Store insertion order using offsets#149901
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…tion order - Add test_racing_store_attr_insertion_order: concurrent attribute stores with natural and reverse order - Add test_racing_store_attr_delete_reinsert: concurrent delete + re-insert - Trim stale comments about skip-write optimization Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
A sequential attribute store -- the common case in __init__ -- appends at index == values->size, so the insertion-order delta is 0. Since the insertion-order array slots at or beyond values->size are kept zero, that write can be skipped: _STORE_ATTR_INSTANCE_VALUE now checks index == values->size and just bumps values->size in that case. Keeping those slots zero requires initialising and maintaining them: * _PyObject_InitInlineValues now zeroes the insertion-order array. Not every allocator memsets the inline-values region -- _PyObject_GC_New (used for TypeVar and friends) does not, only _PyType_AllocNoTrack does -- so the array could otherwise start with garbage. * clear_embedded_values (the embedded path of dict.clear()) re-zeroes the array; previously it reset values->size without clearing it. * delete_index_from_values already re-zeroes the vacated slot. The _PyDictValues_AddToInsertionOrderDelta helper is no longer needed and is removed; the non-sequential path uses _PyDictValues_AddToInsertionOrder. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Add the tier-2-only uop _STORE_ATTR_INSTANCE_VALUE_NO_ORDER and teach the JIT optimiser to emit it. When an object is freshly produced by _ALLOCATE_OBJECT, the optimiser tracks its inline values->size statically: each _STORE_ATTR_INSTANCE_VALUE that stores to the next sequential slot is proven to have insertion-order delta 0, so the whole insertion-order bookkeeping (helper call, delta computation, array write) collapses to a single "values->size = N" store. Tracking is dropped on any escaping uop that could hand the object to code mutating its inline values; the store macro's own uops and _POP_TOP are exempt (the object is not yet reachable by user code). Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
eendebakpt
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