From: trevor_hansen <trevor_hansen@e59a4935-1847-0410-ae03-e826735625c1>
Date: Tue, 3 Apr 2012 15:08:25 +0000 (+0000)
Subject: Improvement to cbipt. Run unsigned division propagagtor instead of the signed divisio... 
X-Git-Url: https://git.unchartedbackwaters.co.uk/w/?a=commitdiff_plain;h=3abd02a6234690f1214a9c34e61cc0dc39312c3a;p=francis%2Fstp.git

Improvement to cbipt. Run unsigned division propagagtor instead of the signed division propagator if both values are positive.

git-svn-id: https://stp-fast-prover.svn.sourceforge.net/svnroot/stp-fast-prover/trunk/stp@1621 e59a4935-1847-0410-ae03-e826735625c1
---

diff --git a/src/simplifier/constantBitP/ConstantBitP_Division.cpp b/src/simplifier/constantBitP/ConstantBitP_Division.cpp
index 34da917..bb485a8 100644
--- a/src/simplifier/constantBitP/ConstantBitP_Division.cpp
+++ b/src/simplifier/constantBitP/ConstantBitP_Division.cpp
@@ -1119,8 +1119,12 @@ Result bvSignedDivisionBothWays(vector<FixedBits*>& children,
         return NO_CHANGE;
     }
 
-
-	return bvSignedDivisionRemainderBothWays(children, output, bm,
+  // unsigned division propagates much better than signed division does!
+  const int top = children[0]->getWidth();
+  if ((*children[0])[top-1] == '0' && (*children[1])[top-1] == '0')
+    return bvUnsignedDivisionBothWays(children, output, bm);
+  else
+    return bvSignedDivisionRemainderBothWays(children, output, bm,
 			bvUnsignedDivisionBothWays, SIGNED_DIVISION);
 }
 }