[cfe-dev] [llvm-dev] RFC: Implementing the Swift calling convention in LLVM and Clang

Renato Golin via cfe-dev cfe-dev at lists.llvm.org
Wed Mar 2 11:04:52 PST 2016

On 2 March 2016 at 19:01, John McCall <rjmccall at apple.com> wrote:
> Also, just a quick question.  I’m happy to continue to talk about the actual
> design and implementation of LLVM IR on this point, and I’d be happy to
> put out the actual patch we’re initially proposing.  Obviously, all of this code
> needs to go through the normal LLVM/Clang code review processes.  But
> before we continue with that, I just want to clarify one important point: assuming
> that the actual implementation ends up satisfying your technical requirements,
> do you have any objections to the general idea of supporting the Swift CC
> in mainline LLVM?

I personally don't. I think we should treat Swift as any other
language that we support, and if we can't use existing mechanisms in
the back-end to lower Swift, then we need to expand the back-end to
support that.

That being said, if the Swift support starts to bit-rot (if, for
instance, Apple stops supporting it in the future), it will be harder
to clean up the back-end from its CC. But that, IMHO, is a very
far-fetched future and a small price to pay.


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