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 Module ( Module )
37 import UniqSupply ( uniqFromSupply, splitUniqSupply, UniqSupply )
38 import Unique ( Unique )
39 import Util ( removeDups )
42 infixr 9 `thenMM`, `thenMM_`
46 type CollectedCCs = ([CostCentre], -- locally defined ones
47 [CostCentre], -- ones needing "extern" decls
48 [CostCentreStack]) -- singleton stacks (for CAFs)
50 stgMassageForProfiling
51 :: Module -> FAST_STRING -- module name, group name
52 -> UniqSupply -- unique supply
53 -> [StgBinding] -- input
54 -> (CollectedCCs, [StgBinding])
56 stgMassageForProfiling mod_name grp_name us stg_binds
58 ((local_ccs, extern_ccs, cc_stacks),
60 = initMM mod_name us (mapMM do_top_binding stg_binds)
62 (fixed_ccs, fixed_cc_stacks)
63 = if opt_AutoSccsOnIndividualCafs
64 then ([],[]) -- don't need "all CAFs" CC
65 -- (for Prelude, we use PreludeCC)
66 else ([all_cafs_cc], [all_cafs_ccs])
68 local_ccs_no_dups = fst (removeDups cmpCostCentre local_ccs)
69 extern_ccs_no_dups = fst (removeDups cmpCostCentre extern_ccs)
71 ((fixed_ccs ++ local_ccs_no_dups,
73 fixed_cc_stacks ++ cc_stacks), stg_binds2)
76 all_cafs_cc = mkAllCafsCC mod_name grp_name
77 all_cafs_ccs = mkSingletonCCS all_cafs_cc
80 do_top_binding :: StgBinding -> MassageM StgBinding
82 do_top_binding (StgNonRec b rhs)
83 = do_top_rhs b rhs `thenMM` \ rhs' ->
84 returnMM (StgNonRec b rhs')
86 do_top_binding (StgRec pairs)
87 = mapMM do_pair pairs `thenMM` \ pairs2 ->
88 returnMM (StgRec pairs2)
91 = do_top_rhs b rhs `thenMM` \ rhs2 ->
95 do_top_rhs :: Id -> StgRhs -> MassageM StgRhs
97 do_top_rhs binder (StgRhsClosure _ bi srt fv u [] (StgSCC cc (StgCon (DataCon con) args _)))
98 | not (isSccCountCostCentre cc)
99 -- Trivial _scc_ around nothing but static data
100 -- Eliminate _scc_ ... and turn into StgRhsCon
101 = returnMM (StgRhsCon dontCareCCS con args)
103 {- Can't do this one with cost-centre stacks: --SDM
104 do_top_rhs binder (StgRhsClosure no_cc bi srt fv u [] (StgSCC ty cc expr))
105 | (noCCSAttached no_cc || currentOrSubsumedCCS no_cc)
106 && not (isSccCountCostCentre cc)
107 -- Top level CAF without a cost centre attached
108 -- Attach and collect cc of trivial _scc_ in body
109 = collectCC cc `thenMM_`
110 set_prevailing_cc cc (do_expr expr) `thenMM` \ expr' ->
111 returnMM (StgRhsClosure cc bi srt fv u [] expr')
114 do_top_rhs binder (StgRhsClosure no_cc bi srt fv u [] body)
115 | noCCSAttached no_cc || currentOrSubsumedCCS no_cc
116 -- Top level CAF without a cost centre attached
117 -- Attach CAF cc (collect if individual CAF ccs)
118 = (if opt_AutoSccsOnIndividualCafs
119 then let cc = mkAutoCC binder mod_name grp_name CafCC
120 ccs = mkSingletonCCS cc
122 collectCC cc `thenMM_`
123 collectCCS ccs `thenMM_`
126 returnMM all_cafs_ccs) `thenMM` \ caf_ccs ->
127 set_prevailing_cc caf_ccs (do_expr body) `thenMM` \ body' ->
128 returnMM (StgRhsClosure caf_ccs bi srt fv u [] body')
130 do_top_rhs binder (StgRhsClosure cc bi srt fv u [] body)
131 -- Top level CAF with cost centre attached
132 -- Should this be a CAF cc ??? Does this ever occur ???
133 = pprPanic "SCCfinal: CAF with cc:" (ppr cc)
135 {- can't do this with cost-centre stacks: --SDM
136 do_top_rhs binder (StgRhsClosure _ bi srt fv u args (StgSCC cc expr))
137 | not (isSccCountCostCentre cc)
138 -- Top level function with trivial _scc_ in body
139 -- Attach and collect cc of trivial _scc_
140 = collectCC cc `thenMM_`
141 set_prevailing_cc cc (do_expr expr) `thenMM` \ expr' ->
142 returnMM (StgRhsClosure cc bi srt fv u args expr')
145 do_top_rhs binder (StgRhsClosure no_ccs bi srt fv u args body)
146 -- Top level function, probably subsumed
147 | noCCSAttached no_ccs
148 = set_prevailing_cc currentCCS (do_expr body) `thenMM` \ body' ->
149 returnMM (StgRhsClosure subsumedCCS bi srt fv u args body')
152 = pprPanic "SCCfinal: CAF with cc:" (ppr no_ccs)
154 do_top_rhs binder (StgRhsCon ccs con args)
155 -- Top-level (static) data is not counted in heap
156 -- profiles; nor do we set CCCS from it; so we
157 -- just slam in dontCareCostCentre
158 = returnMM (StgRhsCon dontCareCCS con args)
161 do_expr :: StgExpr -> MassageM StgExpr
163 do_expr (StgApp fn args)
164 = boxHigherOrderArgs (StgApp fn) args
166 do_expr (StgCon con args res_ty)
167 = boxHigherOrderArgs (\args -> StgCon con args res_ty) args
169 do_expr (StgSCC cc expr) -- Ha, we found a cost centre!
170 = collectCC cc `thenMM_`
171 set_prevailing_cc currentCCS (do_expr expr) `thenMM` \ expr' ->
172 returnMM (StgSCC cc expr')
174 do_expr (StgCase expr fv1 fv2 bndr srt alts)
175 = do_expr expr `thenMM` \ expr' ->
176 do_alts alts `thenMM` \ alts' ->
177 returnMM (StgCase expr' fv1 fv2 bndr srt alts')
179 do_alts (StgAlgAlts ty alts def)
180 = mapMM do_alt alts `thenMM` \ alts' ->
181 do_deflt def `thenMM` \ def' ->
182 returnMM (StgAlgAlts ty alts' def')
184 do_alt (id, bs, use_mask, e)
185 = do_expr e `thenMM` \ e' ->
186 returnMM (id, bs, use_mask, e')
188 do_alts (StgPrimAlts ty alts def)
189 = mapMM do_alt alts `thenMM` \ alts' ->
190 do_deflt def `thenMM` \ def' ->
191 returnMM (StgPrimAlts ty alts' def')
194 = do_expr e `thenMM` \ e' ->
197 do_deflt StgNoDefault = returnMM StgNoDefault
198 do_deflt (StgBindDefault e)
199 = do_expr e `thenMM` \ e' ->
200 returnMM (StgBindDefault e')
203 = do_binding b `thenMM` \ b' ->
204 do_expr e `thenMM` \ e' ->
205 returnMM (StgLet b' e')
207 do_expr (StgLetNoEscape lvs1 lvs2 rhs body)
208 = do_binding rhs `thenMM` \ rhs' ->
209 do_expr body `thenMM` \ body' ->
210 returnMM (StgLetNoEscape lvs1 lvs2 rhs' body')
213 do_binding :: StgBinding -> MassageM StgBinding
215 do_binding (StgNonRec b rhs)
216 = do_rhs rhs `thenMM` \ rhs' ->
217 returnMM (StgNonRec b rhs')
219 do_binding (StgRec pairs)
220 = mapMM do_pair pairs `thenMM` \ new_pairs ->
221 returnMM (StgRec new_pairs)
224 = do_rhs rhs `thenMM` \ rhs' ->
227 do_rhs :: StgRhs -> MassageM StgRhs
228 -- We play much the same game as we did in do_top_rhs above;
229 -- but we don't have to worry about cafs etc.
232 do_rhs (StgRhsClosure closure_cc bi srt fv u [] (StgSCC ty cc (StgCon (DataCon con) args _)))
233 | not (isSccCountCostCentre cc)
234 = collectCC cc `thenMM_`
235 returnMM (StgRhsCon cc con args)
239 do_rhs (StgRhsClosure _ bi srt fv u args (StgSCC ty cc expr))
240 | not (isSccCountCostCentre cc)
241 = collectCC cc `thenMM_`
242 set_prevailing_cc cc (do_expr expr) `thenMM` \ expr' ->
243 returnMM (StgRhsClosure cc bi srt fv u args expr')
246 do_rhs (StgRhsClosure cc bi srt fv u args body)
247 = set_prevailing_cc_maybe cc $ \ cc' ->
248 set_lambda_cc (do_expr body) `thenMM` \ body' ->
249 returnMM (StgRhsClosure cc' bi srt fv u args body')
251 do_rhs (StgRhsCon cc con args)
252 = set_prevailing_cc_maybe cc $ \ cc' ->
253 returnMM (StgRhsCon cc' con args)
255 -- ToDo: Box args and sort out any let bindings ???
256 -- Nope: maybe later? WDP 94/06
259 %************************************************************************
261 \subsection{Boxing higher-order args}
263 %************************************************************************
267 :: ([StgArg] -> StgExpr)
268 -- An application lacking its arguments and live-var info
269 -> [StgArg] -- arguments which we might box
272 boxHigherOrderArgs almost_expr args
273 = returnMM (almost_expr args)
275 {- No boxing for now ... should be moved to desugarer and preserved ...
277 boxHigherOrderArgs almost_expr args live_vars
278 = get_prevailing_cc `thenMM` \ cc ->
279 if (isCafCC cc || isDictCC cc) then
280 -- no boxing required inside CAF/DICT cc
281 -- since CAF/DICT functions are subsumed anyway
282 returnMM (almost_expr args live_vars)
284 mapAccumMM do_arg [] args `thenMM` \ (let_bindings, new_args) ->
285 returnMM (foldr (mk_stg_let cc) (almost_expr new_args live_vars) let_bindings)
288 do_arg bindings atom@(StgLitAtom _) = returnMM (bindings, atom)
290 do_arg bindings atom@(StgVarAtom old_var)
292 var_type = getIdUniType old_var
294 if toplevelishId old_var && isFunType (getTauType var_type)
296 -- make a trivial let-binding for the top-level function
297 getUniqueMM `thenMM` \ uniq ->
299 new_var = mkSysLocal SLIT("sf") uniq var_type
301 returnMM ( (new_var, old_var) : bindings, StgVarAtom new_var )
303 returnMM (bindings, atom)
306 mk_stg_let :: CostCentre -> (Id, Id) -> StgExpr -> StgExpr
308 mk_stg_let cc (new_var, old_var) body
310 rhs_body = StgApp (StgVarAtom old_var) [{-args-}]
311 rhs_closure = StgRhsClosure cc stgArgOcc NoSRT [{-fvs-}] ReEntrant [{-args-}] rhs_body
313 StgLet (StgNonRec new_var rhs_closure) body
315 bOGUS_LVs = emptyUniqSet -- easier to print than: panic "mk_stg_let: LVs"
319 %************************************************************************
321 \subsection{Boring monad stuff for this}
323 %************************************************************************
327 = Module -- module name
328 -> CostCentreStack -- prevailing CostCentre
329 -- if none, subsumedCosts at top-level
330 -- useCurrentCostCentre at nested levels
333 -> (CollectedCCs, result)
335 -- the initUs function also returns the final UniqueSupply and CollectedCCs
337 initMM :: Module -- module name, which we may consult
342 initMM mod_name init_us m = m mod_name noCCS init_us ([],[],[])
344 thenMM :: MassageM a -> (a -> MassageM b) -> MassageM b
345 thenMM_ :: MassageM a -> (MassageM b) -> MassageM b
347 thenMM expr cont mod scope_cc us ccs
348 = case splitUniqSupply us of { (s1, s2) ->
349 case (expr mod scope_cc s1 ccs) of { (ccs2, result) ->
350 cont result mod scope_cc s2 ccs2 }}
352 thenMM_ expr cont mod scope_cc us ccs
353 = case splitUniqSupply us of { (s1, s2) ->
354 case (expr mod scope_cc s1 ccs) of { (ccs2, _) ->
355 cont mod scope_cc s2 ccs2 }}
357 returnMM :: a -> MassageM a
358 returnMM result mod scope_cc us ccs = (ccs, result)
361 nopMM mod scope_cc us ccs = (ccs, ())
363 mapMM :: (a -> MassageM b) -> [a] -> MassageM [b]
365 mapMM f [] = returnMM []
367 = f m `thenMM` \ r ->
368 mapMM f ms `thenMM` \ rs ->
371 mapAccumMM :: (acc -> x -> MassageM (acc, y)) -> acc -> [x] -> MassageM (acc, [y])
373 mapAccumMM f b [] = returnMM (b, [])
374 mapAccumMM f b (m:ms)
375 = f b m `thenMM` \ (b2, r) ->
376 mapAccumMM f b2 ms `thenMM` \ (b3, rs) ->
379 getUniqueMM :: MassageM Unique
380 getUniqueMM mod scope_cc us ccs = (ccs, uniqFromSupply us)
383 I'm not sure about all this prevailing CC stuff --SDM
386 set_prevailing_cc :: CostCentreStack -> MassageM a -> MassageM a
387 set_prevailing_cc cc_to_set_to action mod scope_cc us ccs
388 -- set unconditionally
389 = action mod cc_to_set_to us ccs
391 set_prevailing_cc_maybe :: CostCentreStack -> (CostCentreStack -> MassageM a) -> MassageM a
392 set_prevailing_cc_maybe cc_to_try action mod scope_cc us ccs
393 -- set only if a real cost centre
396 = if noCCSAttached cc_to_try
397 then scope_cc -- carry on as before
398 else cc_to_try -- use new cost centre
400 action cc_to_use mod cc_to_use us ccs
402 set_lambda_cc :: MassageM a -> MassageM a
403 set_lambda_cc action mod scope_cc us ccs
404 -- used when moving inside a lambda;
405 -- if we were chugging along as "caf/dict" we change to "ccc"
407 cc_to_use = currentCCS
409 = if isCafCC scope_cc || isDictCC scope_cc
410 then useCurrentCostCentre
414 action mod cc_to_use us ccs
417 get_prevailing_cc :: MassageM CostCentreStack
418 get_prevailing_cc mod scope_cc us ccs = (ccs, scope_cc)
423 collectCC :: CostCentre -> MassageM ()
425 collectCC cc mod_name scope_cc us (local_ccs, extern_ccs, ccss)
426 = ASSERT(not (noCCAttached cc))
427 if (cc `ccFromThisModule` mod_name) then
428 ((cc : local_ccs, extern_ccs, ccss), ())
429 else -- must declare it "extern"
430 ((local_ccs, cc : extern_ccs, ccss), ())
432 collectCCS :: CostCentreStack -> MassageM ()
434 collectCCS ccs mod_name scope_cc us (local_ccs, extern_ccs, ccss)
435 = ASSERT(not (noCCSAttached ccs))
436 ((local_ccs, extern_ccs, ccs : ccss), ())