gas/

gas/
	* config/tc-i386.c (parse_insn): Don't complain about REP prefix
	when the template has opcode_modifier.repprefixok set.
	* NEWS: Mention the change.

gas/testsuite/
	* gas/i386/rep-bsf.d: New file.
	* gas/i386/rep-bsf.s: New file.
	* gas/i386/i386.exp: Add the new test.

opcodes/
	* i386-opc.h (RepPrefixOk): New enum constant.
	(i386_opcode_modifier): New bitfield 'repprefixok'.
	* i386-gen.c (opcode_modifiers): Add RepPrefixOk.
	* i386-opc.tbl: Add RepPrefixOk to bsf, bsr, and to all
	instructions that have IsString.
	* i386-tbl.h: Regenerate.