http://wiki.github.com/facebook/hiphop-php/

Unfortunately, D7's use of PDO doesn't work with HipHop's PDO implementation and there are some issues with the session array merging in includes/session.inc which you can hack around.

Generate files for HipHop's file list
<?php
$cache = apc_cache_info();
foreach($cache['cache_list'] as $file) {
    echo substr($file['filename'],27)."\n";
}
Compile
~> $HPHP_HOME/src/hphp/hphp --input-list=files.list -k 1 --log=3 \ 
   -v "AllDynamic=true" -v "AllVolatile=true" --force=1
creating temporary directory /tmp/hphp_H27LtS ...
parsing inputs...
Unable to stat file /home/rasmus/drupal.hiphop/system/image.gd.inc
Unable to stat file /home/rasmus/drupal.hiphop/sites/sites.php
parsing inputs took 0'02" (2924 ms) wall time
pre-optimizing...
pre-optimizing took 0'01" (1307 ms) wall time
inferring types...
inferring types took 0'02" (2528 ms) wall time
post-optimizing...
post-optimizing took 0'00" (699 ms) wall time
creating CPP files...
creating CPP files took 0'02" (2469 ms) wall time
saving code errors...
compiling and linking CPP files...

compiling and linking CPP files took 34'10" (2050431 ms) wall time
all files saved in /tmp/hphp_H27LtS ...
running hphp took 34'21" (2061375 ms) wall time
Argh! 34 minutes!

Run
~> cp /tmp/hphp_H27LtS/program .

~> ./program -m server -v "Server.SourceRoot=`pwd`" \ 
   -v "Server.DefaultDocument=index.php" -v "Log.Level=Verbose" \ 
   -v "Log.InjectedStackTrace=1"-c $HPHP_HOME/bin/mime.hdf
loading static content...
searching all files under source root...
analyzing 2753 files under source root...
..loaded 542822 bytes of css files
..loaded 77714 bytes of gif files
..loaded 80093 bytes of gz files
..loaded 68939 bytes of htm files
..loaded 22703 bytes of html files
..loaded 822 bytes of ico files
..loaded 448844 bytes of jpg files
..loaded 2038563 bytes of js files
..loaded 4534 bytes of ms files
..loaded 299153 bytes of png files
..loaded 24455 bytes of swf files
..loaded 83599 bytes of txt files
..loaded 1053 bytes of xml files
loaded 3693294 bytes of static content in total
loading static content took 0'02" (2576 ms) wall time
page server started
admin server started
all servers started
But, unfortunately it doesn't work: