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Tobias Tebbi cd33ec5542 [runtime] avoid trim/grow loop when adding and removing one element
We currently grow the backing store to (old_capacity*1.5)+16 if we exceed capacity, 
but shrink the capacity to the current length when 2*length <= capacity.
For short arrays (up to length 32), this can lead to a copy on every operation when using push/pop or push/shift.

Example:
Array of length 32, capacity 32
push
Array grown to length 33, capacity 32*1.5+16 = 64
pop
Array trimmed to length 32, capacity 32 because 2*32 <= 64
...

This CL leaves additional slag space when calling pop and restricts the trimming to backing stores with at least 16 elements to prevent excessive re-trimming on short arrays.

Bug: 
Change-Id: I9dd13e5e2550c7ac819294c8e29f04c8855e02a4
Reviewed-on: https://chromium-review.googlesource.com/502911
Commit-Queue: Tobias Tebbi <tebbi@chromium.org>
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Cr-Commit-Position: refs/heads/master@{#45324}
2017-05-16 08:56:30 +00:00
benchmarks Revert "Refactoring: Make gtest testsuite the default." 2014-09-02 09:17:26 +00:00
build_overrides Remove build_overrides/v8.gni. 2017-01-26 20:18:58 +00:00
docs [Docs] Removed unused docs because they are moved to GitHub 2015-11-19 10:23:30 +00:00
gni [build] Remove remaining disable-inspector options in GN 2017-04-05 17:59:07 +00:00
gypfiles [build] Disable strict-overflow check on gcc 2017-05-04 13:36:39 +00:00
include Fix V8_NORETURN for MSVC 2017-05-15 13:33:59 +00:00
infra [CQ] Make linux64 gcc debug bot mandatory 2017-05-11 10:02:10 +00:00
samples Reland of land "Turn libbase into a component" (patchset #1 id:1 of https://codereview.chromium.org/2396933002/ ) 2016-10-07 07:56:52 +00:00
src [runtime] avoid trim/grow loop when adding and removing one element 2017-05-16 08:56:30 +00:00
test [json] Specialize parsed arrays to most specific elements kind 2017-05-16 08:53:17 +00:00
testing Use GTEST_LANG_CXX11 in V8 2016-07-25 13:06:42 +00:00
third_party Roll third_party/inspector_protocol to efefa86c3183d307f0a0e53bf568fe57c5b58849 2017-04-28 01:43:03 +00:00
tools [foozzie] Fix detection of suppression delimiter 2017-05-16 07:39:24 +00:00
.clang-format [clang-format] Don't derive pointer alignment 2017-01-17 09:28:19 +00:00
.gitignore [wasm] Move the wasm fuzzer corpus to a different directory 2017-04-28 23:29:41 +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
.ycm_extra_conf.py Use C++11 / gnu++11, not 0x 2016-03-22 15:24:43 +00:00
AUTHORS Migrate Number constants and undefined to C++ 2017-02-27 08:20:45 +00:00
BUILD.gn [ignition] Introduce Switch bytecode for generators 2017-05-15 17:43:17 +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 Use v8-reviews@ for review mail, so v8-dev@ is free for dev discussions 2015-09-09 08:14:11 +00:00
DEPS Update V8 DEPS. 2017-05-16 03:34:09 +00:00
DEPS.chromium Add DEPS.chromium for recursive DEPS tracking. 2017-05-15 15:23:48 +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 Introduce mkgrokdump to update tools/v8heapconst.py. 2017-04-20 06:15:02 +00:00
Makefile.android [build] Fix d8-for-Android builds 2016-05-20 12:10:45 +00:00
OWNERS Update to OWNER files. 2017-03-21 10:01:16 +00:00
PRESUBMIT.py Reland "Make unittest link correctly again" 2017-05-03 10:44:07 +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 Use clang for snapshot_toolchain by default, except on ChromeOS. 2016-08-23 14:04:27 +00:00
WATCHLISTS [watchlists] Added parser watchlist. 2017-05-03 12:30:13 +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://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.