[Bug tree-optimization/34265] Missed optimizations

["dominiq at lps dot ens dot fr" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #27 from dominiq at lps dot ens dot fr  2007-12-03 14:32 -------
I have had a look at the failure of gfortran.dg/array_1.f90 with patch #5. The
following reduced code gives the same failure:

! { dg-do run }
! PR 15553 : the array used to be filled with garbage
! this problem disappeared between 2004-05-20 and 2004-09-15
program arrpack
  implicit none

  double precision x(10,10), tmp(6,5)
  integer i, j

  x = -1
  do i=1,6
     do j=1,5
        x(i,j) = i+j*10
     end do
  end do
  tmp(:,:) = x(1:6, 1:5)
  print '(6F8.2)', tmp

end program arrpack

With -O3 and patch #5, the output is

   11.00   12.00   13.00   14.00   15.00   16.00
   -1.00   -1.00   -1.00   -1.00   21.00   22.00
   23.00   24.00   25.00   26.00   -1.00   -1.00
   -1.00   -1.00   31.00   32.00   33.00   34.00
   35.00   36.00   -1.00   -1.00   -1.00   -1.00

instead of

   11.00   12.00   13.00   14.00   15.00   16.00
   21.00   22.00   23.00   24.00   25.00   26.00
   31.00   32.00   33.00   34.00   35.00   36.00
   41.00   42.00   43.00   44.00   45.00   46.00
   51.00   52.00   53.00   54.00   55.00   56.00

I am amaze that it is the only failure of this kind for the several 1000 tests
I have passed!

I'll attach the the results of -fdump-tree-optimize for with and without patch
#5.

I have also looked at the gcc failures. Most of them are missed vectorizations
or new ones. So this is already reported. Is *.[0-9][0-9][0-9]t.vect supposed
to exist if the vectorization is missed? If yes, this explaina few failures.
Concerning the failures with *.[0-9][0-9][0-9]t.cunroll, I see *cunroll1/2, but
no cunroll.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34265