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Initial working constant network support!

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Signed-off-by: Keith Rothman <537074+litghost@users.noreply.github.com>
This commit is contained in:
Keith Rothman 2021-02-18 16:51:36 -08:00
parent cf554f9338
commit 15459cae91
4 changed files with 145 additions and 14 deletions
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36
fpga_interchange/arch.h
View File

@ -67,7 +67,7 @@ NPNR_PACKED_STRUCT(struct BelInfoPOD {
int16_t site;
int16_t site_variant; // some sites have alternative types
int16_t category;
int16_t padding;
int16_t synthetic;
RelPtr<int32_t> pin_map; // Index into CellMapPOD::cell_bel_map
});
@ -128,7 +128,7 @@ NPNR_PACKED_STRUCT(struct TileTypeInfoPOD {
RelSlice<ConstraintTagPOD> tags;
RelSlice<int32_t> site_types;
RelSlice<int32_t> site_types; // constid
});
NPNR_PACKED_STRUCT(struct SiteInstInfoPOD {
@ -902,7 +902,7 @@ struct Arch : ArchAPI<ArchRanges>
auto &constants = chip_info->constants;
BelId bel;
bel.tile = constants->vcc_bel_tile;
bel.index = constants->vcc_bel_pin;
bel.index = constants->vcc_bel_index;
return bel;
}
@ -910,7 +910,7 @@ struct Arch : ArchAPI<ArchRanges>
auto &constants = chip_info->constants;
BelId bel;
bel.tile = constants->gnd_bel_tile;
bel.index = constants->gnd_bel_pin;
bel.index = constants->gnd_bel_index;
return bel;
}
@ -1682,6 +1682,34 @@ struct Arch : ArchAPI<ArchRanges>
auto &pip_data = pip_info(chip_info, pip);
return site_inst_info(chip_info, pip.tile, pip_data.site);
}
// Is this bel synthetic (e.g. added during import process)?
//
// This is generally used for constant networks, but can also be used for
// static partitions.
bool is_bel_synthetic(BelId bel) const
{
const BelInfoPOD & bel_data = bel_info(chip_info, bel);
return bel_data.synthetic != 0;
}
// Is this pip synthetic (e.g. added during import process)?
//
// This is generally used for constant networks, but can also be used for
// static partitions.
bool is_pip_synthetic(PipId pip) const
{
auto &pip_data = pip_info(chip_info, pip);
if(pip_data.site == -1) {
return pip_data.extra_data == -1;
} else {
BelId bel;
bel.tile = pip.tile;
bel.index = pip_data.bel;
return is_bel_synthetic(bel);
}
}
};
NEXTPNR_NAMESPACE_END

4
fpga_interchange/examples/const_wire/wire.v
View File

@ -1,6 +1,8 @@
module top(output o, output o2);
module top(output o, output o2, output o3, output o4);
assign o = 1'b0;
assign o2 = 1'b1;
assign o3 = 1'b0;
assign o4 = 1'b1;
endmodule

4
fpga_interchange/examples/const_wire/wire.xdc
View File

@ -1,5 +1,9 @@
set_property PACKAGE_PIN N15 [get_ports o]
set_property PACKAGE_PIN N16 [get_ports o2]
set_property PACKAGE_PIN P17 [get_ports o3]
set_property PACKAGE_PIN R17 [get_ports o4]
set_property IOSTANDARD LVCMOS33 [get_ports o]
set_property IOSTANDARD LVCMOS33 [get_ports o2]
set_property IOSTANDARD LVCMOS33 [get_ports o3]
set_property IOSTANDARD LVCMOS33 [get_ports o4]

115
fpga_interchange/fpga_interchange.cpp
View File

@ -62,6 +62,10 @@ static PhysicalNetlist::PhysNetlist::RouteBranch::Builder emit_branch(
const std::unordered_map<PipId, PlaceStrength> &pip_place_strength,
PipId pip,
PhysicalNetlist::PhysNetlist::RouteBranch::Builder branch) {
if(ctx->is_pip_synthetic(pip)) {
log_error("FPGA interchange should not emit synthetic pip %s\n", ctx->nameOfPip(pip));
}
const PipInfoPOD & pip_data = pip_info(ctx->chip_info, pip);
const TileTypeInfoPOD & tile_type = loc_info(ctx->chip_info, pip);
const TileInstInfoPOD & tile = ctx->chip_info->tiles[pip.tile];
@ -185,6 +189,11 @@ static void init_bel_pin(
StringEnumerator * strings,
const BelPin &bel_pin,
PhysicalNetlist::PhysNetlist::RouteBranch::Builder branch) {
if(ctx->is_bel_synthetic(bel_pin.bel)) {
log_error("FPGA interchange should not emit synthetic BEL pin %s/%s\n",
ctx->nameOfBel(bel_pin.bel), bel_pin.pin.c_str(ctx));
}
BelId bel = bel_pin.bel;
IdString pin_name = bel_pin.pin;
@ -248,6 +257,35 @@ static void emit_net(
}
}
}
static void find_non_synthetic_edges(const Context * ctx, WireId root_wire,
const std::unordered_map<WireId, std::vector<PipId>> &pip_downhill,
std::vector<PipId> *root_pips) {
std::vector<WireId> wires_to_expand;
wires_to_expand.push_back(root_wire);
while(!wires_to_expand.empty()) {
WireId wire = wires_to_expand.back();
wires_to_expand.pop_back();
auto downhill_iter = pip_downhill.find(wire);
if(downhill_iter == pip_downhill.end()) {
log_warning("Wire %s never entered the real fabric?\n",
ctx->nameOfWire(wire));
continue;
}
for(PipId pip : pip_downhill.at(wire)) {
if(!ctx->is_pip_synthetic(pip)) {
// Stop following edges that are non-synthetic, they will be
// followed during emit_net
root_pips->push_back(pip);
} else {
// Continue to follow synthetic edges.
wires_to_expand.push_back(ctx->getPipDstWire(pip));
}
}
}
}
void FpgaInterchange::write_physical_netlist(const Context * ctx, const std::string &filename) {
::capnp::MallocMessageBuilder message;
@ -272,9 +310,15 @@ void FpgaInterchange::write_physical_netlist(const Context * ctx, const std::str
size_t number_placements = 0;
for(auto & cell_name : placed_cells) {
const CellInfo & cell = *ctx->cells.at(cell_name);
if(!ctx->io_port_types.count(cell.type)) {
number_placements += 1;
if(ctx->io_port_types.count(cell.type)) {
continue;
}
if(ctx->is_bel_synthetic(cell.bel)) {
continue;
}
number_placements += 1;
}
std::unordered_map<std::string, std::string> sites;
@ -286,6 +330,9 @@ void FpgaInterchange::write_physical_netlist(const Context * ctx, const std::str
if(ctx->io_port_types.count(cell.type)) {
continue;
}
if(ctx->is_bel_synthetic(cell.bel)) {
continue;
}
IdStringList bel_name = ctx->getBelName(cell.bel);
NPNR_ASSERT(bel_name.size() == 2);
@ -339,16 +386,27 @@ void FpgaInterchange::write_physical_netlist(const Context * ctx, const std::str
auto &net = *net_pair.second;
auto net_out = *net_iter++;
net_out.setName(strings.get_index(net.name.str(ctx)));
const CellInfo *driver_cell = net.driver.cell;
// FIXME: Mark net as signal/vcc/gnd.
//
// Also vcc/gnd nets needs to get special handling through inverters.
// Handle GND and VCC nets.
if(driver_cell->bel == ctx->get_gnd_bel()) {
IdString gnd_net_name(ctx->chip_info->constants->gnd_net_name);
net_out.setName(strings.get_index(gnd_net_name.str(ctx)));
net_out.setType(PhysicalNetlist::PhysNetlist::NetType::GND);
} else if(driver_cell->bel == ctx->get_vcc_bel()) {
IdString vcc_net_name(ctx->chip_info->constants->vcc_net_name);
net_out.setName(strings.get_index(vcc_net_name.str(ctx)));
net_out.setType(PhysicalNetlist::PhysNetlist::NetType::VCC);
} else {
net_out.setName(strings.get_index(net.name.str(ctx)));
}
// FIXME: Also vcc/gnd nets needs to get special handling through
// inverters.
std::unordered_map<WireId, BelPin> root_wires;
std::unordered_map<WireId, std::vector<PipId>> pip_downhill;
std::unordered_set<PipId> pips;
const CellInfo *driver_cell = net.driver.cell;
if (driver_cell != nullptr && driver_cell->bel != BelId()) {
for(IdString bel_pin_name : driver_cell->cell_bel_pins.at(net.driver.port)) {
BelPin driver_bel_pin;
@ -397,7 +455,27 @@ void FpgaInterchange::write_physical_netlist(const Context * ctx, const std::str
}
}
auto sources = net_out.initSources(root_wires.size());
std::vector<PipId> root_pips;
std::vector<WireId> roots_to_remove;
for(const auto & root_pair : root_wires) {
WireId root_wire = root_pair.first;
BelPin src_bel_pin = root_pair.second;
if(!ctx->is_bel_synthetic(src_bel_pin.bel)) {
continue;
}
roots_to_remove.push_back(root_wire);
find_non_synthetic_edges(ctx, root_wire, pip_downhill, &root_pips);
}
// Remove wires that have a synthetic root.
for(WireId wire : roots_to_remove) {
NPNR_ASSERT(root_wires.erase(wire) == 1);
}
auto sources = net_out.initSources(root_wires.size() + root_pips.size());
auto source_iter = sources.begin();
for(const auto & root_pair : root_wires) {
@ -410,11 +488,30 @@ void FpgaInterchange::write_physical_netlist(const Context * ctx, const std::str
emit_net(ctx, &strings, pip_downhill, sinks, &pips, pip_place_strength, root_wire, source_branch);
}
for(const PipId root : root_pips) {
PhysicalNetlist::PhysNetlist::RouteBranch::Builder source_branch = *source_iter++;
NPNR_ASSERT(pips.erase(root) == 1);
WireId root_wire = ctx->getPipDstWire(root);
source_branch = emit_branch(ctx, &strings, pip_place_strength, root, source_branch);
emit_net(ctx, &strings, pip_downhill, sinks, &pips, pip_place_strength, root_wire, source_branch);
}
// Any pips that were not part of a tree starting from the source are
// stubs.
auto stubs = net_out.initStubs(pips.size());
size_t real_pips = 0;
for(PipId pip : pips) {
if(ctx->is_pip_synthetic(pip)) {
continue;
}
real_pips += 1;
}
auto stubs = net_out.initStubs(real_pips);
auto stub_iter = stubs.begin();
for(PipId pip : pips) {
if(ctx->is_pip_synthetic(pip)) {
continue;
}
emit_branch(ctx, &strings, pip_place_strength, pip, *stub_iter++);
}
}