Marge Bot pushed to branch wip/marge_bot_batch_merge_job at Glasgow Haskell Compiler / GHC Commits: ef038aae by cydparser at 2026-07-15T04:35:41-04:00 Reduce bytes allocated for `capabilities` in RTS (fixes #27487) In rts/Capability.c, `capabilities` is an array of pointers, but it was allocated as if it were an array of Capability's. - - - - - d377e83e by Cheng Shao at 2026-07-15T04:36:27-04:00 rts: fix missing UNTAG in stg_readTVarIOzh This patch fixes missing UNTAG on the current value closure read from StgTVar. UNTAG is a no-op when it's stg_TREC_HEADER_info which is word aligned; it may be a tagged closure, and reading info table from the tagged address is an unaligned load which may cause issues on platforms with strict alignment requirements. Co-authored-by: Codex <codex@openai.com> - - - - - 8ed03842 by Cheng Shao at 2026-07-15T04:36:27-04:00 rts: fix missing UNTAG in stg_control0zh_ll This patch fixes missing UNTAG on the cont closure returned by captureContinuationAndAbort. In case it's not NULL, captureContinuationAndAbort returns a tagged StgContinuation closure, in which case it must be untagged before accessing the apply_mask_frame field. In the past it worked out of luck: when apply_mask_frame was NULL then mask_frame_offset is also 0 so the control flow didn't diverge to a wrong path. Still, this is horribly wrong and will crash once StgContinuation struct is refactored and fields are shuffled around. Co-authored-by: Codex <codex@openai.com> - - - - - 5aa7000a by Cheng Shao at 2026-07-15T04:37:08-04:00 compiler: fix redundant AP thunk codegen when not using -ticky-ap-thunk This patch fixes a double negation confusion in !7525 that results in some redundant AP thunk code generation when not using -ticky-ap-thunk. Now, we use `stgToCmmUseStdApThunk` to indicate whether precomputed AP thunks in the RTS should be used, which defaults to `True`, unless `-ticky-ap-thunk` is passed. `-finfo-table-map` now also implies `-ticky-ap-thunk`, since when doing IPE profiling we want the generated AP thunks to be unique. Fixes #27502. ------------------------- Metric Decrease: T3064 ------------------------- Co-authored-by: Codex <codex@openai.com> - - - - - d43a7b7a by Brian McKenna at 2026-07-15T20:10:04+02:00 Strip ticks when desugaring bool guards The special `considerAccessible` pattern was broken when compiling with debug info. Compiling with debug info wraps expressions with `SourceNote` ticks, which broke the internals of the `desugarBoolGuard` function. Ticks are now ignored within this function. Fixes #27360 - - - - - 19e4b630 by Ben Gamari at 2026-07-15T18:28:04-04:00 base: Display ExceptionContext in WhileHandling's textual description As originally-implemented the implementation for `WhileHandling(displayExceptionAnnotation)` would display the `ExceptionContext` of the exception which it carries (as this was the behavior of `displayException`, in terms of which `displayExceptionAnnotation` was implemented). However, in 284ffab3 the definition of `SomeException(displayException)` was changed to exclude the `ExceptionContext`. This means that `WhileHandling(displayExceptionAnnotation)` fails to describe the provenance of the exception which it captures, greatly limiting its utility. Return the implementation to its originally-specified behavior by implementing `WhileHandling(displayExceptionAnnotation)` in terms of `displayExceptionWithInfo`. Fixes #27456. - - - - - 22 changed files: - + changelog.d/T27360 - + changelog.d/T27456 - + changelog.d/fix-use-std-ap-thunk - compiler/GHC/Driver/Config/StgToCmm.hs - compiler/GHC/Driver/Flags.hs - compiler/GHC/HsToCore/Pmc/Desugar.hs - compiler/GHC/StgToCmm/Bind.hs - compiler/GHC/StgToCmm/Config.hs - libraries/base/changelog.md - libraries/base/tests/T15349.stderr - libraries/ghc-internal/src/GHC/Internal/Exception/Type.hs - libraries/ghc-internal/tests/backtraces/T14532b.stdout - rts/Capability.c - rts/ContinuationOps.cmm - rts/PrimOps.cmm - testsuite/tests/codeGen/should_run/cgrun025.stderr - testsuite/tests/exceptions/T26759.stderr - testsuite/tests/ghc-e/should_fail/T18441fail7.stderr - testsuite/tests/mdo/should_fail/mdofail006.stderr - + testsuite/tests/pmcheck/should_compile/T27360.hs - testsuite/tests/pmcheck/should_compile/all.T - testsuite/tests/runghc/T7859.stderr-mingw32 Changes: ===================================== changelog.d/T27360 ===================================== @@ -0,0 +1,10 @@ +section: compiler +issues: #27360 +mrs: !16161 +synopsis: + Recognise ``considerAccessible`` under ticks (``-g``, ``-finfo-table-map``, ``-fhpc`` etc) +description: + The pattern-match checker now properly recognises ``considerAccessible`` even + when it is surrounded by ticks (e.g. debug info ticks with ``-g``, with + ``-finfo-table-map``, etc). This ensures it works as advertised, suppressing + redundant pattern-match warnings, even when it occurs under a tick. ===================================== changelog.d/T27456 ===================================== @@ -0,0 +1,8 @@ +section: base +issues: #27456 +mrs: !16275 +synopsis: + Show `ExceptionContext` in `displayExceptionAnnotation` implementation of `WhileHandling` +description: + In the past ``displayException`` (in terms of which ``WhileHandling``\'s ``displayExceptionAnnotation` is implemented) was changed to hide ``ExceptionContext``. This regressed the behavior of ``displayExceptionAnnotation`` from that which was originally specified. Restore the intended behavior of showing the ``ExceptionContext`` of the carried exception. + ===================================== changelog.d/fix-use-std-ap-thunk ===================================== @@ -0,0 +1,4 @@ +section: codegen +synopsis: Fix redundant AP thunk codegen when not using -ticky-ap-thunk +issues: #27502 +mrs: !16340 ===================================== compiler/GHC/Driver/Config/StgToCmm.hs ===================================== @@ -87,7 +87,7 @@ initStgToCmmConfig dflags mod = StgToCmmConfig , stgToCmmAvx = isAvxEnabled dflags , stgToCmmAvx2 = isAvx2Enabled dflags , stgToCmmAvx512f = isAvx512fEnabled dflags - , stgToCmmTickyAP = gopt Opt_Ticky_AP dflags + , stgToCmmUseStdApThunk = not $ gopt Opt_Ticky_AP dflags -- See Note [Saving foreign call target to local] , stgToCmmSaveFCallTargetToLocal = any (callerSaves platform) $ activeStgRegs platform } where profile = targetProfile dflags ===================================== compiler/GHC/Driver/Flags.hs ===================================== @@ -379,6 +379,7 @@ impliedGFlags = [(Opt_DeferTypeErrors, turnOn, Opt_DeferTypedHoles) ,(Opt_ByteCodeAndObjectCode, turnOn, Opt_WriteByteCode) ,(Opt_InfoTableMap, turnOn, Opt_InfoTableMapWithStack) ,(Opt_InfoTableMap, turnOn, Opt_InfoTableMapWithFallback) + ,(Opt_InfoTableMap, turnOn, Opt_Ticky_AP) ] ++ validHoleFitsImpliedGFlags -- | General flags that are switched on/off when other general flags are switched ===================================== compiler/GHC/HsToCore/Pmc/Desugar.hs ===================================== @@ -12,7 +12,8 @@ import GHC.Prelude import GHC.HsToCore.Pmc.Types import GHC.HsToCore.Pmc.Utils -import GHC.Core (Expr(Var,App)) +import GHC.Core (CoreExpr, Expr(Var,App)) +import GHC.Core.Utils (stripTicksTopE) import GHC.Data.FastString (unpackFS, lengthFS, mkFastStringShortText) import GHC.Driver.DynFlags import GHC.Hs @@ -474,24 +475,28 @@ desugarLocalBinds _binds = return GdEnd -- | Desugar a pattern guard -- @pat <- e ==> let x = e; <guards for pat <- x>@ desugarBind :: LPat GhcTc -> LHsExpr GhcTc -> DsM GrdDag -desugarBind p e = dsLExpr e >>= \case - Var y - | Nothing <- isDataConId_maybe y - -- RHS is a variable, so that will allow us to omit the let - -> desugarLPat y p - rhs -> do - (x, grds) <- desugarLPatV p - pure (PmLet x rhs `consGrdDag` grds) +desugarBind p e = + dsLExpr_stripTicks e >>= \case + Var y + | Nothing <- isDataConId_maybe y + -- RHS is a variable, so that will allow us to omit the let + -> desugarLPat y p + rhs -> do + (x, grds) <- desugarLPatV p + pure (PmLet x rhs `consGrdDag` grds) -- | Desugar a boolean guard -- @e ==> let x = e; True <- x@ desugarBoolGuard :: LHsExpr GhcTc -> DsM GrdDag desugarBoolGuard e - | isJust (isTrueLHsExpr e) = return GdEnd + | isJust (isTrueLHsExpr e) -- NB: looks through ticks -- The formal thing to do would be to generate (True <- True) -- but it is trivial to solve so instead we give back an empty -- GrdDag for efficiency - | otherwise = dsLExpr e >>= \case + = return GdEnd + + | otherwise + = dsLExpr_stripTicks e >>= \case Var y | Nothing <- isDataConId_maybe y -- Omit the let by matching on y @@ -500,6 +505,19 @@ desugarBoolGuard e x <- mkPmId boolTy pure $ sequencePmGrds [PmLet x rhs, vanillaConGrd x trueDataCon []] +-- | Desugar an expression, stripping off top-level ticks from the resulting +-- Core expression. +-- +-- This function is used instead of 'dsLExpr' when we are immediately going to +-- inspect the Core (as we do in e.g. 'desugarBoolGuard' or 'desugarBind') to +-- make sure we properly look through intervening ticks (fixing #27360). +-- +-- It's not needed when all we do is stash the resulting 'CoreExpr' into a +-- 'GrdDag', as the rest of the machinery (such as 'GHC.HsToCore.Pmc.Solver.addCoreCt') +-- looks through ticks. +dsLExpr_stripTicks :: LHsExpr GhcTc -> DsM CoreExpr +dsLExpr_stripTicks e = stripTicksTopE (const True) <$> dsLExpr e + {- Note [Field match order for RecCon] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The order for RecCon field patterns actually determines evaluation order of ===================================== compiler/GHC/StgToCmm/Bind.hs ===================================== @@ -280,7 +280,7 @@ cgRhs id (StgRhsClosure fvs cc upd_flag args body _typ) = do profile <- getProfile check_tags <- stgToCmmDoTagCheck <$> getStgToCmmConfig - use_std_ap_thunk <- stgToCmmTickyAP <$> getStgToCmmConfig + use_std_ap_thunk <- stgToCmmUseStdApThunk <$> getStgToCmmConfig mkRhsClosure profile use_std_ap_thunk check_tags id cc (nonVoidIds (dVarSetElems fvs)) upd_flag args body ------------------------------------------------------------------------ ===================================== compiler/GHC/StgToCmm/Config.hs ===================================== @@ -73,7 +73,7 @@ data StgToCmmConfig = StgToCmmConfig , stgToCmmAllowWordMul2Instr :: !Bool -- ^ Allowed to generate WordMul2 instruction , stgToCmmAllowFMAInstr :: FMASign -> Bool -- ^ Allowed to generate FMA instruction , stgToCmmAllowIntWord64X2MinMax :: !Bool -- ^ Allowed to generate min/max instructions for Int64X2/Word64X2 - , stgToCmmTickyAP :: !Bool -- ^ Disable use of precomputed standard thunks. + , stgToCmmUseStdApThunk :: !Bool -- ^ Use precomputed standard AP thunks in the RTS. , stgToCmmSaveFCallTargetToLocal :: !Bool -- ^ Save a foreign call target to a Cmm local, see -- Note [Saving foreign call target to local] for details ------------------------------ SIMD flags ------------------------------------ ===================================== libraries/base/changelog.md ===================================== @@ -33,6 +33,7 @@ * Export `labelThread` from `Control.Concurrent`.([CLC proposal #376](https://github.com/haskell/core-libraries-committee/issues/376)) * Add a new module `System.IO.OS` with operations for obtaining operating-system handles (file descriptors, Windows handles). ([CLC proposal #369](https://github.com/haskell/core-libraries-committee/issues/369)) * Evaluate backtraces for "error" exceptions at the moment they are thrown. ([CLC proposal #383](https://github.com/haskell/core-libraries-committee/issues/383)) + * Show `ExceptionContext` in `displayExceptionAnnotation` implementation of `WhileHandling` ([GHC #27456](https://gitlab.haskell.org/ghc/ghc/-/issues/27456)) * Hide implementation details when throwing exceptions in throw and throwSTM. ([CLC proposal #387](https://github.com/haskell/core-libraries-committee/issues/387)) * Change `hIsReadable` and `hIsWritable` such that they always throw a respective exception when encountering a closed or semi-closed handle, not just in the case of a file handle. ([CLC proposal #371](github.com/haskell/core-libraries-committee/issues/371)) * Annotate `onException` continuation with `WhileHandling`. ([CLC Proposal #397](https://github.com/haskell/core-libraries-committee/issues/397)) ===================================== libraries/base/tests/T15349.stderr ===================================== @@ -1,9 +1,11 @@ -T15349: Uncaught exception ghc-internal:GHC.Internal.Control.Exception.Base.NonTermination: +T15349.exe: Uncaught exception ghc-internal:GHC.Internal.Control.Exception.Base.NonTermination: <<loop>> -While handling thread blocked indefinitely in an MVar operation +While handling ghc-internal:GHC.Internal.IO.Exception.BlockedIndefinitelyOnMVar: + | + | thread blocked indefinitely in an MVar operation HasCallStack backtrace: - throwIO, called at libraries/ghc-internal/src/GHC/Internal/Control/Monad/ST/Imp.hs:58:37 in ghc-internal:GHC.Internal.Control.Monad.ST.Imp + throwIO, called at libraries\ghc-internal\src\GHC\Internal\Control\Monad\ST\Imp.hs:59:37 in ghc-internal:GHC.Internal.Control.Monad.ST.Imp ===================================== libraries/ghc-internal/src/GHC/Internal/Exception/Type.hs ===================================== @@ -84,7 +84,7 @@ data WhileHandling = WhileHandling SomeException deriving Show instance ExceptionAnnotation WhileHandling where displayExceptionAnnotation (WhileHandling e) = - "While handling " ++ case lines $ displayException e of + "While handling " ++ case lines $ displayExceptionWithInfo e of [] -> "" (l1:ls) -> -- Indent lines forward. ===================================== libraries/ghc-internal/tests/backtraces/T14532b.stdout ===================================== @@ -2,7 +2,14 @@ ghc-internal:GHC.Internal.Exception.ErrorCall: Error in Exception Handler -While handling Main Error +While handling ghc-internal:GHC.Internal.Exception.ErrorCall: + | + | Main Error + | + | My custom Backtraces: + | HasCallStack backtrace: + | throwIO, called at T14532b.hs:32:6 in main:Main + | My custom Backtraces: HasCallStack backtrace: @@ -13,7 +20,14 @@ ghc-internal:GHC.Internal.Exception.ErrorCall: Error in Exception Handler -While handling Main Error +While handling ghc-internal:GHC.Internal.Exception.ErrorCall: + | + | Main Error + | + | My custom Backtraces: + | HasCallStack backtrace: + | error, called at T14532b.hs:41:6 in main:Main + | My custom Backtraces: HasCallStack backtrace: ===================================== rts/Capability.c ===================================== @@ -413,7 +413,7 @@ void initCapabilities (void) max_n_capabilities = RtsFlags.ParFlags.nCapabilities; } - capabilities = stgMallocBytes(sizeof(Capability) * max_n_capabilities, "initCapabilities"); + capabilities = stgMallocBytes(sizeof(Capability *) * max_n_capabilities, "initCapabilities"); n_capabilities = 0; moreCapabilities(0, RtsFlags.ParFlags.nCapabilities); @@ -422,7 +422,7 @@ void initCapabilities (void) #else /* !THREADED_RTS */ n_capabilities = 1; - capabilities = stgMallocBytes(sizeof(Capability), "initCapabilities"); + capabilities = stgMallocBytes(sizeof(Capability *), "initCapabilities"); capabilities[0] = &MainCapability; initCapability(&MainCapability, 0); ===================================== rts/ContinuationOps.cmm ===================================== @@ -108,7 +108,7 @@ stg_control0zh_ll // explicit stack } W_ apply_mask_frame; - apply_mask_frame = StgContinuation_apply_mask_frame(cont); + apply_mask_frame = StgContinuation_apply_mask_frame(UNTAG(cont)); // The stack has been updated, so it’s time to apply the input function, // passing the captured continuation and a RealWorld token as arguments. ===================================== rts/PrimOps.cmm ===================================== @@ -1565,7 +1565,10 @@ stg_readTVarIOzh ( P_ tvar /* :: TVar a */ ) again: result = %acquire StgTVar_current_value(tvar); - resultinfo = %INFO_PTR(result); + // when result is stg_TREC_HEADER_info, it's word aligned so UNTAG + // is no-op; if it's a tagged closure we must UNTAG it to avoid an + // unaligned memory access + resultinfo = %INFO_PTR(UNTAG(result)); if (resultinfo == stg_TREC_HEADER_info) { goto again; } ===================================== testsuite/tests/codeGen/should_run/cgrun025.stderr ===================================== @@ -1,4 +1,4 @@ -"cgrun025" +"cgrun025.exe" ["cgrun025.hs"] GOT PATH {-# LANGUAGE ScopedTypeVariables #-} @@ -27,11 +27,16 @@ main = do trace "hello, trace" $ catch (getEnv "__WURBLE__" >> return ()) (\ (e :: SomeException) -> error "hello, error") hello, trace -cgrun025: Uncaught exception ghc-internal:GHC.Internal.Exception.ErrorCall: +cgrun025.exe: Uncaught exception ghc-internal:GHC.Internal.Exception.ErrorCall: hello, error -While handling __WURBLE__: getEnv: does not exist (no environment variable) +While handling ghc-internal:GHC.Internal.IO.Exception.IOException: + | + | __WURBLE__: getEnv: does not exist (no environment variable) + | + | HasCallStack backtrace: + | ioException, called at libraries\ghc-internal\src\GHC\Internal\System\Environment.hs:204:26 in ghc-internal:GHC.Internal.System.Environment HasCallStack backtrace: error, called at cgrun025.hs:25:75 in main:Main ===================================== testsuite/tests/exceptions/T26759.stderr ===================================== @@ -1,8 +1,13 @@ -T26759: Uncaught exception ghc-internal:GHC.Internal.Exception.ErrorCall: +T26759.exe: Uncaught exception ghc-internal:GHC.Internal.Exception.ErrorCall: cleanup failure -While handling outer failure +While handling ghc-internal:GHC.Internal.Exception.ErrorCall: + | + | outer failure + | + | HasCallStack backtrace: + | throwIO, called at T26759.hs:6:21 in main:Main HasCallStack backtrace: throwIO, called at T26759.hs:7:22 in main:Main ===================================== testsuite/tests/ghc-e/should_fail/T18441fail7.stderr ===================================== @@ -1,10 +1,12 @@ -<interactive>: Uncaught exception ghc-9.13-inplace:GHC.Utils.Panic.GhcException: +<interactive>: Uncaught exception ghc-10.1-inplace:GHC.Utils.Panic.GhcException: IO error: "Abcde" does not exist -While handling IO error: "Abcde" does not exist +While handling ghc-10.1-inplace:GHC.Utils.Panic.GhcException: + | + | IO error: "Abcde" does not exist HasCallStack backtrace: - throwIO, called at compiler/GHC/Utils/Error.hs:512:19 in ghc-9.13-inplace:GHC.Utils.Error + throwIO, called at compiler\GHC\Utils\Error.hs:499:19 in ghc-10.1-inplace:GHC.Utils.Error 1 ===================================== testsuite/tests/mdo/should_fail/mdofail006.stderr ===================================== @@ -1,9 +1,11 @@ -mdofail006: Uncaught exception ghc-internal:GHC.Internal.IO.Exception.FixIOException: +mdofail006.exe: Uncaught exception ghc-internal:GHC.Internal.IO.Exception.FixIOException: cyclic evaluation in fixIO -While handling thread blocked indefinitely in an MVar operation +While handling ghc-internal:GHC.Internal.IO.Exception.BlockedIndefinitelyOnMVar: + | + | thread blocked indefinitely in an MVar operation HasCallStack backtrace: - throwIO, called at libraries/ghc-internal/src/GHC/Internal/Control/Monad/Fix.hs:167:37 in ghc-internal:GHC.Internal.Control.Monad.Fix + throwIO, called at libraries\ghc-internal\src\GHC\Internal\Control\Monad\Fix.hs:169:37 in ghc-internal:GHC.Internal.Control.Monad.Fix ===================================== testsuite/tests/pmcheck/should_compile/T27360.hs ===================================== @@ -0,0 +1,11 @@ +module T27360 where + +import GHC.Exts + +f :: () +f | False, considerAccessible = () + | otherwise = () + +g :: () +g | False, True <- considerAccessible = () + | otherwise = () ===================================== testsuite/tests/pmcheck/should_compile/all.T ===================================== @@ -182,3 +182,4 @@ test('T24845', [], compile, [overlapping_incomplete]) test('T22652', [], compile, [overlapping_incomplete]) test('T22652a', [], compile, [overlapping_incomplete]) test('T24867', [], compile_fail, [overlapping_incomplete]) +test('T27360', normal, compile, [overlapping_incomplete + '-g3']) ===================================== testsuite/tests/runghc/T7859.stderr-mingw32 ===================================== @@ -2,7 +2,12 @@ runghc-9.13.20241015.exe: Uncaught exception ghc-internal:GHC.Internal.IO.Except defer-type-errors: rawSystem: does not exist (No such file or directory) -While handling rawSystem: does not exist (No such file or directory) +While handling ghc-internal:GHC.Internal.IO.Exception.IOException: + | + | rawSystem: does not exist (No such file or directory) + | + | HasCallStack backtrace: + | ioError, called at libraries/ghc-internal/src/GHC/Internal/Foreign/C/Error.hs:<line>:<column> in <package-id>:GHC.Internal.Foreign.C.Error HasCallStack backtrace: ioError, called at libraries\process\System\Process\Common.hs:239:16 in process-1.6.25.0-inplace:System.Process.Common View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/6a9f1ff9164358d29de72a5b9f8af58... -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/6a9f1ff9164358d29de72a5b9f8af58... 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