GitLab

Reviewers: austin, bgamari, goldfire

Reviewed By: bgamari

Subscribers: rwbarton, thomie

GHC Trac Issues: #13782

Differential Revision: https://phabricator.haskell.org/D3641

Reviewers: bgamari, austin, simonmar

Reviewed By: bgamari

Subscribers: mpickering, rwbarton, thomie

Differential Revision: https://phabricator.haskell.org/D3651

This tries to be more precise when generating reloads of local
registers in proc points. Previously we'd reload all local registers
that were live. But we used liveness information that assumed local
registers survive native calls. For the purpose of reloading registers
this is an overapproximation and might lead to generating huge amounts
of unnecessary reloads (in case there's another proc point before the
register is used).

This change takes the approach of moving the generation of reloads to
a second pass over the Cmm, which allows to recompute the liveness and
can use the knowledge that local registers do *not* survive calls.
This leads to generating only useful reloads. For an extreme example
where this helps a lot please see T3294. This should also fix #7198

Finally, this re-introduces the code to do Cmm rewriting using in
`Dataflow` module (with the difference that we know operate on a whole
block at a time).
Signed-off-by: Michal Terepeta <michal.terepeta@gmail.com>

Reviewers: austin, bgamari, simonmar

Reviewed By: simonmar

Subscribers: kavon, rwbarton, thomie

GHC Trac Issues: #7198

Differential Revision: https://phabricator.haskell.org/D3586

Reviewers: austin, bgamari

Reviewed By: bgamari

Subscribers: rwbarton, thomie

GHC Trac Issues: #13821

Differential Revision: https://phabricator.haskell.org/D3642

This is not the most precise test, unfortunately, but it does
demonstrate a modest improvement in compiler residency as a
result of the specializer don't-loop patch. A rather less
realistic variation on this has somewhat more dramatic effects.

Reviewers: austin, bgamari

Reviewed By: bgamari

Subscribers: rwbarton, thomie

Differential Revision: https://phabricator.haskell.org/D3656

Reviewers: austin

Subscribers: rwbarton, thomie

GHC Trac Issues: #13822

Differential Revision: https://phabricator.haskell.org/D3655

Summary:
This amounts to using `exactTyCoVarsOfType` instead of
`tyCoVarsOfType` in the right place. I also fixed a similar issue for
`-XDatatypeContexts` while I was in town (but couldn't be bothered to add a
test for it).

Test Plan: make test TEST=T13813

Reviewers: austin, bgamari, simonpj

Reviewed By: simonpj

Subscribers: simonpj, rwbarton, thomie

GHC Trac Issues: #13813

Differential Revision: https://phabricator.haskell.org/D3635

The IdBindingInfo field of ATcId serves two purposes

- to control generalisation when we have -XMonoLocalBinds
- to check for floatability when dealing with (static e)

These are related, but not the same, and they'd becomme confused.
Trac #13804 showed this up via an example like this:

  f periph = let sr :: forall a. [a] -> [a]
                 sr = if periph then reverse else id

                 sr2 = sr
                 -- The question: is sr2 generalised?
                 -- It should be, because sr has a type sig
                 -- even though it has periph free
             in
             (sr2 [True], sr2 "c")

Here sr2 should be generalised, despite the free var 'periph'
in 'sr' because 'sr' has a closed type signature.

I documented all this very carefully this time, in TcRnTypes:
  Note [Meaning of IdBindingInfo]
  Note [Bindings with closed types: ClosedTypeId]

Test Plan: validate

Reviewers: austin, hvr, erikd, simonmar

Subscribers: rwbarton, thomie

GHC Trac Issues: #13832

Differential Revision: https://phabricator.haskell.org/D3652

Previously -w combined with -Wunrecognised-warning-flags would not
report unrecognized flags.

Reviewers: austin, bgamari, dfeuer

Reviewed By: bgamari

Subscribers: dfeuer, rwbarton, thomie

GHC Trac Issues: #12056

Differential Revision: https://phabricator.haskell.org/D3581

`repNonArrowKind` was missing a case for `HsKindSig`, which this
commit adds. Fixes #13781.

Test Plan: make test TEST=T13781

Reviewers: goldfire, austin, bgamari

Reviewed By: goldfire

Subscribers: rwbarton, thomie

GHC Trac Issues: #13781

Differential Revision: https://phabricator.haskell.org/D3627

Commit 2b74bd9d did wonders for the
program reported in #12545. Let's add a perf test for it to make sure it
stays fast.

Test Plan: make test TEST=T12545

Reviewers: austin, bgamari

Reviewed By: bgamari

Subscribers: rwbarton, thomie

GHC Trac Issues: #12545

Differential Revision: https://phabricator.haskell.org/D3632

The problem was that the generated label included
a freshly assigned Unique value.

Test Plan:
Added a new test and looked at the generated stub:

```
 #include "HsFFI.h"
 #ifdef __cplusplus
 extern "C" {
 #endif
 extern HsInt zdmainzdAzdAzuzzlzzgzzg(StgStablePtr the_stableptr);
 extern HsInt zdmainzdAzdAzumkStringWriter(StgStablePtr the_stableptr);
 #ifdef __cplusplus
 }
 #endif
```

./validate

Reviewers: simonmar, austin, bgamari

Reviewed By: simonmar

Subscribers: rwbarton, thomie

GHC Trac Issues: #13807

Differential Revision: https://phabricator.haskell.org/D3633

Test Plan: validate

Reviewers: bgamari, niteria, austin, erikd

Reviewed By: bgamari

Subscribers: rwbarton, thomie

Differential Revision: https://phabricator.haskell.org/D3640

This fixes the regressions in the haddock performance tests introduced
in c9eb4385.

Reviewers: austin, bgamari

Reviewed By: bgamari

Subscribers: rwbarton, thomie

GHC Trac Issues: #13789

Differential Revision: https://phabricator.haskell.org/D3629

Remove filesToNotIntermediateClean from DynFlags, create a data type
FilesToClean, and change filesToClean in DynFlags to be a FilesToClean.

Modify SysTools.newTempName and the Temporary constructor of
PipelineMonad.PipelineOutput to take a TempFileLifetime, which specifies
whether a temp file should live until the end of GhcMonad.withSession,
or until the next time cleanIntermediateTempFiles is called.

These changes allow the cleaning of intermediate files in GhcMake to be
much more efficient.

HscTypes.hptObjs is removed as it is no longer used.

A new performance test T13701 is added, which passes both with and
without -keep-tmp-files.  The test fails by 25% without the patch, and
passes when -keep-tmp-files is added.

Note that there are still at two hotspots caused by
algorithms quadratic in the number of modules, however neither of them
allocate. They are:

* DriverPipeline.compileOne'.needsLinker
* GhcMake.getModLoop

DriverPipeline.compileOne'.needsLinker is changed slightly to improve
the situation.

I don't like adding these Types to DynFlags, but they need to be seen by
Dynflags, SysTools and PipelineMonad. The alternative seems to be to
create a new module.

Reviewers: austin, hvr, bgamari, dfeuer, niteria, simonmar, erikd

Reviewed By: simonmar

Subscribers: rwbarton, thomie

GHC Trac Issues: #13701

Differential Revision: https://phabricator.haskell.org/D3620

This is a module contributed by Austin Seipp which is fairly minimal
(albeit requiring vector) but is still representative of contemporary
Haskell.

Reviewers: austin

Subscribers: dfeuer, rwbarton, thomie

Differential Revision: https://phabricator.haskell.org/D3596

Summary:
The problem occurred when
* Threads A & B evaluate the same thunk
* Thread A context-switches, so the thunk gets blackholed
* Thread C enters the blackhole, creates a BLOCKING_QUEUE attached to
  the blackhole and thread A's `tso->bq` queue
* Thread B updates the blackhole with a value, overwriting the BLOCKING_QUEUE
* We GC, replacing A's update frame with stg_enter_checkbh
* Throw an exception in A, which ignores the stg_enter_checkbh frame

Now we have C blocked on A's tso->bq queue, but we forgot to check the
queue because the stg_enter_checkbh frame has been thrown away by the
exception.

The solution and alternative designs are discussed in Note [upd-black-hole].

This also exposed a bug in the interpreter, whereby we were sometimes
context-switching without calling `threadPaused()`.  I've fixed this
and added some Notes.

Test Plan:
* `cd testsuite/tests/concurrent && make slow`
* validate

Reviewers: niteria, bgamari, austin, erikd

Reviewed By: erikd

Subscribers: rwbarton, thomie

GHC Trac Issues: #13751

Differential Revision: https://phabricator.haskell.org/D3630

This patch fixes a bad bug in the specialiser, which showed up as
Trac #13429.  When specialising an imported DFun, the specialiser could
generate a recusive loop where none existed in the original program.

It's all rather tricky, and I've documented it at some length in
   Note [Avoiding loops]

We'd encoutered exactly this before (Trac #3591) but I had failed
to realise that the very same thing could happen for /imported/
DFuns.

I did quite a bit of refactoring.

The compiler seems to get a tiny bit faster on
   deriving/perf/T10858
but almost all the gain had occurred before now; this
patch just pushed it over the line.

Summary:
See https://ghc.haskell.org/trac/ghc/wiki/ImplementingTreesThatGrow

This commit prepares the ground for a full extensible AST, by replacing the type
parameter for the hsSyn data types with a set of indices into type families,

    data GhcPs -- ^ Index for GHC parser output
    data GhcRn -- ^ Index for GHC renamer output
    data GhcTc -- ^ Index for GHC typechecker output

These are now used instead of `RdrName`, `Name` and `Id`/`TcId`/`Var`

Where the original name type is required in a polymorphic context, this is
accessible via the IdP type family, defined as

    type family IdP p
    type instance IdP GhcPs = RdrName
    type instance IdP GhcRn = Name
    type instance IdP GhcTc = Id

These types are declared in the new 'hsSyn/HsExtension.hs' module.

To gain a better understanding of the extension mechanism, it has been applied
to `HsLit` only, also replacing the `SourceText` fields in them with extension
types.

To preserve extension generality, a type class is introduced to capture the
`SourceText` interface, which must be honoured by all of the extension points
which originally had a `SourceText`.  The class is defined as

    class HasSourceText a where
      -- Provide setters to mimic existing constructors
      noSourceText  :: a
      sourceText    :: String -> a

      setSourceText :: SourceText -> a
      getSourceText :: a -> SourceText

And the constraint is captured in `SourceTextX`, which is a constraint type
listing all the extension points that make use of the class.

Updating Haddock submodule to match.

Test Plan: ./validate

Reviewers: simonpj, shayan-najd, goldfire, austin, bgamari

Subscribers: rwbarton, thomie, mpickering

Differential Revision: https://phabricator.haskell.org/D3609

Previously modules with hscTarget == HscNothing were not desugared.
This patch changes behavior so that all modules HsSrcFile Modules except GHC.Prim
are desugared. Modules with hscTarget == HscNothing are not simplified.

Warnings and errors produced by the desugarer will now be produced when
compiling with -fno-code.

HscMain.finishTypecheckingOnly is removed, HscMain.hscIncrementalCompile is
simplified a bit, and HscMain.finish takes in the removed logic. I think this
is easier to follow.

Updates haddock submodule.

Tests T8101, T8101b, T10600 are no longer expect_broken.

Reviewers: ezyang, austin, bgamari

Subscribers: rwbarton, thomie

GHC Trac Issues: #10600

Differential Revision: https://phabricator.haskell.org/D3542

Trac #13785 showed that we were emitting monomorphism warnings
when we shouldn't.  The fix turned out to be simple.

In fact test T10935 then turned out to be another example of
the over-noisy warning so I changed the test slightly.

Previously, we were running some blocks of code at the start of every
GHCi sessions which use do-notation, something which doesn't work well
if you start GHCi with the `-XRebindableSyntax` flag on. This tweaks the
code to avoid the use of do-notation so that `-XRebindableSyntax` won't
reject it.

Test Plan: make test TEST=T13385

Reviewers: austin, bgamari

Reviewed By: bgamari

Subscribers: rwbarton, thomie

GHC Trac Issues: #13385

Differential Revision: https://phabricator.haskell.org/D3621

The import library support added for 7.10.3 was only a partial one.
This support was predicated on using file extensions to determine
whether or not a library was an import library. It also couldn't handle
libraries with multiple dll pointers.

This is a rewrite of that patch and fully integrating it into the normal
archive parsing and loading routines. This solves a host of issues,
among others allowing us to finally use `-lgcc_s`.

This also fixes a problem with our previous implementation, where we
just loaded the DLL and moved on. Doing this had the potential of using
the wrong symbol at resolve time. Say a DLL already loaded (A.dll) has
symbol a exported (dependency of another dll perhaps).

We find an import library `B.lib` explicitly defining an export of `a`.
we load `B.dll` but this gets put after `A.dll`, at resolve time we
would use the value from `A` instead of `B` which is what we wanted.

Test Plan: ./valide and make test TEST=13606

Reviewers: austin, bgamari, erikd, simonmar

Reviewed By: bgamari

Subscribers: rwbarton, RyanGlScott, thomie, #ghc_windows_task_force

GHC Trac Issues: #13606, #12499, #12498

Differential Revision: https://phabricator.haskell.org/D3513

This implements the idea from
https://ghc.haskell.org/trac/ghc/ticket/13092#comment:14.

It's explained in Note [Checking family instance optimization]
in more detail.

This improves the test case T13719 tenfold and
cuts down the compile time on `:load` in `ghci` on our
internal code base by half.

Test Plan: ./validate

Reviewers: simonpj, simonmar, rwbarton, austin, bgamari

Reviewed By: simonpj

Subscribers: thomie

GHC Trac Issues: #13719

Differential Revision: https://phabricator.haskell.org/D3603

This is a cleanup after Trac #13238, as the context was no longer being used.

Most are cosmetic. There's an interesting change in T7861,
but the error is still accurate.

Commit ce97b729 (the fix for #12175) also
fixed #12648. Let's add a regression test so that it stays fixed.

Triggered by the changes in #13677, I ended up doing a bit of
refactoring in type pretty-printing.

* We were using TyOpPrec and FunPrec rather inconsitently, so
  I made it consisent.

* That exposed the fact that we were a bit undecided about whether
  to print
     a + b -> c + d   vs   (a+b) -> (c+d)
  and similarly
     a ~ [b] => blah  vs   (a ~ [b]) => blah

  I decided to make TyOpPrec and FunPrec compare equal
  (in BasicTypes), so (->) is treated as equal precedence with
  other type operators, so you get the unambiguous forms above,
  even though they have more parens.

  We could readily reverse this decision.
  See Note [Type operator precedence] in BasicTypes

* I fixed a bug in pretty-printing of HsType where some
  parens were omitted by mistake.

The big change here is to fix an outright bug in flattening of Givens,
albeit one that is very hard to exhibit.  Suppose we have the constraint
    forall a. (a ~ F b) => ..., (forall c. ....(F b)...) ...

Then
 - we'll flatten the (F) b to a fsk, say  (F b ~ fsk1)
 - we'll rewrite the (F b) inside the inner implication to 'fsk1'
 - when we leave the outer constraint we are suppose to unflatten;
   but that fsk1 will still be there
 - if we re-simplify the entire outer implication, we'll re-flatten
   the Given (F b) to, say, (F b ~ fsk2)
Now we have two fsks standing for the same thing, and that is very
wrong.

Solution: make fsks behave more like fmvs:
 - A flatten-skolem is now a MetaTyVar, whose MetaInfo is FlatSkolTv
 - We "fill in" that meta-tyvar when leaving the implication
 - The old FlatSkol form of TcTyVarDetails is gone completely
 - We track the flatten-skolems for the current implication in
   a new field of InertSet, inert_fsks.

See Note [The flattening story] in TcFlatten.

In doing this I found various other things to fix:

* I removed the zonkSimples from TcFlatten.unflattenWanteds; it wasn't
  needed.   But I added one in TcSimplify.floatEqualities, which does
  the zonk precisely when it is needed.

* Trac #13674 showed up a case where we had
     - an insoluble Given,   e.g.  a ~ [a]
     - the same insoluble Wanted   a ~ [a]
  We don't use the Given to rewwrite the Wanted (obviously), but
  we therefore ended up reporting
      Can't deduce (a ~ [a]) from (a ~ [a])
  which is silly.

  Conclusion: when reporting errors, make the occurs check "win"
  See Note [Occurs check wins] in TcErrors

This patch fixes two separate bugs which contributed to making
Trac #13752 go wrong

1.  We need to use tcSubType, not tcUnify,
    in tcCheckPatSynDecl.tc_arg.

    Reason: Note [Pattern synonyms and higher rank types]

2.  TcUnify.tc_sub_type had a special case designed to improve error
    messages; see Note [Don't skolemise unnecessarily].  But the
    special case was too liberal, and ended up using unification
    (which led to rejecting the program) when it should instead taken
    the normal path (which accepts the program).

    I fixed this by making the test more conservative.

Based on my quick search, we don't have a test
that verifies that we check the type family instances of
currently compiled module against direct or indirect
dependencies.

This adds two tests: for a direct dependency and
for an indirect dependency.

I also added a comment to make it clear what the 'Over'
test tests.

Other than completeness, it makes sense to have these
tests because if you look at
Note [The type family instance consistency story] in FamInsts
these cases are checked through different mechanisms.

Test Plan: new tests

Reviewers: simonmar, rwbarton, simonpj, austin, bgamari

Reviewed By: simonpj, bgamari

Subscribers: thomie

GHC Trac Issues: #13719

Differential Revision: https://phabricator.haskell.org/D3602

I expect to improve this, a testcase will ensure
it doesn't regress.

Test Plan: ./validate

Reviewers: simonmar, austin, bgamari

Reviewed By: bgamari

Subscribers: rwbarton, thomie

GHC Trac Issues: #13719

Differential Revision: https://phabricator.haskell.org/D3600

When main module is listed on command line as a file, we should not
issue a warning about it. See Trac #13727

Reviewers: austin, bgamari, Yuras

Reviewed By: bgamari, Yuras

Subscribers: 23Skidoo, rwbarton, thomie

GHC Trac Issues: #13727

Differential Revision: https://phabricator.haskell.org/D3598

We need to use parentheses more when pretty-printing types with bang
patterns within constructors that use record syntax. Fixes #13699.

Test Plan: make test TEST=T13699

Reviewers: austin, bgamari, dfeuer

Reviewed By: dfeuer

Subscribers: dfeuer, rwbarton, thomie

GHC Trac Issues: #13699

Differential Revision: https://phabricator.haskell.org/D3587

rwbarton pointed out that tab expansions can affect the column numbers
of subsequent characters, so a unstateful map + zip won't do.  This
commit hopefully fixes that.  It also adds a test for this particular
case.

Test Plan: validate

Reviewers: bgamari, rwbarton, austin

Reviewed By: bgamari

Subscribers: dfeuer, thomie

Differential Revision: https://phabricator.haskell.org/D3578