2 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
4 \section[CostCentre]{The @CostCentre@ data type}
7 {-# OPTIONS -fno-warn-incomplete-patterns #-}
8 -- The above warning supression flag is a temporary kludge.
9 -- While working on this module you are encouraged to remove it and fix
10 -- any warnings in the module. See
11 -- http://hackage.haskell.org/trac/ghc/wiki/Commentary/CodingStyle#Warnings
15 CostCentre(..), CcName, IsDupdCC(..), IsCafCC(..),
16 -- All abstract except to friend: ParseIface.y
20 noCCS, subsumedCCS, currentCCS, overheadCCS, dontCareCCS,
21 noCostCentre, noCCAttached,
22 noCCSAttached, isCurrentCCS, isSubsumedCCS, currentOrSubsumedCCS,
23 isDerivedFromCurrentCCS, maybeSingletonCCS,
24 decomposeCCS, pushCCisNop,
26 mkUserCC, mkAutoCC, mkAllCafsCC,
27 mkSingletonCCS, dupifyCC, pushCCOnCCS,
36 cmpCostCentre -- used for removing dups in a list
41 import Module ( Module )
46 import Util ( thenCmp )
49 A Cost Centre Stack is something that can be attached to a closure.
52 - the current cost centre stack (CCCS)
53 - a pre-defined cost centre stack (there are several
54 pre-defined CCSs, see below).
60 | CurrentCCS -- Pinned on a let(rec)-bound
61 -- thunk/function/constructor, this says that the
62 -- cost centre to be attached to the object, when it
63 -- is allocated, is whatever is in the
64 -- current-cost-centre-stack register.
66 | SubsumedCCS -- Cost centre stack for top-level subsumed functions
67 -- (CAFs get an AllCafsCC).
68 -- Its execution costs get subsumed into the caller.
69 -- This guy is *only* ever pinned on static closures,
70 -- and is *never* the cost centre for an SCC construct.
72 | OverheadCCS -- We charge costs due to the profiling-system
73 -- doing its work to "overhead".
75 -- Objects whose CCS is "Overhead"
76 -- have their *allocation* charged to "overhead",
77 -- but have the current CCS put into the object
80 -- For example, if we transform "f g" to "let
81 -- g' = g in f g'" (so that something about
82 -- profiling works better...), then we charge
83 -- the *allocation* of g' to OverheadCCS, but
84 -- we put the cost-centre of the call to f
85 -- (i.e., current CCS) into the g' object. When
86 -- g' is entered, the CCS of the call
89 | DontCareCCS -- We need a CCS to stick in static closures
90 -- (for data), but we *don't* expect them to
91 -- accumulate any costs. But we still need
92 -- the placeholder. This CCS is it.
94 | PushCC CostCentre CostCentreStack
95 -- These are used during code generation as the CCSs
96 -- attached to closures. A PushCC never appears as
97 -- the argument to an _scc_.
99 -- The tail (2nd argument) is either NoCCS, indicating
100 -- a staticly allocated CCS, or CurrentCCS indicating
101 -- a dynamically created CCS. We only support
102 -- statically allocated *singleton* CCSs at the
103 -- moment, for the purposes of initialising the CCS
106 deriving (Eq, Ord) -- needed for Ord on CLabel
109 A Cost Centre is the argument of an _scc_ expression.
113 = NoCostCentre -- Having this constructor avoids having
114 -- to use "Maybe CostCentre" all the time.
117 cc_name :: CcName, -- Name of the cost centre itself
118 cc_mod :: Module, -- Name of module defining this CC.
119 cc_is_dupd :: IsDupdCC, -- see below
120 cc_is_caf :: IsCafCC -- see below
124 cc_mod :: Module -- Name of module defining this CC.
127 type CcName = FastString
130 = OriginalCC -- This says how the CC is *used*. Saying that
131 | DupdCC -- it is DupdCC doesn't make it a different
132 -- CC, just that it a sub-expression which has
133 -- been moved ("dupd") into a different scope.
135 -- The point about a dupd SCC is that we don't
136 -- count entries to it, because it's not the
139 -- In the papers, it's called "SCCsub",
140 -- i.e. SCCsub CC == SCC DupdCC,
141 -- but we are trying to avoid confusion between
142 -- "subd" and "subsumed". So we call the former
145 data IsCafCC = CafCC | NotCafCC
147 -- synonym for triple which describes the cost centre info in the generated
148 -- code for a module.
150 = ( [CostCentre] -- local cost-centres that need to be decl'd
151 , [CostCentre] -- "extern" cost-centres
152 , [CostCentreStack] -- pre-defined "singleton" cost centre stacks
156 WILL: Would there be any merit to recording ``I am now using a
157 cost-centre from another module''? I don't know if this would help a
158 user; it might be interesting to us to know how much computation is
159 being moved across module boundaries.
161 SIMON: Maybe later...
164 noCCS, subsumedCCS, currentCCS, overheadCCS, dontCareCCS :: CostCentreStack
167 subsumedCCS = SubsumedCCS
168 currentCCS = CurrentCCS
169 overheadCCS = OverheadCCS
170 dontCareCCS = DontCareCCS
172 noCostCentre :: CostCentre
173 noCostCentre = NoCostCentre
176 Predicates on Cost-Centre Stacks
179 noCCSAttached :: CostCentreStack -> Bool
180 noCCSAttached NoCCS = True
181 noCCSAttached _ = False
183 noCCAttached :: CostCentre -> Bool
184 noCCAttached NoCostCentre = True
185 noCCAttached _ = False
187 isCurrentCCS :: CostCentreStack -> Bool
188 isCurrentCCS CurrentCCS = True
189 isCurrentCCS _ = False
191 isSubsumedCCS :: CostCentreStack -> Bool
192 isSubsumedCCS SubsumedCCS = True
193 isSubsumedCCS _ = False
195 isCafCCS :: CostCentreStack -> Bool
196 isCafCCS (PushCC cc NoCCS) = isCafCC cc
199 isDerivedFromCurrentCCS :: CostCentreStack -> Bool
200 isDerivedFromCurrentCCS CurrentCCS = True
201 isDerivedFromCurrentCCS (PushCC _ ccs) = isDerivedFromCurrentCCS ccs
202 isDerivedFromCurrentCCS _ = False
204 currentOrSubsumedCCS :: CostCentreStack -> Bool
205 currentOrSubsumedCCS SubsumedCCS = True
206 currentOrSubsumedCCS CurrentCCS = True
207 currentOrSubsumedCCS _ = False
209 maybeSingletonCCS :: CostCentreStack -> Maybe CostCentre
210 maybeSingletonCCS (PushCC cc NoCCS) = Just cc
211 maybeSingletonCCS _ = Nothing
213 pushCCisNop :: CostCentre -> CostCentreStack -> Bool
214 -- (pushCCisNop cc ccs) = True => pushing cc on ccs is a no-op
215 -- It's safe to return False, but the optimiser can remove
216 -- redundant pushes if this function returns True.
217 pushCCisNop cc (PushCC cc' _) = cc == cc'
218 pushCCisNop _ _ = False
221 Building cost centres
224 mkUserCC :: FastString -> Module -> CostCentre
226 = NormalCC { cc_name = cc_name, cc_mod = mod,
227 cc_is_dupd = OriginalCC, cc_is_caf = NotCafCC {-might be changed-}
230 mkAutoCC :: Id -> Module -> IsCafCC -> CostCentre
231 mkAutoCC id mod is_caf
232 = NormalCC { cc_name = str, cc_mod = mod,
233 cc_is_dupd = OriginalCC, cc_is_caf = is_caf
237 -- beware: only external names are guaranteed to have unique
238 -- Occnames. If the name is not external, we must append its
240 -- See bug #249, tests prof001, prof002, also #2411
241 str | isExternalName name = occNameFS (getOccName id)
242 | otherwise = mkFastString $ showSDoc $
243 ftext (occNameFS (getOccName id))
244 <> char '_' <> pprUnique (getUnique name)
245 mkAllCafsCC :: Module -> CostCentre
246 mkAllCafsCC m = AllCafsCC { cc_mod = m }
250 mkSingletonCCS :: CostCentre -> CostCentreStack
251 mkSingletonCCS cc = pushCCOnCCS cc NoCCS
253 pushCCOnCCS :: CostCentre -> CostCentreStack -> CostCentreStack
256 dupifyCC :: CostCentre -> CostCentre
257 dupifyCC cc = cc {cc_is_dupd = DupdCC}
259 isCafCC, isDupdCC :: CostCentre -> Bool
261 isCafCC (AllCafsCC {}) = True
262 isCafCC (NormalCC {cc_is_caf = CafCC}) = True
265 isDupdCC (NormalCC {cc_is_dupd = DupdCC}) = True
268 isSccCountCostCentre :: CostCentre -> Bool
269 -- Is this a cost-centre which records scc counts
272 isSccCountCostCentre NoCostCentre = panic "isSccCount:NoCostCentre"
274 isSccCountCostCentre cc | isCafCC cc = False
275 | isDupdCC cc = False
278 sccAbleCostCentre :: CostCentre -> Bool
279 -- Is this a cost-centre which can be sccd ?
282 sccAbleCostCentre NoCostCentre = panic "sccAbleCC:NoCostCentre"
284 sccAbleCostCentre cc | isCafCC cc = False
287 ccFromThisModule :: CostCentre -> Module -> Bool
288 ccFromThisModule cc m = cc_mod cc == m
292 instance Eq CostCentre where
293 c1 == c2 = case c1 `cmpCostCentre` c2 of { EQ -> True; _ -> False }
295 instance Ord CostCentre where
296 compare = cmpCostCentre
298 cmpCostCentre :: CostCentre -> CostCentre -> Ordering
300 cmpCostCentre (AllCafsCC {cc_mod = m1}) (AllCafsCC {cc_mod = m2}) = m1 `compare` m2
302 cmpCostCentre (NormalCC {cc_name = n1, cc_mod = m1, cc_is_caf = c1})
303 (NormalCC {cc_name = n2, cc_mod = m2, cc_is_caf = c2})
304 -- first key is module name, then we use "kinds" (which include
305 -- names) and finally the caf flag
306 = (m1 `compare` m2) `thenCmp` (n1 `compare` n2) `thenCmp` (c1 `cmp_caf` c2)
308 cmpCostCentre other_1 other_2
310 !tag1 = tag_CC other_1
311 !tag2 = tag_CC other_2
313 if tag1 <# tag2 then LT else GT
315 tag_CC (NormalCC {}) = _ILIT(1)
316 tag_CC (AllCafsCC {}) = _ILIT(2)
318 -- TODO: swap order of IsCafCC, add deriving Ord
319 cmp_caf :: IsCafCC -> IsCafCC -> Ordering
320 cmp_caf NotCafCC CafCC = LT
321 cmp_caf NotCafCC NotCafCC = EQ
322 cmp_caf CafCC CafCC = EQ
323 cmp_caf CafCC NotCafCC = GT
325 decomposeCCS :: CostCentreStack -> ([CostCentre],CostCentreStack)
326 decomposeCCS (PushCC cc ccs) = (cc:more, ccs')
327 where (more,ccs') = decomposeCCS ccs
328 decomposeCCS ccs = ([],ccs)
331 -----------------------------------------------------------------------------
332 Printing Cost Centre Stacks.
334 The outputable instance for CostCentreStack prints the CCS as a C
337 NOTE: Not all cost centres are suitable for using in a static
338 initializer. In particular, the PushCC forms where the tail is CCCS
339 may only be used in inline C code because they expand to a
340 non-constant C expression.
343 instance Outputable CostCentreStack where
344 ppr NoCCS = ptext (sLit "NO_CCS")
345 ppr CurrentCCS = ptext (sLit "CCCS")
346 ppr OverheadCCS = ptext (sLit "CCS_OVERHEAD")
347 ppr DontCareCCS = ptext (sLit "CCS_DONT_CARE")
348 ppr SubsumedCCS = ptext (sLit "CCS_SUBSUMED")
349 ppr (PushCC cc NoCCS) = ppr cc <> ptext (sLit "_ccs")
350 ppr (PushCC cc ccs) = ptext (sLit "PushCostCentre") <>
351 parens (ppr ccs <> comma <>
352 parens(ptext (sLit "void *")) <> ppr cc)
355 -----------------------------------------------------------------------------
356 Printing Cost Centres.
358 There are several different ways in which we might want to print a
361 - the name of the cost centre, for profiling output (a C string)
362 - the label, i.e. C label for cost centre in .hc file.
363 - the debugging name, for output in -ddump things
364 - the interface name, for printing in _scc_ exprs in iface files.
366 The last 3 are derived from costCentreStr below. The first is given
370 instance Outputable CostCentre where
371 ppr cc = getPprStyle $ \ sty ->
373 then ppCostCentreLbl cc
374 else text (costCentreUserName cc)
376 -- Printing in an interface file or in Core generally
377 pprCostCentreCore :: CostCentre -> SDoc
378 pprCostCentreCore (AllCafsCC {cc_mod = m})
379 = text "__sccC" <+> braces (ppr m)
380 pprCostCentreCore (NormalCC {cc_name = n, cc_mod = m,
381 cc_is_caf = caf, cc_is_dupd = dup})
382 = text "__scc" <+> braces (hsep [
389 pp_dup :: IsDupdCC -> SDoc
390 pp_dup DupdCC = char '!'
393 pp_caf :: IsCafCC -> SDoc
394 pp_caf CafCC = text "__C"
397 -- Printing as a C label
398 ppCostCentreLbl :: CostCentre -> SDoc
399 ppCostCentreLbl (NoCostCentre) = text "NONE_cc"
400 ppCostCentreLbl (AllCafsCC {cc_mod = m}) = ppr m <> text "_CAFs_cc"
401 ppCostCentreLbl (NormalCC {cc_name = n, cc_mod = m, cc_is_caf = is_caf})
402 = ppr m <> char '_' <> ftext (zEncodeFS n) <>
403 text (case is_caf of { CafCC -> "_CAF"; _ -> "" }) <> text "_cc"
405 -- This is the name to go in the user-displayed string,
406 -- recorded in the cost centre declaration
407 costCentreUserName :: CostCentre -> String
408 costCentreUserName (NoCostCentre) = "NO_CC"
409 costCentreUserName (AllCafsCC {}) = "CAF"
410 costCentreUserName (NormalCC {cc_name = name, cc_is_caf = is_caf})
411 = case is_caf of { CafCC -> "CAF:"; _ -> "" } ++ unpackFS name