[Bug middle-end/31892] New: optimization: Loop not optimized away

[burnus at gcc dot gnu dot org]

Expected: The following loop is optimized way using gfortran -O3.
------------
      program prova
      implicit none
      integer :: i, j, Nx, Ny
      parameter(Nx=10000,Ny=10000)
      real(8) :: A(Nx,Ny)
      do j=1,Ny
        do i=1,Nx
          A(i,j)=sin(1.d0+i+j);
        end do
      end do
      end program
------------

In an equivalent C program the loop is optimized away and the run time drops
from 10.927s to 0.001s: gcc -O3
------------
#include <math.h>
#define NX 10000
#define NY 10000
int main() {
  double A[NX][NY];
  int i, j;
  for(i = 0; i < NX; i++)
    for(j = 0; j < NY; j++)
      A[i][j] = sin(3.0+i+j);
  return 0;
}


-- 
           Summary: optimization: Loop not optimized away
           Product: gcc
           Version: 4.3.0
            Status: UNCONFIRMED
          Keywords: missed-optimization
          Severity: normal
          Priority: P3
         Component: middle-end
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: burnus at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31892