Le 27/07/2025 à 11:37, Yuao Ma a écrit :
On 7/27/2025 5:19 PM, Mikael Morin wrote:
+gfc_charlen_type
+string_split (gfc_charlen_type stringlen, const CHARTYPE *string,
+ gfc_charlen_type setlen, const CHARTYPE *set,
+ gfc_charlen_type pos, GFC_LOGICAL_4 back)
+{
+ gfc_charlen_type i, j;
+
+ if (!back)
+ {
+ if (pos > stringlen)
+ runtime_error ("If BACK is present with the value false, the
value of "
+ "POS shall be in the range [0, LEN (STRING)]");
+
The condition doesn't check pos >= 0; I think the case pos < 0
doesn't work.
The variable pos is an unsigned type, so checking for < 0 is
unnecessary. (I was not initially aware of this, but the compiler
warning alerted me.)
Mmmh, good point. But POS is a user variable, so a signed type
originally.
Can you check the following:
integer(kind=1) :: my_pos = -1
character(len=300) :: my_str = ""
call split(my_str, " ", my_pos)
Is it rejected at runtime?
I expect the unsigned conversion to convert -1 to 255 and then the
call would be (wrongly) accepted.
Yes, it's rejected at runtime. The trick lies in how the pos is handled:
it's first converted to gfc_charlen_type (an unsigned long long). So,
even if kind=1 and the input is -1, it wraps around to a very large
positive value (specifically, ULLONG_MAX - 1). This value far exceeds
300, leading to a runtime error.
+ pos_for_call = fold_convert (gfc_charlen_type_node, pos);
Ok, according to the dump the conversion is to integer(kind=8) which is
signed. Anyway, I think it works for any sensible case.
So the case above is rejected, but now the value of pos printed is not
what the user specified.
This is what I get:
Fortran runtime error: If BACK is present with the value false, the
value of POS shall be in the range [0, LEN (STRING)], where POS =
18446744073709551615 and LEN (STRING) = 300
Another thing I noticed:
+ gfc_add_expr_to_block (&block, call);
+ gfc_add_modify (&block, pos, fold_convert (TREE_TYPE (pos), call));
You are using the call twice; this results in two calls to the function
split in the dump:
_gfortran_string_split (300, &my_str, 1, &" "[1]{lb: 1 sz: 1},
(integer(kind=8)) my_pos, 0);
my_pos = (integer(kind=1)) _gfortran_string_split (300, &my_str, 1, &"
"[1]{lb: 1 sz: 1}, (integer(kind=8)) my_pos, 0);
