i386.md (isa): Add x64 and nox64.

i386.md (isa): Add x64 and nox64.

	* config/i386/i386.md (isa): Add x64 and nox64.
	(enabled): Define x64 for TARGET_64BIT and nox64 for !TARGET_64BIT.
	(*pushtf): Enable *roF alternative for x64 isa only.
	(*pushxf): Merge with *pushxf_nointeger.  Use Yx*r constraint. Set
	mode attribute of integer alternatives to DImode for TARGET_64BIT.
	(*pushdf): Merge with *pushdf_rex64.  Use x64 and nox64 isa attributes.
	(*movtf_internal): Merge from *movtf_internal_rex64 and
	*movtf_internal_sse.  Use x64 and nox64 isa attributes.
	(*movxf_internal): Merge with *movxf_internal_rex64.  Use x64 and
	nox64 isa attributes.
	(*movdf_internal): Merge with *movdf_internal_rex64.  Use x64 and
	nox64 isa attributes.
	* config/i386/constraints.md (Yd): Do not set for TARGET_64BIT.

From-SVN: r196757