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GH-118095: Unify the behavior of tier 2 FOR_ITER branch micro-ops (GH-118420)

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* Target _FOR_ITER_TIER_TWO at POP_TOP following the matching END_FOR

* Modify _GUARD_NOT_EXHAUSTED_RANGE, _GUARD_NOT_EXHAUSTED_LIST and _GUARD_NOT_EXHAUSTED_TUPLE so that they also target the POP_TOP following the matching END_FOR
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Mark Shannon 2024-05-02 16:17:59 +01:00 • committed by GitHub
parent 9789440de3
commit 72867c962c
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5 changed files with 56 additions and 21 deletions
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50
Python/optimizer.c
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@ -23,6 +23,19 @@
#define MAX_EXECUTORS_SIZE 256
#ifdef Py_DEBUG
static int
base_opcode(PyCodeObject *code, int offset)
{
int opcode = _Py_GetBaseOpcode(code, offset);
if (opcode == ENTER_EXECUTOR) {
int oparg = _PyCode_CODE(code)[offset].op.arg;
_PyExecutorObject *ex = code->co_executors->executors[oparg];
return ex->vm_data.opcode;
}
return opcode;
}
#endif
static bool
has_space_for_executor(PyCodeObject *code, _Py_CODEUNIT *instr)
@ -445,6 +458,14 @@ _PyUOp_Replacements[MAX_UOP_ID + 1] = {
[_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,
@ -594,7 +615,6 @@ top: // Jump here after _PUSH_FRAME or likely branches
uint32_t opcode = instr->op.code;
uint32_t oparg = instr->op.arg;
uint32_t extended = 0;
DPRINTF(2, "%d: %s(%d)\n", target, _PyOpcode_OpName[opcode], oparg);
@ -608,7 +628,6 @@ top: // Jump here after _PUSH_FRAME or likely branches
if (opcode == EXTENDED_ARG) {
instr++;
extended = 1;
opcode = instr->op.code;
oparg = (oparg << 8) | instr->op.arg;
if (opcode == EXTENDED_ARG) {
@ -772,12 +791,15 @@ top: // Jump here after _PUSH_FRAME or likely branches
case OPARG_REPLACED:
uop = _PyUOp_Replacements[uop];
assert(uop != 0);
if (uop == _FOR_ITER_TIER_TWO) {
target += 1 + INLINE_CACHE_ENTRIES_FOR_ITER + oparg + 2 + extended;
assert(_PyCode_CODE(code)[target-2].op.code == END_FOR ||
_PyCode_CODE(code)[target-2].op.code == INSTRUMENTED_END_FOR);
assert(_PyCode_CODE(code)[target-1].op.code == POP_TOP);
#ifdef Py_DEBUG
{
uint32_t next_inst = target + 1 + INLINE_CACHE_ENTRIES_FOR_ITER + (oparg > 255);
uint32_t jump_target = next_inst + oparg;
assert(base_opcode(code, jump_target) == END_FOR ||
base_opcode(code, jump_target) == INSTRUMENTED_END_FOR);
assert(base_opcode(code, jump_target+1) == POP_TOP);
}
#endif
break;
default:
fprintf(stderr,
@ -1000,10 +1022,18 @@ prepare_for_execution(_PyUOpInstruction *buffer, int length)
if (_PyUop_Flags[opcode] & (HAS_EXIT_FLAG | HAS_DEOPT_FLAG)) {
uint16_t exit_op = (_PyUop_Flags[opcode] & HAS_EXIT_FLAG) ?
_SIDE_EXIT : _DEOPT;
if (target != current_jump_target || current_exit_op != exit_op) {
make_exit(&buffer[next_spare], exit_op, target);
int32_t jump_target = target;
if (is_for_iter_test[opcode]) {
/* Target the POP_TOP immediately after the END_FOR,
* leaving only the iterator on the stack. */
int extended_arg = inst->oparg > 255;
int32_t next_inst = target + 1 + INLINE_CACHE_ENTRIES_FOR_ITER + extended_arg;
jump_target = next_inst + inst->oparg + 1;
}
if (jump_target != current_jump_target || current_exit_op != exit_op) {
make_exit(&buffer[next_spare], exit_op, jump_target);
current_exit_op = exit_op;
current_jump_target = target;
current_jump_target = jump_target;
current_jump = next_spare;
next_spare++;
}