From 0e1661f84e99f1d4a487e7a432b05a6cb2071714 Mon Sep 17 00:00:00 2001
From: Clifford Wolf <clifford@clifford.at>
Date: Thu, 7 Nov 2013 16:53:28 +0100
Subject: [PATCH] Fixed type of sign extension in opt_const $eq/$ne handling

---
 kernel/rtlil.cc         | 16 ++++++++++++++++
 kernel/rtlil.h          |  1 +
 passes/opt/opt_const.cc | 18 +++++++++---------
 3 files changed, 26 insertions(+), 9 deletions(-)

diff --git a/kernel/rtlil.cc b/kernel/rtlil.cc
index d64a37bb8..4388acb1d 100644
--- a/kernel/rtlil.cc
+++ b/kernel/rtlil.cc
@@ -940,6 +940,22 @@ void RTLIL::SigSpec::extend(int width, bool is_signed)
 	optimize();
 }
 
+void RTLIL::SigSpec::extend_un0(int width, bool is_signed)
+{
+	if (this->width > width)
+		remove(width, this->width - width);
+	
+	if (this->width < width) {
+		RTLIL::SigSpec padding = this->width > 0 ? extract(this->width - 1, 1) : RTLIL::SigSpec(RTLIL::State::S0);
+		if (!is_signed)
+			padding = RTLIL::SigSpec(RTLIL::State::S0);
+		while (this->width < width)
+			append(padding);
+	}
+
+	optimize();
+}
+
 void RTLIL::SigSpec::check() const
 {
 	int w = 0;
diff --git a/kernel/rtlil.h b/kernel/rtlil.h
index 6cb471b58..376a09abf 100644
--- a/kernel/rtlil.h
+++ b/kernel/rtlil.h
@@ -342,6 +342,7 @@ struct RTLIL::SigSpec {
 	void append(const RTLIL::SigSpec &signal);
 	bool combine(RTLIL::SigSpec signal, RTLIL::State freeState = RTLIL::State::Sz, bool override = false);
 	void extend(int width, bool is_signed = false);
+	void extend_un0(int width, bool is_signed = false);
 	void check() const;
 	bool operator <(const RTLIL::SigSpec &other) const;
 	bool operator ==(const RTLIL::SigSpec &other) const;
diff --git a/passes/opt/opt_const.cc b/passes/opt/opt_const.cc
index b04ed9e72..f20181f1e 100644
--- a/passes/opt/opt_const.cc
+++ b/passes/opt/opt_const.cc
@@ -151,8 +151,8 @@ void replace_const_cells(RTLIL::Design *design, RTLIL::Module *module, bool cons
 
 			if (cell->parameters["\\A_WIDTH"].as_int() != cell->parameters["\\B_WIDTH"].as_int()) {
 				int width = std::max(cell->parameters["\\A_WIDTH"].as_int(), cell->parameters["\\B_WIDTH"].as_int());
-				a.extend(width, cell->parameters["\\A_SIGNED"].as_bool() && cell->parameters["\\B_SIGNED"].as_bool());
-				b.extend(width, cell->parameters["\\A_SIGNED"].as_bool() && cell->parameters["\\B_SIGNED"].as_bool());
+				a.extend_un0(width, cell->parameters["\\A_SIGNED"].as_bool() && cell->parameters["\\B_SIGNED"].as_bool());
+				b.extend_un0(width, cell->parameters["\\A_SIGNED"].as_bool() && cell->parameters["\\B_SIGNED"].as_bool());
 			}
 
 			RTLIL::SigSpec new_a, new_b;
@@ -168,6 +168,13 @@ void replace_const_cells(RTLIL::Design *design, RTLIL::Module *module, bool cons
 				new_b.append(b.chunks[i]);
 			}
 
+			if (new_a.width == 0) {
+				RTLIL::SigSpec new_y = RTLIL::SigSpec(cell->type == "$eq" ?  RTLIL::State::S1 : RTLIL::State::S0);
+				new_y.extend(cell->parameters["\\Y_WIDTH"].as_int(), false);
+				replace_cell(module, cell, "empty", "\\Y", new_y);
+				goto next_cell;
+			}
+
 			if (new_a.width != a.width) {
 				new_a.optimize();
 				new_b.optimize();
@@ -176,13 +183,6 @@ void replace_const_cells(RTLIL::Design *design, RTLIL::Module *module, bool cons
 				cell->parameters["\\A_WIDTH"] = new_a.width;
 				cell->parameters["\\B_WIDTH"] = new_b.width;
 			}
-
-			if (new_a.width == 0) {
-				RTLIL::SigSpec new_y = RTLIL::SigSpec(cell->type == "$eq" ?  RTLIL::State::S1 : RTLIL::State::S0);
-				new_y.extend(cell->parameters["\\Y_WIDTH"].as_int(), false);
-				replace_cell(module, cell, "empty", "\\Y", new_y);
-				goto next_cell;
-			}
 		}
 
 		if ((cell->type == "$eq" || cell->type == "$ne") && cell->parameters["\\Y_WIDTH"].as_int() == 1 &&
-- 
2.30.2