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From: "aldyh at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/80548] -Wmaybe-uninitialized false positive when an assignment is added
Date: Tue, 30 Nov 2021 14:38:04 +0000 [thread overview]
Message-ID: <bug-80548-4-rgMx8wAS42@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-80548-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80548
--- Comment #5 from Aldy Hernandez <aldyh at gcc dot gnu.org> ---
(In reply to Aldy Hernandez from comment #4)
> Created attachment 51908 [details]
> untested patch
>
> Like this. It fixes the problem at least for -O2.
For -O1 y'all are on your own because there are no threaders smart enough to
pick up the pattern.
We'd need a threader at -O1 that runs after loop_done to pick it up:
$ ./cc1 a.c -O1 -Wall -fenable-tree-threadfull2 -quiet
cc1: note: enable pass tree-threadfull2 for functions in the range of [0,
4294967295]
$
Voila, no warning.
DOM3 runs after loop_done, so that would be candidate to handle this since it
threads at -O1. However, this won't happen in this release. It would require
a converting DOM threading to a hybrid approach (and see if the custom copier
can handle cross-loop threading), or convert it entirely to the backward
threader (would require ranger handling floats).
next prev parent reply other threads:[~2021-11-30 14:38 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <bug-80548-4@http.gcc.gnu.org/bugzilla/>
2021-04-13 23:56 ` [Bug middle-end/80548] " msebor at gcc dot gnu.org
2021-11-30 14:09 ` [Bug tree-optimization/80548] " aldyh at gcc dot gnu.org
2021-11-30 14:20 ` aldyh at gcc dot gnu.org
2021-11-30 14:38 ` aldyh at gcc dot gnu.org [this message]
2021-12-01 16:03 ` aldyh at gcc dot gnu.org
2022-11-20 4:05 ` law at gcc dot gnu.org
2022-11-21 9:59 ` vincent-gcc at vinc17 dot net
2022-11-21 14:40 ` law at gcc dot gnu.org
2022-11-22 10:07 ` vincent-gcc at vinc17 dot net
2022-11-22 13:10 ` law at gcc dot gnu.org
2022-11-23 16:46 ` vincent-gcc at vinc17 dot net
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