The x86-64 stack grows towards lower addresses. When a procedure is invoked, more spack on the top of the stack is allocated for that procedure to make use of. This portion of the stack is called a **frame**. The general shape of the stack looks as follows:
![[x86-64-stack.png]]
Note parts of this diagram are omitted when possible. For instance, a stack frame may not exist at all if all arguments to a **leaf procedure** can be passed through registers. A leaf procedure is a function that does not call another function.
%%ANKII
Basic
What ADT is used internally in procedure-calling mechanisms?
Back: A stack.
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
END%%
%%ANKII
Cloze
The x86-64 stack grows towards {lower} addresses.
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
END%%
%%ANKI
Basic
What is a frame w.r.t. the x86-64 stack?
Back: A region of the stack dedicated to a particular function call.
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1728480337611-->
END%%
%%ANKI
Basic
What instructions are used to store and retrieve from the x86-64 stack?
Back: `pushq` and `popq`.
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1728480337614-->
END%%
%%ANKI
Basic
What does the "stack pointer" refer to w.r.t. the x86-64 stack?
Back: Register `%rsp`.
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1728480337617-->
END%%
%%ANKI
Basic
How is the stack pointer manipulated to allocate space on the x86-64 stack?
Back: By decrementing `%rsp` by an appropriate amount.
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1728480337621-->
END%%
%%ANKI
Basic
How is the stack pointer manipulated to deallocate space on the x86-64 stack?
Back: By incrementing `%rsp` by an appropriate amount.
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1728480337604-->
END%%
%%ANKI
Basic
Suppose procedure `P` calls `Q`. What data sits at the end of `P`'s frame?
Back: A return address.
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1728481058927-->
END%%
%%ANKI
Cloze
A {leaf} procedure is a function that {does not call another function}.
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1728481058953-->
END%%
%%ANKI
Basic
Suppose procedure `P` calls `Q`. The return address belongs to who's frame?
Back: `P`
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1728481058960-->
END%%
%%ANKI
Basic
Suppose procedure `P` calls `Q`. Why is the return address considered to be in `P`'s frame?
Back: It is state relevant to `P`.
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1728481058966-->
END%%
## Control Transfer
Like [[conditions#JMP|JMP]] instructions, `call` allows specifying a direct or indirect operand. `call` pushes the address of the instruction following it onto the stack and updates the PC to the operand. `ret` reverts these steps.
| Instruction | Operands | Description |
| ----------- | ----------- | ---------------- |
| `call` | Label | Procedure call |
| `call` | \**Operand* | Procedure call |
| `ret` | | Return from call |
%%ANKI
Cloze
The {`call`} instruction is the counterpart to the {`ret`} instruction.
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1728558288130-->
END%%
%%ANKI
Basic
What two things does the `call` instruction do?
Back: It pushes the return address on the stack and updates the PC.
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1728558288148-->
END%%
%%ANKI
Basic
What two things does the `ret` instruction do?
Back: It pops the return address off the stack and updates the PC.
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1728558288160-->
END%%
%%ANKI
Basic
The operand forms of `call` mirror what other instruction class?
Back: `JMP`
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1728558288165-->
END%%
%%ANKI
Basic
A `call` instruction pushes what address onto the stack?
Back: That of the instruction following the `call` instruction.
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1728558288171-->
END%%
%%ANKI
Basic
What return address is pushed onto the stack after `call` is run?
```x86
1: ...
2: callq .L1
3: ...
```
Back: `3`
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1728558288177-->
END%%
%%ANKI
Basic
What address is the PC updated to after `call` is run?
```x86
1: ...
2: callq .L1
3: ...
```
Back: That corresponding to label `.L1`.
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1728558288183-->
END%%
%%ANKI
Basic
Which register(s) does a `call` instruction update?
Back: `%rsp` and `%rip`.
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1728559336730-->
END%%
%%ANKI
Basic
Which register(s) does a `ret` instruction update?
Back: `%rsp` and `%rip`.
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1728559336760-->
END%%
## Data Transfer
x86-64 employs 6 registers for passing integral (i.e. integer and pointer) arguments between caller and callee.
How many registers are available for passing integral arguments between procedures?
Back: `6`
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1728559336766-->
END%%
%%ANKI
Basic
How many bytes make up the `%rdi` register?
Back: $8$
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1728559336770-->
END%%
%%ANKI
Basic
How many bytes make up the `%di` register?
Back: $2$
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1728559336774-->
END%%
%%ANKI
Basic
How many bytes make up the `%dil` register?
Back: $1$
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1728559336779-->
END%%
%%ANKI
Basic
How many bytes make up the `%edi` register?
Back: $4$
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1728559336782-->
END%%
%%ANKI
Cloze
By convention, register {`%rdi`} is used for {the first integral argument}.
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1728559336787-->
END%%
%%ANKI
Cloze
{1:Words} are to {2:`%di`} whereas {2:double words} are to {1:`%edi`}.
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1728559336792-->
END%%
%%ANKI
Cloze
{1:Bytes} are to {2:`%dil`} whereas {2:quad words} are to {1:`%rdi`}.
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1728559336797-->
END%%
%%ANKI
Basic
How do you access the low-order 2 bytes of `%rdi`?
Back: By using `%di`.
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1728559336802-->
END%%
%%ANKI
Basic
How do you access the low-order 4 bytes of `%rdi`?
Back: By using `%edi`.
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1728559336808-->
END%%
%%ANKI
Basic
How do you access the low-order byte of `%rdi`?
Back: By using `%dil`.
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1728559336813-->
END%%
%%ANKI
Basic
Which register should the first integral argument of a procedure be placed in?
Back: `%rdi`
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1728559336817-->
END%%
%%ANKI
Basic
From smallest to largest, list the four "first integral argument" registers.
Back: `%dil`, `%di`, `%edi`, and `%rdi`.
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1728559336823-->
END%%
%%ANKI
Basic
How many bytes make up the `%rsi` register?
Back: $8$
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1728559336829-->
END%%
%%ANKI
Basic
How many bytes make up the `%si` register?
Back: $2$
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1728559336834-->
END%%
%%ANKI
Basic
How many bytes make up the `%sil` register?
Back: $1$
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1728559336838-->
END%%
%%ANKI
Basic
How many bytes make up the `%esi` register?
Back: $4$
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1728559336843-->
END%%
%%ANKI
Cloze
By convention, register {`%rsi`} is used for {the second integral argument}.
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1728559336847-->
END%%
%%ANKI
Cloze
{1:Words} are to {2:`%si`} whereas {2:double words} are to {1:`%esi`}.
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1728559336852-->
END%%
%%ANKI
Cloze
{1:Bytes} are to {2:`%sil`} whereas {2:quad words} are to {1:`%rsi`}.
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1728559336856-->
END%%
%%ANKI
Basic
How do you access the low-order 2 bytes of `%rsi`?
Back: By using `%si`.
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1728559336860-->
END%%
%%ANKI
Basic
How do you access the low-order 4 bytes of `%rsi`?
Back: By using `%esi`.
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1728559336864-->
END%%
%%ANKI
Basic
How do you access the low-order byte of `%rsi`?
Back: By using `%sil`.
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1728559336868-->
END%%
%%ANKI
Basic
Which register should the second integral argument of a procedure be placed in?
Back: `%rsi`
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1728559336872-->
END%%
%%ANKI
Basic
From smallest to largest, list the four "second integral argument" registers.
Back: `%sil`, `%si`, `%esi`, and `%rsi`.
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1728559336876-->
END%%
%%ANKI
Cloze
{1:`%rdi`} is to the {2:first} integral argument whereas {2:`%rsi`} is to the {1:second} integral argument.
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1729533668317-->
END%%
%%ANKI
Basic
How many bytes make up the `%dx` register?
Back: $2$
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1729533668324-->
END%%
%%ANKI
Basic
How many bytes make up the `%dl` register?
Back: $1$
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1729533668328-->
END%%
%%ANKI
Basic
How many bytes make up the `%edx` register?
Back: $4$
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1729533668334-->
END%%
%%ANKI
Cloze
By convention, register {`%rdx`} is used for {the third integral argument}.
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1729533668338-->
END%%
%%ANKI
Cloze
{1:Words} are to {2:`%dx`} whereas {2:double words} are to {1:`%edx`}.
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1729533668341-->
END%%
%%ANKI
Cloze
{1:Bytes} are to {2:`%dl`} whereas {2:quad words} are to {1:`%rdx`}.
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1729533668345-->
END%%
%%ANKI
Basic
How do you access the low-order 2 bytes of `%rdx`?
Back: By using `%dx`.
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1729641729174-->
END%%
%%ANKI
Basic
How do you access the low-order 4 bytes of `%rdx`?
Back: By using `%edx`.
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1729533668349-->
END%%
%%ANKI
Basic
How do you access the low-order byte of `%rdx`?
Back: By using `%dl`.
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1729533668352-->
END%%
%%ANKI
Basic
Which register should the third integral argument of a procedure be placed in?
Back: `%rdx`
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1729533668358-->
END%%
%%ANKI
Basic
From smallest to largest, list the four "third integral argument" registers.
Back: `%dl`, `%dx`, `%edx`, and `%rdx`.
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1729533668361-->
END%%
%%ANKI
Cloze
{1:`%dil`} is to the {2:first} integral argument whereas {2:`%dl`} is to the {1:third} integral argument.
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1729612004982-->
END%%
%%ANKI
Basic
How many bytes make up the `%rcx` register?
Back: $8$
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1729641729180-->
END%%
%%ANKI
Basic
How many bytes make up the `%ecx` register?
Back: $4$
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1729641729183-->
END%%
%%ANKI
Basic
How many bytes make up the `%cx` register?
Back: $2$
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1729641729186-->
END%%
%%ANKI
Basic
How many bytes make up the `%cl` register?
Back: $1$
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1729641729189-->
END%%
%%ANKI
Cloze
By convention, register {`%rcx`} is used for {the fourth integral argument}.
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1729641729193-->
END%%
%%ANKI
Cloze
{1:Words} are to {2:`%cx`} whereas {2:quad words} are to {1:`%rcx`}.
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1729641729196-->
END%%
%%ANKI
Cloze
{1:Bytes} are to {2:`%cl`} whereas {2:double words} are to {1:`%ecx`}.
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1729641729200-->
END%%
%%ANKI
Basic
How do you access the low-order 2 bytes of `%rcx`?
Back: By using `%cx`.
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1729641729203-->
END%%
%%ANKI
Basic
How do you access the low-order 4 bytes of `%rcx`?
Back: By using `%ecx`.
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1729641729207-->
END%%
%%ANKI
Basic
How do you access the low-order byte of `%rcx`?
Back: By using `%cl`.
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1729641729210-->
END%%
%%ANKI
Basic
Which register should the fourth integral argument of a procedure be placed in?
Back: `%rcx`
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1729641729214-->
END%%
%%ANKI
Basic
From smallest to largest, list the four "fourth integral argument" registers.
Back: `%cl`, `%cx`, `%ecx`, and `%rcx`.
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
<!--ID: 1729641729217-->
END%%
%%ANKI
Cloze
{1:`%di`} is to the {2:first} integral argument whereas {2:`%cx`} is to the {1:fourth} integral argument.
Reference: Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
* Bryant, Randal E., and David O'Hallaron. *Computer Systems: A Programmer's Perspective*. Third edition, Global edition. Always Learning. Pearson, 2016.
