OpenSTA/search/Bfs.cc

699 lines
19 KiB
C++

// OpenSTA, Static Timing Analyzer
// Copyright (c) 2026, Parallax Software, Inc.
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program. If not, see <https://www.gnu.org/licenses/>.
//
// The origin of this software must not be misrepresented; you must not
// claim that you wrote the original software.
//
// Altered source versions must be plainly marked as such, and must not be
// misrepresented as being the original software.
//
// This notice may not be removed or altered from any source distribution.
#include "Bfs.hh"
#include <set>
#include <iostream>
#include "Report.hh"
#include "Debug.hh"
#include "Mutex.hh"
#include "DispatchQueue.hh"
#include "Network.hh"
#include "Graph.hh"
#include "Sdc.hh"
#include "Levelize.hh"
#include "SearchPred.hh"
namespace sta {
BfsIterator::BfsIterator(BfsIndex bfs_index,
Level level_min,
Level level_max,
SearchPred *search_pred,
StaState *sta) :
StaState(sta),
bfs_index_(bfs_index),
level_min_(level_min),
level_max_(level_max),
search_pred_(search_pred)
{
init();
}
void
BfsIterator::init()
{
first_level_ = level_max_;
last_level_ = level_min_;
ensureSize();
}
void
BfsIterator::ensureSize()
{
if (levelize_->levelized()) {
unsigned max_level_1 = levelize_->maxLevel() + 1;
if (queue_.size() < max_level_1)
queue_.resize(max_level_1);
}
}
BfsIterator::~BfsIterator() {}
void
BfsIterator::clear()
{
Level level = first_level_;
while (levelLessOrEqual(level, last_level_)) {
VertexSeq &level_vertices = queue_[level];
for (Vertex *vertex : level_vertices) {
if (vertex)
vertex->setBfsInQueue(bfs_index_, false);
}
level_vertices.clear();
incrLevel(level);
}
init();
}
void
BfsIterator::reportEntries() const
{
for (Level level = first_level_; levelLessOrEqual(level, last_level_);
incrLevel(level)) {
const VertexSeq &level_vertices = queue_[level];
if (!level_vertices.empty()) {
report_->report("Level {}", level);
for (Vertex *vertex : level_vertices)
report_->report(" {}", vertex ? vertex->to_string(this) : "NULL");
}
}
}
void
BfsIterator::deleteEntries(Level level)
{
VertexSeq &level_vertices = queue_[level];
for (Vertex *vertex : level_vertices) {
if (vertex)
vertex->setBfsInQueue(bfs_index_, false);
}
level_vertices.clear();
}
bool
BfsIterator::empty() const
{
return levelLess(last_level_, first_level_);
}
void
BfsIterator::enqueueAdjacentVertices(Vertex *vertex)
{
enqueueAdjacentVertices(vertex, search_pred_);
}
void
BfsIterator::enqueueAdjacentVertices(Vertex *vertex,
const Mode *mode)
{
enqueueAdjacentVertices(vertex, search_pred_, mode);
}
int
BfsIterator::visit(Level to_level,
VertexVisitor *visitor)
{
int visit_count = 0;
while (levelLessOrEqual(first_level_, last_level_)
&& levelLessOrEqual(first_level_, to_level)) {
Level level = first_level_;
VertexSeq &level_vertices = queue_[level];
incrLevel(first_level_);
// Note that ArrivalVisitor::enqueueRefPinInputDelays may enqueue
// vertices at this level so range iteration fails if the vector grows.
while (!level_vertices.empty()) {
Vertex *vertex = level_vertices.back();
level_vertices.pop_back();
if (vertex) {
checkLevel(vertex, level);
vertex->setBfsInQueue(bfs_index_, false);
visitor->visit(vertex);
visit_count++;
}
}
level_vertices.clear();
visitor->levelFinished();
}
return visit_count;
}
int
BfsIterator::visitParallel(Level to_level,
VertexVisitor *visitor)
{
size_t thread_count = thread_count_;
int visit_count = 0;
if (!empty()) {
if (thread_count == 1)
visit_count = visit(to_level, visitor);
else {
std::vector<VertexVisitor *> visitors;
for (int k = 0; k < thread_count_; k++)
visitors.push_back(visitor->copy());
while (levelLessOrEqual(first_level_, last_level_)
&& levelLessOrEqual(first_level_, to_level)) {
VertexSeq &level_vertices = queue_[first_level_];
Level level = first_level_;
incrLevel(first_level_);
if (!level_vertices.empty()) {
size_t vertex_count = level_vertices.size();
if (vertex_count < thread_count) {
for (Vertex *vertex : level_vertices) {
if (vertex) {
checkLevel(vertex, level);
vertex->setBfsInQueue(bfs_index_, false);
visitor->visit(vertex);
}
}
}
else {
size_t from = 0;
size_t chunk_size = vertex_count / thread_count;
BfsIndex bfs_index = bfs_index_;
for (size_t k = 0; k < thread_count; k++) {
// Last thread gets the left overs.
size_t to = (k == thread_count - 1) ? vertex_count : from + chunk_size;
dispatch_queue_->dispatch([=, this](size_t) {
for (size_t i = from; i < to; i++) {
Vertex *vertex = level_vertices[i];
if (vertex) {
checkLevel(vertex, level);
vertex->setBfsInQueue(bfs_index, false);
visitors[k]->visit(vertex);
}
}
});
from = to;
}
dispatch_queue_->finishTasks();
}
visitor->levelFinished();
level_vertices.clear();
visit_count += vertex_count;
}
}
for (VertexVisitor *visitor : visitors)
delete visitor;
}
}
return visit_count;
}
bool
BfsIterator::hasNext()
{
return hasNext(last_level_);
}
bool
BfsIterator::hasNext(Level to_level)
{
findNext(to_level);
return levelLessOrEqual(first_level_, last_level_)
&& !queue_[first_level_].empty();
}
Vertex *
BfsIterator::next()
{
VertexSeq &level_vertices = queue_[first_level_];
Vertex *vertex = level_vertices.back();
level_vertices.pop_back();
vertex->setBfsInQueue(bfs_index_, false);
return vertex;
}
void
BfsIterator::findNext(Level to_level)
{
while (levelLessOrEqual(first_level_, last_level_)
&& levelLessOrEqual(first_level_, to_level)) {
VertexSeq &level_vertices = queue_[first_level_];
// Skip null entries from deleted vertices.
while (!level_vertices.empty()) {
Vertex *vertex = level_vertices.back();
if (vertex == nullptr)
level_vertices.pop_back();
else {
checkLevel(vertex, first_level_);
return;
}
}
incrLevel(first_level_);
}
}
void
BfsIterator::enqueue(Vertex *vertex)
{
debugPrint(debug_, "bfs", 2, "enqueue {}", vertex->to_string(this));
if (!vertex->bfsInQueue(bfs_index_)) {
Level level = vertex->level();
LockGuard lock(queue_lock_);
if (!vertex->bfsInQueue(bfs_index_)) {
vertex->setBfsInQueue(bfs_index_, true);
queue_[level].push_back(vertex);
if (levelLess(last_level_, level))
last_level_ = level;
if (levelLess(level, first_level_))
first_level_ = level;
}
}
}
bool
BfsIterator::inQueue(Vertex *vertex)
{
// checkInQueue(vertex);
return vertex->bfsInQueue(bfs_index_);
}
void
BfsIterator::checkInQueue(Vertex *vertex)
{
Level level = vertex->level();
if (static_cast<Level>(queue_.size()) > level) {
for (Vertex *v : queue_[level]) {
if (v == vertex) {
if (vertex->bfsInQueue(bfs_index_))
return;
else
debugPrint(debug_, "bfs", 1, "extra {}", vertex->to_string(this));
}
}
}
if (vertex->bfsInQueue(bfs_index_))
debugPrint(debug_, "brs", 1, "missing {}", vertex->to_string(this));
}
void
BfsIterator::checkLevel(Vertex *vertex,
Level level)
{
if (vertex->level() != level)
report_->error(2300, "vertex {} level {} != bfs level {}",
vertex->to_string(this), vertex->level(), level);
}
void
BfsIterator::deleteVertexBefore(Vertex *vertex)
{
remove(vertex);
}
// Remove by inserting null vertex pointer.
void
BfsIterator::remove(Vertex *vertex)
{
// If the iterator has not been inited the queue will be empty.
Level level = vertex->level();
if (vertex->bfsInQueue(bfs_index_) && static_cast<Level>(queue_.size()) > level) {
debugPrint(debug_, "bfs", 2, "remove {}", vertex->to_string(this));
for (Vertex *&v : queue_[level]) {
if (v == vertex) {
v = nullptr;
vertex->setBfsInQueue(bfs_index_, false);
break;
}
}
}
}
////////////////////////////////////////////////////////////////
BfsFwdIterator::BfsFwdIterator(BfsIndex bfs_index,
SearchPred *search_pred,
StaState *sta) :
BfsIterator(bfs_index,
0,
level_max,
search_pred,
sta)
{
}
// clear() without saving lists to list_free_.
BfsFwdIterator::~BfsFwdIterator()
{
for (Level level = first_level_; level <= last_level_; level++)
deleteEntries(level);
}
void
BfsFwdIterator::incrLevel(Level &level) const
{
level++;
}
bool
BfsFwdIterator::levelLessOrEqual(Level level1,
Level level2) const
{
return level1 <= level2;
}
bool
BfsFwdIterator::levelLess(Level level1,
Level level2) const
{
return level1 < level2;
}
void
BfsFwdIterator::enqueueAdjacentVertices(Vertex *vertex,
SearchPred *search_pred)
{
if (search_pred->searchFrom(vertex)) {
VertexOutEdgeIterator edge_iter(vertex, graph_);
while (edge_iter.hasNext()) {
Edge *edge = edge_iter.next();
Vertex *to_vertex = edge->to(graph_);
if (search_pred->searchThru(edge) && search_pred->searchTo(to_vertex))
enqueue(to_vertex);
}
}
}
void
BfsFwdIterator::enqueueAdjacentVertices(Vertex *vertex,
SearchPred *search_pred,
const Mode *mode)
{
if (search_pred->searchFrom(vertex, mode)) {
VertexOutEdgeIterator edge_iter(vertex, graph_);
while (edge_iter.hasNext()) {
Edge *edge = edge_iter.next();
Vertex *to_vertex = edge->to(graph_);
if (search_pred->searchThru(edge, mode)
&& search_pred->searchTo(to_vertex, mode))
enqueue(to_vertex);
}
}
}
////////////////////////////////////////////////////////////////
BfsBkwdIterator::BfsBkwdIterator(BfsIndex bfs_index,
SearchPred *search_pred,
StaState *sta) :
BfsIterator(bfs_index,
level_max,
0,
search_pred,
sta)
{
}
// clear() without saving lists to list_free_.
BfsBkwdIterator::~BfsBkwdIterator()
{
for (Level level = first_level_; level >= last_level_; level--)
deleteEntries(level);
}
void
BfsBkwdIterator::incrLevel(Level &level) const
{
level--;
}
bool
BfsBkwdIterator::levelLessOrEqual(Level level1,
Level level2) const
{
return level1 >= level2;
}
bool
BfsBkwdIterator::levelLess(Level level1,
Level level2) const
{
return level1 > level2;
}
void
BfsBkwdIterator::enqueueAdjacentVertices(Vertex *vertex,
SearchPred *search_pred)
{
if (search_pred->searchTo(vertex)) {
VertexInEdgeIterator edge_iter(vertex, graph_);
while (edge_iter.hasNext()) {
Edge *edge = edge_iter.next();
Vertex *from_vertex = edge->from(graph_);
if (search_pred->searchFrom(from_vertex) && search_pred->searchThru(edge))
enqueue(from_vertex);
}
}
}
void
BfsBkwdIterator::enqueueAdjacentVertices(Vertex *vertex,
SearchPred *search_pred,
const Mode *mode)
{
if (search_pred->searchTo(vertex, mode)) {
VertexInEdgeIterator edge_iter(vertex, graph_);
while (edge_iter.hasNext()) {
Edge *edge = edge_iter.next();
Vertex *from_vertex = edge->from(graph_);
if (search_pred->searchFrom(from_vertex, mode)
&& search_pred->searchThru(edge, mode))
enqueue(from_vertex);
}
}
}
thread_local int current_thread_id = 0;
BfsFwdInDegreeIterator::BfsFwdInDegreeIterator(BfsIndex bfs_index,
SearchPred *search_pred,
StaState *sta) :
StaState(sta),
bfs_index_(bfs_index),
search_pred_(search_pred)
{
}
BfsFwdInDegreeIterator::~BfsFwdInDegreeIterator()
{
}
void BfsFwdInDegreeIterator::clear()
{
in_degrees_.reset();
in_degrees_size_ = 0;
roots_.clear();
}
void BfsFwdInDegreeIterator::computeInDegrees()
{
size_t vertex_count = graph_->vertexCount();
in_degrees_ = std::make_unique<std::atomic<int>[]>(vertex_count + 1);
in_degrees_size_ = vertex_count + 1;
for (size_t i = 0; i < in_degrees_size_; i++) {
in_degrees_[i].store(0, std::memory_order_relaxed);
}
roots_.clear();
processed_edges_.clear();
VertexIterator vertex_iter(graph_);
while (vertex_iter.hasNext()) {
Vertex *vertex = vertex_iter.next();
vertex->setVisited(false);
std::set<Vertex*> counted_successors;
VertexOutEdgeIterator edge_iter(vertex, graph_);
while (edge_iter.hasNext()) {
Edge *edge = edge_iter.next();
Vertex *to_vertex = edge->to(graph_);
if (search_pred_->searchThru(edge)) {
if (counted_successors.insert(to_vertex).second) {
in_degrees_[to_vertex->objectIdx()].fetch_add(1, std::memory_order_relaxed);
}
}
}
}
VertexIterator vertex_iter2(graph_);
while (vertex_iter2.hasNext()) {
Vertex *vertex = vertex_iter2.next();
if (search_pred_->searchFrom(vertex)) {
if (in_degrees_[vertex->objectIdx()].load(std::memory_order_relaxed) == 0) {
roots_.push_back(vertex);
}
}
}
}
void BfsFwdInDegreeIterator::computeInDegrees(const VertexSet &invalid_delays)
{
// For incremental, we do a reachability pass to find the affected subgraph.
// Then we compute in-degrees within that subgraph.
// 1. Find reachable subgraph from invalid_delays.
std::set<Vertex*> reachable;
std::vector<Vertex*> work_list;
for (Vertex *v : invalid_delays) {
work_list.push_back(v);
reachable.insert(v);
}
size_t idx = 0;
while (idx < work_list.size()) {
Vertex *v = work_list[idx++];
VertexOutEdgeIterator edge_iter(v, graph_);
while (edge_iter.hasNext()) {
Edge *edge = edge_iter.next();
Vertex *to_vertex = edge->to(graph_);
if (search_pred_->searchThru(edge)) {
if (reachable.insert(to_vertex).second) {
work_list.push_back(to_vertex);
}
}
}
}
// 2. Compute in-degrees within the reachable subgraph.
size_t vertex_count = graph_->vertexCount();
in_degrees_ = std::make_unique<std::atomic<int>[]>(vertex_count + 1);
in_degrees_size_ = vertex_count + 1;
for (size_t i = 0; i < in_degrees_size_; i++) {
in_degrees_[i].store(0, std::memory_order_relaxed);
}
roots_.clear();
for (Vertex *v : reachable) {
VertexOutEdgeIterator edge_iter(v, graph_);
while (edge_iter.hasNext()) {
Edge *edge = edge_iter.next();
Vertex *to_vertex = edge->to(graph_);
if (search_pred_->searchThru(edge)) {
if (reachable.count(to_vertex)) {
in_degrees_[to_vertex->objectIdx()].fetch_add(1, std::memory_order_relaxed);
}
}
}
}
// 3. Find roots within the reachable subgraph.
for (Vertex *v : reachable) {
if (in_degrees_[v->objectIdx()].load(std::memory_order_relaxed) == 0) {
roots_.push_back(v);
}
}
}
void BfsFwdInDegreeIterator::enqueue(Vertex *vertex)
{
visitors_[current_thread_id]->visit(vertex);
visit_count_->fetch_add(1, std::memory_order_relaxed);
enqueueAdjacentVertices(vertex);
}
void BfsFwdInDegreeIterator::enqueueAdjacentVertices(Vertex *vertex)
{
VertexOutEdgeIterator edge_iter(vertex, graph_);
while (edge_iter.hasNext()) {
Edge *edge = edge_iter.next();
Vertex *to_vertex = edge->to(graph_);
if (search_pred_->searchThru(edge)) {
if (!to_vertex->visited()) {
bool inserted = false;
{
std::lock_guard<std::mutex> lock(mutex_);
inserted = processed_edges_.insert(edge).second;
}
if (inserted) {
int old_deg = in_degrees_[to_vertex->objectIdx()].fetch_sub(1, std::memory_order_acq_rel);
if (old_deg == 1) {
to_vertex->setVisited(true);
if (dispatch_queue_) {
dispatch_queue_->dispatch([this, to_vertex](size_t tid) {
current_thread_id = tid;
visitors_[tid]->visit(to_vertex);
visit_count_->fetch_add(1, std::memory_order_relaxed);
enqueueAdjacentVertices(to_vertex);
});
} else {
current_thread_id = 0;
visitors_[0]->visit(to_vertex);
visit_count_->fetch_add(1, std::memory_order_relaxed);
enqueueAdjacentVertices(to_vertex);
}
}
}
}
}
}
}
int BfsFwdInDegreeIterator::visitParallel(Level to_level, VertexVisitor *visitor)
{
size_t thread_count = dispatch_queue_ ? dispatch_queue_->getThreadCount() : 1;
visitors_.clear();
if (dispatch_queue_) {
for (size_t k = 0; k < thread_count; k++)
visitors_.push_back(visitor->copy());
} else {
visitors_.push_back(visitor);
}
std::atomic<int> visit_count(0);
visit_count_ = &visit_count;
for (Vertex *root : roots_) {
if (dispatch_queue_) {
dispatch_queue_->dispatch([this, root](size_t tid) {
current_thread_id = tid;
visitors_[tid]->visit(root);
visit_count_->fetch_add(1, std::memory_order_relaxed);
enqueueAdjacentVertices(root);
});
} else {
current_thread_id = 0;
visitors_[0]->visit(root);
visit_count_->fetch_add(1, std::memory_order_relaxed);
enqueueAdjacentVertices(root);
}
}
if (dispatch_queue_)
dispatch_queue_->finishTasks();
if (dispatch_queue_) {
for (VertexVisitor *v : visitors_)
delete v;
}
visitors_.clear();
return visit_count.load(std::memory_order_relaxed);
}
} // namespace sta