Fix Trac #1988; keep the ru_fn field of a RULE up to date

[ghc-hetmet.git] / compiler / basicTypes / IdInfo.lhs

diff --git a/compiler/basicTypes/IdInfo.lhs b/compiler/basicTypes/IdInfo.lhs
index 02ef0db..7eacbd8 100644 (file)
--- a/compiler/basicTypes/IdInfo.lhs
+++ b/compiler/basicTypes/IdInfo.lhs
@@ -8,6 +8,13 @@
 Haskell. [WDP 94/11])
 
 \begin{code}
+{-# OPTIONS -w #-}
+-- The above warning supression flag is a temporary kludge.
+-- While working on this module you are encouraged to remove it and fix
+-- any warnings in the module. See
+--     http://hackage.haskell.org/trac/ghc/wiki/Commentary/CodingStyle#Warnings
+-- for details
+
 module IdInfo (
        GlobalIdDetails(..), notGlobalId,       -- Not abstract
 
@@ -65,7 +72,7 @@ module IdInfo (
 
        -- Specialisation
        SpecInfo(..), specInfo, setSpecInfo, isEmptySpecInfo, 
-       specInfoFreeVars, specInfoRules, seqSpecInfo,
+       specInfoFreeVars, specInfoRules, seqSpecInfo, setSpecInfoHead,
 
        -- CAF info
        CafInfo(..), cafInfo, ppCafInfo, setCafInfo, mayHaveCafRefs,
@@ -82,6 +89,7 @@ module IdInfo (
 import CoreSyn
 import Class
 import PrimOp
+import Name
 import Var
 import VarSet
 import BasicTypes
@@ -95,7 +103,6 @@ import Module
 import Data.Maybe
 
 #ifdef OLD_STRICTNESS
-import Name
 import Demand
 import qualified Demand
 import Util
@@ -232,7 +239,8 @@ data GlobalIdDetails
   = VanillaGlobal              -- Imported from elsewhere, a default method Id.
 
   | RecordSelId                 -- The Id for a record selector
-    { sel_tycon   :: TyCon
+    { sel_tycon   :: TyCon     -- For a data type family, this is the *instance* TyCon
+                               --      not the family TyCon
     , sel_label   :: FieldLabel
     , sel_naughty :: Bool       -- True <=> naughty
     }                          -- See Note [Naughty record selectors]
@@ -463,9 +471,13 @@ type InlinePragInfo = Activation
 %************************************************************************
 
 \begin{code}
--- CoreRules is used only in an idSpecialisation (move to IdInfo?)
 data SpecInfo 
-  = SpecInfo [CoreRule] VarSet -- Locally-defined free vars of RHSs
+  = SpecInfo 
+       [CoreRule] 
+       VarSet          -- Locally-defined free vars of *both* LHS and RHS 
+                       -- of rules.  I don't think it needs to include the
+                       -- ru_fn though.
+                       -- Note [Rule dependency info]
 
 emptySpecInfo :: SpecInfo
 emptySpecInfo = SpecInfo [] emptyVarSet
@@ -479,9 +491,26 @@ specInfoFreeVars (SpecInfo _ fvs) = fvs
 specInfoRules :: SpecInfo -> [CoreRule]
 specInfoRules (SpecInfo rules _) = rules
 
+setSpecInfoHead :: Name -> SpecInfo -> SpecInfo
+setSpecInfoHead fn (SpecInfo rules fvs)
+  = SpecInfo (map set_head rules) fvs
+  where
+    set_head rule = rule { ru_fn = fn }
+
 seqSpecInfo (SpecInfo rules fvs) = seqRules rules `seq` seqVarSet fvs
 \end{code}
 
+Note [Rule dependency info]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~
+THe VarSet in a SpecInfo is used for dependency analysis in the 
+occurrence analyser.  We must track free vars in *both* lhs and rhs.  Why both?  
+Consider
+       x = y
+       RULE f x = 4
+Then if we substitute y for x, we'd better do so in the
+ rule's LHS too, so we'd better ensure the dependency is respected
+
+
 
 %************************************************************************
 %*                                                                     *
@@ -683,11 +712,11 @@ zapLamInfo info@(IdInfo {occInfo = occ, newDemandInfo = demand})
        -- The "unsafe" occ info is the ones that say I'm not in a lambda
        -- because that might not be true for an unsaturated lambda
     is_safe_occ (OneOcc in_lam _ _) = in_lam
-    is_safe_occ other              = True
+    is_safe_occ _other             = True
 
     safe_occ = case occ of
                 OneOcc _ once int_cxt -> OneOcc insideLam once int_cxt
-                other                 -> occ
+                _other                -> occ
 
     is_safe_dmd Nothing    = True
     is_safe_dmd (Just dmd) = not (isStrictDmd dmd)
@@ -703,9 +732,13 @@ zapDemandInfo info@(IdInfo {newDemandInfo = dmd})
 \begin{code}
 zapFragileInfo :: IdInfo -> Maybe IdInfo
 -- Zap info that depends on free variables
-zapFragileInfo info = Just (info `setSpecInfo` emptySpecInfo
-                                `setWorkerInfo` NoWorker
-                                 `setUnfoldingInfo` NoUnfolding)
+zapFragileInfo info 
+  = Just (info `setSpecInfo` emptySpecInfo
+              `setWorkerInfo` NoWorker
+               `setUnfoldingInfo` NoUnfolding
+              `setOccInfo` if isFragileOcc occ then NoOccInfo else occ)
+  where
+    occ = occInfo info
 \end{code}
 
 %************************************************************************
@@ -718,8 +751,8 @@ zapFragileInfo info = Just (info `setSpecInfo` emptySpecInfo
 type TickBoxId = Int
 
 data TickBoxOp 
-   = TickBox Module !TickBoxId  -- ^Tick box for Hpc-style coverage,
-                               -- type = State# Void#
+   = TickBox Module {-# UNPACK #-} !TickBoxId
+          -- ^Tick box for Hpc-style coverage
 
 instance Outputable TickBoxOp where
     ppr (TickBox mod n)         = ptext SLIT("tick") <+> ppr (mod,n)