[Bug fortran/36915] New: Unneccessary array temporary for same_array = scalar * same_array

[Bug fortran/36915] New: Unneccessary array temporary for same_array = scalar * same_array

[burnus at gcc dot gnu dot org]

Maybe this could be handled by the Middle End, once the array operations in the
ME are implemented. This would save us from checking the alias information in
the FE.

Regarding the "Middle-End Array Expressions", see:
http://www.gccsummit.org/2008/gcc-2008-proceedings.pdf, pp. 33-42.

 * * *

From: http://gcc.gnu.org/ml/fortran/2008-07/msg00166.html

PS The example from Daniel,

SUBROUTINE sub(I)
 REAL, PARAMETER :: PI = 3.1415
 REAL, DIMENSION(:), POINTER   :: I
 I = 2.0 * PI**2 * I
END SUBROUTINE

produces a temporary because the scalarizer makes no attempt to
resolve pointers, for obvious reasons.  We could add a check that the
only pointer on the rhs is the same as that on the lhs, with no
dependencies, and that there are no targets in the rhs expression.


-- 
           Summary: Unneccessary array temporary for  same_array = scalar *
                    same_array
           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: burnus at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36915

[Bug fortran/36915] Unneccessary array temporary for same_array_ptr = const * same_array_ptr

[dfranke at gcc dot gnu dot org]

------- Comment #1 from dfranke at gcc dot gnu dot org  2008-07-24 10:14 -------
Tobias, thanks for opening the PR.


-- 

dfranke at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |dfranke at gcc dot gnu dot
                   |                            |org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36915

[Bug fortran/36915] Unneccessary array temporary for same_array_ptr = const * same_array_ptr

[rguenth at gcc dot gnu dot org]

------- Comment #2 from rguenth at gcc dot gnu dot org  2008-07-24 13:03 -------
See also PR36842 which would benefit as well.


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rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |rguenth at gcc dot gnu dot
                   |                            |org
OtherBugsDependingO|                            |36842
              nThis|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36915

[Bug fortran/36915] Unneccessary array temporary for same_array_ptr = const * same_array_ptr

[burnus at gcc dot gnu dot org]

------- Comment #3 from burnus at gcc dot gnu dot org  2008-07-25 08:43 -------
See also PR 36928 (interleaved assignment, where also an unneeded temporary is
created).


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36915

[Bug fortran/36915] Unneccessary array temporary for same_array_ptr = const * same_array_ptr

[tkoenig at gcc dot gnu dot org]

------- Comment #4 from tkoenig at gcc dot gnu dot org  2008-07-28 10:38 -------
Confirmed.


-- 

tkoenig at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
   Last reconfirmed|0000-00-00 00:00:00         |2008-07-28 10:38:58
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36915

[Bug fortran/36915] Unneccessary array temporary for same_array_ptr = const * same_array_ptr

[dfranke at gcc dot gnu dot org]

------- Comment #5 from dfranke at gcc dot gnu dot org  2010-05-09 20:25 -------
This seemingly was fixed a while ago; -Warray-temporaries does not warn for
4.4.3, 4.5.1 nor current trunk. 

Relevant section of the dump is:
      while (1)
        {
          if (S.0 > D.1515) goto L.1;
          (*D.1516)[(S.0 + D.1520) * D.1523 + D.1517] = (*D.1512)[S.0 * D.1522
+ D.1513] * 1.973804473876953125e+1;
          S.0 = S.0 + 1;
        }


Closing as fixed.


-- 

dfranke at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED
   Target Milestone|---                         |4.4.3


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36915