Index: Python/compile.c
===================================================================
RCS file: /cvsroot/python/python/dist/src/Python/compile.c,v
retrieving revision 2.326
diff -u -r2.326 compile.c
--- Python/compile.c	31 Aug 2004 10:07:13 -0000	2.326
+++ Python/compile.c	21 Sep 2004 03:59:09 -0000
@@ -388,6 +388,50 @@
 #define CODESIZE(op)  (HAS_ARG(op) ? 3 : 1)
 #define ISBASICBLOCK(blocks, start, bytes) (blocks[start]==blocks[start+bytes-1])
 
+static int
+tuple_of_constants(unsigned char *codestr, int n, PyObject *consts)
+{
+	PyObject *newconst, *constant;
+	int i, arg, len_consts;
+
+	/* Pre-conditions */
+	assert(PyList_CheckExact(consts));
+	assert(codestr[0] == LOAD_CONST);
+	assert(codestr[n*3] == BUILD_TUPLE);
+	assert(GETARG(codestr, (n*3)) == n);
+
+	/* Verify chain of n load_constants */
+	for (i=0 ; i<n ; i++)
+		if (codestr[i*3] != LOAD_CONST)
+			return 0;
+
+	/* Buildup new tuple of constants */
+	newconst = PyTuple_New(n);
+	if (newconst == NULL)
+		return 0;
+	for (i=0 ; i<n ; i++) {
+		arg = GETARG(codestr, (i*3));
+		constant = PyList_GET_ITEM(consts, arg);
+		Py_INCREF(constant);
+		PyTuple_SET_ITEM(newconst, i, constant);
+	}
+
+	/* Append folded constant onto consts */
+	len_consts = PyList_GET_SIZE(consts);
+	if (PyList_Append(consts, newconst)) {
+		Py_DECREF(newconst);
+		return 0;
+	}
+	Py_DECREF(newconst);
+
+	/* Write NOPs over old LOAD_CONSTS and
+	   add a new LOAD_CONST newconst on top of the BUILD_TUPLE n */
+	memset(codestr, NOP, n*3);
+	codestr[n*3] = LOAD_CONST;
+	SETARG(codestr, (n*3), len_consts);
+	return 1;
+}
+
 static unsigned int *
 markblocks(unsigned char *code, int len)
 {
@@ -464,7 +508,7 @@
 	blocks = markblocks(codestr, codelen);
 	if (blocks == NULL)
 		goto exitUnchanged;
-	assert(PyTuple_Check(consts));
+	assert(PyList_Check(consts));
 
 	for (i=0, nops=0 ; i<codelen ; i += CODESIZE(codestr[i])) {
 		addrmap[i] = i - nops;
@@ -511,8 +555,8 @@
 			name = PyString_AsString(PyTuple_GET_ITEM(names, j));
 			if (name == NULL  ||  strcmp(name, "None") != 0)
 				continue;
-			for (j=0 ; j < PyTuple_GET_SIZE(consts) ; j++) {
-				if (PyTuple_GET_ITEM(consts, j) == Py_None) {
+			for (j=0 ; j < PyList_GET_SIZE(consts) ; j++) {
+				if (PyList_GET_ITEM(consts, j) == Py_None) {
 					codestr[i] = LOAD_CONST;
 					SETARG(codestr, i, j);
 					break;
@@ -526,16 +570,27 @@
 			if (codestr[i+3] != JUMP_IF_FALSE  ||
 			    codestr[i+6] != POP_TOP  ||
 			    !ISBASICBLOCK(blocks,i,7) ||
-			    !PyObject_IsTrue(PyTuple_GET_ITEM(consts, j)))
+			    !PyObject_IsTrue(PyList_GET_ITEM(consts, j)))
 				continue;
 			memset(codestr+i, NOP, 7);
 			nops += 7;
 			break;
 
-		/* Skip over BUILD_SEQN 1 UNPACK_SEQN 1.
+		/* Try to fold tuples of constants.
+		   Skip over BUILD_SEQN 1 UNPACK_SEQN 1.
 		   Replace BUILD_SEQN 2 UNPACK_SEQN 2 with ROT2.
 		   Replace BUILD_SEQN 3 UNPACK_SEQN 3 with ROT3 ROT2. */
 		case BUILD_TUPLE:
+			j = GETARG(codestr, i);
+			h = i - 3 * j;
+			if (h >= 0  &&
+			    codestr[h] == LOAD_CONST  && 
+			    ISBASICBLOCK(blocks, h, 3*(j+1))  &&
+			    tuple_of_constants(&codestr[h], j, consts)) {
+				nops += 3 * j;
+				break;
+			}
+			/* Intentional fall-through */
 		case BUILD_LIST:
 			j = GETARG(codestr, i);
 			if (codestr[i+3] != UNPACK_SEQUENCE  ||
@@ -4899,7 +4954,6 @@
 	if (sc.c_errors == 0) {
 		PyObject *consts, *names, *varnames, *filename, *name,
 			*freevars, *cellvars, *code;
-		consts = PyList_AsTuple(sc.c_consts);
 		names = PyList_AsTuple(sc.c_names);
 		varnames = PyList_AsTuple(sc.c_varnames);
 		cellvars = dict_keys_inorder(sc.c_cellvars, 0);
@@ -4907,7 +4961,8 @@
 					     PyTuple_GET_SIZE(cellvars));
 		filename = PyString_InternFromString(sc.c_filename);
 		name = PyString_InternFromString(sc.c_name);
-		code = optimize_code(sc.c_code, consts, names, sc.c_lnotab);
+		code = optimize_code(sc.c_code, sc.c_consts, names, sc.c_lnotab);
+		consts = PyList_AsTuple(sc.c_consts);
 		if (!PyErr_Occurred())
 			co = PyCode_New(sc.c_argcount,
 					sc.c_nlocals,
Index: Lib/test/test_peepholer.py
===================================================================
RCS file: /cvsroot/python/python/dist/src/Lib/test/test_peepholer.py,v
retrieving revision 1.2
diff -u -r1.2 test_peepholer.py
--- Lib/test/test_peepholer.py	26 Aug 2004 05:23:19 -0000	1.2
+++ Lib/test/test_peepholer.py	21 Sep 2004 03:59:09 -0000
@@ -64,15 +64,25 @@
 
     def test_pack_unpack(self):
         for line, elem in (
-            ('a, = 1,', 'LOAD_CONST',),
-            ('a, b = 1, 2', 'ROT_TWO',),
-            ('a, b, c = 1, 2, 3', 'ROT_THREE',),
+            ('a, = a,', 'LOAD_CONST',),
+            ('a, b = a, b', 'ROT_TWO',),
+            ('a, b, c = a, b, c', 'ROT_THREE',),
             ):
             asm = dis_single(line)
             self.assert_(elem in asm)
             self.assert_('BUILD_TUPLE' not in asm)
             self.assert_('UNPACK_TUPLE' not in asm)
 
+    def test_folding_of_tuples_of_constants(self):
+        for line, elem in (
+            ('a = 1,2,3', '((1, 2, 3))',),
+            ('a = ("a","b","c")', "(('a', 'b', 'c'))",),
+            ('a, b, c = a, b, c', 'ROT_THREE',),
+            ):
+            asm = dis_single(line)
+            self.assert_(elem in asm)
+            self.assert_('BUILD_TUPLE' not in asm)
+
     def test_elim_extra_return(self):
         # RETURN LOAD_CONST None RETURN  -->  RETURN
         def f(x):