https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109081
--- Comment #1 from Hongtao.liu <crazylht at gmail dot com> --- Here's what I got from wiki for the history of ABM and LZCNT. https://en.wikipedia.org/wiki/X86_Bit_manipulation_instruction_set ------quoted from wiki------- Intel and AMD use AMD's ABM flag to indicate LZCNT support (since LZCNT combined with BMI1 and BMI2 completes the expanded ABM instruction set). ----end ----- So yes, they're exact the same.
