What tools are there for facilitating comparisons of ghc's debug output? I have reduced a performance problem in my code to a case where switching two lines of code doubles or halves the performance (the results of those lines are stored in record fields that never get used in this reduced example.., see ghc trac ticket #2463). So it should be easy to take the outputs of -ddump-simpl, etc. for both variants and run them through a diff viewer, but there are way too many irrelevant differences and details. 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?-) Also, it might be useful if one could translate the transformed code back to highlevel (ghc-)Haskell that would generate the same low-level code (ie, pretending that the source-to-source transformations actually happened at source level). Not only would that blend out irrelevant details, it would also give a direct indication of how to modify the source to get better performing code. What tools are there, and which do you use/recommend for tasks like this? Thanks, Claus