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* [Bug c/19078] New: [4.0 Regression] Poor quality code after loop unrolling.
@ 2004-12-19 10:58 chris at bubblescope dot net
  2004-12-19 13:23 ` [Bug rtl-optimization/19078] " pinskia at gcc dot gnu dot org
                   ` (20 more replies)
  0 siblings, 21 replies; 22+ messages in thread
From: chris at bubblescope dot net @ 2004-12-19 10:58 UTC (permalink / raw)
  To: gcc-bugs

The function:

int* find(int* a,int *b)
{
for(;a!=b;++a)
  if(*a==2) return a;
return a;
}

Is unrolled in both 3.3 and 4.0 with -O2 -funroll-loops. The code from 4.0 is
however about twice as large, and seems to feature a large amount of unnessasary
rearranging of registers, and is somewhat slower.

-- 
           Summary: [4.0 Regression] Poor quality code after loop unrolling.
           Product: gcc
           Version: 4.0.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: chris at bubblescope dot net
                CC: gcc-bugs at gcc dot gnu dot org
  GCC host triplet: i686-pc-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19078


^ permalink raw reply	[flat|nested] 22+ messages in thread
end of thread, other threads:[~2005-09-27 16:17 UTC | newest]

Thread overview: 22+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2004-12-19 10:58 [Bug c/19078] New: [4.0 Regression] Poor quality code after loop unrolling chris at bubblescope dot net
2004-12-19 13:23 ` [Bug rtl-optimization/19078] " pinskia at gcc dot gnu dot org
2004-12-19 19:41 ` rakdver at gcc dot gnu dot org
2004-12-19 22:04 ` rakdver at gcc dot gnu dot org
2004-12-19 22:11 ` pcarlini at suse dot de
2004-12-20 15:04 ` steven at gcc dot gnu dot org
2004-12-20 15:13 ` pcarlini at suse dot de
2004-12-20 15:22 ` pcarlini at suse dot de
2004-12-20 18:44 ` rakdver at gcc dot gnu dot org
2004-12-22 16:46 ` pinskia at gcc dot gnu dot org
2004-12-25 20:32 ` pcarlini at suse dot de
2004-12-25 22:54 ` cvs-commit at gcc dot gnu dot org
2004-12-25 22:58 ` rakdver at gcc dot gnu dot org
2005-01-21 14:06 ` steven at gcc dot gnu dot org
2005-01-24 13:20 ` rakdver at atrey dot karlin dot mff dot cuni dot cz
2005-02-10 17:45 ` steven at gcc dot gnu dot org
2005-02-10 18:03 ` rakdver at atrey dot karlin dot mff dot cuni dot cz
2005-02-10 20:53 ` law at redhat dot com
2005-02-10 21:13 ` kenner at vlsi1 dot ultra dot nyu dot edu
2005-04-21  4:57 ` [Bug rtl-optimization/19078] [4.0/4.1 " mmitchel at gcc dot gnu dot org
2005-07-08  1:36 ` mmitchel at gcc dot gnu dot org
2005-09-27 16:19 ` mmitchel at gcc dot gnu dot org

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