Hi,

This patch adds support for VABAV, VMLADAV and VMLSDAV. These are the 
first MVE-only mnemonics, so this patch shows how we deal with such 
instructions.

We define M_MNEM_<insn> MACROs to be able to encode and reference a 
particular instruction.

Cheers,
Andre

gas/ChangeLog:

2019-05-01  Andre Vieira  <andre.simoesdiasvieira@arm.com>

	* config/tc-arm.c (struct asm_opcode): Make avalue a full int.
	(BAD_ODD, BAD_EVEN, BAD_SIMD_TYPE): New errors.
	(enum operand_parse_code): Handle new operands.
	(parse_operands):
	(M_MNEM_vabav, M_MNEM_vmladav, M_MNEM_vmladava, M_MNEM_vmladavx,
         M_MNEM_vmladavax, M_MNEM_vmlsdav, M_MNEM_vmlsdava, M_MNEM_vmlsdavx,
         M_MNEM_vmlsdavax): Define new encodings.
	(NEON_SHAPE_DEF): Add new shape.
	(neon_check_type): Use BAD_SIMD_TYPE.
	(mve_encode_rqq): New encoding helper function.
	(do_mve_vabav, do_mve_vmladav): New encoding functions.
	(mCEF): New MACRO.
	* testsuite/gas/arm/mve-vabav-bad.d: New test.
	* testsuite/gas/arm/mve-vabav-bad.l: New test.
	* testsuite/gas/arm/mve-vabav-bad.s: New test.
	* testsuite/gas/arm/mve-vmladav-bad.d: New test.
	* testsuite/gas/arm/mve-vmladav-bad.l: New test.
	* testsuite/gas/arm/mve-vmladav-bad.s: New test.
	* testsuite/gas/arm/mve-vmlav-bad.d: New test.
	* testsuite/gas/arm/mve-vmlav-bad.l: New test.
	* testsuite/gas/arm/mve-vmlav-bad.s: New test.
	* testsuite/gas/arm/mve-vmlsdav-bad.d: New test.
	* testsuite/gas/arm/mve-vmlsdav-bad.l: New test.
	* testsuite/gas/arm/mve-vmlsdav-bad.s: New test.