python · markshannon · Sep 14, 2021 · Sep 9, 2021 · Sep 12, 2021 · Sep 13, 2021
diff --git a/Include/opcode.h b/Include/opcode.h
@@ -1638,14 +1638,14 @@ compiler_addop_j_noline(struct compiler *c, int opcode, basicblock *b)
 }

 #define ADDOP_O(C, OP, O, TYPE) { \
-    assert((OP) != LOAD_CONST); /* use ADDOP_LOAD_CONST */ \
+    assert(!HAS_CONST(OP)); /* use ADDOP_LOAD_CONST */ \
    if (!compiler_addop_o((C), (OP), (C)->u->u_ ## TYPE, (O))) \
        return 0; \
 }

 /* Same as ADDOP_O, but steals a reference. */
 #define ADDOP_N(C, OP, O, TYPE) { \
-    assert((OP) != LOAD_CONST); /* use ADDOP_LOAD_CONST_NEW */ \
+    assert(!HAS_CONST(OP)); /* use ADDOP_LOAD_CONST_NEW */ \
    if (!compiler_addop_o((C), (OP), (C)->u->u_ ## TYPE, (O))) { \
        Py_DECREF((O)); \
        return 0; \
@@ -7951,6 +7951,24 @@ assemble(struct compiler *c, int addNone)
    return co;
 }

+static PyObject*
+get_const_value(int opcode, int oparg, PyObject *co_consts)
+{
+    PyObject *constant = NULL;
+    assert(HAS_CONST(opcode));
+    if (opcode == LOAD_CONST) {
+        constant = PyList_GET_ITEM(co_consts, oparg);
+    }
+
+    if (constant == NULL) {
+        PyErr_SetString(PyExc_SystemError,
+                        "Internal error: failed to get value of a constant");
+        return NULL;
+    }
+    Py_INCREF(constant);
+    return constant;
+}
+
 /* Replace LOAD_CONST c1, LOAD_CONST c2 ... LOAD_CONST cn, BUILD_TUPLE n
   with    LOAD_CONST (c1, c2, ... cn).
   The consts table must still be in list form so that the
@@ -7968,7 +7986,7 @@ fold_tuple_on_constants(struct compiler *c,
    assert(inst[n].i_oparg == n);

    for (int i = 0; i < n; i++) {
-        if (inst[i].i_opcode != LOAD_CONST) {
+        if (!HAS_CONST(inst[i].i_opcode)) {
            return 0;
        }
    }
@@ -7979,9 +7997,12 @@ fold_tuple_on_constants(struct compiler *c,
        return -1;
    }
    for (int i = 0; i < n; i++) {
+        int op = inst[i].i_opcode;
        int arg = inst[i].i_oparg;
-        PyObject *constant = PyList_GET_ITEM(consts, arg);
-        Py_INCREF(constant);
+        PyObject *constant = get_const_value(op, arg, consts);
+        if (constant == NULL) {
+            return -1;
+        }
        PyTuple_SET_ITEM(newconst, i, constant);
    }
    if (merge_const_one(c, &newconst) == 0) {
@@ -8107,8 +8128,12 @@ optimize_basic_block(struct compiler *c, basicblock *bb, PyObject *consts)
                switch(nextop) {
                    case POP_JUMP_IF_FALSE:
                    case POP_JUMP_IF_TRUE:
-                        cnt = PyList_GET_ITEM(consts, oparg);
+                        cnt = get_const_value(inst->i_opcode, oparg, consts);
+                        if (cnt == NULL) {
+                            goto error;
+                        }
                        is_true = PyObject_IsTrue(cnt);
+                        Py_DECREF(cnt);
                        if (is_true == -1) {
                            goto error;
                        }
@@ -8124,8 +8149,12 @@ optimize_basic_block(struct compiler *c, basicblock *bb, PyObject *consts)
                        break;
                    case JUMP_IF_FALSE_OR_POP:
                    case JUMP_IF_TRUE_OR_POP:
-                        cnt = PyList_GET_ITEM(consts, oparg);
+                        cnt = get_const_value(inst->i_opcode, oparg, consts);
+                        if (cnt == NULL) {
+                            goto error;
+                        }
                        is_true = PyObject_IsTrue(cnt);
+                        Py_DECREF(cnt);
                        if (is_true == -1) {
                            goto error;
                        }
@@ -8310,6 +8339,9 @@ optimize_basic_block(struct compiler *c, basicblock *bb, PyObject *consts)
                    fold_rotations(inst - oparg + 1, oparg);
                }
                break;
+            default:
+                /* All HAS_CONST opcodes should be handled with LOAD_CONST */
+                assert (!HAS_CONST(inst->i_opcode));
        }
    }
    return 0;

diff --git a/Tools/scripts/generate_opcode_h.py b/Tools/scripts/generate_opcode_h.py
@@ -51,6 +51,7 @@ def main(opcode_py, outfile='Include/opcode.h'):
        code = fp.read()
    exec(code, opcode)
    opmap = opcode['opmap']
+    hasconst = opcode['hasconst']
    hasjrel = opcode['hasjrel']
    hasjabs = opcode['hasjabs']
    used = [ False ] * 256
@@ -65,15 +66,24 @@ def main(opcode_py, outfile='Include/opcode.h'):
            if name == 'POP_EXCEPT': # Special entry for HAVE_ARGUMENT
                fobj.write("#define %-23s %3d\n" %
                            ('HAVE_ARGUMENT', opcode['HAVE_ARGUMENT']))
+
        for name in opcode['_specialized_instructions']:
            while used[next_op]:
                next_op += 1
            fobj.write("#define %-23s %3s\n" % (name, next_op))
            used[next_op] = True
+
        fobj.write("#ifdef NEED_OPCODE_JUMP_TABLES\n")
        write_int_array_from_ops("_PyOpcode_RelativeJump", opcode['hasjrel'], fobj)
        write_int_array_from_ops("_PyOpcode_Jump", opcode['hasjrel'] + opcode['hasjabs'], fobj)
        fobj.write("#endif /* OPCODE_TABLES */\n")
+
+        fobj.write("\n")
+        fobj.write("#define HAS_CONST(op) (false\\")
+        for op in hasconst:
+            fobj.write(f"\n    || ((op) == {op}) \\")
+        fobj.write("\n    )\n")
+
        fobj.write(footer)