Re: Various selective scheduling fixes

[Kyrill Tkachov <kyrylo.tkachov@foss.arm.com>]

Hi Christophe, Andrey,

On 01/04/16 14:09, Christophe Lyon wrote:
> On 1 April 2016 at 10:54, Andrey Belevantsev <abel@ispras.ru> wrote:
>> Hi Christophe,
>>
>>
>> On 01.04.2016 10:33, Christophe Lyon wrote:
>>> On 31 March 2016 at 16:43, Andrey Belevantsev <abel@ispras.ru> wrote:
>>>> Hello,
>>>>
>>>> On 14.03.2016 12:10, Andrey Belevantsev wrote:
>>>>>
>>>>> Hello,
>>>>>
>>>>> In this thread I will be posting the patches for the fixed selective
>>>>> scheduling PRs (except the one that was already kindly checked in by
>>>>> Jeff).
>>>>>   The patches were tested both on x86-64 and ia64 with the following
>>>>> combination: 1) the usual bootstrap/regtest, which only utilizes
>>>>> sel-sched
>>>>> on its own tests, made by default to run on arm/ppc/x86-64/ia64; 2) the
>>>>> bootstrap/regtest with the second scheduler forced to sel-sched; 3) both
>>>>> schedulers forced to sel-sched.  In all cases everything seemed to be
>>>>> fine.
>>>>>
>>>>> Three of the PRs are regressions, the other two showed different errors
>>>>> across the variety of releases tested by submitters;  I think all of
>>>>> them
>>>>> are appropriate at this stage -- they do not touch anything outside of
>>>>> selective scheduling except the first patch where a piece of code from
>>>>> sched-deps.c needs to be refactored into a function to be called from
>>>>> sel-sched.c.
>>>>
>>>>
>>>> I've backported all regression PRs to gcc-5-branch after testing there
>>>> again
>>>> with selective scheduling force enabled: PRs 64411, 66660, 69032, 69102.
>>>> The first one was not marked as a regression as such but the test for PR
>>>> 70292, which is duplicate, works for me on gcc 5.1 thus making it a
>>>> regression, too.
>>>>
>>> Hi,
>>>
>>> The backport for pr69102 shows that the new testcase fails to compile
>>> (ICE)
>>> when GCC is configured as:
>>>
>>> --target=arm-none-linux-gnueabihf --with-float=hard --with-mode=arm
>>> --with-cpu=cortex-a15 --with-fpu=neon-vfpv4
>>>
>>>
>>> /aci-gcc-fsf/sources/gcc-fsf/gccsrc/gcc/testsuite/gcc.c-torture/compile/pr69102.c:
>>> In function 'foo':
>>>
>>> /aci-gcc-fsf/sources/gcc-fsf/gccsrc/gcc/testsuite/gcc.c-torture/compile/pr69102.c:21:1:
>>> internal compiler error: Segmentation fault
>>> 0xa64d15 crash_signal
>>>          /aci-gcc-fsf/sources/gcc-fsf/gccsrc/gcc/toplev.c:383
>>> 0xfa41d7 autopref_multipass_dfa_lookahead_guard(rtx_insn*, int)
>>>          /aci-gcc-fsf/sources/gcc-fsf/gccsrc/gcc/haifa-sched.c:5752
>>> 0xa31cd2 invoke_dfa_lookahead_guard
>>>          /aci-gcc-fsf/sources/gcc-fsf/gccsrc/gcc/sel-sched.c:4212
>>> 0xa31cd2 find_best_expr
>>>          /aci-gcc-fsf/sources/gcc-fsf/gccsrc/gcc/sel-sched.c:4415
>>> 0xa343fb fill_insns
>>>          /aci-gcc-fsf/sources/gcc-fsf/gccsrc/gcc/sel-sched.c:5570
>>> 0xa343fb schedule_on_fences
>>>          /aci-gcc-fsf/sources/gcc-fsf/gccsrc/gcc/sel-sched.c:7395
>>> 0xa36010 sel_sched_region_2
>>>          /aci-gcc-fsf/sources/gcc-fsf/gccsrc/gcc/sel-sched.c:7533
>>> 0xa36f2a sel_sched_region_1
>>>          /aci-gcc-fsf/sources/gcc-fsf/gccsrc/gcc/sel-sched.c:7575
>>> 0xa36f2a sel_sched_region(int)
>>>          /aci-gcc-fsf/sources/gcc-fsf/gccsrc/gcc/sel-sched.c:7676
>>> 0xa37589 run_selective_scheduling()
>>>          /aci-gcc-fsf/sources/gcc-fsf/gccsrc/gcc/sel-sched.c:7752
>>> 0xa14aed rest_of_handle_sched2
>>>          /aci-gcc-fsf/sources/gcc-fsf/gccsrc/gcc/sched-rgn.c:3647
>>> 0xa14aed execute
>>>          /aci-gcc-fsf/sources/gcc-fsf/gccsrc/gcc/sched-rgn.c:3791
>>>
>>> See
>>> http://people.linaro.org/~christophe.lyon/cross-validation/gcc/gcc-5-branch/234625/arm-none-linux-gnueabihf/diff-gcc-rh60-arm-none-linux-gnueabihf-arm-cortex-a15-neon-vfpv4.txt
>>>
>>> Can you have a look?
>>
>> That's because A15 is the only place which enables
>> autopref_multipass_dfa_lookahead_guard as the DFA lookahead guard hook. But
>> autoprefetch modeling doesn't work for selective scheduling, it uses haifa
>> structures that are not kept up to date during sel-sched.  So this is not
>> supposed to work as soon as the param value for prefetcher lookahead depth
>> is positive.
>>
>> The following patch works for me.  Could you check it with your testing? If
>> it works fine for you, I would install the patch both for trunk and gcc-5.
>> It would be great to force sel-sched to be enabled, too.  I could do that
>> but I don't have the hardware or cross-arm target tools at the moment.
>>
>>          * haifa-sched.c (autopref_multipass_dfa_lookahead_guard): Disable
>> for selective scheduler.
>>
> It does work for me, it also fixes the other ICE I reported (on pr69307).
>
> But note that both tests pass on trunk.

This looks to me like PR rtl-optimization/68236 which I fixed on trunk.

Kyrill

> Christophe
>
>
>> Best,
>> Andrey
>>
>>
>>> Christophe
>>>
>>>> Andrey
>>>>
>>>>> Andrey
>>>>
>>>>