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Status: Tags: Links: Computer Memory

Memory Stack

Principles

• Hand Tracing Stack

x86-64 Assembly

• initially empty
• has stack-specific instructions and register

%rsp

• points to address of last used byte on stack
• initialized to “top of stack” at startup
• stack grows towards low memory address
• Should always go back to original position after end of function

push* src

• src can be
  • imm
  • register
  • memory
• execution
  1. get value of operand src
  2. decrement %rsp by 8 as you need to go down the stack
  3. store value at (memory adress stored in) %rsp
• %rsp is an implicit register

pop* dest

• dest can be
  • register
• execution
  1. read value at (memory adress stored in) %rsp and load this value in operand dest
  2. increment %rsp by 8
• %rsp is implicit register

Uses

Store local variables Steps:

• Setup code to create space on stack
  • subq $16, %rsp
• Spill onto stack
  • `movq %rax, 8(%rsp)
• Clean-up code (restore stack)
  • addq $16 %rsp

References:

Created:: 2022-02-12 16:11