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+%
+% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
+%
+\section[SCCfinal]{Modify and collect code generation for final STG program}
+
+This is now a sort-of-normal STG-to-STG pass (WDP 94/06), run by stg2stg.
+
+* Traverses the STG program collecting the cost centres. These are
+  required to declare the cost centres at the start of code
+  generation.
+
+  Note: because of cross-module unfolding, some of these cost centres
+  may be from other modules.  But will still have to give them
+  "extern" declarations.
+
+* Puts on CAF cost-centres if the user has asked for individual CAF
+  cost-centres.
+
+* Ditto for individual DICT cost-centres.
+
+* Boxes top-level inherited functions passed as arguments.
+
+* "Distributes" given cost-centres to all as-yet-unmarked RHSs.
+
+\begin{code}
+module SCCfinal ( stgMassageForProfiling ) where
+
+#include "HsVersions.h"
+
+import StgSyn
+
+import Packages		( HomeModules )
+import StaticFlags	( opt_AutoSccsOnIndividualCafs )
+import CostCentre	-- lots of things
+import Id		( Id )
+import Module		( Module )
+import UniqSupply	( uniqFromSupply, splitUniqSupply, UniqSupply )
+import Unique           ( Unique )
+import VarSet
+import ListSetOps	( removeDups )
+import Outputable	
+
+infixr 9 `thenMM`, `thenMM_`
+\end{code}
+
+\begin{code}
+stgMassageForProfiling
+	:: HomeModules
+	-> Module			-- module name
+	-> UniqSupply		    	-- unique supply
+	-> [StgBinding]		    	-- input
+	-> (CollectedCCs, [StgBinding])
+
+stgMassageForProfiling pdeps mod_name us stg_binds
+  = let
+	((local_ccs, extern_ccs, cc_stacks),
+	 stg_binds2)
+	  = initMM mod_name us (do_top_bindings stg_binds)
+
+	(fixed_ccs, fixed_cc_stacks)
+	  = if opt_AutoSccsOnIndividualCafs
+	    then ([],[])  -- don't need "all CAFs" CC 
+			  -- (for Prelude, we use PreludeCC)
+	    else ([all_cafs_cc], [all_cafs_ccs])
+
+	local_ccs_no_dups  = fst (removeDups cmpCostCentre local_ccs)
+	extern_ccs_no_dups = fst (removeDups cmpCostCentre extern_ccs)
+    in
+    ((fixed_ccs ++ local_ccs_no_dups, 
+      extern_ccs_no_dups, 
+      fixed_cc_stacks ++ cc_stacks), stg_binds2)
+  where
+
+    all_cafs_cc  = mkAllCafsCC mod_name
+    all_cafs_ccs = mkSingletonCCS all_cafs_cc
+
+    ----------
+    do_top_bindings :: [StgBinding] -> MassageM [StgBinding]
+
+    do_top_bindings [] = returnMM []
+
+    do_top_bindings (StgNonRec b rhs : bs) 
+      = do_top_rhs b rhs 		`thenMM` \ rhs' ->
+	addTopLevelIshId b (
+	   do_top_bindings bs `thenMM` \bs' ->
+	   returnMM (StgNonRec b rhs' : bs')
+	)
+
+    do_top_bindings (StgRec pairs : bs)
+      = addTopLevelIshIds binders (
+	   mapMM do_pair pairs		`thenMM` \ pairs2 ->
+	   do_top_bindings bs `thenMM` \ bs' ->
+	   returnMM (StgRec pairs2 : bs')
+	)
+      where
+	binders = map fst pairs
+	do_pair (b, rhs) 
+	   = do_top_rhs b rhs	`thenMM` \ rhs2 ->
+	     returnMM (b, rhs2)
+
+    ----------
+    do_top_rhs :: Id -> StgRhs -> MassageM StgRhs
+
+    do_top_rhs binder (StgRhsClosure _ bi fv u srt [] (StgSCC cc (StgConApp con args)))
+      | not (isSccCountCostCentre cc) && not (isDllConApp pdeps con args)
+	-- Trivial _scc_ around nothing but static data
+	-- Eliminate _scc_ ... and turn into StgRhsCon
+
+	-- isDllConApp checks for LitLit args too
+      = returnMM (StgRhsCon dontCareCCS con args)
+
+{- Can't do this one with cost-centre stacks:  --SDM
+    do_top_rhs binder (StgRhsClosure no_cc bi fv u [] (StgSCC ty cc expr))
+      | (noCCSAttached no_cc || currentOrSubsumedCCS no_cc)
+        && not (isSccCountCostCentre cc)
+	-- Top level CAF without a cost centre attached
+	-- Attach and collect cc of trivial _scc_ in body
+      = collectCC cc					`thenMM_`
+	set_prevailing_cc cc (do_expr expr)		`thenMM`  \ expr' ->
+        returnMM (StgRhsClosure cc bi fv u [] expr')
+-}
+
+    do_top_rhs binder (StgRhsClosure no_cc bi fv u srt [] body)
+      | noCCSAttached no_cc || currentOrSubsumedCCS no_cc
+	-- Top level CAF without a cost centre attached
+	-- Attach CAF cc (collect if individual CAF ccs)
+      = (if opt_AutoSccsOnIndividualCafs 
+		then let cc = mkAutoCC binder mod_name CafCC
+			 ccs = mkSingletonCCS cc
+		     in
+		     collectCC  cc  `thenMM_`
+		     collectCCS ccs `thenMM_`
+		     returnMM ccs
+		else 
+		     returnMM all_cafs_ccs)		`thenMM`  \ caf_ccs ->
+	   set_prevailing_cc caf_ccs (do_expr body)	`thenMM`  \ body' ->
+           returnMM (StgRhsClosure caf_ccs bi fv u srt [] body')
+
+    do_top_rhs binder (StgRhsClosure cc bi fv u srt [] body)
+	-- Top level CAF with cost centre attached
+	-- Should this be a CAF cc ??? Does this ever occur ???
+      = pprPanic "SCCfinal: CAF with cc:" (ppr cc)
+
+    do_top_rhs binder (StgRhsClosure no_ccs bi fv u srt args body)
+	-- Top level function, probably subsumed
+      | noCCSAttached no_ccs
+      = set_lambda_cc (do_expr body)	`thenMM` \ body' ->
+	returnMM (StgRhsClosure subsumedCCS bi fv u srt args body')
+
+      | otherwise
+      = pprPanic "SCCfinal: CAF with cc:" (ppr no_ccs)
+
+    do_top_rhs binder (StgRhsCon ccs con args)
+	-- Top-level (static) data is not counted in heap
+	-- profiles; nor do we set CCCS from it; so we
+	-- just slam in dontCareCostCentre
+      = returnMM (StgRhsCon dontCareCCS con args)
+
+    ------
+    do_expr :: StgExpr -> MassageM StgExpr
+
+    do_expr (StgLit l) = returnMM (StgLit l)
+
+    do_expr (StgApp fn args)
+      = boxHigherOrderArgs (StgApp fn) args
+
+    do_expr (StgConApp con args)
+      = boxHigherOrderArgs (\args -> StgConApp con args) args
+
+    do_expr (StgOpApp con args res_ty)
+      = boxHigherOrderArgs (\args -> StgOpApp con args res_ty) args
+
+    do_expr (StgSCC cc expr)	-- Ha, we found a cost centre!
+      = collectCC cc		`thenMM_`
+	do_expr expr		`thenMM` \ expr' ->
+	returnMM (StgSCC cc expr')
+
+    do_expr (StgCase expr fv1 fv2 bndr srt alt_type alts)
+      = do_expr expr		`thenMM` \ expr' ->
+	mapMM do_alt alts 	`thenMM` \ alts' ->
+	returnMM (StgCase expr' fv1 fv2 bndr srt alt_type alts')
+      where
+	do_alt (id, bs, use_mask, e)
+	  = do_expr e `thenMM` \ e' ->
+	    returnMM (id, bs, use_mask, e')
+
+    do_expr (StgLet b e)
+	= do_let b e `thenMM` \ (b,e) ->
+	  returnMM (StgLet b e)
+
+    do_expr (StgLetNoEscape lvs1 lvs2 b e)
+	= do_let b e `thenMM` \ (b,e) ->
+	  returnMM (StgLetNoEscape lvs1 lvs2 b e)
+
+#ifdef DEBUG
+    do_expr other = pprPanic "SCCfinal.do_expr" (ppr other)
+#endif
+
+    ----------------------------------
+
+    do_let (StgNonRec b rhs) e
+      = do_rhs rhs		 	`thenMM` \ rhs' ->
+	addTopLevelIshId b (
+	  do_expr e		  	`thenMM` \ e' ->
+	  returnMM (StgNonRec b rhs',e')
+        )
+
+    do_let (StgRec pairs) e
+      = addTopLevelIshIds binders (
+	   mapMM do_pair pairs	 	`thenMM` \ pairs' ->
+	   do_expr e		  	`thenMM` \ e' ->
+	   returnMM (StgRec pairs', e')
+	)
+      where
+	binders = map fst pairs
+	do_pair (b, rhs) 
+	   = do_rhs rhs			`thenMM` \ rhs2 ->
+	     returnMM (b, rhs2)
+
+    ----------------------------------
+    do_rhs :: StgRhs -> MassageM StgRhs
+	-- We play much the same game as we did in do_top_rhs above;
+	-- but we don't have to worry about cafs etc.
+
+{-
+    do_rhs (StgRhsClosure closure_cc bi fv u [] (StgSCC ty cc (StgCon (DataCon con) args _)))
+      | not (isSccCountCostCentre cc)
+      = collectCC cc `thenMM_`
+	returnMM (StgRhsCon cc con args)
+-}
+
+    do_rhs (StgRhsClosure _ bi fv u srt args expr)
+      = slurpSCCs currentCCS expr	`thenMM` \ (expr', ccs) ->
+	do_expr expr'			`thenMM` \ expr'' ->
+	returnMM (StgRhsClosure ccs bi fv u srt args expr'')
+      where
+	slurpSCCs ccs (StgSCC cc e) 
+	     = collectCC cc 			`thenMM_`
+	       slurpSCCs (cc `pushCCOnCCS` ccs) e
+	slurpSCCs ccs e 
+	     = returnMM (e, ccs)
+
+    do_rhs (StgRhsCon cc con args)
+      = returnMM (StgRhsCon currentCCS con args)
+\end{code}
+
+%************************************************************************
+%*									*
+\subsection{Boxing higher-order args}
+%*									*
+%************************************************************************
+
+Boxing is *turned off* at the moment, until we can figure out how to
+do it properly in general.
+
+\begin{code}
+boxHigherOrderArgs
+    :: ([StgArg] -> StgExpr)
+			-- An application lacking its arguments
+    -> [StgArg]		-- arguments which we might box
+    -> MassageM StgExpr
+
+#ifndef PROF_DO_BOXING
+boxHigherOrderArgs almost_expr args
+   = returnMM (almost_expr args)
+#else
+boxHigherOrderArgs almost_expr args
+  = getTopLevelIshIds		`thenMM` \ ids ->
+    mapAccumMM (do_arg ids) [] args	`thenMM` \ (let_bindings, new_args) ->
+    returnMM (foldr (mk_stg_let currentCCS) (almost_expr new_args) let_bindings)
+  where
+    ---------------
+
+    do_arg ids bindings arg@(StgVarArg old_var)
+	|  (not (isLocalVar old_var) || elemVarSet old_var ids)
+	&& isFunTy (dropForAlls var_type)
+      =     -- make a trivial let-binding for the top-level function
+	getUniqueMM		`thenMM` \ uniq ->
+	let
+	    new_var = mkSysLocal FSLIT("sf") uniq var_type
+	in
+	returnMM ( (new_var, old_var) : bindings, StgVarArg new_var )
+      where
+	var_type = idType old_var
+
+    do_arg ids bindings arg = returnMM (bindings, arg)
+
+    ---------------
+    mk_stg_let :: CostCentreStack -> (Id, Id) -> StgExpr -> StgExpr
+
+    mk_stg_let cc (new_var, old_var) body
+      = let
+	    rhs_body    = StgApp old_var [{-args-}]
+	    rhs_closure = StgRhsClosure cc stgArgOcc [{-fvs-}] ReEntrant NoSRT{-eeek!!!-} [{-args-}] rhs_body
+        in
+	StgLet (StgNonRec new_var rhs_closure) body
+      where
+	bOGUS_LVs = emptyUniqSet -- easier to print than: panic "mk_stg_let: LVs"
+#endif
+\end{code}
+
+%************************************************************************
+%*									*
+\subsection{Boring monad stuff for this}
+%*									*
+%************************************************************************
+
+\begin{code}
+type MassageM result
+  =  Module		-- module name
+  -> CostCentreStack	-- prevailing CostCentre
+			-- if none, subsumedCosts at top-level
+			-- currentCostCentre at nested levels
+  -> UniqSupply
+  -> VarSet		-- toplevel-ish Ids for boxing
+  -> CollectedCCs
+  -> (CollectedCCs, result)
+
+-- the initMM function also returns the final CollectedCCs
+
+initMM :: Module	-- module name, which we may consult
+       -> UniqSupply
+       -> MassageM a
+       -> (CollectedCCs, a)
+
+initMM mod_name init_us m = m mod_name noCCS init_us emptyVarSet ([],[],[])
+
+thenMM  :: MassageM a -> (a -> MassageM b) -> MassageM b
+thenMM_ :: MassageM a -> (MassageM b) -> MassageM b
+
+thenMM expr cont mod scope_cc us ids ccs
+  = case splitUniqSupply us	of { (s1, s2) ->
+    case (expr mod scope_cc s1 ids ccs) of { (ccs2, result) ->
+    cont result mod scope_cc s2 ids ccs2 }}
+
+thenMM_ expr cont mod scope_cc us ids ccs
+  = case splitUniqSupply us	of { (s1, s2) ->
+    case (expr mod scope_cc s1 ids ccs)	of { (ccs2, _) ->
+    cont mod scope_cc s2 ids ccs2 }}
+
+returnMM :: a -> MassageM a
+returnMM result mod scope_cc us ids ccs = (ccs, result)
+
+nopMM :: MassageM ()
+nopMM mod scope_cc us ids ccs = (ccs, ())
+
+mapMM :: (a -> MassageM b) -> [a] -> MassageM [b]
+mapMM f [] = returnMM []
+mapMM f (m:ms)
+  = f m		`thenMM` \ r  ->
+    mapMM f ms	`thenMM` \ rs ->
+    returnMM (r:rs)
+
+mapAccumMM :: (acc -> x -> MassageM (acc, y)) -> acc -> [x] -> MassageM (acc, [y])
+mapAccumMM f b [] = returnMM (b, [])
+mapAccumMM f b (m:ms)
+  = f b m		`thenMM` \ (b2, r)  ->
+    mapAccumMM f b2 ms	`thenMM` \ (b3, rs) ->
+    returnMM (b3, r:rs)
+
+getUniqueMM :: MassageM Unique
+getUniqueMM mod scope_cc us ids ccs = (ccs, uniqFromSupply us)
+
+addTopLevelIshId :: Id -> MassageM a -> MassageM a
+addTopLevelIshId id scope mod scope_cc us ids ccs
+  | isCurrentCCS scope_cc = scope mod scope_cc us ids ccs
+  | otherwise             = scope mod scope_cc us (extendVarSet ids id) ccs
+
+addTopLevelIshIds :: [Id] -> MassageM a -> MassageM a
+addTopLevelIshIds [] cont = cont
+addTopLevelIshIds (id:ids) cont 
+  = addTopLevelIshId id (addTopLevelIshIds ids cont)
+
+getTopLevelIshIds :: MassageM VarSet
+getTopLevelIshIds mod scope_cc us ids ccs = (ccs, ids)
+\end{code}
+
+The prevailing CCS is used to tell whether we're in a top-levelish
+position, where top-levelish is defined as "not inside a lambda".
+Prevailing CCs used to be used for something much more complicated,
+I'm sure --SDM
+
+\begin{code}
+set_lambda_cc :: MassageM a -> MassageM a
+set_lambda_cc action mod scope_cc us ids ccs
+  = action mod currentCCS us ids ccs
+
+set_prevailing_cc :: CostCentreStack -> MassageM a -> MassageM a
+set_prevailing_cc cc_to_set_to action mod scope_cc us ids ccs
+  = action mod cc_to_set_to us ids ccs
+
+get_prevailing_cc :: MassageM CostCentreStack
+get_prevailing_cc mod scope_cc us ids ccs = (ccs, scope_cc)
+\end{code}
+
+\begin{code}
+collectCC :: CostCentre -> MassageM ()
+
+collectCC cc mod_name scope_cc us ids (local_ccs, extern_ccs, ccss)
+  = ASSERT(not (noCCAttached cc))
+    if (cc `ccFromThisModule` mod_name) then
+	((cc : local_ccs, extern_ccs, ccss), ())
+    else -- must declare it "extern"
+	((local_ccs, cc : extern_ccs, ccss), ())
+
+collectCCS :: CostCentreStack -> MassageM ()
+
+collectCCS ccs mod_name scope_cc us ids (local_ccs, extern_ccs, ccss)
+  = ASSERT(not (noCCSAttached ccs))
+    ((local_ccs, extern_ccs, ccs : ccss), ())
+\end{code}