target/mips: optimize indirect branches

Cc: Yongbok Kim <yongbok.kim@imgtec.com>
Signed-off-by: NAurelien Jarno <aurelien@aurel32.net>
Message-Id: <20170430145254.25616-4-aurelien@aurel32.net>
Signed-off-by: NRichard Henderson <rth@twiddle.net>

target/mips/translate.c

@@ -10725,7 +10725,7 @@ static void gen_branch(DisasContext *ctx, int insn_bytes)
                 save_cpu_state(ctx, 0);
                 gen_helper_raise_exception_debug(cpu_env);
             }
-            tcg_gen_exit_tb(0);
+            tcg_gen_lookup_and_goto_ptr(cpu_PC);
             break;
         default:
             fprintf(stderr, "unknown branch 0x%x\n", proc_hflags);