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This commit is contained in:
Miodrag Milanovic 2018-06-25 16:22:08 +02:00
commit a279720fc1
4 changed files with 195 additions and 51 deletions
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4
common/nextpnr.h
View File

@ -210,10 +210,10 @@ struct BaseCtx
~BaseCtx()
{
for(auto &item : nets) {
for (auto &item : nets) {
delete item.second;
}
for(auto &item : cells) {
for (auto &item : cells) {
delete item.second;
}
delete idstring_str_to_idx;

2
ice40/cells.cc
View File

@ -47,6 +47,8 @@ CellInfo *create_ice_cell(Context *ctx, IdString type, std::string name)
new_cell->params[ctx->id("DFF_ENABLE")] = "0";
new_cell->params[ctx->id("SET_NORESET")] = "0";
new_cell->params[ctx->id("ASYNC_SR")] = "0";
new_cell->params[ctx->id("CIN_CONST")] = "0";
new_cell->params[ctx->id("CIN_SET")] = "0";
add_port(ctx, new_cell, "I0", PORT_IN);
add_port(ctx, new_cell, "I1", PORT_IN);

11
ice40/pack.cc
View File

@ -258,7 +258,7 @@ static void pack_constants(Context *ctx)
std::vector<IdString> dead_nets;
bool gnd_used = false, vcc_used = false;
bool gnd_used = false;
for (auto net : sorted(ctx->nets)) {
NetInfo *ni = net.second;
@ -268,7 +268,6 @@ static void pack_constants(Context *ctx)
dead_nets.push_back(net.first);
} else if (ni->driver.cell != nullptr && ni->driver.cell->type == ctx->id("VCC")) {
set_net_constant(ctx, ni, vcc_net, true);
vcc_used = true;
dead_nets.push_back(net.first);
}
}
@ -280,14 +279,10 @@ static void pack_constants(Context *ctx)
delete gnd_net;
delete gnd_cell;
}
if (vcc_used) {
// Vcc cell always inserted for now, as it may be needed during carry legalisation (TODO: trim later if actually
// never used?)
ctx->cells[vcc_cell->name] = vcc_cell;
ctx->nets[vcc_net->name] = vcc_net;
} else {
delete vcc_net;
delete vcc_cell;
}
for (auto dn : dead_nets)
ctx->nets.erase(dn);

189
ice40/place_legaliser.cc
View File

@ -27,13 +27,18 @@
NEXTPNR_NAMESPACE_BEGIN
struct CellChain
{
std::vector<CellInfo *> cells;
};
// Generic chain finder
template <typename F1, typename F2, typename F3>
std::vector<std::vector<CellInfo *>> find_chains(const Context *ctx, F1 cell_type_predicate, F2 get_previous,
F3 get_next, size_t min_length = 2)
std::vector<CellChain> find_chains(const Context *ctx, F1 cell_type_predicate, F2 get_previous, F3 get_next,
size_t min_length = 2)
{
std::set<IdString> chained;
std::vector<std::vector<CellInfo *>> chains;
std::vector<CellChain> chains;
for (auto cell : sorted(ctx->cells)) {
if (chained.find(cell.first) != chained.end())
continue;
@ -45,15 +50,15 @@ std::vector<std::vector<CellInfo *>> find_chains(const Context *ctx, F1 cell_typ
start = prev_start;
prev_start = get_previous(ctx, start);
}
std::vector<CellInfo *> chain;
CellChain chain;
CellInfo *end = start;
while (end != nullptr) {
chain.push_back(end);
chain.cells.push_back(end);
end = get_next(ctx, end);
}
if (chain.size() >= min_length) {
if (chain.cells.size() >= min_length) {
chains.push_back(chain);
for (auto c : chain)
for (auto c : chain.cells)
chained.insert(c->name);
}
}
@ -61,10 +66,11 @@ std::vector<std::vector<CellInfo *>> find_chains(const Context *ctx, F1 cell_typ
return chains;
}
static void get_chain_midpoint(const Context *ctx, const std::vector<CellInfo *> &chain, float &x, float &y) {
static void get_chain_midpoint(const Context *ctx, const CellChain &chain, float &x, float &y)
{
float total_x = 0, total_y = 0;
int N = 0;
for (auto cell : chain) {
for (auto cell : chain.cells) {
if (cell->bel == BelId())
continue;
int bel_x, bel_y;
@ -79,10 +85,123 @@ static void get_chain_midpoint(const Context *ctx, const std::vector<CellInfo *>
y = total_y / N;
}
static CellInfo *make_carry_pass_out(Context *ctx, PortInfo &cout_port) {
class PlacementLegaliser
{
public:
PlacementLegaliser(Context *ctx) : ctx(ctx){};
bool legalise()
{
bool legalised_carries = legalise_carries();
if (!legalised_carries && !ctx->force)
return false;
return legalised_carries;
}
private:
void init_logic_cells()
{
for (auto bel : ctx->getBels()) {
// Initialise the logic bels vector with unavailable invalid bels, dimensions [0..width][0..height[0..7]
logic_bels.resize(ctx->chip_info->width + 1,
std::vector<std::vector<std::pair<BelId, bool>>>(
ctx->chip_info->height + 1,
std::vector<std::pair<BelId, bool>>(8, std::make_pair(BelId(), true))));
if (ctx->getBelType(bel) == TYPE_ICESTORM_LC) {
// Using the non-standard API here to get (x, y, z) rather than just (x, y)
auto bi = ctx->chip_info->bel_data[bel.index];
int x = bi.x, y = bi.y, z = bi.z;
IdString cell = ctx->getBoundBelCell(bel);
if (cell != IdString() && ctx->cells.at(cell)->belStrength >= STRENGTH_FIXED)
logic_bels.at(x).at(y).at(z) = std::make_pair(bel, true);
else
logic_bels.at(x).at(y).at(z) = std::make_pair(bel, false);
}
}
}
bool legalise_carries()
{
std::vector<CellChain> carry_chains = find_chains(
ctx, is_lc,
[](const Context *ctx, const CellInfo *cell) {
return net_driven_by(ctx, cell->ports.at(ctx->id("CIN")).net, is_lc, ctx->id("COUT"));
},
[](const Context *ctx, const CellInfo *cell) {
return net_only_drives(ctx, cell->ports.at(ctx->id("COUT")).net, is_lc, ctx->id("CIN"), false);
});
int width = ctx->chip_info->width, height = ctx->chip_info->height;
for (auto &base_chain : carry_chains) {
std::vector<CellChain> split_chains = split_carry_chain(base_chain);
for (auto &chain : split_chains) {
float mid_x, mid_y;
get_chain_midpoint(ctx, chain, mid_x, mid_y);
float base_x = mid_x, base_y = mid_y - (chain.cells.size() / 16.0f);
// Find Bel meeting requirements closest to the target base
}
}
return true;
}
// Find Bel closest to a location, meeting chain requirements
BelId find_closest_bel(float x, float y, int chain_size)
{
// TODO
return BelId();
}
// Split a carry chain into multiple legal chains
std::vector<CellChain> split_carry_chain(CellChain &carryc)
{
bool start_of_chain = true;
std::vector<CellChain> chains;
std::vector<const CellInfo *> tile;
const int max_length = (ctx->chip_info->height - 2) * 8 - 2;
auto curr_cell = carryc.cells.begin();
while (curr_cell != carryc.cells.end()) {
CellInfo *cell = *curr_cell;
if (tile.size() >= 8) {
tile.clear();
}
if (start_of_chain) {
tile.clear();
chains.emplace_back();
start_of_chain = false;
if (cell->ports.at(ctx->id("CIN")).net) {
// CIN is not constant and not part of a chain. Must feed in from fabric
CellInfo *feedin = make_carry_feed_in(cell, cell->ports.at(ctx->id("CIN")));
chains.back().cells.push_back(feedin);
tile.push_back(feedin);
}
}
tile.push_back(cell);
chains.back().cells.push_back(cell);
bool split_chain = (!ctx->logicCellsCompatible(tile)) || (int(chains.back().cells.size()) > max_length);
if (split_chain) {
CellInfo *passout = make_carry_pass_out(cell->ports.at(ctx->id("COUT")));
tile.pop_back();
chains.back().cells.back() = passout;
start_of_chain = true;
} else {
NetInfo *carry_net = cell->ports.at(ctx->id("COUT")).net;
if (carry_net != nullptr && carry_net->users.size() > 1) {
CellInfo *passout = make_carry_pass_out(cell->ports.at(ctx->id("COUT")));
chains.back().cells.push_back(passout);
tile.push_back(passout);
}
++curr_cell;
}
}
return chains;
}
// Insert a logic cell to legalise a COUT->fabric connection
CellInfo *make_carry_pass_out(PortInfo &cout_port)
{
assert(cout_port.net != nullptr);
CellInfo *lc = create_ice_cell(ctx, ctx->id("ICESTORM_LC"));
lc->params[ctx->id("LUT_INIT")] = "65280"; // 0xff00: O = I3
lc->params[ctx->id("CARRY_ENABLE")] = "1";
lc->ports.at(ctx->id("O")).net = cout_port.net;
NetInfo *co_i3_net = new NetInfo();
co_i3_net->name = ctx->id(lc->name.str(ctx) + "$I3");
@ -96,21 +215,49 @@ static CellInfo *make_carry_pass_out(Context *ctx, PortInfo &cout_port) {
o_r.cell = lc;
cout_port.net->driver = o_r;
lc->ports.at(ctx->id("I3")).net = co_i3_net;
// I1=1 feeds carry up the chain, so no need to actually break the chain
lc->ports.at(ctx->id("I1")).net = ctx->nets.at(ctx->id("$PACKER_VCC_NET"));
PortRef i1_r;
i1_r.port = ctx->id("I1");
i1_r.cell = lc;
ctx->nets.at(ctx->id("$PACKER_VCC_NET"))->users.push_back(i1_r);
ctx->cells[lc->name] = lc;
createdCells.insert(lc->name);
return lc;
}
}
// Insert a logic cell to legalise a CIN->fabric connection
CellInfo *make_carry_feed_in(CellInfo *cin_cell, PortInfo &cin_port)
{
assert(cin_port.net != nullptr);
CellInfo *lc = create_ice_cell(ctx, ctx->id("ICESTORM_LC"));
lc->params[ctx->id("CARRY_ENABLE")] = "1";
lc->params[ctx->id("CIN_CONST")] = "1";
lc->params[ctx->id("CIN_SET")] = "1";
lc->ports.at(ctx->id("I1")).net = cin_port.net;
cin_port.net->users.erase(std::remove_if(cin_port.net->users.begin(), cin_port.net->users.end(),
[cin_cell, cin_port](const PortRef &usr) {
return usr.cell == cin_cell && usr.port == cin_port.name;
}));
NetInfo *out_net = new NetInfo();
out_net->name = ctx->id(lc->name.str(ctx) + "$O");
ctx->cells[lc->name] = lc;
createdCells.insert(lc->name);
return lc;
}
Context *ctx;
std::unordered_set<IdString> rippedCells;
std::unordered_set<IdString> createdCells;
// Go from X and Y position to logic cells, setting occupied to true if a Bel is unavailable
std::vector<std::vector<std::vector<std::pair<BelId, bool>>>> logic_bels;
};
bool legalise_design(Context *ctx)
{
std::vector<std::vector<CellInfo *>> carry_chains = find_chains(
ctx, is_lc,
[](const Context *ctx, const CellInfo *cell) {
return net_driven_by(ctx, cell->ports.at(ctx->id("CIN")).net, is_lc, ctx->id("COUT"));
},
[](const Context *ctx, const CellInfo *cell) {
return net_only_drives(ctx, cell->ports.at(ctx->id("COUT")).net, is_lc, ctx->id("CIN"), false);
});
// TODO
return true;
PlacementLegaliser lg(ctx);
return lg.legalise();
}
NEXTPNR_NAMESPACE_END