I am wondering what methods there are to add typing information to generated C methods. I'm transpiling a higher-level programming language to C and I'd like to add a moving garbage collector. However to do that I need the method variables to have typing information, otherwise I could modify a primitive value that looks like a pointer.
An obvious approach would be to encapsulate all (primitive and non-primitive) variables in a struct that has an extra (enum) variable for typing information, however this would cause memory and performance overhead, the transpiled code is namely meant for embedded platforms. If I were to accept the memory overhead the obvious option would be to use a heap handle for all objects and then I'd be able to freely move heap blocks. However I'm wondering if there's a more efficient better approach.
I've come up with a potential solution, namely to predeclare and group variables based whether they're primitives or not (I can do that in the transpiler), and add an offset variable to each method at the end (I need to be able to find it accurately when scanning the stack area), that tells me where the non-primitive variables begin and where they end, so I can only scan those. This means that each method will use an additional 16/32-bit (depending on arch) of memory, however this should still be more memory efficient than the heap handle approach.
Example:
void my_func() { int i = 5; int z = 3; bool b = false; void* person; void* person_info = ...; .... // logic volatile int offset = 0x034;}My aim is for something that works universally across GCC compilers, thus my concerns are:
- Can the compiler reorder the variables from how they're declared inthe source code?
- Can I force the compiler to put some data in themethod's stack frame (using volatile)?
- Can I find the offset accurately when scanning the stack?
I'd like to avoid assembly so this approach can work (by default) across multiple platforms, however I'm open for methods even if they involve assembly (if they're reliable).