Return value in R0 in ARM Architecture - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of the R0 register in ARM architecture?

R0 is used to hold the return value of a function in ARM architecture. When a function finishes, it places its result in R0 for the caller to use.

beginner

Which register typically holds the return value after a function call in ARM?

The R0 register typically holds the return value after a function call in ARM processors.

beginner

If a function returns an integer value, where is this value stored in ARM assembly?

The integer return value is stored in the R0 register before returning to the caller.

intermediate

Why is R0 used for return values in ARM instead of other registers?

R0 is used because ARM calling conventions designate it as the primary register for passing return values, simplifying function calls and returns.

intermediate

Can R0 be used for purposes other than returning values in ARM functions?

Yes, R0 can be used as a general-purpose register during function execution, but before returning, it must hold the return value.

In ARM architecture, which register holds the return value of a function?

A R0

B R1

C R7

D LR

R0 is the standard register used to hold the return value after a function call in ARM.

What type of value is typically stored in R0 after a function returns?

A Program counter

B Stack pointer

C Return value

D Status flags

R0 holds the return value from a function, such as an integer or pointer.

If a function returns no value (void), what is stored in R0?

A Zero always

B Stack pointer

C Function address

D Undefined or ignored

If no value is returned, R0 may contain any value and is generally ignored.

Which ARM register is NOT used to return a function value?

A R1

B LR

C R2

D R0

LR (Link Register) holds the return address, not the return value.

Why is it important to place the return value in R0 before returning from a function?

A Because the caller expects the result in R0

B Because R0 controls the program flow

C Because R0 stores the stack pointer

D Because R0 holds the return address

The calling convention requires the return value in R0 so the caller can access it easily.

Explain the role of the R0 register in returning values from functions in ARM architecture.

Think about how functions communicate results back to the caller.

Describe what happens to the R0 register during and after a function call in ARM.

Consider the lifecycle of R0 in a function call.