Chapter 3.8, Problem 3.39PP

Explanation of Solution

Array indexing:

• The declaration “T A[N]” where “T” denotes as a data type, “N” an integer constant and “A” denotes an array.
• The starting location of array denotes “x_A”.
• It allocates “L.N” memory bytes that denote a contiguous region.
• The “L” denotes size of data type.
• The array element “i” will be stored at address “x_A+L.i”.

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.
    • It denotes an instruction that operates on 4 bytes data size.
  • movq:
    • It copies data from a source location to a destination.
    • It denotes an instruction that operates on 8 bytes data size.

Computations of initial values for A_ptr, B_ptr and B_end:

• The details of instructions are shown below:
  • The registers “%rdi”, “%rsi”, “%rdx” and “%rcx” contains values of “A”, “B”, “i” and “k” respectively...