#13639: Skylighting package compilation is glacial -------------------------------------+------------------------------------- Reporter: bgamari | Owner: dfeuer Type: bug | Status: new Priority: normal | Milestone: 8.4.1 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 niteria): This bisects to a6e13d502ef46de854ec1babcd764ccce68c95e3, meaning that commit fixes the underlying problem. I cherry-picked it onto our `ghc-8.0.2-facebook` branch and the compile times are reasonable (~2min as opposed to >30m). I minified the original code to Skylighting.Syntax.Php.hs file that I'm attaching. It's boils down to a large `[Text]` list. With a commit before the fix there's a big blow up in the term size after one of the simplifier passes. After the fix the term sizes look reasonable. Relevant part of `-ddump-show-phases` (this is the released GHC 8.0.2, but the numbers are the the same before the fix): {{{ !!! Parser [Skylighting.Syntax.Php]: finished in 4556.00 milliseconds, allocated 87.667 megabytes [99/1907] *** Renamer/typechecker [Skylighting.Syntax.Php]: !!! Renamer/typechecker [Skylighting.Syntax.Php]: finished in 27009.00 milliseconds, allocated 241.752 megabytes *** Desugar [Skylighting.Syntax.Php]: Result size of Desugar (after optimization) = {terms: 16,197, types: 6,490, coercions: 0} !!! Desugar [Skylighting.Syntax.Php]: finished in 2024.00 milliseconds, allocated 22.967 megabytes *** Simplifier [Skylighting.Syntax.Php]: Result size of Simplifier iteration=1 = {terms: 22,671, types: 19,426, coercions: 0} Result size of Simplifier = {terms: 22,671, types: 19,426, coercions: 0} !!! Simplifier [Skylighting.Syntax.Php]: finished in 14080.00 milliseconds, allocated 150.808 megabytes *** Specialise [Skylighting.Syntax.Php]: Result size of Specialise = {terms: 22,678, types: 19,437, coercions: 2} !!! Specialise [Skylighting.Syntax.Php]: finished in 5593.00 milliseconds, allocated 32.625 megabytes *** Float out(FOS {Lam = Just 0, Consts = True, OverSatApps = False}) [Skylighting.Syntax.Php]: Result size of Float out(FOS {Lam = Just 0, Consts = True, OverSatApps = False}) = {terms: 48,542, types: 58,233, coercions: 2} !!! Float out(FOS {Lam = Just 0, Consts = True, OverSatApps = False}) [Skylighting.Syntax.Php]: finished in 8951.00 milliseconds, allocated 126.301 megabytes *** Simplifier [Skylighting.Syntax.Php]: Result size of Simplifier iteration=1 = {terms: 45,307, types: 55,000, coercions: 0} Result size of Simplifier = {terms: 45,307, types: 55,000, coercions: 0} !!! Simplifier [Skylighting.Syntax.Php]: finished in 36008.00 milliseconds, allocated 394.685 megabytes *** Simplifier [Skylighting.Syntax.Php]: Result size of Simplifier iteration=1 = {terms: 55,006, types: 55,000, coercions: 0} Result size of Simplifier = {terms: 42,074, types: 22,670, coercions: 0} !!! Simplifier [Skylighting.Syntax.Php]: finished in 44152.00 milliseconds, allocated 564.940 megabytes *** Simplifier [Skylighting.Syntax.Php]: Result size of Simplifier iteration=1 = {terms: 1,060,469, types: 775,959, coercions: 193,980} Result size of Simplifier iteration=2 = {terms: 944,081, types: 824,454, coercions: 171,349} Result size of Simplifier iteration=3 = {terms: 827,693, types: 624,008, coercions: 38,796} Result size of Simplifier iteration=4 }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13639#comment:7 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler