Hi.
As you probably mentioned, simple folding improvement has grown to multiple
patches
and multiple iterations. Apart from that, I also noticed that we do not do the
best
for couple of cases and I would like to have a feedback if it worth to improve
or not?
$ cat /tmp/string-folding-missing.c
const char global_1[4] = {'a', 'b', 'c', 'd' };
const char global_2[6] = "abcdefghijk";
int main()
{
const char local1[] = "asdfasdfasdf";
/* Case 1 */
__builtin_memchr (global_1, 'c', 5);
/* Case 2 */
__builtin_memchr (global_2, 'c', 5);
/* Case 3 */
__builtin_memchr (local1, 'a', 5);
return 0;
}
Cases:
1) Currently, calling c_getstr (which calls string_constant) can't handle
CONSTRUCTOR. Potential
solution can be to create on demand STRING_CST, however as string_constant is
called multiple times,
it can be overkill.
2) /tmp/xxxxx.c:2:26: warning: initializer-string for array of chars is too long
const char global_2[6] = "abcdefghijk";
Here I'm not sure whether one can consider global_2 == "abcdef" (w/o trailing
zero char) or not?
If so, adding new output argument (string_length) to string_constant can be
solution.
3) Currently, ctor_for_folding return error_mark_node for local variables. I'm
wondering whether returning
DECL_INITIAL for these would be doable? Will it make any issue for LTO?
Last question is whether one can aggressively fold strcasecmp in a host
compiler? Or are there any situations
where results depends on locale?
Thanks for thoughts.
Martin
