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From: "absoler at smail dot nju.edu.cn" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/113838] regression of redundant load operation
 introduced by -fno-tree-forwprop introduce
Date: Fri, 09 Feb 2024 03:38:47 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D113838

--- Comment #4 from absoler at smail dot nju.edu.cn ---
@(In reply to Jakub Jelinek from comment #1)
> Disabling optimizations and then wondering why optimizations didn't happen
> is too weird.  Don't do that.  Such options are intended for debugging GC=
C,
> or perhaps working around some compiler or application bug, but performan=
ce
> of generated code should be only judged without such options.

The gimple ir has no problem, but `_13` is replaced with g_26[5][3][0] in t=
he
follow-up process, this shouldn't be expected behavior.

We question this option because we found in an older version of gcc (10.2.0=
),
only the O2 option is needed to produce the same bad code, so we worry about
there's a hidden un-fixed problem and it's re-triggered by this option.

Besides, the bad binary code introduce more load operation than the source =
code
(without optimization), so we thought it's necessary to check it regardless=
 of
which optimization is disabled.=