#14880: GHC panic: updateRole -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: goldfire Type: bug | Status: new Priority: normal | Milestone: Component: Compiler (Type | Version: 8.2.2 checker) | Resolution: | Keywords: TypeInType Operating System: Unknown/Multiple | Architecture: Type of failure: Compile-time | Unknown/Multiple crash or panic | Test Case: Blocked By: | Blocking: Related Tickets: #15076 | Differential Rev(s): Phab:D4769 Wiki Page: | -------------------------------------+------------------------------------- Comment (by tdammers): `-ddump-simpl` suggests the problem is not increased Core size; the output is practically identical. So I did a run with `+RTS -p`, and got this: {{{ Mon Jul 16 16:37 2018 Time and Allocation Profiling Report (Final) ghc-stage2 +RTS -p -RTS -B/home/tobias/well-typed/devel/ghc- phab/inplace/lib -c T5631.hs -fforce-recomp total time = 1.38 secs (1383 ticks @ 1000 us, 1 processor) total alloc = 1,208,527,080 bytes (excludes profiling overheads) COST CENTRE MODULE SRC %time %alloc tc_rn_src_decls TcRnDriver compiler/typecheck/TcRnDriver.hs:(491,4)-(553,7) 38.7 55.9 withCleanupSession.cleanup GHC compiler/main/GHC.hs:(468,4)-(475,37) 23.1 0.0 zonkTopDecls TcRnDriver compiler/typecheck/TcRnDriver.hs:(442,16)-(443,43) 7.0 8.7 CorePrep HscMain compiler/main/HscMain.hs:(1317,24)-(1318,57) 3.0 4.9 deSugar HscMain compiler/main/HscMain.hs:512:7-44 2.6 2.5 pprNativeCode AsmCodeGen compiler/nativeGen/AsmCodeGen.hs:(529,37)-(530,65) 2.4 1.8 CoreTidy HscMain compiler/main/HscMain.hs:1257:27-67 1.8 2.3 simplIdF Simplify compiler/simplCore/Simplify.hs:859:61-79 1.6 1.3 simplifyTop TcRnDriver compiler/typecheck/TcRnDriver.hs:409:25-39 1.4 2.2 Parser HscMain compiler/main/HscMain.hs:(317,5)-(385,20) 1.4 2.6 StgCmm HscMain compiler/main/HscMain.hs:(1432,13)-(1433,62) 1.3 1.0 }}} And then digging into the call graph analysis, this surprising bit: {{{ hscTypecheck HscMain compiler/main/HscMain.hs:(425,1)-(428,20) 1564 1 0.0 0.0 51.9 73.1 extract_renamed_stuff HscMain compiler/main/HscMain.hs:(397,1)-(410,31) 1640 1 0.0 0.0 0.0 0.0 hscTypecheck' HscMain compiler/main/HscMain.hs:(434,1)-(456,38) 1565 1 0.0 0.0 51.9 73.1 [...] tcRnModule' HscMain compiler/main/HscMain.hs:(461,1)-(500,72) 1570 1 0.0 0.0 50.5 70.5 Typecheck-Rename HscMain compiler/main/HscMain.hs:(464,16)-(465,73) 1571 1 0.0 0.0 50.5 70.5 ioMsgMaybe HscMain compiler/main/HscMain.hs:(251,1)-(256,122) 1572 1 0.4 0.8 50.5 70.5 }}} In other words, we spend 70% of our allocations on "dealing with errors and warnings returned by a compilation step". -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14880#comment:36 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler