67f3018510
There is no fast path for 0-length substrings, which implied runtime
calls for some of the trickier types of strings (such as non-flat
cons-strings). This made for a big performance gap between
String.p.slice and String.p.substring for those inputs.
This CL just adds the 0-length shortcut in CSA implementation
of SubString.
Here is an example where it makes difference:
let s = "abcdefghijkalmnopqrst";
let a = "";
console.time("Substring");
for (let i = 0; i < 100000; i++) {
s += "0";
a += s.substring(0, 0);
}
console.timeEnd("Substring");
Before this change:
> console.timeEnd: Substring, 640.308000
After this change:
> console.timeEnd: Substring, 13.242000
For completeness, here is the time for slice:
> console.timeEnd: Slice, 13.142000
This also recovers performance in the jsdom library, as
observed in https://github.com/jsdom/jsdom/issues/2350.
Bug: v8:6730
Change-Id: I7d2127e4506a86ec2a7ed378293476c3699dc47a
Reviewed-on: https://chromium-review.googlesource.com/c/1365282
Commit-Queue: Jaroslav Sevcik <jarin@chromium.org>
Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#58071}
|
||
|---|---|---|
| benchmarks | ||
| build_overrides | ||
| custom_deps | ||
| docs | ||
| gni | ||
| include | ||
| infra | ||
| samples | ||
| src | ||
| test | ||
| testing | ||
| third_party | ||
| tools | ||
| .clang-format | ||
| .clang-tidy | ||
| .editorconfig | ||
| .git-blame-ignore-revs | ||
| .gitattributes | ||
| .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 | ||
| 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.