Re: [PATCH] PR fortran/100950 - ICE in output_constructor_regular_field, at varasm.c:5514

[Bernhard Reutner-Fischer <rep.dot.nop@gmail.com>]

On Wed, 9 Jun 2021 23:39:45 +0200
Harald Anlauf via Gcc-patches <gcc-patches@gcc.gnu.org> wrote:

> diff --git a/gcc/fortran/simplify.c b/gcc/fortran/simplify.c
> index c27b47aa98f..016ec259518 100644
> --- a/gcc/fortran/simplify.c
> +++ b/gcc/fortran/simplify.c
> @@ -4512,6 +4512,60 @@ gfc_simplify_leadz (gfc_expr *e)
>  }
> 
> 
> +/* Check for constant length of a substring.  */
> +
> +static bool
> +substring_has_constant_len (gfc_expr *e)
> +{
> +  ptrdiff_t istart, iend;
> +  size_t length;
> +  bool equal_length = false;
> +
> +  if (e->ts.type != BT_CHARACTER
> +      || !(e->ref && e->ref->type == REF_SUBSTRING)

iff we ever can get here with e->ref == NULL then the below will not
work too well. If so then maybe
  if (e->ts.type != BT_CHARACTER
      || ! e->ref
      || e->ref->type != REF_SUBSTRING

?

> +      || !e->ref->u.ss.start
> +      || e->ref->u.ss.start->expr_type != EXPR_CONSTANT
> +      || !e->ref->u.ss.end
> +      || e->ref->u.ss.end->expr_type != EXPR_CONSTANT
> +      || !e->ref->u.ss.length
> +      || !e->ref->u.ss.length->length
> +      || e->ref->u.ss.length->length->expr_type != EXPR_CONSTANT)
> +    return false;
> +
> +  /* Basic checks on substring starting and ending indices.  */
> +  if (!gfc_resolve_substring (e->ref, &equal_length))
> +    return false;
> +
> +  istart = gfc_mpz_get_hwi (e->ref->u.ss.start->value.integer);
> +  iend = gfc_mpz_get_hwi (e->ref->u.ss.end->value.integer);
> +  length = gfc_mpz_get_hwi (e->ref->u.ss.length->length->value.integer);
> +
> +  if (istart <= iend)
> +    {
> +      if (istart < 1)
> +	{
> +	  gfc_error ("Substring start index (%ld) at %L below 1",
> +		     (long) istart, &e->ref->u.ss.start->where);
> +	  return false;
> +	}
> +      if (iend > (ssize_t) length)
> +	{
> +	  gfc_error ("Substring end index (%ld) at %L exceeds string "
> +		     "length", (long) iend, &e->ref->u.ss.end->where);
> +	  return false;
> +	}
> +      length = iend - istart + 1;
> +    }
> +  else
> +    length = 0;
> +
> +  /* Fix substring length.  */
> +  e->value.character.length = length;
> +
> +  return true;
> +}
> +
> +
>  gfc_expr *
>  gfc_simplify_len (gfc_expr *e, gfc_expr *kind)
>  {
> @@ -4547,6 +4601,13 @@ gfc_simplify_len (gfc_expr *e, gfc_expr *kind)
>         of the unlimited polymorphic entity.  To get the _len component the last
>         _data ref needs to be stripped and a ref to the _len component added.  */
>      return gfc_get_len_component (e->symtree->n.sym->assoc->target, k);
> +  else if (substring_has_constant_len (e))
> +    {
> +      result = gfc_get_constant_expr (BT_INTEGER, k, &e->where);
> +      mpz_set_si (result->value.integer,
> +		  e->value.character.length);

I think the mpz_set_si args above fit on one line.

btw.. there's a commentary typo in add_init_expr_to_sym():
s/skeep/skip/

thanks,

> +      return range_check (result, "LEN");
> +    }
>    else
>      return NULL;
>  }
> diff --git a/gcc/testsuite/gfortran.dg/pr100950.f90 b/gcc/testsuite/gfortran.dg/pr100950.f90
> new file mode 100644
> index 00000000000..f06db45b0b4
> --- /dev/null
> +++ b/gcc/testsuite/gfortran.dg/pr100950.f90
> @@ -0,0 +1,18 @@
> +! { dg-do run }
> +! PR fortran/100950 - ICE in output_constructor_regular_field, at varasm.c:5514
> +
> +program p
> +  character(8), parameter :: u = "123"
> +  character(8)            :: x = "", s
> +  character(2)            :: w(2) = [character(len(x(3:4))) :: 'a','b' ]
> +  character(*), parameter :: y(*) = [character(len(u(3:4))) :: 'a','b' ]
> +  character(*), parameter :: z(*) = [character(len(x(3:4))) :: 'a','b' ]
> +  if (len (y) /= 2) stop 1
> +  if (len (z) /= 2) stop 2
> +  if (any (w /= y)) stop 3
> +  if (len ([character(len(u(3:4))) :: 'a','b' ]) /= 2)  stop 4
> +  if (len ([character(len(x(3:4))) :: 'a','b' ]) /= 2)  stop 5
> +  if (any ([character(len(x(3:4))) :: 'a','b' ]  /= y)) stop 6
> +  write(s,*) [character(len(x(3:4))) :: 'a','b' ]
> +  if (s /= " a b    ") stop 7
> +end