Hi! On Wed, Sep 13, 2017 at 06:13:50PM +0100, Kyrill Tkachov wrote: > +;; Specialized OR instruction for combiner. The AND is masking out bits > +;; not needed in the OR (doing a zero_extend). The zero_extend is not > +;; needed because we know from the subreg that the upper part of the reg > +;; is zero. > +(define_insn "*iorqi3_uxtw" > + [(set (match_operand:SI 0 "register_operand" "=r") > + (ior:SI (and:SI > + (subreg:SI (match_operand:QI 1 "register_operand" "r") 0) > + (match_operand:SI 2 "const_int_operand" "n")) > + (match_operand:SI 3 "aarch64_logical_operand" "K")))] > + "INTVAL (operands[2]) + INTVAL (operands[3]) == 255" > + "orr\\t%w0, %w1, %3" > + [(set_attr "type" "logic_imm")] > +) > > We are usually hesitant to add explicit subreg matching in the MD pattern > (though I don't remember if there's a hard rule against it). > In this case this looks like a missing simplification from combine > (simplify-rtx) so > I think adding it there would be better.
Yes, it probably belongs as a generic simplification in simplify-rtx.c; if there is a reason not to do that, it can be done in combine.c instead. Segher
