ARM to C calling convention, NEON registers to save

Question

There is a similar post that covers regular registers. What about NEON registers. As far as I remember either top half or bottom half of registers have to be preserved acros

Answer 1

From the AAPCS, §5.1.2.1:

• s16–s31 (d8–d15, q4–q7) must be preserved
• s0–s15 (d0–d7, q0–q3) and d16–d31 (q8–q15) do not need to be preserved