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From: "wsnyder at wsnyder dot org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/97623] [9/10/11 Regression] Extremely slow O2 compile (>>O(n^2))
Date: Fri, 30 Oct 2020 13:55:08 +0000 [thread overview]
Message-ID: <bug-97623-4-eLzOhqqAgQ@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-97623-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97623
--- Comment #7 from Wilson Snyder <wsnyder at wsnyder dot org> ---
Thanks for the quick service. I can't easily try GCC trunk, but:
-O2
compile 98.61s
runtime 25.76s
-O2 -fno-code-hoisting
compile 40.13s
runtime 26.40s (+2.5%)
-Os
compile 4.25s
runtime 23.42s (-10%)
That -Os runs faster is expected as this program is generally instruction-fetch
limited. I'd have expected -fno-code-hoisting to help more, compile time wise.
Am I correct in understanding that the slowdown is roughly correlated to the
number of "if" or "?:" statements?
next prev parent reply other threads:[~2020-10-30 13:55 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-29 2:02 [Bug c++/97623] New: " wsnyder at wsnyder dot org
2020-10-29 2:03 ` [Bug c++/97623] " wsnyder at wsnyder dot org
2020-10-29 7:17 ` [Bug tree-optimization/97623] [9/10/11 Regression] " rguenth at gcc dot gnu.org
2020-10-29 7:18 ` rguenth at gcc dot gnu.org
2020-10-30 12:35 ` rguenth at gcc dot gnu.org
2020-10-30 12:35 ` rguenth at gcc dot gnu.org
2020-10-30 13:25 ` cvs-commit at gcc dot gnu.org
2020-10-30 13:28 ` rguenth at gcc dot gnu.org
2020-10-30 13:55 ` wsnyder at wsnyder dot org [this message]
2020-11-03 14:16 ` rguenth at gcc dot gnu.org
2020-11-03 15:23 ` cvs-commit at gcc dot gnu.org
2020-11-06 1:50 ` wsnyder at wsnyder dot org
2020-11-06 9:52 ` rguenther at suse dot de
2020-11-06 12:37 ` wsnyder at wsnyder dot org
2020-11-06 13:00 ` rguenth at gcc dot gnu.org
2020-11-06 13:19 ` marxin at gcc dot gnu.org
2020-11-06 13:28 ` rguenth at gcc dot gnu.org
2020-11-06 13:45 ` rguenth at gcc dot gnu.org
2020-11-11 11:51 ` cvs-commit at gcc dot gnu.org
2020-11-11 16:11 ` tschwinge at gcc dot gnu.org
2020-11-11 17:17 ` cvs-commit at gcc dot gnu.org
2020-12-07 13:03 ` [Bug tree-optimization/97623] [9/10 " rguenth at gcc dot gnu.org
2021-01-11 13:37 ` cvs-commit at gcc dot gnu.org
2021-01-11 13:37 ` cvs-commit at gcc dot gnu.org
2021-01-11 13:39 ` [Bug tree-optimization/97623] [9 " rguenth at gcc dot gnu.org
2021-06-01 8:18 ` rguenth at gcc dot gnu.org
2022-05-27 8:56 ` rguenth at gcc dot gnu.org
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