memory: Introduce $meminit_v2 cell, with EN input.

CHANGELOG

@@ -70,6 +70,7 @@ Yosys 0.9 .. Yosys 0.9-dev
     - Added "dfflegalize" pass
     - Added "_TECHMAP_CELLNAME_" parameter for "techmap" pass
     - Merged "dffsr2dff", "opt_rmdff", "dff2dffe", "dff2dffs", "peepopt.dffmux" passes into a new "opt_dff" pass
+    - Added $meminit_v2 cells (with support for write mask)
 
 Yosys 0.8 .. Yosys 0.9
 ----------------------

kernel/celltypes.h

@@ -157,6 +157,7 @@ struct CellTypes
 		setup_type(ID($memrd), {ID::CLK, ID::EN, ID::ADDR}, {ID::DATA});
 		setup_type(ID($memwr), {ID::CLK, ID::EN, ID::ADDR, ID::DATA}, pool<RTLIL::IdString>());
 		setup_type(ID($meminit), {ID::ADDR, ID::DATA}, pool<RTLIL::IdString>());
+		setup_type(ID($meminit_v2), {ID::ADDR, ID::DATA, ID::EN}, pool<RTLIL::IdString>());
 		setup_type(ID($mem), {ID::RD_CLK, ID::RD_EN, ID::RD_ADDR, ID::WR_CLK, ID::WR_EN, ID::WR_ADDR, ID::WR_DATA}, {ID::RD_DATA});
 
 		setup_type(ID($fsm), {ID::CLK, ID::ARST, ID::CTRL_IN}, {ID::CTRL_OUT});

kernel/mem.cc

@@ -263,8 +263,11 @@ void Mem::emit() {
 		}
 		idx = 0;
 		for (auto &init : inits) {
+			bool v2 = !init.en.is_fully_ones();
 			if (!init.cell)
-				init.cell = module->addCell(NEW_ID, ID($meminit));
+				init.cell = module->addCell(NEW_ID, v2 ? ID($meminit_v2) : ID($meminit));
+			else
+				init.cell->type = v2 ? ID($meminit_v2) : ID($meminit);
 			init.cell->attributes = init.attributes;
 			init.cell->parameters[ID::MEMID] = memid.str();
 			init.cell->parameters[ID::ABITS] = GetSize(init.addr);
@@ -273,6 +276,10 @@ void Mem::emit() {
 			init.cell->parameters[ID::PRIORITY] = idx++;
 			init.cell->setPort(ID::ADDR, init.addr);
 			init.cell->setPort(ID::DATA, init.data);
+			if (v2)
+				init.cell->setPort(ID::EN, init.en);
+			else
+				init.cell->unsetPort(ID::EN);
 		}
 	}
 }
@@ -289,6 +296,14 @@ void Mem::coalesce_inits() {
 	for (auto &init : inits) {
 		if (init.removed)
 			continue;
+		bool valid = false;
+		for (auto bit : init.en)
+			if (bit == State::S1)
+				valid = true;
+		if (!valid) {
+			init.removed = true;
+			continue;
+		}
 		int addr = init.addr.as_int();
 		int addr_e = addr + GetSize(init.data) / width;
 		auto it_e = chunks.upper_bound(addr_e);
@@ -335,6 +350,13 @@ void Mem::coalesce_inits() {
 		int caddr_e = chunks[caddr];
 		auto &chunk_inits = it.second;
 		if (GetSize(chunk_inits) == 1) {
+			auto &init = inits[chunk_inits[0]];
+			if (!init.en.is_fully_ones()) {
+				for (int i = 0; i < GetSize(init.data); i++)
+					if (init.en[i % width] != State::S1)
+						init.data[i] = State::Sx;
+				init.en = Const(State::S1, width);
+			}
 			continue;
 		}
 		Const cdata(State::Sx, (caddr_e - caddr) * width);
@@ -344,12 +366,14 @@ void Mem::coalesce_inits() {
 			log_assert(offset >= 0);
 			log_assert(offset + GetSize(init.data) <= GetSize(cdata));
 			for (int i = 0; i < GetSize(init.data); i++)
-				cdata.bits[i+offset] = init.data.bits[i];
+				if (init.en[i % width] == State::S1)
+					cdata.bits[i+offset] = init.data.bits[i];
 			init.removed = true;
 		}
 		MemInit new_init;
 		new_init.addr = caddr;
 		new_init.data = cdata;
+		new_init.en = Const(State::S1, width);
 		inits.push_back(new_init);
 	}
 }
@@ -361,7 +385,7 @@ Const Mem::get_init_data() const {
 			continue;
 		int offset = (init.addr.as_int() - start_offset) * width;
 		for (int i = 0; i < GetSize(init.data); i++)
-			if (0 <= i+offset && i+offset < GetSize(init_data))
+			if (0 <= i+offset && i+offset < GetSize(init_data) && init.en[i % width] == State::S1)
 				init_data.bits[i+offset] = init.data.bits[i];
 	}
 	return init_data;
@@ -432,7 +456,7 @@ namespace {
 					wr_ports[cell->parameters.at(ID::MEMID).decode_string()].insert(cell);
 				else if (cell->type == ID($memrd))
 					rd_ports[cell->parameters.at(ID::MEMID).decode_string()].insert(cell);
-				else if (cell->type == ID($meminit))
+				else if (cell->type.in(ID($meminit), ID($meminit_v2)))
 					inits[cell->parameters.at(ID::MEMID).decode_string()].insert(cell);
 			}
 		}
@@ -507,6 +531,14 @@ namespace {
 					log_error("Non-constant data %s in memory initialization %s.\n", log_signal(data), log_id(cell));
 				init.addr = addr.as_const();
 				init.data = data.as_const();
+				if (cell->type == ID($meminit_v2)) {
+					auto en = cell->getPort(ID::EN);
+					if (!en.is_fully_const())
+						log_error("Non-constant enable %s in memory initialization %s.\n", log_signal(en), log_id(cell));
+					init.en = en.as_const();
+				} else {
+					init.en = RTLIL::Const(State::S1, mem->width);
+				}
 				inits.push_back(std::make_pair(cell->parameters.at(ID::PRIORITY).as_int(), init));
 			}
 			std::sort(inits.begin(), inits.end(), [](const std::pair<int, MemInit> &a, const std::pair<int, MemInit> &b) { return a.first < b.first; });
@@ -558,6 +590,7 @@ namespace {
 					MemInit minit;
 					minit.addr = res.start_offset + pos;
 					minit.data = init.extract(pos * res.width, (epos - pos) * res.width, State::Sx);
+					minit.en = RTLIL::Const(State::S1, res.width);
 					res.inits.push_back(minit);
 					pos = epos;
 				}

kernel/mem.h

@@ -69,6 +69,7 @@ struct MemInit : RTLIL::AttrObject {
 	Cell *cell;
 	Const addr;
 	Const data;
+	Const en;
 	MemInit() : removed(false), cell(nullptr) {}
 };
 
@@ -101,7 +102,8 @@ struct Mem : RTLIL::AttrObject {
 	// address ranges, they are combined into one, with the higher-priority
 	// one's data overwriting the other.  Running this results in
 	// an inits list equivalent to the original, in which all entries
-	// cover disjoint (and non-touching) address ranges.
+	// cover disjoint (and non-touching) address ranges, and all enable
+	// masks are all-1.
 	void coalesce_inits();
 
 	// Checks consistency of this memory and all its ports/inits, using

kernel/rtlil.cc

@@ -1414,6 +1414,16 @@ namespace {
 				return;
 			}
 
+			if (cell->type == ID($meminit_v2)) {
+				param(ID::MEMID);
+				param(ID::PRIORITY);
+				port(ID::ADDR, param(ID::ABITS));
+				port(ID::DATA, param(ID::WIDTH) * param(ID::WORDS));
+				port(ID::EN, param(ID::WIDTH));
+				check_expected();
+				return;
+			}
+
 			if (cell->type == ID($mem)) {
 				param(ID::MEMID);
 				param(ID::SIZE);
@@ -3177,7 +3187,7 @@ void RTLIL::Cell::fixup_parameters(bool set_a_signed, bool set_b_signed)
 
 bool RTLIL::Cell::has_memid() const
 {
-	return type.in(ID($memwr), ID($memrd), ID($meminit));
+	return type.in(ID($memwr), ID($memrd), ID($meminit), ID($meminit_v2));
 }
 
 bool RTLIL::Cell::is_mem_cell() const

manual/CHAPTER_CellLib.tex

@@ -338,14 +338,14 @@ In addition to {\tt \$dlatch} ports and parameters, they also have multi-bit
 \subsection{Memories}
 \label{sec:memcells}
 
-Memories are either represented using RTLIL::Memory objects, {\tt \$memrd}, {\tt \$memwr}, and {\tt \$meminit}
+Memories are either represented using RTLIL::Memory objects, {\tt \$memrd}, {\tt \$memwr}, and {\tt \$meminit\_v2}
 cells, or by {\tt \$mem} cells alone.
 
 In the first alternative the RTLIL::Memory objects hold the general metadata for the memory (bit width,
 size in number of words, etc.) and for each port a {\tt \$memrd} (read port) or {\tt \$memwr} (write port)
 cell is created. Having individual cells for read and write ports has the advantage that they can be
 consolidated using resource sharing passes. In some cases this drastically reduces the number of required
-ports on the memory cell. In this alternative, memory initialization data is represented by {\tt \$meminit} cells,
+ports on the memory cell. In this alternative, memory initialization data is represented by {\tt \$meminit\_v2} cells,
 which allow delaying constant folding for initialization addresses and data until after the frontend finishes.
 
 The {\tt \$memrd} cells have a clock input \B{CLK}, an enable input \B{EN}, an
@@ -401,8 +401,9 @@ edge if this parameter is {\tt 1'b0}.
 The cell with the higher integer value in this parameter wins a write conflict.
 \end{itemize}
 
-The {\tt \$meminit} cells have an address input \B{ADDR} and a data input \B{DATA}, with the width
-of the \B{DATA} port equal to \B{WIDTH} parameter times \B{WORDS} parameter. Both of the inputs
+The {\tt \$meminit\_v2} cells have an address input \B{ADDR}, a data input \B{DATA}, with the width
+of the \B{DATA} port equal to \B{WIDTH} parameter times \B{WORDS} parameter, and a bit enable mask input
+\B{EN} with width equal to \B{WIDTH} parameter. All three of the inputs
 must resolve to a constant for synthesis to succeed.
 
 \begin{itemize}
@@ -497,7 +498,7 @@ This input is \B{WR\_PORTS}*\B{ABITS} bits wide, containing all address signals
 This input is \B{WR\_PORTS}*\B{WIDTH} bits wide, containing all data signals for the write ports.
 \end{itemize}
 
-The {\tt memory\_collect} pass can be used to convert discrete {\tt \$memrd}, {\tt \$memwr}, and {\tt \$meminit} cells
+The {\tt memory\_collect} pass can be used to convert discrete {\tt \$memrd}, {\tt \$memwr}, and {\tt \$meminit\_v2} cells
 belonging to the same memory to a single {\tt \$mem} cell, whereas the {\tt memory\_unpack} pass performs the inverse operation.
 The {\tt memory\_dff} pass can combine asynchronous memory ports that are fed by or feeding registers into synchronous memory ports.
 The {\tt memory\_bram} pass can be used to recognize {\tt \$mem} cells that can be implemented with a block RAM resource on an FPGA.

passes/opt/opt_clean.cc

@@ -117,7 +117,7 @@ void rmunused_module_cells(Module *module, bool verbose)
 	}
 
 	for (Cell *cell : module->cells()) {
-		if (cell->type.in(ID($memwr), ID($meminit))) {
+		if (cell->type.in(ID($memwr), ID($meminit), ID($meminit_v2))) {
 			IdString mem_id = cell->getParam(ID::MEMID).decode_string();
 			mem2cells[mem_id].insert(cell);
 		}

passes/opt/wreduce.cc

@@ -558,7 +558,7 @@ struct WreducePass : public Pass {
 					}
 				}
 
-				if (!opt_memx && c->type.in(ID($memrd), ID($memwr), ID($meminit))) {
+				if (!opt_memx && c->type.in(ID($memrd), ID($memwr), ID($meminit), ID($meminit_v2))) {
 					IdString memid = c->getParam(ID::MEMID).decode_string();
 					RTLIL::Memory *mem = module->memories.at(memid);
 					if (mem->start_offset >= 0) {

passes/sat/sim.cc

@@ -559,6 +559,7 @@ struct SimInstance
 			MemInit minit;
 			minit.addr = mem.mem->start_offset;
 			minit.data = mem.data;
+			minit.en = Const(State::S1, mem.mem->width);
 			mem.mem->inits.push_back(minit);
 			mem.mem->emit();
 		}

techlibs/common/simlib.v

@@ -2233,6 +2233,30 @@ endmodule
 
 // --------------------------------------------------------
 
+module \$meminit_v2 (ADDR, DATA, EN);
+
+parameter MEMID = "";
+parameter ABITS = 8;
+parameter WIDTH = 8;
+parameter WORDS = 1;
+
+parameter PRIORITY = 0;
+
+input [ABITS-1:0] ADDR;
+input [WORDS*WIDTH-1:0] DATA;
+input [WIDTH-1:0] EN;
+
+initial begin
+	if (MEMID != "") begin
+		$display("ERROR: Found non-simulatable instance of $meminit_v2!");
+		$finish;
+	end
+end
+
+endmodule
+
+// --------------------------------------------------------
+
 module \$mem (RD_CLK, RD_EN, RD_ADDR, RD_DATA, WR_CLK, WR_EN, WR_ADDR, WR_DATA);
 
 parameter MEMID = "";