Rodrigo Mesquita pushed to branch wip/romes/27131 at Glasgow Haskell Compiler / GHC Commits: d1ddfd4b by Rodrigo Mesquita at 2026-04-14T18:41:12-04:00 Add test for #25636 The existing test behaviour of "T23146_liftedeq" changed because the simplifier now does a bit more inlining. We can restore the previous bad behavior by using an OPAQUE pragma. This test doubles as a test for #25636 when run in ghci, so we add it as such. - - - - - b9df40ee by Rodrigo Mesquita at 2026-04-14T18:41:12-04:00 refactor: protoBCOName is always a Name Simplifies the code by removing the unnecessary type argument to ProtoBCO which was always 'Name' - - - - - 5c2a179e by Rodrigo Mesquita at 2026-04-14T18:41:12-04:00 Allocate static constructors for bytecode This commit adds support for static constructors when compiling and linking ByteCode objects. Top-level StgRhsCon get lowered to ProtoStaticCons rather than to ProtoBCOs. A ProtoStaticCon gets allocated directly as a data con application on the heap (using the new primop newConApp#). Previously, we would allocate a ProtoBCO which, when evaluated, would PACK and return the constructor. A few more details are given in Note [Static constructors in Bytecode]. Secondly, this commit also fixes issue #25636 which was caused by linking *unlifted* constructors in BCO instructions as - (1) a thunk indexing the array of BCOs in a module - (2) which evaluated to a BCO which still had to be evaluated to return the unlifted constructor proper. The (2) issue has been resolved by allocating the static constructors directly. The (1) issue can be resolved by ensuring that we allocate all unlifted top-level constructors eagerly, and leave the knot-tying for the lifted BCOs and top-level constructors only. The top-level unlifted constructors are never mutually recursive, so we can allocate them all in one go as long as we do it in topological order. Lifted fields of unlifted constructors can still be filled by the knot-tied lifted variables since in those fields it is fine to keep those thunks. See Note [Tying the knot in createBCOs] for more details. Fixes #25636 ------------------------- Metric Decrease: LinkableUsage01 ------------------------- - - - - - cde47053 by Rodrigo Mesquita at 2026-04-14T18:41:12-04:00 Revert "StgToByteCode: Assert that PUSH_G'd values are lifted" This reverts commit ec26c54d818e0cd328276196930313f66b780905. Ever since f7a22c0f4e9ae0dc767115d4c53fddbd8372b777, we now do support and will link top-level unlifted constructors into evaluated and properly tagged values which we can reference with PUSH_G. This assertion is no longer true and triggered a failure in T25636 - - - - - c7a7e5b8 by Rodrigo Mesquita at 2026-04-14T18:41:12-04:00 refactor: Tag more remote Ptrs as RemotePtr Pure refactor which improves the API of - GHC.ByteCode.Linker - GHC.Runtime.Interpreter - GHC.Runtime.Interpreter.Types.SymbolCache by using `RemotePtr` for more functions which used to return `Ptr`s that could potentially be in a foreign process. E.g. `lookupIE`, `lookupStaticPtr`, etc... - - - - - fc59494c by Rodrigo Mesquita at 2026-04-14T18:41:12-04:00 Add float# and subword tests for #25636 These tests cover that static constructors in bytecode work correctly for Float# and subword values (Word8#, Word16#) - - - - - 477f521b by Rodrigo Mesquita at 2026-04-14T18:41:12-04:00 test: Validate topoSort logic in createBCOs This test validates that the topological sorting and ordering of the unlifted constructors and lifted constructors in `createBCOs` is correct. See `Note [Tying the knot in createBCOs]` for why tying the knot for the created BCOs is slightly difficult and why the topological sorting is necessary. This test fails when `let topoSortedObjs = topSortObjs objs` is substituted by `let topoSortedObjs = zip [0..] objs`, thus witnessing the toposort logic is correct and necessary. The test calls the ghci `createBCOs` directly because it is currently impossible to construct in Source Haskell a situation where a top-level static unlifted constructor depends on another (we don't have top-level unlifted constructors except for nullary constructors like `Leaf :: (UTree :: UnliftedType)`). This is another test for fix for #25636 - - - - - 2d9c30be by Simon Jakobi at 2026-04-14T18:42:00-04:00 Improve tests for `elem` ...in order to simplify the work on #27096. * Improve T17752 by including the Core output in golden files, checking both -O1 and -O2. * Add tests for fusion and no-fusion cases. Fixes #27101. - - - - - 2dadf3b0 by sheaf at 2026-04-16T13:28:39-04:00 Simplify mkTick This commit simplifies 'GHC.Core.Utils.mkTick', removing the accumulating parameter 'rest' which was suspiciously treating a bunch of different ticks as a group, and moving the group as a whole around the AST, ignoring that the ticks in the group might have different placement properties. The most important change is that we revert the logic (added in 85b0aae2) that allowed ticks to be placed around coercions, which caused serious issues (e.g. #27121). It was just a mistake, as it doesn't make sense to put a tick around a coercion. Also adds Note [Pushing SCCs inwards] which clarifies the logic for pushing SCCs into lambdas, constructor applications, and dropping SCCs around non-function variables (in particular the treatment of splittable ticks). A few other changes are also implemented: - simplify 'can_split' predicate (no functional change) - combine profiling ticks into one when possible Fixes #26878, #26941 and #27121 Co-authored-by: simonpj <simon.peytonjones@gmail.com> - - - - - a0d6f1f4 by Simon Jakobi at 2026-04-16T13:29:28-04:00 Add regression test for #9074 Closes #9074. - - - - - d178ee89 by Sylvain Henry at 2026-04-16T13:30:25-04:00 Add changelog for #15973 - - - - - e8a196c6 by sheaf at 2026-04-16T13:31:19-04:00 Deal with 'noSpec' in 'coreExprToPmLit' This commit makes two separate changes relating to 'GHC.HsToCore.Pmc.Solver.Types.coreExprAsPmLit': 1. Commit 7124e4ad mistakenly marked deferred errors as non-canonical, which led to the introduction of 'nospec' wrappers in the generated Core. This reverts that accident by declaring deferred errors as being canonical, avoiding spurious 'nospec' wrapping. 2. Look through magic identity-like Ids such as 'nospec', 'inline' and 'lazy' in 'coreExprAsPmLit', just like Core Prep does. There might genuinely be incoherent evidence, but that shouldn't obstruct the pattern match checker. See test T27124a. Fixes #25926 #27124 ------------------------- Metric Decrease: T3294 ------------------------- - - - - - 8cb99552 by Sylvain Henry at 2026-04-16T19:22:43-04:00 hadrian: warn when package index is missing (#16484) Since cabal-install 3.0 we can query the path of remote-repo-cache and check if hackage package index is present. Fixes #16484 - - - - - d6ce7477 by Richard Eisenberg at 2026-04-16T19:23:25-04:00 Teach hadrian to --skip-test. Fixes #27188. This adds the --skip-test flag to `hadrian build`, as documented in the patch. - - - - - 7666f4a9 by Fendor at 2026-04-17T22:29:51-04:00 Migrate `ghc-pkg` to use `OsPath` and `file-io` `ghc-pkg` should use UNC paths as much as possible to avoid MAX_PATH issues on windows. `file-io` uses UNC Paths by default on windows, ensuring we use the correct APIs and that we finally are no longer plagued by MAX_PATH issues in CI and private machines. On top of it, the higher correctness of `OsPath` is appreciated in this small codebase. Also, we improve memory usage very slightly, due to the more efficient memory representation of `OsPath` over `FilePath` Adds `ghc-pkg` regression test for MAX_PATH on windows Make sure `ghc-pkg` behaves as expected when long paths (> 255) are involved on windows. Let's generate a testcase where we can actually observe that `ghc-pkg` behaves as epxected. See the documentation for windows on Maximum Path Length Limitation: * `https://learn.microsoft.com/en-us/windows/win32/fileio/maximum-file-path-limitation` Adds changelog entry for long path support in ghc-pkg. - - - - - 78434e8c by Simon Peyton Jones at 2026-04-17T22:30:38-04:00 Kill off the substitution in Lint Now that we have invariant (NoTypeShadowing) we no longer need Lint to carry an ambient substitution. This makes it simpler and faster. A really worthwhile refactor. There are some knock-on effects * Linting join points after worker/wrapper. See Note [Join points and beta redexes] * Running a type substitution after the desugarer. See Note [Substituting type-lets] in the new module GHC.Core.SubstTypeLets Implements #27078 Most perf tests don't use Lint so we won't see a perf incresae. But T1969, which uses -O0 and Lint, gets 1.3% worse because it has to run the SubstTypeLets pass which is a somewhat expensive no-op Overall though compile-time allocations are down 0.1%. Metric Increase: T1969 - - - - - 86ca6c2c by mangoiv at 2026-04-17T22:31:22-04:00 testsuite: inline elemCoreTest Some weird (probably python scoping) rule caused elemCoreTest, a regex being out of scope on ubuntu, presumably because of a newer python version. This patch just inlines the regex, which fixes the issue. Fixes #27193 - - - - - 72d6dc74 by aparker at 2026-04-20T20:15:44-04:00 NCG: Implement constant folding for vector simd ops (Issue #25030) - - - - - b9cab907 by sheaf at 2026-04-20T20:15:44-04:00 Mark some SIMD tests as broken on i386 optllvm As seen in #25498, several SIMD tests are broken on i386 in the optllvm way. This commit marks them as "expect_broken". - - - - - 76528cc3 by Wolfgang Jeltsch at 2026-04-20T20:16:25-04:00 Move most of the `System.IO` implementation into `base` This involves a rewrite of the `combine` helper function to avoid the use of `last`, which would now be flagged as an error. Metric Decrease: LinkableUsage01 T3294 Metric Increase: T12227 T12707 T5642 - - - - - 948617cc by Rodrigo Mesquita at 2026-04-28T14:13:29+01:00 New rts Message to {set,unset} TSO flags This commit introduces stg_MSG_SET_TSO_FLAG_info and stg_MSG_UNSET_TSO_FLAG_info, which allows setting flags of a TSO other than yourself. This is especially useful/necessary to set breakpoints and toggle breakpoints of different threads, which is needed to safely implement features like pausing, toggling step-out, toggling step-in per thread, etc. Fixes #27131 ------------------------- Metric Decrease: T3294 ------------------------- - - - - - 361c2144 by Rodrigo Mesquita at 2026-04-28T14:13:29+01:00 test: Add test setting another TSO's flags Introduces a test that runs on two capabilities. The main thread running on Capability 0 sets the flags on a TSO running on Capability 1. The TSO from Capability 1 itself checks whether its flags were set and reports that back. This validates that the RTS messages for setting TSO flags work, even if it doesn't test a harsher scenario with race conditions to exercise why the message passing is necessary for safely setting another TSO's flags. Part of #27131 - - - - - 167 changed files: - + changelog.d/T15973 - + changelog.d/T25636 - + changelog.d/T27121.md - + changelog.d/T27124.md - + changelog.d/T27131 - + changelog.d/ghc-pkg-long-path-support - + changelog.d/hadrian-warn-missing-package-index-16484 - + changelog.d/simd_constant_folding - + changelog.d/skip-test - compiler/GHC/Builtin/primops.txt.pp - compiler/GHC/ByteCode/Asm.hs - compiler/GHC/ByteCode/Binary.hs - compiler/GHC/ByteCode/Instr.hs - compiler/GHC/ByteCode/Linker.hs - compiler/GHC/ByteCode/Types.hs - compiler/GHC/Cmm/Liveness.hs - compiler/GHC/Cmm/Opt.hs - compiler/GHC/Core/Lint.hs - + compiler/GHC/Core/Lint/SubstTypeLets.hs - compiler/GHC/Core/Opt/FloatOut.hs - compiler/GHC/Core/Opt/OccurAnal.hs - compiler/GHC/Core/Opt/WorkWrap/Utils.hs - compiler/GHC/Core/Subst.hs - compiler/GHC/Core/Utils.hs - compiler/GHC/CoreToStg/Prep.hs - compiler/GHC/Driver/Config/Core/Lint.hs - compiler/GHC/HsToCore/Pmc/Solver/Types.hs - compiler/GHC/Linker/Loader.hs - compiler/GHC/Runtime/Interpreter.hs - 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utils/haddock/html-test/ref/QuasiExpr.html - utils/haddock/html-test/ref/Test.html The diff was not included because it is too large. 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