+import Specialise ( specProgram)
+import UsageSPInf ( doUsageSPInf )
+import StrictAnal ( saBinds )
+import WorkWrap ( wwTopBinds )
+import CprAnalyse ( cprAnalyse )
+
+import Unique ( Unique, Uniquable(..),
+ ratioTyConKey
+ )
+import UniqSupply ( UniqSupply, mkSplitUniqSupply, splitUniqSupply, uniqFromSupply )
+import Constants ( tARGET_MIN_INT, tARGET_MAX_INT )
+import Util ( mapAccumL )
+import SrcLoc ( noSrcLoc )
+import Bag
+import Maybes
+import IO ( hPutStr, stderr )
+import Outputable
+
+import Ratio ( numerator, denominator )
+\end{code}
+
+%************************************************************************
+%* *
+\subsection{The driver for the simplifier}
+%* *
+%************************************************************************
+
+\begin{code}
+core2core :: [CoreToDo] -- Spec of what core-to-core passes to do
+ -> [CoreBind] -- Binds in
+ -> [ProtoCoreRule] -- Rules
+ -> IO ([CoreBind], [ProtoCoreRule])
+
+core2core core_todos binds rules
+ = do
+ us <- mkSplitUniqSupply 's'
+ let (cp_us, us1) = splitUniqSupply us
+ (ru_us, ps_us) = splitUniqSupply us1
+
+ better_rules <- simplRules ru_us rules binds
+
+ let (binds1, rule_base) = prepareRuleBase binds better_rules
+
+ -- Do the main business
+ (stats, processed_binds) <- doCorePasses zeroSimplCount cp_us binds1
+ rule_base core_todos
+
+ dumpIfSet opt_D_dump_simpl_stats
+ "Grand total simplifier statistics"
+ (pprSimplCount stats)
+
+ -- Do the post-simplification business
+ post_simpl_binds <- doPostSimplification ps_us processed_binds
+
+ -- Return results
+ return (post_simpl_binds, filter orphanRule better_rules)
+
+
+doCorePasses stats us binds irs []
+ = return (stats, binds)
+
+doCorePasses stats us binds irs (to_do : to_dos)
+ = do
+ let (us1, us2) = splitUniqSupply us
+ (stats1, binds1) <- doCorePass us1 binds irs to_do
+ doCorePasses (stats `plusSimplCount` stats1) us2 binds1 irs to_dos
+
+doCorePass us binds rb (CoreDoSimplify sw_chkr) = _scc_ "Simplify" simplifyPgm rb sw_chkr us binds
+doCorePass us binds rb CoreCSE = _scc_ "CommonSubExpr" noStats (cseProgram binds)
+doCorePass us binds rb CoreLiberateCase = _scc_ "LiberateCase" noStats (liberateCase binds)
+doCorePass us binds rb CoreDoFloatInwards = _scc_ "FloatInwards" noStats (floatInwards binds)
+doCorePass us binds rb CoreDoFullLaziness = _scc_ "FloatOutwards" noStats (floatOutwards us binds)
+doCorePass us binds rb CoreDoStaticArgs = _scc_ "StaticArgs" noStats (doStaticArgs us binds)
+doCorePass us binds rb CoreDoStrictness = _scc_ "Stranal" noStats (saBinds binds)
+doCorePass us binds rb CoreDoWorkerWrapper = _scc_ "WorkWrap" noStats (wwTopBinds us binds)
+doCorePass us binds rb CoreDoSpecialising = _scc_ "Specialise" noStats (specProgram us binds)
+doCorePass us binds rb CoreDoCPResult = _scc_ "CPResult" noStats (cprAnalyse binds)
+doCorePass us binds rb CoreDoPrintCore = _scc_ "PrintCore" noStats (printCore binds)
+doCorePass us binds rb CoreDoUSPInf
+ = _scc_ "CoreUsageSPInf"
+ if opt_UsageSPOn then
+ noStats (doUsageSPInf us binds)
+ else
+ trace "WARNING: ignoring requested -fusagesp pass; requires -fusagesp-on" $
+ noStats (return binds)
+
+printCore binds = do dumpIfSet True "Print Core"
+ (pprCoreBindings binds)
+ return binds
+
+noStats thing = do { result <- thing; return (zeroSimplCount, result) }
+\end{code}
+
+
+%************************************************************************
+%* *
+\subsection{Dealing with rules}
+%* *
+%************************************************************************
+
+We must do some gentle simplifiation 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}
+simplRules :: UniqSupply -> [ProtoCoreRule] -> [CoreBind] -> IO [ProtoCoreRule]
+simplRules us rules binds
+ = do let (better_rules,_) = initSmpl sw_chkr us bind_vars black_list_all (mapSmpl simplRule rules)
+
+ dumpIfSet opt_D_dump_rules
+ "Transformation rules"
+ (vcat (map pprProtoCoreRule better_rules))
+
+ return better_rules
+ where
+ black_list_all v = True -- This stops all inlining
+ sw_chkr any = SwBool False -- A bit bogus
+
+ -- Boringly, we need to gather the in-scope set.
+ -- Typically this thunk won't even be force, but the test in
+ -- simpVar fails if it isn't right, and it might conceivably matter
+ bind_vars = foldr (unionVarSet . mkVarSet . bindersOf) emptyVarSet binds
+
+
+simplRule rule@(ProtoCoreRule is_local id (Rule name bndrs args rhs))
+ | not is_local
+ = returnSmpl rule -- No need to fiddle with imported rules
+ | otherwise
+ = simplBinders bndrs $ \ bndrs' ->
+ mapSmpl simplExpr args `thenSmpl` \ args' ->
+ simplExpr rhs `thenSmpl` \ rhs' ->
+ returnSmpl (ProtoCoreRule is_local id (Rule name bndrs' args' rhs'))
+\end{code}
+
+%************************************************************************
+%* *
+\subsection{The driver for the simplifier}
+%* *
+%************************************************************************
+
+\begin{code}
+simplifyPgm :: RuleBase
+ -> (SimplifierSwitch -> SwitchResult)
+ -> UniqSupply
+ -> [CoreBind] -- Input
+ -> IO (SimplCount, [CoreBind]) -- New bindings
+
+simplifyPgm (imported_rule_ids, rule_lhs_fvs)
+ sw_chkr us binds
+ = do {
+ beginPass "Simplify";
+
+ -- 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. Our solution is to do this occasional glom-together step,
+ -- just once per overall simplfication step.
+
+ let { recd_binds = [Rec (flattenBinds binds)] };
+
+ (termination_msg, it_count, counts_out, binds') <- iteration us 1 zeroSimplCount recd_binds;
+
+ dumpIfSet (opt_D_verbose_core2core && opt_D_dump_simpl_stats)
+ "Simplifier statistics"
+ (vcat [text termination_msg <+> text "after" <+> ppr it_count <+> text "iterations",
+ text "",
+ pprSimplCount counts_out]);
+
+ endPass "Simplify"
+ (opt_D_verbose_core2core && not opt_D_dump_simpl_iterations)
+ binds' ;
+
+ return (counts_out, binds')
+ }
+ where
+ max_iterations = getSimplIntSwitch sw_chkr MaxSimplifierIterations
+ black_list_fn = blackListed rule_lhs_fvs (intSwitchSet sw_chkr SimplInlinePhase)
+
+ core_iter_dump binds | opt_D_verbose_core2core = pprCoreBindings binds
+ | otherwise = empty
+
+ iteration us iteration_no counts binds
+ = do {
+ -- Occurrence analysis
+ let { tagged_binds = _scc_ "OccAnal" occurAnalyseBinds binds } ;
+
+ dumpIfSet opt_D_dump_occur_anal "Occurrence analysis"
+ (pprCoreBindings tagged_binds);
+
+ -- Simplify
+ let { (binds', counts') = initSmpl sw_chkr us1 imported_rule_ids
+ black_list_fn
+ (simplTopBinds tagged_binds);
+ -- 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.
+
+ 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 opt_D_dump_simpl_iterations
+ ("Simplifier iteration " ++ show iteration_no
+ ++ " out of " ++ show max_iterations)
+ (pprSimplCount counts') ;
+
+ if opt_D_dump_simpl_iterations then
+ endPass ("Simplifier iteration " ++ show iteration_no ++ " result")
+ opt_D_verbose_core2core
+ binds'
+ else
+ return [] ;
+
+ -- Stop if we've run out of iterations
+ if iteration_no == max_iterations then
+ do {
+ if max_iterations > 2 then
+ hPutStr stderr ("NOTE: Simplifier still going after " ++
+ show max_iterations ++
+ " iterations; bailing out.\n")
+ else 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}
+
+
+%************************************************************************
+%* *
+\subsection{PostSimplification}
+%* *
+%************************************************************************
+
+Several tasks are performed by the post-simplification pass
+
+1. Make the representation of NoRep literals explicit, and
+ float their bindings to the top level. We only do the floating
+ part for NoRep lits inside a lambda (else no gain). We need to
+ take care with let x = "foo" in e
+ that we don't end up with a silly binding
+ let x = y in e
+ with a floated "foo". What a bore.
+
+4. 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. It does eta
+ on the RHSs of bindings but not the RHSs of case alternatives and
+ let bodies)
+
+
+------------------- NOT DONE ANY MORE ------------------------
+[March 98] Indirections are now elimianted by the occurrence analyser
+1. Eliminate indirections. The point here is to transform
+ x_local = E
+ x_exported = x_local
+ ==>
+ x_exported = E
+
+[Dec 98] [Not now done because there is no penalty in the code
+ generator for using the former form]
+2. Convert
+ case x of {...; x' -> ...x'...}
+ ==>
+ case x of {...; _ -> ...x... }
+ See notes in SimplCase.lhs, near simplDefault for the reasoning here.
+--------------------------------------------------------------
+
+Special case
+~~~~~~~~~~~~
+
+NOT ENABLED AT THE MOMENT (because the floated Ids are global-ish
+things, and we need local Ids for non-floated stuff):
+
+ Don't float stuff out of a binder that's marked as a bottoming Id.
+ Reason: it doesn't do any good, and creates more CAFs that increase
+ the size of SRTs.
+
+eg.
+
+ f = error "string"
+
+is translated to
+
+ f' = unpackCString# "string"
+ f = error f'
+
+hence f' and f become CAFs. Instead, the special case for
+tidyTopBinding below makes sure this comes out as
+
+ f = let f' = unpackCString# "string" in error f'
+
+and we can safely ignore f as a CAF, since it can only ever be entered once.
+
+
+
+\begin{code}
+doPostSimplification :: UniqSupply -> [CoreBind] -> IO [CoreBind]
+doPostSimplification us binds_in
+ = do
+ beginPass "Post-simplification pass"
+ let binds_out = initPM us (postSimplTopBinds binds_in)
+ endPass "Post-simplification pass" opt_D_verbose_core2core binds_out
+
+postSimplTopBinds :: [CoreBind] -> PostM [CoreBind]
+postSimplTopBinds binds
+ = mapPM postSimplTopBind binds `thenPM` \ binds' ->
+ returnPM (bagToList (unionManyBags binds'))
+
+postSimplTopBind :: CoreBind -> PostM (Bag CoreBind)
+postSimplTopBind (NonRec bndr rhs)
+ | isBottomingId bndr -- Don't lift out floats for bottoming Ids
+ -- See notes above
+ = getFloatsPM (postSimplExpr rhs) `thenPM` \ (rhs', floats) ->
+ returnPM (unitBag (NonRec bndr (foldrBag Let rhs' floats)))
+
+postSimplTopBind bind
+ = getFloatsPM (postSimplBind bind) `thenPM` \ (bind', floats) ->
+ returnPM (floats `snocBag` bind')
+
+postSimplBind (NonRec bndr rhs)
+ = postSimplExpr rhs `thenPM` \ rhs' ->
+ returnPM (NonRec bndr rhs')
+
+postSimplBind (Rec pairs)
+ = mapPM postSimplExpr rhss `thenPM` \ rhss' ->
+ returnPM (Rec (bndrs `zip` rhss'))
+ where
+ (bndrs, rhss) = unzip pairs