Module 7 - Procedures in Assembly

Question 1

What register stores a temporary value that the caller procedure must save before calling a nested procedure?
  $sp
  $t0
  $ra
  $s0
  $at
  $v0
  $a0

Answer 1

$t0

Question 2

What register does the “jal” instruction automatically update?
  $at
  $ra
  $a0
  $sp
  $v0
  $s0
  $t0

Answer 2

$ra

Question 3

What register stores a temporary value that the callee procedure must save before performing it’s task?

  $s0
  $t0
  $ra
  $sp
  $at
  $a0
  $v0

Answer 3

$s0

Question 4

What are the main reasons for writing procedures in assembly programs? Select all that apply.

Easier to understand and to debug
Avoiding use the jump table
Higher performance in terms of execution time
Easier to reuse the code

Answer 4

Easier to understand and to debug

Easier to reuse the code

Question 5

What register stores a parameter value of a procedure?
  $s0
  $v0
  $at
  $a0
  $sp
  $ra
  $t0

Answer 5

$a0

Question 6

A procedure does not call another procedure. How does it differ from a procedure that does call another procedure?

Register $ra does not need to be saved to stack
It does not need any arguments (no inputs
It does not return any values (no outputs)
Its return address does not need to be saved in $ra

Answer 6

Register $ra does not need to be saved to stack

Question 7

In MIPS, the stack pointer is manipulated using the instruction

addiu $sp, $sp, XX
where “XX” is a number that may be positive or negative.

If we need to reserve enough room on the stack for 6 integers in addition to the $ra register, what is the value of XX?

Answer 7

-28

Question 8

In a procedure call, the $ra register is used for what purpose?
  Temporary scratch storage.
  Storing the return address
  Passing Parameters
  Storing return values

Answer 8

Storing the return address

Question 9

A set of registers are reserved for procedure calls. How do we preserve all values when a procedure calls another procedure?
  Use floating point registers
  Use temporary registers
  Use heap memory
  Use stack memory

Answer 9

Use stack memory

Question 10

In a procedure call, what is responsible for saving the $ra registers?
  Operating System
  Caller Procedure
  Stack
  Callee Procedure

Answer 10

Caller Procedure