Monadify simplCore/SimplEnv: use standard monad functions

[ghc-hetmet.git] / compiler / simplCore / CSE.lhs

diff --git a/compiler/simplCore/CSE.lhs b/compiler/simplCore/CSE.lhs
index 39344fc..3bcc177 100644 (file)
--- a/compiler/simplCore/CSE.lhs
+++ b/compiler/simplCore/CSE.lhs
@@ -4,6 +4,13 @@
 \section{Common subexpression}
 
 \begin{code}
+{-# OPTIONS -w #-}
+-- The above warning supression flag is a temporary kludge.
+-- While working on this module you are encouraged to remove it and fix
+-- any warnings in the module. See
+--     http://hackage.haskell.org/trac/ghc/wiki/Commentary/CodingStyle#Warnings
+-- for details
+
 module CSE (
        cseProgram
     ) where
@@ -21,8 +28,10 @@ import CoreLint              ( showPass, endPass )
 import Outputable
 import StaticFlags     ( opt_PprStyle_Debug )
 import BasicTypes      ( isAlwaysActive )
-import Util            ( mapAccumL, lengthExceeds )
+import Util            ( lengthExceeds )
 import UniqFM
+
+import Data.List
 \end{code}
 
 
@@ -108,8 +117,8 @@ Instead, we shoudl replace (f x) by (# a,b #).  That is, the "reverse mapping" i
        f x --> (# a,b #)
 That is why the CSEMap has pairs of expressions.
 
-Note [INLINE and NOINLINE]
-~~~~~~~~~~~~~~~~~~~~~~~~~~
+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 
 
@@ -162,7 +171,7 @@ Not CSE-ing inside INLINE also solves an annoying bug in CSE. Consider
 a worker/wrapper, in which the worker has turned into a single variable:
        $wf = h
        f = \x -> ...$wf...
-Now CSE may transoform to
+Now CSE may transform to
        f = \x -> ...h...
 But the WorkerInfo for f still says $wf, which is now dead!  This won't
 happen now that we don't look inside INLINEs (which wrappers are).
@@ -207,7 +216,7 @@ do_one env (id, rhs)
     (env', id') = addBinder env id
     rhs' | isAlwaysActive (idInlinePragma id) = cseExpr env' rhs
         | otherwise                          = rhs
-               -- See Note [INLINE and NOINLINE]
+               -- See Note [CSE for INLINE and NOINLINE]
 
 tryForCSE :: CSEnv -> CoreExpr -> CoreExpr
 tryForCSE env (Type t) = Type t
@@ -222,7 +231,7 @@ cseExpr env (Type t)                   = Type t
 cseExpr env (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 evn (Note InlineMe e)     = Note InlineMe e    -- See Note [INLINE and NOINLINE]
+cseExpr env (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