X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=compiler%2Fstranal%2FDmdAnal.lhs;h=3fc84773af953823e92b89a5eeaf125dd1612aac;hb=2f6ad11fa0c2995d950c91fd4301f23aceeb443b;hp=c5cfb7b4bdedde682e5b88669b8305dfef7c07ab;hpb=0065d5ab628975892cea1ec7303f968c3338cbe1;p=ghc-hetmet.git

diff --git a/compiler/stranal/DmdAnal.lhs b/compiler/stranal/DmdAnal.lhs
index c5cfb7b..3fc8477 100644
--- a/compiler/stranal/DmdAnal.lhs
+++ b/compiler/stranal/DmdAnal.lhs
@@ -40,7 +40,8 @@ import TysWiredIn	( unboxedPairDataCon )
 import TysPrim		( realWorldStatePrimTy )
 import UniqFM		( plusUFM_C, addToUFM_Directly, lookupUFM_Directly,
 			  keysUFM, minusUFM, ufmToList, filterUFM )
-import Type		( isUnLiftedType, coreEqType )
+import Type		( isUnLiftedType, coreEqType, splitTyConApp_maybe )
+import Coercion         ( coercionKind )
 import CoreLint		( showPass, endPass )
 import Util		( mapAndUnzip, mapAccumL, mapAccumR, lengthIs )
 import BasicTypes	( Arity, TopLevelFlag(..), isTopLevel, isNeverActive,
@@ -164,16 +165,25 @@ dmdAnal sigs dmd (Lit lit)
 dmdAnal sigs dmd (Var var)
   = (dmdTransform sigs var dmd, Var var)
 
+dmdAnal sigs dmd (Cast e co)
+  = (dmd_ty, Cast e' co)
+  where
+    (dmd_ty, e') = dmdAnal sigs dmd' e
+    to_co        = snd (coercionKind co)
+    dmd'
+      | Just (tc, args) <- splitTyConApp_maybe to_co
+      , isRecursiveTyCon tc = evalDmd
+      | otherwise           = dmd
+	-- This coerce usually arises from a recursive
+        -- newtype, and we don't want to look inside them
+	-- for exactly the same reason that we don't look
+	-- inside recursive products -- we might not reach
+	-- a fixpoint.  So revert to a vanilla Eval demand
+
 dmdAnal sigs dmd (Note n e)
   = (dmd_ty, Note n e')
   where
-    (dmd_ty, e') = dmdAnal sigs dmd' e	
-    dmd' = case n of
-	     Coerce _ _ -> evalDmd  -- This coerce usually arises from a recursive
-	     other	-> dmd 	    -- newtype, and we don't want to look inside them
-				    -- for exactly the same reason that we don't look
-				    -- inside recursive products -- we might not reach
-				    -- a fixpoint.  So revert to a vanilla Eval demand
+    (dmd_ty, e') = dmdAnal sigs dmd e	
 
 dmdAnal sigs dmd (App fun (Type ty))
   = (fun_ty, App fun' (Type ty))
@@ -530,34 +540,6 @@ by dmdAnalTopBind.
 
 \begin{code}
 mk_sig_ty never_inline thunk_cpr_ok rhs (DmdType fv dmds res) 
-  | never_inline && not (isBotRes res)
-	-- 			HACK ALERT
-	-- Don't strictness-analyse NOINLINE things.  Why not?  Because
-	-- the NOINLINE says "don't expose any of the inner workings at the call 
-	-- site" and the strictness is certainly an inner working.
-	--
-	-- More concretely, the demand analyser discovers the following strictness
-	-- for unsafePerformIO:  C(U(AV))
-	-- But then consider
-	--	unsafePerformIO (\s -> let r = f x in 
-	--			       case writeIORef v r s of (# s1, _ #) ->
-	--			       (# s1, r #)
-	-- The strictness analyser will find that the binding for r is strict,
-	-- (becuase of uPIO's strictness sig), and so it'll evaluate it before 
-	-- doing the writeIORef.  This actually makes tests/lib/should_run/memo002
-	-- get a deadlock!  
-	--
-	-- Solution: don't expose the strictness of unsafePerformIO.
-	--
-	-- But we do want to expose the strictness of error functions, 
-	-- which are also often marked NOINLINE
-	--	{-# NOINLINE foo #-}
-	--	foo x = error ("wubble buggle" ++ x)
-	-- So (hack, hack) we only drop the strictness for non-bottom things
-	-- This is all very unsatisfactory.
-  = (deferEnv fv, topSig)
-
-  | otherwise
   = (lazy_fv, mkStrictSig dmd_ty)
   where
     dmd_ty = DmdType strict_fv final_dmds res'