[quietbritishjim]

I guess a really brute force way would be to have a huge dictionary mapping from "memory address" (really just an arbitrary number) to JVM object. malloc() would add to the dictionary and free() would remove an entry. Pointer dereference would look up in it but would need to be able to find the nearest lower entry (for when you have an array and dereference an entry in it, or use a pointer to a field in a struct).

I would hope that there's a much more efficient way to do it, this idea is just evidence that it could be done in principle. But I don't see what that more efficient way would be. You certainly need to keep a secret reference to each JVM object somehow because C doesn't require you to keep any pointer to an object e.g.

    intptr_t x = (intptr_t)malloc(sizeof(int));
    *(int*)x = 99;
    bool did_subtract_50 = false;
    if (x > 50) {
        did_subtract_50 = true;
        x -= 50;
    }
    // Now there is no pointer or even integer that contains the address
    
    // ... later ...
    // Retrieve the address and use and free it
    int* y = (int*)(x + 50 * did_subtract_50);
    printf("value: %d\n", *y);
    free(y);