Should C code be the reference? Should asm be modified only when we are
sure C is ok? It is a problem when people change asm code without updating
the underlying C files.
you should modify whatever your target platform uses
That's a vague response. The C code tries to be the generic reference,
but can't always in the case where the feature can't be implemented
completely in C (or safely given an optimizing compiler). The generic
C code is going to be used by targets that don't override the C file
with an asm file, so yes, it should be modified first. I would then
build and test on a target that uses the generic C file. Next you
probably want to adjust the asm that implements the C file for your
target, and test again.