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Preserve loop LINE events with INSTRUCTION monitoring #9231

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Merged
youknowone merged 1 commit into from
Oct 20, 2026
Merged

Preserve loop LINE events with INSTRUCTION monitoring #9231

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32 changes: 15 additions & 17 deletions crates/vm/src/stdlib/sys/monitoring.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -446,6 +446,14 @@ pub(crate) fn instrument_code(code: &Py<PyCode>, events: u32) {
// Mirrors CPython's initialize_lines: first determine which positions
// are line starts, then mark branch/jump targets, then place opcodes.
if events & MonitoringEvent::Line.mask() != 0 {
let base_opcode = |i| {
let mut op = code.code.instructions.read_op(i);
if matches!(op, Instruction::InstrumentedInstruction) {
op = Instruction::try_from(data.per_instruction_opcodes[i])
.expect("INSTRUMENTED_INSTRUCTION without original opcode");
}
op.to_base().unwrap_or(op)
};
// is_line_start[i] = true if position i should have INSTRUMENTED_LINE
let mut is_line_start = vec![false; len];
let line_locations = rustpython_compiler_core::marshal::linetable_to_locations(
Expand All @@ -459,16 +467,8 @@ pub(crate) fn instrument_code(code: &Py<PyCode>, events: u32) {

// First pass: mark positions where the source line changes
let mut prev_line: Option<u32> = None;
for (i, unit) in code
.code
.instructions
.iter()
.enumerate()
.take(len)
.skip(first_traceable)
{
let op = unit.op;
let base = op.to_base().unwrap_or(op);
for (i, is_start) in is_line_start.iter_mut().enumerate().skip(first_traceable) {
let base = base_opcode(i);
if matches!(base, Instruction::ExtendedArg) {
continue;
}
Expand All @@ -493,7 +493,7 @@ pub(crate) fn instrument_code(code: &Py<PyCode>, events: u32) {
let is_new = prev_line != Some(line);
prev_line = Some(line);
if is_new && line > 0 {
is_line_start[i] = true;
*is_start = true;
}
}
}
Expand All @@ -505,8 +505,8 @@ pub(crate) fn instrument_code(code: &Py<PyCode>, events: u32) {
let mut arg_state = bytecode::OpArgState::default();
let mut instr_idx = first_traceable;
for unit in code.code.instructions[first_traceable..len].iter().copied() {
let (op, arg) = arg_state.get(unit);
let base = op.to_base().unwrap_or(op);
let (_, arg) = arg_state.get(unit);
let base = base_opcode(instr_idx);

if matches!(base, Instruction::ExtendedArg) || matches!(base, Instruction::Cache) {
instr_idx += 1;
Expand Down Expand Up @@ -540,8 +540,7 @@ pub(crate) fn instrument_code(code: &Py<PyCode>, events: u32) {
&& !is_line_start[target_idx]
&& !no_loc_mask.get(target_idx).copied().unwrap_or(false)
{
let target_op = code.code.instructions[target_idx].op;
let target_base = target_op.to_base().unwrap_or(target_op);
let target_base = base_opcode(target_idx);
// Skip synthetic cleanup targets.
if matches!(target_base, Instruction::PopIter) {
instr_idx += 1;
Expand All @@ -563,8 +562,7 @@ pub(crate) fn instrument_code(code: &Py<PyCode>, events: u32) {
&& !is_line_start[target_idx]
&& !no_loc_mask.get(target_idx).copied().unwrap_or(false)
{
let target_op = code.code.instructions.read_op(target_idx);
let target_base = target_op.to_base().unwrap_or(target_op);
let target_base = base_opcode(target_idx);
if !matches!(target_base, Instruction::PopIter)
&& let Some((loc, _)) = line_locations.get(target_idx)
&& loc.line.get() > 0
Expand Down
31 changes: 31 additions & 0 deletions extra_tests/snippets/stdlib_sys.py
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Original file line number Diff line number Diff line change
Expand Up @@ -194,6 +194,37 @@ def jump_out_of_large_loop(code, line):
monitoring.register_callback(2, event, None)
monitoring.free_tool_id(2)


# Combined instruction events must preserve loop-header line events.
def monitored_loop():
total = 0
for value in (1, 2):
total += value
return total


lines = []
monitoring.use_tool_id(2, "combined-lines")
try:
monitoring.register_callback(
2,
monitoring.events.LINE,
lambda code, line: lines.append(line - code.co_firstlineno),
)
monitoring.register_callback(2, monitoring.events.INSTRUCTION, lambda *args: None)
monitoring.set_local_events(
2,
monitored_loop.__code__,
monitoring.events.LINE | monitoring.events.INSTRUCTION,
)
assert monitored_loop() == 3
assert lines == [1, 2, 3, 2, 3, 2, 4]
Comment thread
1ndahous3 marked this conversation as resolved.
finally:
monitoring.set_local_events(2, monitored_loop.__code__, 0)
for event in (monitoring.events.LINE, monitoring.events.INSTRUCTION):
monitoring.register_callback(2, event, None)
monitoring.free_tool_id(2)

assert sys.exc_info() == (None, None, None)

try:
Expand Down
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