Differential Revision: http://reviews.llvm.org/D8225

llvm-svn: 231952
diff --git a/clang/lib/CodeGen/CGCall.cpp b/clang/lib/CodeGen/CGCall.cpp
index 0060c76..6784964 100644
--- a/clang/lib/CodeGen/CGCall.cpp
+++ b/clang/lib/CodeGen/CGCall.cpp
@@ -346,6 +346,22 @@
                                  FTP->getExtInfo(), RequiredArgs(1));
 }
 
+const CGFunctionInfo &
+CodeGenTypes::arrangeMSCopyCtorClosure(const CXXConstructorDecl *CD) {
+  CanQual<FunctionProtoType> FTP = GetFormalType(CD);
+  SmallVector<CanQualType, 2> ArgTys;
+  const CXXRecordDecl *RD = CD->getParent();
+  ArgTys.push_back(GetThisType(Context, RD));
+  ArgTys.push_back(*FTP->param_type_begin());
+  if (RD->getNumVBases() > 0)
+    ArgTys.push_back(Context.IntTy);
+  CallingConv CC = Context.getDefaultCallingConvention(
+      /*IsVariadic=*/false, /*IsCXXMethod=*/true);
+  return arrangeLLVMFunctionInfo(Context.VoidTy, /*instanceMethod=*/true,
+                                 /*chainCall=*/false, ArgTys,
+                                 FunctionType::ExtInfo(CC), RequiredArgs::All);
+}
+
 /// Arrange a call as unto a free function, except possibly with an
 /// additional number of formal parameters considered required.
 static const CGFunctionInfo &