https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120019
--- Comment #3 from Uroš Bizjak <ubizjak at gmail dot com> --- (In reply to Uroš Bizjak from comment #2) > Please detect support during configure time and create an operand modifier > that will output "gs " or "fs " for non-default address spaces. Then output > e.g. "%^%x1rep movsq" for "gs rep movsq" when assembler doesn't support new > form. 'v' is still free for the modifier, you can use this letter to return e.g.: "%^%v1rep movsq" where %v1 is substituted with either "gs " or "fs " for the memory operand in the non-default address space (ADDR_SPACE_SEG_GS or ADDR_SPACE_SEG_FS).
