Assembly Part 2

Question 1

.file

Answer 1

Allows a name to be assigned to assembly language source code file

Question 2

.section

Answer 2

This makes the specified section the current section (required)

Question 3

.rodata

Answer 3

Specifies that the following data to be placed in the read only memory portion of the executable (required if you have read only data)

Question 4

.data

Answer 4

Changes or sets the current section to the data section

Question 5

.text

Answer 5

Changes or sets the current section to the text (or code) section

Question 6

.globl

Answer 6

A directive needed by linker for symbol resolution: followed by name of function

Question 7

.type

Answer 7

Needed by the linker to identify the label associated with a function, as opposed to data

Question 8

.size

Answer 8

Needed by the linker to identify the size of the text for the program

Question 9

.align

Answer 9

Needed if we want to declare values on the head to start an address that has a particular byte alignment (1,2,4,8)

Question 10

What happens if you want to declare static class variables

Answer 10

In the .data or .rodata section of program, you need to declare the values

.quad value
.long value
.word value
.byte value
.string

Question 11

.quad

Answer 11

Places given value in memory encoded by 8 bytes

Question 12

Other data sizes

Answer 12

.long, .,words, .byte, .string

Question 13

Leaq

Answer 13

Address computation

Question 14

Sale

Answer 14

Shift arithmetic left

Question 15

Imulq

Answer 15

Signed multiply

Question 16

The program stack is divided conceptually into ____

Answer 16

Frames

Question 17

Each procedure or function has its own part of the stack to use which is called the ____

Answer 17

Stack frame

Question 18

The stack frame goes from the stack address pointed to by ___. This is called the ___/____ pointer to %______ which points to the ____ of the stack

Answer 18

%rbp, frame,base, top

Question 19

_____ must be set when the procedure is entered

Answer 19

%rbp

Question 20

First use of stack
Save the _____ %rbp before setting our frame pointer

Answer 20

Caller

Question 21

Second use of stack
Before calling another function, perverse values needed using ____/_____

Answer 21

Push, pop

Question 22

Third use of stack
To pass _____ to another function (only if there are more than 6 parameters to pass)

Answer 22

Parameters

Question 23

Fourth use of stack
To store the _______ ________ when a call instruction is executed

Answer 23

Return address

Question 25

Fifth use of the stack If we need more _______ _______ than available registers (automatic, block scope)

Answer 25

Temp data

Question 26

PushX source

Answer 26

Decrement %rsp by number of bytes specified in oppose suffix and write bytes (of size specified by suffix) to memory address %rsp

Question 27

We can push a value of a _____, a value from _____ to the stack, and a _____ to the stack

Answer 27

Register, memory, stack

Question 28

_____ and _____ push instructions are NOT valid

Answer 28

Push, pushb

Question 29

Only push and pop _____ byte value to stack

Answer 29

8

Question 30

PopX destination

Answer 30

Reads number of bytes specified by suffix from the address %rsp and store in destination. Increment %rsp by number of bytes specified by oppose suffix so rsp points to next value on stack

Question 31

First thing to do when setting up program stack 1. Set %rbp to point to _____ of current stack frame

Answer 31

Bottom

Question 32

Setting up program stack 2. Set %rsp to current ____ of stack (same address as the stack bottom initially)

Answer 32

Top

Question 33

At the end of function, what to do with rsp and rbp?

Answer 33

Put them back

Question 34

CallX does two things 1. The _____ of the instruction immediately after the call instruction is pushed onto the stack (that is, the return address is pushed) 2. The _____ is assigned to the PC (%rip) register

Answer 34

Address, Dest

Question 35

Setting up stack frame

Answer 35

1. Push %rbp #save caller’s base pointer 2. Movq %rsp, %rbp #set my base pointer %rbp is equal to %rsp, the stack frame is empty and we are ready to use the stack

Question 36

When leaving a function

Answer 36

Leave. # set caller’s stack frame back up

Question 37

Leave is equivalent to

Answer 37

Movq %rbp, %rsp Pop %rbp

Question 38

RetX 1. The ____ of the instruction immediately after the ______ instruction that got us here is popped from the stack 2. The address is assigned to the PC (%rip) register

Answer 38

Address, call

Question 39

1st step in setting up stack frames

Answer 39

Pushq %rbp —> save caller’s base pointer of the stack

Question 40

2nd step in setting up stack frame

Answer 40

Move %rsp, %rbp -> set the base pointer Now rsp equals rbp, this means the stack frame is empty and stack is ready to use

Question 41

RetX does 2 things 1. The ____ of the instruction immediately after the call instruction that got us here is popped from the stack 2. That address is assigned to the ______ (___) register

Answer 41

Address, PC, %rip

Question 42

What instructions change %rsp

Answer 42

Push, pop, call, ret

Question 43

Push

Answer 43

Decrements rsp and stores value on stack

Question 44

Pop

Answer 44

Increments tsp and pops value from stack

Question 45

Call

Answer 45

Pushes the return address (current %rip) on the stack

Question 46

RetX

Answer 46

Pops return address off the stack Ret —> pops address into rip, rsp += 8 1. The address of the instruction immediately after the call instruction that got is here is popped from stack 2. Address is assigned to PC (%rip) register

Question 47

Reverse to accessing memory using a base address and a offset (usually a constant or a register that holds and offset in bytes)

Answer 47

Conventional index

Question 48

Uses a register multiplied (scaled) by a constant factors (1,2,4,8) to automatically compute byte offsets when working with arrays of primate types (like int double, or pointers)

Answer 48

Scales index Ex: Movl (%rdi, %rsi, 4), %eax