This is a reland of 76a2ab06a1
Changes since the original CL:
- Handle unserialized elements (optional result in getter).
- Merge should_access_heap and --turbo-direct-heap-access paths.
- Slightly update the serialized path in GetOwnCowElement.
- Fix the cctest, add a regression test.
Atomic JSObject::elements/JSArray::length setters are addressed
in this CL: crrev.com/c/2704076.
Original change's description:
> [compiler] Direct heap reads for JSArrayRef
>
> There are two aspects to the non-JSObject parts of JSArrayRef:
>
> - JSArrayRef::length. Relevant only in two spots, 1. when reading
> (immutable) array boilerplates and 2. for GetOwnCowElement.
>
> - JSArrayRef::GetOwnCowElement. May read into a copy-on-write backing
> store. Relies on the invariant that cow backing stores are immutable.
>
> This CL renames the length accessor to length_unsafe to make the
> danger explicit at callsites.
>
> For GetOwnCowElement the refactor is slightly larger, since we now
> need to read into the backing store while keeping full control of
> object reads (e.g. JSArray::length and JSArray::elements_kind). We
> make all reads explicit at the call site by requiring that elements,
> elements kind, and length are passed in as arguments to
> GetOwnCowElement. Inside GetOwnCowElement, consistency between these
> is *not* guaranteed due to concurrency. At runtime, consistency *is*
> guaranteed through the reference-equality check on the elements seen
> during compilation. The actual elements read is implemented in
> ConcurrentLookupIterator::GetOwnCowElement.
>
> Bug: v8:7790
> Change-Id: I9aa169ce4f2b1e2bfe1e9232007669eb7654a995
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2695403
> Commit-Queue: Jakob Gruber <jgruber@chromium.org>
> Reviewed-by: Georg Neis <neis@chromium.org>
> Reviewed-by: Igor Sheludko <ishell@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#72834}
Bug: v8:7790
Change-Id: I7577ad554992cafff81099a28c34f27db9bd8042
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2710431
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Reviewed-by: Georg Neis <neis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#72904}
This reverts commit 76a2ab06a1.
Reason for revert: A few issues, e.g.
https://logs.chromium.org/logs/v8/buildbucket/cr-buildbucket.appspot.com/8854931126653780144/+/u/Check__flakes_/ArrayWithCowElements
Original change's description:
> [compiler] Direct heap reads for JSArrayRef
>
> There are two aspects to the non-JSObject parts of JSArrayRef:
>
> - JSArrayRef::length. Relevant only in two spots, 1. when reading
> (immutable) array boilerplates and 2. for GetOwnCowElement.
>
> - JSArrayRef::GetOwnCowElement. May read into a copy-on-write backing
> store. Relies on the invariant that cow backing stores are immutable.
>
> This CL renames the length accessor to length_unsafe to make the
> danger explicit at callsites.
>
> For GetOwnCowElement the refactor is slightly larger, since we now
> need to read into the backing store while keeping full control of
> object reads (e.g. JSArray::length and JSArray::elements_kind). We
> make all reads explicit at the call site by requiring that elements,
> elements kind, and length are passed in as arguments to
> GetOwnCowElement. Inside GetOwnCowElement, consistency between these
> is *not* guaranteed due to concurrency. At runtime, consistency *is*
> guaranteed through the reference-equality check on the elements seen
> during compilation. The actual elements read is implemented in
> ConcurrentLookupIterator::GetOwnCowElement.
>
> Bug: v8:7790
> Change-Id: I9aa169ce4f2b1e2bfe1e9232007669eb7654a995
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2695403
> Commit-Queue: Jakob Gruber <jgruber@chromium.org>
> Reviewed-by: Georg Neis <neis@chromium.org>
> Reviewed-by: Igor Sheludko <ishell@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#72834}
Bug: v8:7790, chromium:1180012
Change-Id: I50e72380c544b2b78e1e3dc87a8249281b710912
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2704666
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Commit-Queue: Georg Neis <neis@chromium.org>
Reviewed-by: Georg Neis <neis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#72860}
There are two aspects to the non-JSObject parts of JSArrayRef:
- JSArrayRef::length. Relevant only in two spots, 1. when reading
(immutable) array boilerplates and 2. for GetOwnCowElement.
- JSArrayRef::GetOwnCowElement. May read into a copy-on-write backing
store. Relies on the invariant that cow backing stores are immutable.
This CL renames the length accessor to length_unsafe to make the
danger explicit at callsites.
For GetOwnCowElement the refactor is slightly larger, since we now
need to read into the backing store while keeping full control of
object reads (e.g. JSArray::length and JSArray::elements_kind). We
make all reads explicit at the call site by requiring that elements,
elements kind, and length are passed in as arguments to
GetOwnCowElement. Inside GetOwnCowElement, consistency between these
is *not* guaranteed due to concurrency. At runtime, consistency *is*
guaranteed through the reference-equality check on the elements seen
during compilation. The actual elements read is implemented in
ConcurrentLookupIterator::GetOwnCowElement.
Bug: v8:7790
Change-Id: I9aa169ce4f2b1e2bfe1e9232007669eb7654a995
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2695403
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Georg Neis <neis@chromium.org>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#72834}
Jakob Gruber
Georg Neis