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optimizer.c
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#ifdef _Py_TIER2
#include "Python.h"
#include "opcode.h"
#include "pycore_interp.h"
#include "pycore_backoff.h"
#include "pycore_bitutils.h" // _Py_popcount32()
#include "pycore_object.h" // _PyObject_GC_UNTRACK()
#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_uop_ids.h"
#include "pycore_jit.h"
#include <stdbool.h>
#include <stdint.h>
#include <stddef.h>
#define NEED_OPCODE_METADATA
#include "pycore_uop_metadata.h" // Uop tables
#undef NEED_OPCODE_METADATA
#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);
_Py_ExecutorDetach(code->co_executors->executors[index]);
}
else {
assert(code->co_executors->size == index);
assert(code->co_executors->capacity > index);
code->co_executors->size++;
}
executor->vm_data.opcode = instr->op.code;
executor->vm_data.oparg = instr->op.arg;
executor->vm_data.code = code;
executor->vm_data.index = (int)(instr - _PyCode_CODE(code));
code->co_executors->executors[index] = executor;
assert(index < MAX_EXECUTORS_SIZE);
instr->op.code = ENTER_EXECUTOR;
instr->op.arg = index;
}
static int
never_optimize(
_PyOptimizerObject* self,
_PyInterpreterFrame *frame,
_Py_CODEUNIT *instr,
_PyExecutorObject **exec,
int Py_UNUSED(stack_entries),
bool Py_UNUSED(progress_needed))
{
// This may be called if the optimizer is reset
return 0;
}
PyTypeObject _PyDefaultOptimizer_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,
};
static _PyOptimizerObject _PyOptimizer_Default = {
PyObject_HEAD_INIT(&_PyDefaultOptimizer_Type)
.optimize = never_optimize,
};
_PyOptimizerObject *
_Py_GetOptimizer(void)
{
PyInterpreterState *interp = _PyInterpreterState_GET();
if (interp->optimizer == &_PyOptimizer_Default) {
return NULL;
}
Py_INCREF(interp->optimizer);
return interp->optimizer;
}
static _PyExecutorObject *
make_executor_from_uops(_PyUOpInstruction *buffer, int length, const _PyBloomFilter *dependencies);
static const _PyBloomFilter EMPTY_FILTER = { 0 };
_PyOptimizerObject *
_Py_SetOptimizer(PyInterpreterState *interp, _PyOptimizerObject *optimizer)
{
if (optimizer == NULL) {
optimizer = &_PyOptimizer_Default;
}
_PyOptimizerObject *old = interp->optimizer;
if (old == NULL) {
old = &_PyOptimizer_Default;
}
Py_INCREF(optimizer);
interp->optimizer = optimizer;
return old;
}
int
_Py_SetTier2Optimizer(_PyOptimizerObject *optimizer)
{
PyInterpreterState *interp = _PyInterpreterState_GET();
_PyOptimizerObject *old = _Py_SetOptimizer(interp, optimizer);
Py_XDECREF(old);
return old == NULL ? -1 : 0;
}
/* Returns 1 if optimized, 0 if not optimized, and -1 for an error.
* If optimized, *executor_ptr contains a new reference to the executor
*/
int
_PyOptimizer_Optimize(
_PyInterpreterFrame *frame, _Py_CODEUNIT *start,
_PyStackRef *stack_pointer, _PyExecutorObject **executor_ptr, int chain_depth)
{
// The first executor in a chain and the MAX_CHAIN_DEPTH'th executor *must*
// make progress in order to avoid infinite loops or excessively-long
// side-exit chains. We can only insert the executor into the bytecode if
// this is true, since a deopt won't infinitely re-enter the executor:
chain_depth %= MAX_CHAIN_DEPTH;
bool progress_needed = chain_depth == 0;
PyCodeObject *code = _PyFrame_GetCode(frame);
assert(PyCode_Check(code));
PyInterpreterState *interp = _PyInterpreterState_GET();
if (progress_needed && !has_space_for_executor(code, start)) {
return 0;
}
_PyOptimizerObject *opt = interp->optimizer;
int err = opt->optimize(opt, frame, start, executor_ptr, (int)(stack_pointer - _PyFrame_Stackbase(frame)), progress_needed);
if (err <= 0) {
return err;
}
assert(*executor_ptr != NULL);
if (progress_needed) {
int index = get_index_for_executor(code, start);
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_ptr);
return 0;
}
insert_executor(code, start, index, *executor_ptr);
}
else {
(*executor_ptr)->vm_data.code = NULL;
}
(*executor_ptr)->vm_data.chain_depth = chain_depth;
assert((*executor_ptr)->vm_data.valid);
return 1;
}
_PyExecutorObject *
_Py_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;
}
static PyObject *
is_valid(PyObject *self, PyObject *Py_UNUSED(ignored))
{
return PyBool_FromLong(((_PyExecutorObject *)self)->vm_data.valid);
}
static PyObject *
get_opcode(PyObject *self, PyObject *Py_UNUSED(ignored))
{
return PyLong_FromUnsignedLong(((_PyExecutorObject *)self)->vm_data.opcode);
}
static PyObject *
get_oparg(PyObject *self, PyObject *Py_UNUSED(ignored))
{
return PyLong_FromUnsignedLong(((_PyExecutorObject *)self)->vm_data.oparg);
}
static PyMethodDef executor_methods[] = {
{ "is_valid", is_valid, METH_NOARGS, NULL },
{ "get_opcode", get_opcode, METH_NOARGS, NULL },
{ "get_oparg", get_oparg, METH_NOARGS, NULL },
{ NULL, NULL },
};
///////////////////// Experimental UOp Optimizer /////////////////////
static int executor_clear(_PyExecutorObject *executor);
static void unlink_executor(_PyExecutorObject *executor);
static void
uop_dealloc(_PyExecutorObject *self) {
_PyObject_GC_UNTRACK(self);
assert(self->vm_data.code == NULL);
unlink_executor(self);
#ifdef _Py_JIT
_PyJIT_Free(self);
#endif
PyObject_GC_Del(self);
}
const char *
_PyUOpName(int index)
{
if (index < 0 || index > MAX_UOP_ID) {
return NULL;
}
return _PyOpcode_uop_name[index];
}
#ifdef Py_DEBUG
void
_PyUOpPrint(const _PyUOpInstruction *uop)
{
const char *name = _PyUOpName(uop->opcode);
if (name == NULL) {
printf("<uop %d>", uop->opcode);
}
else {
printf("%s", name);
}
switch(uop->format) {
case UOP_FORMAT_TARGET:
printf(" (%d, target=%d, operand=%#" PRIx64,
uop->oparg,
uop->target,
(uint64_t)uop->operand);
break;
case UOP_FORMAT_JUMP:
printf(" (%d, jump_target=%d, operand=%#" PRIx64,
uop->oparg,
uop->jump_target,
(uint64_t)uop->operand);
break;
default:
printf(" (%d, Unknown format)", uop->oparg);
}
if (_PyUop_Flags[uop->opcode] & HAS_ERROR_FLAG) {
printf(", error_target=%d", uop->error_target);
}
printf(")");
}
#endif
static Py_ssize_t
uop_len(_PyExecutorObject *self)
{
return self->code_size;
}
static PyObject *
uop_item(_PyExecutorObject *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 = _PyUOpName(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 *target = PyLong_FromUnsignedLong(self->trace[index].target);
if (oparg == NULL) {
Py_DECREF(oparg);
Py_DECREF(oname);
return NULL;
}
PyObject *operand = PyLong_FromUnsignedLongLong(self->trace[index].operand);
if (operand == NULL) {
Py_DECREF(target);
Py_DECREF(oparg);
Py_DECREF(oname);
return NULL;
}
PyObject *args[4] = { oname, oparg, target, operand };
return _PyTuple_FromArraySteal(args, 4);
}
PySequenceMethods uop_as_sequence = {
.sq_length = (lenfunc)uop_len,
.sq_item = (ssizeargfunc)uop_item,
};
static int
executor_traverse(PyObject *o, visitproc visit, void *arg)
{
_PyExecutorObject *executor = (_PyExecutorObject *)o;
for (uint32_t i = 0; i < executor->exit_count; i++) {
Py_VISIT(executor->exits[i].executor);
}
return 0;
}
static PyObject *
get_jit_code(PyObject *self, PyObject *Py_UNUSED(ignored))
{
#ifndef _Py_JIT
PyErr_SetString(PyExc_RuntimeError, "JIT support not enabled.");
return NULL;
#else
_PyExecutorObject *executor = (_PyExecutorObject *)self;
if (executor->jit_code == NULL || executor->jit_size == 0) {
Py_RETURN_NONE;
}
return PyBytes_FromStringAndSize(executor->jit_code, executor->jit_size);
#endif
}
static PyMethodDef uop_executor_methods[] = {
{ "is_valid", is_valid, METH_NOARGS, NULL },
{ "get_jit_code", get_jit_code, METH_NOARGS, NULL},
{ "get_opcode", get_opcode, METH_NOARGS, NULL },
{ "get_oparg", get_oparg, METH_NOARGS, NULL },
{ NULL, NULL },
};
static int
executor_is_gc(PyObject *o)
{
return !_Py_IsImmortal(o);
}
PyTypeObject _PyUOpExecutor_Type = {
PyVarObject_HEAD_INIT(&PyType_Type, 0)
.tp_name = "uop_executor",
.tp_basicsize = offsetof(_PyExecutorObject, exits),
.tp_itemsize = 1,
.tp_flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_DISALLOW_INSTANTIATION | Py_TPFLAGS_HAVE_GC,
.tp_dealloc = (destructor)uop_dealloc,
.tp_as_sequence = &uop_as_sequence,
.tp_methods = uop_executor_methods,
.tp_traverse = executor_traverse,
.tp_clear = (inquiry)executor_clear,
.tp_is_gc = executor_is_gc,
};
/* TO DO -- Generate these tables */
static const uint16_t
_PyUOp_Replacements[MAX_UOP_ID + 1] = {
[_ITER_JUMP_RANGE] = _GUARD_NOT_EXHAUSTED_RANGE,
[_ITER_JUMP_LIST] = _GUARD_NOT_EXHAUSTED_LIST,
[_ITER_JUMP_TUPLE] = _GUARD_NOT_EXHAUSTED_TUPLE,
[_FOR_ITER] = _FOR_ITER_TIER_TWO,
};
static const uint8_t
is_for_iter_test[MAX_UOP_ID + 1] = {
[_GUARD_NOT_EXHAUSTED_RANGE] = 1,
[_GUARD_NOT_EXHAUSTED_LIST] = 1,
[_GUARD_NOT_EXHAUSTED_TUPLE] = 1,
[_FOR_ITER_TIER_TWO] = 1,
};
static const uint16_t
BRANCH_TO_GUARD[4][2] = {
[POP_JUMP_IF_FALSE - POP_JUMP_IF_FALSE][0] = _GUARD_IS_TRUE_POP,
[POP_JUMP_IF_FALSE - POP_JUMP_IF_FALSE][1] = _GUARD_IS_FALSE_POP,
[POP_JUMP_IF_TRUE - POP_JUMP_IF_FALSE][0] = _GUARD_IS_FALSE_POP,
[POP_JUMP_IF_TRUE - POP_JUMP_IF_FALSE][1] = _GUARD_IS_TRUE_POP,
[POP_JUMP_IF_NONE - POP_JUMP_IF_FALSE][0] = _GUARD_IS_NOT_NONE_POP,
[POP_JUMP_IF_NONE - POP_JUMP_IF_FALSE][1] = _GUARD_IS_NONE_POP,
[POP_JUMP_IF_NOT_NONE - POP_JUMP_IF_FALSE][0] = _GUARD_IS_NONE_POP,
[POP_JUMP_IF_NOT_NONE - POP_JUMP_IF_FALSE][1] = _GUARD_IS_NOT_NONE_POP,
};
#define CONFIDENCE_RANGE 1000
#define CONFIDENCE_CUTOFF 333
#ifdef Py_DEBUG
#define DPRINTF(level, ...) \
if (lltrace >= (level)) { printf(__VA_ARGS__); }
#else
#define DPRINTF(level, ...)
#endif
static inline int
add_to_trace(
_PyUOpInstruction *trace,
int trace_length,
uint16_t opcode,
uint16_t oparg,
uint64_t operand,
uint32_t target)
{
trace[trace_length].opcode = opcode;
trace[trace_length].format = UOP_FORMAT_TARGET;
trace[trace_length].target = target;
trace[trace_length].oparg = oparg;
trace[trace_length].operand = operand;
return trace_length + 1;
}
#ifdef Py_DEBUG
#define ADD_TO_TRACE(OPCODE, OPARG, OPERAND, TARGET) \
assert(trace_length < max_length); \
trace_length = add_to_trace(trace, trace_length, (OPCODE), (OPARG), (OPERAND), (TARGET)); \
if (lltrace >= 2) { \
printf("%4d ADD_TO_TRACE: ", trace_length); \
_PyUOpPrint(&trace[trace_length-1]); \
printf("\n"); \
}
#else
#define ADD_TO_TRACE(OPCODE, OPARG, OPERAND, TARGET) \
assert(trace_length < max_length); \
trace_length = add_to_trace(trace, trace_length, (OPCODE), (OPARG), (OPERAND), (TARGET));
#endif
#define INSTR_IP(INSTR, CODE) \
((uint32_t)((INSTR) - ((_Py_CODEUNIT *)(CODE)->co_code_adaptive)))
// 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; \
}
// Reserve space for N uops, plus 3 for _SET_IP, _CHECK_VALIDITY and _EXIT_TRACE
#define RESERVE(needed) RESERVE_RAW((needed) + 3, _PyUOpName(opcode))
// Trace stack operations (used by _PUSH_FRAME, _RETURN_VALUE)
#define TRACE_STACK_PUSH() \
if (trace_stack_depth >= TRACE_STACK_SIZE) { \
DPRINTF(2, "Trace stack overflow\n"); \
OPT_STAT_INC(trace_stack_overflow); \
return 0; \
} \
assert(func == NULL || func->func_code == (PyObject *)code); \
trace_stack[trace_stack_depth].func = func; \
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--; \
func = trace_stack[trace_stack_depth].func; \
code = trace_stack[trace_stack_depth].code; \
assert(func == NULL || func->func_code == (PyObject *)code); \
instr = trace_stack[trace_stack_depth].instr;
/* Returns the length of the trace on success,
* 0 if it failed to produce a worthwhile trace,
* and -1 on an error.
*/
static int
translate_bytecode_to_trace(
_PyInterpreterFrame *frame,
_Py_CODEUNIT *instr,
_PyUOpInstruction *trace,
int buffer_size,
_PyBloomFilter *dependencies, bool progress_needed)
{
bool first = true;
PyCodeObject *code = _PyFrame_GetCode(frame);
PyFunctionObject *func = _PyFrame_GetFunction(frame);
assert(PyFunction_Check(func));
PyCodeObject *initial_code = code;
_Py_BloomFilter_Add(dependencies, initial_code);
_Py_CODEUNIT *initial_instr = instr;
int trace_length = 0;
// Leave space for possible trailing _EXIT_TRACE
int max_length = buffer_size-2;
struct {
PyFunctionObject *func;
PyCodeObject *code;
_Py_CODEUNIT *instr;
} trace_stack[TRACE_STACK_SIZE];
int trace_stack_depth = 0;
int confidence = CONFIDENCE_RANGE; // Adjusted by branch instructions
bool jump_seen = false;
#ifdef Py_DEBUG
char *python_lltrace = Py_GETENV("PYTHON_LLTRACE");
int lltrace = 0;
if (python_lltrace != NULL && *python_lltrace >= '0') {
lltrace = *python_lltrace - '0'; // TODO: Parse an int and all that
}
#endif
DPRINTF(2,
"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));
ADD_TO_TRACE(_START_EXECUTOR, 0, (uintptr_t)instr, INSTR_IP(instr, code));
uint32_t target = 0;
for (;;) {
target = INSTR_IP(instr, code);
// Need space for _DEOPT
max_length--;
uint32_t opcode = instr->op.code;
uint32_t oparg = instr->op.arg;
if (!first && instr == initial_instr) {
// We have looped around to the start:
RESERVE(1);
ADD_TO_TRACE(_JUMP_TO_TOP, 0, 0, 0);
goto done;
}
DPRINTF(2, "%d: %s(%d)\n", target, _PyOpcode_OpName[opcode], oparg);
if (opcode == EXTENDED_ARG) {
instr++;
opcode = instr->op.code;
oparg = (oparg << 8) | instr->op.arg;
if (opcode == EXTENDED_ARG) {
instr--;
goto done;
}
}
if (opcode == ENTER_EXECUTOR) {
// We have a couple of options here. We *could* peek "underneath"
// this executor and continue tracing, which could give us a longer,
// more optimizeable trace (at the expense of lots of duplicated
// tier two code). Instead, we choose to just end here and stitch to
// the other trace, which allows a side-exit traces to rejoin the
// "main" trace periodically (and also helps protect us against
// pathological behavior where the amount of tier two code explodes
// for a medium-length, branchy code path). This seems to work
// better in practice, but in the future we could be smarter about
// what we do here:
goto done;
}
assert(opcode != ENTER_EXECUTOR && opcode != EXTENDED_ARG);
RESERVE_RAW(2, "_CHECK_VALIDITY_AND_SET_IP");
ADD_TO_TRACE(_CHECK_VALIDITY_AND_SET_IP, 0, (uintptr_t)instr, target);
/* Special case the first instruction,
* so that we can guarantee forward progress */
if (first && progress_needed) {
assert(first);
if (OPCODE_HAS_EXIT(opcode) || OPCODE_HAS_DEOPT(opcode)) {
opcode = _PyOpcode_Deopt[opcode];
}
assert(!OPCODE_HAS_EXIT(opcode));
assert(!OPCODE_HAS_DEOPT(opcode));
}
if (OPCODE_HAS_EXIT(opcode)) {
// Make space for side exit and final _EXIT_TRACE:
RESERVE_RAW(2, "_EXIT_TRACE");
max_length--;
}
if (OPCODE_HAS_ERROR(opcode)) {
// Make space for error stub and final _EXIT_TRACE:
RESERVE_RAW(2, "_ERROR_POP_N");
max_length--;
}
switch (opcode) {
case POP_JUMP_IF_NONE:
case POP_JUMP_IF_NOT_NONE:
case POP_JUMP_IF_FALSE:
case POP_JUMP_IF_TRUE:
{
RESERVE(1);
int counter = instr[1].cache;
int bitcount = _Py_popcount32(counter);
int jump_likely = bitcount > 8;
/* If bitcount is 8 (half the jumps were taken), adjust confidence by 50%.
If it's 16 or 0 (all or none were taken), adjust by 10%
(since the future is still somewhat uncertain).
For values in between, adjust proportionally. */
if (jump_likely) {
confidence = confidence * (bitcount + 2) / 20;
}
else {
confidence = confidence * (18 - bitcount) / 20;
}
uint32_t uopcode = BRANCH_TO_GUARD[opcode - POP_JUMP_IF_FALSE][jump_likely];
DPRINTF(2, "%d: %s(%d): counter=%04x, bitcount=%d, likely=%d, confidence=%d, uopcode=%s\n",
target, _PyOpcode_OpName[opcode], oparg,
counter, bitcount, jump_likely, confidence, _PyUOpName(uopcode));
if (confidence < CONFIDENCE_CUTOFF) {
DPRINTF(2, "Confidence too low (%d < %d)\n", confidence, CONFIDENCE_CUTOFF);
OPT_STAT_INC(low_confidence);
goto done;
}
_Py_CODEUNIT *next_instr = instr + 1 + _PyOpcode_Caches[_PyOpcode_Deopt[opcode]];
_Py_CODEUNIT *target_instr = next_instr + oparg;
if (jump_likely) {
DPRINTF(2, "Jump likely (%04x = %d bits), continue at byte offset %d\n",
instr[1].cache, bitcount, 2 * INSTR_IP(target_instr, code));
instr = target_instr;
ADD_TO_TRACE(uopcode, 0, 0, INSTR_IP(next_instr, code));
goto top;
}
ADD_TO_TRACE(uopcode, 0, 0, INSTR_IP(target_instr, code));
break;
}
case JUMP_BACKWARD:
ADD_TO_TRACE(_CHECK_PERIODIC, 0, 0, target);
_Py_FALLTHROUGH;
case JUMP_BACKWARD_NO_INTERRUPT:
{
instr += 1 + _PyOpcode_Caches[_PyOpcode_Deopt[opcode]] - (int)oparg;
if (jump_seen) {
OPT_STAT_INC(inner_loop);
DPRINTF(2, "JUMP_BACKWARD not to top ends trace\n");
goto done;
}
jump_seen = true;
goto top;
}
case JUMP_FORWARD:
{
RESERVE(0);
// This will emit two _SET_IP instructions; leave it to the optimizer
instr += oparg;
break;
}
case RESUME:
/* Use a special tier 2 version of RESUME_CHECK to allow traces to
* start with RESUME_CHECK */
ADD_TO_TRACE(_TIER2_RESUME_CHECK, 0, 0, target);
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 + 1); /* One extra for exit */
int16_t last_op = expansion->uops[nuops-1].uop;
if (last_op == _RETURN_VALUE || last_op == _RETURN_GENERATOR || last_op == _YIELD_VALUE) {
// Check for trace stack underflow now:
// We can't bail e.g. in the middle of
// LOAD_CONST + _RETURN_VALUE.
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:
assert(opcode != JUMP_BACKWARD_NO_INTERRUPT && opcode != JUMP_BACKWARD);
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;
case OPARG_REPLACED:
uop = _PyUOp_Replacements[uop];
assert(uop != 0);
#ifdef Py_DEBUG
{
uint32_t next_inst = target + 1 + INLINE_CACHE_ENTRIES_FOR_ITER + (oparg > 255);
uint32_t jump_target = next_inst + oparg;
assert(_Py_GetBaseCodeUnit(code, jump_target).op.code == END_FOR);
assert(_Py_GetBaseCodeUnit(code, jump_target+1).op.code == POP_TOP);
}
#endif
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");
}
if (uop == _RETURN_VALUE || uop == _RETURN_GENERATOR || uop == _YIELD_VALUE) {
TRACE_STACK_POP();
/* Set the operand to the function or code object returned to,
* to assist optimization passes. (See _PUSH_FRAME below.)
*/
if (func != NULL) {
operand = (uintptr_t)func;
}
else if (code != NULL) {
operand = (uintptr_t)code | 1;
}
else {
operand = 0;
}
ADD_TO_TRACE(uop, oparg, operand, target);
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);
if (opcode == FOR_ITER_GEN ||
opcode == LOAD_ATTR_PROPERTY ||
opcode == BINARY_SUBSCR_GETITEM ||
opcode == SEND_GEN)
{
DPRINTF(2, "Bailing due to dynamic target\n");
ADD_TO_TRACE(uop, oparg, 0, target);
ADD_TO_TRACE(_DYNAMIC_EXIT, 0, 0, 0);
goto done;
}
assert(_PyOpcode_Deopt[opcode] == CALL || _PyOpcode_Deopt[opcode] == CALL_KW);
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);
PyCodeObject *new_code = NULL;
PyFunctionObject *new_func =
_PyFunction_LookupByVersion(func_version, (PyObject **) &new_code);
DPRINTF(2, "Function: version=%#x; new_func=%p, new_code=%p\n",
(int)func_version, new_func, new_code);
if (new_code != NULL) {
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(uop, oparg, 0, target);
ADD_TO_TRACE(_EXIT_TRACE, 0, 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(uop, oparg, 0, target);
ADD_TO_TRACE(_EXIT_TRACE, 0, 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);
/* Set the operand to the callee's function or code object,
* to assist optimization passes.
* We prefer setting it to the function (for remove_globals())
* but if that's not available but the code is available,
* use the code, setting the low bit so the optimizer knows.
*/
if (new_func != NULL) {
operand = (uintptr_t)new_func;
}
else if (new_code != NULL) {
operand = (uintptr_t)new_code | 1;
}
else {
operand = 0;
}
ADD_TO_TRACE(uop, oparg, operand, target);
code = new_code;
func = new_func;
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;
}
DPRINTF(2, "Bail, new_code == NULL\n");
ADD_TO_TRACE(uop, oparg, 0, target);
ADD_TO_TRACE(_DYNAMIC_EXIT, 0, 0, 0);
goto done;
}
if (uop == _BINARY_OP_INPLACE_ADD_UNICODE) {
assert(i + 1 == nuops);
_Py_CODEUNIT *next_instr = instr + 1 + _PyOpcode_Caches[_PyOpcode_Deopt[opcode]];
assert(next_instr->op.code == STORE_FAST);
operand = next_instr->op.arg;
// Skip the STORE_FAST:
instr++;
}
// All other instructions
ADD_TO_TRACE(uop, oparg, operand, target);
}
break;
}
DPRINTF(2, "Unsupported opcode %s\n", _PyOpcode_OpName[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]];
if (opcode == CALL_LIST_APPEND) {
assert(instr->op.code == POP_TOP);
instr++;
}
top:
// Jump here after _PUSH_FRAME or likely branches.
first = false;
} // End for (;;)
done:
while (trace_stack_depth > 0) {
TRACE_STACK_POP();
}
assert(code == initial_code);
// Skip short traces where we can't even translate a single instruction:
if (first) {
OPT_STAT_INC(trace_too_short);
DPRINTF(2,
"No trace for %s (%s:%d) at byte offset %d (no progress)\n",
PyUnicode_AsUTF8(code->co_qualname),
PyUnicode_AsUTF8(code->co_filename),
code->co_firstlineno,
2 * INSTR_IP(initial_instr, code));
return 0;
}
if (!is_terminator(&trace[trace_length-1])) {
/* Allow space for _EXIT_TRACE */
max_length += 2;
ADD_TO_TRACE(_EXIT_TRACE, 0, 0, target);
}
DPRINTF(1,
"Created a proto-trace for %s (%s:%d) at byte offset %d -- length %d\n",
PyUnicode_AsUTF8(code->co_qualname),
PyUnicode_AsUTF8(code->co_filename),
code->co_firstlineno,
2 * INSTR_IP(initial_instr, code),
trace_length);
OPT_HIST(trace_length, trace_length_hist);
return trace_length;
}
#undef RESERVE
#undef RESERVE_RAW
#undef INSTR_IP
#undef ADD_TO_TRACE
#undef DPRINTF
#define UNSET_BIT(array, bit) (array[(bit)>>5] &= ~(1<<((bit)&31)))
#define SET_BIT(array, bit) (array[(bit)>>5] |= (1<<((bit)&31)))
#define BIT_IS_SET(array, bit) (array[(bit)>>5] & (1<<((bit)&31)))
/* Count the number of unused uops and exits
*/
static int
count_exits(_PyUOpInstruction *buffer, int length)
{
int exit_count = 0;
for (int i = 0; i < length; i++) {
int opcode = buffer[i].opcode;
if (opcode == _EXIT_TRACE || opcode == _DYNAMIC_EXIT) {
exit_count++;
}
}
return exit_count;
}
static void make_exit(_PyUOpInstruction *inst, int opcode, int target)
{
inst->opcode = opcode;
inst->oparg = 0;
inst->operand = 0;
inst->format = UOP_FORMAT_TARGET;
inst->target = target;
}
/* Convert implicit exits, errors and deopts
* into explicit ones. */
static int
prepare_for_execution(_PyUOpInstruction *buffer, int length)
{
int32_t current_jump = -1;
int32_t current_jump_target = -1;
int32_t current_error = -1;
int32_t current_error_target = -1;
int32_t current_popped = -1;
int32_t current_exit_op = -1;
/* Leaving in NOPs slows down the interpreter and messes up the stats */
_PyUOpInstruction *copy_to = &buffer[0];
for (int i = 0; i < length; i++) {
_PyUOpInstruction *inst = &buffer[i];
if (inst->opcode != _NOP) {
if (copy_to != inst) {
*copy_to = *inst;
}
copy_to++;
}
}