-- any warnings in the module. See
-- http://hackage.haskell.org/trac/ghc/wiki/Commentary/CodingStyle#Warnings
-- for details
+{-# LANGUAGE DeriveDataTypeable #-}
module CostCentre (
CostCentre(..), CcName, IsDupdCC(..), IsCafCC(..),
noCostCentre, noCCAttached,
noCCSAttached, isCurrentCCS, isSubsumedCCS, currentOrSubsumedCCS,
isDerivedFromCurrentCCS, maybeSingletonCCS,
- decomposeCCS,
+ decomposeCCS, pushCCisNop,
mkUserCC, mkAutoCC, mkAllCafsCC,
mkSingletonCCS, dupifyCC, pushCCOnCCS,
import FastTypes
import FastString
import Util ( thenCmp )
+
+import Data.Data
\end{code}
A Cost Centre Stack is something that can be attached to a closure.
| AllCafsCC {
cc_mod :: Module -- Name of module defining this CC.
}
+ deriving (Data, Typeable)
type CcName = FastString
-- but we are trying to avoid confusion between
-- "subd" and "subsumed". So we call the former
-- "dupd".
+ deriving (Data, Typeable)
data IsCafCC = CafCC | NotCafCC
+ deriving (Data, Typeable)
-- synonym for triple which describes the cost centre info in the generated
-- code for a module.
maybeSingletonCCS :: CostCentreStack -> Maybe CostCentre
maybeSingletonCCS (PushCC cc NoCCS) = Just cc
maybeSingletonCCS _ = Nothing
+
+pushCCisNop :: CostCentre -> CostCentreStack -> Bool
+-- (pushCCisNop cc ccs) = True => pushing cc on ccs is a no-op
+-- It's safe to return False, but the optimiser can remove
+-- redundant pushes if this function returns True.
+pushCCisNop cc (PushCC cc' _) = cc == cc'
+pushCCisNop _ _ = False
\end{code}
Building cost centres
cmpCostCentre other_1 other_2
= let
- tag1 = tag_CC other_1
- tag2 = tag_CC other_2
+ !tag1 = tag_CC other_1
+ !tag2 = tag_CC other_2
in
if tag1 <# tag2 then LT else GT
where