@pimanttr: I was thinking through this and have been wondering whether it would just be safer and more efficient to always snapshot the VFP.

The alternative is we have to store some sort of dirty bit in Registers_arm and then understand how to conditional restore registers in libunwind::Registers_arm::jumpto in Unwind/UnwindRegistersRestore.S. Totally doable, but unsure whether it's worth the complexity?