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gh-134584: Cleanups for refcount elimination #136104 and #135860 #142604

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gh-134584: Cleanups for refcount elimination #136104 and #135860 #142604

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10f0bfa
Cleanups for refcount elimnation #136104 and #135860
Fidget-Spinner Dec 11, 2025
93022b2
fix type annotations
Fidget-Spinner Dec 11, 2025
ec5a67c
address review
Fidget-Spinner Dec 12, 2025
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3 changes: 2 additions & 1 deletion Python/bytecodes.c
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Original file line number Diff line number Diff line change
Expand Up @@ -4074,9 +4074,10 @@ dummy_func(
assert(oparg == 1);
STAT_INC(CALL, hit);
PyObject *res_o = PySequence_Tuple(arg_o);
DEAD(null);
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@markshannon markshannon Dec 12, 2025

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Suggested change
DEAD(null);

No need to declare null dead here as it will be handled by INPUTS_DEAD below.

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@Fidget-Spinner Fidget-Spinner Dec 12, 2025

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This is required so that ERROR_IF doesn't emit a useless close for it.

ERROR_IF(res_o == NULL);
a = arg;
INPUTS_DEAD();
ERROR_IF(res_o == NULL);
res = PyStackRef_FromPyObjectSteal(res_o);
}

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16 changes: 14 additions & 2 deletions Python/executor_cases.c.h
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12 changes: 11 additions & 1 deletion Python/generated_cases.c.h
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2 changes: 1 addition & 1 deletion Tools/cases_generator/generators_common.py
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Original file line number Diff line number Diff line change
Expand Up @@ -255,7 +255,7 @@ def error_if(
emit_to(self.out, tkn_iter, "RPAREN")
self.out.emit(") {\n")
next(tkn_iter) # Semi colon
storage.clear_inputs("at ERROR_IF")
storage.clear_inputs_and_close_live_ones(self.out)

c_offset = storage.stack.sp_offset()
try:
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87 changes: 49 additions & 38 deletions Tools/cases_generator/stack.py
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Original file line number Diff line number Diff line change
Expand Up @@ -445,6 +445,7 @@ class Storage:
peeks: int
check_liveness: bool
spilled: int = 0
tmp_defined: bool = False

@staticmethod
def needs_defining(var: Local) -> bool:
Expand Down Expand Up @@ -474,6 +475,16 @@ def clear_inputs(self, reason:str) -> None:
)
self.stack.drop(tos.item, self.check_liveness)

def clear_inputs_and_close_live_ones(self, out: CWriter) -> None:
while len(self.inputs) > self.peeks:
tos = self.inputs.pop()
if self.is_live(tos):
self.close_variable(out, tos, "PyStackRef_NULL")
tos.kill()
out.start_line()
self.stack.drop(tos.item, self.check_liveness)


def clear_dead_inputs(self) -> None:
live = ""
while len(self.inputs) > self.peeks:
Expand Down Expand Up @@ -655,43 +666,43 @@ def _print(self, out: CWriter) -> None:
if PRINT_STACKS:
out.emit(self.as_comment() + "\n")

def close_named(self, out: CWriter, close: str, name: str, overwrite: str) -> None:
if overwrite:
if not self.tmp_defined:
out.emit("_PyStackRef ")
self.tmp_defined = True
out.emit(f"tmp = {name};\n")
out.emit(f"{name} = {overwrite};\n")
self.stack.save_variables(out)
out.emit(f"{close}(tmp);\n")
else:
out.emit(f"{close}({name});\n")

def close_variable(self, out: CWriter, var: Local, overwrite: str) -> None:
close = "PyStackRef_CLOSE"
if "null" in var.name:
close = "PyStackRef_XCLOSE"
var.memory_offset = None
self.save(out)
out.start_line()
if var.size:
if var.size == "1":
self.close_named(out, close, f"{var.name}[0]", overwrite)
else:
if overwrite and not self.tmp_defined:
out.emit("_PyStackRef tmp;\n")
self.tmp_defined = True
out.emit(f"for (int _i = {var.size}; --_i >= 0;) {{\n")
self.close_named(out, close, f"{var.name}[_i]", overwrite)
out.emit("}\n")
else:
self.close_named(out, close, var.name, overwrite)
self.reload(out)


def close_inputs(self, out: CWriter) -> None:

tmp_defined = False
def close_named(close: str, name: str, overwrite: str) -> None:
nonlocal tmp_defined
if overwrite:
if not tmp_defined:
out.emit("_PyStackRef ")
tmp_defined = True
out.emit(f"tmp = {name};\n")
out.emit(f"{name} = {overwrite};\n")
self.stack.save_variables(out)
out.emit(f"{close}(tmp);\n")
else:
out.emit(f"{close}({name});\n")

def close_variable(var: Local, overwrite: str) -> None:
nonlocal tmp_defined
close = "PyStackRef_CLOSE"
if "null" in var.name:
close = "PyStackRef_XCLOSE"
var.memory_offset = None
self.save(out)
out.start_line()
if var.size:
if var.size == "1":
close_named(close, f"{var.name}[0]", overwrite)
else:
if overwrite and not tmp_defined:
out.emit("_PyStackRef tmp;\n")
tmp_defined = True
out.emit(f"for (int _i = {var.size}; --_i >= 0;) {{\n")
close_named(close, f"{var.name}[_i]", overwrite)
out.emit("}\n")
else:
close_named(close, var.name, overwrite)
self.reload(out)

self.clear_dead_inputs()
if not self.inputs:
Expand All @@ -713,20 +724,20 @@ def close_variable(var: Local, overwrite: str) -> None:
self.stack.drop(self.inputs[0].item, False)
self.stack.push(output)
self.stack.flush(out)
close_variable(self.inputs[0], "")
self.close_variable(out, self.inputs[0], "")
self.stack.drop(output.item, self.check_liveness)
self.inputs = []
return
if var_size(lowest.item) != var_size(output.item):
raise StackError("Cannot call DECREF_INPUTS with live output not matching first input size")
self.stack.flush(out)
lowest.in_local = True
close_variable(lowest, output.name)
self.close_variable(out, lowest, output.name)
assert lowest.memory_offset is not None
for input in reversed(self.inputs[1:]):
close_variable(input, "PyStackRef_NULL")
self.close_variable(out, input, "PyStackRef_NULL")
if output is None:
close_variable(self.inputs[0], "PyStackRef_NULL")
self.close_variable(out, self.inputs[0], "PyStackRef_NULL")
for input in reversed(self.inputs[1:]):
input.kill()
self.stack.drop(input.item, self.check_liveness)
Expand Down
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