Switch order of clauses in retvalsimpl to match thesis.

[matthijs/master-project/cλash.git] / cλash / CLasH / Normalize.hs

diff --git a/cλash/CLasH/Normalize.hs b/cλash/CLasH/Normalize.hs
index 75ab7380f0bca63f40bac1c4f423ef356e8c2c19..85be0d0ef61ae37050835a9784185a538db04990 100644 (file)
--- a/cλash/CLasH/Normalize.hs
+++ b/cλash/CLasH/Normalize.hs
@@ -121,11 +121,23 @@ castsimpl c expr = return expr
 castsimpltop = everywhere ("castsimpl", castsimpl)
 
 --------------------------------
--- Ensure that a function that just returns another function (or rather,
--- another top-level binder) is still properly normalized. This is a temporary
--- solution, we should probably integrate this pass with lambdasimpl and
--- letsimpl instead.
+-- Return value simplification
 --------------------------------
+-- Ensure the return value of a function follows proper normal form. eta
+-- expansion ensures the body starts with lambda abstractions, this
+-- transformation ensures that the lambda abstractions always contain a
+-- recursive let and that, when the return value is representable, the
+-- let contains a local variable reference in its body.
+retvalsimpl c expr | all (== LambdaBody) c && not (is_lam expr) && not (is_let expr) = do
+  local_var <- Trans.lift $ is_local_var expr
+  repr <- isRepr expr
+  if not local_var && repr
+    then do
+      id <- Trans.lift $ mkBinderFor expr "res" 
+      change $ Let (Rec [(id, expr)]) (Var id)
+    else
+      return expr
+
 retvalsimpl c expr@(Let (Rec binds) body) | all (== LambdaBody) c = do
   -- Don't extract values that are already a local variable, to prevent
   -- loops with ourselves.
@@ -140,15 +152,6 @@ retvalsimpl c expr@(Let (Rec binds) body) | all (== LambdaBody) c = do
     else
       return expr
 
-retvalsimpl c expr | all (== LambdaBody) c && not (is_lam expr) && not (is_let expr) = do
-  local_var <- Trans.lift $ is_local_var expr
-  repr <- isRepr expr
-  if not local_var && repr
-    then do
-      id <- Trans.lift $ mkBinderFor expr "res" 
-      change $ Let (Rec [(id, expr)]) (Var id)
-    else
-      return expr
 
 -- Leave all other expressions unchanged
 retvalsimpl c expr = return expr