问如何在将两个2的补码整数相乘时检测溢出？

EN

int
would_mul_exceed_int(int a, int b) {
  int product_bits;

  if (a == 0 || b == 0 || a == 1 || b == 1) return (0); /* always okay */
  if (a == INT_MIN || b == INT_MIN) return (1); /* always underflow */

  a = ABS(a);
  b = ABS(b);

  product_bits  = significant_bits_uint((unsigned)a);
  product_bits += significant_bits_uint((unsigned)b);

  if (product_bits == BITS(int)) { /* cases where the more expensive test is required */
    return (a > INT_MAX / b); /* remember that IDIV and similar are very slow (dozens - hundreds of cycles) compared to bit shifts, adds */
  }
  return (product_bits > BITS(int));
}