cpython/Python/optimizer.c at main · https-github-com-nzysoft/cpython · GitHub

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#include "Python.h"

#include "opcode.h"

#include "pycore_interp.h"

#include "pycore_bitutils.h" // _Py_popcount32()

#include "pycore_opcode_metadata.h" // _PyOpcode_OpName()

#include "pycore_opcode_utils.h" // MAX_REAL_OPCODE

#include "pycore_optimizer.h" // _Py_uop_analyze_and_optimize()

#include "pycore_pystate.h" // _PyInterpreterState_GET()

#include "pycore_uops.h"

#include "cpython/optimizer.h"

#include <stdbool.h>

#include <stdint.h>

#include <stddef.h>

#define MAX_EXECUTORS_SIZE 256

static bool

has_space_for_executor(PyCodeObject *code, _Py_CODEUNIT *instr)

{

if (instr->op.code == ENTER_EXECUTOR) {

return true;

}

if (code->co_executors == NULL) {

return true;

}

return code->co_executors->size < MAX_EXECUTORS_SIZE;

}

static int32_t

get_index_for_executor(PyCodeObject *code, _Py_CODEUNIT *instr)

{

if (instr->op.code == ENTER_EXECUTOR) {

return instr->op.arg;

}

_PyExecutorArray *old = code->co_executors;

int size = 0;

int capacity = 0;

if (old != NULL) {

size = old->size;

capacity = old->capacity;

assert(size < MAX_EXECUTORS_SIZE);

}

assert(size <= capacity);

if (size == capacity) {

/* Array is full. Grow array */

int new_capacity = capacity ? capacity * 2 : 4;

_PyExecutorArray *new = PyMem_Realloc(

old,

offsetof(_PyExecutorArray, executors) +

new_capacity * sizeof(_PyExecutorObject *));

if (new == NULL) {

return -1;

}

new->capacity = new_capacity;

new->size = size;

code->co_executors = new;

}

assert(size < code->co_executors->capacity);

return size;

}

static void

insert_executor(PyCodeObject *code, _Py_CODEUNIT *instr, int index, _PyExecutorObject *executor)

{

Py_INCREF(executor);

if (instr->op.code == ENTER_EXECUTOR) {

assert(index == instr->op.arg);

_PyExecutorObject *old = code->co_executors->executors[index];

executor->vm_data.opcode = old->vm_data.opcode;

executor->vm_data.oparg = old->vm_data.oparg;

old->vm_data.opcode = 0;

code->co_executors->executors[index] = executor;

Py_DECREF(old);

}

else {

assert(code->co_executors->size == index);

assert(code->co_executors->capacity > index);

executor->vm_data.opcode = instr->op.code;

executor->vm_data.oparg = instr->op.arg;

code->co_executors->executors[index] = executor;

assert(index < MAX_EXECUTORS_SIZE);

instr->op.code = ENTER_EXECUTOR;

instr->op.arg = index;

code->co_executors->size++;

}

return;

}

int

PyUnstable_Replace_Executor(PyCodeObject *code, _Py_CODEUNIT *instr, _PyExecutorObject *new)

{

if (instr->op.code != ENTER_EXECUTOR) {

PyErr_Format(PyExc_ValueError, "No executor to replace");

return -1;

}

int index = instr->op.arg;

assert(index >= 0);

insert_executor(code, instr, index, new);

return 0;

}

static int

error_optimize(

_PyOptimizerObject* self,

PyCodeObject *code,

_Py_CODEUNIT *instr,

_PyExecutorObject **exec,

int Py_UNUSED(stack_entries))

{

PyErr_Format(PyExc_SystemError, "Should never call error_optimize");

return -1;

}

static PyTypeObject DefaultOptimizer_Type = {

PyVarObject_HEAD_INIT(&PyType_Type, 0)

.tp_name = "noop_optimizer",

.tp_basicsize = sizeof(_PyOptimizerObject),

.tp_itemsize = 0,

.tp_flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_DISALLOW_INSTANTIATION,

};

_PyOptimizerObject _PyOptimizer_Default = {

PyObject_HEAD_INIT(&DefaultOptimizer_Type)

.optimize = error_optimize,

.resume_threshold = UINT16_MAX,

.backedge_threshold = UINT16_MAX,

};

_PyOptimizerObject *

PyUnstable_GetOptimizer(void)

{

PyInterpreterState *interp = _PyInterpreterState_GET();

if (interp->optimizer == &_PyOptimizer_Default) {

return NULL;

}

assert(interp->optimizer_backedge_threshold == interp->optimizer->backedge_threshold);

assert(interp->optimizer_resume_threshold == interp->optimizer->resume_threshold);

Py_INCREF(interp->optimizer);

return interp->optimizer;

}

void

PyUnstable_SetOptimizer(_PyOptimizerObject *optimizer)

{

PyInterpreterState *interp = _PyInterpreterState_GET();

if (optimizer == NULL) {

optimizer = &_PyOptimizer_Default;

}

_PyOptimizerObject *old = interp->optimizer;

Py_INCREF(optimizer);

interp->optimizer = optimizer;

interp->optimizer_backedge_threshold = optimizer->backedge_threshold;

interp->optimizer_resume_threshold = optimizer->resume_threshold;

Py_DECREF(old);

}

int

_PyOptimizer_BackEdge(_PyInterpreterFrame *frame, _Py_CODEUNIT *src, _Py_CODEUNIT *dest, PyObject **stack_pointer)

{

assert(src->op.code == JUMP_BACKWARD);

PyCodeObject *code = (PyCodeObject *)frame->f_executable;

assert(PyCode_Check(code));

PyInterpreterState *interp = _PyInterpreterState_GET();

if (!has_space_for_executor(code, src)) {

return 0;

}

_PyOptimizerObject *opt = interp->optimizer;

_PyExecutorObject *executor = NULL;

int err = opt->optimize(opt, code, dest, &executor, (int)(stack_pointer - _PyFrame_Stackbase(frame)));

if (err <= 0) {

assert(executor == NULL);

return err;

}

int index = get_index_for_executor(code, src);

if (index < 0) {

/* Out of memory. Don't raise and assume that the

* error will show up elsewhere.

* If an optimizer has already produced an executor,

* it might get confused by the executor disappearing,

* but there is not much we can do about that here. */

Py_DECREF(executor);

return 0;

}

insert_executor(code, src, index, executor);

Py_DECREF(executor);

return 1;

}

_PyExecutorObject *

PyUnstable_GetExecutor(PyCodeObject *code, int offset)

{

int code_len = (int)Py_SIZE(code);

for (int i = 0 ; i < code_len;) {

if (_PyCode_CODE(code)[i].op.code == ENTER_EXECUTOR && i*2 == offset) {

int oparg = _PyCode_CODE(code)[i].op.arg;

_PyExecutorObject *res = code->co_executors->executors[oparg];

Py_INCREF(res);

return res;

}

i += _PyInstruction_GetLength(code, i);

}

PyErr_SetString(PyExc_ValueError, "no executor at given byte offset");

return NULL;

}

/** Test support **/

typedef struct {

_PyOptimizerObject base;

int64_t count;

} _PyCounterOptimizerObject;

typedef struct {

_PyExecutorObject executor;

_PyCounterOptimizerObject *optimizer;

_Py_CODEUNIT *next_instr;

} _PyCounterExecutorObject;

static void

counter_dealloc(_PyCounterExecutorObject *self) {

_Py_ExecutorClear((_PyExecutorObject *)self);

Py_DECREF(self->optimizer);

PyObject_Free(self);

}

static PyObject *

is_valid(PyObject *self, PyObject *Py_UNUSED(ignored))

{

return PyBool_FromLong(((_PyExecutorObject *)self)->vm_data.valid);

}

static PyMethodDef executor_methods[] = {

{ "is_valid", is_valid, METH_NOARGS, NULL },

{ NULL, NULL },

};

static PyTypeObject CounterExecutor_Type = {

PyVarObject_HEAD_INIT(&PyType_Type, 0)

.tp_name = "counting_executor",

.tp_basicsize = sizeof(_PyCounterExecutorObject),

.tp_itemsize = 0,

.tp_flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_DISALLOW_INSTANTIATION,

.tp_dealloc = (destructor)counter_dealloc,

.tp_methods = executor_methods,

};

static _PyInterpreterFrame *

counter_execute(_PyExecutorObject *self, _PyInterpreterFrame *frame, PyObject **stack_pointer)

{

((_PyCounterExecutorObject *)self)->optimizer->count++;

_PyFrame_SetStackPointer(frame, stack_pointer);

frame->instr_ptr = ((_PyCounterExecutorObject *)self)->next_instr;

Py_DECREF(self);

return frame;

}

static int

counter_optimize(

_PyOptimizerObject* self,

PyCodeObject *code,

_Py_CODEUNIT *instr,

_PyExecutorObject **exec_ptr,

int Py_UNUSED(curr_stackentries)

)

{

_PyCounterExecutorObject *executor = (_PyCounterExecutorObject *)_PyObject_New(&CounterExecutor_Type);

if (executor == NULL) {

return -1;

}

executor->executor.execute = counter_execute;

Py_INCREF(self);

executor->optimizer = (_PyCounterOptimizerObject *)self;

executor->next_instr = instr;

*exec_ptr = (_PyExecutorObject *)executor;

_PyBloomFilter empty;

_Py_BloomFilter_Init(&empty);

_Py_ExecutorInit((_PyExecutorObject *)executor, &empty);

return 1;

}

static PyObject *

counter_get_counter(PyObject *self, PyObject *args)

{

return PyLong_FromLongLong(((_PyCounterOptimizerObject *)self)->count);

}

static PyMethodDef counter_optimizer_methods[] = {

{ "get_count", counter_get_counter, METH_NOARGS, NULL },

{ NULL, NULL },

};

static PyTypeObject CounterOptimizer_Type = {

PyVarObject_HEAD_INIT(&PyType_Type, 0)

.tp_name = "Counter optimizer",

.tp_basicsize = sizeof(_PyCounterOptimizerObject),

.tp_itemsize = 0,

.tp_flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_DISALLOW_INSTANTIATION,

.tp_methods = counter_optimizer_methods,

.tp_dealloc = (destructor)PyObject_Del,

};

PyObject *

PyUnstable_Optimizer_NewCounter(void)

{

PyType_Ready(&CounterExecutor_Type);

PyType_Ready(&CounterOptimizer_Type);

_PyCounterOptimizerObject *opt = (_PyCounterOptimizerObject *)_PyObject_New(&CounterOptimizer_Type);

if (opt == NULL) {

return NULL;

}

opt->base.optimize = counter_optimize;

opt->base.resume_threshold = UINT16_MAX;

opt->base.backedge_threshold = 0;

opt->count = 0;

return (PyObject *)opt;

}

///////////////////// Experimental UOp Optimizer /////////////////////

static void

uop_dealloc(_PyUOpExecutorObject *self) {

_Py_ExecutorClear((_PyExecutorObject *)self);

PyObject_Free(self);

}

static const char *

uop_name(int index) {

if (index <= MAX_REAL_OPCODE) {

return _PyOpcode_OpName[index];

}

return _PyOpcode_uop_name[index];

}

static Py_ssize_t

uop_len(_PyUOpExecutorObject *self)

{

return Py_SIZE(self);

}

static PyObject *

uop_item(_PyUOpExecutorObject *self, Py_ssize_t index)

{

Py_ssize_t len = uop_len(self);

if (index < 0 || index >= len) {

PyErr_SetNone(PyExc_IndexError);

return NULL;

}

const char *name = uop_name(self->trace[index].opcode);

if (name == NULL) {

name = "<nil>";

}

PyObject *oname = _PyUnicode_FromASCII(name, strlen(name));

if (oname == NULL) {

return NULL;

}

PyObject *oparg = PyLong_FromUnsignedLong(self->trace[index].oparg);

if (oparg == NULL) {

Py_DECREF(oname);

return NULL;

}

PyObject *operand = PyLong_FromUnsignedLongLong(self->trace[index].operand);

if (operand == NULL) {

Py_DECREF(oparg);

Py_DECREF(oname);

return NULL;

}

PyObject *args[3] = { oname, oparg, operand };

return _PyTuple_FromArraySteal(args, 3);

}

PySequenceMethods uop_as_sequence = {

.sq_length = (lenfunc)uop_len,

.sq_item = (ssizeargfunc)uop_item,

};

static PyTypeObject UOpExecutor_Type = {

PyVarObject_HEAD_INIT(&PyType_Type, 0)

.tp_name = "uop_executor",

.tp_basicsize = sizeof(_PyUOpExecutorObject) - sizeof(_PyUOpInstruction),

.tp_itemsize = sizeof(_PyUOpInstruction),

.tp_flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_DISALLOW_INSTANTIATION,

.tp_dealloc = (destructor)uop_dealloc,

.tp_as_sequence = &uop_as_sequence,

.tp_methods = executor_methods,

};

static int

move_stubs(

_PyUOpInstruction *trace,

int trace_length,

int stubs_start,

int stubs_end

)

{

memmove(trace + trace_length,

trace + stubs_start,

(stubs_end - stubs_start) * sizeof(_PyUOpInstruction));

// Patch up the jump targets

for (int i = 0; i < trace_length; i++) {

if (trace[i].opcode == _POP_JUMP_IF_FALSE ||

trace[i].opcode == _POP_JUMP_IF_TRUE)

{

int target = trace[i].oparg;

if (target >= stubs_start) {

target += trace_length - stubs_start;

trace[i].oparg = target;

}

return trace_length + stubs_end - stubs_start;

}

#define TRACE_STACK_SIZE 5

static int

translate_bytecode_to_trace(

PyCodeObject *code,

_Py_CODEUNIT *instr,

_PyUOpInstruction *trace,

int buffer_size,

_PyBloomFilter *dependencies)

{

PyCodeObject *initial_code = code;

_Py_BloomFilter_Add(dependencies, initial_code);

_Py_CODEUNIT *initial_instr = instr;

int trace_length = 0;

int max_length = buffer_size;

int reserved = 0;

struct {

PyCodeObject *code;

_Py_CODEUNIT *instr;

} trace_stack[TRACE_STACK_SIZE];

int trace_stack_depth = 0;

#ifdef Py_DEBUG

char *uop_debug = Py_GETENV("PYTHONUOPSDEBUG");

int lltrace = 0;

if (uop_debug != NULL && *uop_debug >= '0') {

lltrace = *uop_debug - '0'; // TODO: Parse an int and all that

}

#endif

#ifdef Py_DEBUG

#define DPRINTF(level, ...) \

if (lltrace >= (level)) { printf(__VA_ARGS__); }

#else

#define DPRINTF(level, ...)

#endif

#define ADD_TO_TRACE(OPCODE, OPARG, OPERAND) \

DPRINTF(2, \

" ADD_TO_TRACE(%s, %d, %" PRIu64 ")\n", \

uop_name(OPCODE), \

(OPARG), \

(uint64_t)(OPERAND)); \

assert(trace_length < max_length); \

assert(reserved > 0); \

reserved--; \

trace[trace_length].opcode = (OPCODE); \

trace[trace_length].oparg = (OPARG); \

trace[trace_length].operand = (OPERAND); \

trace_length++;

#define INSTR_IP(INSTR, CODE) \

((uint32_t)((INSTR) - ((_Py_CODEUNIT *)(CODE)->co_code_adaptive)))

#define ADD_TO_STUB(INDEX, OPCODE, OPARG, OPERAND) \

DPRINTF(2, " ADD_TO_STUB(%d, %s, %d, %" PRIu64 ")\n", \

(INDEX), \

uop_name(OPCODE), \

(OPARG), \

(uint64_t)(OPERAND)); \

assert(reserved > 0); \

reserved--; \

trace[(INDEX)].opcode = (OPCODE); \

trace[(INDEX)].oparg = (OPARG); \

trace[(INDEX)].operand = (OPERAND);

// Reserve space for n uops

#define RESERVE_RAW(n, opname) \

if (trace_length + (n) > max_length) { \

DPRINTF(2, "No room for %s (need %d, got %d)\n", \

(opname), (n), max_length - trace_length); \

OPT_STAT_INC(trace_too_long); \

goto done; \

} \

reserved = (n); // Keep ADD_TO_TRACE / ADD_TO_STUB honest

// Reserve space for main+stub uops, plus 2 for _SET_IP and _EXIT_TRACE

#define RESERVE(main, stub) RESERVE_RAW((main) + (stub) + 2, uop_name(opcode))

// Trace stack operations (used by _PUSH_FRAME, _POP_FRAME)

#define TRACE_STACK_PUSH() \

if (trace_stack_depth >= TRACE_STACK_SIZE) { \

DPRINTF(2, "Trace stack overflow\n"); \

OPT_STAT_INC(trace_stack_overflow); \

ADD_TO_TRACE(_SET_IP, 0, 0); \

goto done; \

} \

trace_stack[trace_stack_depth].code = code; \

trace_stack[trace_stack_depth].instr = instr; \

trace_stack_depth++;

#define TRACE_STACK_POP() \

if (trace_stack_depth <= 0) { \

Py_FatalError("Trace stack underflow\n"); \

} \

trace_stack_depth--; \

code = trace_stack[trace_stack_depth].code; \

instr = trace_stack[trace_stack_depth].instr;

DPRINTF(4,

"Optimizing %s (%s:%d) at byte offset %d\n",

PyUnicode_AsUTF8(code->co_qualname),

PyUnicode_AsUTF8(code->co_filename),

code->co_firstlineno,

2 * INSTR_IP(initial_instr, code));

top: // Jump here after _PUSH_FRAME or likely branches

for (;;) {

RESERVE_RAW(2, "epilogue"); // Always need space for _SET_IP and _EXIT_TRACE

ADD_TO_TRACE(_SET_IP, INSTR_IP(instr, code), 0);

uint32_t opcode = instr->op.code;

uint32_t oparg = instr->op.arg;

uint32_t extras = 0;

while (opcode == EXTENDED_ARG) {

instr++;

extras += 1;

opcode = instr->op.code;

oparg = (oparg << 8) | instr->op.arg;

}

if (opcode == ENTER_EXECUTOR) {

_PyExecutorObject *executor =

(_PyExecutorObject *)code->co_executors->executors[oparg&255];

opcode = executor->vm_data.opcode;

DPRINTF(2, " * ENTER_EXECUTOR -> %s\n", _PyOpcode_OpName[opcode]);

oparg = (oparg & 0xffffff00) | executor->vm_data.oparg;

}

switch (opcode) {

case POP_JUMP_IF_NONE:

{

RESERVE(2, 2);

ADD_TO_TRACE(_IS_NONE, 0, 0);

opcode = POP_JUMP_IF_TRUE;

goto pop_jump_if_bool;

}

case POP_JUMP_IF_NOT_NONE:

{

RESERVE(2, 2);

ADD_TO_TRACE(_IS_NONE, 0, 0);

opcode = POP_JUMP_IF_FALSE;

goto pop_jump_if_bool;

}

case POP_JUMP_IF_FALSE:

case POP_JUMP_IF_TRUE:

{

pop_jump_if_bool:

RESERVE(1, 2);

max_length -= 2; // Really the start of the stubs

int counter = instr[1].cache;

int bitcount = _Py_popcount32(counter);

bool jump_likely = bitcount > 8;

bool jump_sense = opcode == POP_JUMP_IF_TRUE;

uint32_t uopcode = jump_sense ^ jump_likely ?

_POP_JUMP_IF_TRUE : _POP_JUMP_IF_FALSE;

_Py_CODEUNIT *next_instr = instr + 1 + _PyOpcode_Caches[_PyOpcode_Deopt[opcode]];

_Py_CODEUNIT *target_instr = next_instr + oparg;

_Py_CODEUNIT *stub_target = jump_likely ? next_instr : target_instr;

DPRINTF(4, "%s(%d): counter=%x, bitcount=%d, likely=%d, sense=%d, uopcode=%s\n",

uop_name(opcode), oparg,

counter, bitcount, jump_likely, jump_sense, uop_name(uopcode));

ADD_TO_TRACE(uopcode, max_length, 0);

ADD_TO_STUB(max_length, _SET_IP, INSTR_IP(stub_target, code), 0);

ADD_TO_STUB(max_length + 1, _EXIT_TRACE, 0, 0);

if (jump_likely) {

DPRINTF(2, "Jump likely (%x = %d bits), continue at byte offset %d\n",

instr[1].cache, bitcount, 2 * INSTR_IP(target_instr, code));

instr = target_instr;

goto top;

}

break;

}

case JUMP_BACKWARD:

{

if (instr + 2 - oparg == initial_instr && code == initial_code) {

RESERVE(1, 0);

ADD_TO_TRACE(_JUMP_TO_TOP, 0, 0);

}

else {

OPT_STAT_INC(inner_loop);

DPRINTF(2, "JUMP_BACKWARD not to top ends trace\n");

}

goto done;

}

case JUMP_FORWARD:

{

RESERVE(0, 0);

// This will emit two _SET_IP instructions; leave it to the optimizer

instr += oparg;

break;

}

case FOR_ITER_LIST:

case FOR_ITER_TUPLE:

case FOR_ITER_RANGE:

{

RESERVE(4, 3);

int check_op, exhausted_op, next_op;

switch (opcode) {

case FOR_ITER_LIST:

check_op = _ITER_CHECK_LIST;

exhausted_op = _IS_ITER_EXHAUSTED_LIST;

next_op = _ITER_NEXT_LIST;

break;

case FOR_ITER_TUPLE:

check_op = _ITER_CHECK_TUPLE;

exhausted_op = _IS_ITER_EXHAUSTED_TUPLE;

next_op = _ITER_NEXT_TUPLE;

break;

case FOR_ITER_RANGE:

check_op = _ITER_CHECK_RANGE;

exhausted_op = _IS_ITER_EXHAUSTED_RANGE;

next_op = _ITER_NEXT_RANGE;

break;

default:

Py_UNREACHABLE();

}

// Assume jump unlikely (can a for-loop exit be likely?)

_Py_CODEUNIT *target_instr = // +1 at the end skips over END_FOR

instr + 1 + _PyOpcode_Caches[_PyOpcode_Deopt[opcode]] + oparg + 1;

max_length -= 3; // Really the start of the stubs

ADD_TO_TRACE(check_op, 0, 0);

ADD_TO_TRACE(exhausted_op, 0, 0);

ADD_TO_TRACE(_POP_JUMP_IF_TRUE, max_length, 0);

ADD_TO_TRACE(next_op, 0, 0);

ADD_TO_STUB(max_length + 0, POP_TOP, 0, 0);

ADD_TO_STUB(max_length + 1, _SET_IP, INSTR_IP(target_instr, code), 0);

ADD_TO_STUB(max_length + 2, _EXIT_TRACE, 0, 0);

break;

}

default:

{

const struct opcode_macro_expansion *expansion = &_PyOpcode_macro_expansion[opcode];

if (expansion->nuops > 0) {

// Reserve space for nuops (+ _SET_IP + _EXIT_TRACE)

int nuops = expansion->nuops;

RESERVE(nuops, 0);

if (expansion->uops[nuops-1].uop == _POP_FRAME) {

// Check for trace stack underflow now:

// We can't bail e.g. in the middle of

// LOAD_CONST + _POP_FRAME.

if (trace_stack_depth == 0) {

DPRINTF(2, "Trace stack underflow\n");

OPT_STAT_INC(trace_stack_underflow);

goto done;

}

uint32_t orig_oparg = oparg; // For OPARG_TOP/BOTTOM

for (int i = 0; i < nuops; i++) {

oparg = orig_oparg;

uint32_t uop = expansion->uops[i].uop;

uint64_t operand = 0;

// Add one to account for the actual opcode/oparg pair:

int offset = expansion->uops[i].offset + 1;

switch (expansion->uops[i].size) {

case OPARG_FULL:

if (extras && OPCODE_HAS_JUMP(opcode)) {

if (opcode == JUMP_BACKWARD_NO_INTERRUPT) {

oparg -= extras;

}

else {

assert(opcode != JUMP_BACKWARD);

oparg += extras;

}

break;

case OPARG_CACHE_1:

operand = read_u16(&instr[offset].cache);

break;

case OPARG_CACHE_2:

operand = read_u32(&instr[offset].cache);

break;

case OPARG_CACHE_4:

operand = read_u64(&instr[offset].cache);

break;

case OPARG_TOP: // First half of super-instr

oparg = orig_oparg >> 4;

break;

case OPARG_BOTTOM: // Second half of super-instr

oparg = orig_oparg & 0xF;

break;

case OPARG_SAVE_RETURN_OFFSET: // op=_SAVE_RETURN_OFFSET; oparg=return_offset

oparg = offset;

assert(uop == _SAVE_RETURN_OFFSET);

break;

default:

fprintf(stderr,

"opcode=%d, oparg=%d; nuops=%d, i=%d; size=%d, offset=%d\n",

opcode, oparg, nuops, i,

expansion->uops[i].size,

expansion->uops[i].offset);

Py_FatalError("garbled expansion");

}

ADD_TO_TRACE(uop, oparg, operand);

if (uop == _POP_FRAME) {

TRACE_STACK_POP();

DPRINTF(2,

"Returning to %s (%s:%d) at byte offset %d\n",

PyUnicode_AsUTF8(code->co_qualname),

PyUnicode_AsUTF8(code->co_filename),

code->co_firstlineno,

2 * INSTR_IP(instr, code));

goto top;

}

if (uop == _PUSH_FRAME) {

assert(i + 1 == nuops);

int func_version_offset =

offsetof(_PyCallCache, func_version)/sizeof(_Py_CODEUNIT)

// Add one to account for the actual opcode/oparg pair:

+ 1;

uint32_t func_version = read_u32(&instr[func_version_offset].cache);

PyFunctionObject *func = _PyFunction_LookupByVersion(func_version);

DPRINTF(3, "Function object: %p\n", func);

if (func != NULL) {

PyCodeObject *new_code = (PyCodeObject *)PyFunction_GET_CODE(func);

if (new_code == code) {

// Recursive call, bail (we could be here forever).

DPRINTF(2, "Bailing on recursive call to %s (%s:%d)\n",

PyUnicode_AsUTF8(new_code->co_qualname),

PyUnicode_AsUTF8(new_code->co_filename),

new_code->co_firstlineno);

OPT_STAT_INC(recursive_call);

ADD_TO_TRACE(_SET_IP, 0, 0);

goto done;

}

if (new_code->co_version != func_version) {

// func.__code__ was updated.

// Perhaps it may happen again, so don't bother tracing.

// TODO: Reason about this -- is it better to bail or not?

DPRINTF(2, "Bailing because co_version != func_version\n");

ADD_TO_TRACE(_SET_IP, 0, 0);

goto done;

}

// Increment IP to the return address

instr += _PyOpcode_Caches[_PyOpcode_Deopt[opcode]] + 1;

TRACE_STACK_PUSH();

_Py_BloomFilter_Add(dependencies, new_code);

code = new_code;

instr = _PyCode_CODE(code);

DPRINTF(2,

"Continuing in %s (%s:%d) at byte offset %d\n",

PyUnicode_AsUTF8(code->co_qualname),

PyUnicode_AsUTF8(code->co_filename),

code->co_firstlineno,

2 * INSTR_IP(instr, code));

goto top;

}

ADD_TO_TRACE(_SET_IP, 0, 0);

goto done;

}

break;

}

DPRINTF(2, "Unsupported opcode %s\n", uop_name(opcode));

OPT_UNSUPPORTED_OPCODE(opcode);

goto done; // Break out of loop

} // End default

} // End switch (opcode)

instr++;

// Add cache size for opcode

instr += _PyOpcode_Caches[_PyOpcode_Deopt[opcode]];

} // End for (;;)

done:

while (trace_stack_depth > 0) {

TRACE_STACK_POP();

}

assert(code == initial_code);

// Skip short traces like _SET_IP, LOAD_FAST, _SET_IP, _EXIT_TRACE

if (trace_length > 3) {

ADD_TO_TRACE(_EXIT_TRACE, 0, 0);

DPRINTF(1,

"Created a trace for %s (%s:%d) at byte offset %d -- length %d+%d\n",

PyUnicode_AsUTF8(code->co_qualname),

PyUnicode_AsUTF8(code->co_filename),

code->co_firstlineno,

2 * INSTR_IP(initial_instr, code),

trace_length,

buffer_size - max_length);

if (max_length < buffer_size) {

// There are stubs

if (trace_length < max_length) {

// There's a gap before the stubs

// Move the stubs back to be immediately after the main trace

// (which ends at trace_length)

DPRINTF(2,

"Moving %d stub uops back by %d\n",

buffer_size - max_length,

max_length - trace_length);

trace_length = move_stubs(trace, trace_length, max_length, buffer_size);

}

else {

assert(trace_length == max_length);

// There's no gap

trace_length = buffer_size;

}

return trace_length;

}

else {

OPT_STAT_INC(trace_too_short);

DPRINTF(4,

"No trace for %s (%s:%d) at byte offset %d\n",

PyUnicode_AsUTF8(code->co_qualname),

PyUnicode_AsUTF8(code->co_filename),

code->co_firstlineno,

2 * INSTR_IP(initial_instr, code));

}

return 0;

#undef RESERVE

#undef RESERVE_RAW

#undef INSTR_IP

#undef ADD_TO_TRACE

#undef DPRINTF

}

static int

remove_unneeded_uops(_PyUOpInstruction *trace, int trace_length)

{

// Stage 1: Replace unneeded _SET_IP uops with NOP.

// Note that we don't enter stubs, those SET_IPs are needed.

int last_set_ip = -1;

int last_instr = 0;

bool need_ip = true;

for (int pc = 0; pc < trace_length; pc++) {

int opcode = trace[pc].opcode;

if (opcode == _SET_IP) {

if (!need_ip && last_set_ip >= 0) {

trace[last_set_ip].opcode = NOP;

}

need_ip = false;

last_set_ip = pc;

}

else if (opcode == _JUMP_TO_TOP || opcode == _EXIT_TRACE) {

last_instr = pc + 1;

break;

}

else {

// If opcode has ERROR or DEOPT, set need_ip to true

if (_PyOpcode_opcode_metadata[opcode].flags & (HAS_ERROR_FLAG | HAS_DEOPT_FLAG) || opcode == _PUSH_FRAME) {

need_ip = true;

}

// Stage 2: Squash NOP opcodes (pre-existing or set above).

int dest = 0;

for (int pc = 0; pc < last_instr; pc++) {

int opcode = trace[pc].opcode;

if (opcode != NOP) {

if (pc != dest) {

trace[dest] = trace[pc];

}

dest++;

}

// Stage 3: Move the stubs back.

if (dest < last_instr) {

int new_trace_length = move_stubs(trace, dest, last_instr, trace_length);

#ifdef Py_DEBUG

char *uop_debug = Py_GETENV("PYTHONUOPSDEBUG");

int lltrace = 0;

if (uop_debug != NULL && *uop_debug >= '0') {

lltrace = *uop_debug - '0'; // TODO: Parse an int and all that

}

if (lltrace >= 2) {

printf("Optimized trace (length %d+%d = %d, saved %d):\n",

dest, trace_length - last_instr, new_trace_length,

trace_length - new_trace_length);

for (int pc = 0; pc < new_trace_length; pc++) {

printf("%4d: (%s, %d, %" PRIu64 ")\n",

pc,

uop_name(trace[pc].opcode),

(trace[pc].oparg),

(uint64_t)(trace[pc].operand));

}

#endif

trace_length = new_trace_length;

}

return trace_length;

}

static int

uop_optimize(

_PyOptimizerObject *self,

PyCodeObject *code,

_Py_CODEUNIT *instr,

_PyExecutorObject **exec_ptr,

int curr_stackentries)

{

_PyBloomFilter dependencies;

_Py_BloomFilter_Init(&dependencies);

_PyUOpInstruction trace[_Py_UOP_MAX_TRACE_LENGTH];

int trace_length = translate_bytecode_to_trace(code, instr, trace, _Py_UOP_MAX_TRACE_LENGTH, &dependencies);

if (trace_length <= 0) {

// Error or nothing translated

return trace_length;

}

OPT_HIST(trace_length, trace_length_hist);

OPT_STAT_INC(traces_created);

char *uop_optimize = Py_GETENV("PYTHONUOPSOPTIMIZE");

if (uop_optimize != NULL && *uop_optimize > '0') {

trace_length = _Py_uop_analyze_and_optimize(code, trace, trace_length, curr_stackentries);

}

trace_length = remove_unneeded_uops(trace, trace_length);

_PyUOpExecutorObject *executor = PyObject_NewVar(_PyUOpExecutorObject, &UOpExecutor_Type, trace_length);

if (executor == NULL) {

return -1;

}

OPT_HIST(trace_length, optimized_trace_length_hist);

executor->base.execute = _PyUopExecute;

memcpy(executor->trace, trace, trace_length * sizeof(_PyUOpInstruction));

_Py_ExecutorInit((_PyExecutorObject *)executor, &dependencies);

*exec_ptr = (_PyExecutorObject *)executor;

return 1;

}

static void

uop_opt_dealloc(PyObject *self) {

PyObject_Free(self);

}

static PyTypeObject UOpOptimizer_Type = {

PyVarObject_HEAD_INIT(&PyType_Type, 0)

.tp_name = "uop_optimizer",

.tp_basicsize = sizeof(_PyOptimizerObject),

.tp_itemsize = 0,

.tp_flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_DISALLOW_INSTANTIATION,

.tp_dealloc = uop_opt_dealloc,

};

PyObject *

PyUnstable_Optimizer_NewUOpOptimizer(void)

{

PyType_Ready(&UOpExecutor_Type);

PyType_Ready(&UOpOptimizer_Type);

_PyOptimizerObject *opt = PyObject_New(_PyOptimizerObject, &UOpOptimizer_Type);

if (opt == NULL) {

return NULL;

}

opt->optimize = uop_optimize;

opt->resume_threshold = UINT16_MAX;

// Need at least 3 iterations to settle specializations.

// A few lower bits of the counter are reserved for other flags.

opt->backedge_threshold = 16 << OPTIMIZER_BITS_IN_COUNTER;

return (PyObject *)opt;

}

/*****************************************

* Executor management

****************************************/

/* We use a bloomfilter with k = 6, m = 256

* The choice of k and the following constants

* could do with a more rigourous analysis,

* but here is a simple analysis:

* We want to keep the false positive rate low.

* For n = 5 (a trace depends on 5 objects),

* we expect 30 bits set, giving a false positive

* rate of (30/256)**6 == 2.5e-6 which is plenty

* good enough.

* However with n = 10 we expect 60 bits set (worst case),

* giving a false positive of (60/256)**6 == 0.0001

* We choose k = 6, rather than a higher number as

* it means the false positive rate grows slower for high n.

* n = 5, k = 6 => fp = 2.6e-6

* n = 5, k = 8 => fp = 3.5e-7

* n = 10, k = 6 => fp = 1.6e-4

* n = 10, k = 8 => fp = 0.9e-4

View remainder of file in raw view

cpython/Python/optimizer.c at main · https-github-com-nzysoft/cpython · GitHub

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