[cfe-commits] [PATCH] Laying the foundation for alternate C++ ABI support

[Charles Davis]

On 5/25/10 11:18 AM, John McCall wrote:
> On May 24, 2010, at 10:43 PM, Charles Davis wrote:
>> This is the first patch in my GSoC series, in which I will factor out
>> C++ ABI support in IRgen so that we can support other C++ ABIs. This
>> patch is very simple. It just adds a class hierarchy similar to the one
>> for Objective-C runtimes, and a basic implementation for the current GNU
>> C++ ABI. All it supports is name mangling. CodeGenFunction has been
>> redirected to use this new interface instead of holding the
>> MangleContext itself (which is very specific to the GNU ABI right now).
> 
> For better or worse, people call this the Itanium ABI;  gcc's implementation hews
> faithfully to that standard, and we should use that name.  The term "GNU ABI" is likely
> to make people think of the old (pre-v3.2) gcc ABI.
Noted.
> 
> Also, I think we can live without the "CG" prefix on "CGCXXABI".
Done. (The header name still has the CG prefix, though.)
> 
> I'd prefer to avoid lazy initialization.  We should never be calling into the
> CXXABI for non-C++ code, so you should be able to create it during initialization
> if CPlusPlus is set and then assert on its existence in getCXXABI().
I don't know about that.

When I added the assert, clang started asserting whenever it was
generating IR for non-C++ (that's C and ObjC) code. I think clang right
now just assumes that the MangleContext is always available and will "Do
the Right Thing" based on whether or not Features.CPlusPlus is set.

I agree, C and ObjC IRgen shouldn't be calling into any C++-specific
stuff. But I'll fix that later.
> 
> Otherwise this looks fine to me.
Patch with changes committed as r104630.

Chip