[project @ 2003-12-30 16:29:17 by simonpj]

[ghc-hetmet.git] / ghc / compiler / basicTypes / MkId.lhs

diff --git a/ghc/compiler/basicTypes/MkId.lhs b/ghc/compiler/basicTypes/MkId.lhs
index 0d5bcec..cbbe8ec 100644 (file)
--- a/ghc/compiler/basicTypes/MkId.lhs
+++ b/ghc/compiler/basicTypes/MkId.lhs
@@ -14,18 +14,23 @@ have a standard form, namely:
 \begin{code}
 module MkId (
        mkDictFunId, mkDefaultMethodId,
 \begin{code}
 module MkId (
        mkDictFunId, mkDefaultMethodId,

-       mkDictSelId,
+       mkDictSelId, 

 
 

-       mkDataConId, mkDataConWrapId,
-       mkRecordSelId, rebuildConArgs,
+       mkDataConIds,
+       mkRecordSelId, 

        mkPrimOpId, mkFCallId,
 
        mkPrimOpId, mkFCallId,
 

+       mkReboxingAlt, mkNewTypeBody,
+

        -- And some particular Ids; see below for why they are wired in
        -- And some particular Ids; see below for why they are wired in

-       wiredInIds,
-       unsafeCoerceId, realWorldPrimId,
-       eRROR_ID, eRROR_CSTRING_ID, rEC_SEL_ERROR_ID, pAT_ERROR_ID, rEC_CON_ERROR_ID,
-       rEC_UPD_ERROR_ID, iRREFUT_PAT_ERROR_ID, nON_EXHAUSTIVE_GUARDS_ERROR_ID,
-       nO_METHOD_BINDING_ERROR_ID, aBSENT_ERROR_ID, pAR_ERROR_ID
+       wiredInIds, ghcPrimIds,
+       unsafeCoerceId, realWorldPrimId, voidArgId, nullAddrId, seqId,
+       lazyId, lazyIdUnfolding, lazyIdKey,
+
+       mkRuntimeErrorApp,
+       rEC_CON_ERROR_ID, iRREFUT_PAT_ERROR_ID, rUNTIME_ERROR_ID,
+       nON_EXHAUSTIVE_GUARDS_ERROR_ID, nO_METHOD_BINDING_ERROR_ID,
+       pAT_ERROR_ID, eRROR_ID

     ) where
 
 #include "HsVersions.h"
     ) where
 
 #include "HsVersions.h"

@@ -33,63 +38,64 @@ module MkId (
 
 import BasicTypes      ( Arity, StrictnessMark(..), isMarkedUnboxed, isMarkedStrict )
 import TysPrim         ( openAlphaTyVars, alphaTyVar, alphaTy, 
 
 import BasicTypes      ( Arity, StrictnessMark(..), isMarkedUnboxed, isMarkedStrict )
 import TysPrim         ( openAlphaTyVars, alphaTyVar, alphaTy, 

-                         intPrimTy, realWorldStatePrimTy, addrPrimTy
+                         realWorldStatePrimTy, addrPrimTy

                        )
 import TysWiredIn      ( charTy, mkListTy )
                        )
 import TysWiredIn      ( charTy, mkListTy )

-import PrelRules       ( primOpRule )
+import PrelRules       ( primOpRules )

 import Rules           ( addRule )
 import Rules           ( addRule )

+import Type            ( TyThing(..) )

 import TcType          ( Type, ThetaType, mkDictTy, mkPredTys, mkTyConApp,
                          mkTyVarTys, mkClassPred, tcEqPred,
                          mkFunTys, mkFunTy, mkSigmaTy, tcSplitSigmaTy, 
                          isUnLiftedType, mkForAllTys, mkTyVarTy, tyVarsOfType,
                          tcSplitFunTys, tcSplitForAllTys, mkPredTy
                        )
 import TcType          ( Type, ThetaType, mkDictTy, mkPredTys, mkTyConApp,
                          mkTyVarTys, mkClassPred, tcEqPred,
                          mkFunTys, mkFunTy, mkSigmaTy, tcSplitSigmaTy, 
                          isUnLiftedType, mkForAllTys, mkTyVarTy, tyVarsOfType,
                          tcSplitFunTys, tcSplitForAllTys, mkPredTy
                        )

-import Module          ( Module )
-import CoreUtils       ( exprType, mkInlineMe )
+import CoreUtils       ( exprType )

 import CoreUnfold      ( mkTopUnfolding, mkCompulsoryUnfolding, mkOtherCon )
 import CoreUnfold      ( mkTopUnfolding, mkCompulsoryUnfolding, mkOtherCon )

-import Literal         ( Literal(..) )
+import Literal         ( Literal(..), nullAddrLit )

 import TyCon           ( TyCon, isNewTyCon, tyConTyVars, tyConDataCons,
                           tyConTheta, isProductTyCon, isDataTyCon, isRecursiveTyCon )
 import Class           ( Class, classTyCon, classTyVars, classSelIds )
 import TyCon           ( TyCon, isNewTyCon, tyConTyVars, tyConDataCons,
                           tyConTheta, isProductTyCon, isDataTyCon, isRecursiveTyCon )
 import Class           ( Class, classTyCon, classTyVars, classSelIds )

-import Var             ( Id, TyVar )
+import Var             ( Id, TyVar, Var )

 import VarSet          ( isEmptyVarSet )
 import VarSet          ( isEmptyVarSet )

-import Name            ( mkWiredInName, mkFCallName, Name )
-import OccName         ( mkVarOcc )
-import PrimOp          ( PrimOp(DataToTagOp), primOpSig, mkPrimOpIdName )
+import Name            ( mkFCallName, mkWiredInName, Name )
+import OccName         ( mkOccFS, varName )
+import PrimOp          ( PrimOp, primOpSig, primOpOcc, primOpTag )

 import ForeignCall     ( ForeignCall )
 import ForeignCall     ( ForeignCall )

-import DataCon         ( DataCon, 
-                         dataConFieldLabels, dataConRepArity, dataConTyCon,
-                         dataConArgTys, dataConRepType, dataConRepStrictness, 
-                         dataConInstOrigArgTys,
-                          dataConName, dataConTheta,
-                         dataConSig, dataConStrictMarks, dataConId,
+import DataCon         ( DataCon, DataConIds(..),
+                         dataConFieldLabels, dataConRepArity, 
+                         dataConArgTys, dataConRepType, 
+                         dataConOrigArgTys, dataConTheta,
+                         dataConSig, dataConStrictMarks, dataConExStricts, 

                          splitProductType
                        )
                          splitProductType
                        )

-import Id              ( idType, mkGlobalId, mkVanillaGlobal, mkSysLocal,
-                         mkTemplateLocals, mkTemplateLocalsNum,
-                         mkTemplateLocal, idNewStrictness, idName
+import Id              ( idType, mkGlobalId, mkVanillaGlobal, mkSysLocal, 
+                         mkTemplateLocals, mkTemplateLocalsNum, mkExportedLocalId,
+                         mkTemplateLocal, idName

                        )
                        )

-import IdInfo          ( IdInfo, noCafNoTyGenIdInfo,
-                         exactArity, setUnfoldingInfo, setCprInfo,
-                         setArityInfo, setSpecInfo,  setCgInfo,
-                         mkNewStrictnessInfo, setNewStrictnessInfo,
-                         GlobalIdDetails(..), CafInfo(..), CprInfo(..), 
-                         CgInfo(..), setCgArity
+import IdInfo          ( IdInfo, noCafIdInfo,  setUnfoldingInfo, 
+                         setArityInfo, setSpecInfo, setCafInfo,
+                         setAllStrictnessInfo, vanillaIdInfo,
+                         GlobalIdDetails(..), CafInfo(..)

                        )
                        )

-import NewDemand       ( mkStrictSig, strictSigResInfo, DmdResult(..),
-                         mkTopDmdType, topDmd, evalDmd )
-import FieldLabel      ( mkFieldLabel, fieldLabelName, 
-                         firstFieldLabelTag, allFieldLabelTags, fieldLabelType
+import NewDemand       ( mkStrictSig, DmdResult(..),
+                         mkTopDmdType, topDmd, evalDmd, lazyDmd, retCPR,
+                         Demand(..), Demands(..) )
+import FieldLabel      ( fieldLabelName, firstFieldLabelTag, 
+                         allFieldLabelTags, fieldLabelType

                        )
                        )

+import DmdAnal         ( dmdAnalTopRhs )

 import CoreSyn
 import CoreSyn

-import Unique          ( mkBuiltinUnique )
+import Unique          ( mkBuiltinUnique, mkPrimOpIdUnique )

 import Maybes
 import PrelNames
 import Maybe            ( isJust )
 import Maybes
 import PrelNames
 import Maybe            ( isJust )

+import Util             ( dropList, isSingleton )

 import Outputable
 import Outputable

+import FastString

 import ListSetOps      ( assoc, assocMaybe )
 import UnicodeUtil      ( stringToUtf8 )
 import ListSetOps      ( assoc, assocMaybe )
 import UnicodeUtil      ( stringToUtf8 )

-import Char             ( ord )
+import List            ( nubBy )

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

@@ -106,24 +112,33 @@ wiredInIds
        -- 
        -- [The interface file format now carry such information, but there's
        -- no way yet of expressing at the definition site for these 
        -- 
        -- [The interface file format now carry such information, but there's
        -- no way yet of expressing at the definition site for these 

-       -- error-reporting
-       -- functions that they have an 'open' result type. -- sof 1/99]
-
-      aBSENT_ERROR_ID
-    , eRROR_ID
-    , eRROR_CSTRING_ID
-    , iRREFUT_PAT_ERROR_ID
-    , nON_EXHAUSTIVE_GUARDS_ERROR_ID
-    , nO_METHOD_BINDING_ERROR_ID
-    , pAR_ERROR_ID
-    , pAT_ERROR_ID
-    , rEC_CON_ERROR_ID
-    , rEC_UPD_ERROR_ID
-
-       -- These three can't be defined in Haskell
-    , realWorldPrimId
-    , unsafeCoerceId
-    , getTagId
+       -- error-reporting functions that they have an 'open' 
+       -- result type. -- sof 1/99]
+
+    eRROR_ID,  -- This one isn't used anywhere else in the compiler
+               -- But we still need it in wiredInIds so that when GHC
+               -- compiles a program that mentions 'error' we don't
+               -- import its type from the interface file; we just get
+               -- the Id defined here.  Which has an 'open-tyvar' type.
+
+    rUNTIME_ERROR_ID,
+    iRREFUT_PAT_ERROR_ID,
+    nON_EXHAUSTIVE_GUARDS_ERROR_ID,
+    nO_METHOD_BINDING_ERROR_ID,
+    pAT_ERROR_ID,
+    rEC_CON_ERROR_ID,
+
+    lazyId
+    ] ++ ghcPrimIds
+
+-- These Ids are exported from GHC.Prim
+ghcPrimIds
+  = [  -- These can't be defined in Haskell, but they have
+       -- perfectly reasonable unfoldings in Core
+    realWorldPrimId,
+    unsafeCoerceId,
+    nullAddrId,
+    seqId

     ]
 \end{code}
 
     ]
 \end{code}
 

@@ -133,43 +148,6 @@ wiredInIds
 %*                                                                     *
 %************************************************************************
 
 %*                                                                     *
 %************************************************************************
 

-\begin{code}
-mkDataConId :: Name -> DataCon -> Id
-       -- Makes the *worker* for the data constructor; that is, the function
-       -- that takes the reprsentation arguments and builds the constructor.
-mkDataConId work_name data_con
-  = id 
-  where
-    id = mkGlobalId (DataConId data_con) work_name (dataConRepType data_con) info
-    info = noCafNoTyGenIdInfo
-          `setCgArity`                 arity
-          `setArityInfo`               arity
-          `setNewStrictnessInfo`       Just strict_sig
-
-    arity = dataConRepArity data_con
-    strict_sig = mkStrictSig id arity (mkTopDmdType (dataConRepStrictness data_con) cpr_info)
-
-    tycon = dataConTyCon data_con
-    cpr_info | isProductTyCon tycon && 
-              isDataTyCon tycon    &&
-              arity > 0            &&
-              arity <= mAX_CPR_SIZE    = RetCPR
-            | otherwise                = TopRes
-       -- RetCPR is only true for products that are real data types;
-       -- that is, not unboxed tuples or [non-recursive] newtypes
-
-mAX_CPR_SIZE :: Arity
-mAX_CPR_SIZE = 10
--- We do not treat very big tuples as CPR-ish:
---     a) for a start we get into trouble because there aren't 
---        "enough" unboxed tuple types (a tiresome restriction, 
---        but hard to fix), 
---     b) more importantly, big unboxed tuples get returned mainly
---        on the stack, and are often then allocated in the heap
---        by the caller.  So doing CPR for them may in fact make
---        things worse.
-\end{code}
-

 The wrapper for a constructor is an ordinary top-level binding that evaluates
 any strict args, unboxes any args that are going to be flattened, and calls
 the worker.
 The wrapper for a constructor is an ordinary top-level binding that evaluates
 any strict args, unboxes any args that are going to be flattened, and calls
 the worker.

@@ -207,87 +185,118 @@ Notice that
   Making an explicit case expression allows the simplifier to eliminate
   it in the (common) case where the constructor arg is already evaluated.
 
   Making an explicit case expression allows the simplifier to eliminate
   it in the (common) case where the constructor arg is already evaluated.
 

+

 \begin{code}
 \begin{code}

-mkDataConWrapId data_con
-  = wrap_id
-  where
-    wrap_id = mkGlobalId (DataConWrapId data_con) (dataConName data_con) wrap_ty info
-    work_id = dataConId data_con
-
-    info = noCafNoTyGenIdInfo
-          `setUnfoldingInfo`   mkTopUnfolding (mkInlineMe wrap_rhs)
-          `setCgArity`         arity
-               -- The NoCaf-ness is set by noCafNoTyGenIdInfo
-          `setArityInfo`       arity
-               -- It's important to specify the arity, so that partial
-               -- applications are treated as values
-          `setNewStrictnessInfo`       Just wrap_sig
-
-    wrap_ty = mkForAllTys all_tyvars $
-             mkFunTys all_arg_tys
-             result_ty
-
-    res_info = strictSigResInfo (idNewStrictness work_id)
-    wrap_sig = mkStrictSig wrap_id arity (mkTopDmdType (replicate arity topDmd) res_info)
-       -- The Cpr info can be important inside INLINE rhss, where the
-       -- wrapper constructor isn't inlined
-       -- But we are sloppy about the argument demands, because we expect 
-       -- to inline the constructor very vigorously.
-
-    wrap_rhs | isNewTyCon tycon
-            = ASSERT( null ex_tyvars && null ex_dict_args && length orig_arg_tys == 1 )
-               -- No existentials on a newtype, but it can have a context
-               -- e.g.         newtype Eq a => T a = MkT (...)
-               mkLams tyvars $ mkLams dict_args $ Lam id_arg1 $ 
-               mkNewTypeBody tycon result_ty id_arg1
-
-            | null dict_args && not (any isMarkedStrict strict_marks)
-            = Var work_id      -- The common case.  Not only is this efficient,
-                               -- but it also ensures that the wrapper is replaced
-                               -- by the worker even when there are no args.
-                               --              f (:) x
-                               -- becomes 
-                               --              f $w: x
-                               -- This is really important in rule matching,
-                               -- (We could match on the wrappers,
-                               -- but that makes it less likely that rules will match
-                               -- when we bring bits of unfoldings together.)
-               --
-               -- NB:  because of this special case, (map (:) ys) turns into
-               --      (map $w: ys), and thence into (map (\x xs. $w: x xs) ys)
-               --      in core-to-stg.  The top-level defn for (:) is never used.
-               --      This is somewhat of a bore, but I'm currently leaving it 
-               --      as is, so that there still is a top level curried (:) for
-               --      the interpreter to call.
-
-            | otherwise
-            = mkLams all_tyvars $ mkLams dict_args $ 
-              mkLams ex_dict_args $ mkLams id_args $
-              foldr mk_case con_app 
-                    (zip (ex_dict_args++id_args) strict_marks) i3 []
-
-    con_app i rep_ids = mkApps (Var work_id)
-                              (map varToCoreExpr (all_tyvars ++ reverse rep_ids))
+mkDataConIds :: Name -> Name -> DataCon -> DataConIds
+       -- Makes the *worker* for the data constructor; that is, the function
+       -- that takes the reprsentation arguments and builds the constructor.
+mkDataConIds wrap_name wkr_name data_con
+  | isNewTyCon tycon
+  = NewDC nt_wrap_id

 
 

-    (tyvars, theta, ex_tyvars, ex_theta, orig_arg_tys, tycon) = dataConSig data_con
-    all_tyvars   = tyvars ++ ex_tyvars
+  | any isMarkedStrict all_strict_marks                -- Algebraic, needs wrapper
+  = AlgDC (Just alg_wrap_id) wrk_id
+
+  | otherwise                                  -- Algebraic, no wrapper
+  = AlgDC Nothing wrk_id
+  where
+    (tyvars, _, ex_tyvars, ex_theta, orig_arg_tys, tycon) = dataConSig data_con
+    all_tyvars = tyvars ++ ex_tyvars

 
 

-    dict_tys     = mkPredTys theta

     ex_dict_tys  = mkPredTys ex_theta
     ex_dict_tys  = mkPredTys ex_theta

-    all_arg_tys  = dict_tys ++ ex_dict_tys ++ orig_arg_tys
+    all_arg_tys  = ex_dict_tys ++ orig_arg_tys

     result_ty    = mkTyConApp tycon (mkTyVarTys tyvars)
 
     result_ty    = mkTyConApp tycon (mkTyVarTys tyvars)
 

-    mkLocals i tys = (zipWith mkTemplateLocal [i..i+n-1] tys, i+n)
-                  where
-                    n = length tys
+    wrap_ty = mkForAllTys all_tyvars (mkFunTys all_arg_tys result_ty)
+       -- We used to include the stupid theta in the wrapper's args
+       -- but now we don't.  Instead the type checker just injects these
+       -- extra constraints where necessary.
+
+       ----------- Worker (algebraic data types only) --------------
+    wrk_id = mkGlobalId (DataConWorkId data_con) wkr_name
+                       (dataConRepType data_con) wkr_info
+
+    wkr_arity = dataConRepArity data_con
+    wkr_info  = noCafIdInfo
+               `setArityInfo`          wkr_arity
+               `setAllStrictnessInfo`  Just wkr_sig
+
+    wkr_sig = mkStrictSig (mkTopDmdType (replicate wkr_arity topDmd) cpr_info)
+       -- Notice that we do *not* say the worker is strict
+       -- even if the data constructor is declared strict
+       --      e.g.    data T = MkT !(Int,Int)
+       -- Why?  Because the *wrapper* is strict (and its unfolding has case
+       -- expresssions that do the evals) but the *worker* itself is not.
+       -- If we pretend it is strict then when we see
+       --      case x of y -> $wMkT y
+       -- the simplifier thinks that y is "sure to be evaluated" (because
+       -- $wMkT is strict) and drops the case.  No, $wMkT is not strict.
+       --
+       -- When the simplifer sees a pattern 
+       --      case e of MkT x -> ...
+       -- it uses the dataConRepStrictness of MkT to mark x as evaluated;
+       -- but that's fine... dataConRepStrictness comes from the data con
+       -- not from the worker Id.

 
 

-    (dict_args, i1)    = mkLocals 1  dict_tys
-    (ex_dict_args,i2)  = mkLocals i1 ex_dict_tys
-    (id_args,i3)       = mkLocals i2 orig_arg_tys
-    arity             = i3-1
-    (id_arg1:_)   = id_args            -- Used for newtype only
+    cpr_info | isProductTyCon tycon && 
+              isDataTyCon tycon    &&
+              wkr_arity > 0        &&
+              wkr_arity <= mAX_CPR_SIZE        = retCPR
+            | otherwise                        = TopRes
+       -- RetCPR is only true for products that are real data types;
+       -- that is, not unboxed tuples or [non-recursive] newtypes

 
 

-    strict_marks  = dataConStrictMarks data_con
+       ----------- Wrappers for newtypes --------------
+    nt_wrap_id   = mkGlobalId (DataConWrapId data_con) wrap_name wrap_ty nt_wrap_info
+    nt_wrap_info = noCafIdInfo         -- The NoCaf-ness is set by noCafIdInfo
+                 `setArityInfo` 1      -- Arity 1
+                 `setUnfoldingInfo`     newtype_unf
+    newtype_unf  = ASSERT( null ex_tyvars && null ex_theta && 
+                         isSingleton orig_arg_tys )
+                  -- No existentials on a newtype, but it can have a context
+                  -- e.g.      newtype Eq a => T a = MkT (...)
+                  mkTopUnfolding $ Note InlineMe $
+                  mkLams tyvars $ Lam id_arg1 $ 
+                  mkNewTypeBody tycon result_ty (Var id_arg1)
+
+    id_arg1 = mkTemplateLocal 1 (head orig_arg_tys)
+
+       ----------- Wrappers for algebraic data types -------------- 
+    alg_wrap_id = mkGlobalId (DataConWrapId data_con) wrap_name wrap_ty alg_wrap_info
+    alg_wrap_info = noCafIdInfo                -- The NoCaf-ness is set by noCafIdInfo
+                   `setArityInfo`         alg_arity
+                       -- It's important to specify the arity, so that partial
+                       -- applications are treated as values
+                   `setUnfoldingInfo`     alg_unf
+                   `setAllStrictnessInfo` Just wrap_sig
+
+    all_strict_marks = dataConExStricts data_con ++ dataConStrictMarks data_con
+    wrap_sig = mkStrictSig (mkTopDmdType arg_dmds cpr_info)
+    arg_dmds = map mk_dmd all_strict_marks
+    mk_dmd str | isMarkedStrict str = evalDmd
+              | otherwise          = lazyDmd
+       -- The Cpr info can be important inside INLINE rhss, where the
+       -- wrapper constructor isn't inlined.
+       -- And the argument strictness can be important too; we
+       -- may not inline a contructor when it is partially applied.
+       -- For example:
+       --      data W = C !Int !Int !Int
+       --      ...(let w = C x in ...(w p q)...)...
+       -- we want to see that w is strict in its two arguments
+
+    alg_unf = mkTopUnfolding $ Note InlineMe $
+             mkLams all_tyvars $ 
+             mkLams ex_dict_args $ mkLams id_args $
+             foldr mk_case con_app 
+                   (zip (ex_dict_args ++ id_args) all_strict_marks)
+                   i3 []
+
+    con_app i rep_ids = mkApps (Var wrk_id)
+                              (map varToCoreExpr (all_tyvars ++ reverse rep_ids))
+
+    (ex_dict_args,i2)  = mkLocals 1  ex_dict_tys
+    (id_args,i3)       = mkLocals i2 orig_arg_tys
+    alg_arity         = i3-1

 
     mk_case 
           :: (Id, StrictnessMark)      -- Arg, strictness
 
     mk_case 
           :: (Id, StrictnessMark)      -- Arg, strictness

@@ -310,6 +319,21 @@ mkDataConWrapId data_con
                                        body i' (reverse con_args ++ rep_args))]
                              where 
                                (con_args, i') = mkLocals i tys
                                        body i' (reverse con_args ++ rep_args))]
                              where 
                                (con_args, i') = mkLocals i tys

+
+mAX_CPR_SIZE :: Arity
+mAX_CPR_SIZE = 10
+-- We do not treat very big tuples as CPR-ish:
+--     a) for a start we get into trouble because there aren't 
+--        "enough" unboxed tuple types (a tiresome restriction, 
+--        but hard to fix), 
+--     b) more importantly, big unboxed tuples get returned mainly
+--        on the stack, and are often then allocated in the heap
+--        by the caller.  So doing CPR for them may in fact make
+--        things worse.
+
+mkLocals i tys = (zipWith mkTemplateLocal [i..i+n-1] tys, i+n)
+              where
+                n = length tys

 \end{code}
 
 
 \end{code}
 
 

@@ -350,19 +374,16 @@ Then we want
 (not f :: R -> forall a. a->a, which gives the type inference mechanism 
 problems at call sites)
 
 (not f :: R -> forall a. a->a, which gives the type inference mechanism 
 problems at call sites)
 

-Similarly for newtypes
+Similarly for (recursive) newtypes

 
        newtype N = MkN { unN :: forall a. a->a }
 
 
        newtype N = MkN { unN :: forall a. a->a }
 

-       unN :: forall a. N -> a -> a
-       unN = /\a -> \n:N -> coerce (a->a) n
+       unN :: forall b. N -> b -> b
+       unN = /\b -> \n:N -> (coerce (forall a. a->a) n)

 
 \begin{code}
 
 \begin{code}

-mkRecordSelId tycon field_label unpack_id unpackUtf8_id
+mkRecordSelId tycon field_label

        -- Assumes that all fields with the same field label have the same type
        -- Assumes that all fields with the same field label have the same type

-       --
-       -- Annoyingly, we have to pass in the unpackCString# Id, because
-       -- we can't conjure it up out of thin air

   = sel_id
   where
     sel_id     = mkGlobalId (RecordSelId field_label) (fieldLabelName field_label) selector_ty info
   = sel_id
   where
     sel_id     = mkGlobalId (RecordSelId field_label) (fieldLabelName field_label) selector_ty info

@@ -373,13 +394,22 @@ mkRecordSelId tycon field_label unpack_id unpackUtf8_id
     data_ty   = mkTyConApp tycon tyvar_tys
     tyvar_tys = mkTyVarTys tyvars
 
     data_ty   = mkTyConApp tycon tyvar_tys
     tyvar_tys = mkTyVarTys tyvars
 

-    tycon_theta        = tyConTheta tycon      -- The context on the data decl
+       -- Very tiresomely, the selectors are (unnecessarily!) overloaded over
+       -- just the dictionaries in the types of the constructors that contain
+       -- the relevant field.  [The Report says that pattern matching on a
+       -- constructor gives the same constraints as applying it.]  Urgh.  
+       --
+       -- However, not all data cons have all constraints (because of
+       -- TcTyDecls.thinContext).  So we need to find all the data cons 
+       -- involved in the pattern match and take the union of their constraints.
+       --
+       -- NB: this code relies on the fact that DataCons are quantified over
+       -- the identical type variables as their parent TyCon
+    tycon_theta         = tyConTheta tycon     -- The context on the data decl

                                        --   eg data (Eq a, Ord b) => T a b = ...
                                        --   eg data (Eq a, Ord b) => T a b = ...

-    dict_tys  = [mkPredTy pred | pred <- tycon_theta, 
-                                needed_dict pred]
-    needed_dict pred = or [ tcEqPred pred p
-                         | (DataAlt dc, _, _) <- the_alts, p <- dataConTheta dc]
-    n_dict_tys = length dict_tys
+    needed_preds = [pred | (DataAlt dc, _, _) <- the_alts, pred <- dataConTheta dc]
+    dict_tys     = map mkPredTy (nubBy tcEqPred needed_preds)
+    n_dict_tys   = length dict_tys

 
     (field_tyvars,field_theta,field_tau) = tcSplitSigmaTy field_ty
     field_dict_tys                      = map mkPredTy field_theta
 
     (field_tyvars,field_theta,field_tau) = tcSplitSigmaTy field_ty
     field_dict_tys                      = map mkPredTy field_theta

@@ -399,25 +429,22 @@ mkRecordSelId tycon field_label unpack_id unpackUtf8_id
        -- Note that this is exactly the type we'd infer from a user defn
        --      op (R op) = op
 
        -- Note that this is exactly the type we'd infer from a user defn
        --      op (R op) = op
 

-       -- Very tiresomely, the selectors are (unnecessarily!) overloaded over
-       -- just the dictionaries in the types of the constructors that contain
-       -- the relevant field.  Urgh.  
-       -- NB: this code relies on the fact that DataCons are quantified over
-       -- the identical type variables as their parent TyCon
-

     selector_ty :: Type
     selector_ty  = mkForAllTys tyvars $ mkForAllTys field_tyvars $
                   mkFunTys dict_tys  $  mkFunTys field_dict_tys $
                   mkFunTy data_ty field_tau
       
     arity = 1 + n_dict_tys + n_field_dict_tys
     selector_ty :: Type
     selector_ty  = mkForAllTys tyvars $ mkForAllTys field_tyvars $
                   mkFunTys dict_tys  $  mkFunTys field_dict_tys $
                   mkFunTy data_ty field_tau
       
     arity = 1 + n_dict_tys + n_field_dict_tys

-    info = noCafNoTyGenIdInfo
-          `setCgInfo`          (CgInfo arity caf_info)
-          `setArityInfo`       arity
-          `setUnfoldingInfo`   unfolding       
-       -- ToDo: consider adding further IdInfo

 
 

-    unfolding = mkTopUnfolding sel_rhs
+    (strict_sig, rhs_w_str) = dmdAnalTopRhs sel_rhs
+       -- Use the demand analyser to work out strictness.
+       -- With all this unpackery it's not easy!
+
+    info = noCafIdInfo
+          `setCafInfo`           caf_info
+          `setArityInfo`         arity
+          `setUnfoldingInfo`     mkTopUnfolding rhs_w_str
+          `setAllStrictnessInfo` Just strict_sig

 
        -- Allocate Ids.  We do it a funny way round because field_dict_tys is
        -- almost always empty.  Also note that we use length_tycon_theta
 
        -- Allocate Ids.  We do it a funny way round because field_dict_tys is
        -- almost always empty.  Also note that we use length_tycon_theta

@@ -438,7 +465,7 @@ mkRecordSelId tycon field_label unpack_id unpackUtf8_id
     default_alt | no_default = []
                | otherwise  = [(DEFAULT, [], error_expr)]
 
     default_alt | no_default = []
                | otherwise  = [(DEFAULT, [], error_expr)]
 

-       -- the default branch may have CAF refs, because it calls recSelError etc.
+       -- The default branch may have CAF refs, because it calls recSelError etc.

     caf_info    | no_default = NoCafRefs
                | otherwise  = MayHaveCafRefs
 
     caf_info    | no_default = NoCafRefs
                | otherwise  = MayHaveCafRefs
 

@@ -446,81 +473,96 @@ mkRecordSelId tycon field_label unpack_id unpackUtf8_id
              mkLams dict_ids $ mkLams field_dict_ids $
              Lam data_id     $ sel_body
 
              mkLams dict_ids $ mkLams field_dict_ids $
              Lam data_id     $ sel_body
 

-    sel_body | isNewTyCon tycon = mkNewTypeBody tycon field_tau data_id
+    sel_body | isNewTyCon tycon = mk_result (mkNewTypeBody tycon field_ty (Var data_id))

             | otherwise        = Case (Var data_id) data_id (default_alt ++ the_alts)
 
             | otherwise        = Case (Var data_id) data_id (default_alt ++ the_alts)
 

+    mk_result poly_result = mkVarApps (mkVarApps poly_result field_tyvars) field_dict_ids
+       -- We pull the field lambdas to the top, so we need to 
+       -- apply them in the body.  For example:
+       --      data T = MkT { foo :: forall a. a->a }
+       --
+       --      foo :: forall a. T -> a -> a
+       --      foo = /\a. \t:T. case t of { MkT f -> f a }
+

     mk_maybe_alt data_con 
     mk_maybe_alt data_con 

-         = case maybe_the_arg_id of
+       = case maybe_the_arg_id of

                Nothing         -> Nothing
                Nothing         -> Nothing

-               Just the_arg_id -> Just (DataAlt data_con, real_args, mkLets binds body)
-                 where
-                   body               = mkVarApps (mkVarApps (Var the_arg_id) field_tyvars) field_dict_ids
-                   strict_marks       = dataConStrictMarks data_con
-                   (binds, real_args) = rebuildConArgs arg_ids strict_marks
-                                                       (map mkBuiltinUnique [unpack_base..])
+               Just the_arg_id -> Just (mkReboxingAlt uniqs data_con arg_ids body)
+                               where
+                                  body = mk_result (Var the_arg_id)

        where
        where

-            arg_ids = mkTemplateLocalsNum field_base (dataConInstOrigArgTys data_con tyvar_tys)
+            arg_ids = mkTemplateLocalsNum field_base (dataConOrigArgTys data_con)
+                       -- No need to instantiate; same tyvars in datacon as tycon
+                       -- Records can't be existential, so no existential tyvars or dicts

 
            unpack_base = field_base + length arg_ids
 
            unpack_base = field_base + length arg_ids

+           uniqs = map mkBuiltinUnique [unpack_base..]

 
                                -- arity+1 avoids all shadowing
            maybe_the_arg_id  = assocMaybe (field_lbls `zip` arg_ids) field_label
            field_lbls        = dataConFieldLabels data_con
 
 
                                -- arity+1 avoids all shadowing
            maybe_the_arg_id  = assocMaybe (field_lbls `zip` arg_ids) field_label
            field_lbls        = dataConFieldLabels data_con
 

-    error_expr = mkApps (Var rEC_SEL_ERROR_ID) [Type field_tau, err_string]
-    err_string
-        | all safeChar full_msg
-            = App (Var unpack_id) (Lit (MachStr (_PK_ full_msg)))
-        | otherwise
-            = App (Var unpackUtf8_id) (Lit (MachStr (_PK_ (stringToUtf8 (map ord full_msg)))))
-        where
-        safeChar c = c >= '\1' && c <= '\xFF'
-        -- TODO: Putting this Unicode stuff here is ugly. Find a better
-        -- generic place to make string literals. This logic is repeated
-        -- in DsUtils.
+    error_expr = mkRuntimeErrorApp rEC_SEL_ERROR_ID field_tau full_msg

     full_msg   = showSDoc (sep [text "No match in record selector", ppr sel_id]) 
 
 
     full_msg   = showSDoc (sep [text "No match in record selector", ppr sel_id]) 
 
 

--- This rather ugly function converts the unpacked data con 
--- arguments back into their packed form.
-
-rebuildConArgs
-  :: [Id]                      -- Source-level args
-  -> [StrictnessMark]          -- Strictness annotations (per-arg)
-  -> [Unique]                  -- Uniques for the new Ids
-  -> ([CoreBind], [Id])                -- A binding for each source-level arg, plus
-                               -- a list of the representation-level arguments 
--- e.g.   data T = MkT Int !Int
+-- (mkReboxingAlt us con xs rhs) basically constructs the case
+-- alternative (con, xs, rhs)
+-- but it does the reboxing necessary to construct the *source* 
+-- arguments, xs, from the representation arguments ys.
+-- For example:
+--     data T = MkT !(Int,Int) Bool

 --
 --

--- rebuild [x::Int, y::Int] [Not, Unbox]
---  = ([ y = I# t ], [x,t])
+-- mkReboxingAlt MkT [x,b] r 
+--     = (DataAlt MkT, [y::Int,z::Int,b], let x = (y,z) in r)
+--
+-- mkDataAlt should really be in DataCon, but it can't because
+-- it manipulates CoreSyn.

 
 

-rebuildConArgs []        stricts us = ([], [])
+mkReboxingAlt
+  :: [Unique]                  -- Uniques for the new Ids
+  -> DataCon
+  -> [Var]                     -- Source-level args
+  -> CoreExpr                  -- RHS
+  -> CoreAlt

 
 

--- Type variable case
-rebuildConArgs (arg:args) stricts us 
-  | isTyVar arg
-  = let (binds, args') = rebuildConArgs args stricts us
-    in  (binds, arg:args')
+mkReboxingAlt us con args rhs
+  | not (any isMarkedUnboxed stricts)
+  = (DataAlt con, args, rhs)

 
 

--- Term variable case
-rebuildConArgs (arg:args) (str:stricts) us
-  | isMarkedUnboxed str
+  | otherwise

   = let
   = let

-       arg_ty  = idType arg
-
-       (_, tycon_args, pack_con, con_arg_tys)
-                = splitProductType "rebuildConArgs" arg_ty
-
-       unpacked_args  = zipWith (mkSysLocal SLIT("rb")) us con_arg_tys
-       (binds, args') = rebuildConArgs args stricts (drop (length con_arg_tys) us)
-       con_app        = mkConApp pack_con (map Type tycon_args ++ map Var unpacked_args)
+       (binds, args') = go args stricts us

     in
     in

-    (NonRec arg con_app : binds, unpacked_args ++ args')
+    (DataAlt con, args', mkLets binds rhs)

 
 

-  | otherwise
-  = let (binds, args') = rebuildConArgs args stricts us
-    in  (binds, arg:args')
+  where
+    stricts = dataConExStricts con ++ dataConStrictMarks con
+
+    go [] stricts us = ([], [])
+
+       -- Type variable case
+    go (arg:args) stricts us 
+      | isTyVar arg
+      = let (binds, args') = go args stricts us
+       in  (binds, arg:args')
+
+       -- Term variable case
+    go (arg:args) (str:stricts) us
+      | isMarkedUnboxed str
+      = let
+         (_, tycon_args, pack_con, con_arg_tys)
+                = splitProductType "mkReboxingAlt" (idType arg)
+
+         unpacked_args  = zipWith (mkSysLocal FSLIT("rb")) us con_arg_tys
+         (binds, args') = go args stricts (dropList con_arg_tys us)
+         con_app        = mkConApp pack_con (map Type tycon_args ++ map Var unpacked_args)
+       in
+       (NonRec arg con_app : binds, unpacked_args ++ args')
+
+      | otherwise
+      = let (binds, args') = go args stricts us
+        in  (binds, arg:args')

 \end{code}
 
 
 \end{code}
 
 

@@ -533,12 +575,25 @@ rebuildConArgs (arg:args) (str:stricts) us
 Selecting a field for a dictionary.  If there is just one field, then
 there's nothing to do.  
 
 Selecting a field for a dictionary.  If there is just one field, then
 there's nothing to do.  
 

-ToDo: unify with mkRecordSelId.
+Dictionary selectors may get nested forall-types.  Thus:
+
+       class Foo a where
+         op :: forall b. Ord b => a -> b -> b
+
+Then the top-level type for op is
+
+       op :: forall a. Foo a => 
+             forall b. Ord b => 
+             a -> b -> b
+
+This is unlike ordinary record selectors, which have all the for-alls
+at the outside.  When dealing with classes it's very convenient to
+recover the original type signature from the class op selector.

 
 \begin{code}
 mkDictSelId :: Name -> Class -> Id
 mkDictSelId name clas
 
 \begin{code}
 mkDictSelId :: Name -> Class -> Id
 mkDictSelId name clas

-  = mkGlobalId (RecordSelId field_lbl) name sel_ty info
+  = mkGlobalId (ClassOpId clas) name sel_ty info

   where
     sel_ty = mkForAllTys tyvars (mkFunTy (idType dict_id) (idType the_arg_id))
        -- We can't just say (exprType rhs), because that would give a type
   where
     sel_ty = mkForAllTys tyvars (mkFunTy (idType dict_id) (idType the_arg_id))
        -- We can't just say (exprType rhs), because that would give a type

@@ -547,18 +602,24 @@ mkDictSelId name clas
        -- But it's type must expose the representation of the dictionary
        -- to gat (say)         C a -> (a -> a)
 
        -- But it's type must expose the representation of the dictionary
        -- to gat (say)         C a -> (a -> a)
 

-    field_lbl = mkFieldLabel name tycon sel_ty tag
-    tag       = assoc "MkId.mkDictSelId" (map idName (classSelIds clas) `zip` allFieldLabelTags) name
+    tag  = assoc "MkId.mkDictSelId" (map idName (classSelIds clas) `zip` allFieldLabelTags) name
+
+    info = noCafIdInfo
+               `setArityInfo`          1
+               `setUnfoldingInfo`      mkTopUnfolding rhs
+               `setAllStrictnessInfo`  Just strict_sig

 
 

-    info      = noCafNoTyGenIdInfo
-               `setCgArity`        1
-               `setArityInfo`      1
-               `setUnfoldingInfo`  unfolding
-               

        -- We no longer use 'must-inline' on record selectors.  They'll
        -- inline like crazy if they scrutinise a constructor
 
        -- We no longer use 'must-inline' on record selectors.  They'll
        -- inline like crazy if they scrutinise a constructor
 

-    unfolding = mkTopUnfolding rhs
+       -- The strictness signature is of the form U(AAAVAAAA) -> T
+       -- where the V depends on which item we are selecting
+       -- It's worth giving one, so that absence info etc is generated
+       -- even if the selector isn't inlined
+    strict_sig = mkStrictSig (mkTopDmdType [arg_dmd] TopRes)
+    arg_dmd | isNewTyCon tycon = evalDmd
+           | otherwise        = Eval (Prod [ if the_arg_id == id then evalDmd else Abs
+                                           | id <- arg_ids ])

 
     tyvars  = classTyVars clas
 
 
     tyvars  = classTyVars clas
 

@@ -572,16 +633,18 @@ mkDictSelId name clas
     (dict_id:arg_ids) = mkTemplateLocals (mkPredTy pred : arg_tys)
 
     rhs | isNewTyCon tycon = mkLams tyvars $ Lam dict_id $ 
     (dict_id:arg_ids) = mkTemplateLocals (mkPredTy pred : arg_tys)
 
     rhs | isNewTyCon tycon = mkLams tyvars $ Lam dict_id $ 

-                            mkNewTypeBody tycon (head arg_tys) dict_id
+                            mkNewTypeBody tycon (head arg_tys) (Var dict_id)

        | otherwise        = mkLams tyvars $ Lam dict_id $
                             Case (Var dict_id) dict_id
                                  [(DataAlt data_con, arg_ids, Var the_arg_id)]
 
        | otherwise        = mkLams tyvars $ Lam dict_id $
                             Case (Var dict_id) dict_id
                                  [(DataAlt data_con, arg_ids, Var the_arg_id)]
 

-mkNewTypeBody tycon result_ty result_id
+mkNewTypeBody tycon result_ty result_expr
+       -- Adds a coerce where necessary
+       -- Used for both wrapping and unwrapping

   | isRecursiveTyCon tycon     -- Recursive case; use a coerce
   | isRecursiveTyCon tycon     -- Recursive case; use a coerce

-  = Note (Coerce result_ty (idType result_id)) (Var result_id)
+  = Note (Coerce result_ty (exprType result_expr)) result_expr

   | otherwise                  -- Normal case
   | otherwise                  -- Normal case

-  = Var result_id
+  = result_expr

 \end{code}
 
 
 \end{code}
 
 

@@ -596,20 +659,19 @@ mkPrimOpId :: PrimOp -> Id
 mkPrimOpId prim_op 
   = id
   where
 mkPrimOpId prim_op 
   = id
   where

-    (tyvars,arg_tys,res_ty, arity, strict_info) = primOpSig prim_op
+    (tyvars,arg_tys,res_ty, arity, strict_sig) = primOpSig prim_op

     ty   = mkForAllTys tyvars (mkFunTys arg_tys res_ty)
     ty   = mkForAllTys tyvars (mkFunTys arg_tys res_ty)

-    name = mkPrimOpIdName prim_op
+    name = mkWiredInName gHC_PRIM (primOpOcc prim_op) 
+                        (mkPrimOpIdUnique (primOpTag prim_op))
+                        Nothing (AnId id) 

     id   = mkGlobalId (PrimOpId prim_op) name ty info
                
     id   = mkGlobalId (PrimOpId prim_op) name ty info
                

-    info = noCafNoTyGenIdInfo
+    info = noCafIdInfo

           `setSpecInfo`        rules
           `setSpecInfo`        rules

-          `setCgArity`         arity

           `setArityInfo`       arity
           `setArityInfo`       arity

-          `setNewStrictnessInfo`       Just (mkNewStrictnessInfo id arity strict_info NoCPRInfo)
-       -- Until we modify the primop generation code
+          `setAllStrictnessInfo` Just strict_sig

 
 

-    rules = maybe emptyCoreRules (addRule emptyCoreRules id)
-               (primOpRule prim_op)
+    rules = foldl (addRule id) emptyCoreRules (primOpRules prim_op)

 
 
 -- For each ccall we manufacture a separate CCallOpId, giving it
 
 
 -- For each ccall we manufacture a separate CCallOpId, giving it

@@ -626,24 +688,22 @@ mkFCallId uniq fcall ty
   = ASSERT( isEmptyVarSet (tyVarsOfType ty) )
        -- A CCallOpId should have no free type variables; 
        -- when doing substitutions won't substitute over it
   = ASSERT( isEmptyVarSet (tyVarsOfType ty) )
        -- A CCallOpId should have no free type variables; 
        -- when doing substitutions won't substitute over it

-    id
+    mkGlobalId (FCallId fcall) name ty info

   where
   where

-    id = mkGlobalId (FCallId fcall) name ty info
-    occ_str = showSDocIface (braces (ppr fcall <+> ppr ty))
+    occ_str = showSDoc (braces (ppr fcall <+> ppr ty))

        -- The "occurrence name" of a ccall is the full info about the
        -- ccall; it is encoded, but may have embedded spaces etc!
 
     name = mkFCallName uniq occ_str
 
        -- The "occurrence name" of a ccall is the full info about the
        -- ccall; it is encoded, but may have embedded spaces etc!
 
     name = mkFCallName uniq occ_str
 

-    info = noCafNoTyGenIdInfo
-          `setCgArity`                 arity
+    info = noCafIdInfo

           `setArityInfo`               arity
           `setArityInfo`               arity

-          `setNewStrictnessInfo`       Just strict_sig
+          `setAllStrictnessInfo`       Just strict_sig

 
     (_, tau)    = tcSplitForAllTys ty
     (arg_tys, _) = tcSplitFunTys tau
     arity       = length arg_tys
 
     (_, tau)    = tcSplitForAllTys ty
     (arg_tys, _) = tcSplitFunTys tau
     arity       = length arg_tys

-    strict_sig   = mkStrictSig id arity (mkTopDmdType (replicate arity evalDmd) TopRes)
+    strict_sig   = mkStrictSig (mkTopDmdType (replicate arity evalDmd) TopRes)

 \end{code}
 
 
 \end{code}
 
 

@@ -653,19 +713,44 @@ mkFCallId uniq fcall ty
 %*                                                                     *
 %************************************************************************
 
 %*                                                                     *
 %************************************************************************
 

+Important notes about dict funs and default methods
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Dict funs and default methods are *not* ImplicitIds.  Their definition
+involves user-written code, so we can't figure out their strictness etc
+based on fixed info, as we can for constructors and record selectors (say).
+
+We build them as GlobalIds, but when in the module where they are
+bound, we turn the Id at the *binding site* into an exported LocalId.
+This ensures that they are taken to account by free-variable finding
+and dependency analysis (e.g. CoreFVs.exprFreeVars).   The simplifier
+will propagate the LocalId to all occurrence sites. 
+
+Why shouldn't they be bound as GlobalIds?  Because, in particular, if
+they are globals, the specialiser floats dict uses above their defns,
+which prevents good simplifications happening.  Also the strictness
+analyser treats a occurrence of a GlobalId as imported and assumes it
+contains strictness in its IdInfo, which isn't true if the thing is
+bound in the same module as the occurrence.
+
+It's OK for dfuns to be LocalIds, because we form the instance-env to
+pass on to the next module (md_insts) in CoreTidy, afer tidying
+and globalising the top-level Ids.
+
+BUT make sure they are *exported* LocalIds (setIdLocalExported) so 
+that they aren't discarded by the occurrence analyser.
+

 \begin{code}
 \begin{code}

-mkDefaultMethodId dm_name ty
-  = mkVanillaGlobal dm_name ty noCafNoTyGenIdInfo
+mkDefaultMethodId dm_name ty = mkExportedLocalId dm_name ty

 
 mkDictFunId :: Name            -- Name to use for the dict fun;
 
 mkDictFunId :: Name            -- Name to use for the dict fun;

-           -> Class 

            -> [TyVar]
            -> [TyVar]

-           -> [Type]

            -> ThetaType
            -> ThetaType

+           -> Class 
+           -> [Type]

            -> Id
 
            -> Id
 

-mkDictFunId dfun_name clas inst_tyvars inst_tys dfun_theta
-  = mkVanillaGlobal dfun_name dfun_ty noCafNoTyGenIdInfo
+mkDictFunId dfun_name inst_tyvars dfun_theta clas inst_tys
+  = mkExportedLocalId dfun_name dfun_ty

   where
     dfun_ty = mkSigmaTy inst_tyvars dfun_theta (mkDictTy clas inst_tys)
 
   where
     dfun_ty = mkSigmaTy inst_tyvars dfun_theta (mkDictTy clas inst_tys)
 

@@ -705,7 +790,12 @@ mkDictFunId dfun_name clas inst_tyvars inst_tys dfun_theta
 %*                                                                     *
 %************************************************************************
 
 %*                                                                     *
 %************************************************************************
 

-These two can't be defined in Haskell.
+These Ids can't be defined in Haskell.  They could be defined in
+unfoldings in the wired-in GHC.Prim interface file, but we'd have to
+ensure that they were definitely, definitely inlined, because there is
+no curried identifier for them.  That's what mkCompulsoryUnfolding
+does.  If we had a way to get a compulsory unfolding from an interface
+file, we could do that, but we don't right now.

 
 unsafeCoerce# isn't so much a PrimOp as a phantom identifier, that
 just gets expanded into a type coercion wherever it occurs.  Hence we
 
 unsafeCoerce# isn't so much a PrimOp as a phantom identifier, that
 just gets expanded into a type coercion wherever it occurs.  Hence we

@@ -716,10 +806,34 @@ they can unify with both unlifted and lifted types.  Hence we provide
 another gun with which to shoot yourself in the foot.
 
 \begin{code}
 another gun with which to shoot yourself in the foot.
 
 \begin{code}

+mkWiredInIdName mod fs uniq id
+ = mkWiredInName mod (mkOccFS varName fs) uniq Nothing (AnId id)
+
+unsafeCoerceName = mkWiredInIdName gHC_PRIM FSLIT("unsafeCoerce#") unsafeCoerceIdKey  unsafeCoerceId
+nullAddrName     = mkWiredInIdName gHC_PRIM FSLIT("nullAddr#")    nullAddrIdKey      nullAddrId
+seqName                 = mkWiredInIdName gHC_PRIM FSLIT("seq")           seqIdKey           seqId
+realWorldName   = mkWiredInIdName gHC_PRIM FSLIT("realWorld#")    realWorldPrimIdKey realWorldPrimId
+lazyIdName      = mkWiredInIdName pREL_BASE FSLIT("lazy")         lazyIdKey          lazyId
+
+errorName               = mkWiredInIdName pREL_ERR FSLIT("error")           errorIdKey eRROR_ID
+recSelErrorName                 = mkWiredInIdName pREL_ERR FSLIT("recSelError")     recSelErrorIdKey rEC_SEL_ERROR_ID
+runtimeErrorName        = mkWiredInIdName pREL_ERR FSLIT("runtimeError")    runtimeErrorIdKey rUNTIME_ERROR_ID
+irrefutPatErrorName     = mkWiredInIdName pREL_ERR FSLIT("irrefutPatError") irrefutPatErrorIdKey iRREFUT_PAT_ERROR_ID
+recConErrorName                 = mkWiredInIdName pREL_ERR FSLIT("recConError")     recConErrorIdKey rEC_CON_ERROR_ID
+patErrorName            = mkWiredInIdName pREL_ERR FSLIT("patError")        patErrorIdKey pAT_ERROR_ID
+noMethodBindingErrorName = mkWiredInIdName pREL_ERR FSLIT("noMethodBindingError")
+                                          noMethodBindingErrorIdKey nO_METHOD_BINDING_ERROR_ID
+nonExhaustiveGuardsErrorName 
+  = mkWiredInIdName pREL_ERR FSLIT("nonExhaustiveGuardsError") 
+                   nonExhaustiveGuardsErrorIdKey nON_EXHAUSTIVE_GUARDS_ERROR_ID
+\end{code}
+
+\begin{code}
+-- unsafeCoerce# :: forall a b. a -> b

 unsafeCoerceId
 unsafeCoerceId

-  = pcMiscPrelId unsafeCoerceIdKey pREL_GHC SLIT("unsafeCoerce#") ty info
+  = pcMiscPrelId unsafeCoerceName ty info

   where
   where

-    info = noCafNoTyGenIdInfo `setUnfoldingInfo` mkCompulsoryUnfolding rhs
+    info = noCafIdInfo `setUnfoldingInfo` mkCompulsoryUnfolding rhs

           
 
     ty  = mkForAllTys [openAlphaTyVar,openBetaTyVar]
           
 
     ty  = mkForAllTys [openAlphaTyVar,openBetaTyVar]

@@ -727,39 +841,66 @@ unsafeCoerceId
     [x] = mkTemplateLocals [openAlphaTy]
     rhs = mkLams [openAlphaTyVar,openBetaTyVar,x] $
          Note (Coerce openBetaTy openAlphaTy) (Var x)
     [x] = mkTemplateLocals [openAlphaTy]
     rhs = mkLams [openAlphaTyVar,openBetaTyVar,x] $
          Note (Coerce openBetaTy openAlphaTy) (Var x)

-\end{code}
-

 
 

-@getTag#@ is another function which can't be defined in Haskell.  It needs to
-evaluate its argument and call the dataToTag# primitive.
+-- nullAddr# :: Addr#
+-- The reason is is here is because we don't provide 
+-- a way to write this literal in Haskell.
+nullAddrId 
+  = pcMiscPrelId nullAddrName addrPrimTy info
+  where
+    info = noCafIdInfo `setUnfoldingInfo` 
+          mkCompulsoryUnfolding (Lit nullAddrLit)

 
 

-\begin{code}
-getTagId
-  = pcMiscPrelId getTagIdKey pREL_GHC SLIT("getTag#") ty info
+seqId
+  = pcMiscPrelId seqName ty info

   where
   where

-    info = noCafNoTyGenIdInfo `setUnfoldingInfo` mkCompulsoryUnfolding rhs
-       -- We don't provide a defn for this; you must inline it
+    info = noCafIdInfo `setUnfoldingInfo` mkCompulsoryUnfolding rhs
+          

 
 

-    ty = mkForAllTys [alphaTyVar] (mkFunTy alphaTy intPrimTy)
-    [x,y] = mkTemplateLocals [alphaTy,alphaTy]
-    rhs = mkLams [alphaTyVar,x] $
-         Case (Var x) y [ (DEFAULT, [], mkApps (Var dataToTagId) [Type alphaTy, Var y]) ]
+    ty  = mkForAllTys [alphaTyVar,openBetaTyVar]
+                     (mkFunTy alphaTy (mkFunTy openBetaTy openBetaTy))
+    [x,y] = mkTemplateLocals [alphaTy, openBetaTy]
+    rhs = mkLams [alphaTyVar,openBetaTyVar,x,y] (Case (Var x) x [(DEFAULT, [], Var y)])
+
+-- lazy :: forall a?. a? -> a?  (i.e. works for unboxed types too)
+-- Used to lazify pseq:                pseq a b = a `seq` lazy b
+-- No unfolding: it gets "inlined" by the worker/wrapper pass
+-- Also, no strictness: by being a built-in Id, it overrides all
+-- the info in PrelBase.hi.  This is important, because the strictness
+-- analyser will spot it as strict!
+lazyId
+  = pcMiscPrelId lazyIdName ty info
+  where
+    info = noCafIdInfo
+    ty  = mkForAllTys [alphaTyVar] (mkFunTy alphaTy alphaTy)

 
 

-dataToTagId = mkPrimOpId DataToTagOp
+lazyIdUnfolding :: CoreExpr    -- Used to expand LazyOp after strictness anal
+lazyIdUnfolding = mkLams [openAlphaTyVar,x] (Var x)
+               where
+                 [x] = mkTemplateLocals [openAlphaTy]

 \end{code}
 
 @realWorld#@ used to be a magic literal, \tr{void#}.  If things get
 nasty as-is, change it back to a literal (@Literal@).
 
 \end{code}
 
 @realWorld#@ used to be a magic literal, \tr{void#}.  If things get
 nasty as-is, change it back to a literal (@Literal@).
 

+voidArgId is a Local Id used simply as an argument in functions
+where we just want an arg to avoid having a thunk of unlifted type.
+E.g.
+       x = \ void :: State# RealWorld -> (# p, q #)
+
+This comes up in strictness analysis
+

 \begin{code}
 realWorldPrimId        -- :: State# RealWorld
 \begin{code}
 realWorldPrimId        -- :: State# RealWorld

-  = pcMiscPrelId realWorldPrimIdKey pREL_GHC SLIT("realWorld#")
-                realWorldStatePrimTy
-                (noCafNoTyGenIdInfo `setUnfoldingInfo` mkOtherCon [])
+  = pcMiscPrelId realWorldName realWorldStatePrimTy
+                (noCafIdInfo `setUnfoldingInfo` mkOtherCon [])

        -- The mkOtherCon makes it look that realWorld# is evaluated
        -- which in turn makes Simplify.interestingArg return True,
        -- which in turn makes INLINE things applied to realWorld# likely
        -- to be inlined
        -- The mkOtherCon makes it look that realWorld# is evaluated
        -- which in turn makes Simplify.interestingArg return True,
        -- which in turn makes INLINE things applied to realWorld# likely
        -- to be inlined

+
+voidArgId      -- :: State# RealWorld
+  = mkSysLocal FSLIT("void") voidArgIdKey realWorldStatePrimTy

 \end{code}
 
 
 \end{code}
 
 

@@ -785,33 +926,39 @@ not know to be a bottoming Id.  It is used in the @_par_@ and @_seq_@
 templates, but we don't ever expect to generate code for it.
 
 \begin{code}
 templates, but we don't ever expect to generate code for it.
 
 \begin{code}

-eRROR_ID
-  = pc_bottoming_Id errorIdKey pREL_ERR SLIT("error") errorTy
-eRROR_CSTRING_ID
-  = pc_bottoming_Id errorCStringIdKey pREL_ERR SLIT("errorCString") 
-                   (mkSigmaTy [openAlphaTyVar] [] (mkFunTy addrPrimTy openAlphaTy))
-pAT_ERROR_ID
-  = generic_ERROR_ID patErrorIdKey SLIT("patError")
-rEC_SEL_ERROR_ID
-  = generic_ERROR_ID recSelErrIdKey SLIT("recSelError")
-rEC_CON_ERROR_ID
-  = generic_ERROR_ID recConErrorIdKey SLIT("recConError")
-rEC_UPD_ERROR_ID
-  = generic_ERROR_ID recUpdErrorIdKey SLIT("recUpdError")
-iRREFUT_PAT_ERROR_ID
-  = generic_ERROR_ID irrefutPatErrorIdKey SLIT("irrefutPatError")
-nON_EXHAUSTIVE_GUARDS_ERROR_ID
-  = generic_ERROR_ID nonExhaustiveGuardsErrorIdKey SLIT("nonExhaustiveGuardsError")
-nO_METHOD_BINDING_ERROR_ID
-  = generic_ERROR_ID noMethodBindingErrorIdKey SLIT("noMethodBindingError")
-
-aBSENT_ERROR_ID
-  = pc_bottoming_Id absentErrorIdKey pREL_ERR SLIT("absentErr")
-       (mkSigmaTy [openAlphaTyVar] [] openAlphaTy)
-
-pAR_ERROR_ID
-  = pcMiscPrelId parErrorIdKey pREL_ERR SLIT("parError")
-    (mkSigmaTy [openAlphaTyVar] [] openAlphaTy) noCafNoTyGenIdInfo
+mkRuntimeErrorApp 
+       :: Id           -- Should be of type (forall a. Addr# -> a)
+                       --      where Addr# points to a UTF8 encoded string
+       -> Type         -- The type to instantiate 'a'
+       -> String       -- The string to print
+       -> CoreExpr
+
+mkRuntimeErrorApp err_id res_ty err_msg 
+  = mkApps (Var err_id) [Type res_ty, err_string]
+  where
+    err_string = Lit (MachStr (mkFastString (stringToUtf8 err_msg)))
+
+rEC_SEL_ERROR_ID               = mkRuntimeErrorId recSelErrorName
+rUNTIME_ERROR_ID               = mkRuntimeErrorId runtimeErrorName
+iRREFUT_PAT_ERROR_ID           = mkRuntimeErrorId irrefutPatErrorName
+rEC_CON_ERROR_ID               = mkRuntimeErrorId recConErrorName
+pAT_ERROR_ID                   = mkRuntimeErrorId patErrorName
+nO_METHOD_BINDING_ERROR_ID      = mkRuntimeErrorId noMethodBindingErrorName
+nON_EXHAUSTIVE_GUARDS_ERROR_ID = mkRuntimeErrorId nonExhaustiveGuardsErrorName
+
+-- The runtime error Ids take a UTF8-encoded string as argument
+mkRuntimeErrorId name = pc_bottoming_Id name runtimeErrorTy
+runtimeErrorTy               = mkSigmaTy [openAlphaTyVar] [] (mkFunTy addrPrimTy openAlphaTy)
+\end{code}
+
+\begin{code}
+eRROR_ID = pc_bottoming_Id errorName errorTy
+
+errorTy  :: Type
+errorTy  = mkSigmaTy [openAlphaTyVar] [] (mkFunTys [mkListTy charTy] openAlphaTy)
+    -- Notice the openAlphaTyVar.  It says that "error" can be applied
+    -- to unboxed as well as boxed types.  This is OK because it never
+    -- returns, so the return type is irrelevant.

 \end{code}
 
 
 \end{code}
 
 

@@ -822,39 +969,33 @@ pAR_ERROR_ID
 %************************************************************************
 
 \begin{code}
 %************************************************************************
 
 \begin{code}

-pcMiscPrelId :: Unique{-IdKey-} -> Module -> FAST_STRING -> Type -> IdInfo -> Id
-pcMiscPrelId key mod str ty info
-  = let
-       name = mkWiredInName mod (mkVarOcc str) key
-       imp  = mkVanillaGlobal name ty info -- the usual case...
-    in
-    imp
+pcMiscPrelId :: Name -> Type -> IdInfo -> Id
+pcMiscPrelId name ty info
+  = mkVanillaGlobal name ty info

     -- We lie and say the thing is imported; otherwise, we get into
     -- a mess with dependency analysis; e.g., core2stg may heave in
     -- random calls to GHCbase.unpackPS__.  If GHCbase is the module
     -- being compiled, then it's just a matter of luck if the definition
     -- will be in "the right place" to be in scope.
 
     -- We lie and say the thing is imported; otherwise, we get into
     -- a mess with dependency analysis; e.g., core2stg may heave in
     -- random calls to GHCbase.unpackPS__.  If GHCbase is the module
     -- being compiled, then it's just a matter of luck if the definition
     -- will be in "the right place" to be in scope.
 

-pc_bottoming_Id key mod name ty
- = id
+pc_bottoming_Id name ty
+ = pcMiscPrelId name ty bottoming_info

  where
  where

-    id = pcMiscPrelId key mod name ty bottoming_info
-    arity         = 1
-    strict_sig    = mkStrictSig id arity (mkTopDmdType [evalDmd] BotRes)
-    bottoming_info = noCafNoTyGenIdInfo `setNewStrictnessInfo` Just strict_sig
-       -- these "bottom" out, no matter what their arguments
-
-generic_ERROR_ID u n = pc_bottoming_Id u pREL_ERR n errorTy
+    bottoming_info = vanillaIdInfo `setAllStrictnessInfo` Just strict_sig
+       -- Do *not* mark them as NoCafRefs, because they can indeed have
+       -- CAF refs.  For example, pAT_ERROR_ID calls GHC.Err.untangle,
+       -- which has some CAFs
+       -- In due course we may arrange that these error-y things are
+       -- regarded by the GC as permanently live, in which case we
+       -- can give them NoCaf info.  As it is, any function that calls
+       -- any pc_bottoming_Id will itself have CafRefs, which bloats
+       -- SRTs.
+
+    strict_sig    = mkStrictSig (mkTopDmdType [evalDmd] BotRes)
+       -- These "bottom" out, no matter what their arguments

 
 (openAlphaTyVar:openBetaTyVar:_) = openAlphaTyVars
 openAlphaTy  = mkTyVarTy openAlphaTyVar
 openBetaTy   = mkTyVarTy openBetaTyVar
 
 (openAlphaTyVar:openBetaTyVar:_) = openAlphaTyVars
 openAlphaTy  = mkTyVarTy openAlphaTyVar
 openBetaTy   = mkTyVarTy openBetaTyVar

-
-errorTy  :: Type
-errorTy  = mkSigmaTy [openAlphaTyVar] [] (mkFunTys [mkListTy charTy] 
-                                                   openAlphaTy)
-    -- Notice the openAlphaTyVar.  It says that "error" can be applied
-    -- to unboxed as well as boxed types.  This is OK because it never
-    -- returns, so the return type is irrelevant.

 \end{code}
 
 \end{code}