[Git][ghc/ghc][wip/simplifier-tweaks] 19 commits: configure: Use LDFLAGS when trying linkers

Simon Peyton Jones (@simonpj) gitlab at gitlab.haskell.org
Fri Mar 29 10:41:14 UTC 2024



Simon Peyton Jones pushed to branch wip/simplifier-tweaks at Glasgow Haskell Compiler / GHC


Commits:
32a8103f by Rodrigo Mesquita at 2024-03-26T21:16:12-04:00
configure: Use LDFLAGS when trying linkers

A user may configure `LDFLAGS` but not `LD`. When choosing a linker, we
will prefer `ldd`, then `ld.gold`, then `ld.bfd` -- however, we have to
check for a working linker. If either of these fail, we try the next in
line.

However, we were not considering the `$LDFLAGS` when checking if these
linkers worked. So we would pick a linker that does not support the
current $LDFLAGS and fail further down the line when we used that linker
with those flags.

Fixes #24565, where `LDFLAGS=-Wl,-z,pack-relative-relocs` is not
supported by `ld.gold` but that was being picked still.

- - - - -
bf65a7c3 by Rodrigo Mesquita at 2024-03-26T21:16:48-04:00
bindist: Clean xattrs of bin and lib at configure time

For issue #21506, we started cleaning the extended attributes of
binaries and libraries from the bindist *after* they were installed to
workaround notarisation (#17418), as part of `make install`.

However, the `ghc-toolchain` binary that is now shipped with the bindist
must be run at `./configure` time. Since we only cleaned the xattributes
of the binaries and libs after they were installed, in some situations
users would be unable to run `ghc-toolchain` from the bindist, failing
at configure time (#24554).

In this commit we move the xattr cleaning logic to the configure script.

Fixes #24554

- - - - -
cfeb70d3 by Rodrigo Mesquita at 2024-03-26T21:17:24-04:00
Revert "NCG: Fix a bug in jump shortcutting."

This reverts commit 5bd8ed53dcefe10b72acb5729789e19ceb22df66.

Fixes #24586

- - - - -
13223f6d by Serge S. Gulin at 2024-03-27T07:28:51-04:00
JS: `h$rts_isProfiled` is removed from `profiling` and left its version at
`rts/js/config.js`

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0acfe391 by Alan Zimmerman at 2024-03-27T07:29:27-04:00
EPA: Do not extend declaration range for trailine zero len semi

The lexer inserts virtual semicolons having zero width.
Do not use them to extend the list span of items in a list.

- - - - -
cd0fb82f by Alan Zimmerman at 2024-03-27T19:33:08+00:00
EPA: Fix FamDecl range

The span was incorrect if opt_datafam_kind_sig was empty

- - - - -
f8f384a8 by Ben Gamari at 2024-03-29T01:23:03-04:00
Fix type of _get_osfhandle foreign import

Fixes #24601.

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e42c7e48 by Simon Peyton Jones at 2024-03-29T10:23:19+00:00
Several improvements to the handling of coercions

* Make `mkSymCo` and `mkInstCo` smarter
  Fixes #23642

* Fix return role of `SelCo` in the coercion optimiser.
  Fixes #23617

* Make the coercion optimiser `opt_trans_rule` work better for newtypes
  Fixes #23619

- - - - -
ac81968c by Simon Peyton Jones at 2024-03-29T10:23:19+00:00
FloatOut: improve floating for join point

See the new Note [Floating join point bindings].

* Completely get rid of the complicated join_ceiling nonsense, which
  I have never understood.

* Do not float join points at all, except perhaps to top level.

* Some refactoring around wantToFloat, to treat Rec and NonRec more
  uniformly

- - - - -
94c5594b by Simon Peyton Jones at 2024-03-29T10:23:19+00:00
Improve eta-expansion through call stacks

See Note [Eta expanding through CallStacks] in GHC.Core.Opt.Arity

This is a one-line change, that fixes an inconsistency
-               || isCallStackPredTy ty
+               || isCallStackPredTy ty || isCallStackTy ty

- - - - -
75d58615 by Simon Peyton Jones at 2024-03-29T10:23:19+00:00
Spelling, layout, pretty-printing only

- - - - -
8abb62e6 by Simon Peyton Jones at 2024-03-29T10:23:19+00:00
Improve exprIsConApp_maybe a little

Eliminate a redundant case at birth.  This sometimes reduces
Simplifier iterations.

See Note [Case elim in exprIsConApp_maybe].

- - - - -
9b1e466f by Simon Peyton Jones at 2024-03-29T10:23:19+00:00
Inline GHC.HsToCore.Pmc.Solver.Types.trvVarInfo

When exploring compile-time regressions after meddling with the Simplifier, I
discovered that GHC.HsToCore.Pmc.Solver.Types.trvVarInfo was very delicately
balanced.  It's a small, heavily used, overloaded function and it's important
that it inlines. By a fluke it was before, but at various times in my journey it
stopped doing so.  So I just added an INLINE pragma to it; no sense in depending
on a delicately-balanced fluke.

- - - - -
c50b2ac1 by Simon Peyton Jones at 2024-03-29T10:23:20+00:00
Slight improvement in WorkWrap

Ensure that WorkWrap preserves lambda binders, in case of join points.  Sadly I
have forgotten why I made this change (it was while I was doing a lot of
meddling in the Simplifier, but
  * it does no harm,
  * it is slightly more efficient, and
  * presumably it made something better!

Anyway I have kept it in a separate commit.

- - - - -
b170fb8b by Simon Peyton Jones at 2024-03-29T10:23:20+00:00
Use named record fields for the CastIt { ... } data constructor

This is a pure refactor

- - - - -
196129b0 by Simon Peyton Jones at 2024-03-29T10:23:20+00:00
Remove a long-commented-out line

Pure refactoring

- - - - -
21c60ae9 by Simon Peyton Jones at 2024-03-29T10:40:31+00:00
Simplifier improvements

This MR started as: allow the simplifer to do more in one pass,
arising from places I could see the simplifier taking two iterations
where one would do.  But it turned into a larger project, because
these changes unexpectedly made inlining blow up, especially join
points in deeply-nested cases.

The main changes are below.  There are also many new or rewritten Notes.

Avoiding simplifying repeatedly
~~~~~~~~~~~~~~~
See Note [Avoiding simplifying repeatedly]

* The SimplEnv now has a seInlineDepth field, which says how deep
  in unfoldings we are.  See Note [Inline depth] in Simplify.Env.
  Currently used only for the next point: avoiding repeatedly
  simplifying coercions.

* Avoid repeatedly simplifying coercions.
  see Note [Avoid re-simplifying coercions] in Simplify.Iteration
  As you'll see from the Note, this makes use of the seInlineDepth.

* Allow Simplify.Iteration.simplAuxBind to inline used-once things.
  This is another part of Note [Post-inline for single-use things], and
  is really good for reducing simplifier iterations in situations like
      case K e of { K x -> blah }
  wher x is used once in blah.

* Make GHC.Core.SimpleOpt.exprIsConApp_maybe do some simple case
  elimination.  Note [Case elim in exprIsConApp_maybe]

* Improve the case-merge transformation:
  - Move the main code to `GHC.Core.Utils.mergeCaseAlts`, to join `filterAlts`
    and friends.  See Note [Merge Nested Cases] in GHC.Core.Utils.
  - Add a new case for `tagToEnum#`; see wrinkle (MC3).
  - Add a new case to look through join points: see wrinkle (MC4)

postInlineUnconditionally
~~~~~~~~~~~~~~~~~~~~~~~~~
* Allow Simplify.Utils.postInlineUnconditionally to inline variables
  that are used exactly once. See Note [Post-inline for single-use things].

* Do not postInlineUnconditionally join point, ever.
  Doing so does not reduce allocation, which is the main point,
  and with join points that are used a lot it can bloat code.
  See point (1) of Note [Duplicating join points] in
  GHC.Core.Opt.Simplify.Iteration.

* Do not postInlineUnconditionally a strict (demanded) binding.
  It will not allocate a thunk (it'll turn into a case instead)
  so again the main point of inlining it doesn't hold.  Better
  to check per-call-site.

* Improve occurrence analyis for bottoming function calls, to help
  postInlineUnconditionally.  See Note [Bottoming function calls]
  in GHC.Core.Opt.OccurAnal

Inlining generally
~~~~~~~~~~~~~~~~~~
* In GHC.Core.Opt.Simplify.Utils.interestingCallContext,
  use RhsCtxt NonRecursive (not BoringCtxt) for a plain-seq case.
  See Note [Seq is boring]  Also, wrinkle (SB1), inline in that
  `seq` context only for INLINE functions (UnfWhen guidance).

* In GHC.Core.Opt.Simplify.Utils.interestingArg,
  - return ValueArg for OtherCon [c1,c2, ...], but
  - return NonTrivArg for OtherCon []
  This makes a function a little less likely to inline if all we
  know is that the argument is evaluated, but nothing else.

* isConLikeUnfolding is no longer true for OtherCon {}.
  This propagates to exprIsConLike.  Con-like-ness has /positive/
  information.

Join points
~~~~~~~~~~~
* Be very careful about inlining join points.
  See these two long Notes
    Note [Duplicating join points] in GHC.Core.Opt.Simplify.Iteration
    Note [Inlining join points] in GHC.Core.Opt.Simplify.Inline

* When making join points, don't do so if the join point is so small
  it will immediately be inlined; check uncondInlineJoin.

* In GHC.Core.Opt.Simplify.Inline.tryUnfolding, improve the inlining
  heuristics for join points. In general we /do not/ want to inline
  join points /even if they are small/.  See Note [Duplicating join points]
  GHC.Core.Opt.Simplify.Iteration.

  But sometimes we do: see Note [Inlining join points] in
  GHC.Core.Opt.Simplify.Inline; and the new `isBetterUnfoldingThan` function.

* Do not add an unfolding to a join point at birth.  This is a tricky one
  and has a long Note [Do not add unfoldings to join points at birth]
  It shows up in two places
  - In `mkDupableAlt` do not add an inlining
  - (trickier) In `simplLetUnfolding` don't add an unfolding for a
    fresh join point
  I am not fully satisifed with this, but it works and is well documented.

* In GHC.Core.Unfold.sizeExpr, make jumps small, so that we don't penalise
  having a non-inlined join point.

Performance changes
~~~~~~~~~~~~~~~~~~~
* Binary sizes fall by around 2.6%, according to nofib.

* Compile times improve slightly. Here are the figures over 1%.

  I investiate the biggest differnce in T18304. It's a very small module, just
  a few hundred nodes. The large percentage difffence is due to a single
  function that didn't quite inline before, and does now, making code size a
  bit bigger.  I decided gains outweighed the losses.

    Metrics: compile_time/bytes allocated
    ---------------------------------------------------------------------------------------
               CoOpt_Singletons(normal)   -9.0% GOOD
                    LargeRecord(normal)  -23.5% GOOD
    MultiComponentModulesRecomp(normal)   +1.1%
    MultiLayerModulesTH_OneShot(normal)   +4.1%  BAD
                      PmSeriesS(normal)   -4.2%
                      PmSeriesV(normal)   -1.9%
                         T11195(normal)   -1.1%
                         T12227(normal)  -20.5% GOOD
                         T12545(normal)   -3.2%
                         T12707(normal)   -2.2% GOOD
                         T13253(normal)   -1.3%
                     T13253-spj(normal)   +7.8%  BAD
                         T13379(normal)   +0.8%
                         T13386(normal)   -3.1% GOOD
                         T14766(normal)   -2.6% GOOD
                         T15164(normal)   -1.2%
                         T15304(normal)   +1.2%
                         T15630(normal)   -8.4%
                         T15703(normal)  -14.7% GOOD
                         T16577(normal)   -2.3% GOOD
                         T17516(normal)  -34.8% GOOD
                         T18223(normal)  -17.2% GOOD
                         T18282(normal)   -5.2% GOOD
                         T18304(normal)  +10.6%  BAD
                         T18923(normal)   -3.2% GOOD
                          T1969(normal)   +1.0%
                         T19695(normal)   -1.6%
                        T21839c(normal)   -4.1% GOOD
                          T3064(normal)   -1.5%
                          T3294(normal)   +1.2%  BAD
                          T4801(normal)   +1.1%
                          T5030(normal)  -15.3% GOOD
                       T5321Fun(normal)   -1.5%
                          T6048(optasm)  -17.1% GOOD
                           T783(normal)   -1.3%
                          T8095(normal)   -6.0% GOOD
                          T9630(normal)   -4.8% GOOD
                          T9961(normal)   +1.9%  BAD
                          WWRec(normal)   -1.3%
            info_table_map_perf(normal)   -1.7%
                     parsing001(normal)   +1.4%

                              geo. mean   -1.9%
                              minimum    -34.8%
                              maximum    +10.6%

* Runtimes generally improve. In the testsuite perf/should_run gives:
   Metrics: runtime/bytes allocated
   ------------------------------------------
             Conversions(normal)   -0.3%
                 T13536a(optasm)  -41.7% GOOD
                   T4830(normal)   -0.1%
           haddock.Cabal(normal)   -0.1%
            haddock.base(normal)   -0.1%
        haddock.compiler(normal)   -0.1%

                       geo. mean   -0.8%
                       minimum    -41.7%
                       maximum     +0.0%

* For runtime, nofib is a better test.  The news is almost all good:

Metric Decrease:
    CoOpt_Singletons
    LargeRecord
    T12227
    T12707
    T13386
    T13536a
    T14766
    T15703
    T16577
    T17516
    T18223
    T18282
    T18923
    T21839c
    T5030
    T6048
    T8095
    T9630
Metric Increase:
    MultiLayerModulesTH_OneShot
    T13253-spj
    T18304
    T3294
    T9961

- - - - -
32c1cb18 by Simon Peyton Jones at 2024-03-29T10:41:00+00:00
Testsuite message changes from simplifier improvements

- - - - -
c7afc943 by Simon Peyton Jones at 2024-03-29T10:41:00+00:00
Account for bottoming functions in OccurAnal

This fixes #24582, a small but long-standing bug

- - - - -


22 changed files:

- compiler/GHC/CmmToAsm/AArch64/Instr.hs
- compiler/GHC/CmmToAsm/BlockLayout.hs
- compiler/GHC/CmmToAsm/Instr.hs
- compiler/GHC/CmmToAsm/PPC/Instr.hs
- compiler/GHC/CmmToAsm/Reg/Graph/SpillClean.hs
- compiler/GHC/CmmToAsm/Reg/Linear/JoinToTargets.hs
- compiler/GHC/CmmToAsm/Reg/Liveness.hs
- compiler/GHC/CmmToAsm/X86/Instr.hs
- compiler/GHC/Core.hs
- compiler/GHC/Core/Coercion.hs
- compiler/GHC/Core/Coercion/Opt.hs
- compiler/GHC/Core/Opt/Arity.hs
- compiler/GHC/Core/Opt/FloatOut.hs
- compiler/GHC/Core/Opt/Monad.hs
- compiler/GHC/Core/Opt/OccurAnal.hs
- compiler/GHC/Core/Opt/Pipeline.hs
- compiler/GHC/Core/Opt/SetLevels.hs
- compiler/GHC/Core/Opt/Simplify.hs
- compiler/GHC/Core/Opt/Simplify/Env.hs
- compiler/GHC/Core/Opt/Simplify/Inline.hs
- compiler/GHC/Core/Opt/Simplify/Iteration.hs
- compiler/GHC/Core/Opt/Simplify/Monad.hs


The diff was not included because it is too large.


View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/1fbbc520911b02b6a82e9688527595dc524cf860...c7afc94316273e748b5f7a83b71c3b66a55f09ec

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