From d39a5a77a9ec58ea97af91c961b02b5a55deaaa7 Mon Sep 17 00:00:00 2001
From: Eddie Hung <eddie@fpgeh.com>
Date: Thu, 13 Jun 2019 13:13:48 -0700
Subject: [PATCH] Add ConstEvalAig specialised for AIGs

---
 frontends/aiger/aigerparse.cc |   5 +-
 kernel/consteval.h            | 157 ++++++++++++++++++++++++++++++++++
 2 files changed, 159 insertions(+), 3 deletions(-)

diff --git a/frontends/aiger/aigerparse.cc b/frontends/aiger/aigerparse.cc
index 72b37d21d..42b3c7624 100644
--- a/frontends/aiger/aigerparse.cc
+++ b/frontends/aiger/aigerparse.cc
@@ -234,7 +234,7 @@ void AigerReader::parse_xaiger()
 				uint32_t lutNum = parse_xaiger_literal(f);
 				uint32_t lutSize = parse_xaiger_literal(f);
 				log_debug("m: dataSize=%u lutNum=%u lutSize=%u\n", dataSize, lutNum, lutSize);
-				ConstEval ce(module);
+				ConstEvalAig ce(module);
 				for (unsigned i = 0; i < lutNum; ++i) {
 					uint32_t rootNodeID = parse_xaiger_literal(f);
 					uint32_t cutLeavesM = parse_xaiger_literal(f);
@@ -251,12 +251,11 @@ void AigerReader::parse_xaiger()
 					}
 					RTLIL::Const lut_mask(RTLIL::State::Sx, 1 << input_sig.size());
 					for (int j = 0; j < (1 << cutLeavesM); ++j) {
-						ce.push();
+						ce.clear();
 						ce.set(input_sig, RTLIL::Const{j, static_cast<int>(cutLeavesM)});
 						RTLIL::SigSpec o(output_sig);
 						ce.eval(o);
 						lut_mask[j] = o.as_const()[0];
-						ce.pop();
 					}
 					RTLIL::Cell *output_cell = module->cell(stringf("\\__%d__$and", rootNodeID));
 					log_assert(output_cell);
diff --git a/kernel/consteval.h b/kernel/consteval.h
index 154373a8d..59e3ef20f 100644
--- a/kernel/consteval.h
+++ b/kernel/consteval.h
@@ -390,6 +390,163 @@ struct ConstEval
 	}
 };
 
+struct ConstEvalAig
+{
+	RTLIL::Module *module;
+	//SigMap assign_map;
+	SigMap values_map;
+	//SigPool stop_signals;
+	SigSet<RTLIL::Cell*> sig2driver;
+	std::set<RTLIL::Cell*> busy;
+	std::vector<SigMap> stack;
+	//RTLIL::State defaultval;
+
+	ConstEvalAig(RTLIL::Module *module /*, RTLIL::State defaultval = RTLIL::State::Sm*/) : module(module) /*, assign_map(module), defaultval(defaultval)*/
+	{
+		CellTypes ct;
+		ct.setup_internals();
+		ct.setup_stdcells();
+
+		for (auto &it : module->cells_) {
+			if (!ct.cell_known(it.second->type))
+				continue;
+			for (auto &it2 : it.second->connections())
+				if (ct.cell_output(it.second->type, it2.first))
+					sig2driver.insert(/*assign_map*/(it2.second), it.second);
+		}
+	}
+
+	void clear()
+	{
+		values_map.clear();
+		//stop_signals.clear();
+	}
+
+	void push()
+	{
+		stack.push_back(values_map);
+	}
+
+	void pop()
+	{
+		values_map.swap(stack.back());
+		stack.pop_back();
+	}
+
+	void set(RTLIL::SigSpec sig, RTLIL::Const value)
+	{
+		//assign_map.apply(sig);
+#ifndef NDEBUG
+		RTLIL::SigSpec current_val = values_map(sig);
+		for (int i = 0; i < GetSize(current_val); i++)
+			log_assert(current_val[i].wire != NULL || current_val[i] == value.bits[i]);
+#endif
+		values_map.add(sig, RTLIL::SigSpec(value));
+	}
+
+	//void stop(RTLIL::SigSpec sig)
+	//{
+	//	assign_map.apply(sig);
+	//	stop_signals.add(sig);
+	//}
+
+	bool eval(RTLIL::Cell *cell, RTLIL::SigSpec &undef)
+	{
+		RTLIL::SigSpec sig_y = values_map(/*assign_map*/(cell->getPort("\\Y")));
+		if (sig_y.is_fully_const())
+			return true;
+
+		RTLIL::SigSpec sig_a = cell->getPort("\\A");
+		if (sig_a.size() > 0 && !eval(sig_a, undef, cell))
+			return false;
+
+		RTLIL::Const eval_ret;
+		if (cell->type == "$_NOT_") {
+			if (sig_a == RTLIL::S0) eval_ret = RTLIL::S1;
+			else if (sig_a == RTLIL::S1) eval_ret = RTLIL::S0;
+		}
+		else if (cell->type == "$_AND_") {
+			if (sig_a == RTLIL::S0) {
+				eval_ret = RTLIL::S0;
+				goto eval_end;
+			}
+
+			{
+				RTLIL::SigSpec sig_b = cell->getPort("\\B");
+				if (sig_b.size() > 0 && !eval(sig_b, undef, cell))
+					return false;
+				if (sig_b == RTLIL::S0) {
+					eval_ret = RTLIL::S0;
+					goto eval_end;
+				}
+
+				if (sig_a != RTLIL::State::S1 || sig_b != RTLIL::State::S1) {
+					eval_ret = RTLIL::State::Sx;
+					goto eval_end;
+				}
+
+				eval_ret = RTLIL::State::S1;
+			}
+		}
+		else log_abort();
+
+
+eval_end:
+		set(sig_y, eval_ret);
+		return true;
+	}
+
+	bool eval(RTLIL::SigSpec &sig, RTLIL::SigSpec &undef, RTLIL::Cell *busy_cell = NULL)
+	{
+		//assign_map.apply(sig);
+		values_map.apply(sig);
+
+		if (sig.is_fully_const())
+			return true;
+
+		//if (stop_signals.check_any(sig)) {
+		//	undef = stop_signals.extract(sig);
+		//	return false;
+		//}
+
+		if (busy_cell) {
+			if (busy.count(busy_cell) > 0) {
+				undef = sig;
+				return false;
+			}
+			busy.insert(busy_cell);
+		}
+
+		std::set<RTLIL::Cell*> driver_cells;
+		sig2driver.find(sig, driver_cells);
+		for (auto cell : driver_cells) {
+			if (!eval(cell, undef)) {
+				if (busy_cell)
+					busy.erase(busy_cell);
+				return false;
+			}
+		}
+
+		if (busy_cell)
+			busy.erase(busy_cell);
+
+		values_map.apply(sig);
+		if (sig.is_fully_const())
+			return true;
+
+		for (auto &c : sig.chunks())
+			if (c.wire != NULL)
+				undef.append(c);
+		return false;
+	}
+
+	bool eval(RTLIL::SigSpec &sig)
+	{
+		RTLIL::SigSpec undef;
+		return eval(sig, undef);
+	}
+};
+
 YOSYS_NAMESPACE_END
 
 #endif
-- 
2.30.2