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[Bug target/69671] [6 Regression] FAIL: gcc.target/i386/avx512vl-vpmovqb-1.c scan-assembler-times vpmovqb[ \\t]+[^{\n]*%ymm[0-9]+[^\n]*%xmm[0-9]+{%k[1-7]}{z}(?
- From: "kyukhin at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Thu, 18 Feb 2016 11:16:50 +0000
- Subject: [Bug target/69671] [6 Regression] FAIL: gcc.target/i386/avx512vl-vpmovqb-1.c scan-assembler-times vpmovqb[ \\t]+[^{\n]*%ymm[0-9]+[^\n]*%xmm[0-9]+{%k[1-7]}{z}(?
- Auto-submitted: auto-generated
- References: <bug-69671-4 at http dot gcc dot gnu dot org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69671
--- Comment #24 from Kirill Yukhin <kyukhin at gcc dot gnu.org> ---
(In reply to rguenther@suse.de from comment #23)
> On Wed, 17 Feb 2016, jakub at gcc dot gnu.org wrote:
>
> > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69671
> >
> > --- Comment #22 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
> > Created attachment 37722 [details]
> > --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=37722&action=edit
> > gcc6-pr69671.patch
> >
> > Actually, on a closer look, I believe the only problem are the patterns that
> > use a vector_move_operand "0C" inside of vec_select with only constants as the
> > parallel's operands. Because fwprop is able to propagate constants into
> > instructions (thus undo the CSE effect), but doesn't do anything on these,
> > because it also simplifies them, so instead of the expected say
> > (vec_select:V4QI (const_vector:V16QI [
> > (const_int 0 [0])
> > (const_int 0 [0])
> > (const_int 0 [0])
> > (const_int 0 [0])
> > (const_int 0 [0])
> > (const_int 0 [0])
> > (const_int 0 [0])
> > (const_int 0 [0])
> > (const_int 0 [0])
> > (const_int 0 [0])
> > (const_int 0 [0])
> > (const_int 0 [0])
> > (const_int 0 [0])
> > (const_int 0 [0])
> > (const_int 0 [0])
> > (const_int 0 [0])
> > ])
> > (parallel [
> > (const_int 0 [0])
> > (const_int 1 [0x1])
> > (const_int 2 [0x2])
> > (const_int 3 [0x3])
> > ]))
> > we get in there simplified:
> > (const_vector:V4QI [
> > (const_int 0 [0])
> > (const_int 0 [0])
> > (const_int 0 [0])
> > (const_int 0 [0])
> > ])
> > So, by adding extra patterns for that simplification fwprop is able to do its
> > job even if CSE did a better job.
>
> Of course then I wonder why we didn't simplify this in the first place
> when generating RTL and need to wait for forwprop ...
>
> But yes, sounds like the easiest way to go forward.
Agree.