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Re: [GHC] #876: Length is not a good consumer
by GHC 12 Feb '13

12 Feb '13

#876: Length is not a good consumer --------------------------------------+------------------------------------- Reporter: ariep@… | Owner: Type: bug | Status: new Priority: lowest | Milestone: 7.6.2 Component: libraries/base | Version: 6.5 Resolution: | Keywords: length Os: Linux | Architecture: Unknown/Multiple Failure: Runtime performance bug | Difficulty: Unknown Testcase: list003 | Blockedby: Blocking: | Related: --------------------------------------+------------------------------------- Comment(by simonpj): OK, so the problem in Ian's comment 6 years ago (ha ha!) was that the naive version of `length` using `foldr` does not lead to a tail recursive function. But after a little reflection I realise that what we want is `foldl` with a strict accumulating parameter; and that can be expressed using `foldr`. So here is a version that does work (notice the strict apply) in `incL`: {{{ len :: [a] -> Int len xs = foldr incL id xs 0 incL :: a -> (Int -> Int) -> Int -> Int incL = \_ g x -> g $! (x+1) }}} To demonstrate: {{{ foo :: Int -> Int -> Int foo p q = len [p..q] }}} Compile with -O to get this nice tight code {{{ Len.$wfoo :: GHC.Prim.Int# -> GHC.Prim.Int# -> GHC.Prim.Int# Len.$wfoo = \ (ww_sgn :: GHC.Prim.Int#) (ww1_sgr :: GHC.Prim.Int#) -> case GHC.Prim.># ww_sgn ww1_sgr of _ { GHC.Types.False -> letrec { $wgo_sgA [Occ=LoopBreaker] :: GHC.Prim.Int# -> GHC.Prim.Int# -> GHC.Prim.Int# [LclId, Arity=2, Str=DmdType LL] $wgo_sgA = \ (w_sga :: GHC.Prim.Int#) (ww2_sgd :: GHC.Prim.Int#) -> case GHC.Prim.==# w_sga ww1_sgr of _ { GHC.Types.False -> $wgo_sgA (GHC.Prim.+# w_sga 1) (GHC.Prim.+# ww2_sgd 1); GHC.Types.True -> GHC.Prim.+# ww2_sgd 1 }; } in $wgo_sgA ww_sgn 0; GHC.Types.True -> 0 } }}} So I think we can do this for length in the library. I need a clean nofib run to test, though. Simon -- Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/876#comment:25> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7192: Bug in -fregs-graph with -fnew-codegen
by GHC 12 Feb '13

12 Feb '13

#7192: Bug in -fregs-graph with -fnew-codegen -------------------------------+-------------------------------------------- Reporter: simonmar | Owner: benl Type: bug | Status: closed Priority: highest | Milestone: 7.8.1 Component: Compiler | Version: 7.7 Resolution: fixed | Keywords: Os: Unknown/Multiple | Architecture: Unknown/Multiple Failure: None/Unknown | Difficulty: Unknown Testcase: | Blockedby: Blocking: 4258 | Related: -------------------------------+-------------------------------------------- Comment(by shelarcy): Replying to [comment:14 simonmar]: > #7679 I see. Thank you. -- Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7192#comment:15> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #7681: Panic on quoting empty case
by GHC 11 Feb '13

11 Feb '13

#7681: Panic on quoting empty case -----------------------------+---------------------------------------------- Reporter: monoidal | Owner: Type: bug | Status: new Priority: normal | Component: Compiler Version: 7.7 | Keywords: Os: Unknown/Multiple | Architecture: Unknown/Multiple Failure: None/Unknown | Blockedby: Blocking: | Related: -----------------------------+---------------------------------------------- With -XEmptyCase on, {{{ Prelude Language.Haskell.TH> runQ [| case 0 of {} |] ghc: panic! (the 'impossible' happened) (GHC version 7.7.20130209 for x86_64-unknown-linux): coreList: empty argument }}} -- Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7681> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #876: Length is not a good consumer
by GHC 11 Feb '13

11 Feb '13

#876: Length is not a good consumer --------------------------------------+------------------------------------- Reporter: ariep@… | Owner: Type: bug | Status: new Priority: lowest | Milestone: 7.6.2 Component: libraries/base | Version: 6.5 Resolution: | Keywords: length Os: Linux | Architecture: Unknown/Multiple Failure: Runtime performance bug | Difficulty: Unknown Testcase: list003 | Blockedby: Blocking: | Related: --------------------------------------+------------------------------------- Changes (by morabbin): * owner: simonpj => * status: closed => new * resolution: invalid => Comment: Premature; reopening as a performance bug. #915 was about the general stream fusion technique, which needs moar research. This is a good place to track an exemplar of the problem. -- Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/876#comment:24> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #1845: unconditional relative branch out of range (GHC version 6.8.1-6.10.4 for powerpc_apple_darwin)
by GHC 11 Feb '13

11 Feb '13

#1845: unconditional relative branch out of range (GHC version 6.8.1-6.10.4 for powerpc_apple_darwin) ---------------------------------+------------------------------------------ Reporter: guest | Owner: igloo Type: bug | Status: closed Priority: high | Milestone: 7.0.2 Component: Compiler | Version: 7.1 Resolution: fixed | Keywords: Os: MacOS X | Architecture: powerpc Failure: Compile-time crash | Difficulty: Unknown Testcase: ghci024 | Blockedby: Blocking: | Related: ---------------------------------+------------------------------------------ Changes (by igloo): * testcase: => ghci024 -- Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/1845#comment:31> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7498: panic : Register allocator: out of stack slots (need 147)
by GHC 11 Feb '13

11 Feb '13

#7498: panic : Register allocator: out of stack slots (need 147) ----------------------------------+----------------------------------------- Reporter: erikd | Owner: Type: bug | Status: closed Priority: high | Milestone: 7.8.1 Component: Compiler | Version: 7.7 Resolution: fixed | Keywords: Os: Unknown/Multiple | Architecture: powerpc Failure: Building GHC failed | Difficulty: Unknown Testcase: | Blockedby: Blocking: | Related: ----------------------------------+----------------------------------------- Changes (by simonmar): * status: patch => closed * resolution: => fixed -- Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7498#comment:13> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7498: panic : Register allocator: out of stack slots (need 147)
by GHC 11 Feb '13

11 Feb '13

#7498: panic : Register allocator: out of stack slots (need 147) ----------------------------------+----------------------------------------- Reporter: erikd | Owner: Type: bug | Status: patch Priority: high | Milestone: 7.8.1 Component: Compiler | Version: 7.7 Resolution: | Keywords: Os: Unknown/Multiple | Architecture: powerpc Failure: Building GHC failed | Difficulty: Unknown Testcase: | Blockedby: Blocking: | Related: ----------------------------------+----------------------------------------- Comment(by simonmar): pushed, thanks. An error when pushing prevented the commit showing up on the ticket: {{{ Unexpected error while processing ticket ID 7498: columns ticket, time, field are not unique Unexpected error while processing ticket ID 7498: columns ticket, time, field are not unique }}} So here it is: {{{ commit 36d9ded20c07f6b81271fa248e301cc44f29eff7 Merge: 804d8f6 c1feb5f Author: Simon Marlow <marlowsd(a)gmail.com> Date: Mon Feb 11 09:23:40 2013 +0000 Merge remote-tracking branch 'phonohawk/ticket-7498' * phonohawk/ticket-7498: Fix bugs in PPC.Instr.allocMoreStack (#7498) commit c1feb5f9b82ab05a128ecb7678d2da3db078ff40 Author: PHO <pho(a)cielonegro.org> Date: Mon Feb 11 13:49:26 2013 +0900 Fix bugs in PPC.Instr.allocMoreStack (#7498) This patch is ported from #7510, which fixes the same bug in the x86 nativeGen. }}} -- Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7498#comment:12> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7510: Immediate seg-fault on 32-bit windows build
by GHC 11 Feb '13

11 Feb '13

#7510: Immediate seg-fault on 32-bit windows build -------------------------------+-------------------------------------------- Reporter: simonpj | Owner: simonmar Type: bug | Status: closed Priority: highest | Milestone: 7.8.1 Component: Compiler | Version: 7.6.1 Resolution: fixed | Keywords: Os: Unknown/Multiple | Architecture: Unknown/Multiple Failure: None/Unknown | Difficulty: Unknown Testcase: | Blockedby: Blocking: | Related: -------------------------------+-------------------------------------------- Comment(by pho@…): commit c1feb5f9b82ab05a128ecb7678d2da3db078ff40 {{{ Author: PHO <pho(a)cielonegro.org> Date: Mon Feb 11 13:49:26 2013 +0900 Fix bugs in PPC.Instr.allocMoreStack (#7498) This patch is ported from #7510, which fixes the same bug in the x86 nativeGen. compiler/nativeGen/PPC/Instr.hs | 124 ++++++++++++++++++++++++++------------ 1 files changed, 85 insertions(+), 39 deletions(-) }}} -- Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7510#comment:16> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7498: panic : Register allocator: out of stack slots (need 147)
by GHC 11 Feb '13

11 Feb '13

#7498: panic : Register allocator: out of stack slots (need 147) ----------------------------------+----------------------------------------- Reporter: erikd | Owner: Type: bug | Status: patch Priority: high | Milestone: 7.8.1 Component: Compiler | Version: 7.7 Resolution: | Keywords: Os: Unknown/Multiple | Architecture: powerpc Failure: Building GHC failed | Difficulty: Unknown Testcase: | Blockedby: Blocking: | Related: ----------------------------------+----------------------------------------- Comment(by marlowsd@…): commit e19a20488b5b7b412543fb81b81ee9412ef414e6 {{{ Author: Simon Marlow <marlowsd(a)gmail.com> Date: Mon Feb 11 10:50:45 2013 +0000 allocMoreStack: we should be retargetting table jumps too. Thanks to @PHO on #7498 for pointing this out. compiler/nativeGen/X86/Instr.hs | 6 +++--- 1 files changed, 3 insertions(+), 3 deletions(-) }}} -- Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7498#comment:11> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #5113: Huge performance regression of 7.0.2, 7.0.3 and HEAD over 7.0.1 and 6.12 (MonoLocalBinds)
by GHC 11 Feb '13

11 Feb '13

#5113: Huge performance regression of 7.0.2, 7.0.3 and HEAD over 7.0.1 and 6.12 (MonoLocalBinds) --------------------------------------+------------------------------------- Reporter: daniel.is.fischer | Owner: Type: bug | Status: closed Priority: normal | Milestone: Component: Compiler | Version: 7.0.3 Resolution: fixed | Keywords: performance, MonoLocalBinds Os: Linux | Architecture: x86 Failure: Runtime performance bug | Difficulty: Unknown Testcase: perf/should_run/T5113 | Blockedby: Blocking: | Related: --------------------------------------+------------------------------------- Changes (by simonpj): * difficulty: => Unknown Comment: This patch is the crucial one that fixes the original problem {{{ commit b5c18c91da911a7729563207c7b95f7e452cca7e Author: Simon Peyton Jones <simonpj(a)microsoft.com> Date: Fri Feb 8 17:29:40 2013 +0000 Fix an old and egregious specialisation bug (Trac #5113) The specialiser needs to know if a dictionay has some structure, so that it can decide whether to specialise a function. Eg (A) let d = $dfblah d1 in ....(f d).... (B) \d. ....(f d).... In (A) it's probably worth specialising f; in (B) it isn't. Previously we were relying on d's unfolding, but the specialiser does cloning as it goes, which discards the unfolding. So we were simply discarding all specialisations for functions with local dictionary bindings! This bug seems to have been there for a long time. This is what originally caused Trac #5113. Then we went through a phase where local bindings were not generalised, and that meant there was no locally overloaded f to specialise; so the performance problem appeared to be fixed. But now we are generalising local bindings again, so it re-appeared. This patch fixes the original problem. compiler/specialise/Specialise.lhs | 390 ++++++++++++++++++++---------------- 1 files changed, 214 insertions(+), 176 deletions(-) }}} -- Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/5113#comment:6> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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