From 9d117eba9d65cf978716f1c7d41e86466ca03fc6 Mon Sep 17 00:00:00 2001
From: Clifford Wolf <clifford@clifford.at>
Date: Tue, 30 Apr 2019 14:46:12 +0200
Subject: [PATCH] Add handling of init attributes in "opt_expr -undriven"

Signed-off-by: Clifford Wolf <clifford@clifford.at>
---
 passes/opt/opt_expr.cc      | 43 +++++++++++++++++++++++++++++++++++--
 techlibs/ecp5/synth_ecp5.cc |  2 +-
 2 files changed, 42 insertions(+), 3 deletions(-)

diff --git a/passes/opt/opt_expr.cc b/passes/opt/opt_expr.cc
index af6d352af..b445afdc8 100644
--- a/passes/opt/opt_expr.cc
+++ b/passes/opt/opt_expr.cc
@@ -39,6 +39,9 @@ void replace_undriven(RTLIL::Design *design, RTLIL::Module *module)
 	SigPool used_signals;
 	SigPool all_signals;
 
+	dict<SigBit, pair<Wire*, State>> initbits;
+	pool<Wire*> revisit_initwires;
+
 	for (auto cell : module->cells())
 	for (auto &conn : cell->connections()) {
 		if (!ct.cell_known(cell->type) || ct.cell_output(cell->type, conn.first))
@@ -48,6 +51,14 @@ void replace_undriven(RTLIL::Design *design, RTLIL::Module *module)
 	}
 
 	for (auto wire : module->wires()) {
+		if (wire->attributes.count("\\init")) {
+			SigSpec sig = sigmap(wire);
+			Const initval = wire->attributes.at("\\init");
+			for (int i = 0; i < GetSize(initval) && i < GetSize(wire); i++) {
+				if (initval[i] == State::S0 || initval[i] == State::S1)
+					initbits[sig[i]] = make_pair(wire, initval[i]);
+			}
+		}
 		if (wire->port_input)
 			driven_signals.add(sigmap(wire));
 		if (wire->port_output)
@@ -67,10 +78,38 @@ void replace_undriven(RTLIL::Design *design, RTLIL::Module *module)
 		if (sig.size() == 0)
 			continue;
 
-		log_debug("Setting undriven signal in %s to undef: %s\n", RTLIL::id2cstr(module->name), log_signal(c));
-		module->connect(RTLIL::SigSig(c, RTLIL::SigSpec(RTLIL::State::Sx, c.width)));
+		Const val(RTLIL::State::Sx, GetSize(sig));
+		for (int i = 0; i < GetSize(sig); i++) {
+			SigBit bit = sigmap(sig[i]);
+			auto cursor = initbits.find(bit);
+			if (cursor != initbits.end()) {
+				revisit_initwires.insert(cursor->second.first);
+				val[i] = cursor->second.second;
+			}
+		}
+
+		log_debug("Setting undriven signal in %s to constant: %s = %s\n", RTLIL::id2cstr(module->name), log_signal(sig), log_signal(val));
+		module->connect(sig, val);
 		did_something = true;
 	}
+
+	if (!revisit_initwires.empty())
+	{
+		SigMap sm2(module);
+
+		for (auto wire : revisit_initwires) {
+			SigSpec sig = sm2(wire);
+			Const initval = wire->attributes.at("\\init");
+			for (int i = 0; i < GetSize(initval) && i < GetSize(wire); i++) {
+				if (SigBit(initval[i]) == sig[i])
+					initval[i] = State::Sx;
+			}
+			if (initval.is_fully_undef())
+				wire->attributes.erase("\\init");
+			else
+				wire->attributes["\\init"] = initval;
+		}
+	}
 }
 
 void replace_cell(SigMap &assign_map, RTLIL::Module *module, RTLIL::Cell *cell, std::string info, std::string out_port, RTLIL::SigSpec out_val)
diff --git a/techlibs/ecp5/synth_ecp5.cc b/techlibs/ecp5/synth_ecp5.cc
index 4b889d672..c6e12248e 100644
--- a/techlibs/ecp5/synth_ecp5.cc
+++ b/techlibs/ecp5/synth_ecp5.cc
@@ -253,7 +253,7 @@ struct SynthEcp5Pass : public ScriptPass
 			if (!nodffe)
 				run("dff2dffe -direct-match $_DFF_* -direct-match $__DFFS_*");
 			run("techmap -D NO_LUT -map +/ecp5/cells_map.v");
-			run("opt_expr -mux_undef");
+			run("opt_expr -undriven -mux_undef");
 			run("simplemap");
 			run("ecp5_ffinit");
 		}
-- 
2.30.2