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From: "b.buschinski at googlemail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/105740] New: missed optimization switch transformation for conditions with duplicate conditions
Date: Thu, 26 May 2022 11:26:46 +0000 [thread overview]
Message-ID: <bug-105740-4@http.gcc.gnu.org/bugzilla/> (raw)
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105740
Bug ID: 105740
Summary: missed optimization switch transformation for
conditions with duplicate conditions
Product: gcc
Version: 12.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: b.buschinski at googlemail dot com
Target Milestone: ---
Created attachment 53037
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=53037&action=edit
Attached code + asm from the compiler explorer link
Compiler Explorer Link: https://godbolt.org/z/q76s99Gj9
The code on the left does not generate a switch statement.
The code on the right does generate a switch statement.
The code works similar, the only difference is that the duplicate "f->len > 3"
check is moved to the top for the "right" version.
The compiler explorer code is actually a minimized version of the code I work
on (with way more conditions in a hot code path), where I can not easily move
the length check to the top, because the "f-> len > 3 && ..." is done in a very
complicated macro, but that's just details.
I expected both code versions to generate the same assembler.
Tested with GCC-12.1 and 11.3. 10.3 does not generate a switch version for both
versions, as only 11 got this nice feature.
On x86_64 Linux.
Please let me know if you need any additional details or if this report was
useful at all.
next reply other threads:[~2022-05-26 11:26 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-26 11:26 b.buschinski at googlemail dot com [this message]
2022-05-30 9:57 ` [Bug tree-optimization/105740] " marxin at gcc dot gnu.org
2022-06-21 2:45 ` luoxhu at gcc dot gnu.org
2022-06-21 7:30 ` marxin at gcc dot gnu.org
2022-06-21 9:02 ` rguenth at gcc dot gnu.org
2022-06-21 9:12 ` jakub at gcc dot gnu.org
2022-06-21 9:26 ` rguenther at suse dot de
2022-06-21 9:29 ` cvs-commit at gcc dot gnu.org
2022-06-22 6:19 ` luoxhu at gcc dot gnu.org
2022-06-27 13:58 ` marxin at gcc dot gnu.org
2022-07-01 2:06 ` luoxhu at gcc dot gnu.org
2022-07-08 10:46 ` marxin at gcc dot gnu.org
2023-06-26 6:43 ` b.buschinski at googlemail dot com
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