Treat None as a constant.

diff --git a/Misc/NEWS b/Misc/NEWS
index 1619d060c10b6989d123037fdad3f17a579be054..151d3bf3f36570f7a6a5c9b7532e4fbe9bb20108 100644 (file)
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -26,6 +26,8 @@ Core and builtins
 - Added C macros Py_CLEAR and Py_VISIT to ease the implementation of
   types that support garbage collection.
 
+- Compiler now treats None as a constant.
+
 Extension modules
 -----------------
 

diff --git a/Python/compile.c b/Python/compile.c
index 0d230d643a1540e69b142d9dabefdb74c53dc95d..ca8dd266ffe3cc6f49339806c6f7a843a08bee2c 100644 (file)
--- a/Python/compile.c
+++ b/Python/compile.c
@@ -363,12 +363,13 @@ markblocks(unsigned char *code, int len)
 }
 
 static PyObject *
-optimize_code(PyObject *code, PyObject* consts)
+optimize_code(PyObject *code, PyObject* consts, PyObject *names)
 {
        int i, j, codelen;
        int tgt, tgttgt, opcode;
        unsigned char *codestr;
        unsigned int *blocks;
+       char *name;
 
        /* Make a modifiable copy of the code string */
        if (!PyString_Check(code))
@@ -418,6 +419,21 @@ optimize_code(PyObject *code, PyObject* consts)
                         continue;
                        SETARG(codestr, i, (j^1));
                        codestr[i+3] = NOP;
+               
+               /* Replace LOAD_GLOBAL/LOAD_NAME None with LOAD_CONST None */
+               case LOAD_NAME:
+               case LOAD_GLOBAL:
+                       j = GETARG(codestr, i);
+                       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) {
+                                       codestr[i] = LOAD_CONST;
+                                       SETARG(codestr, i, j);
+                                       break;
+                               }
+                       }
                        break;
 
                /* Skip over LOAD_CONST trueconst  JUMP_IF_FALSE xx  POP_TOP. 
@@ -441,7 +457,7 @@ optimize_code(PyObject *code, PyObject* consts)
                                continue;
                        if (!ISBASICBLOCK(blocks,i,6))
                                continue;
-                       if (GETARG(codestr, i) == 2 && \
+                       if (GETARG(codestr, i) == 2 &&
                            GETARG(codestr, i+3) == 2) {
                                codestr[i] = ROT_TWO;
                                codestr[i+1] = JUMP_FORWARD;
@@ -450,7 +466,7 @@ optimize_code(PyObject *code, PyObject* consts)
                                codestr[i+5] = NOP;
                                continue;
                        } 
-                       if (GETARG(codestr, i) == 3 && \
+                       if (GETARG(codestr, i) == 3 &&
                            GETARG(codestr, i+3) == 3) {
                                codestr[i] = ROT_THREE;
                                codestr[i+1] = ROT_TWO;
@@ -542,7 +558,7 @@ PyCode_New(int argcount, int nlocals, int stacksize, int flags,
                co->co_nlocals = nlocals;
                co->co_stacksize = stacksize;
                co->co_flags = flags;
-               co->co_code = optimize_code(code, consts);
+               co->co_code = optimize_code(code, consts, names);
                Py_INCREF(consts);
                co->co_consts = consts;
                Py_INCREF(names);