sim.cc: Move cycle check

Calling `throw dst_end_of_data_exception()` when the desired number of cycles has been reached means that the fst reader can't tidy up after itself and leads to memory leaks.
This doesn't happen when the `-stop` flag is used because the `Yosys::FstData` struct tracks the end time and skips the outer callback if the simulation has gone past the desired end time.
Move cycle checking into the inner callback along with the time checking means that the outer callback no longer needs to throw an exception in order to stop checking further values, while still allowing the fst reader to finish reading and deallocate memory.

kernel/fstdata.cc

@@ -206,6 +206,7 @@ static void reconstruct_clb_attimes(void *user_data, uint64_t pnt_time, fstHandl
 void FstData::reconstruct_callback_attimes(uint64_t pnt_time, fstHandle pnt_facidx, const unsigned char *pnt_value, uint32_t /* plen */)
 {
 	if (pnt_time > end_time || !pnt_value) return;
+	if (curr_cycle > last_cycle) return;
 	// if we are past the timestamp
 	bool is_clock = false;
 	if (!all_samples) {
@@ -225,6 +226,7 @@ void FstData::reconstruct_callback_attimes(uint64_t pnt_time, fstHandle pnt_faci
 	if (pnt_time > last_time) {
 		if (all_samples) {
 			callback(last_time);
+			curr_cycle++;
 			last_time = pnt_time;
 		} else {
 			if (is_clock) {
@@ -232,6 +234,7 @@ void FstData::reconstruct_callback_attimes(uint64_t pnt_time, fstHandle pnt_faci
 				std::string prev = past_data[pnt_facidx];
 				if ((prev!="1" && val=="1") || (prev!="0" && val=="0")) {
 					callback(last_time);
+					curr_cycle++;
 					last_time = pnt_time;
 				}
 			}
@@ -241,12 +244,14 @@ void FstData::reconstruct_callback_attimes(uint64_t pnt_time, fstHandle pnt_faci
 	last_data[pnt_facidx] =  std::string((const char *)pnt_value);
 }
 
-void FstData::reconstructAllAtTimes(std::vector<fstHandle> &signal, uint64_t start, uint64_t end, CallbackFunction cb)
+void FstData::reconstructAllAtTimes(std::vector<fstHandle> &signal, uint64_t start, uint64_t end, unsigned int end_cycle, CallbackFunction cb)
 {
 	clk_signals = signal;
 	callback = cb;
 	start_time = start;
 	end_time = end;
+	curr_cycle = 0;
+	last_cycle = end_cycle;
 	last_data.clear();
 	last_time = start_time;
 	past_data.clear();
@@ -256,12 +261,16 @@ void FstData::reconstructAllAtTimes(std::vector<fstHandle> &signal, uint64_t sta
 	fstReaderSetUnlimitedTimeRange(ctx);
 	fstReaderSetFacProcessMaskAll(ctx);
 	fstReaderIterBlocks2(ctx, reconstruct_clb_attimes, reconstruct_clb_varlen_attimes, this, nullptr);
-	if (last_time!=end_time) {
+	if (last_time!=end_time && curr_cycle < last_cycle) {
 		past_data = last_data;
 		callback(last_time);
+		curr_cycle++;
 	}
+	if (curr_cycle < last_cycle) {
 		past_data = last_data;
 		callback(end_time);
+		curr_cycle++;
+	}
 }
 
 std::string FstData::valueOf(fstHandle signal)

kernel/fstdata.h

@@ -50,7 +50,7 @@ class FstData
 	std::vector<FstVar>& getVars() { return vars; };
 
 	void reconstruct_callback_attimes(uint64_t pnt_time, fstHandle pnt_facidx, const unsigned char *pnt_value, uint32_t plen);
-	void reconstructAllAtTimes(std::vector<fstHandle> &signal, uint64_t start_time, uint64_t end_time, CallbackFunction cb);
+	void reconstructAllAtTimes(std::vector<fstHandle> &signal, uint64_t start_time, uint64_t end_time, unsigned int end_cycle, CallbackFunction cb);
 
 	std::string valueOf(fstHandle signal);
 	fstHandle getHandle(std::string name);
@@ -73,6 +73,8 @@ private:
 	std::string timescale_str;
 	uint64_t start_time;
 	uint64_t end_time;
+	unsigned int last_cycle;
+	unsigned int curr_cycle;
 	CallbackFunction callback;
 	std::vector<fstHandle> clk_signals;
 	bool all_samples;

passes/sat/sim.cc

@@ -1546,9 +1546,9 @@ struct SimWorker : SimShared
 			log(" for %d clock cycle(s)",numcycles);
 		log("\n");
 		bool all_samples = fst_clock.empty();
+		unsigned int end_cycle = cycles_set ? numcycles*2 : INT_MAX;
 
-		try {
+		fst->reconstructAllAtTimes(fst_clock, startCount, stopCount, end_cycle, [&](uint64_t time) {
-			fst->reconstructAllAtTimes(fst_clock, startCount, stopCount, [&](uint64_t time) {
 			if (verbose)
 				log("Co-simulating %s %d [%lu%s].\n", (all_samples ? "sample" : "cycle"), cycle, (unsigned long)time, fst->getTimescaleString());
 			bool did_something = top->setInputs();
@@ -1566,16 +1566,7 @@ struct SimWorker : SimShared
 			if (status)
 				log_error("Signal difference\n");
 			cycle++;
-
-				// Limit to number of cycles if provided
-				if (cycles_set && cycle > numcycles *2)
-					throw fst_end_of_data_exception();
-				if (time==stopCount)
-					throw fst_end_of_data_exception();
 		});
-		} catch(fst_end_of_data_exception) {
-			// end of data detected
-		}
 
 		write_output_files();
 		delete fst;
@@ -2248,8 +2239,8 @@ struct SimWorker : SimShared
 		log("Writing data to `%s`\n", (tb_filename+".txt").c_str());
 		std::ofstream data_file(tb_filename+".txt");
 		std::stringstream initstate;
-		try {
+		unsigned int end_cycle = cycles_set ? numcycles*2 : INT_MAX;
-			fst->reconstructAllAtTimes(fst_clock, startCount, stopCount, [&](uint64_t time) {
+		fst->reconstructAllAtTimes(fst_clock, startCount, stopCount, end_cycle, [&](uint64_t time) {
 			for(auto &item : clocks)
 				data_file << stringf("%s",fst->valueOf(item.second).c_str());
 			for(auto &item : inputs)
@@ -2272,16 +2263,7 @@ struct SimWorker : SimShared
 			}
 			cycle++;
 			prev_time = time;
-
-				// Limit to number of cycles if provided
-				if (cycles_set && cycle > numcycles *2)
-					throw fst_end_of_data_exception();
-				if (time==stopCount)
-					throw fst_end_of_data_exception();
 		});
-		} catch(fst_end_of_data_exception) {
-			// end of data detected
-		}
 
 		f << stringf("\treg [0:%d] data [0:%d];\n", data_len-1, cycle-1);
 		f << "\tinitial begin;\n";