Chapter 3.9, Problem 3.41PP

A.

Explanation of Solution

Offsets for given fields:

The offset contents are shown below:

Offset      0                         8                     12                       16       ;&#x...

B.

Explanation of Solution

Total bytes required for structure:

• The “p” denotes an “int*” type, it has size of 8 bytes.
• The member “s.x” denotes an “int” type, it has size of 4 bytes.
• The member “s...

C.

Explanation of Solution

Given assembly code:

void sp_init(struct prob *sp)

sp in %rdi

sp_init:

movl 12(%rdi), %eax           

movl %eax, 8(%rdi)

leaq 8(%rdi), %rax

movq %rax, (%rdi)

movq %rdi, 16(%rdi)

ret

Load Effective Address:

• The load effective address instruction “leaq” is a variant of “movq” instruction.
• The instruction form reads memory to a register, but memory is not been referenced at all.
• The first operand of instruction is a memory reference; the effective address is been copied to destination.
• The pointers could be generated for later references of memory.
• The common arithmetic operations could be described compactly using this instruction.
• The operand in destination should be a register.

Data movement instructions:

• The different instructions are been grouped as “instruction classes”.
• The instructions in a class performs same operation but with different sizes of operand.
• The “Mov” class denotes data movement instructions that copy data from a source location to a destination.
• The class has 4 instructions that includes:
  • movb:
    • It copies data from a source location to a destination.
    • It denotes an instruction that operates on 1 byte data size.
  • movw: 
    • It copies data from a source location to a destination.
    • It denotes an instruction that operates on 2 bytes data size.
  • movl:
    • It copies data from a source location to a destination...