From c60ca4b7b42eb930030d88fc11d42c70708127d8 Mon Sep 17 00:00:00 2001
From: trevor_hansen <trevor_hansen@e59a4935-1847-0410-ae03-e826735625c1>
Date: Thu, 16 Jun 2011 02:19:27 +0000
Subject: [PATCH] Speedup for easy instances. Don't call the SAT solver if we
 already know the problem is true/false.

git-svn-id: https://stp-fast-prover.svn.sourceforge.net/svnroot/stp-fast-prover/trunk/stp@1339 e59a4935-1847-0410-ae03-e826735625c1
---
 src/to-sat/AIG/ToSATAIG.cpp | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/src/to-sat/AIG/ToSATAIG.cpp b/src/to-sat/AIG/ToSATAIG.cpp
index 2eabd58..5f096c6 100644
--- a/src/to-sat/AIG/ToSATAIG.cpp
+++ b/src/to-sat/AIG/ToSATAIG.cpp
@@ -8,7 +8,15 @@ namespace BEEV
     bool
     ToSATAIG::CallSAT(SATSolver& satSolver, const ASTNode& input, bool needAbsRef)
     {
-      if (cb != NULL  && cb->isUnsatisfiable())
+    	// Shortcut if known. This avoids calling the setup of the CNF generator.
+    	// setup takes about 15ms.
+       if (input == ASTFalse && !needAbsRef)
+    		return false;
+
+       if (input == ASTTrue && !needAbsRef)
+    		return true;
+
+     if (cb != NULL  && cb->isUnsatisfiable())
         return false;
 
       if (simp == NULL)
-- 
2.47.3