7d231e576a
Instead of having one method for 32 bit integers and one for 64 bit,
plus a templatized version to choose from those two, just implement one
version which handles unsigned integers of any size. Also, make them
constexpr.
The Count{Leading,Trailing}Zeros{32,64} methods are kept for now in
order to keep the amount of code changes small. Also, sometimes it
improves readability by stating exactly the size of the argument,
especially for leading zeros (where zero-extending would add more
leading zeros).
CountLeadingZeros now uses a binary search inspired implementation
as proposed in Hacker's Delight. It's more than 20% faster on x64 if
the builtins are disabled.
CountTrailingZeros falls back to CountPopulation instead of counting in
a naive loop. This is ~50% faster.
R=mstarzinger@chromium.org
Change-Id: I1d8bf1d7295b930724163248150444bd17fbb34e
Reviewed-on: https://chromium-review.googlesource.com/741231
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49106}
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| build_overrides | ||
| docs | ||
| gni | ||
| gypfiles | ||
| include | ||
| infra | ||
| samples | ||
| src | ||
| test | ||
| testing | ||
| third_party | ||
| tools | ||
| .clang-format | ||
| .editorconfig | ||
| .git-blame-ignore-revs | ||
| .gitignore | ||
| .gn | ||
| .vpython | ||
| .ycm_extra_conf.py | ||
| AUTHORS | ||
| BUILD.gn | ||
| ChangeLog | ||
| CODE_OF_CONDUCT.md | ||
| codereview.settings | ||
| DEPS | ||
| LICENSE | ||
| LICENSE.fdlibm | ||
| LICENSE.strongtalk | ||
| LICENSE.v8 | ||
| LICENSE.valgrind | ||
| Makefile | ||
| Makefile.android | ||
| OWNERS | ||
| PRESUBMIT.py | ||
| README.md | ||
| snapshot_toolchain.gni | ||
| WATCHLISTS | ||
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://github.com/v8/v8/wiki
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 on the V8 wiki.