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From: "crazylht at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/111820] [13/14 Regression] Compiler time hog in the vectorizer with `-O3 -fno-tree-vrp`
Date: Mon, 16 Oct 2023 07:43:34 +0000 [thread overview]
Message-ID: <bug-111820-4-qu9y3k9Hgn@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-111820-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111820
--- Comment #5 from Hongtao.liu <crazylht at gmail dot com> ---
(In reply to Richard Biener from comment #3)
> for (unsigned i = 0; i != skipn - 1; i++)
> begin = wi::mul (begin, wi::to_wide (step_expr));
>
> (gdb) p skipn
> $5 = 4294967292
>
> niters is 4294967292 in vect_update_ivs_after_vectorizer. Maybe the loop
> should terminate when begin is zero. But I wonder why we pass in 'niters'
Here, it want to calculate begin * pow (step_expr, skipn), yes we can just skip
the loop when begin is 0.
Also optimize the loop to shift when step_expr is power of 2.
But for other cases, the loop is still needed.
next prev parent reply other threads:[~2023-10-16 7:43 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-15 2:02 [Bug c/111820] New: GCC: 14: hangs with a simple while loop 141242068 at smail dot nju.edu.cn
2023-10-15 2:07 ` [Bug tree-optimization/111820] " pinskia at gcc dot gnu.org
2023-10-15 2:09 ` [Bug tree-optimization/111820] [13/14 Regression] Compiler time hog in the vectorizer with `-O3 -fno-tree-vrp` pinskia at gcc dot gnu.org
2023-10-16 7:14 ` rguenth at gcc dot gnu.org
2023-10-16 7:22 ` crazylht at gmail dot com
2023-10-16 7:43 ` crazylht at gmail dot com [this message]
2023-10-16 8:46 ` rguenther at suse dot de
2023-10-17 6:56 ` crazylht at gmail dot com
2023-10-17 7:16 ` rguenther at suse dot de
2023-10-17 9:13 ` crazylht at gmail dot com
2023-10-17 9:47 ` rguenth at gcc dot gnu.org
2023-10-23 1:16 ` cvs-commit at gcc dot gnu.org
2023-10-23 2:39 ` crazylht at gmail dot com
2023-10-23 9:42 ` [Bug tree-optimization/111820] [13 " rguenth at gcc dot gnu.org
2023-10-27 1:06 ` cvs-commit at gcc dot gnu.org
2023-10-27 1:18 ` crazylht at gmail dot com
2023-10-27 1:20 ` pinskia at gcc dot gnu.org
2023-10-27 3:29 ` pinskia at gcc dot gnu.org
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