Sylvain Henry pushed to branch wip/andreask/cfg-fix at Glasgow Haskell Compiler / GHC Commits: 8c947573 by Simon Peyton Jones at 2026-10-16T13:11:53+01:00 Improve exprOkForSpeculation Fixes #27910, which exposed an infelicity in exprOkForSpeculation The new story is carefully described in new Note [exprOkForSpeculation], esp (a-c) and (EOKS1). - - - - - 7dedcf13 by Alan Zimmerman at 2026-10-16T19:03:17-04:00 EPA: Add TTG fields to FamilyInfo This commit is a simple add, with unused extension fields. It lays the groundwork for using them for exact print annotations - - - - - 26b9a8a0 by Arkissa at 2026-10-17T16:04:10+00:00 ghci: Prefer exact source spans in :type-at Prefer expression types for identical source spans. Fixes #27412. - - - - - 70dc4e61 by sheaf at 2026-10-18T18:15:15-04:00 Carefully implement coercion zapping This commit implements coercion zapping in the rewriter, controlled by the -fzap-coercions flag (on by default). This significantly reduces the size of coercions produced when rewriting type family applications, resulting in much faster compilation. See Note [Coercion zapping] in GHC.Tc.Solver.Rewrite for an explanation and further details. The rewriter now keeps track of the `CoVar`s and `CoercionHole`s it uses when rewriting, which allows computing the dependencies of a zapped coercion without traversing the coercion the rewriter produced, as explained in Note [Computing coercion dependencies] in GHC.Tc.Solver.Rewrite. Accompanying changes: - Rework how dependencies of 'UnivCo's are tracked, purely for performance reasons. We now use the 'UnivCoDeps' datatype instead of '[Coercion]', and we now insist that 'uco_deps' also contains the CoVars that appear in the LHS and RHS types of the UnivCo (as a caching mechanism). - Several performance improvements to the rewriter (e.g. increased strictness). - Improvements to the family application cache, including: - Better documentation. - Only cache a whole chain of reduction steps. - Don't put coercion holes in the cache, fixing #27518. - Allow Core Lint to be called from within the typechecker (and from within the coercion optimiser). - Move out "annotation linting" from Core Lint into the general Core pipeline, to avoid the dependency GHC.Core.Coercion.Opt->GHC.Core.Lint causing a regression in CountDepsParser due to transitive dependencies of GHC.Core.Opt.Monad and GHC.Unit.Module.ModGuts. Fixes #8095 #27336 #27518 Summary of performance numbers Compile-time byte allocated in GHC's testsuite (0 regressions) CoOpt_Singletons(normal) ghc/alloc 634,040,332 595,448,728 -6.1% GOOD FamAppCachePerf(normal) ghc/alloc 495,629,812 191,612,920 -61.3% GOOD LargeRecord(normal) ghc/alloc 1,226,806,434 966,260,976 -21.2% GOOD SimplCastPerf(normal) ghc/alloc 160,505,678 148,112,688 -7.7% GOOD T12227(normal) ghc/alloc 244,668,982 233,037,216 -4.8% GOOD T12545(normal) ghc/alloc 697,804,842 424,705,152 -39.1% GOOD T13386(normal) ghc/alloc 422,871,076 35,213,656 -91.7% GOOD T15703(normal) ghc/alloc 288,402,364 273,692,560 -5.1% GOOD T26426(normal) ghc/alloc 86,002,052 78,152,104 -9.1% GOOD T27336(normal) ghc/alloc 498,932,268 35,886,016 -92.8% GOOD T5030(normal) ghc/alloc 117,057,706 88,785,648 -24.2% GOOD T5321Fun(normal) ghc/alloc 252,552,628 243,820,176 -3.5% GOOD T8095(normal) ghc/alloc 768,198,564 127,779,520 -83.4% GOOD T9872a(normal) ghc/alloc 1,655,675,020 1,406,017,008 -15.1% GOOD T9872b(normal) ghc/alloc 1,864,180,628 1,644,706,696 -11.8% GOOD T9872b_defer(normal) ghc/alloc 2,834,585,468 1,657,729,760 -41.5% GOOD T9872c(normal) ghc/alloc 1,572,573,116 1,354,055,424 -13.9% GOOD T9872d(normal) ghc/alloc 351,516,004 331,071,424 -5.8% GOOD TcPlugin_RewritePerf(normal) ghc/alloc 2,063,065,680 1,847,464,272 -10.5% GOOD Chesskell (github.com/Proxymoron461/chesskell/issues) Typechecking that the first N plies of kholmovVsBronsteinShort are a valid chess game: Plies | GHC 9.14 time/alloc | This commit time/alloc | -----:|---------------------|------------------------| 2 | 41s/20GB | 0.2s/19MB | 4 | 95s/49GB | 0.3s/25MB | 6 | timed out | 0.6s/522MB | 8 | timed out | 7s/673MB | 10 | timed out | timed out | Compilation of singletons-base: compile time -28%, allocations -25% ------------------------- Metric Decrease: CoOpt_Singletons FamAppCachePerf LargeRecord SimplCastPerf T12227 T12545 T13386 T15703 T24984 T26426 T27336 T5030 T5321Fun T8095 T9872a T9872b T9872b_defer T9872c T9872d TcPlugin_RewritePerf ------------------------- Co-Authored-By: Sylvain Henry <sylvain@haskus.fr> - - - - - 3d326d7d by Sylvain Henry at 2026-10-18T18:16:09-04:00 JS: fix stack corruption in h$ap_gen_fast's pushAllRegs (#27624) The loop added in 9e46990976 ("JS: support more than 128 registers (#26558)") pushed register N to stack[sp - N - 2] while the switch it falls through into, and every reader of the h$ap_gen frame, uses stack[sp - (N - 2)]. Registers >= R32 were therefore written 4 slots too low: the slots the readers consult were left stale and the frame below was silently corrupted. Fix the loop to use the same slot formula as the switch, and add a regression test: an unknown call to a thunk with 35 argument register slots, which goes through the generic apply. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com> - - - - - 6bbca569 by Andreas Klebinger at 2026-10-21T10:01:10+00:00 Fix a few tag inference bugs. * Treat bottoming functions and nullary join points as functions. * When generating bytecode don't rely on imported tag sigs. Fixes #27831, #27841 and #27842. - - - - - 71808e29 by Sylvain Henry at 2026-10-22T04:50:24-04:00 Add GHC.Internal.Unboxed.Do: do-notation for unboxed values (#27944) QualifiedDo operators can be representation-polymorphic: a do-block is expanded into ordinary applications before typechecking, and the only check on a bound variable is the deferred fixed-runtime-rep check. A representation-polymorphic (>>=) cannot be defined directly, though, because its body would bind a variable of unknown representation. The new module provides such operators for State#-passing code as methods of a class indexed by RuntimeRep, with one instance per representation. With optimisation the dictionaries disappear and a block compiles to the usual nested case expressions: Ubx.do { x <- readWordArray# mba 0# -- x :: Word# ; writeWordArray# mba 1# x -- unit actions are statements ; Ubx.pure x } Also add users guide documentation and tests. Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com> - - - - - 33247780 by Sylvain Henry at 2026-10-22T04:50:24-04:00 Bignum: use Ubx.do for State#-passing code (#27944) Rewrite the State#-passing code of the GHC.Internal.Bignum modules (Primitives, WordArray, BigNat, Natural, Integer, Backend.Native, Backend.GMP) with the qualified do-notation of GHC.Internal.Unboxed.Do. Nested case chains such as case newWordArray# sz s of { (# s, mwa #) -> case act mwa s of { s -> unsafeFreezeByteArray# mwa s }} become Ubx.do mwa <- newWordArray# sz act mwa unsafeFreezeByteArray# mwa The optimised Core is unchanged (compared per top-level binding). BigNat now enables MonoLocalBinds: local loops written with Ubx.do must stay monomorphic in the state type, otherwise GHC does not turn them into join points. Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com> - - - - - 593f5f5b by Sylvain Henry at 2026-10-22T04:51:16-04:00 JS: remove archive padding after wasm objects (#25665) On Darwin hosts, emar (llvm-ar) writes archives in the Darwin format when the first member is not a known object file, which is the case for the archives of the JS backend. This format pads each member to 8 bytes with '\n' and includes the padding in the member size. Wasm objects do not accept trailing bytes: wasm-ld failed with "section too large". The JS linker now removes this padding when it extracts a wasm object from an archive. In addition, Hadrian passes --format=gnu to emar for the JS target. See Note [Wasm objects in Darwin archives]. Also document the format of Cc (wasm) objects in Note [Cc object format]. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> - - - - - 13dff5d0 by L0neGamer at 2026-10-22T21:37:31-04:00 add options for resizing bytearrays (#27244) add five mutable bytearray resizing operations for various kinds of pinnedness and aligning. - prefer unpinned when allocating new array (``resizeMutableByteArrayPreferUnpinned#``; the ``resizeMutableByteArray#`` default) - prefer pinned when allocating new array (``resizeMutableByteArrayPreferPinned#``) - prefer aligned and pinned when allocating new array (``resizeMutableByteArrayPreferAlignedPinned#``) - prefer same as input bytearray when allocating new array (``resizeMutableByteArrayKeepPinnedness#``) - ensure the output array is aligned and pinned after operation (``resizeMutableByteArrayMakeAlignedPinned#``) - - - - - 0c17201c by Sylvain Henry at 2026-10-22T21:38:23-04:00 JS: implement performMinorGC and performBlockingMajorGC (#28012) GHC.Internal.System.Mem imports three C entry points: performMajorGC, performGC (for performMinorGC) and performBlockingMajorGC. The JS RTS only defined h$performMajorGC, so calling performMinorGC or performBlockingMajorGC threw "ReferenceError: h$performGC is not defined" at runtime. The JS RTS has a single non-generational collector, so both missing entry points are now aliases of h$performMajorGC. Add a test that calls every GC entry point of System.Mem. Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com> - - - - - 7a631ff2 by L0neGamer at 2026-10-23T09:11:39-04:00 Mon(a|oi)d of No (Return|Mappend) progress (!15795) Make non-canonical definitions of return and mappend non-suppressible errors, and make canonical definitions of those methods warnings. CLC proposal: https://github.com/haskell/core-libraries-committee/issues/328 - - - - - 14656fd4 by Simon Jakobi at 2026-10-23T09:12:27-04:00 Cmm: keep the CBE substitution idempotent When blocks are merged over multiple rounds during common block elimination, a block that won a merge in an earlier round can still lose a merge in a later round. The substitution map (Subst) used to record this as a chain: the earlier loser mapped to a block that was itself eliminated. In PLT terminology, the substitution became *non-idempotent*. Applying such a substitution with a single lookup left edges to unreachable blocks in the Cmm graph, eventually leading to a setInfoTableStackMap panic (#27368). With this patch, each round's fresh substitutions are applied to the old ones as they are added (extendSubst), so every eliminated block maps directly to its final replacement and the substitution stays idempotent. Fixes #27368. Assisted-by: Claude Fable 5.1 - - - - - 92848e61 by Evgeny Malyshev at 2026-10-23T20:26:04-04:00 hadrian: Include transitive dependencies in Haddock builds Haddock needs indirect dependency interfaces to resolve references to definitions outside a package's direct dependencies. Expose Cabal's configured dependency closure through ContextData and use it alongside the direct list, preserving direct-interface precedence. Bump Shake's cache version for the serialized oracle change. Add a Hadrian selftest requiring template-haskell's indirect ghc-prim interface. Fixes #25850. Fixes #27786. Assisted-By: OpenAI Codex Metric Increase: haddock.Cabal - - - - - 5e8ae81b by Zubin Duggal at 2026-10-23T20:26:47-04:00 WinIO: Don't confuse Win32 errors and NTSTATUS codes WinIO misinterpreted NTSTATUS codes as Win32 errors, and had some ad hoc logic to deal with this. However, this logic was incomplete and resulted in the mishandling of results of certain I/O operations (see testcase). Now the `ErrCode` argument in `CompletionCallback` is always the Win32 error code, and we convert the NTSTATUS using RtlNtStatusToDosError. Also when an overlapped/async operation such as ReadFile fails immediately, with a Win32 error such as ERROR_BROKEN_PIPE, we don't get a further completion notification, so we never recorded the failure. This worked by coincidence earlier, because `STATUS_PENDING` happened to have the same numerical code as `ERROR_NO_MORE_ITEMS`, but it doesn't now that we translate `STATUS_PENDING` into the correct Win32 error code (`ERROR_IO_PENDING`). Fix this by using the Win32 error value we obtained when an operation returns `STATUS_PENDING`. Fixes #27971 - - - - - c42ed66a by Martijn Bastiaan at 2026-10-24T16:00:42+02:00 Add single-threaded test for #27526 + #27123 Issue #27526 is a duplicate of #27123, which has already been fixed in HEAD. The proposed patch in the former carries a "nicer" regression test in that it doesn't rely on multi-threading to trigger. Closes #27526 - - - - - 7f73f515 by Simon Peyton Jones at 2026-10-24T17:29:19-04:00 Refactor QuickLook a bit This MR simply refactors QuickLook a bit. In particular, it simplifies `tcApp`, and moves shared code into `finishApp`. It also adds `Note [QuickLook: arguments before result]` responding to #26599. There should be no user-visible changes, except perhaps in error messages, which improve marginally. For some reason T24984 compiles 8% faster. I'll take the win! Metric Decrease: T24984 - - - - - a4a3a964 by Alan Zimmerman at 2026-10-24T17:30:03-04:00 EPA: Use AnnList for XClosedTypeFamily We now have TTG annotations for FamilyInfo. Make use of it to store the AnnList annotations for a closed type family. - - - - - 953e4c7f by sheaf at 2026-10-26T18:19:10-04:00 Rework LogQueue to be a proper queue Now 'LogQueue' uses a 'TQueue' with a separate 'TVar' to indicate whether the log queue is finished logging, instead of the previous weird data representation using a reverse-order '[Maybe Msg]' with 'Nothing' denoting the end of the queue. - - - - - ec29c5fa by Rodrigo Mesquita at 2026-10-26T18:19:10-04:00 Refactor GHC.Driver.MakeAction Pull out of 'runParPipelines' the logic for creating a 'MakeEnv' ready to be used by multiple threads, as that will be useful for downsweep as well (which doesn't fit the 'runPipelines' flow), rather than being just for upsweep. The code is moved and re-structured to match the export list, simplify the sequentiality checks previously both in 'runPipelines' and 'runAllPipelines', which were weirdly similar and confusing; into the two part step where we need these checks: (1) to construct the MakeEnv, (2) to run the MakeActions in parallel. These two steps are separate and used to be too mixed up. Some additional little simplifications or clean ups here and there. - - - - - 3fb22073 by Rodrigo Mesquita at 2026-10-26T18:19:11-04:00 Refactor GHC.Driver.Downsweep in preparation for parallel downsweep Pure refactor to improve the code to facilitate implementing parallel downsweep in the next commit. This commit puts a MakeEnv into the DownsweepEnv, gives the fields proper names and uses RecordWildcards to simplify, rather than passing around all diagnostic wrappers, driver-message-things and using 10s of positional fields. No behavior changes here! - - - - - 52f385a7 by sheaf at 2026-10-26T18:19:11-04:00 Driver: enableCodeGenForTH in load', not downsweep enableCodeGenForTH modifies the module graph for planning, creating fresh temporary paths. So it should only be run when we are about to execute a build plan (e.g. in load'), so that consumers that want to know facts about the module graph don't go looking for files that don't exist yet (in particular 'haddock --no-compilation'). - - - - - 82402d14 by sheaf at 2026-10-26T18:19:11-04:00 2-phase Cache/Search Finder monad This commit restructures the finder abstraction by introducing the 'FinderM' monad, which splits module lookup operations into two phases: - a cache-only phase, performing no filesystem access, - from the first cache miss onwards, a search action which may access the filesystem. This allows consumers to distinguish between quick cached results versus more expensive filesystem search operations. - - - - - 5c302b40 by sheaf at 2026-10-26T18:19:11-04:00 Separate Home/External finder caches The caches for home modules and modules from external units have different lifetimes, needing to be invalidated at different points. This commit moves the cache for modules from external units into the 'UnitState' type, which keeps the cache correct whenever package flags or package databases change (setSessionDynFlags, :set -package ..., Backpack's addUnit). This also makes it easier to clear the cache of home modules, as they are now stored separately (obviating the 'isUnitEnvInstalledModule' check we used to perform). - - - - - 605fbb96 by sheaf at 2026-10-26T18:19:11-04:00 Add known home modules to the finder cache The finder looks in the file system for the on-disk source that corresponds to a Haskell module name. There are two kinds of modules where we need to bypass this search: - a file passed directly in the command line, which may not be in any search path and whose module name may differ from the file name; - Backpack signatures and modules, which do not exist as files at all. This commit handles these two situations by adding an immutable 'KnownHomeModules' in the finder cache, which is always consulted first before doing any search. This removes the ad-hoc imperative logic which relied on mutating the finder cache at careful points. 'setModuleGraph' now also takes the known home modules, so that the module graph and the known home modules are always set consistently. See Note [Known home modules] in GHC.Unit.Finder.Types. - - - - - 82718f44 by sheaf at 2026-10-26T18:19:11-04:00 Make 'UnresolvedImport' into a suitable cache key The goal of this commit is to make 'UnresolvedImport' suitable for use as a cache key. Specifically, during downsweep we want to be able to cache module resolution queries. We want to do this using some kind of map, e.g. (roughly speaking): Map UnresolvedImport ResolvedImport For this to work, 'UnresolvedImport' must contain **precisely** the input data to each resolution computation. In other words: 1. If something changes that materially affects resolution, it must be stored in the cache key. 2. If changing some input does not materially affect the outcome, then it must not be stored in the cache key. To satisfy (1), we change 'UnitNode' to also keep track of the home unit in whose unit state the unit's dependencies were looked up. For (2), 'ImportResolution' now stores a 'ModuleLookupScope' instead of an 'UnresolvedImportOrigin'. Plugin imports are expressed with a new 'LookupPlugin' scope. The source location of an import, which is immaterial to the resolution, is stored out of band outside 'UnresolvedImport', in 'ModSummary'. - - - - - d4635c7c by sheaf at 2026-10-26T18:19:11-04:00 Add GHC.Data.Dependent This commit adds a minimal implementation of dependent sums ('Some', 'DSum') and dependent maps ('DMap'). The implementation is not entirely performance optimal, as there are a few extraneous allocations compared to the full-blown implementation in the 'dependent-map' package. For our use case (caching downsweep computations), this does not matter much. See GHC.Data.Dependent. - - - - - 6759533e by sheaf at 2026-10-26T18:19:11-04:00 Driver: structured concurrent worker abstraction This commit introduces a structured concurrency framework in the style of the 'ki' library: a collection of threads within a scope. We implement two kinds of concurrent workers on top of this framework: - Independent workers cannot wait for one another at all. The only scheduling operation is to wait for quiescence. - Coordinating workers declare an STM readiness condition (waiting on other workers to complete) which gates their start. See Note [Deterministic concurrent workers] in GHC.Driver.Concurrency. This commit ports upsweep to this new framework, with downsweep being left as subsequent work. Further changes along the way: - Refactoring of how concurrency is acquired to avoid the footgun of trying to use a no-op 'AbstractSem' as a lock in the serial case. - The "re-run with -j1" logic for semaphore opening errors no longer triggers on late semaphore failures (part-way through a lengthy computation). - Logger threads are properly cleaned up on exception, with each concurrent worker's log queue and local TmpFs properly bracketed. - The 'GhcMessage -> AnyGhcDiagnostic' and 'Maybe Messager' arguments of 'depanalE', 'depanalPartial' and 'downsweep', which were all dead in practice, have been dropped. - Concurrent logging has been completely overhauled. Each worker has its own log queue. Workers whose logs are printed as we go are spawned in the order in which their logs must be printed, now using a TQueue instead of the old complicated LogQueueQueue mechanism. 'logThread' is replaced by 'withLogPrinter', which runs the thread that prints the log queues within a concurrent worker scope. These changes allow us to fix issues with the exception handling: we now always flush remaining log queues before exiting (even when the action throws an exception), and exceptions that arise while printing are properly rethrown. This fixes #28009. - - - - - 38a99006 by sheaf at 2026-10-26T18:19:11-04:00 Rule-based deterministic concurrent downsweep This commit rewrites downsweep as a single query-answering rule (see 'DownsweepRule') that can be executed by concurrent worker threads. The design allows every expensive operation (preprocessing files with CPP, parsing headers, reading interfaces) to be performed concurrently according to the -j<N>/-jsem flags. See Note [Rules-based downsweep] in GHC.Driver.Downsweep. The rules are run by "GHC.Driver.Concurrency.runRules" in a demand-driven way: each worker can demand other workers to run, but never wait on another worker. Every piece of work is done at most once. Fixes #27514 Memory usage can increase due to doing more work concurrently: ------------------------- Metric Increase: MultiComponentModulesRecomp MultiComponentModulesRecomp100 mhu-perf ------------------------- - - - - - 9fa7b7be by sheaf at 2026-10-26T18:19:11-04:00 Acquire/release semaphore tokens more readily This commit reworks GHC.Driver.MakeSem to use the scoped worker abstraction of GHC.Utils.Concurrent.Scope. This allows us to get rid of a lot of the tricky logic in GHC.Driver.MakeSem involving manual exception handling, thread spawning and lifetime management, etc. The main user-visible change is that token acquisition is no longer rate limited (due to a bug, there previously was a 1s rate limit on acquisition of semaphore tokens), with the release debounce period shortened from 1s to 10ms. Other changes: - With -jsem, the number of capabilities is now capped at the number of processors, bringing it in line with the -jN behaviour. - Pending jobs whose wait for a token is interrupted by an exception are now withdrawn from the jobserver, instead of acquiring a token that it hung onto without doing useful work. Fixes #27763 - - - - - c83c6733 by Alan Zimmerman at 2026-10-26T18:19:55-04:00 EPA: Update AnnClsInstDecl to contain AnnList It was already separately tracking the '{', '}' and leading ';' values. This aligns it with layout-introducing parser productions ('vocurly'), so the layout processing can be handled uniformly - - - - - ac870ad5 by Simon Jakobi at 2026-10-28T04:40:42-04:00 X86 NCG: use 32-bit POPCNT for sub-word popcounts A 32-bit write zero-extends the result to the full register, so we don't need to emit additional code for this. We also skip emitting zero-extension instructions for the argument when it is already visibly zero-extended. For the byte-wise popcount loop from #24813, this shrinks the popcount sequence from 5 instructions to 3. Assisted-by: Claude Fable 5.1 - - - - - 53087373 by Facundo Domínguez at 2026-10-28T04:41:32-04:00 Use a ShortByteString in Serialized instead of [Word8] This makes the in-memory representation 40x more compact for all values stored in annotations. A test is added to measure the representation size of annotations specified in the compiler input. The GHC API is modified. All functions that previously handled annotations in [Word8] form now use ShortByteString. The following definitions have modified types: * GHC.findGlobalAnns * GHC.Tc.Gen.Splice.getAnnotationsByTypeRep * GHC.Core.Opt.Monad.getAnnotations * GHC.Core.Opt.Monad.getFirstAnnotations * GHC.Types.Annotations.deserializeAnns * GHC.Types.Annotations.findAnns * GHC.Types.Annotations.findAnnsByTypeRep * GHC.Serialized.Serialized * GHC.Serialized.toSerialized * GHC.Serialized.fromSerialized * GHC.Serialized.serializeWithData * GHC.Serialized.deserializeWithData * GHCi.Message.ReifyAnnotations Fixes #28002. - - - - - 9803f87b by Andreas Klebinger at 2026-10-29T09:42:30+01:00 x86 ncg: Track the current block in NatM to keep the CFG in sync The x86 NCG maintains a CFG that is used for code layout. Whenever instruction selection introduces new basic blocks (for instance for word-to-float conversions, cmpxchg based atomic operations, ctz on i386 or 64-bit shifts on i386) it must update this CFG, and the code that follows must use the new block as its origin. Before this patch the current block was threaded explicitly through some statement-level functions only. Block-introducing primops that were dispatched as "simple" (word2Float#, #27915) and the 64-bit shifts in iselExpr64 did not update the CFG at all. This resulted in an out-of-sync CFG, bad code layout and the "Can't find weight for edge that should have one" panic once the register allocator inserted fixup blocks (#27694, #27915). We now keep the current block in the NatM state and provide a few combinators (continueInNewBlock, addCondBlock, addDiamondFlow, addColdSelfLoop, increaseEdgeWeight) that update the CFG and the current block at the same time. See Note [Updating the CFG during CodeGen] in GHC.CmmToAsm.Monad. The cfg sanity check (-dasm-lint) now also checks that all branches in the generated code have a matching edge in the CFG, which catches this class of bug early. It immediately found another desync: when the register allocator needs more stack than preallocated, allocMoreStack moves the body of every entry block into a new block and retargets the local jumps to it, but the CFG only recorded the new block as the immediate successor of the entry block. The new addPreentryBlock also redirects the jump edges (and keeps the call edges, since returns still go through the entry block). Fixes #27694, #27915 Co-authored-by: Sylvain Henry <sylvain@haskus.fr> Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com> - - - - - 377 changed files: - + changelog.d/25665 - + changelog.d/25850 - + changelog.d/27368 - + changelog.d/27624 - + changelog.d/27694 - + changelog.d/27971 - + changelog.d/28012 - + changelog.d/T27412 - + changelog.d/T27763 - + changelog.d/T27831-bottoming-strict-field - + changelog.d/T27842-bytecode-imported-tags - + changelog.d/T28002 - + changelog.d/T28002-api - + changelog.d/monad-of-no-return-canonical - + changelog.d/ncg-x86-subword-popcnt - + changelog.d/parallel-downsweep - + changelog.d/resizeMutableByteArray-pinnedness - + changelog.d/unboxed-do - + changelog.d/zap-coercions - compiler/GHC.hs - compiler/GHC/Builtin.hs - compiler/GHC/Builtin/primops.txt.pp - compiler/GHC/ByteCode/Asm.hs - compiler/GHC/Cmm/CommonBlockElim.hs - compiler/GHC/CmmToAsm.hs - compiler/GHC/CmmToAsm/AArch64/CodeGen.hs - compiler/GHC/CmmToAsm/BlockLayout.hs - compiler/GHC/CmmToAsm/CFG.hs - compiler/GHC/CmmToAsm/CFG/Dominators.hs - compiler/GHC/CmmToAsm/Monad.hs - compiler/GHC/CmmToAsm/X86/CodeGen.hs - compiler/GHC/CmmToAsm/X86/Instr.hs - compiler/GHC/CmmToLlvm/CodeGen.hs - compiler/GHC/Core.hs - compiler/GHC/Core/Coercion.hs - compiler/GHC/Core/Coercion.hs-boot - compiler/GHC/Core/Coercion/Opt.hs - compiler/GHC/Core/FamInstEnv.hs - compiler/GHC/Core/Lint.hs - + compiler/GHC/Core/Lint.hs-boot - compiler/GHC/Core/Opt/Monad.hs - compiler/GHC/Core/Opt/Pipeline.hs - compiler/GHC/Core/Reduction.hs - compiler/GHC/Core/SimpleOpt.hs - compiler/GHC/Core/TyCo/FVs.hs - compiler/GHC/Core/TyCo/FVs.hs-boot - compiler/GHC/Core/TyCo/Make.hs - compiler/GHC/Core/TyCo/Rep.hs - compiler/GHC/Core/TyCo/Rep.hs-boot - compiler/GHC/Core/TyCo/Subst.hs - compiler/GHC/Core/TyCo/Tidy.hs - compiler/GHC/Core/Type.hs - compiler/GHC/Core/Utils.hs - compiler/GHC/CoreToIface.hs - + compiler/GHC/Data/Dependent.hs - compiler/GHC/Data/FastString.hs - compiler/GHC/Data/OrdList.hs - compiler/GHC/Data/Pair.hs - compiler/GHC/Data/Word64Map/Internal.hs - compiler/GHC/Data/Word64Set/Internal.hs - compiler/GHC/Driver/Backpack.hs - compiler/GHC/Driver/CmdLine.hs - + compiler/GHC/Driver/Concurrency.hs - compiler/GHC/Driver/Config.hs - + compiler/GHC/Driver/Config/Concurrency.hs - compiler/GHC/Driver/Config/Core/Lint.hs - compiler/GHC/Driver/Downsweep.hs - compiler/GHC/Driver/DynFlags.hs - compiler/GHC/Driver/Env.hs - compiler/GHC/Driver/Errors/Ppr.hs - compiler/GHC/Driver/Errors/Types.hs - compiler/GHC/Driver/Flags.hs - compiler/GHC/Driver/Main/Passes.hs - compiler/GHC/Driver/Make.hs - compiler/GHC/Driver/MakeAction.hs - compiler/GHC/Driver/MakeFile.hs - compiler/GHC/Driver/MakeSem.hs - compiler/GHC/Driver/Pipeline/Execute.hs - compiler/GHC/Driver/Pipeline/LogQueue.hs - compiler/GHC/Driver/Session.hs - compiler/GHC/Hs/Decls.hs - compiler/GHC/Hs/Dump.hs - compiler/GHC/Hs/Utils.hs - compiler/GHC/HsToCore/Pmc/Types.hs - compiler/GHC/HsToCore/Quote.hs - compiler/GHC/Iface/Ext/Ast.hs - compiler/GHC/Iface/Load.hs - compiler/GHC/Iface/Recomp.hs - compiler/GHC/Iface/Rename.hs - compiler/GHC/Iface/Syntax.hs - compiler/GHC/Iface/Type.hs - compiler/GHC/IfaceToCore.hs - compiler/GHC/JS/Opt/Simple.hs - compiler/GHC/Linker/Deps.hs - compiler/GHC/Parser.y - compiler/GHC/Parser/Header.hs - compiler/GHC/Parser/PostProcess.hs - compiler/GHC/Rename/Env.hs - compiler/GHC/Rename/Module.hs - compiler/GHC/Runtime/Eval/Types.hs - compiler/GHC/Runtime/Interpreter/JS.hs - compiler/GHC/Runtime/Loader.hs - compiler/GHC/Stg/EnforceEpt.hs - compiler/GHC/Stg/EnforceEpt/Rewrite.hs - compiler/GHC/Stg/EnforceEpt/TagSig.hs - compiler/GHC/Stg/EnforceEpt/Types.hs - compiler/GHC/StgToCmm/Prim.hs - compiler/GHC/StgToJS/Apply.hs - compiler/GHC/StgToJS/Linker/Linker.hs - compiler/GHC/StgToJS/Object.hs - compiler/GHC/StgToJS/Prim.hs - compiler/GHC/Tc/Deriv/Generate.hs - compiler/GHC/Tc/Errors/Ppr.hs - compiler/GHC/Tc/Errors/Types.hs - compiler/GHC/Tc/Gen/App.hs - compiler/GHC/Tc/Gen/Splice.hs - compiler/GHC/Tc/Instance/Family.hs - compiler/GHC/Tc/Module.hs - compiler/GHC/Tc/Plugin.hs - compiler/GHC/Tc/Solver/Default.hs - compiler/GHC/Tc/Solver/Equality.hs - compiler/GHC/Tc/Solver/InertSet.hs - compiler/GHC/Tc/Solver/Monad.hs - compiler/GHC/Tc/Solver/Rewrite.hs - compiler/GHC/Tc/Solver/Solve.hs - compiler/GHC/Tc/TyCl.hs - compiler/GHC/Tc/Types.hs - compiler/GHC/Tc/Types/Constraint.hs - compiler/GHC/Tc/Utils/Backpack.hs - compiler/GHC/Tc/Utils/TcMType.hs - compiler/GHC/ThToHs.hs - compiler/GHC/Types/Annotations.hs - compiler/GHC/Types/Basic.hs - compiler/GHC/Types/Error/Codes.hs - compiler/GHC/Types/Hint.hs - compiler/GHC/Types/Hint/Ppr.hs - compiler/GHC/Types/Unique/DSet.hs - compiler/GHC/Types/Unique/FM.hs - compiler/GHC/Types/Unique/Map.hs - compiler/GHC/Types/UnresolvedImport.hs - compiler/GHC/Types/Var/Set.hs - compiler/GHC/Unit/External/ModuleOrigin.hs - compiler/GHC/Unit/External/Visibility.hs - compiler/GHC/Unit/Finder.hs - + compiler/GHC/Unit/Finder/Cache.hs - compiler/GHC/Unit/Finder/Types.hs - compiler/GHC/Unit/Module/Graph.hs - compiler/GHC/Unit/Module/ModSummary.hs - compiler/GHC/Unit/Module/WholeCoreBindings.hs - compiler/GHC/Unit/State.hs - compiler/GHC/Unit/Types.hs - + compiler/GHC/Utils/Concurrent/Scope.hs - compiler/GHC/Utils/Monad/Codensity.hs - compiler/GHC/Utils/Outputable.hs - compiler/GHC/Utils/Ppr/Colour.hs - compiler/GHC/Utils/TmpFs.hs - compiler/Language/Haskell/Syntax/Decls.hs - compiler/Language/Haskell/Syntax/Extension.hs - compiler/ghc.cabal.in - docs/users_guide/extending_ghc.rst - docs/users_guide/exts/qualified_do.rst - docs/users_guide/exts/type_families.rst - docs/users_guide/using-warnings.rst - ghc/GHCi/UI.hs - ghc/GHCi/UI/Info.hs - ghc/Main.hs - ghc/ghc-bin.cabal.in - hadrian/src/Hadrian/Haskell/Cabal/Parse.hs - hadrian/src/Hadrian/Haskell/Cabal/Type.hs - hadrian/src/Main.hs - hadrian/src/Rules/Documentation.hs - hadrian/src/Rules/Selftest.hs - hadrian/src/Settings/Builders/Ar.hs - hadrian/src/Settings/Warnings.hs - libraries/base/src/GHC/Base.hs - libraries/base/src/GHC/Exts.hs - + libraries/base/tests/IO/T27971.hs - + libraries/base/tests/IO/T27971.stdout - libraries/base/tests/IO/all.T - libraries/ghc-boot/GHC/Serialized.hs - libraries/ghc-internal/CHANGELOG.md - libraries/ghc-internal/ghc-internal.cabal.in - libraries/ghc-internal/src/GHC/Internal/Base.hs - libraries/ghc-internal/src/GHC/Internal/Bignum/Backend/GMP.hs - libraries/ghc-internal/src/GHC/Internal/Bignum/Backend/Native.hs - libraries/ghc-internal/src/GHC/Internal/Bignum/BigNat.hs - libraries/ghc-internal/src/GHC/Internal/Bignum/Integer.hs - libraries/ghc-internal/src/GHC/Internal/Bignum/Natural.hs - libraries/ghc-internal/src/GHC/Internal/Bignum/Primitives.hs - libraries/ghc-internal/src/GHC/Internal/Bignum/WordArray.hs - libraries/ghc-internal/src/GHC/Internal/Event/Windows.hsc - libraries/ghc-internal/src/GHC/Internal/Event/Windows/FFI.hsc - libraries/ghc-internal/src/GHC/Internal/IO/Windows/Handle.hsc - + libraries/ghc-internal/src/GHC/Internal/Unboxed/Do.hs - libraries/ghci/GHCi/Message.hs - libraries/ghci/GHCi/TH.hs - libraries/ghci/GHCi/TH/Binary.hs - linters/lint-codes/LintCodes/Static.hs - rts/PrimOps.cmm - rts/RtsSymbols.c - rts/include/stg/MiscClosures.h - rts/js/environment.js - testsuite/tests/ado/ado-optimal.hs - testsuite/tests/ado/ado001.hs - testsuite/tests/annotations/should_run/Makefile - + testsuite/tests/annotations/should_run/T16841.hs - + testsuite/tests/annotations/should_run/T16841.stdout - testsuite/tests/annotations/should_run/all.T - + testsuite/tests/bytecode/T27842.hs - + testsuite/tests/bytecode/T27842.stdout - + testsuite/tests/bytecode/T27842A.hs - + testsuite/tests/bytecode/T27842N.hs - testsuite/tests/bytecode/all.T - + testsuite/tests/codeGen/should_compile/T27368.hs - + testsuite/tests/codeGen/should_compile/T27694.hs - testsuite/tests/codeGen/should_compile/all.T - + testsuite/tests/codeGen/should_gen_asm/T24813.asm - + testsuite/tests/codeGen/should_gen_asm/T24813.cmm - testsuite/tests/codeGen/should_gen_asm/all.T - + testsuite/tests/codeGen/should_run/T27624.hs - + testsuite/tests/codeGen/should_run/T27624.stdout - + testsuite/tests/codeGen/should_run/T27915.hs - + testsuite/tests/codeGen/should_run/T27915.stdout-ws-32 - + testsuite/tests/codeGen/should_run/T27915.stdout-ws-64 - testsuite/tests/codeGen/should_run/all.T - testsuite/tests/concurrent/T13615/Parallel.hs - testsuite/tests/concurrent/should_run/T21651.hs - testsuite/tests/concurrent/should_run/setnumcapabilities001.hs - testsuite/tests/corelint/T27374.hs - testsuite/tests/count-deps/CountDepsParser.stdout - testsuite/tests/cpranal/should_run/T20598a.hs - testsuite/tests/dependent/should_compile/T14729.stderr - testsuite/tests/deriving/should_compile/T13758.hs - testsuite/tests/deriving/should_run/all.T - + testsuite/tests/deriving/should_run/drvrun-canonical-methods.hs - + testsuite/tests/deriving/should_run/drvrun-canonical-methods.stderr - + testsuite/tests/deriving/should_run/drvrun-canonical-methods.stdout - testsuite/tests/determinism/determ017/A.hs - testsuite/tests/diagnostic-codes/codes.stdout - testsuite/tests/dmdanal/should_compile/T9208.hs - testsuite/tests/driver/Makefile - testsuite/tests/driver/T27461/Makefile - + testsuite/tests/driver/T27461/T27461c.stderr - testsuite/tests/driver/T27461/all.T - + testsuite/tests/driver/T27461/src/Wrong.hs - + testsuite/tests/driver/T28009.hs - testsuite/tests/driver/all.T - testsuite/tests/generics/T27245.hs - testsuite/tests/generics/T27245.stdout - testsuite/tests/ghc-api/downsweep/IncrementalDownsweep.hs - testsuite/tests/ghc-api/downsweep/OldModLocation.hs - testsuite/tests/ghc-api/downsweep/PartialDownsweep.hs - testsuite/tests/ghc-api/fixed-nodes/FixedNodes.hs - testsuite/tests/ghc-api/fixed-nodes/InterfaceModuleGraph.hs - testsuite/tests/ghc-api/fixed-nodes/ModuleGraphInvariants.hs - testsuite/tests/ghci.debugger/scripts/T14628.stderr - testsuite/tests/ghci/prog-mhu001/prog-mhu001c.stdout - testsuite/tests/ghci/prog-mhu002/prog-mhu002d.stdout - testsuite/tests/ghci/scripts/T16575.script - testsuite/tests/ghci/scripts/T16575.stdout - testsuite/tests/ghci/scripts/T16804.stdout - testsuite/tests/ghci/scripts/T20150.stdout - + testsuite/tests/ghci/scripts/T27412.hs - + testsuite/tests/ghci/scripts/T27412.script - + testsuite/tests/ghci/scripts/T27412.stdout - testsuite/tests/ghci/scripts/all.T - testsuite/tests/haddock/perf/Fold.hs - testsuite/tests/haddock/should_compile_flag_haddock/T17544.stderr - testsuite/tests/hiefile/should_compile/hie002.hs - testsuite/tests/hpc/raytrace/Eval.hs - testsuite/tests/indexed-types/should_compile/T3787.hs - + testsuite/tests/indexed-types/should_compile/ZapDeps.hs - testsuite/tests/indexed-types/should_compile/all.T - testsuite/tests/indexed-types/should_fail/T7729.hs - testsuite/tests/indexed-types/should_fail/T7729a.hs - 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/javascript/Makefile - + testsuite/tests/javascript/T25665.hs - + testsuite/tests/javascript/T25665.pkg - + testsuite/tests/javascript/T25665.stdout - + testsuite/tests/javascript/T25665Lib.hs - + testsuite/tests/javascript/T25665_c.c - + testsuite/tests/javascript/T25665_js.js - testsuite/tests/javascript/all.T - testsuite/tests/module/mod133.hs - testsuite/tests/parser/should_compile/DumpParsedAst.stderr - testsuite/tests/parser/should_compile/DumpRenamedAst.stderr - testsuite/tests/parser/should_compile/KindSigs.stderr - testsuite/tests/perf/compiler/T13253.hs - testsuite/tests/perf/compiler/T14683.hs - testsuite/tests/perf/compiler/T16473.hs - testsuite/tests/perf/compiler/T18730_A.hs - testsuite/tests/perf/compiler/T25723.hs - testsuite/tests/plugins/T26761Plugin.hs - testsuite/tests/plugins/all.T - testsuite/tests/plugins/defaulting-plugin/DefaultLifted.hs - testsuite/tests/pmcheck/should_compile/T11276.hs - + testsuite/tests/primops/should_run/ResizeByteArrayPinnedness.hs - + testsuite/tests/primops/should_run/ResizeByteArrayPinnedness.stdout - testsuite/tests/primops/should_run/all.T - testsuite/tests/printer/Test24533.stdout - testsuite/tests/profiling/should_compile/T19894/StreamK.hs - testsuite/tests/profiling/should_run/T3001-2.hs - testsuite/tests/programs/galois_raytrace/Eval.hs - testsuite/tests/qualifieddo/should_compile/all.T - + testsuite/tests/qualifieddo/should_compile/qdocompile003.hs - + testsuite/tests/qualifieddo/should_compile/qdocompile003.stderr - testsuite/tests/qualifieddo/should_fail/all.T - + testsuite/tests/qualifieddo/should_fail/qdofail006.hs - + testsuite/tests/qualifieddo/should_fail/qdofail006.stderr - testsuite/tests/qualifieddo/should_run/all.T - + testsuite/tests/qualifieddo/should_run/qdorun008.hs - + testsuite/tests/qualifieddo/should_run/qdorun008.stdout - testsuite/tests/rebindable/rebindable2.hs - + testsuite/tests/rename/should_fail/Noncanonical.hs - + testsuite/tests/rename/should_fail/Noncanonical.stderr - testsuite/tests/rename/should_fail/all.T - testsuite/tests/rename/should_fail/rnfail026.hs - testsuite/tests/rep-poly/RepPolyRule3.stderr - + testsuite/tests/rts/T27526.hs - + testsuite/tests/rts/T27526.stdout - + testsuite/tests/rts/T28012.hs - + testsuite/tests/rts/T28012.stdout - testsuite/tests/rts/all.T - testsuite/tests/rts/ipe/IpeStats/Fold.hs - testsuite/tests/simplCore/should_compile/T14908_Deps.hs - testsuite/tests/simplCore/should_compile/T26051.stderr - + testsuite/tests/simplCore/should_compile/T27910.hs - + testsuite/tests/simplCore/should_compile/T27910.stderr - testsuite/tests/simplCore/should_compile/all.T - testsuite/tests/simplCore/should_compile/simpl017.hs - testsuite/tests/simplStg/should_compile/all.T - + testsuite/tests/simplStg/should_compile/inferTags005.hs - + testsuite/tests/simplStg/should_compile/inferTags005.stderr - + testsuite/tests/simplStg/should_compile/inferTags006.hs - + testsuite/tests/simplStg/should_compile/inferTags006.stderr - + testsuite/tests/simplStg/should_run/InferTags007_A.hs - + testsuite/tests/simplStg/should_run/T27831.hs - + testsuite/tests/simplStg/should_run/T27831.stdout - + testsuite/tests/simplStg/should_run/T27857.hs - + testsuite/tests/simplStg/should_run/T27857.stdout - testsuite/tests/simplStg/should_run/all.T - + testsuite/tests/simplStg/should_run/inferTags007.hs - + testsuite/tests/simplStg/should_run/inferTags007.stdout - testsuite/tests/splice-imports/SI35.hs - testsuite/tests/typecheck/should_compile/DeepSubsumption02.hs - testsuite/tests/typecheck/should_compile/T4524.hs - testsuite/tests/typecheck/should_compile/T4969.hs - testsuite/tests/typecheck/should_fail/T22707.hs - testsuite/tests/typecheck/should_fail/T22707.stderr - testsuite/tests/typecheck/should_fail/T25950.stderr - testsuite/tests/typecheck/should_fail/T7019.hs - testsuite/tests/typecheck/should_fail/T8450.stderr - testsuite/tests/typecheck/should_fail/T8603.hs - + testsuite/tests/warnings/should_compile/RedundantCanonicalMethods.hs - + testsuite/tests/warnings/should_compile/RedundantCanonicalMethods.stderr - testsuite/tests/warnings/should_compile/WarnNoncanonical.hs - testsuite/tests/warnings/should_compile/WarnNoncanonical.stderr - testsuite/tests/warnings/should_compile/all.T - utils/check-exact/ExactPrint.hs - utils/check-ppr/Main.hs - utils/haddock/haddock-api/haddock-api.cabal - utils/haddock/haddock-api/src/Haddock/Backends/Hoogle.hs - utils/haddock/haddock-api/src/Haddock/Backends/LaTeX.hs - utils/haddock/haddock-api/src/Haddock/Backends/Xhtml/Decl.hs - utils/haddock/haddock-api/src/Haddock/Convert.hs - utils/haddock/haddock-api/src/Haddock/Interface.hs - utils/haddock/haddock-api/src/Haddock/Interface/ParseModuleHeader.hs - utils/haddock/haddock-api/src/Haddock/Interface/Rename.hs - utils/haddock/haddock-api/src/Haddock/Types.hs - utils/haddock/haddock-api/src/Haddock/Utils/Json.hs - utils/haddock/haddock-library/haddock-library.cabal - utils/haddock/haddock.cabal - utils/runghc/Main.hs The diff was not included because it is too large. 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