[Git][ghc/ghc][wip/T20749] 22 commits: isIrrefutableHsPat: look up ConLikes in the HscEnv

Sebastian Graf (@sgraf812) gitlab at gitlab.haskell.org
Wed Aug 28 12:32:16 UTC 2024



Sebastian Graf pushed to branch wip/T20749 at Glasgow Haskell Compiler / GHC


Commits:
bdd77b9e by sheaf at 2024-08-16T12:47:11-04:00
isIrrefutableHsPat: look up ConLikes in the HscEnv

At GhcRn stage, in isIrrefutableHsPat we only looked up data constructors
in the RdrEnv, which meant that we lacked fallibility information for
out-of-scope constructors (which can arise from Template Haskell splices).

Instead, we use 'lookupGREInfo', which looks up the information in
the type environment. This was the correct function to call all along,
but was not used in 572fbc44 due to import cycle reasons. The appropriate
functions, 'irrefutableConLike{Rn,Tc}' have been moved to 'GHC.Rename.Env',
which avoids import cycles.

Fixes #25164

- - - - -
4bee377c by Sylvain Henry at 2024-08-16T12:47:53-04:00
Linker: some refactoring to prepare for #24886

- Rename LoadedBCOs into LazyBCOs
- Bundle SptEntries with CompiledByteCode and removed [SptEntry] field
  from the BCOs constructor
- Rename Linkable's LM constructor into Linkable: in the past we had LM
  and LP for Module and Package, now we only have the former.
- Rename Unlinked into LinkablePart (and linkableUnlinked into
  linkableParts)
- Use NonEmpty to encode invariant in Linkable's linkableParts type
- Add helpers: linkableLibs, linkableBCOs, etc.
- Add documentation
- Remove partial nameOfObject
- Rename nameOfObject_maybe into linkablePartPath
- Rename byteCodeOfObject into linkablePartAllBCOs.
- Refactor linkablePartAllBCOs to avoid a panic if a LazyBCO has a C
  stub. Document the fact that LazyBCOs are returned in this case
  (contrary to linkableBCOs which only returns non-lazy ones)

Refactoring done while trying to understand how to adapt the linker code
to support the JS backend too (cf #24886).

- - - - -
fa0dbaca by Mario Blažević at 2024-08-17T03:31:32+00:00
Implements the Exportable Named Default proposal (#24305)

This squashed commit adds support for exportable named defaults, the accepted
GHC proposal at https://github.com/ghc-proposals/ghc-proposals/pull/409

The proposal extends the Haskell '98 declarations

    default (Int, Double)

which were implicitly always applying to Num class alone, to allow specifying
an arbitrary single-parameter class:

    default IsString (Text, String)

The effect of this declaration would be to eliminate the ambiguous type errors
around string literals when OverloadedStrings extension is active. The
declaration by itself has effect only in its module, so the proposal also adds
the ability to export class defaults:

    module MyModule (default IsIstring)

Once the language extension is published and established, we can consider using
it in base and other libraries.

See Note [Named default declarations] in GHC.Tc.Gen.Default
for implementation details.

- - - - -
1deba6b2 by Simon Peyton Jones at 2024-08-17T13:58:13-04:00
Make kick-out more selective

This MR revised the crucial kick-out criteria in the constraint solver.

Ticket #24984 showed an example in which
 * We were kicking out unnecessarily
 * That gave rise to extra work, of course
 * But it /also/ led to exponentially-sized coercions due to lack
   of sharing in coercions (something we want to fix separately #20264)

This MR sharpens up the kick-out criteria; specifially in (KK2) we look
only under type family applications if (fs>=fw).

This forced me to understand the existing kick-out story, and I ended
up rewriting many of the careful Notes in GHC.Tc.Solver.InertSet.
Especially look at the new `Note [The KickOut Criteria]`

The proof of termination is not air-tight, but it is better than before,
and both Richard and I think it's correct :-).

- - - - -
88488847 by Cheng Shao at 2024-08-18T04:44:01+02:00
testsuite: remove undesired -fasm flag from test ways

This patch removes the -fasm flag from test ways, except ways like
optasm that explicitly state they are meant to be compiled with NCG
backend. Most test ways should use the default codegen backend, and
the precense of -fasm can cause stderr mismatches like this when GHC
is configured with the unregisterised backend:

```
--- /dev/null
+++ /tmp/ghctest-3hydwldj/test   spaces/testsuite/tests/profiling/should_compile/prof-late-cc.run/prof-late-cc.comp.stderr.normalised
@@ -0,0 +1,2 @@
+when making flags consistent: warning: [GHC-74335] [-Winconsistent-flags (in -Wdefault)]
+    Target platform uses unregisterised ABI, so compiling via C
*** unexpected failure for prof-late-cc(prof_no_auto)
```

This has been breaking the wasm unreg nightly job since !12595 landed.

- - - - -
3a145315 by Cheng Shao at 2024-08-18T13:05:45-04:00
ghci: fix isMinTTY.h casing for Windows targets

This commit fixes isMinTTY.h casing in isMinTTY.c that's compiled for
Windows targets. While this looks harmless given Windows filesystems
are case-insensitive by default, it does cause a compilation warning
with recent versions of clang, so we might as well fix the casing:

```
driver\ghci\isMinTTY.c:10:10: error:
     warning: non-portable path to file '"isMinTTY.h"'; specified path differs in case from file name on disk [-Wnonportable-include-path]
   |
10 | #include "isMINTTY.h"
   |          ^

 #include "isMINTTY.h"
         ^~~~~~~~~~~~
         "isMinTTY.h"
1 warning generated.
```

- - - - -
5f972bfb by Zubin Duggal at 2024-08-21T03:18:15-04:00
compiler: Fix pretty printing of ticked prefix constructors (#24237)

- - - - -
ef0a08e7 by Mike Pilgrem at 2024-08-21T03:18:57-04:00
Fix #15773 Clarify further -rtsopts 'defaults' in docs

- - - - -
05a4be58 by Sebastian Graf at 2024-08-21T03:19:33-04:00
Improve efficiency of `assertError` (#24625)

... by moving `lazy` to the exception-throwing branch.
It's all documented in `Note [Strictness of assertError]`.

- - - - -
c29b2b5a by sheaf at 2024-08-21T13:11:30-04:00
GHCi debugger: drop record name spaces for Ids

When binding new local variables at a breakpoint, we should create
Ids with variable namespace, and not record field namespace. Otherwise
the rest of the compiler falls over because the IdDetails are wrong.

Fixes #25109

- - - - -
bd82ac9f by Hécate Kleidukos at 2024-08-21T13:12:12-04:00
base: Final deprecation of GHC.Pack

The timeline mandated by #21461 has come to its term and after two years
and four minor releases, we are finally removing GHC.Pack from base.

Closes #21536

- - - - -
5092dbff by Sylvain Henry at 2024-08-21T13:12:54-04:00
JS: support rubbish static literals (#25177)

Support for rubbish dynamic literals was added in #24664. This patch
does the same for static literals.

Fix #25177

- - - - -
b5a2c061 by Phil de Joux at 2024-08-21T13:13:33-04:00
haddock docs: prefix comes before, postfix comes after

- - - - -
6fde3685 by Marcin Szamotulski at 2024-08-21T23:15:39-04:00
haddock: include package info with --show-interface

- - - - -
7e02111b by Andreas Klebinger at 2024-08-21T23:16:15-04:00
Document the (x86) SIMD macros.

Fixes #25021.

- - - - -
05116c83 by Rodrigo Mesquita at 2024-08-22T10:37:44-04:00
ghc-internal: Derive version from ghc's version

Fixes #25005

- - - - -
73f5897d by Ben Gamari at 2024-08-22T10:37:44-04:00
base: Deprecate GHC.Desugar

See https://github.com/haskell/core-libraries-committee/issues/216.

This will be removed in GHC 9.14.

- - - - -
821d0a9a by Cheng Shao at 2024-08-22T10:38:22-04:00
compiler: Store ForeignStubs and foreign C files in interfaces

This data is used alongside Core bindings to reconstruct intermediate
build products when linking Template Haskell splices with bytecode.

Since foreign stubs and files are generated in the pipeline, they were
lost with only Core bindings stored in interfaces.

The interface codec type `IfaceForeign` contains a simplified
representation of `ForeignStubs` and the set of foreign sources that
were manually added by the user.

When the backend phase writes an interface, `mkFullIface` calls
`encodeIfaceForeign` to read foreign source file contents and assemble
`IfaceForeign`.

After the recompilation status check of an upstream module,
`initWholeCoreBindings` calls `decodeIfaceForeign` to restore
`ForeignStubs` and write the contents of foreign sources to the file
system as temporary files.
The restored foreign inputs are then processed by `hscInteractive` in
the same manner as in a regular pipeline.

When linking the stub objects for splices, they are excluded from suffix
adjustment for the interpreter way through a new flag in `Unlinked`.

For details about these processes, please consult Note [Foreign stubs
and TH bytecode linking].

Metric Decrease:
    T13701

- - - - -
f0408eeb by Cheng Shao at 2024-08-23T10:37:10-04:00
git: remove a.out and include it in .gitignore

a.out is a configure script byproduct. It was mistakenly checked into
the tree in !13118. This patch removes it, and include it in
.gitignore to prevent a similar error in the future.

- - - - -
1f95c5e4 by Matthew Pickering at 2024-08-23T10:37:46-04:00
docs: Fix code-block syntax on old sphinx version

This code-block directive breaks the deb9 sphinx build.

Fixes #25201

- - - - -
bfb1e7ad by Sebastian Graf at 2024-08-26T15:15:19+02:00
CorePrep: Attach evaldUnfolding to floats to detect more values

See `Note [Pin evaluatedness on floats]`.

- - - - -
4d2266a9 by Sebastian Graf at 2024-08-28T13:48:12+02:00
Make DataCon workers strict in strict fields (#20749)

This patch tweaks `exprIsConApp_maybe`, `exprIsHNF` and friends, and Demand
Analysis so that they exploit and maintain strictness of DataCon workers. See
`Note [Strict fields in Core]` for details.

Very little needed to change, and it puts field seq insertion done by Tag
Inference into a new perspective: That of *implementing* strict field semantics.
Before Tag Inference, DataCon workers are strict. Afterwards they are
effectively lazy and field seqs happen around use sites. History has shown
that there is no other way to guarantee taggedness and thus the STG Strict Field
Invariant.

Knock-on changes:

  * I reworked the whole narrative around "Tag inference".
    It's now called "EPT enforcement" and I recycyled the different overview
    Notes into `Note [EPT enforcement]`.

  * `exprIsHNF` previously used `exprOkForSpeculation` on unlifted arguments
    instead of recursing into `exprIsHNF`. That regressed the termination
    analysis in CPR analysis (which simply calls out to `exprIsHNF`), so I made
    it call `exprOkForSpeculation`, too.

  * There's a small regression in Demand Analysis, visible in the changed test
    output of T16859: Previously, a field seq on a variable would give that
    variable a "used exactly once" demand, now it's "used at least once",
    because `dmdTransformDataConSig` accounts for future uses of the field
    that actually all go through the case binder (and hence won't re-enter the
    potential thunk). The difference should hardly be observable.

  * The Simplifier's fast path for data constructors only applies to lazy
    data constructors now. I observed regressions involving Data.Binary.Put's
    `Pair` data type.

  * Unfortunately, T21392 does no longer reproduce after this patch, so I marked
    it as "not broken" in order to track whether we regress again in the future.

Fixes #20749, the satisfying conclusion of an annoying saga (cf. the ideas
in #21497 and #22475).

Compiler perf generally improves, sometimes drastically:

                                          Baseline
                      Test    Metric          value      New value Change
--------------------------------------------------------------------------------
  ManyConstructors(normal) ghc/alloc  3,629,760,116  3,711,852,800  +2.3%  BAD
            T12707(normal) ghc/alloc    804,399,798    791,807,320  -1.6% GOOD
            T17516(normal) ghc/alloc    964,987,744  1,008,383,520  +4.5%
            T18140(normal) ghc/alloc     75,381,152     49,860,560 -33.9% GOOD
           T18698b(normal) ghc/alloc    232,614,457    184,262,736 -20.8% GOOD
            T18923(normal) ghc/alloc     62,002,368     58,301,408  -6.0% GOOD
            T20049(normal) ghc/alloc     75,719,168     70,494,368  -6.9% GOOD
             T3294(normal) ghc/alloc  1,237,925,833  1,157,638,992  -6.5% GOOD
             T9233(normal) ghc/alloc    686,490,105    635,166,688  -7.5% GOOD

                 geo. mean                                          -0.7%
                 minimum                                           -33.9%
                 maximum                                            +4.5%

I looked at T17516. It seems we do a few more simplifier iterations and end up
with a larger program. It seems that some things inline more, while other things
inline less. I don't see low-hanging fruit.

NoFib does not seem affected much either:

+-------------------------------++--+------------+-----------+---------------+-----------+
|                               ||  |      base/ | std. err. | T20749/ (rel) | std. err. |
+===============================++==+============+===========+===============+===========+
|           spectral/last-piece ||  |    7.263e8 |      0.0% |        +0.62% |      0.0% |
+===============================++==+============+===========+===============+===========+
|                     geom mean ||  |     +0.00% |           |               |           |
+-------------------------------++--+------------+-----------+---------------+-----------+

I had a look at last-piece. Nothing changes in stg-final, but there is a bit
of ... movement around Data.Map.insert's use of GHC.Exts.lazy that is gone in
stg-final.

Metric Decrease:
    T12707
    T18140
    T18698b
    T18923
    T20049
    T3294
    T9233
Metric Increase:
    ManyConstructors

Co-Authored-By: Jaro Reinders <jaro.reinders at gmail.com>

- - - - -


30 changed files:

- .gitignore
- compiler/GHC/Builtin/Types.hs
- compiler/GHC/ByteCode/Asm.hs
- compiler/GHC/ByteCode/Types.hs
- compiler/GHC/Cmm/CLabel.hs
- compiler/GHC/Core.hs
- compiler/GHC/Core/DataCon.hs
- compiler/GHC/Core/Opt/Arity.hs
- compiler/GHC/Core/Opt/CprAnal.hs
- compiler/GHC/Core/Opt/DmdAnal.hs
- compiler/GHC/Core/Opt/Simplify/Env.hs
- compiler/GHC/Core/Opt/Simplify/Iteration.hs
- compiler/GHC/Core/Opt/WorkWrap/Utils.hs
- compiler/GHC/Core/Predicate.hs
- compiler/GHC/Core/SimpleOpt.hs
- compiler/GHC/Core/Type.hs
- compiler/GHC/Core/Utils.hs
- compiler/GHC/CoreToIface.hs
- compiler/GHC/CoreToStg/Prep.hs
- compiler/GHC/Driver/Backpack.hs
- compiler/GHC/Driver/Flags.hs
- compiler/GHC/Driver/Main.hs
- compiler/GHC/Driver/Make.hs
- compiler/GHC/Driver/Pipeline.hs
- compiler/GHC/Driver/Pipeline/Execute.hs
- compiler/GHC/Hs/Decls.hs
- compiler/GHC/Hs/ImpExp.hs
- compiler/GHC/Hs/Pat.hs
- compiler/GHC/HsToCore.hs
- compiler/GHC/HsToCore/Quote.hs


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