From 4e35d7f5440fb19d708256ec79068224a3cff43a Mon Sep 17 00:00:00 2001
From: Kito Cheng <kito.cheng@sifive.com>
Date: Wed, 24 May 2023 23:21:39 +0800
Subject: [PATCH] Define new tag for atomic ABI.

Alternative version of #383

Defined 4 atomic abi variant.

- unknown, nonatomic, A6C and A6S

Unknown is compatilbe with exising object file.
Nonatomic is used when A-extension is absent
A6C is the table A.6 mapping defined in ISA spec.
And the A6S is the mapping defined in psABI spec.