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Date: Mon, 25 Feb 2008 05:02:00 -0000
Subject: [Bug middle-end/35357]  New: Loop peeling not happening
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From: "xinliangli at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
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//David Li

Loop peeling is special case of index splitting. Gcc has support for this
(under -O3 -funrool_loops, also -fno-tree-vectorize for the simple case), but
it does not happen for the following cases:

int a[100];
int b[1000];
void foo(int n)
{
      int i;
      for ( i = 0; i <= n; i++)
      {

           b[i*2] = a[3*i+1];
           if (i < n)
              b[i*2] +=1;
      }
}


---------------------

int a[100];
int b[1000];
void foo(int n)
{
      int i;
      for ( i = 0; i < n; i++)
      {
          if (i==0) b[i*2] +=1;
           b[i*2] = a[3*i+1];
      }
}


-- 
           Summary: Loop peeling not happening
           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=35357