-%
-% (c) The GRASP/AQUA Project, Glasgow University, 1992-1995
+
+% (c) The University of Glasgow, 1996-2000
%
\section[CmdLineOpts]{Things to do with command-line options}
\begin{code}
-#include "HsVersions.h"
module CmdLineOpts (
- CmdLineInfo(..), SwitchResult(..),
- GlobalSwitch(..), SimplifierSwitch(..),
- CoreToDo(..),
- StgToDo(..),
-#ifdef DPH
- PodizeToDo(..),
-#endif {- Data Parallel Haskell -}
-
- classifyOpts,
- switchIsOn, stringSwitchSet, intSwitchSet,
-
- -- to make the interface self-sufficient
- Maybe, MainIO(..)
+ CoreToDo(..), buildCoreToDo, StgToDo(..),
+ SimplifierSwitch(..),
+ SimplifierMode(..), FloatOutSwitches(..),
+
+ HscTarget(..),
+ DynFlag(..), -- needed non-abstractly by DriverFlags
+ DynFlags(..),
+ PackageFlag(..),
+
+ v_Static_hsc_opts,
+
+ isStaticHscFlag,
+
+ -- Manipulating DynFlags
+ defaultDynFlags, -- DynFlags
+ dopt, -- DynFlag -> DynFlags -> Bool
+ dopt_set, dopt_unset, -- DynFlags -> DynFlag -> DynFlags
+ dopt_CoreToDo, -- DynFlags -> [CoreToDo]
+ dopt_StgToDo, -- DynFlags -> [StgToDo]
+ dopt_HscTarget, -- DynFlags -> HscTarget
+ dopt_OutName, -- DynFlags -> String
+ getOpts, -- (DynFlags -> [a]) -> IO [a]
+ getVerbFlag,
+ updOptLevel,
+
+ -- sets of warning opts
+ minusWOpts,
+ minusWallOpts,
+
+ -- Output style options
+ opt_PprUserLength,
+ opt_PprStyle_Debug,
+
+ -- profiling opts
+ opt_AutoSccsOnAllToplevs,
+ opt_AutoSccsOnExportedToplevs,
+ opt_AutoSccsOnIndividualCafs,
+ opt_SccProfilingOn,
+ opt_DoTickyProfiling,
+
+ -- language opts
+ opt_DictsStrict,
+ opt_MaxContextReductionDepth,
+ opt_IrrefutableTuples,
+ opt_Parallel,
+ opt_SMP,
+ opt_RuntimeTypes,
+ opt_Flatten,
+
+ -- optimisation opts
+ opt_NoMethodSharing,
+ opt_NoStateHack,
+ opt_LiberateCaseThreshold,
+ opt_CprOff,
+ opt_RulesOff,
+ opt_SimplNoPreInlining,
+ opt_SimplExcessPrecision,
+ opt_MaxWorkerArgs,
+
+ -- Unfolding control
+ opt_UF_CreationThreshold,
+ opt_UF_UseThreshold,
+ opt_UF_FunAppDiscount,
+ opt_UF_KeenessFactor,
+ opt_UF_UpdateInPlace,
+ opt_UF_DearOp,
+
+ -- misc opts
+ opt_ErrorSpans,
+ opt_EmitCExternDecls,
+ opt_EnsureSplittableC,
+ opt_GranMacros,
+ opt_HiVersion,
+ opt_HistorySize,
+ opt_OmitBlackHoling,
+ opt_Static,
+ opt_Unregisterised,
+ opt_EmitExternalCore,
+ opt_PIC
) where
-import MainMonad
-import Maybes ( maybeToBool, Maybe(..) )
-import Outputable
+#include "HsVersions.h"
+
+import {-# SOURCE #-} Packages (PackageState)
+import DriverPhases ( HscTarget(..) )
+import Constants -- Default values for some flags
import Util
-#ifdef __GLASGOW_HASKELL__
-import PreludeGlaST -- bad bad bad boy, Will
-#endif
+import FastString ( FastString, mkFastString )
+import Config
+import Maybes ( firstJust )
+
+import Panic ( ghcError, GhcException(UsageError) )
+import GLAEXTS
+import DATA_IOREF ( IORef, readIORef )
+import UNSAFE_IO ( unsafePerformIO )
\end{code}
-A command-line {\em switch} is (generally) either on or off; e.g., the
-``verbose'' (-v) switch is either on or off. (The \tr{-G<group>}
-switch is an exception; it's set to a string, or nothing.)
+%************************************************************************
+%* *
+\subsection{Command-line options}
+%* *
+%************************************************************************
+
+The hsc command-line options are split into two categories:
+
+ - static flags
+ - dynamic flags
+
+Static flags are represented by top-level values of type Bool or Int,
+for example. They therefore have the same value throughout the
+invocation of hsc.
+
+Dynamic flags are represented by an abstract type, DynFlags, which is
+passed into hsc by the compilation manager for every compilation.
+Dynamic flags are those that change on a per-compilation basis,
+perhaps because they may be present in the OPTIONS pragma at the top
+of a module.
+
+Other flag-related blurb:
A list of {\em ToDo}s is things to be done in a particular part of
processing. A (fictitious) example for the Core-to-Core simplifier
(\tr{simplCore/SimplCore.lhs), and in the STG-to-STG processing loop
(\tr{simplStg/SimplStg.lhs}).
-We use function @classifyOpts@ to take raw command-line arguments from
-@GetArgs@ and get back the @CmdLineInfo@, which is what we really
-want.
-
%************************************************************************
%* *
-\subsection[CmdLineOpts-datatype]{Datatypes associated with command-line options}
+\subsection{Datatypes associated with command-line options}
%* *
%************************************************************************
\begin{code}
-type CmdLineInfo
- = (GlobalSwitch -> SwitchResult, -- Switch lookup function
- [CoreToDo], -- Core-to-core spec
-#ifdef DPH
- [PodizeToDo], -- Podizer spec
- [CoreToDo], -- post podized Core-to-core spec
-#endif
- [StgToDo] -- Stg-to-stg spec
- )
-
-data SwitchResult
- = SwBool Bool -- on/off
- | SwString String -- nothing or a String
- | SwInt Int -- nothing or an Int
-\end{code}
-
-\begin{code}
data CoreToDo -- These are diff core-to-core passes,
-- which may be invoked in any order,
-- as many times as you like.
= CoreDoSimplify -- The core-to-core simplifier.
- (SimplifierSwitch -> SwitchResult)
+ SimplifierMode
+ [SimplifierSwitch]
-- Each run of the simplifier can take a different
-- set of simplifier-specific flags.
-
- | Core_Unused_Flag_1
- | CoreDoCalcInlinings1
- | CoreDoCalcInlinings2
| CoreDoFloatInwards
- | CoreDoFullLaziness
+ | CoreDoFloatOutwards FloatOutSwitches
| CoreLiberateCase
| CoreDoPrintCore
| CoreDoStaticArgs
| CoreDoStrictness
+ | CoreDoWorkerWrapper
| CoreDoSpecialising
- | CoreDoDeforest
- | CoreDoAutoCostCentres
- | CoreDoFoldrBuildWorkerWrapper
- | CoreDoFoldrBuildWWAnal
--- ANDY:
---| CoreDoHaskPrint
---| CoreDoHaskLetlessPrint
+ | CoreDoSpecConstr
+ | CoreDoOldStrictness
+ | CoreDoGlomBinds
+ | CoreCSE
+ | CoreDoRuleCheck Int{-CompilerPhase-} String -- Check for non-application of rules
+ -- matching this string
+
+ | CoreDoNothing -- useful when building up lists of these things
\end{code}
\begin{code}
data StgToDo
- = StgDoStaticArgs
- | StgDoUpdateAnalysis
- | StgDoLambdaLift
- | StgDoMassageForProfiling -- should be (next to) last
+ = StgDoMassageForProfiling -- should be (next to) last
-- There's also setStgVarInfo, but its absolute "lastness"
-- is so critical that it is hardwired in (no flag).
| D_stg_stats
\end{code}
\begin{code}
-#ifdef DPH
-data PodizeToDo
- = PodizeNeeded Int -- Which dimensioned PODs need vectorizing
-#endif {- Data Parallel Haskell -}
-\end{code}
+data SimplifierMode -- See comments in SimplMonad
+ = SimplGently
+ | SimplPhase Int
-@GlobalSwitches@ may be visible everywhere in the compiler.
-@SimplifierSwitches@ (which follow) are visible only in the main
-Core-to-Core simplifier.
-
-\begin{code}
-data GlobalSwitch
- = ProduceC String -- generate C output into this file
- | ProduceS String -- generate native-code assembler into this file
- | ProduceHi String -- generate .hi interface into this file
-
- | AsmTarget String -- architecture we are generating code for
- | ForConcurrent
-
- | Haskell_1_3 -- if set => Haskell 1.3; else 1.2
- | GlasgowExts -- Glasgow Haskell extensions allowed
- | CompilingPrelude -- Compiling prelude source
-
- | HideBuiltinNames -- fiddle builtin namespace; used for compiling Prelude
- | HideMostBuiltinNames
- | EnsureSplittableC String -- (by globalising all top-level Ids w/ this String)
-
- | Verbose
- | PprStyle_User -- printing "level" (mostly for debugging)
- | PprStyle_Debug
- | PprStyle_All
-
- | DoCoreLinting -- paranoia flags
- | EmitArityChecks
-
- | OmitInterfacePragmas
- | OmitDerivedRead
- | OmitReexportedInstances
-
- | UnfoldingUseThreshold Int -- global one; see also SimplUnf...
- | UnfoldingCreationThreshold Int -- ditto
- | UnfoldingOverrideThreshold Int
-
- | ReportWhyUnfoldingsDisallowed
- | UseGetMentionedVars
- | ShowPragmaNameErrs
- | NameShadowingNotOK
- | SigsRequired
-
- | SccProfilingOn
- | AutoSccsOnExportedToplevs
- | AutoSccsOnAllToplevs
- | AutoSccsOnIndividualCafs
- | SccGroup String -- name of "group" for this cost centres in this module
-
- | DoTickyProfiling
-
- | DoSemiTagging
-
- -- ToDo: turn these into SimplifierSwitches?
- | FoldrBuildOn -- If foldr/build-style transformations are on.
- -- See also SimplDoFoldrBuild, which is used
- -- inside the simplifier.
- | FoldrBuildTrace -- show all foldr/build optimisations.
-
- | SpecialiseImports -- Treat non-essential spec requests as errors
- | ShowImportSpecs -- Output spec requests for non-essential specs
- | OmitDefaultInstanceMethods
- | SpecialiseOverloaded
- | SpecialiseUnboxed
- | SpecialiseAll
- | SpecialiseTrace
-
- -- this batch of flags is for particular experiments;
- -- v unlikely to be used in any other circumstance
- | OmitBlackHoling
- | StgDoLetNoEscapes
- | IgnoreStrictnessPragmas -- ToDo: still useful?
- | IrrefutableTuples -- We inject extra "LazyPat"s in the typechecker
- | IrrefutableEverything -- (TcPat); doing it any earlier would mean that
- -- deriving-generated code wouldn't be irrefutablified.
- | AllStrict
- | NumbersStrict
- | AllDemanded
-
- | ReturnInRegsThreshold Int
- | VectoredReturnThreshold Int -- very likely UNUSED
-
- | D_dump_rif2hs -- debugging: print out various things
- | D_dump_rn4
- | D_dump_tc
- | D_dump_deriv
- | D_dump_ds
- | D_dump_occur_anal
- | D_dump_simpl
- | D_dump_spec
- | D_dump_stranal
- | D_dump_deforest
- | D_dump_stg
- | D_dump_absC
- | D_dump_flatC
- | D_dump_realC
- | D_dump_asm
- | D_show_passes
---ANDY: | D_dump_core_passes_info -- A Gill-ism
-
- | D_verbose_core2core
- | D_verbose_stg2stg
- | D_simplifier_stats
- | D_source_stats
-
-#ifdef DPH
- | PodizeIntelligent
- | PodizeAggresive
- | PodizeVeryAggresive
- | PodizeExtremelyAggresive
- | D_dump_pod
- | D_dump_psimpl
- | D_dump_nextC
-#endif {- Data Parallel Haskell -}
-\end{code}
-
-\begin{code}
data SimplifierSwitch
- = SimplOkToDupCode
- | SimplFloatLetsExposingWHNF
- | SimplOkToFloatPrimOps
- | SimplAlwaysFloatLetsFromLets
- | SimplDoCaseElim
- | SimplReuseCon
- | SimplCaseOfCase
- | SimplLetToCase
- | SimplMayDeleteConjurableIds
- | SimplPedanticBottoms -- see Simplifier for an explanation
- | SimplDoArityExpand -- expand arity of bindings
- | SimplDoFoldrBuild -- This is the per-simplification flag;
- -- see also FoldrBuildOn, used elsewhere
- -- in the compiler.
- | SimplDoNewOccurAnal -- use the *new*, all singing, Occurance analysis
- | SimplDoInlineFoldrBuild
- -- inline foldr/build (*after* f/b rule is used)
-
- | IgnoreINLINEPragma
- | SimplDoLambdaEtaExpansion
- | SimplDoEtaReduction
-
- | EssentialUnfoldingsOnly -- never mind the thresholds, only
- -- do unfoldings that *must* be done
- -- (to saturate constructors and primitives)
-
- | ShowSimplifierProgress -- report counts on every interation
-
- | MaxSimplifierIterations Int
-
- | SimplUnfoldingUseThreshold Int -- per-simplification variants
- | SimplUnfoldingCreationThreshold Int
-
- | KeepSpecPragmaIds -- We normally *toss* Ids we can do without
- | KeepUnusedBindings
-
- | SimplNoLetFromCase -- used when turning off floating entirely
- | SimplNoLetFromApp -- (for experimentation only) WDP 95/10
- | SimplNoLetFromStrictLet
-{-
- | Extra__SimplFlag1
- | Extra__SimplFlag2
- | Extra__SimplFlag3
- | Extra__SimplFlag4
- | Extra__SimplFlag5
- | Extra__SimplFlag6
- | Extra__SimplFlag7
- | Extra__SimplFlag8
--}
+ = MaxSimplifierIterations Int
+ | NoCaseOfCase
+
+data FloatOutSwitches
+ = FloatOutSw Bool -- True <=> float lambdas to top level
+ Bool -- True <=> float constants to top level,
+ -- even if they do not escape a lambda
\end{code}
%************************************************************************
%* *
-\subsection[CmdLineOpts-classify]{Classifying command-line options}
+\subsection{Dynamic command-line options}
%* *
%************************************************************************
\begin{code}
-classifyOpts :: [String] -- cmd-line args, straight from GetArgs
- -> MainIO CmdLineInfo
--- The MainIO bit is because we might find an unknown flag
--- in which case we print an error message
-
-#ifndef DPH
-classifyOpts opts
- = sep opts [] [] [] -- accumulators...
- where
- sep :: [String] -- cmd-line opts (input)
- -> [GlobalSwitch] -- switch accumulator
- -> [CoreToDo] -> [StgToDo] -- to_do accumulators
- -> MainIO CmdLineInfo -- result
-
- sep [] glob_sw core_td stg_td
- = returnMn (
- isAmong glob_sw,
- reverse core_td,
- reverse stg_td
- )
-
- sep (opt1:opts) glob_sw core_td stg_td
-
-#else {- Data Parallel Haskell -}
-classifyOpts opts
- = sep opts [] [] [] [] [] -- accumulators...
- where
- sep :: [String] -- cmd-line opts (input)
- -> [GlobalSwitch] -- switch accumulator
- -> [CoreToDo] -> [PodizeToDo] -- to_do accumulators
- -> [CoreToDo] -> [StgToDo]
- -> MainIO CmdLineInfo -- result
-
- -- see also the related "simpl_sep" function, used
- -- to collect up the SimplifierSwitches for a "-fsimplify".
-
- sep [] glob_sw core_td pod_td pcore_td stg_td
- = returnMn (
- isAmong glob_sw,
- reverse core_td,
- reverse pod_td,
- reverse pcore_td,
- reverse stg_td
- )
-
- sep (opt1:opts) glob_sw core_td pod_td pcore_td stg_td
-#endif {- Data Parallel Haskell -}
-
-#ifndef DPH
-#define GLOBAL_SW(switch) sep opts (switch:glob_sw) core_td stg_td
-#define CORE_TD(to_do) sep opts glob_sw (to_do:core_td) stg_td
-#define POD_TD(to_do) sep opts glob_sw core_td stg_td
-#define PAR_CORE_TD(to_do) sep opts glob_sw core_td stg_td
-#define BOTH_CORE_TD(to_do) sep opts glob_sw (to_do:core_td) stg_td
-#define STG_TD(to_do) sep opts glob_sw core_td (to_do:stg_td)
-#define IGNORE_ARG() sep opts glob_sw core_td stg_td
-
-#else
-
-#define GLOBAL_SW(switch) sep opts (switch:glob_sw) core_td pod_td pcore_td stg_td
-#define CORE_TD(to_do) sep opts glob_sw (to_do:core_td) pod_td pcore_td stg_td
-#define POD_TD(to_do) sep opts glob_sw core_td (to_do:pod_td) pcore_td stg_td
-#define PAR_CORE_TD(do) sep opts glob_sw core_td pod_td (do:pcore_td) stg_td
-#define BOTH_CORE_TD(do) sep opts glob_sw (do:core_td) pod_td (do:pcore_td) stg_td
-#define STG_TD(to_do) sep opts glob_sw core_td pod_td pcore_td (to_do:stg_td)
-#define IGNORE_ARG() sep opts glob_sw core_td pod_td pcore_td stg_td
-
-#endif {- Data Parallel Haskell -}
-
--- ToDo: DPH-ify
-#define GLOBAL_SIMPL_SW(switch) simpl_sep opts (switch:simpl_sw) glob_sw core_td stg_td
-
- = let
- maybe_fasm = starts_with "-fasm-" opt1
- maybe_G = starts_with "-G" opt1
- maybe_C = starts_with "-C" opt1
- maybe_S = starts_with "-S" opt1
- maybe_hi = starts_with "-hi" opt1
- maybe_hu = starts_with "-hu" opt1
- maybe_uut = starts_with "-funfolding-use-threshold" opt1
- maybe_uct = starts_with "-funfolding-creation-threshold" opt1
- maybe_uot = starts_with "-funfolding-override-threshold" opt1
- maybe_rirt = starts_with "-freturn-in-regs-threshold" opt1
- maybe_gtn = starts_with "-fglobalise-toplev-names" opt1
- starts_with_fasm = maybeToBool maybe_fasm
- starts_with_G = maybeToBool maybe_G
- starts_with_C = maybeToBool maybe_C
- starts_with_S = maybeToBool maybe_S
- starts_with_hi = maybeToBool maybe_hi
- starts_with_hu = maybeToBool maybe_hu
- starts_with_uut = maybeToBool maybe_uut
- starts_with_uct = maybeToBool maybe_uct
- starts_with_uot = maybeToBool maybe_uot
- starts_with_rirt = maybeToBool maybe_rirt
- starts_with_gtn = maybeToBool maybe_gtn
- (Just after_fasm) = maybe_fasm
- (Just after_G) = maybe_G
- (Just after_C) = maybe_C
- (Just after_S) = maybe_S
- (Just after_hi) = maybe_hi
- (Just after_hu) = maybe_hu
- (Just after_uut) = maybe_uut
- (Just after_uct) = maybe_uct
- (Just after_uot) = maybe_uot
- (Just after_rirt) = maybe_rirt
- (Just after_gtn) = maybe_gtn
- in
- case opt1 of -- the non-"just match a string" options are at the end...
- ',' : _ -> IGNORE_ARG() -- it is for the parser
- "-ddump-rif2hs" -> GLOBAL_SW(D_dump_rif2hs)
- "-ddump-rn4" -> GLOBAL_SW(D_dump_rn4)
- "-ddump-tc" -> GLOBAL_SW(D_dump_tc)
- "-ddump-deriv" -> GLOBAL_SW(D_dump_deriv)
- "-ddump-ds" -> GLOBAL_SW(D_dump_ds)
- "-ddump-stranal" -> GLOBAL_SW(D_dump_stranal)
- "-ddump-deforest"-> GLOBAL_SW(D_dump_deforest)
- "-ddump-spec" -> GLOBAL_SW(D_dump_spec)
- "-ddump-simpl" -> GLOBAL_SW(D_dump_simpl)
- "-ddump-occur-anal" -> GLOBAL_SW(D_dump_occur_anal)
-#ifdef DPH
- "-ddump-pod" -> GLOBAL_SW(D_dump_pod)
- "-ddump-psimpl" -> GLOBAL_SW(D_dump_psimpl)
- "-ddump-nextC" -> GLOBAL_SW(D_dump_nextC)
-#endif {- Data Parallel Haskell -}
-
- "-ddump-stg" -> GLOBAL_SW(D_dump_stg)
- "-ddump-absC" -> GLOBAL_SW(D_dump_absC)
- "-ddump-flatC" -> GLOBAL_SW(D_dump_flatC)
- "-ddump-realC" -> GLOBAL_SW(D_dump_realC)
- "-ddump-asm" -> GLOBAL_SW(D_dump_asm)
- "-dshow-passes" -> GLOBAL_SW(D_show_passes)
-
--- ANDY: "-ddump-haskell" -> GLOBAL_SW(D_dump_core_passes_info)
- "-dsimplifier-stats" -> GLOBAL_SW(D_simplifier_stats)
- "-dsource-stats" -> GLOBAL_SW(D_source_stats)
-
- "-dverbose-simpl" ->GLOBAL_SW(D_verbose_core2core)
- "-dverbose-stg" -> GLOBAL_SW(D_verbose_stg2stg)
-
- "-fuse-get-mentioned-vars" -> GLOBAL_SW(UseGetMentionedVars)
-
- "-fhaskell-1.3" -> GLOBAL_SW(Haskell_1_3)
- "-dcore-lint" -> GLOBAL_SW(DoCoreLinting)
- "-fomit-interface-pragmas" -> GLOBAL_SW(OmitInterfacePragmas)
- "-fignore-strictness-pragmas" -> GLOBAL_SW(IgnoreStrictnessPragmas)
- "-firrefutable-tuples" -> GLOBAL_SW(IrrefutableTuples)
- "-firrefutable-everything" -> GLOBAL_SW(IrrefutableEverything)
- "-fall-strict" -> GLOBAL_SW(AllStrict)
- "-fnumbers-strict" -> GLOBAL_SW(NumbersStrict)
- "-fall-demanded" -> GLOBAL_SW(AllDemanded)
-
- "-fsemi-tagging" -> GLOBAL_SW(DoSemiTagging)
-
- "-fsimplify" -> -- gather up SimplifierSwitches specially...
- simpl_sep opts [] glob_sw core_td stg_td
-
- "-fcalc-inlinings1"-> CORE_TD(CoreDoCalcInlinings1)
- "-fcalc-inlinings2"-> CORE_TD(CoreDoCalcInlinings2)
- "-ffloat-inwards" -> CORE_TD(CoreDoFloatInwards)
- "-ffull-laziness" -> CORE_TD(CoreDoFullLaziness)
- "-fliberate-case" -> CORE_TD(CoreLiberateCase)
- "-fprint-core" -> CORE_TD(CoreDoPrintCore)
- "-fstatic-args" -> CORE_TD(CoreDoStaticArgs)
- "-fstrictness" -> CORE_TD(CoreDoStrictness)
- "-fspecialise" -> CORE_TD(CoreDoSpecialising)
- "-fdeforest" -> CORE_TD(CoreDoDeforest)
- "-fadd-auto-sccs" -> CORE_TD(CoreDoAutoCostCentres)
- "-ffoldr-build-worker-wrapper" -> CORE_TD(CoreDoFoldrBuildWorkerWrapper)
- "-ffoldr-build-ww-anal" -> CORE_TD(CoreDoFoldrBuildWWAnal)
---ANDY: "-fprint-haskell-core" -> CORE_TD(CoreDoHaskPrint)
--- "-fprint-haskell-letless-core" -> CORE_TD(CoreDoHaskLetlessPrint)
- "-fomit-default-instance-methods" -> GLOBAL_SW(OmitDefaultInstanceMethods)
- "-fspecialise-overloaded" -> GLOBAL_SW(SpecialiseOverloaded)
- "-fspecialise-unboxed" -> GLOBAL_SW(SpecialiseUnboxed)
- "-fspecialise-all" -> GLOBAL_SW(SpecialiseAll)
- "-fspecialise-imports" -> GLOBAL_SW(SpecialiseImports)
- "-fshow-import-specs" -> GLOBAL_SW(ShowImportSpecs)
- "-ftrace-specialisation" -> GLOBAL_SW(SpecialiseTrace)
-
- "-freport-disallowed-unfoldings"
- -> GLOBAL_SW(ReportWhyUnfoldingsDisallowed)
-
- "-fomit-derived-read" -> GLOBAL_SW(OmitDerivedRead)
-
- "-ffoldr-build-on" -> GLOBAL_SW(FoldrBuildOn)
- "-ffoldr-build-trace" -> GLOBAL_SW(FoldrBuildTrace)
-
- "-fstg-static-args" -> STG_TD(StgDoStaticArgs)
- "-fupdate-analysis" -> STG_TD(StgDoUpdateAnalysis)
- "-dstg-stats" -> STG_TD(D_stg_stats)
- "-flambda-lift" -> STG_TD(StgDoLambdaLift)
- "-fmassage-stg-for-profiling" -> STG_TD(StgDoMassageForProfiling)
-
- "-flet-no-escape" -> GLOBAL_SW(StgDoLetNoEscapes)
-
-#ifdef DPH
- "-fpodize-vector" -> POD_TD(PodizeNeeded 1)
- "-fpodize-matrix" -> POD_TD(PodizeNeeded 2)
- "-fpodize-cube" -> POD_TD(PodizeNeeded 3)
- "-fpodize-intelligent" -> GLOBAL_SW(PodizeIntelligent)
- "-fpodize-aggresive" -> GLOBAL_SW(PodizeAggresive)
- "-fpodize-very-aggresive" -> GLOBAL_SW(PodizeVeryAggresive)
- "-fpodize-extremely-aggresive" -> GLOBAL_SW(PodizeExtremelyAggresive)
-#endif {- Data Parallel Haskell -}
-
- "-v" -> GLOBAL_SW(Verbose)
-
- "-fglasgow-exts" -> GLOBAL_SW(GlasgowExts)
- "-prelude" -> GLOBAL_SW(CompilingPrelude)
-
- "-fscc-profiling" -> GLOBAL_SW(SccProfilingOn)
- "-fauto-sccs-on-exported-toplevs" -> GLOBAL_SW(AutoSccsOnExportedToplevs)
- "-fauto-sccs-on-all-toplevs" -> GLOBAL_SW(AutoSccsOnAllToplevs)
- "-fauto-sccs-on-individual-cafs" -> GLOBAL_SW(AutoSccsOnIndividualCafs)
-
- "-fticky-ticky" -> GLOBAL_SW(DoTickyProfiling)
-
- "-dppr-user" -> GLOBAL_SW(PprStyle_User)
- "-dppr-debug" -> GLOBAL_SW(PprStyle_Debug)
- "-dppr-all" -> GLOBAL_SW(PprStyle_All)
-
- "-fhide-builtin-names"-> GLOBAL_SW(HideBuiltinNames)
- "-fmin-builtin-names" -> GLOBAL_SW(HideMostBuiltinNames)
-
- "-fconcurrent" -> GLOBAL_SW(ForConcurrent)
-
- "-fshow-pragma-name-errs" -> GLOBAL_SW(ShowPragmaNameErrs)
- "-fname-shadowing-not-ok" -> GLOBAL_SW(NameShadowingNotOK)
- "-fsignatures-required" -> GLOBAL_SW(SigsRequired)
- "-fomit-reexported-instances" -> GLOBAL_SW(OmitReexportedInstances)
- "-darity-checks" -> GLOBAL_SW(EmitArityChecks)
- "-dno-black-holing"-> GLOBAL_SW(OmitBlackHoling)
-
- _ | starts_with_fasm -> GLOBAL_SW(AsmTarget after_fasm)
- | starts_with_G -> GLOBAL_SW(SccGroup after_G) -- profiling "group"
- | starts_with_C -> GLOBAL_SW(ProduceC after_C) -- main C output
- | starts_with_S -> GLOBAL_SW(ProduceS after_S) -- main .s output
- | starts_with_hi -> GLOBAL_SW(ProduceHi after_hi) -- interface
---UNUSED: | starts_with_hu -> GLOBAL_SW(ProduceHu after_hu) -- usage info
-
- | starts_with_uut -> GLOBAL_SW(UnfoldingUseThreshold (read after_uut))
- | starts_with_uct -> GLOBAL_SW(UnfoldingCreationThreshold (read after_uct))
- | starts_with_uot -> GLOBAL_SW(UnfoldingOverrideThreshold (read after_uot))
-
- | starts_with_rirt -> -- trace ("rirt:"++after_rirt) $
- GLOBAL_SW(ReturnInRegsThreshold (read after_rirt))
-
- | starts_with_gtn -> GLOBAL_SW(EnsureSplittableC after_gtn)
-
-
- _ -> writeMn stderr ("*** WARNING: bad option: "++opt1++"\n") `thenMn` ( \ _ ->
- -- NB: the driver is really supposed to handle bad options
- IGNORE_ARG() )
-
- ----------------
-
- starts_with :: String -> String -> Maybe String
-
- starts_with [] str = Just str
- starts_with (c:cs) (s:ss)
- = if c /= s then Nothing else starts_with cs ss
-
- ----------------
+data DynFlag
+
+ -- debugging flags
+ = Opt_D_dump_cmm
+ | Opt_D_dump_asm
+ | Opt_D_dump_cpranal
+ | Opt_D_dump_deriv
+ | Opt_D_dump_ds
+ | Opt_D_dump_flatC
+ | Opt_D_dump_foreign
+ | Opt_D_dump_inlinings
+ | Opt_D_dump_occur_anal
+ | Opt_D_dump_parsed
+ | Opt_D_dump_rn
+ | Opt_D_dump_simpl
+ | Opt_D_dump_simpl_iterations
+ | Opt_D_dump_spec
+ | Opt_D_dump_prep
+ | Opt_D_dump_stg
+ | Opt_D_dump_stranal
+ | Opt_D_dump_tc
+ | Opt_D_dump_types
+ | Opt_D_dump_rules
+ | Opt_D_dump_cse
+ | Opt_D_dump_worker_wrapper
+ | Opt_D_dump_rn_trace
+ | Opt_D_dump_rn_stats
+ | Opt_D_dump_opt_cmm
+ | Opt_D_dump_simpl_stats
+ | Opt_D_dump_tc_trace
+ | Opt_D_dump_if_trace
+ | Opt_D_dump_splices
+ | Opt_D_dump_BCOs
+ | Opt_D_dump_vect
+ | Opt_D_source_stats
+ | Opt_D_verbose_core2core
+ | Opt_D_verbose_stg2stg
+ | Opt_D_dump_hi
+ | Opt_D_dump_hi_diffs
+ | Opt_D_dump_minimal_imports
+ | Opt_DoCoreLinting
+ | Opt_DoStgLinting
+ | Opt_DoCmmLinting
+
+ | Opt_WarnIsError -- -Werror; makes warnings fatal
+ | Opt_WarnDuplicateExports
+ | Opt_WarnHiShadows
+ | Opt_WarnIncompletePatterns
+ | Opt_WarnIncompletePatternsRecUpd
+ | Opt_WarnMissingFields
+ | Opt_WarnMissingMethods
+ | Opt_WarnMissingSigs
+ | Opt_WarnNameShadowing
+ | Opt_WarnOverlappingPatterns
+ | Opt_WarnSimplePatterns
+ | Opt_WarnTypeDefaults
+ | Opt_WarnUnusedBinds
+ | Opt_WarnUnusedImports
+ | Opt_WarnUnusedMatches
+ | Opt_WarnDeprecations
+ | Opt_WarnDodgyImports
+ | Opt_WarnOrphans
+
+ -- language opts
+ | Opt_AllowOverlappingInstances
+ | Opt_AllowUndecidableInstances
+ | Opt_AllowIncoherentInstances
+ | Opt_MonomorphismRestriction
+ | Opt_GlasgowExts
+ | Opt_FFI
+ | Opt_PArr -- syntactic support for parallel arrays
+ | Opt_Arrows -- Arrow-notation syntax
+ | Opt_TH
+ | Opt_ImplicitParams
+ | Opt_Generics
+ | Opt_ImplicitPrelude
+ | Opt_ScopedTypeVariables
+
+ -- optimisation opts
+ | Opt_Strictness
+ | Opt_FullLaziness
+ | Opt_CSE
+ | Opt_IgnoreInterfacePragmas
+ | Opt_OmitInterfacePragmas
+ | Opt_DoLambdaEtaExpansion
+ | Opt_IgnoreAsserts
+ | Opt_DoEtaReduction
+ | Opt_CaseMerge
+ | Opt_UnboxStrictFields
+
+ deriving (Eq)
+
+data DynFlags = DynFlags {
+ coreToDo :: Maybe [CoreToDo], -- reserved for use with -Ofile
+ stgToDo :: [StgToDo],
+ hscTarget :: HscTarget,
+ hscOutName :: String, -- name of the output file
+ hscStubHOutName :: String, -- name of the .stub_h output file
+ hscStubCOutName :: String, -- name of the .stub_c output file
+ extCoreName :: String, -- name of the .core output file
+ verbosity :: Int, -- verbosity level
+ optLevel :: Int, -- optimisation level
+ maxSimplIterations :: Int, -- max simplifier iterations
+ ruleCheck :: Maybe String,
+ cppFlag :: Bool, -- preprocess with cpp?
+ ppFlag :: Bool, -- preprocess with a Haskell Pp?
+ recompFlag :: Bool, -- True <=> recompilation checker is on
+ stolen_x86_regs :: Int,
+ cmdlineHcIncludes :: [String], -- -#includes
+ importPaths :: [FilePath],
+
+ -- options for particular phases
+ opt_L :: [String],
+ opt_P :: [String],
+ opt_F :: [String],
+ opt_c :: [String],
+ opt_a :: [String],
+ opt_m :: [String],
+#ifdef ILX
+ opt_I :: [String],
+ opt_i :: [String],
+#endif
+
+ -- ** Package flags
+ extraPkgConfs :: [FilePath],
+ -- The -package-conf flags given on the command line, in the order
+ -- they appeared.
+
+ readUserPkgConf :: Bool,
+ -- Whether or not to read the user package database
+ -- (-no-user-package-conf).
+
+ packageFlags :: [PackageFlag],
+ -- The -package and -hide-package flags from the command-line
- -- ToDo: DPH-ify "simpl_sep"!
+ -- ** Package state
+ pkgState :: PackageState,
- simpl_sep :: [String] -- cmd-line opts (input)
- -> [SimplifierSwitch] -- simplifier-switch accumulator
- -> [GlobalSwitch] -- switch accumulator
- -> [CoreToDo] -> [StgToDo] -- to_do accumulators
- -> MainIO CmdLineInfo -- result
+ -- hsc dynamic flags
+ flags :: [DynFlag]
+ }
- -- "simpl_sep" tailcalls "sep" once it's seen one set
- -- of SimplifierSwitches for a CoreDoSimplify.
+data PackageFlag
+ = ExposePackage String
+ | HidePackage String
+ | IgnorePackage String
-#ifdef DEBUG
- simpl_sep input@[] simpl_sw glob_sw core_td stg_td
- = panic "simpl_sep []"
+defaultHscTarget
+#if defined(i386_TARGET_ARCH) || defined(sparc_TARGET_ARCH) || defined(powerpc_TARGET_ARCH)
+ | cGhcWithNativeCodeGen == "YES" = HscAsm
#endif
+ | otherwise = HscC
+
+defaultDynFlags = DynFlags {
+ coreToDo = Nothing, stgToDo = [],
+ hscTarget = defaultHscTarget,
+ hscOutName = "",
+ hscStubHOutName = "", hscStubCOutName = "",
+ extCoreName = "",
+ verbosity = 0,
+ optLevel = 0,
+ maxSimplIterations = 4,
+ ruleCheck = Nothing,
+ cppFlag = False,
+ ppFlag = False,
+ recompFlag = True,
+ stolen_x86_regs = 4,
+ cmdlineHcIncludes = [],
+ importPaths = ["."],
+ opt_L = [],
+ opt_P = [],
+ opt_F = [],
+ opt_c = [],
+ opt_a = [],
+ opt_m = [],
+#ifdef ILX
+ opt_I = [],
+ opt_i = [],
+#endif
+
+ extraPkgConfs = [],
+ readUserPkgConf = True,
+ packageFlags = [],
+ pkgState = error "pkgState",
+
+ flags = [
+ Opt_ImplicitPrelude,
+ Opt_MonomorphismRestriction,
+ Opt_Generics,
+ -- Generating the helper-functions for
+ -- generics is now on by default
+ Opt_Strictness,
+ -- strictness is on by default, but this only
+ -- applies to -O.
+ Opt_CSE, -- similarly for CSE.
+ Opt_FullLaziness, -- ...and for full laziness
+
+ Opt_DoLambdaEtaExpansion,
+ -- This one is important for a tiresome reason:
+ -- we want to make sure that the bindings for data
+ -- constructors are eta-expanded. This is probably
+ -- a good thing anyway, but it seems fragile.
+
+ -- and the default no-optimisation options:
+ Opt_IgnoreInterfacePragmas,
+ Opt_OmitInterfacePragmas
+
+ ] ++ standardWarnings
+ }
+
+{-
+ Verbosity levels:
+
+ 0 | print errors & warnings only
+ 1 | minimal verbosity: print "compiling M ... done." for each module.
+ 2 | equivalent to -dshow-passes
+ 3 | equivalent to existing "ghc -v"
+ 4 | "ghc -v -ddump-most"
+ 5 | "ghc -v -ddump-all"
+-}
+
+dopt :: DynFlag -> DynFlags -> Bool
+dopt f dflags = f `elem` (flags dflags)
- -- The SimplifierSwitches should be delimited by "(" and ")".
-
- simpl_sep ("(":opts) [{-better be empty-}] glob_sw core_td stg_td
- = simpl_sep opts [] glob_sw core_td stg_td
-
- simpl_sep (")":opts) simpl_sw glob_sw core_td stg_td
- = let
- this_CoreDoSimplify = CoreDoSimplify (isAmongSimpl simpl_sw)
- in
- sep opts glob_sw (this_CoreDoSimplify : core_td) stg_td
-
- simpl_sep (opt1:opts) simpl_sw glob_sw core_td stg_td
- = let
- maybe_suut = starts_with "-fsimpl-uf-use-threshold" opt1
- maybe_suct = starts_with "-fsimpl-uf-creation-threshold" opt1
- maybe_msi = starts_with "-fmax-simplifier-iterations" opt1
- starts_with_suut = maybeToBool maybe_suut
- starts_with_suct = maybeToBool maybe_suct
- starts_with_msi = maybeToBool maybe_msi
- (Just after_suut) = maybe_suut
- (Just after_suct) = maybe_suct
- (Just after_msi) = maybe_msi
- in
- case opt1 of -- the non-"just match a string" options are at the end...
- "-fshow-simplifier-progress" -> GLOBAL_SIMPL_SW(ShowSimplifierProgress)
-
- "-fcode-duplication-ok" -> GLOBAL_SIMPL_SW(SimplOkToDupCode)
- "-ffloat-lets-exposing-whnf" -> GLOBAL_SIMPL_SW(SimplFloatLetsExposingWHNF)
- "-ffloat-primops-ok" -> GLOBAL_SIMPL_SW(SimplOkToFloatPrimOps)
- "-falways-float-lets-from-lets" -> GLOBAL_SIMPL_SW(SimplAlwaysFloatLetsFromLets)
- "-fdo-case-elim" -> GLOBAL_SIMPL_SW(SimplDoCaseElim)
- "-fdo-eta-reduction" -> GLOBAL_SIMPL_SW(SimplDoEtaReduction)
- "-fdo-lambda-eta-expansion" -> GLOBAL_SIMPL_SW(SimplDoLambdaEtaExpansion)
- "-fdo-foldr-build" -> GLOBAL_SIMPL_SW(SimplDoFoldrBuild)
- "-fdo-new-occur-anal" -> GLOBAL_SIMPL_SW(SimplDoNewOccurAnal)
- "-fdo-arity-expand" -> GLOBAL_SIMPL_SW(SimplDoArityExpand)
- "-fdo-inline-foldr-build" -> GLOBAL_SIMPL_SW(SimplDoInlineFoldrBuild)
- "-freuse-con" -> GLOBAL_SIMPL_SW(SimplReuseCon)
- "-fcase-of-case" -> GLOBAL_SIMPL_SW(SimplCaseOfCase)
- "-flet-to-case" -> GLOBAL_SIMPL_SW(SimplLetToCase)
- "-fpedantic-bottoms" -> GLOBAL_SIMPL_SW(SimplPedanticBottoms)
- "-fkeep-spec-pragma-ids" -> GLOBAL_SIMPL_SW(KeepSpecPragmaIds)
- "-fkeep-unused-bindings" -> GLOBAL_SIMPL_SW(KeepUnusedBindings)
- "-fmay-delete-conjurable-ids" -> GLOBAL_SIMPL_SW(SimplMayDeleteConjurableIds)
- "-fessential-unfoldings-only" -> GLOBAL_SIMPL_SW(EssentialUnfoldingsOnly)
- "-fignore-inline-pragma" -> GLOBAL_SIMPL_SW(IgnoreINLINEPragma)
- "-fno-let-from-case" -> GLOBAL_SIMPL_SW(SimplNoLetFromCase)
- "-fno-let-from-app" -> GLOBAL_SIMPL_SW(SimplNoLetFromApp)
- "-fno-let-from-strict-let" -> GLOBAL_SIMPL_SW(SimplNoLetFromStrictLet)
-
- _ | starts_with_msi -> GLOBAL_SIMPL_SW(MaxSimplifierIterations (read after_msi))
- | starts_with_suut -> GLOBAL_SIMPL_SW(SimplUnfoldingUseThreshold (read after_suut))
- | starts_with_suct -> GLOBAL_SIMPL_SW(SimplUnfoldingCreationThreshold (read after_suct))
-
- _ -> writeMn stderr ("*** WARNING: bad simplifier option: "++opt1++"\n") `thenMn` ( \ _ ->
- -- NB: the driver is really supposed to handle bad options
- simpl_sep opts simpl_sw glob_sw core_td stg_td )
+dopt_CoreToDo :: DynFlags -> Maybe [CoreToDo]
+dopt_CoreToDo = coreToDo
+
+dopt_StgToDo :: DynFlags -> [StgToDo]
+dopt_StgToDo = stgToDo
+
+dopt_OutName :: DynFlags -> String
+dopt_OutName = hscOutName
+
+dopt_HscTarget :: DynFlags -> HscTarget
+dopt_HscTarget = hscTarget
+
+dopt_set :: DynFlags -> DynFlag -> DynFlags
+dopt_set dfs f = dfs{ flags = f : flags dfs }
+
+dopt_unset :: DynFlags -> DynFlag -> DynFlags
+dopt_unset dfs f = dfs{ flags = filter (/= f) (flags dfs) }
+
+getOpts :: DynFlags -> (DynFlags -> [a]) -> [a]
+ -- We add to the options from the front, so we need to reverse the list
+getOpts dflags opts = reverse (opts dflags)
+
+getVerbFlag dflags
+ | verbosity dflags >= 3 = "-v"
+ | otherwise = ""
+
+-----------------------------------------------------------------------------
+-- Setting the optimisation level
+
+updOptLevel n dfs
+ = if (n >= 1)
+ then dfs2{ hscTarget = HscC, optLevel = n } -- turn on -fvia-C with -O
+ else dfs2{ optLevel = n }
+ where
+ dfs1 = foldr (flip dopt_unset) dfs remove_dopts
+ dfs2 = foldr (flip dopt_set) dfs1 extra_dopts
+
+ extra_dopts
+ | n == 0 = opt_0_dopts
+ | otherwise = opt_1_dopts
+
+ remove_dopts
+ | n == 0 = opt_1_dopts
+ | otherwise = opt_0_dopts
+
+opt_0_dopts = [
+ Opt_IgnoreInterfacePragmas,
+ Opt_OmitInterfacePragmas
+ ]
+
+opt_1_dopts = [
+ Opt_IgnoreAsserts,
+ Opt_DoEtaReduction,
+ Opt_CaseMerge
+ ]
+
+-- Core-to-core phases:
+
+buildCoreToDo :: DynFlags -> [CoreToDo]
+buildCoreToDo dflags = core_todo
+ where
+ opt_level = optLevel dflags
+ max_iter = maxSimplIterations dflags
+ strictness = dopt Opt_Strictness dflags
+ full_laziness = dopt Opt_FullLaziness dflags
+ cse = dopt Opt_CSE dflags
+ rule_check = ruleCheck dflags
+
+ core_todo =
+ if opt_level == 0 then
+ [
+ CoreDoSimplify (SimplPhase 0) [
+ MaxSimplifierIterations max_iter
+ ]
+ ]
+
+ else {- opt_level >= 1 -} [
+
+ -- initial simplify: mk specialiser happy: minimum effort please
+ CoreDoSimplify SimplGently [
+ -- Simplify "gently"
+ -- Don't inline anything till full laziness has bitten
+ -- In particular, inlining wrappers inhibits floating
+ -- e.g. ...(case f x of ...)...
+ -- ==> ...(case (case x of I# x# -> fw x#) of ...)...
+ -- ==> ...(case x of I# x# -> case fw x# of ...)...
+ -- and now the redex (f x) isn't floatable any more
+ -- Similarly, don't apply any rules until after full
+ -- laziness. Notably, list fusion can prevent floating.
+
+ NoCaseOfCase,
+ -- Don't do case-of-case transformations.
+ -- This makes full laziness work better
+ MaxSimplifierIterations max_iter
+ ],
+
+ -- Specialisation is best done before full laziness
+ -- so that overloaded functions have all their dictionary lambdas manifest
+ CoreDoSpecialising,
+
+ if full_laziness then CoreDoFloatOutwards (FloatOutSw False False)
+ else CoreDoNothing,
+
+ CoreDoFloatInwards,
+
+ CoreDoSimplify (SimplPhase 2) [
+ -- Want to run with inline phase 2 after the specialiser to give
+ -- maximum chance for fusion to work before we inline build/augment
+ -- in phase 1. This made a difference in 'ansi' where an
+ -- overloaded function wasn't inlined till too late.
+ MaxSimplifierIterations max_iter
+ ],
+ case rule_check of { Just pat -> CoreDoRuleCheck 2 pat; Nothing -> CoreDoNothing },
+
+ CoreDoSimplify (SimplPhase 1) [
+ -- Need inline-phase2 here so that build/augment get
+ -- inlined. I found that spectral/hartel/genfft lost some useful
+ -- strictness in the function sumcode' if augment is not inlined
+ -- before strictness analysis runs
+ MaxSimplifierIterations max_iter
+ ],
+ case rule_check of { Just pat -> CoreDoRuleCheck 1 pat; Nothing -> CoreDoNothing },
+
+ CoreDoSimplify (SimplPhase 0) [
+ -- Phase 0: allow all Ids to be inlined now
+ -- This gets foldr inlined before strictness analysis
+
+ MaxSimplifierIterations 3
+ -- At least 3 iterations because otherwise we land up with
+ -- huge dead expressions because of an infelicity in the
+ -- simpifier.
+ -- let k = BIG in foldr k z xs
+ -- ==> let k = BIG in letrec go = \xs -> ...(k x).... in go xs
+ -- ==> let k = BIG in letrec go = \xs -> ...(BIG x).... in go xs
+ -- Don't stop now!
+
+ ],
+ case rule_check of { Just pat -> CoreDoRuleCheck 0 pat; Nothing -> CoreDoNothing },
+
+#ifdef OLD_STRICTNESS
+ CoreDoOldStrictness
+#endif
+ if strictness then CoreDoStrictness else CoreDoNothing,
+ CoreDoWorkerWrapper,
+ CoreDoGlomBinds,
+
+ CoreDoSimplify (SimplPhase 0) [
+ MaxSimplifierIterations max_iter
+ ],
+
+ if full_laziness then
+ CoreDoFloatOutwards (FloatOutSw False -- Not lambdas
+ True) -- Float constants
+ else CoreDoNothing,
+ -- nofib/spectral/hartel/wang doubles in speed if you
+ -- do full laziness late in the day. It only happens
+ -- after fusion and other stuff, so the early pass doesn't
+ -- catch it. For the record, the redex is
+ -- f_el22 (f_el21 r_midblock)
+
+
+ -- We want CSE to follow the final full-laziness pass, because it may
+ -- succeed in commoning up things floated out by full laziness.
+ -- CSE used to rely on the no-shadowing invariant, but it doesn't any more
+
+ if cse then CoreCSE else CoreDoNothing,
+
+ CoreDoFloatInwards,
+
+-- Case-liberation for -O2. This should be after
+-- strictness analysis and the simplification which follows it.
+
+ case rule_check of { Just pat -> CoreDoRuleCheck 0 pat; Nothing -> CoreDoNothing },
+
+ if opt_level >= 2 then
+ CoreLiberateCase
+ else
+ CoreDoNothing,
+ if opt_level >= 2 then
+ CoreDoSpecConstr
+ else
+ CoreDoNothing,
+
+ -- Final clean-up simplification:
+ CoreDoSimplify (SimplPhase 0) [
+ MaxSimplifierIterations max_iter
+ ]
+ ]
\end{code}
%************************************************************************
%* *
-\subsection[CmdLineOpts-order]{Switch ordering}
+\subsection{Warnings}
%* *
%************************************************************************
-In spite of the @Produce*@ and @SccGroup@ constructors, these things
-behave just like enumeration types.
-
\begin{code}
-instance Eq GlobalSwitch where
- a == b = tagOf_Switch a _EQ_ tagOf_Switch b
-
-instance Ord GlobalSwitch where
- a < b = tagOf_Switch a _LT_ tagOf_Switch b
- a <= b = tagOf_Switch a _LE_ tagOf_Switch b
-
-instance Eq SimplifierSwitch where
- a == b = tagOf_SimplSwitch a _EQ_ tagOf_SimplSwitch b
-
-instance Ord SimplifierSwitch where
- a < b = tagOf_SimplSwitch a _LT_ tagOf_SimplSwitch b
- a <= b = tagOf_SimplSwitch a _LE_ tagOf_SimplSwitch b
-
-tagOf_Switch (ProduceC _) =(ILIT(0) :: FAST_INT)
-tagOf_Switch (ProduceS _) = ILIT(1)
-tagOf_Switch (ProduceHi _) = ILIT(2)
-tagOf_Switch (AsmTarget _) = ILIT(4)
-tagOf_Switch ForConcurrent = ILIT(6)
-tagOf_Switch Haskell_1_3 = ILIT(8)
-tagOf_Switch GlasgowExts = ILIT(9)
-tagOf_Switch CompilingPrelude = ILIT(10)
-tagOf_Switch HideBuiltinNames = ILIT(11)
-tagOf_Switch HideMostBuiltinNames = ILIT(12)
-tagOf_Switch (EnsureSplittableC _) = ILIT(13)
-tagOf_Switch Verbose = ILIT(14)
-tagOf_Switch PprStyle_User = ILIT(15)
-tagOf_Switch PprStyle_Debug = ILIT(16)
-tagOf_Switch PprStyle_All = ILIT(17)
-tagOf_Switch DoCoreLinting = ILIT(18)
-tagOf_Switch EmitArityChecks = ILIT(19)
-tagOf_Switch OmitInterfacePragmas = ILIT(20)
-tagOf_Switch OmitDerivedRead = ILIT(21)
-tagOf_Switch OmitReexportedInstances = ILIT(22)
-tagOf_Switch (UnfoldingUseThreshold _) = ILIT(23)
-tagOf_Switch (UnfoldingCreationThreshold _) = ILIT(24)
-tagOf_Switch (UnfoldingOverrideThreshold _) = ILIT(25)
-tagOf_Switch ReportWhyUnfoldingsDisallowed = ILIT(26)
-tagOf_Switch UseGetMentionedVars = ILIT(27)
-tagOf_Switch ShowPragmaNameErrs = ILIT(28)
-tagOf_Switch NameShadowingNotOK = ILIT(29)
-tagOf_Switch SigsRequired = ILIT(30)
-tagOf_Switch SccProfilingOn = ILIT(31)
-tagOf_Switch AutoSccsOnExportedToplevs = ILIT(32)
-tagOf_Switch AutoSccsOnAllToplevs = ILIT(33)
-tagOf_Switch AutoSccsOnIndividualCafs = ILIT(34)
-tagOf_Switch (SccGroup _) = ILIT(36)
-tagOf_Switch DoTickyProfiling = ILIT(37)
-tagOf_Switch DoSemiTagging = ILIT(38)
-tagOf_Switch FoldrBuildOn = ILIT(39)
-tagOf_Switch FoldrBuildTrace = ILIT(40)
-tagOf_Switch SpecialiseImports = ILIT(41)
-tagOf_Switch ShowImportSpecs = ILIT(42)
-tagOf_Switch OmitDefaultInstanceMethods = ILIT(43)
-tagOf_Switch SpecialiseOverloaded = ILIT(44)
-tagOf_Switch SpecialiseUnboxed = ILIT(45)
-tagOf_Switch SpecialiseAll = ILIT(46)
-tagOf_Switch SpecialiseTrace = ILIT(47)
-
-tagOf_Switch OmitBlackHoling = ILIT(49)
-tagOf_Switch StgDoLetNoEscapes = ILIT(50)
-tagOf_Switch IgnoreStrictnessPragmas = ILIT(51)
-tagOf_Switch IrrefutableTuples = ILIT(52)
-tagOf_Switch IrrefutableEverything = ILIT(53)
-tagOf_Switch AllStrict = ILIT(54)
-tagOf_Switch NumbersStrict = ILIT(55)
-tagOf_Switch AllDemanded = ILIT(56)
-
-tagOf_Switch (ReturnInRegsThreshold _) = ILIT(57)
-tagOf_Switch (VectoredReturnThreshold _)= ILIT(58)
-tagOf_Switch D_dump_rif2hs = ILIT(59)
-tagOf_Switch D_dump_rn4 = ILIT(60)
-tagOf_Switch D_dump_tc = ILIT(61)
-tagOf_Switch D_dump_deriv = ILIT(62)
-tagOf_Switch D_dump_ds = ILIT(63)
-tagOf_Switch D_dump_simpl = ILIT(64)
-tagOf_Switch D_dump_spec = ILIT(65)
-tagOf_Switch D_dump_occur_anal = ILIT(66)
-tagOf_Switch D_dump_stranal = ILIT(67)
-tagOf_Switch D_dump_stg = ILIT(68)
-tagOf_Switch D_dump_absC = ILIT(69)
-tagOf_Switch D_dump_flatC = ILIT(70)
-tagOf_Switch D_dump_realC = ILIT(71)
-tagOf_Switch D_dump_asm = ILIT(72)
-tagOf_Switch D_show_passes = ILIT(73)
---ANDY:tagOf_Switch D_dump_core_passes_info = ILIT(??)
-tagOf_Switch D_verbose_core2core = ILIT(74)
-tagOf_Switch D_verbose_stg2stg = ILIT(75)
-tagOf_Switch D_simplifier_stats = ILIT(76)
-tagOf_Switch D_source_stats = ILIT(77) {-see note below!-}
-
-#ifndef DPH
-tagOf_Switch _ = case (panic "tagOf_Switch") of -- BUG avoidance
- s -> tagOf_Switch s
-
-lAST_SWITCH_TAG = IBOX(tagOf_Switch D_source_stats)
-
-#else {- Data Parallel Haskell -}
-
-tagOf_Switch PodizeIntelligent = ILIT(90)
-tagOf_Switch PodizeAggresive = ILIT(91)
-tagOf_Switch PodizeVeryAggresive = ILIT(92)
-tagOf_Switch PodizeExtremelyAggresive = ILIT(93)
-tagOf_Switch D_dump_pod = ILIT(94)
-tagOf_Switch D_dump_psimpl = ILIT(95)
-tagOf_Switch D_dump_nextC = ILIT(96)
-
-tagOf_Switch _ = case (panic "tagOf_Switch") of -- BUG avoidance
- s -> tagOf_Switch s
-
-lAST_SWITCH_TAG = IBOX(tagOf_Switch D_dump_nextC)
-
-#endif {- Data Parallel Haskell -}
+standardWarnings
+ = [ Opt_WarnDeprecations,
+ Opt_WarnOverlappingPatterns,
+ Opt_WarnMissingFields,
+ Opt_WarnMissingMethods,
+ Opt_WarnDuplicateExports
+ ]
+
+minusWOpts
+ = standardWarnings ++
+ [ Opt_WarnUnusedBinds,
+ Opt_WarnUnusedMatches,
+ Opt_WarnUnusedImports,
+ Opt_WarnIncompletePatterns,
+ Opt_WarnDodgyImports
+ ]
+
+minusWallOpts
+ = minusWOpts ++
+ [ Opt_WarnTypeDefaults,
+ Opt_WarnNameShadowing,
+ Opt_WarnMissingSigs,
+ Opt_WarnHiShadows,
+ Opt_WarnOrphans
+ ]
\end{code}
-(Note For Will): Could you please leave a little extra room between
-your last option and @D_dump_spec@... Thanks... jon...
+%************************************************************************
+%* *
+\subsection{Classifying command-line options}
+%* *
+%************************************************************************
\begin{code}
-tagOf_SimplSwitch SimplOkToDupCode =(ILIT(0) :: FAST_INT)
-tagOf_SimplSwitch SimplFloatLetsExposingWHNF = ILIT(1)
-tagOf_SimplSwitch SimplOkToFloatPrimOps = ILIT(2)
-tagOf_SimplSwitch SimplAlwaysFloatLetsFromLets = ILIT(3)
-tagOf_SimplSwitch SimplDoCaseElim = ILIT(4)
-tagOf_SimplSwitch SimplReuseCon = ILIT(5)
-tagOf_SimplSwitch SimplCaseOfCase = ILIT(6)
-tagOf_SimplSwitch SimplLetToCase = ILIT(7)
-tagOf_SimplSwitch SimplMayDeleteConjurableIds = ILIT(9)
-tagOf_SimplSwitch SimplPedanticBottoms = ILIT(10)
-tagOf_SimplSwitch SimplDoArityExpand = ILIT(11)
-tagOf_SimplSwitch SimplDoFoldrBuild = ILIT(12)
-tagOf_SimplSwitch SimplDoNewOccurAnal = ILIT(13)
-tagOf_SimplSwitch SimplDoInlineFoldrBuild = ILIT(14)
-tagOf_SimplSwitch IgnoreINLINEPragma = ILIT(15)
-tagOf_SimplSwitch SimplDoLambdaEtaExpansion = ILIT(16)
-tagOf_SimplSwitch SimplDoEtaReduction = ILIT(18)
-tagOf_SimplSwitch EssentialUnfoldingsOnly = ILIT(19)
-tagOf_SimplSwitch ShowSimplifierProgress = ILIT(20)
-tagOf_SimplSwitch (MaxSimplifierIterations _) = ILIT(21)
-tagOf_SimplSwitch (SimplUnfoldingUseThreshold _) = ILIT(22)
-tagOf_SimplSwitch (SimplUnfoldingCreationThreshold _) = ILIT(23)
-tagOf_SimplSwitch KeepSpecPragmaIds = ILIT(24)
-tagOf_SimplSwitch KeepUnusedBindings = ILIT(25)
-tagOf_SimplSwitch SimplNoLetFromCase = ILIT(26)
-tagOf_SimplSwitch SimplNoLetFromApp = ILIT(27)
-tagOf_SimplSwitch SimplNoLetFromStrictLet = ILIT(28)
--- If you add anything here, be sure to change lAST_SIMPL_SWITCH_TAG, too!
+-- v_Statis_hsc_opts is here to avoid a circular dependency with
+-- main/DriverState.
+GLOBAL_VAR(v_Static_hsc_opts, [], [String])
-{-
-tagOf_SimplSwitch Extra__SimplFlag1 = ILIT(26)
-tagOf_SimplSwitch Extra__SimplFlag2 = ILIT(27)
-tagOf_SimplSwitch Extra__SimplFlag3 = ILIT(28)
-tagOf_SimplSwitch Extra__SimplFlag4 = ILIT(29)
-tagOf_SimplSwitch Extra__SimplFlag5 = ILIT(30)
-tagOf_SimplSwitch Extra__SimplFlag6 = ILIT(31)
-tagOf_SimplSwitch Extra__SimplFlag8 = ILIT(32)
--}
+lookUp :: FastString -> Bool
+lookup_def_int :: String -> Int -> Int
+lookup_def_float :: String -> Float -> Float
+lookup_str :: String -> Maybe String
+
+unpacked_static_opts = unsafePerformIO (readIORef v_Static_hsc_opts)
+packed_static_opts = map mkFastString unpacked_static_opts
+
+lookUp sw = sw `elem` packed_static_opts
+
+-- (lookup_str "foo") looks for the flag -foo=X or -fooX,
+-- and returns the string X
+lookup_str sw
+ = case firstJust (map (startsWith sw) unpacked_static_opts) of
+ Just ('=' : str) -> Just str
+ Just str -> Just str
+ Nothing -> Nothing
+
+lookup_def_int sw def = case (lookup_str sw) of
+ Nothing -> def -- Use default
+ Just xx -> try_read sw xx
+
+lookup_def_float sw def = case (lookup_str sw) of
+ Nothing -> def -- Use default
+ Just xx -> try_read sw xx
+
+
+try_read :: Read a => String -> String -> a
+-- (try_read sw str) tries to read s; if it fails, it
+-- bleats about flag sw
+try_read sw str
+ = case reads str of
+ ((x,_):_) -> x -- Be forgiving: ignore trailing goop, and alternative parses
+ [] -> ghcError (UsageError ("Malformed argument " ++ str ++ " for flag " ++ sw))
+ -- ToDo: hack alert. We should really parse the arugments
+ -- and announce errors in a more civilised way.
-tagOf_SimplSwitch _ = case (panic "tagOf_SimplSwitch") of -- BUG avoidance
- s -> tagOf_SimplSwitch s
-lAST_SIMPL_SWITCH_TAG = IBOX(tagOf_SimplSwitch SimplNoLetFromStrictLet)
+{-
+ Putting the compiler options into temporary at-files
+ may turn out to be necessary later on if we turn hsc into
+ a pure Win32 application where I think there's a command-line
+ length limit of 255. unpacked_opts understands the @ option.
+
+unpacked_opts :: [String]
+unpacked_opts =
+ concat $
+ map (expandAts) $
+ map unpackFS argv -- NOT ARGV any more: v_Static_hsc_opts
+ where
+ expandAts ('@':fname) = words (unsafePerformIO (readFile fname))
+ expandAts l = [l]
+-}
\end{code}
%************************************************************************
%* *
-\subsection[CmdLineOpts-lookup]{Switch lookup}
+\subsection{Static options}
%* *
%************************************************************************
\begin{code}
-isAmong :: [GlobalSwitch] -> GlobalSwitch -> SwitchResult
-isAmongSimpl :: [SimplifierSwitch] -> SimplifierSwitch -> SwitchResult
-
-isAmong on_switches
- = let
- tidied_on_switches = foldl rm_dups [] on_switches
-
- sw_tbl :: Array Int SwitchResult
-
- sw_tbl = (array (0, lAST_SWITCH_TAG) -- bounds...
- all_undefined)
- // defined_elems
-
- all_undefined = [ i := SwBool False | i <- [0 .. lAST_SWITCH_TAG ] ]
-
- defined_elems = map mk_assoc_elem tidied_on_switches
- in
-#ifndef __GLASGOW_HASKELL__
- \ switch -> sw_tbl ! IBOX((tagOf_Switch switch)) -- but this is fast!
-#else
- -- and this is faster!
- -- (avoid some unboxing, bounds checking, and other horrible things:)
- case sw_tbl of { _Array bounds_who_needs_'em stuff ->
- \ switch ->
- case (indexArray# stuff (tagOf_Switch switch)) of
- _Lift v -> v
- }
-#endif
- where
- mk_assoc_elem k@(ProduceC str) = IBOX(tagOf_Switch k) := SwString str
- mk_assoc_elem k@(ProduceS str) = IBOX(tagOf_Switch k) := SwString str
- mk_assoc_elem k@(ProduceHi str) = IBOX(tagOf_Switch k) := SwString str
---UNUSED: mk_assoc_elem k@(ProduceHu str) = IBOX(tagOf_Switch k) := SwString str
- mk_assoc_elem k@(SccGroup str) = IBOX(tagOf_Switch k) := SwString str
- mk_assoc_elem k@(AsmTarget str) = IBOX(tagOf_Switch k) := SwString str
- mk_assoc_elem k@(EnsureSplittableC str) = IBOX(tagOf_Switch k) := SwString str
-
- mk_assoc_elem k@(UnfoldingUseThreshold lvl) = IBOX(tagOf_Switch k) := SwInt lvl
- mk_assoc_elem k@(UnfoldingCreationThreshold lvl) = IBOX(tagOf_Switch k) := SwInt lvl
- mk_assoc_elem k@(UnfoldingOverrideThreshold lvl) = IBOX(tagOf_Switch k) := SwInt lvl
-
- mk_assoc_elem k@(ReturnInRegsThreshold lvl) = IBOX(tagOf_Switch k) := SwInt lvl
-
- mk_assoc_elem k = IBOX(tagOf_Switch k) := SwBool True -- I'm here, Mom!
-
- -- cannot have duplicates if we are going to use the array thing
-
- rm_dups switches_so_far switch
- = if switch `is_elem` switches_so_far
- then switches_so_far
- else switch : switches_so_far
- where
- sw `is_elem` [] = False
- sw `is_elem` (s:ss) = (tagOf_Switch sw) _EQ_ (tagOf_Switch s)
- || sw `is_elem` ss
+-- debugging opts
+opt_PprStyle_Debug = lookUp FSLIT("-dppr-debug")
+opt_PprUserLength = lookup_def_int "-dppr-user-length" 5 --ToDo: give this a name
+
+-- profiling opts
+opt_AutoSccsOnAllToplevs = lookUp FSLIT("-fauto-sccs-on-all-toplevs")
+opt_AutoSccsOnExportedToplevs = lookUp FSLIT("-fauto-sccs-on-exported-toplevs")
+opt_AutoSccsOnIndividualCafs = lookUp FSLIT("-fauto-sccs-on-individual-cafs")
+opt_SccProfilingOn = lookUp FSLIT("-fscc-profiling")
+opt_DoTickyProfiling = lookUp FSLIT("-fticky-ticky")
+
+-- language opts
+opt_DictsStrict = lookUp FSLIT("-fdicts-strict")
+opt_IrrefutableTuples = lookUp FSLIT("-firrefutable-tuples")
+opt_MaxContextReductionDepth = lookup_def_int "-fcontext-stack" mAX_CONTEXT_REDUCTION_DEPTH
+opt_Parallel = lookUp FSLIT("-fparallel")
+opt_SMP = lookUp FSLIT("-fsmp")
+opt_Flatten = lookUp FSLIT("-fflatten")
+
+-- optimisation opts
+opt_NoStateHack = lookUp FSLIT("-fno-state-hack")
+opt_NoMethodSharing = lookUp FSLIT("-fno-method-sharing")
+opt_CprOff = lookUp FSLIT("-fcpr-off")
+opt_RulesOff = lookUp FSLIT("-frules-off")
+ -- Switch off CPR analysis in the new demand analyser
+opt_LiberateCaseThreshold = lookup_def_int "-fliberate-case-threshold" (10::Int)
+opt_MaxWorkerArgs = lookup_def_int "-fmax-worker-args" (10::Int)
+
+opt_EmitCExternDecls = lookUp FSLIT("-femit-extern-decls")
+opt_EnsureSplittableC = lookUp FSLIT("-fglobalise-toplev-names")
+opt_GranMacros = lookUp FSLIT("-fgransim")
+opt_HiVersion = read (cProjectVersionInt ++ cProjectPatchLevel) :: Int
+opt_HistorySize = lookup_def_int "-fhistory-size" 20
+opt_OmitBlackHoling = lookUp FSLIT("-dno-black-holing")
+opt_RuntimeTypes = lookUp FSLIT("-fruntime-types")
+
+-- Simplifier switches
+opt_SimplNoPreInlining = lookUp FSLIT("-fno-pre-inlining")
+ -- NoPreInlining is there just to see how bad things
+ -- get if you don't do it!
+opt_SimplExcessPrecision = lookUp FSLIT("-fexcess-precision")
+
+-- Unfolding control
+opt_UF_CreationThreshold = lookup_def_int "-funfolding-creation-threshold" (45::Int)
+opt_UF_UseThreshold = lookup_def_int "-funfolding-use-threshold" (8::Int) -- Discounts can be big
+opt_UF_FunAppDiscount = lookup_def_int "-funfolding-fun-discount" (6::Int) -- It's great to inline a fn
+opt_UF_KeenessFactor = lookup_def_float "-funfolding-keeness-factor" (1.5::Float)
+opt_UF_UpdateInPlace = lookUp FSLIT("-funfolding-update-in-place")
+
+opt_UF_DearOp = ( 4 :: Int)
+
+opt_Static = lookUp FSLIT("-static")
+opt_Unregisterised = lookUp FSLIT("-funregisterised")
+opt_EmitExternalCore = lookUp FSLIT("-fext-core")
+
+-- Include full span info in error messages, instead of just the start position.
+opt_ErrorSpans = lookUp FSLIT("-ferror-spans")
+
+opt_PIC = lookUp FSLIT("-fPIC")
\end{code}
-Same thing for @SimplifierSwitches@; for efficiency reasons, we
-probably do {\em not} want something overloaded.
- \begin{code}
-isAmongSimpl on_switches
- = let
- tidied_on_switches = foldl rm_dups [] on_switches
-
- sw_tbl :: Array Int SwitchResult
-
- sw_tbl = (array (0, lAST_SIMPL_SWITCH_TAG) -- bounds...
- all_undefined)
- // defined_elems
-
- all_undefined = [ i := SwBool False | i <- [0 .. lAST_SIMPL_SWITCH_TAG ] ]
-
- defined_elems = map mk_assoc_elem tidied_on_switches
- in
-#ifndef __GLASGOW_HASKELL__
- \ switch -> sw_tbl ! IBOX((tagOf_SimplSwitch switch)) -- but this is fast!
-#else
- -- and this is faster!
- -- (avoid some unboxing, bounds checking, and other horrible things:)
- case sw_tbl of { _Array bounds_who_needs_'em stuff ->
- \ switch ->
- case (indexArray# stuff (tagOf_SimplSwitch switch)) of
- _Lift v -> v
- }
-#endif
- where
- mk_assoc_elem k@(MaxSimplifierIterations lvl) = IBOX(tagOf_SimplSwitch k) := SwInt lvl
- mk_assoc_elem k@(SimplUnfoldingUseThreshold i) = IBOX(tagOf_SimplSwitch k) := SwInt i
- mk_assoc_elem k@(SimplUnfoldingCreationThreshold i) = IBOX(tagOf_SimplSwitch k) := SwInt i
-
- mk_assoc_elem k = IBOX(tagOf_SimplSwitch k) := SwBool True -- I'm here, Mom!
-
- -- cannot have duplicates if we are going to use the array thing
-
- rm_dups switches_so_far switch
- = if switch `is_elem` switches_so_far
- then switches_so_far
- else switch : switches_so_far
- where
- sw `is_elem` [] = False
- sw `is_elem` (s:ss) = (tagOf_SimplSwitch sw) _EQ_ (tagOf_SimplSwitch s)
- || sw `is_elem` ss
+%************************************************************************
+%* *
+\subsection{List of static hsc flags}
+%* *
+%************************************************************************
+
+\begin{code}
+isStaticHscFlag f =
+ f `elem` [
+ "fauto-sccs-on-all-toplevs",
+ "fauto-sccs-on-exported-toplevs",
+ "fauto-sccs-on-individual-cafs",
+ "fauto-sccs-on-dicts",
+ "fscc-profiling",
+ "fticky-ticky",
+ "fall-strict",
+ "fdicts-strict",
+ "firrefutable-tuples",
+ "fparallel",
+ "fsmp",
+ "fflatten",
+ "fsemi-tagging",
+ "flet-no-escape",
+ "femit-extern-decls",
+ "fglobalise-toplev-names",
+ "fgransim",
+ "fno-hi-version-check",
+ "dno-black-holing",
+ "fno-method-sharing",
+ "fno-state-hack",
+ "fruntime-types",
+ "fno-pre-inlining",
+ "fexcess-precision",
+ "funfolding-update-in-place",
+ "static",
+ "funregisterised",
+ "fext-core",
+ "frule-check",
+ "frules-off",
+ "fcpr-off",
+ "ferror-spans",
+ "fPIC"
+ ]
+ || any (flip prefixMatch f) [
+ "fcontext-stack",
+ "fliberate-case-threshold",
+ "fmax-worker-args",
+ "fhistory-size",
+ "funfolding-creation-threshold",
+ "funfolding-use-threshold",
+ "funfolding-fun-discount",
+ "funfolding-keeness-factor"
+ ]
\end{code}
%************************************************************************
%* *
-\subsection[CmdLineOpts-misc]{Misc functions for command-line options}
+\subsection{Misc functions for command-line options}
%* *
%************************************************************************
+
\begin{code}
-switchIsOn :: (switch -> SwitchResult) -> switch -> Bool
-
-switchIsOn lookup_fn switch
- = case (lookup_fn switch) of
- SwBool False -> False
- _ -> True
-
-stringSwitchSet :: (switch -> SwitchResult)
- -> (String -> switch)
- -> Maybe String
-
-stringSwitchSet lookup_fn switch
- = case (lookup_fn (switch (panic "stringSwitchSet"))) of
- SwString str -> Just str
- _ -> Nothing
-
-intSwitchSet :: (switch -> SwitchResult)
- -> (Int -> switch)
- -> Maybe Int
-
-intSwitchSet lookup_fn switch
- = -- pprTrace "intSwitchSet:" (ppInt (IBOX (tagOf_Switch (switch (panic "xxx"))))) $
- case (lookup_fn (switch (panic "intSwitchSet"))) of
- SwInt int -> Just int
- _ -> Nothing
+startsWith :: String -> String -> Maybe String
+-- startsWith pfx (pfx++rest) = Just rest
+
+startsWith [] str = Just str
+startsWith (c:cs) (s:ss)
+ = if c /= s then Nothing else startsWith cs ss
+startsWith _ [] = Nothing
\end{code}
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