arm: Auto-vectorization for MVE: vmvn

arm: Auto-vectorization for MVE: vmvn

This patch enables MVE vmvnq instructions for auto-vectorization.  MVE
vmvnq insns in mve.md are modified to use 'not' instead of unspec
expression to support one_cmpl<mode>2.  The one_cmpl<mode>2 expander
is added to vec-common.md.

2020-12-11  Christophe Lyon  <christophe.lyon@linaro.org>

	gcc/
	* config/arm/iterators.md (VDQNOTM2): New mode iterator.
	(supf): Remove VMVNQ_S and VMVNQ_U.
	(VMVNQ): Remove.
	* config/arm/mve.md (mve_vmvnq_u<mode>): New entry for vmvn
	instruction using expression not.
	(mve_vmvnq_s<mode>): New expander.
	* config/arm/neon.md (one_cmpl<mode>2): Renamed into
	one_cmpl<mode>2_neon.
	* config/arm/unspecs.md (VMVNQ_S, VMVNQ_U): Remove.
	* config/arm/vec-common.md (one_cmpl<mode>2): New expander.

	gcc/testsuite/
	* gcc.target/arm/simd/mve-vmvn.c: Add tests for vmvn.