[AArch64][SVE 28/32] Add SVE FP immediate operands

[AArch64][SVE 28/32] Add SVE FP immediate operands

This patch adds support for the new SVE floating-point immediate
operands.  One operand uses the same 8-bit encoding as base AArch64,
but in a different position.  The others use a single bit to select
between two values.

One of the single-bit operands is a choice between 0 and 1, where 0
is not a valid 8-bit encoding.  I think the cleanest way of handling
these single-bit immediates is therefore to use the IEEE float encoding
itself as the immediate value and select between the two possible values
when encoding and decoding.

As described in the covering note for the patch that added F_STRICT,
we get better error messages by accepting unsuffixed vector registers
and leaving the qualifier matching code to report an error.  This means
that we carry on parsing the other operands, and so can try to parse FP
immediates for invalid instructions like:

	fcpy	z0, #2.5

In this case there is no suffix to tell us whether the immediate should
be treated as single or double precision.  Again, we get better error
messages by picking one (arbitrary) immediate size and reporting an error
for the missing suffix later.

include/
	* opcode/aarch64.h (AARCH64_OPND_SVE_FPIMM8): New aarch64_opnd.
	(AARCH64_OPND_SVE_I1_HALF_ONE, AARCH64_OPND_SVE_I1_HALF_TWO)
	(AARCH64_OPND_SVE_I1_ZERO_ONE): Likewise.

opcodes/
	* aarch64-tbl.h (AARCH64_OPERANDS): Add entries for the new SVE FP
	immediate operands.
	* aarch64-opc.h (FLD_SVE_i1): New aarch64_field_kind.
	* aarch64-opc.c (fields): Add corresponding entry.
	(operand_general_constraint_met_p): Handle the new SVE FP immediate
	operands.
	(aarch64_print_operand): Likewise.
	* aarch64-opc-2.c: Regenerate.
	* aarch64-asm.h (ins_sve_float_half_one, ins_sve_float_half_two)
	(ins_sve_float_zero_one): New inserters.
	* aarch64-asm.c (aarch64_ins_sve_float_half_one): New function.
	(aarch64_ins_sve_float_half_two): Likewise.
	(aarch64_ins_sve_float_zero_one): Likewise.
	* aarch64-asm-2.c: Regenerate.
	* aarch64-dis.h (ext_sve_float_half_one, ext_sve_float_half_two)
	(ext_sve_float_zero_one): New extractors.
	* aarch64-dis.c (aarch64_ext_sve_float_half_one): New function.
	(aarch64_ext_sve_float_half_two): Likewise.
	(aarch64_ext_sve_float_zero_one): Likewise.
	* aarch64-dis-2.c: Regenerate.

gas/
	* config/tc-aarch64.c (double_precision_operand_p): New function.
	(parse_operands): Use it to calculate the dp_p input to
	parse_aarch64_imm_float.  Handle the new SVE FP immediate operands.