From 2e4be2314249c7c6d6222482cc3a37bef6ffb019 Mon Sep 17 00:00:00 2001
From: Kathy Gray
Date: Mon, 29 Jun 2015 14:06:01 +0100
Subject: Return unknown for a == unknown or unknown == a. Fixes issue #15

---
 src/lem_interp/interp_lib.lem | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

(limited to 'src')

diff --git a/src/lem_interp/interp_lib.lem b/src/lem_interp/interp_lib.lem
index b8076538..83bee732 100644
--- a/src/lem_interp/interp_lib.lem
+++ b/src/lem_interp/interp_lib.lem
@@ -89,6 +89,8 @@ end
 
 let has_unknown v = match detaint v with
   | V_vector _ _ vs -> List.any is_unknown vs
+  | V_unknown -> true
+  | _ -> false
 end
 
 let has_undef v = match detaint v with
@@ -265,7 +267,10 @@ let extz direction (V_tuple[v1;v]) =
 
 let eq (V_tuple [x; y]) = 
   let combo = binary_taint (fun v _ -> v) x y in
-  retaint combo (V_lit (L_aux (if value_eq (detaint x) (detaint y) then L_one else L_zero) Unknown))
+  retaint combo 
+    (if has_unknown x || has_unknown y 
+    then V_unknown
+    else (V_lit (L_aux (if value_eq (detaint x) (detaint y) then L_one else L_zero) Unknown)))
 
 (* XXX interpret vectors as unsigned numbers for equality *)
 let eq_vec_range (V_tuple [v; r]) = eq (V_tuple [to_num Unsigned v; r]) ;;
-- 
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