[PATCH] Enable ARM tail calls for ELF

[Jim Grosbach]

On Jul 1, 2013, at 10:37 AM, Eric Christopher <echristo at gmail.com> wrote:

> On Mon, Jul 1, 2013 at 10:28 AM, Quentin Colombet <qcolombet at apple.com> wrote:
>> Hi Tim,
>> 
>> The patch LGTM with one question:
>> Do you have any performance number to see the impact of this patch?
>> 
>> Indeed, tail calls are generally faster, but I am wondering why it was not
>> enabled for non-iOS targets before your patch. Hence, having some evidences
>> that it does not have weird side effects would be nice.
>> 
> 
> My guess here is likely testing to be honest, i.e. not wanting to turn
> on an untested code path by default.
> 

Yes.

-Jim

> I would like to see any performance data though. :)
> 
> -eric
> 
>> Thanks,
>> 
>> -Quentin
>> 
>> On Jun 30, 2013, at 3:12 AM, Tim Northover <t.p.northover at gmail.com> wrote:
>> 
>> Hi,
>> 
>> The attached patch enables tail calls for every target that hasn't
>> explicitly been marked as bad (iOS < 5.0). This amounts to any ELF
>> target and being more liberal on some ghost MachO targets (e.g.
>> arm-apple-darwin9) that no-one probably cares about.
>> 
>> I think the ELF side is justified because the required linker support
>> is there in the ARM ELF specification so anywhere it doesn't work has
>> a broken linker. I've also tested it on Linux and our MCJIT dynamic
>> loader with no issues.
>> 
>> Does anyone object to the change?
>> 
>> Cheers.
>> 
>> Tim.
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