Re: Various selective scheduling fixes

[Kyrill Tkachov <kyrylo dot tkachov at foss dot arm dot 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