[Bug target/46091] missed optimization: x86 bt/btc/bts instructions

[a...@cloudius-systems.com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=46091

--- Comment #6 from Avi Kivity <a...@cloudius-systems.com> ---
I believe bts/btc/btr can do more - they also calculate the word offset when
addressing memory, see first comment.