[project @ 2001-09-20 12:14:31 by simonpj]

------------------------------------------------
	Make code generation ignore isLocalId/isGlobalId
	------------------------------------------------

	MERGE WITH STABLE BRANCH

CorePrep may introduce some new, top-level LocalIds.  This
breaks an invariant that the core2stg/code generator passes
occasionally used, namely that LocalIds are not top-level bound.

This commit fixes that problem.

It also removes an assert from CodeGen.cgTopRhs that asks
for the CgInfo of such new LocalIds -- but they may (legitimately)
not have any, so it was a bad ASSERT.  [Showed up in George
Russel's system.]

diff --git a/ghc/compiler/codeGen/CodeGen.lhs b/ghc/compiler/codeGen/CodeGen.lhs
index f9ee5b7..2b15e21 100644 (file)
--- a/ghc/compiler/codeGen/CodeGen.lhs
+++ b/ghc/compiler/codeGen/CodeGen.lhs
@@ -266,8 +266,6 @@ cgTopRhs bndr (StgRhsCon cc con args) srt
 cgTopRhs bndr (StgRhsClosure cc bi fvs upd_flag args body) srt
   =     -- There should be no free variables
     ASSERT(null fvs)
-       -- If the closure is a thunk, then the binder must be recorded as such.
-    ASSERT2(not (isUpdatable upd_flag) || mayHaveCafRefs (idCafInfo bndr), ppr bndr)
 
     getSRTLabel `thenFC` \srt_label ->
     let lf_info = 

diff --git a/ghc/compiler/stgSyn/CoreToStg.lhs b/ghc/compiler/stgSyn/CoreToStg.lhs
index 04da56d..9db3177 100644 (file)
--- a/ghc/compiler/stgSyn/CoreToStg.lhs
+++ b/ghc/compiler/stgSyn/CoreToStg.lhs
@@ -788,7 +788,8 @@ type LneM a =  IdEnv HowBound
            -> a
 
 data HowBound
-  = ImportBound
+  = ImportBound                -- Used only as a response to lookupBinding; never
+                       -- exists in the range of the (IdEnv HowBound)
   | CaseBound
   | LambdaBound
   | LetBound
@@ -873,12 +874,13 @@ extendVarEnvLne ids_w_howbound expr env lvs_cont
   = expr (extendVarEnvList env ids_w_howbound) lvs_cont
 
 lookupVarLne :: Id -> LneM HowBound
-lookupVarLne v env lvs_cont
-  = returnLne (
-      case (lookupVarEnv env v) of
-       Just xx -> xx
-       Nothing -> ImportBound
-    ) env lvs_cont
+lookupVarLne v env lvs_cont = returnLne (lookupBinding env v) env lvs_cont
+
+lookupBinding :: IdEnv HowBound -> Id -> HowBound
+lookupBinding env v = case lookupVarEnv env v of
+                       Just xx -> xx
+                       Nothing -> ASSERT( isGlobalId v ) ImportBound
+
 
 -- The result of lookupLiveVarsForSet, a set of live variables, is
 -- only ever tacked onto a decorated expression. It is never used as
@@ -889,29 +891,24 @@ freeVarsToLiveVars fvs env live_in_cont
   = returnLne (lvs, cafs) env live_in_cont
   where
     (lvs_cont, cafs_cont) = live_in_cont -- not a strict pattern match!
-    (local, global) = partition isLocalId (allFreeIds fvs)
-
-    (lvs_from_fvs, caf_extras) = unzip (map do_one local)
 
-    lvs = unionVarSets lvs_from_fvs
-               `unionVarSet` lvs_cont
+    (lvs_from_fvs, caf_from_fvs) = unzip (map do_one (allFreeIds fvs))
 
-    cafs = mkVarSet (filter is_caf_one global) 
-               `unionVarSet` (unionVarSets caf_extras)
-               `unionVarSet` cafs_cont
+    lvs  = unionVarSets lvs_from_fvs `unionVarSet` lvs_cont
+    cafs = unionVarSets caf_from_fvs `unionVarSet` cafs_cont
 
     do_one v
-      = case (lookupVarEnv env v) of
-             Just (LetBound _ (lvs,cafs) _) -> (extendVarSet lvs v, cafs)
-             Just _                         -> (unitVarSet v, emptyVarSet)
-             Nothing -> pprPanic "lookupLiveVarsForSet/do_one:" (ppr v)
-
-    is_caf_one v
-      = case lookupVarEnv env v of
-               Just (LetBound TopLevelHasCafs (lvs,_) _) ->
-                   ASSERT( isEmptyVarSet lvs ) True
-               Just (LetBound _ _ _) -> False
-               _otherwise          -> mayHaveCafRefs (idCafInfo v)
+      = case lookupBinding env v of
+         LetBound caf_ness (lvs,cafs) _ ->
+           case caf_ness of
+               TopLevelHasCafs  -> ASSERT( isEmptyVarSet lvs ) (emptyVarSet, unitVarSet v)
+               TopLevelNoCafs   -> ASSERT( isEmptyVarSet lvs ) (emptyVarSet, emptyVarSet)
+               NotTopLevelBound -> (extendVarSet lvs v, cafs)
+
+         ImportBound | mayHaveCafRefs (idCafInfo v) -> (emptyVarSet, unitVarSet v)
+                     | otherwise                    -> (emptyVarSet, emptyVarSet)
+
+         _nested_binding -> (unitVarSet v, emptyVarSet)        -- Bound by lambda or case
 \end{code}
 
 %************************************************************************
@@ -1080,12 +1077,10 @@ hasCafRefss p exprs
 -- cafRefs compiles to beautiful code :)
 
 cafRefs p (Var id)
-  | isLocalId id = fastBool False
-  | otherwise = 
-      case lookupVarEnv p id of
-       Just (LetBound TopLevelHasCafs _ _) -> fastBool True
-        Just (LetBound _ _ _) -> fastBool False
-       Nothing -> fastBool (cgMayHaveCafRefs (idCgInfo id)) --  imported Ids
+  = case lookupBinding p id of
+       ImportBound                  -> fastBool (mayHaveCafRefs (idCafInfo id))
+       LetBound TopLevelHasCafs _ _ -> fastBool True
+        other                       -> fastBool False
 
 cafRefs p (Lit l)           = fastBool False
 cafRefs p (App f a)         = fastOr (cafRefs p f) (cafRefs p) a