January 2015 - ghc-devs

RE: vectorisation code?
by Simon Peyton Jones 12 Sep '16

12 Sep '16

Austin, (or anyone else) Manuel says: | > Would it be ok if we left it in the repo, but CPP'd it out so that | we | > didn't compile everything? (The DPH library is in the same state at | > the moment.) | > | > It might suffer bit-rot, but it’d still be there for resurrection. | | Sure, that’s ok. Could you action this? Just avoid compiling anything in 'vectorise/', using (I suppose) cpp to create a stub where necessary. Leave enough comments to explain! Simon | | I hope everything is fine in Cambridge! | Manuel | | > | -----Original Message----- | > | From: ghc-devs [mailto:ghc-devs-bounces@haskell.org] On Behalf Of | > | Manuel M T Chakravarty | > | Sent: 16 January 2015 02:58 | > | To: Richard Eisenberg | > | Cc: ghc-devs(a)haskell.org Devs | > | Subject: Re: vectorisation code? | > | | > | [Sorry, sent from the wrong account at first.] | > | | > | We currently don’t have the resources to work on DPH. I would | > | obviously prefer to leave the code in, in the hope that we will be | > | able to return to it. | > | | > | Manuel | > | | > | > Richard Eisenberg <eir(a)cis.upenn.edu>: | > | > | > | > Hi devs, | > | > | > | > There's a sizable number of modules in the `vectorise` | > | subdirectory of GHC. I'm sure these do all sorts of wonderful | > | things. But what, exactly? And, does anyone make use of these | wonderful things? | > | > | > | > A quick poking through the code shows a tiny link between the | > | vectorise code and the rest of GHC -- the function `vectorise` | > | exported from the module `Vectorise`, which is named in exactly | one | > | place from SimplCore. From what I can tell, the function will be | > | called only when `-fvectorise` is specified, and then it seems to | > | interact with a {-# VECTORISE #-} pragma. However, `{-# VECTORISE | > | #-}` doesn't appear in the manual at all, and `-fvectorise` is | > | given only a cursory explanation. It seems these work with DPH... | > | which has been disabled, no? Searching online finds several hits, | > | but nothing more recent than 2012. | > | > | > | > I hope this question doesn't offend -- it seems that | > | vectorisation probably has amazing performance gains. Yet, the | > | feature also seems unloved. In the meantime, compiling (and | > | recompiling, and | > | recompiling...) the modules takes time, as does going through | them | > | to propagate changes from elsewhere. If this feature is truly | > | orphaned, unloved, and unused at the moment, is it reasonable to | > | consider putting it on furlough? | > | > | > | > Thanks, | > | > Richard | > | > _______________________________________________ | > | > ghc-devs mailing list | > | > ghc-devs(a)haskell.org | > | > http://www.haskell.org/mailman/listinfo/ghc-devs | > | | > | _______________________________________________ | > | ghc-devs mailing list | > | ghc-devs(a)haskell.org | > | http://www.haskell.org/mailman/listinfo/ghc-devs

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arc land changes author
by Joachim Breitner 19 Dec '15

19 Dec '15

Hi, I was just about to apply a DR by David. First I ran $ arc patch D390 which put me on a feature branch. Then I reworded the commit with $ git commit --amend and then I tried to land it with $ arc land Luckily I also passed --hold... It even asked me if I want to land the commit although I am not the author: This branch has revision 'D390: Reorder GHC.List; fix performance regressions' but you are not the author. Land this revision by dfeuer? [y/N] y But it still put me in the author field: $ git show HEAD commit a387c359b99667ce55016de3816b5d9873a155db Author: Joachim Breitner <mail(a)joachim-breitner.de> Date: Wed Oct 29 08:17:05 2014 +0100 Reorder GHC.List; fix performance regressions Summary: Rearrange some oddly placed code. (and undid my commit message changes....) Did I do something wrong? Anyways, it said something along the lines of Cleaning up feature branch... (Use `git checkout -b 'arcpatch-D390' 'a3ceb0e7f44d53f728fb8bd0dfb4c97297818029'` if you want it back.) so with $ git commit --amend -C a3ceb0e7f44d53f728fb8bd0dfb4c97297818029 I was able to get the edited commit message with the right author back. Greetings, Joachim -- Joachim “nomeata” Breitner mail(a)joachim-breitner.de • http://www.joachim-breitner.de/ Jabber: nomeata(a)joachim-breitner.de • GPG-Key: 0xF0FBF51F Debian Developer: nomeata(a)debian.org

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Right way to turn off dynamic linking in build.mk
by Johan Tibell 07 Jul '15

07 Jul '15

Some times when I play around with GHC I'd like to turn off dynamic linking to make GHC compile faster. I'm not sure what the right way to do this in build.mk. It's made confusing by the conditional statements in that file: GhcLibWays = $(if $(filter $(DYNAMIC_GHC_PROGRAMS),YES),v dyn,v) This line make me worry that if I don't put DYNAMIC_GHC_PROGRAMS = NO in the right place in build.mk it wont "take". There's also this one: ifeq "$(PlatformSupportsSharedLibs)" "YES" GhcLibWays += dyn endif Seeing this makes me wonder if DYNAMIC_GHC_PROGRAMS = NO DYNAMIC_BY_DEFAULT = NO is enough or if the build system still sniffs out the fact that my platform supports dynamic linking. Could someone please give an authoritative answer to how to turn off dynamic linking? -- Johan

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Automating GHC build for Windows
by Roman Kuznetsov 29 Mar '15

29 Mar '15

Hello *, As I am still new in this, I will ask. Were there any attempt to automate GHC build process on Windows with some kind of CI engine, like Hudson, Jenkins, etc.? It seems to be rather helpful to publish build results if not after each commit, but at least once every day. WDYT? -- Sincerely yours, Roman Kuznetsov

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Porting to Haiku
by Jessica Hamilton 11 Mar '15

11 Mar '15

Hi, I (and one other) am working on porting GHC to Haiku; we've successfully got a working GHC cross-compiler running on Haiku, and now are able to also build GHC on Haiku from the cross-compiler when using the "quickest" profile in the mk/build.mk file. However, using the default build profile, we're running into a couple of issues. 1. A random segfault in ghc-stage1 (is probably an issue in Haiku, not entirely sure yet), with the following call stack: runCFinalizers + 0x3a runAllCFinalizers + 0x37 hs_exit_ +0x99 shutdownHaskellAndExit + 0x2f hs_main + 0xb1 .../ghc-7.8.3/inplace/lib/bin/ghc-stage1 + 0xc7b374 _start + 0x4b runtime_loader + 0x130 I can't really see anything obvious in the source code myself (although our debugger fails to enumerate the semaphores, and also needs to be killed). Restarting the build is sufficient to get past the issue, however. 2. A more pressing issue is with ghc-cabal. It fails with the error "resource exhausted" when running the following command: inplace/bin/ghc-cabal copy compiler stage2 This error is reproducible every time. I've tried setting up a profile build in the mk/build.mk file in order to get a stack trace from ghc-cabal; however, after rebuilding GHC from scratch, running ghc-cabal +RTS -xc, it still complains that the flag -xc requires the program to be built with -prof. Some advice would be handy before diving into another couple hours of rebuilding GHC to try and get a profiled build of ghc-cabal out of the build system ;-) Cheers, Jessica

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76-fold regression GHC 7.10->7.11 in T9961 byte-allocation
by Herbert Valerio Riedel 20 Feb '15

20 Feb '15

Hello *, I noticed something odd while validating the GHC 7.10 branch: bytes allocated value is too low: (If this is because you have improved GHC, please update the test so that GHC doesn't regress again) Expected T9961(normal) bytes allocated: 772510192 +/-5% Lower bound T9961(normal) bytes allocated: 733884682 Upper bound T9961(normal) bytes allocated: 811135702 Actual T9961(normal) bytes allocated: 9766160 Deviation T9961(normal) bytes allocated: -98.7 % *** unexpected stat test failure for T9961(normal) ...then I also ran ./validate against today's GHC HEAD, and re-ran the T9961 test: Expected T9961(normal) bytes allocated: 772510192 +/-5% Lower bound T9961(normal) bytes allocated: 733884682 Upper bound T9961(normal) bytes allocated: 811135702 Actual T9961(normal) bytes allocated: 748225848 Deviation T9961(normal) bytes allocated: -3.1 % I'm not sure if it's just the test-case being broken, or there's something real regression between 7.10 and HEAD... However, I don't have time to investigate this. Cheers, hvr

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ANNOUNCE: GHC 7.10.1 Release Candidate 2
by Austin Seipp 17 Feb '15

17 Feb '15

We are pleased to announce the second release candidate for GHC 7.10.1: https://downloads.haskell.org/~ghc/7.10.1-rc2/ This includes the source tarball and bindists for 64bit/32bit Linux and Windows. Binary builds for other platforms will be available shortly. (CentOS 6.5 binaries are not available at this time like they were for 7.8.x). These binaries and tarballs have an accompanying SHA256SUMS file signed by my GPG key id (0x3B58D86F). We plan to make the 7.10.1 release sometime in February of 2015. Please test as much as possible; bugs are much cheaper if we find them before the release! -- Regards, Austin Seipp, Haskell Consultant Well-Typed LLP, http://www.well-typed.com/

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Can't install packages with my inplace compiler
by Simon Peyton Jones 06 Feb '15

06 Feb '15

When I say cabal install --with-ghc=/home/simonpj/5builds/HEAD-2/inplace/bin/ghc-stage2 I get this ghc-stage2: ghc no longer supports single-file style package databases (dist/package.conf.inplace) use 'ghc-pkg init' to create the database with the correct format. Now, this is an old build tree, and I could blow it away entirely, but maybe there is something else going on. What should I do? Thanks (all on Linux) Simon

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Generic instances for GHC AST
by Alan & Kim Zimmerman 06 Feb '15

06 Feb '15

At the moment every part of the GHC AST derives instances of Data and Typeable. There are no instances of Generic. If I try to standalone derive these, the derivation eventually fails for deriving instance Generic (Name) because the constructors are not all in scope. So, does it make sense in GHC to at least derive Generic for the items that are opaque, and at most to do so for the whole AST. I know there were some concerns earlier about too many instances being derived, and its impact on compilation time and memory, so the minimal version may be best. This will allow the new generation libraries built around Generics to perform on GHC data structures too. Alan

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Restricted Template Haskell
by Greg Weber 03 Feb '15

03 Feb '15

Hello GHC friends! I am starting up a proposal for variants of Template Haskell that restrict what operations are available. The goal is to make TH easier for users to reason about and to allow for an easier compilation story. Here is the proposal page: https://ghc.haskell.org/trac/ghc/wiki/TemplateHaskell/Restricted Right now the proposal does not have any details and the goal is to write out a clear specification. If this sounds interesting to you, let me know or leave some feedback on the wiki. Thanks, Greg Weber

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