Hardest technical problem would have to be my PhD. I worked out how to apply alias analysis to PHP (previously people had figured out how to do it for the easy

Hardest technical problem would have to be my PhD. I worked out how to apply alias analysis to PHP (previously people had figured out how to do it for the easy subset of PHP - I extended it to the entire language of PHP 5.3 or so). [1] Along the way I'm pretty sure I also figured out how to build SSA form such that you have your alias analysis results available to be used at SSA construction and therefore redundant computation [2]. I never got to chase that down but it was really interesting. [1] http://paulbiggar.com/research/#phd-dissertation http://paulbiggar.com/research/#phd-dissertation, esp chapter 6. [2] http://paulbiggar.com/research/#fit-2009 http://paulbiggar.com/research/#fit-2009