Branch instruction (B) in ARM Architecture - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of the Branch instruction (B) in ARM architecture?

The Branch instruction (B) is used to change the flow of execution by jumping to a different part of the program, allowing the processor to execute instructions from a new address.

beginner

How does the Branch instruction (B) determine where to jump?

The Branch instruction uses a signed offset value that is added to the current program counter (PC) plus 4 to calculate the target address to jump to.

beginner

What happens to the program counter (PC) when a Branch instruction is executed?

When a Branch instruction executes, the program counter (PC) is updated to the target address calculated by adding the offset to the current PC plus 4, causing the CPU to continue execution from that new address.

intermediate

Can the Branch instruction (B) in ARM be conditional?

Yes, the Branch instruction can be conditional by adding condition codes (like BEQ for branch if equal), which makes the jump happen only if certain conditions are met.

intermediate

What is the difference between a Branch (B) and Branch with Link (BL) instruction in ARM?

Branch (B) jumps to a new address without saving the return address, while Branch with Link (BL) saves the return address in the link register (LR) so the program can return after a subroutine call.

What does the Branch instruction (B) do in ARM architecture?

A Loads data from memory

B Changes the flow of execution to a new address

C Performs arithmetic addition

D Stores data to memory

The Branch instruction changes the program flow by jumping to a new address.

How is the target address calculated in a Branch instruction?

A By subtracting the offset from the stack pointer

B By using a fixed absolute address

C By multiplying the offset with the program counter

D By adding a signed offset to the current program counter

The Branch instruction adds a signed offset to the current PC to find the jump target.

What does the 'B' instruction stand for in ARM?

A Buffer

B Break

C Branch

D Byte

'B' stands for Branch, which changes the execution flow.

Which instruction saves the return address when jumping to a subroutine?

A BL (Branch with Link)

B B (Branch)

C MOV

D STR

BL saves the return address in the link register for returning after subroutine.

Can the Branch instruction be conditional in ARM?

A Yes, by using condition codes

B No, it is always unconditional

C Only in ARMv7 and earlier

D Only when used with BL

Branch instructions can be conditional by adding condition codes like BEQ, BNE.

Explain how the Branch instruction (B) changes the flow of a program in ARM architecture.

Think about how the CPU knows where to go next.

Describe the difference between the Branch (B) and Branch with Link (BL) instructions.

Consider what happens when you want to come back after a jump.