[project @ 2001-03-01 17:10:06 by simonpj]

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

diff --git a/ghc/compiler/basicTypes/IdInfo.lhs b/ghc/compiler/basicTypes/IdInfo.lhs
index ca1e2b3..91ecbe2 100644 (file)
--- a/ghc/compiler/basicTypes/IdInfo.lhs
+++ b/ghc/compiler/basicTypes/IdInfo.lhs
@@ -13,7 +13,8 @@ module IdInfo (
        vanillaIdInfo, constantIdInfo, mkIdInfo, seqIdInfo, megaSeqIdInfo,
 
        -- Zapping
-       zapFragileInfo, zapLamInfo, zapSpecPragInfo, shortableIdInfo, copyIdInfo,
+       zapLamInfo, zapDemandInfo,
+       zapSpecPragInfo, shortableIdInfo, copyIdInfo,
 
        -- Flavour
        IdFlavour(..), flavourInfo,  makeConstantFlavour,
@@ -66,7 +67,7 @@ module IdInfo (
         CprInfo(..), cprInfo, setCprInfo, ppCprInfo, noCprInfo,
 
         -- Lambda-bound variable info
-        LBVarInfo(..), lbvarInfo, setLBVarInfo, noLBVarInfo
+        LBVarInfo(..), lbvarInfo, setLBVarInfo, noLBVarInfo, hasNoLBVarInfo
     ) where
 
 #include "HsVersions.h"
@@ -633,6 +634,9 @@ seqLBVar l = l `seq` ()
 \end{code}
 
 \begin{code}
+hasNoLBVarInfo NoLBVarInfo = True
+hasNoLBVarInfo other       = False
+
 noLBVarInfo = NoLBVarInfo
 
 -- not safe to print or parse LBVarInfo because it is not really a
@@ -660,58 +664,6 @@ instance Show LBVarInfo where
 %*                                                                     *
 %************************************************************************
 
-zapFragileInfo is used when cloning binders, mainly in the
-simplifier.  We must forget about used-once information because that
-isn't necessarily correct in the transformed program.
-Also forget specialisations and unfoldings because they would need
-substitution to be correct.  (They get pinned back on separately.)
-
-Hoever, we REMEMBER loop-breaker and dead-variable information.  The loop-breaker
-information is used (for example) in MkIface to avoid exposing the unfolding of
-a loop breaker.
-
-\begin{code}
-zapFragileInfo :: IdInfo -> Maybe IdInfo
-zapFragileInfo info@(IdInfo {occInfo           = occ, 
-                            workerInfo         = wrkr,
-                            specInfo           = rules, 
-                            unfoldingInfo      = unfolding})
-  |  not (isFragileOcc occ)
-        -- We must forget about whether it was marked safe-to-inline,
-       -- because that isn't necessarily true in the simplified expression.
-       -- This is important because expressions may  be re-simplified
-       -- We don't zap deadness or loop-breaker-ness.
-       -- The latter is important because it tells MkIface not to 
-       -- spit out an inlining for the thing.  The former doesn't
-       -- seem so important, but there's no harm.
-
-  && isEmptyCoreRules rules
-       -- Specialisations would need substituting.  They get pinned
-       -- back on separately.
-
-  && not (workerExists wrkr)
-
-  && not (hasUnfolding unfolding)
-       -- This is very important; occasionally a let-bound binder is used
-       -- as a binder in some lambda, in which case its unfolding is utterly
-       -- bogus.  Also the unfolding uses old binders so if we left it we'd
-       -- have to substitute it. Much better simply to give the Id a new
-       -- unfolding each time, which is what the simplifier does.
-  = Nothing
-
-  | otherwise
-  = Just (info {occInfo                = robust_occ_info,
-               workerInfo      = noWorkerInfo,
-               specInfo        = emptyCoreRules,
-               unfoldingInfo   = noUnfolding})
-  where
-       -- It's important to keep the loop-breaker info,
-       -- because the substitution doesn't remember it.
-    robust_occ_info = case occ of
-                       OneOcc _ _ -> NoOccInfo
-                       other      -> occ
-\end{code}
-
 @zapLamInfo@ is used for lambda binders that turn out to to be
 part of an unsaturated lambda
 
@@ -735,6 +687,13 @@ zapLamInfo info@(IdInfo {occInfo = occ, demandInfo = demand})
                 other         -> occ
 \end{code}
 
+\begin{code}
+zapDemandInfo :: IdInfo -> Maybe IdInfo
+zapDemandInfo info@(IdInfo {demandInfo = demand})
+  | not (isStrict demand) = Nothing
+  | otherwise            = Just (info {demandInfo = wwLazy})
+\end{code}
+
 
 copyIdInfo is used when shorting out a top-level binding
        f_local = BIG