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Leszek Swirski e7f6d34cfe [ic] Remove SameValue optimisation for constant fields
We would previously try to preserve field constness if field assignment
was assigning the same value. It's unexpected that real-life code would
be assigning the same value multiple times to an intentionally constant
field, so this was additional bookkeeping with unclear value.

Replace this with not doing it, and considering any write to a constant
field to convert it to mutable. In particular, this means that stores to
existing constant fields in TurboFan become unconditional deopts, rather
than emitting additional code to check whether the value is the same.

Locally, this deopt doesn't fire on our peak-performance benchmarks.

Bug: v8:5495
Change-Id: I12216c5f10a00f42be32c64ca3afe7cf59b4e7f3
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3976516
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/main@{#83955}
2022-10-27 13:05:03 +00:00
.github [github] Close PRs created on the V8 GitHub mirror automatically 2021-01-12 08:39:59 +00:00
bazel Revert "[bazel] Add hide symbols from release / fast builds" 2022-10-21 13:08:38 +00:00
build_overrides [build] Remove obsolete gn flag 2021-01-11 15:50:59 +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 [mips32] Delete mips32 from v8 2022-09-13 07:54:54 +00:00
include [execution] Add ability to set the microtask queue for the context. 2022-10-26 16:40:21 +00:00
infra [build] Equally compile on mac_arm64 sim trybots 2022-10-27 10:33:11 +00:00
samples [sandbox] Initialize sandbox during V8::Initialize 2022-07-15 09:29:32 +00:00
src [ic] Remove SameValue optimisation for constant fields 2022-10-27 13:05:03 +00:00
test [ic] Remove SameValue optimisation for constant fields 2022-10-27 13:05:03 +00:00
testing [test] Migrate cctest/test-api-accessors.cc to unittests/ 2022-05-17 08:27:55 +00:00
third_party Roll inspector_protocol to update copyright headers 2022-10-09 17:40:23 +00:00
tools [wasm] Detemplatize immediates 2022-10-24 17:27:49 +00:00
.bazelrc [bazel] Use v8_enable_handle_zapping only in debug builds. 2022-01-11 11:32:39 +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 remove swarming_client 2021-08-24 10:39:33 +00:00
.git-blame-ignore-revs [infra] Update .git-blame-ignore-revs 2020-03-03 12:59:13 +00:00
.gitattributes .gitattributes: Mark minified emscripten js files as -diff 2018-09-19 16:27:10 +00:00
.gitignore [cleanup] Add .idea to .gitignore 2022-08-22 19:54:38 +00:00
.gn [fuchsia] Add API target level default value 2022-08-29 14:46:45 +00:00
.mailmap Add .mailmap entries for jgruber 2022-08-04 08:53:02 +00:00
.style.yapf [tools] Add basic pointer compression to grokdump 2022-02-04 14:35:26 +00:00
.vpython3 Reland "[resultdb] Add ResultDB indicator" 2022-10-14 11:05:59 +00:00
.ycm_extra_conf.py [ycm] Fix python script 2021-07-29 09:48:32 +00:00
AUTHORS [profiler] add Serialize to v8::CpuProfile 2022-10-25 10:49:04 +00:00
BUILD.bazel [profiler] add Serialize to v8::CpuProfile 2022-10-25 10:49:04 +00:00
BUILD.gn [profiler] add Serialize to v8::CpuProfile 2022-10-25 10:49:04 +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 [owners] Add mliedtke to COMMON_OWNERS 2022-09-16 14:12:27 +00:00
DEPS Update V8 DEPS (trusted) 2022-10-27 03:53:41 +00:00
DIR_METADATA Add DIR_METADATA files to v8. 2020-10-20 22:12:28 +00:00
ENG_REVIEW_OWNERS Add mlippautz@ to ENG_REVIEW_OWNERS. 2022-10-06 18:48:33 +00:00
INFRA_OWNERS [infra] Add alexschulze@ as infra owner 2022-07-18 09:08:54 +00:00
INTL_OWNERS add ftang as owner 2020-04-24 19:19:36 +00:00
LICENSE [mips32] Delete mips32 from v8 2022-09-13 07:54:54 +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
LOONG_OWNERS [LOONG64] Add LoongArch64 backend 2021-08-16 13:05:19 +00:00
MIPS_OWNERS [mips] Add LiuYu to MIPS_OWNERS 2021-09-08 01:38:52 +00:00
OWNERS Reland "[riscv32] Add RISCV32 backend" 2022-08-04 12:47:44 +00:00
PPC_OWNERS Adding myself to relevant OWNERS files. 2020-11-02 16:37:28 +00:00
PRESUBMIT.py [wasm] Limit module size in streaming decoder 2022-07-08 09:43:41 +00:00
README.md [docs] Change links from old wiki to v8.dev 2019-03-07 12:13:30 +00:00
RISCV_OWNERS Add Lu Yahan to RISC-V owners list 2021-09-13 16:35:00 +00:00
S390_OWNERS Adding myself to relevant OWNERS files. 2020-11-02 16:37:28 +00:00
WATCHLISTS Reland "[WATCHLISTS] Add riscv watch" 2022-08-19 07:33:57 +00:00
WORKSPACE [bazel] Remove zlib dependency 2022-08-17 15:30:25 +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.