https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99582
--- Comment #4 from cqwrteur <unlvsur at live dot com> --- (In reply to Alexander Monakov from comment #3) > RCL and RCR are supported via microcode sequencer on Intel and involve many > (9) uops on modern AMD, so they are quite slow in comparison to simple > shifts/rotates. Would library developers still want to use them despite the > poor performance? Equivalent code with "classic" shifts should be more > efficient. > > https://uops.info/html-instr/RCL_R64_CL.html here they want is to get the carry flag from rcl/rcr
