pythongh-115999: Add free-threaded specialization for TO_BOOL

* None / bool / int / str are immutable types, so they is thread-safe.
* list is mutable, but by using ``PyList_GET_SIZE`` we can make it
  as thread-safe.

Lib/test/test_opcache.py

@@ -1255,6 +1255,72 @@ def g():
         self.assert_specialized(g, "CONTAINS_OP_SET")
         self.assert_no_opcode(g, "CONTAINS_OP")
 
+    @cpython_only
+    @requires_specialization_ft
+    def test_to_bool(self):
+        def to_bool_bool():
+            true_cnt, false_cnt = 0, 0
+            elems = [e % 2 == 0 for e in range(100)]
+            for e in elems:
+                if e:
+                    true_cnt += 1
+                else:
+                    false_cnt -= 1
+            self.assertEqual(true_cnt, 50)
+            self.assertEqual(false_cnt, -50)
+
+        to_bool_bool()
+        self.assert_specialized(to_bool_bool, "TO_BOOL_BOOL")
+        self.assert_no_opcode(to_bool_bool, "TO_BOOL")
+
+        def to_bool_int():
+            count = 0
+            for i in range(100):
+                if i:
+                    count += 1
+                else:
+                    count -= 1
+            self.assertEqual(count, 98)
+
+        to_bool_int()
+        self.assert_specialized(to_bool_int, "TO_BOOL_INT")
+        self.assert_no_opcode(to_bool_int, "TO_BOOL")
+
+        def to_bool_list():
+            count = 0
+            elems = [1, 2, 3]
+            while elems:
+                count += elems.pop()
+            self.assertEqual(elems, [])
+            self.assertEqual(count, 6)
+
+        to_bool_list()
+        self.assert_specialized(to_bool_list, "TO_BOOL_LIST")
+        self.assert_no_opcode(to_bool_list, "TO_BOOL")
+
+        def to_bool_none():
+            count = 0
+            elems = [None, None, None, None]
+            for e in elems:
+                if not e:
+                    count += 1
+            self.assertEqual(count, len(elems))
+
+        to_bool_none()
+        self.assert_specialized(to_bool_none, "TO_BOOL_NONE")
+        self.assert_no_opcode(to_bool_none, "TO_BOOL")
+
+        def to_bool_str():
+            count = 0
+            elems = ["", "foo", ""]
+            for e in elems:
+                if e:
+                    count += 1
+            self.assertEqual(count, 1)
+
+        to_bool_str()
+        self.assert_specialized(to_bool_str, "TO_BOOL_STR")
+        self.assert_no_opcode(to_bool_str, "TO_BOOL")
 
 
 if __name__ == "__main__":

Python/bytecodes.c

@@ -391,15 +391,15 @@ dummy_func(
         };
 
         specializing op(_SPECIALIZE_TO_BOOL, (counter/1, value -- value)) {
-            #if ENABLE_SPECIALIZATION
+            #if ENABLE_SPECIALIZATION_FT
             if (ADAPTIVE_COUNTER_TRIGGERS(counter)) {
                 next_instr = this_instr;
                 _Py_Specialize_ToBool(value, next_instr);
                 DISPATCH_SAME_OPARG();
             }
             OPCODE_DEFERRED_INC(TO_BOOL);
             ADVANCE_ADAPTIVE_COUNTER(this_instr[1].counter);
-            #endif  /* ENABLE_SPECIALIZATION */
+            #endif  /* ENABLE_SPECIALIZATION_FT */
         }
 
         op(_TO_BOOL, (value -- res)) {
@@ -435,7 +435,7 @@ dummy_func(
             PyObject *value_o = PyStackRef_AsPyObjectBorrow(value);
             EXIT_IF(!PyList_CheckExact(value_o));
             STAT_INC(TO_BOOL, hit);
-            res = Py_SIZE(value_o) ? PyStackRef_True : PyStackRef_False;
+            res = PyList_GET_SIZE(value_o) ? PyStackRef_True : PyStackRef_False;
             DECREF_INPUTS();
         }
 

Python/specialize.c

@@ -2663,101 +2663,91 @@ _Py_Specialize_Send(_PyStackRef receiver_st, _Py_CODEUNIT *instr)
     cache->counter = adaptive_counter_cooldown();
 }
 
+static int
+to_bool_fail_kind(PyObject *value)
+{
+    if (PyByteArray_CheckExact(value)) {
+        return SPEC_FAIL_TO_BOOL_BYTEARRAY;
+    }
+    if (PyBytes_CheckExact(value)) {
+        return SPEC_FAIL_TO_BOOL_BYTES;
+    }
+    if (PyDict_CheckExact(value)) {
+        return SPEC_FAIL_TO_BOOL_DICT;
+    }
+    if (PyFloat_CheckExact(value)) {
+        return SPEC_FAIL_TO_BOOL_FLOAT;
+    }
+    if (PyMemoryView_Check(value)) {
+        return SPEC_FAIL_TO_BOOL_MEMORY_VIEW;
+    }
+    if (PyAnySet_CheckExact(value)) {
+        return SPEC_FAIL_TO_BOOL_SET;
+    }
+    if (PyTuple_CheckExact(value)) {
+        return SPEC_FAIL_TO_BOOL_TUPLE;
+    }
+    return SPEC_FAIL_OTHER;
+}
+
 void
 _Py_Specialize_ToBool(_PyStackRef value_o, _Py_CODEUNIT *instr)
 {
-    assert(ENABLE_SPECIALIZATION);
+    assert(ENABLE_SPECIALIZATION_FT);
     assert(_PyOpcode_Caches[TO_BOOL] == INLINE_CACHE_ENTRIES_TO_BOOL);
     _PyToBoolCache *cache = (_PyToBoolCache *)(instr + 1);
     PyObject *value = PyStackRef_AsPyObjectBorrow(value_o);
     if (PyBool_Check(value)) {
-        instr->op.code = TO_BOOL_BOOL;
-        goto success;
+        specialize(instr, TO_BOOL_BOOL);
+        return;
     }
     if (PyLong_CheckExact(value)) {
-        instr->op.code = TO_BOOL_INT;
-        goto success;
+        specialize(instr, TO_BOOL_INT);
+        return;
     }
     if (PyList_CheckExact(value)) {
-        instr->op.code = TO_BOOL_LIST;
-        goto success;
+        specialize(instr, TO_BOOL_LIST);
+        return;
     }
     if (Py_IsNone(value)) {
-        instr->op.code = TO_BOOL_NONE;
-        goto success;
+        specialize(instr, TO_BOOL_NONE);
+        return;
     }
     if (PyUnicode_CheckExact(value)) {
-        instr->op.code = TO_BOOL_STR;
-        goto success;
+        specialize(instr, TO_BOOL_STR);
+        return;
     }
     if (PyType_HasFeature(Py_TYPE(value), Py_TPFLAGS_HEAPTYPE)) {
         PyNumberMethods *nb = Py_TYPE(value)->tp_as_number;
         if (nb && nb->nb_bool) {
-            SPECIALIZATION_FAIL(TO_BOOL, SPEC_FAIL_TO_BOOL_NUMBER);
-            goto failure;
+            unspecialize(instr, SPEC_FAIL_TO_BOOL_NUMBER);
+            return;
         }
         PyMappingMethods *mp = Py_TYPE(value)->tp_as_mapping;
         if (mp && mp->mp_length) {
-            SPECIALIZATION_FAIL(TO_BOOL, SPEC_FAIL_TO_BOOL_MAPPING);
-            goto failure;
+            unspecialize(instr, SPEC_FAIL_TO_BOOL_MAPPING);
+            return;
         }
         PySequenceMethods *sq = Py_TYPE(value)->tp_as_sequence;
         if (sq && sq->sq_length) {
-            SPECIALIZATION_FAIL(TO_BOOL, SPEC_FAIL_TO_BOOL_SEQUENCE);
-            goto failure;
+            unspecialize(instr, SPEC_FAIL_TO_BOOL_SEQUENCE);
+            return;
         }
         if (!PyUnstable_Type_AssignVersionTag(Py_TYPE(value))) {
-            SPECIALIZATION_FAIL(TO_BOOL, SPEC_FAIL_OUT_OF_VERSIONS);
-            goto failure;
+            unspecialize(instr, SPEC_FAIL_OUT_OF_VERSIONS);
+            return;
         }
-        uint32_t version = type_get_version(Py_TYPE(value), TO_BOOL);
+        uint32_t version = FT_ATOMIC_LOAD_UINT32_RELAXED(Py_TYPE(value)->tp_version_tag);
         if (version == 0) {
-            goto failure;
+            unspecialize(instr, SPEC_FAIL_OUT_OF_VERSIONS);
+            return;
         }
-        instr->op.code = TO_BOOL_ALWAYS_TRUE;
+        specialize(instr, TO_BOOL_ALWAYS_TRUE);
         write_u32(cache->version, version);
         assert(version);
-        goto success;
-    }
-#ifdef Py_STATS
-    if (PyByteArray_CheckExact(value)) {
-        SPECIALIZATION_FAIL(TO_BOOL, SPEC_FAIL_TO_BOOL_BYTEARRAY);
-        goto failure;
-    }
-    if (PyBytes_CheckExact(value)) {
-        SPECIALIZATION_FAIL(TO_BOOL, SPEC_FAIL_TO_BOOL_BYTES);
-        goto failure;
-    }
-    if (PyDict_CheckExact(value)) {
-        SPECIALIZATION_FAIL(TO_BOOL, SPEC_FAIL_TO_BOOL_DICT);
-        goto failure;
-    }
-    if (PyFloat_CheckExact(value)) {
-        SPECIALIZATION_FAIL(TO_BOOL, SPEC_FAIL_TO_BOOL_FLOAT);
-        goto failure;
-    }
-    if (PyMemoryView_Check(value)) {
-        SPECIALIZATION_FAIL(TO_BOOL, SPEC_FAIL_TO_BOOL_MEMORY_VIEW);
-        goto failure;
-    }
-    if (PyAnySet_CheckExact(value)) {
-        SPECIALIZATION_FAIL(TO_BOOL, SPEC_FAIL_TO_BOOL_SET);
-        goto failure;
-    }
-    if (PyTuple_CheckExact(value)) {
-        SPECIALIZATION_FAIL(TO_BOOL, SPEC_FAIL_TO_BOOL_TUPLE);
-        goto failure;
+        return;
     }
-    SPECIALIZATION_FAIL(TO_BOOL, SPEC_FAIL_OTHER);
-#endif   // Py_STATS
-failure:
-    STAT_INC(TO_BOOL, failure);
-    instr->op.code = TO_BOOL;
-    cache->counter = adaptive_counter_backoff(cache->counter);
-    return;
-success:
-    STAT_INC(TO_BOOL, success);
-    cache->counter = adaptive_counter_cooldown();
+    unspecialize(instr, to_bool_fail_kind(value));
 }
 
 static int