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

[Jeff Law]

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