From bfc7164af7bf64cb2fe5d00e87bbfead841a4dc2 Mon Sep 17 00:00:00 2001
From: Eddie Hung <eddie@fpgeh.com>
Date: Tue, 6 Aug 2019 15:25:50 -0700
Subject: [PATCH] Move LSB-trimming functionality from wreduce to opt_expr

---
 passes/opt/opt_expr.cc | 25 +++++++++++++++++++++++++
 passes/opt/wreduce.cc  | 24 +-----------------------
 2 files changed, 26 insertions(+), 23 deletions(-)

diff --git a/passes/opt/opt_expr.cc b/passes/opt/opt_expr.cc
index 512ef0cbf..acdc39937 100644
--- a/passes/opt/opt_expr.cc
+++ b/passes/opt/opt_expr.cc
@@ -641,6 +641,31 @@ void replace_const_cells(RTLIL::Design *design, RTLIL::Module *module, bool cons
 					did_something = true;
 				}
 			}
+
+			if (cell->type.in("$add", "$sub")) {
+				RTLIL::SigSpec sig_a = assign_map(cell->getPort("\\A"));
+				RTLIL::SigSpec sig_b = assign_map(cell->getPort("\\B"));
+				RTLIL::SigSpec sig_y = cell->getPort("\\Y");
+				bool sub = cell->type == "$sub";
+
+				int i;
+				for (i = 0; i < GetSize(sig_y); i++) {
+					if (sig_b.at(i, State::Sx) == State::S0 && sig_a.at(i, State::Sx) != State::Sx)
+						module->connect(sig_y[i], sig_a[i]);
+					else if (!sub && sig_a.at(i, State::Sx) == State::S0 && sig_b.at(i, State::Sx) != State::Sx)
+						module->connect(sig_y[i], sig_b[i]);
+					else
+						break;
+				}
+				if (i > 0) {
+					cover_list("opt.opt_expr.fine", "$add", "$sub", cell->type.str());
+					cell->setPort("\\A", sig_a.extract_end(i));
+					cell->setPort("\\B", sig_b.extract_end(i));
+					cell->setPort("\\Y", sig_y.extract_end(i));
+					cell->fixup_parameters();
+					did_something = true;
+				}
+			}
 		}
 
 		if (cell->type == "$reduce_xor" || cell->type == "$reduce_xnor" || cell->type == "$shift" || cell->type == "$shiftx" ||
diff --git a/passes/opt/wreduce.cc b/passes/opt/wreduce.cc
index 22af0bd8b..1eeca2748 100644
--- a/passes/opt/wreduce.cc
+++ b/passes/opt/wreduce.cc
@@ -365,28 +365,6 @@ struct WreduceWorker
 			}
 		}
 
-		if (cell->type.in("$add", "$sub")) {
-			SigSpec A = mi.sigmap(cell->getPort("\\A"));
-			SigSpec B = mi.sigmap(cell->getPort("\\B"));
-			bool sub = cell->type == "$sub";
-
-			int i;
-			for (i = 0; i < GetSize(sig); i++) {
-				if (B.at(i, Sx) == S0 && A.at(i, Sx) != Sx)
-					module->connect(sig[i], A[i]);
-				else if (!sub && A.at(i, Sx) == S0 && B.at(i, Sx) != Sx)
-					module->connect(sig[i], B[i]);
-				else
-					break;
-			}
-			if (i > 0) {
-				cell->setPort("\\A", A.extract(i, -1));
-				cell->setPort("\\B", B.extract(i, -1));
-				sig.remove(0, i);
-				bits_removed += i;
-			}
-		}
-
 		if (GetSize(sig) == 0) {
 			log("Removed cell %s.%s (%s).\n", log_id(module), log_id(cell), log_id(cell->type));
 			module->remove(cell);
@@ -394,7 +372,7 @@ struct WreduceWorker
 		}
 
 		if (bits_removed) {
-			log("Removed %d bits (of %d) from port Y of cell %s.%s (%s).\n",
+			log("Removed top %d bits (of %d) from port Y of cell %s.%s (%s).\n",
 					bits_removed, GetSize(sig) + bits_removed, log_id(module), log_id(cell), log_id(cell->type));
 			cell->setPort("\\Y", sig);
 			did_something = true;
-- 
2.30.2