[Bug middle-end/118012] [avr] Expensive code (bit extract + extend + neg + and) instead of bit test

[gjl at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118012

--- Comment #1 from Georg-Johann Lay <gjl at gcc dot gnu.org> ---
(In reply to Georg-Johann Lay from comment #0)
> For comparison, here is the code when the test is for bit 1 instead of bit 0:
> 
>         if (b & 1)
          ^^^^^^^^^^
This should be "if (b & 2)"

>             c ^= a;
> 
> 	sbrs r20,1	 ;  75	[c=4 l=2]  *sbrx_branchhi
> 	rjmp .L3	
> 	eor r24,r18	 ;  73	[c=4 l=1]  *xorqi3
> 	eor r25,r19	 ;  74	[c=4 l=1]  *xorqi3