I've put at http://www.math.purdue.edu/~lucier/bugzilla/9/
some compile-time and run-time statistics related to PR 39157 and PR 33928 and compile times and run times for the programs in the Gambit Scheme benchmark suite. The statistics are for 4.1.2 release, 4.2.4 release, 4.3.3 release, 4.4.1 20090522, 4.5.0 20090521 (revision 147758), and 4.5.0 20090521 (revision 147758) with -fno-forward-propagate; they use (mainly) the set of options -O1 -fno-math-errno -fschedule-insns2 -fno-trapping-math -fno-strict-aliasing -fwrapv -fomit-frame-pointer -fPIC -fno-common -mieee-fp on a Core 2 quad processor (running basically nothing else at the time). I would conclude from the statistics that, right now, the cost of including -fforward-propagate in -O1 overrides any performance benefit that may result. Brad
