The following bit casting method using reinterpret_cast
has undefined behaviour:
```
int a = 1;
float b = *reinterpret_cast<float*>(&a);
```
Above breaks the strict aliasing rule which indicates:
> dereferencing pointers to objects of different types will
never refer to the same memory location.

More information can be found under src/base/macros.h.

`bit_cast` here is implemented with `memcpy` behind the scenes.
C++20 will have this feature included by default.

Change-Id: I69ffdbeba6db64e24b268d838ea1d863fcd9121d
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2889331Reviewed-by: Junliang Yan <junyan@redhat.com>
Commit-Queue: Milad Fa <mfarazma@redhat.com>
Cr-Commit-Position: refs/heads/master@{#74513}

On x64 we can emit more compact instructions for mov(reg, imm). However
currently this only happens when using the Set method explicitly.
This CL renames Set to Move to avoid confusion and yield better code
by default.

Also use the new Move helper for Smis as well.

Change-Id: I06558e88d1142098f77fb98870f09742d494f3dc
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2874450Reviewed-by: Zhi An Ng <zhin@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Commit-Queue: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74512}

Allow GC of the shared heap without any attached clients. This
CL also disables incremental marking for shared heaps for now.

Bug: v8:11708
Change-Id: I1eb47a42fe3ced0f23f679ecaae0c32e09eab461
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2886878Reviewed-by: Victor Gomes <victorgomes@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Dominik Inführ <dinfuehr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74511}

This change adds support for `const` redeclaration on REPL mode with
the semantincs recommended in the design doc:

1) REPL scripts should not be able to reassign bindings to `const`
   variables.

2) Re-declaring `const` variables of page scripts is not allowed in
   REPL scripts.

3) Re-declearing `const` variables is not allowed in the same REPL
   script.

4) `const` re-declaration is allowed across separate REPL scripts.

5) Old references to previously declared variables get updated with the
   new value, even those references from within optimized functions.

Design doc: https://goo.gle/devtools-const-repl

Bug: chromium:1076427
Change-Id: Ic73d2ae7fcfbfc1f5b58f61e0c3c69e9c4d85d77
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2865721Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Reviewed-by: Mythri Alle <mythria@chromium.org>
Commit-Queue: Luis Fernando Pardo Sixtos <lpardosixtos@microsoft.com>
Cr-Commit-Position: refs/heads/master@{#74510}

Bug: v8:11757
Change-Id: Ib463eb25631b9be8fc02b8cbc9e1f5984739dac2
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2887023Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74509}

Port cc06b8c7

Original Commit Message:

    Convert StoreOrigin, TypeOfMode, SaveFPRegsMode and ArgvMode to
    enum classes with k-prefixed values.

R=cbruni@chromium.org, joransiu@ca.ibm.com, junyan@redhat.com, midawson@redhat.com
BUG=
LOG=N

Change-Id: I46993e6e846cf7c1f6b3d15ea0aaea3d5693bf4d
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2887646Reviewed-by: Junliang Yan <junyan@redhat.com>
Commit-Queue: Milad Fa <mfarazma@redhat.com>
Cr-Commit-Position: refs/heads/master@{#74508}

DebugEvaluate can evaluate expressions in side-effect-free mode, where
any operation that would cause observable side effects throws an
exception. Currently, when accessors are backed by callbacks, it's
possible that ICs call those accessors directly, bypassing the
side-effect checks. This CL introduces a bailouts to runtime in those
cases.

Fixed: chromium:1201781
Also-By: ishell@chromium.org, pfaffe@chromium.org
Change-Id: Ie53bfb2bff7b3420f2b27091e8df6723382cf53c
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2857634
Commit-Queue: Philip Pfaffe <pfaffe@chromium.org>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74507}

The deoptimization table needs to be continuously, so we need to block
trampoline pool emission during the whole process.

bug: v8:11759
Change-Id: Ie5e0ffe27dc8e6cdb18985dc2cf26bdadeff318f
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2881918
Commit-Queue: Junliang Yan <junyan@redhat.com>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74506}

Argc and Slot are usually small and fit within a single 32bit word.
This reduces most property calls by 5 bytes.

This results in roughly 1% code reduction for sparkplug and no
measurable regression on x64.

Bug: v8:11420
Change-Id: I272c26c40b99f2dc5817f18bec113662a5bfebce
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2872828Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Commit-Queue: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74505}

The typo in introduced by:
commit b684c36f

Change-Id: Ic8e9afe7b47e5c615c31ecbd3481e5b33d4f84e2
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2885355Reviewed-by: Zhao Jiazhong <zhaojiazhong-hf@loongson.cn>
Commit-Queue: Zhao Jiazhong <zhaojiazhong-hf@loongson.cn>
Auto-Submit: Liu yu <liuyu@loongson.cn>
Cr-Commit-Position: refs/heads/master@{#74504}

This reverts commit cf35926a.

Reason for revert: Speculative revert for TSAN breakage which closed the tree, e.g. https://ci.chromium.org/ui/p/v8/builders/ci/V8%20Linux64%20TSAN%20-%20stress-incremental-marking/3187/overview and https://ci.chromium.org/ui/p/v8/builders/ci/V8%20Linux64%20TSAN/36671/overview

Original change's description:
> [cleanup] Remove PropertyArray::synchronized_length_and_hash
>
> It was never stored with a release store, so can we use the loads as
> non-atomic ones.
>
> Bug: v8:7790
> Change-Id: Ife67e8650a5fb279ad808e5e68c2ab46ee3507c5
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2880541
> Reviewed-by: Georg Neis <neis@chromium.org>
> Commit-Queue: Santiago Aboy Solanes <solanes@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#74493}

Bug: v8:7790
Change-Id: I4f942c46631117c6573ac16ca8464c24c1c23f6e
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2886886
Auto-Submit: Maya Lekova <mslekova@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@{#74503}

This ports https://crrev.com/c/2515787 for V8.

Bug: v8:9871
Change-Id: I3e62b2960bc622f90d433f9731a287ee14319047
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2886880
Auto-Submit: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Maya Lekova <mslekova@chromium.org>
Reviewed-by: Maya Lekova <mslekova@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74502}

This is the second CL in a line of two to implement PKU-based
WebAssembly code space write protection. The first CL added two
low-level PKU functions; this CL uses them to grant/withdraw writable
permissions, local to each thread that wants to modify the code space.

In particular, when {--wasm-memory-protection-keys} is enabled, we first
associate a memory protection key with all code pages, which by
default does not allow any write access. Then, before each location that
needs to modify the code space, we open
{NativeModuleModificationScope}s (which are already present for
mprotect-based write protection). When the PKU flag is given, this then
first tries to set permissions of a memory protection key (which is
fast), and otherwise when {--wasm-write-protect-code-memory} is enabled,
falls back to mprotect-based write protection (which is much more
expensive and also not thread-local, but for the whole process).

R=clemensb@chromium.org

Bug: v8:11714
Change-Id: I3527906a8d9f776ed44c8d5db52539e78e1c52fd
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2882800
Commit-Queue: Daniel Lehmann <dlehmann@google.com>
Reviewed-by: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74501}

Bug: chromium:1206994, chromium:1206754, chromium:1206822
Change-Id: I8ccd501c5a918613fad59afdd65ca499ee57d7a1
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2882805
Commit-Queue: Victor Gomes <victorgomes@chromium.org>
Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74500}

Re-use InstallConstructorFunc and remove an obsolete comment.

R=ahaas@chromium.org

Change-Id: I1143d3e58e968b9210cef5045d8221d20ed18419
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2886859Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Thibaud Michaud <thibaudm@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74499}

This is the first CL in a line of two to finish PKU-based WebAssembly
code space write protection. This CL adds two low-level PKU functions,
which are essentially wrapping the functionality in glibc's
{pkey_mprotect()} and {pkey_set()}).

The added functionality is in
(1) {SetPermissionsAndMemoryProtectionKey()}: Associate a memory
protection key with a page (simultaneously with setting the page's
regular permssions). This is as costly as a regular {mprotect()}.
This call itself does not restrict permissions besides the regular page
permissions.
(2) {SetPermissionsForMemoryProtectionKey()}: Set permissions for the
key itself (now associated with a page). This can be either "all data
access disabled" (i.e., no read or write, but execution is allowed) or
"write access disabled" (which we use for code space write protection).
The permissions are added on top of the page's regular permissions. This
operation is cheap (in the order of 20 cycles) since it is roughly a
thread-local register read, some bit-masking, and register write.
See the second CL (based on this one) for how those two functions will
be used.

A note on compatability and security implications: Because the functions
which we use here were only added in glibc 2.27, and since glibc is
dynamically linked, we check at runtime (with {dlsym()}) whether
{pkey_*()} functions are available. However, calling functions via a
pointer coming from {dlsym()} is not supported by CFI so far, which is
why we disable indirect call checking for the added functions.
Potentially, the functions could hence be used as an indirect call
gadget in a ROP attack. On the other hand, they are only compiled in
currently only on Linux on x64, and disabling CFI indirect call checking
is also done in other places already.

R=clemensb@chromium.org

Bug: v8:11714
Change-Id: I0da00818f28cf1da195a5149bf11fccf87c5f8ea
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2882797
Commit-Queue: Daniel Lehmann <dlehmann@google.com>
Reviewed-by: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74498}

Convert StoreOrigin, TypeOfMode, SaveFPRegsMode and ArgvMode to
enum classes with k-prefixed values.

Change-Id: Ib6ca3a9995297e8303a7e013b1d829613c0db510
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2885042Reviewed-by: Maya Lekova <mslekova@chromium.org>
Reviewed-by: Mythri Alle <mythria@chromium.org>
Reviewed-by: Zhi An Ng <zhin@chromium.org>
Commit-Queue: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74497}

Member is sometimes still used from off-heap storage which prohibits
getting the heap from the Member's slot address.

Bug: v8:11756
Change-Id: I61658ce07a8b02a8c400232ff21c75f0d8b95dcb
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2886879
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Anton Bikineev <bikineev@chromium.org>
Auto-Submit: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Anton Bikineev <bikineev@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74496}

Isolate::UseAsSharedIsolate() was invoked after the Isolate was already
created. I think it is cleaner to have the shared-flag right when
constructing an Isolate. This way we can use that property already
when setting up the isolate.

Bug: v8:11708
Change-Id: Ibbfee09122b7b0361a5af7a1b559796594834813
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2885041Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Commit-Queue: Dominik Inführ <dinfuehr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74495}

Change-Id: I89ceb023d109f3ad69c0d679135c52cd278b4af3
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2878150
Auto-Submit: Yahan Lu <yahan@iscas.ac.cn>
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74494}

It was never stored with a release store, so can we use the loads as
non-atomic ones.

Bug: v8:7790
Change-Id: Ife67e8650a5fb279ad808e5e68c2ab46ee3507c5
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2880541Reviewed-by: Georg Neis <neis@chromium.org>
Commit-Queue: Santiago Aboy Solanes <solanes@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74493}

Rolling v8/build: https://chromium.googlesource.com/chromium/src/build/+log/f8d7f9d..52ccb29

Rolling v8/third_party/aemu-linux-x64: H-kH9WxQErL_AR-Nu_ZL8hbu1D-rZmdQQUaYZYm3AOUC..pwjSs3IapHTvM0wB7z3723g8rjsQnCWikZJhQxtBetsC

Rolling v8/third_party/catapult: https://chromium.googlesource.com/catapult/+log/c92267a..1fbada9

Rolling v8/third_party/depot_tools: https://chromium.googlesource.com/chromium/tools/depot_tools/+log/03dfb00..c499142

Rolling v8/third_party/google_benchmark/src: https://chromium.googlesource.com/external/github.com/google/benchmark/+log/0852c79..3b508fa

Rolling v8/third_party/zlib: https://chromium.googlesource.com/chromium/src/third_party/zlib/+log/eb9ce8c..618ddec

Rolling v8/tools/clang: https://chromium.googlesource.com/chromium/src/tools/clang/+log/dbcffda..e76c8f1

Rolling v8/tools/luci-go: git_revision:66f9c8541b85c7f6efc63e75e68d660d4fb30752..git_revision:1b50bbe2f93441dd227ad6e6684fa9be4ab0dec2

Rolling v8/tools/luci-go: git_revision:66f9c8541b85c7f6efc63e75e68d660d4fb30752..git_revision:1b50bbe2f93441dd227ad6e6684fa9be4ab0dec2

Rolling v8/tools/luci-go: git_revision:66f9c8541b85c7f6efc63e75e68d660d4fb30752..git_revision:1b50bbe2f93441dd227ad6e6684fa9be4ab0dec2

TBR=v8-waterfall-sheriff@grotations.appspotmail.com

Change-Id: I7c116cf19efaf2f55a7b40070a47645eb725c8d0
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2886659Reviewed-by: v8-ci-autoroll-builder <v8-ci-autoroll-builder@chops-service-accounts.iam.gserviceaccount.com>
Commit-Queue: v8-ci-autoroll-builder <v8-ci-autoroll-builder@chops-service-accounts.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/master@{#74492}

This reverts commit 7dce6a26.

Reason for revert: Performance regressions for x64 Octane --no-opt

Original change's description:
> Fix speculation poisoning on x64
>
> Pointer cage reserved another register and inadvertently broke
> speculation poisoning by aliasing kSpeculationPoisonRegister with
> kInterpreterBytecodeArrayRegister (r12).
>
> This CL changes kInterpreterBytecodeArrayRegister to r11. Note that this
> changes it from being callee-save to caller-save, which required code
> reshuffling in a baseline builtin.
>
> Bug: v8:11726
> Change-Id: Ic2a1bd6b3a2cb4c480c84375dd3274f2efedc81f
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2869985
> Commit-Queue: Shu-yu Guo <syg@chromium.org>
> Reviewed-by: Leszek Swirski <leszeks@chromium.org>
> Reviewed-by: Georg Neis <neis@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#74364}

TBR=leszeks@chromium.org

Bug: v8:11726
Change-Id: Ic59b602e5519b05ad06890e409761f5138230b92
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2886544Reviewed-by: Shu-yu Guo <syg@chromium.org>
Commit-Queue: Shu-yu Guo <syg@chromium.org>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Cr-Commit-Position: refs/heads/master@{#74491}

Bug: v8:11589
Change-Id: I971003a41455d9594b9b98379e7976b75718d417
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2885738Reviewed-by: Bill Budge <bbudge@chromium.org>
Commit-Queue: Zhi An Ng <zhin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74490}

- Share RemeberedSetAction and SmiCheck enums between all platforms.
- Convert to enum classes with k-prefixed values

Bug: v8:11420
Change-Id: Ib265a229f12a850ea866fd01d8022cbae5e1a9d8
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2885040Reviewed-by: Zhi An Ng <zhin@chromium.org>
Commit-Queue: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74489}

Bug: v8:11589
Change-Id: I572dcc740f9974261521e239cd37c64af3bb0d7d
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2883484Reviewed-by: Bill Budge <bbudge@chromium.org>
Commit-Queue: Zhi An Ng <zhin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74488}

Spec: https://tc39.es/proposal-intl-locale-info/
Design Doc: https://docs.google.com/document/d/1OwEsvs8VQwvR-ug01xLyIwpgcvUfaP24u9owc7aBKJ4/edit#
https://www.chromestatus.com/feature/5566859262820352

Behind flag --harmony_intl_locale_info

Bug: v8:11638
Change-Id: I9904b777b084aa02c86a258c7df48fdfb976396d
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2878908Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Frank Tang <ftang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74487}

After updating our bots to use GCC 7.4, we do not need to support
incomplete C++14 support any more. In particular, we can assume
complete c++14 constexpr support now.

This CL removes the V8_HAS_CXX14_CONSTEXPR and CONSTEXPR_DCHECK macros.
The CONSTEXPR_DCHECKs are replaced by DCHECK and friend, or
STATIC_ASSERT where possible.

R=jgruber@chromium.org, leszeks@chromium.org, mlippautz@chromium.org

Bug: v8:9686, v8:11384
Change-Id: I3a8769a0f54da7eb2cacc37ee23e5c97092e3051
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2876847Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Mythri Alle <mythria@chromium.org>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74486}

The AtomicWeak wscope was nested within the AtomicMark scope. Both
should be top level scopes and should be nested within each other.

Bug: chromium:1056170
Change-Id: I1d695c1a3a24fff31aa57893739dca4b558901fb
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2883663
Commit-Queue: Omer Katz <omerkatz@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74485}

This reverts commit 5f0ac36c.

Reason for revert: Seems to be associated with multiple Sanitizer failures:

https://ci.chromium.org/p/v8/builders/ci/V8%20Linux64%20TSAN%20-%20stress-incremental-marking/3176

Original change's description:
> [compiler] Consider IsPendingAllocation in Ref construction
>
> The logic in JSHeapBroker::TryGetOrCreateData assumes that parts
> of the object are safe to read. In particular, the instance type
> must be readable for the chain of `Is##Name()` type checks.
>
> This is guaranteed if
>
>  - a global memory fence happened after object initialization and
>    prior to the read by the compiler; or
>  - the object was published through a release store and read through
>    an acquire read.
>
> The former is protected by the new call to ObjectMayBeUninitialized
> (which internally calls IsPendingAllocation) in TryGetOrCreateData.
>
> The latter must be marked explicitly by calling the new
> MakeRefAssumeMemoryFence variant.
>
> Note that support in this CL is expected to be incomplete and will
> have to be extended in the future as more cases show up in which
> MakeRef calls must be converted to MakeRefAssumeMemoryFence or to
> TryMakeRef.
>
> Bug: v8:7790,v8:11711
> Change-Id: Ic2f7d9fc46e4bfc3f6bbe42816f73fc5ec174337
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2874663
> Commit-Queue: Jakob Gruber <jgruber@chromium.org>
> Reviewed-by: Georg Neis <neis@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#74474}

Bug: v8:7790
Bug: v8:11711
Change-Id: Ia736cd1143da30ca25fdc2c3c1a2056ebf18d596
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2883245
Auto-Submit: Bill Budge <bbudge@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@{#74484}

This was missing from Ulan's implementation for
CollectCustomSpaceStatisticsAtLastGC.

Bug: chromium:1056170, chromium:1181269
Change-Id: I72354e4f04873095eac5cb39ed188ed83de0bd26
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2880219Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Omer Katz <omerkatz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74483}

The FrameSummary::FunctionName() method is only used by the
FrameInspector in the debugger, so the natural place to put
the dependency on GetWasmFunctionDebugName() is in there,
rather than adding a new dependency to frames.cc. This is a
follow up cleanup as discussed in https://crrev.com/c/2878734

Bug: chromium:1159307
Change-Id: I0698adf63f88fe6a93d6e5e6235bc0c2219e9341
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2883784Reviewed-by: Clemens Backes <clemensb@chromium.org>
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74482}

As a first step to support Fast API calls with overloads, adds a
new FunctionTemplate constructor that accepts a vector of CFunction*.

Bug: v8:11739
Change-Id: I112b1746768f52df52c893a4f1fb799b6bd90856
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2860838Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Reviewed-by: Maya Lekova <mslekova@chromium.org>
Reviewed-by: Georg Neis <neis@chromium.org>
Commit-Queue: Paolo Severini <paolosev@microsoft.com>
Cr-Commit-Position: refs/heads/master@{#74481}

Disable the checksum comparison for the read-only snapshot when
--stress-snapshot is used, since it's possible that it would be
corrupted. This corruption is not important as the purpose of
stress-snapshot is not to produce a useable snapshot, but to test that
the serialization/deserialization does not fail for any given objects.

Since the --stress-snapshot flag's value is now used outside of d8,
this also moves it to flag-definitions.h.

Cq-Include-Trybots: luci.v8.try:v8_linux64_gc_stress_custom_snapshot_dbg_ng
Bug: v8:11750
Change-Id: Iedcf1cfb5afa5f16ac19a76820b62b5b93948f2c
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2882810
Commit-Queue: Dan Elphick <delphick@chromium.org>
Auto-Submit: Dan Elphick <delphick@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Marja Hölttä <marja@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74480}

Make %PretenureAllocationSite more resilient to fuzzer inputs/configs
and allow it for fuzzing.

Bug: chromium:1200724
Change-Id: I541b1410ab1719b478c4ad9516dc350fec02fbba
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2883783Reviewed-by: Dominik Inführ <dinfuehr@chromium.org>
Commit-Queue: Patrick Thier <pthier@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74479}

Port d3d4a896

Original Commit Message:

    Checking for Smis is cheap. There is no need to put this in the
    deferred code block. With this CL we will bail out earlier for
    Smis.

R=cbruni@chromium.org, joransiu@ca.ibm.com, junyan@redhat.com, midawson@redhat.com
BUG=
LOG=N

Change-Id: I29811cdeae0310031c114260734f3d5429e77633
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2883861Reviewed-by: Junliang Yan <junyan@redhat.com>
Commit-Queue: Milad Fa <mfarazma@redhat.com>
Cr-Commit-Position: refs/heads/master@{#74478}

This is a partial reland of https://crrev.com/c/2850932, which was
reverted because the histogram failed Chromium integration. The V8
histogram added here uses only two values (0 = no support, 1 = support),
but is declared with 3 buckets in order not not fail a DCHECK on
Chromium's side. As soon as https://crrev.com/c/2874651 lands in
Chromium, we can properly declare the histogram here with only 2 buckets,
but for now this is good enough to get early data on PKU support in
the wild.

The other part of the original reverted CL (adding PKU alloc and free
functions, and a V8 flag for PKU) was already landed again in
https://crrev.com/c/2878738

Original change's description:
> [wasm] Add PKU alloc/free and support counter
>
> To enforce W^X for the WebAssembly code space, we want to explore using
> Intel memory protection keys for userspace, also known as MPK, PKEYs, or
> PKU. Instead of flipping page protection flags with mprotect (which
> incurs a high syscall overhead; and which switches flags for the whole
> process), this associates a key with each page once, and then changes
> the permissions of that key with a fast thread-local register write.
> That is, this gives both finger-grained permissions (per-thread) and
> more performance.
>
> This CL is starts experimenting with PKUs by
> (1) trying to allocate a protection key once per {WasmEngine} in x64
> Linux systems, and
> (2) adding a counter for recording the sucess/failure of that, to assess
> the support for PKUs on the target machine.
>
> The low-level PKU allocating functions should be moved into base/platform
> long-term, but are inside wasm/ for this CL.
>
> R=clemensb@chromium.org
> CC=​jkummerow@chromium.org
>
> Bug: v8:11714
> Change-Id: Ia4858970ced4d0b84cc8c2651e86dceb532c88a7
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2850932
> Commit-Queue: Daniel Lehmann <dlehmann@google.com>
> Reviewed-by: Clemens Backes <clemensb@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#74319}

Bug: v8:11714, chromium:1207318
Change-Id: I1035ac09bd7aa04584fbc5df7a408b96dd270d0a
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2871451Reviewed-by: Clemens Backes <clemensb@chromium.org>
Commit-Queue: Daniel Lehmann <dlehmann@google.com>
Cr-Commit-Position: refs/heads/master@{#74477}

This is moving needed stuff out of #if V8_ENABLE_WEBASSEMBLY.

Everything related to guards is still behind V8_ENABLE_WEBASSEMBLY,
since RAB / GSAB don't use guards.

Bug: v8:11111
Change-Id: I9b9fd0dbdcdc1f3c70d6e4f5eb1c70d1bab98e68
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2880221Reviewed-by: Clemens Backes <clemensb@chromium.org>
Commit-Queue: Marja Hölttä <marja@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74476}

Checking for Smis is cheap. There is no need to put this in the
deferred code block. With this CL we will bail out earlier for
Smis.

Bug: v8:11420
Change-Id: I52e39def633d7cb8bd51ae24d56d9582f56faf41
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2872826Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Commit-Queue: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74475}

The logic in JSHeapBroker::TryGetOrCreateData assumes that parts
of the object are safe to read. In particular, the instance type
must be readable for the chain of `Is##Name()` type checks.

This is guaranteed if

 - a global memory fence happened after object initialization and
   prior to the read by the compiler; or
 - the object was published through a release store and read through
   an acquire read.

The former is protected by the new call to ObjectMayBeUninitialized
(which internally calls IsPendingAllocation) in TryGetOrCreateData.

The latter must be marked explicitly by calling the new
MakeRefAssumeMemoryFence variant.

Note that support in this CL is expected to be incomplete and will
have to be extended in the future as more cases show up in which
MakeRef calls must be converted to MakeRefAssumeMemoryFence or to
TryMakeRef.

Bug: v8:7790,v8:11711
Change-Id: Ic2f7d9fc46e4bfc3f6bbe42816f73fc5ec174337
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2874663
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Georg Neis <neis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74474}