I seem to recall someone mentioning a tool for normalizing the output of things like -ddump-simpl to make diffs easier by reducing irrelevant differences due to gensym-generated names. Was that just wishful thinking, or does such a thing exist?-)
I would also find such a tool very useful, but to the best of my knowledge there's nothing out there yet.
Surprising - how do all of you optimization tuners manage without?
You can get quite far by using the -dsuppress-uniques flag, which removes irrelevant differences due solely to the unique numbers assigned to names. However, I've found that diff output from that is still hard to deal with because GHC reorders functions in the Core output under some circumstances. I've been meaning to find the time to try and fix this.
Thanks. Simon PJ also mentioned that (undocumented?) flag, but I must be using it wrong, because ghc --make -O2 Main.hs -dsuppress-uniques -ddump-simpl >simpl-slow still gives me plenty of _labels in the output (6.9.20080514). How is this flag supposed to be used? I've had some success by simply doing a brute-force #s/_[^ _]*\>//g' over the files before diffing, to remove anything that looks like a final addon-label. That isn't quite right (__inline_me becomes __inline, etc), but at least it helps to fold away lots of unwanted detail. Claus