bpo-46841: Use inline cache for BINARY_SUBSCR. (GH-31618)

Author: markshannon

Include/cpython/object.h

@@ -229,6 +229,13 @@ struct _typeobject {
     vectorcallfunc tp_vectorcall;
 };
 
+/* This struct is used by the specializer
+ * It should should be treated as an opaque blob
+ * by code other than the specializer and interpreter. */
+struct _specialization_cache {
+    PyObject *getitem;
+};
+
 /* The *real* layout of a type object when allocated on the heap */
 typedef struct _heaptypeobject {
     /* Note: there's a dependency on the order of these members
@@ -247,6 +254,7 @@ typedef struct _heaptypeobject {
     struct _dictkeysobject *ht_cached_keys;
     PyObject *ht_module;
     char *_ht_tpname;  // Storage for "tp_name"; see PyType_FromModuleAndSpec
+    struct _specialization_cache _spec_cache; // For use by the specializer.
     /* here are optional user slots, followed by the members. */
 } PyHeapTypeObject;
 

Include/internal/pycore_code.h

@@ -92,6 +92,15 @@ typedef struct {
 
 #define INLINE_CACHE_ENTRIES_COMPARE_OP CACHE_ENTRIES(_PyCompareOpCache)
 
+typedef struct {
+    _Py_CODEUNIT counter;
+    _Py_CODEUNIT type_version;
+    _Py_CODEUNIT _t1;
+    _Py_CODEUNIT func_version;
+} _PyBinarySubscrCache;
+
+#define INLINE_CACHE_ENTRIES_BINARY_SUBSCR CACHE_ENTRIES(_PyBinarySubscrCache)
+
 /* Maximum size of code to quicken, in code units. */
 #define MAX_SIZE_TO_QUICKEN 5000
 
@@ -323,7 +332,7 @@ extern int _Py_Specialize_LoadAttr(PyObject *owner, _Py_CODEUNIT *instr, PyObjec
 extern int _Py_Specialize_StoreAttr(PyObject *owner, _Py_CODEUNIT *instr, PyObject *name, SpecializedCacheEntry *cache);
 extern int _Py_Specialize_LoadGlobal(PyObject *globals, PyObject *builtins, _Py_CODEUNIT *instr, PyObject *name);
 extern int _Py_Specialize_LoadMethod(PyObject *owner, _Py_CODEUNIT *instr, PyObject *name, SpecializedCacheEntry *cache);
-extern int _Py_Specialize_BinarySubscr(PyObject *sub, PyObject *container, _Py_CODEUNIT *instr, SpecializedCacheEntry *cache);
+extern int _Py_Specialize_BinarySubscr(PyObject *sub, PyObject *container, _Py_CODEUNIT *instr);
 extern int _Py_Specialize_StoreSubscr(PyObject *container, PyObject *sub, _Py_CODEUNIT *instr);
 extern int _Py_Specialize_Call(PyObject *callable, _Py_CODEUNIT *instr, int nargs,
     PyObject *kwnames, SpecializedCacheEntry *cache);

Include/opcode.h

@@ -389,7 +389,7 @@ def _write_atomic(path, data, mode=0o666):
 #     Python 3.11a5 3480 (New CALL opcodes, second iteration)
 #     Python 3.11a5 3481 (Use inline cache for BINARY_OP)
 #     Python 3.11a5 3482 (Use inline caching for UNPACK_SEQUENCE and LOAD_GLOBAL)
-#     Python 3.11a5 3483 (Use inline caching for COMPARE_OP)
+#     Python 3.11a5 3483 (Use inline caching for COMPARE_OP and BINARY_SUBSCR)
 
 #     Python 3.12 will start with magic number 3500
 

Lib/importlib/_bootstrap_external.py

@@ -68,7 +68,7 @@ def jabs_op(name, op, entries=0):
 
 def_op('UNARY_INVERT', 15)
 
-def_op('BINARY_SUBSCR', 25)
+def_op('BINARY_SUBSCR', 25, 4)
 
 def_op('GET_LEN', 30)
 def_op('MATCH_MAPPING', 31)

Lib/opcode.py

@@ -335,7 +335,7 @@ class C(): pass
             *_, count = line.split(b' ')
             count = int(count)
             self.assertLessEqual(count, i*5)
-            self.assertGreaterEqual(count, i*5-1)
+            self.assertGreaterEqual(count, i*5-2)
 
     def test_mapping_keys_values_items(self):
         class Mapping1(dict):

Lib/test/test_capi.py

@@ -1501,7 +1501,9 @@ def delx(self): del self.__x
                   '3P'                  # PyMappingMethods
                   '10P'                 # PySequenceMethods
                   '2P'                  # PyBufferProcs
-                  '6P')
+                  '6P'
+                  '1P'                  # Specializer cache
+                  )
         class newstyleclass(object): pass
         # Separate block for PyDictKeysObject with 8 keys and 5 entries
         check(newstyleclass, s + calcsize(DICT_KEY_STRUCT_FORMAT) + 64 + 42*calcsize("n2P"))

Lib/test/test_sys.py

@@ -0,0 +1 @@
+Use inline cache for :opcode:`BINARY_SUBSCR`.

Misc/NEWS.d/next/Core and Builtins/2022-02-28-15-46-36.bpo-46841.MDQoty.rst

@@ -2102,25 +2102,24 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, _PyInterpreterFrame *frame, int
             SET_TOP(res);
             if (res == NULL)
                 goto error;
+            JUMPBY(INLINE_CACHE_ENTRIES_BINARY_SUBSCR);
             DISPATCH();
         }
 
         TARGET(BINARY_SUBSCR_ADAPTIVE) {
-            SpecializedCacheEntry *cache = GET_CACHE();
-            if (cache->adaptive.counter == 0) {
+            _PyBinarySubscrCache *cache = (_PyBinarySubscrCache *)next_instr;
+            if (cache->counter == 0) {
                 PyObject *sub = TOP();
                 PyObject *container = SECOND();
                 next_instr--;
-                if (_Py_Specialize_BinarySubscr(container, sub, next_instr, cache) < 0) {
+                if (_Py_Specialize_BinarySubscr(container, sub, next_instr) < 0) {
                     goto error;
                 }
                 DISPATCH();
             }
             else {
                 STAT_INC(BINARY_SUBSCR, deferred);
-                cache->adaptive.counter--;
-                assert(cache->adaptive.original_oparg == 0);
-                /* No need to set oparg here; it isn't used by BINARY_SUBSCR */
+                cache->counter--;
                 JUMP_TO_INSTRUCTION(BINARY_SUBSCR);
             }
         }
@@ -2146,6 +2145,7 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, _PyInterpreterFrame *frame, int
             Py_DECREF(sub);
             SET_TOP(res);
             Py_DECREF(list);
+            JUMPBY(INLINE_CACHE_ENTRIES_BINARY_SUBSCR);
             NOTRACE_DISPATCH();
         }
 
@@ -2170,6 +2170,7 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, _PyInterpreterFrame *frame, int
             Py_DECREF(sub);
             SET_TOP(res);
             Py_DECREF(tuple);
+            JUMPBY(INLINE_CACHE_ENTRIES_BINARY_SUBSCR);
             NOTRACE_DISPATCH();
         }
 
@@ -2188,18 +2189,22 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, _PyInterpreterFrame *frame, int
             Py_DECREF(sub);
             SET_TOP(res);
             Py_DECREF(dict);
+            JUMPBY(INLINE_CACHE_ENTRIES_BINARY_SUBSCR);
             DISPATCH();
         }
 
         TARGET(BINARY_SUBSCR_GETITEM) {
             PyObject *sub = TOP();
             PyObject *container = SECOND();
-            SpecializedCacheEntry *caches = GET_CACHE();
-            _PyAdaptiveEntry *cache0 = &caches[0].adaptive;
-            _PyObjectCache *cache1 = &caches[-1].obj;
-            PyFunctionObject *getitem = (PyFunctionObject *)cache1->obj;
-            DEOPT_IF(Py_TYPE(container)->tp_version_tag != cache0->version, BINARY_SUBSCR);
-            DEOPT_IF(getitem->func_version != cache0->index, BINARY_SUBSCR);
+            _PyBinarySubscrCache *cache = (_PyBinarySubscrCache *)next_instr;
+            uint32_t type_version = read32(&cache->type_version);
+            PyTypeObject *tp = Py_TYPE(container);
+            DEOPT_IF(tp->tp_version_tag != type_version, BINARY_SUBSCR);
+            assert(tp->tp_flags & Py_TPFLAGS_HEAPTYPE);
+            PyObject *cached = ((PyHeapTypeObject *)tp)->_spec_cache.getitem;
+            assert(PyFunction_Check(cached));
+            PyFunctionObject *getitem = (PyFunctionObject *)cached;
+            DEOPT_IF(getitem->func_version != cache->func_version, BINARY_SUBSCR);
             PyCodeObject *code = (PyCodeObject *)getitem->func_code;
             size_t size = code->co_nlocalsplus + code->co_stacksize + FRAME_SPECIALS_SIZE;
             assert(code->co_argcount == 2);
@@ -2218,6 +2223,7 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, _PyInterpreterFrame *frame, int
                 new_frame->localsplus[i] = NULL;
             }
             _PyFrame_SetStackPointer(frame, stack_pointer);
+            frame->f_lasti += INLINE_CACHE_ENTRIES_BINARY_SUBSCR;
             new_frame->previous = frame;
             frame = cframe.current_frame = new_frame;
             CALL_STAT_INC(inlined_py_calls);
@@ -5605,7 +5611,7 @@ MISS_WITH_CACHE(PRECALL)
 MISS_WITH_CACHE(CALL)
 MISS_WITH_INLINE_CACHE(BINARY_OP)
 MISS_WITH_INLINE_CACHE(COMPARE_OP)
-MISS_WITH_CACHE(BINARY_SUBSCR)
+MISS_WITH_INLINE_CACHE(BINARY_SUBSCR)
 MISS_WITH_INLINE_CACHE(UNPACK_SEQUENCE)
 MISS_WITH_OPARG_COUNTER(STORE_SUBSCR)