bpo-40222: "Zero cost" exception handling (GH-25729)

"Zero cost" exception handling.

* Uses a lookup table to determine how to handle exceptions.
* Removes SETUP_FINALLY and POP_TOP block instructions, eliminating (most of) the runtime overhead of try statements.
* Reduces the size of the frame object by about 60%.

1 files changed, 3 insertions, 2 deletions

diff --git a/Include/cpython/code.h b/Include/cpython/code.h
index e810eb4..330f1f5 100644
--- a/Include/cpython/code.h
+++ b/Include/cpython/code.h
@@ -40,6 +40,7 @@ struct PyCodeObject {
     PyObject *co_name;          /* unicode (name, for reference) */
     PyObject *co_linetable;     /* string (encoding addr<->lineno mapping) See
                                    Objects/lnotab_notes.txt for details. */
+    PyObject *co_exceptiontable; /* Byte string encoding exception handling table */
     void *co_zombieframe;       /* for optimization only (see frameobject.c) */
     PyObject *co_weakreflist;   /* to support weakrefs to code objects */
     /* Scratch space for extra data relating to the code object.
@@ -117,12 +118,12 @@ PyAPI_DATA(PyTypeObject) PyCode_Type;
 PyAPI_FUNC(PyCodeObject *) PyCode_New(
         int, int, int, int, int, PyObject *, PyObject *,
         PyObject *, PyObject *, PyObject *, PyObject *,
-        PyObject *, PyObject *, int, PyObject *);
+        PyObject *, PyObject *, int, PyObject *, PyObject *);
 
 PyAPI_FUNC(PyCodeObject *) PyCode_NewWithPosOnlyArgs(
         int, int, int, int, int, int, PyObject *, PyObject *,
         PyObject *, PyObject *, PyObject *, PyObject *,
-        PyObject *, PyObject *, int, PyObject *);
+        PyObject *, PyObject *, int, PyObject *, PyObject *);
         /* same as struct above */
 
 /* Creates a new empty code object with the specified source location. */