FA-90735 / Garbage collector invariants / Member archive

Remembered sets: intra-region pointers recorded · case 05

Remembered sets fill with pointers that never cross a region boundary.

Member previewVariant 5 · 3 implementations · 6 checks per implementation

Case contract

Region-based remembered sets. kinds[r] is young, old, humongous or hcont (a continuation region of the humongous object that starts in the nearest preceding humongous region). For each write [slot, value]: null values are ignored; the target region is the region of value, mapped from continuations back to the humongous start; writes within one region and writes whose slot is in a young region are filtered; otherwise the slot's card index (slot // card) is added to the target region's set. Return the remembered sets.

Why this case matters

Remembered-set filtering decides which cross-region pointers an evacuation will find.

One recorded failure

Sample boundary fixture

This sample comes from the broken implementation of a controlled reproducer.

Boundary fixture	Actual	Expected	Outcome
pointer within the same region	`{"2": [16, 23]}`	`{}`	Failed

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