i386: Disallow address spaces with string insns

i386: Disallow address spaces with string insns

While cmps and movs allow a segment override of the ds:esi
source, the es:edi source/destination cannot be overriden.
Simplify things in the backend for now by disallowing
segments for string insns entirely.

	* config/i386/i386.c (ix86_check_no_addr_space): New.
	(decide_alg): Add have_as parameter.
	(alg_usable_p): Likewise; disable rep algorithms if set.
	(ix86_expand_set_or_movmem): Notice if either MEM has a
	non-default address space.
	(ix86_expand_strlen): Likewise.
	* config/i386/i386.md (strmov, strset): Likewise.
	(*strmovdi_rex_1): Use ix86_check_no_addr_space.
	(*strmovsi_1, *strmovqi_1, *rep_movdi_rex64, *rep_movsi, *rep_movqi,
	*strsetdi_rex_1, *strsetsi_1, *strsethi_1, *strsetqi_1,
	*rep_stosdi_rex64, *rep_stossi, *rep_stosqi, *cmpstrnqi_nz_1,
	*cmpstrnqi_1, *strlenqi_1): Likewise.

From-SVN: r230002