Avoid generating machine code for infrequently used indirect jumps

We set 256 as the threshold because we recorded 16 indirect jumps, and
the threshold for launching T1C is 4096. This modification also saves
code cache space by avoiding storing the machine code with less usage.

Author: qwe661234

src/jit.c

@@ -57,6 +57,7 @@
 
 #define STACK_SIZE 512
 #define MAX_INSNS 1024
+#define IN_JUMP_THRESHOLD 256
 #if defined(__x86_64__)
 #define JUMP_LOC jump_loc + 2
 /* Special values for target_pc in struct jump */
@@ -1349,7 +1350,7 @@ void parse_branch_history_table(struct jit_state *state, rv_insn_t *ir)
         if (bt->times[max_idx] < bt->times[i])
             max_idx = i;
     }
-    if (bt->PC[max_idx]) {
+    if (bt->PC[max_idx] && bt->times[max_idx] >= IN_JUMP_THRESHOLD) {
         emit_load_imm(state, register_map[0], bt->PC[max_idx]);
         emit_cmp32(state, temp_reg, register_map[0]);
         uint32_t jump_loc = state->offset;
@@ -1564,7 +1565,8 @@ static void translate_chained_block(struct jit_state *state,
             if (bt->times[max_idx] < bt->times[i])
                 max_idx = i;
         }
-        if (bt->PC[max_idx] && !set_has(set, bt->PC[max_idx])) {
+        if (bt->PC[max_idx] && bt->times[max_idx] >= IN_JUMP_THRESHOLD &&
+            !set_has(set, bt->PC[max_idx])) {
             block_t *block1 =
                 cache_get(rv->block_cache, bt->PC[max_idx], false);
             if (block1 && block1->translatable)