September 2013 - ghc-tickets

Re: [GHC] #5762: GHC gives incorrect warnings with simple applications of the view patterns extension
by GHC 18 Sep '13

18 Sep '13

#5762: GHC gives incorrect warnings with simple applications of the view patterns extension -------------------------------------------------+------------------------- Reporter: jmg | Owner: Type: bug | Status: new Priority: normal | Milestone: _|_ Component: Compiler | Version: 7.3 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Incorrect warning at | Unknown/Multiple compile-time | Difficulty: Test Case: | Unknown Blocking: | Blocked By: | Related Tickets: -------------------------------------------------+------------------------- Comment (by hvr): !PatternGuards can result in a similar spurious warning, i.e. {{{#!hs module Foo where foo :: Either t t -> t foo x | Left l <- x = l | Right r <- x = r bar :: Either t t -> t bar x = v where v | Left l <- x = l | Right r <- x = r }}} leads to {{{ Foo.hs:4:1: Warning: Pattern match(es) are non-exhaustive In an equation for `foo': Patterns not matched: _ Foo.hs:10:5: Warning: Pattern match(es) are non-exhaustive In an equation for `v': Patterns not matched: }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/5762#comment:2> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7574: Register allocator chokes on certain branches with literals
by GHC 18 Sep '13

18 Sep '13

#7574: Register allocator chokes on certain branches with literals -------------------------------------+------------------------------------- Reporter: thoughtpolice | Owner: simonmar Type: bug | Status: new Priority: highest | Milestone: 7.8.1 Component: Compiler (NCG) | Version: 7.7 Resolution: | Keywords: ncg, codegen Operating System: Unknown/Multiple | Architecture: Unknown/Multiple Type of failure: Compile-time | Difficulty: Unknown crash | Blocked By: 7573 Test Case: | Related Tickets: #7571,#7534, codeGen/should_compile/T7574 | #7814 Blocking: | -------------------------------------+------------------------------------- Comment (by thoughtpolice): Thank you Simon. I'm quite busy at the moment - and I've also had a partially working patch (probably similar to yours,) but mine also threw away too much code when discarding unreachable blocks. I mean to brain- dump it to you, but I imagine you can manage :) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7574#comment:25> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7574: Register allocator chokes on certain branches with literals
by GHC 18 Sep '13

18 Sep '13

#7574: Register allocator chokes on certain branches with literals -------------------------------------+------------------------------------- Reporter: thoughtpolice | Owner: simonmar Type: bug | Status: new Priority: highest | Milestone: 7.8.1 Component: Compiler (NCG) | Version: 7.7 Resolution: | Keywords: ncg, codegen Operating System: Unknown/Multiple | Architecture: Unknown/Multiple Type of failure: Compile-time | Difficulty: Unknown crash | Blocked By: 7573 Test Case: | Related Tickets: #7571,#7534, codeGen/should_compile/T7574 | #7814 Blocking: | -------------------------------------+------------------------------------- Changes (by simonmar): * owner: thoughtpolice => simonmar Comment: Claiming this. I have a half-finished patch to fix it, just need a bit of time to finish it off. Sounds like a good thing to do while travelling to ICFP on Saturday. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7574#comment:24> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7574: Register allocator chokes on certain branches with literals
by GHC 18 Sep '13

18 Sep '13

#7574: Register allocator chokes on certain branches with literals -------------------------------------+------------------------------------- Reporter: thoughtpolice | Owner: thoughtpolice Type: bug | Status: new Priority: highest | Milestone: 7.8.1 Component: Compiler (NCG) | Version: 7.7 Resolution: | Keywords: ncg, codegen Operating System: Unknown/Multiple | Architecture: Unknown/Multiple Type of failure: Compile-time | Difficulty: Unknown crash | Blocked By: 7573 Test Case: | Related Tickets: #7571,#7534, codeGen/should_compile/T7574 | #7814 Blocking: | -------------------------------------+------------------------------------- Comment (by bos): This bug accounts for over 90% of the compilation failures in attempting to compile hackage with HEAD. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7574#comment:23> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7574: Register allocator chokes on certain branches with literals
by GHC 18 Sep '13

18 Sep '13

#7574: Register allocator chokes on certain branches with literals -------------------------------------+------------------------------------- Reporter: thoughtpolice | Owner: thoughtpolice Type: bug | Status: new Priority: highest | Milestone: 7.8.1 Component: Compiler (NCG) | Version: 7.7 Resolution: | Keywords: ncg, codegen Operating System: Unknown/Multiple | Architecture: Unknown/Multiple Type of failure: Compile-time | Difficulty: Unknown crash | Blocked By: 7573 Test Case: | Related Tickets: #7571,#7534, codeGen/should_compile/T7574 | #7814 Blocking: | -------------------------------------+------------------------------------- Changes (by bos): * cc: bos@… (added) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7574#comment:22> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8328: Crash at -O2: Cannot read from uninitialized register
by GHC 18 Sep '13

18 Sep '13

#8328: Crash at -O2: Cannot read from uninitialized register ----------------------------------+--------------------------------------- Reporter: bos | Owner: Type: bug | Status: new Priority: highest | Milestone: 7.8.1 Component: Compiler | Version: 7.7 Keywords: | Operating System: Linux Architecture: x86_64 (amd64) | Type of failure: Compile-time crash Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ----------------------------------+--------------------------------------- I did a quick x86_64 compile of all of Hackage today using HEAD, and GHC is crashing when compiling the utf8-string package. {{{ [2 of 7] Compiling Codec.Binary.UTF8.Generic ( Codec/Binary/UTF8/Generic.hs, dist/dist-sandbox- 4a6171fb/build/Codec/Binary/UTF8/Generic.o ) ghc: panic! (the 'impossible' happened) (GHC version 7.7.20130915 for x86_64-unknown-linux): allocateRegsAndSpill: Cannot read from uninitialized register %vI_sa0l }}} To reproduce using utf8-string: {{{ cabal get utf8-string cd utf8-string* ghc -XCPP -fforce-recomp -O2 --make -c Codec/Binary/UTF8/Generic.hs }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8328> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7883: enable GHC LLVM backend to use LLVM provided CAS / Atomicity primitives?
by GHC 18 Sep '13

18 Sep '13

#7883: enable GHC LLVM backend to use LLVM provided CAS / Atomicity primitives? -------------------------------------+------------------------------------ Reporter: carter | Owner: carter Type: task | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.7 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Unknown/Multiple Type of failure: None/Unknown | Difficulty: Unknown Test Case: | Blocked By: Blocking: | Related Tickets: -------------------------------------+------------------------------------ Comment (by carter): i'll work on adding this stuff after the 7.8 rush. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7883#comment:15> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #6166: Performance regression in mwc-random since 7.0.x
by GHC 18 Sep '13

18 Sep '13

#6166: Performance regression in mwc-random since 7.0.x --------------------------------------------+------------------------------ Reporter: bos | Owner: Type: bug | Status: new Priority: high | Milestone: 7.6.2 Component: Compiler | Version: 7.4.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: x86_64 Type of failure: Runtime performance bug | (amd64) Test Case: | Difficulty: Unknown Blocking: | Blocked By: | Related Tickets: --------------------------------------------+------------------------------ Comment (by Khudyakov): I've been able to remove all stuff from mwc-random. Here is test case. Again it's slow version. {{{ {-# LANGUAGE BangPatterns #-} import qualified Data.Vector.Unboxed as I import Data.Vector.Unboxed ((!)) import Control.Monad main :: IO () main = replicateM_ (100*1000) (return $! standard) standard :: Double {-# INLINE standard #-} standard = blocks ! 0 where blocks :: I.Vector Double blocks = I.cons r $ I.unfoldrN 130 go $ T r f where go (T b g) = let !u = T h (exp (-0.5 * h * h)) h = sqrt (-2 * log (v / b + g)) in Just (h, u) {-# NOINLINE blocks #-} v,r,f :: Double v = 9.91256303526217e-3 r = 3.442619855899 -- f = 2.669629083880923e-3 -- FAST f = exp (-0.5 * r * r) -- SLOW -- Unboxed 2-tuple data T = T {-# UNPACK #-} !Double {-# UNPACK #-} !Double }}} Couple of observations 1. Replacing `f` with constant restores run time to normal. AFAIR GHC cannot constant fold `exp` and similar functions. So it may matter 2. Floating `block` to top level or removing `I.cons` restores run time too. 3. Simplifying `go` function changes run time. Removing `sqrt` or `log` reduce rim time. It looks like `blocks` is reevaluated every time `standard` is evaluated. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/6166#comment:10> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #6135: Unboxed Booleans
by GHC 18 Sep '13

18 Sep '13

#6135: Unboxed Booleans ---------------------------------------------+----------------------------- Reporter: benl | Owner: jstolarek Type: feature request | Status: closed Priority: normal | Milestone: 7.8.1 Component: Compiler | Version: 7.4.1 Resolution: fixed | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: None/Unknown | Unknown/Multiple Test Case: primops/should_run/T6135 | Difficulty: Unknown Blocking: | Blocked By: 8103, | 8103 | Related Tickets: #605 ---------------------------------------------+----------------------------- Comment (by Jan Stolarek <jan.stolarek@…>): In [changeset:5ab5b3d7ca15fc7620de4c979f4eece7780895f4/ghc-prim]: {{{ #!CommitTicketReference repository="ghc-prim" revision="5ab5b3d7ca15fc7620de4c979f4eece7780895f4" Follow changes in comparison primops (see #6135) }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/6135#comment:88> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #6135: Unboxed Booleans
by GHC 18 Sep '13

18 Sep '13

#6135: Unboxed Booleans ---------------------------------------------+----------------------------- Reporter: benl | Owner: jstolarek Type: feature request | Status: closed Priority: normal | Milestone: 7.8.1 Component: Compiler | Version: 7.4.1 Resolution: fixed | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: None/Unknown | Unknown/Multiple Test Case: primops/should_run/T6135 | Difficulty: Unknown Blocking: | Blocked By: 8103, | 8103 | Related Tickets: #605 ---------------------------------------------+----------------------------- Comment (by Jan Stolarek <jan.stolarek@…>): In [changeset:427cbd522c3aeb04dc6a9bd696ffb7c71069facc/base]: {{{ #!CommitTicketReference repository="base" revision="427cbd522c3aeb04dc6a9bd696ffb7c71069facc" Follow changes in comparison primops (see #6135) }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/6135#comment:87> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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