[llvm] r203488 - For functions with ARM target specific calling convention, when simplify-libcall

[Evan Cheng]

On Mar 12, 2014, at 4:40 AM, Tim Northover <t.p.northover at gmail.com> wrote:

>> Even more, the backend knows the default calling convention for a
>> target.
> 
> Agreed, if every C function emitted by Clang gets a PCS specifier then
> something is probably very wonky. It could be made to work and might
> even be natural for odd targets, but it's suspicious.

That's definitely the case now.

> 
>> So, plain C CC should "just work" and transform to AAPCS or AAPCS-VFP when necessary.
> 
> You could imagine a situation where some platform started out aapcs
> and had to maintain that for existing libcalls for ABI compatibility,
> but moved to aapcs_vfp for new additions. I don't know of any current
> example though.

Ok, if the design is these platforms will have just one set of library than I agree this change will cause problems. I had thought the linkers would be smart enough to link against the right variants.

I'll revert the patches.

Evan

> 
> That's my main reason for wanting TargetLowering to have a say.
> 
> Cheers.
> 
> Tim.