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From: "eggert at cs dot ucla.edu" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/99591] Improving __builtin_add_overflow performance on x86-64
Date: Wed, 01 Sep 2021 07:44:38 +0000 [thread overview]
Message-ID: <bug-99591-4-0fUV1ZRdPW@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-99591-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99591
eggert at cs dot ucla.edu changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |eggert at cs dot ucla.edu
--- Comment #3 from eggert at cs dot ucla.edu ---
(In reply to Andrew Pinski from comment #2)
> (In reply to Andrew Pinski from comment #1)
> > Looks fixed for GCC 11+.
It doesn't appear to be fixed in GCC 11.2.1 20210728 (Red Hat 11.2.1-1). For
signed1_overflow I get the same suboptimal machine code described in comment
#0. For signed2_overflow I get:
signed2_overflow:
movswl %si, %esi
movswl %di, %edi
addw %si, %di
seto %al
ret
Although this is better than the machine code described in comment #0 it's
still clearly suboptimal, as the two movswl instructions are redundant and both
can be omitted.
next prev parent reply other threads:[~2021-09-01 7:44 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-15 8:46 [Bug target/99591] New: " eggert at gnu dot org
2021-09-01 5:30 ` [Bug target/99591] " pinskia at gcc dot gnu.org
2021-09-01 5:32 ` pinskia at gcc dot gnu.org
2021-09-01 7:44 ` eggert at cs dot ucla.edu [this message]
2021-09-01 7:57 ` [Bug c/99591] " pinskia at gcc dot gnu.org
2021-09-01 8:16 ` jakub at gcc dot gnu.org
2021-09-01 8:53 ` [Bug tree-optimization/99591] " jakub at gcc dot gnu.org
2021-09-02 9:26 ` cvs-commit at gcc dot gnu.org
2021-09-02 9:29 ` jakub at gcc dot gnu.org
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