On Tue, Sep 28, 2021 at 2:59 PM Richard Biener via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
> On Mon, 27 Sep 2021, sunil.k.pandey wrote:
>
> > On Linux/x86_64,
> >
> > 6390c5047adb75960f86d56582e6322aaa4d9281 is the first bad commit
> > commit 6390c5047adb75960f86d56582e6322aaa4d9281
> > Author: Richard Biener <rguent...@suse.de>
> > Date: Wed Nov 18 09:36:57 2020 +0100
> >
> > Allow different vector types for stmt groups
> >
> > caused
> >
> > FAIL: gcc.dg/vect/bb-slp-17.c -flto -ffat-lto-objects scan-tree-dump-times
> > slp2 "optimized: basic block" 1
> > FAIL: gcc.dg/vect/bb-slp-17.c scan-tree-dump-times slp2 "optimized: basic
> > block" 1
>
> This shows that it is maybe a bad idea to support V2SImode vectorization
> with -m32 when we refuse to implement even plus.
>
> OTOH it's just the mode that's available, autovectorize_vector_modes
> doesn't include the corresponding mode but we still pick it up via
> the related vector mode for group-size == 2.
>
> > FAIL: gcc.dg/vect/bb-slp-pr65935.c -flto -ffat-lto-objects
> > scan-tree-dump-times slp1 "optimized: basic block" 10
> > FAIL: gcc.dg/vect/bb-slp-pr65935.c scan-tree-dump-times slp1 "optimized:
> > basic block" 10
>
> We are now vectorizing the SSE tail when vectorizing with AVX. I'll
> adjust the testcase to prefer SSE.
>
> > FAIL: gcc.target/i386/vect-pr97352.c scan-assembler-times vmov.pd 4
>
> With -mach=cascadelake we get
>
> vpermpd $68, c, %ymm0
> vpermpd $238, c, %ymm0
>
> instead of
>
> vmovapd c, %ymm1
> vinsertf128 $1, %xmm1, %ymm1, %ymm0
> vperm2f128 $49, %ymm1, %ymm1, %ymm0
>
> what's a way to disallow additional -march= from taking effect? It's
I usually add -mno-{avx,avx512f} and -mtune=generic or sometimes
-mprefer-vector-width=* to the testcases.
or use (?:vinsertf128|vpermpd) for alternative instructions.
> really impossible to cater for all possible ISA variants in these kind
> of testcases.
Additional option -march=cascadelake sometimes can find real regression.
>
> Richard.
--
BR,
Hongtao
