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Re: ira.c update_equiv_regs patch causes gcc/testsuite/gcc.target/arm/pr43920-2.c regression
- From: Marcus Shawcroft <marcus dot shawcroft at gmail dot com>
- To: Alex Velenko <Alex dot Velenko at arm dot com>
- Cc: Jeff Law <law at redhat dot com>, Shiva Chen <shiva0217 at gmail dot com>, "gcc at gcc dot gnu dot org" <gcc at gcc dot gnu dot org>, "gcc-patches at gcc dot gnu dot org" <gcc-patches at gcc dot gnu dot org>, jakub at redhat dot com
- Date: Tue, 18 Aug 2015 10:45:29 +0100
- Subject: Re: ira.c update_equiv_regs patch causes gcc/testsuite/gcc.target/arm/pr43920-2.c regression
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- References: <CAH=PD7Z2s3Yw+nWkhKBzEVrvg=aeBLhL-rZJQ=VtpgOjZZ+DLA at mail dot gmail dot com> <55312EDF dot 90005 at redhat dot com> <CAH=PD7a0ofWfFBnJqD=6e5uYJY8v_GRjcvRuOBvy-x3EZNzFJg at mail dot gmail dot com> <5535DFB5 dot 3020003 at redhat dot com> <55B7C784 dot 4010104 at arm dot com> <55B95039 dot 3070803 at redhat dot com> <55BB5640 dot 2060508 at arm dot com> <55D2FA1D dot 1060508 at arm dot com>
On 18 August 2015 at 10:25, Alex Velenko <Alex.Velenko@arm.com> wrote:
>
>
> On 31/07/15 12:04, Alex Velenko wrote:
>>
>> 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
>
>
> Ping!
>
> Currently this test is passed on fsf-trunk, but not passed on fsf-5, so I
> think it is a regression on fsf-5:
That does not make it a regression, it is only a regression if a
version prior to 5 passes, how does this test behave on 4.9?
Cheers
/Marcus