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Clemens Hammacher 27ffc624ef Reland "[bits] Consolidate Count{Leading,Trailing}Zeros" 
This is a reland of 7d231e576a, fixed to
avoid instantiating CountLeadingZeros for bits==0.

Original change's description:
> [bits] Consolidate Count{Leading,Trailing}Zeros
> 
> 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}

Change-Id: Icdff2510ec66d1c96a1912cef29d77d8550994ee
Reviewed-on: https://chromium-review.googlesource.com/753903
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49138}
2017-11-06 11:55:44 +00:00
benchmarks Fix common misspellings 2017-08-02 09:35:28 +00:00
build_overrides Remove build_override for macOS min SDK and deployment target. 2017-07-14 18:24:44 +00:00
docs [Docs] Removed unused docs because they are moved to GitHub 2015-11-19 10:23:30 +00:00
gni [test] Fix isolate for auto-detect in gyp 2017-10-19 11:52:11 +00:00
gypfiles Reland "[heap] Temporarily disable concurrent marking." 2017-11-02 19:10:00 +00:00
include [cleanup] Fix typos 2017-11-06 11:15:04 +00:00
infra [CQ] Use non-luci fuchsia bots for cq experiment 2017-10-30 12:45:10 +00:00
samples [presubmit] Enable and fix "build/namespaces" linter check. 2017-09-04 11:24:26 +00:00
src Reland "[bits] Consolidate Count{Leading,Trailing}Zeros" 2017-11-06 11:55:44 +00:00
test Reland "[bits] Consolidate Count{Leading,Trailing}Zeros" 2017-11-06 11:55:44 +00:00
testing Use GTEST_LANG_CXX11 in V8 2016-07-25 13:06:42 +00:00
third_party Add colorama package to DEPS so that pylib can import it 2017-10-24 14:18:49 +00:00
tools Whitespace change to trigger bots 2017-11-04 20:34:31 +00:00
.clang-format [clang-format] Don't derive pointer alignment 2017-01-17 09:28:19 +00:00
.editorconfig Add .editorconfig 2017-07-28 13:39:24 +00:00
.git-blame-ignore-revs [build] Add DEPS formatting to hyper-blame 2017-10-09 14:08:45 +00:00
.gitignore Add colorama package to DEPS so that pylib can import it 2017-10-24 14:18:49 +00:00
.gn For building v8 using gn on aix_ppc64, linux_s390x and linux_ppc64(both LE and BE). 2017-05-12 01:35:09 +00:00
.vpython Add a comment for the VPython dep 2017-10-25 12:23:35 +00:00
.ycm_extra_conf.py Use C++11 / gnu++11, not 0x 2016-03-22 15:24:43 +00:00
AUTHORS [modules] Optimize import.meta in the interpreter 2017-10-20 20:31:49 +00:00
BUILD.gn Reland "[heap] Temporarily disable concurrent marking." 2017-11-02 19:10:00 +00:00
ChangeLog [Release] Update ChangeLog file 2016-02-17 21:29:09 +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
DEPS Update V8 DEPS. 2017-11-03 03:55:24 +00:00
LICENSE Updates to the license information of third party components. 2015-06-16 12:37:50 +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
Makefile [test] Continued test support for make targets 2017-10-20 15:01:51 +00:00
Makefile.android [build] Fix d8-for-Android builds 2016-05-20 12:10:45 +00:00
OWNERS Add eholk and gdeepti to toplevel owners 2017-08-12 07:07:29 +00:00
PRESUBMIT.py Add vpython verification presubmit 2017-11-03 10:39:56 +00:00
README.md [Docs] Removed unused docs because they are moved to GitHub 2015-11-19 10:23:30 +00:00
snapshot_toolchain.gni MIPS[64]: Add support for big endian build using GN 2017-06-02 15:02:18 +00:00
WATCHLISTS [V8Tracing] Add lpy@ and fmeawad@ into watchlist for tracing/. 2017-05-22 19:40:17 +00:00

README.md

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.