* i386.c (x86_promote_QImode): Set for Athlon
	(x86_fast_prefix): New global variable.
	(x86_arch_always_fancy_math_387): Fix formating.
	* i386.h (x86_fast_prefix): Declare
	(TARGET_FAST_PREFIX): define.
	* i386.md (and to strict_low_part, HI to SI
	promoting splitter): Use new macro.

	* i386.h (RTX_COSTS): float_extend is not for free for SSE.

From-SVN: r54521