Chapter 3.6, Problem 3.23PP

A.

Explanation of Solution

Registers for holding values:

• The parameter “x” is been passed to function in register “%rdi”.
• Once loop is entered, there is no reference to register.
• The register “%rax” is initialized to “x”.
• The register “%rcx” is initialized to “x*x”...

B.

Explanation of Solution

Compiler elimination of pointer variable:

• The pointer “p” always points to x as determined by compiler.
• The expression “(*p)++” would increment x...

C.

Explanation of Solution

Modified annotated code:

long dw_loop(long x)

x in %rdi

dw_loop:

movq %rdi, %rax;Copy x to %rax

movq %rdi, %rcx

imulq %rdi, %rcx;Compute y = x*x

leaq (%rdi, %rdi), %rdx;Compute n = 2*x

.L2:;Loop

leaq 1(%rcx, %rax), %rax;Compute x+=y+1

subq $1, %rdx;Decrement n

testq %rdx, %rdx;Test n

jg ...