对于某个程序被取消后的第一个调用，或对于某个方法调用，编译器会初始化这些专用寄存器的字段，将它们作为初始值。

For the first call to a program after a cancel of that program, or for a method invocation, the compiler initializes the fields of these special registers to their initial values.

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更好的是，对于小型对象，J VM可以把分配工作完全优化掉，只把对象的字段放入寄存器。

Even better, for small objects, the JVM can optimize away the allocation entirely and simply hoist the object's fields into registers.

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