Don't overwrite WATCHLISTS each time with a checkout from the latest
release branch as that means it will never pick up changes from
master.

No-Try: true
Bug: chromium:832032
Change-Id: I3a9231369caa9a6591acb9b7f0c76dc031ab9178
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1926029
Commit-Queue: Dan Elphick <delphick@chromium.org>
Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65063}

https://chromium-review.googlesource.com/c/v8/v8/+/1926027 deprecated the
"preparser" test suite.

This CL removes the remaining test suite configuration.

R=machenbach@chromium.org

Bug: v8:10001
Change-Id: I45afb709ddad5be1ec6072a42567e669f900095e
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1926147
Auto-Submit: Tamer Tas <tmrts@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65062}

Bug: v8:9972
Change-Id: Ia85520eea8d3bcadc2573c16bf2778b1c3ff0c5a
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1926028
Auto-Submit: Jakob Gruber <jgruber@chromium.org>
Commit-Queue: Georg Neis <neis@chromium.org>
Reviewed-by: Georg Neis <neis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65061}

Bug: chromium:1010272
Change-Id: Ifc7ed5ff66b84e889668fd0820cea1d5b6af328f
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1925809Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Commit-Queue: Deepti Gandluri <gdeepti@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65060}

"preparser" is a legacy test-suite written in Python. "cctest/test-parsing"
provides the same coverage and more for the preparser.

This CL removes "preparser" stand-alone test-suite

R=verwaest@chromium.org
CC=​machenbach@chromium.org

Bug: v8:10001
Change-Id: I1823967e654e8d6d9e42eadfd667f90074d57ba9
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1926027Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Commit-Queue: Toon Verwaest <verwaest@chromium.org>
Auto-Submit: Tamer Tas <tmrts@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65059}

Rolling v8/build: https://chromium.googlesource.com/chromium/src/build/+log/456253c..9f9c46f

Rolling v8/third_party/catapult: https://chromium.googlesource.com/catapult/+log/f7d5f0c..4c9781e

Rolling v8/third_party/depot_tools: https://chromium.googlesource.com/chromium/tools/depot_tools/+log/35a67a5..639872c

TBR=machenbach@chromium.org,tmrts@chromium.org

Change-Id: I34208500b48e4d745ae0aa83d6667c35ed8800cb
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1924898Reviewed-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@{#65058}

This reverts commit f2a74165.

Reason for revert: Clusterfuzz
Bug: chromium:1026479

Original change's description:
> [regexp] Re-execute regexp when '.indices' is accessed.
> 
> Instead of storing a pointer to the last_match_info, which may
> change, this cl modifies JSRegExpResult to store a pointer to
> the original JSRegExp which generated it, as well as additional
> data needed to re-execute the match.
> 
> Basically a straight copy and tidy off jgruber@'s prototype:
> https://chromium-review.googlesource.com/c/v8/v8/+/1876810
> 
> Bug: v8:9548
> Change-Id: I11b7deae681b8287e41e8d0e342291ff484751fb
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1910129
> Commit-Queue: Joshua Litt <joshualitt@chromium.org>
> Reviewed-by: Jakob Gruber <jgruber@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#65053}

TBR=jgruber@chromium.org,joshualitt@chromium.org

Change-Id: I6294e3d7ac0b3e2bd9404697823b8d3cc2545c16
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:9548
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1925651Reviewed-by: Joshua Litt <joshualitt@chromium.org>
Commit-Queue: Joshua Litt <joshualitt@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65057}

Bug: v8:9886
Change-Id: I5ed8ad13a4c92b61cddb8d86ec97e242252a556e
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1922231
Commit-Queue: Zhi An Ng <zhin@chromium.org>
Reviewed-by: Bill Budge <bbudge@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65056}

Bug: v8:8976
Change-Id: Ifa9b874b5b75b51046ba611db2b9fad3cbd33905
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1920066
Commit-Queue: Z Nguyen-Huu <duongn@microsoft.com>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65055}

Minor cleanup: some classes in Torque don't yet have any definitions for
their fields, so it doesn't make sense to emit field layout macros for
those classes.

Bug: v8:7793
Change-Id: Iee38aa3cbe684f4a63329a676e2e94944dc05de1
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1925010Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Commit-Queue: Seth Brenith <seth.brenith@microsoft.com>
Cr-Commit-Position: refs/heads/master@{#65054}

Instead of storing a pointer to the last_match_info, which may
change, this cl modifies JSRegExpResult to store a pointer to
the original JSRegExp which generated it, as well as additional
data needed to re-execute the match.

Basically a straight copy and tidy off jgruber@'s prototype:
https://chromium-review.googlesource.com/c/v8/v8/+/1876810

Bug: v8:9548
Change-Id: I11b7deae681b8287e41e8d0e342291ff484751fb
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1910129
Commit-Queue: Joshua Litt <joshualitt@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65053}

function descriptor

Change-Id: I439bac759cb363f35f6aa23a699b6ef1d9079684
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1925027Reviewed-by: Junliang Yan <jyan@ca.ibm.com>
Commit-Queue: Milad Farazmand <miladfar@ca.ibm.com>
Cr-Commit-Position: refs/heads/master@{#65052}

These instructions should always treat inputs as signed, and saturate to
unsigned min/max values.

E.g. given -1, it should saturate to 0.

The spec text,
https://github.com/WebAssembly/simd/blob/master/proposals/simd/SIMD.md#integer-to-integer-narrowing,
has been updated to describe this.

The changes here include codegen changes to ia32, x64, arm, and arm64,
changes to arm simulator, assembler, and disassembler to handle the case
of treating input as signed and narrowing to unsigned. The vqmovn
instruction can handle this case, our assembler wasn't allowing callers
to specify this.

The interpreter and scalar lowering are also fixed with this change.

Bug: v8:9729
Change-Id: I6f72baa825f59037f7754485df6a2964af59fe31
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1879423Reviewed-by: Deepti Gandluri <gdeepti@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Reviewed-by: Bill Budge <bbudge@chromium.org>
Commit-Queue: Zhi An Ng <zhin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65051}

Bug: v8:9886
Change-Id: I860bea0c317e9666662329e9b36598952c8ecfad
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1919697
Commit-Queue: Zhi An Ng <zhin@chromium.org>
Reviewed-by: Bill Budge <bbudge@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65050}

Spill/fill now take offsets instead of indices. We provide a
helper, GetStackOffsetFromIndex, for callers. This is currently only
useful while slot sizes are still fixed to 8 bytes.

StackTransferRecipe's RegisterLoad now works in terms of offset.

LiftoffStackSlots work in terms of offset as well.

TransferStackSlot currently still works in terms of indicies, but can be
converted to use offsets in a subsequent change.

Bug: v8:9909
Change-Id: If54fb844309bdfd641720d063135dd59551813e0
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1922489Reviewed-by: Clemens Backes <clemensb@chromium.org>
Commit-Queue: Zhi An Ng <zhin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65049}

This reverts commit 386e7dd2.

Reason for revert: blocking the V8 roll on linux_chromium_asan_rel_ng

Original change's description:
> [ptr-compr][x64] Temporarily enable pointer compression on x64
>
> Bug: v8:7703
> Change-Id: Iaa7a35a2438dc1181f60289190191b519e45bed0
> Cq-Include-Trybots: luci.v8.try:v8_linux64_ubsan_rel_ng,v8_linux64_tsan_rel
> Cq-Include-Trybots: luci.v8.try:v8_linux64_cfi_rel_ng
> Cq-Include-Trybots: luci.chromium.try:fuchsia_x64,linux-rel,mac-rel
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1924347
> Reviewed-by: Michael Achenbach <machenbach@chromium.org>
> Reviewed-by: Toon Verwaest <verwaest@chromium.org>
> Commit-Queue: Igor Sheludko <ishell@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#65033}

TBR=machenbach@chromium.org,ishell@chromium.org,verwaest@chromium.org

Change-Id: I6dd5c0c80c9d5b4a786c9b42a60a5b850c9168ac
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:7703
Cq-Include-Trybots: luci.v8.try:v8_linux64_ubsan_rel_ng,v8_linux64_tsan_rel
Cq-Include-Trybots: luci.v8.try:v8_linux64_cfi_rel_ng
Cq-Include-Trybots: luci.chromium.try:fuchsia_x64,linux-rel,mac-rel
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1925148
Commit-Queue: Igor Sheludko <ishell@chromium.org>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65048}

Port a7b9e588

R=zhin@chromium.org, joransiu@ca.ibm.com, jyan@ca.ibm.com, michael_dawson@ca.ibm.com
BUG=
LOG=N

Change-Id: I3406f424dcf918edd8cc51f7fe94dc28c2b4ed85
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1924867Reviewed-by: Junliang Yan <jyan@ca.ibm.com>
Commit-Queue: Milad Farazmand <miladfar@ca.ibm.com>
Cr-Commit-Position: refs/heads/master@{#65047}

This is part 3 of Torquifying DescriptorArray: making it possible to use
the "descriptors" indexed field from code written in Torque. A small
macro EnsureArrayLengthWritable is converted to demonstrate the new
functionality.

This CL also introduces the arrow token `->` and desugars a->b to (*a).b
so that the new builtin looks a little cleaner.

Bug: v8:7793
Change-Id: I84eaa97f664aa67273866760e6ede4346a3ee2f9
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1900332
Commit-Queue: Seth Brenith <seth.brenith@microsoft.com>
Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65046}

Bug: v8:9886
Change-Id: I88a4364596ef529c3873f4c80f36e0bfbe71e022
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1919695Reviewed-by: Bill Budge <bbudge@chromium.org>
Reviewed-by: Deepti Gandluri <gdeepti@chromium.org>
Commit-Queue: Zhi An Ng <zhin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65045}

Handlify raw SharedFunctionInfo in
CreateInterpreterDataForDeserializedCode.

Bug: v8:9992
Change-Id: I58fd2a78723cb3cd4784086c171c58cf2c32aacc
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1924362
Auto-Submit: Dan Elphick <delphick@chromium.org>
Commit-Queue: Maya Lekova <mslekova@chromium.org>
Reviewed-by: Maya Lekova <mslekova@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65044}

Bug: v8:9996
Change-Id: I8c39a3a74a58e35eea784b8b26a2c519819b3269
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1924364
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Igor Sheludko <ishell@chromium.org>
Auto-Submit: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65043}

Bug: chromium:1022270
Change-Id: I6f1ee944b6cee977894d3cc425445f326a0866e5
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1924351Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Commit-Queue: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65042}

Bug: v8:9813
Change-Id: I75ca39612f0420548a56cc32edaa13a36a9713e9
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1900661Reviewed-by: Bill Budge <bbudge@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Commit-Queue: Zhi An Ng <zhin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65041}

Bug: v8:9708
Change-Id: Iba4bf148437b9aa27d9b57ee2ebf48948d1ac163
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1801838Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65040}

This reduction relies on a known object layout of the regexp instance
in order to access the lastIndex field through a statically-determined
offset. Prior to this CL, we checked only for instance types, not for
the map, and thus it was possible to read garbage from either inside
or outside the current object.

Bug: chromium:1024758,v8:7779
Change-Id: I1eec8220797f443bdf3d05804e54f33b21fa2f00
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1924353Reviewed-by: Georg Neis <neis@chromium.org>
Reviewed-by: Sigurd Schneider <sigurds@chromium.org>
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65039}

TBR=neis@chromium.org
NOTRY=true

Bug: v8:9984
Change-Id: If192eb8680f8147d64aaa796955cb2ca38d0246d
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1924360Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65038}

This CL implements torque builtins for BigInt subtraction and extends
the compilation pipeline to lower calls to the generic subtraction
to SpeculativeBigIntSubtract and later to BigIntSubtract with
necessary checks in case of BigInt feedback.

The CL also implements lowering of these operators to native machine
word operations on 64 bit architectures if they are used in a
truncating context (aka BigInt.asUintN).

Bug: v8:9407
Change-Id: Idf5da14c380bc7c12375e7f084a3e1c455303f5f
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1895566Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Reviewed-by: Georg Neis <neis@chromium.org>
Commit-Queue: Nico Hartmann <nicohartmann@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65037}

Bytecode flushing bit me again.

Bug: v8:9945, v8:9983
Change-Id: I9e4f9dd5e1793d60b24def447a8374e550fa248a
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1924352
Auto-Submit: Georg Neis <neis@chromium.org>
Reviewed-by: Nico Hartmann <nicohartmann@chromium.org>
Commit-Queue: Georg Neis <neis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65036}

For arm64 decompressing a TaggedSigned results in a 64-bit value, with
the top 32 bits zeroed and the lower 32 bits being the SMI. This patch,
with the --debug-code flag enabled, will corrupt the top 32 bits to try
and catch places that are using 64-bit operations instead of 32-bit operations.

Change-Id: I3d3048c4f4b87f3bce26d0c7eb41789ec6b99f5b
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1917099Reviewed-by: Santiago Aboy Solanes <solanes@chromium.org>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Commit-Queue: Joey Gouly <joey.gouly@arm.com>
Cr-Commit-Position: refs/heads/master@{#65035}

Bug: v8:9810
Change-Id: I6d7b9099a53badfdfdfa6b57211931b39ae72124
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1917154Reviewed-by: Igor Sheludko <ishell@chromium.org>
Commit-Queue: Mythri Alle <mythria@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65034}

Bug: v8:7703
Change-Id: Iaa7a35a2438dc1181f60289190191b519e45bed0
Cq-Include-Trybots: luci.v8.try:v8_linux64_ubsan_rel_ng,v8_linux64_tsan_rel
Cq-Include-Trybots: luci.v8.try:v8_linux64_cfi_rel_ng
Cq-Include-Trybots: luci.chromium.try:fuchsia_x64,linux-rel,mac-rel
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1924347Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Commit-Queue: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65033}

The optimization behavior in these configurations is strange, I'm
still trying to understand what exactly is going on.

Bug: v8:9945, v8:9983

Change-Id: I52782b9e73decb9f3b2439cddd5e23068faebdf4
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1924349Reviewed-by: Nico Hartmann <nicohartmann@chromium.org>
Commit-Queue: Georg Neis <neis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65032}

Former CL 352bbb12 https://crrev.com/c/1893192 made an optimization that move non-JS
linkage builtins code objects into RO_SPACE, but caused v8 crash on mips platform,
so temporarily disable the change on mips platform.

Change-Id: Iffba1a35985ccf6688e29e35db20602d69a496e6
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1919442
Auto-Submit: Zhao Jiazhong <zhaojiazhong-hf@loongson.cn>
Reviewed-by: Dan Elphick <delphick@chromium.org>
Commit-Queue: Dan Elphick <delphick@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65031}

Drive-by: For more flexibility (e.g. for future IsNull methods), remove
'Constant' from names in the list of constants.

Bug: v8:9972
Change-Id: I66ec64c30cb397641d77cd26b514e8ac52763e16
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1924348
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Commit-Queue: Georg Neis <neis@chromium.org>
Auto-Submit: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Georg Neis <neis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65030}

In most cases where we bail out to TurboFan, we actually have a fallback
that just calls a C function instead. This fallback did not exist
initially, but was added later for other platforms (see e.g.
https://crrev.com/c/1044187).
By reusing that fallback on intel, we remove another portion of function
that could not be compiled in Liftoff on specific CPUs.

R=ahaas@chromium.org

Bug: v8:9919
Change-Id: I151000c004dc330362337bf7ddeaec68390c3467
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1921986Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65029}

R=jgruber@chromium.org

Change-Id: If4b439ac7465cd984600816ff619d66f04cf174b
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1917156Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65028}

... by disallowing checkpoint elimination across function boundaries.
See the comment in checkpoint-elimination.cc and the tests for details.

Bug: v8:9945
Change-Id: Ibf4ab6f0e4e709e26d3c4428a082ef45dcbeb8b0
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1906208
Auto-Submit: Georg Neis <neis@chromium.org>
Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Reviewed-by: Maya Lekova <mslekova@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Commit-Queue: Georg Neis <neis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65027}

Individual frames of a stack frame in the frame cache might point
to the JSFunction of that corresponding stack frame. It is illegal to
serialize JSFunction objects in the isolate snapshot, so the attempt
to serialize the stack frame cache results in a crash. This can happen
when a warmup script is run, before a snapshot is created.

This CL fixes the crash by not utilizing the stack frame cache in case
the serializer is enabled.

Change-Id: I8b79a06b8cff36e1f54b54d3d8e5397b07ba52e7
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1923068
Auto-Submit: Simon Zünd <szuend@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Commit-Queue: Yang Guo <yangguo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65026}

We recently extended function-entry stack checks by an offset
representing the difference in optimized and unoptimized frame sizes,
with the intent of avoiding stack overflows during deopts. Although
the generated code is very efficient (just a single additional
register subtraction, executed exactly once per call), perf impact
is measurable.

To avoid the overhead in most cases, this CL adds a stack slack,
currently set to 256 bytes, by which deopts are allowed to exceed the
real V8 stack limit. For function-entry stack checks with an offset
less than stack slack, the offset is not applied and the more
efficient version of the stack check is emitted.

The V8 limit is chosen to be smaller than OS stack size (assumed to
be at least 1 MB). This guarantee is upheld even with slack.

Bug: chromium:1020989,v8:9534
Change-Id: Idee2e7ad1fa7810bf086a9f72ce00a9717010310
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1910099Reviewed-by: Georg Neis <neis@chromium.org>
Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65025}

Rolling v8/build: https://chromium.googlesource.com/chromium/src/build/+log/253c17c..456253c

Rolling v8/buildtools: https://chromium.googlesource.com/chromium/src/buildtools/+log/140e4d7..6b3e658

Rolling v8/buildtools/third_party/libc++/trunk: https://chromium.googlesource.com/chromium/llvm-project/libcxx/+log/5938e05..78d6a77

Rolling v8/third_party/catapult: https://chromium.googlesource.com/catapult/+log/a6bbfb9..f7d5f0c

Rolling v8/third_party/depot_tools: https://chromium.googlesource.com/chromium/tools/depot_tools/+log/1f392b8..35a67a5

Rolling v8/tools/clang: https://chromium.googlesource.com/chromium/src/tools/clang/+log/fdd6048..7506d59

TBR=machenbach@chromium.org,tmrts@chromium.org

Change-Id: I0f90feffadd437d852796e7f9268167841c4cb92
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1923090Reviewed-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@{#65024}