X-Git-Url: https://git.stderr.nl/gitweb?a=blobdiff_plain;f=c%CE%BBash%2FCLasH%2FNormalize.hs;h=b2b4bd86f0080693d29f70183ef469083b15bdfc;hb=e17057696a5f74170dad6167867ee24d64d0854b;hp=6238b48b56527ef2c1fc975a049764469dc0ae40;hpb=b83ea5327202d46fc976e369ac303608cbc2330e;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 6238b48..b2b4bd8 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) where
+module CLasH.Normalize (getNormalized, normalizeExpr) where
 
 -- Standard modules
 import Debug.Trace
@@ -157,6 +157,24 @@ 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, _) = not $ any (expr_uses_binders [bndr]) (res:bound_exprs)
+-- Leave all other expressions unchanged
+letremoveunused expr = return expr
+letremoveunusedtop = everywhere ("letremoveunused", letremoveunused)
+
 --------------------------------
 -- Function inlining
 --------------------------------
@@ -473,7 +491,7 @@ 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, letremoveunusedtop]
 
 -- | Returns the normalized version of the given function.
 getNormalized ::
@@ -488,14 +506,23 @@ getNormalized bndr = Utils.makeCached bndr tsNormalized $ do
       error $ "\nNormalize.normalizeBind: Function " ++ show bndr ++ " is polymorphic, can't normalize"
     else do
       expr <- getBinding bndr
+      normalizeExpr (show bndr) expr
+
+-- | Normalize an expression
+normalizeExpr ::
+  String -- ^ What are we normalizing? For debug output only.
+  -> CoreSyn.CoreExpr -- ^ The expression to normalize 
+  -> TranslatorSession CoreSyn.CoreExpr -- ^ The normalized expression
+
+normalizeExpr what expr = do
       -- Introduce an empty Let at the top level, so there will always be
       -- a let in the expression (none of the transformations will remove
       -- the last let).
       let expr' = Let (Rec []) expr
       -- Normalize this expression
-      trace ("Transforming " ++ (show bndr) ++ "\nBefore:\n\n" ++ showSDoc ( ppr expr' ) ++ "\n") $ return ()
+      trace ("Transforming " ++ what ++ "\nBefore:\n\n" ++ showSDoc ( ppr expr' ) ++ "\n") $ return ()
       expr'' <- dotransforms transforms expr'
-      trace ("\nAfter:\n\n" ++ showSDoc ( ppr expr')) $ return ()
+      trace ("\nAfter:\n\n" ++ showSDoc ( ppr expr'')) $ return ()
       return expr''
 
 -- | Get the value that is bound to the given binder at top level. Fails when