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Jakob Gruber 4547c5ef30 [compiler] Allow deopts to slightly exceed the stack limit
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/+/1910099
Reviewed-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}
2019-11-19 06:30:07 +00:00
build_overrides Use relative paths to OWNERS files 2019-08-12 13:52:52 +00:00
custom_deps Use relative paths to OWNERS files 2019-08-12 13:52:52 +00:00
docs Add OWNERS for docs/ 2019-05-15 12:06:15 +00:00
gni [build] Move split_static_library.gni from Chromium repo 2019-11-04 15:45:54 +00:00
include [Intl] Prototype Intl.DisplayNames 2019-11-18 21:48:22 +00:00
infra Revert "[ptr-compr][x64] Temporarily enable pointer compression on x64" 2019-11-18 09:01:31 +00:00
samples [cleanup] Drop some occurrences of Isolate::Current 2019-06-26 19:39:21 +00:00
src [compiler] Allow deopts to slightly exceed the stack limit 2019-11-19 06:30:07 +00:00
test [class] Remove local test262 private class field tests 2019-11-19 00:34:46 +00:00
testing Use relative paths to OWNERS files 2019-08-12 13:52:52 +00:00
third_party [Builtins] Math.abs and Math.imul ported to Torque 2019-11-13 20:23:15 +00:00
tools [Intl] Prototype Intl.DisplayNames 2019-11-18 21:48:22 +00:00
.clang-format [clang-format] Don't derive pointer alignment 2017-01-17 09:28:19 +00:00
.clang-tidy [tool] Remove unfixed clang-tidy warnings to ease use. 2018-10-26 07:40:32 +00:00
.editorconfig Add .editorconfig 2017-07-28 13:39:24 +00:00
.flake8 Add .flake8 to allow for python style checking. 2019-07-19 21:44:03 +00:00
.git-blame-ignore-revs Add recent code rewrite to .git-blame-ignore-revs 2019-05-23 10:38:45 +00:00
.gitattributes .gitattributes: Mark minified emscripten js files as -diff 2018-09-19 16:27:10 +00:00
.gitignore Remove MIPS(64) builders from V8 infra 2019-09-16 11:20:11 +00:00
.gn [build] Dynamically decide if to use system xcode 2019-07-29 08:20:24 +00:00
.vpython [tools] Implement confidence-based number of runs 2019-05-09 09:42:28 +00:00
.ycm_extra_conf.py [ycm] Switch from gnu++11 to gnu++14 2017-11-27 07:48:21 +00:00
AUTHORS [builtins] Port Number.prototype.toString to Torque 2019-11-05 11:00:26 +00:00
BUILD.gn [Intl] Prototype Intl.DisplayNames 2019-11-18 21:48:22 +00:00
ChangeLog [release] Merge ChangeLog back to master 2018-12-07 15:41:59 +00:00
CODE_OF_CONDUCT.md Explicitly state that the Chromium Code of Conduct also applies to V8 2016-03-02 09:51:24 +00:00
codereview.settings Make Gerrit the default code review for V8 2017-06-30 17:37:37 +00:00
COMMON_OWNERS Rename clemensh to clemensb in OWNERS 2019-09-26 08:44:44 +00:00
DEPS Update V8 DEPS. 2019-11-19 03:55:17 +00:00
ENG_REVIEW_OWNERS Add eng review owners as escalation path 2019-05-15 19:12:10 +00:00
INFRA_OWNERS Clean up infra owners 2019-05-15 11:18:43 +00:00
INTL_OWNERS Add missing owners files 2019-05-31 07:21:01 +00:00
LICENSE [wasm] Draft version of C/C++ Wasm API 2019-04-17 16:00:26 +00:00
LICENSE.fdlibm Add LICENSE.fdlibm for all the fdlibm imported sources. 2016-06-09 07:17:03 +00:00
LICENSE.strongtalk Add LICENSE.v8, LICENSE.strongtalk and LICENSE.valgrind to the v8 2011-02-03 07:10:06 +00:00
LICENSE.v8 Add LICENSE.v8, LICENSE.strongtalk and LICENSE.valgrind to the v8 2011-02-03 07:10:06 +00:00
LICENSE.valgrind Add LICENSE.v8, LICENSE.strongtalk and LICENSE.valgrind to the v8 2011-02-03 07:10:06 +00:00
MIPS_OWNERS Move architecture dependent files 2019-05-28 14:02:15 +00:00
OWNERS Add syg@chromium.org as DEPS owner for test262 rolls 2019-09-17 19:29:11 +00:00
PPC_OWNERS Move architecture dependent files 2019-05-28 14:02:15 +00:00
PRESUBMIT.py Re-check all files on a DEPS change 2019-09-30 09:23:36 +00:00
README.md [docs] Change links from old wiki to v8.dev 2019-03-07 12:13:30 +00:00
S390_OWNERS Move architecture dependent files 2019-05-28 14:02:15 +00:00
WATCHLISTS Remove 'profiler' category from WATCHLISTS 2019-10-21 08:23:59 +00:00

V8 JavaScript Engine

V8 is Google's open source JavaScript engine.

V8 implements ECMAScript as specified in ECMA-262.

V8 is written in C++ and is used in Google Chrome, the open source browser from Google.

V8 can run standalone, or can be embedded into any C++ application.

V8 Project page: https://v8.dev/docs

Getting the Code

Checkout depot tools, and run

    fetch v8

This will checkout V8 into the directory v8 and fetch all of its dependencies. To stay up to date, run

    git pull origin
    gclient sync

For fetching all branches, add the following into your remote configuration in .git/config:

    fetch = +refs/branch-heads/*:refs/remotes/branch-heads/*
    fetch = +refs/tags/*:refs/tags/*

Contributing

Please follow the instructions mentioned at v8.dev/docs/contribute.