wip: switch from BRANCH_TAKEN to BRANCH_RIGHT

Author: nedbat

coverage/core.py

@@ -64,12 +64,12 @@ def __init__(self, warn: TWarnFn, config: CoverageConfig, metacov: bool) -> None
                 warn("sys.monitoring isn't available, using default core", slug="no-sysmon")
                 core_name = None
 
-            if core_name == "sysmon" and config.branch and not env.PYBEHAVIOR.branch_taken:
-                warn(
-                    "sys.monitoring can't yet measure branches well, using default core",
-                    slug="no-sysmon",
-                )
-                core_name = None
+            # if core_name == "sysmon" and config.branch and not env.PYBEHAVIOR.branch_right_left:
+            #     warn(
+            #         "sys.monitoring can't yet measure branches well, using default core",
+            #         slug="no-sysmon",
+            #     )
+            #     core_name = None
 
             if not core_name:
                 # Once we're comfortable with sysmon as a default:

coverage/env.py

@@ -100,10 +100,10 @@ class PYBEHAVIOR:
     # https://github.com/python/cpython/issues/113728
     lasti_is_yield = (PYVERSION[:2] != (3, 13))
 
-    # Does sys.monitoring support BRANCH_TAKEN?
-    branch_taken = (
+    # Does sys.monitoring support BRANCH_RIGHT and BRANCH_LEFT?
+    branch_right_left = (
         pep669 and
-        hasattr(sys.monitoring.events, "BRANCH_TAKEN") # type:ignore[attr-defined,unused-ignore]
+        hasattr(sys.monitoring.events, "BRANCH_RIGHT") # type:ignore[attr-defined,unused-ignore]
     )
 
 

coverage/sysmon.py

@@ -246,8 +246,8 @@ def start(self) -> None:
         if self.trace_arcs:
             register(events.PY_RETURN, self.sysmon_py_return)
             register(events.LINE, self.sysmon_line_arcs)
-            register(events.BRANCH_TAKEN, self.sysmon_branch_taken)
-            register(events.BRANCH_NOT_TAKEN, self.sysmon_branch_not_taken)
+            register(events.BRANCH_RIGHT, self.sysmon_branch_right)     # type:ignore[attr-defined]
+            register(events.BRANCH_LEFT, self.sysmon_branch_left)       # type:ignore[attr-defined]
         else:
             register(events.LINE, self.sysmon_line_lines)
         sys_monitoring.restart_events()
@@ -343,9 +343,9 @@ def sysmon_py_start(  # pylint: disable=useless-return
                         assert sys_monitoring is not None
                         local_events = events.PY_RETURN | events.PY_RESUME | events.LINE
                         if self.trace_arcs:
-                            assert env.PYBEHAVIOR.branch_taken
+                            assert env.PYBEHAVIOR.branch_right_left
                             local_events |= (
-                                events.BRANCH_TAKEN | events.BRANCH_NOT_TAKEN
+                                events.BRANCH_RIGHT | events.BRANCH_LEFT # type:ignore[attr-defined]
                             )
                         sys_monitoring.set_local_events(self.myid, code, local_events)
                         self.local_event_codes[id(code)] = code
@@ -390,10 +390,10 @@ def sysmon_line_arcs(self, code: CodeType, line_number: int) -> MonitorReturn:
         return DISABLE
 
     @panopticon("code", "@", "@")
-    def sysmon_branch_taken(
+    def sysmon_branch_right(
         self, code: CodeType, instruction_offset: int, destination_offset: int
     ) -> MonitorReturn:
-        """Handed BRANCH_TAKEN and BRANCH_NOT_TAKEN events."""
+        """Handed BRANCH_RIGHT and BRANCH_LEFT events."""
         code_info = self.code_infos[id(code)]
         if code_info.file_data is not None:
             b2l = code_info.byte_to_line
@@ -404,10 +404,10 @@ def sysmon_branch_taken(
         return DISABLE
 
     @panopticon("code", "@", "@")
-    def sysmon_branch_not_taken(
+    def sysmon_branch_left(
         self, code: CodeType, instruction_offset: int, destination_offset: int
     ) -> MonitorReturn:
-        """Handed BRANCH_TAKEN and BRANCH_NOT_TAKEN events."""
+        """Handed BRANCH_RIGHT and BRANCH_LEFT events."""
         code_info = self.code_infos[id(code)]
         if code_info.file_data is not None:
             b2l = code_info.byte_to_line

lab/run_sysmon.py

@@ -31,8 +31,8 @@ def bytes_to_lines(code):
     events.PY_RETURN
     | events.PY_RESUME
     | events.LINE
-    | events.BRANCH_TAKEN
-    | events.BRANCH_NOT_TAKEN
+    | events.BRANCH_RIGHT
+    | events.BRANCH_LEFT
     | events.JUMP
 )
 
@@ -82,13 +82,13 @@ def sysmon_branch(code, instruction_offset, destination_offset):
     return sys.monitoring.DISABLE
 
 
-def sysmon_branch_taken(code, instruction_offset, destination_offset):
-    show_off_off("BRANCH_TAKEN", code, instruction_offset, destination_offset)
+def sysmon_branch_right(code, instruction_offset, destination_offset):
+    show_off_off("BRANCH_RIGHT", code, instruction_offset, destination_offset)
     return sys.monitoring.DISABLE
 
 
-def sysmon_branch_not_taken(code, instruction_offset, destination_offset):
-    show_off_off("BRANCH_NOT_TAKEN", code, instruction_offset, destination_offset)
+def sysmon_branch_left(code, instruction_offset, destination_offset):
+    show_off_off("BRANCH_LEFT", code, instruction_offset, destination_offset)
     return sys.monitoring.DISABLE
 
 
@@ -108,8 +108,8 @@ def sysmon_jump(code, instruction_offset, destination_offset):
     # register(events.PY_UNWIND, sysmon_py_unwind_arcs)
     register(events.LINE, sysmon_line)
     register(events.BRANCH, sysmon_branch)
-    register(events.BRANCH_TAKEN, sysmon_branch_taken)
-    register(events.BRANCH_NOT_TAKEN, sysmon_branch_not_taken)
+    register(events.BRANCH_RIGHT, sysmon_branch_right)
+    register(events.BRANCH_LEFT, sysmon_branch_left)
     register(events.JUMP, sysmon_jump)
 
 exec(code)

tests/test_concurrency.py

@@ -556,7 +556,7 @@ def test_multiprocessing_with_branching(self, start_method: str) -> None:
         expected_out = f"{nprocs} pids, total = {total}"
         expect_warn = (
             env.PYBEHAVIOR.pep669
-            and (not env.PYBEHAVIOR.branch_taken)
+            and (not env.PYBEHAVIOR.branch_right_left)
             and testenv.SYS_MON
         )
         self.make_file("multi.py", code)