July 2015 - ghc-tickets

Re: [GHC] #7450: Regression in optimisation time of functions with many patterns (6.12 to 7.4)?
by GHC 06 Jul '15

06 Jul '15

#7450: Regression in optimisation time of functions with many patterns (6.12 to 7.4)? -------------------------------------+------------------------------------- Reporter: iustin | Owner: bgamari Type: bug | Status: patch Priority: normal | Milestone: 7.12.1 Component: Compiler | Version: 7.6.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Compile-time | Unknown/Multiple performance bug | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Revisions: Phab:D1012 -------------------------------------+------------------------------------- Comment (by bgamari): I finally had a chance to look further into this. It seems that after the fix `CmmPipeline.doRTs` may still be non-linear. With 2048 constructors, {{{ COST CENTRE MODULE %time %alloc lintAnnots CoreLint 12.5 20.4 doSRTs CmmPipeline 11.6 16.9 FloatOutwards SimplCore 6.3 2.0 simplLetUnfolding Simplify 4.5 2.7 pprNativeCode AsmCodeGen 4.3 5.0 completeBind Simplify 4.1 2.0 StgCmm HscMain 3.3 2.7 ... }}} With 4096 constructors, {{{ COST CENTRE MODULE %time %alloc doSRTs CmmPipeline 23.0 33.0 lintAnnots CoreLint 16.9 26.5 FloatOutwards SimplCore 7.8 1.6 completeBind Simplify 4.0 1.2 simplLetUnfolding Simplify 3.9 1.6 pprNativeCode AsmCodeGen 3.3 3.3 ... }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7450#comment:22> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10575: "unsatisfied constraints" typo
by GHC 06 Jul '15

06 Jul '15

#10575: "unsatisfied constraints" typo -------------------------------------+------------------------------------- Reporter: ekmett | Owner: ekmett Type: bug | Status: new Priority: low | Milestone: Component: Core | Version: 7.10.1 Libraries | Operating System: Unknown/Multiple Keywords: | Type of failure: None/Unknown Architecture: | Blocked By: Unknown/Multiple | Related Tickets: Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- {{{ UnsatisfiedConstraints -> "unsatisified constraints" }}} should be {{{ UnsatisfiedConstraints -> "unsatisfied constraints" }}} in http://hackage.haskell.org/package/base-4.8.0.0/docs/src/GHC-IO- Exception.html#line-326 -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10575> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10519: Can't put wildcard behind forall
by GHC 06 Jul '15

06 Jul '15

#10519: Can't put wildcard behind forall -------------------------------------+------------------------------------- Reporter: yongqli | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.1-rc3 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Blocked By: Test Case: | Related Tickets: Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- This type signature doesn't compile: {{{ forall v. _ => Acc (Array DIM2 (v Double)) -> Acc (Array DIM2 (v Double)) -> Acc (A.Vector Double) -> Acc (Array DIM2 Double) }}} with "Invalid partial type signature ... An extra-constraints wildcard is only allowed at the top-level of the signature" I need the forall because I use `v` in the body of the function. This occurs with version 7.10.1.20150612 but not 7.10.1.20150519 -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10519> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7450: Regression in optimisation time of functions with many patterns (6.12 to 7.4)?
by GHC 06 Jul '15

06 Jul '15

#7450: Regression in optimisation time of functions with many patterns (6.12 to 7.4)? -------------------------------------+------------------------------------- Reporter: iustin | Owner: bgamari Type: bug | Status: patch Priority: normal | Milestone: 7.12.1 Component: Compiler | Version: 7.6.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Compile-time | Unknown/Multiple performance bug | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Revisions: Phab:D1012 -------------------------------------+------------------------------------- Comment (by Ben Gamari <ben@…>): In [changeset:"4681f55970cabc6e33591d7e698621580818f9a2/ghc"]: {{{ #!CommitTicketReference repository="ghc" revision="4681f55970cabc6e33591d7e698621580818f9a2" Specialise: Avoid unnecessary recomputation of free variable information When examining compile times for code with large ADTs (particularly those with many record constructors), I found that the specialiser contributed disproportionately to the compiler runtime. Some profiling suggested that the a great deal of time was being spent in `pair_fvs` being called from `consDictBind`. @simonpj pointed out that `flattenDictBinds` as called by `specBind` was unnecessarily discarding cached free variable information, which then needed to be recomputed by `pair_fvs`. Here I refactor the specializer to retain the free variable cache whenever possible. **Open Qustions** * I used `fst` in a couple of places to extract the bindings from a `DictBind`. Perhaps this is a sign that `DictBind` has outgrown its type synonym status? Test Plan: validate Reviewers: austin, simonpj Reviewed By: simonpj Subscribers: thomie, bgamari, simonpj Differential Revision: https://phabricator.haskell.org/D1012 GHC Trac Issues: #7450 }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7450#comment:21> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9839: RTS options parser silently accepts invalid flags
by GHC 05 Jul '15

05 Jul '15

#9839: RTS options parser silently accepts invalid flags -------------------------------------+------------------------------------- Reporter: adamgundry | Owner: simonmar Type: bug | Status: new Priority: normal | Milestone: Component: Runtime System | Version: 7.8.3 Keywords: | Operating System: Architecture: Unknown/Multiple | Unknown/Multiple Difficulty: Unknown | Type of failure: Incorrect Blocked By: | result at runtime Related Tickets: #4243 | Test Case: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- RTS options that do not take arguments (such as `-T`) silently ignore anything that comes afterwards. For example, `+RTS -T,-s` or `+RTS -T-s` turns on collection of GC statistics (`-T`) but does not print out a summary (`-s`). Instead, this should produce an error message. Otherwise, users may mistakenly think that options have been applied. (This has just bitten us in a production system.) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9839> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8206: Add support for Portable Native Client
by GHC 05 Jul '15

05 Jul '15

#8206: Add support for Portable Native Client -------------------------------------------------+------------------------- Reporter: guest | Owner: Alex Type: feature request | Sayers Priority: normal | Status: new Component: Compiler | Milestone: Keywords: NaCl PNaCl Portable Native | Version: Client pexe | Operating System: Architecture: Unknown/Multiple | Unknown/Multiple Difficulty: Project (more than a week) | Type of failure: Blocked By: | None/Unknown Related Tickets: | Test Case: | Blocking: -------------------------------------------------+------------------------- == Motivation == [http://www.chromium.org/nativeclient/pnacl/building-and-testing-portable- native-client Portable Native Client] (PNaCl) is a feature in Google Chrome which (roughly) allows it to use LLVM bitcode like browsers use javascript today. The bitcode is downloaded, validated, compiled, and (safely) executed, with access to an API for manipulating the DOM of the page which loaded it. The dream: Haskell executed in the browser at near- native speed. Unfortunately, while GHC has an LLVM backend, the bitcode it generates doesn't satisfy the PNaCl validator. == Portable Native Client == The user visits a page with an <embed> tag pointing to a "pexe" - a PNaCl bitcode file. The bitcode is downloaded and streamed first into a code validator, and then into a compiler. The resulting machine code is then executed as a memory-protected process. The [https://developers.google.com /native-client/pepperc/ Pepper API], a library Google provides, provides access to the browser for things like connecting to websockets, playing audio, and communicating with javascript running on the page. PNaCl is present in Chrome 29 (go to chrome://flags to enable it), and will be enabled for arbitrary sources (the "open web") in Chrome 30. Mozilla have announced that they don't intend to support Native Client. == The Easily-Fixed == The pexe bitcode format is a frozen subset of LLVM bitcode. The PNaCl toolchain provides `pnacl-finalize`, which translates LLVM bitcode into pexe bitcode. PNaCl [http://www.chromium.org/nativeclient/pnacl/bitcode- abi##callingconventions only allows] the standard "ccc" calling convention, whereas GHC likes to use its own "cc 10" calling convention. You can make GHC use ccc by using an unregisterised build, for a slow-down factor of about 2. It seems likely that code-next-to-tables will upset the validator. If so, this can be turned off for a small performance hit. == The Not-So-Easily-Fixed == The validator requires that requests for IO are sent to Pepper. PNaCl also requires that you use newlib instead of glibc. Spawning new processes is forbidden (although creating pthreads is fine). It also seems likely that the validator with take umbrage at calls to `mmap`, which the GHC runtime uses to request memory allocation. It seems, therefore, that significant chunks of the RTS will have to be ported. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8206> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10605: mispelling Indentity in Data.Traversable
by GHC 05 Jul '15

05 Jul '15

#10605: mispelling Indentity in Data.Traversable -------------------------------------+------------------------------------- Reporter: uznx | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: | Version: 7.10.1 libraries/base | Operating System: Unknown/Multiple Keywords: | Type of failure: None/Unknown Architecture: | Blocked By: Unknown/Multiple | Related Tickets: Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- The documentation for Data.Traversable has Identity misspelled as Indentity: instance Applicative Indentity where -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10605> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8353: Easy way to defer type errors
by GHC 04 Jul '15

04 Jul '15

#8353: Easy way to defer type errors ------------------------------------+------------------------------------- Reporter: goldfire | Owner: Type: feature request | Status: new Priority: normal | Milestone: Component: GHCi | Version: 7.6.3 Keywords: | Operating System: Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: None/Unknown Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ------------------------------------+------------------------------------- A number of comments I've heard recently have focused on the joy of `-fdefer-type-errors`, especially for newcomers to Haskell. However, in GHCi, one has to 1. be aware that `-fdefer-type-errors` exists 2. know the `:set ...` syntax to turn it on, and then 3. is stuck with this setting on until they turn it off Instead, I propose new `:load!` and `:reload!` commands (abbreviated to `:l!` and `:r!`) which turn on `-fdefer-type-errors` just for that one command. When a load or reload fails, the error message could suggest these alternate forms. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8353> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #5941: Add compilation stage plugins
by GHC 04 Jul '15

04 Jul '15

#5941: Add compilation stage plugins -------------------------------------+------------------------------------- Reporter: tibbe | Owner: Type: feature request | Status: infoneeded Priority: normal | Milestone: 7.12.1 Component: Compiler | Version: 7.4.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: None/Unknown | Unknown/Multiple Blocked By: | Test Case: Related Tickets: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- Changes (by adamgundry): * cc: adamgundry (added) Comment: I've felt for a while that there should be better integration between [wiki:Plugins/TypeChecker plugins] and [wiki:Ghc/Hooks hooks], so that a plugin could hook into more stages of the compilation pipeline, and that hooks could register typechecker plugins. But I don't have a clear design yet, nor any spare cycles to work on this at the moment. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/5941#comment:7> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7389: can't link postgresql-libpq on windows
by GHC 04 Jul '15

04 Jul '15

#7389: can't link postgresql-libpq on windows -------------------------------------+------------------------------------- Reporter: eflister | Owner: Type: bug | Status: closed Priority: normal | Milestone: 7.12.1 Component: GHCi | Version: 7.4.1 Resolution: fixed | Keywords: Operating System: Windows | Architecture: x86_64 Type of failure: Runtime crash | (amd64) Blocked By: 3658 | Test Case: Related Tickets: #9907 | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- Changes (by Phyx-): * status: new => closed * resolution: => fixed * related: => #9907 * blockedby: 3658, 5987 => 3658 Comment: Already fixed in 7.10.1 by #9907 -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7389#comment:7> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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