https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63464
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Last reconfirmed| |2014-10-06
CC| |jakub at gcc dot gnu.org,
| |rguenth at gcc dot gnu.org,
| |steven at gcc dot gnu.org
Ever confirmed|0 |1
--- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
We have this optimization implemented for switches, if you compile
char*f3(char*s){
do
{
switch (*s)
{
case ' ':
case ',':
case '\r':
case '\n':
++s;
continue;
default:
return s;
}
}
while (1);
}
then it will do the bit test, see r189173 (and various follow-up fixes for
that).
Now, we can argue whether in this case it is beneficial to perform the
MINUS_EXPR or if maxval is small enough (e.g. when maxval is smaller than
BITS_PER_WORD), just assume minval is 0.
And then the question is, if we should teach reassoc range optimizations to
reuse emit_case_bit_tests, or convert such tests into a GIMPLE_SWITCH and
expand as such.
Richard/Steven, thoughts about this?
