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From: "qing.zhao at oracle dot com" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug middle-end/104550] bogus warning from -Wuninitialized + -ftrivial-auto-var-init=pattern Date: Thu, 17 Feb 2022 16:47:13 +0000 [thread overview] Message-ID: <bug-104550-4-ZcllzxL8N8@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-104550-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104550 --- Comment #14 from Qing Zhao <qing.zhao at oracle dot com> --- > On Feb 17, 2022, at 1:54 AM, rguenther at suse dot de <gcc-bugzilla@gcc.gnu.org> wrote: >> >> If padding clearing is exposed too late till RTL expansion, some tree >> optimization will not be able to be applied on the expanded stores? > > Doesn't the same argument apply to .DEFERRED_INIT itself? Dependent > on the .DEFERRED_INIT expansion strathegy the padding clearing might > be unneccessary (for example when using memset())? Yes, because we use memset to initialize auto-var when it’s in memory, we do not insert a call to __builtin_clear_padding to zero initialization. We only insert __builtin_clear_padding to pattern Initialization to set the padding to zeroes. That’s why this bug only exposed with pattern init. > >> the approach to mark the load "MEM" as not needing a warning might be better? > > It's probably a good thing anyway, the 'R' in the RMW cycle isn't really > a use. If it’s not a real use, should we exclude this case from emitting the uninitialized warning directly?
next prev parent reply other threads:[~2022-02-17 16:47 UTC|newest] Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-02-15 15:49 [Bug middle-end/104550] New: " qinzhao at gcc dot gnu.org 2022-02-15 15:50 ` [Bug middle-end/104550] " qinzhao at gcc dot gnu.org 2022-02-15 15:52 ` qinzhao at gcc dot gnu.org 2022-02-15 21:33 ` qinzhao at gcc dot gnu.org 2022-02-15 21:38 ` pinskia at gcc dot gnu.org 2022-02-15 22:38 ` qing.zhao at oracle dot com 2022-02-16 10:33 ` rguenther at suse dot de 2022-02-16 15:05 ` qinzhao at gcc dot gnu.org 2022-02-16 15:38 ` jakub at gcc dot gnu.org 2022-02-16 16:24 ` qinzhao at gcc dot gnu.org 2022-02-16 16:44 ` jakub at gcc dot gnu.org 2022-02-16 16:57 ` qinzhao at gcc dot gnu.org 2022-02-17 7:54 ` rguenther at suse dot de 2022-02-17 8:01 ` rguenther at suse dot de 2022-02-17 16:47 ` qing.zhao at oracle dot com [this message] 2022-02-17 16:53 ` jakub at gcc dot gnu.org 2022-02-18 6:53 ` rguenther at suse dot de 2022-02-18 17:16 ` qinzhao at gcc dot gnu.org 2022-02-18 20:14 ` qinzhao at gcc dot gnu.org 2022-02-21 7:56 ` rguenth at gcc dot gnu.org 2022-02-21 15:21 ` qing.zhao at oracle dot com 2022-02-28 15:58 ` cvs-commit at gcc dot gnu.org 2022-02-28 16:00 ` qinzhao at gcc dot gnu.org
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