This reverts commit aa541f1c9c.
Reason for revert: Reverting due to large regressions for motionmark on M1.
Original change's description:
> [turbofan][arm64] Emit Lsl for Int32MulWithOverflow when possible
>
> Int32MulWithOverflow on arm64 uses a cmp to set flags rather than
> the multiply instruction itself, thus we can use a left shift when
> the multiplication is by a power of two.
>
> This provides 0.15% for Speedometer2 on a Neoverse-N1 machine,
> with React being improved by 0.45%.
>
> Change-Id: Ic8db42ecc7cb14cf1ac7bbbeab0e9d8359104351
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3829472
> Commit-Queue: George Wort <george.wort@arm.com>
> Reviewed-by: Nico Hartmann <nicohartmann@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#82499}
Change-Id: I896530a53fbdf6d397922124abddda4140144448
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3854222
Reviewed-by: Nico Hartmann <nicohartmann@chromium.org>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Commit-Queue: George Wort <george.wort@arm.com>
Cr-Commit-Position: refs/heads/main@{#82696}
This CL adds a soft limit (via AllocationObserver) to run
incremental marking for MinorMC.
Once the soft limit is triggered, roots are marked.
This a stepping stone for concurrent marking
(YoungGenerationConcurrentMarkingVisitor, go/YGCMV) integration.
Bug: v8:13012
Change-Id: I5bc9aeb80511159561845deb494023ade3fb7365
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3824339
Reviewed-by: Dominik Inführ <dinfuehr@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Leon Bettscheider <bettscheider@google.com>
Cr-Commit-Position: refs/heads/main@{#82695}
Concurrent markers could add work into the worklist before the CHECK.
Bug: v8:12775, v8:13223
Change-Id: I8ac252b0fec8e5acbcfec56dad04830e596c709d
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3854496
Commit-Queue: Dominik Inführ <dinfuehr@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/main@{#82690}
This is a reland of commit abd0adf106
Original change's description:
> [compiler] Make ReduceWord32EqualForConstantRhs work for Word64Equal
>
> Adds reduction case in MachineOperatorReducer for when the left-hand side of a
> Word64Equals is based on a 64-bit shift-and-mask operation, as is the case
> when Torque accesses 64-bit bitfields.
>
> This improves Speedometer2 by 0.15% on a Neoverse-N1 machine, with
> React-Redux being improved by 0.4%.
>
> Change-Id: Icd0451c00c1b25f7d370e81bddcfd668a5b2523c
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3834027
> Commit-Queue: George Wort <george.wort@arm.com>
> Reviewed-by: Nico Hartmann <nicohartmann@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#82593}
Change-Id: I62393c062b2c785a5dfa3500b80fe44ec08f6f21
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3841569
Commit-Queue: George Wort <george.wort@arm.com>
Reviewed-by: Nico Hartmann <nicohartmann@chromium.org>
Cr-Commit-Position: refs/heads/main@{#82684}
Users should rely on CppHeap which is the only supported way of using
v8::TracedReference in going forward.
Bug: v8:13207
Change-Id: Idd03f458167c74b06f285bb568e5c77ad46003fe
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3849037
Reviewed-by: Dominik Inführ <dinfuehr@chromium.org>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Simon Zünd <szuend@chromium.org>
Cr-Commit-Position: refs/heads/main@{#82681}
... 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}
IsRunning() and IsMarking() are now equivalent. So IsRunning() can be
removed in favor of IsMarking().
IsComplete() is also renamed to IsMarkingComplete().
Bug: v8:12775
Change-Id: Ife88be4d674af055590ba5178ec1e410f8fa89d9
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3849833
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Dominik Inführ <dinfuehr@chromium.org>
Cr-Commit-Position: refs/heads/main@{#82665}
Generate Tbz/Tbnz instead of (tst;bcc),
and Cbz/Cbnz instead of (cmp;bcc), where possible.
This improves Speedometer2 by 0.22% on a Neoverse-N1 machine.
Change-Id: Ie86bae7189a7a4bd4975f946e7413225c9023316
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3833816
Commit-Queue: Martyn Capewell <martyn.capewell@arm.com>
Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/main@{#82657}
Use the `fuchsia_component` and `fuchsia_package` GN templates from the
Fuchsia SDK to package the `v8_unittests` test for Fuchsia. Give the
`v8_unittests` their own dedicated `.cmx` file, instead of depending on
`v8.cmx`.
Bug: chromium:1256503
Change-Id: I22788359bed18eb643e288ee1a0c92c24c0dc3e1
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3819644
Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Reviewed-by: Wez <wez@chromium.org>
Commit-Queue: Derek Gonyeo <dgonyeo@google.com>
Cr-Commit-Position: refs/heads/main@{#82656}
- Swap() was not necessary as all uses merely required Merge()
- Remove unused empty Local ctor
- Use refrence for backref as it's always supposed to be non-null
Bug: v8:13193
Change-Id: Ide0a0de15185a67d028890371ae30528fd55a058
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3846863
Reviewed-by: Dominik Inführ <dinfuehr@chromium.org>
Reviewed-by: Anton Bikineev <bikineev@chromium.org>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/main@{#82648}
This change adds support for new table element types besides the
existing support for func and extern.
The newly supported types are the generic types of the 'any' subtype
hierarchy: any, eq, data and array.
All these table types are also usable and accessible via JavaScript,
causing implicit internalization and externalization of the elements
on Table::get() and Table::set().
Bug: v8:7748
Change-Id: Ie85d8f5e1d70471360dd2fb8a39cd38efaac2c22
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3838729
Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Matthias Liedtke <mliedtke@chromium.org>
Cr-Commit-Position: refs/heads/main@{#82643}
We found there are redundant load context operations in
some bytecode array.
like this:
LdaImmutableCurrentContextSlot [1]
Star0
...... (don’t edit accumulator)
LdaImmutableCurrentContextSlot [1]
Star1
Add r1
In that case, we could modify this bytecode array as:
LdaImmutableCurrentContextSlot [1]
Star0
...... (don’t edit accumulator)
Add r0
This CL will elide these redundant bytecodes
(LdaImmutableCurrentContextSlot and Star1), because there is no
side effect for loading context, and this context slot is immutable.
Change-Id: Ia26f4b934d3bd1d48c50c0c4699ba7942939991c
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3816221
Reviewed-by: Shu-yu Guo <syg@chromium.org>
Commit-Queue: Shu-yu Guo <syg@chromium.org>
Cr-Commit-Position: refs/heads/main@{#82641}
Per-context mode marking segregates worklists per context. Upon doing
so, Worklist::Local's move ctor was invoked which cleared the back
pointer to worklist. This break switching to that context which
happens in rare secnarios.
Rework Local marking worklists avoiding the move ctor which is also
removed.
Bug: chromium:1355545
Change-Id: If0e8c7f08df564b2a1e27e4a3fc5a6a40e46ee46
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3845630
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Dominik Inführ <dinfuehr@chromium.org>
Cr-Commit-Position: refs/heads/main@{#82636}
This changeset include:
1. [prepare for migrate] move `cctest/compiler/value-helper.h`,
`cctest/compiler/c-signature.h`, and `cctest/compiler/call-tester.h` to
`test/common` directory because both `test-codegen` and a lot of cctest file
include it.
2. [prepare for migrate] separate the tester helper part of `test-codegen`
into a new `codegen-tester` file.
3. finally, migrate test-codegen.cc to `codegen-unittest.cc`
Bug: v8:12781
Change-Id: Ia2f52c1d3b6b62501066dc1c4308a2c09d699e92
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3831146
Reviewed-by: Clemens Backes <clemensb@chromium.org>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/main@{#82630}
This reverts commit abd0adf106.
Reason for revert: Test times out on Win64
https://ci.chromium.org/ui/p/v8/builders/ci/V8%20Win64%20-%20msvc/23024/overview
Original change's description:
> [compiler] Make ReduceWord32EqualForConstantRhs work for Word64Equal
>
> Adds reduction case in MachineOperatorReducer for when the left-hand side of a
> Word64Equals is based on a 64-bit shift-and-mask operation, as is the case
> when Torque accesses 64-bit bitfields.
>
> This improves Speedometer2 by 0.15% on a Neoverse-N1 machine, with
> React-Redux being improved by 0.4%.
>
> Change-Id: Icd0451c00c1b25f7d370e81bddcfd668a5b2523c
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3834027
> Commit-Queue: George Wort <george.wort@arm.com>
> Reviewed-by: Nico Hartmann <nicohartmann@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#82593}
Change-Id: I26515348a3d8de58445ecddc0486d9fcc2711cec
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3839048
Commit-Queue: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Auto-Submit: Shu-yu Guo <syg@chromium.org>
Owners-Override: Shu-yu Guo <syg@chromium.org>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Cr-Commit-Position: refs/heads/main@{#82603}
Currently there is nothing ensuring the internal VM state of shared
objects are in a coherent state and visible to other threads when the
shared object is published.
This CL adds a store-store memory barrier when returning from Factory methods that allocate shared JSObjects that are exposed to user JS code. For primitives, there is an additional store-store memory barrier in the shared value barrier.
Bug: v8:12547
Change-Id: I4833c7ebf02cc352da9b006d2732669d6d043172
Cq-Include-Trybots: luci.v8.try:v8_linux64_tsan_isolates_rel_ng,v8_linux64_tsan_rel_ng
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3819041
Commit-Queue: Shu-yu Guo <syg@chromium.org>
Reviewed-by: Dominik Inführ <dinfuehr@chromium.org>
Cr-Commit-Position: refs/heads/main@{#82596}
Adds reduction case in MachineOperatorReducer for when the left-hand side of a
Word64Equals is based on a 64-bit shift-and-mask operation, as is the case
when Torque accesses 64-bit bitfields.
This improves Speedometer2 by 0.15% on a Neoverse-N1 machine, with
React-Redux being improved by 0.4%.
Change-Id: Icd0451c00c1b25f7d370e81bddcfd668a5b2523c
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3834027
Commit-Queue: George Wort <george.wort@arm.com>
Reviewed-by: Nico Hartmann <nicohartmann@chromium.org>
Cr-Commit-Position: refs/heads/main@{#82593}
NormalPageMemoryRegion is a span of 10 pages, all of which must belong
to the same space. This requirement imposes a fragmentation issue for virtual space, which is not ideal for the current 2GB cage
configuration.
The CL fixes this by mixing pages of different spaces inside the same
NormalPageMemoryRegion. With cage it's actually not necessary anymore
to have NormalPageMemoryRegion, but we keep it to allow the code to be
uniform for cage/non-cage configurations.
There is no type confusion across spaces, since pages (even empty) are
never shared between spaces. In addition, the shared cage puts an
additional memory constraint on the GC. So, there is no security benefit
in having NormalPageMemoryRegion assigned to a single space.
Savings in reserved address space:
cnn:2021: 14%
facebook_infinite_scroll:2018: 23%
Bug: chromium:1325007, chromium:1352649
Change-Id: I7b49032d581dd56feb8633734a1f37803e9526c6
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3840749
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Anton Bikineev <bikineev@chromium.org>
Cr-Commit-Position: refs/heads/main@{#82584}
Traced nodes were allocated black, even outside of GCs. Nodes would
always survive one GC, while the objects pointed to could die.
This CL removes black allocation and relies on proper write barriers
(that are anyways in place) to mark the nodes and their objects. This
also means that marked nodes should always point to live objects which
is now verified in the atomic pause.
Bug: v8:13141
Change-Id: Ie5cdc92d8fe5f57865d02b71d3fae9425ae532fa
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3820070
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Dominik Inführ <dinfuehr@chromium.org>
Cr-Commit-Position: refs/heads/main@{#82559}
Introducing IncrementalMarking::AdvanceForTesting as last bottleneck
for driving incremental marking in addition to AdvanceFromTask
and AdvanceOnAllocation.
Now that we have those 3 bottlenecks, Step() and AdvanceWithDeadline()
can become private methods in IncrementalMarking. We also don't need
the StepResult return value in Step() anymore, which allows us to
remove CombineStepResult.
Bug: v8:12775
Change-Id: I702714439ef7ea4b9abf2156387503d4d00a7a48
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3823131
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Dominik Inführ <dinfuehr@chromium.org>
Cr-Commit-Position: refs/heads/main@{#82552}
This is a reland of commit ee89a26977
Original change's description:
> [wasm-gc] Add extern.externalize
>
> This adds `extern.externalize(ref null any): ref null extern` to wasm
> which packs wasm objects into JS objects if the js-interop flag is not set.
> This is the counterpart to extern.internalize introduced in
> 50ec8a11f2.
>
> Bug: v8:7748
> Change-Id: I67b8fe6d70b9f526ff6c43b0a4d7861c7ff5dad0
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3825879
> Reviewed-by: Nico Hartmann <nicohartmann@chromium.org>
> Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
> Commit-Queue: Matthias Liedtke <mliedtke@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#82492}
Bug: v8:7748
Change-Id: Ie13cfd6464006dcadc2a53f2dbf77f76ab185504
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3829940
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Reviewed-by: Nico Hartmann <nicohartmann@chromium.org>
Auto-Submit: Matthias Liedtke <mliedtke@chromium.org>
Commit-Queue: Nico Hartmann <nicohartmann@chromium.org>
Cr-Commit-Position: refs/heads/main@{#82551}
- Move InnerPointerToCodeCache to using internal callbacks.
- Refactor internal and external callbacks to use a unified interface.
Bug: v8:13184
Change-Id: If0006d324b0433f5d6bbf00b6d0fc1a2589227bc
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3834583
Reviewed-by: Hannes Payer <hpayer@chromium.org>
Reviewed-by: Dominik Inführ <dinfuehr@chromium.org>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/main@{#82515}
Int32MulWithOverflow on arm64 uses a cmp to set flags rather than
the multiply instruction itself, thus we can use a left shift when
the multiplication is by a power of two.
This provides 0.15% for Speedometer2 on a Neoverse-N1 machine,
with React being improved by 0.45%.
Change-Id: Ic8db42ecc7cb14cf1ac7bbbeab0e9d8359104351
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3829472
Commit-Queue: George Wort <george.wort@arm.com>
Reviewed-by: Nico Hartmann <nicohartmann@chromium.org>
Cr-Commit-Position: refs/heads/main@{#82499}
This is a reland of commit a19316d9d7
- Revert malloc_usable_size() changes temporarily to land them in
isolation.
- Add cosmetics from https://crrev.com/c/3827876
Original change's description:
> [heap] Rework Worklist base type
>
> Worklist uses a singly-linked list of segments to hold entries.
> Segment size was based on a compile-time constant but already stored
> in the segment itself.
>
> Rework the segments to query `malloc_usable_size()` on allocation and
> adjust the capacity properly. For PartitionAlloc, it turns out that
> there's ~20% more capacity available for the 64-element segments.
>
> This slows down actual allocation of the segments with the upside of
> improving utilization and requiring 20% less segments.
>
> Change-Id: Ib8595c3fb9fb75b02e4022f6c525bb59a2df7ab7
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3826047
> Commit-Queue: Anton Bikineev <bikineev@chromium.org>
> Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
> Reviewed-by: Anton Bikineev <bikineev@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#82432}
Change-Id: Ic8c5257cfe3c347b11eea5c513ca7f62e09f637f
Bug: v8:13193
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3829475
Reviewed-by: Anton Bikineev <bikineev@chromium.org>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/main@{#82493}
This adds `extern.externalize(ref null any): ref null extern` to wasm
which packs wasm objects into JS objects if the js-interop flag is not set.
This is the counterpart to extern.internalize introduced in
50ec8a11f2.
Bug: v8:7748
Change-Id: I67b8fe6d70b9f526ff6c43b0a4d7861c7ff5dad0
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3825879
Reviewed-by: Nico Hartmann <nicohartmann@chromium.org>
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Matthias Liedtke <mliedtke@chromium.org>
Cr-Commit-Position: refs/heads/main@{#82492}
When freezing flags, not only remember this in a global variable, but
also actually memory-protect the memory that holds the flag values.
R=cbruni@chromium.org
CC=sroettger@chromium.org
Bug: v8:12887
Cq-Include-Trybots: luci.v8.try:v8_linux_blink_rel
Change-Id: I2ae638790d1f08f4bcc1b7e6cb5970e4e7463aad
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3811286
Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/main@{#82478}
Make sure there is no background GC when setting flags.
Bug: v8:12612, v8:13185
Change-Id: I0a2d4796abe265defa00d86f826003eb048e5bf1
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3829482
Auto-Submit: Omer Katz <omerkatz@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/main@{#82474}
This CL builds upon https://crrev.com/c/3284887 (and partly reverts it).
Class literals are a bit iffy when it comes to source position and
debugging. Mainly the debugger assumes the following invariant:
When we are paused inside a class scope, then we expect the class's
BlockContext to be pushed already. On the other hand, when we are
paused outside a class scope in a function, we don't expect to find
the class's BlockContext.
The problem is that there are cases where we can either pause
"inside" or "outside" the class scope. E.g.:
* `var x = class {};` will break on `class` which is inside
the class scope, so we expect the BlockContext to be pushed
* `new class x {};` will break on `new` which is outside the
class scope, so we expect the BlockContext to not be pushed
yet.
The issue with the fix in https://crrev.com/c/3284887 is that it
adjusted the break position for the bytecode of class literals to
ALWAYS be after the BlockContext is pushed. This breaks the
second example above. We need to tighten the fix a bit and only
defer the break position if the "current source position" is
inside the class's scope. This way we always guarantee that the
BlockContext is pushed or not, depending if the source position
that corresponds to the break position is inside or outside the
class's scope.
Note 1: The CL updates a lot of the bytecode expectations. This
is because the class literals are often the first statement in
the snippet so we don't need to defer the break position.
Note 2: We add a mirrored debugger test to the inspector test so
the fuzzer can have some more fun.
Fixed: chromim:1350842
Change-Id: I9b5a409f77be80db674217a685a3fc9f8a0a71cf
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3827871
Reviewed-by: Shu-yu Guo <syg@chromium.org>
Reviewed-by: Kim-Anh Tran <kimanh@chromium.org>
Commit-Queue: Simon Zünd <szuend@chromium.org>
Reviewed-by: Marja Hölttä <marja@chromium.org>
Cr-Commit-Position: refs/heads/main@{#82473}
Bug: v8:12781
Change-Id: I759024fb18ee596ecb678e5b70c95235ea91e520
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3827126
Reviewed-by: Adam Klein <adamk@chromium.org>
Commit-Queue: Adam Klein <adamk@chromium.org>
Cr-Commit-Position: refs/heads/main@{#82464}
This reverts commit a19316d9d7.
Reason for revert: https://ci.chromium.org/ui/p/v8/builders/ci/V8%20Linux64%20UBSan/22670/overview
Original change's description:
> [heap] Rework Worklist base type
>
> Worklist uses a singly-linked list of segments to hold entries.
> Segment size was based on a compile-time constant but already stored
> in the segment itself.
>
> Rework the segments to query `malloc_usable_size()` on allocation and
> adjust the capacity properly. For PartitionAlloc, it turns out that
> there's ~20% more capacity available for the 64-element segments.
>
> This slows down actual allocation of the segments with the upside of
> improving utilization and requiring 20% less segments.
>
> Change-Id: Ib8595c3fb9fb75b02e4022f6c525bb59a2df7ab7
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3826047
> Commit-Queue: Anton Bikineev <bikineev@chromium.org>
> Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
> Reviewed-by: Anton Bikineev <bikineev@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#82432}
Change-Id: I14994e11ff5ffaba70b93d977d40dd2f6e9e5d35
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3829474
Owners-Override: Nico Hartmann <nicohartmann@chromium.org>
Commit-Queue: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Auto-Submit: Nico Hartmann <nicohartmann@chromium.org>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Cr-Commit-Position: refs/heads/main@{#82438}
