Marge Bot pushed to branch wip/marge_bot_batch_merge_job at Glasgow Haskell Compiler / GHC Commits: dec0ac68 by Simon Peyton Jones at 2026-05-16T03:32:10-04:00 Do not use mkCast during typechecking This commit fixes #27219. The problem was that the typechecker was using `mkCast`, whose assertion checks legitimately fail when applied to types that contain unification variables. - - - - - dd01a019 by Simon Peyton Jones at 2026-05-16T03:32:10-04:00 Major refactor of the Simplifier The main payload of this patch is to refactor the Simplifer to avoid repeated simplification when using Plan (AFTER) for rule rewrites. The need for this was shown up by #26989. See Note [Avoid repeated simplification] in GHC.Core.Opt.Simplify.Iteration. Related refactoring: * Refactor the two fields `sc_dup` and `sc_env` in `ApplyToVal` into one, `sc_env`. Reason: the envt is irrelevant in the "simplified" case, so the data type describes the possiblitiies much more accurately now. * Some refactoring in `knownCon` to split off `wrapDataConFloats`. * Refactor `lookupRule` and its auxiliary functions to return `RuleMatch`, a new data type. See Note [data RuleMatch] in GHC.Core. Ditto for BuiltinRule. This RuleMatch returns fragments of the target in rm_args and rm_floats, leaving `rm_rhs` to be the stuff from the RULE itself. Doing this has routine consequences in GHC.Core.Opt.ConstantFold. Many changes there but all routine. * When doing occurrence analysis on RULEs, make the occ-info on the rule binders relate just to the RHS, not the LHS. See (OUR1) in Note Note [OccInfo in unfoldings and rules] This means that Lint must not complain about the fact that the patterns in the RULE mentions binders that are marked dead. See Note [Dead occurrences] in GHC.Core.Lint. I changed the Core pretty-printer so that it didn't suppress dead binders, else I can't see those binders in RULEs. That led to quite a lot of testsuite wibbles. * Refactor FloatBinds, so that it is used both by `exprIsConApp_mabye` and by `lookupRule` * Move the definition of FloatBinds out of GHc.Core.Make, into GHC.Core. * Add FloatTick as an extra constructor. * Refactor `lookupRule` to use `FloatBinds` instead of `BindWrapper`. This refactor just shares more code. (Rename GHC.Core.Opt.FloatOut.FloatBinds to FloatLets, to avoid gratuitious name clash with GHC.Core.FloatBinds.) Corecion optimisation * In simpleOpt, when composing coercions, call new function `optTransCo`. This is much lighter weight than full blown coercion optimisation. * Make `GHC.Core.Opt.Arity.pushCoValArg` and `pushCoTyArg` return the coercionLKind of the coercion. This saves recomputing that coercionLKind at the key call sites in GHC.Core.Opt.Simplify.Iteration.pushCast. * Rename `addCoerce` in GHC.Core.Simplify.Iteration to become `pushCast`. * In the `ApplyToVal` case of `pushCast` we had a very unsavoury call to `simplArg`. I eliminated it by adding a field `sc_cast` to `ApplyToVal` that records any pending casts. Much nicer now. See Note [The sc_cast field of ApplyToVal]. * Don't optimise coercions if the type-substitution is empty. See Note [Optimising coercions] in GHC.Core.Opt.Simplify.Iteration. The fix for #26838 is dramatic. For the test in perf/compiler/T26839 we have Compiler allocs: Before: 7,363M After: 688M Compile time goes down generally. Here are compiler-alloc changes over 0.5%: CoOpt_Read(normal) 729,184,920 -0.7% CoOpt_Singletons(normal) 666,916,960 -4.6% GOOD LargeRecord(normal) 1,227,056,876 +1.1% T12227(normal) 256,827,604 -4.6% GOOD T12425(optasm) 76,879,410 -0.8% T12545(normal) 787,826,918 -10.8% GOOD T12707(normal) 775,186,464 -0.9% T13253(normal) 318,599,596 -0.8% T14766(normal) 685,857,320 -1.0% T15304(normal) 1,123,333,422 -2.2% T15630(normal) 123,142,330 -2.6% T15630a(normal) 123,092,100 -2.6% T15703(normal) 299,751,682 -2.9% GOOD T17516(normal) 964,072,280 +1.0% T18223(normal) 367,016,820 -6.2% GOOD T18730(optasm) 130,643,770 -3.3% GOOD T20261(normal) 535,608,584 -0.7% T21839c(normal) 340,340,436 -0.9% T24984(normal) 85,568,392 -1.9% T3064(normal) 174,631,992 -1.2% T3294(normal) 1,215,886,432 -0.7% T5030(normal) 141,449,704 -17.2% GOOD T5321Fun(normal) 258,484,744 -1.9% T8095(normal) 770,532,232 -2.7% T9630(normal) 858,423,408 -14.5% GOOD T9872c(normal) 1,591,709,448 +0.7% info_table_map_perf(normal) 19,700,614,458 -1.3% geo. mean -0.7% minimum -17.2% maximum +1.1% Metric Decrease: CoOpt_Singletons T12227 T12545 T12707 T15703 T18223 T18730 T21839c T5030 T9630 - - - - - 651148d1 by Vladislav Zavialov at 2026-05-16T03:32:11-04:00 Add type families: Tuple, Constraints, Tuple#, Sum# These type families map tuples of types to the corresponding Tuple<N>, Tuple<N>#, CTuple<N>, and Sum<N># types. Some examples at N=2: Tuple (Int, Bool) = Tuple2 Int Bool Constraints (Show a, Eq a) = CTuple2 (Show a) (Eq a) Tuple# (Int#, Float#) = Tuple2# Int# Float# Sum# (Int#, Float#) = Sum2# Int# Float# See GHC Proposal #145 "Non-punning list and tuple syntax". To make the Sum# instance at N=64 possible, this patch also introduces the Sum64# constructor declaration and bumps mAX_SUM_SIZE from 63 to 64. Metric Increase: ghc_experimental_dir - - - - - d1e099b1 by fendor at 2026-05-16T03:32:12-04:00 Fix regression T27202: `:load` and `:add` work in GHCi To fix the regression there are conceptually two major things that we fix: * We don't remove the `importDirs` from `interactive-session` * When `:add`ing a module, we don't try to find them via PackageImports * The PackageImport is wrong as we can't know the package-name at this stage in ghc/UI.hs What does it mean to not remove the `importDirs` from `interactive-session`? It means that, given some initial `DynFlags`, we will use those `importDirs` in `interactive-session`. The initial `DynFlags`, however, depend on how you initialise the GHC session. For a simple session, initialised by ghc -isrc -this-unit-id main It is simple, just use the `DynFlags` given on the cli. Thus, `main` and `interactive-session` will have the same `DynFlags`, except for the `homeUnitId` and `interactive-session` depends on `main` by construction of the GHCi session. What about a multiple home unit session, though? ghc -unit @unit1 -unit @unit2 What are the `DynFlags` in this cli invocation? It shouldn't be either `@unti1` nor `@unit2`, as the order shouldn't matter or any other implicit condition. For consistency, we decide that the initial `DynFlags` are the top `DynFlags` on the cli, ignoring `-unit` flags. Thus, in this example, there are no `importsDirs` regardless of what we might find in `@unit1` and `@unit2`. But in this invocation: ghc -isrc -unit @unit1 -unit @unit2 The `interactive-session` will have the `importsDirs` `src`. Note, `-isrc` will be inherited in `@unit1` and `@unit2`, so you need to explicitly use `-i` to clear the `importsDirs`, in order to avoid accidentally adding `src` as an import directory to all other home units. This fix has been made possible by the improvements introduced in !15888, which avoids ambiguity when a home unit shares the `importsDirs` with the `interactive-session`, on top of being much faster for multiple home units. Adds regression tests for T27202 for `:load`ing and `:add`ing modules that are located in import directories. - - - - - 67c7f95b by fendor at 2026-05-16T03:32:12-04:00 Use home unit package db stacks in GHCi prompt and session unit In order to import modules from home unit dependencies (e.g., `Data.Map`), the ghci prompt unit needs to populate its `UnitState`. This is tricky to handle correctly, which `PackageDBFlag`s should we use to populate the `UnitState`? We decide, the most intuitive solution for users is to depend on all `PackageDBFlag`s, so that any dependency can be imported in GHCi. This assumes consistency in the `PackageDBFlag`s, so no two home units specify `PackageDBFlag`s that are inconsistent with each other. We could simply concat all the `PackageDBFlag`s of the existing home units, but later `PackageDBFlag`s shadow earlier ones, leading to the last processed home units' `PackageDBFlag`s to shadow the earlier ones. This is hard to fix, we need to give users the capability to provide ghc options for the ghci prompt home unit. However, as this is considerably more work, we decided on an approximation that should work out most of the time. Package Db stacks in cabal and stack follow a certain structure: -no-user-package-db > -package-db $cabal-store > -package-db $local-db The first two arguments are always the same, namely the `-no-user-package-db` and `-package-db`. We compute the longest common prefix over all home units, and use that as the start of the package db stack. Then, over the rest of the `PackageDBFlag`s, we simply take the union and append them to our initial stack. We assume, that the rest of package dbs only defines very few, "local" units that are usually not shadowing each other. This allows us to get a relatively consistent package database stack for the ghci prompt home unit. Similar reasoning applies to the session unit in order to add modules to the session and have dependencies available in the module. We do something similar for `-package` flags, to make sure only the correct units are actually visible in the ghci session. This time, we simply take the union of all `PackageFlag`s, allowing us to import modules from the home unit dependencies. In the future, it would be beneficial to allow the user to provide the exact ghc options to control the visibilities. For now, this will have to do. - - - - - 0d9d0d6e by Duncan Coutts at 2026-05-16T03:32:13-04:00 Document removal of the signal-based interval timer Update mentions within the RTS section of the users guide. Add a changelog entry. - - - - - 2b1473df by Duncan Coutts at 2026-05-16T03:32:13-04:00 Fix section for an recent changelog entry - - - - - 149 changed files: - + changelog.d/T27202 - changelog.d/dynamic-trace-flags - + changelog.d/lib-add-tuple-tyfam-27179 - + changelog.d/no-more-timer-signal - compiler/GHC/Core.hs - compiler/GHC/Core/Coercion.hs - compiler/GHC/Core/Coercion/Opt.hs - compiler/GHC/Core/Lint.hs - compiler/GHC/Core/Make.hs - compiler/GHC/Core/Opt/Arity.hs - compiler/GHC/Core/Opt/ConstantFold.hs - compiler/GHC/Core/Opt/FloatIn.hs - compiler/GHC/Core/Opt/FloatOut.hs - compiler/GHC/Core/Opt/OccurAnal.hs - compiler/GHC/Core/Opt/Simplify/Env.hs - compiler/GHC/Core/Opt/Simplify/Iteration.hs - compiler/GHC/Core/Opt/Simplify/Utils.hs - compiler/GHC/Core/Opt/SpecConstr.hs - compiler/GHC/Core/Opt/Specialise.hs - compiler/GHC/Core/Ppr.hs - compiler/GHC/Core/Rules.hs - compiler/GHC/Core/SimpleOpt.hs - compiler/GHC/Core/TyCo/Subst.hs - compiler/GHC/CoreToStg/Prep.hs - compiler/GHC/Data/List/SetOps.hs - compiler/GHC/Driver/Config/Core/Lint.hs - compiler/GHC/Driver/DynFlags.hs - compiler/GHC/HsToCore/Pmc/Solver.hs - compiler/GHC/IfaceToCore.hs - compiler/GHC/Settings/Constants.hs - compiler/GHC/Tc/Types/Evidence.hs - compiler/GHC/Types/Id/Make.hs - compiler/GHC/Unit/State.hs - docs/users_guide/profiling.rst - docs/users_guide/runtime_control.rst - ghc/GHCi/UI.hs - ghc/Main.hs - libraries/base/src/GHC/Base.hs - libraries/base/src/GHC/Exts.hs - libraries/ghc-experimental/src/Data/Sum/Experimental.hs - libraries/ghc-experimental/src/Data/Tuple/Experimental.hs - libraries/ghc-internal/src/GHC/Internal/Base.hs - libraries/ghc-internal/src/GHC/Internal/Exts.hs - libraries/ghc-internal/src/GHC/Internal/Types.hs - testsuite/tests/codeGen/should_compile/T25177.stderr - testsuite/tests/deSugar/should_compile/T13208.stdout - testsuite/tests/driver/fat-iface/fat014.stdout - + testsuite/tests/ghci/prog-mhu006/Makefile - + testsuite/tests/ghci/prog-mhu006/a/A.hs - + testsuite/tests/ghci/prog-mhu006/all.T - + testsuite/tests/ghci/prog-mhu006/b/B.hs - + testsuite/tests/ghci/prog-mhu006/prog-mhu006a.script - + testsuite/tests/ghci/prog-mhu006/prog-mhu006a.stdout - + testsuite/tests/ghci/prog-mhu006/unitA - + testsuite/tests/ghci/prog-mhu006/unitB - testsuite/tests/ghci/prog018/prog018.stdout - testsuite/tests/ghci/prog020/Makefile - testsuite/tests/ghci/prog020/all.T - testsuite/tests/ghci/prog020/ghci.prog020.script → testsuite/tests/ghci/prog020/ghci.prog020a.script - testsuite/tests/ghci/prog020/ghci.prog020.stderr → testsuite/tests/ghci/prog020/ghci.prog020a.stderr - testsuite/tests/ghci/prog020/ghci.prog020.stdout → testsuite/tests/ghci/prog020/ghci.prog020a.stdout - + testsuite/tests/ghci/prog020/ghci.prog020b.script - + testsuite/tests/ghci/prog020/ghci.prog020b.stderr - + testsuite/tests/ghci/prog020/ghci.prog020b.stdout - + testsuite/tests/ghci/prog023/Makefile - + testsuite/tests/ghci/prog023/all.T - + testsuite/tests/ghci/prog023/prog023a.script - + testsuite/tests/ghci/prog023/prog023a.stdout - + testsuite/tests/ghci/prog023/prog023b.script - + testsuite/tests/ghci/prog023/prog023b.stdout - + testsuite/tests/ghci/prog023/src/A.hs - + testsuite/tests/ghci/prog024/Makefile - + testsuite/tests/ghci/prog024/all.T - + testsuite/tests/ghci/prog024/prog024a.script - + testsuite/tests/ghci/prog024/prog024a.stdout - + testsuite/tests/ghci/prog024/prog024b.script - + testsuite/tests/ghci/prog024/prog024b.stdout - + testsuite/tests/ghci/prog024/prog024c.script - + testsuite/tests/ghci/prog024/prog024c.stderr - + testsuite/tests/ghci/prog024/prog024c.stdout - + testsuite/tests/ghci/prog024/prog024d.script - + testsuite/tests/ghci/prog024/prog024d.stderr - + testsuite/tests/ghci/prog024/prog024d.stdout - + testsuite/tests/ghci/prog024/prog024e.script - + testsuite/tests/ghci/prog024/prog024e.stdout - + testsuite/tests/ghci/prog024/prog024f.script - + testsuite/tests/ghci/prog024/prog024f.stdout - + testsuite/tests/ghci/prog024/src/A.hs - + testsuite/tests/ghci/prog024/src/B.hs - + testsuite/tests/ghci/prog025/Makefile - + testsuite/tests/ghci/prog025/a/A.hs - + testsuite/tests/ghci/prog025/all.T - + testsuite/tests/ghci/prog025/prog025a.script - + testsuite/tests/ghci/prog025/prog025a.stdout - + testsuite/tests/ghci/prog025/prog025b.script - + testsuite/tests/ghci/prog025/prog025b.stdout - + testsuite/tests/ghci/prog025/testpkg/Test.hs - + testsuite/tests/ghci/prog025/testpkg/testpkg-0.1.0.0.pkg - + testsuite/tests/ghci/prog025/testpkg/testpkg-0.2.0.0.pkg - + testsuite/tests/ghci/prog025/unitA - testsuite/tests/ghci/scripts/ListTuplePunsPprNoAbbrevTuple.stdout - testsuite/tests/ghci/scripts/T13997.stdout - testsuite/tests/ghci/scripts/T1914.stdout - testsuite/tests/ghci/scripts/T20217.stdout - testsuite/tests/ghci/scripts/T8042.stdout - testsuite/tests/ghci/scripts/T8042recomp.stdout - testsuite/tests/ghci/scripts/all.T - testsuite/tests/ghci/should_run/T10920.stderr - testsuite/tests/interface-stability/ghc-experimental-exports.stdout - testsuite/tests/interface-stability/ghc-experimental-exports.stdout-mingw32 - testsuite/tests/interface-stability/ghc-prim-exports.stdout - testsuite/tests/interface-stability/ghc-prim-exports.stdout-mingw32 - testsuite/tests/linters/notes.stdout - testsuite/tests/numeric/should_compile/T15547.stderr - testsuite/tests/numeric/should_compile/T20347.stderr - testsuite/tests/numeric/should_compile/T20374.stderr - testsuite/tests/numeric/should_compile/T20376.stderr - testsuite/tests/parser/should_compile/ListTuplePunsSuccess1.hs - testsuite/tests/parser/should_compile/all.T - + testsuite/tests/parser/should_fail/ListTuplePunsFail6.hs - + testsuite/tests/parser/should_fail/ListTuplePunsFail6.stderr - testsuite/tests/parser/should_fail/all.T - testsuite/tests/parser/should_run/ListTuplePunsConstraints.hs - + testsuite/tests/perf/compiler/T26989.hs - + testsuite/tests/perf/compiler/T26989a.hs - testsuite/tests/perf/compiler/all.T - testsuite/tests/printer/T18052a.stderr - testsuite/tests/profiling/should_run/callstack001.stdout - testsuite/tests/simplCore/should_compile/DsSpecPragmas.stderr - testsuite/tests/simplCore/should_compile/RewriteHigherOrderPatterns.stderr - testsuite/tests/simplCore/should_compile/T15205.stderr - testsuite/tests/simplCore/should_compile/T18668.stderr - testsuite/tests/simplCore/should_compile/T19246.stderr - testsuite/tests/simplCore/should_compile/T19599.stderr - testsuite/tests/simplCore/should_compile/T19599a.stderr - testsuite/tests/simplCore/should_compile/T21917.stderr - testsuite/tests/simplCore/should_compile/T23074.stderr - testsuite/tests/simplCore/should_compile/T24359a.stderr - testsuite/tests/simplCore/should_compile/T25160.stderr - testsuite/tests/simplCore/should_compile/T25718c.stderr-ws-32 - testsuite/tests/simplCore/should_compile/T25718c.stderr-ws-64 - testsuite/tests/simplCore/should_compile/T26051.stderr - testsuite/tests/simplCore/should_compile/T26116.stderr - testsuite/tests/simplCore/should_compile/T8331.stderr - testsuite/tests/simplCore/should_compile/T8848a.stderr - testsuite/tests/simplCore/should_compile/spec004.stderr - testsuite/tests/typecheck/should_compile/T13032.stderr - + testsuite/tests/typecheck/should_compile/T23135.hs - testsuite/tests/typecheck/should_compile/all.T The diff was not included because it is too large. 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