faster-cpython
diff --git a/‎Lib/test/test_monitoring.py
Copy file name to clipboardExpand all lines: Lib/test/test_monitoring.py
+15Lines changed: 15 additions & 0 deletions b/‎Lib/test/test_monitoring.py
Copy file name to clipboardExpand all lines: Lib/test/test_monitoring.py
+15Lines changed: 15 additions & 0 deletions
diff --git a/‎Python/bytecodes.c
Copy file name to clipboardExpand all lines: Python/bytecodes.c
+1-1Lines changed: 1 addition & 1 deletion b/‎Python/bytecodes.c
Copy file name to clipboardExpand all lines: Python/bytecodes.c
+1-1Lines changed: 1 addition & 1 deletion
diff --git a/‎Python/generated_cases.c.h
Copy file name to clipboardExpand all lines: Python/generated_cases.c.h
+2-2Lines changed: 2 additions & 2 deletions b/‎Python/generated_cases.c.h
Copy file name to clipboardExpand all lines: Python/generated_cases.c.h
+2-2Lines changed: 2 additions & 2 deletions
@@ -2157,6 +2157,21 @@ def callback(code, instruction_offset):
         sys.monitoring.restart_events()
         sys.monitoring.set_events(0, 0)
 
+    def test_134879(self):
+        # gh-134789
+        # Specialized FOR_ITER not incrementing index
+        def foo():
+            t = 0
+            for i in [1,2,3,4]:
+                t += i
+            self.assertEqual(t, 10)
+
+        sys.monitoring.use_tool_id(0, "test")
+        self.addCleanup(sys.monitoring.free_tool_id, 0)
+        sys.monitoring.set_local_events(0, foo.__code__, E.BRANCH_LEFT | E.BRANCH_RIGHT)
+        foo()
+        sys.monitoring.set_local_events(0, foo.__code__, 0)
+
 
 class TestOptimizer(MonitoringTestBase, unittest.TestCase):
 
 
@@ -3130,7 +3130,6 @@ dummy_func(
             if (PyStackRef_IsTaggedInt(null_or_index)) {
                 next = _PyForIter_NextWithIndex(iter_o, null_or_index);
                 if (PyStackRef_IsNull(next)) {
-                    null_or_index = PyStackRef_TagInt(-1);
                     JUMPBY(oparg + 1);
                     DISPATCH();
                 }
@@ -3191,6 +3190,7 @@ dummy_func(
                     JUMPBY(oparg + 1);
                     DISPATCH();
                 }
+                null_or_index = PyStackRef_IncrementTaggedIntNoOverflow(null_or_index);
                 INSTRUMENTED_JUMP(this_instr, next_instr, PY_MONITORING_EVENT_BRANCH_LEFT);
             }
             else {
Original file line number	Diff line number	Diff line change
`@@ -3130,7 +3130,6 @@ dummy_func(`
`3130`	`3130`	`if (PyStackRef_IsTaggedInt(null_or_index)) {`
`3131`	`3131`	`next = _PyForIter_NextWithIndex(iter_o, null_or_index);`
`3132`	`3132`	`if (PyStackRef_IsNull(next)) {`
`3133`		`- null_or_index = PyStackRef_TagInt(-1);`
`3134`	`3133`	`JUMPBY(oparg + 1);`
`3135`	`3134`	`DISPATCH();`
`3136`	`3135`	`}`
`@@ -3191,6 +3190,7 @@ dummy_func(`
`3191`	`3190`	`JUMPBY(oparg + 1);`
`3192`	`3191`	`DISPATCH();`
`3193`	`3192`	`}`
	`3193`	`+ null_or_index = PyStackRef_IncrementTaggedIntNoOverflow(null_or_index);`
`3194`	`3194`	`INSTRUMENTED_JUMP(this_instr, next_instr, PY_MONITORING_EVENT_BRANCH_LEFT);`
`3195`	`3195`	`}`
`3196`	`3196`	`else {`