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[GHC] #10474: Suggested options for "Use a bigger heap!" seem wrong
by GHC 03 Jun '15

03 Jun '15

#10474: Suggested options for "Use a bigger heap!" seem wrong -------------------------------------+------------------------------------- Reporter: ezyang | Owner: ezyang Type: bug | Status: new Priority: normal | Milestone: Component: | Version: 7.10.1 Documentation | Operating System: Unknown/Multiple Keywords: | Type of failure: Documentation Architecture: | bug Unknown/Multiple | Blocked By: Test Case: | Related Tickets: Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- In https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/faster.html we have guidance for how to use a bigger heap, which can speed up programs when they are spending too long in GC: > If your program's GC stats (-S RTS option) indicate that it's doing lots of garbage-collection (say, more than 20% of execution time), more memory might help—with the -M<size> or -A<size> RTS options (see Section 4.17.3, “RTS options to control the garbage collector”). The suggested `-M` seems bad: `-M` won't make GHC use more memory; in fact, you'd expect it to have no/bad effect on programs. Here's one particular example benchmarked on 7.10: ezyang@sabre:~/Dev/serum$ dist/build/serum/serum 15 gen-binaryE +RTS -s -M128m benchmarking gen-binaryE time 53.34 ms (51.51 ms .. 54.90 ms) 0.997 R² (0.992 R² .. 0.999 R²) mean 52.58 ms (51.82 ms .. 54.08 ms) std dev 1.864 ms (1.158 ms .. 2.769 ms) 3,715,656,736 bytes allocated in the heap 1,863,677,408 bytes copied during GC 2,070,152 bytes maximum residency (846 sample(s)) 102,968 bytes maximum slop 6 MB total memory in use (0 MB lost due to fragmentation) Tot time (elapsed) Avg pause Max pause Gen 0 6235 colls, 0 par 2.508s 2.693s 0.0004s 0.0033s Gen 1 846 colls, 0 par 1.628s 1.618s 0.0019s 0.0070s INIT time 0.000s ( 0.000s elapsed) MUT time 2.252s ( 2.702s elapsed) GC time 4.136s ( 4.312s elapsed) EXIT time 0.000s ( 0.000s elapsed) Total time 6.388s ( 7.014s elapsed) %GC time 64.7% (61.5% elapsed) Alloc rate 1,649,936,383 bytes per MUT second Productivity 35.3% of total user, 32.1% of total elapsed ezyang@sabre:~/Dev/serum$ dist/build/serum/serum 15 gen-binaryE +RTS -s -H128m benchmarking gen-binaryE time 25.02 ms (23.80 ms .. 26.15 ms) 0.988 R² (0.973 R² .. 0.997 R²) mean 28.79 ms (27.61 ms .. 30.55 ms) std dev 3.059 ms (1.871 ms .. 4.412 ms) variance introduced by outliers: 43% (moderately inflated) 6,571,453,840 bytes allocated in the heap 137,492,888 bytes copied during GC 117,280 bytes maximum residency (3 sample(s)) 35,624 bytes maximum slop 132 MB total memory in use (0 MB lost due to fragmentation) Tot time (elapsed) Avg pause Max pause Gen 0 132 colls, 0 par 0.464s 0.475s 0.0036s 0.0115s Gen 1 3 colls, 0 par 0.004s 0.002s 0.0008s 0.0016s INIT time 0.000s ( 0.000s elapsed) MUT time 5.556s ( 6.254s elapsed) GC time 0.468s ( 0.477s elapsed) EXIT time 0.000s ( 0.000s elapsed) Total time 6.024s ( 6.732s elapsed) %GC time 7.8% (7.1% elapsed) Alloc rate 1,182,767,069 bytes per MUT second Productivity 92.2% of total user, 82.5% of total elapsed }}} It seems to me the writer really meant to suggest `-H`. I'll volunteer to write the patch if someone confirms. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10474> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #4012: Compilation results are not deterministic
by GHC 03 Jun '15

03 Jun '15

#4012: Compilation results are not deterministic -------------------------------------+------------------------------------- Reporter: kili | Owner: Type: bug | Status: new Priority: high | Milestone: 7.12.1 Component: Compiler | Version: 6.12.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Other | Unknown/Multiple Blocked By: | Test Case: Related Tickets: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- Changes (by thoughtpolice): * owner: Fuuzetsu => * status: patch => new * milestone: 7.10.2 => 7.12.1 Comment: Okay, moving back to 7.12.1 for future work. 7a82b77691fb90 is in `ghc-7.10` now (as 1ff03e466c). -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/4012#comment:90> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9938: cryptarithm2 fails with undefined reference to `transzuH9c1w14lEUN3zzdWCTsn8jG_ControlziMonadziTransziStateziLazzy_zdwzdcp0Alternative_info'
by GHC 03 Jun '15

03 Jun '15

#9938: cryptarithm2 fails with undefined reference to `transzuH9c1w14lEUN3zzdWCTsn8jG_ControlziMonadziTransziStateziLazzy_zdwzdcp0Alternative_info' -------------------------------------+------------------------------------- Reporter: nomeata | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.11 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Compile-time Unknown/Multiple | crash Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -------------------------------------+------------------------------------- I am observing this right now: {{{ ==nofib== cryptarithm2: size of Main.o follows... text data bss dec hex filename 25423 1304 0 26727 6867 Main.o ==nofib== cryptarithm2: time to link cryptarithm2 follows... Main.o: In Funktion `c79k_info': (.text+0x1a5b): Nicht definierter Verweis auf `transzuH9c1w14lEUN3zzdWCTsn8jG_ControlziMonadziTransziStateziLazzy_zdwzdcp0Alternative_info' Main.o: In Funktion `c7cP_info': (.text+0x2283): Nicht definierter Verweis auf `transzuH9c1w14lEUN3zzdWCTsn8jG_ControlziMonadziTransziStateziLazzy_zdwzdcp0Alternative_info' Main.o: In Funktion `c7ll_info': (.text+0x2f53): Nicht definierter Verweis auf `transzuH9c1w14lEUN3zzdWCTsn8jG_ControlziMonadziTransziStateziLazzy_zdwzdcp0Alternative_info' Main.o: In Funktion `c7p2_info': (.text+0x37cb): Nicht definierter Verweis auf `transzuH9c1w14lEUN3zzdWCTsn8jG_ControlziMonadziTransziStateziLazzy_zdwzdcp0Alternative_info' collect2: error: ld returned 1 exit status <<ghc: 12447488 bytes, 13 GCs, 430760/691224 avg/max bytes residency (2 samples), 31M in use, 0.001 INIT (0.001 elapsed), 0.008 MUT (0.207 elapsed), 0.013 GC (0.013 elapsed) :ghc>> make[2]: *** [cryptarithm2] Fehler 1 Failed making all in cryptarithm2: 1 make[1]: *** [all] Fehler 1 Failed making all in spectral: 1 make: *** [all] Fehler 1 make: Verlasse Verzeichnis '/data1/ghc-builder/logs/ghc-tmp-REV/nofib' }}} Trying to minimize the problem, I came up with this file: {{{ module Main where import Control.Monad import Control.Monad.Trans.State solve :: Int -> StateT () [] () solve carry | carry > 0 = do guard (0 == carry) solve (carry -1) solve 0 = mzero main :: IO () main = return () }}} It only occurs when using this sequence (I’m also pasting the DEBUG output, in case it is useful): {{{ $ /home/jojo/build/haskell/ghc/inplace/bin/ghc-stage2 -O2 -c Main.hs WARNING: file compiler/specialise/Specialise.hs, line 677 specImport discarding: $w$cmany :: forall s_a1an (m_a1ao :: * -> *). MonadPlus m_a1ao => forall a_a1ap. StateT s_a1an m_a1ao a_a1ap -> StateT s_a1an m_a1ao [a_a1ap] want: False stable: False calls: $w$cmany _ @ [] $fMonadPlus[] WARNING: file compiler/specialise/Specialise.hs, line 677 specImport discarding: $w$csome :: forall s_a1ax (m_a1ay :: * -> *). MonadPlus m_a1ay => forall a_a1az. StateT s_a1ax m_a1ay a_a1az -> StateT s_a1ax m_a1ay [a_a1az] want: False stable: False calls: $w$csome _ @ [] $fMonadPlus[] WARNING: file compiler/specialise/Specialise.hs, line 677 specImport discarding: $w$cp0Alternative :: forall s_a1aT (m_a1aU :: * -> *). MonadPlus m_a1aU => (# Functor (StateT s_a1aT m_a1aU), forall a_a1aV. a_a1aV -> StateT s_a1aT m_a1aU a_a1aV, forall a_a1aW b_a1aX. StateT s_a1aT m_a1aU (a_a1aW -> b_a1aX) -> StateT s_a1aT m_a1aU a_a1aW -> StateT s_a1aT m_a1aU b_a1aX, forall a_a1aY b_a1aZ. StateT s_a1aT m_a1aU a_a1aY -> StateT s_a1aT m_a1aU b_a1aZ -> StateT s_a1aT m_a1aU b_a1aZ, forall a_a1b0 b_a1b1. StateT s_a1aT m_a1aU a_a1b0 -> StateT s_a1aT m_a1aU b_a1b1 -> StateT s_a1aT m_a1aU a_a1b0 #) want: False stable: False calls: $w$cp0Alternative _ @ [] $fMonadPlus[] WARNING: file compiler/specialise/Specialise.hs, line 1093 Missed specialisation opportunity for $fMonadStateT_$c>> [] 2 [] 1 [ALWAYS] $ /home/jojo/build/haskell/ghc/inplace/bin/ghc-stage2 -O2 -o cryptarithm2 Main.o Main.o: In function `r3He_info': (.text+0x52): undefined reference to `transzuH9c1w14lEUN3zzdWCTsn8jG_ControlziMonadziTransziStateziLazzy_zdwzdcp0Alternative_info' collect2: error: ld returned 1 exit status }}} It works fine if I compile directly using {{{ $ /home/jojo/build/haskell/ghc/inplace/bin/ghc-stage2 -O2 -o cryptarithm2 Main.hs }}} Changing the order of the cases in `solve` also makes the problem go away. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9938> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #4012: Compilation results are not deterministic
by GHC 03 Jun '15

03 Jun '15

#4012: Compilation results are not deterministic -------------------------------------+------------------------------------- Reporter: kili | Owner: Fuuzetsu Type: bug | Status: patch Priority: high | Milestone: 7.10.2 Component: Compiler | Version: 6.12.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Other | Unknown/Multiple Blocked By: | Test Case: Related Tickets: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- Comment (by Austin Seipp <austin@…>): In [changeset:"7a82b77691fb90c4af6863673f10e454a449739e/ghc"]: {{{ #!CommitTicketReference repository="ghc" revision="7a82b77691fb90c4af6863673f10e454a449739e" newTempName: Do not include pid in basename The filename of temporary files, especially the basename of C files, can end up in the output in some form, e.g. as part of linker debug information. In the interest of bit-wise exactly reproducible compilation (#4012), the basename of the temporary file no longer contains random information (it used to ontain the process id). This is ok, as the temporary directory used contains the pid (see getTempDir). This patch has been applied to the Debian package (version 7.10.1-5) and allowed a fully bit-wise reproducible build: https://reproducible.debian.net/rb-pkg/experimental/amd64/ghc.html Reviewed By: austin, rwbarton Differential Revision: https://phabricator.haskell.org/D910 GHC Trac Issues: #4012 }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/4012#comment:89> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10452: ApiAnnotations : rationalise tests
by GHC 03 Jun '15

03 Jun '15

#10452: ApiAnnotations : rationalise tests -------------------------------------+------------------------------------- Reporter: alanz | Owner: alanz Type: task | Status: new Priority: normal | Milestone: 7.10.2 Component: Compiler | Version: 7.10.1 Keywords: | Operating System: Unknown/Multiple ApiAnnotations | Type of failure: None/Unknown Architecture: | Blocked By: Unknown/Multiple | Related Tickets: Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- At the moment the API Annotations tests have a driver that has been copy/pasted multiple times. Compile it once, and run it for each test case. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10452> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10400: Run time increases by 40% in fractal plotter core loop
by GHC 03 Jun '15

03 Jun '15

#10400: Run time increases by 40% in fractal plotter core loop -------------------------------------+------------------------------------- Reporter: saffroy | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.4 Keywords: | Operating System: Linux Architecture: x86_64 | Type of failure: Runtime (amd64) | performance bug Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -------------------------------------+------------------------------------- I'm writing a toy fractal plotter to teach myself some Haskell. For a while I used GHC 7.4, recently upgraded to 7.10, and found a significant drop in run time performance. Tests with other versions show that the drop dates back to 7.8. Not sure if this is a good practice, or if this is relevant here, but I used bangs to improve performance by adding strictness: this gives a good speedup with 7.4/7.6, but perf is unchanged with 7.8/7.10. || version || run time (sec) - bangs || no bangs || ||7.4.2 || 6.09|| 18.73|| ||7.6.3 || 6.10|| 18.93|| ||7.8.4 || 8.92|| 8.88|| ||7.10.1 || 8.92|| 9.04|| (All builds with ghc -O2.) Source: {{{#!hs {-# LANGUAGE BangPatterns #-} iterations :: Int -> Double -> Double -> Double -> Double -> Int -> Int iterations !maxK !x !y !x0 !y0 !k = let !x2 = x * x !y2 = y * y in if k == maxK || x2 + y2 > 4 then k else iterations maxK (x2 - y2 + x0) (2 * x * y + y0) x0 y0 (k + 1) inSet :: Int -> Int -> (Double, Double) -> Bool inSet !minK !maxK (!x, !y) = k >= minK && k < maxK where !k = iterations maxK x y x y 0 main = do let pointSource = repeat $ ((-0.6518209274278592), 0.3549264214581329) nPoints = 1000 * 1000 points = take nPoints pointSource selected = filter (inSet 1000 (1000 * 20)) points print $ length selected == nPoints }}} The host C compiler is gcc 4.7.2. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10400> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10425: User's guide PDF version: Example with wrong indentation in Section 13.1.1.2
by GHC 03 Jun '15

03 Jun '15

#10425: User's guide PDF version: Example with wrong indentation in Section 13.1.1.2 -------------------------------------+------------------------------------- Reporter: asr | Owner: Type: bug | Status: new Priority: normal | Milestone: 7.10.2 Component: | Version: 7.10.1 Documentation | Operating System: Unknown/Multiple Keywords: | Type of failure: None/Unknown Architecture: | Blocked By: Unknown/Multiple | Related Tickets: Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- In the '''pdf''' version of User's Guide Version 7.10.1, the first example of "Section 13.1.1.2 Contex-free syntax" has the following wrong indentation: {{{#!hs main = do args <- getArgs if null args then return [] else do ps <- mapM process args mapM print ps }}} The HTML version is OK, though. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10425> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #8025: "During interactive linking, GHCi couldn't find the following symbol" typechecker error with TemplateHaskell involved
by GHC 03 Jun '15

03 Jun '15

#8025: "During interactive linking, GHCi couldn't find the following symbol" typechecker error with TemplateHaskell involved -------------------------------------+------------------------------------- Reporter: mojojojo | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler (Type | Version: 7.6.3 checker) | Keywords: Resolution: | Architecture: x86 Operating System: Unknown/Multiple | Test Case: Type of failure: Incorrect | Blocking: warning at compile-time | Differential Revisions: Blocked By: | Related Tickets: | -------------------------------------+------------------------------------- Changes (by rwbarton): * status: infoneeded => new Comment: (How) is this supposed to work at all? I mean, if you want to be able to run a TH splice, you need to at some point generate code for the values used in the splice, right? Is the TH runner supposed to recompile the necessary module(s) with the bytecode generator? A minimal reproducer is simply {{{ -- A.hs {-# LANGUAGE TemplateHaskell #-} module A where a = [|3|] -- B.hs {-# LANGUAGE TemplateHaskell #-} module B where import A x = $(a) -- command: ghc -fno-code B }}} It might be possible to diagnose the situation and produce a better error message, but making this actually work seems solidly in feature request territory to me. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8025#comment:5> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10461: Suggest UnliftedFFITypes when applicable
by GHC 03 Jun '15

03 Jun '15

#10461: Suggest UnliftedFFITypes when applicable -------------------------------------+------------------------------------- Reporter: ezyang | Owner: ezyang Type: bug | Status: new Priority: low | Milestone: Component: Compiler | Version: 7.11 (Type checker) | Operating System: Unknown/Multiple Keywords: | Type of failure: Incorrect Architecture: | warning at compile-time Unknown/Multiple | Blocked By: Test Case: | Related Tickets: Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Here's an example bad error message: {{{ Serum.hs:5:1: Unacceptable result type in foreign declaration: ‘Word#’ cannot be marshalled in a foreign call When checking declaration: foreign import prim safe "static chenycopy" cheneycopy :: Any -> Word# }}} We should also add something like: {{{ To enable marshalling unlifted types, enable -XUnliftedFFITypes }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10461> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10466: Bogus multiple-declaration error in GHCi + Template Haskell
by GHC 02 Jun '15

02 Jun '15

#10466: Bogus multiple-declaration error in GHCi + Template Haskell -------------------------------------+------------------------------------- Reporter: simonpj | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.3 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Blocked By: Test Case: | Related Tickets: Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Try this (with ghc 7.8.3) {{{ th% ghc --version The Glorious Glasgow Haskell Compilation System, version 7.8.3 th $ ghc --interactive -XTemplateHaskell GHCi, version 7.8.3: http://www.haskell.org/ghc/ :? for help Loading package ghc-prim ... linking ... done. Loading package integer-gmp ... linking ... done. Loading package base ... linking ... done. Prelude> let x = True Prelude> let y = [d| x = 'c' |] <interactive>:3:13: Multiple declarations of ‘x’ Declared at: <interactive>:2:5 <interactive>:3:13 In the Template Haskell quotation [d| x = 'c' |] }}} This is obviously wrong, a failure of the name-shadwing code in `RnNames.extendGlobalRdrEnvRn`. I suspect that this afflicts 7.10 too, but I can't check that right now. Working on a fix. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10466> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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