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* Modules: Core (#13009)Sylvain Henry2020-02-261-2821/+0
| | | | Update haddock submodule
* Comments, small refactorKrzysztof Gogolewski2020-02-241-20/+12
| | | | | | | | | | | | * Remove outdated Note [HsForAllTy tyvar binders] and [Context quantification]. Since the wildcard refactor 1e041b7382, HsForAllTy no longer has an flag controlling explicity. The field `hsq_implicit` is gone too. The current situation is covered by Note [HsType binders] which is already linked from LHsQTyVars. * Small refactor in CoreLint, extracting common code to a function * Remove "not so sure about WpFun" in TcEvidence, per Richard's comment https://gitlab.haskell.org/ghc/ghc/merge_requests/852#note_223226 * Use mkIfThenElse in Foreign/Call, as it does exactly what we need.
* Modules: Driver (#13009)Sylvain Henry2020-02-211-3/+3
| | | | submodule updates: nofib, haddock
* Re-implement unsafe coercions in terms of unsafe equality proofsSimon Peyton Jones2020-02-201-13/+42
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | (Commit message written by Omer, most of the code is written by Simon and Richard) See Note [Implementing unsafeCoerce] for how unsafe equality proofs and the new unsafeCoerce# are implemented. New notes added: - [Checking for levity polymorphism] in CoreLint.hs - [Implementing unsafeCoerce] in base/Unsafe/Coerce.hs - [Patching magic definitions] in Desugar.hs - [Wiring in unsafeCoerce#] in Desugar.hs Only breaking change in this patch is unsafeCoerce# is not exported from GHC.Exts, instead of GHC.Prim. 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Allocates more on 32-bit platforms. - Rest of the increases are tiny amounts (still enough to pass the threshold) in micro-benchmarks. I briefly looked at each one in a profiling build: most of the increased allocations seem to be because of random changes in the generated code. Metric Decrease: T14683 Metric Increase: T12150 T12234 T12425 T13035 T14683 T5837 T6048 Co-Authored-By: Richard Eisenberg <rae@cs.brynmawr.edu> Co-Authored-By: Ömer Sinan Ağacan <omeragacan@gmail.com>
* Separate CPR analysis from the Demand analyserwip/sep-cprSebastian Graf2020-02-121-3/+4
| | | | | | | | | | | | | | | | | | | The reasons for that can be found in the wiki: https://gitlab.haskell.org/ghc/ghc/wikis/nested-cpr/split-off-cpr We now run CPR after demand analysis (except for after the final demand analysis run just before code gen). CPR got its own dump flags (`-ddump-cpr-anal`, `-ddump-cpr-signatures`), but not its own flag to activate/deactivate. It will run with `-fstrictness`/`-fworker-wrapper`. As explained on the wiki page, this step is necessary for a sane Nested CPR analysis. And it has quite positive impact on compiler performance: Metric Decrease: T9233 T9675 T9961 T15263
* Module hierarchy: Iface (cf #13009)Sylvain Henry2020-01-061-1/+1
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* Fix typos, via a Levenshtein-style correctorBrian Wignall2020-01-041-1/+1
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* Module hierarchy (#13009): StgSylvain Henry2019-12-311-1/+1
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* Add GHC-API logging hooksSylvain Henry2019-12-181-2/+4
| | | | | | | | | | | | | | | | | | | | | | | * Add 'dumpAction' hook to DynFlags. It allows GHC API users to catch dumped intermediate codes and information. The format of the dump (Core, Stg, raw text, etc.) is now reported allowing easier automatic handling. * Add 'traceAction' hook to DynFlags. Some dumps go through the trace mechanism (for instance unfoldings that have been considered for inlining). This is problematic because: 1) dumps aren't written into files even with -ddump-to-file on 2) dumps are written on stdout even with GHC API 3) in this specific case, dumping depends on unsafe globally stored DynFlags which is bad for GHC API users We introduce 'traceAction' hook which allows GHC API to catch those traces and to avoid using globally stored DynFlags. * Avoid dumping empty logs via dumpAction/traceAction (but still write empty files to keep the existing behavior)
* Do more validity checks for quantified constraintsRichard Eisenberg2019-12-161-1/+1
| | | | | | Close #17583. Test case: typecheck/should_fail/T17563
* Optimize MonadUnique instances based on IO (#16843)nineonine2019-11-191-2/+2
| | | | | Metric Decrease: T14683
* Ensure that coreView/tcView are able to inlineBen Gamari2019-11-131-1/+1
| | | | | | | | | | | | | | | | | | | | Previously an import cycle between Type and TyCoRep meant that several functions in TyCoRep ended up SOURCE import coreView. This is quite unfortunate as coreView is intended to be fused into a larger pattern match and not incur an extra call. Fix this with a bit of restructuring: * Move the functions in `TyCoRep` which depend upon things in `Type` into `Type` * Fold contents of `Kind` into `Type` and turn `Kind` into a simple wrapper re-exporting kind-ish things from `Type` * Clean up the redundant imports that popped up as a result Closes #17441. Metric Decrease: T4334
* Makes Lint less chatty:Simon Peyton Jones2019-11-011-11/+13
| | | | | | | | | | | | | | | | | I found in #17415 that Lint was printing out truly gigantic warnings, unmanageably huge, with repeated copies of the same thing. This patch makes Lint less chatty, especially for warnings: * For **warnings**, I don't print details of the location, unless you add `-dppr-debug`. * For **errors**, I still print all the info. They are fatal and stop exection, whereas warnings appear repeatedly. * I've made much less use of `AnExpr` in `LintLocInfo`; the expression can be gigantic.
* Fix bogus type of case expressionwip/T17056Simon Peyton Jones2019-09-201-61/+114
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Issue #17056 revealed that we were sometimes building a case expression whose type field (in the Case constructor) was bogus. Consider a phantom type synonym type S a = Int and we want to form the case expression case x of K (a::*) -> (e :: S a) We must not make the type field of the Case constructor be (S a) because 'a' isn't in scope. We must instead expand the synonym. Changes in this patch: * Expand synonyms in the new function CoreUtils.mkSingleAltCase. * Use mkSingleAltCase in MkCore.wrapFloat, which was the proximate source of the bug (when called by exprIsConApp_maybe) * Use mkSingleAltCase elsewhere * Documentation CoreSyn new invariant (6) in Note [Case expression invariants] CoreSyn Note [Why does Case have a 'Type' field?] CoreUtils Note [Care with the type of a case expression] * I improved Core Lint's error reporting, which was pretty confusing in this case, because it didn't mention that the offending type was the return type of a case expression. * A little bit of cosmetic refactoring in CoreUtils
* Break up TyCoRepBen Gamari2019-07-311-4/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | This breaks up the monstrous TyCoReps module into several new modules by topic: * TyCoRep: Contains the `Coercion`, `Type`, and related type definitions and a few simple predicates but nothing further * TyCoPpr: Contains the the pretty-printer logic * TyCoFVs: Contains the free variable computations (and `tyConAppNeedsKindSig`, although I suspect this should change) * TyCoSubst: Contains the substitution logic for types and coercions * TyCoTidy: Contains the tidying logic for types While we are able to eliminate a good number of `SOURCE` imports (and make a few others smaller) with this change, we must introduce one new `hs-boot` file for `TyCoPpr` so that `TyCoRep` can define `Outputable` instances for the types it defines. Metric Increase: haddock.Cabal haddock.compiler
* Fix erroneous float in CoreOptSimon Peyton Jones2019-07-091-3/+6
| | | | | | | | | | | The simple optimiser was making an invalid transformation to join points -- yikes. The fix is easy. I also added some documentation about the fact that GHC uses a slightly more restrictive version of join points than does the paper. Fix #16918
* Minor refactoring in CoreSimplÖmer Sinan Ağacan2019-07-091-3/+0
| | | | | | When `join_ids` is empty `extendVarSetList existing_joins join_ids` is already no-op, so no need to check whether `join_ids` is empty or not before extending the joins set.
* Use DeriveFunctor throughout the codebase (#15654)Krzysztof Gogolewski2019-06-121-3/+2
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* Compute demand signatures assuming idAritySebastian Graf2019-04-301-23/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | This does four things: 1. Look at `idArity` instead of manifest lambdas to decide whether to use LetUp 2. Compute the strictness signature in LetDown assuming at least `idArity` incoming arguments 3. Remove the special case for trivial RHSs, which is subsumed by 2 4. Don't perform the W/W split when doing so would eta expand a binding. Otherwise we would eta expand PAPs, causing unnecessary churn in the Simplifier. NoFib Results -------------------------------------------------------------------------------- Program Allocs Instrs -------------------------------------------------------------------------------- fannkuch-redux +0.3% 0.0% gg -0.0% -0.1% maillist +0.2% +0.2% minimax 0.0% +0.8% pretty 0.0% -0.1% reptile -0.0% -1.2% -------------------------------------------------------------------------------- Min -0.0% -1.2% Max +0.3% +0.8% Geometric Mean +0.0% -0.0%
* Add a safeguard to Core LintKrzysztof Gogolewski2019-04-141-3/+6
| | | | | | | | | Lint returns a pair (Maybe a, WarnsAndErrs). The Maybe monad allows to handle an unrecoverable failure. In case of such a failure, the error should be added to the second component of the pair. If this is not done, Lint will silently accept bad programs. This situation actually happened during development of linear types. This adds a safeguard.
* Update Wiki URLs to point to GitLabTakenobu Tani2019-03-251-1/+1
| | | | | | | | | | | | | | | | | | | | | | | This moves all URL references to Trac Wiki to their corresponding GitLab counterparts. This substitution is classified as follows: 1. Automated substitution using sed with Ben's mapping rule [1] Old: ghc.haskell.org/trac/ghc/wiki/XxxYyy... New: gitlab.haskell.org/ghc/ghc/wikis/xxx-yyy... 2. Manual substitution for URLs containing `#` index Old: ghc.haskell.org/trac/ghc/wiki/XxxYyy...#Zzz New: gitlab.haskell.org/ghc/ghc/wikis/xxx-yyy...#zzz 3. Manual substitution for strings starting with `Commentary` Old: Commentary/XxxYyy... New: commentary/xxx-yyy... See also !539 [1]: https://gitlab.haskell.org/bgamari/gitlab-migration/blob/master/wiki-mapping.json
* Update Trac ticket URLs to point to GitLabRyan Scott2019-03-151-10/+10
| | | | | This moves all URL references to Trac tickets to their corresponding GitLab counterparts.
* Add AnonArgFlag to FunTySimon Peyton Jones2019-02-231-3/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The big payload of this patch is: Add an AnonArgFlag to the FunTy constructor of Type, so that (FunTy VisArg t1 t2) means (t1 -> t2) (FunTy InvisArg t1 t2) means (t1 => t2) The big payoff is that we have a simple, local test to make when decomposing a type, leading to many fewer calls to isPredTy. To me the code seems a lot tidier, and probably more efficient (isPredTy has to take the kind of the type). See Note [Function types] in TyCoRep. There are lots of consequences * I made FunTy into a record, so that it'll be easier when we add a linearity field, something that is coming down the road. * Lots of code gets touched in a routine way, simply because it pattern matches on FunTy. * I wanted to make a pattern synonym for (FunTy2 arg res), which picks out just the argument and result type from the record. But alas the pattern-match overlap checker has a heart attack, and either reports false positives, or takes too long. In the end I gave up on pattern synonyms. There's some commented-out code in TyCoRep that shows what I wanted to do. * Much more clarity about predicate types, constraint types and (in particular) equality constraints in kinds. See TyCoRep Note [Types for coercions, predicates, and evidence] and Note [Constraints in kinds]. This made me realise that we need an AnonArgFlag on AnonTCB in a TyConBinder, something that was really plain wrong before. See TyCon Note [AnonTCB InivsArg] * When building function types we must know whether we need VisArg (mkVisFunTy) or InvisArg (mkInvisFunTy). This turned out to be pretty easy in practice. * Pretty-printing of types, esp in IfaceType, gets tidier, because we were already recording the (->) vs (=>) distinction in an ad-hoc way. Death to IfaceFunTy. * mkLamType needs to keep track of whether it is building (t1 -> t2) or (t1 => t2). See Type Note [mkLamType: dictionary arguments] Other minor stuff * Some tidy-up in validity checking involving constraints; Trac #16263
* Prepare source-tree for base-4.13 MFP bumpHerbert Valerio Riedel2019-01-181-0/+2
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* Fix treatment of hi-boot files and dfunsSimon Peyton Jones2018-12-211-24/+37
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Trac #16038 exposed the fact that TcRnDriver.checkHiBootIface was creating a binding, in the module being compiled, for $fxBlah = $fBlah but $fxBlah was a /GlobalId/. But all bindings should be for /LocalIds/ else dependency analysis goes down the tubes. * I added a CoreLint check that an occurrence of a GlobalId is not bound by an binding of a LocalId. (There is already a binding-site check that no binding binds a GlobalId.) * I refactored (and actually signficantly simplified) the tricky code for dfuns in checkHiBootIface to ensure that we get LocalIds for those boot-dfuns. Alas, I then got "duplicate instance" messages when compiling HsExpr. It turns out that this is a long-standing, but extremely delicate, bug: even before this patch, if you compile HsExpr with -ddump-tc-trace, you get "duplicate instance". Without -ddump-tc-trace, it's OK. What a mess! The reason for the duplicate-instance is now explained in Note [Loading your own hi-boot file] in LoadIface. I fixed it by a Gross Hack in LoadIface.loadInterface. This is at least no worse than before. But there should be a better way. I have opened #16081 for this.
* Taming the Kind Inference MonsterSimon Peyton Jones2018-11-291-2/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | My original goal was (Trac #15809) to move towards using level numbers as the basis for deciding which type variables to generalise, rather than searching for the free varaibles of the environment. However it has turned into a truly major refactoring of the kind inference engine. Let's deal with the level-numbers part first: * Augment quantifyTyVars to calculate the type variables to quantify using level numbers, and compare the result with the existing approach. That is; no change in behaviour, just a WARNing if the two approaches give different answers. * To do this I had to get the level number right when calling quantifyTyVars, and this entailed a bit of care, especially in the code for kind-checking type declarations. * However, on the way I was able to eliminate or simplify a number of calls to solveEqualities. This work is incomplete: I'm not /using/ level numbers yet. When I subsequently get rid of any remaining WARNings in quantifyTyVars, that the level-number answers differ from the current answers, then I can rip out the current "free vars of the environment" stuff. Anyway, this led me into deep dive into kind inference for type and class declarations, which is an increasingly soggy part of GHC. Richard already did some good work recently in commit 5e45ad10ffca1ad175b10f6ef3327e1ed8ba25f3 Date: Thu Sep 13 09:56:02 2018 +0200 Finish fix for #14880. The real change that fixes the ticket is described in Note [Naughty quantification candidates] in TcMType. but I kept turning over stones. So this patch has ended up with a pretty significant refactoring of that code too. Kind inference for types and classes ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ * Major refactoring in the way we generalise the inferred kind of a TyCon, in kcTyClGroup. Indeed, I made it into a new top-level function, generaliseTcTyCon. Plus a new Note to explain it Note [Inferring kinds for type declarations]. * We decided (Trac #15592) not to treat class type variables specially when dealing with Inferred/Specified/Required for associated types. That simplifies things quite a bit. I also rewrote Note [Required, Specified, and Inferred for types] * Major refactoring of the crucial function kcLHsQTyVars: I split it into kcLHsQTyVars_Cusk and kcLHsQTyVars_NonCusk because the two are really quite different. The CUSK case is almost entirely rewritten, and is much easier because of our new decision not to treat the class variables specially * I moved all the error checks from tcTyClTyVars (which was a bizarre place for it) into generaliseTcTyCon and/or the CUSK case of kcLHsQTyVars. Now tcTyClTyVars is extremely simple. * I got rid of all the all the subtleties in tcImplicitTKBndrs. Indeed now there is no difference between tcImplicitTKBndrs and kcImplicitTKBndrs; there is now a single bindImplicitTKBndrs. Same for kc/tcExplicitTKBndrs. None of them monkey with level numbers, nor build implication constraints. scopeTyVars is gone entirely, as is kcLHsQTyVarBndrs. It's vastly simpler. I found I could get rid of kcLHsQTyVarBndrs entirely, in favour of the bnew bindExplicitTKBndrs. Quantification ~~~~~~~~~~~~~~ * I now deal with the "naughty quantification candidates" of the previous patch in candidateQTyVars, rather than in quantifyTyVars; see Note [Naughty quantification candidates] in TcMType. I also killed off closeOverKindsCQTvs in favour of the same strategy that we use for tyCoVarsOfType: namely, close over kinds at the occurrences. And candidateQTyVars no longer needs a gbl_tvs argument. * Passing the ContextKind, rather than the expected kind itself, to tc_hs_sig_type_and_gen makes it easy to allocate the expected result kind (when we are in inference mode) at the right level. Type families ~~~~~~~~~~~~~~ * I did a major rewrite of the impenetrable tcFamTyPats. The result is vastly more comprehensible. * I got rid of kcDataDefn entirely, quite a big function. * I re-did the way that checkConsistentFamInst works, so that it allows alpha-renaming of invisible arguments. * The interaction of kind signatures and family instances is tricky. Type families: see Note [Apparently-nullary families] Data families: see Note [Result kind signature for a data family instance] and Note [Eta-reduction for data families] * The consistent instantation of an associated type family is tricky. See Note [Checking consistent instantiation] and Note [Matching in the consistent-instantation check] in TcTyClsDecls. It's now checked in TcTyClsDecls because that is when we have the relevant info to hand. * I got tired of the compromises in etaExpandFamInst, so I did the job properly by adding a field cab_eta_tvs to CoAxBranch. See Coercion.etaExpandCoAxBranch. tcInferApps and friends ~~~~~~~~~~~~~~~~~~~~~~~ * I got rid of the mysterious and horrible ClsInstInfo argument to tcInferApps, checkExpectedKindX, and various checkValid functions. It was horrible! * I got rid of [Type] result of tcInferApps. This list was used only in tcFamTyPats, when checking the LHS of a type instance; and if there is a cast in the middle, the list is meaningless. So I made tcInferApps simpler, and moved the complexity (not much) to tcInferApps. Result: tcInferApps is now pretty comprehensible again. * I refactored the many function in TcMType that instantiate skolems. Smaller things * I rejigged the error message in checkValidTelescope; I think it's quite a bit better now. * checkValidType was not rejecting constraints in a kind signature forall (a :: Eq b => blah). blah2 That led to further errors when we then do an ambiguity check. So I make checkValidType reject it more aggressively. * I killed off quantifyConDecl, instead calling kindGeneralize directly. * I fixed an outright bug in tyCoVarsOfImplic, where we were not colleting the tyvar of the kind of the skolems * Renamed ClsInstInfo to AssocInstInfo, and made it into its own data type * Some fiddling around with pretty-printing of family instances which was trickier than I thought. I wanted wildcards to print as plain "_" in user messages, although they each need a unique identity in the CoAxBranch. Some other oddments * Refactoring around the trace messages from reportUnsolved. * A bit of extra tc-tracing in TcHsSyn.commitFlexi This patch fixes a raft of bugs, and includes tests for them. * #14887 * #15740 * #15764 * #15789 * #15804 * #15817 * #15870 * #15874 * #15881
* Refactor the treatment of predicate typesSimon Peyton Jones2018-10-241-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Trac #15648 showed that GHC was a bit confused about the difference between the types for * Predicates * Coercions * Evidence (in the typechecker constraint solver) This patch cleans it up. See especially Type.hs Note [Types for coercions, predicates, and evidence] Particular changes * Coercion types (a ~# b) and (a ~#R b) are not predicate types (so isPredTy reports False for them) and are not implicitly instantiated by the type checker. This is a real change, but it consistently reflects that fact that (~#) and (~R#) really are different from predicates. * isCoercionType is renamed to isCoVarType * During type inference, simplifyInfer, we do /not/ want to infer a constraint (a ~# b), because that is no longer a predicate type. So we 'lift' it to (a ~ b). See TcType Note [Lift equality constaints when quantifying] * During type inference for pattern synonyms, we need to 'lift' provided constraints of type (a ~# b) to (a ~ b). See Note [Equality evidence in pattern synonyms] in PatSyn * But what about (forall a. Eq a => a ~# b)? Is that a predicate type? No -- it does not have kind Constraint. Is it an evidence type? Perhaps, but awkwardly so. In the end I decided NOT to make it an evidence type, and to ensure the the type inference engine never meets it. This made me /simplify/ the code in TcCanonical.makeSuperClasses; see TcCanonical Note [Equality superclasses in quantified constraints] Instead I moved the special treatment for primitive equality to TcInteract.doTopReactOther. See TcInteract Note [Looking up primitive equalities in quantified constraints] Also see Note [Evidence for quantified constraints] in Type. All this means I can have isEvVarType ty = isCoVarType ty || isPredTy ty which is nice. All in all, rather a lot of work for a small refactoring, but I think it's a real improvement.
* Adding almost devoid check for covar in ForAllCoNingning Xie2018-10-191-1/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | Summary: For the sake of consistency of the dependent core, there is a restriction on where a coercion variable can appear in ForAllCo: the coercion variable can appear nowhere except in coherence coercions. Currently this restriction is missing in Core. The goal of this patch is to add the missing restriction. After discussion, we decide: coercion variables can appear nowhere except in `GRefl` and `Refl`. Relaxing the restriction to include `Refl` should not break consistency, we premuse. Test Plan: ./validate Reviewers: goldfire, simonpj, bgamari Reviewed By: goldfire Subscribers: rwbarton, carter GHC Trac Issues: #15757 Differential Revision: https://phabricator.haskell.org/D5231
* Make Lint check that for CoVars more carefullySimon Peyton Jones2018-10-041-2/+8
| | | | | | Check than an Id of type (t1 ~# t2) is a CoVar; if not, it ends up in the wrong simplifier environment, with strange consequences. (Trac #15648)
* Fix Lint of unsaturated type familiesSimon Peyton Jones2018-09-261-24/+26
| | | | | | | | | | GHC allows types to have unsaturated type synonyms and type families, provided they /are/ saturated if you expand all type synonyms. TcValidity carefully checked this; see check_syn_tc_app. But Lint only did half the job, adn that led to Trac #15664. This patch just teaches Core Lint to be as clever as TcValidity.
* Coercion Quantificationningning2018-09-151-20/+87
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch corresponds to #15497. According to https://ghc.haskell.org/trac/ghc/wiki/DependentHaskell/Phase2, we would like to have coercion quantifications back. This will allow us to migrate (~#) to be homogeneous, instead of its current heterogeneous definition. This patch is (lots of) plumbing only. There should be no user-visible effects. An overview of changes: - Both `ForAllTy` and `ForAllCo` can quantify over coercion variables, but only in *Core*. All relevant functions are updated accordingly. - Small changes that should be irrelevant to the main task: 1. removed dead code `mkTransAppCo` in Coercion 2. removed out-dated Note Computing a coercion kind and roles in Coercion 3. Added `Eq4` in Note Respecting definitional equality in TyCoRep, and updated `mkCastTy` accordingly. 4. Various updates and corrections of notes and typos. - Haddock submodule needs to be changed too. Acknowledgments: This work was completed mostly during Ningning Xie's Google Summer of Code, sponsored by Google. It was advised by Richard Eisenberg, supported by NSF grant 1704041. Test Plan: ./validate Reviewers: goldfire, simonpj, bgamari, hvr, erikd, simonmar Subscribers: RyanGlScott, monoidal, rwbarton, carter GHC Trac Issues: #15497 Differential Revision: https://phabricator.haskell.org/D5054
* Allow (~) in the head of a quantified constraintsSimon Peyton Jones2018-09-131-0/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Since the introduction of quantified constraints, GHC has rejected a quantified constraint with (~) in the head, thus f :: (forall a. blah => a ~ ty) => stuff I am frankly dubious that this is ever useful. But /is/ necessary for Coercible (representation equality version of (~)) and it does no harm to allow it for (~) as well. Plus, our users are asking for it (Trac #15359, #15625). It was really only excluded by accident, so this patch lifts the restriction. See TcCanonical Note [Equality superclasses in quantified constraints] There are a number of wrinkles: * If the context of the quantified constraint is empty, we can get trouble when we get down to unboxed equality (a ~# b) or (a ~R# b), as Trac #15625 showed. This is even more of a corner case, but it produced an outright crash, so I elaborated the superclass machinery in TcCanonical.makeStrictSuperClasses to add a void argument in this case. See Note [Equality superclasses in quantified constraints] * The restriction on (~) was in TcValidity.checkValidInstHead. In lifting the restriction I discovered an old special case for (~), namely | clas_nm `elem` [ heqTyConName, eqTyConName] , nameModule clas_nm /= this_mod This was (solely) to support the strange instance instance a ~~ b => a ~ b in Data.Type.Equality. But happily that is no longer with us, since commit f265008fb6f70830e7e92ce563f6d83833cef071 Refactor (~) to reduce the suerpclass stack So I removed the special case. * I found that the Core invariants on when we could have co = <expr> were entirely not written down. (Getting this wrong ws the proximate source of the crash in Trac #15625. So - Documented them better in CoreSyn Note [CoreSyn type and coercion invariant], - Modified CoreOpt and CoreLint to match - Modified CoreUtils.bindNonRec to match - Made MkCore.mkCoreLet use bindNonRec, rather than duplicate its logic - Made Simplify.rebuildCase case-to-let respect Note [CoreSyn type and coercion invariant],
* Refactor coercion ruleningning2018-07-091-9/+16
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Summary: The patch is an attempt on #15192. It defines a new coercion rule ``` | GRefl Role Type MCoercion ``` which correspondes to the typing rule ``` t1 : k1 ------------------------------------ GRefl r t1 MRefl: t1 ~r t1 t1 : k1 co :: k1 ~ k2 ------------------------------------ GRefl r t1 (MCo co) : t1 ~r t1 |> co ``` MCoercion wraps a coercion, which might be reflexive (MRefl) or not (MCo co). To know more about MCoercion see #14975. We keep Refl ty as a special case for nominal reflexive coercions, naemly, Refl ty :: ty ~n ty. This commit is meant to be a general performance improvement, but there are a few regressions. See #15192, comment:13 for more information. Test Plan: ./validate Reviewers: bgamari, goldfire, simonpj Subscribers: rwbarton, thomie, carter GHC Trac Issues: #15192 Differential Revision: https://phabricator.haskell.org/D4747
* Simplify lintIdUnfoldingMatthew Pickering2018-07-061-10/+3
| | | | | | | | | | | | | | The logic for `DFunUnfolding` seemed quite confusing and unecessary. A simpler strategy uses `maybeUnfoldingTemplate`, as that is what is actually used when doing inlining and checking that has the right type. Reviewers: simonpj, goldfire, bgamari Reviewed By: bgamari Subscribers: rwbarton, thomie, carter Differential Revision: https://phabricator.haskell.org/D4919
* Make a variant of mkCastErr for kind coercionsRyan Scott2018-07-061-7/+25
| | | | | | | | | | | | | | | | | | | Summary: I discovered when debugging #15346 that the Core Lint error message for ill typed casts always mentions types of enclosed //expressions//, even if the thing being casted is actually a type. This generalizes `mkCastErr` a bit to allow it to give the proper labelling for kind coercions. Test Plan: Run on failing program in #15346, read the Core Lint error Reviewers: goldfire, bgamari, simonpj Reviewed By: simonpj Subscribers: simonpj, rwbarton, thomie, carter Differential Revision: https://phabricator.haskell.org/D4940
* Typofixes in docs and comments [ci skip]Gabor Greif2018-06-181-1/+1
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* Fix corner case in typeKind, plus refactoringSimon Peyton Jones2018-06-151-21/+16
| | | | | | | | | | | | | | | | | | | | | | | | | | | This is a continuation of commit 9d600ea68c283b0d38ac663c3cc48baba6b94f57 Author: Simon Peyton Jones <simonpj@microsoft.com> Date: Fri Jun 1 16:36:57 2018 +0100 Expand type synonyms when Linting a forall That patch pointed out that there was a lurking hole in typeKind, where it could return an ill-scoped kind, because of not expanding type synonyms enough. This patch fixes it, quite nicely * Use occCheckExpand to expand those synonyms (it was always designed for that exact purpose), and call it from Type.typeKind CoreUtils.coreAltType CoreLint.lintTYpe * Consequently, move occCheckExpand from TcUnify.hs to Type.hs, and generalise it to take a list of type variables. I also tidied up lintType a bit.
* Expand type synonyms when Linting a forallSimon Peyton Jones2018-06-041-7/+30
| | | | | | | | | | | | | | | Trac #14939 showed a type like type Alg cls ob = ob f :: forall (cls :: * -> Constraint) (b :: Alg cls *). b where the kind of the forall looks like (Alg cls *), with a free cls. This tripped up Core Lint. I fixed this by making Core Lint a bit more forgiving, expanding type synonyms if necessary. I'm worried that this might not be the whole story; notably typeKind looks suspect. But it certainly fixes this problem.
* vectorise: Put it out of its miseryBen Gamari2018-06-021-1/+0
| | | | | | | | | | | | | | | | | | | | | Poor DPH and its vectoriser have long been languishing; sadly it seems there is little chance that the effort will be rekindled. Every few years we discuss what to do with this mass of code and at least once we have agreed that it should be archived on a branch and removed from `master`. Here we do just that, eliminating heaps of dead code in the process. Here we drop the ParallelArrays extension, the vectoriser, and the `vector` and `primitive` submodules. Test Plan: Validate Reviewers: simonpj, simonmar, hvr, goldfire, alanz Reviewed By: simonmar Subscribers: goldfire, rwbarton, thomie, mpickering, carter Differential Revision: https://phabricator.haskell.org/D4761
* Better linting for typesSimon Peyton Jones2018-04-271-72/+97
| | | | | | | | | | Trac #15057 described deficiencies in the linting for types involving type synonyms. This patch fixes an earlier attempt. The moving parts are desrcribed in Note [Linting type synonym applications] Not a big deal.
* Caching coercion roles in NthCo and coercionKindsRole refactoringTobias Dammers2018-04-201-3/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | While addressing nonlinear behavior related to coercion roles, particularly `NthCo`, we noticed that coercion roles are recalculated often even though they should be readily at hand already in most cases. This patch adds a `Role` to the `NthCo` constructor so that we can cache them rather than having to recalculate them on the fly. https://ghc.haskell.org/trac/ghc/ticket/11735#comment:23 explains the approach. Performance improvement over GHC HEAD, when compiling Grammar.hs (see below): GHC 8.2.1: ``` ghc Grammar.hs 176.27s user 0.23s system 99% cpu 2:56.81 total ``` before patch (but with other optimizations applied): ``` ghc Grammar.hs -fforce-recomp 175.77s user 0.19s system 100% cpu 2:55.78 total ``` after: ``` ../../ghc/inplace/bin/ghc-stage2 Grammar.hs 10.32s user 0.17s system 98% cpu 10.678 total ``` Introduces the following regressions: - perf/compiler/parsing001 (possibly false positive) - perf/compiler/T9872 - perf/compiler/haddock.base Reviewers: goldfire, bgamari, simonpj Reviewed By: simonpj Subscribers: rwbarton, thomie, carter GHC Trac Issues: #11735 Differential Revision: https://phabricator.haskell.org/D4394
* Lint types in newFamInstRyan Scott2018-04-191-29/+83
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | We weren't linting the types used in `newFamInst`, which might have been why #15012 went undiscovered for so long. Let's fix that. One has to be surprisingly careful with expanding type synonyms in `lintType`, since in the offending program (simplified): ```lang=haskell type FakeOut a = Int type family TF a type instance TF Int = FakeOut a ``` If one expands type synonyms, then `FakeOut a` will expand to `Int`, which masks the issue (that `a` is unbound). I added an extra Lint flag to configure whether type synonyms should be expanded or not in Lint, and disabled this when calling `lintTypes` from `newFamInst`. As evidence that this works, I ran it on the offending program from #15012, and voilà: ``` $ ghc3/inplace/bin/ghc-stage2 Bug.hs -dcore-lint [1 of 1] Compiling Foo ( Bug.hs, Bug.o ) ghc-stage2: panic! (the 'impossible' happened) (GHC version 8.5.20180417 for x86_64-unknown-linux): Core Lint error <no location info>: warning: In the type ‘... (Rec0 (FakeOut b_a1Qt))))’ @ b_a1Qt is out of scope ``` Test Plan: make test TEST=T15057 Reviewers: simonpj, goldfire, bgamari Reviewed By: bgamari Subscribers: thomie, carter GHC Trac Issues: #15057 Differential Revision: https://phabricator.haskell.org/D4611
* Allow top level ticked string literalsBartosz Nitka2018-03-061-3/+3
| | | | | | | | | | | | | | | | | | | | This reverts f5b275a239d2554c4da0b7621211642bf3b10650 and changes the places that looked for `Lit (MachStr _))` to use `exprIsMbTickedLitString_maybe` to unwrap ticks as necessary. Also updated relevant comments. Test Plan: I added 3 new tests that previously reproduced. GHC HEAD now builds with -g Reviewers: simonpj, simonmar, bgamari, hvr, goldfire Subscribers: rwbarton, thomie, carter GHC Trac Issues: #14779 Differential Revision: https://phabricator.haskell.org/D4470
* Tiny refactor in Core LintSimon Peyton Jones2018-02-271-2/+3
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* Fix utterly bogus TagToEnum rule in caseRulesSimon Peyton Jones2018-02-071-1/+1
| | | | | | | | | | | | | | | | In prelRules we had: tx_con_tte :: DynFlags -> AltCon -> AltCon tx_con_tte _ DEFAULT = DEFAULT tx_con_tte dflags (DataAlt dc) | tag == 0 = DEFAULT -- See Note [caseRules for tagToEnum] | otherwise = LitAlt (mkMachInt dflags (toInteger tag)) The tag==0 case is totally wrong, and led directly to Trac #14768. See "Beware" in Note [caseRules for tagToEnum] (in the patch). Easily fixed, though!
* Add -ddump-ds-preoptSimon Peyton Jones2018-02-011-1/+1
| | | | | | | | | | | | | This allows you to see the output immediately after desugaring but before any optimisation. I've wanted this for some time, but I was triggered into action by Trac #13032 comment:9. Interestingly, the change means that with -dcore-lint we will now Lint the output before the very simple optimiser; and this showed up Trac #14749. But that's not the fault of -ddump-ds-preopt!
* CoreLint: typo in a commentÖmer Sinan Ağacan2018-01-151-2/+2
| | | | | | | | | | Reviewers: bgamari, goldfire Reviewed By: bgamari Subscribers: rwbarton, thomie, carter Differential Revision: https://phabricator.haskell.org/D4308
* Refactor coercion holesSimon Peyton Jones2017-12-211-2/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In fixing Trac #14584 I found that it would be /much/ more convenient if a "hole" in a coercion (much like a unification variable in a type) acutally had a CoVar associated with it rather than just a Unique. Then I can ask what the free variables of a coercion is, and get a set of CoVars including those as-yet-un-filled in holes. Once that is done, it makes no sense to stuff coercion holes inside UnivCo. They were there before so we could know the kind and role of a "hole" coercion, but once there is a CoVar we can get that info from the CoVar. So I removed HoleProv from UnivCoProvenance and added HoleCo to Coercion. In summary: * Add HoleCo to Coercion and remove HoleProv from UnivCoProvanance * Similarly in IfaceCoercion * Make CoercionHole have a CoVar in it, not a Unique * Make tyCoVarsOfCo return the free coercion-hole variables as well as the ordinary free CoVars. Similarly, remember to zonk the CoVar in a CoercionHole We could go further, and remove CoercionHole as a distinct type altogther, just collapsing it into HoleCo. But I have not done that yet.
* Remove unreliable Core Lint empty case checksDavid Feuer2017-11-091-19/+38
| | | | | | | | | | | | | | | | | | | Trac #13990 shows that the Core Lint checks for empty case are unreliable, and very hard to make reliable. The consensus (among simonpj, nomeata, and goldfire) seems to be that they should be removed altogether. Do that. Add test Reviewers: goldfire, bgamari Reviewed By: bgamari Subscribers: rwbarton, thomie GHC Trac Issues: #13990 Differential Revision: https://phabricator.haskell.org/D4161
* Invoke lintUnfolding only on top-level unfoldings (#14430)Joachim Breitner2017-11-081-2/+10
| | | | | | | | | | | | as nested unfoldings are linted together with the top-level unfolding, and lintUnfolding does the wrong things for nestd unfoldings that mention join points. The easiest way of doing that was to pass a TopLevel flag through `tcUnfolding`, which is invoked both for top level and nested unfoldings. Differential Revision: https://phabricator.haskell.org/D4169
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