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Re: [GHC] #1600: Optimisation: CPR the results of IO
by GHC 04 Dec '13

04 Dec '13

#1600: Optimisation: CPR the results of IO -------------------------------------+------------------------------------- Reporter: simonmar | Owner: nomeata Type: task | Status: new Priority: lowest | Milestone: 7.6.2 Component: Compiler | Version: 6.6.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Unknown/Multiple Type of failure: Runtime | Difficulty: Moderate (less performance bug | than a day) Test Case: | Blocked By: Blocking: | Related Tickets: -------------------------------------+------------------------------------- Changes (by nomeata): * owner: => nomeata Comment: Interesting corner case: With nested CPR enabled, `GHC.TopHandler` in base fails to compile with: {{{ ghc-stage1: panic! (the 'impossible' happened) (GHC version 7.7.20131203 for x86_64-unknown-linux): mkWWcpr: non-algebraic or open body type a{tv a28d} [tv] but CPR type tm1() }}} The problem is this code: {{{ #!haskell case {__pkg_ccall_GC base shutdownHaskellAndExit GHC.Prim.Int# -> GHC.Prim.Int# -> GHC.Prim.State# GHC.Prim.RealWorld -> (# GHC.Prim.State# GHC.Prim.RealWorld #)}_d2VI 255 ds_d2VF eta_XG of _ [Occ=Dead, Dmd=<L,A>] { (# ds_d2VG [OS=OneShot] #) -> (# ds_d2VG, GHC.Tuple.() #) }}} stemming from {{{ #!haskell foreign import ccall "shutdownHaskellAndSignal" shutdownHaskellAndSignal :: CInt -> CInt -> IO () }}} which then is `unsafeCoerce#`’ed to `a`, with note explanation {{{ -- we have to use unsafeCoerce# to get the 'IO a' result type, since the -- compiler doesn't let us declare that as the result type of a foreign export. }}} There are a few ways to attack this issue: 1. We allow `a` in the return type of a foreign export (but maybe overkill to do that just for this code). 2. We try to forget CPR information when things pass through `unsafeCoerce#` (but that is just a {{{`cast`}}} in Core, and may be hard to detect reliably. Maybe every coercion that has a `UnivCo representational` inside?) 3. We re-write that code in base, e.g. instead of `unsafeCoerce` use `... >> error "I’m still alive?"`. 4. We simply turn the `panic` into a warning. I guess 2. makes most sense, because we don’t want other instances of `unsafeCoerce#` to cause this error either. For now I’ll do 4, to not get stuck compiling base. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/1600#comment:25> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #3384: Add HsSyn prettyprinter tests
by GHC 04 Dec '13

04 Dec '13

#3384: Add HsSyn prettyprinter tests -------------------------------------+------------------------------------ Reporter: igloo | Owner: kseo Type: task | Status: new Priority: normal | Milestone: _|_ Component: Test Suite | Version: 6.10.4 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Unknown/Multiple Type of failure: None/Unknown | Difficulty: Unknown Test Case: | Blocked By: Blocking: | Related Tickets: -------------------------------------+------------------------------------ Changes (by kseo): * owner: => kseo -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/3384#comment:2> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #3384: Add HsSyn prettyprinter tests
by GHC 04 Dec '13

04 Dec '13

#3384: Add HsSyn prettyprinter tests -------------------------------------+------------------------------------ Reporter: igloo | Owner: Type: task | Status: new Priority: normal | Milestone: _|_ Component: Test Suite | Version: 6.10.4 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Unknown/Multiple Type of failure: None/Unknown | Difficulty: Unknown Test Case: | Blocked By: Blocking: | Related Tickets: -------------------------------------+------------------------------------ Changes (by kseo): * failure: => None/Unknown Comment: I'd like to work on this task as my first patch to GHC. I think the idea suggested by dfranke in #1966 is a good starting point. Take some large Haskell projects and: 1. Parse them 1. Pretty-print them 1. Reparse the output 1. Pretty-print again and verify that step 3 succeeds and the outputs of steps 2 and 4 match. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/3384#comment:1> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #3625: GHCI doesn't work with dtrace on OS X
by GHC 04 Dec '13

04 Dec '13

#3625: GHCI doesn't work with dtrace on OS X ---------------------------------+------------------------------------ Reporter: rl | Owner: Type: bug | Status: new Priority: low | Milestone: 7.6.2 Component: GHCi | Version: 6.10.4 Resolution: | Keywords: Operating System: MacOS X | Architecture: Unknown/Multiple Type of failure: None/Unknown | Difficulty: Unknown Test Case: | Blocked By: Blocking: | Related Tickets: ---------------------------------+------------------------------------ Changes (by carter): * cc: hvr (added) Comment: is this resolved with ghc 7.7 head? Has anyone tested dtrce with head? if not i'll try to find the time to test it out soon. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/3625#comment:10> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #1600: Optimisation: CPR the results of IO
by GHC 03 Dec '13

03 Dec '13

#1600: Optimisation: CPR the results of IO -------------------------------------+------------------------------------- Reporter: simonmar | Owner: Type: task | Status: new Priority: lowest | Milestone: 7.6.2 Component: Compiler | Version: 6.6.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Unknown/Multiple Type of failure: Runtime | Difficulty: Moderate (less performance bug | than a day) Test Case: | Blocked By: Blocking: | Related Tickets: -------------------------------------+------------------------------------- Comment (by nomeata): Run nofib the first time, mixed results: {{{ binary-trees -1.3% +0.6% +7.7% +7.5% +0.0% hidden -1.3% -0.5% -0.3% -0.5% +0.0% mandel -1.2% -9.2% 0.10 0.10 +0.0% nucleic2 -1.0% -2.6% 0.11 0.11 +0.0% reverse-complem -1.3% +4.9% 0.21 0.22 +0.0% -------------------------------------------------------------------------------- Min -1.4% -9.2% -6.3% -6.6% -4.5% Max -1.0% +4.9% +7.7% +7.5% +0.0% Geometric Mean -1.3% -0.0% +0.5% +0.6% -0.1% }}} The gain in mandel seems to come from a a few more unboxed results in `Data.Complex`, in particular the return types of `$w$sphase` and `$w$smagnitued` turns from `Double` to `Double#` (and likewise the `Float`-specializations). And why the new chance for that? Because `$fFloatingComplex` (which is a CAF for `D# 0.0`) and other constants are inlined (and thus no longer shared). Not sure why that part changed, and it seems that this is not related to ''nested''CPR... -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/1600#comment:24> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #8006: Asynchronous exception rethrown synchronously inside runStmt
by GHC 03 Dec '13

03 Dec '13

#8006: Asynchronous exception rethrown synchronously inside runStmt -------------------------------------+------------------------------------ Reporter: edsko | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.6.3 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 Edsko de Vries <edsko@…>): In [changeset:"586bc85538cf12048137c2693da7c9fe3ca481ef/ghc"]: {{{ #!CommitTicketReference repository="ghc" revision="586bc85538cf12048137c2693da7c9fe3ca481ef" Mask async exceptions in forkM_ See #8006 for the reason why. This is not a fix as such; more of a workaround. }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8006#comment:9> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7307: Share top-level code for strings
by GHC 03 Dec '13

03 Dec '13

#7307: Share top-level code for strings -------------------------------------+------------------------------------ Reporter: simonpj | Owner: parcs Type: bug | Status: new Priority: normal | Milestone: 7.8.1 Component: Compiler | Version: 7.6.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Unknown/Multiple Type of failure: None/Unknown | Difficulty: Unknown Test Case: | Blocked By: Blocking: | Related Tickets: -------------------------------------+------------------------------------ Changes (by parcs): * owner: => parcs Comment: I will try to do this. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7307#comment:2> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8576: Improve deriving error messages
by GHC 03 Dec '13

03 Dec '13

#8576: Improve deriving error messages -------------------------------------------+------------------------------- Reporter: nomeata | Owner: nomeata Type: feature request | Status: new Priority: low | Milestone: Component: Compiler (Type checker) | Version: Keywords: | Operating System: Architecture: Unknown/Multiple | Unknown/Multiple Difficulty: Unknown | Type of failure: Blocked By: | None/Unknown Related Tickets: | Test Case: | Blocking: -------------------------------------------+------------------------------- Instead of {{{ No instance for (Eq (Int -> Bool)) arising from the 'deriving' clause of a data type declaration Possible fix: add an instance declaration for (Eq (Int -> Bool)) or use a standalone 'deriving instance' declaration, so you can specify the instance context yourself When deriving the instance for (Eq Foo) }}} for {{{ data Foo = Foo Int (Int -> Bool, Bool) deriving Eq }}} we want something like {{{ No instance for (Eq (Int -> Bool)) arising from the second field of the constructor Foo Possible fix: add an instance declaration for (Eq (Int -> Bool)) or use a standalone 'deriving instance' declaration, so you can specify the instance context yourself When deriving the instance for (Eq Foo) }}} where we tell the user more precisely from where in its data type the problem comes from. Should be possible by beefing up `CtOrigin`. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8576> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #2233: Overhaul System.Process
by GHC 03 Dec '13

03 Dec '13

#2233: Overhaul System.Process --------------------------------------+------------------------------------ Reporter: simonmar | Owner: simonmar Type: task | Status: closed Priority: normal | Milestone: _|_ Component: libraries/process | Version: 6.8.2 Resolution: fixed | Keywords: Operating System: Unknown/Multiple | Architecture: Unknown/Multiple Type of failure: None/Unknown | Difficulty: Unknown Test Case: | Blocked By: Blocking: | Related Tickets: --------------------------------------+------------------------------------ Comment (by Herbert Valerio Riedel <hvr@…>): In [changeset:"edda1be660d07b461da75b2dfacc3d5820b4d084/process"]: {{{ #!CommitTicketReference repository="process" revision="edda1be660d07b461da75b2dfacc3d5820b4d084" Add Haddock note to `call{Command,Process}` wrt execptions (#2233) This also tweaks Haddock comments & markup in "System.Process" while at it. Signed-off-by: Herbert Valerio Riedel <hvr(a)gnu.org> }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/2233#comment:30> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #2233: Overhaul System.Process
by GHC 03 Dec '13

03 Dec '13

#2233: Overhaul System.Process --------------------------------------+------------------------------------ Reporter: simonmar | Owner: simonmar Type: task | Status: closed Priority: normal | Milestone: _|_ Component: libraries/process | Version: 6.8.2 Resolution: fixed | Keywords: Operating System: Unknown/Multiple | Architecture: Unknown/Multiple Type of failure: None/Unknown | Difficulty: Unknown Test Case: | Blocked By: Blocking: | Related Tickets: --------------------------------------+------------------------------------ Comment (by Herbert Valerio Riedel <hvr@…>): In [changeset:"776a260be009cc27cfeacf298934d544c4e87408/process"]: {{{ #!CommitTicketReference repository="process" revision="776a260be009cc27cfeacf298934d544c4e87408" Make `cleanupProcess` resistant to SIGPIPE Otherwise, `cleanupProcess` may exit prematurely if trying to flush out data to the process' stdin handle even though the endpoint has already vanished, and fail to complete the cleanup process. See also 228297ec53e9ee7a1a6a3c5964ca7e89a6474c9b and #2233. Signed-off-by: Herbert Valerio Riedel <hvr(a)gnu.org> }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/2233#comment:29> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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