[AArch64][SVE] Utilize ASRD instruction for division and remainder

[AArch64][SVE] Utilize ASRD instruction for division and remainder

2019-09-30  Yuliang Wang  <yuliang.wang@arm.com>

gcc/
	* config/aarch64/aarch64-sve.md (sdiv_pow2<mode>3):
	New pattern for ASRD.
	* config/aarch64/iterators.md (UNSPEC_ASRD): New unspec.
	* internal-fn.def (IFN_DIV_POW2): New internal function.
	* optabs.def (sdiv_pow2_optab): New optab.
	* tree-vect-patterns.c (vect_recog_divmod_pattern):
	Modify pattern to support new operation.
	* doc/md.texi (sdiv_pow2$var{m3}): Documentation for the above.
	* doc/sourcebuild.texi (vect_sdiv_pow2_si):
	Document new target selector.

gcc/testsuite/
	* gcc.dg/vect/vect-sdiv-pow2-1.c: New test.
	* gcc.target/aarch64/sve/asrdiv_1.c: As above.
	* lib/target-supports.exp (check_effective_target_vect_sdiv_pow2_si):
	Return true for AArch64 with SVE.

From-SVN: r276343