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static: Speedup with parallel wirelength gradient computation

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Signed-off-by: gatecat <gatecat@ds0.me>
This commit is contained in:
gatecat 2024-06-18 13:53:42 +02:00
parent 945cf48c6c
commit c89037db49
1 changed files with 20 additions and 8 deletions
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20
common/place/placer_static.cc
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@ -801,6 +801,8 @@ class StaticPlacer
});
}
std::vector<std::pair<CellInfo *, RealPair>> gathered_wirelen_grad;
float wirelen_grad(CellInfo *cell, Axis axis, bool ref)
{
float gradient = 0;
@ -878,16 +880,26 @@ class StaticPlacer
// total gradient computed at the end
(ref ? cell.ref_total_grad : cell.total_grad) = RealPair(0, 0);
}
// Second loop: sum up wirelength gradients across concrete cell instances
if (gathered_wirelen_grad.empty()) {
for (auto &cell : ctx->cells) {
CellInfo *ci = cell.second.get();
if (ci->udata == -1)
continue;
auto &mc = mcells.at(ci->udata);
// TODO: exploit parallelism across axes
gathered_wirelen_grad.emplace_back(ci, RealPair());
}
}
// Compute wirelength gradients for cells in parallel, this is a slow part
pool.run(gathered_wirelen_grad.size(), [&](int i) {
auto &entry = gathered_wirelen_grad.at(i);
CellInfo *ci = entry.first;
float wl_gx = wirelen_grad(ci, Axis::X, ref);
float wl_gy = wirelen_grad(ci, Axis::Y, ref);
(ref ? mc.ref_wl_grad : mc.wl_grad) += RealPair(wl_gx, wl_gy);
entry.second = RealPair(wl_gx, wl_gy);
});
// Second loop: sum up wirelength gradients across concrete cell instances
for (auto entry : gathered_wirelen_grad) {
auto &mc = mcells.at(entry.first->udata);
(ref ? mc.ref_wl_grad : mc.wl_grad) += entry.second;
}
if (init_penalty) {
// set initial density penalty