I'm developing a virtual CPU for fun and I am currently working on the assembly part.
Now I wonder if values in the .data section should be mutable or not.
section .data
MyGlobalVar dw 10h
In the places where I reference MyGlobalVar, should I resolve the value at assembly time or runtime? Which would be the most appropriate way of doing it?
mov ra, 10h ; Assembly time resolved value
mov ra, [0x00000000] ; Address of MyGlobalVar dereferenced when executed
If you implicitly dereferenced at assemble time to produce an immediate constant, you'd always get the value from the source code. That's what equ is for; programmers can use that if that's what they want instead of a load from .rodata. (In that case, the bytes in that section would only be accessed by code that indexes a lookup table or something like that.)
And obviously that doesn't work at all for mutable data, it has to be a load from the memory location other code might have modified.
It's assembly language; don't change the program instructions to something with an architecturally different effect. You're writing an assembler, not a compiler. Even a section like .rodata that normally gets mapped into read-only pages can get modified by a debugger, potentially.