Simplifier and SpecConstr performance regression with 8.2.1
A proprietary application I've upgraded to compile with 8.2.1-rc1 makes GHC manifest a performance regression when producing optimized (-O2) code.
After a crude analysis of a compile log produced with -show-passes it appears that the biggest slowdown is in the Simplifier and SpecConstr phases when compiling the "main" modules.
Theres a conversation at GHC Users with more details: https://mail.haskell.org/pipermail/glasgow-haskell-users/2017-June/026543.html. The data, the results and the script to to analyse it live at: https://gist.github.com/albertov/145ac5c01bfbadc5c9ff55e9c5c2e50e
I'll try to update this ticket with a way to to reproduce it as soon as I can (if I can).