Re: Various selective scheduling fixes

[Jeff Law <law@redhat.com>]

On 04/01/2016 07:26 AM, Christophe Lyon wrote:
> On 1 April 2016 at 15:12, Kyrill Tkachov <kyrylo.tkachov@foss.arm.com> wrote:
>> 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.
>>
> You are right: I've just checked that backporting your patch r230088 does
> fix the problems in the gcc-5 branch.
>
> Can I commit it ? I guess the question is for Jakub?
Yes, you can commit it to the branch.

jeff