Methodology

Andreas Jaeger has kindly tested our code on industrial standard SPECint2000 benchmark suite. It contains several commonly used programs--for instance the perl interpreter, old version of GCC itself, chess playing program crafty, gzip and bzip compression programs and more. The detailed information about the product can be found at http://www.spec.org.

The SPECint2000 is highly memory bound as programs usually operate on data set of about 200MB in size and the code segments are also quite large making these results conservative estimation of our contribution.

Since we integrated our changes to mainline GCC tree containing changes from many other developers and also merged all changes happening in mainline to our development tree, there is no version of GCC without our changes comparable with our cfg-branch version available.

We decided to benchmark only the benefits of profile based optimizations, as these can be easily disabled. This is again just a conservative approximation of our work.

We also benchmarked GCC with two different sets of options. The -O2 -march=athlon commonly used by developers and with aggressive optimizations enabled -O3 -fomit-frame-pointer -march=athlon -funroll-all-loops
-fstrict-aliasing -malign-double -fprefetch-loop-arrays. These flags were chosen to test as many features of GCC as possible, not to produce best performing code, and they are used by Andreas' automated tester to monitor GCC performance for almost a year now.