https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90827
--- Comment #2 from leimaohui <leimaohui at cn dot fujitsu.com> --- (In reply to Andrew Pinski from comment #1) > >"rev" is an alias of "rev64". > > It is the other way around. rev64 is an optional alias to rev (for > intereger registers). rev only takes integer registers. rev64 takes both > vector and integer registers (though it is optional in ARMv8.0-a and > ARMv8.1-a modes that it does the integer registers). > > By the way the assembler is not part of GCC but rather part of GNU binutils > project. I got it, thank you!