This is a reland of 863bc2b88a
Diff to original:
- Don't eliminate GC observable stores that were temporarily
unobservable during traversal.
- Skip the previously added test for single-generation
- Add new test
Original change's description:
> [turbofan] Improve StoreStoreElimination
>
> Previously, StoreStoreElimination handled allocations as
> "can observe anything". This is pretty conservative and prohibits
> elimination of repeated double stores to the same field.
> With this CL allocations are changed to "observes initializing or
> transitioning stores".
> This way it is guaranteed that initializing stores to a freshly created
> object or stores that are part of a map transition are not eliminated
> before allocations (that can trigger GC), but allows elimination of
> non-initializing, non-transitioning, unobservable stores in the
> presence of allocations.
>
> Bug: v8:12200
> Change-Id: Ie1419696b9c8cb7c39aecf38d9f08102177b2c0f
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3295449
> Commit-Queue: Patrick Thier <pthier@chromium.org>
> Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
> Reviewed-by: Maya Lekova <mslekova@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#78230}
Bug: v8:12200, chromium:1276923, v8:12477
Change-Id: Ied45ee28ac12b370f7b232d2d338f93e10fea6b4
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3320460
Reviewed-by: Maya Lekova <mslekova@chromium.org>
Commit-Queue: Patrick Thier <pthier@chromium.org>
Cr-Commit-Position: refs/heads/main@{#78349}
e926da4592