E.g. make sure the RLP segment is only used with the kernel context. Using current-context memory would also work, we just need to be consistent.
For transaction parsing etc, the context should be 0 anyway, but explicitly referring to kernel memory feels more idiomatic to me.
Again borrowing syntax from NASM. Example from the test:
%macro spin
%%start:
PUSH %%start
JUMP
%endmacro
One thing this lets us do is create "wrapper" macros which call a function, then return to the code immediately following the macro call, such as
%macro decode_rlp_scalar
%stack (pos) -> (pos, %%after)
%jump(decode_rlp_scalar)
%%after:
%endmacro
I used this to clean up `type_0.asm`.
However, since such macros need to insert `%%after` beneath any arguments in the stack, using them will be suboptimal in some cases. I wouldn't worry about it generally, but we might want to avoid them in performance-critical code, or functions with many arguments like `memcpy`.
