[Git][ghc/ghc][wip/T21470] 19 commits: DmdAnal: Don't panic in addCaseBndrDmd (#22039)

Fri Sep 9 16:24:17 UTC 2022

Simon Peyton Jones pushed to branch wip/T21470 at Glasgow Haskell Compiler / GHC

Commits:
d2be80fd by Sebastian Graf at 2022-09-05T23:12:14-04:00
DmdAnal: Don't panic in addCaseBndrDmd (#22039)

Rather conservatively return Top.
See Note [Untyped demand on case-alternative binders].

I also factored `addCaseBndrDmd` into two separate functions `scrutSubDmd` and
`fieldBndrDmds`.

Fixes #22039.

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25f68ace by Ben Gamari at 2022-09-05T23:12:50-04:00
gitlab-ci: Ensure that ghc derivation is in scope

Previously the lint-ci job attempted to use cabal-install (specifically
`cabal update`) without a GHC in PATH. However, cabal-install-3.8
appears to want GHC, even for `cabal update`.

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f37b621f by sheaf at 2022-09-06T11:51:53+00:00
Update instances.rst, clarifying InstanceSigs

Fixes #22103

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d4f908f7 by Jan Hrček at 2022-09-06T15:36:58-04:00
Fix :add docs in user guide

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808bb793 by Cheng Shao at 2022-09-06T15:37:35-04:00
ci: remove unused build_make/test_make in ci script

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d0a2efb2 by Eric Lindblad at 2022-09-07T16:42:45-04:00
typo
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fac0098b by Eric Lindblad at 2022-09-07T16:42:45-04:00
typos

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a581186f by Eric Lindblad at 2022-09-07T16:42:45-04:00
whitespace

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04a738cb by Cheng Shao at 2022-09-07T16:43:22-04:00
CmmToAsm: remove unused ModLocation from NatM_State

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ee1cfaa9 by Krzysztof Gogolewski at 2022-09-07T16:43:58-04:00
Minor SDoc cleanup

Change calls to renderWithContext with showSDocOneLine; it's more
efficient and explanatory.

Remove polyPatSig (unused)

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7918265d by Krzysztof Gogolewski at 2022-09-07T16:43:58-04:00
Remove Outputable Char instance

Use 'text' instead of 'ppr'.
Using 'ppr' on the list "hello" rendered as "h,e,l,l,o".

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77209ab3 by Georgi Lyubenov at 2022-09-08T17:14:36+03:00
Export liftA2 from Prelude

Changes:
In order to be warning free and compatible, we hide Applicative(..)
from Prelude in a few places and instead import it directly from
Control.Applicative.
Please see the migration guide at
https://github.com/haskell/core-libraries-committee/blob/main/guides/export-lifta2-prelude.md
for more details.

This means that Applicative is now exported in its entirety from
Prelude.

Motivation:

This change is motivated by a few things:
* liftA2 is an often used function, even more so than (<*>) for some
  people.
* When implementing Applicative, the compiler will prompt you for either
  an implementation of (<*>) or of liftA2, but trying to use the latter
  ends with an error, without further imports. This could be confusing
  for newbies.
* For teaching, it is often times easier to introduce liftA2 first,
  as it is a natural generalisation of fmap.
* This change seems to have been unanimously and enthusiastically
  accepted by the CLC members, possibly indicating a lot of love for it.
* This change causes very limited breakage, see the linked issue below
  for an investigation on this.

See https://github.com/haskell/core-libraries-committee/issues/50
for the surrounding discussion and more details.

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442a94e8 by Georgi Lyubenov at 2022-09-08T17:14:36+03:00
Add changelog entry for liftA2 export from Prelude

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fb968680 by Georgi Lyubenov at 2022-09-08T17:14:36+03:00
Bump submodule containers to one with liftA2 warnings fixed

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f54ff818 by Georgi Lyubenov at 2022-09-08T17:14:36+03:00
Bump submodule Cabal to one with liftA2 warnings fixed

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a4b34808 by Georgi Lyubenov at 2022-09-08T17:14:36+03:00
Isolate some Applicative hidings to GHC.Prelude

By reexporting the entirety of Applicative from GHC.Prelude, we can save
ourselves some `hiding` and importing of `Applicative` in consumers of GHC.Prelude.
This also has the benefit of isolating this type of change to
GHC.Prelude, so that people in the future don't have to think about it.

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9c4ea90c by Cheng Shao at 2022-09-08T17:49:47-04:00
CmmToC: enable 64-bit CallishMachOp on 32-bit targets

Normally, the unregisterised builds avoid generating 64-bit
CallishMachOp in StgToCmm, so CmmToC doesn't support these. However,
there do exist cases where we'd like to invoke cmmToC for other cmm
inputs which may contain such CallishMachOps, and it's a rather low
effort to add support for these since they only require calling into
existing ghc-prim cbits.

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aac311af by Simon Peyton Jones at 2022-09-09T17:25:14+01:00
Make the specialiser handle polymorphic specialisation

Ticket #13873 unexpectedly showed that a SPECIALISE pragma made a
program run (a lot) slower, because less specialisation took place
overall. It turned out that the specialiser was missing opportunities
because of quantified type variables.

It was quite easy to fix. The story is given in
    Note [Specialising polymorphic dictionaries]

Two other minor fixes in the specialiser

* There is no benefit in specialising data constructor /wrappers/.
  (They can appear overloaded because they are given a dictionary
  to store in the constructor.)  Small guard in canSpecImport.

* There was a buglet in the UnspecArg case of specHeader, in the
  case where there is a dead binder. We need a LitRubbish filler
  for the specUnfolding stuff.  I expanded
  Note [Drop dead args from specialisations] to explain.

There is a 4% increase in compile time for T13056, because we generate
more specialised code.  This seems OK.

Metric Increase:
    T13056

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ff2734fa by Simon Peyton Jones at 2022-09-09T17:25:14+01:00
Fix binder-swap bug

This patch fixes #21229 / #21470 properly, by avoiding doing a
binder-swap on dictionary Ids.  This is pretty subtle, and explained
in Note [Care with binder-swap on dictionaries].

This allows us to restore a feature to the specialiser that we had
to revert: see Note [Specialising polymorphic dictionaries].

I als modularised things, using a new function scrutBinderSwap_maybe
in all the places where we are (effectively) doing a binder-swap,
notably

* Simplify.Iteration.addAltUnfoldings
* SpecConstr.extendCaseBndrs

In Simplify.Iteration.addAltUnfoldings I also eliminated a guard
    Many <- idMult case_bndr
because we concluded, in #22123, that it was doing no good.

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30 changed files:

- .gitlab-ci.yml
- .gitlab/ci.sh
- compiler/GHC/ByteCode/Instr.hs
- compiler/GHC/Cmm/Dominators.hs
- compiler/GHC/Cmm/Parser.y
- compiler/GHC/CmmToAsm.hs
- compiler/GHC/CmmToAsm/CFG.hs
- compiler/GHC/CmmToAsm/Monad.hs
- compiler/GHC/CmmToAsm/X86/CodeGen.hs
- compiler/GHC/CmmToC.hs
- compiler/GHC/CmmToLlvm/Base.hs
- compiler/GHC/CmmToLlvm/CodeGen.hs
- compiler/GHC/CmmToLlvm/Ppr.hs
- compiler/GHC/Core/Opt/DmdAnal.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/Specialise.hs
- compiler/GHC/Core/Rules.hs
- compiler/GHC/Core/Subst.hs
- compiler/GHC/Core/Type.hs
- compiler/GHC/Core/Unfold.hs
- compiler/GHC/CoreToStg/Prep.hs
- compiler/GHC/Driver/Pipeline.hs
- compiler/GHC/Driver/Pipeline/Execute.hs
- compiler/GHC/Hs/Binds.hs
- compiler/GHC/Hs/Doc.hs
- compiler/GHC/HsToCore/Foreign/C.hs

The diff was not included because it is too large.

View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/4ecab78ab29c619b91a31704f6b2f435fc9595ea...ff2734fa3eae10dc33ec77af632642a5ca9f6f3c

-- 
View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/4ecab78ab29c619b91a31704f6b2f435fc9595ea...ff2734fa3eae10dc33ec77af632642a5ca9f6f3c
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