wasm: decline inlining a bridge whose source guard is in the preamble; _abc: consume __abc_tpflags__ in _abc_init and export the collection-flag setters - #1416
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WalkthroughChangesWASM inline bridge control flow
Virtual-state mismatch diagnostics
ABC collection flags
Estimated code review effort: 4 (Complex) | ~45 minutes Merge Risk: ⚪ Minimal · up to The PR changes WebAssembly guard handling, JIT diagnostics, and ABC flag initialization, with the supplied verification indicating no regression. The remaining suggestions are localized test and maintainability follow-ups; no actionable merge-blocking risk remains. Sequence Diagram(s)sequenceDiagram
participant TraceBuilder
participant InlineBridge
participant LoopLabelCheck
participant BridgeDiagnostics
TraceBuilder->>InlineBridge: request non-header resume
InlineBridge->>LoopLabelCheck: locate source guard relative to loop label
LoopLabelCheck-->>InlineBridge: return preamble or loop-body result
InlineBridge->>BridgeDiagnostics: record source_in_preamble when declined
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| if unsafe { is_int(w_flags) } { | ||
| let flags = unsafe { w_int_get_value(w_flags) }; |
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When __abc_tpflags__ is an arbitrary-precision integer outside the machine-int representation, is_int is false, so _abc_init silently deletes the attribute and succeeds. CPython 3.14 instead raises OverflowError for inputs such as 1 << 100, making this an observable mismatch for custom ABCs; handle the long-integer representation and propagate the conversion overflow rather than treating it like a non-integer value.
AGENTS.md reference: AGENTS.md:L146-L150
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| // `del cls.__abc_tpflags__`. Outside the int arm: the attribute is | ||
| // consumed by the class that spells it whatever it holds, and a | ||
| // leftover would be inherited by every subclass and re-read here. | ||
| crate::baseobjspace::delattr_str(cls, "__abc_tpflags__")?; |
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When the class's metaclass overrides __delattr__, this normal attribute deletion unexpectedly invokes user code, whereas CPython 3.14 removes __abc_tpflags__ directly from the type dictionary without calling the hook. It is also performed too late: the conflicting-bits return above leaves the attribute present even though CPython consumes it before raising. Pop the namespace entry before validation instead of dispatching through delattr_str.
AGENTS.md reference: AGENTS.md:L146-L150
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| if let Some(found) = simple_weak_set_contains(roots.get(cache_slot), roots.get(item_slot))? { | ||
| return Ok(found); |
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When code replaces _abc.SimpleWeakSet.__contains__, caches created by _abc_init still have this exact type and a set-valued data, so this early return bypasses the patched method and changes isinstance/issubclass results. The previous membership-protocol call, and PyPy's app-level implementation, resolve __contains__ dynamically; only take this fast path after proving the class-level method is still the original implementation.
AGENTS.md reference: AGENTS.md:L146-L150
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| for child in unsafe { typeobject::w_type_get_subclasses(*w_type, false) } { | ||
| set_collection_flag_recursive(child, marker); |
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When an intermediate descendant already has the requested marker but a deeper descendant was changed through the newly exported non-recursive setter, this call reaches set_collection_flag_recursive, whose equality shortcut stops at the intermediate class and leaves the deeper marker unchanged. PyPy's interp_abc.set_collection_flag_recursive unconditionally recurses through every child, so the exported primitive should likewise stamp the entire subtree rather than reuse the registration-specific shortcut.
AGENTS.md reference: AGENTS.md:L182-L185
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Inline comments:
In `@majit/majit-backend-wasm/tests/codegen_test.rs`:
- Around line 3670-3699: Introduce a local test helper, such as
test_module_inputs, that accepts inputargs, ops, and inlined_bridges and
constructs the shared codegen::ModuleBuildInputs defaults. Replace the repeated
literals in the affected tests, including build_owner_with_region_closing_at and
run_non_header_region_repro, with calls to this helper while preserving the
existing varying values.
In `@pyre/pyre-interpreter/src/module/_abc/mod.rs`:
- Around line 108-114: Update the error arm in the weak-cache membership match
around w_set_contains_checked to propagate the original native membership error
instead of returning Ok(None). Preserve the existing Ok(Some(found)) success
behavior and ensure weak_cache_contains does not retry membership after hashing
or equality fails.
- Around line 73-83: Restrict the fast path around the cache type and data
validation to exact built-in set objects, not set subclasses, so customized
data.__contains__ implementations use the fallback. Also detect when
SimpleWeakSet.__contains__ has been replaced on its class and fall back in that
case, while preserving the existing behavior that instance-level replacement
does not affect the in operator.
- Around line 245-277: Update the __abc_tpflags__ handling around
set_collection_flag_of to accept both machine-sized integers and W_LongObject
values, extracting their low machine-word bits before validating
COLLECTION_FLAGS and applying the collection marker. Preserve deletion for every
consumed attribute, and add regression tests covering large positive and
negative arbitrary-size integers.
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🤖 Codex parity reviewStatic analysis of this diff vs the local RPython/PyPy sources (commit 18ba6e7). Files in the reviewed diff1. Regressions to PyPy parity introduced by this patch
2. Other mismatches introduced by this patch
3. Pre-existing mismatches (already present before this patch)None. 4. Structural adaptationsNone. |
Review responsesEach finding checked against Pushed as Fixed
Confirmed. Not taken: coderabbit's remedy, "extract the low machine-word bits from both integer representations". That would make Fixed in the same block, and not raised by either reviewer:
Confirmed on both counts. 3.14 is
Now Native membership error swallowed, then membership re-run — coderabbit Confirmed, and reachable: the probe weakref hashes and compares by its referent, so a metaclass The exported recursive setter could mark
Test-helper extraction — coderabbit Taken for the six sites whose non-varying fields are byte-identical: the three this PR adds plus 1292 / 3011 / 3203. −131/+53 lines. Not taken for the other nine Refuted"Revisit every descendant in the recursive setter" — codex The scenario is real, but the shortcut is the 3.14 spec, not a local optimization. if (PyType_HasFeature(self, Py_TPFLAGS_IMMUTABLETYPE) ||
(self->tp_flags & mask) == flags)
{
return;
}
Declined, documentedHonour a patched
The first half of coderabbit VerificationProbe of 11
One pre-existing divergence surfaced while verifying and is not touched here: pyre marks — commented by Claude |
Correction — two of the responses above are superseded by
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https://github.com/youknowone/pyre/blob/6356d5962b8c9b0d65bf201f25baefb62f1d05f6/pyre-interpreter/src/module/_abc/mod.rs#L263
When free-threaded code mutates cls.__abc_tpflags__ concurrently with _abc_init, this lookup and the later type_dict_delete execute as two separately locked dictionary operations. A writer can replace or remove the entry between them, causing _abc_init to apply stale flags while deleting a newer value; CPython's PyDict_Pop instead returns the exact value removed in one critical section. Use a single locked pop so consumption and validation operate on the same entry.
AGENTS.md reference: AGENTS.md:L142-L144
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`InlineGuard::branch_depth` is a depth at loop-body statement level, where the per-region blocks opened after the loop header's `loop` are the innermost open blocks. `emit_guard_exit` applied it to whichever guard matched the region's `source_fail_index`, including one in the peeled preamble — where the innermost open blocks are the LABEL (past_loader, loader) pairs. Such a guard branched into a resume loader, which reloads label args from frame slots nothing wrote on that path, and the region body was left with no predecessor. Add `codegen::inline_source_guard_precedes_loop_label` and a `source_in_preamble` decline ahead of the merge. BRIDGE_DIAG grows to 53 and the runner's label table names the counter. The arm fires 0 times over the 443-fixture synth corpus with the default settings, where `not_header` already declines every preamble-sourced region. Under `PYRE_WASM_INLINE_NONHEADER=1` it fires on subscr_user_getitem_inline (1) and str_search_index_bounds (2), the two fixtures that previously died with a TypeError; both now run correctly and still inline their loop-body-sourced regions. Tests: the new predicate; a region resuming at a LABEL that carries a backend-only capture; two regions closing at the same non-header LABEL. Assisted-by: Claude
…on a virtual-state mismatch The `[jit][jte] virtualstate mismatch` line computed `runtime_value` with `get_constant_box`, which reads only a constant-folded operand. The `Constant` arm of `generate_guards` decides on `runtime_value_of`, the box's observed value, so a box carrying an observed value printed as having none. Assisted-by: Claude
…flag setters `type_new` folded a class body's `__abc_tpflags__` into the structural-match marker and left the attribute in place. Two consequences: a plain class carrying the name got the marker, so `case [...]` accepted an object that is not a sequence, and the consumed marker stayed visible on `collections.abc.Sequence` / `Mapping`. Move the block to `_abc_init`, where `app_abc.py` has it, so only a class going through `ABCMeta` is affected, and delete the attribute afterwards. `_abcmodule.c _abc__abc_init_impl` masks the value rather than comparing it whole, so `__abc_tpflags__ = (1 << 5) | 1` sets the sequence marker. Add `set_collection_flag_of` for the non-recursive arm and export `_internal_set_collection_flag` / `_internal_set_collection_flag_recursive`, which `moduledef.py` lists as interpleveldefs and this module had neither of. Restate four upstream citations as symbols rather than line numbers. Assisted-by: Claude
…-range values `_abc_init` deleted the attribute with `delattr_str` after validating it, so a metaclass `__delattr__` ran and a rejected value stayed in the class dict. `_abc__abc_init_impl` pops it out of the type dict before the checks. `is_int` admitted `bool` and excluded `W_LongObject`, where `PyLong_CheckExact` excludes `bool` and every `int` subclass, and `PyLong_AsLong` raises `OverflowError` past the machine word. Test both int representations exactly and convert through `int_w`. `_internal_set_collection_flag_recursive` stamped its root argument through `set_collection_flag`, which has no immutable-type stop, so the primitive marked `str`. `set_flags_recursive` starts the guarded walk at the argument itself. Flag validation moves to a shared `collection_marker`. `simple_weak_set_contains` answered `None` when the native set probe raised, and the caller re-ran membership through the protocol, running a metaclass `__hash__` / `__eq__` a second time. Propagate the recovered exception. `stdlib_abc.py` covers the cases above and passes on CPython 3.14.6. Assisted-by: Claude
The six inline-region tests spelled the same eighteen non-varying fields; only the owner trace, its inputargs and the merged regions differ between them. Assisted-by: Claude
Rebased onto
|
| region | resolution | why |
|---|---|---|
subclass_of, the _abc_registry walk comment |
ours | both sides dropped the :154-157; ours also names the enclosing _abc_subclasscheck (app_abc.py:125, the loop at :153), which is what the repo's citation rule asks for |
instancecheck × 3 (subclass = instance.__class__, subtype = type(instance), the any(...) line) |
ours | same; enclosing symbol is _abc_instancecheck (app_abc.py:109) |
simple_weak_set_contains, the set-probe error arm |
main |
take_pending_set_element_error(probe) names a set element, which is what wr in self.data stands for; my take_pending_hash_error() is the weaker recovery |
The stale doc paragraph in which I argued against honouring a patched __contains__ was auto-merged in by the rebase and has been removed — it contradicted the guard main ships.
Verification on the rebased tree
Probe of 11 __abc_tpflags__ shapes plus the metaclass-__delattr__ and immutable-type cases: every behavioural line matches the CPython 3.14.6 oracle. The only textual difference left is the OverflowError wording (int too large to convert to int), which is int_w's message — implementation follows pypy there, behaviour follows CPython. _internal_set_collection_flag_recursive(str, 1 << 6) leaves str unchanged, confirming the root guard.
extra_tests gated subset 86/86 dynasm
extra_tests full corpus 329/337 dynasm; stdlib_abc.py green,
8 failures pre-existing and abc-unrelated
test_abc OK
test_collections OK (skipped=3)
test_typing OK (skipped=2)
test_patma 6 failures, all TestTracing (sys.settrace line events, pre-existing)
cargo test -p majit-backend-wasm 53 + 11 passed, 0 failed
cargo fmt --all --check clean
check-new-line-citations.py clean
— commented by Claude
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https://github.com/youknowone/pyre/blob/18ba6e7690fb0b3552a80b794cd1ac25207a58d7/pyre-interpreter/src/module/_abc/mod.rs#L335
When one thread calls _abc_init(cls) while another replaces cls.__abc_tpflags__, the lookup at line 326 and this separate deletion can interleave: _abc_init may process the old value while deleting the newly assigned one, producing a marker/dictionary state that no serial ordering permits. The new direct-delete implementation still does not implement the atomic retrieve-and-remove semantics of the cited PyDict_Pop; use a single pop operation that returns the exact removed value.
AGENTS.md reference: AGENTS.md:L142-L144
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Inline comments:
In `@majit/majit-backend-wasm/tests/codegen_test.rs`:
- Around line 3662-3699: Extract the duplicated build, validate, instantiate,
execute, and frame-reading logic from run_non_header_region_repro,
run_non_header_capture_repro, and run_two_non_header_regions_repro into a shared
run_inline_region_trace helper. Have it accept ModuleBuildInputs and return the
exit index plus the first three frame-slot values, then update each caller to
perform only its scenario-specific exit assertion and result handling.
In `@pyre/extra_tests/snippets/stdlib_abc.py`:
- Around line 89-96: Add coverage in the abc_with_tpflags overflow tests to
verify that __abc_tpflags__ is consumed even when conversion raises
OverflowError, while preserving the existing checks for overflowing values and
collection flags.
- Around line 157-158: Update the assertion after Marked.register(str) to
directly verify that str lacks PY_TPFLAGS_SEQUENCE using str.__flags__, rather
than relying on matches_sequence_pattern("ab").
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| Marked.register(str) | ||
| assert not matches_sequence_pattern("ab") |
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🎯 Functional Correctness | 🟡 Minor | ⚡ Quick win
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Assert the marker directly for str. match_sequence_value excludes str, bytes, and bytearray after reading the marker, so line 158 passes even if str is incorrectly marked. Add assert not (str.__flags__ & PY_TPFLAGS_SEQUENCE) instead.
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In `@pyre/extra_tests/snippets/stdlib_abc.py` around lines 157 - 158, Update the
assertion after Marked.register(str) to directly verify that str lacks
PY_TPFLAGS_SEQUENCE using str.__flags__, rather than relying on
matches_sequence_pattern("ab").
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The premise is right and I strengthened the line in 09074f4d3b6, but not with the exact assertion suggested — it would turn this snippet red on pyre today.
Measured:
CPython 3.14.6: str.__flags__ & (1<<5) == 0 list SEQ dict MAP
pyre: str.__flags__ & (1<<5) != 0 list SEQ
pyre marks str (and bytes, bytearray, range, memoryview, array) Py_TPFLAGS_SEQUENCE in its typedef.rs registration table, where objspace.py StdObjSpace.initialize marks only dict / dictproxy / list / tuple and CPython marks neither str nor bytes. match_sequence_value compensates with an explicit str/bytes-like exclusion, which is exactly the masking effect noted here. That deviation is real and separately tracked; it is not something this PR introduces, and fixing it means adjudicating eight flag_map_or_seq readers.
What this line is actually about is that register must not hand the marker to an immutable type, so the portable form of the check is that the marker is unchanged across the call:
str_flags = str.__flags__
Marked.register(str)
assert str.__flags__ == str_flags
assert not matches_sequence_pattern("ab")That reads the marker rather than only the pattern, holds on CPython 3.14.6 and on pyre, and will keep holding once str is unmarked.
— commented by Claude
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@youknowone, the proposed check is correct for this test.
It verifies that Marked.register(str) does not change str.__flags__. It does not require Pyre’s current baseline flags to match CPython.
The available review snapshot is 18ba6e7690. It does not contain the str_flags before/after assertion. Commit 09074f4d3b6 is also unavailable in this checkout. I will keep the finding open for this snapshot.
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✏️ Learnings added
Learnt from: youknowone
Repo: youknowone/pyre PR: 1416
File: pyre/extra_tests/snippets/stdlib_abc.py:157-158
Timestamp: 2026-08-22T06:42:02.624Z
Learning: In Pyre, `str`, `bytes`, `bytearray`, `range`, `memoryview`, and `array` currently have `Py_TPFLAGS_SEQUENCE` set by the `typedef.rs` registration table. This differs from CPython for `str` and `bytes`. `match_sequence_value` explicitly excludes string-like values, so sequence-pattern matching does not expose those baseline flags. Tests for `_abc` recursive collection-flag registration must compare an immutable type’s `__flags__` before and after `Marked.register(type)` instead of asserting that its sequence bit is initially clear.
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Two unrelated topics, both root-caused from a dump rather than from reading.
wasm: a region attached to a preamble guard branched into a resume loader
InlineGuard::branch_depthis a depth taken at loop-body statement level, butemit_guard_exitapplied it to whichever guard matched the fail index — including one in the peeled preamble. There the innermost open blocks are the LABEL(past_loader, loader)pairs, so the guard branched into a resume loader that reloads label args from frame slots nothing wrote on that path, and the region body was left with zero predecessors.Confirmed in an emitted WAT: the region's guard reads
br 1 (;@4;)where@4is LABEL 1's resume loader, and the region body has no incoming branch at all.not_headerwas masking this. A preamble guard's loop-closing bridge naturally resumes at an earlier LABEL, which is exactly the population that gate declines — so the defect was latent in the shipped default for any preamble guard whose bridge does close at the header.inline_source_guard_precedes_loop_labeldeclines those bridges (diag 52,source_in_preamble).Verification: minimal repro green; a 5-fixture probe where the preamble-region count is the exact red/green discriminator (the two former reds carry 1 and 2, the three greens carry 0); default corpus 433/433; 53 unit tests. The arm is inert on the default path — a census across all 443 fixtures finds 0 declines.
jit: the mismatch diagnostic printed the wrong field
[jit][jte] virtualstate mismatchcomputed itsruntime_valuewithget_constant_box, which only reads a constant-folded operand, while theConstantarm ofgenerate_guardsdecides onruntime_value_of— the box's observed value. A box that carried the matching value printed as having none. It now prints both.This is the field that sent an investigation down the wrong path for a while, so it is worth its line.
_abc:
__abc_tpflags__was consumed in the wrong placetype_newfolded a class body's__abc_tpflags__into the structural-match marker and left the attribute behind. Two consequences, both measured against pypy3 and CPython 3.14:__abc_tpflags__onSequence_internal_set_collection_flag[_recursive]The second is the real one:
_abc_initruns only for a class going throughABCMeta, so consuming the marker at class creation also marks a plain class that happens to spell the name, andcase [...]then accepts an object that is not a sequence.Moved to
_abc_init, whereapp_abc.pyhas it, with the attribute deleted afterwards. Addedset_collection_flag_offor the non-recursive arm and exported_internal_set_collection_flag/_internal_set_collection_flag_recursive, whichmoduledef.pylists as interpleveldefs and this module had neither of.One spec conflict, resolved explicitly
interp_abc.py set_collection_flagcompares the whole value against a single flag and raisesValueErrorotherwise;_abcmodule.c _abc__abc_init_implmasks and deletes unconditionally. They disagree on real input:__abc_tpflags__(1 << 5) | 10"nope"Spec follows CPython, so
_abc_initmasks. The primitive keeps pypy's strict one-bit contract and only ever receives an already-masked bit, so both surfaces stay faithful.Four upstream citations in this file are restated as symbols rather than line numbers.
Verification
All four
__abc_tpflags__probes now match CPython 3.14 exactly.test_abcOK,test_collectionsOK (skipped=3),test_typingOK (skipped=2). Synthetic corpus on dynasm: 15 failed / 425 passed, an identical failing set to the pre-change control — no regression.test_patmaunder unittest shows 6 failures, all inTestTracing, which contains zero references to abc / Sequence / Mapping / register /__abc_tpflags__; the failures aresys.settraceline-event differences and are pre-existing. Running it as-m test.test_patmahits animport pyperfin the file's__main__benchmark block, which fails on any Python.Everything above was re-measured after a mid-session rebase moved the base to #1409.
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