Initial checkin of HetMet / -XModalTypes modifications

[ghc-hetmet.git] / compiler / deSugar / Desugar.lhs

diff --git a/compiler/deSugar/Desugar.lhs b/compiler/deSugar/Desugar.lhs
index 64fff0d..7d0be3f 100644 (file)
--- a/compiler/deSugar/Desugar.lhs
+++ b/compiler/deSugar/Desugar.lhs
@@ -8,6 +8,7 @@ The Desugarer: turning HsSyn into Core.
 \begin{code}
 module Desugar ( deSugar, deSugarExpr ) where
 
 \begin{code}
 module Desugar ( deSugar, deSugarExpr ) where
 

+import TysWiredIn (unitDataConId)

 import DynFlags
 import StaticFlags
 import HscTypes
 import DynFlags
 import StaticFlags
 import HscTypes

@@ -17,6 +18,7 @@ import MkIface
 import Id
 import Name
 import CoreSyn
 import Id
 import Name
 import CoreSyn

+import CoreSubst

 import PprCore
 import DsMonad
 import DsExpr
 import PprCore
 import DsMonad
 import DsExpr

@@ -27,16 +29,20 @@ import DsExpr               ()      -- Forces DsExpr to be compiled; DsBinds only
 import Module
 import RdrName
 import NameSet
 import Module
 import RdrName
 import NameSet

+import NameEnv

 import Rules
 import CoreMonad       ( endPass, CoreToDo(..) )
 import ErrUtils
 import Outputable
 import SrcLoc
 import Rules
 import CoreMonad       ( endPass, CoreToDo(..) )
 import ErrUtils
 import Outputable
 import SrcLoc

-import Maybes
-import FastString

 import Coverage
 import Coverage

-
+import Util
+import MonadUtils
+import OrdList
+import Data.List

 import Data.IORef
 import Data.IORef

+import DsHetMet
+import Control.Exception ( catch, ErrorCall, Exception(..) )

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

@@ -65,6 +71,8 @@ deSugar hsc_env
                            tcg_warns        = warns,
                            tcg_anns         = anns,
                            tcg_binds        = binds,
                            tcg_warns        = warns,
                            tcg_anns         = anns,
                            tcg_binds        = binds,

+                           tcg_imp_specs    = imp_specs,
+                           tcg_ev_binds     = ev_binds,

                            tcg_fords        = fords,
                            tcg_rules        = rules,
                            tcg_insts        = insts,
                            tcg_fords        = fords,
                            tcg_rules        = rules,
                            tcg_insts        = insts,

@@ -83,44 +91,74 @@ deSugar hsc_env
               <- case target of
                   HscNothing ->
                        return (emptyMessages,
               <- case target of
                   HscNothing ->
                        return (emptyMessages,

-                               Just ([], [], NoStubs, hpcInfo, emptyModBreaks))
+                               Just ([], nilOL, [], NoStubs, hpcInfo, emptyModBreaks))

                    _        -> do
                      (binds_cvr,ds_hpc_info, modBreaks)
                         <- if (opt_Hpc
                                  || target == HscInterpreted)
                               && (not (isHsBoot hsc_src))
                    _        -> do
                      (binds_cvr,ds_hpc_info, modBreaks)
                         <- if (opt_Hpc
                                  || target == HscInterpreted)
                               && (not (isHsBoot hsc_src))

-                              then addCoverageTicksToBinds dflags mod mod_loc (typeEnvTyCons type_env) binds 
+                              then addCoverageTicksToBinds dflags mod mod_loc
+                                                           (typeEnvTyCons type_env) binds 

                               else return (binds, hpcInfo, emptyModBreaks)
                      initDs hsc_env mod rdr_env type_env $ do
                               else return (binds, hpcInfo, emptyModBreaks)
                      initDs hsc_env mod rdr_env type_env $ do

-                        core_prs <- dsTopLHsBinds auto_scc binds_cvr
-                        (ds_fords, foreign_prs) <- dsForeigns fords
-                        let all_prs = foreign_prs ++ core_prs
-                        ds_rules <- mapM dsRule rules
-                        return (all_prs, catMaybes ds_rules, ds_fords, ds_hpc_info, modBreaks)
+                      do { ds_ev_binds <- dsEvBinds ev_binds
+                         ; core_prs <- dsTopLHsBinds auto_scc binds_cvr
+                          ; (spec_prs, spec_rules) <- dsImpSpecs imp_specs
+                         ; (ds_fords, foreign_prs) <- dsForeigns fords
+                         ; rules <- mapMaybeM dsRule rules
+                         ; return ( ds_ev_binds
+                                   , foreign_prs `appOL` core_prs `appOL` spec_prs
+                                   , spec_rules ++ rules
+                                   , ds_fords, ds_hpc_info, modBreaks) }

 
        ; case mb_res of {
           Nothing -> return (msgs, Nothing) ;
 
        ; case mb_res of {
           Nothing -> return (msgs, Nothing) ;

-          Just (all_prs, ds_rules, ds_fords,ds_hpc_info, modBreaks) -> do
+          Just (ds_ev_binds, all_prs, all_rules, ds_fords,ds_hpc_info, modBreaks) -> do

 
        {       -- Add export flags to bindings
          keep_alive <- readIORef keep_var
 
        {       -- Add export flags to bindings
          keep_alive <- readIORef keep_var

-       ; let final_prs = addExportFlags target export_set
-                                 keep_alive all_prs 
-             ds_binds  = [Rec final_prs]
+       ; let (rules_for_locals, rules_for_imps) 
+                   = partition isLocalRule all_rules
+              final_prs = addExportFlagsAndRules target
+                             export_set keep_alive rules_for_locals (fromOL all_prs)
+
+              final_pgm = combineEvBinds ds_ev_binds final_prs

        -- Notice that we put the whole lot in a big Rec, even the foreign binds
        -- When compiling PrelFloat, which defines data Float = F# Float#
        -- we want F# to be in scope in the foreign marshalling code!
        -- You might think it doesn't matter, but the simplifier brings all top-level
        -- things into the in-scope set before simplifying; so we get no unfolding for F#!
 
        -- Notice that we put the whole lot in a big Rec, even the foreign binds
        -- When compiling PrelFloat, which defines data Float = F# Float#
        -- we want F# to be in scope in the foreign marshalling code!
        -- You might think it doesn't matter, but the simplifier brings all top-level
        -- things into the in-scope set before simplifying; so we get no unfolding for F#!
 

-       -- Lint result if necessary
-       ; endPass dflags CoreDesugar ds_binds ds_rules
-
-       -- Dump output
-       ; doIfSet (dopt Opt_D_dump_ds dflags) 
-                 (printDump (ppr_ds_rules ds_rules))
-
-        ; used_names <- mkUsedNames tcg_env
+       -- Lint result if necessary, and print
+        ; dumpIfSet_dyn dflags Opt_D_dump_ds "Desugared, before opt" $
+               (vcat [ pprCoreBindings final_pgm
+                     , pprRules rules_for_imps ])
+
+       ; (ds_binds, ds_rules_for_imps) <- simpleOptPgm dflags final_pgm rules_for_imps
+                        -- The simpleOptPgm gets rid of type 
+                        -- bindings plus any stupid dead code
+{-
+        ; dumpIfSet_dyn dflags Opt_D_dump_proof "input to flattener" (text $ showSDoc $ pprCoreBindings ds_binds)
+        ; let uhandler (err::ErrorCall)
+                      = dumpIfSet_dyn dflags Opt_D_dump_proof "System FC Proof"
+                                       (text $ "\\begin{verbatim}\n" ++
+                                               show err ++
+                                               "\\end{verbatim}\n\n")
+          in (dumpIfSet_dyn dflags Opt_D_dump_proof "System FC Proof" $
+               (vcat (map (\ bind -> let e = case bind of
+                                               NonRec b e -> e
+                                               Rec    lve -> Let (Rec lve) (Var unitDataConId)
+                                     in text $ "\\begin{verbatim}\n" ++
+                                               (showSDoc $ pprCoreBindings ds_binds) ++
+                                               "\\end{verbatim}\n\n" ++
+                                               "$$\n"++
+                                               (core2proofAndShow e) ++
+                                               "$$\n"
+                          ) ds_binds))) `Control.Exception.catch` uhandler
+-}
+       ; endPass dflags CoreDesugar ds_binds ds_rules_for_imps
+
+        ; let used_names = mkUsedNames tcg_env

        ; deps <- mkDependencies tcg_env
 
         ; let mod_guts = ModGuts {     
        ; deps <- mkDependencies tcg_env
 
         ; let mod_guts = ModGuts {     

@@ -139,7 +177,7 @@ deSugar hsc_env
                mg_fam_insts    = fam_insts,
                mg_inst_env     = inst_env,
                mg_fam_inst_env = fam_inst_env,
                mg_fam_insts    = fam_insts,
                mg_inst_env     = inst_env,
                mg_fam_inst_env = fam_inst_env,

-               mg_rules        = ds_rules,
+               mg_rules        = ds_rules_for_imps,

                mg_binds        = ds_binds,
                mg_foreign      = ds_fords,
                mg_hpc_info     = ds_hpc_info,
                mg_binds        = ds_binds,
                mg_foreign      = ds_fords,
                mg_hpc_info     = ds_hpc_info,

@@ -149,6 +187,38 @@ deSugar hsc_env
         ; return (msgs, Just mod_guts)
        }}}
 
         ; return (msgs, Just mod_guts)
        }}}
 

+dsImpSpecs :: [LTcSpecPrag] -> DsM (OrdList (Id,CoreExpr), [CoreRule])
+dsImpSpecs imp_specs
+ = do { spec_prs <- mapMaybeM (dsSpec Nothing) imp_specs
+      ; let (spec_binds, spec_rules) = unzip spec_prs
+      ; return (concatOL spec_binds, spec_rules) }
+
+combineEvBinds :: [DsEvBind] -> [(Id,CoreExpr)] -> [CoreBind]
+-- Top-level bindings can include coercion bindings, but not via superclasses
+-- See Note [Top-level evidence]
+combineEvBinds [] val_prs 
+  = [Rec val_prs]
+combineEvBinds (LetEvBind (NonRec b r) : bs) val_prs
+  | isId b    = combineEvBinds bs ((b,r):val_prs)
+  | otherwise = NonRec b r : combineEvBinds bs val_prs
+combineEvBinds (LetEvBind (Rec prs) : bs) val_prs 
+  = combineEvBinds bs (prs ++ val_prs)
+combineEvBinds (CaseEvBind x _ _ : _) _
+  = pprPanic "topEvBindPairs" (ppr x)
+\end{code}
+
+Note [Top-level evidence]
+~~~~~~~~~~~~~~~~~~~~~~~~~
+Top-level evidence bindings may be mutually recursive with the top-level value
+bindings, so we must put those in a Rec.  But we can't put them *all* in a Rec
+because the occurrence analyser doesn't teke account of type/coercion variables
+when computing dependencies.  
+
+So we pull out the type/coercion variables (which are in dependency order),
+and Rec the rest.
+
+
+\begin{code}

 mkAutoScc :: DynFlags -> Module -> NameSet -> AutoScc
 mkAutoScc dflags mod exports
   | not opt_SccProfilingOn     -- No profiling
 mkAutoScc :: DynFlags -> Module -> NameSet -> AutoScc
 mkAutoScc dflags mod exports
   | not opt_SccProfilingOn     -- No profiling

@@ -173,7 +243,7 @@ deSugarExpr :: HscEnv
 
 deSugarExpr hsc_env this_mod rdr_env type_env tc_expr = do
     let dflags = hsc_dflags hsc_env
 
 deSugarExpr hsc_env this_mod rdr_env type_env tc_expr = do
     let dflags = hsc_dflags hsc_env

-    showPass dflags "Desugar"
+    showPass dflags "Desugarz"

 
     -- Do desugaring
     (msgs, mb_core_expr) <- initDs hsc_env this_mod rdr_env type_env $
 
     -- Do desugaring
     (msgs, mb_core_expr) <- initDs hsc_env this_mod rdr_env type_env $

@@ -183,40 +253,51 @@ deSugarExpr hsc_env this_mod rdr_env type_env tc_expr = do
       Nothing   -> return (msgs, Nothing)
       Just expr -> do
 
       Nothing   -> return (msgs, Nothing)
       Just expr -> do
 

+{-

         -- Dump output
         -- Dump output

-        dumpIfSet_dyn dflags Opt_D_dump_ds "Desugared" (pprCoreExpr expr)
+        dumpIfSet_dyn dflags Opt_D_dump_ds    "Desugared"            (text $ "$$\n"++(core2proofAndShow expr)++"$$\n")
+-}

 
         return (msgs, Just expr)
 
         return (msgs, Just expr)

+\end{code}

 
 

---             addExportFlags
--- Set the no-discard flag if either 
---     a) the Id is exported
---     b) it's mentioned in the RHS of an orphan rule
---     c) it's in the keep-alive set
---
--- It means that the binding won't be discarded EVEN if the binding
--- ends up being trivial (v = w) -- the simplifier would usually just 
--- substitute w for v throughout, but we don't apply the substitution to
--- the rules (maybe we should?), so this substitution would make the rule
--- bogus.
-
--- You might wonder why exported Ids aren't already marked as such;
--- it's just because the type checker is rather busy already and
--- I didn't want to pass in yet another mapping.
-
-addExportFlags :: HscTarget -> NameSet -> NameSet -> [(Id, t)]
-               -> [(Id, t)]
-addExportFlags target exports keep_alive prs
-  = [(add_export bndr, rhs) | (bndr,rhs) <- prs]
+%************************************************************************
+%*                                                                     *
+%*             Add rules and export flags to binders
+%*                                                                     *
+%************************************************************************
+
+\begin{code}
+addExportFlagsAndRules 
+    :: HscTarget -> NameSet -> NameSet -> [CoreRule]
+    -> [(Id, t)] -> [(Id, t)]
+addExportFlagsAndRules target exports keep_alive rules prs
+  = mapFst add_one prs

   where
   where

-    add_export bndr
-       | dont_discard bndr = setIdExported bndr
+    add_one bndr = add_rules name (add_export name bndr)
+       where
+         name = idName bndr
+
+    ---------- Rules --------
+       -- See Note [Attach rules to local ids]
+       -- NB: the binder might have some existing rules,
+       -- arising from specialisation pragmas
+    add_rules name bndr
+       | Just rules <- lookupNameEnv rule_base name
+       = bndr `addIdSpecialisations` rules
+       | otherwise
+       = bndr
+    rule_base = extendRuleBaseList emptyRuleBase rules
+
+    ---------- Export flag --------
+    -- See Note [Adding export flags]
+    add_export name bndr
+       | dont_discard name = setIdExported bndr

        | otherwise         = bndr
 
        | otherwise         = bndr
 

-    dont_discard bndr = is_exported name
+    dont_discard :: Name -> Bool
+    dont_discard name = is_exported name

                     || name `elemNameSet` keep_alive
                     || name `elemNameSet` keep_alive

-                    where
-                       name = idName bndr

 
        -- In interactive mode, we don't want to discard any top-level
        -- entities at all (eg. do not inline them away during
 
        -- In interactive mode, we don't want to discard any top-level
        -- entities at all (eg. do not inline them away during

@@ -228,15 +309,44 @@ addExportFlags target exports keep_alive prs
     is_exported :: Name -> Bool
     is_exported | target == HscInterpreted = isExternalName
                | otherwise                = (`elemNameSet` exports)
     is_exported :: Name -> Bool
     is_exported | target == HscInterpreted = isExternalName
                | otherwise                = (`elemNameSet` exports)

-
-ppr_ds_rules :: [CoreRule] -> SDoc
-ppr_ds_rules [] = empty
-ppr_ds_rules rules
-  = blankLine $$ text "-------------- DESUGARED RULES -----------------" $$
-    pprRules rules

 \end{code}
 
 
 \end{code}
 
 

+Note [Adding export flags]
+~~~~~~~~~~~~~~~~~~~~~~~~~~
+Set the no-discard flag if either 
+       a) the Id is exported
+       b) it's mentioned in the RHS of an orphan rule
+       c) it's in the keep-alive set
+
+It means that the binding won't be discarded EVEN if the binding
+ends up being trivial (v = w) -- the simplifier would usually just 
+substitute w for v throughout, but we don't apply the substitution to
+the rules (maybe we should?), so this substitution would make the rule
+bogus.
+
+You might wonder why exported Ids aren't already marked as such;
+it's just because the type checker is rather busy already and
+I didn't want to pass in yet another mapping.
+
+Note [Attach rules to local ids]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Find the rules for locally-defined Ids; then we can attach them
+to the binders in the top-level bindings
+
+Reason
+  - It makes the rules easier to look up
+  - It means that transformation rules and specialisations for
+    locally defined Ids are handled uniformly
+  - It keeps alive things that are referred to only from a rule
+    (the occurrence analyser knows about rules attached to Ids)
+  - It makes sure that, when we apply a rule, the free vars
+    of the RHS are more likely to be in scope
+  - The imported rules are carried in the in-scope set
+    which is extended on each iteration by the new wave of
+    local binders; any rules which aren't on the binding will
+    thereby get dropped
+

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

@@ -250,28 +360,28 @@ dsRule (L loc (HsRule name act vars lhs _tv_lhs rhs _fv_rhs))
   = putSrcSpanDs loc $ 
     do { let bndrs' = [var | RuleBndr (L _ var) <- vars]
 
   = putSrcSpanDs loc $ 
     do { let bndrs' = [var | RuleBndr (L _ var) <- vars]
 

-       ; lhs'  <- unsetOptM Opt_EnableRewriteRules $
-                  dsLExpr lhs  -- Note [Desugaring RULE lhss]
+        ; lhs' <- unsetOptM Opt_EnableRewriteRules $
+                  unsetOptM Opt_WarnIdentities $
+                  dsLExpr lhs   -- Note [Desugaring RULE left hand sides]

 
 

-       ; rhs'  <- dsLExpr rhs
+       ; rhs' <- dsLExpr rhs

 
        -- Substitute the dict bindings eagerly,
        -- and take the body apart into a (f args) form
 
        -- Substitute the dict bindings eagerly,
        -- and take the body apart into a (f args) form

-       ; case decomposeRuleLhs (mkLams bndrs' lhs') of {
-               Nothing -> do { warnDs msg; return Nothing } ;
-               Just (bndrs, fn_id, args) -> do
+       ; case decomposeRuleLhs bndrs' lhs' of {
+               Left msg -> do { warnDs msg; return Nothing } ;
+               Right (final_bndrs, fn_id, args) -> do

        
        

-       { let local_rule = isLocalId fn_id
+       { let is_local = isLocalId fn_id

                -- NB: isLocalId is False of implicit Ids.  This is good becuase
                -- we don't want to attach rules to the bindings of implicit Ids, 
                -- because they don't show up in the bindings until just before code gen
                -- NB: isLocalId is False of implicit Ids.  This is good becuase
                -- we don't want to attach rules to the bindings of implicit Ids, 
                -- because they don't show up in the bindings until just before code gen

-             fn_name = idName fn_id
-             rule    = mkRule local_rule name act fn_name bndrs args rhs' 
+             fn_name   = idName fn_id
+             final_rhs = simpleOptExpr rhs'    -- De-crap it
+             rule      = mkRule False {- Not auto -} is_local 
+                                 name act fn_name final_bndrs args final_rhs

        ; return (Just rule)
        } } }
        ; return (Just rule)
        } } }

-  where
-    msg = hang (ptext (sLit "RULE left-hand side too complicated to desugar; ignored"))
-            2 (ppr lhs)

 \end{code}
 
 Note [Desugaring RULE left hand sides]
 \end{code}
 
 Note [Desugaring RULE left hand sides]

@@ -283,3 +393,7 @@ of cons's. We can achieve that slightly indirectly by
 switching off EnableRewriteRules.  See DsExpr.dsExplicitList.
 
 That keeps the desugaring of list comprehensions simple too.
 switching off EnableRewriteRules.  See DsExpr.dsExplicitList.
 
 That keeps the desugaring of list comprehensions simple too.

+
+Nor do we want to warn of conversion identities on the LHS;
+the rule is precisly to optimise them:
+  {-# RULES "fromRational/id" fromRational = id :: Rational -> Rational #-}