https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63464
--- Comment #15 from Uroš Bizjak <ubizjak at gmail dot com> ---
(In reply to Jakub Jelinek from comment #14)
> So, supposedly there is something we want to match-and-simplify, perhaps
> also something we want to simplify at the RTL level, and check if
> bt+set{,n}c might not be beneficial here compared to the shift + and + xor.
Generation of "bt" is quite fragile and heavily depends on combiner to do its
job correctly. IIRC, there were some talks to introduce bit-test tree code (and
corresponding RTX ?) to enable further optimizations. Something like how bswap
is now handled throughout the compilation.
