* optabs.c (emit_unop_insn): Break out to ...
	(maybe_emit_unop_insn): ... this one.
	(expand_sfix_optab): Use maybe variant.
	* optabs.h (maybe_emit_unop_insn): Declare.

	* i386.md (mov0 patterns): Enable by default.
	(FP conversion expanders): Disable expansion of code expanding
	sequences when instruction should be optimized for size.
	(single strinop patterns): Enable when optimizing for size.
	(string expanders): Disable expanding of code expanding sequences
	when optimizning instruction for size.
	* i386.c (ix86_expand_vector_move_misalign): Do code size optimization
	per BB basis.
	(ix86_fp_comparison_sahf_cost): Likewise.
	(ix86_expand_branch): Likewise.
	(ix86_expand_ashl_const): Likewise.
	(ix86_split_ashl): Likewise.
	(ix86_expand_strlen): Likewise.
	(ix86_emit_fp_unordered_jump): Likewie.

From-SVN: r138835