From e5a62a884321df193921801ecf12b740ee707e4e Mon Sep 17 00:00:00 2001
From: Vitor Santos Costa <vsc@dcc.fc.up.pt>
Date: Wed, 31 Aug 2011 13:56:32 -0700
Subject: [PATCH] CloseSlots should work even if the stack doesn't have a slot
 on top.

---
 H/Yap.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/H/Yap.h b/H/Yap.h
index 11d19ed25..74fa8d810 100644
--- a/H/Yap.h
+++ b/H/Yap.h
@@ -1377,6 +1377,8 @@ Yap_StartSlots( USES_REGS1 ) {
 static inline void
 Yap_CloseSlots( USES_REGS1 ) {
   Int old_slots;
+  if (CurSlot < LCL0-ASP)
+    return;
   old_slots = IntOfTerm(ASP[0]);
   ASP += (old_slots+1);
   CurSlot = IntOfTerm(*ASP);