[PPC PATCH] Extend easy_altivec_constant for FP vector constants

[David Edelsohn]

>>>>> Roger Sayle writes:

Roger> Are the rs6000 bits OK for mainline, and the 4.1 branch after a while?
Roger> If approved, I'll commit them concurrently with the second patch below
Roger> which will resolve the regression PR target/27858 on the alpha.

	PR target/27158
	* config/rs6000/rs6000.c (const_vector_elt_as_int): New function to
	extract a CONST_VECTOR element and interpret it as an integer.
	(vspltis_constant): Use const_vector_elt_as_int instead of the
	macro CONST_VECTOR_ELT in order to handle FP vector modes.
	* config/rs6000/predicates.md (easy_vector_const): Consider
	floating point ALTIVEC_VECTOR_MODEs via easy_altivec_constant.

Okay by me.

Thanks, David