2 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
4 \section[SCCfinal]{Modify and collect code generation for final STG program}
6 This is now a sort-of-normal STG-to-STG pass (WDP 94/06), run by stg2stg.
8 * Traverses the STG program collecting the cost centres. These are
9 required to declare the cost centres at the start of code
12 Note: because of cross-module unfolding, some of these cost centres
13 may be from other modules. But will still have to give them
14 "extern" declarations.
16 * Puts on CAF cost-centres if the user has asked for individual CAF
19 * Ditto for individual DICT cost-centres.
21 * Boxes top-level inherited functions passed as arguments.
23 * "Distributes" given cost-centres to all as-yet-unmarked RHSs.
26 module SCCfinal ( stgMassageForProfiling ) where
28 #include "HsVersions.h"
32 import CmdLineOpts ( opt_AutoSccsOnIndividualCafs )
33 import CostCentre -- lots of things
34 import Const ( Con(..) )
35 import Id ( Id, mkSysLocal )
36 import UniqSupply ( uniqFromSupply, splitUniqSupply, UniqSupply )
37 import Unique ( Unique )
38 import Util ( removeDups, assertPanic, trace )
41 infixr 9 `thenMM`, `thenMM_`
45 type CollectedCCs = ([CostCentre], -- locally defined ones
46 [CostCentre], -- ones needing "extern" decls
47 [CostCentreStack]) -- singleton stacks (for CAFs)
49 stgMassageForProfiling
50 :: FAST_STRING -> FAST_STRING -- module name, group name
51 -> UniqSupply -- unique supply
52 -> [StgBinding] -- input
53 -> (CollectedCCs, [StgBinding])
55 stgMassageForProfiling mod_name grp_name us stg_binds
57 ((local_ccs, extern_ccs, cc_stacks),
59 = initMM mod_name us (mapMM do_top_binding stg_binds)
61 (fixed_ccs, fixed_cc_stacks)
62 = if opt_AutoSccsOnIndividualCafs
63 then ([],[]) -- don't need "all CAFs" CC
64 -- (for Prelude, we use PreludeCC)
65 else ([all_cafs_cc], [all_cafs_ccs])
67 local_ccs_no_dups = fst (removeDups cmpCostCentre local_ccs)
68 extern_ccs_no_dups = fst (removeDups cmpCostCentre extern_ccs)
70 ((fixed_ccs ++ local_ccs_no_dups,
72 fixed_cc_stacks ++ cc_stacks), stg_binds2)
75 all_cafs_cc = mkAllCafsCC mod_name grp_name
76 all_cafs_ccs = mkSingletonCCS all_cafs_cc
79 do_top_binding :: StgBinding -> MassageM StgBinding
81 do_top_binding (StgNonRec b rhs)
82 = do_top_rhs b rhs `thenMM` \ rhs' ->
83 returnMM (StgNonRec b rhs')
85 do_top_binding (StgRec pairs)
86 = mapMM do_pair pairs `thenMM` \ pairs2 ->
87 returnMM (StgRec pairs2)
90 = do_top_rhs b rhs `thenMM` \ rhs2 ->
94 do_top_rhs :: Id -> StgRhs -> MassageM StgRhs
96 do_top_rhs binder (StgRhsClosure _ bi srt fv u [] (StgSCC cc (StgCon (DataCon con) args _)))
97 | not (isSccCountCostCentre cc)
98 -- Trivial _scc_ around nothing but static data
99 -- Eliminate _scc_ ... and turn into StgRhsCon
100 = returnMM (StgRhsCon dontCareCCS con args)
102 {- Can't do this one with cost-centre stacks: --SDM
103 do_top_rhs binder (StgRhsClosure no_cc bi srt fv u [] (StgSCC ty cc expr))
104 | (noCCSAttached no_cc || currentOrSubsumedCCS no_cc)
105 && not (isSccCountCostCentre cc)
106 -- Top level CAF without a cost centre attached
107 -- Attach and collect cc of trivial _scc_ in body
108 = collectCC cc `thenMM_`
109 set_prevailing_cc cc (do_expr expr) `thenMM` \ expr' ->
110 returnMM (StgRhsClosure cc bi srt fv u [] expr')
113 do_top_rhs binder (StgRhsClosure no_cc bi srt fv u [] body)
114 | noCCSAttached no_cc || currentOrSubsumedCCS no_cc
115 -- Top level CAF without a cost centre attached
116 -- Attach CAF cc (collect if individual CAF ccs)
117 = (if opt_AutoSccsOnIndividualCafs
118 then let cc = mkAutoCC binder mod_name grp_name IsCafCC
119 ccs = mkSingletonCCS cc
121 collectCC cc `thenMM_`
122 collectCCS ccs `thenMM_`
125 returnMM all_cafs_ccs) `thenMM` \ caf_ccs ->
126 set_prevailing_cc caf_ccs (do_expr body) `thenMM` \ body' ->
127 returnMM (StgRhsClosure caf_ccs bi srt fv u [] body')
129 do_top_rhs binder (StgRhsClosure cc bi srt fv u [] body)
130 -- Top level CAF with cost centre attached
131 -- Should this be a CAF cc ??? Does this ever occur ???
132 = pprPanic "SCCfinal: CAF with cc:" (ppr cc)
134 {- can't do this with cost-centre stacks: --SDM
135 do_top_rhs binder (StgRhsClosure _ bi srt fv u args (StgSCC cc expr))
136 | not (isSccCountCostCentre cc)
137 -- Top level function with trivial _scc_ in body
138 -- Attach and collect cc of trivial _scc_
139 = collectCC cc `thenMM_`
140 set_prevailing_cc cc (do_expr expr) `thenMM` \ expr' ->
141 returnMM (StgRhsClosure cc bi srt fv u args expr')
144 do_top_rhs binder (StgRhsClosure no_ccs bi srt fv u args body)
145 -- Top level function, probably subsumed
146 | noCCSAttached no_ccs
147 = set_prevailing_cc currentCCS (do_expr body) `thenMM` \ body' ->
148 returnMM (StgRhsClosure subsumedCCS bi srt fv u args body')
151 = pprPanic "SCCfinal: CAF with cc:" (ppr no_ccs)
153 do_top_rhs binder (StgRhsCon ccs con args)
154 -- Top-level (static) data is not counted in heap
155 -- profiles; nor do we set CCCS from it; so we
156 -- just slam in dontCareCostCentre
157 = returnMM (StgRhsCon dontCareCCS con args)
160 do_expr :: StgExpr -> MassageM StgExpr
162 do_expr (StgApp fn args)
163 = boxHigherOrderArgs (StgApp fn) args
165 do_expr (StgCon con args res_ty)
166 = boxHigherOrderArgs (\args -> StgCon con args res_ty) args
168 do_expr (StgSCC cc expr) -- Ha, we found a cost centre!
169 = collectCC cc `thenMM_`
170 set_prevailing_cc currentCCS (do_expr expr) `thenMM` \ expr' ->
171 returnMM (StgSCC cc expr')
173 do_expr (StgCase expr fv1 fv2 bndr srt alts)
174 = do_expr expr `thenMM` \ expr' ->
175 do_alts alts `thenMM` \ alts' ->
176 returnMM (StgCase expr' fv1 fv2 bndr srt alts')
178 do_alts (StgAlgAlts ty alts def)
179 = mapMM do_alt alts `thenMM` \ alts' ->
180 do_deflt def `thenMM` \ def' ->
181 returnMM (StgAlgAlts ty alts' def')
183 do_alt (id, bs, use_mask, e)
184 = do_expr e `thenMM` \ e' ->
185 returnMM (id, bs, use_mask, e')
187 do_alts (StgPrimAlts ty alts def)
188 = mapMM do_alt alts `thenMM` \ alts' ->
189 do_deflt def `thenMM` \ def' ->
190 returnMM (StgPrimAlts ty alts' def')
193 = do_expr e `thenMM` \ e' ->
196 do_deflt StgNoDefault = returnMM StgNoDefault
197 do_deflt (StgBindDefault e)
198 = do_expr e `thenMM` \ e' ->
199 returnMM (StgBindDefault e')
202 = do_binding b `thenMM` \ b' ->
203 do_expr e `thenMM` \ e' ->
204 returnMM (StgLet b' e')
206 do_expr (StgLetNoEscape lvs1 lvs2 rhs body)
207 = do_binding rhs `thenMM` \ rhs' ->
208 do_expr body `thenMM` \ body' ->
209 returnMM (StgLetNoEscape lvs1 lvs2 rhs' body')
212 do_binding :: StgBinding -> MassageM StgBinding
214 do_binding (StgNonRec b rhs)
215 = do_rhs rhs `thenMM` \ rhs' ->
216 returnMM (StgNonRec b rhs')
218 do_binding (StgRec pairs)
219 = mapMM do_pair pairs `thenMM` \ new_pairs ->
220 returnMM (StgRec new_pairs)
223 = do_rhs rhs `thenMM` \ rhs' ->
226 do_rhs :: StgRhs -> MassageM StgRhs
227 -- We play much the same game as we did in do_top_rhs above;
228 -- but we don't have to worry about cafs etc.
231 do_rhs (StgRhsClosure closure_cc bi srt fv u [] (StgSCC ty cc (StgCon (DataCon con) args _)))
232 | not (isSccCountCostCentre cc)
233 = collectCC cc `thenMM_`
234 returnMM (StgRhsCon cc con args)
238 do_rhs (StgRhsClosure _ bi srt fv u args (StgSCC ty cc expr))
239 | not (isSccCountCostCentre cc)
240 = collectCC cc `thenMM_`
241 set_prevailing_cc cc (do_expr expr) `thenMM` \ expr' ->
242 returnMM (StgRhsClosure cc bi srt fv u args expr')
245 do_rhs (StgRhsClosure cc bi srt fv u args body)
246 = set_prevailing_cc_maybe cc $ \ cc' ->
247 set_lambda_cc (do_expr body) `thenMM` \ body' ->
248 returnMM (StgRhsClosure cc' bi srt fv u args body')
250 do_rhs (StgRhsCon cc con args)
251 = set_prevailing_cc_maybe cc $ \ cc' ->
252 returnMM (StgRhsCon cc' con args)
254 -- ToDo: Box args and sort out any let bindings ???
255 -- Nope: maybe later? WDP 94/06
258 %************************************************************************
260 \subsection{Boxing higher-order args}
262 %************************************************************************
266 :: ([StgArg] -> StgExpr)
267 -- An application lacking its arguments and live-var info
268 -> [StgArg] -- arguments which we might box
271 boxHigherOrderArgs almost_expr args
272 = returnMM (almost_expr args)
274 {- No boxing for now ... should be moved to desugarer and preserved ...
276 boxHigherOrderArgs almost_expr args live_vars
277 = get_prevailing_cc `thenMM` \ cc ->
278 if (isCafCC cc || isDictCC cc) then
279 -- no boxing required inside CAF/DICT cc
280 -- since CAF/DICT functions are subsumed anyway
281 returnMM (almost_expr args live_vars)
283 mapAccumMM do_arg [] args `thenMM` \ (let_bindings, new_args) ->
284 returnMM (foldr (mk_stg_let cc) (almost_expr new_args live_vars) let_bindings)
287 do_arg bindings atom@(StgLitAtom _) = returnMM (bindings, atom)
289 do_arg bindings atom@(StgVarAtom old_var)
291 var_type = getIdUniType old_var
293 if toplevelishId old_var && isFunType (getTauType var_type)
295 -- make a trivial let-binding for the top-level function
296 getUniqueMM `thenMM` \ uniq ->
298 new_var = mkSysLocal uniq var_type
300 returnMM ( (new_var, old_var) : bindings, StgVarAtom new_var )
302 returnMM (bindings, atom)
305 mk_stg_let :: CostCentre -> (Id, Id) -> StgExpr -> StgExpr
307 mk_stg_let cc (new_var, old_var) body
309 rhs_body = StgApp (StgVarAtom old_var) [{-args-}]
310 rhs_closure = StgRhsClosure cc stgArgOcc NoSRT [{-fvs-}] ReEntrant [{-args-}] rhs_body
312 StgLet (StgNonRec new_var rhs_closure) body
314 bOGUS_LVs = emptyUniqSet -- easier to print than: panic "mk_stg_let: LVs"
318 %************************************************************************
320 \subsection{Boring monad stuff for this}
322 %************************************************************************
326 = FAST_STRING -- module name
327 -> CostCentreStack -- prevailing CostCentre
328 -- if none, subsumedCosts at top-level
329 -- useCurrentCostCentre at nested levels
332 -> (CollectedCCs, result)
334 -- the initUs function also returns the final UniqueSupply and CollectedCCs
336 initMM :: FAST_STRING -- module name, which we may consult
341 initMM mod_name init_us m = m mod_name noCCS init_us ([],[],[])
343 thenMM :: MassageM a -> (a -> MassageM b) -> MassageM b
344 thenMM_ :: MassageM a -> (MassageM b) -> MassageM b
346 thenMM expr cont mod scope_cc us ccs
347 = case splitUniqSupply us of { (s1, s2) ->
348 case (expr mod scope_cc s1 ccs) of { (ccs2, result) ->
349 cont result mod scope_cc s2 ccs2 }}
351 thenMM_ expr cont mod scope_cc us ccs
352 = case splitUniqSupply us of { (s1, s2) ->
353 case (expr mod scope_cc s1 ccs) of { (ccs2, _) ->
354 cont mod scope_cc s2 ccs2 }}
356 returnMM :: a -> MassageM a
357 returnMM result mod scope_cc us ccs = (ccs, result)
360 nopMM mod scope_cc us ccs = (ccs, ())
362 mapMM :: (a -> MassageM b) -> [a] -> MassageM [b]
364 mapMM f [] = returnMM []
366 = f m `thenMM` \ r ->
367 mapMM f ms `thenMM` \ rs ->
370 mapAccumMM :: (acc -> x -> MassageM (acc, y)) -> acc -> [x] -> MassageM (acc, [y])
372 mapAccumMM f b [] = returnMM (b, [])
373 mapAccumMM f b (m:ms)
374 = f b m `thenMM` \ (b2, r) ->
375 mapAccumMM f b2 ms `thenMM` \ (b3, rs) ->
378 getUniqueMM :: MassageM Unique
379 getUniqueMM mod scope_cc us ccs = (ccs, uniqFromSupply us)
382 I'm not sure about all this prevailing CC stuff --SDM
385 set_prevailing_cc :: CostCentreStack -> MassageM a -> MassageM a
386 set_prevailing_cc cc_to_set_to action mod scope_cc us ccs
387 -- set unconditionally
388 = action mod cc_to_set_to us ccs
390 set_prevailing_cc_maybe :: CostCentreStack -> (CostCentreStack -> MassageM a) -> MassageM a
391 set_prevailing_cc_maybe cc_to_try action mod scope_cc us ccs
392 -- set only if a real cost centre
395 = if noCCSAttached cc_to_try
396 then scope_cc -- carry on as before
397 else cc_to_try -- use new cost centre
399 action cc_to_use mod cc_to_use us ccs
401 set_lambda_cc :: MassageM a -> MassageM a
402 set_lambda_cc action mod scope_cc us ccs
403 -- used when moving inside a lambda;
404 -- if we were chugging along as "caf/dict" we change to "ccc"
406 cc_to_use = currentCCS
408 = if isCafCC scope_cc || isDictCC scope_cc
409 then useCurrentCostCentre
413 action mod cc_to_use us ccs
416 get_prevailing_cc :: MassageM CostCentreStack
417 get_prevailing_cc mod scope_cc us ccs = (ccs, scope_cc)
422 collectCC :: CostCentre -> MassageM ()
424 collectCC cc mod_name scope_cc us (local_ccs, extern_ccs, ccss)
425 = ASSERT(not (noCCAttached cc))
426 if (cc `ccFromThisModule` mod_name) then
427 ((cc : local_ccs, extern_ccs, ccss), ())
428 else -- must declare it "extern"
429 ((local_ccs, cc : extern_ccs, ccss), ())
431 collectCCS :: CostCentreStack -> MassageM ()
433 collectCCS ccs mod_name scope_cc us (local_ccs, extern_ccs, ccss)
434 = ASSERT(not (noCCSAttached ccs))
435 ((local_ccs, extern_ccs, ccs : ccss), ())