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Deepti Gandluri authored
This reverts commit fd2548f3. Reason for revert: Breaks telemetry benchmark, blocks deps roll. https://ci.chromium.org/p/chromium/builders/try/linux-rel/373686? https://chromium-swarm.appspot.com/task?id=4be57eb0279bbb10 Original change's description: > Reland^4 "[runtime] Amortize descriptor array growing for fast-mode prototypes" > > This CL: > - stops tracking transitions for fast maps that are known to be detached > - reuses descriptor arrays when transitioning detached maps to avoid O(n^2) performance and garbage creation > > Fix2 in reland: constructor_or_backpointer can be a smi since it can also hold a user-provided function.prototype > Fix in reland: check whether the map of the back pointer is the metamap rather than reading the map of the constructor-or-backpointer slot. If the slot contains a constructor, it's possible that the object transitions while the concurrent marker is reading the map (from which it's reading the instance type); and it's possible that the transitioned map isn't set up yet fully when we read the instance type. An acquire load for the constructor-or-backpointer map would also fix it by serializing stores, but is more expensive. Checking the metamap is faster. > > Original commit message: > > This avoids an O(n^2) algorithm that creates an equal amount of garbage. > > Even though the actual final descriptor array might be a little bigger, > > it reduces peak memory usage by allocating less. > > Change-Id: Id99dc76a369057e5c4d76a31163605cb38a66867 > Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2172080 > Reviewed-by: Ulan Degenbaev <ulan@chromium.org> > Commit-Queue: Toon Verwaest <verwaest@chromium.org> > Cr-Commit-Position: refs/heads/master@{#67501} TBR=ulan@chromium.org,verwaest@chromium.org Change-Id: If305b5410ca37e04e9ec0ce50e9b494f5c4cd4dc No-Presubmit: true No-Tree-Checks: true No-Try: true Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2174767Reviewed-by: Deepti Gandluri <gdeepti@chromium.org> Commit-Queue: Deepti Gandluri <gdeepti@chromium.org> Cr-Commit-Position: refs/heads/master@{#67510}
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