X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=compiler%2FsimplCore%2FCSE.lhs;h=5bec8f0c3d7705dbaf78cce28f9886013004477d;hp=8b5825bf6a9d9f37eda8da1b02efe71e20546c8f;hb=2c8aabcad1d2f2c469cb8a10afa7b66beeaedd45;hpb=9bcd95bad83ee937c178970e8b729732e680fe1e

diff --git a/compiler/simplCore/CSE.lhs b/compiler/simplCore/CSE.lhs
index 8b5825b..5bec8f0 100644
--- a/compiler/simplCore/CSE.lhs
+++ b/compiler/simplCore/CSE.lhs
@@ -10,8 +10,8 @@ module CSE (
 
 #include "HsVersions.h"
 
-import Id		( Id, idType, idInlinePragma, zapIdOccInfo )
-import CoreUtils	( hashExpr, cheapEqExpr, exprIsBig, mkAltExpr, exprIsCheap )
+import Id		( Id, idType, idInlineActivation, zapIdOccInfo )
+import CoreUtils	( hashExpr, eqExpr, exprIsBig, mkAltExpr, exprIsCheap )
 import DataCon		( isUnboxedTupleCon )
 import Type		( tyConAppArgs )
 import CoreSyn
@@ -49,8 +49,8 @@ So we carry an extra var->var substitution which we apply *before* looking up in
 reverse mapping.
 
 
-[Note: SHADOWING]
-~~~~~~~~~~~~~~~~~
+Note [Shadowing]
+~~~~~~~~~~~~~~~~
 We have to be careful about shadowing.
 For example, consider
 	f = \x -> let y = x+x in
@@ -114,7 +114,7 @@ Note [CSE for INLINE and NOINLINE]
 We are careful to do no CSE inside functions that the user has marked as
 INLINE or NOINLINE.  In terms of Core, that means 
 
-	a) we do not do CSE inside (Note InlineMe e)
+	a) we do not do CSE inside an InlineRule
 
 	b) we do not do CSE on the RHS of a binding b=e
 	   unless b's InlinePragma is AlwaysActive
@@ -201,12 +201,13 @@ do_one env (id, rhs)
 	Nothing             -> (addCSEnvItem env' rhs' (Var id'), (id', rhs'))
   where
     (env', id') = addBinder env id
-    rhs' | isAlwaysActive (idInlinePragma id) = cseExpr env' rhs
-	 | otherwise			      = rhs
+    rhs' | isAlwaysActive (idInlineActivation id) = cseExpr env' rhs
+	 | otherwise			          = rhs
 		-- See Note [CSE for INLINE and NOINLINE]
 
 tryForCSE :: CSEnv -> CoreExpr -> CoreExpr
 tryForCSE _   (Type t) = Type t
+tryForCSE _   (Coercion c) = Coercion c
 tryForCSE env expr     = case lookupCSEnv env expr' of
 			    Just smaller_expr -> smaller_expr
  			    Nothing  	      -> expr'
@@ -215,10 +216,10 @@ tryForCSE env expr     = case lookupCSEnv env expr' of
 
 cseExpr :: CSEnv -> CoreExpr -> CoreExpr
 cseExpr _   (Type t)               = Type t
+cseExpr _   (Coercion co)          = Coercion co
 cseExpr _   (Lit lit)              = Lit lit
 cseExpr env (Var v)		   = Var (lookupSubst env v)
 cseExpr env (App f a)        	   = App (cseExpr env f) (tryForCSE env a)
-cseExpr _   (Note InlineMe e)      = Note InlineMe e    -- See Note [CSE for INLINE and NOINLINE]
 cseExpr env (Note n e)       	   = Note n (cseExpr env e)
 cseExpr env (Cast e co)            = Cast (cseExpr env e) co
 cseExpr env (Lam b e)	     	   = let (env', b') = addBinder env b
@@ -239,7 +240,7 @@ cseAlts :: CSEnv -> CoreExpr -> CoreBndr -> CoreBndr -> [CoreAlt] -> [CoreAlt]
 cseAlts env scrut' bndr _bndr' [(DataAlt con, args, rhs)]
   | isUnboxedTupleCon con
 	-- Unboxed tuples are special because the case binder isn't
-	-- a real values.  See Note [Unboxed tuple case binders]
+	-- a real value.  See Note [Unboxed tuple case binders]
   = [(DataAlt con, args'', tryForCSE new_env rhs)]
   where
     (env', args') = addBinders env args
@@ -302,15 +303,19 @@ emptyCSEnv :: CSEnv
 emptyCSEnv = CS emptyUFM emptyInScopeSet emptyVarEnv
 
 lookupCSEnv :: CSEnv -> CoreExpr -> Maybe CoreExpr
-lookupCSEnv (CS cs _ _) expr
+lookupCSEnv (CS cs in_scope _) expr
   = case lookupUFM cs (hashExpr expr) of
 	Nothing -> Nothing
-	Just pairs -> lookup_list pairs expr
-
-lookup_list :: [(CoreExpr,CoreExpr)] -> CoreExpr -> Maybe CoreExpr
-lookup_list [] _ = Nothing
-lookup_list ((e,e'):es) expr | cheapEqExpr e expr = Just e'
-			     | otherwise	  = lookup_list es expr
+	Just pairs -> lookup_list pairs
+  where
+  -- In this lookup we use full expression equality
+  -- Reason: when expressions differ we generally find out quickly
+  --         but I found that cheapEqExpr was saying (\x.x) /= (\y.y),
+  -- 	     and this kind of thing happened in real programs
+    lookup_list :: [(CoreExpr,CoreExpr)] -> Maybe CoreExpr
+    lookup_list []                                   = Nothing
+    lookup_list ((e,e'):es) | eqExpr in_scope e expr = Just e'
+        		    | otherwise	             = lookup_list es
 
 addCSEnvItem :: CSEnv -> CoreExpr -> CoreExpr -> CSEnv
 addCSEnvItem env expr expr' | exprIsBig expr = env
@@ -342,12 +347,12 @@ extendSubst (CS cs in_scope sub) x y = CS cs in_scope (extendVarEnv sub x y)
 addBinder :: CSEnv -> Id -> (CSEnv, Id)
 addBinder (CS cs in_scope sub) v
   | not (v `elemInScopeSet` in_scope) = (CS cs (extendInScopeSet in_scope v)  sub,		       v)
-  | isIdVar v			      = (CS cs (extendInScopeSet in_scope v') (extendVarEnv sub v v'), v')
+  | isId v			      = (CS cs (extendInScopeSet in_scope v') (extendVarEnv sub v v'), v')
   | otherwise			      = WARN( True, ppr v )
 				        (CS emptyUFM in_scope		      sub,		       v)
 	-- This last case is the unusual situation where we have shadowing of
 	-- a type variable; we have to discard the CSE mapping
-	-- See "IMPORTANT NOTE" at the top 
+	-- See Note [Shadowing]
   where
     v' = uniqAway in_scope v