On 1/12, Robert Dewar wrote:
>> I cannot see a reason not to use "orb $32,y" here instead of a three
>> steps read/modify/write operation. Is this only a missed optimization?
>> (in which case I will open a PR)
>
> Are you sure it is an optimization, the timing on these things is
> very subtle. What evidence do you have that there is a missed
> optimization here?
For this pattern (isolated setting of one bit in the middle of a byte at
a random memory location), this is the best code on this platform AFAIK.
As an evidence, if you mark neither variable as volatile GCC generates
with -O3 -fomit-frame-pointer:
f:
orb $16, x
orb $32, y
ret
And I sure expect that GCC didn't choose to generate worst code when
I *removed* the volatile constraint :)
