#9400: poor performance when compiling modules with many Text literals at -O1 -------------------------------------+------------------------------------- Reporter: rwbarton | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.3 Keywords: | Operating System: Architecture: Unknown/Multiple | Unknown/Multiple Difficulty: Unknown | Type of failure: Compile- Blocked By: | time performance bug Related Tickets: #9370 | Test Case: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- (Spawned from #9370; see there for original discussion) Unpack the xmlhtml package and edit `src/Text/XmlHtml/HTML/Meta.hs` and remove the `OPTIONS_GHC` line at the top of the file that disables optimizations and build with `cabal buidl`. Then GHC takes ~1.5GB and over a minute to build this single module. Preliminary investigation indicates that Text's fromString and its constituent parts is being inlined repeatedly: {{{ Inlining done: Data.String.fromString Inlining done: Data.Text.$fIsStringText Inlining done: Data.Text.pack Inlining done: Data.Text.Internal.Fusion.unstream Inlining done: Data.Text.Internal.Fusion.Common.map Inlining done: Data.Text.Internal.Fusion.Common.streamList Inlining done: Data.Text.Internal.safe Inlining done: Data.Bits.$fBitsInt_$c.&. Inlining done: Data.Text.Internal.Fusion.Types.$WYield [ repeats ~4000 times ] }}} resulting in a very large intermediate program: {{{ *** Checking old interface for xmlhtml-0.2.3.2:Text.XmlHtml.HTML.Meta: [ 1 of 10] Compiling Text.XmlHtml.HTML.Meta ( src/Text/XmlHtml/HTML/Meta.hs, dist/build/Text/XmlHtml/HTML/Meta.o ) *** Parser: *** Renamer/typechecker: *** Desugar: Result size of Desugar (after optimization) = {terms: 26,260, types: 20,021, coercions: 0} *** Simplifier: Result size of Simplifier iteration=1 = {terms: 1,446,658, types: 953,432, coercions: 314,352} ... }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9400 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler