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From: "roger at nextmovesoftware dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug middle-end/103641] [11/12 regression] Severe compile time regression in SLP vectorize step
Date: Fri, 10 Dec 2021 13:17:09 +0000 [thread overview]
Message-ID: <bug-103641-4-5WFUzrj5c2@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-103641-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103641
Roger Sayle <roger at nextmovesoftware dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |roger at nextmovesoftware dot com
--- Comment #18 from Roger Sayle <roger at nextmovesoftware dot com> ---
Hm. PR 87256 was much easier to diagnose, as the cost of multiplication on
hppa64 was 20-30 ALU instructions, so a single pathological multiplier would
combinatorially challenge synth_mult. The new costs on AArch64 have a vector
multiplication cost of 4, which is very reasonable. But I did see somewhere in
Andre's patch that had an ALU cost of COSTS_N_INSNS(0), which would fool
synth_mult that it's allowed/beneficial to use an infinite number of ALU
instructions to avoid a single multiplication. Likewise, the very cheap (free)
shifts on ARM. But this is just guess work; a reduced testcase that exhibits
the problem would be helpful.
next prev parent reply other threads:[~2021-12-10 13:17 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-10 9:03 [Bug rtl-optimization/103641] New: [aarch64][11 " husseydevin at gmail dot com
2021-12-10 9:25 ` [Bug rtl-optimization/103641] " marxin at gcc dot gnu.org
2021-12-10 9:37 ` [Bug tree-optimization/103641] " pinskia at gcc dot gnu.org
2021-12-10 9:43 ` [Bug tree-optimization/103641] [11/12 " pinskia at gcc dot gnu.org
2021-12-10 9:46 ` pinskia at gcc dot gnu.org
2021-12-10 9:56 ` pinskia at gcc dot gnu.org
2021-12-10 10:01 ` marxin at gcc dot gnu.org
2021-12-10 10:02 ` pinskia at gcc dot gnu.org
2021-12-10 10:03 ` pinskia at gcc dot gnu.org
2021-12-10 10:06 ` marxin at gcc dot gnu.org
2021-12-10 10:08 ` pinskia at gcc dot gnu.org
2021-12-10 10:09 ` pinskia at gcc dot gnu.org
2021-12-10 10:12 ` marxin at gcc dot gnu.org
2021-12-10 10:12 ` pinskia at gcc dot gnu.org
2021-12-10 10:14 ` pinskia at gcc dot gnu.org
2021-12-10 10:15 ` [Bug middle-end/103641] " pinskia at gcc dot gnu.org
2021-12-10 10:24 ` pinskia at gcc dot gnu.org
2021-12-10 10:28 ` pinskia at gcc dot gnu.org
2021-12-10 13:17 ` roger at nextmovesoftware dot com [this message]
2021-12-10 13:19 ` husseydevin at gmail dot com
2022-01-18 14:10 ` rguenth at gcc dot gnu.org
2022-01-22 14:30 ` roger at nextmovesoftware dot com
2022-01-24 8:13 ` rguenther at suse dot de
2022-01-24 16:49 ` roger at nextmovesoftware dot com
2022-01-24 17:02 ` roger at nextmovesoftware dot com
2022-01-25 7:23 ` rguenth at gcc dot gnu.org
2022-01-25 7:52 ` rguenth at gcc dot gnu.org
2022-02-04 7:26 ` rguenth at gcc dot gnu.org
2022-02-04 10:30 ` cvs-commit at gcc dot gnu.org
2022-02-04 10:43 ` rguenth at gcc dot gnu.org
2022-02-04 11:08 ` tnfchris at gcc dot gnu.org
2022-02-07 12:19 ` tnfchris at gcc dot gnu.org
2022-02-07 15:05 ` [Bug middle-end/103641] [11 " rguenth at gcc dot gnu.org
2022-02-08 8:08 ` tnfchris at gcc dot gnu.org
2022-02-08 8:13 ` pinskia at gcc dot gnu.org
2022-02-08 8:15 ` tnfchris at gcc dot gnu.org
2022-03-16 8:22 ` cvs-commit at gcc dot gnu.org
2022-03-16 8:23 ` rguenth at gcc dot gnu.org
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