Simon Peyton Jones pushed to branch wip/T26831 at Glasgow Haskell Compiler / GHC Commits: d741a6cc by Andreas Klebinger at 2026-03-31T04:39:33-04:00 Bump minimum shake version for hadrian. We also add the shake version we want to stack.yaml Fixes #26884 - - - - - 5e556f9e by Vladislav Zavialov at 2026-03-31T04:40:16-04:00 Status check for the HsType~HsExpr refactoring (#25121) Add a test case to track the status of a refactoring project within GHC whose goal is to arrive at the following declaration: type HsType = HsExpr The rationale for this is to increase code reuse between the term- and type-level code in the compiler front-end (AST, parser, renamer, type checker). The status report is saved to testsuite/tests/ghc-api/T25121_status.stdout and provides useful insights into what needs to happen to make progress on the ticket. - - - - - acffb1b1 by fendor at 2026-03-31T04:41:02-04:00 Extract Binary instances to `GHC.ByteCode.Binary` - - - - - e2ea8e25 by fendor at 2026-03-31T04:41:02-04:00 Add `seqNonEmpty` for evaluating `NonEmpty a` - - - - - 048b00b7 by fendor at 2026-03-31T04:41:02-04:00 Record `LinkableUsage` instead of `Linkable` in `LoaderState` Retaining a ByteCode `Linkable` after it has been loaded retains its `UnlinkedBCO`, keeping it alive for the remainder of the program. This starts accumulating a lot of `UnlinkedBCO` and memory over time. However, the `Linkable` is merely used to later record its usage in `mkObjectUsage`, which is used for recompilation checking. However, this is incorrect, as the interface file and bytecode objects could be in different states, e.g. the interface changes, but the bytecode library hasn't changed so we don't need to recompile and vice versa. By computing a `Fingerprint` for the `ModuleByteCode`, and recording it in the `LinkableUsage`, we know precisely whether the `ByteCode` object on disk is outdated. Thus, parts of this commit just makes sure that we efficiently compute a `Fingerprint` for `ModuleByteCode` and store it in the on-disk representation of `ModuleByteCode`. We change the `LoaderState` to retain `LinkableUsage`, which is smaller representation of a `Linkable`. This allows us to free the unneeded fields of `Linkable` after linking them. We declare the following memory invariants that this commit implements: * No `LinkablePart` should be retained from `LoaderState`. * `Linkable`s should be unloaded after they have been loaded. These invariants are unfortunately tricky to automatically uphold, so we are simply documenting our assumptions for now. We introduce the `linkable-space` test which makes sure that after loading, no `DotGBC` or `UnlinkedBCO` is retained. ------------------------- Metric Increase: MultiLayerModulesTH_OneShot ------------------------- We allocate a bit more, but the peak number of bytes doesn't change. While a bit unfortunate, accepting the metric increase. We add multiple new performance measurements where we were able to observe the desired memory invariants. Further, we add regression tests to validate that the recompilation checker behaves more correct than before. - - - - - 2d1c1997 by Simon Jakobi at 2026-03-31T04:41:46-04:00 Eliminate dictionary-passing in ListMap operations Mark the ListMap helpers 'INLINABLE' so importing modules can specialise the 'TrieMap (ListMap m)' methods and avoid recursive dictionary-passing. See Note [Making ListMap operations specialisable]. Fixes #27097 - - - - - ed2c6570 by Cheng Shao at 2026-03-31T04:42:33-04:00 testsuite: fix testdir cleanup logic on Windows testdir cleanup is unreliable on Windows (#13162) and despite existing hacks in the driver, new failure mode has occurred. This patch makes it print the warning and carry on when failed to clean up a testdir, instead of reporting a spurious framework failure. See added comment for detailed explanation. - - - - - d9388e29 by Simon Jakobi at 2026-03-31T13:14:59-04:00 Add regression test for #18177 Closes #18177. Assisted-by: Codex - - - - - 6a10045c by mangoiv at 2026-03-31T13:15:43-04:00 ci: allow metric decrease for two tests on i386 There has been a nightly failure on i386 due to a compiler runtime improvement on i386 debian 12. We allow that. Metric Decrease (test_env='i386-linux-deb12'): T12707 T8095 - - - - - e9623c94 by Simon Peyton Jones at 2026-03-31T21:01:01+01:00 Refactor eta-expansion in Prep The Prep pass does eta-expansion but I found cases where it was doing bad things. So I refactored and simplified it quite a bit. In the new design * There is no distinction between `rhs` and `body`; in particular, lambdas can now appear anywhere, rather than just as the RHS of a let-binding. * This change led to a significant simplification of Prep, and a more straightforward explanation of eta-expansion. See the new Note [Eta expansion] * The consequences is that CoreToStg needs to handle naked lambdas. This is very easy; but it does need a unique supply, which forces some simple refactoring. Having a unique supply to hand is probably a good thing anyway. - - - - - 3a33983b by Simon Peyton Jones at 2026-03-31T21:01:02+01:00 Clarify Note [Interesting dictionary arguments] Ticket #26831 ended up concluding that the code for GHC.Core.Opt.Specialise.interestingDict was good, but the commments were a bit inadequate. This commit improves the comments slightly. - - - - - 690acec9 by Simon Peyton Jones at 2026-03-31T21:01:02+01:00 Make inlining a bit more eager for overloaded functions If we have f d = ... (class-op d x y) ... we should be eager to inline `f`, because that may change the higher order call (class-op d x y) into a call to a statically known function. See the discussion on #26831. Even though this does a bit /more/ inlining, compile times decrease by an average of 0.4%. Compile time changes: DsIncompleteRecSel3(normal) 431,786,104 -2.2% ManyAlternatives(normal) 670,883,768 -1.6% ManyConstructors(normal) 3,758,493,832 -2.6% GOOD MultilineStringsPerf(normal) 29,900,576 -2.8% T14052Type(ghci) 1,047,600,848 -1.2% T17836(normal) 392,852,328 -5.2% T18478(normal) 442,785,768 -1.4% T21839c(normal) 341,536,992 -14.1% GOOD T3064(normal) 174,086,152 +5.3% BAD T5631(normal) 506,867,800 +1.0% hard_hole_fits(normal) 209,530,736 -1.3% info_table_map_perf(normal) 19,523,093,184 -1.2% parsing001(normal) 377,810,528 -1.1% pmcOrPats(normal) 60,075,264 -0.5% geo. mean -0.4% minimum -14.1% maximum +5.3% Runtime changes haddock.Cabal(normal) 27,351,988,792 -0.7% haddock.base(normal) 26,997,212,560 -0.6% haddock.compiler(normal) 219,531,332,960 -1.0% Metric Decrease: ManyConstructors T17949 T21839c T13035 TcPlugin_RewritePerf hard_hole_fits Metric Increase: T3064 - - - - - 69 changed files: - compiler/GHC/Builtin/PrimOps.hs - + compiler/GHC/ByteCode/Binary.hs - + compiler/GHC/ByteCode/Recomp/Binary.hs - compiler/GHC/ByteCode/Serialize.hs - compiler/GHC/Core/Opt/Arity.hs - compiler/GHC/Core/Opt/Specialise.hs - compiler/GHC/Core/Tidy.hs - compiler/GHC/Core/Unfold.hs - compiler/GHC/CoreToStg.hs - compiler/GHC/CoreToStg/Prep.hs - compiler/GHC/Data/TrieMap.hs - compiler/GHC/Driver/Hooks.hs - compiler/GHC/Driver/Main.hs - compiler/GHC/Driver/Pipeline.hs - compiler/GHC/Driver/Plugins.hs - compiler/GHC/HsToCore/Usage.hs - compiler/GHC/Iface/Recomp.hs - compiler/GHC/Iface/Recomp/Types.hs - compiler/GHC/Linker/ByteCode.hs - compiler/GHC/Linker/Deps.hs - compiler/GHC/Linker/Loader.hs - compiler/GHC/Linker/Types.hs - compiler/GHC/Runtime/Loader.hs - compiler/GHC/Stg/Lint.hs - compiler/GHC/Tc/Types.hs - compiler/GHC/Tc/Utils/Monad.hs - compiler/GHC/Types/Id.hs - compiler/GHC/Types/Id/Info.hs - compiler/GHC/Unit/Home/ModInfo.hs - compiler/GHC/Unit/Module/Deps.hs - compiler/GHC/Unit/Module/Status.hs - compiler/GHC/Utils/Misc.hs - compiler/ghc.cabal.in - ghc/GHCi/Leak.hs - hadrian/hadrian.cabal - hadrian/stack.yaml - testsuite/driver/testlib.py - testsuite/tests/arityanal/should_compile/Arity01.stderr - testsuite/tests/arityanal/should_compile/Arity05.stderr - testsuite/tests/arityanal/should_compile/Arity08.stderr - testsuite/tests/arityanal/should_compile/Arity11.stderr - testsuite/tests/arityanal/should_compile/Arity14.stderr - + testsuite/tests/bytecode/TLinkable/BCOTemplate.hs - + testsuite/tests/bytecode/TLinkable/LinkableUsage01.stderr - + testsuite/tests/bytecode/TLinkable/LinkableUsage02.stderr - + testsuite/tests/bytecode/TLinkable/Makefile - + testsuite/tests/bytecode/TLinkable/all.T - + testsuite/tests/bytecode/TLinkable/genLinkables.sh - + testsuite/tests/bytecode/TLinkable/linkable-space.hs - + testsuite/tests/bytecode/TLinkable/linkable-space.stdout - testsuite/tests/count-deps/CountDepsAst.stdout - testsuite/tests/count-deps/CountDepsParser.stdout - + testsuite/tests/driver/T18177.hs - testsuite/tests/driver/all.T - testsuite/tests/driver/multipleHomeUnits/multipleHomeUnits_recomp_th.stdout - + testsuite/tests/driver/recomp022/A1.hs - + testsuite/tests/driver/recomp022/A2.hs - + testsuite/tests/driver/recomp022/A3.hs - + testsuite/tests/driver/recomp022/B.hs - + testsuite/tests/driver/recomp022/C.hs - + testsuite/tests/driver/recomp022/Makefile - + testsuite/tests/driver/recomp022/all.T - + testsuite/tests/driver/recomp022/recomp022a.stdout - + testsuite/tests/driver/recomp022/recomp022b.stdout - + testsuite/tests/ghc-api/T25121_status.hs - + testsuite/tests/ghc-api/T25121_status.stdout - testsuite/tests/ghc-api/all.T - testsuite/tests/simplCore/should_compile/T15205.stderr - testsuite/tests/wasm/should_run/control-flow/LoadCmmGroup.hs The diff was not included because it is too large. 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