yosys/passes/techmap/extract_counter.cc

652 lines
19 KiB
C++

/*
* yosys -- Yosys Open SYnthesis Suite
*
* Copyright (C) 2017 Clifford Wolf <clifford@clifford.at>
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*
*/
#include "kernel/yosys.h"
#include "kernel/sigtools.h"
#include "kernel/modtools.h"
USING_YOSYS_NAMESPACE
PRIVATE_NAMESPACE_BEGIN
//get the list of cells hooked up to at least one bit of a given net
pool<Cell*> get_other_cells(const RTLIL::SigSpec& port, ModIndex& index, Cell* src)
{
pool<Cell*> rval;
for(auto b : port)
{
pool<ModIndex::PortInfo> ports = index.query_ports(b);
for(auto x : ports)
{
if(x.cell == src)
continue;
rval.insert(x.cell);
}
}
return rval;
}
//return true if there is a full-width bus connection from cell a port ap to cell b port bp
//if other_conns_allowed is false, then we require a strict point to point connection (no other links)
bool is_full_bus(
const RTLIL::SigSpec& sig,
ModIndex& index,
Cell* a,
RTLIL::IdString ap,
Cell* b,
RTLIL::IdString bp,
bool other_conns_allowed = false)
{
for(auto s : sig)
{
pool<ModIndex::PortInfo> ports = index.query_ports(s);
bool found_a = false;
bool found_b = false;
for(auto x : ports)
{
if( (x.cell == a) && (x.port == ap) )
found_a = true;
else if( (x.cell == b) && (x.port == bp) )
found_b = true;
else if(!other_conns_allowed)
return false;
}
if( (!found_a) || (!found_b) )
return false;
}
return true;
}
//return true if the signal connects to one port only (nothing on the other end)
bool is_unconnected(const RTLIL::SigSpec& port, ModIndex& index)
{
for(auto b : port)
{
pool<ModIndex::PortInfo> ports = index.query_ports(b);
if(ports.size() > 1)
return false;
}
return true;
}
struct CounterExtraction
{
int width; //counter width
RTLIL::Wire* rwire; //the register output
bool has_reset; //true if we have a reset
bool has_ce; //true if we have a clock enable
RTLIL::SigSpec rst; //reset pin
bool rst_inverted; //true if reset is active low
bool rst_to_max; //true if we reset to max instead of 0
int count_value; //value we count from
RTLIL::SigSpec ce; //clock signal
RTLIL::SigSpec clk; //clock enable, if any
RTLIL::SigSpec outsig; //counter output signal
RTLIL::Cell* count_mux; //counter mux
RTLIL::Cell* count_reg; //counter register
RTLIL::Cell* underflow_inv; //inverter reduction for output-underflow detect
pool<ModIndex::PortInfo> pouts; //Ports that take a parallel output from us
};
//attempt to extract a counter centered on the given adder cell
//For now we only support DOWN counters.
//TODO: up/down support
int counter_tryextract(
ModIndex& index,
Cell *cell,
CounterExtraction& extract,
pool<RTLIL::IdString>& parallel_cells,
int maxwidth)
{
SigMap& sigmap = index.sigmap;
//A counter with less than 2 bits makes no sense
//TODO: configurable min threshold
int a_width = cell->getParam("\\A_WIDTH").as_int();
extract.width = a_width;
if( (a_width < 2) || (a_width > maxwidth) )
return 1;
//Second input must be a single bit
int b_width = cell->getParam("\\B_WIDTH").as_int();
if(b_width != 1)
return 2;
//Both inputs must be unsigned, so don't extract anything with a signed input
bool a_sign = cell->getParam("\\A_SIGNED").as_bool();
bool b_sign = cell->getParam("\\B_SIGNED").as_bool();
if(a_sign || b_sign)
return 3;
//To be a counter, one input of the ALU must be a constant 1
//TODO: can A or B be swapped in synthesized RTL or is B always the 1?
const RTLIL::SigSpec b_port = sigmap(cell->getPort("\\B"));
if(!b_port.is_fully_const() || (b_port.as_int() != 1) )
return 4;
//BI and CI must be constant 1 as well
const RTLIL::SigSpec bi_port = sigmap(cell->getPort("\\BI"));
if(!bi_port.is_fully_const() || (bi_port.as_int() != 1) )
return 5;
const RTLIL::SigSpec ci_port = sigmap(cell->getPort("\\CI"));
if(!ci_port.is_fully_const() || (ci_port.as_int() != 1) )
return 6;
//CO and X must be unconnected (exactly one connection to each port)
if(!is_unconnected(sigmap(cell->getPort("\\CO")), index))
return 7;
if(!is_unconnected(sigmap(cell->getPort("\\X")), index))
return 8;
//Y must have exactly one connection, and it has to be a $mux cell.
//We must have a direct bus connection from our Y to their A.
const RTLIL::SigSpec aluy = sigmap(cell->getPort("\\Y"));
pool<Cell*> y_loads = get_other_cells(aluy, index, cell);
if(y_loads.size() != 1)
return 9;
Cell* count_mux = *y_loads.begin();
extract.count_mux = count_mux;
if(count_mux->type != "$mux")
return 10;
if(!is_full_bus(aluy, index, cell, "\\Y", count_mux, "\\A"))
return 11;
//B connection of the mux is our underflow value
const RTLIL::SigSpec underflow = sigmap(count_mux->getPort("\\B"));
if(!underflow.is_fully_const())
return 12;
extract.count_value = underflow.as_int();
//S connection of the mux must come from an inverter (need not be the only load)
const RTLIL::SigSpec muxsel = sigmap(count_mux->getPort("\\S"));
extract.outsig = muxsel;
pool<Cell*> muxsel_conns = get_other_cells(muxsel, index, count_mux);
Cell* underflow_inv = NULL;
for(auto c : muxsel_conns)
{
if(c->type != "$logic_not")
continue;
if(!is_full_bus(muxsel, index, c, "\\Y", count_mux, "\\S", true))
continue;
underflow_inv = c;
break;
}
if(underflow_inv == NULL)
return 13;
extract.underflow_inv = underflow_inv;
//Y connection of the mux must have exactly one load, the counter's internal register, if there's no clock enable
//If we have a clock enable, Y drives the B input of a mux. A of that mux must come from our register
const RTLIL::SigSpec muxy = sigmap(count_mux->getPort("\\Y"));
pool<Cell*> muxy_loads = get_other_cells(muxy, index, count_mux);
if(muxy_loads.size() != 1)
return 14;
Cell* muxload = *muxy_loads.begin();
Cell* count_reg = muxload;
Cell* cemux = NULL;
RTLIL::SigSpec cey;
if(muxload->type == "$mux")
{
//This mux is probably a clock enable mux.
//Find our count register (should be our only load)
cemux = muxload;
cey = sigmap(cemux->getPort("\\Y"));
pool<Cell*> cey_loads = get_other_cells(cey, index, cemux);
if(cey_loads.size() != 1)
return 24;
count_reg = *cey_loads.begin();
//Mux should have A driven by count Q, and B by muxy
//TODO: if A and B are swapped, CE polarity is inverted
if(sigmap(cemux->getPort("\\B")) != muxy)
return 24;
if(sigmap(cemux->getPort("\\A")) != sigmap(count_reg->getPort("\\Q")))
return 24;
if(sigmap(cemux->getPort("\\Y")) != sigmap(count_reg->getPort("\\D")))
return 24;
//Select of the mux is our clock enable
extract.has_ce = true;
extract.ce = sigmap(cemux->getPort("\\S"));
}
else
extract.has_ce = false;
extract.count_reg = count_reg;
if(count_reg->type == "$dff")
extract.has_reset = false;
else if(count_reg->type == "$adff")
{
extract.has_reset = true;
//Check polarity of reset - we may have to add an inverter later on!
extract.rst_inverted = (count_reg->getParam("\\ARST_POLARITY").as_int() != 1);
//Verify ARST_VALUE is zero or full scale
int rst_value = count_reg->getParam("\\ARST_VALUE").as_int();
if(rst_value == 0)
extract.rst_to_max = false;
else if(rst_value == extract.count_value)
extract.rst_to_max = true;
else
return 23;
//Save the reset
extract.rst = sigmap(count_reg->getPort("\\ARST"));
}
//TODO: support synchronous reset
else
return 15;
//Sanity check that we use the ALU output properly
if(extract.has_ce)
{
if(!is_full_bus(muxy, index, count_mux, "\\Y", cemux, "\\B"))
return 16;
if(!is_full_bus(cey, index, cemux, "\\Y", count_reg, "\\D"))
return 16;
}
else if(!is_full_bus(muxy, index, count_mux, "\\Y", count_reg, "\\D"))
return 16;
//TODO: Verify count_reg CLK_POLARITY is 1
//Register output must have exactly two loads, the inverter and ALU
//(unless we have a parallel output!)
//If we have a clock enable, 3 is OK
const RTLIL::SigSpec qport = count_reg->getPort("\\Q");
const RTLIL::SigSpec cnout = sigmap(qport);
pool<Cell*> cnout_loads = get_other_cells(cnout, index, count_reg);
unsigned int max_loads = 2;
if(extract.has_ce)
max_loads = 3;
if(cnout_loads.size() > max_loads)
{
for(auto c : cnout_loads)
{
if(c == underflow_inv)
continue;
if(c == cell)
continue;
if(c == muxload)
continue;
//If we specified a limited set of cells for parallel output, check that we only drive them
if(!parallel_cells.empty())
{
//Make sure we're in the whitelist
if( parallel_cells.find(c->type) == parallel_cells.end())
return 17;
}
//Figure out what port(s) are driven by it
//TODO: this can probably be done more efficiently w/o multiple iterations over our whole net?
for(auto b : qport)
{
pool<ModIndex::PortInfo> ports = index.query_ports(b);
for(auto x : ports)
{
if(x.cell != c)
continue;
extract.pouts.insert(ModIndex::PortInfo(c, x.port, 0));
}
}
}
}
if(!is_full_bus(cnout, index, count_reg, "\\Q", underflow_inv, "\\A", true))
return 18;
if(!is_full_bus(cnout, index, count_reg, "\\Q", cell, "\\A", true))
return 19;
//Look up the clock from the register
extract.clk = sigmap(count_reg->getPort("\\CLK"));
//Register output net must have an INIT attribute equal to the count value
extract.rwire = cnout.as_wire();
if(extract.rwire->attributes.find("\\init") == extract.rwire->attributes.end())
return 20;
int rinit = extract.rwire->attributes["\\init"].as_int();
if(rinit != extract.count_value)
return 21;
return 0;
}
void counter_worker(
ModIndex& index,
Cell *cell,
unsigned int& total_counters,
pool<Cell*>& cells_to_remove,
pool<pair<Cell*, string>>& cells_to_rename,
pool<RTLIL::IdString>& parallel_cells,
int maxwidth)
{
SigMap& sigmap = index.sigmap;
//Core of the counter must be an ALU
if (cell->type != "$alu")
return;
//A input is the count value. Check if it has COUNT_EXTRACT set.
//If it's not a wire, don't even try
auto port = sigmap(cell->getPort("\\A"));
if(!port.is_wire())
return;
RTLIL::Wire* a_wire = port.as_wire();
bool force_extract = false;
bool never_extract = false;
string count_reg_src = a_wire->attributes["\\src"].decode_string().c_str();
if(a_wire->attributes.find("\\COUNT_EXTRACT") != a_wire->attributes.end())
{
pool<string> sa = a_wire->get_strpool_attribute("\\COUNT_EXTRACT");
string extract_value;
if(sa.size() >= 1)
{
extract_value = *sa.begin();
log(" Signal %s declared at %s has COUNT_EXTRACT = %s\n",
log_id(a_wire),
count_reg_src.c_str(),
extract_value.c_str());
if(extract_value == "FORCE")
force_extract = true;
else if(extract_value == "NO")
never_extract = true;
else if(extract_value == "AUTO")
{} //default
else
log_error(" Illegal COUNT_EXTRACT value %s (must be one of FORCE, NO, AUTO)\n",
extract_value.c_str());
}
}
//If we're explicitly told not to extract, don't infer a counter
if(never_extract)
return;
//Attempt to extract a counter
CounterExtraction extract;
int reason = counter_tryextract(index, cell, extract, parallel_cells, maxwidth);
//Nonzero code - we could not find a matchable counter.
//Do nothing, unless extraction was forced in which case give an error
if(reason != 0)
{
static const char* reasons[25]=
{
"no problem", //0
"counter is too large/small", //1
"counter does not count by one", //2
"counter uses signed math", //3
"counter does not count by one", //4
"ALU is not a subtractor", //5
"ALU is not a subtractor", //6
"ALU ports used outside counter", //7
"ALU ports used outside counter", //8
"ALU output used outside counter", //9
"ALU output is not a mux", //10
"ALU output is not full bus", //11
"Underflow value is not constant", //12
"No underflow detector found", //13
"Mux output is used outside counter", //14
"Counter reg is not DFF/ADFF", //15
"Counter input is not full bus", //16
"Count register is used outside counter, but not by an allowed cell", //17
"Register output is not full bus", //18
"Register output is not full bus", //19
"No init value found", //20
"Underflow value is not equal to init value", //21
"RESERVED, not implemented", //22, kept for compatibility but not used anymore
"Reset is not to zero or COUNT_TO", //23
"Clock enable configuration is unsupported" //24
};
if(force_extract)
{
log_error(
"Counter extraction is set to FORCE on register %s, but a counter could not be inferred (%s)\n",
log_id(a_wire),
reasons[reason]);
}
return;
}
//Get new cell name
string countname = string("$COUNTx$") + log_id(extract.rwire->name.str());
//Wipe all of the old connections to the ALU
cell->unsetPort("\\A");
cell->unsetPort("\\B");
cell->unsetPort("\\BI");
cell->unsetPort("\\CI");
cell->unsetPort("\\CO");
cell->unsetPort("\\X");
cell->unsetPort("\\Y");
cell->unsetParam("\\A_SIGNED");
cell->unsetParam("\\A_WIDTH");
cell->unsetParam("\\B_SIGNED");
cell->unsetParam("\\B_WIDTH");
cell->unsetParam("\\Y_WIDTH");
//Change the cell type
cell->type = "$__COUNT_";
//Hook up resets
if(extract.has_reset)
{
//TODO: support other kinds of reset
cell->setParam("\\RESET_MODE", RTLIL::Const("LEVEL"));
//If the reset is active low, infer an inverter ($__COUNT_ cells always have active high reset)
if(extract.rst_inverted)
{
auto realreset = cell->module->addWire(NEW_ID);
cell->module->addNot(NEW_ID, extract.rst, RTLIL::SigSpec(realreset));
cell->setPort("\\RST", realreset);
}
else
cell->setPort("\\RST", extract.rst);
}
else
{
cell->setParam("\\RESET_MODE", RTLIL::Const("RISING"));
cell->setPort("\\RST", RTLIL::SigSpec(false));
}
//Hook up other stuff
//cell->setParam("\\CLKIN_DIVIDE", RTLIL::Const(1));
cell->setParam("\\COUNT_TO", RTLIL::Const(extract.count_value));
cell->setParam("\\WIDTH", RTLIL::Const(extract.width));
cell->setPort("\\CLK", extract.clk);
cell->setPort("\\OUT", extract.outsig);
//Hook up clock enable
if(extract.has_ce)
{
cell->setParam("\\HAS_CE", RTLIL::Const(1));
cell->setPort("\\CE", extract.ce);
}
else
cell->setParam("\\HAS_CE", RTLIL::Const(0));
//Hook up hard-wired ports (for now up/down are not supported), default to no parallel output
cell->setParam("\\HAS_POUT", RTLIL::Const(0));
cell->setParam("\\RESET_TO_MAX", RTLIL::Const(0));
cell->setParam("\\DIRECTION", RTLIL::Const("DOWN"));
cell->setPort("\\CE", RTLIL::Const(1));
cell->setPort("\\UP", RTLIL::Const(0));
//Hook up any parallel outputs
for(auto load : extract.pouts)
{
log(" Counter has parallel output to cell %s port %s\n", log_id(load.cell->name), log_id(load.port));
//Find the wire hooked to the old port
auto sig = load.cell->getPort(load.port);
//Connect it to our parallel output
//(this is OK to do more than once b/c they all go to the same place)
cell->setPort("\\POUT", sig);
cell->setParam("\\HAS_POUT", RTLIL::Const(1));
}
//Delete the cells we've replaced (let opt_clean handle deleting the now-redundant wires)
cells_to_remove.insert(extract.count_mux);
cells_to_remove.insert(extract.count_reg);
cells_to_remove.insert(extract.underflow_inv);
//Log it
total_counters ++;
string reset_type = "non-resettable";
if(extract.has_reset)
{
if(extract.rst_inverted)
reset_type = "negative";
else
reset_type = "positive";
//TODO: support other kind of reset
reset_type += " async resettable";
}
log(" Found %d-bit (%s) down counter %s (counting from %d) for register %s, declared at %s\n",
extract.width,
reset_type.c_str(),
countname.c_str(),
extract.count_value,
log_id(extract.rwire->name),
count_reg_src.c_str());
//Optimize the counter
//If we have no parallel output, and we have redundant bits, shrink us
if(extract.pouts.empty())
{
//TODO: Need to update this when we add support for counters with nonzero reset values
//to make sure the reset value fits in our bit space too
//Optimize it
int newbits = ceil(log2(extract.count_value));
if(extract.width != newbits)
{
cell->setParam("\\WIDTH", RTLIL::Const(newbits));
log(" Optimizing out %d unused high-order bits (new width is %d)\n",
extract.width - newbits,
newbits);
}
}
//Finally, rename the cell
cells_to_rename.insert(pair<Cell*, string>(cell, countname));
}
struct ExtractCounterPass : public Pass {
ExtractCounterPass() : Pass("extract_counter", "Extract GreenPak4 counter cells") { }
virtual void help()
{
// |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
log("\n");
log(" extract_counter [options] [selection]\n");
log("\n");
log("This pass converts non-resettable or async resettable down counters to\n");
log("counter cells. Use a target-specific 'techmap' map file to convert those cells\n");
log("to the actual target cells.\n");
log("\n");
log(" -maxwidth N\n");
log(" Only extract counters up to N bits wide\n");
log("\n");
log(" -pout X,Y,...\n");
log(" Only allow parallel output from the counter to the listed cell types\n");
log(" (if not specified, parallel outputs are not restricted)\n");
log("\n");
log("\n");
}
virtual void execute(std::vector<std::string> args, RTLIL::Design *design)
{
log_header(design, "Executing EXTRACT_COUNTER pass (find counters in netlist).\n");
int maxwidth = 64;
size_t argidx;
pool<RTLIL::IdString> parallel_cells;
for (argidx = 1; argidx < args.size(); argidx++)
{
if (args[argidx] == "-pout")
{
if(argidx + 1 >= args.size())
{
log_error("extract_counter -pout requires an argument\n");
return;
}
std::string pouts = args[++argidx];
std::string tmp;
for(size_t i=0; i<pouts.length(); i++)
{
if(pouts[i] == ',')
{
parallel_cells.insert(RTLIL::escape_id(tmp));
tmp = "";
}
else
tmp += pouts[i];
}
parallel_cells.insert(RTLIL::escape_id(tmp));
continue;
}
if (args[argidx] == "-maxwidth" && argidx+1 < args.size())
{
maxwidth = atoi(args[++argidx].c_str());
continue;
}
}
extra_args(args, argidx, design);
//Extract all of the counters we could find
unsigned int total_counters = 0;
for (auto module : design->selected_modules())
{
pool<Cell*> cells_to_remove;
pool<pair<Cell*, string>> cells_to_rename;
ModIndex index(module);
for (auto cell : module->selected_cells())
counter_worker(index, cell, total_counters, cells_to_remove, cells_to_rename, parallel_cells, maxwidth);
for(auto cell : cells_to_remove)
{
//log("Removing cell %s\n", log_id(cell->name));
module->remove(cell);
}
for(auto cpair : cells_to_rename)
{
//log("Renaming cell %s to %s\n", log_id(cpair.first->name), cpair.second.c_str());
module->rename(cpair.first, cpair.second);
}
}
if(total_counters)
log("Extracted %u counters\n", total_counters);
}
} ExtractCounterPass;
PRIVATE_NAMESPACE_END