/*
* nextpnr -- Next Generation Place and Route
*
* Copyright (C) 2018 Clifford Wolf <clifford@symbioticeda.com>
* Copyright (C) 2018 David Shah <david@symbioticeda.com>
*
* Simulated annealing implementation based on arachne-pnr
* Copyright (C) 2015-2018 Cotton Seed
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*
*/
#include "placer1.h"
#include <algorithm>
#include <boost/lexical_cast.hpp>
#include <boost/range/adaptor/reversed.hpp>
#include <chrono>
#include <cmath>
#include <iostream>
#include <limits>
#include <list>
#include <map>
#include <ostream>
#include <queue>
#include <set>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <vector>
#include "fast_bels.h"
#include "log.h"
#include "place_common.h"
#include "timing.h"
#include "util.h"
namespace std {
template <> struct hash<std::pair<NEXTPNR_NAMESPACE_PREFIX IdString, std::size_t>>
{
std::size_t operator()(const std::pair<NEXTPNR_NAMESPACE_PREFIX IdString, std::size_t> &idp) const noexcept
{
std::size_t seed = 0;
boost::hash_combine(seed, hash<NEXTPNR_NAMESPACE_PREFIX IdString>()(idp.first));
boost::hash_combine(seed, hash<std::size_t>()(idp.second));
return seed;
}
};
} // namespace std
NEXTPNR_NAMESPACE_BEGIN
class SAPlacer
{
private:
struct BoundingBox
{
// Actual bounding box
int x0 = 0, x1 = 0, y0 = 0, y1 = 0;
// Number of cells at each extremity
int nx0 = 0, nx1 = 0, ny0 = 0, ny1 = 0;
wirelen_t hpwl(const Placer1Cfg &cfg) const
{
return wirelen_t(cfg.hpwl_scale_x * (x1 - x0) + cfg.hpwl_scale_y * (y1 - y0));
}
};
public:
SAPlacer(Context *ctx, Placer1Cfg cfg)
: ctx(ctx), fast_bels(ctx, /*check_bel_available=*/false, cfg.minBelsForGridPick), cfg(cfg)
{
for (auto bel : ctx->getBels()) {
Loc loc = ctx->getBelLocation(bel);
max_x = std::max(max_x, loc.x);
max_y = std::max(max_y, loc.y);
}
diameter = std::max(max_x, max_y) + 1;
std::unordered_set<IdString> cell_types_in_use;
for (auto cell : sorted(ctx->cells)) {
IdString cell_type = cell.second->type;
cell_types_in_use.insert(cell_type);
}
for (auto cell_type : cell_types_in_use) {
fast_bels.addCellType(cell_type);
}
net_bounds.resize(ctx->nets.size());
net_arc_tcost.resize(ctx->nets.size());
old_udata.reserve(ctx->nets.size());
net_by_udata.reserve(ctx->nets.size());
decltype(NetInfo::udata) n = 0;
for (auto &net : ctx->nets) {
old_udata.emplace_back(net.second->udata);
net_arc_tcost.at(n).resize(net.second->users.size());
net.second->udata = n++;
net_by_udata.push_back(net.second.get());
}
for (auto ®ion : sorted(ctx->region)) {
Region *r = region.second;
BoundingBox bb;
if (r->constr_bels) {
bb.x0 = std::numeric_limits<int>::max();
bb.x1 = std::numeric_limits<int>::min();
bb.y0 = std::numeric_limits<int>::max();
bb.y1 = std::numeric_limits<int>::min();
for (auto bel : r->bels) {
Loc loc = ctx->getBelLocation(bel);
bb.x0 = std::min(bb.x0, loc.x);
bb.x1 = std::max(bb.x1, loc.x);
bb.y0 = std::min(bb.y0, loc.y);
bb.y1 = std::max(bb.y1, loc.y);
}
} else {
bb.x0 = 0;
bb.y0 = 0;
bb.x1 = max_x;
bb.y1 = max_y;
}
region_bounds[r->name] = bb;
}
build_port_index();
}
~SAPlacer()
{
for (auto &net : ctx->nets)
net.second->udata = old_udata[net.second->udata];
}
bool place(bool refine = false)
{
log_break();
ctx->lock();
size_t placed_cells = 0;
std::vector<CellInfo *> autoplaced;
std::vector<CellInfo *> chain_basis;
if (!refine) {
// Initial constraints placer
for (auto &cell_entry : ctx->cells) {
CellInfo *cell = cell_entry.second.get();
auto loc = cell->attrs.find(ctx->id("BEL"));
if (loc != cell->attrs.end()) {
std::string loc_name = loc->second.as_string();
BelId bel = ctx->getBelByNameStr(loc_name);
if (bel == BelId()) {
log_error("No Bel named \'%s\' located for "
"this chip (processing BEL attribute on \'%s\')\n",
loc_name.c_str(), cell->name.c_str(ctx));
}
if (!ctx->isValidBelForCellType(cell->type, bel)) {
IdString bel_type = ctx->getBelType(bel);
log_error("Bel \'%s\' of type \'%s\' does not match cell "
"\'%s\' of type \'%s\'\n",
loc_name.c_str(), bel_type.c_str(ctx), cell->name.c_str(ctx), cell->type.c_str(ctx));
}
auto bound_cell = ctx->getBoundBelCell(bel);
if (bound_cell) {
log_error(
"Cell \'%s\' cannot be bound to bel \'%s\' since it is already bound to cell \'%s\'\n",
cell->name.c_str(ctx), loc_name.c_str(), bound_cell->name.c_str(ctx));
}
ctx->bindBel(bel, cell, STRENGTH_USER);
if (!ctx->isBelLocationValid(bel)) {
IdString bel_type = ctx->getBelType(bel);
log_error("Bel \'%s\' of type \'%s\' is not valid for cell "
"\'%s\' of type \'%s\'\n",
loc_name.c_str(), bel_type.c_str(ctx), cell->name.c_str(ctx), cell->type.c_str(ctx));
}
locked_bels.insert(bel);
placed_cells++;
}
}
int constr_placed_cells = placed_cells;
log_info("Placed %d cells based on constraints.\n", int(placed_cells));
ctx->yield();
// Sort to-place cells for deterministic initial placement
for (auto &cell : ctx->cells) {
CellInfo *ci = cell.second.get();
if (ci->bel == BelId()) {
autoplaced.push_back(cell.second.get());
}
}
std::sort(autoplaced.begin(), autoplaced.end(), [](CellInfo *a, CellInfo *b) { return a->name < b->name; });
ctx->shuffle(autoplaced);
auto iplace_start = std::chrono::high_resolution_clock::now();
// Place cells randomly initially
log_info("Creating initial placement for remaining %d cells.\n", int(autoplaced.size()));
for (auto cell : autoplaced) {
place_initial(cell);
placed_cells++;
if ((placed_cells - constr_placed_cells) % 500 == 0)
log_info(" initial placement placed %d/%d cells\n", int(placed_cells - constr_placed_cells),
int(autoplaced.size()));
}
if ((placed_cells - constr_placed_cells) % 500 != 0)
log_info(" initial placement placed %d/%d cells\n", int(placed_cells - constr_placed_cells),
int(autoplaced.size()));
if (cfg.budgetBased && cfg.slack_redist_iter > 0)
assign_budget(ctx);
ctx->yield();
auto iplace_end = std::chrono::high_resolution_clock::now();
log_info("Initial placement time %.02fs\n",
std::chrono::duration<float>(iplace_end - iplace_start).count());
log_info("Running simulated annealing placer.\n");
} else {
for (auto &cell : ctx->cells) {
CellInfo *ci = cell.second.get();
if (ci->belStrength > STRENGTH_STRONG)
continue;
else if (ci->constr_parent != nullptr)
continue;
else if (!ci->constr_children.empty() || ci->constr_z != ci->UNCONSTR)
chain_basis.push_back(ci);
else
autoplaced.push_back(ci);
}
require_legal = false;
diameter = 3;
log_info("Running simulated annealing placer for refinement.\n");
}
auto saplace_start = std::chrono::high_resolution_clock::now();
// Invoke timing analysis to obtain criticalities
if (!cfg.budgetBased)
get_criticalities(ctx, &net_crit);
// Calculate costs after initial placement
setup_costs();
moveChange.init(this);
curr_wirelen_cost = total_wirelen_cost();
curr_timing_cost = total_timing_cost();
last_wirelen_cost = curr_wirelen_cost;
last_timing_cost = curr_timing_cost;
if (cfg.netShareWeight > 0)
setup_nets_by_tile();
wirelen_t avg_wirelen = curr_wirelen_cost;
wirelen_t min_wirelen = curr_wirelen_cost;
int n_no_progress = 0;
temp = refine ? 1e-7 : cfg.startTemp;
// Main simulated annealing loop
for (int iter = 1;; iter++) {
n_move = n_accept = 0;
improved = false;
if (iter % 5 == 0 || iter == 1)
log_info(" at iteration #%d: temp = %f, timing cost = "
"%.0f, wirelen = %.0f\n",
iter, temp, double(curr_timing_cost), double(curr_wirelen_cost));
for (int m = 0; m < 15; ++m) {
// Loop through all automatically placed cells
for (auto cell : autoplaced) {
// Find another random Bel for this cell
BelId try_bel = random_bel_for_cell(cell);
// If valid, try and swap to a new position and see if
// the new position is valid/worthwhile
if (try_bel != BelId() && try_bel != cell->bel)
try_swap_position(cell, try_bel);
}
// Also try swapping chains, if applicable
for (auto cb : chain_basis) {
Loc chain_base_loc = ctx->getBelLocation(cb->bel);
BelId try_base = random_bel_for_cell(cb, chain_base_loc.z);
if (try_base != BelId() && try_base != cb->bel)
try_swap_chain(cb, try_base);
}
}
if (ctx->debug) {
// Verify correctness of incremental wirelen updates
for (size_t i = 0; i < net_bounds.size(); i++) {
auto net = net_by_udata[i];
if (ignore_net(net))
continue;
auto &incr = net_bounds.at(i), gold = get_net_bounds(net);
NPNR_ASSERT(incr.x0 == gold.x0);
NPNR_ASSERT(incr.x1 == gold.x1);
NPNR_ASSERT(incr.y0 == gold.y0);
NPNR_ASSERT(incr.y1 == gold.y1);
NPNR_ASSERT(incr.nx0 == gold.nx0);
NPNR_ASSERT(incr.nx1 == gold.nx1);
NPNR_ASSERT(incr.ny0 == gold.ny0);
NPNR_ASSERT(incr.ny1 == gold.ny1);
}
}
if (curr_wirelen_cost < min_wirelen) {
min_wirelen = curr_wirelen_cost;
improved = true;
}
// Heuristic to improve placement on the 8k
if (improved)
n_no_progress = 0;
else
n_no_progress++;
if (temp <= 1e-7 && n_no_progress >= (refine ? 1 : 5)) {
log_info(" at iteration #%d: temp = %f, timing cost = "
"%.0f, wirelen = %.0f \n",
iter, temp, double(curr_timing_cost), double(curr_wirelen_cost));
break;
}
double Raccept = double(n_accept) / double(n_move);
int M = std::max(max_x, max_y) + 1;
if (ctx->verbose)
log("iter #%d: temp = %f, timing cost = "
"%.0f, wirelen = %.0f, dia = %d, Ra = %.02f \n",
iter, temp, double(curr_timing_cost), double(curr_wirelen_cost), diameter, Raccept);
if (curr_wirelen_cost < 0.95 * avg_wirelen && curr_wirelen_cost > 0) {
avg_wirelen = 0.8 * avg_wirelen + 0.2 * curr_wirelen_cost;
} else {
double diam_next = diameter * (1.0 - 0.44 + Raccept);
diameter = std::max<int>(1, std::min<int>(M, int(diam_next + 0.5)));
if (Raccept > 0.96) {
temp *= 0.5;
} else if (Raccept > 0.8) {
temp *= 0.9;
} else if (Raccept > 0.15 && diameter > 1) {
temp *= 0.95;
} else {
temp *= 0.8;
}
}
// Once cooled below legalise threshold, run legalisation and start requiring
// legal moves only
if (diameter < legalise_dia && require_legal) {
if (legalise_relative_constraints(ctx)) {
// Only increase temperature if something was moved
autoplaced.clear();
chain_basis.clear();
for (auto cell : sorted(ctx->cells)) {
if (cell.second->belStrength <= STRENGTH_STRONG && cell.second->constr_parent == nullptr &&
!cell.second->constr_children.empty())
chain_basis.push_back(cell.second);
else if (cell.second->belStrength < STRENGTH_STRONG)
autoplaced.push_back(cell.second);
}
// temp = post_legalise_temp;
// diameter = std::min<int>(M, diameter * post_legalise_dia_scale);
ctx->shuffle(autoplaced);
// Legalisation is a big change so force a slack redistribution here
if (cfg.slack_redist_iter > 0 && cfg.budgetBased)
assign_budget(ctx, true /* quiet */);
}
require_legal = false;
} else if (cfg.budgetBased && cfg.slack_redist_iter > 0 && iter % cfg.slack_redist_iter == 0) {
assign_budget(ctx, true /* quiet */);
}
// Invoke timing analysis to obtain criticalities
if (!cfg.budgetBased && cfg.timing_driven)
get_criticalities(ctx, &net_crit);
// Need to rebuild costs after criticalities change
setup_costs();
// Reset incremental bounds
moveChange.reset(this);
moveChange.new_net_bounds = net_bounds;
// Recalculate total metric entirely to avoid rounding errors
// accumulating over time
curr_wirelen_cost = total_wirelen_cost();
curr_timing_cost = total_timing_cost();
last_wirelen_cost = curr_wirelen_cost;
last_timing_cost = curr_timing_cost;
// Let the UI show visualization updates.
ctx->yield();
}
auto saplace_end = std::chrono::high_resolution_clock::now();
log_info("SA placement time %.02fs\n", std::chrono::duration<float>(saplace_end - saplace_start).count());
// Final post-placement validity check
ctx->yield();
for (auto bel : ctx->getBels()) {
CellInfo *cell = ctx->getBoundBelCell(bel);
if (!ctx->isBelLocationValid(bel)) {
std::string cell_text = "no cell";
if (cell != nullptr)
cell_text = std::string("cell '") + ctx->nameOf(cell) + "'";
if (ctx->force) {
log_warning("post-placement validity check failed for Bel '%s' "
"(%s)\n",
ctx->nameOfBel(bel), cell_text.c_str());
} else {
log_error("post-placement validity check failed for Bel '%s' "
"(%s)\n",
ctx->nameOfBel(bel), cell_text.c_str());
}
}
}
for (auto cell : sorted(ctx->cells))
if (get_constraints_distance(ctx, cell.second) != 0)
log_error("constraint satisfaction check failed for cell '%s' at Bel '%s'\n", cell.first.c_str(ctx),
ctx->nameOfBel(cell.second->bel));
timing_analysis(ctx);
ctx->unlock();
return true;
}
private:
// Initial random placement
void place_initial(CellInfo *cell)
{
bool all_placed = false;
int iters = 25;
while (!all_placed) {
BelId best_bel = BelId();
uint64_t best_score = std::numeric_limits<uint64_t>::max(),
best_ripup_score = std::numeric_limits<uint64_t>::max();
CellInfo *ripup_target = nullptr;
BelId ripup_bel = BelId();
if (cell->bel != BelId()) {
ctx->unbindBel(cell->bel);
}
IdString targetType = cell->type;
auto proc_bel = [&](BelId bel) {
if (ctx->isValidBelForCellType(targetType, bel)) {
if (ctx->checkBelAvail(bel)) {
uint64_t score = ctx->rng64();
if (score <= best_score) {
best_score = score;
best_bel = bel;
}
} else {
uint64_t score = ctx->rng64();
CellInfo *bound_cell = ctx->getBoundBelCell(bel);
if (score <= best_ripup_score && bound_cell->belStrength < STRENGTH_STRONG) {
best_ripup_score = score;
ripup_target = bound_cell;
ripup_bel = bel;
}
}
}
};
if (cell->region != nullptr && cell->region->constr_bels) {
for (auto bel : cell->region->bels) {
proc_bel(bel);
}
} else {
for (auto bel : ctx->getBels()) {
proc_bel(bel);
}
}
if (best_bel == BelId()) {
if (iters == 0 || ripup_bel == BelId())
log_error("failed to place cell '%s' of type '%s'\n", cell->name.c_str(ctx), cell->type.c_str(ctx));
--iters;
ctx->unbindBel(ripup_target->bel);
best_bel = ripup_bel;
} else {
ripup_target = nullptr;
all_placed = true;
}
ctx->bindBel(best_bel, cell, STRENGTH_WEAK);
if (!ctx->isBelLocationValid(best_bel)) {
ctx->unbindBel(best_bel);
if (ripup_target != nullptr) {
ctx->bindBel(best_bel, ripup_target, STRENGTH_WEAK);
}
all_placed = false;
continue;
}
// Back annotate location
cell->attrs[ctx->id("BEL")] = ctx->getBelName(cell->bel).str(ctx);
cell = ripup_target;
}
}
// Attempt a SA position swap, return true on success or false on failure
bool try_swap_position(CellInfo *cell, BelId newBel)
{
static const double epsilon = 1e-20;
moveChange.reset(this);
if (!require_legal && cell->isConstrained(false))
return false;
BelId oldBel = cell->bel;
CellInfo *other_cell = ctx->getBoundBelCell(newBel);
if (!require_legal && other_cell != nullptr &&
(other_cell->isConstrained(false) || other_cell->belStrength > STRENGTH_WEAK)) {
return false;
}
int old_dist = get_constraints_distance(ctx, cell);
int new_dist;
if (other_cell != nullptr)
old_dist += get_constraints_distance(ctx, other_cell);
double delta = 0;
int net_delta_score = 0;
if (cfg.netShareWeight > 0)
net_delta_score += update_nets_by_tile(cell, ctx->getBelLocation(cell->bel), ctx->getBelLocation(newBel));
ctx->unbindBel(oldBel);
if (other_cell != nullptr) {
ctx->unbindBel(newBel);
}
ctx->bindBel(newBel, cell, STRENGTH_WEAK);
if (other_cell != nullptr) {
ctx->bindBel(oldBel, other_cell, STRENGTH_WEAK);
if (cfg.netShareWeight > 0)
net_delta_score +=
update_nets_by_tile(other_cell, ctx->getBelLocation(newBel), ctx->getBelLocation(oldBel));
}
add_move_cell(moveChange, cell, oldBel);
if (other_cell != nullptr) {
add_move_cell(moveChange, other_cell, newBel);
}
if (!ctx->isBelLocationValid(newBel) || ((other_cell != nullptr && !ctx->isBelLocationValid(oldBel)))) {
ctx->unbindBel(newBel);
if (other_cell != nullptr)
ctx->unbindBel(oldBel);
goto swap_fail;
}
// Recalculate metrics for all nets touched by the perturbation
compute_cost_changes(moveChange);
new_dist = get_constraints_distance(ctx, cell);
if (other_cell != nullptr)
new_dist += get_constraints_distance(ctx, other_cell);
delta = lambda * (moveChange.timing_delta / std::max<double>(last_timing_cost, epsilon)) +
(1 - lambda) * (double(moveChange.wirelen_delta) / std::max<double>(last_wirelen_cost, epsilon));
delta += (cfg.constraintWeight / temp) * (new_dist - old_dist) / last_wirelen_cost;
if (cfg.netShareWeight > 0)
delta += -cfg.netShareWeight * (net_delta_score / std::max<double>(total_net_share, epsilon));
n_move++;
// SA acceptance criteria
if (delta < 0 || (temp > 1e-8 && (ctx->rng() / float(0x3fffffff)) <= std::exp(-delta / temp))) {
n_accept++;
} else {
if (other_cell != nullptr)
ctx->unbindBel(oldBel);
ctx->unbindBel(newBel);
goto swap_fail;
}
commit_cost_changes(moveChange);
#if 0
log_info("swap %s -> %s\n", cell->name.c_str(ctx), ctx->nameOfBel(newBel));
if (other_cell != nullptr)
log_info("swap %s -> %s\n", other_cell->name.c_str(ctx), ctx->nameOfBel(oldBel));
#endif
return true;
swap_fail:
ctx->bindBel(oldBel, cell, STRENGTH_WEAK);
if (other_cell != nullptr) {
ctx->bindBel(newBel, other_cell, STRENGTH_WEAK);
if (cfg.netShareWeight > 0)
update_nets_by_tile(other_cell, ctx->getBelLocation(oldBel), ctx->getBelLocation(newBel));
}
if (cfg.netShareWeight > 0)
update_nets_by_tile(cell, ctx->getBelLocation(newBel), ctx->getBelLocation(oldBel));
return false;
}
// Swap the Bel of a cell with another, return the original location
BelId swap_cell_bels(CellInfo *cell, BelId newBel)
{
BelId oldBel = cell->bel;
#if 0
log_info("%s old: %s new: %s\n", cell->name.c_str(ctx), ctx->nameOfBel(cell->bel), ctx->nameOfBel(newBel));
#endif
CellInfo *bound = ctx->getBoundBelCell(newBel);
if (bound != nullptr)
ctx->unbindBel(newBel);
ctx->unbindBel(oldBel);
ctx->bindBel(newBel, cell, cell->isConstrained(false) ? STRENGTH_STRONG : STRENGTH_WEAK);
if (bound != nullptr) {
ctx->bindBel(oldBel, bound, bound->isConstrained(false) ? STRENGTH_STRONG : STRENGTH_WEAK);
if (cfg.netShareWeight > 0)
update_nets_by_tile(bound, ctx->getBelLocation(newBel), ctx->getBelLocation(oldBel));
}
if (cfg.netShareWeight > 0)
update_nets_by_tile(cell, ctx->getBelLocation(oldBel), ctx->getBelLocation(newBel));
return oldBel;
}
// Discover the relative positions of all cells in a chain
void discover_chain(Loc baseLoc, CellInfo *cell, std::vector<std::pair<CellInfo *, Loc>> &cell_rel)
{
Loc cellLoc = ctx->getBelLocation(cell->bel);
Loc rel{cellLoc.x - baseLoc.x, cellLoc.y - baseLoc.y, cellLoc.z};
cell_rel.emplace_back(std::make_pair(cell, rel));
for (auto child : cell->constr_children)
discover_chain(baseLoc, child, cell_rel);
}
// Attempt to swap a chain with a non-chain
bool try_swap_chain(CellInfo *cell, BelId newBase)
{
std::vector<std::pair<CellInfo *, Loc>> cell_rel;
std::unordered_set<IdString> cells;
std::vector<std::pair<CellInfo *, BelId>> moves_made;
std::vector<std::pair<CellInfo *, BelId>> dest_bels;
double delta = 0;
int orig_share_cost = total_net_share;
moveChange.reset(this);
#if 0
if (ctx->debug)
log_info("finding cells for chain swap %s\n", cell->name.c_str(ctx));
#endif
Loc baseLoc = ctx->getBelLocation(cell->bel);
discover_chain(baseLoc, cell, cell_rel);
Loc newBaseLoc = ctx->getBelLocation(newBase);
NPNR_ASSERT(newBaseLoc.z == baseLoc.z);
for (const auto &cr : cell_rel)
cells.insert(cr.first->name);
for (const auto &cr : cell_rel) {
Loc targetLoc = {newBaseLoc.x + cr.second.x, newBaseLoc.y + cr.second.y, cr.second.z};
BelId targetBel = ctx->getBelByLocation(targetLoc);
if (targetBel == BelId())
return false;
if (!ctx->isValidBelForCellType(cell->type, targetBel))
return false;
CellInfo *bound = ctx->getBoundBelCell(targetBel);
// We don't consider swapping chains with other chains, at least for the time being - unless it is
// part of this chain
if (bound != nullptr && !cells.count(bound->name) &&
(bound->belStrength >= STRENGTH_STRONG || bound->isConstrained(false)))
return false;
dest_bels.emplace_back(std::make_pair(cr.first, targetBel));
}
#if 0
if (ctx->debug)
log_info("trying chain swap %s\n", cell->name.c_str(ctx));
#endif
// <cell, oldBel>
for (const auto &db : dest_bels) {
BelId oldBel = swap_cell_bels(db.first, db.second);
moves_made.emplace_back(std::make_pair(db.first, oldBel));
CellInfo *bound = ctx->getBoundBelCell(oldBel);
add_move_cell(moveChange, db.first, oldBel);
if (bound != nullptr)
add_move_cell(moveChange, bound, db.second);
}
for (const auto &mm : moves_made) {
if (!ctx->isBelLocationValid(mm.first->bel) || !mm.first->testRegion(mm.first->bel))
goto swap_fail;
if (!ctx->isBelLocationValid(mm.second))
goto swap_fail;
CellInfo *bound = ctx->getBoundBelCell(mm.second);
if (bound && !bound->testRegion(bound->bel))
goto swap_fail;
}
compute_cost_changes(moveChange);
delta = lambda * (moveChange.timing_delta / last_timing_cost) +
(1 - lambda) * (double(moveChange.wirelen_delta) / last_wirelen_cost);
if (cfg.netShareWeight > 0) {
delta +=
cfg.netShareWeight * (orig_share_cost - total_net_share) / std::max<double>(total_net_share, 1e-20);
}
n_move++;
// SA acceptance criteria
if (delta < 0 || (temp > 1e-9 && (ctx->rng() / float(0x3fffffff)) <= std::exp(-delta / temp))) {
n_accept++;
#if 0
if (ctx->debug)
log_info("accepted chain swap %s\n", cell->name.c_str(ctx));
#endif
} else {
goto swap_fail;
}
commit_cost_changes(moveChange);
return true;
swap_fail:
for (const auto &entry : boost::adaptors::reverse(moves_made))
swap_cell_bels(entry.first, entry.second);
return false;
}
// Find a random Bel of the correct type for a cell, within the specified
// diameter
BelId random_bel_for_cell(CellInfo *cell, int force_z = -1)
{
IdString targetType = cell->type;
Loc curr_loc = ctx->getBelLocation(cell->bel);
int count = 0;
int dx = diameter, dy = diameter;
if (cell->region != nullptr && cell->region->constr_bels) {
dx = std::min(cfg.hpwl_scale_x * diameter,
(region_bounds[cell->region->name].x1 - region_bounds[cell->region->name].x0) + 1);
dy = std::min(cfg.hpwl_scale_y * diameter,
(region_bounds[cell->region->name].y1 - region_bounds[cell->region->name].y0) + 1);
// Clamp location to within bounds
curr_loc.x = std::max(region_bounds[cell->region->name].x0, curr_loc.x);
curr_loc.x = std::min(region_bounds[cell->region->name].x1, curr_loc.x);
curr_loc.y = std::max(region_bounds[cell->region->name].y0, curr_loc.y);
curr_loc.y = std::min(region_bounds[cell->region->name].y1, curr_loc.y);
}
FastBels::FastBelsData *bel_data;
auto type_cnt = fast_bels.getBelsForCellType(targetType, &bel_data);
while (true) {
int nx = ctx->rng(2 * dx + 1) + std::max(curr_loc.x - dx, 0);
int ny = ctx->rng(2 * dy + 1) + std::max(curr_loc.y - dy, 0);
if (cfg.minBelsForGridPick >= 0 && type_cnt < cfg.minBelsForGridPick)
nx = ny = 0;
if (nx >= int(bel_data->size()))
continue;
if (ny >= int(bel_data->at(nx).size()))
continue;
const auto &fb = bel_data->at(nx).at(ny);
if (fb.size() == 0)
continue;
BelId bel = fb.at(ctx->rng(int(fb.size())));
if (force_z != -1) {
Loc loc = ctx->getBelLocation(bel);
if (loc.z != force_z)
continue;
}
if (!cell->testRegion(bel))
continue;
if (locked_bels.find(bel) != locked_bels.end())
continue;
count++;
return bel;
}
}
// Return true if a net is to be entirely ignored
inline bool ignore_net(NetInfo *net)
{
return net->driver.cell == nullptr || net->driver.cell->bel == BelId() ||
ctx->getBelGlobalBuf(net->driver.cell->bel);
}
// Get the bounding box for a net
inline BoundingBox get_net_bounds(NetInfo *net)
{
BoundingBox bb;
NPNR_ASSERT(net->driver.cell != nullptr);
Loc dloc = ctx->getBelLocation(net->driver.cell->bel);
bb.x0 = dloc.x;
bb.x1 = dloc.x;
bb.y0 = dloc.y;
bb.y1 = dloc.y;
bb.nx0 = 1;
bb.nx1 = 1;
bb.ny0 = 1;
bb.ny1 = 1;
for (auto user : net->users) {
if (user.cell->bel == BelId())
continue;
Loc uloc = ctx->getBelLocation(user.cell->bel);
if (bb.x0 == uloc.x)
++bb.nx0;
else if (uloc.x < bb.x0) {
bb.x0 = uloc.x;
bb.nx0 = 1;
}
if (bb.x1 == uloc.x)
++bb.nx1;
else if (uloc.x > bb.x1) {
bb.x1 = uloc.x;
bb.nx1 = 1;
}
if (bb.y0 == uloc.y)
++bb.ny0;
else if (uloc.y < bb.y0) {
bb.y0 = uloc.y;
bb.ny0 = 1;
}
if (bb.y1 == uloc.y)
++bb.ny1;
else if (uloc.y > bb.y1) {
bb.y1 = uloc.y;
bb.ny1 = 1;
}
}
return bb;
}
// Get the timing cost for an arc of a net
inline double get_timing_cost(NetInfo *net, size_t user)
{
int cc;
if (net->driver.cell == nullptr)
return 0;
if (ctx->getPortTimingClass(net->driver.cell, net->driver.port, cc) == TMG_IGNORE)
return 0;
if (cfg.budgetBased) {
double delay = ctx->getDelayNS(ctx->predictDelay(net, net->users.at(user)));
return std::min(10.0, std::exp(delay - ctx->getDelayNS(net->users.at(user).budget) / 10));
} else {
auto crit = net_crit.find(net->name);
if (crit == net_crit.end() || crit->second.criticality.empty())
return 0;
double delay = ctx->getDelayNS(ctx->predictDelay(net, net->users.at(user)));
return delay * std::pow(crit->second.criticality.at(user), crit_exp);
}
}
// Set up the cost maps
void setup_costs()
{
for (auto net : sorted(ctx->nets)) {
NetInfo *ni = net.second;
if (ignore_net(ni))
continue;
net_bounds[ni->udata] = get_net_bounds(ni);
if (cfg.timing_driven && int(ni->users.size()) < cfg.timingFanoutThresh)
for (size_t i = 0; i < ni->users.size(); i++)
net_arc_tcost[ni->udata][i] = get_timing_cost(ni, i);
}
}
// Get the total wiring cost for the design
wirelen_t total_wirelen_cost()
{
wirelen_t cost = 0;
for (const auto &net : net_bounds)
cost += net.hpwl(cfg);
return cost;
}
// Get the total timing cost for the design
double total_timing_cost()
{
double cost = 0;
for (const auto &net : net_arc_tcost) {
for (auto arc_cost : net) {
cost += arc_cost;
}
}
return cost;
}
// Cost-change-related data for a move
struct MoveChangeData
{
enum BoundChangeType
{
NO_CHANGE,
CELL_MOVED_INWARDS,
CELL_MOVED_OUTWARDS,
FULL_RECOMPUTE
};
std::vector<decltype(NetInfo::udata)> bounds_changed_nets_x, bounds_changed_nets_y;
std::vector<std::pair<decltype(NetInfo::udata), size_t>> changed_arcs;
std::vector<BoundChangeType> already_bounds_changed_x, already_bounds_changed_y;
std::vector<std::vector<bool>> already_changed_arcs;
std::vector<BoundingBox> new_net_bounds;
std::vector<std::pair<std::pair<decltype(NetInfo::udata), size_t>, double>> new_arc_costs;
wirelen_t wirelen_delta = 0;
double timing_delta = 0;
void init(SAPlacer *p)
{
already_bounds_changed_x.resize(p->ctx->nets.size());
already_bounds_changed_y.resize(p->ctx->nets.size());
already_changed_arcs.resize(p->ctx->nets.size());
for (auto &net : p->ctx->nets) {
already_changed_arcs.at(net.second->udata).resize(net.second->users.size());
}
new_net_bounds = p->net_bounds;
}
void reset(SAPlacer *p)
{
for (auto bc : bounds_changed_nets_x) {
new_net_bounds[bc] = p->net_bounds[bc];
already_bounds_changed_x[bc] = NO_CHANGE;
}
for (auto bc : bounds_changed_nets_y) {
new_net_bounds[bc] = p->net_bounds[bc];
already_bounds_changed_y[bc] = NO_CHANGE;
}
for (const auto &tc : changed_arcs)
already_changed_arcs[tc.first][tc.second] = false;
bounds_changed_nets_x.clear();
bounds_changed_nets_y.clear();
changed_arcs.clear();
new_arc_costs.clear();
wirelen_delta = 0;
timing_delta = 0;
}
} moveChange;
void add_move_cell(MoveChangeData &mc, CellInfo *cell, BelId old_bel)
{
Loc curr_loc = ctx->getBelLocation(cell->bel);
Loc old_loc = ctx->getBelLocation(old_bel);
// Check net bounds
for (const auto &port : cell->ports) {
NetInfo *pn = port.second.net;
if (pn == nullptr)
continue;
if (ignore_net(pn))
continue;
BoundingBox &curr_bounds = mc.new_net_bounds[pn->udata];
// Incremental bounding box updates
// Note that everything other than full updates are applied immediately rather than being queued,
// so further updates to the same net in the same move are dealt with correctly.
// If a full update is already queued, this can be considered a no-op
if (mc.already_bounds_changed_x[pn->udata] != MoveChangeData::FULL_RECOMPUTE) {
// Bounds x0
if (curr_loc.x < curr_bounds.x0) {
// Further out than current bounds x0
curr_bounds.x0 = curr_loc.x;
curr_bounds.nx0 = 1;
if (mc.already_bounds_changed_x[pn->udata] == MoveChangeData::NO_CHANGE) {
// Checking already_bounds_changed_x ensures that each net is only added once
// to bounds_changed_nets, lest we add its HPWL change multiple times skewing the
// overall cost change
mc.already_bounds_changed_x[pn->udata] = MoveChangeData::CELL_MOVED_OUTWARDS;
mc.bounds_changed_nets_x.push_back(pn->udata);
}
} else if (curr_loc.x == curr_bounds.x0 && old_loc.x > curr_bounds.x0) {
curr_bounds.nx0++;
if (mc.already_bounds_changed_x[pn->udata] == MoveChangeData::NO_CHANGE) {
mc.already_bounds_changed_x[pn->udata] = MoveChangeData::CELL_MOVED_OUTWARDS;
mc.bounds_changed_nets_x.push_back(pn->udata);
}
} else if (old_loc.x == curr_bounds.x0 && curr_loc.x > curr_bounds.x0) {
if (mc.already_bounds_changed_x[pn->udata] == MoveChangeData::NO_CHANGE)
mc.bounds_changed_nets_x.push_back(pn->udata);
if (curr_bounds.nx0 == 1) {
mc.already_bounds_changed_x[pn->udata] = MoveChangeData::FULL_RECOMPUTE;
} else {
curr_bounds.nx0--;
if (mc.already_bounds_changed_x[pn->udata] == MoveChangeData::NO_CHANGE)
mc.already_bounds_changed_x[pn->udata] = MoveChangeData::CELL_MOVED_INWARDS;
}
}
// Bounds x1
if (curr_loc.x > curr_bounds.x1) {
// Further out than current bounds x1
curr_bounds.x1 = curr_loc.x;
curr_bounds.nx1 = 1;
if (mc.already_bounds_changed_x[pn->udata] == MoveChangeData::NO_CHANGE) {
// Checking already_bounds_changed_x ensures that each net is only added once
// to bounds_changed_nets, lest we add its HPWL change multiple times skewing the
// overall cost change
mc.already_bounds_changed_x[pn->udata] = MoveChangeData::CELL_MOVED_OUTWARDS;
mc.bounds_changed_nets_x.push_back(pn->udata);
}
} else if (curr_loc.x == curr_bounds.x1 && old_loc.x < curr_bounds.x1) {
curr_bounds.nx1++;
if (mc.already_bounds_changed_x[pn->udata] == MoveChangeData::NO_CHANGE) {
mc.already_bounds_changed_x[pn->udata] = MoveChangeData::CELL_MOVED_OUTWARDS;
mc.bounds_changed_nets_x.push_back(pn->udata);
}
} else if (old_loc.x == curr_bounds.x1 && curr_loc.x < curr_bounds.x1) {
if (mc.already_bounds_changed_x[pn->udata] == MoveChangeData::NO_CHANGE)
mc.bounds_changed_nets_x.push_back(pn->udata);
if (curr_bounds.nx1 == 1) {
mc.already_bounds_changed_x[pn->udata] = MoveChangeData::FULL_RECOMPUTE;
} else {
curr_bounds.nx1--;
if (mc.already_bounds_changed_x[pn->udata] == MoveChangeData::NO_CHANGE)
mc.already_bounds_changed_x[pn->udata] = MoveChangeData::CELL_MOVED_INWARDS;
}
}
}
if (mc.already_bounds_changed_y[pn->udata] != MoveChangeData::FULL_RECOMPUTE) {
// Bounds y0
if (curr_loc.y < curr_bounds.y0) {
// Further out than current bounds y0
curr_bounds.y0 = curr_loc.y;
curr_bounds.ny0 = 1;
if (mc.already_bounds_changed_y[pn->udata] == MoveChangeData::NO_CHANGE) {
mc.already_bounds_changed_y[pn->udata] = MoveChangeData::CELL_MOVED_OUTWARDS;
mc.bounds_changed_nets_y.push_back(pn->udata);
}
} else if (curr_loc.y == curr_bounds.y0 && old_loc.y > curr_bounds.y0) {
curr_bounds.ny0++;
if (mc.already_bounds_changed_y[pn->udata] == MoveChangeData::NO_CHANGE) {
mc.already_bounds_changed_y[pn->udata] = MoveChangeData::CELL_MOVED_OUTWARDS;
mc.bounds_changed_nets_y.push_back(pn->udata);
}
} else if (old_loc.y == curr_bounds.y0 && curr_loc.y > curr_bounds.y0) {
if (mc.already_bounds_changed_y[pn->udata] == MoveChangeData::NO_CHANGE)
mc.bounds_changed_nets_y.push_back(pn->udata);
if (curr_bounds.ny0 == 1) {
mc.already_bounds_changed_y[pn->udata] = MoveChangeData::FULL_RECOMPUTE;
} else {
curr_bounds.ny0--;
if (mc.already_bounds_changed_y[pn->udata] == MoveChangeData::NO_CHANGE)
mc.already_bounds_changed_y[pn->udata] = MoveChangeData::CELL_MOVED_INWARDS;
}
}
// Bounds y1
if (curr_loc.y > curr_bounds.y1) {
// Further out than current bounds y1
curr_bounds.y1 = curr_loc.y;
curr_bounds.ny1 = 1;
if (mc.already_bounds_changed_y[pn->udata] == MoveChangeData::NO_CHANGE) {
mc.already_bounds_changed_y[pn->udata] = MoveChangeData::CELL_MOVED_OUTWARDS;
mc.bounds_changed_nets_y.push_back(pn->udata);
}
} else if (curr_loc.y == curr_bounds.y1 && old_loc.y < curr_bounds.y1) {
curr_bounds.ny1++;
if (mc.already_bounds_changed_y[pn->udata] == MoveChangeData::NO_CHANGE) {
mc.already_bounds_changed_y[pn->udata] = MoveChangeData::CELL_MOVED_OUTWARDS;
mc.bounds_changed_nets_y.push_back(pn->udata);
}
} else if (old_loc.y == curr_bounds.y1 && curr_loc.y < curr_bounds.y1) {
if (mc.already_bounds_changed_y[pn->udata] == MoveChangeData::NO_CHANGE)
mc.bounds_changed_nets_y.push_back(pn->udata);
if (curr_bounds.ny1 == 1) {
mc.already_bounds_changed_y[pn->udata] = MoveChangeData::FULL_RECOMPUTE;
} else {
curr_bounds.ny1--;
if (mc.already_bounds_changed_y[pn->udata] == MoveChangeData::NO_CHANGE)
mc.already_bounds_changed_y[pn->udata] = MoveChangeData::CELL_MOVED_INWARDS;
}
}
}
if (cfg.timing_driven && int(pn->users.size()) < cfg.timingFanoutThresh) {
// Output ports - all arcs change timing
if (port.second.type == PORT_OUT) {
int cc;
TimingPortClass cls = ctx->getPortTimingClass(cell, port.first, cc);
if (cls != TMG_IGNORE)
for (size_t i = 0; i < pn->users.size(); i++)
if (!mc.already_changed_arcs[pn->udata][i]) {
mc.changed_arcs.emplace_back(std::make_pair(pn->udata, i));
mc.already_changed_arcs[pn->udata][i] = true;
}
} else if (port.second.type == PORT_IN) {
auto usr = fast_port_to_user.at(&port.second);
if (!mc.already_changed_arcs[pn->udata][usr]) {
mc.changed_arcs.emplace_back(std::make_pair(pn->udata, usr));
mc.already_changed_arcs[pn->udata][usr] = true;
}
}
}
}
}
void compute_cost_changes(MoveChangeData &md)
{
for (const auto &bc : md.bounds_changed_nets_x) {
if (md.already_bounds_changed_x[bc] == MoveChangeData::FULL_RECOMPUTE)
md.new_net_bounds[bc] = get_net_bounds(net_by_udata[bc]);
}
for (const auto &bc : md.bounds_changed_nets_y) {
if (md.already_bounds_changed_x[bc] != MoveChangeData::FULL_RECOMPUTE &&
md.already_bounds_changed_y[bc] == MoveChangeData::FULL_RECOMPUTE)
md.new_net_bounds[bc] = get_net_bounds(net_by_udata[bc]);
}
for (const auto &bc : md.bounds_changed_nets_x)
md.wirelen_delta += md.new_net_bounds[bc].hpwl(cfg) - net_bounds[bc].hpwl(cfg);
for (const auto &bc : md.bounds_changed_nets_y)
if (md.already_bounds_changed_x[bc] == MoveChangeData::NO_CHANGE)
md.wirelen_delta += md.new_net_bounds[bc].hpwl(cfg) - net_bounds[bc].hpwl(cfg);
if (cfg.timing_driven) {
for (const auto &tc : md.changed_arcs) {
double old_cost = net_arc_tcost.at(tc.first).at(tc.second);
double new_cost = get_timing_cost(net_by_udata.at(tc.first), tc.second);
md.new_arc_costs.emplace_back(std::make_pair(tc, new_cost));
md.timing_delta += (new_cost - old_cost);
md.already_changed_arcs[tc.first][tc.second] = false;
}
}
}
void commit_cost_changes(MoveChangeData &md)
{
for (const auto &bc : md.bounds_changed_nets_x)
net_bounds[bc] = md.new_net_bounds[bc];
for (const auto &bc : md.bounds_changed_nets_y)
net_bounds[bc] = md.new_net_bounds[bc];
for (const auto &tc : md.new_arc_costs)
net_arc_tcost[tc.first.first].at(tc.first.second) = tc.second;
curr_wirelen_cost += md.wirelen_delta;
curr_timing_cost += md.timing_delta;
}
// Build the cell port -> user index
void build_port_index()
{
for (auto net : sorted(ctx->nets)) {
NetInfo *ni = net.second;
for (size_t i = 0; i < ni->users.size(); i++) {
auto &usr = ni->users.at(i);
fast_port_to_user[&(usr.cell->ports.at(usr.port))] = i;
}
}
}
// Simple routeability driven placement
const int large_cell_thresh = 50;
int total_net_share = 0;
std::vector<std::vector<std::unordered_map<IdString, int>>> nets_by_tile;
void setup_nets_by_tile()
{
total_net_share = 0;
nets_by_tile.resize(max_x + 1, std::vector<std::unordered_map<IdString, int>>(max_y + 1));
for (auto cell : sorted(ctx->cells)) {
CellInfo *ci = cell.second;
if (int(ci->ports.size()) > large_cell_thresh)
continue;
Loc loc = ctx->getBelLocation(ci->bel);
auto &nbt = nets_by_tile.at(loc.x).at(loc.y);
for (const auto &port : ci->ports) {
if (port.second.net == nullptr)
continue;
if (port.second.net->driver.cell == nullptr || ctx->getBelGlobalBuf(port.second.net->driver.cell->bel))
continue;
int &s = nbt[port.second.net->name];
if (s > 0)
++total_net_share;
++s;
}
}
}
int update_nets_by_tile(CellInfo *ci, Loc old_loc, Loc new_loc)
{
if (int(ci->ports.size()) > large_cell_thresh)
return 0;
int loss = 0, gain = 0;
auto &nbt_old = nets_by_tile.at(old_loc.x).at(old_loc.y);
auto &nbt_new = nets_by_tile.at(new_loc.x).at(new_loc.y);
for (const auto &port : ci->ports) {
if (port.second.net == nullptr)
continue;
if (port.second.net->driver.cell == nullptr || ctx->getBelGlobalBuf(port.second.net->driver.cell->bel))
continue;
int &o = nbt_old[port.second.net->name];
--o;
NPNR_ASSERT(o >= 0);
if (o > 0)
++loss;
int &n = nbt_new[port.second.net->name];
if (n > 0)
++gain;
++n;
}
int delta = gain - loss;
total_net_share += delta;
return delta;
}
// Get the combined wirelen/timing metric
inline double curr_metric()
{
return lambda * curr_timing_cost + (1 - lambda) * curr_wirelen_cost - cfg.netShareWeight * total_net_share;
}
// Map nets to their bounding box (so we can skip recompute for moves that do not exceed the bounds
std::vector<BoundingBox> net_bounds;
// Map net arcs to their timing cost (criticality * delay ns)
std::vector<std::vector<double>> net_arc_tcost;
// Fast lookup for cell port to net user index
std::unordered_map<const PortInfo *, size_t> fast_port_to_user;
// Wirelength and timing cost at last and current iteration
wirelen_t last_wirelen_cost, curr_wirelen_cost;
double last_timing_cost, curr_timing_cost;
// Criticality data from timing analysis
NetCriticalityMap net_crit;
Context *ctx;
float temp = 10;
float crit_exp = 8;
float lambda = 0.5;
bool improved = false;
int n_move, n_accept;
int diameter = 35, max_x = 1, max_y = 1;
std::unordered_map<IdString, std::tuple<int, int>> bel_types;
std::unordered_map<IdString, BoundingBox> region_bounds;
FastBels fast_bels;
std::unordered_set<BelId> locked_bels;
std::vector<NetInfo *> net_by_udata;
std::vector<decltype(NetInfo::udata)> old_udata;
bool require_legal = true;
const int legalise_dia = 4;
Placer1Cfg cfg;
};
Placer1Cfg::Placer1Cfg(Context *ctx)
{
constraintWeight = ctx->setting<float>("placer1/constraintWeight", 10);
netShareWeight = ctx->setting<float>("placer1/netShareWeight", 0);
minBelsForGridPick = ctx->setting<int>("placer1/minBelsForGridPick", 64);
budgetBased = ctx->setting<bool>("placer1/budgetBased", false);
startTemp = ctx->setting<float>("placer1/startTemp", 1);
timingFanoutThresh = std::numeric_limits<int>::max();
timing_driven = ctx->setting<bool>("timing_driven");
slack_redist_iter = ctx->setting<int>("slack_redist_iter");
hpwl_scale_x = 1;
hpwl_scale_y = 1;
}
bool placer1(Context *ctx, Placer1Cfg cfg)
{
try {
SAPlacer placer(ctx, cfg);
placer.place();
log_info("Checksum: 0x%08x\n", ctx->checksum());
#ifndef NDEBUG
ctx->lock();
ctx->check();
ctx->unlock();
#endif
return true;
} catch (log_execution_error_exception) {
#ifndef NDEBUG
ctx->check();
#endif
ctx->unlock();
return false;
}
}
bool placer1_refine(Context *ctx, Placer1Cfg cfg)
{
try {
SAPlacer placer(ctx, cfg);
placer.place(true);
log_info("Checksum: 0x%08x\n", ctx->checksum());
#ifndef NDEBUG
ctx->lock();
ctx->check();
ctx->unlock();
#endif
return true;
} catch (log_execution_error_exception) {
#ifndef NDEBUG
ctx->check();
#endif
ctx->unlock();
return false;
}
}
NEXTPNR_NAMESPACE_END