#9203: Perf regression in 7.8.2 relative to 7.6.3, possibly related to HashMap --------------------------------------------+------------------------------ Reporter: simonmar | Owner: Type: bug | Status: merge Priority: high | Milestone: 7.8.3 Component: Compiler | Version: 7.8.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Runtime performance bug | Unknown/Multiple Test Case: | Difficulty: Unknown Blocking: | Blocked By: | Related Tickets: --------------------------------------------+------------------------------ Comment (by simonmar): Simon: I don't think you added a comment on Phabricator (you probably need to click the big button at the bottom of the page). I've been digging a bit more into this: it turns out we had fixed this once before, see #3245, and there was even a big Note in the code that was *removed* by Pedro in 3d53407f9c6e87bcff30d51f0a048e92b2745a32. There's also a perf test (`testsuite/tests/perf/should_run/T3245.hs`), but that didn't trigger because (a) there are no bounds defined for it in all.T, and (b) that test doesn't trigger the bug any more anyway. I'm going to add a new perf test, and some comments to `Internal.hs`. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9203#comment:8 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler