#12506: Compile time regression in GHC 8. -------------------------------------+------------------------------------- Reporter: deech | Owner: bgamari Type: bug | Status: new Priority: high | Milestone: Component: Compiler | Version: 8.0.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Compile-time | Unknown/Multiple performance bug | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by tdammers): OK, got it compiled against GHC head. The output of `-ddump-timings` shows two obvious suspects: {{{ [5 of 5] Compiling Main ( app/Main.hs, app/Main.o ) *** Parser [Main]: Parser [Main]: alloc=14721280 time=9.927 *** Renamer/typechecker [Main]: Renamer/typechecker [Main]: alloc=585898184 time=956.617 *** Desugar [Main]: Desugar [Main]: alloc=76966472 time=214.242 *** Simplifier [Main]: Simplifier [Main]: alloc=3469053424 time=2430.489 *** CoreTidy [Main]: CoreTidy [Main]: alloc=220130032 time=371.644 *** CorePrep [Main]: CorePrep [Main]: alloc=7744 time=0.030 *** CodeGen [Main]: CodeGen [Main]: alloc=3436008728 time=4730.477 Linking app/Main ... }}} In other words, while compiling `Main`, we get very long timings on the Simplifier and CodeGen steps. I suspect that the latter is caused by the former. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12506#comment:20 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler