Pusing to haddock

Tue Jun 14 08:18:20 UTC 2016

|  tests/alloc/haddock.Cabal 	11811321368 	+ 6.40% 	12567003040
|  	bytes
|  tests/alloc/haddock.compiler 	60211764264 	+ 7.39%
|  	64658444232 	bytes
|  
|  The haddock stats changes are probably genuine, I assume, but the
|  expected value in all.T should be updated.
|  

I'm sad about this. My changes should have had no visible performance impact. But I'm not set up to dig into why this one patch might have had such large impact on Haddock.  Presumably it's not Haddock per-se but perhaps the GHC session that it invokes.

I am not sure what to do... I'm quite reluctant to cause a 7% regression in allocation without investigation.  I suppose I or someone should investigate before-and-after, but I don't have time to do that this week.

If someone felt able to have a go, that'd be fantastic.  Otherwise let's at least make a ticket. 

For the record, the series of patches, one of which presumably causes the regression, is below.   Bisecting to the right one would be very helpful -- but you have to apply the final one (haddock-update) first.

Sigh.  I should be more careful.

Simon

commit d55a9b4fd5a3ce24b13311962bca66155b17a558
Author: Simon Peyton Jones <simonpj at microsoft.com>
Date:   Mon Jun 13 18:28:30 2016 +0100

    Update Haddock to follow change in LHsSigWcType

    Update submodule to accompany this commit:

        commit 15b9bf4ba4ab47e6809bf2b3b36ec16e502aea72
        Author: Simon Peyton Jones <simonpj at microsoft.com>
        Date:   Sat Jun 11 23:49:27 2016 +0100

            Improve typechecking of let-bindings

    Sorry it's late!

commit 0497ee504cc9ac5d6babee9b98bf779b3fc50b98
Author: Bartosz Nitka <niteria at gmail.com>
Date:   Thu Jun 9 08:50:32 2016 -0700

    Make the Ord Module independent of Unique order

    The `Ord Module` instance currently uses `Unique`s for comparison.
    We don't want to use the `Unique` order because it can introduce nondeterminism.
    This switches `Ord ModuleName` and `Ord UnitId` to use lexicographic ordering
    making `Ord Module` deterministic transitively.

    I've run `nofib` and it doesn't make a measurable difference.

    See also Note [ModuleEnv determinism and performance].

    Test Plan:
    ./validate
    run nofib: P112

    Reviewers: simonpj, simonmar, austin, bgamari

    Subscribers: thomie

    Differential Revision: https://phabricator.haskell.org/D2030

    GHC Trac Issues: #4012

commit 586d55815401c54f4687d053fb033e53865e0bf1
Author: Bartosz Nitka <niteria at gmail.com>
Date:   Mon Jun 13 07:35:32 2016 -0700

    Use UniqFM for SigOf

    Summary:
    The Ord instance for ModuleName is currently implemented in
    terms of Uniques causing potential determinism problems.
    I plan to change it to use the actual FastStrings and in
    preparation for that I'm switching to UniqFM where it's
    possible (you need *one* Unique per key, and you can't get
    the keys back), so that the performance doesn't suffer.

    Test Plan: ./validate

    Reviewers: simonmar, austin, ezyang, bgamari

    Reviewed By: bgamari

    Subscribers: thomie

    Differential Revision: https://phabricator.haskell.org/D2320

    GHC Trac Issues: #4012

commit 7de776cfe7825fca6a71fe6b3854c3c86bf9ca12
Author: Bartosz Nitka <niteria at gmail.com>
Date:   Mon Jun 13 04:53:43 2016 -0700

    Kill unused foldModuleEnv

    With the current implementation, it's nondeterministic
    because Ord Module is nondeterministic.

commit 5cee88d766723929f789ffcd2ef24d8b5ef62a16
Author: Tamar Christina <tamar at zhox.com>
Date:   Mon Jun 13 13:29:17 2016 +0200

    Add thin library support to Windows too

    Summary:
    Code already existed in the RTS to add thin library support for non-Windows
    operating systems. This adds it to Windows as well.

    ar thin libraries have the exact same format as normal archives except they
    have a different magic string and they don't copy the object files into the
    archive.

    Instead each header entry points to the location of the object file on disk.
    This is useful when a library is only created to satisfy a compile time dependency
    instead of to be distributed. This saves the time required for copying.

    Test Plan: ./validate and new test T11788

    Reviewers: austin, bgamari, simonmar, erikd

    Reviewed By: bgamari, simonmar

    Subscribers: thomie, #ghc_windows_task_force

    Differential Revision: https://phabricator.haskell.org/D2323

    GHC Trac Issues: #11788

commit 1dcb32ddba605bced2e0e0ce3f52b58e8ff33f5b
Author: Simon Peyton Jones <simonpj at microsoft.com>
Date:   Mon Jun 13 12:02:54 2016 +0100

    A second test for Trac #12055

    This one omits the extension, thereby making GHC 8.0 produce
    "GHC internal error".

commit 921ebc9f0854d033cbafd43d3b2c5ba679c27b3c
Author: Simon Peyton Jones <simonpj at microsoft.com>
Date:   Mon Jun 13 11:56:44 2016 +0100

    Test Trac #12055

commit e064f501d76c208ddab3c3be551ffe5167d7974f
Author: Simon Peyton Jones <simonpj at microsoft.com>
Date:   Sun Jun 12 22:32:31 2016 +0100

    Add to .gitignore

    This adds
      *.patch
      *.stackdump    (Windows)
      foo*           (simonpj uses foo* for junk files)

commit 8104f7c674d7ef2db0c25312f48763202dcef57f
Author: Simon Peyton Jones <simonpj at microsoft.com>
Date:   Sun Jun 12 22:01:49 2016 +0100

    Remove some traceTc calls

    During the kind-checking "knot" we have to be careful not
    to print too eagerly.

commit 599d912f0b85583e389661d85ed2f198e2621bb0
Author: Simon Peyton Jones <simonpj at microsoft.com>
Date:   Sun Jun 12 00:06:31 2016 +0100

    Beef up isPredTy

    isPredTy can be called on ill-kinded types, especially (of course) if
    there is a kind error.  We don't wnat it to crash, but it was, in
    piResultTy.

    This patch introduces piResultTy_maybe, and uses it in isPredTy.

    Ugh.  I dislike this code.  It's mainly used to know when we should
    print types with '=>', and we should probably have a better way to
    signal that.

commit 15fc52819c440f9e9b91ce92fcfda3c264cbe1c1
Author: Simon Peyton Jones <simonpj at microsoft.com>
Date:   Sun Jun 12 00:04:30 2016 +0100

    Fix the in-scope set for extendTvSubstWithClone

    We'd forgotten the variables free in the kind.

    Ditto extendCvSubstWithClone

commit 1f661281a23b6eab83a1144c43e464c0e2d2195a
Author: Simon Peyton Jones <simonpj at microsoft.com>
Date:   Sun Jun 12 00:00:53 2016 +0100

    Beef up mkNakedCastTy

    By spotting Refl coercions we can avoid building an awful
    lot of CastTys.  Simple and effective.

commit 35c9de7ca053eda472cb446c53bcd2007bfd8394
Author: Simon Peyton Jones <simonpj at microsoft.com>
Date:   Sat Jun 11 23:56:42 2016 +0100

    Move the constraint-kind validity check

    For type synonyms, we need to check that if the RHS has
    kind Constraint, then we have -XConstraintKinds.  For
    some reason this was done in checkValidType, but it makes
    more sense to do it in checkValidTyCon.

    I can't remember quite why I made this change; maybe it fixes
    a Trac ticket, but if so I forget which.  But it's a modest
    improvement anyway.

commit 7afb7adf45216701e4f645676ecc0668f64b424d
Author: Simon Peyton Jones <simonpj at microsoft.com>
Date:   Sat Jun 11 23:55:10 2016 +0100

    Get in-scope set right in top_instantiate

    ...thereby being able to replace substThetaUnchecked
    with substTheta

commit c28dde37f3f274a2a1207dd4e175ea79769f5ead
Author: Simon Peyton Jones <simonpj at microsoft.com>
Date:   Sat Jun 11 23:51:44 2016 +0100

    Tidy up zonkQuantifiedTyVar

    I managed to eliminate the strange zonkQuantifiedTyVarOrType,
    which is no longer used.

commit 15b9bf4ba4ab47e6809bf2b3b36ec16e502aea72
Author: Simon Peyton Jones <simonpj at microsoft.com>
Date:   Sat Jun 11 23:49:27 2016 +0100

    Improve typechecking of let-bindings

    This major commit was initially triggered by #11339, but it spiraled
    into a major review of the way in which type signatures for bindings
    are handled, especially partial type signatures.  On the way I fixed a
    number of other bugs, namely
       #12069
       #12033
       #11700
       #11339
       #11670

    The main change is that I completely reorganised the way in which type
    signatures in bindings are handled. The new story is in TcSigs
    Note [Overview of type signatures].  Some specific:

    * Changes in the data types for signatures in TcRnTypes:
      TcIdSigInfo and new TcIdSigInst

    * New module TcSigs deals with typechecking type signatures
      and pragmas. It contains code mostly moved from TcBinds,
      which is already too big

    * HsTypes: I swapped the nesting of HsWildCardBndrs
      and HsImplicitBndsrs, so that the wildcards are on the
      oustide not the insidde in a LHsSigWcType.  This is just
      a matter of convenient, nothing deep.

    There are a host of other changes as knock-on effects, and
    it all took FAR longer than I anticipated :-).  But it is
    a significant improvement, I think.

    Lots of error messages changed slightly, some just variants but
    some modest improvements.

    New tests

    * typecheck/should_compile
        * SigTyVars: a scoped-tyvar test
        * ExPat, ExPatFail: existential pattern bindings
        * T12069
        * T11700
        * T11339

    * partial-sigs/should_compile
        * T12033
        * T11339a
        * T11670

    One thing to check:

    * Small change to output from ghc-api/landmines.
      Need to check with Alan Zimmerman