[CodeGen] Fix access sizes in new-format TBAA tags

[kosarev]

Summary

The new format requires to specify both the type of the access and its size. This patch fixes setting access sizes for TBAA tags that denote accesses to structure members. This fix affects all future TBAA metadata tests for the new format, so I guess we don't need any special tests for this fix.

[rjmccall]

LGTM.

[hfinkel]

In D41452#961710, @rjmccall wrote:

LGTM.

Me too.

cfe/trunk/lib/CodeGen/CGExpr.cpp

if (base.getTBAAInfo().isMayAlias() ||
     // Adjust offset to be relative to the base type.
     const ASTRecordLayout &Layout =
         getContext().getASTRecordLayout(field->getParent());
     unsigned CharWidth = getContext().getCharWidth();
     if (FieldTBAAInfo.BaseType)
       FieldTBAAInfo.Offset +=
           Layout.getFieldOffset(field->getFieldIndex()) / CharWidth;
 
-    // Update the final access type.
+    // Update the final access type and size.
     FieldTBAAInfo.AccessType = CGM.getTBAATypeInfo(FieldType);
+    FieldTBAAInfo.Size =
+        getContext().getTypeSizeInChars(FieldType).getQuantity();
   }
 
   Address addr = base.getAddress();
   unsigned RecordCVR = base.getVRQualifiers();
   if (rec->isUnion()) {
     // For unions, there is no pointer adjustment.
     assert(!FieldType->isReferenceType() && "union has reference member");
     if (CGM.getCodeGenOpts().StrictVTablePointers &&