PR bootstrap/51134
	* i386.c (atom_cost): Fix 32bit memset description.
	(expand_set_or_movmem_via_loop_with_iter): Output proper bounds check for epilogue loops.
	(expand_movmem_epilogue): Handle epilogues up to size 15 w/o producing byte loop.
	(decide_alg): sse_loop is not useable wthen SSE2 is disabled; when not optimizing always
	use rep movsb or lincall; do not produce word sized loops when optimizing memset for
	size (to avoid need for large constants).
	(ix86_expand_movmem): Get into sync with ix86_expand_setmem; choose unroll factors
	better; always do 128bit moves when producing SSE loops; do not produce loopy epilogue
	when size is too small.
	(promote_duplicated_reg_to_size): Do not look into desired alignments when
	doing vector expansion.
	(ix86_expand_setmem): Track better when promoted value is available; choose unroll factors
	more sanely.; output loopy epilogue only when needed.

From-SVN: r181466