python · markshannon · Dec 19, 2024 · Dec 11, 2024 · Dec 13, 2024 · Dec 13, 2024
diff --git a/Doc/c-api/monitoring.rst b/Doc/c-api/monitoring.rst
@@ -75,9 +75,14 @@ See :mod:`sys.monitoring` for descriptions of the events.
    Fire a ``JUMP`` event.
 
 
-.. c:function:: int PyMonitoring_FireBranchEvent(PyMonitoringState *state, PyObject *codelike, int32_t offset, PyObject *target_offset)
+.. c:function:: int PyMonitoring_FireBranchLeftEvent(PyMonitoringState *state, PyObject *codelike, int32_t offset, PyObject *target_offset)
 
-   Fire a ``BRANCH`` event.
+   Fire a ``BRANCH_LEFT`` event.
+
+
+.. c:function:: int PyMonitoring_FireBranchRightEvent(PyMonitoringState *state, PyObject *codelike, int32_t offset, PyObject *target_offset)
+
+   Fire a ``BRANCH_RIGHT`` event.
 
 
 .. c:function:: int PyMonitoring_FireCReturnEvent(PyMonitoringState *state, PyObject *codelike, int32_t offset, PyObject *retval)
@@ -168,7 +173,8 @@ would typically correspond to a python function.
    ================================================== =====================================
    Macro                                              Event
    ================================================== =====================================
-   .. c:macro:: PY_MONITORING_EVENT_BRANCH            :monitoring-event:`BRANCH`
+   .. c:macro:: PY_MONITORING_EVENT_BRANCH_LEFT       :monitoring-event:`BRANCH_LEFT`
+   .. c:macro:: PY_MONITORING_EVENT_BRANCH_RIGHT      :monitoring-event:`BRANCH_RIGHT`
    .. c:macro:: PY_MONITORING_EVENT_CALL              :monitoring-event:`CALL`
    .. c:macro:: PY_MONITORING_EVENT_C_RAISE           :monitoring-event:`C_RAISE`
    .. c:macro:: PY_MONITORING_EVENT_C_RETURN          :monitoring-event:`C_RETURN`

diff --git a/Doc/library/sys.monitoring.rst b/Doc/library/sys.monitoring.rst
@@ -79,9 +79,17 @@ Events
 
 The following events are supported:
 
-.. monitoring-event:: BRANCH
+.. monitoring-event:: BRANCH_LEFT
 
-   A conditional branch is taken (or not).
+   A conditional branch goes left.
+
+   It is up to the tool to determine how to present "left" and "right" branches.
+   There is no guarantee which branch is "left" and which is "right", except
+   that it will be consistent for the duration of the program.
+
+.. monitoring-event:: BRANCH_RIGHT
+
+   A conditional branch goes right.
 
 .. monitoring-event:: CALL
 
@@ -180,9 +188,20 @@ The local events are:
 * :monitoring-event:`LINE`
 * :monitoring-event:`INSTRUCTION`
 * :monitoring-event:`JUMP`
-* :monitoring-event:`BRANCH`
+* :monitoring-event:`BRANCH_LEFT`
+* :monitoring-event:`BRANCH_RIGHT`
 * :monitoring-event:`STOP_ITERATION`
 
+Deprecated event
+''''''''''''''''
+
+* ``BRANCH``
+
+The ``BRANCH`` event is deprecated in 3.14.
+Using :monitoring-event:`BRANCH_LEFT` and :monitoring-event:`BRANCH_RIGHT`
+events will give much better performance as they can be disabled
+independently.
+
 Ancillary events
 ''''''''''''''''
 
@@ -357,13 +376,11 @@ Different events will provide the callback function with different arguments, as
 
     func(code: CodeType, line_number: int) -> DISABLE | Any
 
-* :monitoring-event:`BRANCH` and :monitoring-event:`JUMP`::
+* :monitoring-event:`BRANCH_LEFT`, :monitoring-event:`BRANCH_RIGHT` and :monitoring-event:`JUMP`::
 
     func(code: CodeType, instruction_offset: int, destination_offset: int) -> DISABLE | Any
 
   Note that the *destination_offset* is where the code will next execute.
-  For an untaken branch this will be the offset of the instruction following
-  the branch.
 
 * :monitoring-event:`INSTRUCTION`::
 

diff --git a/Doc/whatsnew/3.13.rst b/Doc/whatsnew/3.13.rst
@@ -1971,7 +1971,7 @@ New Features
   * :c:func:`PyMonitoring_FireCallEvent`
   * :c:func:`PyMonitoring_FireLineEvent`
   * :c:func:`PyMonitoring_FireJumpEvent`
-  * :c:func:`PyMonitoring_FireBranchEvent`
+  * ``PyMonitoring_FireBranchEvent``
   * :c:func:`PyMonitoring_FireCReturnEvent`
   * :c:func:`PyMonitoring_FirePyThrowEvent`
   * :c:func:`PyMonitoring_FireRaiseEvent`

diff --git a/Doc/whatsnew/3.14.rst b/Doc/whatsnew/3.14.rst
@@ -603,6 +603,11 @@ sys
   which only exists in specialized builds of Python, may now return objects
   from other interpreters than the one it's called in.
 
+sys.monitoring
+--------------
+
+Two new events are added: :monitoring-event:`BRANCH_LEFT` and
+:monitoring-event:`BRANCH_RIGHT`. The ``BRANCH`` event is deprecated.
 
 tkinter
 -------
@@ -1144,6 +1149,11 @@ New features
   a :exc:`UnicodeError` object.
   (Contributed by Bénédikt Tran in :gh:`127691`.)
 
+* Add :c:func:`PyMonitoring_FireBranchLeftEvent` and
+  :c:func:`PyMonitoring_FireBranchRightEvent` for generating
+  :monitoring-event:`BRANCH_LEFT` and :monitoring-event:`BRANCH_RIGHT`
+  events, respectively.
+
 
 Porting to Python 3.14
 ----------------------
@@ -1177,6 +1187,10 @@ Deprecated
 
 .. include:: ../deprecations/c-api-pending-removal-in-future.rst
 
+* The ``PyMonitoring_FireBranchEvent`` function is deprecated and should
+  be replaced with calls to :c:func:`PyMonitoring_FireBranchLeftEvent`
+  and :c:func:`PyMonitoring_FireBranchRightEvent`.
+
 Removed
 -------
 

diff --git a/Include/cpython/code.h b/Include/cpython/code.h
@@ -11,11 +11,11 @@ extern "C" {
 /* Total tool ids available */
 #define  _PY_MONITORING_TOOL_IDS 8
 /* Count of all local monitoring events */
-#define  _PY_MONITORING_LOCAL_EVENTS 10
+#define  _PY_MONITORING_LOCAL_EVENTS 11
 /* Count of all "real" monitoring events (not derived from other events) */
-#define _PY_MONITORING_UNGROUPED_EVENTS 15
+#define _PY_MONITORING_UNGROUPED_EVENTS 16
 /* Count of all  monitoring events */
-#define _PY_MONITORING_EVENTS 17
+#define _PY_MONITORING_EVENTS 19
 
 /* Tables of which tools are active for each monitored event. */
 typedef struct _Py_LocalMonitors {

diff --git a/Include/cpython/monitoring.h b/Include/cpython/monitoring.h
@@ -13,25 +13,27 @@
 #define PY_MONITORING_EVENT_LINE 5
 #define PY_MONITORING_EVENT_INSTRUCTION 6
 #define PY_MONITORING_EVENT_JUMP 7
-#define PY_MONITORING_EVENT_BRANCH 8
-#define PY_MONITORING_EVENT_STOP_ITERATION 9
+#define PY_MONITORING_EVENT_BRANCH_LEFT 8
+#define PY_MONITORING_EVENT_BRANCH_RIGHT 9
+#define PY_MONITORING_EVENT_STOP_ITERATION 10
 
 #define PY_MONITORING_IS_INSTRUMENTED_EVENT(ev) \
     ((ev) < _PY_MONITORING_LOCAL_EVENTS)
 
 /* Other events, mainly exceptions */
 
-#define PY_MONITORING_EVENT_RAISE 10
-#define PY_MONITORING_EVENT_EXCEPTION_HANDLED 11
-#define PY_MONITORING_EVENT_PY_UNWIND 12
-#define PY_MONITORING_EVENT_PY_THROW 13
-#define PY_MONITORING_EVENT_RERAISE 14
+#define PY_MONITORING_EVENT_RAISE 11
+#define PY_MONITORING_EVENT_EXCEPTION_HANDLED 12
+#define PY_MONITORING_EVENT_PY_UNWIND 13
+#define PY_MONITORING_EVENT_PY_THROW 14
+#define PY_MONITORING_EVENT_RERAISE 15
 
 
 /* Ancillary events */
 
-#define PY_MONITORING_EVENT_C_RETURN 15
-#define PY_MONITORING_EVENT_C_RAISE 16
+#define PY_MONITORING_EVENT_C_RETURN 16
+#define PY_MONITORING_EVENT_C_RAISE 17
+#define PY_MONITORING_EVENT_BRANCH 18
 
 
 typedef struct _PyMonitoringState {
@@ -74,10 +76,18 @@ PyAPI_FUNC(int)
 _PyMonitoring_FireJumpEvent(PyMonitoringState *state, PyObject *codelike, int32_t offset,
                             PyObject *target_offset);
 
-PyAPI_FUNC(int)
+Py_DEPRECATED(3.14) PyAPI_FUNC(int)
 _PyMonitoring_FireBranchEvent(PyMonitoringState *state, PyObject *codelike, int32_t offset,
                               PyObject *target_offset);
 
+PyAPI_FUNC(int)
+_PyMonitoring_FireBranchRightEvent(PyMonitoringState *state, PyObject *codelike, int32_t offset,
+                              PyObject *target_offset);
+
+PyAPI_FUNC(int)
+_PyMonitoring_FireBranchLeftEvent(PyMonitoringState *state, PyObject *codelike, int32_t offset,
+                              PyObject *target_offset);
+
 PyAPI_FUNC(int)
 _PyMonitoring_FireCReturnEvent(PyMonitoringState *state, PyObject *codelike, int32_t offset,
                                PyObject *retval);
@@ -174,12 +184,21 @@ PyMonitoring_FireJumpEvent(PyMonitoringState *state, PyObject *codelike, int32_t
 }
 
 static inline int
-PyMonitoring_FireBranchEvent(PyMonitoringState *state, PyObject *codelike, int32_t offset,
+PyMonitoring_FireBranchRightEvent(PyMonitoringState *state, PyObject *codelike, int32_t offset,
+                             PyObject *target_offset)
+{
+    _PYMONITORING_IF_ACTIVE(
+        state,
+        _PyMonitoring_FireBranchRightEvent(state, codelike, offset, target_offset));
+}
+
+static inline int
+PyMonitoring_FireBranchLeftEvent(PyMonitoringState *state, PyObject *codelike, int32_t offset,
                              PyObject *target_offset)
 {
     _PYMONITORING_IF_ACTIVE(
         state,
-        _PyMonitoring_FireBranchEvent(state, codelike, offset, target_offset));
+        _PyMonitoring_FireBranchLeftEvent(state, codelike, offset, target_offset));
 }
 
 static inline int

diff --git a/Include/internal/pycore_code.h b/Include/internal/pycore_code.h
@@ -603,6 +603,8 @@ extern _Py_CODEUNIT _Py_GetBaseCodeUnit(PyCodeObject *code, int offset);
 
 extern int _PyInstruction_GetLength(PyCodeObject *code, int offset);
 
+extern PyObject *_PyInstrumentation_BranchesIterator(PyCodeObject *code);
+
 struct _PyCode8 _PyCode_DEF(8);
 
 PyAPI_DATA(const struct _PyCode8) _Py_InitCleanup;

diff --git a/Include/internal/pycore_magic_number.h b/Include/internal/pycore_magic_number.h
@@ -262,6 +262,7 @@ Known values:
     Python 3.14a1 3607 (Add pseudo instructions JUMP_IF_TRUE/FALSE)
     Python 3.14a1 3608 (Add support for slices)
     Python 3.14a2 3609 (Add LOAD_SMALL_INT and LOAD_CONST_IMMORTAL instructions, remove RETURN_CONST)
+    Python 3.14a3 3610 (Add NOT_TAKEN instruction)
 
     Python 3.15 will start with 3650
 
@@ -274,7 +275,7 @@ PC/launcher.c must also be updated.
 
 */
 
-#define PYC_MAGIC_NUMBER 3609
+#define PYC_MAGIC_NUMBER 3611
 /* This is equivalent to converting PYC_MAGIC_NUMBER to 2 bytes
    (little-endian) and then appending b'\r\n'. */
 #define PYC_MAGIC_NUMBER_TOKEN \

diff --git a/Include/internal/pycore_opcode_metadata.h b/Include/internal/pycore_opcode_metadata.h
diff --git a/Include/internal/pycore_opcode_utils.h b/Include/internal/pycore_opcode_utils.h
@@ -45,6 +45,12 @@ extern "C" {
          (opcode) == JUMP_BACKWARD || \
          (opcode) == JUMP_BACKWARD_NO_INTERRUPT)
 
+#define IS_CONDITIONAL_JUMP_OPCODE(opcode) \
+        ((opcode) == POP_JUMP_IF_FALSE || \
+         (opcode) == POP_JUMP_IF_TRUE || \
+         (opcode) == POP_JUMP_IF_NONE || \
+         (opcode) == POP_JUMP_IF_NOT_NONE)
+
 #define IS_SCOPE_EXIT_OPCODE(opcode) \
         ((opcode) == RETURN_VALUE || \
          (opcode) == RAISE_VARARGS || \