[Bug fortran/28005] gfortran: mathmul produces wrong result

["paul dot richard dot thomas at cea dot fr" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #2 from paul dot richard dot thomas at cea dot fr  2006-06-14 10:28 -------
Created an attachment (id=11668)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=11668&action=view)
Development fix to the PR

Tobias,

I have fixed the problem for integer_4; I do not have the time to regenerate
the library today but will do so in the next 24 hours, so that the general case
is fixed. I will submit the patch asap afterwards.

The testcase that will be submitted is attached below.

Thanks again

Paul

! { dg-do run }
! Check the fix for PR28005, in which the mechanism for dealing
! with matmul (transpose (a), b) would cause wrong results for
! matmul (a(i, 1:n), b(1:n, 1:n)).
!
! Based on the original testcase contributed by
! Tobias Burnus  <tobias.burnus@physik.fu-berlin.de>
!   
   implicit none
   integer, parameter         ::  nmax = 3
   integer                    ::  i, n = 2
   integer, dimension(nmax,nmax) ::  iB=0 , iC=1
   integer, dimension(nmax,nmax) ::  iX1=99, iX2=99, iChk
   iChk = reshape((/30,66,102,36,81,126,42,96,150/),(/3,3/))

! This would give 3, 3, 99
   iB = reshape((/1 ,3 ,0 ,2 ,5 ,0 ,0 ,0 ,0 /),(/3,3/))
   iX1(1:n,1) = matmul( iB(2,1:n),iC(1:n,1:n) )

! This would give 4, 4, 99
   ib(3,1) = 1
   iX2(1:n,1) = matmul( iB(2,1:n),iC(1:n,1:n) )

! Whereas, we should have 8, 8, 99
   if (any (iX1(1:n,1) .ne. (/8, 8, 99/))) call abort ()
   if (any (iX1 .ne. iX2)) call abort ()

! Make sure that the fix does not break transpose temporaries.
   iB = reshape((/(i, i = 1, 9)/),(/3,3/))
   ic = transpose (iB)
   iX1 = transpose (iB)
   iX1 = matmul (iX1, iC)
   iX2 = matmul (transpose (iB), iC)
   if (any (iX1 .ne. iX2)) call abort ()
   if (any (iX1 .ne. iChk)) call abort ()
end


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28005