target/riscv: Add a riscv_cpu_is_32bit() helper function

Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Bin Meng <bin.meng@windriver.com>
Tested-by: Bin Meng <bin.meng@windriver.com>
Reviewed-by: Palmer Dabbelt <palmerdabbelt@google.com>
Acked-by: Palmer Dabbelt <palmerdabbelt@google.com>
Message-id: ebd37b237a8cbe457335b948bd57f487b6b31869.1608142916.git.alistair.francis@wdc.com

target/riscv/cpu.c

@@ -108,6 +108,15 @@ const char *riscv_cpu_get_trap_name(target_ulong cause, bool async)
     }
 }
 
+bool riscv_cpu_is_32bit(CPURISCVState *env)
+{
+    if (env->misa & RV64) {
+        return false;
+    }
+
+    return true;
+}
+
 static void set_misa(CPURISCVState *env, target_ulong misa)
 {
     env->misa_mask = env->misa = misa;

target/riscv/cpu.h

@@ -384,6 +384,8 @@ FIELD(TB_FLAGS, VILL, 8, 1)
 /* Is a Hypervisor instruction load/store allowed? */
 FIELD(TB_FLAGS, HLSX, 9, 1)
 
+bool riscv_cpu_is_32bit(CPURISCVState *env);
+
 /*
  * A simplification for VLMAX
  * = (1 << LMUL) * VLEN / (8 * (1 << SEW))