- Glasgow-haskell-users

How do we best make sure {Int,Word,Float,Double} to {Int,Word,Float,Double} conversions stay efficient
by Johan Tibell 17 Dec '12

17 Dec '12

Hi, I've been tracking down a few (unrelated) performance bugs related to conversions between primitive types. What these issues had in common is that some rule failed to fire and the conversion went via Integer, killing performance. How do we best write a test that make sure that fromIntegral conversions between these types don't regress? Is it possible to test the output of the simplifier or do we have to do something less direct, like writing a loop that does such conversions and make sure that the allocation stay low? -- Johan

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Haskell Dynamic Loading with -fllvm
by Nathaniel Neitzke 13 Dec '12

13 Dec '12

Essentially I have a use case that, if worked, would save countless hours in development time. I am writing a scientific computing web service utilizing the Repa and Snap libraries. The Snap framework has a dynamic loader that will load modules on the fly when the source files change. This works excellent! The problem is that the modules must be compiled with full optimizations (including -fllvm) or web service operations take minutes instead of < second to execute at run time. I do not mind the penalty paid for optimized compilation. It is still much faster than recompiling and linking the entire exe from scratch and restarting the server. The problem is when the code is compiled with -fllvm dynamically, it crashes. I believe this is a known issue as listed in this trac - http://hackage.haskell.org/trac/ghc/ticket/4210 NOTE: it says "The LLVM backend doesn't support dynamic libraries at the moment." My question is could anyone point me in the right direction as to what might need to be implemented support for this? Is anyone currently working on it? It would be a huge win for the work I am currently doing, to the point where if I can't find a way to get this working (even if it means diving in and attacking it myself), I may have to switch to another language/platform. Thanks, Nathan

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Hoopl vs LLVM?
by Greg Fitzgerald 13 Dec '12

13 Dec '12

I don't know my way around the GHC source tree. How can I get the list of optimizations implemented with Hoopl? Is there overlap with LLVM's optimization passes? If so, has anyone compared the implementations at all? Should one group be stealing ideas from the other? Or apples and oranges? Thanks, Greg

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Mailing list reorganisation
by Ian Lynagh 12 Dec '12

12 Dec '12

Hi all, Following a recent discussion, we propose to reorganise the GHC-related mailing lists so that we end up with: glasgow-haskell-users For user discussions ghc-devs For developer discussions ghc-commits For automated commit messages from the git repositories ghc-builds For automated nightly build reports ghc-tickets For automated messages from trac We would remove cvs-ghc cvs-libraries cvs-other glasgow-haskell-bugs but leave the archives in place, and for now forwarding messages to cvs-* to ghc-devs, and glasgow-haskell-bugs to ghc-tickets. (cvs-libraries and cvs-other are included in this list, because we think they are mainly used by libraries that GHC HQ maintains, or by GHC's lagging repos of libraries that other people maintain). The initial subscriber lists for ghc-devs, ghc-commits and ghc-builds would be the union of the subscribers of cvs-ghc, cvs-libraries and cvs-other. For ghc-tickets it would be the subscriber list for glasgow-haskell-bugs. Does that sound reasonable? Does anyone have any further questions or comments? Thanks Ian

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ghc-7.6.2 breaks haddock interface...
by Joachim Breitner 12 Dec '12

12 Dec '12

Hi, I built GHC 7.6.2-rc1 for Debian. Unfortunately, we have this: Control files of package ghc-haddock: lines which differ (wdiff format) ----------------------------------------------------------------------- Depends: ghc (= [-7.6.1-3),-] {+7.6.1.20121207-1),+} libc6 (>= 2.11), libffi5 (>= 3.0.4), libgmp10 Installed-Size: [-32917-] {+33044+} Provides: haddock, [-haddock-interface-21-] {+haddock-interface-22+} Version: [-7.6.1-3-] {+7.6.1.20121207-1+} i.e. upstream has bumped the haddock interface number. I really was not expecting this from a minor release. @GHC devs: Is that intentional? I.e., is there really a change to the on-disk format of the .haddock files? Can we expect this to be stable until 7.6.2 final? In general, please only bump the interface number if really required, makes live much easier for us (and probably also for some of your other users). @Debian: If the answer is yes, what should we do? I think I have automated rebuilding everything (at least everything in Darcs) enough to make that not as painful as it used to be, but it would still take some time. On the other hand, it would break Haskell in experimental for some time (maybe a week, optimistically). But then, it is already partly broken. Thanks, Joachim -- Joachim "nomeata" Breitner Debian Developer nomeata(a)debian.org | ICQ# 74513189 | GPG-Keyid: 4743206C JID: nomeata(a)joachim-breitner.de | http://people.debian.org/~nomeata

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Re: [Haskell-cafe] GHCi + FFI + global C variables
by Brandon Allbery 11 Dec '12

11 Dec '12

On Tue, Dec 11, 2012 at 5:57 AM, Francisco Vieira de Souza < vieira.ufpi(a)gmail.com> wrote: > Hi Simon! Is it not necessary to show the type of igraph_bool_t > igraphhaskell_initialized like > > "int igraph_bool_t igraphhaskell_initialized = 0"? > "igraph_bool_t" uses the _t suffix convention for typedefs in C; in other words, it *is* the type. (And if it weren't, that would be a compile time error, not link time.) -- brandon s allbery kf8nh sine nomine associates allbery.b(a)gmail.com ballbery(a)sinenomine.net unix, openafs, kerberos, infrastructure, xmonad http://sinenomine.net

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GHCi + FFI + global C variables
by Nils 11 Dec '12

11 Dec '12

I'm currently working with a C library that needs to use/modify global C variables, for example: igraph_bool_t igraphhaskell_initialized = 0; int igraphhaskell_initialize() { if (igraphhaskell_initialized != 0) { printf("C: Not initializing. igraphhaskell_initialized = %i\n", igraphhaskell_initialized); return 1; } // initialization } If I compile an example programm using this library everything works fine, but if I try to run the same program in GHCi it dies with the message C: Not initializing. igraphhaskell_initialized = -907777 The value (and apparently the adress of the global variable) is completly off, and I have no idea what is causing this or how to solve this issue and make the library GHCi-friendly. Is it possible to run this code in GHCi at all? Also, since it's a foreign library I obviously cannot just change the C code to simply not use any global variables at all. - Nils

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How to use C-land variable from Cmm-land?
by Yuras Shumovich 11 Dec '12

11 Dec '12

Hi, I'm working on that issue as an exercise/playground while studding the GHC internals: http://hackage.haskell.org/trac/ghc/ticket/693 First I tried just to replace "ccall lockClosure(mvar "ptr")" with GET_INFO(mvar) in stg_takeMVarzh and stg_putMVarzh and got 60% speedup (see the test case at the end.) Then I changed lockClosure to read header info directly when enabled_capabilities == 1. The speedup was significantly lower, <20% I tried to hack stg_putMVarzh directly: if (enabled_capabilities == 1) { info = GET_INFO(mvar); } else { ("ptr" info) = ccall lockClosure(mvar "ptr"); } But got no speedup at all. The generated asm (amd64): movl $enabled_capabilities,%eax cmpq $1,%rax je .Lcgq .Lcgp: movq %rbx,%rdi subq $8,%rsp movl $0,%eax call lockClosure addq $8,%rsp .Lcgr: cmpq $stg_MVAR_CLEAN_info,%rax jne .Lcgu {...} .Lcgq: movq (%rbx),%rax jmp .Lcgr It moves enabled_capabilities into %eax and then compares 1 with %rax. It looks wrong for me: the highest part of %rax remains uninitialized. (And actually it ignores the highest 32 bits of enabled_capabilities. That is ok here, but generally wrong.) The compiler knows that enabled_capabilities is 64bit (it complains when trying to assign it to bits32 register.) What do I miss? Any help? Thanks, Yuras -- The test case import Control.Concurrent import Control.Monad main :: IO () main = do var <- newMVar () replicateM_ 100000000 $ do takeMVar var putMVar var ()

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cabal-install use multiple config files?
by Stephen Paul Weber 09 Dec '12

09 Dec '12

I don't see a command-line switch to ask cabal-install to use a different config file. Is there an environment variable for it or something? I want to use the same cabal-install binary with three different installs of ghc and ghc-pkg to allow me to maintain my cross-compiler packages as well. -- Stephen Paul Weber, @singpolyma See <http://singpolyma.net> for how I prefer to be contacted edition right joseph

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building GHC for "antique" OSX
by wren ng thornton 09 Dec '12

09 Dec '12

Hello all, I'm one of those curmudgeons still working on OSX 10.5.8. Recently I finally got around to building the latest GHC and, FWIW, everything seems to have worked out fine. I did get a few failed tests in the testsuite though, and I'm curious what they mean or if they're actually cause for concern? OVERALL SUMMARY for test run started at Fri Dec 7 10:49:39 EST 2012 3402 total tests, which gave rise to 14436 test cases, of which 0 caused framework failures 11364 were skipped 2985 expected passes 47 had missing libraries 34 expected failures 0 unexpected passes 6 unexpected failures Unexpected failures: ../../libraries/directory/tests T4113 [bad stdout] (normal) concurrent/should_run conc070 [bad stdout or stderr] (ghci) ghci/should_run 3171 [bad stdout] (normal) perf/haddock haddock.Cabal [stat too good] (normal) perf/haddock haddock.base [stat too good] (normal) perf/haddock haddock.compiler [stat too good] (normal) -- Live well, ~wren

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