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nexus: Use a toposort when preplacing clock primitives

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Signed-off-by: gatecat <gatecat@ds0.me>
This commit is contained in:
gatecat 2024-05-16 14:27:54 +02:00 committed by myrtle
parent 423f1b7159
commit 59a29e5f42
1 changed files with 39 additions and 11 deletions
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50
nexus/pack.cc
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@ -916,19 +916,47 @@ struct NexusPacker
{
// Keep running until we reach a fixed point
log_info("Placing globals...\n");
bool did_something = true;
while (did_something) {
did_something = false;
for (auto &cell : ctx->cells) {
CellInfo *ci = cell.second.get();
if (ci->type == id_OSC_CORE)
did_something |= preplace_singleton(ci);
else if (ci->type == id_DCC)
did_something |= preplace_prim(ci, id_CLKI, false);
else if (ci->type == id_PLL_CORE)
did_something |= preplace_prim(ci, id_REFCK, false);
TopoSort<IdString> sorter;
auto is_glb_cell = [&](const CellInfo *cell) {
return cell->type.in(id_OSC_CORE, id_DCC, id_PLL_CORE, id_DCS);
};
for (auto &cell : ctx->cells) {
CellInfo *ci = cell.second.get();
if (is_glb_cell(ci)) {
sorter.node(ci->name);
auto do_pin = [&](IdString pin) {
NetInfo *net = ci->getPort(pin);
if (!net || !net->driver.cell || !is_glb_cell(net->driver.cell))
return;
sorter.edge(net->driver.cell->name, ci->name);
};
if (ci->type == id_PLL_CORE) {
do_pin(id_REFCK);
} else if (ci->type == id_DCC) {
do_pin(id_CLKI);
} else if (ci->type == id_DCS) {
do_pin(id_CLK0);
do_pin(id_CLK1);
}
}
}
sorter.sort();
for (IdString cell_name : sorter.sorted) {
CellInfo *ci = ctx->cells.at(cell_name).get();
if (ci->type == id_OSC_CORE)
preplace_singleton(ci);
else if (ci->type == id_DCC)
preplace_prim(ci, id_CLKI, false);
else if (ci->type == id_PLL_CORE)
preplace_prim(ci, id_REFCK, false);
else if (ci->type == id_DCS)
preplace_prim(ci, id_CLK0, false);
}
}
// Get a bus port name