remove Mux Value.cast before passing to 1st argument __Mux__

only one case requires Mux to perform Value.cast, which is when the sel
argument is a python bool

diff --git a/nmigen/hdl/ast.py b/nmigen/hdl/ast.py
index 9ddc7176d2723c951de062686bccffb2b8937200..6a1a05ee9d6beb5289a671a9745375c474d3a9a3 100644 (file)
--- a/nmigen/hdl/ast.py
+++ b/nmigen/hdl/ast.py
@@ -732,9 +732,8 @@ class Operator(Value):
 
 
 def Mux(sel, val1, val0):
-    sel = Value.cast(sel)
-    if len(sel) != 1:
-        sel = sel.bool()
+    if isinstance(sel, bool): # one instance where Mux is passed an actual bool
+        sel = Value.cast(sel)
     return sel.__Mux__(val1, val0)