Marge Bot pushed to branch wip/marge_bot_batch_merge_job at Glasgow Haskell Compiler / GHC Commits: 3bfe7a40 by Sylvain Henry at 2026-03-24T10:53:39-04:00 Check that shift values are valid In GHC's codebase in non-DEBUG builds we silently substitute shiftL/R with unsafeShiftL/R for performance reasons. However we were not checking that the shift value was valid for unsafeShiftL/R, leading to wrong computations, but only in non-DEBUG builds. This patch adds the necessary checks and reports an error when a wrong shift value is passed. - - - - - b80d08c3 by Sylvain Henry at 2026-03-24T10:53:39-04:00 Implement basic value range analysis (#25718) Perform basic value range analysis to try to determine at compile time the result of the application of some comparison primops (ltWord#, etc.). This subsumes the built-in rewrite rules used previously to check if one of the comparison argument was a bound (e.g. (x :: Word8) <= 255 is always True). Our analysis is more powerful and handles type conversions: e.g. word8ToWord x <= 255 is now detected as always True too. We also use value range analysis to filter unreachable alternatives in case-expressions. To support this, we had to allow case-expressions for primitive types to not have a DEFAULT alternative (as was assumed before and checked in Core lint). - - - - - fee0c6ed by Teo Camarasu at 2026-03-24T10:53:40-04:00 ghc-internal: Float Generics to near top of module graph We remove GHC.Internal.Generics from the critical path of the `ghc-internal` module graph. GHC.Internal.Generics used to be in the middle of the module graph, but now it is nearer the top (built later). This change thins out the module graph and allows us to get rid of the ByteOrder hs-boot file. We implement this by moving Generics instances from the module where the datatype is defined to the GHC.Internal.Generics module. This trades off increasing the compiled size of GHC.Internal.Generics with reducing the dependency footprint of datatype modules. Not all instances are moved to GHC.Internal.Generics. For instance, `GHC.Internal.Control.Monad.Fix` keeps its instance as it is one of the very last modules compiled in `ghc-internal` and so inverting the relationship here would risk adding GHC.Internal.Generics back onto the critical path. We also don't change modules that are re-exported from the `template-haskell` or `ghc-heap`. This is done to make it easy to eventually move `Generics` to `base` once something like #26657 is implemented. Resolves #26930 Metric Decrease: T21839c - - - - - a4e249ff by Ian Duncan at 2026-03-24T10:53:45-04:00 AArch64: fix MOVK regUsageOfInstr to mark dst as both read and written MOVK (move with keep) modifies only a 16-bit slice of the destination register, so the destination is both read and written. The register allocator must know this to avoid clobbering live values. Update regUsageOfInstr to list the destination in both src and dst sets. No regression test: triggering the misallocation requires specific register pressure around a MOVK sequence, which is difficult to reliably provoke from Haskell source. - - - - - 0199a156 by Luite Stegeman at 2026-03-24T10:53:57-04:00 Windows: remove StgAsyncIOResult and fix crash/leaks In stg_block_async{_void}, a stack slot was reserved for an StgAsyncIOResult. This slot would be filled by the IO manager upon completion of the async call. However, if the blocked thread was interrupted by an async exception, we would end up in an invalid state: - If the blocked computation was never re-entered, the StgAsyncIOResult would never be freed. - If the blocked computation was re-entered, the thread would find an unitialized stack slot for the StgAsyncIOResult, leading to a crash reading its fields, or freeing the pointer. We fix this by removing the StgAsyncIOResult altogether and writing the result directly to the stack. Fixes #26341 - - - - - 068d8a05 by mangoiv at 2026-03-24T10:53:59-04:00 release tracking: adopt release tracking ticket from #16816 - - - - - 0980a23d by mangoiv at 2026-03-24T10:53:59-04:00 release tracking: add a release tracking ticket Brings the information in the release tracking ticket up to date with https://gitlab.haskell.org/ghc/ghc-hq/-/blob/main/release-management.mkd Resolves #26691 - - - - - 0c59ff8e by Cheng Shao at 2026-03-24T10:54:00-04:00 ghc-boot: move GHC.Data.SmallArray to ghc-boot This commit moves `GHC.Data.SmallArray` from the `ghc` library to `ghc-boot`, so that it can be used by `ghci` as well: - The `Binary` (from `ghc`) instance of `SmallArray` is moved to `GHC.Utils.Binary` - Util functions `replicateSmallArrayIO`, `mapSmallArrayIO`, `mapSmallArrayM_`, `imapSmallArrayM_` , `smallArrayFromList` and `smallArrayToList` are added - The `Show` instance is added - The `Binary` (from `binary`) instance is added - - - - - 1c2ab582 by Cheng Shao at 2026-03-24T10:54:00-04:00 compiler: use `Binary` instance of `BCOByteArray` for bytecode objects This commit defines `Binary` (from `compiler`) instance of `BCOByteArray` which serializes the underlying buffer directly, and uses it directly in bytecode object serialization. Previously we reuse the `Binary` (from `binary`) instance, and this change allows us to avoid double-copying via an intermediate `ByteString` when using `put`/`get` in `binnary`. Also see added comment for explanation. - - - - - b9ee3bdf by Cheng Shao at 2026-03-24T10:54:00-04:00 ghci: use SmallArray directly in ResolvedBCO This patch makes ghci use `SmallArray` directly in `ResolvedBCO` when applicable, making the memory representation more compact and reducing marshaling overhead. Closes #27058. - - - - - 18b66f1a by Wen Kokke at 2026-03-24T10:54:04-04:00 Fix race condition between flushEventLog and start/endEventLogging. This commit changes `flushEventLog` to acquire/release the `state_change` mutex to prevent interleaving with `startEventLogging` and `endEventLogging`. In the current RTS, `flushEventLog` _does not_ acquire this mutex, which may lead to eventlog corruption on the following interleaving: - `startEventLogging` writes the new `EventLogWriter` to `event_log_writer`. - `flushEventLog` flushes some events to `event_log_writer`. - `startEventLogging` writes the eventlog header to `event_log_writer`. This causes the eventlog to be written out in an unreadable state, with one or more events preceding the eventlog header. This commit renames the old function to `flushEventLog_` and defines `flushEventLog` simply as: ```c void flushEventLog(Capability **cap USED_IF_THREADS) { ACQUIRE_LOCK(&state_change_mutex); flushEventLog_(cap); RELEASE_LOCK(&state_change_mutex); } ``` The old function is still needed internally within the compilation unit, where it is used in `endEventLogging` in a context where the `state_change` mutex has already been acquired. I've chosen to mark `flushEventLog_` as static and let other uses of `flushEventLog` within the RTS refer to the new version. There is one use in `hs_init_ghc` via `flushTrace`, where the new locking behaviour should be harmless, and one use in `handle_tick`, which I believe was likely vulnerable to the same race condition, so the new locking behaviour is desirable. I have not added a test. The behaviour is highly non-deterministic and requires a program that concurrently calls `flushEventLog` and `startEventLogging`/`endEventLogging`. I encountered the issue while developing `eventlog-socket` and within that context have verified that my patch likely addresses the issue: a test that used to fail within the first dozen or so runs now has been running on repeat for several hours. - - - - - 74 changed files: - + .gitlab/issue_templates/release_tracking.md - compiler/GHC/ByteCode/Linker.hs - compiler/GHC/ByteCode/Serialize.hs - compiler/GHC/CmmToAsm/AArch64/Instr.hs - compiler/GHC/Core.hs - compiler/GHC/Core/Lint.hs - compiler/GHC/Core/Opt/ConstantFold.hs - + compiler/GHC/Core/Opt/Range.hs - compiler/GHC/Core/Opt/Simplify/Iteration.hs - compiler/GHC/Prelude/Basic.hs - compiler/GHC/StgToCmm/Expr.hs - compiler/GHC/StgToCmm/Utils.hs - compiler/GHC/Utils/Binary.hs - compiler/ghc.cabal.in - compiler/GHC/Data/SmallArray.hs → libraries/ghc-boot/GHC/Data/SmallArray.hs - libraries/ghc-boot/ghc-boot.cabal.in - libraries/ghc-internal/src/GHC/Internal/ByteOrder.hs - − libraries/ghc-internal/src/GHC/Internal/ByteOrder.hs-boot - libraries/ghc-internal/src/GHC/Internal/Char.hs - libraries/ghc-internal/src/GHC/Internal/Data/Foldable.hs - libraries/ghc-internal/src/GHC/Internal/Data/Functor/Const.hs - libraries/ghc-internal/src/GHC/Internal/Data/Functor/Identity.hs - libraries/ghc-internal/src/GHC/Internal/Data/Monoid.hs - libraries/ghc-internal/src/GHC/Internal/Data/Semigroup/Internal.hs - libraries/ghc-internal/src/GHC/Internal/Data/Traversable.hs - libraries/ghc-internal/src/GHC/Internal/Data/Version.hs - libraries/ghc-internal/src/GHC/Internal/Event/Control.hs - libraries/ghc-internal/src/GHC/Internal/Functor/ZipList.hs - libraries/ghc-internal/src/GHC/Internal/Generics.hs - libraries/ghc-internal/src/GHC/Internal/IO/Exception.hs - libraries/ghc-internal/src/GHC/Internal/RTS/Flags.hsc - libraries/ghc-internal/src/GHC/Internal/Read.hs - libraries/ghc-internal/src/GHC/Internal/Unicode/Bits.hs - libraries/ghci/GHCi/CreateBCO.hs - libraries/ghci/GHCi/ResolvedBCO.hs - rts/HeapStackCheck.cmm - rts/IOManager.c - rts/PrimOps.cmm - rts/RtsSymbols.c - rts/Threads.c - rts/eventlog/EventLog.c - rts/include/rts/storage/TSO.h - rts/include/stg/MiscClosures.h - rts/win32/AsyncMIO.c - rts/win32/AsyncMIO.h - + testsuite/tests/concurrent/should_run/T26341.hs - + testsuite/tests/concurrent/should_run/T26341.stdout - + testsuite/tests/concurrent/should_run/T26341a.hs - + testsuite/tests/concurrent/should_run/T26341a.stdout - + testsuite/tests/concurrent/should_run/T26341b.hs - + testsuite/tests/concurrent/should_run/T26341b.stdout - testsuite/tests/concurrent/should_run/all.T - testsuite/tests/count-deps/CountDepsAst.stdout - testsuite/tests/count-deps/CountDepsParser.stdout - testsuite/tests/ghci/scripts/ListTuplePunsPpr.stdout - testsuite/tests/ghci/scripts/T10963.stderr - testsuite/tests/ghci/scripts/ghci064.stdout - testsuite/tests/interface-stability/base-exports.stdout - testsuite/tests/interface-stability/base-exports.stdout-javascript-unknown-ghcjs - testsuite/tests/interface-stability/base-exports.stdout-mingw32 - testsuite/tests/interface-stability/base-exports.stdout-ws-32 - + testsuite/tests/simplCore/should_compile/T19166.hs - + testsuite/tests/simplCore/should_compile/T19166.stderr - + testsuite/tests/simplCore/should_compile/T25718.hs - + testsuite/tests/simplCore/should_compile/T25718.stderr - + testsuite/tests/simplCore/should_compile/T25718a.hs - + testsuite/tests/simplCore/should_compile/T25718a.stderr - + testsuite/tests/simplCore/should_compile/T25718b.hs - + testsuite/tests/simplCore/should_compile/T25718b.stderr - + testsuite/tests/simplCore/should_compile/T25718c.hs - + testsuite/tests/simplCore/should_compile/T25718c.stderr-ws-32 - + testsuite/tests/simplCore/should_compile/T25718c.stderr-ws-64 - testsuite/tests/simplCore/should_compile/all.T - utils/deriveConstants/Main.hs The diff was not included because it is too large. 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