[Bug rtl-optimization/71336] Suboptimal x86 code generated for "(a & 1) ? (CST1 + CST2) : CST1"

[pinskia at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71336

--- Comment #6 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Sorry this one is more correct
Something like (very much pesdu code):
(simplify
 (cond (eq (bit_and@0 @1 int_pow2p@2) integer_zerop) INTEGET_CST@3
INTEGER_CST@4)
 (switch
  (if (@3 u> @4 && exact_pow2(@3 - @4))
   (convert (plus (mult (rshift @0:typeu @2) (minus @3:typeu @4:typeu))
@4:typeu)))
  (if (@4 u> @3 && exact_pow2(@4 - @3))
   (convert (minus (mult (rshift @0:typeu @2) (minus @4:typeu @3:typeu))
@3:typeu))
 ))

The mult could be changed to lshift to be more correct.