mwilliams
4842f4ee1d
While investigating why gcc-4.7.1 is slower than gcc-4.6.2, I noticed that under 4.6.2 the tbb code was being inlined into Unit::GetNamedEntity, but under 4.7.1 it wasn't. Perf showed that the inclusive time for GetNamedEntity was about .4% higher under gcc-4.7.1. Meanwhile, after various code changes, gcc-4.6.2 is no longer inlining the tbb code either. Playing with the inlining options, I wasnt able to get either version of gcc to inline it anymore, but using __attribute__((__flatten__)) works for both. But that also causes a bunch of other, slow-path code to be inlined, so split it into a hot and a cold function, and flatten the hot function. Perf shows about a .2% win for Unit::GetNamedEntiry under gcc-4.6.2
HipHop VM for PHP
HipHop VM (HHVM) is a new open-source virtual machine designed for executing programs written in PHP. HHVM uses a just-in-time compilation approach to achieve superior performance while maintaining the flexibility that PHP developers are accustomed to. HipHop VM (and before it HPHPc) has realized >5x increase in throughput for Facebook compared with Zend PHP 5.2.
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