Hello,

This patch series adds the Custom Datapath Extension to the arm backend.
This extension is currently only for the Thumb ISA.

The specification can be found here:
https://developer.arm.com/docs/ddi0607/latest

The patch is in two parts:
Part 1 enables the scalar instructions, which are predicated on *either*
Armv8-m with the floating point extension *or* Armv8.1-m with the MVE
extension.

Part 2 enables the vector instructions which are dependent on Armv8.1-m with
MVE.

Part 1 was worked on by both me and Stam Markianos-Wright.

The patch series has been successfully regression tested on arm-none-eabi and
arm-wince-pe.

Ok for master?

Regards,
MM

Entire patch series attached to cover letter.