[Bug fortran/105381] New: [12 Regression] Memory-hog since r12-8230

[Bug fortran/105381] New: [12 Regression] Memory-hog since r12-8230

[anlauf at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105381

            Bug ID: 105381
           Summary: [12 Regression] Memory-hog since r12-8230
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: anlauf at gcc dot gnu.org
  Target Milestone: ---

The following reduced code shows an issue with an apparently infinite
compile-time loop.

MODULE m
  implicit none
  integer,  parameter :: ncrit  =  8
  integer,  parameter :: nterm  =  7
contains

  subroutine new_thin_rule (rule1)
    character(*),intent(in) ,optional :: rule1(ncrit)
    character(len=8) :: rules (ncrit,nterm)
    rules = ''
    if (present (rule1)) rules(:,1) = rule1  ! <-- compile time hog
  end subroutine new_thin_rule

end module m

This eats lots of memory...

Fails with r12-8230, works with r12-8223.

[Bug fortran/105381] [12 Regression] Memory-hog since r12-8230

[anlauf at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105381

anlauf at gcc dot gnu.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |compile-time-hog
   Target Milestone|---                         |12.0
                 CC|                            |mikael at gcc dot gnu.org

[Bug fortran/105381] [12 Regression] Memory-hog since r12-8230

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105381

Martin Liška <marxin at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|                            |2022-04-25
                 CC|                            |marxin at gcc dot gnu.org
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |NEW

[Bug fortran/105381] [12 Regression] Memory-hog since r12-8230

[mikael at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105381

--- Comment #1 from Mikael Morin <mikael at gcc dot gnu.org> ---
Draft patch.

diff --git a/gcc/fortran/trans-array.cc b/gcc/fortran/trans-array.cc
index e4b6270ccf8..e0070aa080d 100644
--- a/gcc/fortran/trans-array.cc
+++ b/gcc/fortran/trans-array.cc
@@ -3698,7 +3698,8 @@ non_negative_strides_array_p (tree expr)
   if (DECL_P (expr)
       && DECL_LANG_SPECIFIC (expr))
     if (tree orig_decl = GFC_DECL_SAVED_DESCRIPTOR (expr))
-      return non_negative_strides_array_p (orig_decl);
+      if (orig_decl != expr)
+       return non_negative_strides_array_p (orig_decl);

   return true;
 }

[Bug fortran/105381] [12 Regression] Memory-hog since r12-8230

[mikael at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105381

Mikael Morin <mikael at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
           Assignee|unassigned at gcc dot gnu.org      |mikael at gcc dot gnu.org

[Bug fortran/105381] [12 Regression] Memory-hog since r12-8230

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105381

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P1

[Bug fortran/105381] [12 Regression] Memory-hog since r12-8230

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105381

--- Comment #2 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Mikael Morin <mikael@gcc.gnu.org>:

https://gcc.gnu.org/g:3e0c9fdfd00b5b5cbff1a0bd6ac012a10fe81348

commit r12-8280-g3e0c9fdfd00b5b5cbff1a0bd6ac012a10fe81348
Author: Mikael Morin <mikael@gcc.gnu.org>
Date:   Wed Apr 27 11:36:00 2022 +0200

    fortran: Avoid infinite self-recursion [PR105381]

    Dummy array decls are local decls different from the argument decl
    accessible through GFC_DECL_SAVED_DESCRIPTOR.  If the argument decl has
    a DECL_LANG_SPECIFIC set, it is copied over to the local decl at the
    time the latter is created, so that the DECL_LANG_SPECIFIC object is
    shared between local dummy decl and argument decl, and thus the
    GFC_DECL_SAVED_DESCRIPTOR of the argument decl is the argument decl
    itself.

    The r12-8230-g7964ab6c364c410c34efe7ca2eba797d36525349 change introduced
    the non_negative_strides_array_p predicate which recurses through
    GFC_DECL_SAVED_DESCRIPTOR to avoid seeing dummy decls as purely local
    decls.  As the GFC_DECL_SAVED_DESCRIPTOR of the argument decl is itself,
    this can cause infinite recursion.

    This change adds a check to avoid infinite recursion.

            PR fortran/102043
            PR fortran/105381

    gcc/fortran/ChangeLog:

            * trans-array.cc (non_negative_strides_array_p): Inline variable
            orig_decl and merge nested if conditions.  Add condition to not
            recurse if the next argument is the same as the current.

    gcc/testsuite/ChangeLog:

            * gfortran.dg/character_array_dummy_1.f90: New test.

[Bug fortran/105381] [12 Regression] Memory-hog since r12-8230

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105381

Richard Biener <rguenth at gcc dot gnu.org> changed:

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

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
Thanks.