wip: working on infinite loop handling in vm

src/vm/fzl_vm.c

@@ -4,6 +4,7 @@
 #include <common/fzl_value.h>
 #include <compiler/utils/fzl_const_pool.h>
 #include <stdbool.h>
+#include <stddef.h>
 #include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -13,6 +14,11 @@
 #include <vm/fzl_vm_object.h>
 
 char last_err[256];
+size_t last_jmp_ip = 0;
+
+// NOTE: add `--max-iter` option for limit
+size_t max_iter_limit    = 100000;
+size_t total_jmp_on_same = 0;
 
 static char *expect_hdr = "FZL\0\1";
 
@@ -667,7 +673,22 @@ int fzl_vm_run(fzl_vm_t *vm)
           return -1;
         }
         uint64_t jmp_ip = vm->ops[++vm->ip];
-        vm->ip          = jmp_ip - 1;
+        if (jmp_ip == last_jmp_ip)
+          total_jmp_on_same++;
+        else
+          total_jmp_on_same = 0;
+
+        if (total_jmp_on_same > max_iter_limit)
+        {
+          snprintf(last_err, sizeof(last_err),
+                   "runtime error - exceeded max loop jumps (infinite loop?)\n"
+                   "If you thinks there's mistake, change jumps limit with "
+                   "--max-iter=N");
+          return -1;
+        }
+
+        vm->ip      = jmp_ip - 1;
+        last_jmp_ip = jmp_ip;
         break;
       }