[Bug fortran/100656] New: ICE in gfc_conv_expr_present, at fortran/trans-expr.c:1934

[Bug fortran/100656] New: ICE in gfc_conv_expr_present, at fortran/trans-expr.c:1934

[gscfq@t-online.de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100656

            Bug ID: 100656
           Summary: ICE in gfc_conv_expr_present, at
                    fortran/trans-expr.c:1934
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: gscfq@t-online.de
  Target Milestone: ---

Affects versions down to at least r5 :
(with option -fcheck=all or -fcheck=bounds)


$ cat z1.f90
subroutine s(x)
   character(:), allocatable, optional :: x(:)
   if ( present(x) ) then
      if ( allocated(x) ) then
         x = 'a' // x // 'e'
      end if
   end if
end


$ gfortran-12-20210516 -c z1.f90 -fcheck=all
z1.f90:5:28:

    5 |          x = 'a' // x // 'e'
      |                            1
internal compiler error: in gfc_conv_expr_present, at fortran/trans-expr.c:1934
0x767b80 gfc_conv_expr_present(gfc_symbol*, bool)
        ../../gcc/fortran/trans-expr.c:1934
0x745114 gfc_conv_ss_startstride(gfc_loopinfo*)
        ../../gcc/fortran/trans-array.c:4723
0x77b991 gfc_trans_assignment_1
        ../../gcc/fortran/trans-expr.c:11218
0x73dcb7 trans_code
        ../../gcc/fortran/trans.c:1932
0x7aa2f5 gfc_trans_if_1
        ../../gcc/fortran/trans-stmt.c:1475
0x7b1e8a gfc_trans_if(gfc_code*)
        ../../gcc/fortran/trans-stmt.c:1507
0x73ddd7 trans_code
        ../../gcc/fortran/trans.c:2020
0x7aa2f5 gfc_trans_if_1
        ../../gcc/fortran/trans-stmt.c:1475
0x7b1e8a gfc_trans_if(gfc_code*)
        ../../gcc/fortran/trans-stmt.c:1507
0x73ddd7 trans_code
        ../../gcc/fortran/trans.c:2020
0x764314 gfc_generate_function_code(gfc_namespace*)
        ../../gcc/fortran/trans-decl.c:6885
0x6eac86 translate_all_program_units
        ../../gcc/fortran/parse.c:6370
0x6eac86 gfc_parse_file()
        ../../gcc/fortran/parse.c:6639
0x736f7f gfc_be_parse_file
        ../../gcc/fortran/f95-lang.c:212

[Bug fortran/100656] ICE in gfc_conv_expr_present, at fortran/trans-expr.c:1934

[anlauf at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100656

anlauf at gcc dot gnu.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|                            |2021-05-18
             Status|UNCONFIRMED                 |NEW
     Ever confirmed|0                           |1

--- Comment #1 from anlauf at gcc dot gnu.org ---
Confirmed.

[Bug fortran/100656] ICE in gfc_conv_expr_present, at fortran/trans-expr.c:1934

[anlauf at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100656

--- Comment #2 from anlauf at gcc dot gnu.org ---
Using a temporary may help:

subroutine s(x)
  character(:), allocatable, optional :: x(:)
  character(:), allocatable           :: y(:)
  if ( present(x) ) then
     if ( allocated(x) ) then
        y = 'a' // x // 'e'
        x = y
     end if
  end if
end

This does not ICE.

[Bug fortran/100656] ICE in gfc_conv_expr_present, at fortran/trans-expr.c:1934

[anlauf at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100656

--- Comment #3 from anlauf at gcc dot gnu.org ---
The following patch seems to fix the issue:

diff --git a/gcc/fortran/trans-array.c b/gcc/fortran/trans-array.c
index 6d38ea78273..7eeef554c0f 100644
--- a/gcc/fortran/trans-array.c
+++ b/gcc/fortran/trans-array.c
@@ -4718,8 +4718,9 @@ done:

          /* For optional arguments, only check bounds if the argument is
             present.  */
-         if (expr->symtree->n.sym->attr.optional
-             || expr->symtree->n.sym->attr.not_always_present)
+         if ((expr->symtree->n.sym->attr.optional
+              || expr->symtree->n.sym->attr.not_always_present)
+             && expr->symtree->n.sym->attr.dummy)
            tmp = build3_v (COND_EXPR,
                            gfc_conv_expr_present (expr->symtree->n.sym),
                            tmp, build_empty_stmt (input_location));

If I understand the code correctly, the issue arises since we try to generate
runtime checks for a compiler generated temporary that is not a dummy, thus
hitting the assert in gfc_conv_expr_present.

[Bug fortran/100656] ICE in gfc_conv_expr_present, at fortran/trans-expr.c:1934

[anlauf at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100656

anlauf at gcc dot gnu.org changed:

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

--- Comment #4 from anlauf at gcc dot gnu.org ---
Patch: https://gcc.gnu.org/pipermail/fortran/2021-May/056088.html

[Bug fortran/100656] ICE in gfc_conv_expr_present, at fortran/trans-expr.c:1934

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100656

--- Comment #5 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Harald Anlauf <anlauf@gcc.gnu.org>:

https://gcc.gnu.org/g:9d3a953ec4d2695e9a6bfa5f22655e2aea47a973

commit r12-1090-g9d3a953ec4d2695e9a6bfa5f22655e2aea47a973
Author: Harald Anlauf <anlauf@gmx.de>
Date:   Thu May 27 13:55:11 2021 +0200

    PR fortran/100656 - prevent ICE in gfc_conv_expr_present

    gcc/fortran/ChangeLog:

            PR fortran/100656
            * trans-array.c (gfc_conv_ss_startstride): Do not call check for
            presence of a dummy argument when a symbol actually refers to a
            non-dummy.

    gcc/testsuite/ChangeLog:

            PR fortran/100656
            * gfortran.dg/bounds_check_22.f90: New test.

[Bug fortran/100656] ICE in gfc_conv_expr_present, at fortran/trans-expr.c:1934

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100656

--- Comment #6 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-11 branch has been updated by Harald Anlauf
<anlauf@gcc.gnu.org>:

https://gcc.gnu.org/g:1cb4a0db82c51c742961a350c9c7a45ba1fe8475

commit r11-8479-g1cb4a0db82c51c742961a350c9c7a45ba1fe8475
Author: Harald Anlauf <anlauf@gmx.de>
Date:   Thu May 27 13:55:11 2021 +0200

    PR fortran/100656 - prevent ICE in gfc_conv_expr_present

    gcc/fortran/ChangeLog:

            PR fortran/100656
            * trans-array.c (gfc_conv_ss_startstride): Do not call check for
            presence of a dummy argument when a symbol actually refers to a
            non-dummy.

    gcc/testsuite/ChangeLog:

            PR fortran/100656
            * gfortran.dg/bounds_check_22.f90: New test.

    (cherry picked from commit 9d3a953ec4d2695e9a6bfa5f22655e2aea47a973)

[Bug fortran/100656] ICE in gfc_conv_expr_present, at fortran/trans-expr.c:1934

[anlauf at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100656

anlauf at gcc dot gnu.org changed:

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

--- Comment #7 from anlauf at gcc dot gnu.org ---
Fixed on mainline for gcc-12, and on 11-branch.

Since this is not a regression, not backporting further for now,
although this would be possible.

Thanks for the report!

[Bug fortran/100656] ICE in gfc_conv_expr_present, at fortran/trans-expr.c:1934

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100656

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |11.3