memory_map: add -attr option, to respect inference attributes.

Before this commit, memory_map (which is always a part of a synth
script) would always pick up any $mem cell that was not processed
by a preceding pass and lower it down to $dff/$mux cells.
This is undesirable for two reasons:
  * If there is an explicit inference attribute set on a $mem cell,
    e.g. (* ram_block *), then it is arguably incorrect to map such
    a memory to $dff/$mux cells.
  * If memory_map tries to lower a memory that was intended to
    be mapped to a large BRAM, it often takes extraordinarily long
    time to finish, produces an extremely large log file, and outputs
    an unusable design.

After this commit, properly invoked memory_map will not map any
memory that has an explicit inference attribute specified, solving
the first issue, and alleviating the second. The default behavior
is not changed.

1 files changed, 113 insertions, 6 deletions

diff --git a/passes/memory/memory_map.cc b/passes/memory/memory_map.cc
index 65bccb5ef..8820d6d72 100644
--- a/passes/memory/memory_map.cc
+++ b/passes/memory/memory_map.cc
@@ -28,11 +28,32 @@ PRIVATE_NAMESPACE_BEGIN
 
 struct MemoryMapWorker
 {
+	bool attr_icase = false;
+	dict<RTLIL::IdString, std::vector<RTLIL::Const>> attributes;
+
 	RTLIL::Design *design;
 	RTLIL::Module *module;
 
 	std::map<std::pair<RTLIL::SigSpec, RTLIL::SigSpec>, RTLIL::SigBit> decoder_cache;
 
+	MemoryMapWorker(RTLIL::Design *design, RTLIL::Module *module) : design(design), module(module) {}
+
+	std::string map_case(std::string value) const
+	{
+		if (attr_icase) {
+			for (char &c : value)
+				c = tolower(c);
+		}
+		return value;
+	}
+
+	RTLIL::Const map_case(RTLIL::Const value) const
+	{
+		if (value.flags & RTLIL::CONST_FLAG_STRING)
+			return map_case(value.decode_string());
+		return value;
+	}
+
 	std::string genid(RTLIL::IdString name, std::string token1 = "", int i = -1, std::string token2 = "", int j = -1, std::string token3 = "", int k = -1, std::string token4 = "")
 	{
 		std::stringstream sstr;
@@ -98,6 +119,36 @@ struct MemoryMapWorker
 			return;
 		}
 
+		// check if attributes allow us to infer FFRAM for this cell
+		for (const auto &attr : attributes) {
+			if (cell->attributes.count(attr.first)) {
+				const auto &cell_attr = cell->attributes[attr.first];
+				if (attr.second.empty()) {
+					log("Not mapping memory cell %s in module %s (attribute %s is set).\n",
+							cell->name.c_str(), module->name.c_str(), attr.first.c_str());
+					return;
+				}
+
+				bool found = false;
+				for (auto &value : attr.second) {
+					if (map_case(cell_attr) == map_case(value)) {
+						found = true;
+						break;
+					}
+				}
+				if (!found) {
+					if (cell_attr.flags & RTLIL::CONST_FLAG_STRING) {
+						log("Not mapping memory cell %s in module %s (attribute %s is set to \"%s\").\n",
+								cell->name.c_str(), module->name.c_str(), attr.first.c_str(), cell_attr.decode_string().c_str());
+					} else {
+						log("Not mapping memory cell %s in module %s (attribute %s is set to %d).\n",
+								cell->name.c_str(), module->name.c_str(), attr.first.c_str(), cell_attr.as_int());
+					}
+					return;
+				}
+			}
+		}
+
 		// all write ports must share the same clock
 		RTLIL::SigSpec clocks = cell->getPort("\\WR_CLK");
 		RTLIL::Const clocks_pol = cell->parameters["\\WR_CLK_POLARITY"];
@@ -339,7 +390,7 @@ struct MemoryMapWorker
 		module->remove(cell);
 	}
 
-	MemoryMapWorker(RTLIL::Design *design, RTLIL::Module *module) : design(design), module(module)
+	void run()
 	{
 		std::vector<RTLIL::Cell*> cells;
 		for (auto cell : module->selected_cells())
@@ -356,17 +407,73 @@ struct MemoryMapPass : public Pass {
 	{
 		//   |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
 		log("\n");
-		log("    memory_map [selection]\n");
+		log("    memory_map [options] [selection]\n");
 		log("\n");
 		log("This pass converts multiport memory cells as generated by the memory_collect\n");
 		log("pass to word-wide DFFs and address decoders.\n");
 		log("\n");
+		log("    -attr !<name>\n");
+		log("        do not map memories that have attribute <name> set.\n");
+		log("\n");
+		log("    -attr <name>[=<value>]\n");
+		log("        for memories that have attribute <name> set, only map them if its value\n");
+		log("        is a string <value> (if specified), or an integer 1 (otherwise). if this\n");
+		log("        option is specified multiple times, map the memory if the attribute is\n");
+		log("        to any of the values.\n");
+		log("\n");
+		log("    -iattr\n");
+		log("        for -attr, ignore case of <value>.\n");
+		log("\n");
 	}
-	void execute(std::vector<std::string> args, RTLIL::Design *design) YS_OVERRIDE {
+	void execute(std::vector<std::string> args, RTLIL::Design *design) YS_OVERRIDE
+	{
+		bool attr_icase = false;
+		dict<RTLIL::IdString, std::vector<RTLIL::Const>> attributes;
+
 		log_header(design, "Executing MEMORY_MAP pass (converting $mem cells to logic and flip-flops).\n");
-		extra_args(args, 1, design);
-		for (auto mod : design->selected_modules())
-			MemoryMapWorker(design, mod);
+
+		size_t argidx;
+		for (argidx = 1; argidx < args.size(); argidx++)
+		{
+			if (args[argidx] == "-attr" && argidx + 1 < args.size())
+			{
+				std::string attr_arg = args[++argidx];
+				std::string name;
+				RTLIL::Const value;
+				size_t eq_at = attr_arg.find('=');
+				if (eq_at != std::string::npos) {
+					name  = attr_arg.substr(0, eq_at);
+					value = attr_arg.substr(eq_at + 1);
+				} else {
+					name  = attr_arg;
+					value = RTLIL::Const(1);
+				}
+				if (attr_arg.size() > 1 && attr_arg[0] == '!') {
+					if (value != RTLIL::Const(1)) {
+						--argidx;
+						break; // we don't support -attr !<name>=<value>
+					}
+					attributes[RTLIL::escape_id(name.substr(1))].clear();
+				} else {
+					attributes[RTLIL::escape_id(name)].push_back(value);
+				}
+				continue;
+			}
+			if (args[argidx] == "-iattr")
+			{
+				attr_icase = true;
+				continue;
+			}
+			break;
+		}
+		extra_args(args, argidx, design);
+
+		for (auto mod : design->selected_modules()) {
+			MemoryMapWorker worker(design, mod);
+			worker.attr_icase = attr_icase;
+			worker.attributes = attributes;
+			worker.run();
+		}
 	}
 } MemoryMapPass;