X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=compiler%2FdeSugar%2FDsBinds.lhs;h=e65da3cf9ba13e161f746f46ea9174e62929e835;hp=020b7b4fa3acf7f3c44686633cb238b2372c3d4f;hb=90ce88a0a9b5611416e592a6ff96781ba884975f;hpb=7e8cba32c6f045dde3db8a9ddc9831ec8ab4ed43

diff --git a/compiler/deSugar/DsBinds.lhs b/compiler/deSugar/DsBinds.lhs
index 020b7b4..e65da3c 100644
--- a/compiler/deSugar/DsBinds.lhs
+++ b/compiler/deSugar/DsBinds.lhs
@@ -36,6 +36,7 @@ import TcType
 import CostCentre
 import Module
 import Id
+import MkId	( seqId )
 import Var	( Var, TyVar )
 import VarSet
 import Rules
@@ -163,14 +164,16 @@ dsHsBind auto_scc rest (AbsBinds [] [] exports binds)
   where B is the *non-recursive* binding
 	fl = fg a b
 	gl = gg b
-	h  = h a b 
+	h  = h a b    -- See (b); note shadowing!
   
   Notice (a) g has a different number of type variables to f, so we must
 	     use the mkArbitraryType thing to fill in the gaps.  
 	     We use a type-let to do that.
 
 	 (b) The local variable h isn't in the exports, and rather than
-	     clone a fresh copy we simply replace h by (h a b).  
+	     clone a fresh copy we simply replace h by (h a b), where
+	     the two h's have different types!  Shadowing happens here,
+	     which looks confusing but works fine.
 
 	 (c) The result is *still* quadratic-sized if there are a lot of
 	     small bindings.  So if there are more than some small
@@ -474,6 +477,12 @@ decomposeRuleLhs lhs
         -- a LHS:       let f71 = M.f Int in f71
     decomp env (Let (NonRec dict rhs) body) 
         = decomp (extendVarEnv env dict (simpleSubst env rhs)) body
+
+    decomp env (Case scrut bndr ty [(DEFAULT, _, body)])
+        | isDeadBinder bndr	-- Note [Matching seqId]
+        = Just (seqId, [Type (idType bndr), Type ty, 
+                        simpleSubst env scrut, simpleSubst env body])
+
     decomp env body 
         = case collectArgs (simpleSubst env body) of
             (Var fn, args) -> Just (fn, args)
@@ -514,17 +523,23 @@ addInlinePrags prags bndr rhs
 	(inl:_) -> addInlineInfo inl bndr rhs
 
 addInlineInfo :: InlineSpec -> Id -> CoreExpr -> (Id,CoreExpr)
-addInlineInfo (Inline phase is_inline) bndr rhs
-  = (attach_phase bndr phase, wrap_inline is_inline rhs)
+addInlineInfo (Inline prag is_inline) bndr rhs
+  = (attach_pragma bndr prag, wrap_inline is_inline rhs)
   where
-    attach_phase bndr phase 
-	| isAlwaysActive phase = bndr	-- Default phase
-	| otherwise  	       = bndr `setInlinePragma` phase
+    attach_pragma bndr prag
+        | isDefaultInlinePragma prag = bndr
+        | otherwise                  = bndr `setInlinePragma` prag
 
     wrap_inline True  body = mkInlineMe body
     wrap_inline False body = body
 \end{code}
 
+Note [Matching seq]
+~~~~~~~~~~~~~~~~~~~
+The desugarer turns (seq e r) into (case e of _ -> r), via a special-case hack
+and this code turns it back into an application of seq!  
+See Note [Rules for seq] in MkId for the details.
+
 
 %************************************************************************
 %*									*