[Bug fortran/36928] array temporary for interleaving assignment with non-constant start values

[Bug fortran/36928] array temporary for interleaving assignment with non-constant start values

[tkoenig at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36928

Thomas Koenig <tkoenig at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |FIXED

--- Comment #15 from Thomas Koenig <tkoenig at gcc dot gnu.org> ---
Fixed with

Author: tkoenig
Date: Thu Mar 28 21:30:26 2013
New Revision: 197217

URL: http://gcc.gnu.org/viewcvs?rev=197217&root=gcc&view=rev
Log:
2013-03-28  Thomas Koenig  <tkoenig@gcc.gnu.org>

    PR fortran/45159
    * gfortran.h (gfc_dep_difference):  Add prototype.
    * dependency.c (discard_nops):  New function.
    (gfc_dep_difference):  New function.
    (check_section_vs_section):  Use gfc_dep_difference
    to calculate the difference of starting indices.
    * trans-expr.c (gfc_conv_substring):  Use
    gfc_dep_difference to calculate the length of
    substrings where possible.

2013-03-28  Thomas Koenig  <tkoenig@gcc.gnu.org>

    PR fortran/45159
    * gfortran.dg/string_length_2.f90:  New test.
    * gfortran.dg/dependency_41.f90:  New test.


Added:
    trunk/gcc/testsuite/gfortran.dg/dependency_41.f90
    trunk/gcc/testsuite/gfortran.dg/string_length_2.f90
Modified:
    trunk/gcc/fortran/ChangeLog
    trunk/gcc/fortran/dependency.c
    trunk/gcc/fortran/gfortran.h
    trunk/gcc/fortran/trans-expr.c
    trunk/gcc/testsuite/ChangeLog

[Bug fortran/36928] New: array temporary for interleaving assignment

[tkoenig at gcc dot gnu dot org]

The temporary is not needed in this case.

$ cat foo.f90
program main
  real, dimension(10) :: a
  read (10) a
  a(2:10:2) = a (1:9:2)
end program main
$ gfortran -Warray-temporaries foo.f90
foo.f90:4.14:

  a(2:10:2) = a (1:9:2)
             1
Warning: Creating array temporary at (1)


-- 
           Summary: array temporary for interleaving assignment
           Product: gcc
           Version: 4.4.0
            Status: UNCONFIRMED
          Keywords: missed-optimization
          Severity: enhancement
          Priority: P3
         Component: fortran
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: tkoenig at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36928

[Bug fortran/36928] array temporary for interleaving assignment with non-constant start values

[tkoenig at gcc dot gnu dot org]

------- Comment #14 from tkoenig at gcc dot gnu dot org  2010-06-01 05:30 -------
Fixed for the constant case.

Still to do, but much harder: A case like

a(n,m,2) = a(n+1,m,2).

Unassigning myself for now.


-- 

tkoenig at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|tkoenig at gcc dot gnu dot  |unassigned at gcc dot gnu
                   |org                         |dot org
             Status|ASSIGNED                    |NEW
            Summary|array temporary for         |array temporary for
                   |interleaving assignment     |interleaving assignment with
                   |                            |non-constant start values


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36928