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* [Bug middle-end/35341]  New: Early exit loop with short known trip count not unrolled
@ 2008-02-24  4:21 xinliangli at gmail dot com
  2008-02-24 21:58 ` [Bug middle-end/35341] " rguenth at gcc dot gnu dot org
  0 siblings, 1 reply; 2+ messages in thread
From: xinliangli at gmail dot com @ 2008-02-24  4:21 UTC (permalink / raw)
  To: gcc-bugs

Gcc fully unrolls short trip counted (known) loop if the unrolled loop body
size d oes not exceed a threshold. However, if  the loop has early exit, this
is not done -- leading to missing scalar opt later on.

Example:

int a[100];
int b[100];
int foo(void)
{
     int i, j;

     for (i = 0; i < 5; i ++)
     {
          a[2*i] += a[i];
          if (a[2*i] == 10) break;
     }

     return 0;
}


-- 
           Summary: Early exit loop with short known trip count not unrolled
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: middle-end
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: xinliangli at gmail dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35341


^ permalink raw reply	[flat|nested] 2+ messages in thread
* [Bug middle-end/35341] Early exit loop with short known trip count not unrolled
  2008-02-24  4:21 [Bug middle-end/35341] New: Early exit loop with short known trip count not unrolled xinliangli at gmail dot com
@ 2008-02-24 21:58 ` rguenth at gcc dot gnu dot org
  0 siblings, 0 replies; 2+ messages in thread
From: rguenth at gcc dot gnu dot org @ 2008-02-24 21:58 UTC (permalink / raw)
  To: gcc-bugs



-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |rakdver at gcc dot gnu dot
                   |                            |org
           Severity|normal                      |enhancement
           Keywords|                            |missed-optimization
            Version|unknown                     |4.3.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35341


^ permalink raw reply	[flat|nested] 2+ messages in thread
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2008-02-24  4:21 [Bug middle-end/35341] New: Early exit loop with short known trip count not unrolled xinliangli at gmail dot com
2008-02-24 21:58 ` [Bug middle-end/35341] " rguenth at gcc dot gnu dot org

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