From f2d113cf3cbb0f4966a7c909b9cd2c14aa753eb1 Mon Sep 17 00:00:00 2001
From: Andres Noetzli <noetzli@stanford.edu>
Date: Wed, 15 May 2019 17:38:04 +0000
Subject: [PATCH] Fix model of Boolean vars with eager bit-blaster (#2998)

When bit-blasting eagerly, we were not assigning values to the Boolean
variables in the `TheoryModel`. With eager bit-blasting, the BV SAT
solver gets all (converted) terms, including the Boolean ones, so
`EagerBitblaster::collectModelInfo()` is responsible for assigning
values to Boolean variables. However, it has only been assigning values
to bit-vector variables, which lead to wrong models. This commit fixes
the issue by asking the `CnfStream` for the Boolean variables, querying
the SAT solver for their value, and assigning them in the `TheoryModel`.
---
 src/theory/bv/bitblast/eager_bitblaster.cpp | 19 +++++++++++++++++++
 test/regress/CMakeLists.txt                 |  1 +
 test/regress/regress0/bv/bool-model.smt2    |  7 +++++++
 3 files changed, 27 insertions(+)
 create mode 100644 test/regress/regress0/bv/bool-model.smt2

diff --git a/src/theory/bv/bitblast/eager_bitblaster.cpp b/src/theory/bv/bitblast/eager_bitblaster.cpp
index 77ff6f885..0d3d3b483 100644
--- a/src/theory/bv/bitblast/eager_bitblaster.cpp
+++ b/src/theory/bv/bitblast/eager_bitblaster.cpp
@@ -241,6 +241,9 @@ Node EagerBitblaster::getModelFromSatSolver(TNode a, bool fullModel) {
 
 bool EagerBitblaster::collectModelInfo(TheoryModel* m, bool fullModel)
 {
+  NodeManager* nm = NodeManager::currentNM();
+
+  // Collect the values for the bit-vector variables
   TNodeSet::iterator it = d_variables.begin();
   for (; it != d_variables.end(); ++it) {
     TNode var = *it;
@@ -262,6 +265,22 @@ bool EagerBitblaster::collectModelInfo(TheoryModel* m, bool fullModel)
       }
     }
   }
+
+  // Collect the values for the Boolean variables
+  std::vector<TNode> vars;
+  d_cnfStream->getBooleanVariables(vars);
+  for (TNode var : vars)
+  {
+    Assert(d_cnfStream->hasLiteral(var));
+    prop::SatLiteral bit = d_cnfStream->getLiteral(var);
+    prop::SatValue value = d_satSolver->value(bit);
+    Assert(value != prop::SAT_VALUE_UNKNOWN);
+    if (!m->assertEquality(
+            var, nm->mkConst(value == prop::SAT_VALUE_TRUE), true))
+    {
+      return false;
+    }
+  }
   return true;
 }
 
diff --git a/test/regress/CMakeLists.txt b/test/regress/CMakeLists.txt
index 307906dc3..c3f2bc866 100644
--- a/test/regress/CMakeLists.txt
+++ b/test/regress/CMakeLists.txt
@@ -159,6 +159,7 @@ set(regress_0_tests
   regress0/bv/ackermann2.smt2
   regress0/bv/ackermann3.smt2
   regress0/bv/ackermann4.smt2
+  regress0/bv/bool-model.smt2
   regress0/bv/bool-to-bv-all.smt2
   regress0/bv/bool-to-bv-ite.smt2
   regress0/bv/bug260a.smt
diff --git a/test/regress/regress0/bv/bool-model.smt2 b/test/regress/regress0/bv/bool-model.smt2
new file mode 100644
index 000000000..30531418c
--- /dev/null
+++ b/test/regress/regress0/bv/bool-model.smt2
@@ -0,0 +1,7 @@
+; COMMAND-LINE: --bitblast=eager
+(set-info :status sat)
+(set-logic QF_BV)
+(declare-fun x () Bool)
+(declare-fun y () Bool)
+(assert (xor y x))
+(check-sat)
-- 
2.30.2