translateRecordAccess.java

	public void translate(Expr.RecordAccess e, Location target, Context context) {
		// Determine the field offset
		Type.Record type = (Type.Record) typeOf(e.getSource());
		int offset = getFieldOffset(type, e.getName());
		
		// Translate source expression into a temporary stack location. This is
		// unfortunately a little inefficient in some cases, as we could
		// potentially avoid all memory usage. But, it will do for now!
		// Note that 'llocateLocation' modifies the stack pointer so it invalidates
		// 'target' if target is stack relative.
		MemoryLocation recordLocation = (MemoryLocation)allocateLocation(e.getSource(), context);
		translate(e.getSource(), recordLocation, context);
		
		// get the absolute (i.e. non stack-relative) location of the record then 
		// free the location reserved for the record.
		// 'recordBase' now points beyond the end of the stack to the record but 
		// the stack is as it was when we entered the function, so if 'target' is
		// stack-relative then it becomes correct again.
		RegisterLocation recordBase = context.selectFreeRegister(new Type.Int());
		bitwiseCopy(new RegisterLocation(new Type.Int(), recordLocation.base), recordBase, context);
		context = context.lockLocation(recordBase);
		freeLocations(context, recordLocation);

		// Finally, copy bits into target location
		MemoryLocation fieldLocation = new MemoryLocation(target.type(), recordBase.register, recordLocation.offset + offset);
		bitwiseCopy(fieldLocation, target, context);
		context = context.unlockLocation(recordBase);
	}