https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100056
--- Comment #4 from Luc Van Oostenryck <luc.vanoostenryck at gmail dot com> ---
(In reply to Jakub Jelinek from comment #3)
> Created attachment 50583 [details]
> gcc11-pr100056.patch
>
> Untested fix.
Mmmm, that's working fine for the cases I had but not in
more general cases. I think that the constraint on the AND
may be too tight. For example, changing things slightly to
have a smaller mask:
int or_lsl_u3(unsigned i) {
i &= 7;
return i | (i << 11);
}
still gives:
or_lsl_u3:
and w1, w0, 7
ubfiz w0, w0, 11, 3
orr w0, w0, w1
ret
while GCC8 gave the expected:
or_lsl_u3:
and w0, w0, 7
orr w0, w0, w0, lsl 11
ret
In fact, I would tend to think that the AND part should be
removed from your split pattern (some kind of zero-extension
seems to be needed to reproduce the problem but that's all).
