[Patch, fortran] PR/97045 A wrong column is selected when addressing individual elements of unlimited polymorphic dummy argument

[Patch, fortran] PR/97045 A wrong column is selected when addressing individual elements of unlimited polymorphic dummy argument

[dhumieres.dominique]

Hi Paull,

Your patch works as expected and AFAICT it also fixes the ICEs for the 
tests in PR79426.

Thanks for the patch.

Dominique

Re: [Patch, fortran] PR/97045 A wrong column is selected when addressing individual elements of unlimited polymorphic dummy argument

[Thomas Koenig]

Hi Paul,


> Regtests on FC31/x86_64 - OK for master?

OK.

You're quite right that trans-* is chock full of special-case
handling (which I also found out, again, working together
with Nicolas on the shared memory coarrays).

Cleaning that up would be a worthwile job, although probably
quite big :-(

Best regards

	Thomas

[Patch, fortran] PR/97045 A wrong column is selected when addressing individual elements of unlimited polymorphic dummy argument

[Paul Richard Thomas]

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Hi All,

The original testcase turned out to be relatively easy to fix - the chunks
in trans-expr.c and trans-stmt.c do this. However, I tested character
actual arguments to 'write_array' in the testcase and found that the _len
component of the unlimited polymorphic dummy was not being used for the
selector and so the payloads were being treated as if they were
character(len = 1). The fix for this part of the problem further
complicates the building of array references. It looks to me as if
rationalizing this part of the trans-* part of gfortran is quite a
significant TODO, since it is now little more than bandaid on sticking
plaster! I will flag this up in a new PR.

Regtests on FC31/x86_64 - OK for master?

Paul

This patch fixes PR97045 - unlimited polymorphic array element selectors.

2020-25-09  Paul Thomas  <pault@gcc.gnu.org>

gcc/fortran
PR fortran/97045
* trans-array.c (gfc_conv_array_ref): Make sure that the class
decl is passed to build_array_ref in the case of unlimited
polymorphic entities.
* trans-expr.c (gfc_conv_derived_to_class): Ensure that array
refs do not preceed the _len component. Free the _len expr.
* trans-stmt.c (trans_associate_var): Reset 'need_len_assign'
for polymorphic scalars.
* trans.c (gfc_build_array_ref): When the vptr size is used for
span, multiply by the _len field of unlimited polymorphic
entities, when non-zero.

gcc/testsuite/
PR fortran/97045
* gfortran.dg/select_type_50.f90 : New test.

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diff --git a/gcc/fortran/trans-array.c b/gcc/fortran/trans-array.c
index 6566c47d4ae..998d4d4ed9b 100644
--- a/gcc/fortran/trans-array.c
+++ b/gcc/fortran/trans-array.c
@@ -3787,7 +3787,20 @@ gfc_conv_array_ref (gfc_se * se, gfc_array_ref * ar, gfc_expr *expr,
 	decl = sym->backend_decl;
     }
   else if (sym->ts.type == BT_CLASS)
-    decl = NULL_TREE;
+    {
+      if (UNLIMITED_POLY (sym))
+	{
+	  gfc_expr *class_expr = gfc_find_and_cut_at_last_class_ref (expr);
+	  gfc_init_se (&tmpse, NULL);
+	  gfc_conv_expr (&tmpse, class_expr);
+	  if (!se->class_vptr)
+	    se->class_vptr = gfc_class_vptr_get (tmpse.expr);
+	  gfc_free_expr (class_expr);
+	  decl = tmpse.expr;
+	}
+      else
+	decl = NULL_TREE;
+    }
 
   se->expr = build_array_ref (se->expr, offset, decl, se->class_vptr);
 }
diff --git a/gcc/fortran/trans-expr.c b/gcc/fortran/trans-expr.c
index a690839f591..2c31ec9bf01 100644
--- a/gcc/fortran/trans-expr.c
+++ b/gcc/fortran/trans-expr.c
@@ -728,7 +728,7 @@ gfc_conv_derived_to_class (gfc_se *parmse, gfc_expr *e,
 	  gfc_expr *len;
 	  gfc_se se;
 
-	  len = gfc_copy_expr (e);
+	  len = gfc_find_and_cut_at_last_class_ref (e);
 	  gfc_add_len_component (len);
 	  gfc_init_se (&se, NULL);
 	  gfc_conv_expr (&se, len);
@@ -739,6 +739,7 @@ gfc_conv_derived_to_class (gfc_se *parmse, gfc_expr *e,
 					    integer_zero_node));
 	  else
 	    tmp = se.expr;
+	  gfc_free_expr (len);
 	}
       else
 	tmp = integer_zero_node;
diff --git a/gcc/fortran/trans-stmt.c b/gcc/fortran/trans-stmt.c
index 389fec7227e..adc6b8fefb5 100644
--- a/gcc/fortran/trans-stmt.c
+++ b/gcc/fortran/trans-stmt.c
@@ -2091,6 +2091,7 @@ trans_associate_var (gfc_symbol *sym, gfc_wrapped_block *block)
 	  /* Obtain a temporary class container for the result.  */
 	  gfc_conv_derived_to_class (&se, e, sym->ts, tmp, false, false);
 	  se.expr = build_fold_indirect_ref_loc (input_location, se.expr);
+	  need_len_assign = false;
 	}
       else
 	{
diff --git a/gcc/fortran/trans.c b/gcc/fortran/trans.c
index ed054261452..8caa625ab0e 100644
--- a/gcc/fortran/trans.c
+++ b/gcc/fortran/trans.c
@@ -429,7 +429,28 @@ gfc_build_array_ref (tree base, tree offset, tree decl, tree vptr)
   /* If decl or vptr are non-null, pointer arithmetic for the array reference
      is likely. Generate the 'span' for the array reference.  */
   if (vptr)
-    span = gfc_vptr_size_get (vptr);
+    {
+      span = gfc_vptr_size_get (vptr);
+
+      /* Check if this is an unlimited polymorphic object carrying a character
+	 payload. In this case, the 'len' field is non-zero.  */
+      if (decl && GFC_CLASS_TYPE_P (TREE_TYPE (decl)))
+	{
+	  tmp = gfc_class_len_or_zero_get (decl);
+	  if (!integer_zerop (tmp))
+	    {
+	      tree cond;
+	      tree stype = TREE_TYPE (span);
+	      tmp = fold_convert (stype, tmp);
+	      cond = fold_build2_loc (input_location, EQ_EXPR,
+				      logical_type_node, tmp,
+				      build_int_cst (stype, 0));
+	      tmp = fold_build2 (MULT_EXPR, stype, span, tmp);
+	      span = fold_build3_loc (input_location, COND_EXPR, stype,
+				      cond, span, tmp);
+	    }
+	}
+    }
   else if (decl)
     span = get_array_span (type, decl);
 

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! { dg-do run }
!
! Test the fix for PR97045. The report was for the INTEGER version. Testing
! revealed a further bug with the character versions.
!
! Contributed by Igor Gayday  <igor.gayday@mu.edu>
!
program test_prg
  implicit none
  integer :: i
  integer, allocatable :: arr(:, :)
  character(kind = 1, len = 2), allocatable :: chr(:, :)
  character(kind = 4, len = 2), allocatable :: chr4(:, :)

  arr = reshape ([(i, i = 1, 9)], [3, 3])
  do i = 1, 3
    call write_array(arr(1:2, i), i)
  end do

  chr = reshape([(char (i)//char (i+1), i = 65, 83, 2)], [3, 3])
  do i = 1, 3
    call write_array (chr(1:2, i), i)
  end do

  chr4 = reshape([(char (i, kind = 4)//char (i+1, kind = 4), i = 65, 83, 2)], &
                 [3, 3])
  do i = 1, 3
    call write_array (chr4(1:2, i), i)
  end do

contains

  subroutine write_array(array, j)
    class(*), intent(in) :: array(:)
    integer :: i = 2
    integer :: j, k

    select type (elem => array(i))
      type is (integer)
        k = 3*(j-1)+i
        if (elem .ne. k) stop 1
      type is (character(kind = 1, len = *))
        k = 63 + 2*(3*(j-1)+i)
        if (elem .ne. char (k)//char (k+1)) print *, elem, "   ", char (k)//char (k+1)
      type is (character(kind = 4, len = *))
        k = 63 + 2*(3*(j-1)+i)
        if (elem .ne. char (k, kind = 4)//char (k+1, kind = 4)) stop 3
    end select

  end subroutine

end program