I’m working on practice problem 3.34 in Computer Systems a Programmers Perspective and trying to understand exactly what is happening. The question states "Consider a function P, which generates local values, named a0-a7. It then calls function Qusing these generated values as arguments. GCC produces the following code for the first part of P". We are given the following assembly code:

/* long P(long x)
 * x in %rdi */
P:
  pushq   %r15
  pushq   %r14
  pushq   %r13
  pushq   %r12
  pushq   %rbp
  pushq   %rbx
  subq    $24, %rsp
  leaq    1(%rdi), %r15
  leaq    2(%rdi), %r14
  leaq    3(%rdi), %r13
  leaq    4(%rdi), %r12
  leaq    5(%rdi), %rbp
  leaq    6(%rdi), %rax
  movq    %rax, (%rsp)
  leaq    7(%rdi), %rdx
  movq    %rdx, 8(%rsp)
  movl    $0,