X-Git-Url: https://git.stderr.nl/gitweb?a=blobdiff_plain;f=c%CE%BBash%2FCLasH%2FNormalize.hs;h=7fb0dc235d2a60d8a3e3798b8a655e9f6f3218f7;hb=10dfe589f40e65d51ca1585beecf00ae85169cae;hp=8b35bb986bd4265df2ec58e6988fc21f04fe64de;hpb=d42006e5be8a3d6e3970b84767856b77d00f7f73;p=matthijs%2Fmaster-project%2Fc%CE%BBash.git

diff --git "a/c\316\273ash/CLasH/Normalize.hs" "b/c\316\273ash/CLasH/Normalize.hs"
index 8b35bb9..7fb0dc2 100644
--- "a/c\316\273ash/CLasH/Normalize.hs"
+++ "b/c\316\273ash/CLasH/Normalize.hs"
@@ -4,7 +4,7 @@
 -- top level function "normalize", and defines the actual transformation passes that
 -- are performed.
 --
-module CLasH.Normalize (getNormalized, normalizeExpr) where
+module CLasH.Normalize (getNormalized, normalizeExpr, splitNormalized) where
 
 -- Standard modules
 import Debug.Trace
@@ -90,6 +90,30 @@ castprop expr = return expr
 -- Perform this transform everywhere
 castproptop = everywhere ("castprop", castprop)
 
+--------------------------------
+-- Cast simplification. Mostly useful for state packing and unpacking, but
+-- perhaps for others as well.
+--------------------------------
+castsimpl, castsimpltop :: Transform
+castsimpl expr@(Cast val ty) = do
+  -- Don't extract values that are already simpl
+  local_var <- Trans.lift $ is_local_var val
+  -- Don't extract values that are not representable, to prevent loops with
+  -- inlinenonrep
+  repr <- isRepr val
+  if (not local_var) && repr
+    then do
+      -- Generate a binder for the expression
+      id <- Trans.lift $ mkBinderFor val "castval"
+      -- Extract the expression
+      change $ Let (Rec [(id, val)]) (Cast (Var id) ty)
+    else
+      return expr
+-- Leave all other expressions unchanged
+castsimpl expr = return expr
+-- Perform this transform everywhere
+castsimpltop = everywhere ("castsimpl", castsimpl)
+
 --------------------------------
 -- let recursification
 --------------------------------
@@ -113,7 +137,7 @@ letsimpl expr@(Let (Rec binds) res) = do
     then do
       -- If the result is not a local var already (to prevent loops with
       -- ourselves), extract it.
-      id <- Trans.lift $ mkInternalVar "foo" (CoreUtils.exprType res)
+      id <- Trans.lift $ mkBinderFor res "foo"
       let bind = (id, res)
       change $ Let (Rec (bind:binds)) (Var id)
     else
@@ -157,6 +181,54 @@ letflattop = everywhere ("letflat", letflat)
 letremovetop :: Transform
 letremovetop = everywhere ("letremove", inlinebind (\(b, e) -> Trans.lift $ is_local_var e))
 
+--------------------------------
+-- Unused let binding removal
+--------------------------------
+letremoveunused, letremoveunusedtop :: Transform
+letremoveunused expr@(Let (Rec binds) res) = do
+  -- Filter out all unused binds.
+  let binds' = filter dobind binds
+  -- Only set the changed flag if binds got removed
+  changeif (length binds' /= length binds) (Let (Rec binds') res)
+    where
+      bound_exprs = map snd binds
+      -- For each bind check if the bind is used by res or any of the bound
+      -- expressions
+      dobind (bndr, _) = any (expr_uses_binders [bndr]) (res:bound_exprs)
+-- Leave all other expressions unchanged
+letremoveunused expr = return expr
+letremoveunusedtop = everywhere ("letremoveunused", letremoveunused)
+
+--------------------------------
+-- Identical let binding merging
+--------------------------------
+-- Merge two bindings in a let if they are identical 
+-- TODO: We would very much like to use GHC's CSE module for this, but that
+-- doesn't track if something changed or not, so we can't use it properly.
+letmerge, letmergetop :: Transform
+letmerge expr@(Let (Rec binds) res) = do
+  binds' <- domerge binds
+  return (Let (Rec binds') res)
+  where
+    domerge :: [(CoreBndr, CoreExpr)] -> TransformMonad [(CoreBndr, CoreExpr)]
+    domerge [] = return []
+    domerge (e:es) = do 
+      es' <- mapM (mergebinds e) es
+      es'' <- domerge es'
+      return (e:es'')
+
+    -- Uses the second bind to simplify the second bind, if applicable.
+    mergebinds :: (CoreBndr, CoreExpr) -> (CoreBndr, CoreExpr) -> TransformMonad (CoreBndr, CoreExpr)
+    mergebinds (b1, e1) (b2, e2)
+      -- Identical expressions? Replace the second binding with a reference to
+      -- the first binder.
+      | CoreUtils.cheapEqExpr e1 e2 = change $ (b2, Var b1)
+      -- Different expressions? Don't change
+      | otherwise = return (b2, e2)
+-- Leave all other expressions unchanged
+letmerge expr = return expr
+letmergetop = everywhere ("letmerge", letmerge)
+    
 --------------------------------
 -- Function inlining
 --------------------------------
@@ -189,7 +261,7 @@ scrutsimpl expr@(Case scrut b ty alts) = do
   repr <- isRepr scrut
   if repr
     then do
-      id <- Trans.lift $ mkInternalVar "scrut" (CoreUtils.exprType scrut)
+      id <- Trans.lift $ mkBinderFor scrut "scrut"
       change $ Let (Rec [(id, scrut)]) (Case (Var id) b ty alts)
     else
       return expr
@@ -283,7 +355,7 @@ casesimpl expr@(Case scrut b ty alts) = do
         -- prevent loops with inlinenonrep).
         if (not uses_bndrs) && (not local_var) && repr
           then do
-            id <- Trans.lift $ mkInternalVar "caseval" (CoreUtils.exprType expr)
+            id <- Trans.lift $ mkBinderFor expr "caseval"
             -- We don't flag a change here, since casevalsimpl will do that above
             -- based on Just we return here.
             return $ (Just (id, expr), Var id)
@@ -323,7 +395,7 @@ appsimpl expr@(App f arg) = do
   local_var <- Trans.lift $ is_local_var arg
   if repr && not local_var
     then do -- Extract representable arguments
-      id <- Trans.lift $ mkInternalVar "arg" (CoreUtils.exprType arg)
+      id <- Trans.lift $ mkBinderFor arg "arg"
       change $ Let (Rec [(id, arg)]) (App f (Var id))
     else -- Leave non-representable arguments unchanged
       return expr
@@ -473,7 +545,7 @@ funextracttop = everywhere ("funextract", funextract)
 
 
 -- What transforms to run?
-transforms = [argproptop, funextracttop, etatop, betatop, castproptop, letremovetop, letrectop, letsimpltop, letflattop, scrutsimpltop, casesimpltop, caseremovetop, inlinenonreptop, appsimpltop]
+transforms = [argproptop, funextracttop, etatop, betatop, castproptop, letremovetop, letrectop, letsimpltop, letflattop, scrutsimpltop, casesimpltop, caseremovetop, inlinenonreptop, appsimpltop, letmergetop, letremoveunusedtop, castsimpltop]
 
 -- | Returns the normalized version of the given function.
 getNormalized ::
@@ -502,9 +574,9 @@ normalizeExpr what expr = do
       -- the last let).
       let expr' = Let (Rec []) expr
       -- Normalize this expression
-      trace ("Transforming " ++ what ++ "\nBefore:\n\n" ++ showSDoc ( ppr expr' ) ++ "\n") $ return ()
+      trace (what ++ " before normalization:\n\n" ++ showSDoc ( ppr expr' ) ++ "\n") $ return ()
       expr'' <- dotransforms transforms expr'
-      trace ("\nAfter:\n\n" ++ showSDoc ( ppr expr')) $ return ()
+      trace ("\n" ++ what ++ " after normalization:\n\n" ++ showSDoc ( ppr expr'')) $ return ()
       return expr''
 
 -- | Get the value that is bound to the given binder at top level. Fails when
@@ -517,3 +589,15 @@ getBinding bndr = Utils.makeCached bndr tsBindings $ do
   -- If the binding isn't in the "cache" (bindings map), then we can't create
   -- it out of thin air, so return an error.
   error $ "Normalize.getBinding: Unknown function requested: " ++ show bndr
+
+-- | Split a normalized expression into the argument binders, top level
+--   bindings and the result binder.
+splitNormalized ::
+  CoreExpr -- ^ The normalized expression
+  -> ([CoreBndr], [Binding], CoreBndr)
+splitNormalized expr = 
+  case letexpr of
+    (Let (Rec binds) (Var res)) -> (args, binds, res)
+    _ -> error $ "Normalize.splitNormalized: Not in normal form: " ++ pprString expr ++ "\n"
+  where
+    (args, letexpr) = CoreSyn.collectBinders expr