CoreMonad: add lookupOrigCoreM, modeled after IfaceEnv.lookupOrig

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

diff --git a/compiler/simplCore/CoreMonad.lhs b/compiler/simplCore/CoreMonad.lhs
index bb598c6..67a0991 100644 (file)
--- a/compiler/simplCore/CoreMonad.lhs
+++ b/compiler/simplCore/CoreMonad.lhs
@@ -43,6 +43,8 @@ module CoreMonad (
     debugTraceMsg, debugTraceMsgS,
     dumpIfSet_dyn, 
 
+    lookupOrigCoreM,
+
 #ifdef GHCI
     -- * Getting 'Name's
     thNameToGhcName
@@ -90,6 +92,11 @@ import Data.Word
 import Control.Monad
 
 import Prelude hiding   ( read )
+import OccName
+import IfaceEnv
+import Name
+import SrcLoc
+import Control.Exception.Base
 
 #ifdef GHCI
 import {-# SOURCE #-} TcSplice ( lookupThName_maybe )
@@ -370,13 +377,21 @@ getCoreToDo dflags
 
     simpl_phase phase names iter
       = CoreDoPasses
-          [ maybe_strictness_before phase
+      $   [ maybe_strictness_before phase
           , CoreDoSimplify iter
                 (base_mode { sm_phase = Phase phase
                            , sm_names = names })
 
-          , maybe_rule_check (Phase phase)
-          ]
+          , maybe_rule_check (Phase phase) ]
+
+          -- Vectorisation can introduce a fair few common sub expressions involving 
+          --  DPH primitives. For example, see the Reverse test from dph-examples.
+          --  We need to eliminate these common sub expressions before their definitions
+          --  are inlined in phase 2. The CSE introduces lots of  v1 = v2 bindings, 
+          --  so we also run simpl_gently to inline them.
+      ++  (if dopt Opt_Vectorise dflags && phase == 3
+           then [CoreCSE, simpl_gently]
+           else [])
 
     vectorisation
       = runWhen (dopt Opt_Vectorise dflags) $
@@ -401,7 +416,7 @@ getCoreToDo dflags
     simpl_gently = CoreDoSimplify max_iter
                        (base_mode { sm_phase = InitialPhase
                                   , sm_names = ["Gentle"]
-                                  , sm_rules = True     -- Note [RULEs enabled in SimplGently]
+                                  , sm_rules = rules_on   -- Note [RULEs enabled in SimplGently]
                                   , sm_inline = False
                                   , sm_case_case = False })
                           -- Don't do case-of-case transformations.
@@ -568,9 +583,6 @@ RULES are enabled when doing "gentle" simplification.  Two reasons:
 But watch out: list fusion can prevent floating.  So use phase control
 to switch off those rules until after floating.
 
-Currently (Oct10) I think that sm_rules is always True, so we
-could remove it.
-
 
 %************************************************************************
 %*                                                                     *
@@ -1116,3 +1128,29 @@ thNameToGhcName th_name = do
     liftIO $ initTcForLookup hsc_env (lookupThName_maybe th_name)
 #endif
 \end{code}
+
+\begin{code}
+updNameCache' :: (NameCache -> (NameCache, a)) -> CoreM a
+updNameCache' upd_fn = do
+  HscEnv { hsc_NC = nc_var } <- getHscEnv
+  r  <- liftIO $ atomicModifyIORef nc_var upd_fn
+  r' <- liftIO $ readIORef nc_var
+  _  <- liftIO $ evaluate r'
+  return r
+
+-- cut-and-pasted from IfaceEnv, where it lives in the TcRn monad rather than CoreM
+lookupOrigCoreM :: Module -> OccName -> CoreM Name
+lookupOrigCoreM mod occ
+  = do         { mod `seq` occ `seq` return () 
+        ; updNameCache' $ \name_cache ->
+            case lookupOrigNameCache (nsNames name_cache) mod occ of {
+             Just name -> (name_cache, name);
+             Nothing   ->
+              case takeUniqFromSupply (nsUniqs name_cache) of {
+              (uniq, us) ->
+                  let
+                    name      = mkExternalName uniq mod occ noSrcSpan
+                    new_cache = extendNameCache (nsNames name_cache) mod occ name
+                  in (name_cache{ nsUniqs = us, nsNames = new_cache }, name)
+    }}}
+\end{code}
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