PR14759: Debug info support for C++ member pointers.

This works fine with GDB for member variable pointers, but GDB's support for
member function pointers seems to be quite unrelated to
DW_TAG_ptr_to_member_type. (see GDB bug 14998 for details)

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@171698 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp b/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
index 5dbf74d..854d82c 100644
--- a/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
+++ b/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
@@ -784,6 +784,9 @@
   if (Size && Tag != dwarf::DW_TAG_pointer_type)
     addUInt(&Buffer, dwarf::DW_AT_byte_size, 0, Size);
 
+  if (Tag == dwarf::DW_TAG_ptr_to_member_type)
+      addDIEEntry(&Buffer, dwarf::DW_AT_containing_type, dwarf::DW_FORM_ref4,
+                  getOrCreateTypeDIE(DTy.getClassType()));
   // Add source line info if available and TyDesc is not a forward declaration.
   if (!DTy.isForwardDecl())
     addSourceLine(&Buffer, DTy);