%
-% (c) The GRASP/AQUA Project, Glasgow University, 1992-1996
+% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
%
\section[SimplCore]{Driver for simplifying @Core@ programs}
\begin{code}
-#include "HsVersions.h"
-
module SimplCore ( core2core ) where
-IMP_Ubiq(){-uitous-}
-IMPORT_1_3(IO(hPutStr,stderr))
-
-import AnalFBWW ( analFBWW )
-import Bag ( isEmptyBag, foldBag )
-import BinderInfo ( BinderInfo{-instance Outputable-} )
-import CmdLineOpts ( CoreToDo(..), SimplifierSwitch(..), switchIsOn,
- opt_D_show_passes,
- opt_D_simplifier_stats,
- opt_D_verbose_core2core,
- opt_DoCoreLinting,
- opt_FoldrBuildOn,
- opt_ReportWhyUnfoldingsDisallowed,
- opt_ShowImportSpecs,
- opt_LiberateCaseThreshold
+#include "HsVersions.h"
+
+import CmdLineOpts ( CoreToDo(..), SimplifierSwitch(..),
+ SwitchResult(..), intSwitchSet,
+ opt_UsageSPOn,
+ DynFlags, DynFlag(..), dopt
)
-import CoreLint ( lintCoreBindings )
+import CoreLint ( beginPass, endPass )
import CoreSyn
-import CoreUtils ( coreExprType )
-import SimplUtils ( etaCoreExpr, typeOkForCase )
+import CoreFVs ( ruleSomeFreeVars )
+import HscTypes ( PackageRuleBase, HomeSymbolTable, ModDetails(..) )
+import CSE ( cseProgram )
+import Rules ( RuleBase, emptyRuleBase, ruleBaseFVs, ruleBaseIds, extendRuleBaseList, addRuleBaseFVs )
+import Module ( moduleEnvElts )
import CoreUnfold
-import Literal ( Literal(..), literalType, mkMachInt )
-import ErrUtils ( ghcExit )
-import FiniteMap ( FiniteMap )
+import PprCore ( pprCoreBindings, pprIdCoreRule )
+import OccurAnal ( occurAnalyseBinds )
+import CoreUtils ( etaReduceExpr, coreBindsSize )
+import Simplify ( simplTopBinds, simplExpr )
+import SimplUtils ( simplBinders )
+import SimplMonad
+import ErrUtils ( dumpIfSet, dumpIfSet_dyn )
import FloatIn ( floatInwards )
import FloatOut ( floatOutwards )
-import FoldrBuildWW ( mkFoldrBuildWW )
-import Id ( mkSysLocal, setIdVisibility, replaceIdInfo,
- replacePragmaInfo, getIdDemandInfo, idType,
- getIdInfo, getPragmaInfo, mkIdWithNewUniq,
- nullIdEnv, addOneToIdEnv, delOneFromIdEnv,
- lookupIdEnv, SYN_IE(IdEnv), omitIfaceSigForId,
- apply_to_Id,
- GenId{-instance Outputable-}, SYN_IE(Id)
- )
-import IdInfo ( willBeDemanded, DemandInfo )
-import Name ( isExported, isLocallyDefined,
- isLocalName, uniqToOccName,
- SYN_IE(Module), NamedThing(..), OccName(..)
- )
-import TyCon ( TyCon )
-import PrimOp ( PrimOp(..) )
-import PrelVals ( unpackCStringId, unpackCString2Id,
- integerZeroId, integerPlusOneId,
- integerPlusTwoId, integerMinusOneId
- )
-import Type ( maybeAppDataTyCon, isPrimType, SYN_IE(Type) )
-import TysWiredIn ( stringTy, isIntegerTy )
+import Id ( Id, isDataConWrapId, setIdNoDiscard )
+import VarSet
import LiberateCase ( liberateCase )
-import MagicUFs ( MagicUnfoldingFun )
-import Outputable ( PprStyle(..), Outputable(..){-instance * (,) -} )
-import PprCore
-import PprType ( GenType{-instance Outputable-}, GenTyVar{-ditto-},
- nmbrType
- )
-import Pretty ( Doc, vcat, ($$), hsep )
import SAT ( doStaticArgs )
-import SimplMonad ( zeroSimplCount, showSimplCount, SimplCount )
-import SimplPgm ( simplifyPgm )
-import Specialise
-import SpecUtils ( pprSpecErrs )
-import StrictAnal ( saWwTopBinds )
-import TyVar ( SYN_IE(TyVar), nullTyVarEnv, GenTyVar{-instance Eq-},
- nameTyVar
- )
-import Unique ( Unique{-instance Eq-}, Uniquable(..),
- integerTyConKey, ratioTyConKey,
- mkUnique, incrUnique,
- initTidyUniques
- )
-import UniqSupply ( UniqSupply, mkSplitUniqSupply,
- splitUniqSupply, getUnique
- )
-import UniqFM ( UniqFM, lookupUFM, addToUFM )
-import Usage ( SYN_IE(UVar), cloneUVar )
-import Util ( mapAccumL, assertPanic, panic{-ToDo:rm-}, pprTrace, pprPanic )
-import SrcLoc ( noSrcLoc )
-import Constants ( tARGET_MIN_INT, tARGET_MAX_INT )
-import Bag
-import Maybes
-
-
-#ifndef OMIT_DEFORESTER
-import Deforest ( deforestProgram )
-import DefUtils ( deforestable )
-#endif
+import Specialise ( specProgram)
+import UsageSPInf ( doUsageSPInf )
+import StrictAnal ( saBinds )
+import WorkWrap ( wwTopBinds )
+import CprAnalyse ( cprAnalyse )
-\end{code}
-
-\begin{code}
-core2core :: [CoreToDo] -- spec of what core-to-core passes to do
- -> FAST_STRING -- module name (profiling only)
- -> PprStyle -- printing style (for debugging only)
- -> UniqSupply -- a name supply
- -> [TyCon] -- local data tycons and tycon specialisations
- -> FiniteMap TyCon [(Bool, [Maybe Type])]
- -> [CoreBinding] -- input...
- -> IO
- ([CoreBinding], -- results: program, plus...
- SpecialiseData) -- specialisation data
-
-core2core core_todos module_name ppr_style us local_tycons tycon_specs binds
- = -- Print heading
- (if opt_D_verbose_core2core then
- hPutStr stderr "VERBOSE CORE-TO-CORE:\n"
- else return ()) >>
-
- -- Do the main business
- foldl_mn do_core_pass
- (binds, us, init_specdata, zeroSimplCount)
- core_todos
- >>= \ (processed_binds, us', spec_data, simpl_stats) ->
-
- -- Do the final tidy-up
- let
- final_binds = core_linter "TidyCorePgm" True $
- tidyCorePgm module_name processed_binds
- in
-
- -- Report statistics
- (if opt_D_simplifier_stats then
- hPutStr stderr ("\nSimplifier Stats:\n") >>
- hPutStr stderr (showSimplCount simpl_stats) >>
- hPutStr stderr "\n"
- else return ()) >>
-
- --
- return (final_binds, spec_data)
- where
- init_specdata = initSpecData local_tycons tycon_specs
-
- -------------
- core_linter what spec_done
- = if opt_DoCoreLinting
- then (if opt_D_show_passes then
- trace ("\n*** Core Lint result of " ++ what)
- else id
- )
- lintCoreBindings ppr_style what spec_done
- else id
-
- --------------
- do_core_pass info@(binds, us, spec_data, simpl_stats) to_do =
- case (splitUniqSupply us) of
- (us1,us2) ->
- case to_do of
- CoreDoSimplify simpl_sw_chkr
- -> _scc_ "CoreSimplify"
- begin_pass ("Simplify" ++ if switchIsOn simpl_sw_chkr SimplDoFoldrBuild
- then " (foldr/build)" else "") >>
- case (simplifyPgm binds simpl_sw_chkr simpl_stats us1) of
- (p, it_cnt, simpl_stats2)
- -> end_pass False us2 p spec_data simpl_stats2
- ("Simplify (" ++ show it_cnt ++ ")"
- ++ if switchIsOn simpl_sw_chkr SimplDoFoldrBuild
- then " foldr/build" else "")
-
- CoreDoFoldrBuildWorkerWrapper
- -> _scc_ "CoreDoFoldrBuildWorkerWrapper"
- begin_pass "FBWW" >>
- case (mkFoldrBuildWW us1 binds) of { binds2 ->
- end_pass False us2 binds2 spec_data simpl_stats "FBWW" }
-
- CoreDoFoldrBuildWWAnal
- -> _scc_ "CoreDoFoldrBuildWWAnal"
- begin_pass "AnalFBWW" >>
- case (analFBWW binds) of { binds2 ->
- end_pass False us2 binds2 spec_data simpl_stats "AnalFBWW" }
-
- CoreLiberateCase
- -> _scc_ "LiberateCase"
- begin_pass "LiberateCase" >>
- case (liberateCase opt_LiberateCaseThreshold binds) of { binds2 ->
- end_pass False us2 binds2 spec_data simpl_stats "LiberateCase" }
-
- CoreDoFloatInwards
- -> _scc_ "FloatInwards"
- begin_pass "FloatIn" >>
- case (floatInwards binds) of { binds2 ->
- end_pass False us2 binds2 spec_data simpl_stats "FloatIn" }
-
- CoreDoFullLaziness
- -> _scc_ "CoreFloating"
- begin_pass "FloatOut" >>
- case (floatOutwards us1 binds) of { binds2 ->
- end_pass False us2 binds2 spec_data simpl_stats "FloatOut" }
-
- CoreDoStaticArgs
- -> _scc_ "CoreStaticArgs"
- begin_pass "StaticArgs" >>
- case (doStaticArgs binds us1) of { binds2 ->
- end_pass False us2 binds2 spec_data simpl_stats "StaticArgs" }
- -- Binds really should be dependency-analysed for static-
- -- arg transformation... Not to worry, they probably are.
- -- (I don't think it *dies* if they aren't [WDP 94/04/15])
-
- CoreDoStrictness
- -> _scc_ "CoreStranal"
- begin_pass "StrAnal" >>
- case (saWwTopBinds us1 binds) of { binds2 ->
- end_pass False us2 binds2 spec_data simpl_stats "StrAnal" }
-
- CoreDoSpecialising
- -> _scc_ "Specialise"
- begin_pass "Specialise" >>
- case (specProgram us1 binds spec_data) of {
- (p, spec_data2@(SpecData _ spec_noerrs _ _ _
- spec_errs spec_warn spec_tyerrs)) ->
-
- -- if we got errors, we die straight away
- (if not spec_noerrs ||
- (opt_ShowImportSpecs && not (isEmptyBag spec_warn)) then
- hPutStr stderr (show
- (pprSpecErrs module_name spec_errs spec_warn spec_tyerrs))
- >> hPutStr stderr "\n"
- else
- return ()) >>
-
- (if not spec_noerrs then -- Stop here if specialisation errors occured
- ghcExit 1
- else
- return ()) >>
-
- end_pass False us2 p spec_data2 simpl_stats "Specialise"
- }
-
- CoreDoDeforest
-#if OMIT_DEFORESTER
- -> error "ERROR: CoreDoDeforest: not built into compiler\n"
-#else
- -> _scc_ "Deforestation"
- begin_pass "Deforestation" >>
- case (deforestProgram binds us1) of { binds2 ->
- end_pass False us2 binds2 spec_data simpl_stats "Deforestation" }
-#endif
+import UniqSupply ( UniqSupply, mkSplitUniqSupply, splitUniqSupply )
+import IO ( hPutStr, stderr )
+import Outputable
- CoreDoPrintCore -- print result of last pass
- -> end_pass True us2 binds spec_data simpl_stats "Print"
-
- -------------------------------------------------
-
- begin_pass
- = if opt_D_show_passes
- then \ what -> hPutStr stderr ("*** Core2Core: "++what++"\n")
- else \ what -> return ()
-
- end_pass print us2 binds2
- spec_data2@(SpecData spec_done _ _ _ _ _ _ _)
- simpl_stats2 what
- = -- report verbosely, if required
- (if (opt_D_verbose_core2core && not print) ||
- (print && not opt_D_verbose_core2core)
- then
- hPutStr stderr ("\n*** "++what++":\n")
- >>
- hPutStr stderr (show
- (vcat (map (pprCoreBinding ppr_style) binds2)))
- >>
- hPutStr stderr "\n"
- else
- return ()) >>
- let
- linted_binds = core_linter what spec_done binds2
- in
- return
- (linted_binds, -- processed binds, possibly run thru CoreLint
- us2, -- UniqSupply for the next guy
- spec_data2, -- possibly-updated specialisation info
- simpl_stats2 -- accumulated simplifier stats
- )
-
--- here so it can be inlined...
-foldl_mn f z [] = return z
-foldl_mn f z (x:xs) = f z x >>= \ zz ->
- foldl_mn f zz xs
+import List ( partition )
\end{code}
-
-
%************************************************************************
%* *
-\subsection[SimplCore-indirections]{Eliminating indirections in Core code, and globalising}
+\subsection{The driver for the simplifier}
%* *
%************************************************************************
-Several tasks are done by @tidyCorePgm@
-
-1. Eliminate indirections. The point here is to transform
- x_local = E
- x_exported = x_local
- ==>
- x_exported = E
-
-2. Make certain top-level bindings into Globals. The point is that
- Global things get externally-visible labels at code generation
- time
-
-3. Make the representation of NoRep literals explicit, and
- float their bindings to the top level
-
-4. Convert
- case x of {...; x' -> ...x'...}
- ==>
- case x of {...; _ -> ...x... }
- See notes in SimplCase.lhs, near simplDefault for the reasoning here.
-
-5. *Mangle* cases involving fork# and par# in the discriminant. The
- original templates for these primops (see @PrelVals.lhs@) constructed
- case expressions with boolean results solely to fool the strictness
- analyzer, the simplifier, and anyone else who might want to fool with
- the evaluation order. At this point in the compiler our evaluation
- order is safe. Therefore, we convert expressions of the form:
-
- case par# e of
- True -> rhs
- False -> parError#
- ==>
- case par# e of
- _ -> rhs
-
-6. Eliminate polymorphic case expressions. We can't generate code for them yet.
-
-7. Do eta reduction for lambda abstractions appearing in:
- - the RHS of case alternatives
- - the body of a let
- These will otherwise turn into local bindings during Core->STG; better to
- nuke them if possible. (In general the simplifier does eta expansion not
- eta reduction, up to this point.)
-
-8. Do let-to-case. See notes in Simplify.lhs for why we defer let-to-case
- for multi-constructor types.
-
-9. Give all binders a nice print-name. Their uniques aren't changed; rather we give
- them lexically unique occ-names, so that we can safely print the OccNae only
- in the interface file. [Bad idea to change the uniques, because the code
- generator makes global labels from the uniques for local thunks etc.]
-
-
-Eliminate indirections
-~~~~~~~~~~~~~~~~~~~~~~
-In @elimIndirections@, we look for things at the top-level of the form...
-\begin{verbatim}
- x_local = ....
- x_exported = x_local
-\end{verbatim}
-In cases we find like this, we go {\em backwards} and replace
-\tr{x_local} with \tr{x_exported}. This save a gratuitous jump
-(from \tr{x_exported} to \tr{x_local}), and makes strictness
-information propagate better.
-
-We rely on prior eta reduction to simplify things like
-\begin{verbatim}
- x_exported = /\ tyvars -> x_local tyvars
-==>
- x_exported = x_local
-\end{verbatim}
-
-If more than one exported thing is equal to a local thing (i.e., the
-local thing really is shared), then we do one only:
-\begin{verbatim}
- x_local = ....
- x_exported1 = x_local
- x_exported2 = x_local
-==>
- x_exported1 = ....
-
- x_exported2 = x_exported1
-\end{verbatim}
-
-There's a possibility of leaving unchanged something like this:
-\begin{verbatim}
- x_local = ....
- x_exported1 = x_local Int
-\end{verbatim}
-By the time we've thrown away the types in STG land this
-could be eliminated. But I don't think it's very common
-and it's dangerous to do this fiddling in STG land
-because we might elminate a binding that's mentioned in the
-unfolding for something.
-
-General Strategy: first collect the info; then make a \tr{Id -> Id} mapping.
-Then blast the whole program (LHSs as well as RHSs) with it.
-
-
-
-\begin{code}
-tidyCorePgm :: Module -> [CoreBinding] -> [CoreBinding]
-
-tidyCorePgm mod binds_in
- = initTM mod indirection_env $
- tidyTopBindings (catMaybes reduced_binds) `thenTM` \ binds ->
- returnTM (bagToList binds)
- where
- (indirection_env, reduced_binds) = mapAccumL try_bind nullIdEnv binds_in
-
- try_bind :: IdEnv CoreBinder -> CoreBinding -> (IdEnv CoreBinder, Maybe CoreBinding)
- try_bind env_so_far (NonRec exported_binder rhs)
- | isExported exported_binder && -- Only if this is exported
- maybeToBool maybe_rhs_id && -- and the RHS is a simple Id
-
- isLocallyDefined rhs_id && -- Only if this one is defined in this
- -- module, so that we *can* change its
- -- binding to be the exported thing!
-
- not (isExported rhs_id) && -- Only if this one is not itself exported,
- -- since the transformation will nuke it
-
- not (omitIfaceSigForId rhs_id) && -- Don't do the transformation if rhs_id is
- -- something like a constructor, whose
- -- definition is implicitly exported and
- -- which must not vanish.
- -- To illustrate the preceding check consider
- -- data T = MkT Int
- -- mkT = MkT
- -- f x = MkT (x+1)
- -- Here, we'll make a local, non-exported, defn for MkT, and without the
- -- above condition we'll transform it to:
- -- mkT = \x. MkT [x]
- -- f = \y. mkT (y+1)
- -- This is bad because mkT will get the IdDetails of MkT, and won't
- -- be exported. Also the code generator won't make a definition for
- -- the MkT constructor.
- -- Slightly gruesome, this.
-
- not (maybeToBool (lookupIdEnv env_so_far rhs_id))
- -- Only if not already substituted for
-
- = (addOneToIdEnv env_so_far rhs_id (ValBinder new_rhs_id), Nothing)
- where
- maybe_rhs_id = case etaCoreExpr rhs of
- Var rhs_id -> Just rhs_id
- other -> Nothing
- Just rhs_id = maybe_rhs_id
- new_rhs_id = exported_binder `replaceIdInfo` getIdInfo rhs_id
- `replacePragmaInfo` getPragmaInfo rhs_id
- -- NB: we keep the Pragmas and IdInfo for the old rhs_id!
- -- This is important; it might be marked "no-inline" by
- -- the occurrence analyser (because it's recursive), and
- -- we must not lose that information.
-
- try_bind env_so_far bind
- = (env_so_far, Just bind)
-\end{code}
-
-Top level bindings
-~~~~~~~~~~~~~~~~~~
-\begin{code}
-tidyTopBindings [] = returnTM emptyBag
-tidyTopBindings (b:bs)
- = tidyTopBinding b $
- tidyTopBindings bs
-
-tidyTopBinding :: CoreBinding
- -> TopTidyM (Bag CoreBinding)
- -> TopTidyM (Bag CoreBinding)
-
-tidyTopBinding (NonRec bndr rhs) thing_inside
- = initNestedTM (tidyCoreExpr rhs) `thenTM` \ (rhs',floats) ->
- mungeTopBinder bndr $ \ bndr' ->
- thing_inside `thenTM` \ binds ->
- returnTM ((floats `snocBag` NonRec bndr' rhs') `unionBags` binds)
-
-tidyTopBinding (Rec pairs) thing_inside
- = mungeTopBinders binders $ \ binders' ->
- initNestedTM (mapTM tidyCoreExpr rhss) `thenTM` \ (rhss', floats) ->
- thing_inside `thenTM` \ binds_inside ->
- returnTM ((floats `snocBag` Rec (binders' `zip` rhss')) `unionBags` binds_inside)
- where
- (binders, rhss) = unzip pairs
-\end{code}
-
-
-
-Expressions
-~~~~~~~~~~~
\begin{code}
-tidyCoreExpr (Var v) = lookupId v `thenTM` \ v' ->
- returnTM (Var v')
-
-tidyCoreExpr (Lit lit)
- = litToRep lit `thenTM` \ (_, lit_expr) ->
- returnTM lit_expr
-
-tidyCoreExpr (App fun arg)
- = tidyCoreExpr fun `thenTM` \ fun' ->
- tidyCoreArg arg `thenTM` \ arg' ->
- returnTM (App fun' arg')
-
-tidyCoreExpr (Con con args)
- = mapTM tidyCoreArg args `thenTM` \ args' ->
- returnTM (Con con args')
-
-tidyCoreExpr (Prim prim args)
- = mapTM tidyCoreArg args `thenTM` \ args' ->
- returnTM (Prim prim args')
-
-tidyCoreExpr (Lam (ValBinder v) body)
- = newId v $ \ v' ->
- tidyCoreExpr body `thenTM` \ body' ->
- returnTM (Lam (ValBinder v') body')
-
-tidyCoreExpr (Lam (TyBinder tv) body)
- = newTyVar tv $ \ tv' ->
- tidyCoreExpr body `thenTM` \ body' ->
- returnTM (Lam (TyBinder tv') body')
-
-tidyCoreExpr (Lam (UsageBinder uv) body)
- = newUVar uv $ \ uv' ->
- tidyCoreExpr body `thenTM` \ body' ->
- returnTM (Lam (UsageBinder uv') body')
-
- -- Try for let-to-case (see notes in Simplify.lhs for why
- -- some let-to-case stuff is deferred to now).
-tidyCoreExpr (Let (NonRec bndr rhs) body)
- | willBeDemanded (getIdDemandInfo bndr) &&
- typeOkForCase (idType bndr)
- = ASSERT( not (isPrimType (idType bndr)) )
- tidyCoreExpr (Case rhs (AlgAlts [] (BindDefault bndr body)))
-
-tidyCoreExpr (Let (NonRec bndr rhs) body)
- = tidyCoreExpr rhs `thenTM` \ rhs' ->
- newId bndr $ \ bndr' ->
- tidyCoreExprEta body `thenTM` \ body' ->
- returnTM (Let (NonRec bndr' rhs') body')
-
-tidyCoreExpr (Let (Rec pairs) body)
- = newIds bndrs $ \ bndrs' ->
- mapTM tidyCoreExpr rhss `thenTM` \ rhss' ->
- tidyCoreExprEta body `thenTM` \ body' ->
- returnTM (Let (Rec (bndrs' `zip` rhss')) body')
- where
- (bndrs, rhss) = unzip pairs
-
-tidyCoreExpr (SCC cc body)
- = tidyCoreExprEta body `thenTM` \ body' ->
- returnTM (SCC cc body')
-
-tidyCoreExpr (Coerce coercion ty body)
- = tidyCoreExprEta body `thenTM` \ body' ->
- tidyTy ty `thenTM` \ ty' ->
- returnTM (Coerce coercion ty' body')
-
--- Wierd case for par, seq, fork etc. See notes above.
-tidyCoreExpr (Case scrut@(Prim op args) (PrimAlts _ (BindDefault binder rhs)))
- | funnyParallelOp op
- = tidyCoreExpr scrut `thenTM` \ scrut' ->
- newId binder $ \ binder' ->
- tidyCoreExprEta rhs `thenTM` \ rhs' ->
- returnTM (Case scrut' (PrimAlts [] (BindDefault binder' rhs')))
-
--- Eliminate polymorphic case, for which we can't generate code just yet
-tidyCoreExpr (Case scrut (AlgAlts [] (BindDefault deflt_bndr rhs)))
- | not (typeOkForCase (idType deflt_bndr))
- = pprTrace "Warning: discarding polymorphic case:" (ppr PprDebug scrut) $
- case scrut of
- Var v -> extendEnvTM deflt_bndr v (tidyCoreExpr rhs)
- other -> tidyCoreExpr (Let (NonRec deflt_bndr scrut) rhs)
-
-tidyCoreExpr (Case scrut alts)
- = tidyCoreExpr scrut `thenTM` \ scrut' ->
- tidy_alts scrut' alts `thenTM` \ alts' ->
- returnTM (Case scrut' alts')
- where
- tidy_alts scrut (AlgAlts alts deflt)
- = mapTM tidy_alg_alt alts `thenTM` \ alts' ->
- tidy_deflt scrut deflt `thenTM` \ deflt' ->
- returnTM (AlgAlts alts' deflt')
-
- tidy_alts scrut (PrimAlts alts deflt)
- = mapTM tidy_prim_alt alts `thenTM` \ alts' ->
- tidy_deflt scrut deflt `thenTM` \ deflt' ->
- returnTM (PrimAlts alts' deflt')
-
- tidy_alg_alt (con,bndrs,rhs) = newIds bndrs $ \ bndrs' ->
- tidyCoreExprEta rhs `thenTM` \ rhs' ->
- returnTM (con, bndrs', rhs')
-
- tidy_prim_alt (lit,rhs) = tidyCoreExprEta rhs `thenTM` \ rhs' ->
- returnTM (lit,rhs')
-
- -- We convert case x of {...; x' -> ...x'...}
- -- to
- -- case x of {...; _ -> ...x... }
- --
- -- See notes in SimplCase.lhs, near simplDefault for the reasoning.
- -- It's quite easily done: simply extend the environment to bind the
- -- default binder to the scrutinee.
-
- tidy_deflt scrut NoDefault = returnTM NoDefault
- tidy_deflt scrut (BindDefault bndr rhs)
- = newId bndr $ \ bndr' ->
- extend_env (tidyCoreExprEta rhs) `thenTM` \ rhs' ->
- returnTM (BindDefault bndr' rhs')
- where
- extend_env = case scrut of
- Var v -> extendEnvTM bndr v
- other -> \x -> x
-
-tidyCoreExprEta e = tidyCoreExpr e `thenTM` \ e' ->
- returnTM (etaCoreExpr e')
+core2core :: DynFlags
+ -> PackageRuleBase -- Rule-base accumulated from imported packages
+ -> HomeSymbolTable
+ -> [CoreToDo] -- Spec of what core-to-core passes to do
+ -> [CoreBind] -- Binds in
+ -> [IdCoreRule] -- Rules in
+ -> IO ([CoreBind], [IdCoreRule]) -- binds, local orphan rules out
+
+core2core dflags pkg_rule_base hst core_todos binds rules
+ = do
+ us <- mkSplitUniqSupply 's'
+ let (cp_us, ru_us) = splitUniqSupply us
+
+ -- COMPUTE THE RULE BASE TO USE
+ (rule_base, binds1, orphan_rules)
+ <- prepareRules dflags pkg_rule_base hst ru_us binds rules
+
+
+ -- DO THE BUSINESS
+ (stats, processed_binds)
+ <- doCorePasses dflags rule_base (zeroSimplCount dflags) cp_us binds1 core_todos
+
+ dumpIfSet_dyn dflags Opt_D_dump_simpl_stats
+ "Grand total simplifier statistics"
+ (pprSimplCount stats)
+
+ -- Return results
+ -- We only return local orphan rules, i.e., local rules not attached to an Id
+ -- The bindings cotain more rules, embedded in the Ids
+ return (processed_binds, orphan_rules)
+
+
+doCorePasses :: DynFlags
+ -> RuleBase -- the main rule base
+ -> SimplCount -- simplifier stats
+ -> UniqSupply -- uniques
+ -> [CoreBind] -- local binds in (with rules attached)
+ -> [CoreToDo] -- which passes to do
+ -> IO (SimplCount, [CoreBind]) -- stats, binds, local orphan rules
+
+doCorePasses dflags rb stats us binds []
+ = return (stats, binds)
+
+doCorePasses dflags rb stats us binds (to_do : to_dos)
+ = do
+ let (us1, us2) = splitUniqSupply us
+
+ (stats1, binds1) <- doCorePass dflags rb us1 binds to_do
+
+ doCorePasses dflags rb (stats `plusSimplCount` stats1) us2 binds1 to_dos
+
+doCorePass dfs rb us binds (CoreDoSimplify sw_chkr)
+ = _scc_ "Simplify" simplifyPgm dfs rb sw_chkr us binds
+doCorePass dfs rb us binds CoreCSE
+ = _scc_ "CommonSubExpr" noStats dfs (cseProgram dfs binds)
+doCorePass dfs rb us binds CoreLiberateCase
+ = _scc_ "LiberateCase" noStats dfs (liberateCase dfs binds)
+doCorePass dfs rb us binds CoreDoFloatInwards
+ = _scc_ "FloatInwards" noStats dfs (floatInwards dfs binds)
+doCorePass dfs rb us binds (CoreDoFloatOutwards f)
+ = _scc_ "FloatOutwards" noStats dfs (floatOutwards dfs f us binds)
+doCorePass dfs rb us binds CoreDoStaticArgs
+ = _scc_ "StaticArgs" noStats dfs (doStaticArgs us binds)
+doCorePass dfs rb us binds CoreDoStrictness
+ = _scc_ "Stranal" noStats dfs (saBinds dfs binds)
+doCorePass dfs rb us binds CoreDoWorkerWrapper
+ = _scc_ "WorkWrap" noStats dfs (wwTopBinds dfs us binds)
+doCorePass dfs rb us binds CoreDoSpecialising
+ = _scc_ "Specialise" noStats dfs (specProgram dfs us binds)
+doCorePass dfs rb us binds CoreDoCPResult
+ = _scc_ "CPResult" noStats dfs (cprAnalyse dfs binds)
+doCorePass dfs rb us binds CoreDoPrintCore
+ = _scc_ "PrintCore" noStats dfs (printCore binds)
+doCorePass dfs rb us binds CoreDoUSPInf
+ = _scc_ "CoreUsageSPInf" noStats dfs (doUsageSPInf dfs us binds)
+doCorePass dfs rb us binds CoreDoGlomBinds
+ = noStats dfs (glomBinds dfs binds)
+
+printCore binds = do dumpIfSet True "Print Core"
+ (pprCoreBindings binds)
+ return binds
+
+-- most passes return no stats and don't change rules
+noStats dfs thing = do { binds <- thing; return (zeroSimplCount dfs, binds) }
\end{code}
-Arguments
-~~~~~~~~~
-\begin{code}
-tidyCoreArg :: CoreArg -> NestTidyM CoreArg
-
-tidyCoreArg (VarArg v)
- = lookupId v `thenTM` \ v' ->
- returnTM (VarArg v')
-
-tidyCoreArg (LitArg lit)
- = litToRep lit `thenTM` \ (lit_ty, lit_expr) ->
- case lit_expr of
- Var v -> returnTM (VarArg v)
- Lit l -> returnTM (LitArg l)
- other -> addTopFloat lit_ty lit_expr `thenTM` \ v ->
- returnTM (VarArg v)
-
-tidyCoreArg (TyArg ty) = tidyTy ty `thenTM` \ ty' ->
- returnTM (TyArg ty')
-tidyCoreArg (UsageArg u) = returnTM (UsageArg u)
-\end{code}
%************************************************************************
%* *
-\subsection[coreToStg-lits]{Converting literals}
+\subsection{Dealing with rules}
%* *
%************************************************************************
-Literals: the NoRep kind need to be de-no-rep'd.
-We always replace them with a simple variable, and float a suitable
-binding out to the top level.
+-- prepareLocalRuleBase takes the CoreBinds and rules defined in this module.
+-- It attaches those rules that are for local Ids to their binders, and
+-- returns the remainder attached to Ids in an IdSet. It also returns
+-- Ids mentioned on LHS of some rule; these should be blacklisted.
-\begin{code}
-
-litToRep :: Literal -> NestTidyM (Type, CoreExpr)
+-- The rule Ids and LHS Ids are black-listed; that is, they aren't inlined
+-- so that the opportunity to apply the rule isn't lost too soon
-litToRep (NoRepStr s)
- = returnTM (stringTy, rhs)
+\begin{code}
+prepareRules :: DynFlags -> PackageRuleBase -> HomeSymbolTable
+ -> UniqSupply
+ -> [CoreBind] -> [IdCoreRule] -- Local bindings and rules
+ -> IO (RuleBase, -- Full rule base
+ [CoreBind], -- Bindings augmented with rules
+ [IdCoreRule]) -- Orphan rules
+
+prepareRules dflags pkg_rule_base hst us binds rules
+ = do { let (better_rules,_) = initSmpl dflags sw_chkr us local_ids black_list_all
+ (mapSmpl simplRule rules)
+
+ ; dumpIfSet_dyn dflags Opt_D_dump_rules "Transformation rules"
+ (vcat (map pprIdCoreRule better_rules))
+
+ ; let (local_id_rules, orphan_rules) = partition ((`elemVarSet` local_ids) . fst) better_rules
+ (binds1, local_rule_fvs) = addRulesToBinds binds local_id_rules
+ imp_rule_base = foldl add_rules pkg_rule_base (moduleEnvElts hst)
+ rule_base = extendRuleBaseList imp_rule_base orphan_rules
+ final_rule_base = addRuleBaseFVs rule_base local_rule_fvs
+ -- The last step black-lists the free vars of local rules too
+
+ ; return (final_rule_base, binds1, orphan_rules)
+ }
where
- rhs = if (any is_NUL (_UNPK_ s))
+ sw_chkr any = SwBool False -- A bit bogus
+ black_list_all v = not (isDataConWrapId v)
+ -- This stops all inlining except the
+ -- wrappers for data constructors
+
+ add_rules rule_base mds = extendRuleBaseList rule_base (md_rules mds)
+
+ -- Boringly, we need to gather the in-scope set.
+ -- Typically this thunk won't even be forced, but the test in
+ -- simpVar fails if it isn't right, and it might conceiveably matter
+ local_ids = foldr (unionVarSet . mkVarSet . bindersOf) emptyVarSet binds
+
+addRulesToBinds :: [CoreBind] -> [(Id,CoreRule)] -> ([CoreBind], IdSet)
+ -- A horrible function
+
+ -- Attach the rules for each locally-defined Id to that Id.
+ -- - This makes the rules easier to look up
+ -- - It means that transformation rules and specialisations for
+ -- locally defined Ids are handled uniformly
+ -- - It keeps alive things that are referred to only from a rule
+ -- (the occurrence analyser knows about rules attached to Ids)
+ -- - It makes sure that, when we apply a rule, the free vars
+ -- of the RHS are more likely to be in scope
+ --
+ -- Both the LHS and RHS Ids are marked 'no-discard'.
+ -- This means that the binding won't be discarded EVEN if the binding
+ -- ends up being trivial (v = w) -- the simplifier would usually just
+ -- substitute w for v throughout, but we don't apply the substitution to
+ -- the rules (maybe we should?), so this substitution would make the rule
+ -- bogus.
+
+addRulesToBinds binds local_rules
+ = (map zap_bind binds, rule_lhs_fvs)
+ where
+ -- rule_fvs is the set of all variables mentioned in this module's rules
+ rule_fvs = unionVarSets [ ruleSomeFreeVars isId rule | (_,rule) <- local_rules ]
- then -- Must cater for NULs in literal string
- mkGenApp (Var unpackCString2Id)
- [LitArg (MachStr s),
- LitArg (mkMachInt (toInteger (_LENGTH_ s)))]
+ rule_base = extendRuleBaseList emptyRuleBase local_rules
+ rule_lhs_fvs = ruleBaseFVs rule_base
+ rule_ids = ruleBaseIds rule_base
- else -- No NULs in the string
- App (Var unpackCStringId) (LitArg (MachStr s))
+ zap_bind (NonRec b r) = NonRec (zap_bndr b) r
+ zap_bind (Rec prs) = Rec [(zap_bndr b, r) | (b,r) <- prs]
- is_NUL c = c == '\0'
+ zap_bndr bndr = case lookupVarSet rule_ids bndr of
+ Just bndr' -> setIdNoDiscard bndr'
+ Nothing | bndr `elemVarSet` rule_fvs -> setIdNoDiscard bndr
+ | otherwise -> bndr
\end{code}
-If an Integer is small enough (Haskell implementations must support
-Ints in the range $[-2^29+1, 2^29-1]$), wrap it up in @int2Integer@;
-otherwise, wrap with @litString2Integer@.
-\begin{code}
-litToRep (NoRepInteger i integer_ty)
- = returnTM (integer_ty, rhs)
- where
- rhs | i == 0 = Var integerZeroId -- Extremely convenient to look out for
- | i == 1 = Var integerPlusOneId -- a few very common Integer literals!
- | i == 2 = Var integerPlusTwoId
- | i == (-1) = Var integerMinusOneId
-
- | i > tARGET_MIN_INT && -- Small enough, so start from an Int
- i < tARGET_MAX_INT
- = Prim Int2IntegerOp [LitArg (mkMachInt i)]
-
- | otherwise -- Big, so start from a string
- = Prim Addr2IntegerOp [LitArg (MachStr (_PK_ (show i)))]
-
-
-litToRep (NoRepRational r rational_ty)
- = tidyCoreArg (LitArg (NoRepInteger (numerator r) integer_ty)) `thenTM` \ num_arg ->
- tidyCoreArg (LitArg (NoRepInteger (denominator r) integer_ty)) `thenTM` \ denom_arg ->
- returnTM (rational_ty, Con ratio_data_con [TyArg integer_ty, num_arg, denom_arg])
- where
- (ratio_data_con, integer_ty)
- = case (maybeAppDataTyCon rational_ty) of
- Just (tycon, [i_ty], [con])
- -> ASSERT(isIntegerTy i_ty && uniqueOf tycon == ratioTyConKey)
- (con, i_ty)
-
- _ -> (panic "ratio_data_con", panic "integer_ty")
-
-litToRep other_lit = returnTM (literalType other_lit, Lit other_lit)
-\end{code}
+We must do some gentle simplification on the template (but not the RHS)
+of each rule. The case that forced me to add this was the fold/build rule,
+which without simplification looked like:
+ fold k z (build (/\a. g a)) ==> ...
+This doesn't match unless you do eta reduction on the build argument.
\begin{code}
-funnyParallelOp SeqOp = True
-funnyParallelOp ParOp = True
-funnyParallelOp ForkOp = True
-funnyParallelOp _ = False
-\end{code}
+simplRule rule@(id, BuiltinRule _)
+ = returnSmpl rule
+simplRule rule@(id, Rule name bndrs args rhs)
+ = simplBinders bndrs $ \ bndrs' ->
+ mapSmpl simpl_arg args `thenSmpl` \ args' ->
+ simplExpr rhs `thenSmpl` \ rhs' ->
+ returnSmpl (id, Rule name bndrs' args' rhs')
+
+simpl_arg e
+-- I've seen rules in which a LHS like
+-- augment g (build h)
+-- turns into
+-- augment (\a. g a) (build h)
+-- So it's a help to eta-reduce the args as we simplify them.
+-- Otherwise we don't match when given an argument like
+-- (\a. h a a)
+ = simplExpr e `thenSmpl` \ e' ->
+ returnSmpl (etaReduceExpr e')
+\end{code}
%************************************************************************
%* *
-\subsection{The monad}
+\subsection{Glomming}
%* *
%************************************************************************
\begin{code}
-type TidyM a state = Module
- -> UniqFM CoreBinder -- Maps Ids to Ids, TyVars to TyVars etc
- -> state
- -> (a, state)
-
-type TopTidyM a = TidyM a Unique
-type NestTidyM a = TidyM a (Unique, -- Global names
- Unique, -- Local names
- Bag CoreBinding) -- Floats
-
-
-(initialTopTidyUnique, initialNestedTidyUnique) = initTidyUniques
-
-initTM :: Module -> UniqFM CoreBinder -> TopTidyM a -> a
-initTM mod env m
- = case m mod env initialTopTidyUnique of
- (result, _) -> result
-
-initNestedTM :: NestTidyM a -> TopTidyM (a, Bag CoreBinding)
-initNestedTM m mod env global_us
- = case m mod env (global_us, initialNestedTidyUnique, emptyBag) of
- (result, (global_us', _, floats)) -> ((result, floats), global_us')
-
-returnTM v mod env usf = (v, usf)
-thenTM m k mod env usf = case m mod env usf of
- (r, usf') -> k r mod env usf'
-
-mapTM f [] = returnTM []
-mapTM f (x:xs) = f x `thenTM` \ r ->
- mapTM f xs `thenTM` \ rs ->
- returnTM (r:rs)
-\end{code}
-
-
-\begin{code}
--- Need to extend the environment when we munge a binder, so that occurrences
--- of the binder will print the correct way (i.e. as a global not a local)
-mungeTopBinder :: Id -> (Id -> TopTidyM a) -> TopTidyM a
-mungeTopBinder id thing_inside mod env us
- = case lookupIdEnv env id of
- Just (ValBinder global) -> thing_inside global mod env us -- Already bound
-
- other -> -- Give it a new print-name unless it's an exported thing
- -- setNameVisibility also does the local/global thing
- let
- (id', us') | isExported id = (id, us)
- | otherwise
- = (setIdVisibility (Just mod) us id,
- incrUnique us)
-
- new_env = addToUFM env id (ValBinder id')
- in
- thing_inside id' mod new_env us'
-
-mungeTopBinders [] k = k []
-mungeTopBinders (b:bs) k = mungeTopBinder b $ \ b' ->
- mungeTopBinders bs $ \ bs' ->
- k (b' : bs')
-
-addTopFloat :: Type -> CoreExpr -> NestTidyM Id
-addTopFloat lit_ty lit_rhs mod env (gus, lus, floats)
- = let
- gus' = incrUnique gus
- lit_local = mkSysLocal SLIT("lit") gus lit_ty noSrcLoc
- lit_id = setIdVisibility (Just mod) gus lit_local
- in
- (lit_id, (gus', lus, floats `snocBag` NonRec lit_id lit_rhs))
-
-lookupId :: Id -> TidyM Id state
-lookupId v mod env usf
- = case lookupUFM env v of
- Nothing -> (v, usf)
- Just (ValBinder v') -> (v', usf)
-
-extendEnvTM :: Id -> Id -> (TidyM a state) -> TidyM a state
-extendEnvTM v v' m mod env usf
- = m mod (addOneToIdEnv env v (ValBinder v')) usf
+glomBinds :: DynFlags -> [CoreBind] -> IO [CoreBind]
+-- Glom all binds together in one Rec, in case any
+-- transformations have introduced any new dependencies
+--
+-- NB: the global invariant is this:
+-- *** the top level bindings are never cloned, and are always unique ***
+--
+-- We sort them into dependency order, but applying transformation rules may
+-- make something at the top refer to something at the bottom:
+-- f = \x -> p (q x)
+-- h = \y -> 3
+--
+-- RULE: p (q x) = h x
+--
+-- Applying this rule makes f refer to h,
+-- although it doesn't appear to in the source program.
+-- This pass lets us control where it happens.
+--
+-- NOTICE that this cannot happen for rules whose head is a locally-defined
+-- function. It only happens for rules whose head is an imported function
+-- (p in the example above). So, for example, the rule had been
+-- RULE: f (p x) = h x
+-- then the rule for f would be attached to f itself (in its IdInfo)
+-- by prepareLocalRuleBase and h would be regarded by the occurrency
+-- analyser as free in f.
+
+glomBinds dflags binds
+ = do { beginPass dflags "GlomBinds" ;
+ let { recd_binds = [Rec (flattenBinds binds)] } ;
+ return recd_binds }
+ -- Not much point in printing the result...
+ -- just consumes output bandwidth
\end{code}
-Making new local binders
-~~~~~~~~~~~~~~~~~~~~~~~~
-\begin{code}
-newId id thing_inside mod env (gus, local_uniq, floats)
- = let
- -- Give the Id a fresh print-name, *and* rename its type
- local_uniq' = incrUnique local_uniq
- rn_id = setIdVisibility Nothing local_uniq id
- id' = apply_to_Id (nmbr_ty env local_uniq') rn_id
- env' = addToUFM env id (ValBinder id')
- in
- thing_inside id' mod env' (gus, local_uniq', floats)
-
-newIds [] thing_inside
- = thing_inside []
-newIds (bndr:bndrs) thing_inside
- = newId bndr $ \ bndr' ->
- newIds bndrs $ \ bndrs' ->
- thing_inside (bndr' : bndrs')
-
-
-newTyVar tyvar thing_inside mod env (gus, local_uniq, floats)
- = let
- local_uniq' = incrUnique local_uniq
- tyvar' = nameTyVar tyvar (uniqToOccName local_uniq)
- env' = addToUFM env tyvar (TyBinder tyvar')
- in
- thing_inside tyvar' mod env' (gus, local_uniq', floats)
-
-newUVar uvar thing_inside mod env (gus, local_uniq, floats)
- = let
- local_uniq' = incrUnique local_uniq
- uvar' = cloneUVar uvar local_uniq
- env' = addToUFM env uvar (UsageBinder uvar')
- in
- thing_inside uvar' mod env' (gus, local_uniq', floats)
-\end{code}
+%************************************************************************
+%* *
+\subsection{The driver for the simplifier}
+%* *
+%************************************************************************
-Re-numbering types
-~~~~~~~~~~~~~~~~~~
\begin{code}
-tidyTy ty mod env usf@(_, local_uniq, _)
- = (nmbr_ty env local_uniq ty, usf)
- -- We can use local_uniq as a base for renaming forall'd variables
- -- in the type; we don't need to know how many are consumed.
-
--- This little impedance-matcher calls nmbrType with the right arguments
-nmbr_ty env uniq ty
- = nmbrType tv_env u_env uniq ty
+simplifyPgm :: DynFlags
+ -> RuleBase
+ -> (SimplifierSwitch -> SwitchResult)
+ -> UniqSupply
+ -> [CoreBind] -- Input
+ -> IO (SimplCount, [CoreBind]) -- New bindings
+
+simplifyPgm dflags rule_base
+ sw_chkr us binds
+ = do {
+ beginPass dflags "Simplify";
+
+ (termination_msg, it_count, counts_out, binds')
+ <- iteration us 1 (zeroSimplCount dflags) binds;
+
+ dumpIfSet (dopt Opt_D_verbose_core2core dflags
+ && dopt Opt_D_dump_simpl_stats dflags)
+ "Simplifier statistics"
+ (vcat [text termination_msg <+> text "after" <+> ppr it_count <+> text "iterations",
+ text "",
+ pprSimplCount counts_out]);
+
+ endPass dflags "Simplify"
+ (dopt Opt_D_verbose_core2core dflags
+ && not (dopt Opt_D_dump_simpl_iterations dflags))
+ binds' ;
+
+ return (counts_out, binds')
+ }
where
- tv_env :: TyVar -> TyVar
- tv_env tyvar = case lookupUFM env tyvar of
- Just (TyBinder tyvar') -> tyvar'
- other -> tyvar
-
- u_env :: UVar -> UVar
- u_env uvar = case lookupUFM env uvar of
- Just (UsageBinder uvar') -> uvar'
- other -> uvar
-\end{code}
+ max_iterations = getSimplIntSwitch sw_chkr MaxSimplifierIterations
+ black_list_fn = blackListed rule_lhs_fvs (intSwitchSet sw_chkr SimplInlinePhase)
+ imported_rule_ids = ruleBaseIds rule_base
+ rule_lhs_fvs = ruleBaseFVs rule_base
+
+ iteration us iteration_no counts binds
+ -- Try and force thunks off the binds; significantly reduces
+ -- space usage, especially with -O. JRS, 000620.
+ | let sz = coreBindsSize binds in sz == sz
+ = do {
+ -- Occurrence analysis
+ let { tagged_binds = _scc_ "OccAnal" occurAnalyseBinds binds } ;
+
+ dumpIfSet_dyn dflags Opt_D_dump_occur_anal "Occurrence analysis"
+ (pprCoreBindings tagged_binds);
+
+ -- SIMPLIFY
+ -- We do this with a *case* not a *let* because lazy pattern
+ -- matching bit us with bad space leak!
+ -- With a let, we ended up with
+ -- let
+ -- t = initSmpl ...
+ -- counts' = snd t
+ -- in
+ -- case t of {(_,counts') -> if counts'=0 then ...
+ -- So the conditional didn't force counts', because the
+ -- selection got duplicated. Sigh!
+ case initSmpl dflags sw_chkr us1 imported_rule_ids black_list_fn
+ (simplTopBinds tagged_binds)
+ of { (binds', counts') -> do {
+ -- The imported_rule_ids are used by initSmpl to initialise
+ -- the in-scope set. That way, the simplifier will change any
+ -- occurrences of the imported id to the one in the imported_rule_ids
+ -- set, which are decorated with their rules.
+
+ let { all_counts = counts `plusSimplCount` counts' } ;
+
+ -- Stop if nothing happened; don't dump output
+ if isZeroSimplCount counts' then
+ return ("Simplifier reached fixed point", iteration_no, all_counts, binds')
+ else do {
+
+ -- Dump the result of this iteration
+ dumpIfSet_dyn dflags Opt_D_dump_simpl_iterations
+ ("Simplifier iteration " ++ show iteration_no
+ ++ " out of " ++ show max_iterations)
+ (pprSimplCount counts') ;
+
+ if dopt Opt_D_dump_simpl_iterations dflags then
+ endPass dflags
+ ("Simplifier iteration " ++ show iteration_no ++ " result")
+ (dopt Opt_D_verbose_core2core dflags)
+ binds'
+ else
+ return [] ;
+
+ -- Stop if we've run out of iterations
+ if iteration_no == max_iterations then
+ do {
+#ifdef DEBUG
+ if max_iterations > 2 then
+ hPutStr stderr ("NOTE: Simplifier still going after " ++
+ show max_iterations ++
+ " iterations; bailing out.\n")
+ else
+#endif
+ return ();
+ return ("Simplifier baled out", iteration_no, all_counts, binds')
+ }
+ -- Else loop
+ else iteration us2 (iteration_no + 1) all_counts binds'
+ } } } }
+ where
+ (us1, us2) = splitUniqSupply us
+\end{code}
projects / ghc-hetmet.git / blobdiff