Kotlin 无需额外对象分配的数组(Array)列表(List)迭代

I'm working on a game written in Kotlin and was looking into improving GC churn. One of the major sources of churn are for-loops called in the main game/rendering loops that result in the allocation of iterators.

Turning to the documentation, I found this paragraph:

A for loop over an array is compiled to an index-based loop that does not create an iterator object.

如果要通过索引遍历数组或列表，可以这样做:

for (i in array.indices)
  print(array[i])

Note that this “iteration through a range” is compiled down to optimal implementation with no extra objects created.

https://kotlinlang.org/docs/reference/control-flow.html#for-loops个

这是真的吗？为了验证，我使用了这个简单的Kotlin程序，并判断了生成的字节码:

fun main(args: Array<String>) {
    val arr = arrayOf(1, 2, 3)
    for (i in arr.indices) {
        println(arr[i])
    }
}

根据上面的引文，这不应该导致分配任何对象，而是将其编译为一个很好的旧的Java-5之前的for循环样式.然而，我得到的是:

      41: aload_1
      42: checkcast     #23                 // class "[Ljava/lang/Object;"
      45: invokestatic  #31                 // Method kotlin/collections/ArraysKt.getIndices:([Ljava/lang/Object;)Lkotlin/ranges/IntRange;
      48: dup
      49: invokevirtual #37                 // Method kotlin/ranges/IntRange.getFirst:()I
      52: istore_2
      53: invokevirtual #40                 // Method kotlin/ranges/IntRange.getLast:()I
      56: istore_3
      57: iload_2
      58: iload_3
      59: if_icmpgt     93

在我看来，好像调用了一个名为getIndices的方法，该方法分配了一个临时IntRange对象来备份循环中的边界判断.这是一个"没有创建额外对象"的"最佳实现"，还是我遗漏了什么？

UPDATE: So, after toying around a bit more and looking at the answers, the following appears to be true for Kotlin 1.0.2:

Arrays:

• for (i in array.indices):范围分配
• for (i in 0..array.size): no allocation
• for (el in array):没有分配
• array.forEach:不分配

Collections:

• for (i in coll.indices)范围分配
• for (i in 0..coll.size): no allocation
• for (el in coll):迭代器分配
• coll.forEach: iterator allocation