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Datacon RULES test
by David Feuer 24 Feb '17

24 Feb '17

For good or ill, Simon doesn't want RULES for datacons. T12689 has to be removed (leaving T12689a, which is still fine). But I don't know enough about what you're doing with T12689broken to know how to make it express the right idea after this change. Can you please advise? Thanks, David Feuer Well-Typed LLP

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Windows build broken
by Simon Peyton Jones 22 Feb '17

22 Feb '17

Please please please could some one fix this? On windows. It's frustrating being unable to build. Please please Simon libraries\time\lib\Data\Time\Clock\Internal\SystemTime.hs:57:5: error: Not in scope: data constructor FILETIME Perhaps you meant Win32.FILETIME (imported from System.Win32.Time) | 57 | FILETIME ft <- Win32.getSystemTimeAsFileTime | ^^^^^^^^

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RE: Windows build broken
by Simon Peyton Jones 22 Feb '17

22 Feb '17

Re-adding ghc-devs. | Settup up things so that all master pushes go through a build&smoke-test-on- | all-relevant-platforms purgatory shouldn't be that problematic.. I know. We discuss it periodically The trouble is that it takes work to do these things (reliably, solidly) and everyone is busy. If someone felt able to step up to doing it, it'd be great. Simon | -----Original Message----- | From: Kosyrev Serge [mailto:skosyrev@ptsecurity.com] | Sent: 22 February 2017 14:18 | To: Simon Peyton Jones <simonpj(a)microsoft.com> | Subject: Re: Windows build broken | | Simon, | | It pains me to see how something trivially preventable by a functioning | "continuous integration" setup keeps causing you trouble so regularly. | | Settup up things so that all master pushes go through a build&smoke-test-on- | all-relevant-platforms purgatory shouldn't be that problematic.. | | I know, it's not my ground to meddle in, but I just can't be calmly watching | this entirely preventable suffering.. | | Simon Peyton Jones via ghc-devs writes: | > Please please please could some one fix this? On windows. | > | > It’s frustrating being unable to build. | > | > Please | > | > please | > | > Simon | > | > libraries\time\lib\Data\Time\Clock\Internal\SystemTime.hs:57:5: error: | > | > Not in scope: data constructor FILETIME | > | > Perhaps you meant Win32.FILETIME (imported from System.Win32.Time) | > | > | | > | > 57 | FILETIME ft <- Win32.getSystemTimeAsFileTime | > | > | ^^^^^^^^ | | -- | с уважениeм / respectfully, not a GHC developer at all, Косырев Сергей | -- | “Most deadly errors arise from obsolete assumptions.” | -- Frank Herbert, Children of Dune

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Status of early-inline branch
by David Feuer 21 Feb '17

21 Feb '17

I've been working on trying to get the branch in shape for review and such, but I see that you're also still working on it. So we don't tread on each other's toes too much, I'm wondering if you could give me a sense of what the status is, which commits are firm and which you might change, etc. Thanks, David Feuer

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XTypeApplication and @spaces
by Gracjan Polak 21 Feb '17

21 Feb '17

Hi all, I was thinking about implementing @Type syntax <https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/glasgow_ext…> highlight for haskell-mode <https://github.com/haskell/haskell-mode> and noticed a rule about spacing required before @-sign. I do not understand where does this rule come from and what does it buy us. Experimentation shows that @-patterns do not care about spaces at all: Prelude> let f a @ Nothing = print a in f Nothing Nothing Comment next to implementation says: "This, of course, conflicts with as-patterns. The conflict arises because expressions and patterns use the same parser, and also because we want to allow type patterns within expression patterns." As I understand pattern and expression contexts are always separate in Haskell so the part just after 'of course' is not clear to me. Can I get an example for "we want to allow type patterns within expression patterns"? I understand the part "expressions and patterns use the same parser" but then I'd rather file a bug report about this one. Rationale: I'd rather limit usage for horizontal space to separate tokens on the lexer level. This looks like it tries to promote space to separate things on parser level, which is rather hard to get right in crude parsers that we have for syntax highligh, indentation, completion and the like. -- Gracjan

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Re: Time library broken
by Ryan Scott 21 Feb '17

21 Feb '17

There also appears to be a plain old build failure on Windows with time-1.8. Here's an excerpt [1] from a failing Harbormaster build: libraries\time\lib\Data\Time\Clock\Internal\SystemTime.hs:57:5: error: Not in scope: data constructor ‘FILETIME’ Perhaps you meant ‘Win32.FILETIME’ (imported from System.Win32.Time) | 57 | FILETIME ft <- Win32.getSystemTimeAsFileTime | ^^^^^^^^ Ryan S. ----- [1] https://phabricator.haskell.org/harbormaster/build/21312/?l=100

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Time library broken
by Simon Peyton Jones 21 Feb '17

21 Feb '17

I'm getting this libraries/time/lib/Data/Time/Clock/Internal/SystemTime.hs:1:14: warning: [-Wtrustworthy-safe] 'Data.Time.Clock.Internal.SystemTime' is marked as Trustworthy but has been inferred as safe! | 1 | {-# LANGUAGE Trustworthy #-} | ^^^^^^^^^^^ Since I use -Werror in stage2, my build fails. Simon

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Superclasses
by Simon Peyton Jones 20 Feb '17

20 Feb '17

Edward In comment:23 of https://ghc.haskell.org/trac/ghc/ticket/11523 I claim that there is an infinite tower of superclasses, so that GHC can legitimately spin. You have not responded for nearly a year. Do you agree? Simon

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Early inline
by Simon Peyton Jones 19 Feb '17

19 Feb '17

Ben, David, Reid I have been working for months (on and off, mostly off, but very ON for the last week or two) on a very simple idea: the simplifier should inline things even in the "gentle" phase. It seems so simple. And it is: the key patch is tiny. But it stressed corners of the optimiser that were not stressed before; and digging into it showed opportunities I did not know about before. So I have ended up a with a whole series of patches, which are on wip/spj-early-inline branch 7f14d15c0e5fc2c9a81db3d0f0b01d85857b1d87 Error message wibbles accumulated from the preceding patches 0499c65d9fa45e7879e1e1264fdaa15274adcba6 Improve SetLevels for join points 3b2fc0827ff6cafa34836c2d9dc710b628c990b6 Change -ddump-tc-trace output in TcErrors, slightly 9ffdf62b0ca72c4f35579f9d6f31a9beebf23025 Improve pretty-printing of types 3f346eac06399a79adf48425018ee949cee245bf Add VarSet.anyDVarSet, allDVarSet 912e71eb3b4ec91e805ecf2236d1033e55e2933a The Early Inline Patch 7188cd13f8e54efa764d52ca016b87b3669b29f5 Small changes to expression sizing in CoreUnfold bfc6fa3f377d11bdfcdbf82b65bf2f39cb00b90c Fix SetLevels for makeStaticPtr 8b1cfea089faacb5b95ffcc3511e05faeabb8076 Extend CSE to handle recursive bindings 50411995641802568bb27c867afe804f91e0524c Combine identical case alterantives in CSE 2e077ccc736a0b2a622b7f42b7929966bddb4ded Inline data constructor wrappers in phase 2 only b868de53dd19f639c1070089ecff21948ff33e0d Make Specialise work with casts c767ae5f04a09ef71dcb8f67a17225a52c2cc5d2 Stop uniques ending up in SPEC rule names b49ed1f0102f93ca7f62632c436b41bd240b501f Occurrence-analyse the result of rule firings 607a735dfb99bb8f0edf466ccb01e732218c42ec Add -fspec-constr-keen 67a0c1872c0515f1f12ea68097a84e02da92f45b Refactor floating of bindings (fiBind) e90f4d7c6d3003039fa1647a3da3dafcaa75527b More tracing in SpecConstr Much to my surprise, we get some jolly nice improvements in compiler perf: 3% perf/compiler/T5837.run T5837 [stat too good] (normal) 7% perf/compiler/parsing001.run parsing001 [stat too good] (normal) 9% perf/compiler/T12234.run T12234 [stat too good] (optasm) 35% perf/compiler/T9020.run T9020 [stat too good] (optasm) 9% perf/compiler/T3064.run T3064 [stat too good] (normal) 13% perf/compiler/T9961.run T9961 [stat too good] (normal) 20% perf/compiler/T13056.run T13056 [stat too good] (optasm) 5% perf/compiler/T9872d.run T9872d [stat too good] (normal) 5% perf/compiler/T9872c.run T9872c [stat too good] (normal) 5% perf/compiler/T9872b.run T9872b [stat too good] (normal) 7% perf/compiler/T9872a.run T9872a [stat too good] (normal) 5% perf/compiler/T783.run T783 [stat too good] (normal) 35% perf/compiler/T12227.run T12227 [stat too good] (normal) 20% perf/compiler/T1969.run T1969 [stat too good] (normal) 5% perf/should_run/lazy-bs-alloc.run lazy-bs-alloc [stat too good] (normal) 5% perf/compiler/T12707.run T12707 [stat too good] (normal) 4% perf/compiler/T3294.run T3294 [stat too good] (normal) 1.5% perf/space_leaks/T4029.run T4029 [stat too good] (ghci) So what is left? I have sunk so much time into this and am still not QUITE out of the woods. I was left with Unexpected failures: codeGen/should_compile/debug.run debug [bad stdout] (normal) concurrent/should_run/T4030.run T4030 [bad exit code] (normal) I'm re-validating having pulled from HEAD, but I THINK that's all. Now * I don't know how to Phab these individually * I have not sweated through which patch is responsible for which perf improvments. Maybe Gipeda can tell? * I have not put each error message change with the correct patch. I don't know how much that matters. So this is to say: anything you guys can do to help get this actually Done would be really helpful. I'm out of time till Monday at least. It would be great to collect those performance improvements! Thanks! Simon

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Static data and RULES
by David Feuer 18 Feb '17

18 Feb '17

Ben Gamari and Reid Barton are interested in making it cheaper for static data to pass through simplification. The basic idea is that if a term is already made entirely of data constructors and literals, then there's nothing left to optimize. However, RULES are allowed to match on data constructors and it would be nice to let that keep happening. But on the other hand, RULES are apparently (according to Duncan Coutts) already broken for strict data constructors, because they have workers and wrappers. My thought: let's allow phased INLINE and NOINLINE pragmas for data constructors. The default would be INLINE. The ~ phase choice would not be available: once inline, always inline. Semantics ~~~~~~~~~~ For all constructors: If a constructor is allowed by pragmas to inline in a certain phase, then in that phase terms built from it can be considered static. Once static, always static. If a constructor is not allowed to inline in a certain phase, terms built from it will be considered non-static. After demand analysis and worker/wrapper, all constructors are considered inline. For strict constructors: A strict constructor wrapper prohibited from inlining in a certain phase simply will not. Strict constructor wrappers will all be allowed to inline after demand analysis and worker/wrapper. This matches the way we now handle wrappers actually created in that phase. Syntax: For GADT syntax, this is easy: data Foo ... where {-# INLINE [1] Bar #-} Bar :: ... For traditional syntax, I think it's probably best to pull the pragmas to the top: {-# NOINLINE Quux #-} data Baz ... = Quux ... | ...

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