Chromium Blog: Irregexp, Google Chrome's New Regexp Implementation

Chromium Blog

News and developments from the open source browser project

Irregexp, Google Chrome's New Regexp Implementation

Wednesday, February 4, 2009

One of the new features in the most recent dev-channel release of Google Chrome (2.0.160.0) is Irregexp, a completely new implementation of regular expressions (regexps) in the V8 JavaScript engine. Irregexp builds on V8's existing infrastructure for memory management and native code generation and is tailored to work well for the kinds of regexps used by JavaScript programs on the web. The result is a considerable improvement in V8's regexp performance.
While the V8 team has been working hard to improve JavaScript performance, one part of the language that we have so far not given much attention is regexps. Our previous implementation was based on the widely used PCRE library developed by Philip Hazel at the University of Cambridge. The version we used, known as JSCRE, was adapted and improved by the WebKit project for use with JavaScript. Using JSCRE gave us a regular expression implementation that was compatible with industry standards and has served us well. However, as we've improved other parts of the language, regexps started to stand out as being slower than the rest. We felt it should be possible to improve performance by integrating with our existing infrastructure rather than using an external library. The SquirrelFish team is following a similar approach with their JavaScript engine.
A fundamental decision we made early in the design of Irregexp was that we would be willing to spend extra time compiling a regular expression if that would make running it faster. During compilation Irregexp first converts a regexp into an intermediate automaton representation. This is in many ways the "natural" and most accessible representation and makes it much easier to analyze and optimize the regexp. For instance, when compiling /Sun|Mon/ the automaton representation lets us recognize that both alternatives have an 'n' as their third character. We can quickly scan the input until we find an 'n' and then start to match the regexp two characters earlier. Irregexp looks up to four characters ahead and matches up to four characters at a time.
After optimization we generate native machine code which uses backtracking to try different alternatives. Backtracking can be time-consuming so we use optimizations to avoid as much of it as we can. There are techniques to avoid backtracking altogether but the nature of regexps in JavaScript makes it difficult to apply them in our case, though it is something we may implement in the future.
During development we have tested Irregexp against one million of the most popular webpages to ensure that the new implementation stays compatible with our previous implementation and the web. We have also used this data to create a new benchmark which is included in version 3 of the V8 Benchmark Suite. We feel this is a good reflection of what is found on the web.
If you want to try this out, and help us test it in the process, you can subscribe to the dev-channel and if you see problems that might be related to Irregexp consider filing a bug.
And BTW, we'll have sessions on V8 and other Chrome-related topics in May at Google I/O, Google's largest developer conference.
Posted by Erik Corry, Christian Plesner Hansen and Lasse Reichstein Holst Nielsen, Software Engineers

Google

Labels

$200K 1
10th birthday 4
abusive ads 1
abusive notifications 2
accessibility 3
ad blockers 1
ad blocking 2
advanced capabilities 1
android 2
anti abuse 1
anti-deception 1
background periodic sync 1
badging 1
benchmarks 1
beta 83
better ads standards 1
billing 1
birthday 4
blink 2
browser 2
browser interoperability 1
bundles 1
capabilities 6
capable web 1
cds 1
cds18 2
cds2018 1
chrome 35
chrome 81 1
chrome 83 2
chrome 84 2
chrome ads 1
chrome apps 5
Chrome dev 1
chrome dev summit 1
chrome dev summit 2018 1
chrome dev summit 2019 1
chrome developer 1
Chrome Developer Center 1
chrome developer summit 1
chrome devtools 1
Chrome extension 1
chrome extensions 3
Chrome Frame 1
Chrome lite 1
Chrome on Android 2
chrome on ios 1
Chrome on Mac 1
Chrome OS 1
chrome privacy 4
chrome releases 1
chrome security 10
chrome web store 32
chromedevtools 1
chromeframe 3
chromeos 4
chromeos.dev 1
chromium 9
cloud print 1
coalition 1
coalition for better ads 1
contact picker 1
content indexing 1
cookies 1
core web vitals 2
csrf 1
css 1
cumulative layout shift 1
custom tabs 1
dart 8
dashboard 1
Data Saver 3
Data saver desktop extension 1
day 2 1
deceptive installation 1
declarative net request api 1
design 2
developer dashboard 1
Developer Program Policy 2
developer website 1
devtools 13
digital event 1
discoverability 1
DNS-over-HTTPS 4
DoH 4
emoji 1
emscriptem 1
enterprise 1
extensions 27
Fast badging 1
faster web 1
features 1
feedback 2
field data 1
first input delay 1
Follow 1
fonts 1
form controls 1
frameworks 1
fugu 2
fund 1
funding 1
gdd 1
google earth 1
google event 1
google io 2019 1
google web developer 1
googlechrome 12
harmful ads 1
html5 11
HTTP/3 1
HTTPS 4
iframes 1
images 1
incognito 1
insecure forms 1
intent to explain 1
ios 1
ios Chrome 1
issue tracker 3
jank 1
javascript 5
lab data 1
labelling 1
largest contentful paint 1
launch 1
lazy-loading 1
lighthouse 2
linux 2
Lite Mode 2
Lite pages 1
loading interventions 1
loading optimizations 1
lock icon 1
long-tail 1
mac 1
manifest v3 2
metrics 2
microsoft edge 1
mixed forms 1
mobile 2
na 1
native client 8
native file system 1
New Features 5
notifications 1
octane 1
open web 4
origin trials 2
pagespeed insights 1
pagespeedinsights 1
passwords 1
payment handler 1
payment request 1
payments 2
performance 20
performance tools 1
permission UI 1
permissions 1
play store 1
portals 3
prefetching 1
privacy 2
privacy sandbox 4
private prefetch proxy 1
profile guided optimization 1
progressive web apps 2
Project Strobe 1
protection 1
pwa 1
QUIC 1
quieter permissions 1
releases 3
removals 1
rlz 1
root program 1
safe browsing 2
Secure DNS 2
security 36
site isolation 1
slow loading 1
sms receiver 1
spam policy 1
spdy 2
spectre 1
speed 4
ssl 2
store listing 1
strobe 2
subscription pages 1
suspicious site reporter extension 1
TCP 1
the fast and the curious 23
TLS 1
tools 1
tracing 1
transparency 1
trusted web activities 1
twa 2
user agent string 1
user data policy 1
v8 6
video 2
wasm 1
web 1
web apps 1
web assembly 2
web developers 1
web intents 1
web packaging 1
web payments 1
web platform 1
web request api 1
web vitals 1
web.dev 1
web.dev live 1
webapi 1
webassembly 1
webaudio 3
webgl 7
webkit 5
WebM 1
webmaster 1
webp 5
webrtc 6
websockets 5
webtiming 1
writable-files 1
yerba beuna center for the arts 1

Feed

Give us feedback in our Product Forums.

Google
Privacy
Terms

Chromium Blog

Irregexp, Google Chrome's New Regexp Implementation

Labels

Archive

Feed