[Git][ghc/ghc][wip/T22404] 4 commits: Update Match Datatype

Simon Peyton Jones (@simonpj) gitlab at gitlab.haskell.org
Fri Jul 28 21:54:52 UTC 2023



Simon Peyton Jones pushed to branch wip/T22404 at Glasgow Haskell Compiler / GHC


Commits:
a5319358 by David Knothe at 2023-07-28T13:13:10-04:00
Update Match Datatype

EquationInfo currently contains a list of the equation's patterns together with a CoreExpr that is to be evaluated after a successful match on this equation.
All the match-functions only operate on the first pattern of an equation - after successfully matching it, match is called recursively on the tail of the pattern list.
We can express this more clearly and make the code a little more elegant by updating the datatype of EquationInfo as follows:

data EquationInfo
    = EqnMatch { eqn_pat = Pat GhcTc, eqn_rest = EquationInfo }
    | EqnDone { eqn_rhs = MatchResult CoreExpr }

An EquationInfo now explicitly exposes its first pattern which most functions operate on, and exposes the equation that remains after processing the first pattern. An EqnDone signifies an empty equation where the CoreExpr can now be evaluated.

- - - - -
86ad1af9 by David Binder at 2023-07-28T13:13:53-04:00
Improve documentation for Data.Fixed

- - - - -
f8fa1d08 by Ben Gamari at 2023-07-28T13:14:31-04:00
ghc-prim: Use C11 atomics

Previously `ghc-prim`'s atomic wrappers used the legacy `__sync_*`
family of C builtins. Here we refactor these to rather use the
appropriate C11 atomic equivalents, allowing us to be more explicit
about the expected ordering semantics.

- - - - -
af04ebee by Simon Peyton Jones at 2023-07-28T22:54:13+01:00
Make the occurrence analyser smarter about join points

This MR addresses #22404.  There is a big Note

   Note [Occurrence analysis for join points]

that explains it all.  Significant changes

* New field occ_join_points in OccEnv

* The NonRec case of occAnalBind splits into two cases:
  one for existing join points (which does the special magic for
  Note [Occurrence analysis for join points], and one for other
  bindings.

* mkOneOcc adds in info from occ_join_points.

* All "bring into scope" activity is centralised in the
  new function `addInScope`.

* I made a local data type LocalOcc for use inside the occurrence analyser
  It is like OccInfo, but lacks IAmDead and IAmALoopBreaker, which in turn
  makes computationns over it simpler and more efficient.

* I found quite a bit of allocation in GHC.Core.Rules.getRules
  so I optimised it a bit.

More minor changes

* I found I was using (Maybe Arity) a lot, so I defined a new data
  type JoinPointHood and used it everwhere.  This touches a lot of
  non-occ-anal files, but it makes everything more perspicuous.

* Renamed data constructor WithUsageDetails to WUD, and
  WithTailUsageDetails to WTUD

This also fixes #21128, on the way.

--------- Compiler perf -----------
I spent quite a time on performance tuning, so even though it
does more than before, the occurrence analyser runs slightly faster
on average.  Here are the compile-time allocation changes over 0.5%

      CoOpt_Read(normal) ghc/alloc    766,025,520    754,561,992  -1.5%
CoOpt_Singletons(normal) ghc/alloc    759,436,840    762,925,512  +0.5%
     LargeRecord(normal) ghc/alloc  1,814,482,440  1,799,530,456  -0.8%
       PmSeriesT(normal) ghc/alloc     68,159,272     67,519,720  -0.9%
          T10858(normal) ghc/alloc    120,805,224    118,746,968  -1.7%
          T11374(normal) ghc/alloc    164,901,104    164,070,624  -0.5%
          T11545(normal) ghc/alloc     79,851,808     78,964,704  -1.1%
          T12150(optasm) ghc/alloc     73,903,664     71,237,544  -3.6% GOOD
          T12227(normal) ghc/alloc    333,663,200    331,625,864  -0.6%
          T12234(optasm) ghc/alloc     52,583,224     52,340,344  -0.5%
          T12425(optasm) ghc/alloc     81,943,216     81,566,720  -0.5%
          T13056(optasm) ghc/alloc    294,517,928    289,642,512  -1.7%
      T13253-spj(normal) ghc/alloc    118,271,264     59,859,040 -49.4% GOOD
          T15164(normal) ghc/alloc  1,102,630,352  1,091,841,296  -1.0%
          T15304(normal) ghc/alloc  1,196,084,000  1,166,733,000  -2.5%
          T15630(normal) ghc/alloc    148,729,632    147,261,064  -1.0%
          T15703(normal) ghc/alloc    379,366,664    377,600,008  -0.5%
          T16875(normal) ghc/alloc     32,907,120     32,670,976  -0.7%
          T17516(normal) ghc/alloc  1,658,001,888  1,627,863,848  -1.8%
          T17836(normal) ghc/alloc    395,329,400    393,080,248  -0.6%
          T18140(normal) ghc/alloc     71,968,824     73,243,040  +1.8%
          T18223(normal) ghc/alloc    456,852,568    453,059,088  -0.8%
          T18282(normal) ghc/alloc    129,105,576    131,397,064  +1.8%
          T18304(normal) ghc/alloc     71,311,712     70,722,720  -0.8%
         T18698a(normal) ghc/alloc    208,795,112    210,102,904  +0.6%
         T18698b(normal) ghc/alloc    230,320,736    232,697,976  +1.0%  BAD
          T19695(normal) ghc/alloc  1,483,648,128  1,504,702,976  +1.4%
          T20049(normal) ghc/alloc     85,612,024     85,114,376  -0.6%
         T21839c(normal) ghc/alloc    415,080,992    410,906,216  -1.0% GOOD
           T4801(normal) ghc/alloc    247,590,920    250,726,272  +1.3%
           T6048(optasm) ghc/alloc     95,699,416     95,080,680  -0.6%
            T783(normal) ghc/alloc    335,323,384    332,988,120  -0.7%
           T9233(normal) ghc/alloc    709,641,224    685,947,008  -3.3% GOOD
           T9630(normal) ghc/alloc    965,635,712    948,356,120  -1.8%
           T9675(optasm) ghc/alloc    444,604,152    428,987,216  -3.5% GOOD
           T9961(normal) ghc/alloc    303,064,592    308,798,800  +1.9%  BAD
           WWRec(normal) ghc/alloc    503,728,832    498,102,272  -1.1%

               geo. mean                                          -1.0%
               minimum                                           -49.4%
               maximum                                            +1.9%

In fact these figures seem to vary between platforms; generally worse
on i386 for some reason.  But the geom mean stay solidly negative, which
is good.  The "increase/decrease" list below covers all platforms.

The big win on T13253-spj comes because it has a big nest of join
points, each occurring twice in the next one.  The new occ-anal takes
only one iteration of the simplifier to do the inlining; the old one
took four.  Moreover, we get much smaller code with the new one:

  New: Result size of Tidy Core
    = {terms: 429, types: 84, coercions: 0, joins: 14/14}

  Old: Result size of Tidy Core
    = {terms: 2,437, types: 304, coercions: 0, joins: 10/10}

--------- Runtime perf -----------
No significant changes in nofib results, except a 1% reduction in
compiler allocation.

Metric Decrease:
    CoOpt_Read
    T13253-spj
    T9233
    T9630
    T9675
    T12150
    T21839c
    LargeRecord
    MultiComponentModulesRecomp

Metric Increase:
    T18140
    T9961
    T18282
    T18698a
    T18698b
    T19695

- - - - -


30 changed files:

- compiler/GHC/Core/Lint.hs
- compiler/GHC/Core/Opt/CSE.hs
- compiler/GHC/Core/Opt/DmdAnal.hs
- compiler/GHC/Core/Opt/Exitify.hs
- compiler/GHC/Core/Opt/FloatIn.hs
- compiler/GHC/Core/Opt/FloatOut.hs
- compiler/GHC/Core/Opt/OccurAnal.hs
- compiler/GHC/Core/Opt/SetLevels.hs
- compiler/GHC/Core/Opt/Simplify/Env.hs
- compiler/GHC/Core/Opt/Simplify/Iteration.hs
- compiler/GHC/Core/Opt/SpecConstr.hs
- compiler/GHC/Core/Opt/WorkWrap.hs
- compiler/GHC/Core/Ppr.hs
- compiler/GHC/Core/Rules.hs
- compiler/GHC/Core/SimpleOpt.hs
- compiler/GHC/Core/Tidy.hs
- compiler/GHC/Core/Unfold.hs
- compiler/GHC/Core/Unfold/Make.hs
- compiler/GHC/CoreToIface.hs
- compiler/GHC/CoreToStg/Prep.hs
- compiler/GHC/HsToCore/Expr.hs
- compiler/GHC/HsToCore/Match.hs
- compiler/GHC/HsToCore/Match/Constructor.hs
- compiler/GHC/HsToCore/Match/Literal.hs
- compiler/GHC/HsToCore/Monad.hs
- compiler/GHC/HsToCore/Utils.hs
- compiler/GHC/Iface/Syntax.hs
- compiler/GHC/IfaceToCore.hs
- compiler/GHC/Stg/Lint.hs
- compiler/GHC/Types/Basic.hs


The diff was not included because it is too large.


View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/68e92a9acb53114cb4498134ac2728a507bc96df...af04ebee389800f4350d22b7bb0e919604baf2eb

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View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/68e92a9acb53114cb4498134ac2728a507bc96df...af04ebee389800f4350d22b7bb0e919604baf2eb
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