ira.c update_equiv_regs patch causes gcc/testsuite/gcc.target/arm/pr43920-2.c regression

[Alex Velenko]

On 29/07/15 23:14, Jeff Law wrote:
> On 07/28/2015 12:18 PM, Alex Velenko wrote:
>> On 21/04/15 06:27, Jeff Law wrote:
>>> On 04/20/2015 01:09 AM, Shiva Chen wrote:
>>>> Hi, Jeff
>>>>
>>>> Thanks for your advice.
>>>>
>>>> can_replace_by.patch is the new patch to handle both cases.
>>>>
>>>> pr43920-2.c.244r.jump2.ori is the original  jump2 rtl dump
>>>>
>>>> pr43920-2.c.244r.jump2.patch_can_replace_by is the jump2 rtl dump
>>>> after patch  can_replace_by.patch
>>>>
>>>> Could you help me to review the patch?
>>> Thanks.  This looks pretty good.
>>>
>>> I expanded the comment for the new function a bit and renamed the
>>> function in an effort to clarify its purpose.  From reviewing
>>> can_replace_by, it seems it should have been handling this case, but
>>> clearly wasn't due to implementation details.
>>>
>>> I then bootstrapped and regression tested the patch on x86_64-linux-gnu
>>> where it passed.  I also instrumented that compiler to see how often
>>> this code triggers.  During a bootstrap it triggers a couple hundred
>>> times (which is obviously a proxy for cross jumping improvements).  So
>>> it's triggering regularly on x86_64, which is good.
>>>
>>> I also verified that this fixes BZ64916 for an arm-non-eabi toolchain
>>> configured with --with-arch=armv7.
>>>
>>> Installed on the trunk.  No new testcase as it's covered by existing
>>> tests.
>>>
>>> Thanks,,
>>> jeff
>>>
>>
>> Hi,
>> I see this patch been committed in r222256 on trunk. Is it okay to port
>> this to fsf-5?
> It's not a regression, so backporting it would be generally frowned
> upon.  If you feel strongly about it, you should ask Jakub, Joseph or
> Richi (the release managers) for an exception to the general policy.
>
> jeff
>
Hi Jakub,
Can this commit be ported to fsf-5? It fixed gcc.target/arm/pr43920-2.c
at the time, so I think it is a good idea to port. Please, see
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64916
Kind regards,
Alex