Saturday, December 25, 2010

Googland

Googland

[G] Battle of the Demos: Musical Holiday Edition

Posted: 24 Dec 2010 11:51 PM PST

Official Google Blog: Battle of the Demos: Musical Holiday Edition

Nothing brings out holiday spirit like caroling around town or sharing a good time with friends. But when you combine both of those fun activities with Google technology, Weezer, Greyson Chance, and Demo Slam, you get Battle of the Demos: Musical Holiday Edition.

This winter season, Weezer and Greyson Chance stepped to into the Demo Slam arena to show the world their most creative tech demos. We know they can both sing, but who will win in a battle of technology?

Spending his Christmas home in Oklahoma City, Greyson Chance figured he could combine Google Local Search and caroling to spread some musical cheer around town:



Weezer is known for their adoring fans (well, at least one adoring fan authoring this post). Check out this slam that gets the whole crowd involved:



Head over to demoslam.com to vote and help decide whether a voice search performed by 3,000 people or crooning through the streets of Oklahoma City will reign supreme.

Posted by Laura Melahn, Weezer Fan Club and Amanda Kelly, Greyson Chance Cheer Squad
URL: http://googleblog.blogspot.com/2010/12/battle-of-demos-musical-holiday-edition.html

[G] Notes from the 2010 LLVM Developers' Meeting

Posted: 24 Dec 2010 11:32 PM PST

Google Open Source Blog: Notes from the 2010 LLVM Developers' Meeting

My name is Lang Hames, and I am a PhD student at the University of Sydney where I research aggressive register allocation techniques. Last year I completed a six month internship with the LLVM team improving their register allocation infrastructure, and last month Google sponsored my attendance at the 2010 LLVM Developers' Meeting.

I had a fantastic time at the meeting. Californian hospitality always makes me feel right at home, and it was great to see all my friends from previous Dev Meetings and my internship with the LLVM team.

The meeting was huge this year, with over 190 attendees and such a abundance of talks it was impossible to make it around to everything on the day. It's a good thing the entire proceedings are up on the web. The talks this year were impressive and diverse, including introductions to major new LLVM-family projects, new applications leveraging LLVM technology, and targets ranging from GPUs to FPGAs.

A few of my favourite talks:

Doug Gregor, a member of the Clang team at Apple and code owner of the Clang libraries, gave a great talk on "libclang: Thinking Beyond the Compiler." (PDF) libclang is the Clang compiler's functionality packaged as a library. It lets you parse source, access diagnostics, examine ASTs and even find code completion targets. This raises the really exciting prospect of building new development tools on top of a feature complete front-end. Imagine having syntax highlighting, code-completion and cross-reference all handled by the same parser that's in the compiler. It's difficult to over-state how cool this is, and I say that as an optimization guy (I thought the front end was just there to feed me CFGs). I'd highly recommend checking out a copy of Clang and playing with it. Doug's talk included plenty of code snippets, and I've found reading through them to be a great way to get started.

Craig Silverstein of Google gave a talk on "Implementing Include-what-you-use Using Clang" (PDF). Include-what-you-use is the principle that C/C++ source files should directly #include header files that provide declarations/definitions that they use, rather than relying on transitive #includes. Building on Clang, Craig has developed a tool to analyse C++ code to detect and correct violations of this principle. This looks like a really handy and great example of what you can build on top of libclang.

Howard Hinnant of Apple introduced us to libc++ (PDF), a new C++ standard library built from the ground up with C++0x in mind. It has a lot of cool features, including fast default constructors, minimal memory footprints for default constructed objects, and fast move constructors. Dependence on libstdc++ is no barrier to trying it out: you can happily link your project against both libraries (libc++ uses inline namespaces to avoid confusion over ABI incompatible objects). One feature I thought was particularly neat was the adaptive sort: the sorting algorithms in libc++ automatically recognize partially sorted ranges and optimize their behavior to exploit the partial sorting for better performance. Howard's test cases showed impressive speedups (over 2x in a lot of cases). I'm really looking forward to trying this out in some of my code.

Greg Clayton, also of Apple, introduced LLDB (PDF), a debugger built on Clang and LLVM libraries. This looks incredible and deserves a blog post of its own, but I'll mention a few of my favorite features here. By building on libclang, LLDB is able to parse complex C++ expressions, up to and including multi-line expressions with local variables and control flow. It has been built from scratch to support a multicore, multithreaded world, with per-thread state and runtime control. Symbolic breakpoints allow you to set breakpoints with everything from File and Line to regular expressions (great for breaking on getters, setters, handlers, etc). Finally, following LLVM's design philosophy all this functionality will be available via a C-API, with python bindings provided too. Looks like another excellent base for new developer tools, and I can't wait to see what people do with it.

Other talks I particularly enjoyed included Nadav Rotem's talk (PDF) on using LLVM for C-to-Verilog synthesis (aka building circuits out of C-code). Nadav ran us though some of the optimizations necessary to prepare LLVM IR for efficient hardware synthesis. Xuejun Yang's talk, "Hardening LLVM with Random Testing" (PDF), was also fantastic. Xuejun's team have developed a system for generating expressive, unambiguous C programs with defined meanings which can be used to test compiler correctness. Since March, 2008 they've helped find and fix over 170 bugs in LLVM.

Slides and videos of the talks I mentioned, and many others, are available on the LLVM Dev Meeting 2010 website. I highly encourage you to check them out.

The Dev Meeting doesn't stop at the talks of course. It's an invaluable opportunity to meet and swap ideas with other LLVM developers. I got a chance to meet Jakob Olesen and Andy Trick, who have been doing great things with LLVM's register allocation framework (my PhD research area). I also chatted with some of the Google devs who are using Clang to tackle issues such as include-what-you-use in the Google codebase. Finally I attended "Birds of a Feather" meetings on LLVM optimizations, and on the progress that's been made (and plans for the future) in building Linux with Clang.

Many thanks to Google, Apple, Qualcomm, and the Qualcomm Innovation Center for making such an amazing event possible. I'd also like to add very special thank you to Google for sponsoring me to attend this event. At the end of the day I walked out amazed at what has been achieved in the last year, and how active the LLVM community has been. I look forward to trying out all these new tools for myself, and I can't wait for next year!

By Lang Hames, LLVM Developer
URL: http://google-opensource.blogspot.com/2010/12/notes-from-2010-llvm-developers-meeting.html

[G] Now on YouTube: googleOSPO

Posted: 24 Dec 2010 11:32 PM PST

Google Open Source Blog: Now on YouTube: googleOSPO

You may have noticed that this blog has been featuring more videos recently. Today we are launching a new YouTube channel, googleOSPO, to organize videos relating to Google and open source in one place. There are playlists of Google Tech Talks that feature open source projects, Googlers speaking at open source conferences, and of course original content like Jeremy Allison's Geek Time series.

In addition to our new channel, our student programs channel continues to grow with videos, screencasts, and presentations from our Google Summer of Code community. As the Google Code-in program wraps up, we hope to add more videos from those participants as well. Both channels will have content added on a regular basis, so subscribe if you don't want to miss anything!

By Ellen Ko, Open Source Team
URL: http://google-opensource.blogspot.com/2010/12/now-on-youtube-googleospo.html

[G] Happy holidays from AdSense

Posted: 24 Dec 2010 11:19 PM PST

Inside AdSense: Happy holidays from AdSense

Wishing you a very happy holidays from all of us in AdSense! Our team in Dublin is pictured below to send you extra season's greetings.



Posted by Katrina Kurnit - Inside AdSense team
URL: http://adsense.blogspot.com/2010/12/happy-holidays-from-adsense.html
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