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Another heuristic experiment

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Signed-off-by: David Shah <davey1576@gmail.com>
This commit is contained in:
David Shah 2018-06-13 19:10:12 +02:00
parent b1e08fa064
commit 3ef45d2a27
1 changed files with 18 additions and 77 deletions
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95
common/place.cc
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@ -123,45 +123,32 @@ void place_design(Design *design)
}
}
static void place_cell(Design *design, CellInfo *cell, BelId closeTo,
size_t &placed_cells,
std::queue<CellInfo *> &visit_cells)
static void place_cell(Design *design, CellInfo *cell)
{
assert(cell->bel == BelId());
float best_distance = std::numeric_limits<float>::infinity();
BelId best_bel = BelId();
Chip &chip = design->chip;
BelType targetType = belTypeFromId(cell->type);
PosInfo origin;
if (closeTo != BelId()) {
origin = chip.getBelPosition(closeTo);
for (auto bel : chip.getBelsAtSameTile(closeTo)) {
if (chip.getBelType(bel) == targetType && chip.checkBelAvail(bel) &&
isValidBelForCell(design, cell, bel)) {
// prefer same tile
best_bel = bel;
goto placed;
}
}
}
for (auto bel : chip.getBels()) {
if (chip.getBelType(bel) == targetType && chip.checkBelAvail(bel) &&
isValidBelForCell(design, cell, bel)) {
if (closeTo == BelId()) {
best_distance = 0;
best_bel = bel;
goto placed;
} else {
float distance =
chip.estimateDelay(origin, chip.getBelPosition(bel));
if (distance < best_distance) {
best_distance = distance;
best_bel = bel;
float distance = 0;
PosInfo belPosition = chip.getBelPosition(bel);
for (auto port : cell->ports) {
const PortInfo &pi = port.second;
if(pi.net != nullptr && pi.type == PORT_IN) {
CellInfo *drv = pi.net->driver.cell;
if (drv != nullptr && drv->bel != BelId())
distance += chip.estimateDelay(chip.getBelPosition(drv->bel), belPosition);
}
}
if (distance < best_distance) {
best_distance = distance;
best_bel = bel;
}
}
}
placed:
if (best_bel == BelId()) {
log_error("failed to place cell '%s' of type '%s'\n",
cell->name.c_str(), cell->type.c_str());
@ -171,42 +158,6 @@ placed:
// Back annotate location
cell->attrs["BEL"] = chip.getBelName(cell->bel).str();
placed_cells++;
visit_cells.push(cell);
}
static void place_cell_neighbours(Design *design, CellInfo *cell,
size_t &placed_cells,
std::queue<CellInfo *> &visit_cells)
{
if (cell->bel == BelId())
return;
int placed_count = 0;
const int count_thresh = 15;
for (auto port : cell->ports) {
NetInfo *net = port.second.net;
if (net != nullptr) {
for (auto user : net->users) {
if (net->users.size() > 3)
continue;
if (user.cell != nullptr && user.cell->bel == BelId()) {
place_cell(design, user.cell, cell->bel, placed_cells,
visit_cells);
placed_count++;
if (placed_count > count_thresh)
return;
}
}
if (net->driver.cell != nullptr && net->driver.cell->bel == BelId()) {
place_cell(design, net->driver.cell, cell->bel, placed_cells,
visit_cells);
placed_count++;
}
if (placed_count > count_thresh)
return;
}
}
}
void place_design_heuristic(Design *design)
@ -241,21 +192,11 @@ void place_design_heuristic(Design *design)
}
}
log_info("place_constraints placed %d\n", placed_cells);
while (placed_cells < total_cells) {
if (!visit_cells.empty()) {
CellInfo *next = visit_cells.front();
visit_cells.pop();
place_cell_neighbours(design, next, placed_cells, visit_cells);
} else {
// Nothing to visit (netlist is split), pick the next unplaced cell
for (auto cell : design->cells) {
CellInfo *ci = cell.second;
if (ci->bel == BelId()) {
place_cell(design, ci, BelId(), placed_cells, visit_cells);
break;
}
}
}
for (auto cell : design->cells) {
CellInfo *ci = cell.second;
if (ci->bel == BelId())
place_cell(design, ci);
placed_cells++;
log_info("placed %d/%d\n", placed_cells, total_cells);
}
}