Committed to trunk as rev. 268726. after adding a comment that a check
for negative substring length is already present. The updated version
is attached.
Thanks for the review. Will not backport unless requested.
Harald
On 02/08/19 21:36, Harald Anlauf wrote:
> The attached patch attempts a substring length simplification
> so that more complex expressions are handled in initialization
> expressions. Thanks to Thomas König for the suggestion.
>
> Regtested on x86_64-pc-linux-gnu.
>
> (The PR still has other wrong-code issue to be addressed separately.)
>
> OK for trunk? And for backports to 8/7?
>
> Thanks,
> Harald
>
>
> 2019-02-08 Harald Anlauf <anl...@gmx.de>
>
> PR fortran/89077
> * resolve.c (gfc_resolve_substring_charlen): Check substring
> length for constantness prior to general calculation of length.
>
> 2019-02-08 Harald Anlauf <anl...@gmx.de>
>
> PR fortran/89077
> * gfortran.dg/substr_simplify.f90: New test.
>
--
Harald Anlauf
Dieburger Str. 17
60386 Frankfurt
Tel.: (069) 4014 8318
Index: gcc/fortran/resolve.c
===================================================================
--- gcc/fortran/resolve.c (revision 268725)
+++ gcc/fortran/resolve.c (working copy)
@@ -4965,6 +4965,7 @@
gfc_ref *char_ref;
gfc_expr *start, *end;
gfc_typespec *ts = NULL;
+ mpz_t diff;
for (char_ref = e->ref; char_ref; char_ref = char_ref->next)
{
@@ -5016,12 +5017,26 @@
return;
}
- /* Length = (end - start + 1). */
- e->ts.u.cl->length = gfc_subtract (end, start);
- e->ts.u.cl->length = gfc_add (e->ts.u.cl->length,
- gfc_get_int_expr (gfc_charlen_int_kind,
- NULL, 1));
+ /* Length = (end - start + 1).
+ Check first whether it has a constant length. */
+ if (gfc_dep_difference (end, start, &diff))
+ {
+ gfc_expr *len = gfc_get_constant_expr (BT_INTEGER, gfc_charlen_int_kind,
+ &e->where);
+ mpz_add_ui (len->value.integer, diff, 1);
+ mpz_clear (diff);
+ e->ts.u.cl->length = len;
+ /* The check for length < 0 is handled below */
+ }
+ else
+ {
+ e->ts.u.cl->length = gfc_subtract (end, start);
+ e->ts.u.cl->length = gfc_add (e->ts.u.cl->length,
+ gfc_get_int_expr (gfc_charlen_int_kind,
+ NULL, 1));
+ }
+
/* F2008, 6.4.1: Both the starting point and the ending point shall
be within the range 1, 2, ..., n unless the starting point exceeds
the ending point, in which case the substring has length zero. */
