Created attachment 7867 [details]
File to produce assertion,  --enable-assertion=YES is required

This assertion in CGRecordLayout *CodeGenTypes::ComputeRecordLayout(const RecordDecl *D, llvm::StructType *Ty) bothers Peren test. It makes it failed. This assertion tried to compute the size of BaseTy of a layout's non virtual size. However, the real code has modified the BaseTy before assertion. So I added a recompution of the real BaseTy in assert test segment 

...
  // If we're in C++, compute the base subobject type.
  llvm::StructType *BaseTy = 0;
  if (isa<CXXRecordDecl>(D)) {
    BaseTy = Builder.BaseSubobjectType;
    if (!BaseTy) BaseTy = Ty;   <--- is not BaseTy anymore if BaseTy is NULL
  }
...
#ifndef NDEBUG
  // Verify that the computed LLVM struct size matches the AST layout size.
  const ASTRecordLayout &Layout = getContext().getASTRecordLayout(D);
...

  if (BaseTy) {  <-- this requires the true BaseTy
    CharUnits NonVirtualSize  = Layout.getNonVirtualSize();
    CharUnits NonVirtualAlign = Layout.getNonVirtualAlign();
    CharUnits AlignedNonVirtualTypeSize = 
      NonVirtualSize.RoundUpToAlignment(NonVirtualAlign);

    uint64_t AlignedNonVirtualTypeSizeInBits = 
      getContext().toBits(AlignedNonVirtualTypeSize);

    assert(AlignedNonVirtualTypeSizeInBits == 
           getTargetData().getTypeAllocSizeInBits(BaseTy) &&
           "Type size mismatch!");
  }