February 2008 - jhc - Haskell.org

Substitutions.
by Lemmih 28 Feb '08

28 Feb '08

Hiya, I've encountered something I don't understand in E.Subst. The substitution routine is very eager to inline stuff. It inlines all the simple applications it can find. Consider the following example: (\a -> a+a) expensive The substitution routine will inline that to: expensive+expensive Wouldn't it be prudent to generate this instead: let a = expensive in a + a Whether to inline it further would be decided later on. -- Cheers, Lemmih

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Occurance collection.
by Lemmih 26 Feb '08

26 Feb '08

Hiya, In E.SSimplify.collectOccurance the 'arg' function is used quite often and I can't tell why. The function clears usage information for free variables and is primarily used for types. It would be a great help if you'd add a short description to collectOccurance and collectDs. Any information about invariants and/or what they're trying to do would be appreciated. -- Cheers, Lemmih

2 1

Threading and atoms.
by Lemmih 24 Feb '08

24 Feb '08

Hiya, When I use -threaded and -N2 in jhc, atoms fail in spectacular ways. So far I've seen: >>> internal error: fullCheck': Instance@.iJhc.Monad.return.Jhc.Prim.IO x6598 Strong': ? x6598 Cannot strong: (?, [x6598]) and: stringlib: error alocating memory Are atoms in some way not thread-safe enough? -- Cheers, Lemmih

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darcs patch: Fix bug in E.Subst.
by Lemmih 23 Feb '08

23 Feb '08

Sat Feb 23 15:00:47 CET 2008 Lemmih <lemmih(a)gmail.com> * Fix bug in E.Subst.

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darcs patch: Cache a few items, this gives a 20% speed bump.
by Lemmih 22 Feb '08

22 Feb '08

Fri Feb 22 12:59:49 CET 2008 Lemmih <lemmih(a)gmail.com> * Cache a few items, this gives a 20% speed bump.

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darcs patch: Use an IdMap in E.Demand. This gives an 18% speed-up a...
by Lemmih 22 Feb '08

22 Feb '08

Fri Feb 22 03:14:45 CET 2008 Lemmih <lemmih(a)gmail.com> * Use an IdMap in E.Demand. This gives an 18% speed-up and smaller ho files.

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Atoms, Infos and unique ids.
by Lemmih 22 Feb '08

22 Feb '08

Hiya, TVr's can be large and are duplicated many times over. We avoid duplicating Info and type information by clearing all variables and restoring them from their binding point. Atoms are very similar to Infos in this regard: they're large enough that we don't want to keep multiple copies around. However, atoms are currently dealt with in an unsafe (see 'getMap') and inefficient manner (10mb (40%) in base-1.0.hl is wasted on duplicate strings). It is my understanding that atoms could be stored exactly like Infos. I tried to implement this but, unfortunately, atoms are frequently being relied on for unique ids. Some cases are easy to fix, others less so. John, do you have time to document the intended behavior in the difficult cases? -- Cheers, Lemmih

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jhc backend
by Csaba Hruska 21 Feb '08

21 Feb '08

Hi! Will jhc strictly generate only c code ? I know the llvm compiler framework (llvm.org) and what do you think of using llvm for (imperative) backend instead of current c backend. LLVM can generate c code too and it supports many platforms (X86, IA64, SPARC, ARM, MIPS, SPU, POWERPC) and also handles all platform specific stuff. LLVM uses an intermediate language (typed risk lile language), and uses SSA form. Many optimizations can be done via llvm. and llvm supports JIT (Just In Time ) compilationm, taht can be useful for interactive (interpreters) use of haskell. any opinion ? Cheers, Csaba Hruska P.S.: I'm new here so let me to introduce: My name is Csaba Hruska, i'm in the 5th year in university (BME budapest, hungary). i'm studiyng computer science.

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darcs patch: Makefile wibbles for jhcp and *.hsc
by Lemmih 21 Feb '08

21 Feb '08

Wed Feb 20 19:49:10 CET 2008 Lemmih <lemmih(a)gmail.com> * Makefile wibbles for jhcp and *.hsc

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darcs patch: Cache scoping info, avoid unnecessary maps. (and 2 more)
by Lemmih 21 Feb '08

21 Feb '08

Tue Feb 19 16:14:10 CET 2008 Lemmih <lemmih(a)gmail.com> * Cache scoping info, avoid unnecessary maps. Tue Feb 19 16:15:54 CET 2008 Lemmih <lemmih(a)gmail.com> * Remove debug code. Wed Feb 20 19:40:27 CET 2008 Lemmih <lemmih(a)gmail.com> * Add a comment describing the function of E.Subst.

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