bpo-41670: Remove outdated predict macro invocation. (GH-22026)

Remove PREDICTion of POP_BLOCK from FOR_ITER.

Author: markshannon

Lib/test/test_sys_settrace.py

@@ -602,6 +602,23 @@ def run(tracer):
         self.compare_events(doit_async.__code__.co_firstlineno,
                             tracer.events, events)
 
+    def test_loop_in_try_except(self):
+        # https://bugs.python.org/issue41670
+
+        def func():
+            try:
+                for i in []: pass
+                return 1
+            except:
+                return 2
+
+        self.run_and_compare(func,
+            [(0, 'call'),
+             (1, 'line'),
+             (2, 'line'),
+             (3, 'line'),
+             (3, 'return')])
+
 
 class SkipLineEventsTraceTestCase(TraceTestCase):
     """Repeat the trace tests, but with per-line events skipped"""

Misc/NEWS.d/next/Core and Builtins/2020-08-31-11-37-59.bpo-41670.vmRJRx.rst

@@ -0,0 +1,4 @@
+Prevent line trace being skipped on platforms not compiled
+with ``USE_COMPUTED_GOTOS``.
+Fixes issue where some lines nested within a try-except block
+were not being traced on Windows.

Python/ceval.c

@@ -2311,7 +2311,6 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, PyFrameObject *f, int throwflag)
         }
 
         case TARGET(POP_BLOCK): {
-            PREDICTED(POP_BLOCK);
             PyFrame_BlockPop(f);
             DISPATCH();
         }
@@ -3366,7 +3365,6 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, PyFrameObject *f, int throwflag)
             STACK_SHRINK(1);
             Py_DECREF(iter);
             JUMPBY(oparg);
-            PREDICT(POP_BLOCK);
             DISPATCH();
         }