rs6000: Add vector pdep/pext

rs6000: Add vector pdep/pext

Add support for the vpdepd and vpextd instructions that perform
vector parallel bit deposit and vector parallel bit extract.

[gcc]

2020-05-11  Kelvin Nilsen  <kelvin@gcc.gnu.org>
	    Bill Schmidt  <wschmidt@linux.ibm.com>

	* config/rs6000/altivec.h (vec_pdep): New macro implementing new
	built-in function.
	(vec_pext): Likewise.
	* config/rs6000/altivec.md (UNSPEC_VPDEPD): New constant.
	(UNSPEC_VPEXTD): Likewise.
	(vpdepd): New insn.
	(vpextd): Likewise.
	* config/rs6000/rs6000-builtin.def (__builtin_altivec_vpdepd): New
	built-in function.
	(__builtin_altivec_vpextd): Likewise.
	* config/rs6000/rs6000-call.c (builtin_function_type): Add
	handling for FUTURE_BUILTIN_VPDEPD and FUTURE_BUILTIN_VPEXTD
	cases.
	* doc/extend.texi (PowerPC Altivec Built-in Functions Available
	for a Future Architecture): Add description of vec_pdep and
	vec_pext built-in functions.

[gcc/testsuite]

2020-05-11  Kelvin Nilsen  <kelvin@gcc.gnu.org>

	* gcc.target/powerpc/vec-pdep-0.c: New.
	* gcc.target/powerpc/vec-pdep-1.c: New.
	* gcc.target/powerpc/vec-pext-0.c: New.
	* gcc.target/powerpc/vec-pext-1.c: New.