Fix PyFrame_FastToLocals() and counterpart to deal with cells and

frees.  Note there doesn't seem to be any way to test LocalsToFast(),
because the instructions that trigger it are illegal in nested scopes
with free variables.

Fix allocation strategy for cells that are also formal parameters.
Instead of emitting LOAD_FAST / STORE_DEREF pairs for each parameter,
have the argument handling code in eval_code2() do the right thing.

A side-effect of this change is that cell variables that are also
arguments are listed at the front of co_cellvars in the order they
appear in the argument list.

Objects/frameobject.c

@@ -251,7 +251,51 @@ PyFrame_BlockPop(PyFrameObject *f)
 
 /* Convert between "fast" version of locals and dictionary version */
 
-/* XXX should also copy free variables and cell variables */
+void
+map_to_dict(PyObject *map, int nmap, PyObject *dict, PyObject **values,
+	    int deref)
+{
+	int j;
+	for (j = nmap; --j >= 0; ) {
+		PyObject *key = PyTuple_GetItem(map, j);
+		PyObject *value = values[j];
+		if (deref)
+			value = PyCell_GET(value);
+		if (value == NULL) {
+			PyErr_Clear();
+			if (PyDict_DelItem(dict, key) != 0)
+				PyErr_Clear();
+		}
+		else {
+			if (PyDict_SetItem(dict, key, value) != 0)
+				PyErr_Clear();
+		}
+	}
+}
+
+void
+dict_to_map(PyObject *map, int nmap, PyObject *dict, PyObject **values,
+	    int deref, int clear)
+{
+	int j;
+	for (j = nmap; --j >= 0; ) {
+		PyObject *key = PyTuple_GetItem(map, j);
+		PyObject *value = PyDict_GetItem(dict, key);
+		Py_XINCREF(value);
+		if (deref) {
+			if (value) {
+				if (PyCell_Set(values[j], value) < 0)
+					PyErr_Clear();
+			} else if (clear) {
+				Py_XDECREF(values[j]);
+				values[j] = value;
+			}
+		} else if (value != NULL || clear) {
+			Py_XDECREF(values[j]);
+			values[j] = value;
+		}
+	}
+}
 
 void
 PyFrame_FastToLocals(PyFrameObject *f)
@@ -281,18 +325,19 @@ PyFrame_FastToLocals(PyFrameObject *f)
 	j = PyTuple_Size(map);
 	if (j > f->f_nlocals)
 		j = f->f_nlocals;
-	for (; --j >= 0; ) {
-		PyObject *key = PyTuple_GetItem(map, j);
-		PyObject *value = fast[j];
-		if (value == NULL) {
-			PyErr_Clear();
-			if (PyDict_DelItem(locals, key) != 0)
-				PyErr_Clear();
-		}
-		else {
-			if (PyDict_SetItem(locals, key, value) != 0)
-				PyErr_Clear();
+	map_to_dict(map, j, locals, fast, 0);
+	if (f->f_ncells || f->f_nfreevars) {
+		if (!(PyTuple_Check(f->f_code->co_cellvars)
+		      && PyTuple_Check(f->f_code->co_freevars))) {
+			Py_DECREF(locals);
+			return;
 		}
+		map_to_dict(f->f_code->co_cellvars, 
+			    PyTuple_GET_SIZE(f->f_code->co_cellvars),
+			    locals, fast + f->f_nlocals, 1);
+		map_to_dict(f->f_code->co_freevars, 
+			    PyTuple_GET_SIZE(f->f_code->co_freevars),
+			    locals, fast + f->f_nlocals + f->f_ncells, 1);
 	}
 	PyErr_Restore(error_type, error_value, error_traceback);
 }
@@ -318,14 +363,17 @@ PyFrame_LocalsToFast(PyFrameObject *f, int clear)
 	j = PyTuple_Size(map);
 	if (j > f->f_nlocals)
 		j = f->f_nlocals;
-	for (; --j >= 0; ) {
-		PyObject *key = PyTuple_GetItem(map, j);
-		PyObject *value = PyDict_GetItem(locals, key);
-		Py_XINCREF(value);
-		if (value != NULL || clear) {
-			Py_XDECREF(fast[j]);
-			fast[j] = value;
-		}
+	dict_to_map(f->f_code->co_varnames, j, locals, fast, 0, clear);
+	if (f->f_ncells || f->f_nfreevars) {
+		if (!(PyTuple_Check(f->f_code->co_cellvars)
+		      && PyTuple_Check(f->f_code->co_freevars)))
+			return;
+		dict_to_map(f->f_code->co_cellvars, 
+			    PyTuple_GET_SIZE(f->f_code->co_cellvars),
+			    locals, fast, 1, clear);
+		dict_to_map(f->f_code->co_freevars, 
+			    PyTuple_GET_SIZE(f->f_code->co_freevars),
+			    locals, fast, 1, clear);
 	}
 	PyErr_Restore(error_type, error_value, error_traceback);
 }

Python/ceval.c

@@ -570,11 +570,52 @@ eval_code2(PyCodeObject *co, PyObject *globals, PyObject *locals,
 			goto fail;
 		}
 	}
-	/* Allocate storage for cell vars and copy free vars into frame */ 
+	/* Allocate and initialize storage for cell vars, and copy free
+	   vars into frame.  This isn't too efficient right now. */
 	if (f->f_ncells) {
-		int i;
-		for (i = 0; i < f->f_ncells; ++i)
-			freevars[i] = PyCell_New(NULL);
+		int i = 0, j = 0, nargs, found;
+		char *cellname, *argname;
+		PyObject *c;
+
+		nargs = co->co_argcount;
+		if (co->co_flags & CO_VARARGS)
+			nargs++;
+		if (co->co_flags & CO_VARKEYWORDS)
+			nargs++;
+
+		/* Check for cells that shadow args */
+		for (i = 0; i < f->f_ncells && j < nargs; ++i) {
+			cellname = PyString_AS_STRING(
+				PyTuple_GET_ITEM(co->co_cellvars, i));
+			found = 0;
+			while (j < nargs) {
+				argname = PyString_AS_STRING(
+					PyTuple_GET_ITEM(co->co_varnames, j));
+				if (strcmp(cellname, argname) == 0) {
+					c = PyCell_New(GETLOCAL(j));
+					if (c == NULL)
+						goto fail;
+					GETLOCAL(f->f_nlocals + i) = c;
+					found = 1;
+					break;
+				}
+				j++;
+			}
+			if (found == 0) {
+				c = PyCell_New(NULL);
+				if (c == NULL)
+					goto fail;
+				SETLOCAL(f->f_nlocals + i, c);
+			}
+		}
+		/* Initialize any that are left */
+		while (i < f->f_ncells) {
+			c = PyCell_New(NULL);
+			if (c == NULL)
+				goto fail;
+			SETLOCAL(f->f_nlocals + i, c);
+			i++;
+		}
 	}
 	if (f->f_nfreevars) {
 		int i;

Python/compile.c

@@ -3552,16 +3552,7 @@ com_arglist(struct compiling *c, node *n)
 			break;
 		REQ(ch, fpdef); /* fpdef: NAME | '(' fplist ')' */
 		fp = CHILD(ch, 0);
-		if (TYPE(fp) == NAME) {
-			PyObject *v;
-			name = STR(fp); 
-			v = PyDict_GetItemString(c->c_cellvars, name);
-			if (v) {
-				com_addoparg(c, LOAD_FAST, narg);
-				com_addoparg(c, STORE_DEREF, 
-					     PyInt_AS_LONG(v));
-			}
-		} else {
+		if (TYPE(fp) != NAME) {
 			name = nbuf;
 			sprintf(nbuf, ".%d", i);
 			complex = 1;
@@ -3576,47 +3567,6 @@ com_arglist(struct compiling *c, node *n)
 		else
 			REQ(ch, COMMA);
 	}
-	/* Handle *arguments */
-	if (i < nch) {
-		node *ch;
-		ch = CHILD(n, i);
-		if (TYPE(ch) != DOUBLESTAR) {
-			REQ(ch, STAR);
-			ch = CHILD(n, i+1);
-			if (TYPE(ch) == NAME) {
-				PyObject *v;
-				i += 3;
-				v = PyDict_GetItemString(c->c_cellvars,
-							 STR(ch));
-				if (v) {
-					com_addoparg(c, LOAD_FAST, narg);
-					com_addoparg(c, STORE_DEREF, 
-						     PyInt_AS_LONG(v));
-			}
-				narg++;
-		}
-	}
-	}
-	/* Handle **keywords */
-	if (i < nch) {
-		PyObject *v;
-		node *ch;
-		ch = CHILD(n, i);
-		if (TYPE(ch) != DOUBLESTAR) {
-			REQ(ch, STAR);
-			ch = CHILD(n, i+1);
-			REQ(ch, STAR);
-			ch = CHILD(n, i+2);
-		}
-		else
-			ch = CHILD(n, i+1);
-		REQ(ch, NAME);
-		v = PyDict_GetItemString(c->c_cellvars, STR(ch));
-		if (v) {
-			com_addoparg(c, LOAD_FAST, narg);
-			com_addoparg(c, STORE_DEREF, PyInt_AS_LONG(v));
-		}			
-	}
 	if (complex) {
 		/* Generate code for complex arguments only after
 		   having counted the simple arguments */
@@ -4137,6 +4087,69 @@ symtable_resolve_free(struct compiling *c, PyObject *name,
 	return 0;
 }
 
+/* If a variable is a cell and an argument, make sure that appears in
+   co_cellvars before any variable to its right in varnames. 
+*/
+
+
+static int
+symtable_cellvar_offsets(PyObject **cellvars, int argcount, 
+			 PyObject *varnames, int flags) 
+{
+	PyObject *v, *w, *d, *list = NULL;
+	int i, pos;
+
+	if (flags & CO_VARARGS)
+		argcount++;
+	if (flags & CO_VARKEYWORDS)
+		argcount++;
+	for (i = argcount; --i >= 0; ) {
+		v = PyList_GET_ITEM(varnames, i);
+		if (PyDict_GetItem(*cellvars, v)) {
+			if (list == NULL) {
+				list = PyList_New(1);
+				if (list == NULL)
+					return -1;
+				PyList_SET_ITEM(list, 0, v);
+				Py_INCREF(v);
+			} else
+				PyList_Insert(list, 0, v);
+		}
+	}
+	if (list == NULL || PyList_GET_SIZE(list) == 0)
+		return 0;
+	/* There are cellvars that are also arguments.  Create a dict
+	   to replace cellvars and put the args at the front.
+	*/
+	d = PyDict_New();
+	for (i = PyList_GET_SIZE(list); --i >= 0; ) {
+		v = PyInt_FromLong(i);
+		if (v == NULL) 
+			goto fail;
+		if (PyDict_SetItem(d, PyList_GET_ITEM(list, i), v) < 0)
+			goto fail;
+		if (PyDict_DelItem(*cellvars, PyList_GET_ITEM(list, i)) < 0)
+			goto fail;
+	}
+	pos = 0;
+	i = PyList_GET_SIZE(list);
+	Py_DECREF(list);
+	while (PyDict_Next(*cellvars, &pos, &v, &w)) {
+		w = PyInt_FromLong(i++);  /* don't care about the old key */
+		if (PyDict_SetItem(d, v, w) < 0) {
+			Py_DECREF(w);
+			goto fail;
+		}
+		Py_DECREF(w);
+	}
+	Py_DECREF(*cellvars);
+	*cellvars = d;
+	return 1;
+ fail:
+	Py_DECREF(d);
+	return -1;
+}
+
 static int
 symtable_freevar_offsets(PyObject *freevars, int offset)
 {
@@ -4386,6 +4399,11 @@ symtable_load_symbols(struct compiling *c)
 		}
 	}
 
+	if (si.si_ncells > 1) { /* one cell is always in order */
+		if (symtable_cellvar_offsets(&c->c_cellvars, c->c_argcount,
+					     c->c_varnames, c->c_flags) < 0)
+			return -1;
+	}
 	if (symtable_freevar_offsets(c->c_freevars, si.si_ncells) < 0)
 		return -1;
 	return symtable_update_flags(c, ste, &si);