Hello all, In the context of https://github.com/ghc-proposals/ghc-proposals/pull/500, I am looking for a strategy to measure the impact of resolving modules dependencies using a lexical scan during the downsweep phase. For example, in this branch: https://gitlab.haskell.org/TristanCacqueray/ghc/-/tree/make-lexical-analysis I've added a tokenizer pass in the GHC.Driver.Make.getPreprocessedImports function, and using `/usr/bin/time -o /dev/stdout -v _build/stage1/bin/ghc compiler/GHC/Tc/TyCl.hs 2> /dev/null` I measure: LexicalAnalysis found 91 qualified name, and lasted: 150msec Elapsed (wall clock) time (h:mm:ss or m:ss): 0:00.72 Maximum resident set size (kbytes): 142396 Using a clean build I get: Elapsed (wall clock) time (h:mm:ss or m:ss): 0:00.68 Maximum resident set size (kbytes): 140012 Now my question is, how would you measure the time and space cost of such change. For example, what profiling tool would you recommend and how can I test a modified ghc to build ghc itself? Thanks in advance, -Tristan