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* Don't return preload units when we set DyNFlagsSylvain Henry2020-06-137-23/+26
| | | | Preload units can be retrieved in UnitState when needed (i.e. in GHCi)
* Put database cache in UnitConfigSylvain Henry2020-06-131-43/+34
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* Create helper upd_wired_in_home_instantiationsSylvain Henry2020-06-131-9/+17
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* Move distrustAll into mkUnitStateSylvain Henry2020-06-131-13/+12
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* DynFlags: add UnitConfig datatypeSylvain Henry2020-06-133-120/+182
| | | | | | Avoid directly querying flags from DynFlags to build the UnitState. Instead go via UnitConfig so that we could reuse this to make another UnitState for plugins.
* DynFlags: merge_databasesSylvain Henry2020-06-131-9/+11
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* DynFlags: reportCycles, reportUnusableSylvain Henry2020-06-131-8/+8
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* DynFlags: findWiredInUnitsSylvain Henry2020-06-131-6/+6
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* Refactor and document closeUnitDepsSylvain Henry2020-06-131-30/+26
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* Refactor and document add_packageSylvain Henry2020-06-131-25/+26
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* DynFlags: make listVisibleModuleNames take a UnitStateSylvain Henry2020-06-133-6/+8
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* DynFlags: remove useless add_package parameterSylvain Henry2020-06-131-9/+7
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* Document getPreloadUnitsAndSylvain Henry2020-06-131-4/+5
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* DynFlags: refactor unwireUnitSylvain Henry2020-06-133-11/+12
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* Remove preload parameter of mkUnitStateSylvain Henry2020-06-131-12/+8
| | | | | | * Remove preload parameter (unused) * Don't explicitly return preloaded units: redundant because already returned as "preloadUnits" field of UnitState
* Avoid timing module map dump in initUnitsSylvain Henry2020-06-131-18/+24
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* Move wiring of homeUnitInstantiations outside of mkUnitStateSylvain Henry2020-06-131-8/+16
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* Move dump_mod_map into initUnitsSylvain Henry2020-06-131-8/+8
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* Rename Package into Unit (2)Sylvain Henry2020-06-1316-118/+118
| | | | | | | * rename PackageState into UnitState * rename findWiredInPackages into findWiredInUnits * rename lookupModuleInAll[Packages,Units] * etc.
* Remove ClosureUnitInfoMapSylvain Henry2020-06-138-185/+168
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* Make ClosureUnitInfoMap uses UnitInfoMapSylvain Henry2020-06-132-18/+37
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* Rename Package into UnitSylvain Henry2020-06-1325-267/+262
| | | | | | | | | | | | | | | | | | | | | | | | | The terminology changed over time and now package databases contain "units" (there can be several units compiled from a single Cabal package: one per-component, one for each option set, one per instantiation, etc.). We should try to be consistent internally and use "units": that's what this renaming does. Maybe one day we'll fix the UI too (e.g. replace -package-id with -unit-id, we already have -this-unit-id and ghc-pkg has -unit-id...) but it's not done in this patch. * rename getPkgFrameworkOpts into getUnitFrameworkOpts * rename UnitInfoMap into ClosureUnitInfoMap * rename InstalledPackageIndex into UnitInfoMap * rename UnusablePackages into UnusableUnits * rename PackagePrecedenceIndex into UnitPrecedenceMap * rename PackageDatabase into UnitDatabase * rename pkgDatabase into unitDatabases * rename pkgState into unitState * rename initPackages into initUnits * rename renamePackage into renameUnitInfo * rename UnusablePackageReason into UnusableUnitReason * rename getPackage* into getUnit* * etc.
* Rename listUnitInfoMap into listUnitInfoSylvain Henry2020-06-131-5/+5
| | | | There is no Map involved
* Remove PreloadUnitId type aliasSylvain Henry2020-06-131-17/+15
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* Document and refactor `mkUnit` and `mkUnitInfoMap`Sylvain Henry2020-06-132-15/+31
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* Refactor WiredMapSylvain Henry2020-06-132-48/+33
| | | | * Remove WiredInUnitId and WiredUnitId type aliases
* Remove LinkerUnitId type aliasSylvain Henry2020-06-132-9/+5
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* Enhance UnitId useSylvain Henry2020-06-1329-133/+156
| | | | | | | | * use UnitId instead of String to identify wired-in units * use UnitId instead of Unit in the backend (Unit are only use by Backpack to produce type-checked interfaces, not real code) * rename lookup functions for consistency * documentation
* Add allowVirtualUnits field in PackageStateSylvain Henry2020-06-1311-73/+90
| | | | | | | | | | Instead of always querying DynFlags to know whether we are allowed to use virtual units (i.e. instantiated on-the-fly, cf Note [About units] in GHC.Unit), we store it once for all in `PackageState.allowVirtualUnits`. This avoids using DynFlags too much (cf #17957) and is preliminary work for #14335.
* Rename unsafeGetUnitInfo into unsafeLookupUnitSylvain Henry2020-06-136-11/+11
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* Refactor homeUnitSylvain Henry2020-06-1330-161/+165
| | | | | * rename thisPackage into homeUnit * document and refactor several Backpack things
* Remove unused codeSylvain Henry2020-06-131-23/+0
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* DynFlags refactoring VIII (#17957)Sylvain Henry2020-06-1310-322/+356
| | | | | | | | | | | * Remove several uses of `sdocWithDynFlags`, especially in GHC.Llvm.* * Add LlvmOpts datatype to store Llvm backend options * Remove Outputable instances (for LlvmVar, LlvmLit, LlvmStatic and Llvm.MetaExpr) which require LlvmOpts. * Rename ppMetaExpr into ppMetaAnnotExpr (pprMetaExpr is now used in place of `ppr :: MetaExpr -> SDoc`)
* Only test T16190 with the NCGSylvain Henry2020-06-131-1/+4
| | | | | T16190 is meant to test a NCG feature. It has already caused spurious failures in other MRs (e.g. !2165) when LLVM is used.
* Release Notes: Add news from the pattern-match checker [skip ci]wip/pmcheck-release-notes-8.12Sebastian Graf2020-06-111-0/+13
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* test: fix conc038Sylvain Henry2020-06-102-3/+3
| | | | | | | | | | | | | | | | We had spurious failures of conc038 test on CI with stdout: ``` newThread started -mainThread -Haskell: 2 newThread back again +mainThread 1 sec later shutting down +Haskell: 2 ```
* Initialize the allocation counter in GHCi to 0 (Fixes #16012)Roland Senn2020-06-104-2/+6
| | | | | | According to the documentation for the function `getAllocationCounter` in [System.Mem](http://hackage.haskell.org/package/base-4.14.0.0/docs/System-Mem.html) initialize the allocationCounter also in GHCi to 0.
* Fix lookupGlobalOccRn_maybe sometimes reporting an errorLuke Lau2020-06-106-62/+136
| | | | | | | | | | | | | | | | | In some cases it was possible for lookupGlobalOccRn_maybe to return an error, when it should be returning a Nothing. If it called lookupExactOcc_either when there were no matching GlobalRdrElts in the otherwise case, it would return an error message. This could be caused when lookupThName_maybe in Template Haskell was looking in different namespaces (thRdrNameGuesses), guessing different namespaces that the name wasn't guaranteed to be found in. However, by addressing this some more accurate errors were being lost in the conversion to Maybes. So some of the lookup* functions have been shuffled about so that errors should always be ignored in lookup*_maybes, and propagated otherwise. This fixes #18263
* Implement cast worker/wrapper properlySimon Peyton Jones2020-06-1032-416/+910
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The cast worker/wrapper transformation transforms x = e |> co into y = e x = y |> co This is done by the simplifier, but we were being careless about transferring IdInfo from x to y, and about what to do if x is a NOINLNE function. This resulted in a series of bugs: #17673, #18093, #18078. This patch fixes all that: * Main change is in GHC.Core.Opt.Simplify, and the new prepareBinding function, which does this cast worker/wrapper transform. See Note [Cast worker/wrappers]. * There is quite a bit of refactoring around prepareRhs, makeTrivial etc. It's nicer now. * Some wrappers from strictness and cast w/w, notably those for a function with a NOINLINE, should inline very late. There wasn't really a mechanism for that, which was an existing bug really; so I invented a new finalPhase = Phase (-1). It's used for all simplifier runs after the user-visible phase 2,1,0 have run. (No new runs of the simplifier are introduced thereby.) See new Note [Compiler phases] in GHC.Types.Basic; the main changes are in GHC.Core.Opt.Driver * Doing this made me trip over two places where the AnonArgFlag on a FunTy was being lost so we could end up with (Num a -> ty) rather than (Num a => ty) - In coercionLKind/coercionRKind - In contHoleType in the Simplifier I fixed the former by defining mkFunctionType and using it in coercionLKind/RKind. I could have done the same for the latter, but the information is almost to hand. So I fixed the latter by - adding sc_hole_ty to ApplyToVal (like ApplyToTy), - adding as_hole_ty to ValArg (like TyArg) - adding sc_fun_ty to StrictArg Turned out I could then remove ai_type from ArgInfo. This is just moving the deck chairs around, but it worked out nicely. See the new Note [AnonArgFlag] in GHC.Types.Var * When looking at the 'arity decrease' thing (#18093) I discovered that stable unfoldings had a much lower arity than the actual optimised function. That's what led to the arity-decrease message. Simple solution: eta-expand. It's described in Note [Eta-expand stable unfoldings] in GHC.Core.Opt.Simplify * I also discovered that unsafeCoerce wasn't being inlined if the context was boring. So (\x. f (unsafeCoerce x)) would create a thunk -- yikes! I fixed that by making inlineBoringOK a bit cleverer: see Note [Inline unsafeCoerce] in GHC.Core.Unfold. I also found that unsafeCoerceName was unused, so I removed it. I made a test case for #18078, and a very similar one for #17673. The net effect of all this on nofib is very modest, but positive: -------------------------------------------------------------------------------- Program Size Allocs Runtime Elapsed TotalMem -------------------------------------------------------------------------------- anna -0.4% -0.1% -3.1% -3.1% 0.0% fannkuch-redux -0.4% -0.3% -0.1% -0.1% 0.0% maillist -0.4% -0.1% -7.8% -1.0% -14.3% primetest -0.4% -15.6% -7.1% -6.6% 0.0% -------------------------------------------------------------------------------- Min -0.9% -15.6% -13.3% -14.2% -14.3% Max -0.3% 0.0% +12.1% +12.4% 0.0% Geometric Mean -0.4% -0.2% -2.3% -2.2% -0.1% All following metric decreases are compile-time allocation decreases between -1% and -3%: Metric Decrease: T5631 T13701 T14697 T15164
* Optimisation in Unique.SupplySimon Peyton Jones2020-06-101-25/+120
| | | | | | | | | | | | | | | | | | | | | | | This patch switches on -fno-state-hack in GHC.Types.Unique.Supply. It turned out that my fixes for #18078 (coercion floating) changed the optimisation pathway for mkSplitUniqSupply in such a way that we had an extra allocation inside the inner loop. Adding -fno-state-hack fixed that -- and indeed the loop in mkSplitUniqSupply is a classic example of the way in which -fno-state-hack can be bad; see #18238. Moreover, the new code is better than the old. They allocate the same, but the old code ends up with a partial application. The net effect is that the test perf/should_run/UniqLoop runs 20% faster! From 2.5s down to 2.0s. The allocation numbers are the same -- but elapsed time falls. Good! The bad thing about this is that it's terribly delicate. But at least it's a good example of such delicacy in action. There is a long Note [Optimising the unique supply] which now explains all this.
* Give Language a Bounded instanceShayne Fletcher2020-06-101-2/+1
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* Cross-module LambdaFormInfo passingÖmer Sinan Ağacan2020-06-1028-190/+580
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | - Store LambdaFormInfos of exported Ids in interface files - Use them in importing modules This is for optimization purposes: if we know LambdaFormInfo of imported Ids we can generate more efficient calling code, see `getCallMethod`. Exporting (putting them in interface files or in ModDetails) and importing (reading them from interface files) are both optional. We don't assume known LambdaFormInfos anywhere and do not change how we call Ids with unknown LambdaFormInfos. Runtime, allocation, and residency numbers when building Cabal-the-library (commit 0d4ee7ba3): (Log and .hp files are in the MR: !2842) | | GHC HEAD | This patch | Diff | |-----|----------|------------|----------------| | -O0 | 0:35.89 | 0:34.10 | -1.78s, -4.98% | | -O1 | 2:24.01 | 2:23.62 | -0.39s, -0.27% | | -O2 | 2:52.23 | 2:51.35 | -0.88s, -0.51% | | | GHC HEAD | This patch | Diff | |-----|-----------------|-----------------|----------------------------| | -O0 | 54,843,608,416 | 54,878,769,544 | +35,161,128 bytes, +0.06% | | -O1 | 227,136,076,400 | 227,569,045,168 | +432,968,768 bytes, +0.19% | | -O2 | 266,147,063,296 | 266,749,643,440 | +602,580,144 bytes, +0.22% | NOTE: Residency is measured with extra runtime args: `-i0 -h` which effectively turn all GCs into major GCs, and do GC more often. | | GHC HEAD | This patch | Diff | |-----|----------------------------|------------------------------|----------------------------| | -O0 | 410,284,000 (910 samples) | 411,745,008 (906 samples) | +1,461,008 bytes, +0.35% | | -O1 | 928,580,856 (2109 samples) | 943,506,552 (2103 samples) | +14,925,696 bytes, +1.60% | | -O2 | 993,951,352 (2549 samples) | 1,010,156,328 (2545 samples) | +16,204,9760 bytes, +1.63% | NoFib results: -------------------------------------------------------------------------------- Program Size Allocs Instrs Reads Writes -------------------------------------------------------------------------------- CS 0.0% 0.0% +0.0% +0.0% +0.0% CSD 0.0% 0.0% 0.0% +0.0% +0.0% FS 0.0% 0.0% +0.0% +0.0% +0.0% S 0.0% 0.0% +0.0% +0.0% +0.0% VS 0.0% 0.0% +0.0% +0.0% +0.0% VSD 0.0% 0.0% +0.0% +0.0% +0.1% VSM 0.0% 0.0% +0.0% +0.0% +0.0% anna 0.0% 0.0% -0.3% -0.8% -0.0% ansi 0.0% 0.0% -0.0% -0.0% 0.0% atom 0.0% 0.0% -0.0% -0.0% 0.0% awards 0.0% 0.0% -0.1% -0.3% 0.0% banner 0.0% 0.0% -0.0% -0.0% -0.0% bernouilli 0.0% 0.0% -0.0% -0.0% -0.0% binary-trees 0.0% 0.0% -0.0% -0.0% +0.0% boyer 0.0% 0.0% -0.0% -0.0% 0.0% boyer2 0.0% 0.0% -0.0% -0.0% 0.0% bspt 0.0% 0.0% -0.0% -0.2% 0.0% cacheprof 0.0% 0.0% -0.1% -0.4% +0.0% calendar 0.0% 0.0% -0.0% -0.0% 0.0% cichelli 0.0% 0.0% -0.9% -2.4% 0.0% circsim 0.0% 0.0% -0.0% -0.0% 0.0% clausify 0.0% 0.0% -0.1% -0.3% 0.0% comp_lab_zift 0.0% 0.0% -0.0% -0.0% +0.0% compress 0.0% 0.0% -0.0% -0.0% -0.0% compress2 0.0% 0.0% -0.0% -0.0% 0.0% constraints 0.0% 0.0% -0.1% -0.2% -0.0% cryptarithm1 0.0% 0.0% -0.0% -0.0% 0.0% cryptarithm2 0.0% 0.0% -1.4% -4.1% -0.0% cse 0.0% 0.0% -0.0% -0.0% -0.0% digits-of-e1 0.0% 0.0% -0.0% -0.0% -0.0% digits-of-e2 0.0% 0.0% -0.0% -0.0% -0.0% dom-lt 0.0% 0.0% -0.1% -0.2% 0.0% eliza 0.0% 0.0% -0.5% -1.5% 0.0% event 0.0% 0.0% -0.0% -0.0% -0.0% exact-reals 0.0% 0.0% -0.1% -0.3% +0.0% exp3_8 0.0% 0.0% -0.0% -0.0% -0.0% expert 0.0% 0.0% -0.3% -1.0% -0.0% fannkuch-redux 0.0% 0.0% +0.0% +0.0% +0.0% fasta 0.0% 0.0% -0.0% -0.0% +0.0% fem 0.0% 0.0% -0.0% -0.0% 0.0% fft 0.0% 0.0% -0.0% -0.0% 0.0% fft2 0.0% 0.0% -0.0% -0.0% 0.0% fibheaps 0.0% 0.0% -0.0% -0.0% +0.0% fish 0.0% 0.0% 0.0% -0.0% +0.0% fluid 0.0% 0.0% -0.4% -1.2% +0.0% fulsom 0.0% 0.0% -0.0% -0.0% 0.0% gamteb 0.0% 0.0% -0.1% -0.3% 0.0% gcd 0.0% 0.0% -0.0% -0.0% 0.0% gen_regexps 0.0% 0.0% -0.0% -0.0% -0.0% genfft 0.0% 0.0% -0.0% -0.0% 0.0% gg 0.0% 0.0% -0.0% -0.0% +0.0% grep 0.0% 0.0% -0.0% -0.0% -0.0% hidden 0.0% 0.0% -0.1% -0.4% -0.0% hpg 0.0% 0.0% -0.2% -0.5% +0.0% ida 0.0% 0.0% -0.0% -0.0% +0.0% infer 0.0% 0.0% -0.3% -0.8% -0.0% integer 0.0% 0.0% -0.0% -0.0% +0.0% integrate 0.0% 0.0% -0.0% -0.0% 0.0% k-nucleotide 0.0% 0.0% -0.0% -0.0% +0.0% kahan 0.0% 0.0% -0.0% -0.0% +0.0% knights 0.0% 0.0% -2.2% -5.4% 0.0% lambda 0.0% 0.0% -0.6% -1.8% 0.0% last-piece 0.0% 0.0% -0.0% -0.0% 0.0% lcss 0.0% 0.0% -0.0% -0.1% 0.0% life 0.0% 0.0% -0.0% -0.1% 0.0% lift 0.0% 0.0% -0.2% -0.6% +0.0% linear 0.0% 0.0% -0.0% -0.0% -0.0% listcompr 0.0% 0.0% -0.0% -0.0% 0.0% listcopy 0.0% 0.0% -0.0% -0.0% 0.0% maillist 0.0% 0.0% -0.1% -0.3% +0.0% mandel 0.0% 0.0% -0.0% -0.0% 0.0% mandel2 0.0% 0.0% -0.0% -0.0% -0.0% mate +0.0% 0.0% -0.0% -0.0% -0.0% minimax 0.0% 0.0% -0.2% -1.0% 0.0% mkhprog 0.0% 0.0% -0.1% -0.2% -0.0% multiplier 0.0% 0.0% -0.0% -0.0% -0.0% n-body 0.0% 0.0% -0.0% -0.0% +0.0% nucleic2 0.0% 0.0% -0.1% -0.2% 0.0% para 0.0% 0.0% -0.0% -0.0% -0.0% paraffins 0.0% 0.0% -0.0% -0.0% 0.0% parser 0.0% 0.0% -0.2% -0.7% 0.0% parstof 0.0% 0.0% -0.0% -0.0% +0.0% pic 0.0% 0.0% -0.0% -0.0% 0.0% pidigits 0.0% 0.0% +0.0% +0.0% +0.0% power 0.0% 0.0% -0.2% -0.6% +0.0% pretty 0.0% 0.0% -0.0% -0.0% -0.0% primes 0.0% 0.0% -0.0% -0.0% 0.0% primetest 0.0% 0.0% -0.0% -0.0% -0.0% prolog 0.0% 0.0% -0.3% -1.1% 0.0% puzzle 0.0% 0.0% -0.0% -0.0% 0.0% queens 0.0% 0.0% -0.0% -0.0% +0.0% reptile 0.0% 0.0% -0.0% -0.0% 0.0% reverse-complem 0.0% 0.0% -0.0% -0.0% +0.0% rewrite 0.0% 0.0% -0.7% -2.5% -0.0% rfib 0.0% 0.0% -0.0% -0.0% 0.0% rsa 0.0% 0.0% -0.0% -0.0% 0.0% scc 0.0% 0.0% -0.1% -0.2% -0.0% sched 0.0% 0.0% -0.0% -0.0% -0.0% scs 0.0% 0.0% -1.0% -2.6% +0.0% simple 0.0% 0.0% +0.0% -0.0% +0.0% solid 0.0% 0.0% -0.0% -0.0% 0.0% sorting 0.0% 0.0% -0.6% -1.6% 0.0% spectral-norm 0.0% 0.0% +0.0% 0.0% +0.0% sphere 0.0% 0.0% -0.0% -0.0% -0.0% symalg 0.0% 0.0% -0.0% -0.0% +0.0% tak 0.0% 0.0% -0.0% -0.0% 0.0% transform 0.0% 0.0% -0.0% -0.0% 0.0% treejoin 0.0% 0.0% -0.0% -0.0% 0.0% typecheck 0.0% 0.0% -0.0% -0.0% +0.0% veritas +0.0% 0.0% -0.2% -0.4% +0.0% wang 0.0% 0.0% -0.0% -0.0% 0.0% wave4main 0.0% 0.0% -0.0% -0.0% -0.0% wheel-sieve1 0.0% 0.0% -0.0% -0.0% -0.0% wheel-sieve2 0.0% 0.0% -0.0% -0.0% +0.0% x2n1 0.0% 0.0% -0.0% -0.0% -0.0% -------------------------------------------------------------------------------- Min 0.0% 0.0% -2.2% -5.4% -0.0% Max +0.0% 0.0% +0.0% +0.0% +0.1% Geometric Mean -0.0% -0.0% -0.1% -0.3% +0.0% Metric increases micro benchmarks tracked in #17686: Metric Increase: T12150 T12234 T12425 T13035 T5837 T6048 T9233 Co-authored-by: Andreas Klebinger <klebinger.andreas@gmx.at>
* Expose impliedGFlags, impledOffGFlags, impliedXFlagsShayne Fletcher2020-06-101-0/+7
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* Fix -fkeep-cafs flag name in users guideÖmer Sinan Ağacan2020-06-102-2/+1
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* rts: Remove unused GET_ENTRY closure macroÖmer Sinan Ağacan2020-06-101-2/+0
| | | | | This macro is not used and got broken in the meantime, as ENTRY_CODE was deleted.
* Clarify leaf module names for new module hierarchyTakenobu Tani2020-06-1080-131/+131
| | | | | | | | | | | | | | | | | | | | | This updates comments only. This patch replaces leaf module names according to new module hierarchy [1][2] as followings: * Expand leaf names to easily find the module path: for instance, `Id.hs` to `GHC.Types.Id`. * Modify leaf names according to new module hierarchy: for instance, `Convert.hs` to `GHC.ThToHs`. * Fix typo: for instance, `GHC.Core.TyCo.Rep.hs` to `GHC.Core.TyCo.Rep` See also !3375 [1]: https://gitlab.haskell.org/ghc/ghc/-/wikis/Make-GHC-codebase-more-modular [2]: https://gitlab.haskell.org/ghc/ghc/issues/13009
* Always use rnImplicitBndrs to bring implicit tyvars into scopeRyan Scott2020-06-1020-194/+230
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This implements a first step towards #16762 by changing the renamer to always use `rnImplicitBndrs` to bring implicitly bound type variables into scope. The main change is in `rnFamInstEqn` and `bindHsQTyVars`, which previously used _ad hoc_ methods of binding their implicit tyvars. There are a number of knock-on consequences: * One of the reasons that `rnFamInstEqn` used an _ad hoc_ binding mechanism was to give more precise source locations in `-Wunused-type-patterns` warnings. (See https://gitlab.haskell.org/ghc/ghc/issues/16762#note_273343 for an example of this.) However, these warnings are actually a little _too_ precise, since implicitly bound type variables don't have exact binding sites like explicitly bound type variables do. A similar problem existed for "`Different names for the same type variable`" errors involving implicit tyvars bound by `bindHsQTyVars`. Therefore, we simply accept the less precise (but more accurate) source locations from `rnImplicitBndrs` in `rnFamInstEqn` and `bindHsQTyVars`. See `Note [Source locations for implicitly bound type variables]` in `GHC.Rename.HsType` for the full story. * In order for `rnImplicitBndrs` to work in `rnFamInstEqn`, it needs to be able to look up names from the parent class (in the event that we are renaming an associated type family instance). As a result, `rnImplicitBndrs` now takes an argument of type `Maybe assoc`, which is `Just` in the event that a type family instance is associated with a class. * Previously, GHC kept track of three type synonyms for free type variables in the renamer: `FreeKiTyVars`, `FreeKiTyVarsDups` (which are allowed to contain duplicates), and `FreeKiTyVarsNoDups` (which contain no duplicates). However, making is a distinction between `-Dups` and `-NoDups` is now pointless, as all code that returns `FreeKiTyVars{,Dups,NoDups}` will eventually end up being passed to `rnImplicitBndrs`, which removes duplicates. As a result, I decided to just get rid of `FreeKiTyVarsDups` and `FreeKiTyVarsNoDups`, leaving only `FreeKiTyVars`. * The `bindLRdrNames` and `deleteBys` functions are now dead code, so I took the liberty of removing them.
* Make GADT constructors adhere to the forall-or-nothing rule properlyRyan Scott2020-06-0926-297/+713
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Issue #18191 revealed that the types of GADT constructors don't quite adhere to the `forall`-or-nothing rule. This patch serves to clean up this sad state of affairs somewhat. The main change is not in the code itself, but in the documentation, as this patch introduces two sections to the GHC User's Guide: * A "Formal syntax for GADTs" section that presents a BNF-style grammar for what is and isn't allowed in GADT constructor types. This mostly exists to codify GHC's existing behavior, but it also imposes a new restriction that addresses #18191: the outermost `forall` and/or context in a GADT constructor is not allowed to be surrounded by parentheses. Doing so would make these `forall`s/contexts nested, and GADTs do not support nested `forall`s/contexts at present. * A "`forall`-or-nothing rule" section that describes exactly what the `forall`-or-nothing rule is all about. Surprisingly, there was no mention of this anywhere in the User's Guide up until now! To adhere the new specification in the "Formal syntax for GADTs" section of the User's Guide, the following code changes were made: * A new function, `GHC.Hs.Type.splitLHsGADTPrefixTy`, was introduced. This is very much like `splitLHsSigmaTy`, except that it avoids splitting apart any parentheses, which can be syntactically significant for GADT types. See `Note [No nested foralls or contexts in GADT constructors]` in `GHC.Hs.Type`. * `ConDeclGADTPrefixPs`, an extension constructor for `XConDecl`, was introduced so that `GHC.Parser.PostProcess.mkGadtDecl` can return it when given a prefix GADT constructor. Unlike `ConDeclGADT`, `ConDeclGADTPrefixPs` does not split the GADT type into its argument and result types, as this cannot be done until after the type is renamed (see `Note [GADT abstract syntax]` in `GHC.Hs.Decls` for why this is the case). * `GHC.Renamer.Module.rnConDecl` now has an additional case for `ConDeclGADTPrefixPs` that (1) splits apart the full `LHsType` into its `forall`s, context, argument types, and result type, and (2) checks for nested `forall`s/contexts. Step (2) used to be performed the typechecker (in `GHC.Tc.TyCl.badDataConTyCon`) rather than the renamer, but now the relevant code from the typechecker can simply be deleted. One nice side effect of this change is that we are able to give a more accurate error message for GADT constructors that use visible dependent quantification (e.g., `MkFoo :: forall a -> a -> Foo a`), which improves the stderr in the `T16326_Fail6` test case. Fixes #18191. Bumps the Haddock submodule.
* Add link to GHC's wiki in the GHC API headerTakenobu Tani2020-06-091-0/+3
| | | | | | | | | | This adds a URL to point to GHC's wiki in the GHC API header. Newcomers could easily find more information from the GHC API's web like [1]. [1]: Current version, https://ghc.gitlab.haskell.org/ghc/doc/libraries/ghc-8.11.0.20200604/index.html [skip ci]
* OccurAnal: Avoid exponential behavior due to where clausesBen Gamari2020-06-071-9/+16
| | | | | | | | | | | | | | | Previously the `Var` case of `occAnalApp` could in some cases (namely in the case of `runRW#` applications) call `occAnalRhs` two. In the case of nested `runRW#`s this results in exponential complexity. In some cases the compilation time that resulted would be very long indeed (see #18296). Fixes #18296. Metric Decrease: T9961 T12150 T12234
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