https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109907
--- Comment #6 from Georg-Johann Lay <gjl at gcc dot gnu.org> ---
(In reply to Andrew Pinski from comment #4)
> For cset_32bit30_not with some patches which I will be posting, I get:
> bst r25,6 ; 23 [c=4 l=3] *extzv/4
> clr r24
> bld r24,0
> ldi r25,lo8(1) ; 24 [c=4 l=1] movqi_insn/1
> eor r24,r25 ; 25 [c=4 l=1] *xorqi3
> /* epilogue start */
> ret ; 28 [c=0 l=1] return
>
> Which is better than what was there before.
Quite impressive improvement. Maybe the last step can be achieved with a
combiner pattern that combines extzv with a bit flip.
One problem is usually that there is no canonical form (sometimes zero_extract,
sometimes shift+and, sometimes with subregs for extraction or paradoxical
subregs for wider types, different behaviour for MSB, etc.).
avr's extzv currently reads
(define_expand "extzv"
[(set (match_operand:QI 0 "register_operand")
(zero_extract:QI (match_operand:QI 1 "register_operand")
(match_operand:QI 2 "const1_operand")
(match_operand:QI 3 "const_0_to_7_operand")))])
Maybe QI for op1 is not optimal, but it's not possible to use mode iterator
because there's only one gen_extzv. Dunno if VOIDmode would help or is sane.
> The first one I suspect load_extend_op for SImode returning SIGN_EXTEND for
> avr.
It's not implemented for avr, thus UNKNOWN as of defaults.h.
