From: Matthijs Kooijman <m.kooijman@student.utwente.nl>
Date: Mon, 17 Aug 2009 09:28:20 +0000 (+0200)
Subject: Make letremoveunused work for recursive lets again.
X-Git-Url: https://git.stderr.nl/gitweb?a=commitdiff_plain;h=a166e4049d45e4e1688baf748e1a82806374a3c0;p=matthijs%2Fmaster-project%2Fc%CE%BBash.git

Make letremoveunused work for recursive lets again.

The non-recursive version is also changed to work for each nested let in
turn, instead of running on a bunch of them at the same time.
---

diff --git "a/c\316\273ash/CLasH/Normalize.hs" "b/c\316\273ash/CLasH/Normalize.hs"
index a7223e3..b16eb7a 100644
--- "a/c\316\273ash/CLasH/Normalize.hs"
+++ "b/c\316\273ash/CLasH/Normalize.hs"
@@ -248,13 +248,17 @@ letremovesimpletop = everywhere ("letremovesimple", inlinebind (\(b, e) -> Trans
 -- Unused let binding removal
 --------------------------------
 letremoveunused, letremoveunusedtop :: Transform
-letremoveunused expr@(Let _ _) = do
+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
   -- Only set the changed flag if binds got removed
-  changeif (length binds' /= length binds) (mkNonRecLets binds' res)
+  changeif (length binds' /= length binds) (Let (Rec binds') res)
     where
-      (binds, res) = flattenLets expr
       bound_exprs = map snd binds
       -- For each bind check if the bind is used by res or any of the bound
       -- expressions