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From: "ak at muc dot de" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug middle-end/17886] New: variable rotate and long long rotate should be better optimized
Date: Fri, 08 Oct 2004 00:04:00 -0000	[thread overview]
Message-ID: <20041008000425.17886.ak@muc.de> (raw)

gcc can detect the (x << y)|(x >> (bitwidth-y)) idiom for rotate and convert
it into the machine rotate instruction. But it only works when y is a constant
and is not long long.

Enhancement request is to handle it for long long too (on 32bit) and
to handle variable shifts.

The attached test case should use rol in f1-f4

-- 
           Summary: variable rotate and long long rotate should be better
                    optimized
           Product: gcc
           Version: 4.0.0
            Status: UNCONFIRMED
          Severity: enhancement
          Priority: P2
         Component: middle-end
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: ak at muc dot de
                CC: gcc-bugs at gcc dot gnu dot org
GCC target triplet: i386-linux


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17886


             reply	other threads:[~2004-10-08  0:04 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2004-10-08  0:04 ak at muc dot de [this message]
2004-10-08  0:05 ` [Bug middle-end/17886] " ak at muc dot de
2004-10-08  0:07 ` steven at gcc dot gnu dot org
2004-10-08  0:16 ` pinskia at gcc dot gnu dot org
2005-09-28  0:15 ` mmitchel at gcc dot gnu dot org
2005-09-28  0:18 ` mmitchel at gcc dot gnu dot org
2005-09-28  0:57 ` mmitchel at gcc dot gnu dot org
2005-09-28  1:53 ` mmitchel at gcc dot gnu dot org
2005-09-28  2:11 ` mmitchel at gcc dot gnu dot org
2005-09-28 16:24 ` mmitchel at gcc dot gnu dot org
2005-09-29  3:32 ` cvs-commit at gcc dot gnu dot org
2005-09-29  3:52 ` mmitchel at gcc dot gnu dot org
2005-09-29  4:36 ` dank at kegel dot com
2005-09-29  5:05 ` mmitchel at gcc dot gnu dot org

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