Add TODO.

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

diff --git a/cλash/CLasH/Normalize.hs b/cλash/CLasH/Normalize.hs
index ea1051694f52c405e3fd1d965b578a082389ec27..a06094b9927b7b855ad1e703533f5166273227d2 100644 (file)
--- a/cλash/CLasH/Normalize.hs
+++ b/cλash/CLasH/Normalize.hs
@@ -616,10 +616,18 @@ argprop expr@(App _ _) | is_var fexpr = do
           let free_vars = VarSet.varSetElems $ CoreFVs.exprSomeFreeVars interesting arg
           -- Mark the current expression as changed
           setChanged
+          -- TODO: Clone the free_vars (and update references in arg), since
+          -- this might cause conflicts if two arguments that are propagated
+          -- share a free variable. Also, we are now introducing new variables
+          -- into a function that are not fresh, which violates the binder
+          -- uniqueness invariant.
           return (map Var free_vars, free_vars, arg)
         else do
           -- Representable types will not be propagated, and arguments with free
           -- type variables will be propagated later.
+          -- Note that we implicitly remove any type variables in the type of
+          -- the original argument by using the type of the actual argument
+          -- for the new formal parameter.
           -- TODO: preserve original naming?
           id <- Trans.lift $ mkBinderFor arg "param"
           -- Just pass the original argument to the new function, which binds it