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From: Alan Modra <amodra@bigpond.net.au>
To: nobody@gcc.gnu.org
Cc: gcc-prs@gcc.gnu.org,
Subject: Re: c/10339: [sparc] Invalid optimization: replacing strncmp by memcmp
Date: Tue, 08 Apr 2003 01:16:00 -0000 [thread overview]
Message-ID: <20030408011600.6052.qmail@sources.redhat.com> (raw)
The following reply was made to PR optimization/10339; it has been noted by GNATS.
From: Alan Modra <amodra@bigpond.net.au>
To: bangerth@dealii.org, gcc-bugs@gcc.gnu.org, ubell@sleepycat.com,
gcc-gnats@gcc.gnu.org
Cc:
Subject: Re: c/10339: [sparc] Invalid optimization: replacing strncmp by memcmp
Date: Tue, 08 Apr 2003 10:43:36 +0930
On Mon, Apr 07, 2003 at 06:42:47PM -0000, bangerth@dealii.org wrote:
> Old Synopsis: strncmp generates imPure code
> New Synopsis: [sparc] Invalid optimization: replacing strncmp by memcmp
Also happens on powerpc-linux and powerpc64-linux. Incidentally,
I think Andreas' suggestion that memcmp is allowed to compare from
the upper end of the arrays is not very likely to happen given
memcmp's return value. A more reasonable objection to the
strncmp -> memcmp transformation is that a memcmp implementation
might load multiple words into registers (say a cache-line worth),
before comparing.
--
Alan Modra
IBM OzLabs - Linux Technology Centre
next reply other threads:[~2003-04-08 1:16 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-04-08 1:16 Alan Modra [this message]
-- strict thread matches above, loose matches on Subject: below --
2003-04-09 5:56 Richard Henderson
2003-04-07 18:42 bangerth
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