Why is it necessary for a called function in ARM to restore callee-saved registers before returning?

easy📝 Conceptual Q1 of 15

ARM Architecture - Subroutines and Stack

ATo allow the caller to modify those registers freely

BTo ensure the caller's register values remain unchanged after the call

CTo optimize the use of caller-saved registers

DTo avoid using the stack during function calls

Step-by-Step Solution

Solution:

Step 1: Understand callee-saved registers
Callee-saved registers must retain their values across function calls.
Step 2: Role of the called function
The called function must save and restore these registers if it modifies them.
Final Answer:
To ensure the caller's register values remain unchanged after the call -> Option B
Quick Check:
Preserving caller state is key [OK]

Quick Trick: Callee-saved registers must be restored to keep caller's state intact [OK]

Common Mistakes:

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