[m-dev.] New type_layout traversal code

[Fergus Henderson]

Oliver Hutchison, you wrote:
> 
> process_float :
> 	/* XXX : this wont work for boxed floats! */
> 	return data_word;

Try

#ifdef BOXED_FLOAT
	if (in_range(data_value)) {
		return float_to_word(word_to_float(data_word));
	}	
#endif
	return data_word;

> process_simple :
> 	/* If the argument vector is in range, copy the
> 	** arguments.
> 	**/
> 	if (in_range(data_value)) {
> 		int i;
> 		Word arity = ((Word *)entry_value)[
> 			TYPELAYOUT_SIMPLE_ARITY_OFFSET];
> 		Word * type_info_vector = ((Word *) entry_value) + 
> 				TYPELAYOUT_SIMPLE_ARGS_OFFSET;
> 
> 		/* allocate space for new args. */
> 		incr_saved_hp(new_data, arity);
> 
> 		/* copy arguments */
> 		for (i = 0; i < arity; i++) {
> 			bool allocated;
> 			Word * new_type_info = make_type_info(type_info,
> 			(Word *) type_info_vector[i], &allocated);
> 			field(0, new_data, i) = 
> 				deep_copy(((Word *) data_value)[i],
>     					new_type_info, lower_limit, 
> 					upper_limit); 
> 			if (allocated) { 
> 				free(new_type_info);
> 			}
> 		}
> 		/* tag this pointer */
> 		new_data = (Word) mkword(data_tag, new_data);
> 	} else {
> 		new_data = data_word;
> 	}
> 	return new_data;
> process_complicated :
> 	if (in_range(data_value)) {
> 		Word secondary_tag = ((Word *) data_value)[0];
> 		Word new_entry_value = ((Word *) entry_value)[secondary_tag + 
> 				TYPELAYOUT_COMPLIC_ENTRY_OFFSET];
> 		Word new_entry_tag = tag(entry_value);
> 		Word new_entry_body = body(new_entry_value, new_entry_tag);
> 		Word new_data_value  = (Word) ((Word *) data_value)[1];
> 		data_value = new_data_value;
> 		entry_value = new_entry_body;
> 		goto process_simple;
> 	} else {
> 		return data_word;
> 	}

That is a particularly awful kind of goto, because
there is no indication at the label that it is the target
of more than one goto, or that "process_simple" is in fact
used for processing complicated tags.

-- 
Fergus Henderson <fjh at cs.mu.oz.au>   |  "I have always known that the pursuit
WWW: <http://www.cs.mu.oz.au/~fjh>   |  of excellence is a lethal habit"
PGP: finger fjh at 128.250.37.3         |     -- the last words of T. S. Garp.