e1dbe835d7
The way to determine whether a MaybeObject is a strong or weak
reference to the heap object is to check its lowest two bits.
However, if the MaybeObject is known to not be a smi, that is, the
lowest bit is known to be 1, we can check one bit instead. This
allows Turbofan to select better instructions:
x64:
Before:
movl r9,r11
andl r9,0x3
cmpb r9l,0x1
After:
testb r11,0x2
arm64:
Before:
and w8, w7, #0x3
cmp w8, #0x1 (1)
b.ne #+0x320
After:
tbnz w7, #1, #+0x320
Change-Id: I03623183406ad7d920c96a752651e0116a22832e
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3861310
Reviewed-by: Nico Hartmann <nicohartmann@chromium.org>
Commit-Queue: Hao A Xu <hao.a.xu@intel.com>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/main@{#83153}
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|---|---|---|
| .github | ||
| bazel | ||
| build_overrides | ||
| custom_deps | ||
| docs | ||
| gni | ||
| include | ||
| infra | ||
| samples | ||
| src | ||
| test | ||
| testing | ||
| third_party | ||
| tools | ||
| .bazelrc | ||
| .clang-format | ||
| .clang-tidy | ||
| .editorconfig | ||
| .flake8 | ||
| .git-blame-ignore-revs | ||
| .gitattributes | ||
| .gitignore | ||
| .gn | ||
| .mailmap | ||
| .style.yapf | ||
| .vpython | ||
| .vpython3 | ||
| .ycm_extra_conf.py | ||
| AUTHORS | ||
| BUILD.bazel | ||
| BUILD.gn | ||
| CODE_OF_CONDUCT.md | ||
| codereview.settings | ||
| COMMON_OWNERS | ||
| DEPS | ||
| DIR_METADATA | ||
| ENG_REVIEW_OWNERS | ||
| INFRA_OWNERS | ||
| INTL_OWNERS | ||
| LICENSE | ||
| LICENSE.fdlibm | ||
| LICENSE.strongtalk | ||
| LICENSE.v8 | ||
| LOONG_OWNERS | ||
| MIPS_OWNERS | ||
| OWNERS | ||
| PPC_OWNERS | ||
| PRESUBMIT.py | ||
| README.md | ||
| RISCV_OWNERS | ||
| S390_OWNERS | ||
| WATCHLISTS | ||
| WORKSPACE | ||
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.