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From: "jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/108498] [11/12/13 Regression] ppc64 big endian generates uninitialized reads with -fstore-merging
Date: Tue, 24 Jan 2023 17:46:42 +0000 [thread overview]
Message-ID: <bug-108498-4-Q1GPUklLY6@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-108498-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108498
--- Comment #24 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
(In reply to Eric Botcazou from comment #23)
> > The C/C++ FEs since r9-6625-gbec1da64aec26a490 turn some array initializers
> > into strings.
>
> Ouch. I'm not sure that's worthwhile if the arrays are not byte-aligned.
They actually are byte aligned.
What happens is basically we have first some INTEGER_CST byte-sized store,
then a STRING_CST store and then an INTEGER_CST store of just a few bits.
So, the conditions for merging the first INTEGER_CST with the STRING_CST are
met,
string_concatenate is set, everything is contiguous and so the bit store at the
end
is merged in (in the testcase there are some other stores in between too, all
INTEGER_CSTs).
In the end we got a group with 71 bits with byte aligned start and we just
store 64 bits and leave those 7 uninitialized.
next prev parent reply other threads:[~2023-01-24 17:46 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-23 14:18 [Bug c/108498] New: " kungfujesus06 at gmail dot com
2023-01-23 15:18 ` [Bug c/108498] " kungfujesus06 at gmail dot com
2023-01-23 15:20 ` [Bug middle-end/108498] " pinskia at gcc dot gnu.org
2023-01-23 15:22 ` kungfujesus06 at gmail dot com
2023-01-23 15:34 ` kungfujesus06 at gmail dot com
2023-01-23 15:38 ` rguenth at gcc dot gnu.org
2023-01-23 15:48 ` kungfujesus06 at gmail dot com
2023-01-23 15:51 ` kungfujesus06 at gmail dot com
2023-01-23 15:54 ` kungfujesus06 at gmail dot com
2023-01-23 17:39 ` pinskia at gcc dot gnu.org
2023-01-23 17:40 ` pinskia at gcc dot gnu.org
2023-01-23 17:42 ` kungfujesus06 at gmail dot com
2023-01-23 17:45 ` pinskia at gcc dot gnu.org
2023-01-23 17:51 ` [Bug tree-optimization/108498] " pinskia at gcc dot gnu.org
2023-01-23 17:51 ` kungfujesus06 at gmail dot com
2023-01-23 18:18 ` kungfujesus06 at gmail dot com
2023-01-23 19:04 ` jakub at gcc dot gnu.org
2023-01-24 12:20 ` [Bug tree-optimization/108498] [11/12/13 Regression] " jakub at gcc dot gnu.org
2023-01-24 12:55 ` jakub at gcc dot gnu.org
2023-01-24 15:35 ` jakub at gcc dot gnu.org
2023-01-24 16:09 ` jakub at gcc dot gnu.org
2023-01-24 16:48 ` ebotcazou at gcc dot gnu.org
2023-01-24 17:10 ` jakub at gcc dot gnu.org
2023-01-24 17:33 ` ebotcazou at gcc dot gnu.org
2023-01-24 17:46 ` jakub at gcc dot gnu.org [this message]
2023-01-25 9:51 ` cvs-commit at gcc dot gnu.org
2023-01-25 10:35 ` [Bug tree-optimization/108498] [11/12 " jakub at gcc dot gnu.org
2023-02-10 17:46 ` cvs-commit at gcc dot gnu.org
2023-02-10 18:00 ` [Bug tree-optimization/108498] [11 " jakub at gcc dot gnu.org
2023-05-02 20:13 ` cvs-commit at gcc dot gnu.org
2023-05-03 10:35 ` jakub at gcc dot gnu.org
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