[MS ABI] Account for the virtual inheritance quirk when mangling

Virtual inheritance member pointers are always relative to the vbindex,
even when the member pointer doesn't point into a virtual base.  This is
corrected by adjusting the non-virtual offset backwards from the vbptr
back to the top of the most derived class.  While we performed this
adjustment when manifesting member pointers as constants or when
performing conversions, we didn't perform the adjustment when mangling
them.

llvm-svn: 240453

1 files changed, 8 insertions, 1 deletions

diff --git a/clang/lib/AST/MicrosoftMangle.cpp b/clang/lib/AST/MicrosoftMangle.cpp
index 26894bb91eb..c50db60abe5 100644
--- a/clang/lib/AST/MicrosoftMangle.cpp
+++ b/clang/lib/AST/MicrosoftMangle.cpp
@@ -502,6 +502,9 @@ void MicrosoftCXXNameMangler::mangleMemberDataPointer(const CXXRecordDecl *RD,
     FieldOffset /= getASTContext().getCharWidth();
 
     VBTableOffset = 0;
+
+    if (IM == MSInheritanceAttr::Keyword_virtual_inheritance)
+      FieldOffset -= getASTContext().getOffsetOfBaseWithVBPtr(RD).getQuantity();
   } else {
     FieldOffset = RD->nullFieldOffsetIsZero() ? 0 : -1;
 
@@ -570,6 +573,10 @@ MicrosoftCXXNameMangler::mangleMemberFunctionPointer(const CXXRecordDecl *RD,
       mangleName(MD);
       mangleFunctionEncoding(MD, /*ShouldMangle=*/true);
     }
+
+    if (VBTableOffset == 0 &&
+        IM == MSInheritanceAttr::Keyword_virtual_inheritance)
+      NVOffset -= getASTContext().getOffsetOfBaseWithVBPtr(RD).getQuantity();
   } else {
     // Null single inheritance member functions are encoded as a simple nullptr.
     if (IM == MSInheritanceAttr::Keyword_single_inheritance) {
@@ -582,7 +589,7 @@ MicrosoftCXXNameMangler::mangleMemberFunctionPointer(const CXXRecordDecl *RD,
   }
 
   if (MSInheritanceAttr::hasNVOffsetField(/*IsMemberFunction=*/true, IM))
-    mangleNumber(NVOffset);
+    mangleNumber(static_cast<uint32_t>(NVOffset));
   if (MSInheritanceAttr::hasVBPtrOffsetField(IM))
     mangleNumber(VBPtrOffset);
   if (MSInheritanceAttr::hasVBTableOffsetField(IM))