On Fri, Mar 20, 2015 at 11:33:09AM +0100, Martin Liška wrote:
> @@ -30670,6 +30673,20 @@ def_builtin_const (HOST_WIDE_INT mask, const char
> *name,
> static void
> ix86_add_new_builtins (HOST_WIDE_INT isa)
> {
> + /* Last cached isa value. */
> + static HOST_WIDE_INT last_tested_isa_value = 0;
> +
> + /* We iterate through all defined builtins just if the last tested
> + values is different from ISA and just in case there is any intersection
> + between ISA value and union of all possible configurations.
> + Last condition skips iterations if ISA is changed by the change has
> + empty intersection with defined_isa_values. */
> + if ((isa & defined_isa_values) == 0 || isa == last_tested_isa_value
> + || ((isa ^ last_tested_isa_value) & defined_isa_values) == 0)
> + return;
> +
> + last_tested_isa_value = isa;
Isn't at least the isa == last_tested_isa_value test useless?
I mean, if they are equal, then (isa ^ last_tested_isa_value) is 0
and so the third test is true.
Also, given that the loop does something only for
(ix86_builtins_isa[i].isa & isa) != 0
it means once you call ix86_add_new_builtins with some particular
bit set in the isa, it doesn't make sense to try that bit again.
So, I think it would be better:
1) rename defined_isa_values bitmask to say deferred_isa_values
(as in, isa bits that might still enable any new builtins)
2) in def_builtin, don't or in the mask unconditionally, but only
in the else case - when add_builtin_function is not called
3) in ix86_add_new_builtins, don't add last_tested_isa_value at all, instead
do:
if ((isa & deferred_isa_values) == 0)
return;
deferred_isa_values &= ~isa;
That way, when you actually enable all builtins (either immediately in
def_builtin because it wasn't C/C++-like FE, or because all ISAs were
enabled from the start, or because ix86_add_new_builtins has been already
called with sufficiently full bitmask), deferred_isa_values will be 0 and
you won't do anything in the function any more.
Jakub
