[GHC] #14738: Investigate performance of CoreTidy
#14738: Investigate performance of CoreTidy -------------------------------------+------------------------------------- Reporter: tdammers | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.2 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Compile-time Unknown/Multiple | performance bug Test Case: | Blocked By: Blocking: | Related Tickets: #11735 #14683 Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Considering the following profile output (compiling [https://ghc.haskell.org/trac/ghc/attachment/ticket/14683/Grammar.hs]): {{{ Thu Jan 25 13:11 2018 Time and Allocation Profiling Report (Final) ghc-stage2 +RTS -p -RTS -B/home/tobias/well- typed/devel/ghc/inplace/lib Grammar.hs -ddump-stg -ddump-simpl -ddump-to- file -fforce-recomp total time = 20.99 secs (20989 ticks @ 1000 us, 1 processor) total alloc = 29,250,375,256 bytes (excludes profiling overheads) COST CENTRE MODULE SRC %time %alloc CoreTidy HscMain compiler/main/HscMain.hs:1253:27-67 24.2 28.5 Stg2Stg HscMain compiler/main/HscMain.hs:1489:12-44 20.3 24.2 simplCast Simplify compiler/simplCore/Simplify.hs:871:62-87 18.7 15.9 tc_rn_src_decls TcRnDriver compiler/typecheck/TcRnDriver.hs:(494,4)-(556,7) 9.0 6.9 addCoerce-pushCoTyArg Simplify compiler/simplCore/Simplify.hs:(1236,12)-(1237,72) 7.4 6.4 subst_ty TyCoRep compiler/types/TyCoRep.hs:2237:28-32 4.3 5.1 zonkTopDecls TcRnDriver compiler/typecheck/TcRnDriver.hs:(445,16)-(446,43) 1.4 1.1 coercionKind Coercion compiler/types/Coercion.hs:1725:3-7 1.3 3.0 simplExprF1-Lam Simplify compiler/simplCore/Simplify.hs:896:5-39 1.0 1.1 }}} ...the amount of time spent in `CoreTidy` is striking, and should be investigated. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14738 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#14738: Investigate performance of CoreTidy -------------------------------------+------------------------------------- Reporter: tdammers | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Compile-time | Unknown/Multiple performance bug | Test Case: Blocked By: | Blocking: Related Tickets: #11735 #14683 | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by tdammers): * cc: tdammers (added) -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14738#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#14738: Investigate performance of CoreTidy -------------------------------------+------------------------------------- Reporter: tdammers | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Compile-time | Unknown/Multiple performance bug | Test Case: Blocked By: | Blocking: Related Tickets: #11735 #14683 | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by tdammers): The problem seems to mysteriously go away on newer commits. Adding more cost centres to GHC HEAD, I've found that `CoreTidy` hardly shows up in the profile at all, and practically all the remaining slowdown comes from code in `Simplify.hs`, which I believe #14737 is about. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14738#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#14738: Investigate performance of CoreTidy -------------------------------------+------------------------------------- Reporter: tdammers | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Compile-time | Unknown/Multiple performance bug | Test Case: Blocked By: | Blocking: Related Tickets: #11735 #14683 | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by tdammers): Profile, based on GHC HEAD + some changes from #11735 + added SCCs, compiling `Grammar.hs`: {{{ Mon Feb 5 12:47 2018 Time and Allocation Profiling Report (Final) ghc-stage2 +RTS -p -RTS -B/home/tobias/well- typed/devel/ghc/inplace/lib Grammar.hs -fforce-recomp total time = 12.73 secs (12733 ticks @ 1000 us, 1 processor) total alloc = 14,413,041,648 bytes (excludes profiling overheads) COST CENTRE MODULE SRC %time %alloc addCoerce-pushCoTyArg Simplify compiler/simplCore/Simplify.hs:1234:70-90 46.7 45.7 tc_rn_src_decls TcRnDriver compiler/typecheck/TcRnDriver.hs:(494,4)-(556,7) 12.2 14.0 subst_ty TyCoRep compiler/types/TyCoRep.hs:2265:28-32 7.0 10.4 tidyTopBinds TidyPgm compiler/main/TidyPgm.hs:370:21-82 3.3 3.5 writeIface HscMain compiler/main/HscMain.hs:1279:9-45 3.2 0.2 coercionKind Coercion compiler/types/Coercion.hs:1735:3-7 3.0 6.0 zonkTopDecls TcRnDriver compiler/typecheck/TcRnDriver.hs:(445,16)-(446,43) 2.1 2.2 simplExprF1-Lam Simplify compiler/simplCore/Simplify.hs:896:5-39 1.7 2.2 simplCast-simplCoercion Simplify compiler/simplCore/Simplify.hs:1224:57-77 1.6 1.5 deSugar HscMain compiler/main/HscMain.hs:511:7-44 1.5 1.3 findExternalRules TidyPgm compiler/main/TidyPgm.hs:366:23-77 1.1 0.2 Parser HscMain compiler/main/HscMain.hs:(316,5)-(384,20) 1.1 1.6 simplIdF Simplify compiler/simplCore/Simplify.hs:868:61-79 1.0 0.5 simplCast-addCoerce Simplify compiler/simplCore/Simplify.hs:1225:53-71 1.0 1.0 }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14738#comment:3 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
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