within all of these functions, and is only stored in some to correctly pad
the stack.
This will be needed to build as Thumb-2 as, unlike with ARM instructions,
the msr instruction only takes a register as the input.
existing functions with the exception they use the condition flags to
store the result.
Differential Revision: https://reviews.freebsd.org/D872
Silence from: current@ and numerics@
MFC after: 1 week