memory_libmap: look for ram_style attributes on surrounding signals

kernel/constids.inc

@@ -140,6 +140,7 @@ X(nomem2reg)
 X(nomeminit)
 X(nosync)
 X(nowrshmsk)
+X(no_ram)
 X(no_rw_check)
 X(O)
 X(OFFSET)

kernel/mem.cc

@@ -148,6 +148,8 @@ void Mem::emit() {
 			for (int j = 0; j < (1 << wr_ports[i].wide_log2); j++)
 				wr_port_xlat.push_back(i);
 		for (auto &port : rd_ports) {
+			for (auto attr: port.attributes)
+				cell->attributes.insert(attr);
 			if (port.cell) {
 				module->remove(port.cell);
 				port.cell = nullptr;
@@ -210,6 +212,8 @@ void Mem::emit() {
 		cell->setPort(ID::RD_ADDR, rd_addr);
 		cell->setPort(ID::RD_DATA, rd_data);
 		for (auto &port : wr_ports) {
+			for (auto attr: port.attributes)
+				cell->attributes.insert(attr);
 			if (port.cell) {
 				module->remove(port.cell);
 				port.cell = nullptr;
@@ -246,6 +250,8 @@ void Mem::emit() {
 		cell->setPort(ID::WR_ADDR, wr_addr);
 		cell->setPort(ID::WR_DATA, wr_data);
 		for (auto &init : inits) {
+			for (auto attr: init.attributes)
+				cell->attributes.insert(attr);
 			if (init.cell) {
 				module->remove(init.cell);
 				init.cell = nullptr;

passes/memory/memory_libmap.cc

@@ -481,18 +481,49 @@ void MemMapping::dump_config(MemConfig &cfg) {
 	}
 }
 
+std::pair<bool, Const> search_for_attribute(Mem mem, IdString attr) {
+	if (mem.has_attribute(attr))
+		return std::make_pair(true, mem.attributes.at(attr));
+	for (auto &port: mem.rd_ports){
+		if (port.has_attribute(attr))
+			return std::make_pair(true, port.attributes.at(attr));
+		log_debug("looking for attribute %s on signal %s\n", log_id(attr), log_signal(port.data));
+		for (SigBit bit: port.data)
+			if (bit.is_wire() && bit.wire->has_attribute(attr))
+				return std::make_pair(true, bit.wire->attributes.at(attr));
+		log_debug("looking for attribute %s on signal %s\n", log_id(attr), log_signal(port.data));
+		for (SigBit bit: port.addr)
+			if (bit.is_wire() && bit.wire->has_attribute(attr))
+				return std::make_pair(true, bit.wire->attributes.at(attr));
+	}
+	for (auto &port: mem.wr_ports){
+		if (port.has_attribute(attr))
+			return std::make_pair(true, port.attributes.at(attr));
+		log_debug("looking for attribute %s on signal %s\n", log_id(attr), log_signal(port.data));
+		for (SigBit bit: port.data)
+			if (bit.is_wire() && bit.wire->has_attribute(attr))
+				return std::make_pair(true, bit.wire->attributes.at(attr));
+		for (SigBit bit: port.addr)
+			if (bit.is_wire() && bit.wire->has_attribute(attr))
+				return std::make_pair(true, bit.wire->attributes.at(attr));
+	}
+	return std::make_pair(false, Const());
+}
+
 // Go through memory attributes to determine user-requested mapping style.
 void MemMapping::determine_style() {
 	kind = RamKind::Auto;
 	style = "";
-	if (mem.get_bool_attribute(ID::lram)) {
+	auto find_attr = search_for_attribute(mem, ID::lram);
+	if (find_attr.first && find_attr.second.as_bool()) {
 		kind = RamKind::Huge;
 		log("found attribute 'lram' on memory %s.%s, forced mapping to huge RAM\n", log_id(mem.module->name), log_id(mem.memid));
 		return;
 	}
 	for (auto attr: {ID::ram_block, ID::rom_block, ID::ram_style, ID::rom_style, ID::ramstyle, ID::romstyle, ID::syn_ramstyle, ID::syn_romstyle}) {
-		if (mem.has_attribute(attr)) {
-			Const val = mem.attributes.at(attr);
+		find_attr = search_for_attribute(mem, attr);
+		if (find_attr.first) {
+			Const val = find_attr.second;
 			if (val == 1) {
 				kind = RamKind::NotLogic;
 				log("found attribute '%s = 1' on memory %s.%s, disabled mapping to FF\n", log_id(attr), log_id(mem.module->name), log_id(mem.memid));
@@ -526,8 +557,11 @@ void MemMapping::determine_style() {
 			return;
 		}
 	}
-	if (mem.get_bool_attribute(ID::logic_block))
-		kind = RamKind::Logic;
+	for (auto attr: {ID::logic_block, ID::no_ram}){
+		find_attr = search_for_attribute(mem, attr);
+		if (find_attr.first && find_attr.second.as_bool())
+			kind = RamKind::Logic;
+	}
 }
 
 // Determine whether the memory can be mapped entirely to soft logic.

tests/memlib/generate.py

@@ -1513,6 +1513,28 @@ def __init__(self, name, src, libs, defs, cells):
 		["block_sp_full"], defs, 
 		{"RAM_BLOCK_SP": 1, "$*": add_logic}
 	))
+
+ROM_CASE = """
+module rom(input clk, input [2:0] addr, {attr}output reg [7:0] data);
+
+always @(posedge clk) begin
+	case (addr)
+		3'b000: data <= 8'h12;
+		3'b001: data <= 8'hAB;
+		3'b010: data <= 8'h42;
+		3'b011: data <= 8'h23;
+		3'b100: data <= 8'h66;
+		3'b101: data <= 8'hC0;
+		3'b110: data <= 8'h3F;
+		3'b111: data <= 8'h95;
+	endcase
+end
+
+endmodule
+"""
+
+TESTS.append(Test("rom_case", ROM_CASE.format(attr=""), ["block_sdp"], [], {"RAM_BLOCK_SDP" : 0}))
+TESTS.append(Test("rom_case_block", ROM_CASE.format(attr="(* rom_style = \"block\" *) "), ["block_sdp"], [], {"RAM_BLOCK_SDP" : 1}))
 
 with open("run-test.mk", "w") as mf:
     mf.write("ifneq ($(strip $(SEED)),)\n")