memory_dff: Fix checking of feedback mux input when more than one mux

Signed-off-by: David Shah <dave@ds0.me>

3 files changed, 25 insertions, 3 deletions

diff --git a/passes/memory/memory_dff.cc b/passes/memory/memory_dff.cc
index 5215cce44..32b97f27a 100644
--- a/passes/memory/memory_dff.cc
+++ b/passes/memory/memory_dff.cc
@@ -17,6 +17,7 @@
  *
  */
 
+#include <algorithm>
 #include "kernel/yosys.h"
 #include "kernel/sigtools.h"
 
@@ -183,12 +184,12 @@ struct MemoryDffWorker
 		if (mux_cells_a.count(sig_data) || mux_cells_b.count(sig_data))
 		{
 			RTLIL::SigSpec en;
-			RTLIL::SigSpec check_q;
+			std::vector<RTLIL::SigSpec> check_q;
 
 			do {
 				bool enable_invert = mux_cells_a.count(sig_data) != 0;
 				Cell *mux = enable_invert ? mux_cells_a.at(sig_data) : mux_cells_b.at(sig_data);
-				check_q = sigmap(mux->getPort(enable_invert ? "\\B" : "\\A"));
+				check_q.push_back(sigmap(mux->getPort(enable_invert ? "\\B" : "\\A")));
 				sig_data = sigmap(mux->getPort("\\Y"));
 				en.append(enable_invert ? module->LogicNot(NEW_ID, mux->getPort("\\S")) : mux->getPort("\\S"));
 			} while (mux_cells_a.count(sig_data) || mux_cells_b.count(sig_data));
@@ -197,7 +198,8 @@ struct MemoryDffWorker
 				if (sigbit_users_count[bit] > 1)
 					goto skip_ff_after_read_merging;
 
-			if (find_sig_before_dff(sig_data, clk_data, clk_polarity, true) && clk_data != RTLIL::SigSpec(RTLIL::State::Sx) && sig_data == check_q)
+			if (find_sig_before_dff(sig_data, clk_data, clk_polarity, true) && clk_data != RTLIL::SigSpec(RTLIL::State::Sx) &&
+					std::all_of(check_q.begin(), check_q.end(), [&](const SigSpec &cq) {return cq == sig_data; }))
 			{
 				disconnect_dff(sig_data);
 				cell->setPort("\\CLK", clk_data);
diff --git a/tests/memories/read_two_mux.v b/tests/memories/read_two_mux.v
new file mode 100644
index 000000000..4f2e7e1cd
--- /dev/null
+++ b/tests/memories/read_two_mux.v
@@ -0,0 +1,16 @@
+// expect-wr-ports 1
+// expect-rd-ports 1
+// expect-no-rd-clk
+
+module top(input clk, input we, re, reset, input [7:0] addr, wdata, output reg [7:0] rdata);
+
+reg [7:0] bram[0:255];
+(* keep *) reg dummy;
+
+always @(posedge clk) begin
+	rdata <= re ? (reset ? 8'b0 : bram[addr]) : rdata;
+	if (we)
+		bram[addr] <= wdata;
+end
+
+endmodule
diff --git a/tests/memories/run-test.sh b/tests/memories/run-test.sh
index 76acaa9cd..8d1a8b413 100755
--- a/tests/memories/run-test.sh
+++ b/tests/memories/run-test.sh
@@ -31,6 +31,10 @@ for f in `egrep -l 'expect-(wr-ports|rd-ports|rd-clk)' *.v`; do
 		grep -q "connect \\\\RD_CLK \\$(gawk '/expect-rd-clk/ { print $3; }' $f)\$" ${f%.v}.dmp ||
 				{ echo " ERROR: Unexpected read clock."; false; }
 	fi
+	if grep -q expect-no-rd-clk $f; then
+		grep -q "connect \\\\RD_CLK 1'x\$" ${f%.v}.dmp ||
+				{ echo " ERROR: Expected no read clock."; false; }
+	fi
 	echo " ok."
 done