https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96633
Martin Liška <marxin at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Last reconfirmed| |2020-08-17
Status|UNCONFIRMED |NEW
Keywords| |missed-optimization
CC| |marxin at gcc dot gnu.org
Ever confirmed|0 |1
--- Comment #1 from Martin Liška <marxin at gcc dot gnu.org> ---
Nice trick!
Generally speaking about the optimization (for longer types), it can be tricky
as:
shr $6, %ecx
can be bigger than 64 and so
shrq %cl, %rax
can result in undefined behavior as 1 << X, where X > 64.
