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bpo-44826: Specialize STORE_ATTR (GH-27590)

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* Generalize cache names for LOAD_ATTR to allow store and delete specializations.

* Factor out specialization of attribute dictionary access.

* Specialize STORE_ATTR.
This commit is contained in:
Mark Shannon 2021-08-09 10:40:21 +01:00 • committed by GitHub
parent b854557b49
commit ac75f6bdd4
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GPG key ID: 4AEE18F83AFDEB23
9 changed files with 345 additions and 93 deletions
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276
Python/specialize.c
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@ -173,6 +173,7 @@ _Py_PrintSpecializationStats(void)
print_stats(out, &_specialization_stats[LOAD_ATTR], "load_attr");
print_stats(out, &_specialization_stats[LOAD_GLOBAL], "load_global");
print_stats(out, &_specialization_stats[BINARY_SUBSCR], "binary_subscr");
print_stats(out, &_specialization_stats[STORE_ATTR], "store_attr");
if (out != stderr) {
fclose(out);
}
@ -262,13 +263,15 @@ static uint8_t adaptive_opcodes[256] = {
[LOAD_ATTR] = LOAD_ATTR_ADAPTIVE,
[LOAD_GLOBAL] = LOAD_GLOBAL_ADAPTIVE,
[BINARY_SUBSCR] = BINARY_SUBSCR_ADAPTIVE,
[STORE_ATTR] = STORE_ATTR_ADAPTIVE,
};
/* The number of cache entries required for a "family" of instructions. */
static uint8_t cache_requirements[256] = {
[LOAD_ATTR] = 2, /* _PyAdaptiveEntry and _PyLoadAttrCache */
[LOAD_ATTR] = 2, /* _PyAdaptiveEntry and _PyAttrCache */
[LOAD_GLOBAL] = 2, /* _PyAdaptiveEntry and _PyLoadGlobalCache */
[BINARY_SUBSCR] = 0,
[STORE_ATTR] = 2, /* _PyAdaptiveEntry and _PyAttrCache */
};
/* Return the oparg for the cache_offset and instruction index.
@ -416,7 +419,7 @@ _Py_Quicken(PyCodeObject *code) {
static int
specialize_module_load_attr(
PyObject *owner, _Py_CODEUNIT *instr, PyObject *name,
_PyAdaptiveEntry *cache0, _PyLoadAttrCache *cache1)
_PyAdaptiveEntry *cache0, _PyAttrCache *cache1)
{
PyModuleObject *m = (PyModuleObject *)owner;
PyObject *value = NULL;
@ -475,15 +478,24 @@ typedef enum {
MUTABLE, /* Instance of a mutable class; might, or might not, be a descriptor */
ABSENT, /* Attribute is not present on the class */
DUNDER_CLASS, /* __class__ attribute */
GETATTRIBUTE_OVERRIDDEN /* __getattribute__ has been overridden */
GETSET_OVERRIDDEN /* __getattribute__ or __setattr__ has been overridden */
} DesciptorClassification;
static DesciptorClassification
analyze_descriptor(PyTypeObject *type, PyObject *name, PyObject **descr)
analyze_descriptor(PyTypeObject *type, PyObject *name, PyObject **descr, int store)
{
if (type->tp_getattro != PyObject_GenericGetAttr) {
*descr = NULL;
return GETATTRIBUTE_OVERRIDDEN;
if (store) {
if (type->tp_setattro != PyObject_GenericSetAttr) {
*descr = NULL;
return GETSET_OVERRIDDEN;
}
}
else {
if (type->tp_getattro != PyObject_GenericGetAttr) {
*descr = NULL;
return GETSET_OVERRIDDEN;
}
}
PyObject *descriptor = _PyType_Lookup(type, name);
*descr = descriptor;
@ -522,11 +534,92 @@ analyze_descriptor(PyTypeObject *type, PyObject *name, PyObject **descr)
return NON_DESCRIPTOR;
}
static int
specialize_dict_access(
PyObject *owner, _Py_CODEUNIT *instr, PyTypeObject *type,
DesciptorClassification kind, PyObject *name,
_PyAdaptiveEntry *cache0, _PyAttrCache *cache1,
int base_op, int split_op, int hint_op)
{
assert(kind == NON_OVERRIDING || kind == NON_DESCRIPTOR || kind == ABSENT);
// No desciptor, or non overriding.
if (type->tp_dictoffset < 0) {
SPECIALIZATION_FAIL(base_op, type, name, "negative offset");
return 0;
}
if (type->tp_dictoffset > 0) {
PyObject **dictptr = (PyObject **) ((char *)owner + type->tp_dictoffset);
if (*dictptr == NULL || !PyDict_CheckExact(*dictptr)) {
SPECIALIZATION_FAIL(base_op, type, name, "no dict or not a dict");
return 0;
}
// We found an instance with a __dict__.
PyDictObject *dict = (PyDictObject *)*dictptr;
if ((type->tp_flags & Py_TPFLAGS_HEAPTYPE)
&& dict->ma_keys == ((PyHeapTypeObject*)type)->ht_cached_keys
) {
// Keys are shared
assert(PyUnicode_CheckExact(name));
Py_hash_t hash = PyObject_Hash(name);
if (hash == -1) {
return -1;
}
PyObject *value;
Py_ssize_t index = _Py_dict_lookup(dict, name, hash, &value);
assert (index != DKIX_ERROR);
if (index != (uint16_t)index) {
SPECIALIZATION_FAIL(base_op, type, name,
index < 0 ? "attribute not in dict" : "index out of range");
return 0;
}
uint32_t keys_version = _PyDictKeys_GetVersionForCurrentState(dict);
if (keys_version == 0) {
SPECIALIZATION_FAIL(base_op, type, name, "no more key versions");
return 0;
}
cache1->dk_version_or_hint = keys_version;
cache1->tp_version = type->tp_version_tag;
cache0->index = (uint16_t)index;
*instr = _Py_MAKECODEUNIT(split_op, _Py_OPARG(*instr));
return 0;
}
else {
PyObject *value = NULL;
Py_ssize_t hint =
_PyDict_GetItemHint(dict, name, -1, &value);
if (hint != (uint32_t)hint) {
SPECIALIZATION_FAIL(base_op, type, name, "hint out of range");
return 0;
}
cache1->dk_version_or_hint = (uint32_t)hint;
cache1->tp_version = type->tp_version_tag;
*instr = _Py_MAKECODEUNIT(hint_op, _Py_OPARG(*instr));
return 1;
}
}
assert(type->tp_dictoffset == 0);
/* No attribute in instance dictionary */
switch(kind) {
case NON_OVERRIDING:
SPECIALIZATION_FAIL(base_op, type, name, "non-overriding descriptor");
return 0;
case NON_DESCRIPTOR:
/* To do -- Optimize this case */
SPECIALIZATION_FAIL(base_op, type, name, "non descriptor");
return 0;
case ABSENT:
SPECIALIZATION_FAIL(base_op, type, name, "no attribute");
return 0;
default:
Py_UNREACHABLE();
}
}
int
_Py_Specialize_LoadAttr(PyObject *owner, _Py_CODEUNIT *instr, PyObject *name, SpecializedCacheEntry *cache)
{
_PyAdaptiveEntry *cache0 = &cache->adaptive;
_PyLoadAttrCache *cache1 = &cache[-1].load_attr;
_PyAttrCache *cache1 = &cache[-1].attr;
if (PyModule_CheckExact(owner)) {
int err = specialize_module_load_attr(owner, instr, name, cache0, cache1);
if (err) {
@ -541,7 +634,7 @@ _Py_Specialize_LoadAttr(PyObject *owner, _Py_CODEUNIT *instr, PyObject *name, Sp
}
}
PyObject *descr;
DesciptorClassification kind = analyze_descriptor(type, name, &descr);
DesciptorClassification kind = analyze_descriptor(type, name, &descr, 0);
switch(kind) {
case OVERRIDING:
SPECIALIZATION_FAIL(LOAD_ATTR, type, name, "overriding descriptor");
@ -557,6 +650,10 @@ _Py_Specialize_LoadAttr(PyObject *owner, _Py_CODEUNIT *instr, PyObject *name, Sp
PyMemberDescrObject *member = (PyMemberDescrObject *)descr;
struct PyMemberDef *dmem = member->d_member;
Py_ssize_t offset = dmem->offset;
if (dmem->flags & PY_AUDIT_READ) {
SPECIALIZATION_FAIL(LOAD_ATTR, type, name, "audit read");
goto fail;
}
if (offset != (uint16_t)offset) {
SPECIALIZATION_FAIL(LOAD_ATTR, type, name, "offset out of range");
goto fail;
@ -583,7 +680,7 @@ _Py_Specialize_LoadAttr(PyObject *owner, _Py_CODEUNIT *instr, PyObject *name, Sp
case MUTABLE:
SPECIALIZATION_FAIL(LOAD_ATTR, type, name, "mutable class attribute");
goto fail;
case GETATTRIBUTE_OVERRIDDEN:
case GETSET_OVERRIDDEN:
SPECIALIZATION_FAIL(LOAD_ATTR, type, name, "__getattribute__ overridden");
goto fail;
case NON_OVERRIDING:
@ -591,77 +688,15 @@ _Py_Specialize_LoadAttr(PyObject *owner, _Py_CODEUNIT *instr, PyObject *name, Sp
case ABSENT:
break;
}
assert(kind == NON_OVERRIDING || kind == NON_DESCRIPTOR || kind == ABSENT);
// No desciptor, or non overriding.
if (type->tp_dictoffset < 0) {
SPECIALIZATION_FAIL(LOAD_ATTR, type, name, "negative offset");
goto fail;
int err = specialize_dict_access(
owner, instr, type, kind, name, cache0, cache1,
LOAD_ATTR, LOAD_ATTR_SPLIT_KEYS, LOAD_ATTR_WITH_HINT
);
if (err < 0) {
return -1;
}
if (type->tp_dictoffset > 0) {
PyObject **dictptr = (PyObject **) ((char *)owner + type->tp_dictoffset);
if (*dictptr == NULL || !PyDict_CheckExact(*dictptr)) {
SPECIALIZATION_FAIL(LOAD_ATTR, type, name, "no dict or not a dict");
goto fail;
}
// We found an instance with a __dict__.
PyDictObject *dict = (PyDictObject *)*dictptr;
if ((type->tp_flags & Py_TPFLAGS_HEAPTYPE)
&& dict->ma_keys == ((PyHeapTypeObject*)type)->ht_cached_keys
) {
// Keys are shared
assert(PyUnicode_CheckExact(name));
Py_hash_t hash = PyObject_Hash(name);
if (hash == -1) {
return -1;
}
PyObject *value;
Py_ssize_t index = _Py_dict_lookup(dict, name, hash, &value);
assert (index != DKIX_ERROR);
if (index != (uint16_t)index) {
SPECIALIZATION_FAIL(LOAD_ATTR, type, name,
index < 0 ? "attribute not in dict" : "index out of range");
goto fail;
}
uint32_t keys_version = _PyDictKeys_GetVersionForCurrentState(dict);
if (keys_version == 0) {
SPECIALIZATION_FAIL(LOAD_ATTR, type, name, "no more key versions");
goto fail;
}
cache1->dk_version_or_hint = keys_version;
cache1->tp_version = type->tp_version_tag;
cache0->index = (uint16_t)index;
*instr = _Py_MAKECODEUNIT(LOAD_ATTR_SPLIT_KEYS, _Py_OPARG(*instr));
goto success;
}
else {
PyObject *value = NULL;
Py_ssize_t hint =
_PyDict_GetItemHint(dict, name, -1, &value);
if (hint != (uint32_t)hint) {
SPECIALIZATION_FAIL(LOAD_ATTR, type, name, "hint out of range");
goto fail;
}
cache1->dk_version_or_hint = (uint32_t)hint;
cache1->tp_version = type->tp_version_tag;
*instr = _Py_MAKECODEUNIT(LOAD_ATTR_WITH_HINT, _Py_OPARG(*instr));
goto success;
}
}
assert(type->tp_dictoffset == 0);
/* No attribute in instance dictionary */
switch(kind) {
case NON_OVERRIDING:
SPECIALIZATION_FAIL(LOAD_ATTR, type, name, "non-overriding descriptor");
goto fail;
case NON_DESCRIPTOR:
/* To do -- Optimize this case */
SPECIALIZATION_FAIL(LOAD_ATTR, type, name, "non descriptor");
goto fail;
case ABSENT:
SPECIALIZATION_FAIL(LOAD_ATTR, type, name, "no attribute");
goto fail;
default:
Py_UNREACHABLE();
if (err) {
goto success;
}
fail:
STAT_INC(LOAD_ATTR, specialization_failure);
@ -675,6 +710,87 @@ success:
return 0;
}
int
_Py_Specialize_StoreAttr(PyObject *owner, _Py_CODEUNIT *instr, PyObject *name, SpecializedCacheEntry *cache)
{
_PyAdaptiveEntry *cache0 = &cache->adaptive;
_PyAttrCache *cache1 = &cache[-1].attr;
PyTypeObject *type = Py_TYPE(owner);
if (PyModule_CheckExact(owner)) {
SPECIALIZATION_FAIL(STORE_ATTR, type, name, "module attribute");
goto fail;
}
PyObject *descr;
DesciptorClassification kind = analyze_descriptor(type, name, &descr, 1);
switch(kind) {
case OVERRIDING:
SPECIALIZATION_FAIL(STORE_ATTR, type, name, "overriding descriptor");
goto fail;
case METHOD:
SPECIALIZATION_FAIL(STORE_ATTR, type, name, "method");
goto fail;
case PROPERTY:
SPECIALIZATION_FAIL(STORE_ATTR, type, name, "property");
goto fail;
case OBJECT_SLOT:
{
PyMemberDescrObject *member = (PyMemberDescrObject *)descr;
struct PyMemberDef *dmem = member->d_member;
Py_ssize_t offset = dmem->offset;
if (dmem->flags & READONLY) {
SPECIALIZATION_FAIL(STORE_ATTR, type, name, "read only");
goto fail;
}
if (offset != (uint16_t)offset) {
SPECIALIZATION_FAIL(STORE_ATTR, type, name, "offset out of range");
goto fail;
}
assert(dmem->type == T_OBJECT_EX);
assert(offset > 0);
cache0->index = (uint16_t)offset;
cache1->tp_version = type->tp_version_tag;
*instr = _Py_MAKECODEUNIT(STORE_ATTR_SLOT, _Py_OPARG(*instr));
goto success;
}
case DUNDER_CLASS:
case OTHER_SLOT:
SPECIALIZATION_FAIL(STORE_ATTR, type, name, "other slot");
goto fail;
case MUTABLE:
SPECIALIZATION_FAIL(STORE_ATTR, type, name, "mutable class attribute");
goto fail;
case GETSET_OVERRIDDEN:
SPECIALIZATION_FAIL(STORE_ATTR, type, name, "__setattr__ overridden");
goto fail;
case NON_OVERRIDING:
case NON_DESCRIPTOR:
case ABSENT:
break;
}
int err = specialize_dict_access(
owner, instr, type, kind, name, cache0, cache1,
STORE_ATTR, STORE_ATTR_SPLIT_KEYS, STORE_ATTR_WITH_HINT
);
if (err < 0) {
return -1;
}
if (err) {
goto success;
}
fail:
STAT_INC(STORE_ATTR, specialization_failure);
assert(!PyErr_Occurred());
cache_backoff(cache0);
return 0;
success:
STAT_INC(STORE_ATTR, specialization_success);
assert(!PyErr_Occurred());
cache0->counter = saturating_start();
return 0;
}
int
_Py_Specialize_LoadGlobal(
PyObject *globals, PyObject *builtins,