I reported this in https://ghc.haskell.org/trac/ghc/ticket/13604
On Thu, Aug 3, 2017 at 4:32 PM Evan Laforge <qdun...@gmail.com> wrote: > My program uses the GHC API to provide a REPL, and upgrading to 8.2.1 > broke that... well, just made it really slow. Where it used to > quickly load the compiled files, it now wants to recompile everything > as bytecode which makes 1s startup time go to 1m. The reason was it > now thinks flags have changed. I tracked it down to changes in > FlagChecker.hs, documented with > https://ghc.haskell.org/trac/ghc/ticket/11798 and > https://ghc.haskell.org/trac/ghc/ticket/10923, which add -fhpc and -O > to the tracked flags. -fhpc means loading tests in ghci can never > work, because ghci rejects the -fhpc flag, and likewise -O means ghci > can never load optimized files for the same reason. > > It seems like the easiest solution might be to just have ghci not > reject -fhpc and -O. Of course we could also revert those changes, > but they're justified in the trac tickets. > > Of course this means I'm loading optimized code together with bytecode > compiled code and maybe that's a bad thing (or for tests, -fhpc with > non-hpc). But I've been doing this for something like 7 years and > it's been fine. > > > Unrelatedly, I was hoping compiles would get faster, but they seem a > bit slower, from around 3m20s to around 4m :( I can track down > per-file timing changes if it would be interesting to someone. > > Also thanks to whoever put trac tickets in the comments, it makes it > really easy to find out why a change was made. > _______________________________________________ > Glasgow-haskell-users mailing list > Glasgow-haskell-users@haskell.org > http://mail.haskell.org/cgi-bin/mailman/listinfo/glasgow-haskell-users >
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