a few peephole optimizations

Objects/dictobject.c

@@ -133,7 +133,7 @@ lookmapping(mp, key, hash)
 	   and 0 < incr < ma_size and both are a function of hash */
 	i = sum % mp->ma_size;
 	do {
-		sum = sum + sum + sum + 1;
+		sum = 3*sum + 1;
 		incr = sum % mp->ma_size;
 	} while (incr == 0);
 	for (;;) {

Objects/listobject.c

@@ -120,6 +120,7 @@ setlistitem(op, i, newitem)
 	register object *newitem;
 {
 	register object *olditem;
+	register object **p;
 	if (!is_listobject(op)) {
 		XDECREF(newitem);
 		err_badcall();
@@ -130,8 +131,9 @@ setlistitem(op, i, newitem)
 		err_setstr(IndexError, "list assignment index out of range");
 		return -1;
 	}
-	olditem = ((listobject *)op) -> ob_item[i];
-	((listobject *)op) -> ob_item[i] = newitem;
+	p = ((listobject *)op) -> ob_item + i;
+	olditem = *p;
+	*p = newitem;
 	XDECREF(olditem);
 	return 0;
 }

Objects/mappingobject.c

@@ -133,7 +133,7 @@ lookmapping(mp, key, hash)
 	   and 0 < incr < ma_size and both are a function of hash */
 	i = sum % mp->ma_size;
 	do {
-		sum = sum + sum + sum + 1;
+		sum = 3*sum + 1;
 		incr = sum % mp->ma_size;
 	} while (incr == 0);
 	for (;;) {

Objects/stringobject.c

@@ -419,7 +419,7 @@ string_hash(a)
 	p = (unsigned char *) a->ob_sval;
 	x = *p << 7;
 	while (--len >= 0)
-		x = (x + x + x) ^ *p++;
+		x = (3*x) ^ *p++;
 	x ^= a->ob_size;
 	if (x == -1)
 		x = -2;

Objects/tupleobject.c

@@ -119,9 +119,10 @@ int
 settupleitem(op, i, newitem)
 	register object *op;
 	register int i;
-	register object *newitem;
+	object *newitem;
 {
 	register object *olditem;
+	register object **p;
 	if (!is_tupleobject(op)) {
 		XDECREF(newitem);
 		err_badcall();
@@ -132,8 +133,9 @@ settupleitem(op, i, newitem)
 		err_setstr(IndexError, "tuple assignment index out of range");
 		return -1;
 	}
-	olditem = ((tupleobject *)op) -> ob_item[i];
-	((tupleobject *)op) -> ob_item[i] = newitem;
+	p = ((tupleobject *)op) -> ob_item + i;
+	olditem = *p;
+	*p = newitem;
 	XDECREF(olditem);
 	return 0;
 }