[PATCH 0/2] Correct the requirement of compressed floating point instructions.

[Kito Cheng]

This series patches are contain 2 patches, main purpose is correct the
requirement of compressed floating point load/store instructions.

In current implementation, -march=rv32ic and -march=rv64ic can accept
fld without warning, because gas only check C extension is available.

So I've make it able to check more than one extension in first patch,
and fix those info for compressed floating point load/store
instructions.

[Kito Cheng]

ChangeLog

2018-08-29 Kito Cheng <ki...@andestech.com>

gas/
* config/tc-riscv.c (riscv_subset_supports): New argument:
xlen_required.
(riscv_multi_subset_supports): New function, able to check more
than one extension.
(riscv_ip): Use riscv_multi_subset_supports instead of
riscv_subset_supports.
(riscv_set_arch): Update call-site for riscv_subset_supports.
(riscv_after_parse_args): Likewise.

include/
*opcode/riscv.h (MAX_SUBSET_NUM): New.
(riscv_opcode): Add xlen_requirement field and change type of
subset.

opcodes/
* riscv-dis.c (riscv_disassemble_insn): Check XLEN by
riscv_opcode.xlen_requirement.
* riscv-opc.c (riscv_opcodes): Update for struct change.

[Jim Wilson]

I committed the first part.

Jim