JIT Compiler چیه و چطور کار می‌کنه؟ - قسمت ۴

void main() {
   int a = 0;
   for (;;) { a += 1; }
}

main:
        push    rbp
        mov     rbp, rsp
        mov     DWORD PTR [rbp-4], 0
.L2:
        add     DWORD PTR [rbp-4], 1
        jmp     .L2

struct Instruction {
  int type; // 0: Mov, 1: Add, 2: JMP
  int arg0; // A: 0
  int arg1;
};

int main() {

  struct Instruction code[] = {
    { type: 0, arg0: 0, arg1: 0 }, // MOV A, #0
    { type: 1, arg0: 1 },          // ADD #1
    { type: 2, arg0: 1 },          // JMP :1
  };
  int ip = 0;
  int A = 0;
  struct Instruction current;
  for(;;) {
    if (ip >= sizeof(code)) { break; }
    current = code[ip];
    switch(current.type) {
      case 0:
        switch(current.arg0) {
            case 0:
              A = current.arg1;
              break;
            default: return -1;
        }
        break;
      case 1:
        A += current.arg0;
        break;
      case 2:
        ip = current.arg0;
        continue;
      default: return -1;
    }
    ip += 1;
  }
}

function isNumberBigEnough(x) {
   if (x > 5000) {
       return true;
   } else {
      return false;
  }
}

var jit = require('jit.js');

var fn = jit.compile(function() {
  this.Proc(function() {
    this.mov('rax', 42);
    this.Return();
  });
});
console.log(fn());