程序集 – 返回中断处理程序后程序计数器的位置？

嗨我想知道当程序从中断服务程序返回时程序计数器在哪里？我知道当中断事件发生时,PC被推入堆栈.但是什么地址被推入堆栈的下一个或同一个(只执行一个)？当我们有

first instruction;
interrupt event here;
go inside the ISR;
exit ISR;
second instruction;

要么

first instruction;
interrupt event here;
go inside the ISR
exit ISR;
first instruction;

我的意思是,PC是指向ISR入口之前执行的指令,还是指向下一条指令(从ISR返回后)？
我希望你明白这个主意.

解决方法

由于在cpu处于精确固定状态之前无法处理中断,如果在指令中间产生中断,则在执行指令后将跳转到中断向量程序.

因此,当从中断过程返回时,PC将指向第一个之后的指令.

first instruction fetch (PC is updated meanwhile)
first instruction decode
interrupt is raised
first instruction execution
** Now and only Now the cpu checks for a possible interrupt **
interrupt is present,pushing PC on stack and other things
jump to interrupt address
execution of interrupt
return from interrupt (pop of PC and other things)
second instruction fetch 
...