X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=rts%2FPrimOps.cmm;h=5c9cfb75ad87ab00c3440bc4612993497a2db5f3;hb=0885017a4e92fe5710d1427c214adb87b92987e5;hp=701654af49db72e31c77995aecee9bdf3082e9a4;hpb=59977b6c7cc81777dc6f8266c68945d1ab691aec;p=ghc-hetmet.git

diff --git a/rts/PrimOps.cmm b/rts/PrimOps.cmm
index 701654a..5c9cfb7 100644
--- a/rts/PrimOps.cmm
+++ b/rts/PrimOps.cmm
@@ -230,6 +230,25 @@ stg_newMutVarzh
     RET_P(mv);
 }
 
+stg_casMutVarzh
+ /* MutVar# s a -> a -> a -> State# s -> (# State#, Int#, a #) */
+{
+    W_ mv, old, new, h;
+
+    mv  = R1;
+    old = R2;
+    new = R3;
+
+    (h) = foreign "C" cas(mv + SIZEOF_StgHeader + OFFSET_StgMutVar_var,
+                          old, new) [];
+    if (h != old) {
+        RET_NP(1,h);
+    } else {
+        RET_NP(0,h);
+    }
+}
+
+
 stg_atomicModifyMutVarzh
 {
     W_ mv, f, z, x, y, r, h;