Added support for Minisat::SimpSolver + ezSAT frezze() API

kernel/satgen.h

@@ -72,6 +72,7 @@ struct SatGen
 			} else {
 				std::string name = pf + stringf(c.wire->width == 1 ?  "%s" : "%s [%d]", RTLIL::id2cstr(c.wire->name), c.offset);
 				vec.push_back(ez->literal(name));
+				ez->freeze(vec.back());
 			}
 		return vec;
 	}

libs/ezsat/ezminisat.cc

@@ -51,9 +51,19 @@ void ezMiniSAT::clear()
 	}
 	foundContradiction = false;
 	minisatVars.clear();
+#if EZMINISAT_SIMPSOLVER && EZMINISAT_INCREMENTAL
+	cnfFrozenVars.clear();
+#endif
 	ezSAT::clear();
 }
 
+#if EZMINISAT_SIMPSOLVER && EZMINISAT_INCREMENTAL
+void ezMiniSAT::freeze(int id)
+{
+	cnfFrozenVars.insert(bind(id));
+}
+#endif
+
 ezMiniSAT *ezMiniSAT::alarmHandlerThis = NULL;
 clock_t ezMiniSAT::alarmHandlerTimeout = 0;
 
@@ -92,7 +102,7 @@ contradiction:
 		modelIdx.push_back(bind(id));
 
 	if (minisatSolver == NULL) {
-		minisatSolver = new EZMINISAT_SOLVER;
+		minisatSolver = new Solver;
 		minisatSolver->verbosity = EZMINISAT_VERBOSITY;
 	}
 
@@ -106,13 +116,27 @@ contradiction:
 	while (int(minisatVars.size()) < numCnfVariables())
 		minisatVars.push_back(minisatSolver->newVar());
 
+#if EZMINISAT_SIMPSOLVER && EZMINISAT_INCREMENTAL
+	for (auto idx : cnfFrozenVars)
+		minisatSolver->setFrozen(minisatVars.at(idx > 0 ? idx-1 : -idx-1), true);
+	cnfFrozenVars.clear();
+#endif
+
 	for (auto &clause : cnf) {
 		Minisat::vec<Minisat::Lit> ps;
-		for (auto idx : clause)
+		for (auto idx : clause) {
 			if (idx > 0)
 				ps.push(Minisat::mkLit(minisatVars.at(idx-1)));
 			else
 				ps.push(Minisat::mkLit(minisatVars.at(-idx-1), true));
+#if EZMINISAT_SIMPSOLVER
+			if (minisatSolver->isEliminated(minisatVars.at(idx > 0 ? idx-1 : -idx-1))) {
+				fprintf(stderr, "Assert in %s:%d failed! Missing call to ezsat->freeze(): %s (lit=%d)\n",
+						__FILE__, __LINE__, cnfLiteralInfo(idx).c_str(), idx);
+				abort();
+			}
+#endif
+		}
 		if (!minisatSolver->addClause(ps))
 			goto contradiction;
 	}
@@ -122,11 +146,18 @@ contradiction:
 
 	Minisat::vec<Minisat::Lit> assumps;
 
-	for (auto idx : extraClauses)
+	for (auto idx : extraClauses) {
 		if (idx > 0)
 			assumps.push(Minisat::mkLit(minisatVars.at(idx-1)));
 		else
 			assumps.push(Minisat::mkLit(minisatVars.at(-idx-1), true));
+#if EZMINISAT_SIMPSOLVER
+		if (minisatSolver->isEliminated(minisatVars.at(idx > 0 ? idx-1 : -idx-1))) {
+			fprintf(stderr, "Assert in %s:%d failed! Missing call to ezsat->freeze(): %s\n", __FILE__, __LINE__, cnfLiteralInfo(idx).c_str());
+			abort();
+		}
+#endif
+	}
 
 	sighandler_t old_alarm_sighandler = NULL;
 	int old_alarm_timeout = 0;

libs/ezsat/ezminisat.h

@@ -20,7 +20,7 @@
 #ifndef EZMINISAT_H
 #define EZMINISAT_H
 
-#define EZMINISAT_SOLVER Minisat::Solver
+#define EZMINISAT_SIMPSOLVER 0
 #define EZMINISAT_VERBOSITY 0
 #define EZMINISAT_INCREMENTAL 1
 
@@ -38,10 +38,19 @@ namespace Minisat {
 class ezMiniSAT : public ezSAT
 {
 private:
-	EZMINISAT_SOLVER *minisatSolver;
+#if EZMINISAT_SIMPSOLVER
+	typedef Minisat::SimpSolver Solver;
+#else
+	typedef Minisat::Solver Solver;
+#endif
+	Solver *minisatSolver;
 	std::vector<int> minisatVars;
 	bool foundContradiction;
 
+#if EZMINISAT_SIMPSOLVER && EZMINISAT_INCREMENTAL
+	std::set<int> cnfFrozenVars;
+#endif
+
 	static ezMiniSAT *alarmHandlerThis;
 	static clock_t alarmHandlerTimeout;
 	static void alarmHandler(int);
@@ -50,6 +59,9 @@ public:
 	ezMiniSAT();
 	virtual ~ezMiniSAT();
 	virtual void clear();
+#if EZMINISAT_SIMPSOLVER && EZMINISAT_INCREMENTAL
+	virtual void freeze(int id);
+#endif
 	virtual bool solver(const std::vector<int> &modelExpressions, std::vector<bool> &modelValues, const std::vector<int> &assumptions);
 };
 

libs/ezsat/ezsat.cc

@@ -29,18 +29,18 @@ const int ezSAT::FALSE = 2;
 
 ezSAT::ezSAT()
 {
-	literal("TRUE");
-	literal("FALSE");
-
-	assert(literal("TRUE") == TRUE);
-	assert(literal("FALSE") == FALSE);
-
 	cnfConsumed = false;
 	cnfVariableCount = 0;
 	cnfClausesCount = 0;
 
 	solverTimeout = 0;
 	solverTimoutStatus = false;
+
+	freeze(literal("TRUE"));
+	freeze(literal("FALSE"));
+
+	assert(literal("TRUE") == TRUE);
+	assert(literal("FALSE") == FALSE);
 }
 
 ezSAT::~ezSAT()
@@ -345,6 +345,10 @@ void ezSAT::clear()
 	cnfAssumptions.clear();
 }
 
+void ezSAT::freeze(int)
+{
+}
+
 void ezSAT::assume(int id)
 {
 	cnfAssumptions.insert(id);
@@ -462,6 +466,23 @@ int ezSAT::bound(int id) const
 	return 0;
 }
 
+std::string ezSAT::cnfLiteralInfo(int idx) const
+{
+	for (size_t i = 0; i < cnfLiteralVariables.size(); i++) {
+		if (cnfLiteralVariables[i] == idx)
+			return to_string(i+1);
+		if (cnfLiteralVariables[i] == -idx)
+			return "NOT " + to_string(i+1);
+	}
+	for (size_t i = 0; i < cnfExpressionVariables.size(); i++) {
+		if (cnfExpressionVariables[i] == idx)
+			return to_string(-i-1);
+		if (cnfExpressionVariables[i] == -idx)
+			return "NOT " + to_string(-i-1);
+	}
+	return "<unnamed>";
+}
+
 int ezSAT::bind(int id)
 {
 	if (id >= 0) {

libs/ezsat/ezsat.h

@@ -141,6 +141,7 @@ public:
 	// manage CNF (usually only accessed by SAT solvers)
 
 	virtual void clear();
+	virtual void freeze(int id);
 	void assume(int id);
 	int bind(int id);
 
@@ -154,6 +155,8 @@ public:
 	void consumeCnf();
 	void consumeCnf(std::vector<std::vector<int>> &cnf);
 
+	std::string cnfLiteralInfo(int idx) const;
+
 	// simple helpers for build expressions easily
 
 	struct _V {