[Git][ghc/ghc][wip/T22194-flags] 23 commits: Make exprIsConApp_maybe a bit cleverer

Simon Peyton Jones (@simonpj) gitlab at gitlab.haskell.org
Thu Mar 30 23:34:09 UTC 2023



Simon Peyton Jones pushed to branch wip/T22194-flags at Glasgow Haskell Compiler / GHC


Commits:
c1f755c4 by Simon Peyton Jones at 2023-03-27T22:09:41+01:00
Make exprIsConApp_maybe a bit cleverer

Addresses #23159.

See Note Note [Exploit occ-info in exprIsConApp_maybe]
in GHC.Core.SimpleOpt.

Compile times go down very slightly, but always go down,
never up.  Good!

Metrics: compile_time/bytes allocated
------------------------------------------------
 CoOpt_Singletons(normal)   -1.8%
           T15703(normal)   -1.2% GOOD

                geo. mean   -0.1%
                minimum     -1.8%
                maximum     +0.0%

Metric Decrease:
    CoOpt_Singletons
    T15703

- - - - -
76bb4c58 by Ryan Scott at 2023-03-28T08:12:08-04:00
Add COMPLETE pragmas to TypeRep, SSymbol, SChar, and SNat

This implements
[CLC proposal #149](https://github.com/haskell/core-libraries-committee/issues/149).

- - - - -
3f374399 by sheaf at 2023-03-29T13:57:33+02:00
Handle records in the renamer

This patch moves the field-based logic for disambiguating record updates
to the renamer. The type-directed logic, scheduled for removal, remains
in the typechecker.

To do this properly (and fix the myriad of bugs surrounding the treatment
of duplicate record fields), we took the following main steps:

  1. Create GREInfo, a renamer-level equivalent to TyThing which stores
     information pertinent to the renamer.
     This allows us to uniformly treat imported and local Names in the
     renamer, as described in Note [GREInfo].

  2. Remove GreName. Instead of a GlobalRdrElt storing GreNames, which
     distinguished between normal names and field names, we now store
     simple Names in GlobalRdrElt, along with the new GREInfo information
     which allows us to recover the FieldLabel for record fields.

  3. Add namespacing for record fields, within the OccNames themselves.
     This allows us to remove the mangling of duplicate field selectors.

     This change ensures we don't print mangled names to the user in
     error messages, and allows us to handle duplicate record fields
     in Template Haskell.

  4. Move record disambiguation to the renamer, and operate on the
     level of data constructors instead, to handle #21443.

     The error message text for ambiguous record updates has also been
     changed to reflect that type-directed disambiguation is on the way
     out.

(3) means that OccEnv is now a bit more complex: we first key on the
textual name, which gives an inner map keyed on NameSpace:

  OccEnv a ~ FastStringEnv (UniqFM NameSpace a)

Note that this change, along with (2), both increase the memory residency
of GlobalRdrEnv = OccEnv [GlobalRdrElt], which causes a few tests to
regress somewhat in compile-time allocation.

Even though (3) simplified a lot of code (in particular the treatment of
field selectors within Template Haskell and in error messages), it came
with one important wrinkle: in the situation of

  -- M.hs-boot
  module M where { data A; foo :: A -> Int }
  -- M.hs
  module M where { data A = MkA { foo :: Int } }

we have that M.hs-boot exports a variable foo, which is supposed to match
with the record field foo that M exports. To solve this issue, we add a
new impedance-matching binding to M

  foo{var} = foo{fld}

This mimics the logic that existed already for impedance-binding DFunIds,
but getting it right was a bit tricky.
See Note [Record field impedance matching] in GHC.Tc.Module.

We also needed to be careful to avoid introducing space leaks in GHCi.
So we dehydrate the GlobalRdrEnv before storing it anywhere, e.g. in
ModIface. This means stubbing out all the GREInfo fields, with the
function forceGlobalRdrEnv.
When we read it back in, we rehydrate with rehydrateGlobalRdrEnv.
This robustly avoids any space leaks caused by retaining old type
environments.

Fixes #13352 #14848 #17381 #17551 #19664 #21443 #21444 #21720 #21898 #21946 #21959 #22125 #22160 #23010 #23062 #23063

Updates haddock submodule

-------------------------
Metric Increase:
    MultiComponentModules
    MultiLayerModules
    MultiLayerModulesDefsGhci
    MultiLayerModulesNoCode
    T13701
    T14697
    hard_hole_fits
-------------------------

- - - - -
4f1940f0 by sheaf at 2023-03-29T13:57:33+02:00
Avoid repeatedly shadowing in shadowNames

This commit refactors GHC.Type.Name.Reader.shadowNames to first
accumulate all the shadowing arising from the introduction of a new
set of GREs, and then applies all the shadowing to the old GlobalRdrEnv
in one go.

- - - - -
d246049c by sheaf at 2023-03-29T13:57:34+02:00
igre_prompt_env: discard "only-qualified" names

We were unnecessarily carrying around names only available qualified
in igre_prompt_env, violating the icReaderEnv invariant.
We now get rid of these, as they aren't needed for the shadowing
computation that igre_prompt_env exists for.

Fixes #23177

-------------------------
Metric Decrease:
    T14052
    T14052Type
-------------------------

- - - - -
41a572f6 by Matthew Pickering at 2023-03-29T16:17:21-04:00
hadrian: Fix path to HpcParser.y

The source for this project has been moved into a src/ folder so we also
need to update this path.

Fixes #23187

- - - - -
b159e0e9 by doyougnu at 2023-03-30T01:40:08-04:00
js: split JMacro into JS eDSL and JS syntax

This commit:

Splits JExpr and JStat into two nearly identical DSLs:
- GHC.JS.Syntax is the JMacro based DSL without unsaturation, i.e., a
value cannot be unsaturated, or, a value of this DSL is a witness that a
value of GHC.JS.Unsat has been saturated
- GHC.JS.Unsat is the JMacro DSL from GHCJS with Unsaturation.

Then all binary and outputable instances are changed to use
GHC.JS.Syntax.

This moves us closer to closing out #22736 and #22352. See #22736 for
roadmap.

-------------------------
Metric Increase:
    CoOpt_Read
    LargeRecord
    ManyAlternatives
    PmSeriesS
    PmSeriesT
    PmSeriesV
    T10421
    T10858
    T11195
    T11374
    T11822
    T12227
    T12707
    T13035
    T13253
    T13253-spj
    T13379
    T14683
    T15164
    T15703
    T16577
    T17096
    T17516
    T17836
    T18140
    T18282
    T18304
    T18478
    T18698a
    T18698b
    T18923
    T1969
    T19695
    T20049
    T21839c
    T3064
    T4801
    T5321FD
    T5321Fun
    T5631
    T5642
    T783
    T9198
    T9233
    T9630
    TcPlugin_RewritePerf
    WWRec
-------------------------

- - - - -
f4f1f14f by Sylvain Henry at 2023-03-30T01:40:49-04:00
ghc-heap: remove wrong Addr# coercion (#23181)

Conversion from Addr# to I# isn't correct with the JS backend.

Also used the opportunity to reenable 64-bit Word/Int tests

- - - - -
a5360490 by Ben Gamari at 2023-03-30T01:41:25-04:00
testsuite: Fix racing prints in T21465

As noted in #23155, we previously failed to add flushes necessary to
ensure predictable output.

Fixes #23155.

- - - - -
98b5cf67 by Matthew Pickering at 2023-03-30T09:58:40+01:00
Revert "ghc-heap: remove wrong Addr# coercion (#23181)"

This reverts commit f4f1f14f8009c3c120b8b963ec130cbbc774ec02.

This fails to build with GHC-9.2 as a boot compiler.

See #23195 for tracking this issue.

- - - - -
61a2dfaa by Bodigrim at 2023-03-30T14:35:57-04:00
Add {-# WARNING #-} to Data.List.{head,tail}

- - - - -
8f15c47c by Bodigrim at 2023-03-30T14:35:57-04:00
Fixes to accomodate Data.List.{head,tail} with {-# WARNING #-}

- - - - -
7c7dbade by Bodigrim at 2023-03-30T14:35:57-04:00
Bump submodules

- - - - -
d2d8251b by Bodigrim at 2023-03-30T14:35:57-04:00
Fix tests

- - - - -
3d38dcb6 by sheaf at 2023-03-30T14:35:57-04:00
Proxies for head and tail: review suggestions
- - - - -
930edcfd by sheaf at 2023-03-30T14:36:33-04:00
docs: move RecordUpd changelog entry to 9.8

This was accidentally included in the 9.6 changelog
instead of the 9.6 changelog.
- - - - -
6f885e65 by sheaf at 2023-03-30T14:37:09-04:00
Add LANGUAGE GADTs to GHC.Rename.Env

We need to enable this extension for the file to compile with ghc 9.2,
as we are pattern matching on a GADT and this required the GADT extension
to be enabled until 9.4.
- - - - -
51af5d58 by Simon Peyton Jones at 2023-03-30T23:16:25+01:00
Major refactor in the handling of equality constraints

This MR substantially refactors the way in which the constraint
solver deals with equality constraints.  The big thing is:

* Intead of a pipeline in which we /first/ canonicalise and /then/
  interact (the latter including performing unification) the two steps
  are more closely integreated into one.  That avoids the current
  rather indirect communication between the two steps.

The proximate cause for this refactoring is fixing #22194, which involve
solving   [W] alpha[2] ~ Maybe (F beta[4])
by doing this:
          alpha[2] := Maybe delta[2]
          [W] delta[2] ~ F beta[4]
That is, we don't promote beta[4]!  This is very like introducing a cycle
breaker, and was very awkward to do before, but now it is all nice.
See GHC.Tc.Utils.Unify Note [Promotion and level-checking] and
Note [Family applications in canonical constraints].

The big change is this:

* Several canonicalisation checks (occurs-check, cycle-breaking,
  checking for concreteness) are combined into one new function:
     GHC.Tc.Utils.Unify.checkTyEqRhs

  This function is controlled by `TyEqFlags`, which says what to do
  for foralls, type families etc.

* `canEqCanLHSFinish` now sees if unification is possible, and if so,
  actually does it: see `canEqCanLHSFinish_try_unification`.

There are loads of smaller changes:

* The on-the-fly unifier `GHC.Tc.Utils.Unify.unifyType` has a
  cheap-and-cheerful version of `checkTyEqRhs`, called
  `simpleUnifyCheck`.  If `simpleUnifyCheck` succeeds, it can unify,
  otherwise it defers by emitting a constraint. This is simpler than
  before.

* I simplified the swapping code in `GHC.Tc.Solver.Equality.canEqCanLHS`.
  Especially the nasty stuff involving `swap_for_occurs` and
  `canEqTyVarFunEq`.  Much nicer now.  See
      Note [Orienting TyVarLHS/TyFamLHS]
      Note [Orienting TyFamLHS/TyFamLHS]

* Added `cteSkolemOccurs`, `cteConcrete`, and `cteCoercionHole` to the
  problems that can be discovered by `checkTyEqRhs`.

Yet smaller:

* Added a `synIsConcrete` flag to `SynonymTyCon` (alongside `synIsFamFree`)
  to reduce the need for synonym expansion when checking concreteness.
  Use it in `isConcreteType`.

* Renamed `isConcrete` to `isConcreteType`

* Defined `GHC.Core.TyCo.FVs.isInjectiveInType` as a more efficient
  way to find if a particular type variable is used injectively than
  finding all the injective variables.  It is called in
  `GHC.Tc.Utils.Unify.definitely_poly`, which in turn is used quite a
  lot.

* Moved `rewriterView` to `GHC.Core.Type`, so we can use it from the
  constraint solver.

Fixes #22194

Compile times decrease by an average of 0.1%; but there is a 7.4%
drop in compiler allocation on T15703.

Metric Decrease:
    T15703

- - - - -
6050255e by Simon Peyton Jones at 2023-03-30T23:16:25+01:00
Never quantify over equalities in an inferred type

An experiment.. trying to do the Right Thing!

Examples
* #22194
* `histogram_` in Statistics.Sample.Histogram in `statistics`

- - - - -
84a85294 by Simon Peyton Jones at 2023-03-30T23:16:26+01:00
Typos and comments

- - - - -
c2bbef2a by Simon Peyton Jones at 2023-03-30T23:16:26+01:00
Add a type signature in isAtomicHsExpr

- - - - -
b1b7d9b6 by Simon Peyton Jones at 2023-03-30T23:16:26+01:00
Allow quantification over equalities at top level (only)

- - - - -
35bc5c05 by Simon Peyton Jones at 2023-03-30T23:16:26+01:00
Make pickQuantifiablePred more generous

- - - - -


30 changed files:

- compiler/GHC.hs
- compiler/GHC/Builtin/Names.hs
- compiler/GHC/Builtin/Names/TH.hs
- compiler/GHC/Builtin/Uniques.hs
- compiler/GHC/Builtin/Uniques.hs-boot
- compiler/GHC/Builtin/Utils.hs
- compiler/GHC/ByteCode/Linker.hs
- compiler/GHC/Core/ConLike.hs
- compiler/GHC/Core/DataCon.hs
- compiler/GHC/Core/LateCC.hs
- compiler/GHC/Core/Map/Type.hs
- compiler/GHC/Core/Opt/Simplify/Iteration.hs
- compiler/GHC/Core/SimpleOpt.hs
- compiler/GHC/Core/TyCo/FVs.hs
- compiler/GHC/Core/TyCo/Rep.hs
- compiler/GHC/Core/TyCon.hs
- compiler/GHC/Core/TyCon/Env.hs
- compiler/GHC/Core/Type.hs
- compiler/GHC/Core/Type.hs-boot
- compiler/GHC/CoreToIface.hs
- compiler/GHC/Data/Bag.hs
- compiler/GHC/Data/FastString/Env.hs
- compiler/GHC/Data/Maybe.hs
- compiler/GHC/Driver/Env.hs
- compiler/GHC/Hs/Decls.hs
- compiler/GHC/Hs/Expr.hs
- compiler/GHC/Hs/ImpExp.hs
- compiler/GHC/Hs/Instances.hs
- compiler/GHC/Hs/Pat.hs
- compiler/GHC/Hs/Type.hs


The diff was not included because it is too large.


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