intobject.c: Save references to small integers, so that they can be

shared.  The default is to save references to the integers in
	the range -1..99.  The lower limit can be set by defining
	NSMALLNEGINTS (absolute value of smallest integer to be saved)
	and NSMALLPOSINTS (1 more than the largest integer to be
	saved).
tupleobject.c: Save a reference to the empty tuple to be returned
	whenever a tuple of size 0 is requested.  Tuples of size 1
	upto, but not including, MAXSAVESIZE (default 20) are put in
	free lists when deallocated.  When MAXSAVESIZE equals 1, only
	share references to the empty tuple, when MAXSAVESIZE equals
	0, don't include the code at all and revert to the old
	behavior.
object.c: Print some more statistics when COUNT_ALLOCS is defined.

Objects/intobject.c

@@ -75,12 +75,42 @@ fill_free_list()
 }
 
 static intobject *free_list = NULL;
+#ifndef NSMALLPOSINTS
+#define NSMALLPOSINTS		100
+#endif
+#ifndef NSMALLNEGINTS
+#define NSMALLNEGINTS		1
+#endif
+#if NSMALLNEGINTS + NSMALLPOSINTS > 0
+/* References to small integers are saved in this array so that they
+   can be shared.
+   The integers that are saved are those in the range
+   -NSMALLNEGINTS (inclusive) to NSMALLPOSINTS (not inclusive).
+*/
+static intobject *small_ints[NSMALLNEGINTS + NSMALLPOSINTS];
+#endif
+#ifdef COUNT_ALLOCS
+int quick_int_allocs, quick_neg_int_allocs;
+#endif
 
 object *
 newintobject(ival)
 	long ival;
 {
 	register intobject *v;
+#if NSMALLNEGINTS + NSMALLPOSINTS > 0
+	if (-NSMALLNEGINTS <= ival && ival < NSMALLPOSINTS &&
+	    (v = small_ints[ival + NSMALLNEGINTS]) != NULL) {
+		INCREF(v);
+#ifdef COUNT_ALLOCS
+		if (ival >= 0)
+			quick_int_allocs++;
+		else
+			quick_neg_int_allocs++;
+#endif
+		return (object *) v;
+	}
+#endif
 	if (free_list == NULL) {
 		if ((free_list = fill_free_list()) == NULL)
 			return NULL;
@@ -90,6 +120,13 @@ newintobject(ival)
 	v->ob_type = &Inttype;
 	v->ob_ival = ival;
 	NEWREF(v);
+#if NSMALLNEGINTS + NSMALLPOSINTS > 0
+	if (-NSMALLNEGINTS <= ival && ival < NSMALLPOSINTS) {
+		/* save this one for a following allocation */
+		INCREF(v);
+		small_ints[ival + NSMALLNEGINTS] = v;
+	}
+#endif
 	return (object *) v;
 }
 

Objects/object.c

@@ -36,15 +36,21 @@ long ref_total;
 
 #ifdef COUNT_ALLOCS
 static typeobject *type_list;
-
+extern int tuple_zero_allocs, fast_tuple_allocs;
+extern int quick_int_allocs, quick_neg_int_allocs;
 void
 dump_counts()
 {
 	typeobject *tp;
 
 	for (tp = type_list; tp; tp = tp->tp_next)
-		printf("%s %d %d %d\n", tp->tp_name, tp->tp_alloc, tp->tp_free,
+		printf("%s alloc'd: %d, freed: %d, max in use: %d\n",
+		       tp->tp_name, tp->tp_alloc, tp->tp_free,
 		       tp->tp_maxalloc);
+	printf("fast tuple allocs: %d, empty: %d\n", fast_tuple_allocs,
+	       tuple_zero_allocs);
+	printf("fast int allocs: pos: %d, neg: %d\n", quick_int_allocs,
+	       quick_neg_int_allocs);
 }
 
 void

Objects/tupleobject.c

@@ -26,6 +26,21 @@ OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 
 #include "allobjects.h"
 
+#ifndef MAXSAVESIZE
+#define MAXSAVESIZE	20
+#endif
+
+#if MAXSAVESIZE > 0
+/* Entries 1 upto MAXSAVESIZE are free lists, entry 0 is the empty
+   tuple () of which at most one instance will be allocated.
+*/
+static tupleobject *free_list[MAXSAVESIZE];
+#endif
+#ifdef COUNT_ALLOCS
+int fast_tuple_allocs;
+int tuple_zero_allocs;
+#endif
+
 object *
 newtupleobject(size)
 	register int size;
@@ -36,15 +51,39 @@ newtupleobject(size)
 		err_badcall();
 		return NULL;
 	}
+#if MAXSAVESIZE > 0
+	if (size == 0 && free_list[0]) {
+		op = free_list[0];
+		INCREF(op);
+#ifdef COUNT_ALLOCS
+		tuple_zero_allocs++;
+#endif
+		return (object *) op;
+	}
+	if (0 < size && size < MAXSAVESIZE && (op = free_list[size]) != NULL) {
+		free_list[size] = (tupleobject *) op->ob_item[0];
+#ifdef COUNT_ALLOCS
+		fast_tuple_allocs++;
+#endif
+	} else
+#endif
+	{
 		op = (tupleobject *)
 			malloc(sizeof(tupleobject) + size * sizeof(object *));
 		if (op == NULL)
 			return err_nomem();
+	}
 	op->ob_type = &Tupletype;
 	op->ob_size = size;
 	for (i = 0; i < size; i++)
 		op->ob_item[i] = NULL;
 	NEWREF(op);
+#if MAXSAVESIZE > 0
+	if (size == 0) {
+		free_list[0] = op;
+		INCREF(op);	/* extra INCREF so that this is never freed */
+	}
+#endif
 	return (object *) op;
 }
 
@@ -113,6 +152,12 @@ tupledealloc(op)
 		if (op->ob_item[i] != NULL)
 			DECREF(op->ob_item[i]);
 	}
+#if MAXSAVESIZE > 0
+	if (0 < op->ob_size && op->ob_size < MAXSAVESIZE) {
+		op->ob_item[0] = (object *) free_list[op->ob_size];
+		free_list[op->ob_size] = op;
+	} else
+#endif
 		free((ANY *)op);
 }