From 9da4fe747e96e68a0c8ca8420659ff016cc8481b Mon Sep 17 00:00:00 2001
From: "N. Engelhardt" <nak@yosyshq.com>
Date: Tue, 28 Jan 2025 11:23:36 +0100
Subject: [PATCH] fix bus ioff inference

---
 techlibs/quicklogic/ql_ioff.cc           | 18 +++---
 tests/arch/quicklogic/qlf_k6n10f/ioff.ys | 81 ++++++++++++++++++++++++
 2 files changed, 91 insertions(+), 8 deletions(-)

diff --git a/techlibs/quicklogic/ql_ioff.cc b/techlibs/quicklogic/ql_ioff.cc
index c857fc35d..e08850fb7 100644
--- a/techlibs/quicklogic/ql_ioff.cc
+++ b/techlibs/quicklogic/ql_ioff.cc
@@ -39,13 +39,14 @@ struct QlIoffPass : public Pass {
 				if (!(e_const && r_const && s_const))
 					continue;
 
-				auto d_sig = modwalker.sigmap(cell->getPort(ID::D));
-				if (d_sig.is_wire() && d_sig.as_wire()->port_input) {
+				SigSpec d = cell->getPort(ID::D);
+				if (GetSize(d) != 1) continue;
+				SigBit d_sig = modwalker.sigmap(d[0]);
+				if (d_sig.is_wire() && d_sig.wire->port_input) {
 					log_debug("Cell %s is potentially eligible for promotion to input IOFF.\n", cell->name.c_str());
 					// check that d_sig has no other consumers
-					if (GetSize(d_sig) != 1) continue;
 					pool<ModWalker::PortBit> portbits;
-					modwalker.get_consumers(portbits, d_sig[0]);
+					modwalker.get_consumers(portbits, d_sig);
 					if (GetSize(portbits) > 1) {
 						log_debug("not promoting: d_sig has other consumers\n");
 						continue;
@@ -53,13 +54,14 @@ struct QlIoffPass : public Pass {
 					cells_to_replace.insert(cell);
 					continue; // no need to check Q if we already put it on the list
 				}
-				auto q_sig = modwalker.sigmap(cell->getPort(ID::Q));
-				if (q_sig.is_wire() && q_sig.as_wire()->port_output) {
+				SigSpec q = cell->getPort(ID::Q);
+				if (GetSize(q) != 1) continue;
+				SigBit q_sig = modwalker.sigmap(q[0]);
+				if (q_sig.is_wire() && q_sig.wire->port_output) {
 					log_debug("Cell %s is potentially eligible for promotion to output IOFF.\n", cell->name.c_str());
 					// check that q_sig has no other consumers
-					if (GetSize(q_sig) != 1) continue;
 					pool<ModWalker::PortBit> portbits;
-					modwalker.get_consumers(portbits, q_sig[0]);
+					modwalker.get_consumers(portbits, q_sig);
 					if (GetSize(portbits) > 0) {
 						log_debug("not promoting: q_sig has other consumers\n");
 						continue;
diff --git a/tests/arch/quicklogic/qlf_k6n10f/ioff.ys b/tests/arch/quicklogic/qlf_k6n10f/ioff.ys
index bd69a28d4..3144eda13 100644
--- a/tests/arch/quicklogic/qlf_k6n10f/ioff.ys
+++ b/tests/arch/quicklogic/qlf_k6n10f/ioff.ys
@@ -9,6 +9,18 @@ EOF
 synth_quicklogic -family qlf_k6n10f -top top
 select -assert-count 1 t:dff
 
+design -reset
+# test: acceptable for output IOFF promotion
+read_verilog <<EOF
+module top (input clk, input [3:0] a, output reg [3:0] o);
+    always @(posedge clk) begin
+        o <= ~a;
+    end
+endmodule
+EOF
+synth_quicklogic -family qlf_k6n10f -top top
+select -assert-count 4 t:dff
+
 design -reset
 # test: acceptable for input IOFF promotion
 read_verilog <<EOF
@@ -23,6 +35,20 @@ EOF
 synth_quicklogic -family qlf_k6n10f -top top
 select -assert-count 1 t:dff
 
+design -reset
+# test: acceptable for input IOFF promotion
+read_verilog <<EOF
+module top (input clk, input [3:0] a, output [3:0] o);
+    reg [3:0] r;
+    always @(posedge clk) begin
+        r <= a;
+    end
+    assign o = ~r;
+endmodule
+EOF
+synth_quicklogic -family qlf_k6n10f -top top
+select -assert-count 4 t:dff
+
 design -reset
 # test: acceptable for either IOFF promotion
 read_verilog <<EOF
@@ -47,6 +73,18 @@ EOF
 synth_quicklogic -family qlf_k6n10f -top top
 select -assert-count 0 t:dff
 
+design -reset
+# test: not acceptable for output IOFF promotion: output signal is used
+read_verilog <<EOF
+module top (input clk, input [3:0] a, output reg [3:0] o);
+    always @(posedge clk) begin
+        o <= ~a | o;
+    end
+endmodule
+EOF
+synth_quicklogic -family qlf_k6n10f -top top
+select -assert-count 0 t:dff
+
 design -reset
 # test: not acceptable for input IOFF promotion: input signal is used
 read_verilog <<EOF
@@ -62,6 +100,21 @@ EOF
 synth_quicklogic -family qlf_k6n10f -top top
 select -assert-count 0 t:dff
 
+design -reset
+# test: not acceptable for input IOFF promotion: input signal is used
+read_verilog <<EOF
+module top (input clk, input [3:0] a, output [3:0] o, output [3:0] p);
+    reg [3:0] r;
+    always @(posedge clk) begin
+        r <= a;
+    end
+    assign o = ~r;
+    assign p = ~a;
+endmodule
+EOF
+synth_quicklogic -family qlf_k6n10f -top top
+select -assert-count 0 t:dff
+
 design -reset
 # test: not acceptable for IOFF promotion: FF has reset
 read_verilog <<EOF
@@ -77,6 +130,21 @@ EOF
 synth_quicklogic -family qlf_k6n10f -top top
 select -assert-count 0 t:dff
 
+design -reset
+# test: not acceptable for IOFF promotion: FF has reset
+read_verilog <<EOF
+module top (input clk, input rst, input [3:0] a, output reg [3:0] o);
+    always @(posedge clk) begin
+        if (rst)
+            o <= 4'b0;
+        else
+            o <= a;
+    end
+endmodule
+EOF
+synth_quicklogic -family qlf_k6n10f -top top
+select -assert-count 0 t:dff
+
 design -reset
 # test: not acceptable for IOFF promotion: FF has enable
 read_verilog <<EOF
@@ -89,3 +157,16 @@ endmodule
 EOF
 synth_quicklogic -family qlf_k6n10f -top top
 select -assert-count 0 t:dff
+
+design -reset
+# test: not acceptable for IOFF promotion: FF has enable
+read_verilog <<EOF
+module top (input clk, input en, input [3:0] a, output reg [3:0] o);
+    always @(posedge clk) begin
+        if (en)
+            o <= a;
+    end
+endmodule
+EOF
+synth_quicklogic -family qlf_k6n10f -top top
+select -assert-count 0 t:dff