Re: [PATCH] PR57878, Incorrect code: live register clobbered in split2

[Wei Mi <wmi at google dot com>]

Thank you! backported as r201068 in gcc-4_8-branch.

Thanks,
Wei.


On Thu, Jul 18, 2013 at 10:05 AM, Vladimir Makarov <vmakarov@redhat.com> wrote:
> On 07/15/2013 02:26 PM, Wei Mi wrote:
>> Hi,
>>
>> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57878
>>
>> The bug occurs because tfreq is given higher priority than bigger mode
>> in reload_pseudo_compare_func. When there are multiple reload pseudos
>> in the same insnï and the pseudo with bigger mode has lower thread
>> frequency than other reload pseudos, it is possible the bigger mode
>> pseudo cannot find available hardregs.
>>
>> The proposed fix is to switch the priority of bigger mode and tfreq in
>> reload_pseudo_compare_func. Besides I promoted lra_assert to
>> gcc_assert at the end of to make adding testcase easier since
>> lra_assert will not fire on 4.8.1.
>>
>> bootstrap and regression test are ok on x86_64-linux-gnu. Is it ok for
>> trunk and 4.8 branch?
>>
>> Thanks,
>> Wei.
>>
>> 2013-07-15  Wei Mi  <wmi@google.com>
>>
>>         PR rtl-optimization/57878
>>         * lra-assigns.c (reload_pseudo_compare_func): Switch the priority of
>>         bigger mode and tfreq.
>>
>> 2013-07-15  Wei Mi  <wmi@google.com>
>>
>>         PR rtl-optimization/57878
>>         * g++.dg/pr57518.C: New test.
> In overall, the PR analysis and the patch is ok.  The only problem the
> patch can affect generated code performance especially for 32-bit
> targets.  I see regressions on 4 SPECInt2000 tests.
>
> Here is the patch I've committed into the trunk.  It decreases the patch
> effect on performance.
>
> The patch was successfully bootstrapped an tested on x86/x86-64.
>
> Committed to the trunk as rev. 201036.
>
> Wei Mi, could you commit it to gcc4.8 branch.
>
> Thanks.
>
> 2013-07-18  Vladimir Makarov  <vmakarov@redhat.com>
>             Wei Mi  <wmi@google.com>
>
>         PR rtl-optimization/57878
>         * lra-assigns.c (assign_by_spills): Move non_reload_pseudos to the
>         top.
>         (reload_pseudo_compare_func): Check nregs first for reload
>         pseudos.
>
> 2013-07-18  Wei Mi  <wmi@google.com>
>
>         PR rtl-optimization/57878
>         * g++.dg/pr57518.C: New test.
>