Re: [Patch, fortran] PR109451 - ICE in gfc_conv_expr_descriptor with ASSOCIATE and substrings

[Paul Richard Thomas <paul.richard.thomas@gmail.com>]

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Hi Harald,

The fix was trivial. An updated patch and testcase are attached.

Thanks

Paul

Fortran: Fix some deferred character problems in associate [PR109451]

2023-04-14  Paul Thomas  <pault@gcc.gnu.org>

gcc/fortran
PR fortran/109451
* trans-array.cc (gfc_conv_expr_descriptor): Guard expression
character length backend decl before using it. Suppress the
assignment if lhs equals rhs.
* trans-io.cc (gfc_trans_transfer): Scalarize transfer of
associate variables pointing to a variable. Add comment.
* trans-stmt.cc (trans_associate_var): Remove requirement that
the character length be deferred before assigning the value
returned by gfc_conv_expr_descriptor. Also, guard the backend
decl before testing with VAR_P.

gcc/testsuite/
PR fortran/109451
* gfortran.dg/associate_61.f90 : New test


On Thu, 13 Apr 2023 at 07:18, Paul Richard Thomas <
paul.richard.thomas@gmail.com> wrote:

> Hi Harald,
>
> That's interesting - the string length '.q' is not set for either of the
> associate blocks. I'm onto it.
>
> Thanks
>
> Paul
>
>
> On Wed, 12 Apr 2023 at 20:26, Harald Anlauf <anlauf@gmx.de> wrote:
>
>> Hi Paul,
>>
>> On 4/12/23 17:25, Paul Richard Thomas via Gcc-patches wrote:
>> > Hi All,
>> >
>> > I think that the changelog says it all. OK for mainline?
>>
>> this looks almost fine, but still fails if one directly uses the
>> dummy argument as the ASSOCIATE target, as in:
>>
>> program p
>>    implicit none
>>    character(4) :: c(2) = ["abcd","efgh"]
>>    call dcs0 (c)
>> ! call dcs0 (["abcd","efgh"])
>> contains
>>    subroutine dcs0(a)
>>      character(len=*), intent(in) :: a(:)
>>      print *, size(a),len(a)
>>      associate (q => a(:))
>>        print *, size(q),len(q)
>>      end associate
>>      associate (q => a(:)(:))
>>        print *, size(q),len(q)
>>      end associate
>>      return
>>    end subroutine dcs0
>> end
>>
>> This prints e.g.
>>
>>             2           4
>>             2           0
>>             2           0
>>
>> (sometimes I also get junk values for the character length).
>>
>> Can you please have another look?
>>
>> Thanks,
>> Harald
>>
>>
>> > Paul
>> >
>> > Fortran: Fix some deferred character problems in associate [PR109451]
>> >
>> > 2023-04-07  Paul Thomas  <pault@gcc.gnu.org>
>> >
>> > gcc/fortran
>> > PR fortran/109451
>> > * trans-array.cc (gfc_conv_expr_descriptor): Guard expression
>> > character length backend decl before using it. Suppress the
>> > assignment if lhs equals rhs.
>> > * trans-io.cc (gfc_trans_transfer): Scalarize transfer of
>> > associate variables pointing to a variable. Add comment.
>> >
>> >
>> > gcc/testsuite/
>> > PR fortran/109451
>> > * gfortran.dg/associate_61.f90 : New test
>>
>>
>
> --
> "If you can't explain it simply, you don't understand it well enough" -
> Albert Einstein
>


-- 
"If you can't explain it simply, you don't understand it well enough" -
Albert Einstein

[-- Attachment #2: pr109451.diff --]
[-- Type: text/x-patch, Size: 2928 bytes --]

diff --git a/gcc/fortran/trans-array.cc b/gcc/fortran/trans-array.cc
index e1725808033..7c0bcfe5cbb 100644
--- a/gcc/fortran/trans-array.cc
+++ b/gcc/fortran/trans-array.cc
@@ -7934,8 +7934,12 @@ gfc_conv_expr_descriptor (gfc_se *se, gfc_expr *expr)
 	  else
 	    tmp = se->string_length;
 
-	  if (expr->ts.deferred && VAR_P (expr->ts.u.cl->backend_decl))
-	    gfc_add_modify (&se->pre, expr->ts.u.cl->backend_decl, tmp);
+	  if (expr->ts.deferred && expr->ts.u.cl->backend_decl
+	      && VAR_P (expr->ts.u.cl->backend_decl))
+	    {
+	      if (expr->ts.u.cl->backend_decl != tmp)
+	        gfc_add_modify (&se->pre, expr->ts.u.cl->backend_decl, tmp);
+	    }
 	  else
 	    expr->ts.u.cl->backend_decl = tmp;
 	}
@@ -7998,7 +8002,13 @@ gfc_conv_expr_descriptor (gfc_se *se, gfc_expr *expr)
 		}
 	    }
 	}
-
+      if (expr->ts.type == BT_CHARACTER
+	  && VAR_P (TYPE_SIZE_UNIT (gfc_get_element_type (TREE_TYPE (parm)))))
+	{
+	  tree elem_len = TYPE_SIZE_UNIT (gfc_get_element_type (TREE_TYPE (parm)));
+	  gfc_add_modify (&loop.pre, elem_len,
+			  fold_convert (TREE_TYPE (elem_len),					     gfc_get_array_span (desc, expr)));
+	}
       /* Set the span field.  */
       tmp = NULL_TREE;
       if (GFC_DESCRIPTOR_TYPE_P (TREE_TYPE (desc)))
diff --git a/gcc/fortran/trans-io.cc b/gcc/fortran/trans-io.cc
index 9b54d2f0d31..67658769b9e 100644
--- a/gcc/fortran/trans-io.cc
+++ b/gcc/fortran/trans-io.cc
@@ -2620,9 +2620,13 @@ gfc_trans_transfer (gfc_code * code)
 	  gcc_assert (ref && ref->type == REF_ARRAY);
 	}
 
+      /* These expressions don't always have the dtype element length set
+	 correctly, rendering them useless for array transfer.  */
       if (expr->ts.type != BT_CLASS
 	 && expr->expr_type == EXPR_VARIABLE
 	 && ((expr->symtree->n.sym->ts.type == BT_DERIVED && expr->ts.deferred)
+	     || (expr->symtree->n.sym->assoc
+		 && expr->symtree->n.sym->assoc->variable)
 	     || gfc_expr_attr (expr).pointer))
 	goto scalarize;
 
diff --git a/gcc/fortran/trans-stmt.cc b/gcc/fortran/trans-stmt.cc
index f78875455a5..a1d8a26f64f 100644
--- a/gcc/fortran/trans-stmt.cc
+++ b/gcc/fortran/trans-stmt.cc
@@ -1930,15 +1930,13 @@ trans_associate_var (gfc_symbol *sym, gfc_wrapped_block *block)
       gfc_conv_expr_descriptor (&se, e);
 
       if (sym->ts.type == BT_CHARACTER
-	  && sym->ts.deferred
 	  && !sym->attr.select_type_temporary
+	  && sym->ts.u.cl->backend_decl
 	  && VAR_P (sym->ts.u.cl->backend_decl)
 	  && se.string_length != sym->ts.u.cl->backend_decl)
-	{
-	  gfc_add_modify (&se.pre, sym->ts.u.cl->backend_decl,
-			  fold_convert (TREE_TYPE (sym->ts.u.cl->backend_decl),
-					se.string_length));
-	}
+	gfc_add_modify (&se.pre, sym->ts.u.cl->backend_decl,
+			fold_convert (TREE_TYPE (sym->ts.u.cl->backend_decl),
+				      se.string_length));
 
       /* If we didn't already do the pointer assignment, set associate-name
 	 descriptor to the one generated for the temporary.  */

[-- Attachment #3: pr109451.f90 --]
[-- Type: text/x-fortran, Size: 1379 bytes --]

! { dg-do run }
! Test fixes for PR109451
! Contributed by Harald Anlauf  <anlauf@gcc.gnu.org>
!
program p
   implicit none
   character(4) :: c(2) = ["abcd","efgh"]
   call dcs3 (c)
   call dcs0 (c)
contains
  subroutine dcs3 (a)
    character(len=*), intent(in)  :: a(:)
    character(:),     allocatable :: b(:)
    b = a(:)
    call test (b, a, 1)
    associate (q => b(:))    ! no ICE but print repeated first element
      call test (q, a, 2)
      print *, q
      q = q(:)(2:3)
    end associate
    call test (b, ["bc  ","fg  "], 4)
    b = a(:)
    associate (q => b(:)(:)) ! ICE
      call test (q, a, 3)
      associate (r => q(:)(1:3))
        call test (r, a(:)(1:3), 5)
      end associate
    end associate
    associate (q => b(:)(2:3))
      call test (q, a(:)(2:3), 6)
    end associate
  end subroutine dcs3

! The associate vars in dsc0 had string length not set
  subroutine dcs0 (a)
    character(len=*), intent(in) :: a(:)
    associate (q => a)
      call test (q, a, 7)
    end associate
    associate (q => a(:))
      call test (q, a, 8)
    end associate
    associate (q => a(:)(:))
      call test (q, a, 9)
    end associate
  end subroutine dcs0

  subroutine test (x, y, i)
    character(len=*), intent(in) :: x(:), y(:)
    integer, intent(in) :: i
    if (any (x .ne. y)) stop i
  end subroutine test
end program p
! { dg-output " abcdefgh" }