s390.c (legitimate_reload_constant_p): Accept floating- point zero operands that fit into a single GPR.

2010-09-09  Ulrich Weigand  <Ulrich.Weigand@de.ibm.com>

	* config/s390/s390.c (legitimate_reload_constant_p): Accept floating-
	point zero operands that fit into a single GPR.
	(s390_preferred_reload_class): Ensure we only return general-purpose
	register classes.
	* config/s390/s390.md ("*mov<mode>_64dfp"): Use lghi to load
	floating-point zero operands into GPRs.
	("*mov<mode>_64"): Likewise.
	("mov<mode>"): Likewise using lhi.

From-SVN: r164076