Marge Bot pushed to branch wip/marge_bot_batch_merge_job at Glasgow Haskell Compiler / GHC Commits: a3afae0c by Simon Peyton Jones at 2025-12-25T15:26:36-05:00 Check for rubbish literals in Lint Addresses #26607. See new Note [Checking for rubbish literals] in GHC.Core.Lint - - - - - 963635a3 by Aaron Allen at 2025-12-31T20:14:21-05:00 [#26183] Associated Type Iface Fix When determining "extras" for class decl interface entries, axioms for the associated types need to included so that dependent modules will be recompiled if those axioms change. resolves #26183 - - - - - be4b173d by Cheng Shao at 2025-12-31T20:14:22-05:00 testsuite: run numeric tests with optasm when available This patch adds the `optasm` extra way to nueric tests when NCG is available. Some numeric bugs only surface with optimization, omitting this can hide these bugs and even make them slip into release! (e.g. #26711) - - - - - 13 changed files: - compiler/GHC/Core/Lint.hs - compiler/GHC/Core/Utils.hs - compiler/GHC/Driver/Config/Core/Lint.hs - compiler/GHC/Driver/Config/Core/Lint/Interactive.hs - compiler/GHC/Iface/Recomp.hs - compiler/GHC/IfaceToCore.hs - + testsuite/tests/driver/recomp26183/M.hs - + testsuite/tests/driver/recomp26183/M2A.hs - + testsuite/tests/driver/recomp26183/M2B.hs - + testsuite/tests/driver/recomp26183/Makefile - + testsuite/tests/driver/recomp26183/all.T - + testsuite/tests/driver/recomp26183/recomp26183.stderr - testsuite/tests/numeric/should_run/all.T Changes: ===================================== compiler/GHC/Core/Lint.hs ===================================== @@ -405,7 +405,6 @@ data LintPassResultConfig = LintPassResultConfig { lpr_diagOpts :: !DiagOpts , lpr_platform :: !Platform , lpr_makeLintFlags :: !LintFlags - , lpr_showLintWarnings :: !Bool , lpr_passPpr :: !SDoc , lpr_localsInScope :: ![Var] } @@ -425,18 +424,16 @@ lintPassResult logger cfg binds "Core Linted result of " ++ renderWithContext defaultSDocContext (lpr_passPpr cfg) ; displayLintResults logger - (lpr_showLintWarnings cfg) (lpr_passPpr cfg) + (lpr_passPpr cfg) (pprCoreBindings binds) warns_and_errs } displayLintResults :: Logger - -> Bool -- ^ If 'True', display linter warnings. - -- If 'False', ignore linter warnings. -> SDoc -- ^ The source of the linted program -> SDoc -- ^ The linted program, pretty-printed -> WarnsAndErrs -> IO () -displayLintResults logger display_warnings pp_what pp_pgm (warns, errs) +displayLintResults logger pp_what pp_pgm (warns, errs) | not (isEmptyBag errs) = do { lintMessage logger (vcat [ lint_banner "errors" pp_what, Err.pprMessageBag errs @@ -447,7 +444,6 @@ displayLintResults logger display_warnings pp_what pp_pgm (warns, errs) | not (isEmptyBag warns) , log_enable_debug (logFlags logger) - , display_warnings = lintMessage logger (lint_banner "warnings" pp_what $$ Err.pprMessageBag (mapBag ($$ blankLine) warns)) @@ -858,6 +854,31 @@ remember the details, but could probably recover it if we want to revisit. So Lint current accepts (Coercion co) in arbitrary places. There is no harm in that: it really is a value, albeit a zero-bit value. +Note [Checking for rubbish literals] +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +GHC uses "rubbish literals" (see Note [Rubbish literals] in GHC.Types.Literal) +to fill for absent arguments, in worker/wrapper. See Note [Absent fillers] in +GHC.Core.Opt.WorkWrap.Utils. + +These rubbish literals are almost always discarded as dead code, in post-w/w +optimisation. If they are ever used at runtime, something is wrong. For lifted +absent fillers, instead of using a `LitRubbish` we use an error thunk. So if, +through some catastrophe, it is used at runtime after all, we get a civilised +runtime error + +But for /unlifted/ ones we can't use a thunk, so we use a random "rubbish" value +of the right type. That could lead to bizarre behaviour at runtime. + +Worse, for dictionaries, for reasons explained in Note [Absent fillers], we also +don't use an error thunk. Now if we use it at runtime after all, a seg-fault will +happen (e.g. #26416). Yikes! + +So Lint warns about the presence of rubbish literals, in the output of CorePrep +only (see GHC.Driver.Config.Core.Lint.perPassFlags). It's a warning, not an +error, because it's not /necessarily/ wrong to see a rubbish literal. But it's +suspicious and worth investigating if you have a seg-fault or bizarre behaviour. + + ************************************************************************ * * \subsection[lintCoreExpr]{lintCoreExpr} @@ -883,7 +904,14 @@ lintCoreExpr (Var var) ; return var_pair } lintCoreExpr (Lit lit) - = return (literalType lit, zeroUE) + = do { flags <- getLintFlags + + ; -- See Note [Checking for rubbish literals] + when (lf_check_rubbish_lits flags) $ + checkWarnL (not (isLitRubbish lit)) $ + hang (text "Unexpected rubbish literal:") 2 (ppr lit) + + ; return (literalType lit, zeroUE) } lintCoreExpr (Cast expr co) = do { (expr_ty, ue) <- markAllJoinsBad (lintCoreExpr expr) @@ -2785,7 +2813,7 @@ lintAxioms :: Logger -> [CoAxiom Branched] -> IO () lintAxioms logger cfg what axioms = - displayLintResults logger True what (vcat $ map pprCoAxiom axioms) $ + displayLintResults logger what (vcat $ map pprCoAxiom axioms) $ initL cfg $ do { mapM_ lint_axiom axioms ; let axiom_groups = groupWith coAxiomTyCon axioms @@ -2968,9 +2996,10 @@ data LintFlags = LF { lf_check_global_ids :: Bool -- See Note [Checking for global Ids] , lf_check_inline_loop_breakers :: Bool -- See Note [Checking for INLINE loop breakers] , lf_check_static_ptrs :: StaticPtrCheck -- ^ See Note [Checking StaticPtrs] - , lf_report_unsat_syns :: Bool -- ^ See Note [Linting type synonym applications] - , lf_check_linearity :: Bool -- ^ See Note [Linting linearity] - , lf_check_fixed_rep :: Bool -- See Note [Checking for representation polymorphism] + , lf_report_unsat_syns :: Bool -- ^ See Note [Linting type synonym applications] + , lf_check_linearity :: Bool -- ^ See Note [Linting linearity] + , lf_check_fixed_rep :: Bool -- ^ See Note [Checking for representation polymorphism] + , lf_check_rubbish_lits :: Bool -- ^ See Note [Checking for rubbish literals] } -- See Note [Checking StaticPtrs] ===================================== compiler/GHC/Core/Utils.hs ===================================== @@ -2168,20 +2168,24 @@ it doesn't have the trickiness of the let-can-float invariant to worry about. -- Suppose @f x@ diverges; then @C (f x)@ is not a value. -- We check for this using needsCaseBinding below exprIsHNF :: CoreExpr -> Bool -- True => Value-lambda, constructor, PAP -exprIsHNF = exprIsHNFlike isDataConWorkId isEvaldUnfolding +exprIsHNF = exprIsHNFlike isDataConWorkId isEvaldUnfolding True -- | Similar to 'exprIsHNF' but includes CONLIKE functions as well as -- data constructors. Conlike arguments are considered interesting by the -- inliner. exprIsConLike :: CoreExpr -> Bool -- True => lambda, conlike, PAP -exprIsConLike = exprIsHNFlike isConLikeId isConLikeUnfolding +exprIsConLike = exprIsHNFlike isConLikeId isConLikeUnfolding False -- | Returns true for values or value-like expressions. These are lambdas, -- constructors / CONLIKE functions (as determined by the function argument) -- or PAPs. -- -exprIsHNFlike :: HasDebugCallStack => (Var -> Bool) -> (Unfolding -> Bool) -> CoreExpr -> Bool -exprIsHNFlike is_con is_con_unf e +exprIsHNFlike :: HasDebugCallStack => (Var -> Bool) + -> (Unfolding -> Bool) + -> Bool + -> CoreExpr -> Bool +{-# INLINE exprIsHNFlike #-} -- Specialise at its two call sites +exprIsHNFlike is_con is_con_unf rubbish_lit_result e = -- pprTraceWith "hnf" (\r -> ppr r <+> ppr e) $ is_hnf_like e where @@ -2200,9 +2204,12 @@ exprIsHNFlike is_con is_con_unf e || definitelyUnliftedType (idType v) -- Unlifted binders are always evaluated (#20140) - is_hnf_like (Lit l) = not (isLitRubbish l) + is_hnf_like (Lit lit) + | isLitRubbish lit = rubbish_lit_result + | otherwise = True -- Regarding a LitRubbish as ConLike leads to unproductive inlining in -- WWRec, see #20035 + is_hnf_like (Type _) = True -- Types are honorary Values; -- we don't mind copying them is_hnf_like (Coercion _) = True -- Same for coercions @@ -2283,7 +2290,6 @@ exprIsHNFlike is_con is_con_unf e | otherwise = Nothing -{-# INLINE exprIsHNFlike #-} {- Note [exprIsHNF Tick] ===================================== compiler/GHC/Driver/Config/Core/Lint.hs ===================================== @@ -106,26 +106,18 @@ initLintPassResultConfig dflags extra_vars pass = LintPassResultConfig { lpr_diagOpts = initDiagOpts dflags , lpr_platform = targetPlatform dflags , lpr_makeLintFlags = perPassFlags dflags pass - , lpr_showLintWarnings = showLintWarnings pass , lpr_passPpr = ppr pass , lpr_localsInScope = extra_vars } -showLintWarnings :: CoreToDo -> Bool --- Disable Lint warnings on the first simplifier pass, because --- there may be some INLINE knots still tied, which is tiresomely noisy -showLintWarnings (CoreDoSimplify cfg) - | SimplPhase InitialPhase <- sm_phase (so_mode cfg) - = False -showLintWarnings _ = True - perPassFlags :: DynFlags -> CoreToDo -> LintFlags perPassFlags dflags pass = (defaultLintFlags dflags) - { lf_check_global_ids = check_globals + { lf_check_global_ids = check_globals , lf_check_inline_loop_breakers = check_lbs - , lf_check_static_ptrs = check_static_ptrs - , lf_check_linearity = check_linearity } + , lf_check_static_ptrs = check_static_ptrs + , lf_check_linearity = check_linearity + , lf_check_rubbish_lits = check_rubbish } where -- See Note [Checking for global Ids] check_globals = case pass of @@ -137,6 +129,14 @@ perPassFlags dflags pass check_lbs = case pass of CoreDesugar -> False CoreDesugarOpt -> False + + -- Disable Lint warnings on the first simplifier pass, because + -- there may be some INLINE knots still tied, which is tiresomely noisy + CoreDoSimplify cfg + | SimplPhase InitialPhase <- sm_phase (so_mode cfg) + -> True + | otherwise + -> False _ -> True -- See Note [Checking StaticPtrs] @@ -153,6 +153,11 @@ perPassFlags dflags pass CoreDesugar -> True _ -> False) + -- See Note [Checking for rubbish literals] in GHC.Core.Lint + check_rubbish = case pass of + CorePrep -> True + _ -> False + initLintConfig :: DynFlags -> [Var] -> LintConfig initLintConfig dflags vars =LintConfig { l_diagOpts = initDiagOpts dflags @@ -168,4 +173,5 @@ defaultLintFlags dflags = LF { lf_check_global_ids = False , lf_check_linearity = gopt Opt_DoLinearCoreLinting dflags , lf_report_unsat_syns = True , lf_check_fixed_rep = True + , lf_check_rubbish_lits = True } ===================================== compiler/GHC/Driver/Config/Core/Lint/Interactive.hs ===================================== @@ -10,12 +10,9 @@ import GHC.Driver.Config.Core.Lint import GHC.Core import GHC.Core.Ppr - import GHC.Core.Lint import GHC.Core.Lint.Interactive ---import GHC.Runtime.Context - import GHC.Data.Bag import GHC.Utils.Outputable as Outputable @@ -27,7 +24,7 @@ lintInteractiveExpr what hsc_env expr | not (gopt Opt_DoCoreLinting dflags) = return () | Just err <- lintExpr (initLintConfig dflags $ interactiveInScope $ hsc_IC hsc_env) expr - = displayLintResults logger False what (pprCoreExpr expr) (emptyBag, err) + = displayLintResults logger what (pprCoreExpr expr) (emptyBag, err) | otherwise = return () where ===================================== compiler/GHC/Iface/Recomp.hs ===================================== @@ -1782,10 +1782,12 @@ declExtras fix_fn ann_fn rule_env inst_env fi_env dm_env complete_env decl IfaceClass{ifBody = IfConcreteClass { ifSigs=sigs, ifATs=ats }} -> IfaceClassExtras (fix_fn n) insts (ann_fn (AnnOccName n)) meths defms where - insts = (map ifDFun $ (concatMap at_extras ats) - ++ lookupOccEnvL inst_env n) - -- Include instances of the associated types - -- as well as instances of the class (#5147) + insts = + let (atFamInsts, atClsInsts) = foldMap at_extras ats + in (ifFamInstAxiom <$> atFamInsts) ++ (ifDFun <$> atClsInsts) + ++ (ifDFun <$> lookupOccEnvL inst_env n) + -- Include instances and axioms of the associated types + -- as well as instances of the class (#5147) (#26183) meths = [id_extras (getOccName op) | IfaceClassOp op _ _ <- sigs] -- Names of all the default methods (see Note [default method Name]) defms = [ dmName @@ -1802,7 +1804,10 @@ declExtras fix_fn ann_fn rule_env inst_env fi_env dm_env complete_env decl where n = getOccName decl id_extras occ = IdExtras (fix_fn occ) (lookupOccEnvL rule_env occ) (ann_fn (AnnOccName occ)) (lookup_complete_match occ) - at_extras (IfaceAT decl _) = lookupOccEnvL inst_env (getOccName decl) + at_extras (IfaceAT decl _) = + ( lookupOccEnvL fi_env (getOccName decl) -- Axioms + , lookupOccEnvL inst_env (getOccName decl) -- Class instances + ) lookup_complete_match occ = lookupOccEnvL complete_env occ ===================================== compiler/GHC/IfaceToCore.hs ===================================== @@ -1413,7 +1413,7 @@ tcIfaceRule (IfaceRule {ifRuleName = name, ifActivation = act, ifRuleBndrs = bnd Nothing -> return () Just errs -> do logger <- getLogger - liftIO $ displayLintResults logger False doc + liftIO $ displayLintResults logger doc (pprCoreExpr rhs') (emptyBag, errs) } ; return (bndrs', args', rhs') } @@ -2006,7 +2006,7 @@ tcUnfoldingRhs is_compulsory toplvl name expr case lintUnfolding is_compulsory (initLintConfig dflags in_scope) noSrcLoc core_expr' of Nothing -> return () Just errs -> liftIO $ - displayLintResults logger False doc + displayLintResults logger doc (pprCoreExpr core_expr') (emptyBag, errs) return core_expr' where ===================================== testsuite/tests/driver/recomp26183/M.hs ===================================== @@ -0,0 +1,5 @@ +module M where +import M2 + +x :: AT () +x = True ===================================== testsuite/tests/driver/recomp26183/M2A.hs ===================================== @@ -0,0 +1,8 @@ +{-# LANGUAGE TypeFamilies #-} +module M2 where + +class C a where + type AT a + +instance C () where + type AT () = Bool ===================================== testsuite/tests/driver/recomp26183/M2B.hs ===================================== @@ -0,0 +1,8 @@ +{-# LANGUAGE TypeFamilies #-} +module M2 where + +class C a where + type AT a + +instance C () where + type AT () = Int ===================================== testsuite/tests/driver/recomp26183/Makefile ===================================== @@ -0,0 +1,13 @@ +TOP=../../.. +include $(TOP)/mk/boilerplate.mk +include $(TOP)/mk/test.mk + +# Recompilation tests + +recomp26183: + cp M2A.hs M2.hs + '$(TEST_HC)' $(TEST_HC_OPTS) --make M.hs + sleep 1 + cp M2B.hs M2.hs + # This should fail + if '$(TEST_HC)' $(TEST_HC_OPTS) --make M.hs; then false; fi ===================================== testsuite/tests/driver/recomp26183/all.T ===================================== @@ -0,0 +1,3 @@ +test('recomp26183', [extra_files(['M2A.hs', 'M.hs', 'M2B.hs']), + when(fast(), skip), ignore_stdout], + makefile_test, []) ===================================== testsuite/tests/driver/recomp26183/recomp26183.stderr ===================================== @@ -0,0 +1,7 @@ +M.hs:5:5: error: [GHC-83865] + • Couldn't match type ‘Bool’ with ‘Int’ + Expected: AT () + Actual: Bool + • In the expression: True + In an equation for ‘x’: x = True + ===================================== testsuite/tests/numeric/should_run/all.T ===================================== @@ -5,6 +5,10 @@ import random +# some bugs only surface with -O, omitting optasm may cause them to +# slip into releases! (e.g. #26711) +setTestOpts(when(have_ncg(), extra_ways(['optasm']))) + test('arith001', normal, compile_and_run, ['']) test('arith002', normal, compile_and_run, ['']) test('arith003', normal, compile_and_run, ['']) View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/459e4ccfab37abeb309fb5fa5563b17... -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/459e4ccfab37abeb309fb5fa5563b17... You're receiving this email because of your account on gitlab.haskell.org.