Many thanks! It looks like I just didn't do enough probing into the file strucure!
I've also just discovered this brief paper:
that briefly states a not-so-pretty but definitive way to map the register addresses to variables. It looks like this:
#define PORTA (* (volatile unsigned char *) 0x38)
I'd imagine that a 32-bit microcontroller would have a snippet of code more like this:
#define IOD_OWER (* (volatile unsigned int *) 0x400E14A0)