bpo-46072: Add stats for FOR_ITER.

Python/ceval.c

@@ -4212,6 +4212,11 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, InterpreterFrame *frame, int thr
             PREDICTED(FOR_ITER);
             /* before: [iter]; after: [iter, iter()] *or* [] */
             PyObject *iter = TOP();
+#ifdef Py_STATS
+            extern int _PySpecialization_ClassifyIterator(PyObject *);
+            _py_stats.opcode_stats[FOR_ITER].specialization.failure++;
+            _py_stats.opcode_stats[FOR_ITER].specialization.failure_kinds[_PySpecialization_ClassifyIterator(iter)]++;
+#endif
             PyObject *next = (*Py_TYPE(iter)->tp_iternext)(iter);
             if (next != NULL) {
                 PUSH(next);

Python/specialize.c

@@ -548,6 +548,23 @@ initial_counter_value(void) {
 #define SPEC_FAIL_NOT_FOLLOWED_BY_COND_JUMP 14
 #define SPEC_FAIL_BIG_INT 15
 
+/* FOR_ITER */
+#define SPEC_FAIL_ITER_GENERATOR 10
+#define SPEC_FAIL_ITER_COROUTINE 11
+#define SPEC_FAIL_ITER_ASYNC_GENERATOR 12
+#define SPEC_FAIL_ITER_LIST 13
+#define SPEC_FAIL_ITER_TUPLE 14
+#define SPEC_FAIL_ITER_SET 15
+#define SPEC_FAIL_ITER_STRING 16
+#define SPEC_FAIL_ITER_BYTES 17
+#define SPEC_FAIL_ITER_RANGE 18
+#define SPEC_FAIL_ITER_ITERTOOLS 19
+#define SPEC_FAIL_ITER_DICT_KEYS 20
+#define SPEC_FAIL_ITER_DICT_ITEMS 21
+#define SPEC_FAIL_ITER_DICT_VALUES 22
+#define SPEC_FAIL_ITER_ENUMERATE 23
+
+
 static int
 specialize_module_load_attr(
     PyObject *owner, _Py_CODEUNIT *instr, PyObject *name,
@@ -1817,3 +1834,54 @@ _Py_Specialize_CompareOp(PyObject *lhs, PyObject *rhs,
     STAT_INC(COMPARE_OP, success);
     adaptive->counter = initial_counter_value();
 }
+
+
+int
+ _PySpecialization_ClassifyIterator(PyObject *iter)
+{
+    if (PyGen_CheckExact(iter)) {
+        return SPEC_FAIL_ITER_GENERATOR;
+    }
+    if (PyCoro_CheckExact(iter)) {
+        return SPEC_FAIL_ITER_COROUTINE;
+    }
+    if (PyAsyncGen_CheckExact(iter)) {
+        return SPEC_FAIL_ITER_ASYNC_GENERATOR;
+    }
+    PyTypeObject *t = _Py_TYPE(iter);
+    if (t == &PyListIter_Type) {
+        return SPEC_FAIL_ITER_LIST;
+    }
+    if (t == &PyTupleIter_Type) {
+        return SPEC_FAIL_ITER_TUPLE;
+    }
+    if (t == &PyDictIterKey_Type) {
+        return SPEC_FAIL_ITER_DICT_KEYS;
+    }
+    if (t == &PyDictIterValue_Type) {
+        return SPEC_FAIL_ITER_DICT_VALUES;
+    }
+    if (t == &PyDictIterItem_Type) {
+        return SPEC_FAIL_ITER_DICT_ITEMS;
+    }
+    if (t == &PySetIter_Type) {
+        return SPEC_FAIL_ITER_SET;
+    }
+    if (t == &PyUnicodeIter_Type) {
+        return SPEC_FAIL_ITER_STRING;
+    }
+    if (t == &PyBytesIter_Type) {
+        return SPEC_FAIL_ITER_BYTES;
+    }
+    if (t == &PyRangeIter_Type) {
+        return SPEC_FAIL_ITER_RANGE;
+    }
+    if (t == &PyEnum_Type) {
+        return SPEC_FAIL_ITER_ENUMERATE;
+    }
+
+    if (strncmp(t->tp_name, "itertools", 8) == 0) {
+        return SPEC_FAIL_ITER_ITERTOOLS;
+    }
+    return SPEC_FAIL_OTHER;
+}

Tools/scripts/summarize_stats.py

@@ -26,7 +26,7 @@
 TOTAL = "specialization.deferred", "specialization.hit", "specialization.miss", "execution_count"
 
 def print_specialization_stats(name, family_stats):
-    if "specialization.deferred" not in family_stats:
+    if "specialization.failure" not in family_stats:
         return
     total = sum(family_stats.get(kind, 0) for kind in TOTAL)
     if total == 0: