gas * config/tc-arm.c (arm_extensions):
(arm_archs): New entry for "armv8.4-a".
Add FPU_ARCH_DOTPROD_NEON_VFP_ARMV8.
(arm_ext_v8_2): New variable.
(enum arm_reg_type): New enumeration REG_TYPE_NSD.
(reg_expected_msgs): New entry for REG_TYPE_NSD.
(parse_typed_reg_or_scalar): Handle REG_TYPE_NSD.
(parse_scalar): Support REG_TYPE_VFS.
(enum operand_parse_code): New enumerations OP_RNSD and OP_RNSD_RNSC.
(parse_operands): Handle OP_RNSD and OP_RNSD_RNSC.
(NEON_SHAPE_DEF): New entries for DHH and DHS.
(neon_scalar_for_fmac_fp16_long): New function to generate Rm encoding
for new FP16 instructions in ARMv8.2-A.
(do_neon_fmac_maybe_scalar_long): New function to encode new FP16
instructions in ARMv8.2-A.
(do_neon_vfmal): Wrapper function for vfmal.
(do_neon_vfmsl): Wrapper function for vfmsl.
(insns): New entries for vfmal and vfmsl.
* doc/c-arm.texi (-march): Document "armv8.4-a".
* testsuite/gas/arm/dotprod-mandatory.d: New test.
* testsuite/gas/arm/armv8_2-a-fp16.s: New test source.
* testsuite/gas/arm/armv8_2-a-fp16-illegal.s: New test source.
* testsuite/gas/arm/armv8_2-a-fp16.d: New test.
* testsuite/gas/arm/armv8_3-a-fp16.d: New test.
* testsuite/gas/arm/armv8_4-a-fp16.d: New test.
* testsuite/gas/arm/armv8_2-a-fp16-thumb2.d: New test.
* testsuite/gas/arm/armv8_2-a-fp16-illegal.d: New test.
* testsuite/gas/arm/armv8_2-a-fp16-illegal.l: New error file.
opcodes * arm-dis.c (coprocessor_opcodes): New entries for ARMv8.2-A new
FP16 instructions, including vfmal.f16 and vfmsl.f16.
include * opcode/arm.h (ARM_AEXT2_V8_4A): Include Dot Product feature.
(ARM_EXT2_V8_4A): New macro.
(ARM_AEXT2_V8_4A): Likewise.
(ARM_ARCH_V8_4A): Likewise.