Hello,
I have worked with different Arm processors including M4 and M7 (STMF32, CM408) and their assembly programming especially on SIMD DSP instructions. Also I have done assembly programming on many other processors (TI, ADI, NXP)
As long as it is assembly, it does not matter which compiler (Keil, IAR, Gcc) you are using.
Anyway, my time and price are approximate and will depend on the amount of work.
Thanks.