Code Generation: Pointers and Arrays
Lecture 11

Get the memory address of a variable

int x;
pointer<int> y;
x = 10;
y = &x;

What is the value of y?

Get the contents of the memory at a pointer address

int x;
pointer<int> y;
x = 10;
y = &x;
return *y;

What is the value of *y?

Get the contents of the memory at a pointer address

int x;
pointer<int> y;
x = 10;
y = &x;
*y = 11;
return x;

What is the value of *y?

What is the value of y?

What is the value of x being returned?

• mov (%rax), %rbx (note parentheses) moves contents of memory at address contained in rax to rbx
• Handles x = *y

• mov %rax, (%rbx) (note parentheses) moves contents of rax to memory address contained in rbx
• Handles *y = 10

What does this program return?

main {
  int x;
  int y;
  pointer<int> z;
  x = 1;
  y = 2;
  z = &x - (pointer<int>)8;
  return *z;
}