Added timout functionality to SAT solver

libs/ezsat/ezminisat.cc

@@ -23,6 +23,7 @@
 
 #include <limits.h>
 #include <stdint.h>
+#include <signal.h>
 #include <cinttypes>
 
 #include "minisat/core/Solver.h"
@@ -50,8 +51,22 @@ void ezMiniSAT::clear()
 	ezSAT::clear();
 }
 
+ezMiniSAT *ezMiniSAT::alarmHandlerThis = NULL;
+clock_t ezMiniSAT::alarmHandlerTimeout = 0;
+
+void ezMiniSAT::alarmHandler(int)
+{
+	if (clock() > alarmHandlerTimeout) {
+		alarmHandlerThis->minisatSolver->interrupt();
+		alarmHandlerTimeout = 0;
+	} else
+		alarm(1);
+}
+
 bool ezMiniSAT::solver(const std::vector<int> &modelExpressions, std::vector<bool> &modelValues, const std::vector<int> &assumptions)
 {
+	solverTimoutStatus = false;
+
 	if (0) {
 contradiction:
 		delete minisatSolver;
@@ -104,7 +119,28 @@ contradiction:
 		else
 			assumps.push(Minisat::mkLit(minisatVars.at(-idx-1), true));
 
-	if (!minisatSolver->solve(assumps))
+	sighandler_t old_alarm_sighandler;
+	int old_alarm_timeout;
+
+	if (solverTimeout > 0) {
+		alarmHandlerThis = this;
+		alarmHandlerTimeout = clock() + solverTimeout*CLOCKS_PER_SEC;
+		old_alarm_timeout = alarm(0);
+		old_alarm_sighandler = signal(SIGALRM, alarmHandler);
+		alarm(1);
+	}
+
+	bool foundSolution = minisatSolver->solve(assumps);
+
+	if (solverTimeout > 0) {
+		if (alarmHandlerTimeout == 0)
+			solverTimoutStatus = true;
+		alarm(0);
+		signal(SIGALRM, old_alarm_sighandler);
+		alarm(old_alarm_timeout);
+	}
+
+	if (!foundSolution)
 		return false;
 
 	modelValues.clear();

libs/ezsat/ezminisat.h

@@ -21,6 +21,7 @@
 #define EZMINISAT_H
 
 #include "ezsat.h"
+#include <time.h>
 
 // minisat is using limit macros and format macros in their headers that
 // can be the source of some troubles when used from c++11. thefore we
@@ -36,6 +37,10 @@ private:
 	std::vector<int> minisatVars;
 	bool foundContradiction;
 
+	static ezMiniSAT *alarmHandlerThis;
+	static clock_t alarmHandlerTimeout;
+	static void alarmHandler(int);
+
 public:
 	ezMiniSAT();
 	virtual ~ezMiniSAT();

libs/ezsat/ezsat.cc

@@ -38,6 +38,9 @@ ezSAT::ezSAT()
 	cnfConsumed = false;
 	cnfVariableCount = 0;
 	cnfClausesCount = 0;
+
+	solverTimeout = 0;
+	solverTimoutStatus = false;
 }
 
 ezSAT::~ezSAT()

libs/ezsat/ezsat.h

@@ -69,6 +69,9 @@ private:
 	int bind_cnf_or(const std::vector<int> &args);
 
 public:
+	int solverTimeout;
+	bool solverTimoutStatus;
+
 	ezSAT();
 	virtual ~ezSAT();
 
@@ -130,6 +133,14 @@ public:
 		return solver(modelExpressions, modelValues, assumptions);
 	}
 
+	void setSolverTimeout(int newTimeoutSeconds) {
+		solverTimeout = newTimeoutSeconds;
+	}
+
+	bool getSolverTimoutStatus() {
+		return solverTimoutStatus;
+	}
+
 	// manage CNF (usually only accessed by SAT solvers)
 
 	virtual void clear();

passes/sat/sat.cc

@@ -52,12 +52,15 @@ struct SatHelper
 	std::vector<std::string> shows;
 	SigPool show_signal_pool;
 	SigSet<RTLIL::Cell*> show_drivers;
-	int max_timestep;
+	int max_timestep, timeout;
+	bool gotTimeout;
 
 	SatHelper(RTLIL::Design *design, RTLIL::Module *module) :
 		design(design), module(module), sigmap(module), ct(design), satgen(&ez, design, &sigmap)
 	{
 		max_timestep = -1;
+		timeout = 0;
+		gotTimeout = false;
 	}
 
 	void setup(int timestep = -1)
@@ -190,12 +193,22 @@ struct SatHelper
 
 	bool solve(const std::vector<int> &assumptions)
 	{
-		return ez.solve(modelExpressions, modelValues, assumptions);
+		log_assert(gotTimeout == false);
+		ez.setSolverTimeout(timeout);
+		bool success = ez.solve(modelExpressions, modelValues, assumptions);
+		if (ez.getSolverTimoutStatus())
+			gotTimeout = true;
+		return success;
 	}
 
 	bool solve(int a = 0, int b = 0, int c = 0, int d = 0, int e = 0, int f = 0)
 	{
-		return ez.solve(modelExpressions, modelValues, a, b, c, d, e, f);
+		log_assert(gotTimeout == false);
+		ez.setSolverTimeout(timeout);
+		bool success = ez.solve(modelExpressions, modelValues, a, b, c, d, e, f);
+		if (ez.getSolverTimoutStatus())
+			gotTimeout = true;
+		return success;
 	}
 
 	struct ModelBlockInfo {
@@ -380,6 +393,17 @@ static void print_proof_failed()
 	log("\n");
 }
 
+static void print_timeout()
+{
+	log("\n");
+	log("        _____  _  _      _____ ____  _     _____\n");
+	log("       /__ __\\/ \\/ \\__/|/  __//  _ \\/ \\ /\\/__ __\\\n");
+	log("         / \\  | || |\\/|||  \\  | / \\|| | ||  / \\\n");
+	log("         | |  | || |  |||  /_ | \\_/|| \\_/|  | |\n");
+	log("         \\_/  \\_/\\_/  \\|\\____\\\\____/\\____/  \\_/\n");
+	log("\n");
+}
+
 static void print_qed()
 {
 	log("\n");
@@ -442,9 +466,15 @@ struct SatPass : public Pass {
 		log("    -maxsteps <N>\n");
 		log("        Set a maximum length for the induction.\n");
 		log("\n");
+		log("    -timeout <N>\n");
+		log("        Maximum number of seconds a single SAT instance may take.\n");
+		log("\n");
 		log("    -verify\n");
 		log("        Return an error and stop the synthesis script if the proof fails.\n");
 		log("\n");
+		log("    -verify-no-timeout\n");
+		log("        Like -verify but do not return an error for timeouts.\n");
+		log("\n");
 	}
 	virtual void execute(std::vector<std::string> args, RTLIL::Design *design)
 	{
@@ -452,8 +482,8 @@ struct SatPass : public Pass {
 		std::map<int, std::vector<std::pair<std::string, std::string>>> sets_at;
 		std::map<int, std::vector<std::string>> unsets_at;
 		std::vector<std::string> shows;
-		int loopcount = 0, seq_len = 0, maxsteps = 0;
-		bool verify = false;
+		int loopcount = 0, seq_len = 0, maxsteps = 0, timeout = 0;
+		bool verify = false, fail_on_timeout = false;
 
 		log_header("Executing SAT pass (solving SAT problems in the circuit).\n");
 
@@ -464,9 +494,18 @@ struct SatPass : public Pass {
 				continue;
 			}
 			if (args[argidx] == "-verify") {
+				fail_on_timeout = true;
 				verify = true;
 				continue;
 			}
+			if (args[argidx] == "-verify-no-timeout") {
+				verify = true;
+				continue;
+			}
+			if (args[argidx] == "-timeout" && argidx+1 < args.size()) {
+				timeout = atoi(args[++argidx].c_str());
+				continue;
+			}
 			if (args[argidx] == "-max" && argidx+1 < args.size()) {
 				loopcount = atoi(args[++argidx].c_str());
 				continue;
@@ -539,6 +578,7 @@ struct SatPass : public Pass {
 			basecase.sets_at = sets_at;
 			basecase.unsets_at = unsets_at;
 			basecase.shows = shows;
+			basecase.timeout = timeout;
 
 			for (int timestep = 1; timestep <= seq_len; timestep++)
 				basecase.setup(timestep);
@@ -546,6 +586,7 @@ struct SatPass : public Pass {
 			inductstep.sets = sets;
 			inductstep.prove = prove;
 			inductstep.shows = shows;
+			inductstep.timeout = timeout;
 
 			inductstep.setup(1);
 			inductstep.ez.assume(inductstep.setup_proof(1));
@@ -573,6 +614,9 @@ struct SatPass : public Pass {
 					goto tip_failed;
 				}
 
+				if (basecase.gotTimeout)
+					goto timeout;
+
 				log("Base case for induction length %d proven.\n", inductlen);
 				basecase.ez.assume(property);
 
@@ -589,6 +633,8 @@ struct SatPass : public Pass {
 						inductstep.ez.numCnfVariables(), inductstep.ez.numCnfClauses());
 
 				if (!inductstep.solve(inductstep.ez.NOT(property))) {
+					if (inductstep.gotTimeout)
+						goto timeout;
 					log("Induction step proven: SUCCESS!\n");
 					print_qed();
 					goto tip_success;
@@ -622,6 +668,7 @@ struct SatPass : public Pass {
 			sathelper.sets_at = sets_at;
 			sathelper.unsets_at = unsets_at;
 			sathelper.shows = shows;
+			sathelper.timeout = timeout;
 
 			if (seq_len == 0) {
 				sathelper.setup();
@@ -668,6 +715,8 @@ struct SatPass : public Pass {
 			}
 			else
 			{
+				if (sathelper.gotTimeout)
+					goto timeout;
 				if (did_rerun)
 					log("SAT solving finished - no more models found.\n");
 				else if (prove.size() == 0)
@@ -678,6 +727,14 @@ struct SatPass : public Pass {
 				}
 			}
 		}
+
+		if (0) {
+	timeout:
+			log("Interrupted SAT solver: TIMEOUT!\n");
+			print_timeout();
+			if (fail_on_timeout)
+				log_error("Called with -verify and proof did time out!\n");
+		}
 	}
 } SatPass;
  

tests/xsthammer/run-check.sh

@@ -51,8 +51,8 @@ done
 {
 	echo "read_ilang ${job}_top_nomap.il"
 	echo "read_ilang ${job}_top_techmap.il"
-	echo "sat -verify -show a,b,y_rtl,y_xst -prove y_rtl y_xst ${job}_top_nomap"
-	echo "sat -verify -show a,b,y_rtl,y_xst -prove y_rtl y_xst ${job}_top_techmap"
+	echo "sat -timeout 60 -verify-no-timeout -show a,b,y_rtl,y_xst -prove y_rtl y_xst ${job}_top_nomap"
+	echo "sat -timeout 60 -verify-no-timeout -show a,b,y_rtl,y_xst -prove y_rtl y_xst ${job}_top_techmap"
 	if [[ $job != expression_* ]]; then
 		echo "eval -brute_force_equiv_checker ${job}_rtl_nomap   ${job}_xst_nomap"
 		echo "eval -brute_force_equiv_checker ${job}_rtl_techmap ${job}_xst_techmap"