[Bug tree-optimization/30102] New: missed strength reduction optimization (irreducible loops)

[dann at godzilla dot ics dot uci dot edu]

The following 2 functions should be compiled to the same assembly. 
This is one of Briggs' compiler benchmarks.


void strength_test4(int *data)
{
  int i;
  if (data[1]) {
    i = 2;
    goto here;
  }
  i = 0;
  do {
    i = i + 1;
here:
    data[data[2]] = 2;
  } while (i * 21 < data[3]);
}
void strength_result4(int *data)
{
  int i;
  if (data[1]) {
    i = 42;
    goto here;
  }
  i = 0;
  do {
    i = i + 21;
here:
    data[data[2]] = 2;
  } while (i < data[3]);
}


-- 
           Summary: missed strength reduction optimization (irreducible
                    loops)
           Product: gcc
           Version: 4.3.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: dann at godzilla dot ics dot uci dot edu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30102