The stack object is primarily used for conservative stack scanning, both
by the V8 and C++ garbage collectors. This CL introduces the notion of a
"stack context", which comprises of the current stack marker (the lowest
address on the stack that may contain interesting pointers) and the
values of the saved registers. It simplifies the way in which iteration
through the stack is invoked: the context must have previously been
saved and iteration always uses the stack marker.
Bug: v8:13257
Bug: v8:13493
Change-Id: Ia99ef702eb6ac67a3bcd006f0edf5e57d9975ab2
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/4017512
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Omer Katz <omerkatz@chromium.org>
Commit-Queue: Nikolaos Papaspyrou <nikolaos@chromium.org>
Cr-Commit-Position: refs/heads/main@{#84303}
It's been enabled by default since Chromium M95.
Also removes duplicate setup code for WebAssembly.Tag JS API
from WasmJs::InstallConditionalFeatures, since we're guaranteed
to set it up via the non-conditional WasmJs::Install.
Bug: v8:8091
Change-Id: Ic500feb655ad4fc0703ed226504847ca6d940537
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3996810
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Adam Klein <adamk@chromium.org>
Cr-Commit-Position: refs/heads/main@{#84074}
This CL introduces the mechanism for conservative stack scanning (CSS).
Behind a compile-time flag, it also introduces a CSS pass which scans
the stack during the GC marking phase and marking verification. This
pass is now redundant, i.e., it is not needed for the correctness of
garbage collection. It will be used for experimenting with CSS and for
benchmarking.
Bug: v8:13257
Change-Id: If35bc24fde3bc08c5735d9e2f1b67724f7e31ef7
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3968710
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Omer Katz <omerkatz@chromium.org>
Commit-Queue: Nikolaos Papaspyrou <nikolaos@chromium.org>
Cr-Commit-Position: refs/heads/main@{#84036}
Maps are now in old space, so start to report the first page in old
space now.
Bug: v8:12578
Change-Id: Icf08c9074558a2d47bb9f1f8df72cec9668d2b4e
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3986087
Auto-Submit: Dominik Inführ <dinfuehr@chromium.org>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/main@{#84002}
It's been enabled by default since Chrome 91.
Bug: v8:6020
Change-Id: Id26b7fb0b7dffe19a88a6f0071dd59203b06415a
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3957636
Reviewed-by: Deepti Gandluri <gdeepti@chromium.org>
Commit-Queue: Adam Klein <adamk@chromium.org>
Cr-Commit-Position: refs/heads/main@{#83862}
When merging a newly deserialized script into an existing one from the
compilation cache, it is often the case that a SharedFunctionInfo from
the cached script ("old SFI") has been flushed and the corresponding
SharedFunctionInfo from the new script ("new SFI") is compiled. In that
case, it is sufficient to copy the bytecode array and feedback metadata
from the new SFI to the old SFI, as already implemented.
However, there is another case to consider: perhaps the new SFI is
compiled and the old SFI was never compiled. In that case, the old SFI
has no ScopeInfo and some of its flags may be incorrect.
To fix the problem, this CL updates CompleteMergeInForeground to copy
everything except script_or_debug_info from the new SFI to the old SFI.
This change implies some duplication of ScopeInfos, since each ScopeInfo
can point to its parent, so matching parent ScopeInfos from the new and
old scripts will coexist. However, this isn't a new problem: similar
duplication is already caused by the portion of the merge algorithm
which attaches new compiled SFIs into the old Script where the old
Script doesn't have a matching SFI. I don't see any way in which this
duplication would cause incorrect behavior. In fact, it is possible to
get duplicated ScopeInfos without any merging at all, which indicates to
me that such duplication is safe. Duplication occurs if a SFI is flushed
or removed while one of its descendant functions is still alive, and
subsequently the same function literal is compiled again.
Bug: v8:12808, chromium:1359773
Change-Id: I2a3a720021c797c62a87d10e999603ff5e29a027
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3965723
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Seth Brenith <seth.brenith@microsoft.com>
Cr-Commit-Position: refs/heads/main@{#83825}
A circular ownership of ref-counted resources caused the leak as the
wasm::StreamingDecoder stored a callback that contained the decoder in
its scope (needed for the URL).
Bug: chromium:1368609
Change-Id: Ib07b066c92f16b658daa1daf482f71c33a16e89a
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3942066
Reviewed-by: Clemens Backes <clemensb@chromium.org>
Commit-Queue: Matthias Liedtke <mliedtke@chromium.org>
Cr-Commit-Position: refs/heads/main@{#83695}
It is possible, though unlikely, that V8 will deserialize code cache
data, decide to merge that new data with an existing script from the
Isolate compilation cache, and subsequently do nothing in the background
portion of the merge (make no heap changes, and request no follow-up
changes on the main thread). In this case, the most optimal outcome is
to reuse the script from the Isolate compilation cache, not to use the
newly deserialized script.
CodeSerializer::FinishOffThreadDeserialize uses
BackgroundMergeTask::HasPendingForegroundWork to determine whether it
should complete the merge and use the Script from the compilation cache
or complete the deserialization and use the newly deserialized Script.
This change updates HasPendingForegroundWork so that it will return true
even if the merge was a no-op.
Bug: v8:12808
Change-Id: I08fcb814e797218e5be2b4ce4f45bd4e0637ec80
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3916270
Commit-Queue: Seth Brenith <seth.brenith@microsoft.com>
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/main@{#83439}
V8-side implementation for trusted types fromLiteral.
Create a separate JSArray root map for template literal objects to
clearly identify untampered template literals belonging to a given
context.
Given that template literals are frozen arrays with a 'raw' property,
we don't expect additional polymorphism.
Drive-by-fix:
Avoid ValidateElements call in NewJSArrayWithElements.
Bug: chromium:1271149
Change-Id: I327b0fd99a2db3b57d35efa9293ddf2f14e555ea
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3572044
Reviewed-by: Shu-yu Guo <syg@chromium.org>
Commit-Queue: Camillo Bruni <cbruni@chromium.org>
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Auto-Submit: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/main@{#83383}
Avoid the deprecated FLAG_* syntax, access flag values via the
{v8_flags} struct instead.
R=jkummerow@chromium.org
Bug: v8:12887
Change-Id: Ieccf35730f69bcefa3740227f15e05686080d122
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3843517
Auto-Submit: Clemens Backes <clemensb@chromium.org>
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
Cr-Commit-Position: refs/heads/main@{#82774}
... when the code range is created. This key should be more helpful
than the existing kCodeSpaceFirstPageAddress crash key, especially
for the cases when snapshot does not contain Code objects and thus
the code space is not created during Isolate initialization.
The mid-term plan is to remove the latter in favour of the former
since the default configuration does not imply creation of the code
space.
Bug: v8:11880
Change-Id: Icdea38723c7ed73605c2df6589ec01193571d55c
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3849038
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/main@{#82667}
The existing version for paged spaces simply reset the freelist, which
doesn't work for tests that require actual objects in the space.
The version for new space also doesn't work because it assumes
everything after top is free space.
Fill the space with FixedArray by iterating over the freelist and
creating an object in place of each freelist entry.
This method actually fills the space, so that we can also use it to
force page promotion.
Bug: v8:12612
Change-Id: Ie0d73e846bbf688ea52030be29e0587b2f37ed4e
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3823135
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Omer Katz <omerkatz@chromium.org>
Cr-Commit-Position: refs/heads/main@{#82437}
This pr refactor all usage of v8_str in unittests/ into NewString
method in test-utils.h
Change-Id: I8ffc456851488e8c050d7a38f5459aebfa3f314f
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3813064
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: 王澳 <wangao.james@bytedance.com>
Cr-Commit-Position: refs/heads/main@{#82314}
This is a reland of commit e895b7af73
The unit test has been updated to work correctly when
--stress-incremental-marking is enabled.
Original change's description:
> Background merging of deserialized scripts
>
> Recently, https://crrev.com/c/v8/v8/+/3681880 added new API functions
> with which an embedder could request that V8 merge newly deserialized
> script data into an existing Script from the Isolate's compilation
> cache. This change implements those new functions. This functionality is
> still disabled by default due to the flag
> merge_background_deserialized_script_with_compilation_cache.
>
> The goal of this new functionality is to reduce memory usage when
> multiple frames load the same script with a long delay between (long
> enough for the script to have been evicted from Blink's in-memory cache
> and for the top-level SharedFunctionInfo to be flushed). In that case,
> there are two Script objects for the same script: one which was found in
> the Isolate compilation cache (the "old" script), and one which was
> recently deserialized (the "new" script). The new script's object graph
> is essentially standalone: it may point to internalized strings and
> readonly objects such as the empty feedback metadata, but otherwise
> it is unconnected to the rest of the heap. The merging logic takes any
> useful data from the new script's object graph and attaches it into the
> old script's object graph, so that the new Script object and any other
> duplicated objects can be discarded. More specifically:
>
> 1. If the new Script has a SharedFunctionInfo for a particular function
> literal, and the old Script does not, then the old Script is updated
> to refer to the new SharedFunctionInfo.
> 2. If the new Script has a compiled SharedFunctionInfo for a particular
> function literal, and the old Script has an uncompiled
> SharedFunctionInfo, then the old SharedFunctionInfo is updated to
> point to the function_data and feedback_metadata from the new
> SharedFunctionInfo.
> 3. If any used object from the new object graph points to a
> SharedFunctionInfo, where the old object graph contains a matching
> SharedFunctionInfo for the same function literal, then that pointer
> is updated to point to the old SharedFunctionInfo.
>
> The document at [0] includes diagrams showing an example merge on a very
> small script.
>
> Steps 1 and 2 above are pretty simple, but step 3 requires walking a
> possibly large set of objects, so this new API lets the embedder run
> step 3 from a background thread. Steps 1 and 2 are performed later, on
> the main thread.
>
> The next important question is: in what ways can the old script's object
> graph be modified during the background execution of step 3, or during
> the time after step 3 but before steps 1 and 2?
>
> A. SharedFunctionInfos can go from compiled to uncompiled due to
> flushing. This is okay; the worst outcome is that the function would
> need to be compiled again later. Such a risk is already present,
> since V8 doesn't keep IsCompiledScopes for every compiled function in
> a background-deserialized script.
> B. SharedFunctionInfos can go from uncompiled to compiled due to lazy
> compilation. This is also okay; the merge completion logic on the
> main thread will just keep this lazily compiled data rather than
> inserting compiled data from the newly deserialized object graph.
> C. SharedFunctionInfos can be cleared from the Script's weak array if
> they are no longer referenced. This is mostly okay, because any
> SharedFunctionInfo that is needed by the background merge is strongly
> referenced and therefore can't be cleared. The only problem arises if
> the top-level SharedFunctionInfo gets cleared, so the merge task must
> deliberately keep a reference to that one.
> D. SharedFunctionInfos can be created if they are needed due to lazy
> compilation of a parent function. This change is somewhat troublesome
> because it invalidates the background thread's work and requires a
> re-traversal on the main thread to update any pointers that should
> point to this lazily compiled SharedFunctionInfo.
>
> At a high level, this change implements three previously unimplemented
> functions in BackgroundDeserializeTask (in compiler.cc) and updates one:
>
> - BackgroundDeserializeTask::SourceTextAvailable, run on the main
> thread, checks whether there is a matching Script in the Isolate
> compilation cache which doesn't already have a top-level
> SharedFunctionInfo. If so, it saves that Script in a persistent
> handle.
> - BackgroundDeserializeTask::ShouldMergeWithExistingScript checks
> whether the persistent handle from the first step exists (a fast
> operation which can be called from any thread).
> - BackgroundDeserializeTask::MergeWithExistingScript, run on a
> background thread, performs step 3 of the merge described above and
> generates lists of persistent data describing how the main thread can
> complete the merge.
> - BackgroundDeserializeTask::Finish is updated to perform the merge
> steps 1 and 2 listed above, as well as a possible re-traversal of the
> graph if required due to newly created SharedFunctionInfos in the old
> Script.
>
> The merge logic has nothing to do with deserialization, and indeed I
> hope to reuse it for background compilation tasks as well, so it is all
> contained within a new class BackgroundMergeTask (in compiler.h,cc). It
> uses a second class, ForwardPointersVisitor (in compiler.cc) to perform
> the object visitation that updates pointers to SharedFunctionInfos.
>
> [0] https://docs.google.com/document/d/1UksB5Vm7TT1-f3S9W1dK_rP9jKn_ly0WVm_UDPpWuBw/edit
>
> Bug: v8:12808
> Change-Id: Id405869e9d5b106ca7afd9c4b08cb5813e6852c6
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3739232
> Reviewed-by: Leszek Swirski <leszeks@chromium.org>
> Commit-Queue: Seth Brenith <seth.brenith@microsoft.com>
> Cr-Commit-Position: refs/heads/main@{#81941}
Bug: v8:12808
Change-Id: Id2036dfa4eba8670cac899773d7a906825fa2c50
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3787266
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Seth Brenith <seth.brenith@microsoft.com>
Cr-Commit-Position: refs/heads/main@{#82045}
This reverts commit e895b7af73.
Reason for revert: TSAN failures: https://ci.chromium.org/ui/p/v8/builders/ci/V8%20Linux64%20TSAN%20-%20stress-incremental-marking/8468/overview
Original change's description:
> Background merging of deserialized scripts
>
> Recently, https://crrev.com/c/v8/v8/+/3681880 added new API functions
> with which an embedder could request that V8 merge newly deserialized
> script data into an existing Script from the Isolate's compilation
> cache. This change implements those new functions. This functionality is
> still disabled by default due to the flag
> merge_background_deserialized_script_with_compilation_cache.
>
> The goal of this new functionality is to reduce memory usage when
> multiple frames load the same script with a long delay between (long
> enough for the script to have been evicted from Blink's in-memory cache
> and for the top-level SharedFunctionInfo to be flushed). In that case,
> there are two Script objects for the same script: one which was found in
> the Isolate compilation cache (the "old" script), and one which was
> recently deserialized (the "new" script). The new script's object graph
> is essentially standalone: it may point to internalized strings and
> readonly objects such as the empty feedback metadata, but otherwise
> it is unconnected to the rest of the heap. The merging logic takes any
> useful data from the new script's object graph and attaches it into the
> old script's object graph, so that the new Script object and any other
> duplicated objects can be discarded. More specifically:
>
> 1. If the new Script has a SharedFunctionInfo for a particular function
> literal, and the old Script does not, then the old Script is updated
> to refer to the new SharedFunctionInfo.
> 2. If the new Script has a compiled SharedFunctionInfo for a particular
> function literal, and the old Script has an uncompiled
> SharedFunctionInfo, then the old SharedFunctionInfo is updated to
> point to the function_data and feedback_metadata from the new
> SharedFunctionInfo.
> 3. If any used object from the new object graph points to a
> SharedFunctionInfo, where the old object graph contains a matching
> SharedFunctionInfo for the same function literal, then that pointer
> is updated to point to the old SharedFunctionInfo.
>
> The document at [0] includes diagrams showing an example merge on a very
> small script.
>
> Steps 1 and 2 above are pretty simple, but step 3 requires walking a
> possibly large set of objects, so this new API lets the embedder run
> step 3 from a background thread. Steps 1 and 2 are performed later, on
> the main thread.
>
> The next important question is: in what ways can the old script's object
> graph be modified during the background execution of step 3, or during
> the time after step 3 but before steps 1 and 2?
>
> A. SharedFunctionInfos can go from compiled to uncompiled due to
> flushing. This is okay; the worst outcome is that the function would
> need to be compiled again later. Such a risk is already present,
> since V8 doesn't keep IsCompiledScopes for every compiled function in
> a background-deserialized script.
> B. SharedFunctionInfos can go from uncompiled to compiled due to lazy
> compilation. This is also okay; the merge completion logic on the
> main thread will just keep this lazily compiled data rather than
> inserting compiled data from the newly deserialized object graph.
> C. SharedFunctionInfos can be cleared from the Script's weak array if
> they are no longer referenced. This is mostly okay, because any
> SharedFunctionInfo that is needed by the background merge is strongly
> referenced and therefore can't be cleared. The only problem arises if
> the top-level SharedFunctionInfo gets cleared, so the merge task must
> deliberately keep a reference to that one.
> D. SharedFunctionInfos can be created if they are needed due to lazy
> compilation of a parent function. This change is somewhat troublesome
> because it invalidates the background thread's work and requires a
> re-traversal on the main thread to update any pointers that should
> point to this lazily compiled SharedFunctionInfo.
>
> At a high level, this change implements three previously unimplemented
> functions in BackgroundDeserializeTask (in compiler.cc) and updates one:
>
> - BackgroundDeserializeTask::SourceTextAvailable, run on the main
> thread, checks whether there is a matching Script in the Isolate
> compilation cache which doesn't already have a top-level
> SharedFunctionInfo. If so, it saves that Script in a persistent
> handle.
> - BackgroundDeserializeTask::ShouldMergeWithExistingScript checks
> whether the persistent handle from the first step exists (a fast
> operation which can be called from any thread).
> - BackgroundDeserializeTask::MergeWithExistingScript, run on a
> background thread, performs step 3 of the merge described above and
> generates lists of persistent data describing how the main thread can
> complete the merge.
> - BackgroundDeserializeTask::Finish is updated to perform the merge
> steps 1 and 2 listed above, as well as a possible re-traversal of the
> graph if required due to newly created SharedFunctionInfos in the old
> Script.
>
> The merge logic has nothing to do with deserialization, and indeed I
> hope to reuse it for background compilation tasks as well, so it is all
> contained within a new class BackgroundMergeTask (in compiler.h,cc). It
> uses a second class, ForwardPointersVisitor (in compiler.cc) to perform
> the object visitation that updates pointers to SharedFunctionInfos.
>
> [0] https://docs.google.com/document/d/1UksB5Vm7TT1-f3S9W1dK_rP9jKn_ly0WVm_UDPpWuBw/edit
>
> Bug: v8:12808
> Change-Id: Id405869e9d5b106ca7afd9c4b08cb5813e6852c6
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3739232
> Reviewed-by: Leszek Swirski <leszeks@chromium.org>
> Commit-Queue: Seth Brenith <seth.brenith@microsoft.com>
> Cr-Commit-Position: refs/heads/main@{#81941}
Bug: v8:12808
Change-Id: I82a080e6287828445293cb6b4b94a5e8f15eb8f3
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3787213
Auto-Submit: Deepti Gandluri <gdeepti@chromium.org>
Commit-Queue: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Owners-Override: Deepti Gandluri <gdeepti@chromium.org>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Cr-Commit-Position: refs/heads/main@{#81943}
Recently, https://crrev.com/c/v8/v8/+/3681880 added new API functions
with which an embedder could request that V8 merge newly deserialized
script data into an existing Script from the Isolate's compilation
cache. This change implements those new functions. This functionality is
still disabled by default due to the flag
merge_background_deserialized_script_with_compilation_cache.
The goal of this new functionality is to reduce memory usage when
multiple frames load the same script with a long delay between (long
enough for the script to have been evicted from Blink's in-memory cache
and for the top-level SharedFunctionInfo to be flushed). In that case,
there are two Script objects for the same script: one which was found in
the Isolate compilation cache (the "old" script), and one which was
recently deserialized (the "new" script). The new script's object graph
is essentially standalone: it may point to internalized strings and
readonly objects such as the empty feedback metadata, but otherwise
it is unconnected to the rest of the heap. The merging logic takes any
useful data from the new script's object graph and attaches it into the
old script's object graph, so that the new Script object and any other
duplicated objects can be discarded. More specifically:
1. If the new Script has a SharedFunctionInfo for a particular function
literal, and the old Script does not, then the old Script is updated
to refer to the new SharedFunctionInfo.
2. If the new Script has a compiled SharedFunctionInfo for a particular
function literal, and the old Script has an uncompiled
SharedFunctionInfo, then the old SharedFunctionInfo is updated to
point to the function_data and feedback_metadata from the new
SharedFunctionInfo.
3. If any used object from the new object graph points to a
SharedFunctionInfo, where the old object graph contains a matching
SharedFunctionInfo for the same function literal, then that pointer
is updated to point to the old SharedFunctionInfo.
The document at [0] includes diagrams showing an example merge on a very
small script.
Steps 1 and 2 above are pretty simple, but step 3 requires walking a
possibly large set of objects, so this new API lets the embedder run
step 3 from a background thread. Steps 1 and 2 are performed later, on
the main thread.
The next important question is: in what ways can the old script's object
graph be modified during the background execution of step 3, or during
the time after step 3 but before steps 1 and 2?
A. SharedFunctionInfos can go from compiled to uncompiled due to
flushing. This is okay; the worst outcome is that the function would
need to be compiled again later. Such a risk is already present,
since V8 doesn't keep IsCompiledScopes for every compiled function in
a background-deserialized script.
B. SharedFunctionInfos can go from uncompiled to compiled due to lazy
compilation. This is also okay; the merge completion logic on the
main thread will just keep this lazily compiled data rather than
inserting compiled data from the newly deserialized object graph.
C. SharedFunctionInfos can be cleared from the Script's weak array if
they are no longer referenced. This is mostly okay, because any
SharedFunctionInfo that is needed by the background merge is strongly
referenced and therefore can't be cleared. The only problem arises if
the top-level SharedFunctionInfo gets cleared, so the merge task must
deliberately keep a reference to that one.
D. SharedFunctionInfos can be created if they are needed due to lazy
compilation of a parent function. This change is somewhat troublesome
because it invalidates the background thread's work and requires a
re-traversal on the main thread to update any pointers that should
point to this lazily compiled SharedFunctionInfo.
At a high level, this change implements three previously unimplemented
functions in BackgroundDeserializeTask (in compiler.cc) and updates one:
- BackgroundDeserializeTask::SourceTextAvailable, run on the main
thread, checks whether there is a matching Script in the Isolate
compilation cache which doesn't already have a top-level
SharedFunctionInfo. If so, it saves that Script in a persistent
handle.
- BackgroundDeserializeTask::ShouldMergeWithExistingScript checks
whether the persistent handle from the first step exists (a fast
operation which can be called from any thread).
- BackgroundDeserializeTask::MergeWithExistingScript, run on a
background thread, performs step 3 of the merge described above and
generates lists of persistent data describing how the main thread can
complete the merge.
- BackgroundDeserializeTask::Finish is updated to perform the merge
steps 1 and 2 listed above, as well as a possible re-traversal of the
graph if required due to newly created SharedFunctionInfos in the old
Script.
The merge logic has nothing to do with deserialization, and indeed I
hope to reuse it for background compilation tasks as well, so it is all
contained within a new class BackgroundMergeTask (in compiler.h,cc). It
uses a second class, ForwardPointersVisitor (in compiler.cc) to perform
the object visitation that updates pointers to SharedFunctionInfos.
[0] https://docs.google.com/document/d/1UksB5Vm7TT1-f3S9W1dK_rP9jKn_ly0WVm_UDPpWuBw/edit
Bug: v8:12808
Change-Id: Id405869e9d5b106ca7afd9c4b08cb5813e6852c6
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3739232
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Seth Brenith <seth.brenith@microsoft.com>
Cr-Commit-Position: refs/heads/main@{#81941}
Adds Module::GetStalledTopLevelAwaitMessage() API which searches for
modules that have no pending async dependencies but have not yet
resolved. An embedder may call this API when they are about to exit
to check if TLA evaluation has stalled and provide a better error
message.
Change-Id: I3b88802f70cc84c973551f13d73ef3e3d06f4027
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2341765
Commit-Queue: Joyee Cheung <joyee@igalia.com>
Commit-Queue: Camillo Bruni <cbruni@chromium.org>
Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/main@{#81080}
Original CL got reverted, this time the failing test should be fixed.
Bug: v8:12578
Change-Id: Id2d8801f07742e8b00884fefec8200e4270f4250
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3657434
Commit-Queue: Dominik Inführ <dinfuehr@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/main@{#80668}
Due to the consistent overhead of snapshot checksum verification
we ideally want to avoid it all-together. However there are still enough
devices out there that suffer from corrupted snapshots that might
cause hard to debug heap corruptions.
This CL exposes the calculated (dummy value for now) and the expected
snapshot checksum as a crash key, so it can be easily consulted during
investigation.
Note: The calculated crash key contains 0x0 for now as a dummy value. We
will come up with a strategy later-on to limit the overhead of
calculating the checksum.
Bug: v8:12195
Change-Id: I6da6d74c035cb6f9b0edae212a36e6c41c048a5b
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3605813
Reviewed-by: Jakob Linke <jgruber@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/main@{#80325}
- Add RunJSNoChecked to run the script which possibly throws.
- Add CompileRun to run the script outside TEST_F, e.g., in
FunctionTemplate and helpers etc.
Bug: v8:12781
Change-Id: Ibab2e19cf1f7c76f7a81a90fc5894e7e6bfb7cdf
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3586770
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: 王澳 <wangao.james@bytedance.com>
Cr-Commit-Position: refs/heads/main@{#80025}
Change the unittest runner to no longer uncondtionally set up a default
platform in the "environment", but to instead make platform set-up part
of the "mixin" framework for test fixtures.
Requires modifying some tests that expect the platform to be available,
and all flag implications resolved, before the mixin constructors run.
We still keep the environment for setting up the process for cppgc. This
process setup can only be done once per process, so it can no longer use
the platform -- that's ok though, the page allocator used by cppgc's
process initialisation doesn't have to be the same as the platform's so
we can just pass in a separate new one.
Change-Id: Ic8ccf39722e8212962c5bba87350c4b304388a7c
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3571886
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Auto-Submit: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/main@{#79820}
This is a reland of d1b27019d3
Fixes include:
Adding missing file to bazel build
Forward-declaring classing before friend-classing them to fix win/gcc
Add missing v8-isolate.h include for vtune builds
Original change's description:
> [include] Split out v8.h
>
> This moves every single class/function out of include/v8.h into a
> separate header in include/, which v8.h then includes so that
> externally nothing appears to have changed.
>
> Every include of v8.h from inside v8 has been changed to a more
> fine-grained include.
>
> Previously inline functions defined at the bottom of v8.h would call
> private non-inline functions in the V8 class. Since that class is now
> in v8-initialization.h and is rarely included (as that would create
> dependency cycles), this is not possible and so those methods have been
> moved out of the V8 class into the namespace v8::api_internal.
>
> None of the previous files in include/ now #include v8.h, which means
> if embedders were relying on this transitive dependency then it will
> give compile failures.
>
> v8-inspector.h does depend on v8-scripts.h for the time being to ensure
> that Chrome continue to compile but that change will be reverted once
> those transitive #includes in chrome are changed to include it directly.
>
> Full design:
> https://docs.google.com/document/d/1rTD--I8hCAr-Rho1WTumZzFKaDpEp0IJ8ejZtk4nJdA/edit?usp=sharing
>
> Bug: v8:11965
> Change-Id: I53b84b29581632710edc80eb11f819c2097a2877
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3097448
> Reviewed-by: Yang Guo <yangguo@chromium.org>
> Reviewed-by: Camillo Bruni <cbruni@chromium.org>
> Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
> Reviewed-by: Leszek Swirski <leszeks@chromium.org>
> Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
> Commit-Queue: Dan Elphick <delphick@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#76424}
Cq-Include-Trybots: luci.v8.try:v8_linux_vtunejit
Bug: v8:11965
Change-Id: I99f5d3a73bf8fe25b650adfaf9567dc4e44a09e6
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3113629
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Reviewed-by: Simon Zünd <szuend@chromium.org>
Commit-Queue: Dan Elphick <delphick@chromium.org>
Cr-Commit-Position: refs/heads/main@{#76460}
This reverts commit d1b27019d3.
Reason for revert: Broke vtune build, tsan build and possibly others
Original change's description:
> [include] Split out v8.h
>
> This moves every single class/function out of include/v8.h into a
> separate header in include/, which v8.h then includes so that
> externally nothing appears to have changed.
>
> Every include of v8.h from inside v8 has been changed to a more
> fine-grained include.
>
> Previously inline functions defined at the bottom of v8.h would call
> private non-inline functions in the V8 class. Since that class is now
> in v8-initialization.h and is rarely included (as that would create
> dependency cycles), this is not possible and so those methods have been
> moved out of the V8 class into the namespace v8::api_internal.
>
> None of the previous files in include/ now #include v8.h, which means
> if embedders were relying on this transitive dependency then it will
> give compile failures.
>
> v8-inspector.h does depend on v8-scripts.h for the time being to ensure
> that Chrome continue to compile but that change will be reverted once
> those transitive #includes in chrome are changed to include it directly.
>
> Full design:
> https://docs.google.com/document/d/1rTD--I8hCAr-Rho1WTumZzFKaDpEp0IJ8ejZtk4nJdA/edit?usp=sharing
>
> Bug: v8:11965
> Change-Id: I53b84b29581632710edc80eb11f819c2097a2877
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3097448
> Reviewed-by: Yang Guo <yangguo@chromium.org>
> Reviewed-by: Camillo Bruni <cbruni@chromium.org>
> Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
> Reviewed-by: Leszek Swirski <leszeks@chromium.org>
> Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
> Commit-Queue: Dan Elphick <delphick@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#76424}
Bug: v8:11965
Change-Id: Id57313ae992e720c8b19abc975cd69729e1344aa
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3113627
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Owners-Override: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/main@{#76428}
This moves every single class/function out of include/v8.h into a
separate header in include/, which v8.h then includes so that
externally nothing appears to have changed.
Every include of v8.h from inside v8 has been changed to a more
fine-grained include.
Previously inline functions defined at the bottom of v8.h would call
private non-inline functions in the V8 class. Since that class is now
in v8-initialization.h and is rarely included (as that would create
dependency cycles), this is not possible and so those methods have been
moved out of the V8 class into the namespace v8::api_internal.
None of the previous files in include/ now #include v8.h, which means
if embedders were relying on this transitive dependency then it will
give compile failures.
v8-inspector.h does depend on v8-scripts.h for the time being to ensure
that Chrome continue to compile but that change will be reverted once
those transitive #includes in chrome are changed to include it directly.
Full design:
https://docs.google.com/document/d/1rTD--I8hCAr-Rho1WTumZzFKaDpEp0IJ8ejZtk4nJdA/edit?usp=sharing
Bug: v8:11965
Change-Id: I53b84b29581632710edc80eb11f819c2097a2877
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3097448
Reviewed-by: Yang Guo <yangguo@chromium.org>
Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Dan Elphick <delphick@chromium.org>
Cr-Commit-Position: refs/heads/main@{#76424}
To consume a code cache off-thread
1. The embedder creates a CachedData object wrapping the data blob.
2. The embedder calls ScriptCompiler::StartConsumingCodeCache with the
CachedData, and receives a ScriptCompiler::CodeCacheConsumeTask
which takes ownership of the CachedData.
3. The embedder calls ScriptCompiler::CodeCacheConsumeTask::Run
on a different thread.
4. Once this completes, the embedded passes the completed task as an
optional argument into Source constructor, and calls Compile as
before.
This is roughly similar to how streaming compilation works, with the
QoL improvement that Source owns the CodeCacheConsumeTask and therefore
we can reuse the same Compile method and do the off-thread finalization
behind the scenes inside Compile.
On the v8::internal side, ScriptCompiler::CodeCacheConsumeTask wraps a
v8::internal::BackgroundDeserializeTask, which has a Run and a Finish
method. The Run creates a LocalIsolate (again, similar to
BackgroundCompileTask), calls some helpers on CodeSerializer, and stores
the pre-finalization result in a OffThreadDeserializeData structure.
This stores Persistent Handles to the off-thread initialized SFI and
a vector of Scripts needing fixing up, and it owns the PersistentHandles
object which owns those Handles. Finally, the Finish method consumes
this OffThreadDeserializeData structure, fixes up Scripts, moves the
SFI Handle into the caller HandleScope, and that's it.
Since we don't yet have the source at off-thread deserialization time,
the various code cache sanity checks are done without the source hash
when deserializing, and the Finish method re-does them now that the
source is available.
Bug: chromium:1075999
Change-Id: If1faf35ba3ef840fa4e735581d0b29c96c1d5fc8
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3067322
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Omer Katz <omerkatz@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#76155}
This reverts commit a5fd60e15a.
Reason for revert: As per crbug/1213374 this is not applied consistently. E.g. wrapping object into an array will bypass access checks. With the crrev/c/3041424 however, only accessible properties are shown in console, so logging a restricted object is no longer unsafe.
Original change's description:
> Calls to {console} require an access check for the provided arguments
>
> This CL adds an access check for the arguments to all calls to
> {console} like {console.log}. This is needed since the DevTools
> protocol notificiation event does not contain the context in which
> the {console.log} call occurred. Only the context of the argument.
> When DevTools then reads properties for the preview of the argument,
> it uses arguments context, instead of the calling context, potentially
> leaking objects/exceptions into the calling context.
>
> Bug: chromium:987502, chromium:986393
> Change-Id: I6f7682f7bee94a28ac61994bad259bd003511c39
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1741664
> Commit-Queue: Simon Zünd <szuend@chromium.org>
> Reviewed-by: Yang Guo <yangguo@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#63122}
Bug: chromium:987502, chromium:986393, chromium:1213374
Change-Id: I92a8bb7663ff97de8831ddeb2c8560fb9fa1c12e
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3046189
Reviewed-by: Simon Zünd <szuend@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Commit-Queue: Danil Somsikov <dsv@chromium.org>
Cr-Commit-Position: refs/heads/master@{#75881}
This is a reland of 80f5dfda01. A condition
in pipeline.cc was inverted, which lead to a CSA verifier error.
Original change's description:
> [no-wasm] Exclude src/wasm from compilation
>
> This is the biggest chunk, including
> - all of src/wasm,
> - torque file for wasm objects,
> - torque file for wasm builtins,
> - wasm builtins,
> - wasm runtime functions,
> - int64 lowering,
> - simd scala lowering,
> - WasmGraphBuilder (TF graph construction for wasm),
> - wasm frame types,
> - wasm interrupts,
> - the JSWasmCall opcode,
> - wasm backing store allocation.
>
> Those components are all recursively entangled, so I found no way to
> split this change up further.
>
> Some includes that were recursively included by wasm headers needed to
> be added explicitly now.
>
> backing-store-unittest.cc is renamed to wasm-backing-store-unittest.cc
> because it only tests wasm backing stores. This file is excluded from
> no-wasm builds then.
>
> R=jkummerow@chromium.org, jgruber@chromium.org, mlippautz@chromium.org, petermarshall@chromium.org
>
> Bug: v8:11238
> Change-Id: I7558f2d12d2dd6c65128c4de7b79173668c80b2b
> Cq-Include-Trybots: luci.v8.try:v8_linux64_no_wasm_compile_rel
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2742955
> Commit-Queue: Clemens Backes <clemensb@chromium.org>
> Reviewed-by: Peter Marshall <petermarshall@chromium.org>
> Reviewed-by: Toon Verwaest <verwaest@chromium.org>
> Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
> Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
> Reviewed-by: Jakob Gruber <jgruber@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#73344}
TBR=jgruber@chromium.org
Bug: v8:11238
Change-Id: I20bd2847a59c68738b5a336cd42582b7b1499585
Cq-Include-Trybots: luci.v8.try:v8_linux64_no_wasm_compile_rel
Cq-Include-Trybots: luci.v8.try:v8_linux_verify_csa_rel_ng
Cq-Include-Trybots: luci.v8.try:v8_linux64_verify_csa_rel_ng
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2752867
Reviewed-by: Clemens Backes <clemensb@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#73348}
This reverts commit 80f5dfda01.
Reason for revert: Fails CSA verification: https://ci.chromium.org/ui/p/v8/builders/ci/V8%20Linux%20-%20verify%20csa/21766/overview
Original change's description:
> [no-wasm] Exclude src/wasm from compilation
>
> This is the biggest chunk, including
> - all of src/wasm,
> - torque file for wasm objects,
> - torque file for wasm builtins,
> - wasm builtins,
> - wasm runtime functions,
> - int64 lowering,
> - simd scala lowering,
> - WasmGraphBuilder (TF graph construction for wasm),
> - wasm frame types,
> - wasm interrupts,
> - the JSWasmCall opcode,
> - wasm backing store allocation.
>
> Those components are all recursively entangled, so I found no way to
> split this change up further.
>
> Some includes that were recursively included by wasm headers needed to
> be added explicitly now.
>
> backing-store-unittest.cc is renamed to wasm-backing-store-unittest.cc
> because it only tests wasm backing stores. This file is excluded from
> no-wasm builds then.
>
> R=jkummerow@chromium.org, jgruber@chromium.org, mlippautz@chromium.org, petermarshall@chromium.org
>
> Bug: v8:11238
> Change-Id: I7558f2d12d2dd6c65128c4de7b79173668c80b2b
> Cq-Include-Trybots: luci.v8.try:v8_linux64_no_wasm_compile_rel
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2742955
> Commit-Queue: Clemens Backes <clemensb@chromium.org>
> Reviewed-by: Peter Marshall <petermarshall@chromium.org>
> Reviewed-by: Toon Verwaest <verwaest@chromium.org>
> Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
> Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
> Reviewed-by: Jakob Gruber <jgruber@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#73344}
Bug: v8:11238
Change-Id: I93672002c1faa36bb0bb5b4a9cc2032ee2ccd814
Cq-Include-Trybots: luci.v8.try:v8_linux64_no_wasm_compile_rel
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2752866
Auto-Submit: Clemens Backes <clemensb@chromium.org>
Commit-Queue: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Cr-Commit-Position: refs/heads/master@{#73346}
This is the biggest chunk, including
- all of src/wasm,
- torque file for wasm objects,
- torque file for wasm builtins,
- wasm builtins,
- wasm runtime functions,
- int64 lowering,
- simd scala lowering,
- WasmGraphBuilder (TF graph construction for wasm),
- wasm frame types,
- wasm interrupts,
- the JSWasmCall opcode,
- wasm backing store allocation.
Those components are all recursively entangled, so I found no way to
split this change up further.
Some includes that were recursively included by wasm headers needed to
be added explicitly now.
backing-store-unittest.cc is renamed to wasm-backing-store-unittest.cc
because it only tests wasm backing stores. This file is excluded from
no-wasm builds then.
R=jkummerow@chromium.org, jgruber@chromium.org, mlippautz@chromium.org, petermarshall@chromium.org
Bug: v8:11238
Change-Id: I7558f2d12d2dd6c65128c4de7b79173668c80b2b
Cq-Include-Trybots: luci.v8.try:v8_linux64_no_wasm_compile_rel
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2742955
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Reviewed-by: Peter Marshall <petermarshall@chromium.org>
Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#73344}
The current API returns a Handle<NativeContext> which can be
optionally null and all the users of this API never actually
checked for this null value.
Previously, this wasn't a problem as all the possible JSObjects
that were user visible would return a valid NativeContext but now
there are wasm objects that don't have a valid constructor so don't
have a NativeContext.
Bug: v8:11451, chromium:1166077
Change-Id: I4fd5edf8f1a750e6f0abb931fd41358e5ae4dfcf
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2692695
Commit-Queue: Sathya Gunasekaran <gsathya@chromium.org>
Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#72769}
Scopes in V8 are used to guarantee one or more properties during its
lifetimes. If a scope is not named e.g MyClassScope(args) instead of
MyClassScope scope(args) it will get created and automatically destroyed
and therefore, being useless as a scope. This CL would produce a
compiling warning when that happens to ward off this developer error.
Follow-up to ccrev.com/2552415 in which it was introduced and
implemented for Guard classes.
Change-Id: Ifa0fb89cc3d9bdcdee0fd8150a2618af5ef45cbf
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2555001
Commit-Queue: Santiago Aboy Solanes <solanes@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#71425}
This is a reland of 29c1eab92e
Original change's description:
> [builtins] Clean up the use of class_name / ES5 [[Class]]
>
> Before ES2015, the ES spec had a [[Class]] internal slot for all
> objects, which Object.prototype.toString() would use to figure the
> returned string. Post-ES2015, the [[Class]] slot was removed in spec for
> all objects, with the @@toStringTag well-known symbol the proper way to
> change Object.prototype.toString() output.
>
> At the time, spec-identical handling without the use of [[Class]] was
> implemented in V8 for all objects other than API objects, where issues
> with the Web IDL spec [1] prevented Blink, and hence V8, to totally
> migrate to @@toStringTag. However, since 2016 [2] Blink has been setting
> @@toStringTag on API class prototypes to manage the
> Object.prototype.toString() output, so the legacy [[Class]] handling in
> V8 has not been necessary for the past couple of years.
>
> This CL removes the remaining legacy [[Class]] handling in
> Object.prototype.toString(), JSReceiver::class_name(), and
> GetConstructorName(). However, it does not remove the class_name field
> in FunctionTemplateInfo, as it is still used for the `name` property of
> created functions.
>
> This CL also cleans up other places in the codebase that still reference
> [[Class]].
>
> This change should have minimal impact on web-compatibility. For the
> change to be observable, a script must do one of the following:
>
> 1. delete APIConstructor.prototype[Symbol.toStringTag];
> 2. Object.setPrototypeOf(apiObject, somethingElse);
>
> Before this CL, these changes will not change the apiObject.toString()
> output. But after this CL, they will make apiObject.toString() show
> "[object Object]" (in the first case) or the @@toStringTag of the other
> prototype (in the latter case).
>
> However, both are deemed unlikely. @@toStringTag is not well-known
> feature of JavaScript, nor does it get tampered much on API
> constructors. In the second case, setting the prototype of an API object
> would effectly render the object useless, as all its methods (including
> property getters/setters) would no longer be accessible.
>
> Currently, @@toStringTag-based API object branding is not yet
> implemented by other browsers. This V8 bug in particular has been an
> impediment to standardizing toString behavior. Fixing this bug will
> unblock [3] and lead to a better Web IDL spec, and better toString()
> compatibility for all.
>
> [1]: https://www.w3.org/Bugs/Public/show_bug.cgi?id=28244
> [2]: https://crrev.com/909c0d7d5a53c8526ded351683c65ea7d17531d4
> [3]: https://github.com/heycam/webidl/pull/357
>
> Bug: chromium:793406
> Cq-Include-Trybots: luci.chromium.try:linux-rel
> Change-Id: Iceded24e37afa2646ec385d5018909f55b177f93
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2146996
> Commit-Queue: Timothy Gu <timothygu@chromium.org>
> Reviewed-by: Toon Verwaest <verwaest@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#67327}
Bug: chromium:793406
Change-Id: Ia5d97bd4e1c44cadc6f18a17ffc9d06b038cf8f1
Cq-Include-Trybots: luci.chromium.try:linux-rel
Cq-Include-Trybots: luci.v8.try:v8_linux_blink_rel
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2163881
Auto-Submit: Timothy Gu <timothygu@chromium.org>
Commit-Queue: Toon Verwaest <verwaest@chromium.org>
Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Cr-Commit-Position: refs/heads/master@{#67361}
