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Handle full-width operands in the None-return scanner #9347

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Merged
youknowone merged 1 commit into from
Oct 25, 2026
Merged

Handle full-width operands in the None-return scanner #9347

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47 changes: 23 additions & 24 deletions crates/vm/src/vm/crossinterp.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -14,12 +14,15 @@ use crate::{
PyMemoryView, PyStr, PyStrInterned, PyTuple,
},
bytecode::{
BorrowedConstant, CodeFlags, Constant, Instruction,
CodeFlags, Instruction,
oparg::{CommonConstant, OpArg, OpArgState},
},
protocol::PyBuffer,
};
use core::sync::atomic::{AtomicBool, Ordering};
use core::{
borrow::Borrow,
sync::atomic::{AtomicBool, Ordering},
};
use num_traits::ToPrimitive;
use rustpython_common::wtf8::Wtf8Buf;

Expand Down Expand Up @@ -828,31 +831,27 @@ pub(crate) fn code_returns_only_none(code: &Py<PyCode>) -> bool {
if !is_pure_function(code) {
return false;
}
let units = &code.instructions;
// Look up None in co_consts.
let none_index = code
.constants
.iter()
.position(|c| matches!(c.borrow_constant(), BorrowedConstant::None));
// We don't worry about EXTENDED_ARG for now.
for (at, op, _) in walk_instructions(code) {
if !matches!(op, Instruction::ReturnValue) {
continue;
}
debug_assert_ne!(at, 0);
let prev_op = units.read_op(at - 1).deoptimize();
let prev_arg = u32::from(u8::from(units.read_arg(at - 1)));
if matches!(prev_op, Instruction::LoadCommonConstant { .. })
&& prev_arg == u32::from(CommonConstant::None)
{
let mut previous_loads_none = false;
for (_, instruction, arg) in walk_instructions(code) {
if matches!(instruction, Instruction::ExtendedArg) {
continue;
}
if matches!(prev_op, Instruction::LoadConst { .. })
&& none_index.is_some_and(|none_index| prev_arg as usize == none_index)
{
continue;
if matches!(instruction, Instruction::ReturnValue) && !previous_loads_none {
return false;
}
return false;
previous_loads_none = match instruction {
Instruction::LoadCommonConstant { idx } => {
matches!(idx.try_get(arg), Ok(CommonConstant::None))
}
Instruction::LoadConst { consti } => code
.constants
.get(consti.get(arg).as_usize())
.is_some_and(|constant| {
let object: &PyObject = constant.borrow();
object.is(&crate::Context::genesis().none)
}),
_ => false,
};
}
true
}
Expand Down
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