Arm32 doesn’t have a zero-value register. Its non-general-purpose registers are PC, LR, SP, FP – tho the link register can be used for temporary values.
Re:The Return of the Frame Pointers
by CountSessine on Wednesday March 20, 2024 @08:19PM
(#39773630)
Ah yes - the weird one was PC not zero. Anyhoo, all of these mistakes were fixed with Arm64.
That said, I don’t know how valuable getting rid of FP on ARM is - I once benchmarked ffmpeg on 32-bit x86 before and after enabling FP and PIC (basically removing 2 GPRs) and the difference was huge (>10%) but that’s an extreme example.