Here's now my third attempt to fix this PR, taking into account
the comments by Tobias and Bernhard.
> > On 10.06.21 20:52, Harald Anlauf via Fortran wrote:
> > > +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
> >
> > Is there a reason why you do not handle:
> >
> > type t
> > character(len=5) :: str1
> > character(len=:), allocatable :: str2
> > end type
> > type(t) :: x
> >
> > allocate(x%str2, source="abd")
> > if (len (x%str)) /= 1) ...
> > if (len (x%str2(1:2) /= 2) ...
> > etc.
> >
> > Namely: Search the last_ref = expr->ref->next->next ...?
> > and then check that lastref?
The mentioned search is now implemented.
Note, however, that gfc_simplify_len still won't handle neither
deferred strings nor their substrings.
I think there is nothing to simplify at compile time here. Otherwise
there would be a conflict/inconsistency with type parameter inquiry,
see F2018:9.4.5(2):
"A deferred type parameter of a pointer that is not associated or
of an unallocated allocatable variable shall not be inquired about."
> > * * *
> >
> > Slightly unrelated: I think the following does not violate
> > F2018's R916 / C923 – but is rejected, namely:
> > R916 type-param-inquiry is designator % type-param-name
> > the latter is 'len' or 'kind' for intrinsic types. And:
> > R901 designator is ...
> > or substring
> > But
> >
> > character(len=5) :: str
> > print *, str(1:3)%len
> > end
> >
> > fails with
> >
> > 2 | print *, str(1:3)%len
> > | 1
> > Error: Syntax error in PRINT statement at (1)
> >
> >
> > Assuming you don't want to handle it, can you open a new PR?
> > Thanks!
I tried to look into this, but there appear to be several unrelated
issues requiring a separate treatment. I therefore opened:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101735
> > > + 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);
> >
> > As mentioned by Bernhard, you could use HOST_WIDE_INT_PRINT_DEC.
> >
> > (It probably only matters on Windows which uses long == int = 32bit for
> > strings longer than INT_MAX.)
Done.
The updated patch regtests fine. OK?
Thanks,
Harald
Fortran - simplify length of substring with constant bounds
gcc/fortran/ChangeLog:
PR fortran/100950
* simplify.c (substring_has_constant_len): New.
(gfc_simplify_len): Handle case of substrings with constant
bounds.
gcc/testsuite/ChangeLog:
PR fortran/100950
* gfortran.dg/pr100950.f90: New test.
diff --git a/gcc/fortran/simplify.c b/gcc/fortran/simplify.c
index c27b47aa98f..8f7fcec94c8 100644
--- a/gcc/fortran/simplify.c
+++ b/gcc/fortran/simplify.c
@@ -4512,6 +4512,69 @@ gfc_simplify_leadz (gfc_expr *e)
}
+/* Check for constant length of a substring. */
+
+static bool
+substring_has_constant_len (gfc_expr *e)
+{
+ gfc_ref *ref;
+ HOST_WIDE_INT istart, iend, length;
+ bool equal_length = false;
+
+ if (e->ts.type != BT_CHARACTER || e->ts.deferred)
+ return false;
+
+ for (ref = e->ref; ref; ref = ref->next)
+ if (ref->type != REF_COMPONENT)
+ break;
+
+ if (!ref
+ || ref->type != REF_SUBSTRING
+ || !ref->u.ss.start
+ || ref->u.ss.start->expr_type != EXPR_CONSTANT
+ || !ref->u.ss.end
+ || ref->u.ss.end->expr_type != EXPR_CONSTANT
+ || !ref->u.ss.length
+ || !ref->u.ss.length->length
+ || ref->u.ss.length->length->expr_type != EXPR_CONSTANT)
+ return false;
+
+ /* Basic checks on substring starting and ending indices. */
+ if (!gfc_resolve_substring (ref, &equal_length))
+ return false;
+
+ istart = gfc_mpz_get_hwi (ref->u.ss.start->value.integer);
+ iend = gfc_mpz_get_hwi (ref->u.ss.end->value.integer);
+ length = gfc_mpz_get_hwi (ref->u.ss.length->length->value.integer);
+
+ if (istart <= iend)
+ {
+ if (istart < 1)
+ {
+ gfc_error ("Substring start index (" HOST_WIDE_INT_PRINT_DEC
+ ") at %L below 1",
+ istart, &ref->u.ss.start->where);
+ return false;
+ }
+ if (iend > length)
+ {
+ gfc_error ("Substring end index (" HOST_WIDE_INT_PRINT_DEC
+ ") at %L exceeds string length",
+ iend, &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)
{
@@ -4521,7 +4584,11 @@ gfc_simplify_len (gfc_expr *e, gfc_expr *kind)
if (k == -1)
return &gfc_bad_expr;
- if (e->expr_type == EXPR_CONSTANT)
+ if (e->ts.deferred)
+ return NULL;
+
+ if (e->expr_type == EXPR_CONSTANT
+ || 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);
diff --git a/gcc/testsuite/gfortran.dg/pr100950.f90 b/gcc/testsuite/gfortran.dg/pr100950.f90
new file mode 100644
index 00000000000..a86c8016e2e
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/pr100950.f90
@@ -0,0 +1,29 @@
+! { 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' ]
+ character(*), parameter :: t(*) = [character(len(x( :2))) :: 'a','b' ]
+ character(*), parameter :: v(*) = [character(len(x(7: ))) :: 'a','b' ]
+ type t_
+ character(len=5) :: s
+ end type t_
+ type(t_) :: q, r(1)
+ integer, parameter :: lq = len (q%s(3:4)), lr = len (r%s(3:4))
+
+ 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
+ if (len (t) /= 2) stop 8
+ if (len (v) /= 2) stop 9
+ if (lq /= 2 .or. lr /= 2) stop 10
+end
