rs6000 Add vector insert builtin support

rs6000 Add vector insert builtin support

GCC maintainers:

This patch adds support for vec_insertl and vec_inserth builtins.

The patch has been compiled and tested on

  powerpc64le-unknown-linux-gnu (Power 8 LE)
  powerpc64le-unknown-linux-gnu (Power 9 LE)

and mambo with no regression errors.

Please let me know if this patch is acceptable for the mainline branch.

Thanks.

                         Carl Love

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gcc/ChangeLog

	    2020-08-04  Carl Love  <cel@us.ibm.com>

	* config/rs6000/altivec.h (vec_insertl, vec_inserth): New defines.
	* config/rs6000/rs6000-builtin.def (VINSERTGPRBL, VINSERTGPRHL,
	VINSERTGPRWL, VINSERTGPRDL, VINSERTVPRBL, VINSERTVPRHL, VINSERTVPRWL,
	VINSERTGPRBR, VINSERTGPRHR, VINSERTGPRWR, VINSERTGPRDR, VINSERTVPRBR,
	VINSERTVPRHR, VINSERTVPRWR): New builtins.
	(INSERTL, INSERTH): New builtins.
	* config/rs6000/rs6000-call.c (P10_BUILTIN_VEC_INSERTL,
	P10_BUILTIN_VEC_INSERTH): New overloaded definitions.
	(P10_BUILTIN_VINSERTGPRBL, P10_BUILTIN_VINSERTGPRHL,
	P10_BUILTIN_VINSERTGPRWL, P10_BUILTIN_VINSERTGPRDL,
	P10_BUILTIN_VINSERTVPRBL, P10_BUILTIN_VINSERTVPRHL,
	P10_BUILTIN_VINSERTVPRWL): Add case entries.
	* config/rs6000/vsx.md (define_c_enum): Add UNSPEC_INSERTL,
	UNSPEC_INSERTR.
	(define_expand): Add vinsertvl_<mode>, vinsertvr_<mode>,
	vinsertgl_<mode>, vinsertgr_<mode>, mode is VI2.
	(define_ins): vinsertvl_internal_<mode>, vinsertvr_internal_<mode>,
	vinsertgl_internal_<mode>, vinsertgr_internal_<mode>, mode VEC_I.
	* doc/extend.texi: Add documentation for vec_insertl, vec_inserth.

gcc/testsuite/ChangeLog

	    2020-08-04  Carl Love  <cel@us.ibm.com>

	* gcc.target/powerpc/vec-insert-word-runnable.c: New test case.