Issue #19722: Added opcode.stack_effect(), which accurately

computes the stack effect of bytecode instructions.

1 files changed, 116 insertions, 0 deletions

diff --git a/Modules/_opcode.c b/Modules/_opcode.c
new file mode 100644
index 0000000000..c53f0e04d6
--- /dev/null
+++ b/Modules/_opcode.c
@@ -0,0 +1,116 @@
+#include "Python.h"
+#include "opcode.h"
+
+
+/*[clinic]
+
+module _opcode
+
+_opcode.stack_effect -> int
+
+  opcode: int
+
+  [
+  oparg: int
+  ]
+  /
+
+Compute the stack effect of the opcode.
+[clinic]*/
+
+PyDoc_STRVAR(_opcode_stack_effect__doc__,
+"Compute the stack effect of the opcode.\n"
+"\n"
+"_opcode.stack_effect(opcode, [oparg])");
+
+#define _OPCODE_STACK_EFFECT_METHODDEF    \
+    {"stack_effect", (PyCFunction)_opcode_stack_effect, METH_VARARGS, _opcode_stack_effect__doc__},
+
+static int
+_opcode_stack_effect_impl(PyObject *module, int opcode, int group_right_1, int oparg);
+
+static PyObject *
+_opcode_stack_effect(PyObject *module, PyObject *args)
+{
+    PyObject *return_value = NULL;
+    int opcode;
+    int group_right_1 = 0;
+    int oparg = 0;
+    int _return_value;
+
+    switch (PyTuple_Size(args)) {
+        case 1:
+            if (!PyArg_ParseTuple(args, "i:stack_effect", &opcode))
+                return NULL;
+            break;
+        case 2:
+            if (!PyArg_ParseTuple(args, "ii:stack_effect", &opcode, &oparg))
+                return NULL;
+            group_right_1 = 1;
+            break;
+        default:
+            PyErr_SetString(PyExc_TypeError, "_opcode.stack_effect requires 1 to 2 arguments");
+            return NULL;
+    }
+    _return_value = _opcode_stack_effect_impl(module, opcode, group_right_1, oparg);
+    if ((_return_value == -1) && PyErr_Occurred())
+        goto exit;
+    return_value = PyLong_FromLong((long)_return_value);
+
+exit:
+    return return_value;
+}
+
+static int
+_opcode_stack_effect_impl(PyObject *module, int opcode, int group_right_1, int oparg)
+/*[clinic checksum: 2312ded40abc9bcbce718942de21f53e61a2dfd3]*/
+{
+    int effect;
+    if (HAS_ARG(opcode)) {        
+        if (!group_right_1) {
+            PyErr_SetString(PyExc_ValueError,
+                    "stack_effect: opcode requires oparg but oparg was not specified");
+            return -1;
+        }
+    }
+    else if (group_right_1) {
+        PyErr_SetString(PyExc_ValueError,
+                "stack_effect: opcode does not permit oparg but oparg was specified");
+        return -1;
+    }
+    effect = PyCompile_OpcodeStackEffect(opcode, oparg);
+    if (effect == PY_INVALID_STACK_EFFECT) {
+            PyErr_SetString(PyExc_ValueError,
+                    "invalid opcode or oparg");
+            return -1;
+    }
+    return effect;
+}
+
+
+
+
+static PyMethodDef
+opcode_functions[] =  {
+    _OPCODE_STACK_EFFECT_METHODDEF
+    {NULL, NULL, 0, NULL}
+};
+
+
+static struct PyModuleDef opcodemodule = {
+    PyModuleDef_HEAD_INIT,
+    "_opcode",
+    "Opcode support module.",
+    -1,
+    opcode_functions,
+    NULL,
+    NULL,
+    NULL,
+    NULL
+};
+
+PyMODINIT_FUNC
+PyInit__opcode(void)
+{
+    return PyModule_Create(&opcodemodule);
+}