This CL repurposes the v8.wasm trace event category, and introduces
additionally the v8.wasm.detailed category.

The v8.wasm category is enabled by default and captures core wasm events
like validation, compilation, instantiation, and important operations
like grow-memory and tier-up timings.

The v8.wasm.detailed category is disabled by default. It captures all
events the previous v8.wasm category captured, like compilation of
single functions, time needed for register allocation, ...

This CL splits these categories to allow enabling the v8.wasm category
in telemetry benchmarks to calculate compile time and other metrics
from traces of telemetry runs.

R=ecmziegler@chromium.org

Bug: chromium:1084929
Change-Id: Ida58b8f344b0ccb6ee1210e259c3e0e993eff497
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2210230
Commit-Queue: Andreas Haas <ahaas@chromium.org>
Reviewed-by: Clemens Backes <clemensb@chromium.org>
Reviewed-by: Adam Klein <adamk@chromium.org>
Reviewed-by: Emanuel Ziegler <ecmziegler@chromium.org>
Cr-Commit-Position: refs/heads/master@{#68156}

This is a reland of 9efe315e after marking
box2d slow.

Original change's description:
> Mark functions for optimization only on bytecode budget interrupts
>
> We used to mark functions for optimization on any interrupt. This sometimes
> causes functions to OSR when not needed. The implementation was such because
> we didn't have a different runtime function to distinguish bytecode budget
> interrupts from other interrupts. For lazy feedback allocation we added a
> new runtime function for bytecode budget interrupts so it makes it easier
> to actually mark functions only when needed.
>
> This also includes a fix to reduce the stack limits for interrupts when
> entering a scope that allows interrupts from a postponed interrupt scope.
>
> Bug: chromium:993061
> Change-Id: Iaf7b4dccb7a503e5b6bfcbb993bc7482aa593955
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1829218
> Reviewed-by: Leszek Swirski <leszeks@chromium.org>
> Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
> Commit-Queue: Mythri Alle <mythria@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#64048}

Bug: chromium:993061
Change-Id: I24dae03357d6c368e4173db3f071e8ab09e9d6dc
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1832173Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Commit-Queue: Mythri Alle <mythria@chromium.org>
Cr-Commit-Position: refs/heads/master@{#64082}

This reverts commit 9efe315e.

Reason for revert: Causing time out issues on box2d tests:

https://ci.chromium.org/p/v8/builders/ci/V8%20Linux%20-%20debug/27752

and

https://ci.chromium.org/p/v8/builders/ci/V8%20Linux64%20-%20debug/29630

Original change's description:
> Mark functions for optimization only on bytecode budget interrupts
> 
> We used to mark functions for optimization on any interrupt. This sometimes
> causes functions to OSR when not needed. The implementation was such because
> we didn't have a different runtime function to distinguish bytecode budget
> interrupts from other interrupts. For lazy feedback allocation we added a
> new runtime function for bytecode budget interrupts so it makes it easier
> to actually mark functions only when needed.
> 
> This also includes a fix to reduce the stack limits for interrupts when
> entering a scope that allows interrupts from a postponed interrupt scope.
> 
> Bug: chromium:993061
> Change-Id: Iaf7b4dccb7a503e5b6bfcbb993bc7482aa593955
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1829218
> Reviewed-by: Leszek Swirski <leszeks@chromium.org>
> Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
> Commit-Queue: Mythri Alle <mythria@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#64048}

TBR=rmcilroy@chromium.org,mythria@chromium.org,leszeks@chromium.org

Change-Id: I97938934fdaa030b958695d18e1788d75c17077c
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: chromium:993061
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1832645Reviewed-by: Francis McCabe <fgm@chromium.org>
Commit-Queue: Francis McCabe <fgm@chromium.org>
Cr-Commit-Position: refs/heads/master@{#64053}

We used to mark functions for optimization on any interrupt. This sometimes
causes functions to OSR when not needed. The implementation was such because
we didn't have a different runtime function to distinguish bytecode budget
interrupts from other interrupts. For lazy feedback allocation we added a
new runtime function for bytecode budget interrupts so it makes it easier
to actually mark functions only when needed.

This also includes a fix to reduce the stack limits for interrupts when
entering a scope that allows interrupts from a postponed interrupt scope.

Bug: chromium:993061
Change-Id: Iaf7b4dccb7a503e5b6bfcbb993bc7482aa593955
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1829218Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Commit-Queue: Mythri Alle <mythria@chromium.org>
Cr-Commit-Position: refs/heads/master@{#64048}

This reverts commit 9da34831

Original change's description:
> "Reland x4 [arraybuffer] Rearchitect backing store ownership"
>
> This is a reland of bc33f5ae
>
> Contributed by titzer@chromium.org
>
> Original change's description:
> > [arraybuffer] Rearchitect backing store ownership
> >
> > This CL completely rearchitects the ownership of array buffer backing stores,
> > consolidating ownership into a {BackingStore} C++ object that is tracked
> > throughout V8 using unique_ptr and shared_ptr where appropriate.
> >
> > Overall, lifetime management is simpler and more explicit. The numerous
> > ways that array buffers were initialized have been streamlined to one
> > Attach() method on JSArrayBuffer. The array buffer tracker in the
> > GC implementation now manages std::shared_ptr<BackingStore> pointers,
> > and the construction and destruction of the BackingStore object itself
> > handles the underlying page or embedder-allocated memory.
> >
> > The embedder API remains unchanged for now. We use the
> > v8::ArrayBuffer::Contents struct to hide an additional shared_ptr to
> > keep the backing store alive properly, even in the case of aliases
> > from live heap objects. Thus the embedder has a lower chance of making
> > a mistake. Long-term, we should move the embedder to a model where they
> > manage backing stores using shared_ptr to an opaque backing store object.
>
> TBR=yangguo@chromium.org
>
> BUG=v8:9380,v8:9221,chromium:986318
>
> Change-Id: If671a4a9ca0476e8f084efae46e0d2bf99ed99ef
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1731005
> Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
> Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
> Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>

> Cr-Commit-Position: refs/heads/master@{#63041}

TBR=yangguo@chromium.org

Change-Id: I3cc4bb80081c662b1751234bc16a821c20e744be
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1792166
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63617}

This CL makes ThreadManager::InitThread *the* place that's responsible
for initializing metadata for a new thread, and ensures that all new
threads actually go through there. This was previously not the case,
and e.g. test-lockers/LockerUnlocker exposed a case where some threads
were trying to use another thread's simulator instance because the
ThreadLocalTop on the Isolate was in inconsistent state.

Change-Id: I302c643f420457f6ba73897fd45eb87969e1331c
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1781688
Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
Auto-Submit: Jakob Kummerow <jkummerow@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63527}

This reverts commit 62e16830.

Reason for revert: it will be relanded after branch

Original change's description:
> Reland x5 [arraybuffer] Rearchitect backing store ownership
> 
> This reverts commit 8fdb2387.
> 
> Original change's description:
> > "Reland x4 [arraybuffer] Rearchitect backing store ownership"
> >
> > This is a reland of bc33f5ae
> >
> > Contributed by titzer@chromium.org
> >
> > Original change's description:
> > > [arraybuffer] Rearchitect backing store ownership
> > >
> > > This CL completely rearchitects the ownership of array buffer backing stores,
> > > consolidating ownership into a {BackingStore} C++ object that is tracked
> > > throughout V8 using unique_ptr and shared_ptr where appropriate.
> > >
> > > Overall, lifetime management is simpler and more explicit. The numerous
> > > ways that array buffers were initialized have been streamlined to one
> > > Attach() method on JSArrayBuffer. The array buffer tracker in the
> > > GC implementation now manages std::shared_ptr<BackingStore> pointers,
> > > and the construction and destruction of the BackingStore object itself
> > > handles the underlying page or embedder-allocated memory.
> > >
> > > The embedder API remains unchanged for now. We use the
> > > v8::ArrayBuffer::Contents struct to hide an additional shared_ptr to
> > > keep the backing store alive properly, even in the case of aliases
> > > from live heap objects. Thus the embedder has a lower chance of making
> > > a mistake. Long-term, we should move the embedder to a model where they
> > > manage backing stores using shared_ptr to an opaque backing store object.
> >
> > TBR=yangguo@chromium.org
> >
> > BUG=v8:9380,v8:9221,chromium:986318
> >
> > Change-Id: If671a4a9ca0476e8f084efae46e0d2bf99ed99ef
> > Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1731005
> > Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
> > Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
> > Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
> > Cr-Commit-Position: refs/heads/master@{#63041}
> 
> TBR=yangguo@chromium.org,clemensh@chromium.org,mstarzinger@chromium.org
> 
> Change-Id: Iba55c7ab71e5642b5cb6aeb699d6fc9cf9061486
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1771795
> Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
> Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#63461}

TBR=ulan@chromium.org,mlippautz@chromium.org

Change-Id: Id8f67a68ab398032eb2975b1b24ee125394d9c4b
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1776095Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63471}

This reverts commit 8fdb2387.

Original change's description:
> "Reland x4 [arraybuffer] Rearchitect backing store ownership"
>
> This is a reland of bc33f5ae
>
> Contributed by titzer@chromium.org
>
> Original change's description:
> > [arraybuffer] Rearchitect backing store ownership
> >
> > This CL completely rearchitects the ownership of array buffer backing stores,
> > consolidating ownership into a {BackingStore} C++ object that is tracked
> > throughout V8 using unique_ptr and shared_ptr where appropriate.
> >
> > Overall, lifetime management is simpler and more explicit. The numerous
> > ways that array buffers were initialized have been streamlined to one
> > Attach() method on JSArrayBuffer. The array buffer tracker in the
> > GC implementation now manages std::shared_ptr<BackingStore> pointers,
> > and the construction and destruction of the BackingStore object itself
> > handles the underlying page or embedder-allocated memory.
> >
> > The embedder API remains unchanged for now. We use the
> > v8::ArrayBuffer::Contents struct to hide an additional shared_ptr to
> > keep the backing store alive properly, even in the case of aliases
> > from live heap objects. Thus the embedder has a lower chance of making
> > a mistake. Long-term, we should move the embedder to a model where they
> > manage backing stores using shared_ptr to an opaque backing store object.
>
> TBR=yangguo@chromium.org
>
> BUG=v8:9380,v8:9221,chromium:986318
>
> Change-Id: If671a4a9ca0476e8f084efae46e0d2bf99ed99ef
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1731005
> Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
> Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
> Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#63041}

TBR=yangguo@chromium.org,clemensh@chromium.org,mstarzinger@chromium.org

Change-Id: Iba55c7ab71e5642b5cb6aeb699d6fc9cf9061486
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1771795Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63461}

Stack limits were additionally maintained in pseudo-smi roots.
"Pseudo", because we stored the raw limit pointers there, just making
sure their values looked like smis by masking the least significant
bits.

This mechanism is no longer needed now that we can access the stack
limit external references as efficiently as the smi roots.

Bug: v8:9534
Change-Id: I37e78851c97aebc1012ea0e95075e56366a40a73
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1745339
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63183}

IsolateData guarantees a fixed root-relative offset for its contents,
thus allowing more efficient code generation for accesses to these
addresses. The stack limit, located within the StackGuard, is used by
all stack checks in CSA.

This CL moves the StackGuard inside IsolateData to make such efficient
loads of the limit possible.

Bug: v8:9595,v8:9534
Change-Id: I9abe26b88952709c88bf625cc6c028497815a58c
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1741648Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Auto-Submit: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63160}

This reverts commit 5611f70b.

Reason for revert: flaky tests: v8:9588, v8:9587

Original change's description:
> "Reland x4 [arraybuffer] Rearchitect backing store ownership"
> 
> This is a reland of bc33f5ae
> 
> Contributed by titzer@chromium.org
> 
> Original change's description:
> > [arraybuffer] Rearchitect backing store ownership
> >
> > This CL completely rearchitects the ownership of array buffer backing stores,
> > consolidating ownership into a {BackingStore} C++ object that is tracked
> > throughout V8 using unique_ptr and shared_ptr where appropriate.
> >
> > Overall, lifetime management is simpler and more explicit. The numerous
> > ways that array buffers were initialized have been streamlined to one
> > Attach() method on JSArrayBuffer. The array buffer tracker in the
> > GC implementation now manages std::shared_ptr<BackingStore> pointers,
> > and the construction and destruction of the BackingStore object itself
> > handles the underlying page or embedder-allocated memory.
> >
> > The embedder API remains unchanged for now. We use the
> > v8::ArrayBuffer::Contents struct to hide an additional shared_ptr to
> > keep the backing store alive properly, even in the case of aliases
> > from live heap objects. Thus the embedder has a lower chance of making
> > a mistake. Long-term, we should move the embedder to a model where they
> > manage backing stores using shared_ptr to an opaque backing store object.
> 
> TBR=yangguo@chromium.org
> 
> BUG=v8:9380,v8:9221,chromium:986318
> 
> Change-Id: If671a4a9ca0476e8f084efae46e0d2bf99ed99ef
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1731005
> Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
> Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
> Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#63041}

TBR=ulan@chromium.org,yangguo@chromium.org,mstarzinger@chromium.org,clemensh@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: v8:9380, v8:9221, chromium:986318
Change-Id: Ic7381239f4e90d0c437b7e47a5ac6e8bce60f882
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1736747Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63081}

This is a reland of bc33f5ae

Contributed by titzer@chromium.org

Original change's description:
> [arraybuffer] Rearchitect backing store ownership
>
> This CL completely rearchitects the ownership of array buffer backing stores,
> consolidating ownership into a {BackingStore} C++ object that is tracked
> throughout V8 using unique_ptr and shared_ptr where appropriate.
>
> Overall, lifetime management is simpler and more explicit. The numerous
> ways that array buffers were initialized have been streamlined to one
> Attach() method on JSArrayBuffer. The array buffer tracker in the
> GC implementation now manages std::shared_ptr<BackingStore> pointers,
> and the construction and destruction of the BackingStore object itself
> handles the underlying page or embedder-allocated memory.
>
> The embedder API remains unchanged for now. We use the
> v8::ArrayBuffer::Contents struct to hide an additional shared_ptr to
> keep the backing store alive properly, even in the case of aliases
> from live heap objects. Thus the embedder has a lower chance of making
> a mistake. Long-term, we should move the embedder to a model where they
> manage backing stores using shared_ptr to an opaque backing store object.

TBR=yangguo@chromium.org

BUG=v8:9380,v8:9221,chromium:986318

Change-Id: If671a4a9ca0476e8f084efae46e0d2bf99ed99ef
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1731005
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63041}

This reverts commit df8e6177.

Reason for revert: Multiple flakes in apparently related areas:

https://logs.chromium.org/logs/v8/buildbucket/cr-buildbucket.appspot.com/8906409837768155568/+/steps/Check__flakes_/0/logs/BackingStoreTest.RacyGrowWasmMem.../0

Original change's description:
> "Reland x3 [arraybuffer] Rearchitect backing store ownership"
> 
> This is a reland of bc33f5ae
> 
> Original change's description:
> > [arraybuffer] Rearchitect backing store ownership
> >
> > This CL completely rearchitects the ownership of array buffer backing stores,
> > consolidating ownership into a {BackingStore} C++ object that is tracked
> > throughout V8 using unique_ptr and shared_ptr where appropriate.
> >
> > Overall, lifetime management is simpler and more explicit. The numerous
> > ways that array buffers were initialized have been streamlined to one
> > Attach() method on JSArrayBuffer. The array buffer tracker in the
> > GC implementation now manages std::shared_ptr<BackingStore> pointers,
> > and the construction and destruction of the BackingStore object itself
> > handles the underlying page or embedder-allocated memory.
> >
> > The embedder API remains unchanged for now. We use the
> > v8::ArrayBuffer::Contents struct to hide an additional shared_ptr to
> > keep the backing store alive properly, even in the case of aliases
> > from live heap objects. Thus the embedder has a lower chance of making
> > a mistake. Long-term, we should move the embedder to a model where they
> > manage backing stores using shared_ptr to an opaque backing store object.
> 
> R=​mlippautz@chromium.org
> BUG=v8:9380,v8:9221,chromium:986318
> TBR=ulan@chromium.org
> 
> Change-Id: I6c49e2425029b5664ef1c68dab8b5146f4ed0ff2
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1719191
> Reviewed-by: Ben Titzer <titzer@chromium.org>
> Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
> Commit-Queue: Ben Titzer <titzer@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#63007}

TBR=mstarzinger@chromium.org,titzer@chromium.org,mlippautz@chromium.org

Change-Id: If0266e5893b1325a332d5986337fa7ece2cb6943
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:9380, v8:9221, chromium:986318
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1729549Reviewed-by: Francis McCabe <fgm@chromium.org>
Commit-Queue: Francis McCabe <fgm@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63011}

This is a reland of bc33f5ae

Original change's description:
> [arraybuffer] Rearchitect backing store ownership
>
> This CL completely rearchitects the ownership of array buffer backing stores,
> consolidating ownership into a {BackingStore} C++ object that is tracked
> throughout V8 using unique_ptr and shared_ptr where appropriate.
>
> Overall, lifetime management is simpler and more explicit. The numerous
> ways that array buffers were initialized have been streamlined to one
> Attach() method on JSArrayBuffer. The array buffer tracker in the
> GC implementation now manages std::shared_ptr<BackingStore> pointers,
> and the construction and destruction of the BackingStore object itself
> handles the underlying page or embedder-allocated memory.
>
> The embedder API remains unchanged for now. We use the
> v8::ArrayBuffer::Contents struct to hide an additional shared_ptr to
> keep the backing store alive properly, even in the case of aliases
> from live heap objects. Thus the embedder has a lower chance of making
> a mistake. Long-term, we should move the embedder to a model where they
> manage backing stores using shared_ptr to an opaque backing store object.

R=mlippautz@chromium.org
BUG=v8:9380,v8:9221,chromium:986318
TBR=ulan@chromium.org

Change-Id: I6c49e2425029b5664ef1c68dab8b5146f4ed0ff2
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1719191Reviewed-by: Ben Titzer <titzer@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Commit-Queue: Ben Titzer <titzer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63007}

This reverts commit 306cf403.

Reason for revert: performance regressions / too near branch point

TBR=mslekova@chromium.org
BUG=v8:9380

Change-Id: If77630b73eafbf1190c823199fe2a34361da303f
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1714867Reviewed-by: Ben Titzer <titzer@chromium.org>
Reviewed-by: Maya Lekova <mslekova@chromium.org>
Commit-Queue: Ben Titzer <titzer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#62867}

This is a reland of bc33f5ae

Original change's description:
> Reland "[arraybuffer] Rearchitect backing store ownership"
> 
> This is a reland of 31cd5d83
> 
> Original change's description:
> > [arraybuffer] Rearchitect backing store ownership
> > 
> > This CL completely rearchitects the ownership of array buffer backing stores,
> > consolidating ownership into a {BackingStore} C++ object that is tracked
> > throughout V8 using unique_ptr and shared_ptr where appropriate.
> > 
> > Overall, lifetime management is simpler and more explicit. The numerous
> > ways that array buffers were initialized have been streamlined to one
> > Attach() method on JSArrayBuffer. The array buffer tracker in the
> > GC implementation now manages std::shared_ptr<BackingStore> pointers,
> > and the construction and destruction of the BackingStore object itself
> > handles the underlying page or embedder-allocated memory.
> > 
> > The embedder API remains unchanged for now. We use the
> > v8::ArrayBuffer::Contents struct to hide an additional shared_ptr to
> > keep the backing store alive properly, even in the case of aliases
> > from live heap objects. Thus the embedder has a lower chance of making
> > a mistake. Long-term, we should move the embedder to a model where they
> > manage backing stores using shared_ptr to an opaque backing store object.
> > 
> > R=mlippautz@chromium.org
> > BUG=v8:9380,v8:9221
> > 
> > Change-Id: I48fae5ac85dcf6172a83f252439e77e7c1a16ccd
> > Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1584323
> > Commit-Queue: Ben Titzer <titzer@chromium.org>
> > Reviewed-by: Ben Titzer <titzer@chromium.org>
> > Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
> > Reviewed-by: Yang Guo <yangguo@chromium.org>
> > Reviewed-by: Deepti Gandluri <gdeepti@chromium.org>
> > Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
> > Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
> > Cr-Commit-Position: refs/heads/master@{#62572}
> 
> Bug: v8:9380, v8:9221
> Change-Id: If3f72967a8ebeb067c0edcfc16ed631e36829dbc
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1691906
> Commit-Queue: Ben Titzer <titzer@chromium.org>
> Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
> Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
> Reviewed-by: Deepti Gandluri <gdeepti@chromium.org>
> Reviewed-by: Yang Guo <yangguo@chromium.org>
> Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#62809}

Bug: v8:9380, v8:9221
Change-Id: I9a2525753ae2424108d074fa81df5f25d945c824
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1709409
Commit-Queue: Ben Titzer <titzer@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#62847}

This reverts commit bc33f5ae.

Reason for revert: Still failing (OOM on win32): https://ci.chromium.org/p/v8/builders/ci/V8%20Win32/22210

Original change's description:
> Reland "[arraybuffer] Rearchitect backing store ownership"
> 
> This is a reland of 31cd5d83
> 
> Original change's description:
> > [arraybuffer] Rearchitect backing store ownership
> > 
> > This CL completely rearchitects the ownership of array buffer backing stores,
> > consolidating ownership into a {BackingStore} C++ object that is tracked
> > throughout V8 using unique_ptr and shared_ptr where appropriate.
> > 
> > Overall, lifetime management is simpler and more explicit. The numerous
> > ways that array buffers were initialized have been streamlined to one
> > Attach() method on JSArrayBuffer. The array buffer tracker in the
> > GC implementation now manages std::shared_ptr<BackingStore> pointers,
> > and the construction and destruction of the BackingStore object itself
> > handles the underlying page or embedder-allocated memory.
> > 
> > The embedder API remains unchanged for now. We use the
> > v8::ArrayBuffer::Contents struct to hide an additional shared_ptr to
> > keep the backing store alive properly, even in the case of aliases
> > from live heap objects. Thus the embedder has a lower chance of making
> > a mistake. Long-term, we should move the embedder to a model where they
> > manage backing stores using shared_ptr to an opaque backing store object.
> > 
> > R=mlippautz@chromium.org
> > BUG=v8:9380,v8:9221
> > 
> > Change-Id: I48fae5ac85dcf6172a83f252439e77e7c1a16ccd
> > Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1584323
> > Commit-Queue: Ben Titzer <titzer@chromium.org>
> > Reviewed-by: Ben Titzer <titzer@chromium.org>
> > Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
> > Reviewed-by: Yang Guo <yangguo@chromium.org>
> > Reviewed-by: Deepti Gandluri <gdeepti@chromium.org>
> > Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
> > Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
> > Cr-Commit-Position: refs/heads/master@{#62572}
> 
> Bug: v8:9380, v8:9221
> Change-Id: If3f72967a8ebeb067c0edcfc16ed631e36829dbc
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1691906
> Commit-Queue: Ben Titzer <titzer@chromium.org>
> Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
> Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
> Reviewed-by: Deepti Gandluri <gdeepti@chromium.org>
> Reviewed-by: Yang Guo <yangguo@chromium.org>
> Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#62809}

TBR=ulan@chromium.org,yangguo@chromium.org,mstarzinger@chromium.org,titzer@chromium.org,gdeepti@chromium.org,mlippautz@chromium.org

Change-Id: Iea755df9aaa1e95d284135bd0a6681b1340b6832
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:9380, v8:9221
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1708487Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#62811}

This is a reland of 31cd5d83

Original change's description:
> [arraybuffer] Rearchitect backing store ownership
> 
> This CL completely rearchitects the ownership of array buffer backing stores,
> consolidating ownership into a {BackingStore} C++ object that is tracked
> throughout V8 using unique_ptr and shared_ptr where appropriate.
> 
> Overall, lifetime management is simpler and more explicit. The numerous
> ways that array buffers were initialized have been streamlined to one
> Attach() method on JSArrayBuffer. The array buffer tracker in the
> GC implementation now manages std::shared_ptr<BackingStore> pointers,
> and the construction and destruction of the BackingStore object itself
> handles the underlying page or embedder-allocated memory.
> 
> The embedder API remains unchanged for now. We use the
> v8::ArrayBuffer::Contents struct to hide an additional shared_ptr to
> keep the backing store alive properly, even in the case of aliases
> from live heap objects. Thus the embedder has a lower chance of making
> a mistake. Long-term, we should move the embedder to a model where they
> manage backing stores using shared_ptr to an opaque backing store object.
> 
> R=mlippautz@chromium.org
> BUG=v8:9380,v8:9221
> 
> Change-Id: I48fae5ac85dcf6172a83f252439e77e7c1a16ccd
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1584323
> Commit-Queue: Ben Titzer <titzer@chromium.org>
> Reviewed-by: Ben Titzer <titzer@chromium.org>
> Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
> Reviewed-by: Yang Guo <yangguo@chromium.org>
> Reviewed-by: Deepti Gandluri <gdeepti@chromium.org>
> Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
> Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#62572}

Bug: v8:9380, v8:9221
Change-Id: If3f72967a8ebeb067c0edcfc16ed631e36829dbc
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1691906
Commit-Queue: Ben Titzer <titzer@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Deepti Gandluri <gdeepti@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#62809}

This reverts commit 31cd5d83.

Reason for revert: It breaks my heart to revert this, but it fails differently on several bots, e.g. https://ci.chromium.org/p/v8/builders/ci/V8%20Linux%20-%20debug/26671.

Original change's description:
> [arraybuffer] Rearchitect backing store ownership
> 
> This CL completely rearchitects the ownership of array buffer backing stores,
> consolidating ownership into a {BackingStore} C++ object that is tracked
> throughout V8 using unique_ptr and shared_ptr where appropriate.
> 
> Overall, lifetime management is simpler and more explicit. The numerous
> ways that array buffers were initialized have been streamlined to one
> Attach() method on JSArrayBuffer. The array buffer tracker in the
> GC implementation now manages std::shared_ptr<BackingStore> pointers,
> and the construction and destruction of the BackingStore object itself
> handles the underlying page or embedder-allocated memory.
> 
> The embedder API remains unchanged for now. We use the
> v8::ArrayBuffer::Contents struct to hide an additional shared_ptr to
> keep the backing store alive properly, even in the case of aliases
> from live heap objects. Thus the embedder has a lower chance of making
> a mistake. Long-term, we should move the embedder to a model where they
> manage backing stores using shared_ptr to an opaque backing store object.
> 
> R=​mlippautz@chromium.org
> BUG=v8:9380,v8:9221
> 
> Change-Id: I48fae5ac85dcf6172a83f252439e77e7c1a16ccd
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1584323
> Commit-Queue: Ben Titzer <titzer@chromium.org>
> Reviewed-by: Ben Titzer <titzer@chromium.org>
> Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
> Reviewed-by: Yang Guo <yangguo@chromium.org>
> Reviewed-by: Deepti Gandluri <gdeepti@chromium.org>
> Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
> Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#62572}

TBR=ulan@chromium.org,yangguo@chromium.org,mstarzinger@chromium.org,titzer@chromium.org,gdeepti@chromium.org,mlippautz@chromium.org

Change-Id: Ib35788ba8c31192d90cbc72df3dbc41030f109de
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:9380, v8:9221
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1691034Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#62578}

This CL completely rearchitects the ownership of array buffer backing stores,
consolidating ownership into a {BackingStore} C++ object that is tracked
throughout V8 using unique_ptr and shared_ptr where appropriate.

Overall, lifetime management is simpler and more explicit. The numerous
ways that array buffers were initialized have been streamlined to one
Attach() method on JSArrayBuffer. The array buffer tracker in the
GC implementation now manages std::shared_ptr<BackingStore> pointers,
and the construction and destruction of the BackingStore object itself
handles the underlying page or embedder-allocated memory.

The embedder API remains unchanged for now. We use the
v8::ArrayBuffer::Contents struct to hide an additional shared_ptr to
keep the backing store alive properly, even in the case of aliases
from live heap objects. Thus the embedder has a lower chance of making
a mistake. Long-term, we should move the embedder to a model where they
manage backing stores using shared_ptr to an opaque backing store object.

R=mlippautz@chromium.org
BUG=v8:9380,v8:9221

Change-Id: I48fae5ac85dcf6172a83f252439e77e7c1a16ccd
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1584323
Commit-Queue: Ben Titzer <titzer@chromium.org>
Reviewed-by: Ben Titzer <titzer@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Reviewed-by: Deepti Gandluri <gdeepti@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#62572}

Refactor-only, this moves interrupt scopes and stack guard code into
their own dedicated files.

Change-Id: I5723a04786a04bba31a0da54622f3cd0b926ef07
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1655288
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#62141}