Allow tests for full overlap of defs.

Not actually used yet, but I imagine I'll want it.

tools/qfcc/include/def.h

@@ -251,7 +251,8 @@ void initialize_def (struct symbol_s *sym, struct type_s *type,
 
 	\param d1		The first def to check. May be an alias def.
 	\param d2		The second def to check. May be an alias def.
-	\return			1 if the defs overlap, 0 otherwise.
+	\return			1 if the defs overlap, 2 if \a d1 fully overlaps \a d2,
+					otherwise 0.
 */
 int def_overlap (def_t *d1, def_t *d2);
 
@@ -293,8 +294,9 @@ int def_size (def_t *def);
 	function will return.
 
 	\param def		The def representing the alias cluster to visit.
-	\param overlap  If true, then only defs that overlap \a def will be
-					visited.
+	\param overlap  If non-zero, then only defs that overlap \a def will
+					be visited. If 2, then the given def must fully overlap
+					the visited def.
 	\param visit	The function to call when visiting a def. The first
 					parameter is the def being visited, and the second
 					parameter is \a data passed on. If non-zero is returned,

tools/qfcc/source/def.c

@@ -615,8 +615,10 @@ def_overlap (def_t *d1, def_t *d2)
 		offs2 += d2->alias->offset;
 	size2 = type_size (d2->type);
 
+	if (offs1 <= offs2 && offs1 + size1 >= offs2 + size2)
+		return 2;	// d1 fully overlaps d2
 	if (offs1 < offs2 + size2 && offs2 < offs1 + size1)
-		return 1;
+		return 1;	// d1 and d2 at least partially overlap
 	return 0;
 }
 
@@ -652,7 +654,7 @@ def_visit_all (def_t *def, int overlap,
 	for (def = def->alias_defs; def; def = def->next) {
 		if (def == start_def)
 			continue;
-		if (overlap && !def_overlap (def, start_def))
+		if (overlap && def_overlap (def, start_def) < overlap)
 			continue;
 		if ((ret = visit (def, data)))
 			return ret;