什么是pushl/popl%esp的汇编级表示？

Question

C++

ATT大会

我试图理解以下两条指令的行为:

pushl %esp

和:

popl %esp

请注意,它们将计算出的值存储回来%esp.

我正在独立地考虑这些指令,而不是按顺序.我知道存储的值%esp总是递增/递减之前的值,但是我怎么能用汇编语言表示行为呢？这是我到目前为止所提出的:

推送:

movl %esp, %edx     1. save value of %esp
subl  $4, %esp      2. decrement stack pointer
movl %edx, (%esp)   3. store old value of %esp on top of stack

对于pop:

movl (%esp), %esp   You wouldn’t need the increment portion. 

它是否正确？如果没有,我哪里错了？谢谢.

Answer 1

正如它push esp在英特尔®64和IA-32架构开发人员手册中所述:组合卷:

The PUSH ESP instruction pushes the value of the ESP register as it existed
before the instruction was executed. If a PUSH instruction uses a memory operand
in which the ESP register is used for computing the operand address, the address
of the operand is computed before the ESP register is decremented.

至于pop esp:

The POP ESP instruction increments the stack pointer (ESP) before data at the old
top of stack is written into the destination.