X-Git-Url: https://git.stderr.nl/gitweb?a=blobdiff_plain;f=c%CE%BBash%2FCLasH%2FNormalize.hs;h=192ed55cf0500c1655fb9b1adba6c3a79512d596;hb=60174903a7e142bf05586c24498b7e064a7118ff;hp=cd3ba5817ca1e04384185d74dd7e50f113059d61;hpb=0e3e9200536bf038c77f43e43a678d408afee466;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 cd3ba58..192ed55 100644
--- "a/c\316\273ash/CLasH/Normalize.hs"
+++ "b/c\316\273ash/CLasH/Normalize.hs"
@@ -115,6 +115,36 @@ castsimpl expr = return expr
 -- Perform this transform everywhere
 castsimpltop = everywhere ("castsimpl", castsimpl)
 
+
+--------------------------------
+-- Lambda simplication
+--------------------------------
+-- Ensure that a lambda always evaluates to a let expressions or a simple
+-- variable reference.
+lambdasimpl, lambdasimpltop :: Transform
+-- Don't simplify a lambda that evaluates to let, since this is already
+-- normal form (and would cause infinite loops).
+lambdasimpl expr@(Lam _ (Let _ _)) = return expr
+-- Put the of a lambda in its own binding, but not when the expression is
+-- already a local variable, or not representable (to prevent loops with
+-- inlinenonrep).
+lambdasimpl expr@(Lam bndr res) = do
+  repr <- isRepr res
+  local_var <- Trans.lift $ is_local_var res
+  if not local_var && repr
+    then do
+      id <- Trans.lift $ mkBinderFor res "res"
+      change $ Lam bndr (Let (NonRec id res) (Var id))
+    else
+      -- If the result is already a local var or not representable, don't
+      -- extract it.
+      return expr
+
+-- Leave all other expressions unchanged
+lambdasimpl expr = return expr
+-- Perform this transform everywhere
+lambdasimpltop = everywhere ("lambdasimpl", lambdasimpl)
+
 --------------------------------
 -- let derecursification
 --------------------------------
@@ -175,8 +205,22 @@ letsimpltop = everywhere ("letsimpl", letsimpl)
 -- to:
 -- let b' = expr' in (let b = res' in res)
 letflat, letflattop :: Transform
-letflat (Let (NonRec b (Let (NonRec b' expr')  res')) res) = 
-  change $ Let (NonRec b' expr') (Let (NonRec b res') res)
+-- Turn a nonrec let that binds a let into two nested lets.
+letflat (Let (NonRec b (Let binds  res')) res) = 
+  change $ Let binds (Let (NonRec b res') res)
+letflat (Let (Rec binds) expr) = do
+  -- Flatten each binding.
+  binds' <- Utils.concatM $ Monad.mapM flatbind binds
+  -- Return the new let. We don't use change here, since possibly nothing has
+  -- changed. If anything has changed, flatbind has already flagged that
+  -- change.
+  return $ Let (Rec binds') expr
+  where
+    -- Turns a binding of a let into a multiple bindings, or any other binding
+    -- into a list with just that binding
+    flatbind :: (CoreBndr, CoreExpr) -> TransformMonad [(CoreBndr, CoreExpr)]
+    flatbind (b, Let (Rec binds) expr) = change ((b, expr):binds)
+    flatbind (b, expr) = return [(b, expr)]
 -- Leave all other expressions unchanged
 letflat expr = return expr
 -- Perform this transform everywhere
@@ -204,6 +248,11 @@ letremovesimpletop = everywhere ("letremovesimple", inlinebind (\(b, e) -> Trans
 -- Unused let binding removal
 --------------------------------
 letremoveunused, letremoveunusedtop :: Transform
+letremoveunused expr@(Let (NonRec b bound) res) = do
+  let used = expr_uses_binders [b] res
+  if used
+    then return expr
+    else change res
 letremoveunused expr@(Let (Rec binds) res) = do
   -- Filter out all unused binds.
   let binds' = filter dobind binds
@@ -218,6 +267,7 @@ letremoveunused expr@(Let (Rec binds) res) = do
 letremoveunused expr = return expr
 letremoveunusedtop = everywhere ("letremoveunused", letremoveunused)
 
+{-
 --------------------------------
 -- Identical let binding merging
 --------------------------------
@@ -248,7 +298,8 @@ letmerge expr@(Let _ _) = do
 -- Leave all other expressions unchanged
 letmerge expr = return expr
 letmergetop = everywhere ("letmerge", letmerge)
-    
+-}
+
 --------------------------------
 -- Function inlining
 --------------------------------
@@ -308,7 +359,7 @@ casesimpl expr@(Case scrut b ty alts) = do
   (bindingss, alts') <- (Monad.liftM unzip) $ mapM doalt alts
   let bindings = concat bindingss
   -- Replace the case with a let with bindings and a case
-  let newlet = (Let (Rec bindings) (Case scrut b ty alts'))
+  let newlet = mkNonRecLets bindings (Case scrut b ty alts')
   -- If there are no non-wild binders, or this case is already a simple
   -- selector (i.e., a single alt with exactly one binding), already a simple
   -- selector altan no bindings (i.e., no wild binders in the original case),
@@ -331,7 +382,7 @@ casesimpl expr@(Case scrut b ty alts) = do
     (exprbinding_maybe, expr') <- doexpr expr uses_bndrs
     -- Create a new alternative
     let newalt = (con, newbndrs, expr')
-    let bindings = Maybe.catMaybes (exprbinding_maybe : bindings_maybe)
+    let bindings = Maybe.catMaybes (bindings_maybe ++ [exprbinding_maybe])
     return (bindings, newalt)
     where
       -- Make wild alternatives for each binder
@@ -565,7 +616,7 @@ funextracttop = everywhere ("funextract", funextract)
 
 
 -- What transforms to run?
-transforms = [argproptop, funextracttop, etatop, betatop, castproptop, letremovesimpletop, letderectop, letremovetop, letsimpltop, letflattop, scrutsimpltop, casesimpltop, caseremovetop, inlinenonreptop, appsimpltop, letmergetop, letremoveunusedtop, castsimpltop]
+transforms = [argproptop, funextracttop, etatop, betatop, castproptop, letremovesimpletop, letderectop, letremovetop, letsimpltop, letflattop, scrutsimpltop, casesimpltop, caseremovetop, inlinenonreptop, appsimpltop, letremoveunusedtop, castsimpltop, lambdasimpltop]
 
 -- | Returns the normalized version of the given function.
 getNormalized ::