PR target/77270
	* config/i386/i386.c (ix86_option_override_internal): Remove
	PTA_PRFCHW from entries that also have PTA_3DNOW flag.
	Enable SSE prefetch also for TARGET_PREFETCHWT1.
	Do not try to enable TARGET_PRFCHW ISA flag here.
	* config/i386/i386.md (prefetch): Enable also for TARGET_3DNOW.
	Rewrite expander function body.
	(*prefetch_3dnow): Enable for TARGET_3DNOW and TARGET_PREFETCHWT1.

From-SVN: r239626