CSC448: Code Generation: Run-Time Environment V [58/133]

What if recursive procedure calls are permitted?

A stack allows fast allocation and deallocation of activation records.

The position of local variables is not known at compile-time.

Generated code expects to find local variables at a fixed offset from the current activation record (in a C-like language).

On x86:

• The ebp (Stack-Frame Base Pointer) register points to the current activation record.
• For example, -4(%ebp) refers to the memory location that is 4 bytes (or one word = one 32 bit integer) below the area pointed to by the base pointer. The following code moves the integer constant 3 into that location:

  movl $3, -4(%ebp)
  

• The esp (Stack Pointer) register points to the top element of the stack.
• The stack grows downwards in memory.