[PATCH] Enable ARM tail calls for ELF

[Eric Christopher]

On Mon, Jul 1, 2013 at 2:31 PM, Tim Northover <t.p.northover at gmail.com> wrote:
>>>> // This option should go away when tail calls fully work.
>
>> That was almost assuredly Evan, might want to ask him what problems he
>> thinks there still might be? :)
>
> Bob, actually. It looks like there was a problem with some linker back
> in the day (my guess is the MCJIT linker since it tends to be more
> ad-hoc than static linkers, but I haven't checked).
>

Interesting :)

> These days, I think the LLVM-only parts have probably been adequately
> tested by iOS, which leaves random home-grown linkers that may not
> cope. I think that's their problem but wanted to make sure no-one had
> one that they thought was important enough to block LLVM with.
>

Unlikely. It'd be nice if anything that currently works with lld
continue to work I guess? Otherwise, ld64, gnu ld, and gold should all
continue to work. I imagine the arm bots will notice this change,
we'll want to pay attention there.

> I suppose there could be a disagreement about the functions where it's
> acceptable to change the ABI for a tail call between ELF and MachO,
> but that seems unlikely to me.
>

*shrug* This seems like a "worry about it if it comes up"

-eric