From: Jakub Jelinek <jakub@redhat.com>
To: "Liu, Hongtao" <hongtao.liu@intel.com>
Cc: Segher Boessenkool <segher@kernel.crashing.org>,
Richard Biener <richard.guenther@gmail.com>,
GCC Patches <gcc-patches@gcc.gnu.org>
Subject: Re: [PATCH] Canonicalize (vec_duplicate (not A)) to (not (vec_duplicate A)).
Date: Thu, 3 Jun 2021 13:06:24 +0200 [thread overview]
Message-ID: <20210603110624.GE7746@tucnak> (raw)
In-Reply-To: <CY4PR11MB2007083223D73249A34A3777E53C9@CY4PR11MB2007.namprd11.prod.outlook.com>
On Thu, Jun 03, 2021 at 11:03:43AM +0000, Liu, Hongtao via Gcc-patches wrote:
> In simplify_rtx, no simplication occurs, there is just the difference between
> (vec_duplicate (not REG)) and (not (vec_duplicate (REG)). So here tem will only be 0.
> Basically we don't know it's a simplication until combine successfully split the
> 3->2 instructions (not + broadcast + and to andnot + broadcast), but it's pretty awkward
> to do this in combine.
>
> Consider andnot is existed for many backends, I think a canonicalization is needed here.
> Maybe we can add insn canonicalization for transforming (and (vect_duplicate (not A)) B) to
> (and (not (duplicate (not A)) B) instead of (vec_duplicate (not A)) to (not (vec_duplicate A))?
For the (not (vec_duplicate)) vs. (vec_duplicate (not)) it isn't clear which
one is generally a win on major targets, so I'd say it is better to add a
combine splitter to swap it in backends that want that.
Jakub
next prev parent reply other threads:[~2021-06-03 11:06 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-25 5:49 [PATCH][i386] Split not+broadcast+pand to broadcast+pandn Hongtao Liu
2021-05-25 6:11 ` Andrew Pinski
2021-05-25 6:23 ` Hongtao Liu
2021-05-25 6:29 ` Andrew Pinski
2021-05-25 6:34 ` Hongtao Liu
2021-05-26 1:21 ` Hongtao Liu
2021-05-26 4:12 ` Andrew Pinski
2021-05-26 5:17 ` Hongtao Liu
2021-06-01 8:32 ` Hongtao Liu
2021-06-01 13:54 ` Segher Boessenkool
2021-06-01 14:02 ` Segher Boessenkool
2021-06-02 5:39 ` liuhongt
2021-06-02 5:39 ` [PATCH] Canonicalize (vec_duplicate (not A)) to (not (vec_duplicate A)) liuhongt
2021-06-02 7:07 ` Richard Biener
2021-06-02 20:46 ` Segher Boessenkool
2021-06-03 11:03 ` Liu, Hongtao
2021-06-03 11:06 ` Jakub Jelinek [this message]
2021-06-03 19:59 ` Segher Boessenkool
2021-06-04 2:48 ` Liu, Hongtao
2021-06-02 5:49 ` Hongtao Liu
2021-06-02 5:41 ` [PATCH] Canonicalize (vec_duplicate (not A)) to (not (vec_duplicate A)) liuhongt
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