[Solved] Identify the error in this ARM assembly snippet:BL subroutine MOV R0, #1 subroutine: MOV R0, #2 B LR | ARM Architecture

ARM Architecture - Control Flow Instructions

Identify the error in this ARM assembly snippet:

BL subroutine
MOV R0, #1
subroutine:
MOV R0, #2
B LR

AMOV instruction cannot follow BL

BMissing label after BL instruction

CBL cannot call subroutines with MOV

DIncorrect use of B LR instead of BX LR to return

Step-by-Step Solution

Solution:

Step 1: Check return instruction
To return from subroutine, BX LR must be used to branch to address in LR.
Step 2: Identify error
B LR branches to label LR, which likely does not exist, causing error.
Final Answer:
Incorrect use of B LR instead of BX LR to return -> Option D
Quick Check:
Return from subroutine requires BX LR [OK]

Quick Trick: Use BX LR, not B LR, to return from subroutine [OK]

Common Mistakes:

Master "Control Flow Instructions" in ARM Architecture

9 interactive learning modes - each teaches the same concept differently

More ARM Architecture Quizzes

Identify the error in this ARM assembly snippet: