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kmurraykmurray
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Support splitting clock signals used as data into separate signals
The packer in particular complains about this type of connectivity, so we fix it during BLIF netlist clean-up.
1 parent 827d8a0 commit 6ccf516

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7 files changed

+236
-24
lines changed

7 files changed

+236
-24
lines changed

‎vpr/SRC/base/atom_netlist.c

Lines changed: 26 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -424,12 +424,17 @@ AtomPortId AtomNetlist::pin_port (const AtomPinId id) const {
424424
return pin_ports_[id];
425425
}
426426

427-
BitIndex AtomNetlist::pin_port_bit(const AtomPinId id) const {
427+
BitIndex AtomNetlist::pin_port_bit (const AtomPinId id) const {
428428
VTR_ASSERT(valid_pin_id(id));
429429

430430
return pin_port_bits_[id];
431431
}
432432

433+
AtomPortType AtomNetlist::pin_port_type (const AtomPinId id) const {
434+
AtomPortId port = pin_port(id);
435+
return port_type(port);
436+
}
437+
433438
AtomBlockId AtomNetlist::pin_block (const AtomPinId id) const {
434439
//Convenience lookup bypassing the port
435440
VTR_ASSERT(valid_pin_id(id));
@@ -944,6 +949,24 @@ void AtomNetlist::set_pin_is_constant(const AtomPinId pin_id, const bool value)
944949
pin_is_constant_[pin_id] = value;
945950
}
946951

952+
void AtomNetlist::set_pin_net (const AtomPinId pin, AtomPinType pin_type, const AtomNetId net) {
953+
VTR_ASSERT(valid_pin_id(pin));
954+
VTR_ASSERT( (pin_type == AtomPinType::DRIVER && pin_port_type(pin) == AtomPortType::OUTPUT)
955+
|| (pin_type == AtomPinType::SINK && (pin_port_type(pin) == AtomPortType::INPUT || pin_port_type(pin) == AtomPortType::CLOCK)));
956+
957+
AtomNetId orig_net = pin_net(pin);
958+
if(orig_net) {
959+
//Clean up the pin reference on the original net
960+
remove_net_pin(orig_net, pin);
961+
}
962+
963+
//Mark the pin's net
964+
pin_nets_[pin] = net;
965+
966+
//Add the pin to the net
967+
associate_pin_with_net(pin, pin_type, net);
968+
}
969+
947970
void AtomNetlist::remove_block(const AtomBlockId blk_id) {
948971
VTR_ASSERT(valid_block_id(blk_id));
949972

@@ -1763,8 +1786,8 @@ AtomNetlist::AtomStringId AtomNetlist::create_string (const std::string& str) {
17631786
void AtomNetlist::associate_pin_with_net(const AtomPinId pin_id, const AtomPinType type, const AtomNetId net_id) {
17641787
//Add the pin to the net
17651788
if(type == AtomPinType::DRIVER) {
1766-
VTR_ASSERT_MSG(net_pins_[net_id].size() > 0, "Space for net's pin");
1767-
VTR_ASSERT_MSG(net_pins_[net_id][0] == AtomPinId::INVALID(), "No existing net driver");
1789+
VTR_ASSERT_MSG(net_pins_[net_id].size() > 0, "Must be space for net's pin");
1790+
VTR_ASSERT_MSG(net_pins_[net_id][0] == AtomPinId::INVALID(), "Must be no existing net driver");
17681791

17691792
net_pins_[net_id][0] = pin_id; //Set driver
17701793
} else {

‎vpr/SRC/base/atom_netlist.h

Lines changed: 17 additions & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -520,25 +520,28 @@ class AtomNetlist {
520520
* Pins
521521
*/
522522
//Returns the constructed name (derived from block and port) for the specified pin
523-
std::string pin_name (const AtomPinId id) const;
523+
std::string pin_name (const AtomPinId id) const;
524524

525525
//Returns the net associated with the specified pin
526-
AtomNetId pin_net (const AtomPinId id) const;
526+
AtomNetId pin_net (const AtomPinId id) const;
527527

528528
//Returns the pin type of the specified pin
529-
AtomPinType pin_type (const AtomPinId id) const;
529+
AtomPinType pin_type (const AtomPinId id) const;
530530

531531
//Returns the port associated with the specified pin
532-
AtomPortId pin_port (const AtomPinId id) const;
532+
AtomPortId pin_port (const AtomPinId id) const;
533533

534534
//Returns the port bit index associated with the specified pin
535-
BitIndex pin_port_bit (const AtomPinId id) const;
535+
BitIndex pin_port_bit (const AtomPinId id) const;
536+
537+
//Returns the port type associated with the specified pin
538+
AtomPortType pin_port_type (const AtomPinId id) const;
536539

537540
//Returns the block associated with the specified pin
538-
AtomBlockId pin_block (const AtomPinId id) const;
541+
AtomBlockId pin_block (const AtomPinId id) const;
539542

540543
//Returns true if the pin is a constant (i.e. its value never changes)
541-
bool pin_is_constant (const AtomPinId id) const;
544+
bool pin_is_constant (const AtomPinId id) const;
542545

543546
/*
544547
* Nets
@@ -658,6 +661,13 @@ class AtomNetlist {
658661
// value : The boolean value to set the pin_is_constant attribute
659662
void set_pin_is_constant(const AtomPinId pin_id, const bool value);
660663

664+
//Add the specified pin to the specified net as pin_type. Automatically removes
665+
//any previous net connection for this pin.
666+
// pin : The pin to add
667+
// pin_type : The type of the pin (i.e. driver or sink)
668+
// net : The net to add the pin to
669+
void set_pin_net(const AtomPinId pin, AtomPinType pin_type, const AtomNetId net);
670+
661671
/*
662672
* Note: all remove_*() will mark the associated items as invalid, but the items
663673
* will not be removed until compress() is called.

‎vpr/SRC/base/atom_netlist_utils.c

Lines changed: 136 additions & 13 deletions
Original file line numberDiff line numberDiff line change
@@ -10,6 +10,15 @@
1010
#include "vtr_log.h"
1111

1212
#include "vpr_error.h"
13+
#include "vpr_utils.h"
14+
15+
std::map<AtomNetId,std::vector<AtomPinId>> find_clock_used_as_data_pins(const AtomNetlist& netlist);
16+
17+
AtomBlockId fix_clock_to_data_pins(AtomNetlist& netlist,
18+
const AtomNetId clock_net, const std::vector<AtomPinId>& data_pins,
19+
const t_model* blk_model,
20+
const t_model_ports* model_clock_port, const BitIndex clock_port_bit,
21+
const t_model_ports* model_data_port, const BitIndex data_port_bit);
1322

1423
std::vector<AtomBlockId> identify_buffer_luts(const AtomNetlist& netlist);
1524
bool is_buffer_lut(const AtomNetlist& netlist, const AtomBlockId blk);
@@ -123,9 +132,6 @@ void print_netlist_as_blif(FILE* f, const AtomNetlist& netlist) {
123132
auto input_ports = netlist.block_input_ports(blk_id);
124133
auto output_ports = netlist.block_output_ports(blk_id);
125134
auto clock_ports = netlist.block_clock_ports(blk_id);
126-
VTR_ASSERT(input_ports.size() == 1);
127-
VTR_ASSERT(output_ports.size() == 1);
128-
VTR_ASSERT(clock_ports.size() == 1);
129135

130136
for(auto ports : {input_ports, output_ports, clock_ports}) {
131137
for(AtomPortId port_id : ports) {
@@ -149,21 +155,35 @@ void print_netlist_as_blif(FILE* f, const AtomNetlist& netlist) {
149155
}
150156
}
151157

158+
if(d_net.empty()) {
159+
d_net = make_unconn(unconn_count, AtomPinType::SINK);
160+
}
161+
162+
if(q_net.empty()) {
163+
q_net = make_unconn(unconn_count, AtomPinType::DRIVER);
164+
}
165+
166+
if(clk_net.empty()) {
167+
clk_net = make_unconn(unconn_count, AtomPinType::SINK);
168+
}
169+
152170
//Latch type: VPR always assumes rising edge
153171
auto type = "re";
154172

155173
//Latch initial value
156174
int init_val = 3; //Unkown or unspecified
157175
//The initial value is stored as a single value in the truth table
158176
const auto& so_cover = netlist.block_truth_table(blk_id);
159-
VTR_ASSERT(so_cover.size() == 1); //Only one row
160-
VTR_ASSERT(so_cover[0].size() == 1); //Only one column
161-
switch(so_cover[0][0]) {
162-
case vtr::LogicValue::TRUE: init_val = 1; break;
163-
case vtr::LogicValue::FALSE: init_val = 0; break;
164-
case vtr::LogicValue::DONT_CARE: init_val = 2; break;
165-
case vtr::LogicValue::UNKOWN: init_val = 3; break;
166-
default: VTR_ASSERT_MSG(false, "Unrecognzied latch initial state");
177+
if(so_cover.size() == 1) {
178+
VTR_ASSERT(so_cover.size() == 1); //Only one row
179+
VTR_ASSERT(so_cover[0].size() == 1); //Only one column
180+
switch(so_cover[0][0]) {
181+
case vtr::LogicValue::TRUE: init_val = 1; break;
182+
case vtr::LogicValue::FALSE: init_val = 0; break;
183+
case vtr::LogicValue::DONT_CARE: init_val = 2; break;
184+
case vtr::LogicValue::UNKOWN: init_val = 3; break;
185+
default: VTR_ASSERT_MSG(false, "Unrecognzied latch initial state");
186+
}
167187
}
168188

169189
fprintf(f, ".latch %s %s %s %s %d\n", d_net.c_str(), q_net.c_str(), type, clk_net.c_str(), init_val);
@@ -557,6 +577,102 @@ void remove_buffer_lut(AtomNetlist& netlist, AtomBlockId blk) {
557577

558578
}
559579

580+
void fix_clock_to_data_conversions(AtomNetlist& netlist, const t_model* library_models) {
581+
//Some netlists contain clock signals that are also used as data inputs
582+
//
583+
//This function removes these cases by creating a new net whose sinks are the
584+
//'data' sinks of the clock net. This net is then driven by a latch with no
585+
//input data signal, but clocked by the original clock
586+
587+
auto clock_data_pins = find_clock_used_as_data_pins(netlist);
588+
589+
//Use the latch D port to generate the data version fo the clock
590+
const t_model* model = find_model(library_models, "latch");
591+
VTR_ASSERT(model);
592+
const t_model_ports* clock_port = find_model_port(model, "clk");
593+
VTR_ASSERT(clock_port);
594+
BitIndex clock_port_bit = 0;
595+
596+
const t_model_ports* data_port = find_model_port(model, "Q");
597+
VTR_ASSERT(data_port);
598+
BitIndex data_port_bit = 0;
599+
600+
for(auto kv : clock_data_pins) {
601+
AtomNetId clock_net = kv.first;
602+
const std::vector<AtomPinId>& data_pins = kv.second;
603+
604+
vtr::printf_warning(__FILE__, __LINE__, "Clock '%s' drives both clock and data pins, splitting it into separate clock and data nets\n",
605+
netlist.net_name(clock_net).c_str());
606+
607+
fix_clock_to_data_pins(netlist,
608+
clock_net, data_pins,
609+
model,
610+
clock_port, clock_port_bit,
611+
data_port, data_port_bit);
612+
}
613+
}
614+
615+
//Finds all clock sinks which are data ports in the netlist.
616+
//Returns a map of clock_net to the clock's data_sinks
617+
std::map<AtomNetId,std::vector<AtomPinId>> find_clock_used_as_data_pins(const AtomNetlist& netlist) {
618+
std::map<AtomNetId,std::vector<AtomPinId>> clock_data_pins;
619+
620+
auto netlist_clocks = find_netlist_clocks(netlist);
621+
622+
623+
for(AtomNetId clock_net : netlist_clocks) {
624+
for(AtomPinId clock_sink : netlist.net_sinks(clock_net)) {
625+
626+
auto port_type = netlist.pin_port_type(clock_sink);
627+
628+
if(port_type != AtomPortType::CLOCK) {
629+
630+
clock_data_pins[clock_net].push_back(clock_sink);
631+
}
632+
}
633+
}
634+
635+
return clock_data_pins;
636+
}
637+
638+
AtomBlockId fix_clock_to_data_pins(AtomNetlist& netlist,
639+
const AtomNetId clock_net, const std::vector<AtomPinId>& data_pins,
640+
const t_model* blk_model,
641+
const t_model_ports* model_clock_port, const BitIndex clock_port_bit,
642+
const t_model_ports* model_data_port, const BitIndex data_port_bit) {
643+
//Create a new block clocked by clock_net which will drive the 'data' version of the clock
644+
645+
std::string blk_name = "__vpr__" + netlist.net_name(clock_net) + "__as_data__";
646+
VTR_ASSERT_MSG(!netlist.find_block(blk_name), "Failed to create unique clock as data source block name");
647+
648+
//Make the block
649+
AtomBlockId blk = netlist.create_block(blk_name, blk_model);
650+
VTR_ASSERT(blk);
651+
652+
//Connect the clock
653+
AtomPortId clock_port = netlist.create_port(blk, model_clock_port);
654+
netlist.create_pin(clock_port, clock_port_bit, clock_net, AtomPinType::SINK);
655+
656+
//Make the data port
657+
AtomPortId data_port = netlist.create_port(blk, model_data_port);
658+
659+
//Make the net
660+
VTR_ASSERT_MSG(!netlist.find_net(blk_name), "Failed to create unique clock as data net name");
661+
AtomNetId clock_data_net = netlist.create_net(blk_name);
662+
VTR_ASSERT(clock_data_net);
663+
664+
//Create the driver pin
665+
netlist.create_pin(data_port, data_port_bit, clock_data_net, AtomPinType::DRIVER);
666+
667+
//Update all the data pins to connect to clock_data_net instead of the original clock net
668+
for(AtomPinId sink_pin : data_pins) {
669+
670+
netlist.set_pin_net(sink_pin, AtomPinType::SINK, clock_data_net);
671+
}
672+
673+
return blk;
674+
}
675+
560676
bool is_removable_block(const AtomNetlist& netlist, const AtomBlockId blk_id) {
561677
//Any block with no fanout is removable
562678
for(AtomPinId pin_id : netlist.block_output_pins(blk_id)) {
@@ -797,7 +913,7 @@ std::string make_unconn(size_t& unconn_count, AtomPinType /*pin_type*/) {
797913
return std::string("unconn");
798914
}
799915
#else
800-
return std::string("unconn") + std::to_string(unconn_count++);
916+
return std::string("__vpr__unconn") + std::to_string(unconn_count++);
801917
#endif
802918
}
803919

@@ -963,6 +1079,8 @@ std::set<AtomNetId> find_netlist_clocks(const AtomNetlist& netlist) {
9631079
//
9641080
//Since we don't have good information about what pins are clock generators we build a lookup as we go
9651081
for(auto blk_id : netlist.blocks()) {
1082+
if(!blk_id) continue;
1083+
9661084
AtomBlockType type = netlist.block_type(blk_id);
9671085
if(type != AtomBlockType::BLOCK) continue;
9681086

@@ -986,6 +1104,8 @@ std::set<AtomNetId> find_netlist_clocks(const AtomNetlist& netlist) {
9861104

9871105
//Look for connected input clocks
9881106
for(auto pin_id : netlist.block_clock_pins(blk_id)) {
1107+
if(!pin_id) continue;
1108+
9891109
AtomNetId clk_net_id = netlist.pin_net(pin_id);
9901110
VTR_ASSERT(clk_net_id);
9911111

@@ -1001,8 +1121,11 @@ std::set<AtomNetId> find_netlist_clocks(const AtomNetlist& netlist) {
10011121
AtomPortId clk_gen_port = netlist.find_port(blk_id, model_port);
10021122

10031123
for(AtomPinId pin_id : netlist.port_pins(clk_gen_port)) {
1124+
if(!pin_id) continue;
1125+
10041126
AtomNetId clk_net_id = netlist.pin_net(pin_id);
1005-
VTR_ASSERT(clk_net_id);
1127+
if(!clk_net_id) continue;
1128+
10061129
clock_nets.insert(clk_net_id);
10071130
}
10081131
}

‎vpr/SRC/base/atom_netlist_utils.h

Lines changed: 6 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -15,6 +15,12 @@
1515
*/
1616
void absorb_buffer_luts(AtomNetlist& netlist);
1717

18+
/*
19+
* Modifies the netlist to fix cases where a clock is used as data,
20+
* by replacing the data portion of the net with the specified model/port/bit driver
21+
*/
22+
void fix_clock_to_data_conversions(AtomNetlist& netlist, const t_model* library_models);
23+
1824
/*
1925
* Modify the netlist by sweeping away unused nets/blocks/inputs
2026
*/

‎vpr/SRC/base/read_blif.c

Lines changed: 13 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -46,6 +46,7 @@ static AtomNetlist read_blif(const char *blif_file,
4646
const t_model *library_models);
4747

4848
static void process_blif(AtomNetlist& netlist,
49+
const t_model *library_models,
4950
bool should_absorb_buffers,
5051
bool should_sweep_dangling_primary_ios,
5152
bool should_sweep_dangling_nets,
@@ -664,6 +665,7 @@ AtomNetlist read_and_process_blif(const char *blif_file,
664665
print_netlist_as_blif("atom_netlist.orig.echo.blif", netlist);
665666

666667
process_blif(netlist,
668+
library_models,
667669
should_absorb_buffers,
668670
should_sweep_dangling_primary_ios,
669671
should_sweep_dangling_nets,
@@ -679,6 +681,7 @@ AtomNetlist read_and_process_blif(const char *blif_file,
679681
}
680682

681683
static void process_blif(AtomNetlist& netlist,
684+
const t_model *library_models,
682685
bool should_absorb_buffers,
683686
bool should_sweep_dangling_primary_ios,
684687
bool should_sweep_dangling_nets,
@@ -712,6 +715,16 @@ static void process_blif(AtomNetlist& netlist,
712715
should_sweep_dangling_nets,
713716
should_sweep_dangling_blocks,
714717
should_sweep_constant_primary_outputs);
718+
719+
//Fix-up cases where a clock is used as a data input
720+
// Currently such connections break the clusterer, so
721+
// we take care of them here. Note that this modification
722+
// likely causes the netlist to no longer be logically equivalent
723+
// to the input
724+
bool should_fix_clock_to_data_conversions = true; //TODO make cmd line option
725+
if(should_fix_clock_to_data_conversions) {
726+
fix_clock_to_data_conversions(netlist, library_models);
727+
}
715728
}
716729

717730
{

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