Rollback INLINE patches

[ghc-hetmet.git] / compiler / coreSyn / CoreUtils.lhs

diff --git a/compiler/coreSyn/CoreUtils.lhs b/compiler/coreSyn/CoreUtils.lhs
index 146f8cf..44ca27a 100644 (file)
--- a/compiler/coreSyn/CoreUtils.lhs
+++ b/compiler/coreSyn/CoreUtils.lhs
@@ -6,35 +6,45 @@
 Utility functions on @Core@ syntax
 
 \begin{code}
 Utility functions on @Core@ syntax
 
 \begin{code}

+{-# OPTIONS -fno-warn-incomplete-patterns #-}
+-- 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
+
+-- | Commonly useful utilites for manipulating the Core language

 module CoreUtils (
 module CoreUtils (

-       -- Construction
-       mkInlineMe, mkSCC, mkCoerce, 
+       -- * Constructing expressions
+       mkInlineMe, mkSCC, mkCoerce, mkCoerceI,

        bindNonRec, needsCaseBinding,
        bindNonRec, needsCaseBinding,

-       mkIfThenElse, mkAltExpr, mkPiType, mkPiTypes,
+       mkAltExpr, mkPiType, mkPiTypes,

 
 

-       -- Taking expressions apart
-       findDefault, findAlt, isDefaultAlt, mergeAlts,
+       -- * Taking expressions apart
+       findDefault, findAlt, isDefaultAlt, mergeAlts, trimConArgs,

 
 

-       -- Properties of expressions
-       exprType, coreAltType,
+       -- * Properties of expressions
+       exprType, coreAltType, coreAltsType,

        exprIsDupable, exprIsTrivial, exprIsCheap, 
        exprIsHNF,exprOkForSpeculation, exprIsBig, 
        exprIsConApp_maybe, exprIsBottom,
        rhsIsStatic,
 
        exprIsDupable, exprIsTrivial, exprIsCheap, 
        exprIsHNF,exprOkForSpeculation, exprIsBig, 
        exprIsConApp_maybe, exprIsBottom,
        rhsIsStatic,
 

-       -- Arity and eta expansion
+       -- * Arity and eta expansion

        manifestArity, exprArity, 
        exprEtaExpandArity, etaExpand, 
 
        manifestArity, exprArity, 
        exprEtaExpandArity, etaExpand, 
 

-       -- Size
-       coreBindsSize,
+       -- * Expression and bindings size
+       coreBindsSize, exprSize,

 
 

-       -- Hashing
+       -- * Hashing

        hashExpr,
 
        hashExpr,
 

-       -- Equality
-       cheapEqExpr, tcEqExpr, tcEqExprX, applyTypeToArgs, applyTypeToArg,
+       -- * Equality
+       cheapEqExpr, tcEqExpr, tcEqExprX,

 
 

+       -- * Manipulating data constructors and types
+       applyTypeToArgs, applyTypeToArg,

         dataConOrigInstPat, dataConRepInstPat, dataConRepFSInstPat
     ) where
 
         dataConOrigInstPat, dataConRepInstPat, dataConRepFSInstPat
     ) where
 

@@ -48,6 +58,7 @@ import SrcLoc
 import VarSet
 import VarEnv
 import Name
 import VarSet
 import VarEnv
 import Name

+import Module

 #if mingw32_TARGET_OS
 import Packages
 #endif
 #if mingw32_TARGET_OS
 import Packages
 #endif

@@ -60,16 +71,17 @@ import NewDemand
 import Type
 import Coercion
 import TyCon
 import Type
 import Coercion
 import TyCon

-import TysWiredIn

 import CostCentre
 import BasicTypes
 import CostCentre
 import BasicTypes

-import PackageConfig

 import Unique
 import Outputable
 import DynFlags
 import TysPrim
 import FastString
 import Unique
 import Outputable
 import DynFlags
 import TysPrim
 import FastString

+import Maybes

 import Util
 import Util

+import Data.Word
+import Data.Bits

 
 import GHC.Exts                -- For `xori` 
 \end{code}
 
 import GHC.Exts                -- For `xori` 
 \end{code}

@@ -83,15 +95,16 @@ import GHC.Exts             -- For `xori`
 
 \begin{code}
 exprType :: CoreExpr -> Type
 
 \begin{code}
 exprType :: CoreExpr -> Type

-
-exprType (Var var)             = idType var
-exprType (Lit lit)             = literalType lit
-exprType (Let _ body)          = exprType body
-exprType (Case _ _ ty alts)     = ty
-exprType (Cast e co) 
-  = let (_, ty) = coercionKind co in ty
-exprType (Note other_note e)    = exprType e
-exprType (Lam binder expr)      = mkPiType binder (exprType expr)
+-- ^ Recover the type of a well-typed Core expression. Fails when
+-- applied to the actual 'CoreSyn.Type' expression as it cannot
+-- really be said to have a type
+exprType (Var var)          = idType var
+exprType (Lit lit)          = literalType lit
+exprType (Let _ body)       = exprType body
+exprType (Case _ _ ty _)     = ty
+exprType (Cast _ co)         = snd (coercionKind co)
+exprType (Note _ e)          = exprType e
+exprType (Lam binder expr)   = mkPiType binder (exprType expr)

 exprType e@(App _ _)
   = case collectArgs e of
        (fun, args) -> applyTypeToArgs e (exprType fun) args
 exprType e@(App _ _)
   = case collectArgs e of
        (fun, args) -> applyTypeToArgs e (exprType fun) args

@@ -99,35 +112,39 @@ exprType e@(App _ _)
 exprType other = pprTrace "exprType" (pprCoreExpr other) alphaTy
 
 coreAltType :: CoreAlt -> Type
 exprType other = pprTrace "exprType" (pprCoreExpr other) alphaTy
 
 coreAltType :: CoreAlt -> Type

+-- ^ Returns the type of the alternatives right hand side

 coreAltType (_,_,rhs) = exprType rhs
 coreAltType (_,_,rhs) = exprType rhs

-\end{code}

 
 

-@mkPiType@ makes a (->) type or a forall type, depending on whether
-it is given a type variable or a term variable.  We cleverly use the
-lbvarinfo field to figure out the right annotation for the arrove in
-case of a term variable.
+coreAltsType :: [CoreAlt] -> Type
+-- ^ Returns the type of the first alternative, which should be the same as for all alternatives
+coreAltsType (alt:_) = coreAltType alt
+coreAltsType []             = panic "corAltsType"
+\end{code}

 
 \begin{code}
 
 \begin{code}

-mkPiType  :: Var   -> Type -> Type     -- The more polymorphic version
-mkPiTypes :: [Var] -> Type -> Type     --    doesn't work...
-
-mkPiTypes vs ty = foldr mkPiType ty vs
+mkPiType  :: Var   -> Type -> Type
+-- ^ Makes a @(->)@ type or a forall type, depending
+-- on whether it is given a type variable or a term variable.
+mkPiTypes :: [Var] -> Type -> Type
+-- ^ 'mkPiType' for multiple type or value arguments

 
 mkPiType v ty
    | isId v    = mkFunTy (idType v) ty
    | otherwise = mkForAllTy v ty
 
 mkPiType v ty
    | isId v    = mkFunTy (idType v) ty
    | otherwise = mkForAllTy v ty

+
+mkPiTypes vs ty = foldr mkPiType ty vs

 \end{code}
 
 \begin{code}
 applyTypeToArg :: Type -> CoreExpr -> Type
 \end{code}
 
 \begin{code}
 applyTypeToArg :: Type -> CoreExpr -> Type

+-- ^ Determines the type resulting from applying an expression to a function with the given type

 applyTypeToArg fun_ty (Type arg_ty) = applyTy fun_ty arg_ty
 applyTypeToArg fun_ty (Type arg_ty) = applyTy fun_ty arg_ty

-applyTypeToArg fun_ty other_arg     = funResultTy fun_ty
+applyTypeToArg fun_ty _             = funResultTy fun_ty

 
 applyTypeToArgs :: CoreExpr -> Type -> [CoreExpr] -> Type
 
 applyTypeToArgs :: CoreExpr -> Type -> [CoreExpr] -> Type

--- A more efficient version of applyTypeToArg 
--- when we have several args
--- The first argument is just for debugging
-applyTypeToArgs e op_ty [] = op_ty
+-- ^ A more efficient version of 'applyTypeToArg' when we have several arguments.
+-- The first argument is just for debugging, and gives some context
+applyTypeToArgs _ op_ty [] = op_ty

 
 applyTypeToArgs e op_ty (Type ty : args)
   =    -- Accumulate type arguments so we can instantiate all at once
 
 applyTypeToArgs e op_ty (Type ty : args)
   =    -- Accumulate type arguments so we can instantiate all at once

@@ -136,15 +153,18 @@ applyTypeToArgs e op_ty (Type ty : args)
     go rev_tys (Type ty : args) = go (ty:rev_tys) args
     go rev_tys rest_args        = applyTypeToArgs e op_ty' rest_args
                                where
     go rev_tys (Type ty : args) = go (ty:rev_tys) args
     go rev_tys rest_args        = applyTypeToArgs e op_ty' rest_args
                                where

-                                 op_ty' = applyTys op_ty (reverse rev_tys)
+                                 op_ty' = applyTysD msg op_ty (reverse rev_tys)
+                                 msg = ptext (sLit "applyTypeToArgs") <+> 
+                                       panic_msg e op_ty

 
 

-applyTypeToArgs e op_ty (other_arg : args)
+applyTypeToArgs e op_ty (_ : args)

   = case (splitFunTy_maybe op_ty) of
        Just (_, res_ty) -> applyTypeToArgs e res_ty args
   = case (splitFunTy_maybe op_ty) of
        Just (_, res_ty) -> applyTypeToArgs e res_ty args

-       Nothing -> pprPanic "applyTypeToArgs" (pprCoreExpr e $$ ppr op_ty)
-\end{code}
-
+       Nothing -> pprPanic "applyTypeToArgs" (panic_msg e op_ty)

 
 

+panic_msg :: CoreExpr -> Type -> SDoc
+panic_msg e op_ty = pprCoreExpr e $$ ppr op_ty
+\end{code}

 
 %************************************************************************
 %*                                                                     *
 
 %************************************************************************
 %*                                                                     *

@@ -185,13 +205,20 @@ its rhs is trivial) and *then* we could get rid of the inline_me.
 But it hardly seems worth it, so I don't bother.
 
 \begin{code}
 But it hardly seems worth it, so I don't bother.
 
 \begin{code}

+-- | Wraps the given expression in an inlining hint unless the expression
+-- is trivial in some sense, so that doing so would usually hurt us
+mkInlineMe :: CoreExpr -> CoreExpr

 mkInlineMe (Var v) = Var v
 mkInlineMe e      = Note InlineMe e
 \end{code}
 
 mkInlineMe (Var v) = Var v
 mkInlineMe e      = Note InlineMe e
 \end{code}
 

-
-

 \begin{code}
 \begin{code}

+-- | Wrap the given expression in the coercion, dropping identity coercions and coalescing nested coercions
+mkCoerceI :: CoercionI -> CoreExpr -> CoreExpr
+mkCoerceI IdCo e = e
+mkCoerceI (ACo co) e = mkCoerce co e
+
+-- | Wrap the given expression in the coercion safely, coalescing nested coercions

 mkCoerce :: Coercion -> CoreExpr -> CoreExpr
 mkCoerce co (Cast expr co2)
   = ASSERT(let { (from_ty, _to_ty) = coercionKind co; 
 mkCoerce :: Coercion -> CoreExpr -> CoreExpr
 mkCoerce co (Cast expr co2)
   = ASSERT(let { (from_ty, _to_ty) = coercionKind co; 

@@ -200,7 +227,7 @@ mkCoerce co (Cast expr co2)
     mkCoerce (mkTransCoercion co2 co) expr
 
 mkCoerce co expr 
     mkCoerce (mkTransCoercion co2 co) expr
 
 mkCoerce co expr 

-  = let (from_ty, to_ty) = coercionKind co in
+  = let (from_ty, _to_ty) = coercionKind co in

 --    if to_ty `coreEqType` from_ty
 --    then expr
 --    else 
 --    if to_ty `coreEqType` from_ty
 --    then expr
 --    else 

@@ -209,10 +236,12 @@ mkCoerce co expr
 \end{code}
 
 \begin{code}
 \end{code}
 
 \begin{code}

+-- | Wraps the given expression in the cost centre unless
+-- in a way that maximises their utility to the user

 mkSCC :: CostCentre -> Expr b -> Expr b
        -- Note: Nested SCC's *are* preserved for the benefit of
        --       cost centre stack profiling
 mkSCC :: CostCentre -> Expr b -> Expr b
        -- Note: Nested SCC's *are* preserved for the benefit of
        --       cost centre stack profiling

-mkSCC cc (Lit lit)         = Lit lit
+mkSCC _  (Lit lit)          = Lit lit

 mkSCC cc (Lam x e)         = Lam x (mkSCC cc e)  -- Move _scc_ inside lambda
 mkSCC cc (Note (SCC cc') e) = Note (SCC cc) (Note (SCC cc') e)
 mkSCC cc (Note n e)        = Note n (mkSCC cc e) -- Move _scc_ inside notes
 mkSCC cc (Lam x e)         = Lam x (mkSCC cc e)  -- Move _scc_ inside lambda
 mkSCC cc (Note (SCC cc') e) = Note (SCC cc) (Note (SCC cc') e)
 mkSCC cc (Note n e)        = Note n (mkSCC cc e) -- Move _scc_ inside notes

@@ -229,20 +258,27 @@ mkSCC cc expr                 = Note (SCC cc) expr
 
 \begin{code}
 bindNonRec :: Id -> CoreExpr -> CoreExpr -> CoreExpr
 
 \begin{code}
 bindNonRec :: Id -> CoreExpr -> CoreExpr -> CoreExpr

--- (bindNonRec x r b) produces either
---     let x = r in b
--- or
---     case r of x { _DEFAULT_ -> b }
+-- ^ @bindNonRec x r b@ produces either:
+--
+-- > let x = r in b
+--
+-- or:

 --
 --

--- depending on whether x is unlifted or not
+-- > case r of x { _DEFAULT_ -> b }
+--
+-- depending on whether we have to use a @case@ or @let@
+-- binding for the expression (see 'needsCaseBinding').

 -- It's used by the desugarer to avoid building bindings
 -- It's used by the desugarer to avoid building bindings

--- that give Core Lint a heart attack.  Actually the simplifier
--- deals with them perfectly well.
-
+-- that give Core Lint a heart attack, although actually
+-- the simplifier deals with them perfectly well. See
+-- also 'MkCore.mkCoreLet'

 bindNonRec bndr rhs body 
 bindNonRec bndr rhs body 

-  | needsCaseBinding (idType bndr) rhs = Case rhs bndr (exprType body) [(DEFAULT,[],body)]
+  | needsCaseBinding (idType bndr) rhs = Case rhs bndr (exprType body) [(DEFAULT, [], body)]

   | otherwise                         = Let (NonRec bndr rhs) body
 
   | otherwise                         = Let (NonRec bndr rhs) body
 

+-- | Tests whether we have to use a @case@ rather than @let@ binding for this expression
+-- as per the invariants of 'CoreExpr': see "CoreSyn#let_app_invariant"
+needsCaseBinding :: Type -> CoreExpr -> Bool

 needsCaseBinding ty rhs = isUnLiftedType ty && not (exprOkForSpeculation rhs)
        -- Make a case expression instead of a let
        -- These can arise either from the desugarer,
 needsCaseBinding ty rhs = isUnLiftedType ty && not (exprOkForSpeculation rhs)
        -- Make a case expression instead of a let
        -- These can arise either from the desugarer,

@@ -250,20 +286,18 @@ needsCaseBinding ty rhs = isUnLiftedType ty && not (exprOkForSpeculation rhs)
 \end{code}
 
 \begin{code}
 \end{code}
 
 \begin{code}

-mkAltExpr :: AltCon -> [CoreBndr] -> [Type] -> CoreExpr
-       -- This guy constructs the value that the scrutinee must have
-       -- when you are in one particular branch of a case
+mkAltExpr :: AltCon     -- ^ Case alternative constructor
+          -> [CoreBndr] -- ^ Things bound by the pattern match
+          -> [Type]     -- ^ The type arguments to the case alternative
+          -> CoreExpr
+-- ^ This guy constructs the value that the scrutinee must have
+-- given that you are in one particular branch of a case

 mkAltExpr (DataAlt con) args inst_tys
   = mkConApp con (map Type inst_tys ++ varsToCoreExprs args)
 mkAltExpr (LitAlt lit) [] []
   = Lit lit
 mkAltExpr (DataAlt con) args inst_tys
   = mkConApp con (map Type inst_tys ++ varsToCoreExprs args)
 mkAltExpr (LitAlt lit) [] []
   = Lit lit

-
-mkIfThenElse :: CoreExpr -> CoreExpr -> CoreExpr -> CoreExpr
-mkIfThenElse guard then_expr else_expr
--- Not going to be refining, so okay to take the type of the "then" clause
-  = Case guard (mkWildId boolTy) (exprType then_expr) 
-        [ (DataAlt falseDataCon, [], else_expr),       -- Increasing order of tag!
-          (DataAlt trueDataCon,  [], then_expr) ]
+mkAltExpr (LitAlt _) _ _ = panic "mkAltExpr LitAlt"
+mkAltExpr DEFAULT _ _ = panic "mkAltExpr DEFAULT"

 \end{code}
 
 
 \end{code}
 
 

@@ -277,15 +311,18 @@ The default alternative must be first, if it exists at all.
 This makes it easy to find, though it makes matching marginally harder.
 
 \begin{code}
 This makes it easy to find, though it makes matching marginally harder.
 
 \begin{code}

+-- | Extract the default case alternative

 findDefault :: [CoreAlt] -> ([CoreAlt], Maybe CoreExpr)
 findDefault ((DEFAULT,args,rhs) : alts) = ASSERT( null args ) (alts, Just rhs)
 findDefault alts                       =                     (alts, Nothing)
 
 findDefault :: [CoreAlt] -> ([CoreAlt], Maybe CoreExpr)
 findDefault ((DEFAULT,args,rhs) : alts) = ASSERT( null args ) (alts, Just rhs)
 findDefault alts                       =                     (alts, Nothing)
 

+-- | Find the case alternative corresponding to a particular 
+-- constructor: panics if no such constructor exists

 findAlt :: AltCon -> [CoreAlt] -> CoreAlt
 findAlt con alts
   = case alts of
        (deflt@(DEFAULT,_,_):alts) -> go alts deflt
 findAlt :: AltCon -> [CoreAlt] -> CoreAlt
 findAlt con alts
   = case alts of
        (deflt@(DEFAULT,_,_):alts) -> go alts deflt

-       other                      -> go alts panic_deflt
+        _                          -> go alts panic_deflt

   where
     panic_deflt = pprPanic "Missing alternative" (ppr con $$ vcat (map ppr alts))
 
   where
     panic_deflt = pprPanic "Missing alternative" (ppr con $$ vcat (map ppr alts))
 

@@ -298,12 +335,12 @@ findAlt con alts
 
 isDefaultAlt :: CoreAlt -> Bool
 isDefaultAlt (DEFAULT, _, _) = True
 
 isDefaultAlt :: CoreAlt -> Bool
 isDefaultAlt (DEFAULT, _, _) = True

-isDefaultAlt other          = False
+isDefaultAlt _               = False

 
 ---------------------------------
 mergeAlts :: [CoreAlt] -> [CoreAlt] -> [CoreAlt]
 
 ---------------------------------
 mergeAlts :: [CoreAlt] -> [CoreAlt] -> [CoreAlt]

--- Merge preserving order; alternatives in the first arg
--- shadow ones in the second
+-- ^ Merge alternatives preserving order; alternatives in
+-- the first argument shadow ones in the second

 mergeAlts [] as2 = as2
 mergeAlts as1 [] = as1
 mergeAlts (a1:as1) (a2:as2)
 mergeAlts [] as2 = as2
 mergeAlts as1 [] = as1
 mergeAlts (a1:as1) (a2:as2)

@@ -311,6 +348,21 @@ mergeAlts (a1:as1) (a2:as2)
        LT -> a1 : mergeAlts as1      (a2:as2)
        EQ -> a1 : mergeAlts as1      as2       -- Discard a2
        GT -> a2 : mergeAlts (a1:as1) as2
        LT -> a1 : mergeAlts as1      (a2:as2)
        EQ -> a1 : mergeAlts as1      as2       -- Discard a2
        GT -> a2 : mergeAlts (a1:as1) as2

+
+
+---------------------------------
+trimConArgs :: AltCon -> [CoreArg] -> [CoreArg]
+-- ^ Given:
+--
+-- > case (C a b x y) of
+-- >        C b x y -> ...
+--
+-- We want to drop the leading type argument of the scrutinee
+-- leaving the arguments to match agains the pattern
+
+trimConArgs DEFAULT      args = ASSERT( null args ) []
+trimConArgs (LitAlt _)   args = ASSERT( null args ) []
+trimConArgs (DataAlt dc) args = dropList (dataConUnivTyVars dc) args

 \end{code}
 
 
 \end{code}
 
 

@@ -325,14 +377,11 @@ mergeAlts (a1:as1) (a2:as2)
                applications.  Note that primop Ids aren't considered
                trivial unless 
 
                applications.  Note that primop Ids aren't considered
                trivial unless 
 

-@exprIsBottom@ is true of expressions that are guaranteed to diverge
-
-

 There used to be a gruesome test for (hasNoBinding v) in the
 Var case:
        exprIsTrivial (Var v) | hasNoBinding v = idArity v == 0
 There used to be a gruesome test for (hasNoBinding v) in the
 Var case:
        exprIsTrivial (Var v) | hasNoBinding v = idArity v == 0

-The idea here is that a constructor worker, like $wJust, is
-really short for (\x -> $wJust x), becuase $wJust has no binding.
+The idea here is that a constructor worker, like \$wJust, is
+really short for (\x -> \$wJust x), becuase \$wJust has no binding.

 So it should be treated like a lambda.  Ditto unsaturated primops.
 But now constructor workers are not "have-no-binding" Ids.  And
 completely un-applied primops and foreign-call Ids are sufficiently
 So it should be treated like a lambda.  Ditto unsaturated primops.
 But now constructor workers are not "have-no-binding" Ids.  And
 completely un-applied primops and foreign-call Ids are sufficiently

@@ -345,15 +394,16 @@ SCC notes.  We do not treat (_scc_ "foo" x) as trivial, because
   b) see the note [SCC-and-exprIsTrivial] in Simplify.simplLazyBind
 
 \begin{code}
   b) see the note [SCC-and-exprIsTrivial] in Simplify.simplLazyBind
 
 \begin{code}

-exprIsTrivial (Var v)     = True       -- See notes above
-exprIsTrivial (Type _)    = True
-exprIsTrivial (Lit lit)    = litIsTrivial lit
-exprIsTrivial (App e arg)  = not (isRuntimeArg arg) && exprIsTrivial e
-exprIsTrivial (Note (SCC _) e) = False         -- See notes above
+exprIsTrivial :: CoreExpr -> Bool
+exprIsTrivial (Var _)          = True        -- See notes above
+exprIsTrivial (Type _)         = True
+exprIsTrivial (Lit lit)        = litIsTrivial lit
+exprIsTrivial (App e arg)      = not (isRuntimeArg arg) && exprIsTrivial e
+exprIsTrivial (Note (SCC _) _) = False       -- See notes above

 exprIsTrivial (Note _       e) = exprIsTrivial e
 exprIsTrivial (Note _       e) = exprIsTrivial e

-exprIsTrivial (Cast e co)  = exprIsTrivial e
-exprIsTrivial (Lam b body) = not (isRuntimeVar b) && exprIsTrivial body
-exprIsTrivial other       = False
+exprIsTrivial (Cast e _)       = exprIsTrivial e
+exprIsTrivial (Lam b body)     = not (isRuntimeVar b) && exprIsTrivial body
+exprIsTrivial _                = False

 \end{code}
 
 
 \end{code}
 
 

@@ -369,20 +419,21 @@ exprIsTrivial other          = False
 
 
 \begin{code}
 
 
 \begin{code}

-exprIsDupable (Type _)         = True
-exprIsDupable (Var v)          = True
-exprIsDupable (Lit lit)        = litIsDupable lit
-exprIsDupable (Note InlineMe e) = True
+exprIsDupable :: CoreExpr -> Bool
+exprIsDupable (Type _)          = True
+exprIsDupable (Var _)           = True
+exprIsDupable (Lit lit)         = litIsDupable lit
+exprIsDupable (Note InlineMe _) = True

 exprIsDupable (Note _ e)        = exprIsDupable e
 exprIsDupable (Note _ e)        = exprIsDupable e

-exprIsDupable (Cast e co)       = exprIsDupable e
-exprIsDupable expr          
+exprIsDupable (Cast e _)        = exprIsDupable e
+exprIsDupable expr

   = go expr 0
   where
   = go expr 0
   where

-    go (Var v)   n_args = True
+    go (Var _)   _      = True

     go (App f a) n_args =  n_args < dupAppSize
                        && exprIsDupable a
                        && go f (n_args+1)
     go (App f a) n_args =  n_args < dupAppSize
                        && exprIsDupable a
                        && go f (n_args+1)

-    go other n_args    = False
+    go _         _      = False

 
 dupAppSize :: Int
 dupAppSize = 4         -- Size of application we are prepared to duplicate
 
 dupAppSize :: Int
 dupAppSize = 4         -- Size of application we are prepared to duplicate

@@ -418,12 +469,12 @@ because sharing will make sure it is only evaluated once.
 
 \begin{code}
 exprIsCheap :: CoreExpr -> Bool
 
 \begin{code}
 exprIsCheap :: CoreExpr -> Bool

-exprIsCheap (Lit lit)        = True
+exprIsCheap (Lit _)           = True

 exprIsCheap (Type _)          = True
 exprIsCheap (Var _)           = True
 exprIsCheap (Type _)          = True
 exprIsCheap (Var _)           = True

-exprIsCheap (Note InlineMe e) = True
+exprIsCheap (Note InlineMe _) = True

 exprIsCheap (Note _ e)        = exprIsCheap e
 exprIsCheap (Note _ e)        = exprIsCheap e

-exprIsCheap (Cast e co)       = exprIsCheap e
+exprIsCheap (Cast e _)        = exprIsCheap e

 exprIsCheap (Lam x e)         = isRuntimeVar x || exprIsCheap e
 exprIsCheap (Case e _ _ alts) = exprIsCheap e && 
                                and [exprIsCheap rhs | (_,_,rhs) <- alts]
 exprIsCheap (Lam x e)         = isRuntimeVar x || exprIsCheap e
 exprIsCheap (Case e _ _ alts) = exprIsCheap e && 
                                and [exprIsCheap rhs | (_,_,rhs) <- alts]

@@ -444,7 +495,7 @@ exprIsCheap other_expr      -- Applications and variables
     go (App f a) val_args | isRuntimeArg a = go f (a:val_args)
                          | otherwise      = go f val_args
 
     go (App f a) val_args | isRuntimeArg a = go f (a:val_args)
                          | otherwise      = go f val_args
 

-    go (Var f) [] = True       -- Just a type application of a variable
+    go (Var _) [] = True       -- Just a type application of a variable

                                -- (f t1 t2 t3) counts as WHNF
     go (Var f) args
        = case globalIdDetails f of
                                -- (f t1 t2 t3) counts as WHNF
     go (Var f) args
        = case globalIdDetails f of

@@ -453,14 +504,14 @@ exprIsCheap other_expr    -- Applications and variables
                PrimOpId op    -> go_primop op args
 
                DataConWorkId _ -> go_pap args
                PrimOpId op    -> go_primop op args
 
                DataConWorkId _ -> go_pap args

-               other | length args < idArity f -> go_pap args
+               _ | length args < idArity f -> go_pap args

 
 

-               other -> isBottomingId f
+               _ -> isBottomingId f

                        -- Application of a function which
                        -- always gives bottom; we treat this as cheap
                        -- because it certainly doesn't need to be shared!
        
                        -- Application of a function which
                        -- always gives bottom; we treat this as cheap
                        -- because it certainly doesn't need to be shared!
        

-    go other args = False
+    go _ _ = False

  
     --------------
     go_pap args = all exprIsTrivial args
  
     --------------
     go_pap args = all exprIsTrivial args

@@ -478,54 +529,60 @@ exprIsCheap other_expr    -- Applications and variables
  
     --------------
     go_sel [arg] = exprIsCheap arg     -- I'm experimenting with making record selection
  
     --------------
     go_sel [arg] = exprIsCheap arg     -- I'm experimenting with making record selection

-    go_sel other = False               -- look cheap, so we will substitute it inside a
+    go_sel _     = False               -- look cheap, so we will substitute it inside a

                                        -- lambda.  Particularly for dictionary field selection.
                -- BUT: Take care with (sel d x)!  The (sel d) might be cheap, but
                --      there's no guarantee that (sel d x) will be too.  Hence (n_val_args == 1)
 \end{code}
 
                                        -- lambda.  Particularly for dictionary field selection.
                -- BUT: Take care with (sel d x)!  The (sel d) might be cheap, but
                --      there's no guarantee that (sel d x) will be too.  Hence (n_val_args == 1)
 \end{code}
 

-exprOkForSpeculation returns True of an expression that it is
-
-       * safe to evaluate even if normal order eval might not 
-         evaluate the expression at all, or
-
-       * safe *not* to evaluate even if normal order would do so
-
-It returns True iff
-
-       the expression guarantees to terminate, 
-       soon, 
-       without raising an exception,
-       without causing a side effect (e.g. writing a mutable variable)
-
-NB: if exprIsHNF e, then exprOkForSpecuation e
-
-E.G.
-       let x = case y# +# 1# of { r# -> I# r# }
-       in E
-==>
-       case y# +# 1# of { r# -> 
-       let x = I# r#
-       in E 
-       }
-
-We can only do this if the (y+1) is ok for speculation: it has no
-side effects, and can't diverge or raise an exception.
-

 \begin{code}
 \begin{code}

+-- | 'exprOkForSpeculation' returns True of an expression that is:
+--
+--  * Safe to evaluate even if normal order eval might not 
+--    evaluate the expression at all, or
+--
+--  * Safe /not/ to evaluate even if normal order would do so
+--
+-- Precisely, it returns @True@ iff:
+--
+--  * The expression guarantees to terminate, 
+--
+--  * soon, 
+--
+--  * without raising an exception,
+--
+--  * without causing a side effect (e.g. writing a mutable variable)
+--
+-- Note that if @exprIsHNF e@, then @exprOkForSpecuation e@.
+-- As an example of the considerations in this test, consider:
+--
+-- > let x = case y# +# 1# of { r# -> I# r# }
+-- > in E
+--
+-- being translated to:
+--
+-- > case y# +# 1# of { r# -> 
+-- >    let x = I# r#
+-- >    in E 
+-- > }
+-- 
+-- We can only do this if the @y + 1@ is ok for speculation: it has no
+-- side effects, and can't diverge or raise an exception.

 exprOkForSpeculation :: CoreExpr -> Bool
 exprOkForSpeculation (Lit _)     = True
 exprOkForSpeculation (Type _)    = True
 exprOkForSpeculation :: CoreExpr -> Bool
 exprOkForSpeculation (Lit _)     = True
 exprOkForSpeculation (Type _)    = True

+    -- Tick boxes are *not* suitable for speculation

 exprOkForSpeculation (Var v)     = isUnLiftedType (idType v)
 exprOkForSpeculation (Var v)     = isUnLiftedType (idType v)

+                                && not (isTickBoxOp v)

 exprOkForSpeculation (Note _ e)  = exprOkForSpeculation e
 exprOkForSpeculation (Note _ e)  = exprOkForSpeculation e

-exprOkForSpeculation (Cast e co) = exprOkForSpeculation e
+exprOkForSpeculation (Cast e _)  = exprOkForSpeculation e

 exprOkForSpeculation other_expr
   = case collectArgs other_expr of
        (Var f, args) -> spec_ok (globalIdDetails f) args
 exprOkForSpeculation other_expr
   = case collectArgs other_expr of
        (Var f, args) -> spec_ok (globalIdDetails f) args

-       other         -> False
+        _             -> False

  
   where
  
   where

-    spec_ok (DataConWorkId _) args
+    spec_ok (DataConWorkId _) _

       = True   -- The strictness of the constructor has already
                -- been expressed by its "wrapper", so we don't need
                -- to take the arguments into account
       = True   -- The strictness of the constructor has already
                -- been expressed by its "wrapper", so we don't need
                -- to take the arguments into account

@@ -543,11 +600,10 @@ exprOkForSpeculation other_expr
                                -- A bit conservative: we don't really need
                                -- to care about lazy arguments, but this is easy
 
                                -- A bit conservative: we don't really need
                                -- to care about lazy arguments, but this is easy
 

-    spec_ok other args = False
+    spec_ok _ _ = False

 
 

+-- | True of dyadic operators that can fail only if the second arg is zero!

 isDivOp :: PrimOp -> Bool
 isDivOp :: PrimOp -> Bool

--- True of dyadic operators that can fail 
--- only if the second arg is zero

 -- This function probably belongs in PrimOp, or even in 
 -- an automagically generated file.. but it's such a 
 -- special case I thought I'd leave it here for now.
 -- This function probably belongs in PrimOp, or even in 
 -- an automagically generated file.. but it's such a 
 -- special case I thought I'd leave it here for now.

@@ -559,53 +615,59 @@ isDivOp IntegerQuotRemOp = True
 isDivOp IntegerDivModOp  = True
 isDivOp FloatDivOp       = True
 isDivOp DoubleDivOp      = True
 isDivOp IntegerDivModOp  = True
 isDivOp FloatDivOp       = True
 isDivOp DoubleDivOp      = True

-isDivOp other           = False
+isDivOp _                = False

 \end{code}
 
 \end{code}
 

-

 \begin{code}
 \begin{code}

-exprIsBottom :: CoreExpr -> Bool       -- True => definitely bottom
+-- | True of expressions that are guaranteed to diverge upon execution
+exprIsBottom :: CoreExpr -> Bool

 exprIsBottom e = go 0 e
 exprIsBottom e = go 0 e

-              where
-               -- n is the number of args
-                go n (Note _ e)     = go n e
-                 go n (Cast e co)    = go n e
-                go n (Let _ e)      = go n e
-                go n (Case e _ _ _) = go 0 e   -- Just check the scrut
-                go n (App e _)      = go (n+1) e
-                go n (Var v)        = idAppIsBottom v n
-                go n (Lit _)        = False
-                go n (Lam _ _)      = False
-                go n (Type _)       = False
+               where
+                -- n is the number of args
+                 go n (Note _ e)     = go n e
+                 go n (Cast e _)     = go n e
+                 go n (Let _ e)      = go n e
+                 go _ (Case e _ _ _) = go 0 e   -- Just check the scrut
+                 go n (App e _)      = go (n+1) e
+                 go n (Var v)        = idAppIsBottom v n
+                 go _ (Lit _)        = False
+                 go _ (Lam _ _)      = False
+                 go _ (Type _)       = False

 
 idAppIsBottom :: Id -> Int -> Bool
 idAppIsBottom id n_val_args = appIsBottom (idNewStrictness id) n_val_args
 \end{code}
 
 
 idAppIsBottom :: Id -> Int -> Bool
 idAppIsBottom id n_val_args = appIsBottom (idNewStrictness id) n_val_args
 \end{code}
 

-@exprIsHNF@ returns true for expressions that are certainly *already* 
-evaluated to *head* normal form.  This is used to decide whether it's ok 
-to change
-
-       case x of _ -> e   ===>   e
-
-and to decide whether it's safe to discard a `seq`
-
-So, it does *not* treat variables as evaluated, unless they say they are.
-
-But it *does* treat partial applications and constructor applications
-as values, even if their arguments are non-trivial, provided the argument
-type is lifted; 
-       e.g.  (:) (f x) (map f xs)      is a value
-             map (...redex...)         is a value
-Because `seq` on such things completes immediately
-
-For unlifted argument types, we have to be careful:
-               C (f x :: Int#)
-Suppose (f x) diverges; then C (f x) is not a value.  True, but
-this form is illegal (see the invariants in CoreSyn).  Args of unboxed
-type must be ok-for-speculation (or trivial).
-

 \begin{code}
 \begin{code}

+
+-- | This returns true for expressions that are certainly /already/ 
+-- evaluated to /head/ normal form.  This is used to decide whether it's ok 
+-- to change:
+--
+-- > case x of _ -> e
+--
+-- into:
+--
+-- > e
+--
+-- and to decide whether it's safe to discard a 'seq'.
+-- So, it does /not/ treat variables as evaluated, unless they say they are.
+-- However, it /does/ treat partial applications and constructor applications
+-- as values, even if their arguments are non-trivial, provided the argument
+-- type is lifted. For example, both of these are values:
+--
+-- > (:) (f x) (map f xs)
+-- > map (...redex...)
+--
+-- Because 'seq' on such things completes immediately.
+--
+-- For unlifted argument types, we have to be careful:
+--
+-- > C (f x :: Int#)
+--
+-- Suppose @f x@ diverges; then @C (f x)@ is not a value. However this can't 
+-- happen: see "CoreSyn#let_app_invariant". This invariant states that arguments of
+-- unboxed type must be ok-for-speculation (or trivial).

 exprIsHNF :: CoreExpr -> Bool          -- True => Value-lambda, constructor, PAP
 exprIsHNF (Var v)      -- NB: There are no value args at this point
   =  isDataConWorkId v         -- Catches nullary constructors, 
 exprIsHNF :: CoreExpr -> Bool          -- True => Value-lambda, constructor, PAP
 exprIsHNF (Var v)      -- NB: There are no value args at this point
   =  isDataConWorkId v         -- Catches nullary constructors, 

@@ -616,47 +678,38 @@ exprIsHNF (Var v)         -- NB: There are no value args at this point
        -- A worry: what if an Id's unfolding is just itself: 
        -- then we could get an infinite loop...
 
        -- A worry: what if an Id's unfolding is just itself: 
        -- then we could get an infinite loop...
 

-exprIsHNF (Lit l)         = True
-exprIsHNF (Type ty)       = True       -- Types are honorary Values; 
-                                       -- we don't mind copying them
-exprIsHNF (Lam b e)       = isRuntimeVar b || exprIsHNF e
-exprIsHNF (Note (TickBox {}) _)
-                          = False
-exprIsHNF (Note (BinaryTickBox {}) _)
-                          = False
-exprIsHNF (Note _ e)      = exprIsHNF e
-exprIsHNF (Cast e co)      = exprIsHNF e
+exprIsHNF (Lit _)          = True
+exprIsHNF (Type _)         = True       -- Types are honorary Values;
+                                        -- we don't mind copying them
+exprIsHNF (Lam b e)        = isRuntimeVar b || exprIsHNF e
+exprIsHNF (Note _ e)       = exprIsHNF e
+exprIsHNF (Cast e _)       = exprIsHNF e

 exprIsHNF (App e (Type _)) = exprIsHNF e
 exprIsHNF (App e a)        = app_is_value e [a]
 exprIsHNF (App e (Type _)) = exprIsHNF e
 exprIsHNF (App e a)        = app_is_value e [a]

-exprIsHNF other                   = False
+exprIsHNF _                = False

 
 -- There is at least one value argument
 
 -- There is at least one value argument

+app_is_value :: CoreExpr -> [CoreArg] -> Bool

 app_is_value (Var fun) args
 app_is_value (Var fun) args

-  |  isDataConWorkId fun               -- Constructor apps are values
-  || idArity fun > valArgCount args    -- Under-applied function
-  = check_args (idType fun) args
-app_is_value (App f a) as = app_is_value f (a:as)
-app_is_value other     as = False
-
-       -- 'check_args' checks that unlifted-type args
-       -- are in fact guaranteed non-divergent
-check_args fun_ty []             = True
-check_args fun_ty (Type _ : args) = case splitForAllTy_maybe fun_ty of
-                                     Just (_, ty) -> check_args ty args
-check_args fun_ty (arg : args)
-  | isUnLiftedType arg_ty = exprOkForSpeculation arg
-  | otherwise            = check_args res_ty args
-  where
-    (arg_ty, res_ty) = splitFunTy fun_ty
+  = idArity fun > valArgCount args     -- Under-applied function
+    ||  isDataConWorkId fun            --  or data constructor
+app_is_value (Note _ f) as = app_is_value f as
+app_is_value (Cast f _) as = app_is_value f as
+app_is_value (App f a)  as = app_is_value f (a:as)
+app_is_value _          _  = False

 \end{code}
 
 \end{code}
 

+These InstPat functions go here to avoid circularity between DataCon and Id
+

 \begin{code}
 \begin{code}

--- These InstPat functions go here to avoid circularity between DataCon and Id
-dataConRepInstPat   = dataConInstPat dataConRepArgTys (repeat (FSLIT("ipv")))
+dataConRepInstPat, dataConOrigInstPat :: [Unique] -> DataCon -> [Type] -> ([TyVar], [CoVar], [Id])
+dataConRepFSInstPat :: [FastString] -> [Unique] -> DataCon -> [Type] -> ([TyVar], [CoVar], [Id])
+
+dataConRepInstPat   = dataConInstPat dataConRepArgTys (repeat ((fsLit "ipv")))

 dataConRepFSInstPat = dataConInstPat dataConRepArgTys
 dataConRepFSInstPat = dataConInstPat dataConRepArgTys

-dataConOrigInstPat  = dataConInstPat dc_arg_tys       (repeat (FSLIT("ipv")))
+dataConOrigInstPat  = dataConInstPat dc_arg_tys       (repeat ((fsLit "ipv")))

   where 
   where 

-    dc_arg_tys dc = map mkPredTy (dataConTheta dc) ++ dataConOrigArgTys dc
+    dc_arg_tys dc = map mkPredTy (dataConEqTheta dc) ++ map mkPredTy (dataConDictTheta dc) ++ dataConOrigArgTys dc

        -- Remember to include the existential dictionaries
 
 dataConInstPat :: (DataCon -> [Type])      -- function used to find arg tys
        -- Remember to include the existential dictionaries
 
 dataConInstPat :: (DataCon -> [Type])      -- function used to find arg tys

@@ -672,9 +725,13 @@ dataConInstPat :: (DataCon -> [Type])      -- function used to find arg tys
 --
 --   co_tvs are intended to be used as binders for coercion args and the kinds
 --     of these vars have been instantiated by the inst_tys and the ex_tys
 --
 --   co_tvs are intended to be used as binders for coercion args and the kinds
 --     of these vars have been instantiated by the inst_tys and the ex_tys

+--     The co_tvs include both GADT equalities (dcEqSpec) and 
+--     programmer-specified equalities (dcEqTheta)

 --
 --

---   arg_ids are indended to be used as binders for value arguments, including
---     dicts, and their types have been instantiated with inst_tys and ex_tys
+--   arg_ids are indended to be used as binders for value arguments, 
+--     and their types have been instantiated with inst_tys and ex_tys
+--     The arg_ids include both dicts (dcDictTheta) and
+--     programmer-specified arguments (after rep-ing) (deRepArgTys)

 --
 -- Example.
 --  The following constructor T1
 --
 -- Example.
 --  The following constructor T1

@@ -684,26 +741,27 @@ dataConInstPat :: (DataCon -> [Type])      -- function used to find arg tys
 --    ...
 --
 --  has representation type 
 --    ...
 --
 --  has representation type 

---   forall a. forall a1. forall b. (a :=: (a1,b)) => 
+--   forall a. forall a1. forall b. (a ~ (a1,b)) => 

 --     Int -> b -> T a
 --
 --  dataConInstPat fss us T1 (a1',b') will return
 --
 --     Int -> b -> T a
 --
 --  dataConInstPat fss us T1 (a1',b') will return
 --

---  ([a1'', b''], [c :: (a1', b'):=:(a1'', b'')], [x :: Int, y :: b''])
+--  ([a1'', b''], [c :: (a1', b')~(a1'', b'')], [x :: Int, y :: b''])

 --
 --  where the double-primed variables are created with the FastStrings and
 --  Uniques given as fss and us
 dataConInstPat arg_fun fss uniqs con inst_tys 
 --
 --  where the double-primed variables are created with the FastStrings and
 --  Uniques given as fss and us
 dataConInstPat arg_fun fss uniqs con inst_tys 

-  = (ex_bndrs, co_bndrs, id_bndrs)
+  = (ex_bndrs, co_bndrs, arg_ids)

   where 
     univ_tvs = dataConUnivTyVars con
     ex_tvs   = dataConExTyVars con
     arg_tys  = arg_fun con
     eq_spec  = dataConEqSpec con
   where 
     univ_tvs = dataConUnivTyVars con
     ex_tvs   = dataConExTyVars con
     arg_tys  = arg_fun con
     eq_spec  = dataConEqSpec con

-    eq_preds = eqSpecPreds eq_spec
+    eq_theta = dataConEqTheta con
+    eq_preds = eqSpecPreds eq_spec ++ eq_theta

 
     n_ex = length ex_tvs
 
     n_ex = length ex_tvs

-    n_co = length eq_spec
+    n_co = length eq_preds

 
       -- split the Uniques and FastStrings
     (ex_uniqs, uniqs')   = splitAt n_ex uniqs
 
       -- split the Uniques and FastStrings
     (ex_uniqs, uniqs')   = splitAt n_ex uniqs

@@ -730,21 +788,21 @@ dataConInstPat arg_fun fss uniqs con inst_tys
          co_kind  = substTy subst (mkPredTy eq_pred)
 
       -- make value vars, instantiating types
          co_kind  = substTy subst (mkPredTy eq_pred)
 
       -- make value vars, instantiating types

-    mk_id_var uniq fs ty = mkUserLocal (mkVarOccFS fs) uniq (substTy subst ty) noSrcLoc
-    id_bndrs = zipWith3 mk_id_var id_uniqs id_fss arg_tys
+    mk_id_var uniq fs ty = mkUserLocal (mkVarOccFS fs) uniq (substTy subst ty) noSrcSpan
+    arg_ids = zipWith3 mk_id_var id_uniqs id_fss arg_tys

 
 

+-- | Returns @Just (dc, [x1..xn])@ if the argument expression is 
+-- a constructor application of the form @dc x1 .. xn@

 exprIsConApp_maybe :: CoreExpr -> Maybe (DataCon, [CoreExpr])
 exprIsConApp_maybe :: CoreExpr -> Maybe (DataCon, [CoreExpr])

--- Returns (Just (dc, [x1..xn])) if the argument expression is 
--- a constructor application of the form (dc x1 .. xn)

 exprIsConApp_maybe (Cast expr co)
 exprIsConApp_maybe (Cast expr co)

-  =     -- Here we do the PushC reduction rule as described in the FC paper
+  =     -- Here we do the KPush reduction rule as described in the FC paper

     case exprIsConApp_maybe expr of {
        Nothing            -> Nothing ;
        Just (dc, dc_args) -> 
 
        -- The transformation applies iff we have
        --      (C e1 ... en) `cast` co
     case exprIsConApp_maybe expr of {
        Nothing            -> Nothing ;
        Just (dc, dc_args) -> 
 
        -- The transformation applies iff we have
        --      (C e1 ... en) `cast` co

-       -- where co :: (T t1 .. tn) :=: (T s1 ..sn)
+       -- where co :: (T t1 .. tn) ~ (T s1 ..sn)

        -- That is, with a T at the top of both sides
        -- The left-hand one must be a T, because exprIsConApp returned True
        -- but the right-hand one might not be.  (Though it usually will.)
        -- That is, with a T at the top of both sides
        -- The left-hand one must be a T, because exprIsConApp returned True
        -- but the right-hand one might not be.  (Though it usually will.)

@@ -767,17 +825,20 @@ exprIsConApp_maybe (Cast expr co)
     let
        tc_arity = tyConArity from_tc
 
     let
        tc_arity = tyConArity from_tc
 

-        (univ_args, rest1)  = splitAt tc_arity dc_args
-        (ex_args, rest2)    = splitAt n_ex_tvs rest1
-       (co_args, val_args) = splitAt n_cos rest2
+        (univ_args, rest1)        = splitAt tc_arity dc_args
+        (ex_args, rest2)          = splitAt n_ex_tvs rest1
+       (co_args_spec, rest3)     = splitAt n_cos_spec rest2
+       (co_args_theta, val_args) = splitAt n_cos_theta rest3

 
         arg_tys            = dataConRepArgTys dc
        dc_univ_tyvars      = dataConUnivTyVars dc
         dc_ex_tyvars        = dataConExTyVars dc
        dc_eq_spec          = dataConEqSpec dc
 
         arg_tys            = dataConRepArgTys dc
        dc_univ_tyvars      = dataConUnivTyVars dc
         dc_ex_tyvars        = dataConExTyVars dc
        dc_eq_spec          = dataConEqSpec dc

+        dc_eq_theta         = dataConEqTheta dc

         dc_tyvars           = dc_univ_tyvars ++ dc_ex_tyvars
         n_ex_tvs            = length dc_ex_tyvars
         dc_tyvars           = dc_univ_tyvars ++ dc_ex_tyvars
         n_ex_tvs            = length dc_ex_tyvars

-       n_cos               = length dc_eq_spec
+       n_cos_spec          = length dc_eq_spec
+       n_cos_theta         = length dc_eq_theta

 
        -- Make the "theta" from Fig 3 of the paper
         gammas              = decomposeCo tc_arity co
 
        -- Make the "theta" from Fig 3 of the paper
         gammas              = decomposeCo tc_arity co

@@ -785,10 +846,15 @@ exprIsConApp_maybe (Cast expr co)
         theta               = zipOpenTvSubst dc_tyvars new_tys
 
           -- First we cast the existential coercion arguments
         theta               = zipOpenTvSubst dc_tyvars new_tys
 
           -- First we cast the existential coercion arguments

-        cast_co (tv,ty) (Type co) = Type $ mkSymCoercion (substTyVar theta tv)
-                                          `mkTransCoercion` co
-                                          `mkTransCoercion` (substTy theta ty)
-        new_co_args = zipWith cast_co dc_eq_spec co_args
+        cast_co_spec (tv, ty) co 
+          = cast_co_theta (mkEqPred (mkTyVarTy tv, ty)) co
+        cast_co_theta eqPred (Type co) 
+          | (ty1, ty2) <- getEqPredTys eqPred
+          = Type $ mkSymCoercion (substTy theta ty1)
+                  `mkTransCoercion` co
+                  `mkTransCoercion` (substTy theta ty2)
+        new_co_args = zipWith cast_co_spec  dc_eq_spec  co_args_spec ++
+                      zipWith cast_co_theta dc_eq_theta co_args_theta

   
           -- ...and now value arguments
        new_val_args = zipWith cast_arg arg_tys val_args
   
           -- ...and now value arguments
        new_val_args = zipWith cast_arg arg_tys val_args

@@ -804,6 +870,7 @@ exprIsConApp_maybe (Cast expr co)
     Just (dc, map Type to_tc_arg_tys ++ ex_args ++ new_co_args ++ new_val_args)
     }}
 
     Just (dc, map Type to_tc_arg_tys ++ ex_args ++ new_co_args ++ new_val_args)
     }}
 

+{-

 -- We do not want to tell the world that we have a
 -- Cons, to *stop* Case of Known Cons, which removes
 -- the TickBox.
 -- We do not want to tell the world that we have a
 -- Cons, to *stop* Case of Known Cons, which removes
 -- the TickBox.

@@ -811,6 +878,7 @@ exprIsConApp_maybe (Note (TickBox {}) expr)
   = Nothing
 exprIsConApp_maybe (Note (BinaryTickBox {}) expr)
   = Nothing
   = Nothing
 exprIsConApp_maybe (Note (BinaryTickBox {}) expr)
   = Nothing

+-}

 
 exprIsConApp_maybe (Note _ expr)
   = exprIsConApp_maybe expr
 
 exprIsConApp_maybe (Note _ expr)
   = exprIsConApp_maybe expr

@@ -840,7 +908,7 @@ exprIsConApp_maybe expr = analyse (collectArgs expr)
          isCheapUnfolding unf
        = exprIsConApp_maybe (unfoldingTemplate unf)
 
          isCheapUnfolding unf
        = exprIsConApp_maybe (unfoldingTemplate unf)
 

-    analyse other = Nothing
+    analyse _ = Nothing

 \end{code}
 
 
 \end{code}
 
 

@@ -852,10 +920,10 @@ exprIsConApp_maybe expr = analyse (collectArgs expr)
 %************************************************************************
 
 \begin{code}
 %************************************************************************
 
 \begin{code}

+-- ^ The Arity returned is the number of value args the 
+-- expression can be applied to without doing much work

 exprEtaExpandArity :: DynFlags -> CoreExpr -> Arity
 exprEtaExpandArity :: DynFlags -> CoreExpr -> Arity

-{- The Arity returned is the number of value args the 
-   thing can be applied to without doing much work
-
+{- 

 exprEtaExpandArity is used when eta expanding
        e  ==>  \xy -> e x y
 
 exprEtaExpandArity is used when eta expanding
        e  ==>  \xy -> e x y
 

@@ -941,26 +1009,27 @@ data ArityType = AFun Bool ArityType     -- True <=> one-shot
 
 arityDepth :: ArityType -> Arity
 arityDepth (AFun _ ty) = 1 + arityDepth ty
 
 arityDepth :: ArityType -> Arity
 arityDepth (AFun _ ty) = 1 + arityDepth ty

-arityDepth ty         = 0
+arityDepth _           = 0

 
 

-andArityType ABot          at2           = at2
-andArityType ATop          at2           = ATop
+andArityType :: ArityType -> ArityType -> ArityType
+andArityType ABot           at2           = at2
+andArityType ATop           _             = ATop

 andArityType (AFun t1 at1)  (AFun t2 at2) = AFun (t1 && t2) (andArityType at1 at2)
 andArityType (AFun t1 at1)  (AFun t2 at2) = AFun (t1 && t2) (andArityType at1 at2)

-andArityType at1           at2           = andArityType at2 at1
+andArityType at1            at2           = andArityType at2 at1

 
 arityType :: DynFlags -> CoreExpr -> ArityType
        -- (go1 e) = [b1,..,bn]
        -- means expression can be rewritten \x_b1 -> ... \x_bn -> body
        -- where bi is True <=> the lambda is one-shot
 
 
 arityType :: DynFlags -> CoreExpr -> ArityType
        -- (go1 e) = [b1,..,bn]
        -- means expression can be rewritten \x_b1 -> ... \x_bn -> body
        -- where bi is True <=> the lambda is one-shot
 

-arityType dflags (Note n e) = arityType dflags e
+arityType dflags (Note _ e) = arityType dflags e

 --     Not needed any more: etaExpand is cleverer
 --     Not needed any more: etaExpand is cleverer

---  | ok_note n = arityType dflags e
---  | otherwise = ATop
+-- removed: | ok_note n = arityType dflags e
+-- removed: | otherwise = ATop

 
 

-arityType dflags (Cast e co) = arityType dflags e
+arityType dflags (Cast e _) = arityType dflags e

 
 

-arityType dflags (Var v) 
+arityType _ (Var v)

   = mk (idArity v) (arg_tys (idType v))
   where
     mk :: Arity -> [Type] -> ArityType
   = mk (idArity v) (arg_tys (idType v))
   where
     mk :: Arity -> [Type] -> ArityType

@@ -970,9 +1039,9 @@ arityType dflags (Var v)
        --              False -> \(s:RealWorld) -> e
        -- where foo has arity 1.  Then we want the state hack to
        -- apply to foo too, so we can eta expand the case.
        --              False -> \(s:RealWorld) -> e
        -- where foo has arity 1.  Then we want the state hack to
        -- apply to foo too, so we can eta expand the case.

-    mk 0 tys | isBottomingId v                    = ABot
-             | (ty:tys) <- tys, isStateHackType ty = AFun True ATop
-            | otherwise                           = ATop
+    mk 0 tys | isBottomingId v                   = ABot
+             | (ty:_) <- tys, isStateHackType ty = AFun True ATop
+             | otherwise                         = ATop

     mk n (ty:tys) = AFun (isStateHackType ty) (mk (n-1) tys)
     mk n []       = AFun False               (mk (n-1) [])
 
     mk n (ty:tys) = AFun (isStateHackType ty) (mk (n-1) tys)
     mk n []       = AFun False               (mk (n-1) [])
 

@@ -989,9 +1058,13 @@ arityType dflags (Lam x e)
 
        -- Applications; decrease arity
 arityType dflags (App f (Type _)) = arityType dflags f
 
        -- Applications; decrease arity
 arityType dflags (App f (Type _)) = arityType dflags f

-arityType dflags (App f a)       = case arityType dflags f of
-                                       AFun one_shot xs | exprIsCheap a -> xs
-                                       other                            -> ATop
+arityType dflags (App f a)
+   = case arityType dflags f of
+       ABot -> ABot    -- If function diverges, ignore argument
+       ATop -> ATop    -- No no info about function
+       AFun _ xs
+               | exprIsCheap a -> xs
+               | otherwise     -> ATop

                                                           
        -- Case/Let; keep arity if either the expression is cheap
        -- or it's a 1-shot lambda
                                                           
        -- Case/Let; keep arity if either the expression is cheap
        -- or it's a 1-shot lambda

@@ -1002,15 +1075,15 @@ arityType dflags (App f a)        = case arityType dflags f of
        -- The difference is observable using 'seq'
 arityType dflags (Case scrut _ _ alts)
   = case foldr1 andArityType [arityType dflags rhs | (_,_,rhs) <- alts] of
        -- The difference is observable using 'seq'
 arityType dflags (Case scrut _ _ alts)
   = case foldr1 andArityType [arityType dflags rhs | (_,_,rhs) <- alts] of

-       xs | exprIsCheap scrut          -> xs
-       xs@(AFun one_shot _) | one_shot -> AFun True ATop
-       other                           -> ATop
+        xs | exprIsCheap scrut     -> xs
+        AFun one_shot _ | one_shot -> AFun True ATop
+        _                          -> ATop

 
 arityType dflags (Let b e) 
   = case arityType dflags e of
 
 arityType dflags (Let b e) 
   = case arityType dflags e of

-       xs                   | cheap_bind b -> xs
-       xs@(AFun one_shot _) | one_shot     -> AFun True ATop
-       other                               -> ATop
+        xs              | cheap_bind b -> xs
+        AFun one_shot _ | one_shot     -> AFun True ATop
+        _                              -> ATop

   where
     cheap_bind (NonRec b e) = is_cheap (b,e)
     cheap_bind (Rec prs)    = all is_cheap prs
   where
     cheap_bind (NonRec b e) = is_cheap (b,e)
     cheap_bind (Rec prs)    = all is_cheap prs

@@ -1033,7 +1106,7 @@ arityType dflags (Let b e)
        -- One could go further and make exprIsCheap reply True to any
        -- dictionary-typed expression, but that's more work.
 
        -- One could go further and make exprIsCheap reply True to any
        -- dictionary-typed expression, but that's more work.
 

-arityType dflags other = ATop
+arityType _ _ = ATop

 
 {- NOT NEEDED ANY MORE: etaExpand is cleverer
 ok_note InlineMe = False
 
 {- NOT NEEDED ANY MORE: etaExpand is cleverer
 ok_note InlineMe = False

@@ -1052,17 +1125,21 @@ ok_note other    = True
 
 
 \begin{code}
 
 
 \begin{code}

-etaExpand :: Arity             -- Result should have this number of value args
-         -> [Unique]
-         -> CoreExpr -> Type   -- Expression and its type
-         -> CoreExpr
--- (etaExpand n us e ty) returns an expression with 
--- the same meaning as 'e', but with arity 'n'.  
+-- | @etaExpand n us e ty@ returns an expression with
+-- the same meaning as @e@, but with arity @n@.
+--
+-- Given:

 --
 --

--- Given e' = etaExpand n us e ty
--- We should have
---     ty = exprType e = exprType e'
+-- > e' = etaExpand n us e ty

 --
 --

+-- We should have that:
+--
+-- > ty = exprType e = exprType e'
+etaExpand :: Arity             -- ^ Result should have this number of value args
+         -> [Unique]           -- ^ Uniques to assign to the new binders
+         -> CoreExpr           -- ^ Expression to expand
+         -> Type               -- ^ Type of expression to expand
+         -> CoreExpr

 -- Note that SCCs are not treated specially.  If we have
 --     etaExpand 2 (\x -> scc "foo" e)
 --     = (\xy -> (scc "foo" e) y)
 -- Note that SCCs are not treated specially.  If we have
 --     etaExpand 2 (\x -> scc "foo" e)
 --     = (\xy -> (scc "foo" e) y)

@@ -1072,7 +1149,6 @@ etaExpand n us expr ty
   | manifestArity expr >= n = expr             -- The no-op case
   | otherwise              
   = eta_expand n us expr ty
   | manifestArity expr >= n = expr             -- The no-op case
   | otherwise              
   = eta_expand n us expr ty

-  where

 
 -- manifestArity sees how many leading value lambdas there are
 manifestArity :: CoreExpr -> Arity
 
 -- manifestArity sees how many leading value lambdas there are
 manifestArity :: CoreExpr -> Arity

@@ -1080,7 +1156,7 @@ manifestArity (Lam v e) | isId v    = 1 + manifestArity e
                        | otherwise = manifestArity e
 manifestArity (Note _ e)           = manifestArity e
 manifestArity (Cast e _)            = manifestArity e
                        | otherwise = manifestArity e
 manifestArity (Note _ e)           = manifestArity e
 manifestArity (Cast e _)            = manifestArity e

-manifestArity e                            = 0
+manifestArity _                     = 0

 
 -- etaExpand deals with for-alls. For example:
 --             etaExpand 1 E
 
 -- etaExpand deals with for-alls. For example:
 --             etaExpand 1 E

@@ -1090,8 +1166,9 @@ manifestArity e                       = 0
 --
 -- It deals with coerces too, though they are now rare
 -- so perhaps the extra code isn't worth it
 --
 -- It deals with coerces too, though they are now rare
 -- so perhaps the extra code isn't worth it

+eta_expand :: Int -> [Unique] -> CoreExpr -> Type -> CoreExpr

 
 

-eta_expand n us expr ty
+eta_expand n _ expr ty

   | n == 0 && 
     -- The ILX code generator requires eta expansion for type arguments
     -- too, but alas the 'n' doesn't tell us how many of them there 
   | n == 0 && 
     -- The ILX code generator requires eta expansion for type arguments
     -- too, but alas the 'n' doesn't tell us how many of them there 

@@ -1132,7 +1209,7 @@ eta_expand n us expr ty
 
               Lam lam_tv (eta_expand n us2 (App expr (Type (mkTyVarTy lam_tv))) (substTyWith [tv] [mkTyVarTy lam_tv] ty'))
                   where 
 
               Lam lam_tv (eta_expand n us2 (App expr (Type (mkTyVarTy lam_tv))) (substTyWith [tv] [mkTyVarTy lam_tv] ty'))
                   where 

-                    lam_tv = setVarName tv (mkSysTvName uniq FSLIT("etaT"))
+                    lam_tv = setVarName tv (mkSysTvName uniq (fsLit "etaT"))

                        -- Using tv as a base retains its tyvar/covar-ness
                     (uniq:us2) = us 
        ; Nothing ->
                        -- Using tv as a base retains its tyvar/covar-ness
                     (uniq:us2) = us 
        ; Nothing ->

@@ -1140,7 +1217,7 @@ eta_expand n us expr ty
        case splitFunTy_maybe ty of {
          Just (arg_ty, res_ty) -> Lam arg1 (eta_expand (n-1) us2 (App expr (Var arg1)) res_ty)
                                where
        case splitFunTy_maybe ty of {
          Just (arg_ty, res_ty) -> Lam arg1 (eta_expand (n-1) us2 (App expr (Var arg1)) res_ty)
                                where

-                                  arg1       = mkSysLocal FSLIT("eta") uniq arg_ty
+                                  arg1       = mkSysLocal (fsLit "eta") uniq arg_ty

                                   (uniq:us2) = us
                                   
        ; Nothing ->
                                   (uniq:us2) = us
                                   
        ; Nothing ->

@@ -1153,14 +1230,15 @@ eta_expand n us expr ty
                --      coerce T (\x::[T] -> (coerce ([T]->Int) e) x)
 
        case splitNewTypeRepCo_maybe ty of {
                --      coerce T (\x::[T] -> (coerce ([T]->Int) e) x)
 
        case splitNewTypeRepCo_maybe ty of {

-         Just(ty1,co) -> 
-              mkCoerce (mkSymCoercion co) (eta_expand n us (mkCoerce co expr) ty1) ;
+         Just(ty1,co) -> mkCoerce (mkSymCoercion co) 
+                                  (eta_expand n us (mkCoerce co expr) ty1) ;

          Nothing  -> 
 
        -- We have an expression of arity > 0, but its type isn't a function
        -- This *can* legitmately happen: e.g.  coerce Int (\x. x)
        -- Essentially the programmer is playing fast and loose with types
        -- (Happy does this a lot).  So we simply decline to eta-expand.
          Nothing  -> 
 
        -- We have an expression of arity > 0, but its type isn't a function
        -- This *can* legitmately happen: e.g.  coerce Int (\x. x)
        -- Essentially the programmer is playing fast and loose with types
        -- (Happy does this a lot).  So we simply decline to eta-expand.

+       -- Otherwise we'd end up with an explicit lambda having a non-function type

        expr
        }}}
 \end{code}
        expr
        }}}
 \end{code}

@@ -1189,26 +1267,52 @@ And in any case it seems more robust to have exprArity be a bit more intelligent
 But note that  (\x y z -> f x y z)
 should have arity 3, regardless of f's arity.
 
 But note that  (\x y z -> f x y z)
 should have arity 3, regardless of f's arity.
 

+Note [exprArity invariant]
+~~~~~~~~~~~~~~~~~~~~~~~~~~
+exprArity has the following invariant:
+       (exprArity e) = n, then manifestArity (etaExpand e n) = n
+
+That is, if exprArity says "the arity is n" then etaExpand really can get
+"n" manifest lambdas to the top.
+
+Why is this important?  Because 
+  - In TidyPgm we use exprArity to fix the *final arity* of 
+    each top-level Id, and in
+  - In CorePrep we use etaExpand on each rhs, so that the visible lambdas
+    actually match that arity, which in turn means
+    that the StgRhs has the right number of lambdas
+
+An alternative would be to do the eta-expansion in TidyPgm, at least
+for top-level bindings, in which case we would not need the trim_arity
+in exprArity.  That is a less local change, so I'm going to leave it for today!
+
+

 \begin{code}
 \begin{code}

+-- | An approximate, fast, version of 'exprEtaExpandArity'

 exprArity :: CoreExpr -> Arity
 exprArity e = go e
 exprArity :: CoreExpr -> Arity
 exprArity e = go e

-           where
-             go (Var v)                   = idArity v
-             go (Lam x e) | isId x        = go e + 1
-                          | otherwise     = go e
-              go (Note (TickBox {}) _)     = 0
-              go (Note (BinaryTickBox {}) _) 
-                                          = 0
-             go (Note n e)                = go e
-              go (Cast e _)                = go e
-             go (App e (Type t))          = go e
-             go (App f a) | exprIsCheap a = (go f - 1) `max` 0
-               -- NB: exprIsCheap a!  
-               --      f (fac x) does not have arity 2, 
-               --      even if f has arity 3!
-               -- NB: `max 0`!  (\x y -> f x) has arity 2, even if f is
-               --               unknown, hence arity 0
-             go _                         = 0
+  where
+    go (Var v)                          = idArity v
+    go (Lam x e) | isId x       = go e + 1
+                | otherwise     = go e
+    go (Note _ e)                = go e
+    go (Cast e co)               = trim_arity (go e) 0 (snd (coercionKind co))
+    go (App e (Type _))          = go e
+    go (App f a) | exprIsCheap a = (go f - 1) `max` 0
+       -- NB: exprIsCheap a!  
+       --      f (fac x) does not have arity 2, 
+       --      even if f has arity 3!
+       -- NB: `max 0`!  (\x y -> f x) has arity 2, even if f is
+       --               unknown, hence arity 0
+    go _                          = 0
+
+       -- Note [exprArity invariant]
+    trim_arity n a ty
+       | n==a                                        = a
+       | Just (_, ty') <- splitForAllTy_maybe ty     = trim_arity n a     ty'
+       | Just (_, ty') <- splitFunTy_maybe ty        = trim_arity n (a+1) ty'
+       | Just (ty',_)  <- splitNewTypeRepCo_maybe ty = trim_arity n a     ty'
+       | otherwise                                   = a

 \end{code}
 
 %************************************************************************
 \end{code}
 
 %************************************************************************

@@ -1217,11 +1321,12 @@ exprArity e = go e
 %*                                                                     *
 %************************************************************************
 
 %*                                                                     *
 %************************************************************************
 

-@cheapEqExpr@ is a cheap equality test which bales out fast!
-       True  => definitely equal
-       False => may or may not be equal
-

 \begin{code}
 \begin{code}

+-- | A cheap equality test which bales out fast!
+--      If it returns @True@ the arguments are definitely equal,
+--      otherwise, they may or may not be equal.
+--
+-- See also 'exprIsBig'

 cheapEqExpr :: Expr b -> Expr b -> Bool
 
 cheapEqExpr (Var v1)   (Var v2)   = v1==v2
 cheapEqExpr :: Expr b -> Expr b -> Bool
 
 cheapEqExpr (Var v1)   (Var v2)   = v1==v2

@@ -1231,23 +1336,26 @@ cheapEqExpr (Type t1)  (Type t2)  = t1 `coreEqType` t2
 cheapEqExpr (App f1 a1) (App f2 a2)
   = f1 `cheapEqExpr` f2 && a1 `cheapEqExpr` a2
 
 cheapEqExpr (App f1 a1) (App f2 a2)
   = f1 `cheapEqExpr` f2 && a1 `cheapEqExpr` a2
 

+cheapEqExpr (Cast e1 t1) (Cast e2 t2)
+  = e1 `cheapEqExpr` e2 && t1 `coreEqCoercion` t2
+

 cheapEqExpr _ _ = False
 
 exprIsBig :: Expr b -> Bool
 cheapEqExpr _ _ = False
 
 exprIsBig :: Expr b -> Bool

--- Returns True of expressions that are too big to be compared by cheapEqExpr
+-- ^ Returns @True@ of expressions that are too big to be compared by 'cheapEqExpr'

 exprIsBig (Lit _)      = False
 exprIsBig (Lit _)      = False

-exprIsBig (Var v)      = False
-exprIsBig (Type t)     = False
+exprIsBig (Var _)      = False
+exprIsBig (Type _)     = False

 exprIsBig (App f a)    = exprIsBig f || exprIsBig a
 exprIsBig (Cast e _)   = exprIsBig e   -- Hopefully coercions are not too big!
 exprIsBig (App f a)    = exprIsBig f || exprIsBig a
 exprIsBig (Cast e _)   = exprIsBig e   -- Hopefully coercions are not too big!

-exprIsBig other               = True
+exprIsBig _            = True

 \end{code}
 
 
 \begin{code}
 tcEqExpr :: CoreExpr -> CoreExpr -> Bool
 \end{code}
 
 
 \begin{code}
 tcEqExpr :: CoreExpr -> CoreExpr -> Bool

--- Used in rule matching, so does *not* look through 
--- newtypes, predicate types; hence tcEqExpr
+-- ^ A kind of shallow equality used in rule matching, so does 
+-- /not/ look through newtypes or predicate types

 
 tcEqExpr e1 e2 = tcEqExprX rn_env e1 e2
   where
 
 tcEqExpr e1 e2 = tcEqExprX rn_env e1 e2
   where

@@ -1255,7 +1363,7 @@ tcEqExpr e1 e2 = tcEqExprX rn_env e1 e2
 
 tcEqExprX :: RnEnv2 -> CoreExpr -> CoreExpr -> Bool
 tcEqExprX env (Var v1)    (Var v2)     = rnOccL env v1 == rnOccR env v2
 
 tcEqExprX :: RnEnv2 -> CoreExpr -> CoreExpr -> Bool
 tcEqExprX env (Var v1)    (Var v2)     = rnOccL env v1 == rnOccR env v2

-tcEqExprX env (Lit lit1)   (Lit lit2)   = lit1 == lit2
+tcEqExprX _   (Lit lit1)   (Lit lit2)   = lit1 == lit2

 tcEqExprX env (App f1 a1)  (App f2 a2)  = tcEqExprX env f1 f2 && tcEqExprX env a1 a2
 tcEqExprX env (Lam v1 e1)  (Lam v2 e2)  = tcEqExprX (rnBndr2 env v1 v2) e1 e2
 tcEqExprX env (Let (NonRec v1 r1) e1)
 tcEqExprX env (App f1 a1)  (App f2 a2)  = tcEqExprX env f1 f2 && tcEqExprX env a1 a2
 tcEqExprX env (Lam v1 e1)  (Lam v2 e2)  = tcEqExprX (rnBndr2 env v1 v2) e1 e2
 tcEqExprX env (Let (NonRec v1 r1) e1)

@@ -1277,16 +1385,18 @@ tcEqExprX env (Case e1 v1 t1 a1)
                                     where
                                       env' = rnBndr2 env v1 v2
 
                                     where
                                       env' = rnBndr2 env v1 v2
 

-tcEqExprX env (Note n1 e1) (Note n2 e2) = eq_note env n1 n2 && tcEqExprX env e1 e2
+tcEqExprX env (Note n1 e1)  (Note n2 e2)  = eq_note env n1 n2 && tcEqExprX env e1 e2

 tcEqExprX env (Cast e1 co1) (Cast e2 co2) = tcEqTypeX env co1 co2 && tcEqExprX env e1 e2
 tcEqExprX env (Cast e1 co1) (Cast e2 co2) = tcEqTypeX env co1 co2 && tcEqExprX env e1 e2

-tcEqExprX env (Type t1)    (Type t2)    = tcEqTypeX env t1 t2
-tcEqExprX env e1               e2      = False
-                                        
+tcEqExprX env (Type t1)     (Type t2)     = tcEqTypeX env t1 t2
+tcEqExprX _   _             _             = False
+
+eq_alt :: RnEnv2 -> CoreAlt -> CoreAlt -> Bool

 eq_alt env (c1,vs1,r1) (c2,vs2,r2) = c1==c2 && tcEqExprX (rnBndrs2 env vs1  vs2) r1 r2
 
 eq_alt env (c1,vs1,r1) (c2,vs2,r2) = c1==c2 && tcEqExprX (rnBndrs2 env vs1  vs2) r1 r2
 

-eq_note env (SCC cc1)      (SCC cc2)      = cc1 == cc2
-eq_note env (CoreNote s1)  (CoreNote s2)  = s1 == s2
-eq_note env other1            other2     = False
+eq_note :: RnEnv2 -> Note -> Note -> Bool
+eq_note _ (SCC cc1)     (SCC cc2)      = cc1 == cc2
+eq_note _ (CoreNote s1) (CoreNote s2)  = s1 == s2
+eq_note _ _             _              = False

 \end{code}
 
 
 \end{code}
 
 

@@ -1301,8 +1411,8 @@ coreBindsSize :: [CoreBind] -> Int
 coreBindsSize bs = foldr ((+) . bindSize) 0 bs
 
 exprSize :: CoreExpr -> Int
 coreBindsSize bs = foldr ((+) . bindSize) 0 bs
 
 exprSize :: CoreExpr -> Int

-       -- A measure of the size of the expressions
-       -- It also forces the expression pretty drastically as a side effect
+-- ^ A measure of the size of the expressions, strictly greater than 0
+-- It also forces the expression pretty drastically as a side effect

 exprSize (Var v)         = v `seq` 1
 exprSize (Lit lit)       = lit `seq` 1
 exprSize (App f a)       = exprSize f + exprSize a
 exprSize (Var v)         = v `seq` 1
 exprSize (Lit lit)       = lit `seq` 1
 exprSize (App f a)       = exprSize f + exprSize a

@@ -1313,25 +1423,28 @@ exprSize (Cast e co)     = (seqType co `seq` 1) + exprSize e
 exprSize (Note n e)      = noteSize n + exprSize e
 exprSize (Type t)        = seqType t `seq` 1
 
 exprSize (Note n e)      = noteSize n + exprSize e
 exprSize (Type t)        = seqType t `seq` 1
 

+noteSize :: Note -> Int

 noteSize (SCC cc)       = cc `seq` 1
 noteSize InlineMe       = 1
 noteSize (CoreNote s)   = s `seq` 1  -- hdaume: core annotations
 noteSize (SCC cc)       = cc `seq` 1
 noteSize InlineMe       = 1
 noteSize (CoreNote s)   = s `seq` 1  -- hdaume: core annotations

-noteSize (TickBox m n)    = m `seq` n `seq` 1 
-noteSize (BinaryTickBox m t e)  = m `seq` t `seq` e `seq` 1 
-
+ 

 varSize :: Var -> Int
 varSize b  | isTyVar b = 1
           | otherwise = seqType (idType b)             `seq`
                         megaSeqIdInfo (idInfo b)       `seq`
                         1
 
 varSize :: Var -> Int
 varSize b  | isTyVar b = 1
           | otherwise = seqType (idType b)             `seq`
                         megaSeqIdInfo (idInfo b)       `seq`
                         1
 

-varsSize = foldr ((+) . varSize) 0
+varsSize :: [Var] -> Int
+varsSize = sum . map varSize

 
 

+bindSize :: CoreBind -> Int

 bindSize (NonRec b e) = varSize b + exprSize e
 bindSize (Rec prs)    = foldr ((+) . pairSize) 0 prs
 
 bindSize (NonRec b e) = varSize b + exprSize e
 bindSize (Rec prs)    = foldr ((+) . pairSize) 0 prs
 

+pairSize :: (Var, CoreExpr) -> Int

 pairSize (b,e) = varSize b + exprSize e
 
 pairSize (b,e) = varSize b + exprSize e
 

+altSize :: CoreAlt -> Int

 altSize (c,bs,e) = c `seq` varsSize bs + exprSize e
 \end{code}
 
 altSize (c,bs,e) = c `seq` varsSize bs + exprSize e
 \end{code}
 

@@ -1344,39 +1457,60 @@ altSize (c,bs,e) = c `seq` varsSize bs + exprSize e
 
 \begin{code}
 hashExpr :: CoreExpr -> Int
 
 \begin{code}
 hashExpr :: CoreExpr -> Int

--- Two expressions that hash to the same Int may be equal (but may not be)
--- Two expressions that hash to the different Ints are definitely unequal
+-- ^ Two expressions that hash to the same @Int@ may be equal (but may not be)
+-- Two expressions that hash to the different Ints are definitely unequal.
+--
+-- The emphasis is on a crude, fast hash, rather than on high precision.

 -- 
 -- 

--- But "unequal" here means "not identical"; two alpha-equivalent 
--- expressions may hash to the different Ints
+-- But unequal here means \"not identical\"; two alpha-equivalent 
+-- expressions may hash to the different Ints.

 --
 --

--- The emphasis is on a crude, fast hash, rather than on high precision
-
-hashExpr e | hash < 0  = 77    -- Just in case we hit -maxInt
-          | otherwise = hash
-          where
-            hash = abs (hash_expr e)   -- Negative numbers kill UniqFM
-
-hash_expr (Note _ e)                     = hash_expr e
-hash_expr (Cast e co)             = hash_expr e
-hash_expr (Let (NonRec b r) e)    = hashId b
-hash_expr (Let (Rec ((b,r):_)) e) = hashId b
-hash_expr (Case _ b _ _)         = hashId b
-hash_expr (App f e)              = hash_expr f * fast_hash_expr e
-hash_expr (Var v)                = hashId v
-hash_expr (Lit lit)              = hashLiteral lit
-hash_expr (Lam b _)              = hashId b
-hash_expr (Type t)               = trace "hash_expr: type" 1           -- Shouldn't happen
-
-fast_hash_expr (Var v)         = hashId v
-fast_hash_expr (Lit lit)       = hashLiteral lit
-fast_hash_expr (App f (Type _)) = fast_hash_expr f
-fast_hash_expr (App f a)        = fast_hash_expr a
-fast_hash_expr (Lam b _)        = hashId b
-fast_hash_expr other           = 1
-
-hashId :: Id -> Int
-hashId id = hashName (idName id)
+-- We must be careful that @\\x.x@ and @\\y.y@ map to the same hash code,
+-- (at least if we want the above invariant to be true).
+
+hashExpr e = fromIntegral (hash_expr (1,emptyVarEnv) e .&. 0x7fffffff)
+             -- UniqFM doesn't like negative Ints
+
+type HashEnv = (Int, VarEnv Int)  -- Hash code for bound variables
+
+hash_expr :: HashEnv -> CoreExpr -> Word32
+-- Word32, because we're expecting overflows here, and overflowing
+-- signed types just isn't cool.  In C it's even undefined.
+hash_expr env (Note _ e)             = hash_expr env e
+hash_expr env (Cast e _)              = hash_expr env e
+hash_expr env (Var v)                = hashVar env v
+hash_expr _   (Lit lit)               = fromIntegral (hashLiteral lit)
+hash_expr env (App f e)              = hash_expr env f * fast_hash_expr env e
+hash_expr env (Let (NonRec b r) e)    = hash_expr (extend_env env b) e * fast_hash_expr env r
+hash_expr env (Let (Rec ((b,_):_)) e) = hash_expr (extend_env env b) e
+hash_expr env (Case e _ _ _)         = hash_expr env e
+hash_expr env (Lam b e)                      = hash_expr (extend_env env b) e
+hash_expr _   (Type _)                = WARN(True, text "hash_expr: type") 1
+-- Shouldn't happen.  Better to use WARN than trace, because trace
+-- prevents the CPR optimisation kicking in for hash_expr.
+
+fast_hash_expr :: HashEnv -> CoreExpr -> Word32
+fast_hash_expr env (Var v)             = hashVar env v
+fast_hash_expr env (Type t)    = fast_hash_type env t
+fast_hash_expr _   (Lit lit)    = fromIntegral (hashLiteral lit)
+fast_hash_expr env (Cast e _)   = fast_hash_expr env e
+fast_hash_expr env (Note _ e)   = fast_hash_expr env e
+fast_hash_expr env (App _ a)    = fast_hash_expr env a -- A bit idiosyncratic ('a' not 'f')!
+fast_hash_expr _   _            = 1
+
+fast_hash_type :: HashEnv -> Type -> Word32
+fast_hash_type env ty 
+  | Just tv <- getTyVar_maybe ty            = hashVar env tv
+  | Just (tc,tys) <- splitTyConApp_maybe ty = let hash_tc = fromIntegral (hashName (tyConName tc))
+                                             in foldr (\t n -> fast_hash_type env t + n) hash_tc tys
+  | otherwise                              = 1
+
+extend_env :: HashEnv -> Var -> (Int, VarEnv Int)
+extend_env (n,env) b = (n+1, extendVarEnv env b n)
+
+hashVar :: HashEnv -> Var -> Word32
+hashVar (_,env) v
+ = fromIntegral (lookupVarEnv env v `orElse` hashName (idName v))

 \end{code}
 
 %************************************************************************
 \end{code}
 
 %************************************************************************

@@ -1391,17 +1525,17 @@ arguments, come from another DLL (because we can't refer to static
 labels in other DLLs).
 
 If this happens we simply make the RHS into an updatable thunk, 
 labels in other DLLs).
 
 If this happens we simply make the RHS into an updatable thunk, 

-and 'exectute' it rather than allocating it statically.
+and 'execute' it rather than allocating it statically.

 
 \begin{code}
 
 \begin{code}

+-- | This function is called only on *top-level* right-hand sides.
+-- Returns @True@ if the RHS can be allocated statically in the output,
+-- with no thunks involved at all.

 rhsIsStatic :: PackageId -> CoreExpr -> Bool
 rhsIsStatic :: PackageId -> CoreExpr -> Bool

--- This function is called only on *top-level* right-hand sides
--- Returns True if the RHS can be allocated statically, with
--- no thunks involved at all.
---

 -- It's called (i) in TidyPgm.hasCafRefs to decide if the rhs is, or
 -- It's called (i) in TidyPgm.hasCafRefs to decide if the rhs is, or

--- refers to, CAFs; and (ii) in CoreToStg to decide whether to put an
--- update flag on it.
+-- refers to, CAFs; (ii) in CoreToStg to decide whether to put an
+-- update flag on it and (iii) in DsExpr to decide how to expand
+-- list literals

 --
 -- The basic idea is that rhsIsStatic returns True only if the RHS is
 --     (a) a value lambda
 --
 -- The basic idea is that rhsIsStatic returns True only if the RHS is
 --     (a) a value lambda

@@ -1451,27 +1585,22 @@ rhsIsStatic :: PackageId -> CoreExpr -> Bool
 --        dynamic
 -- 
 --    c) don't look through unfolding of f in (f x).
 --        dynamic
 -- 
 --    c) don't look through unfolding of f in (f x).

---
--- When opt_RuntimeTypes is on, we keep type lambdas and treat
--- them as making the RHS re-entrant (non-updatable).

 
 

-rhsIsStatic this_pkg rhs = is_static False rhs
+rhsIsStatic _this_pkg rhs = is_static False rhs

   where
   is_static :: Bool    -- True <=> in a constructor argument; must be atomic
          -> CoreExpr -> Bool
   
   is_static False (Lam b e) = isRuntimeVar b || is_static False e
   
   where
   is_static :: Bool    -- True <=> in a constructor argument; must be atomic
          -> CoreExpr -> Bool
   
   is_static False (Lam b e) = isRuntimeVar b || is_static False e
   

-  is_static in_arg (Note (SCC _) e) = False
-  is_static in_arg (Note (TickBox {}) e) = False
-  is_static in_arg (Note (BinaryTickBox {}) e) = False
+  is_static _      (Note (SCC _) _) = False

   is_static in_arg (Note _ e)       = is_static in_arg e
   is_static in_arg (Note _ e)       = is_static in_arg e

-  is_static in_arg (Cast e co)      = is_static in_arg e
+  is_static in_arg (Cast e _)       = is_static in_arg e

   
   

-  is_static in_arg (Lit lit)
+  is_static _      (Lit lit)

     = case lit of
        MachLabel _ _ -> False
     = case lit of
        MachLabel _ _ -> False

-       other         -> True
+        _             -> True

        -- A MachLabel (foreign import "&foo") in an argument
        -- prevents a constructor application from being static.  The
        -- reason is that it might give rise to unresolvable symbols
        -- A MachLabel (foreign import "&foo") in an argument
        -- prevents a constructor application from being static.  The
        -- reason is that it might give rise to unresolvable symbols

@@ -1485,7 +1614,7 @@ rhsIsStatic this_pkg rhs = is_static False rhs
    where
     go (Var f) n_val_args
 #if mingw32_TARGET_OS
    where
     go (Var f) n_val_args
 #if mingw32_TARGET_OS

-        | not (isDllName this_pkg (idName f))
+        | not (isDllName _this_pkg (idName f))

 #endif
        =  saturated_data_con f n_val_args
        || (in_arg && n_val_args == 0)  
 #endif
        =  saturated_data_con f n_val_args
        || (in_arg && n_val_args == 0)  

@@ -1507,11 +1636,11 @@ rhsIsStatic this_pkg rhs = is_static False rhs
         --   x = D# (1.0## /## 2.0##)
         -- can't float because /## can fail.
 
         --   x = D# (1.0## /## 2.0##)
         -- can't float because /## can fail.
 

-    go (Note (SCC _) f) n_val_args = False
-    go (Note _ f) n_val_args       = go f n_val_args
-    go (Cast e co) n_val_args      = go e n_val_args
+    go (Note (SCC _) _) _          = False
+    go (Note _ f)       n_val_args = go f n_val_args
+    go (Cast e _)       n_val_args = go e n_val_args

 
 

-    go other n_val_args = False
+    go _                _          = False

 
     saturated_data_con f n_val_args
        = case isDataConWorkId_maybe f of
 
     saturated_data_con f n_val_args
        = case isDataConWorkId_maybe f of