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specialize.c
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#include "Python.h"
#include "pycore_code.h"
#include "pycore_dict.h"
#include "pycore_long.h"
#include "pycore_moduleobject.h"
#include "pycore_object.h"
#include "opcode.h"
#include "structmember.h" // struct PyMemberDef, T_OFFSET_EX
#include <stdlib.h> // rand()
/* For guidance on adding or extending families of instructions see
* ./adaptive.md
*/
/* We layout the quickened data as a bi-directional array:
* Instructions upwards, cache entries downwards.
* first_instr is aligned to a SpecializedCacheEntry.
* The nth instruction is located at first_instr[n]
* The nth cache is located at ((SpecializedCacheEntry *)first_instr)[-1-n]
* The first (index 0) cache entry is reserved for the count, to enable finding
* the first instruction from the base pointer.
* The cache_count argument must include space for the count.
* We use the SpecializedCacheOrInstruction union to refer to the data
* to avoid type punning.
Layout of quickened data, each line 8 bytes for M cache entries and N instructions:
<cache_count> <---- co->co_quickened
<cache M-1>
<cache M-2>
...
<cache 0>
<instr 0> <instr 1> <instr 2> <instr 3> <--- co->co_first_instr
<instr 4> <instr 5> <instr 6> <instr 7>
...
<instr N-1>
*/
Py_ssize_t _Py_QuickenedCount = 0;
#if COLLECT_SPECIALIZATION_STATS
SpecializationStats _specialization_stats[256] = { 0 };
#define ADD_STAT_TO_DICT(res, field) \
do { \
PyObject *val = PyLong_FromUnsignedLongLong(stats->field); \
if (val == NULL) { \
Py_DECREF(res); \
return NULL; \
} \
if (PyDict_SetItemString(res, #field, val) == -1) { \
Py_DECREF(res); \
Py_DECREF(val); \
return NULL; \
} \
Py_DECREF(val); \
} while(0);
static PyObject*
stats_to_dict(SpecializationStats *stats)
{
PyObject *res = PyDict_New();
if (res == NULL) {
return NULL;
}
ADD_STAT_TO_DICT(res, specialization_success);
ADD_STAT_TO_DICT(res, specialization_failure);
ADD_STAT_TO_DICT(res, hit);
ADD_STAT_TO_DICT(res, deferred);
ADD_STAT_TO_DICT(res, miss);
ADD_STAT_TO_DICT(res, deopt);
ADD_STAT_TO_DICT(res, unquickened);
#if COLLECT_SPECIALIZATION_STATS_DETAILED
PyObject *failure_kinds = PyTuple_New(SPECIALIZATION_FAILURE_KINDS);
if (failure_kinds == NULL) {
Py_DECREF(res);
return NULL;
}
for (int i = 0; i < SPECIALIZATION_FAILURE_KINDS; i++) {
PyObject *stat = PyLong_FromUnsignedLongLong(stats->specialization_failure_kinds[i]);
if (stat == NULL) {
Py_DECREF(res);
Py_DECREF(failure_kinds);
return NULL;
}
PyTuple_SET_ITEM(failure_kinds, i, stat);
}
if (PyDict_SetItemString(res, "specialization_failure_kinds", failure_kinds)) {
Py_DECREF(res);
Py_DECREF(failure_kinds);
return NULL;
}
Py_DECREF(failure_kinds);
#endif
return res;
}
#undef ADD_STAT_TO_DICT
static int
add_stat_dict(
PyObject *res,
int opcode,
const char *name) {
SpecializationStats *stats = &_specialization_stats[opcode];
PyObject *d = stats_to_dict(stats);
if (d == NULL) {
return -1;
}
int err = PyDict_SetItemString(res, name, d);
Py_DECREF(d);
return err;
}
#if COLLECT_SPECIALIZATION_STATS
PyObject*
_Py_GetSpecializationStats(void) {
PyObject *stats = PyDict_New();
if (stats == NULL) {
return NULL;
}
int err = 0;
err += add_stat_dict(stats, LOAD_ATTR, "load_attr");
err += add_stat_dict(stats, LOAD_GLOBAL, "load_global");
err += add_stat_dict(stats, LOAD_METHOD, "load_method");
err += add_stat_dict(stats, BINARY_SUBSCR, "binary_subscr");
err += add_stat_dict(stats, STORE_SUBSCR, "store_subscr");
err += add_stat_dict(stats, STORE_ATTR, "store_attr");
err += add_stat_dict(stats, CALL_FUNCTION, "call_function");
err += add_stat_dict(stats, BINARY_OP, "binary_op");
err += add_stat_dict(stats, COMPARE_OP, "compare_op");
if (err < 0) {
Py_DECREF(stats);
return NULL;
}
return stats;
}
#endif
#define PRINT_STAT(name, field) fprintf(out, " %s." #field " : %" PRIu64 "\n", name, stats->field);
static void
print_stats(FILE *out, SpecializationStats *stats, const char *name)
{
PRINT_STAT(name, specialization_success);
PRINT_STAT(name, specialization_failure);
PRINT_STAT(name, hit);
PRINT_STAT(name, deferred);
PRINT_STAT(name, miss);
PRINT_STAT(name, deopt);
PRINT_STAT(name, unquickened);
#if PRINT_SPECIALIZATION_STATS_DETAILED
for (int i = 0; i < SPECIALIZATION_FAILURE_KINDS; i++) {
fprintf(out, " %s.specialization_failure_kinds[%d] : %" PRIu64 "\n",
name, i, stats->specialization_failure_kinds[i]);
}
#endif
}
#undef PRINT_STAT
void
_Py_PrintSpecializationStats(void)
{
FILE *out = stderr;
#if PRINT_SPECIALIZATION_STATS_TO_FILE
/* Write to a file instead of stderr. */
# ifdef MS_WINDOWS
const char *dirname = "c:\\temp\\py_stats\\";
# else
const char *dirname = "/tmp/py_stats/";
# endif
char buf[48];
sprintf(buf, "%s%u_%u.txt", dirname, (unsigned)clock(), (unsigned)rand());
FILE *fout = fopen(buf, "w");
if (fout) {
out = fout;
}
#else
fprintf(out, "Specialization stats:\n");
#endif
print_stats(out, &_specialization_stats[LOAD_ATTR], "load_attr");
print_stats(out, &_specialization_stats[LOAD_GLOBAL], "load_global");
print_stats(out, &_specialization_stats[LOAD_METHOD], "load_method");
print_stats(out, &_specialization_stats[BINARY_SUBSCR], "binary_subscr");
print_stats(out, &_specialization_stats[STORE_SUBSCR], "store_subscr");
print_stats(out, &_specialization_stats[STORE_ATTR], "store_attr");
print_stats(out, &_specialization_stats[CALL_FUNCTION], "call_function");
print_stats(out, &_specialization_stats[BINARY_OP], "binary_op");
print_stats(out, &_specialization_stats[COMPARE_OP], "compare_op");
if (out != stderr) {
fclose(out);
}
}
#if COLLECT_SPECIALIZATION_STATS_DETAILED
#define SPECIALIZATION_FAIL(opcode, kind) _specialization_stats[opcode].specialization_failure_kinds[kind]++
#endif
#endif
#ifndef SPECIALIZATION_FAIL
#define SPECIALIZATION_FAIL(opcode, kind) ((void)0)
#endif
static SpecializedCacheOrInstruction *
allocate(int cache_count, int instruction_count)
{
assert(sizeof(SpecializedCacheOrInstruction) == 2*sizeof(int32_t));
assert(sizeof(SpecializedCacheEntry) == 2*sizeof(int32_t));
assert(cache_count > 0);
assert(instruction_count > 0);
int count = cache_count + (instruction_count + INSTRUCTIONS_PER_ENTRY -1)/INSTRUCTIONS_PER_ENTRY;
SpecializedCacheOrInstruction *array = (SpecializedCacheOrInstruction *)
PyMem_Malloc(sizeof(SpecializedCacheOrInstruction) * count);
if (array == NULL) {
PyErr_NoMemory();
return NULL;
}
_Py_QuickenedCount++;
array[0].entry.zero.cache_count = cache_count;
return array;
}
static int
get_cache_count(SpecializedCacheOrInstruction *quickened) {
return quickened[0].entry.zero.cache_count;
}
/* Map from opcode to adaptive opcode.
Values of zero are ignored. */
static uint8_t adaptive_opcodes[256] = {
[LOAD_ATTR] = LOAD_ATTR_ADAPTIVE,
[LOAD_GLOBAL] = LOAD_GLOBAL_ADAPTIVE,
[LOAD_METHOD] = LOAD_METHOD_ADAPTIVE,
[BINARY_SUBSCR] = BINARY_SUBSCR_ADAPTIVE,
[STORE_SUBSCR] = STORE_SUBSCR_ADAPTIVE,
[CALL_FUNCTION] = CALL_FUNCTION_ADAPTIVE,
[STORE_ATTR] = STORE_ATTR_ADAPTIVE,
[BINARY_OP] = BINARY_OP_ADAPTIVE,
[COMPARE_OP] = COMPARE_OP_ADAPTIVE,
};
/* The number of cache entries required for a "family" of instructions. */
static uint8_t cache_requirements[256] = {
[LOAD_ATTR] = 2, /* _PyAdaptiveEntry and _PyAttrCache */
[LOAD_GLOBAL] = 2, /* _PyAdaptiveEntry and _PyLoadGlobalCache */
[LOAD_METHOD] = 3, /* _PyAdaptiveEntry, _PyAttrCache and _PyObjectCache */
[BINARY_SUBSCR] = 2, /* _PyAdaptiveEntry, _PyObjectCache */
[STORE_SUBSCR] = 0,
[CALL_FUNCTION] = 2, /* _PyAdaptiveEntry and _PyObjectCache/_PyCallCache */
[STORE_ATTR] = 2, /* _PyAdaptiveEntry and _PyAttrCache */
[BINARY_OP] = 1, // _PyAdaptiveEntry
[COMPARE_OP] = 1, /* _PyAdaptiveEntry */
};
/* Return the oparg for the cache_offset and instruction index.
*
* If no cache is needed then return the original oparg.
* If a cache is needed, but cannot be accessed because
* oparg would be too large, then return -1.
*
* Also updates the cache_offset, as it may need to be incremented by
* more than the cache requirements, if many instructions do not need caches.
*
* See pycore_code.h for details of how the cache offset,
* instruction index and oparg are related */
static int
oparg_from_instruction_and_update_offset(int index, int opcode, int original_oparg, int *cache_offset) {
/* The instruction pointer in the interpreter points to the next
* instruction, so we compute the offset using nexti (index + 1) */
int nexti = index + 1;
uint8_t need = cache_requirements[opcode];
if (need == 0) {
return original_oparg;
}
assert(adaptive_opcodes[opcode] != 0);
int oparg = oparg_from_offset_and_nexti(*cache_offset, nexti);
assert(*cache_offset == offset_from_oparg_and_nexti(oparg, nexti));
/* Some cache space is wasted here as the minimum possible offset is (nexti>>1) */
if (oparg < 0) {
oparg = 0;
*cache_offset = offset_from_oparg_and_nexti(oparg, nexti);
}
else if (oparg > 255) {
return -1;
}
*cache_offset += need;
return oparg;
}
static int
entries_needed(const _Py_CODEUNIT *code, int len)
{
int cache_offset = 0;
int previous_opcode = -1;
for (int i = 0; i < len; i++) {
uint8_t opcode = _Py_OPCODE(code[i]);
if (previous_opcode != EXTENDED_ARG) {
oparg_from_instruction_and_update_offset(i, opcode, 0, &cache_offset);
}
previous_opcode = opcode;
}
return cache_offset + 1; // One extra for the count entry
}
static inline _Py_CODEUNIT *
first_instruction(SpecializedCacheOrInstruction *quickened)
{
return &quickened[get_cache_count(quickened)].code[0];
}
/** Insert adaptive instructions and superinstructions.
*
* Skip instruction preceded by EXTENDED_ARG for adaptive
* instructions as those are both very rare and tricky
* to handle.
*/
static void
optimize(SpecializedCacheOrInstruction *quickened, int len)
{
_Py_CODEUNIT *instructions = first_instruction(quickened);
int cache_offset = 0;
int previous_opcode = -1;
int previous_oparg = 0;
for(int i = 0; i < len; i++) {
int opcode = _Py_OPCODE(instructions[i]);
int oparg = _Py_OPARG(instructions[i]);
uint8_t adaptive_opcode = adaptive_opcodes[opcode];
if (adaptive_opcode && previous_opcode != EXTENDED_ARG) {
int new_oparg = oparg_from_instruction_and_update_offset(
i, opcode, oparg, &cache_offset
);
if (new_oparg < 0) {
/* Not possible to allocate a cache for this instruction */
previous_opcode = opcode;
continue;
}
previous_opcode = adaptive_opcode;
int entries_needed = cache_requirements[opcode];
if (entries_needed) {
/* Initialize the adpative cache entry */
int cache0_offset = cache_offset-entries_needed;
SpecializedCacheEntry *cache =
_GetSpecializedCacheEntry(instructions, cache0_offset);
cache->adaptive.original_oparg = oparg;
cache->adaptive.counter = 0;
} else {
// oparg is the adaptive cache counter
new_oparg = 0;
}
instructions[i] = _Py_MAKECODEUNIT(adaptive_opcode, new_oparg);
}
else {
/* Super instructions don't use the cache,
* so no need to update the offset. */
switch (opcode) {
case JUMP_ABSOLUTE:
instructions[i] = _Py_MAKECODEUNIT(JUMP_ABSOLUTE_QUICK, oparg);
break;
case LOAD_FAST:
switch(previous_opcode) {
case LOAD_FAST:
instructions[i-1] = _Py_MAKECODEUNIT(LOAD_FAST__LOAD_FAST, previous_oparg);
break;
case STORE_FAST:
instructions[i-1] = _Py_MAKECODEUNIT(STORE_FAST__LOAD_FAST, previous_oparg);
break;
case LOAD_CONST:
instructions[i-1] = _Py_MAKECODEUNIT(LOAD_CONST__LOAD_FAST, previous_oparg);
break;
}
break;
case STORE_FAST:
if (previous_opcode == STORE_FAST) {
instructions[i-1] = _Py_MAKECODEUNIT(STORE_FAST__STORE_FAST, previous_oparg);
}
break;
case LOAD_CONST:
if (previous_opcode == LOAD_FAST) {
instructions[i-1] = _Py_MAKECODEUNIT(LOAD_FAST__LOAD_CONST, previous_oparg);
}
break;
}
previous_opcode = opcode;
previous_oparg = oparg;
}
}
assert(cache_offset+1 == get_cache_count(quickened));
}
int
_Py_Quicken(PyCodeObject *code) {
if (code->co_quickened) {
return 0;
}
Py_ssize_t size = PyBytes_GET_SIZE(code->co_code);
int instr_count = (int)(size/sizeof(_Py_CODEUNIT));
if (instr_count > MAX_SIZE_TO_QUICKEN) {
code->co_warmup = QUICKENING_WARMUP_COLDEST;
return 0;
}
int entry_count = entries_needed(code->co_firstinstr, instr_count);
SpecializedCacheOrInstruction *quickened = allocate(entry_count, instr_count);
if (quickened == NULL) {
return -1;
}
_Py_CODEUNIT *new_instructions = first_instruction(quickened);
memcpy(new_instructions, code->co_firstinstr, size);
optimize(quickened, instr_count);
code->co_quickened = quickened;
code->co_firstinstr = new_instructions;
return 0;
}
static inline int
initial_counter_value(void) {
/* Starting value for the counter.
* This value needs to be not too low, otherwise
* it would cause excessive de-optimization.
* Neither should it be too high, or that would delay
* de-optimization excessively when it is needed.
* A value around 50 seems to work, and we choose a
* prime number to avoid artifacts.
*/
return 53;
}
/* Common */
#define SPEC_FAIL_OTHER 0
#define SPEC_FAIL_NO_DICT 1
#define SPEC_FAIL_OVERRIDDEN 2
#define SPEC_FAIL_OUT_OF_VERSIONS 3
#define SPEC_FAIL_OUT_OF_RANGE 4
#define SPEC_FAIL_EXPECTED_ERROR 5
/* Attributes */
#define SPEC_FAIL_NON_STRING_OR_SPLIT 6
#define SPEC_FAIL_MODULE_ATTR_NOT_FOUND 7
#define SPEC_FAIL_OVERRIDING_DESCRIPTOR 8
#define SPEC_FAIL_NON_OVERRIDING_DESCRIPTOR 9
#define SPEC_FAIL_NOT_DESCRIPTOR 10
#define SPEC_FAIL_METHOD 11
#define SPEC_FAIL_MUTABLE_CLASS 12
#define SPEC_FAIL_PROPERTY 13
#define SPEC_FAIL_NON_OBJECT_SLOT 14
#define SPEC_FAIL_READ_ONLY 15
#define SPEC_FAIL_AUDITED_SLOT 16
#define SPEC_FAIL_NOT_MANAGED_DICT 17
/* Methods */
#define SPEC_FAIL_IS_ATTR 15
#define SPEC_FAIL_DICT_SUBCLASS 16
#define SPEC_FAIL_BUILTIN_CLASS_METHOD 17
#define SPEC_FAIL_CLASS_METHOD_OBJ 18
#define SPEC_FAIL_OBJECT_SLOT 19
/* Binary subscr */
#define SPEC_FAIL_ARRAY_INT 8
#define SPEC_FAIL_ARRAY_SLICE 9
#define SPEC_FAIL_LIST_SLICE 10
#define SPEC_FAIL_TUPLE_SLICE 11
#define SPEC_FAIL_STRING_INT 12
#define SPEC_FAIL_STRING_SLICE 13
#define SPEC_FAIL_BUFFER_INT 15
#define SPEC_FAIL_BUFFER_SLICE 16
#define SPEC_FAIL_SEQUENCE_INT 17
/* Binary add */
#define SPEC_FAIL_NON_FUNCTION_SCOPE 11
#define SPEC_FAIL_DIFFERENT_TYPES 12
/* Calls */
#define SPEC_FAIL_GENERATOR 7
#define SPEC_FAIL_COMPLEX_PARAMETERS 8
#define SPEC_FAIL_WRONG_NUMBER_ARGUMENTS 9
#define SPEC_FAIL_CO_NOT_OPTIMIZED 10
/* SPEC_FAIL_METHOD defined as 11 above */
#define SPEC_FAIL_PYCFUNCTION 13
#define SPEC_FAIL_PYCFUNCTION_WITH_KEYWORDS 14
#define SPEC_FAIL_PYCFUNCTION_FAST_WITH_KEYWORDS 15
#define SPEC_FAIL_PYCFUNCTION_NOARGS 16
#define SPEC_FAIL_BAD_CALL_FLAGS 17
#define SPEC_FAIL_CLASS 18
/* COMPARE_OP */
#define SPEC_FAIL_STRING_COMPARE 13
#define SPEC_FAIL_NOT_FOLLOWED_BY_COND_JUMP 14
#define SPEC_FAIL_BIG_INT 15
static int
specialize_module_load_attr(
PyObject *owner, _Py_CODEUNIT *instr, PyObject *name,
_PyAdaptiveEntry *cache0, _PyAttrCache *cache1, int opcode,
int opcode_module)
{
PyModuleObject *m = (PyModuleObject *)owner;
PyObject *value = NULL;
PyObject *getattr;
_Py_IDENTIFIER(__getattr__);
assert((owner->ob_type->tp_flags & Py_TPFLAGS_MANAGED_DICT) == 0);
PyDictObject *dict = (PyDictObject *)m->md_dict;
if (dict == NULL) {
SPECIALIZATION_FAIL(opcode, SPEC_FAIL_NO_DICT);
return -1;
}
if (dict->ma_keys->dk_kind != DICT_KEYS_UNICODE) {
SPECIALIZATION_FAIL(opcode, SPEC_FAIL_NON_STRING_OR_SPLIT);
return -1;
}
getattr = _PyUnicode_FromId(&PyId___getattr__); /* borrowed */
if (getattr == NULL) {
SPECIALIZATION_FAIL(opcode, SPEC_FAIL_OVERRIDDEN);
PyErr_Clear();
return -1;
}
Py_ssize_t index = _PyDict_GetItemHint(dict, getattr, -1, &value);
assert(index != DKIX_ERROR);
if (index != DKIX_EMPTY) {
SPECIALIZATION_FAIL(opcode, SPEC_FAIL_MODULE_ATTR_NOT_FOUND);
return -1;
}
index = _PyDict_GetItemHint(dict, name, -1, &value);
assert (index != DKIX_ERROR);
if (index != (uint16_t)index) {
SPECIALIZATION_FAIL(opcode, SPEC_FAIL_OUT_OF_RANGE);
return -1;
}
uint32_t keys_version = _PyDictKeys_GetVersionForCurrentState(dict->ma_keys);
if (keys_version == 0) {
SPECIALIZATION_FAIL(opcode, SPEC_FAIL_OUT_OF_VERSIONS);
return -1;
}
cache1->dk_version_or_hint = keys_version;
cache0->index = (uint16_t)index;
*instr = _Py_MAKECODEUNIT(opcode_module, _Py_OPARG(*instr));
return 0;
}
/* Attribute specialization */
typedef enum {
OVERRIDING, /* Is an overriding descriptor, and will remain so. */
METHOD, /* Attribute has Py_TPFLAGS_METHOD_DESCRIPTOR set */
PROPERTY, /* Is a property */
OBJECT_SLOT, /* Is an object slot descriptor */
OTHER_SLOT, /* Is a slot descriptor of another type */
NON_OVERRIDING, /* Is another non-overriding descriptor, and is an instance of an immutable class*/
BUILTIN_CLASSMETHOD, /* Builtin methods with METH_CLASS */
PYTHON_CLASSMETHOD, /* Python classmethod(func) object */
NON_DESCRIPTOR, /* Is not a descriptor, and is an instance of an immutable class */
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 */
GETSET_OVERRIDDEN /* __getattribute__ or __setattr__ has been overridden */
} DesciptorClassification;
static DesciptorClassification
analyze_descriptor(PyTypeObject *type, PyObject *name, PyObject **descr, int store)
{
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;
if (descriptor == NULL) {
return ABSENT;
}
PyTypeObject *desc_cls = Py_TYPE(descriptor);
if (!(desc_cls->tp_flags & Py_TPFLAGS_IMMUTABLETYPE)) {
return MUTABLE;
}
if (desc_cls->tp_descr_set) {
if (desc_cls == &PyMemberDescr_Type) {
PyMemberDescrObject *member = (PyMemberDescrObject *)descriptor;
struct PyMemberDef *dmem = member->d_member;
if (dmem->type == T_OBJECT_EX) {
return OBJECT_SLOT;
}
return OTHER_SLOT;
}
if (desc_cls == &PyProperty_Type) {
return PROPERTY;
}
if (PyUnicode_CompareWithASCIIString(name, "__class__") == 0) {
if (descriptor == _PyType_Lookup(&PyBaseObject_Type, name)) {
return DUNDER_CLASS;
}
}
return OVERRIDING;
}
if (desc_cls->tp_descr_get) {
if (desc_cls->tp_flags & Py_TPFLAGS_METHOD_DESCRIPTOR) {
return METHOD;
}
if (Py_IS_TYPE(descriptor, &PyClassMethodDescr_Type)) {
return BUILTIN_CLASSMETHOD;
}
if (Py_IS_TYPE(descriptor, &PyClassMethod_Type)) {
return PYTHON_CLASSMETHOD;
}
return NON_OVERRIDING;
}
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 values_op, int hint_op)
{
assert(kind == NON_OVERRIDING || kind == NON_DESCRIPTOR || kind == ABSENT ||
kind == BUILTIN_CLASSMETHOD || kind == PYTHON_CLASSMETHOD);
// No descriptor, or non overriding.
if ((type->tp_flags & Py_TPFLAGS_MANAGED_DICT) == 0) {
SPECIALIZATION_FAIL(base_op, SPEC_FAIL_NOT_MANAGED_DICT);
return 0;
}
PyObject **dictptr = _PyObject_ManagedDictPointer(owner);
PyDictObject *dict = (PyDictObject *)*dictptr;
if (dict == NULL) {
// Virtual dictionary
PyDictKeysObject *keys = ((PyHeapTypeObject *)type)->ht_cached_keys;
assert(PyUnicode_CheckExact(name));
Py_ssize_t index = _PyDictKeys_StringLookup(keys, name);
assert (index != DKIX_ERROR);
if (index != (uint16_t)index) {
SPECIALIZATION_FAIL(base_op, SPEC_FAIL_OUT_OF_RANGE);
return 0;
}
cache1->tp_version = type->tp_version_tag;
cache0->index = (uint16_t)index;
*instr = _Py_MAKECODEUNIT(values_op, _Py_OPARG(*instr));
}
else {
if (!PyDict_CheckExact(dict)) {
SPECIALIZATION_FAIL(base_op, SPEC_FAIL_NO_DICT);
return 0;
}
// We found an instance with a __dict__.
PyObject *value = NULL;
Py_ssize_t hint =
_PyDict_GetItemHint(dict, name, -1, &value);
if (hint != (uint32_t)hint) {
SPECIALIZATION_FAIL(base_op, SPEC_FAIL_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;
}
int
_Py_Specialize_LoadAttr(PyObject *owner, _Py_CODEUNIT *instr, PyObject *name, SpecializedCacheEntry *cache)
{
_PyAdaptiveEntry *cache0 = &cache->adaptive;
_PyAttrCache *cache1 = &cache[-1].attr;
if (PyModule_CheckExact(owner)) {
int err = specialize_module_load_attr(owner, instr, name, cache0, cache1,
LOAD_ATTR, LOAD_ATTR_MODULE);
if (err) {
goto fail;
}
goto success;
}
PyTypeObject *type = Py_TYPE(owner);
if (type->tp_dict == NULL) {
if (PyType_Ready(type) < 0) {
return -1;
}
}
PyObject *descr;
DesciptorClassification kind = analyze_descriptor(type, name, &descr, 0);
switch(kind) {
case OVERRIDING:
SPECIALIZATION_FAIL(LOAD_ATTR, SPEC_FAIL_OVERRIDING_DESCRIPTOR);
goto fail;
case METHOD:
SPECIALIZATION_FAIL(LOAD_ATTR, SPEC_FAIL_METHOD);
goto fail;
case PROPERTY:
SPECIALIZATION_FAIL(LOAD_ATTR, SPEC_FAIL_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 & PY_AUDIT_READ) {
SPECIALIZATION_FAIL(LOAD_ATTR, SPEC_FAIL_AUDITED_SLOT);
goto fail;
}
if (offset != (uint16_t)offset) {
SPECIALIZATION_FAIL(LOAD_ATTR, SPEC_FAIL_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(LOAD_ATTR_SLOT, _Py_OPARG(*instr));
goto success;
}
case DUNDER_CLASS:
{
Py_ssize_t offset = offsetof(PyObject, ob_type);
assert(offset == (uint16_t)offset);
cache0->index = (uint16_t)offset;
cache1->tp_version = type->tp_version_tag;
*instr = _Py_MAKECODEUNIT(LOAD_ATTR_SLOT, _Py_OPARG(*instr));
goto success;
}
case OTHER_SLOT:
SPECIALIZATION_FAIL(LOAD_ATTR, SPEC_FAIL_NON_OBJECT_SLOT);
goto fail;
case MUTABLE:
SPECIALIZATION_FAIL(LOAD_ATTR, SPEC_FAIL_MUTABLE_CLASS);
goto fail;
case GETSET_OVERRIDDEN:
SPECIALIZATION_FAIL(LOAD_ATTR, SPEC_FAIL_OVERRIDDEN);
goto fail;
case BUILTIN_CLASSMETHOD:
case PYTHON_CLASSMETHOD:
case NON_OVERRIDING:
case NON_DESCRIPTOR:
case ABSENT:
break;
}
int err = specialize_dict_access(
owner, instr, type, kind, name, cache0, cache1,
LOAD_ATTR, LOAD_ATTR_INSTANCE_VALUE, LOAD_ATTR_WITH_HINT
);
if (err < 0) {
return -1;
}
if (err) {
goto success;
}
fail:
STAT_INC(LOAD_ATTR, specialization_failure);
assert(!PyErr_Occurred());
cache_backoff(cache0);
return 0;
success:
STAT_INC(LOAD_ATTR, specialization_success);
assert(!PyErr_Occurred());
cache0->counter = initial_counter_value();
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, SPEC_FAIL_OVERRIDDEN);
goto fail;
}
PyObject *descr;
DesciptorClassification kind = analyze_descriptor(type, name, &descr, 1);
switch(kind) {
case OVERRIDING:
SPECIALIZATION_FAIL(STORE_ATTR, SPEC_FAIL_OVERRIDING_DESCRIPTOR);
goto fail;
case METHOD:
SPECIALIZATION_FAIL(STORE_ATTR, SPEC_FAIL_METHOD);
goto fail;
case PROPERTY:
SPECIALIZATION_FAIL(STORE_ATTR, SPEC_FAIL_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, SPEC_FAIL_READ_ONLY);
goto fail;
}
if (offset != (uint16_t)offset) {
SPECIALIZATION_FAIL(STORE_ATTR, SPEC_FAIL_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, SPEC_FAIL_NON_OBJECT_SLOT);
goto fail;
case MUTABLE:
SPECIALIZATION_FAIL(STORE_ATTR, SPEC_FAIL_MUTABLE_CLASS);
goto fail;
case GETSET_OVERRIDDEN:
SPECIALIZATION_FAIL(STORE_ATTR, SPEC_FAIL_OVERRIDDEN);
goto fail;
case BUILTIN_CLASSMETHOD:
case PYTHON_CLASSMETHOD:
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_INSTANCE_VALUE, 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 = initial_counter_value();
return 0;
}
#if COLLECT_SPECIALIZATION_STATS_DETAILED
static int
load_method_fail_kind(DesciptorClassification kind)
{
switch (kind) {
case OVERRIDING:
return SPEC_FAIL_OVERRIDING_DESCRIPTOR;
case METHOD:
return SPEC_FAIL_METHOD;
case PROPERTY:
return SPEC_FAIL_PROPERTY;
case OBJECT_SLOT:
return SPEC_FAIL_OBJECT_SLOT;
case OTHER_SLOT:
return SPEC_FAIL_NON_OBJECT_SLOT;
case DUNDER_CLASS:
return SPEC_FAIL_OTHER;
case MUTABLE:
return SPEC_FAIL_MUTABLE_CLASS;
case GETSET_OVERRIDDEN:
return SPEC_FAIL_OVERRIDDEN;
case BUILTIN_CLASSMETHOD:
return SPEC_FAIL_BUILTIN_CLASS_METHOD;
case PYTHON_CLASSMETHOD:
return SPEC_FAIL_CLASS_METHOD_OBJ;
case NON_OVERRIDING:
return SPEC_FAIL_NON_OVERRIDING_DESCRIPTOR;
case NON_DESCRIPTOR:
return SPEC_FAIL_NOT_DESCRIPTOR;
case ABSENT:
return SPEC_FAIL_EXPECTED_ERROR;
}
Py_UNREACHABLE();
}
#endif
static int
specialize_class_load_method(PyObject *owner, _Py_CODEUNIT *instr, PyObject *name,
_PyAttrCache *cache1, _PyObjectCache *cache2)
{
PyObject *descr = NULL;
DesciptorClassification kind = 0;
kind = analyze_descriptor((PyTypeObject *)owner, name, &descr, 0);
switch (kind) {
case METHOD:
case NON_DESCRIPTOR:
cache1->tp_version = ((PyTypeObject *)owner)->tp_version_tag;
cache2->obj = descr;
*instr = _Py_MAKECODEUNIT(LOAD_METHOD_CLASS, _Py_OPARG(*instr));
return 0;
default:
SPECIALIZATION_FAIL(LOAD_METHOD, load_method_fail_kind(kind));
return -1;
}
}
// Please collect stats carefully before and after modifying. A subtle change
// can cause a significant drop in cache hits. A possible test is
// python.exe -m test_typing test_re test_dis test_zlib.
int
_Py_Specialize_LoadMethod(PyObject *owner, _Py_CODEUNIT *instr, PyObject *name, SpecializedCacheEntry *cache)
{
_PyAdaptiveEntry *cache0 = &cache->adaptive;
_PyAttrCache *cache1 = &cache[-1].attr;
_PyObjectCache *cache2 = &cache[-2].obj;
PyTypeObject *owner_cls = Py_TYPE(owner);
if (PyModule_CheckExact(owner)) {
int err = specialize_module_load_attr(owner, instr, name, cache0, cache1,
LOAD_METHOD, LOAD_METHOD_MODULE);
if (err) {
goto fail;
}
goto success;
}
if (owner_cls->tp_dict == NULL) {
if (PyType_Ready(owner_cls) < 0) {
return -1;
}
}
if (PyType_Check(owner)) {
int err = specialize_class_load_method(owner, instr, name, cache1, cache2);
if (err) {
goto fail;
}
goto success;
}
PyObject *descr = NULL;
DesciptorClassification kind = 0;
kind = analyze_descriptor(owner_cls, name, &descr, 0);
assert(descr != NULL || kind == ABSENT || kind == GETSET_OVERRIDDEN);
if (kind != METHOD) {
SPECIALIZATION_FAIL(LOAD_METHOD, load_method_fail_kind(kind));
goto fail;
}
if (owner_cls->tp_flags & Py_TPFLAGS_MANAGED_DICT) {
PyObject **owner_dictptr = _PyObject_ManagedDictPointer(owner);
if (*owner_dictptr) {
SPECIALIZATION_FAIL(LOAD_METHOD, SPEC_FAIL_IS_ATTR);
goto fail;
}
PyDictKeysObject *keys = ((PyHeapTypeObject *)owner_cls)->ht_cached_keys;
Py_ssize_t index = _PyDictKeys_StringLookup(keys, name);
if (index != DKIX_EMPTY) {
SPECIALIZATION_FAIL(LOAD_METHOD, SPEC_FAIL_IS_ATTR);
goto fail;
}
uint32_t keys_version = _PyDictKeys_GetVersionForCurrentState(keys);
if (keys_version == 0) {
SPECIALIZATION_FAIL(LOAD_METHOD, SPEC_FAIL_OUT_OF_VERSIONS);
goto fail;
}
cache1->dk_version_or_hint = keys_version;
*instr = _Py_MAKECODEUNIT(LOAD_METHOD_CACHED, _Py_OPARG(*instr));
}
else {
if (owner_cls->tp_dictoffset == 0) {
*instr = _Py_MAKECODEUNIT(LOAD_METHOD_NO_DICT, _Py_OPARG(*instr));
}
else {
SPECIALIZATION_FAIL(LOAD_METHOD, SPEC_FAIL_IS_ATTR);
goto fail;
}
}
/* `descr` is borrowed. This is safe for methods (even inherited ones from
* super classes!) as long as tp_version_tag is validated for two main reasons:
*
* 1. The class will always hold a reference to the method so it will
* usually not be GC-ed. Should it be deleted in Python, e.g.
* `del obj.meth`, tp_version_tag will be invalidated, because of reason 2.
*
* 2. The pre-existing type method cache (MCACHE) uses the same principles
* of caching a borrowed descriptor. The MCACHE infrastructure does all the
* heavy lifting for us. E.g. it invalidates tp_version_tag on any MRO
* modification, on any type object change along said MRO, etc. (see
* PyType_Modified usages in typeobject.c). The MCACHE has been
* working since Python 2.6 and it's battle-tested.
*/
cache1->tp_version = owner_cls->tp_version_tag;
cache2->obj = descr;