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drt/odb: fix non-determinism on pin access #10085

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Merged
eder-matheus merged 5 commits into from
Apr 11, 2026
+15 −4
Merged

drt/odb: fix non-determinism on pin access #10085

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5cb7027
drt: add custom comparator for dirty_unique_classes
eder-matheus Apr 8, 2026
f98e2c9
odb: sort iterms inside dbAccessPoint for deterministic serialization
eder-matheus Apr 8, 2026
a38bf6c
odb: remove iterm from access point terms list
eder-matheus Apr 8, 2026
7a67a57
maintain sorted AP iterms_ to ensure deterministic serialization
eder-matheus Apr 8, 2026
084c2ea
Merge branch 'master' of https://github.com/The-OpenROAD-Project/Open…
eder-matheus Apr 10, 2026
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3 changes: 2 additions & 1 deletion src/drt/src/pa/FlexPA.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -121,7 +121,8 @@ void FlexPA::removeDirtyInst(frInst* inst)

void FlexPA::updateDirtyInsts()
{
std::set<UniqueClass*> dirty_unique_classes;
auto cmp = [](UniqueClass* a, UniqueClass* b) { return a->key() < b->key(); };
std::set<UniqueClass*, decltype(cmp)> dirty_unique_classes(cmp);
frOrderedIdSet<frInst*>
pattern_insts; // list of insts that need row pattern generation
for (const auto& inst : dirty_insts_) {
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16 changes: 13 additions & 3 deletions src/odb/src/db/dbITerm.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -801,7 +801,9 @@ void dbITerm::setAccessPoint(dbMPin* pin, dbAccessPoint* ap)
if (ap != nullptr) {
iterm->aps_[pin->getImpl()->getOID()] = ap->getImpl()->getOID();
_dbAccessPoint* _ap = (_dbAccessPoint*) ap;
_ap->iterms_.push_back(iterm->getOID());
auto& iterms = _ap->iterms_;
auto pos = std::lower_bound(iterms.begin(), iterms.end(), iterm->getOID());
iterms.insert(pos, iterm->getOID());
Comment on lines +804 to +806
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@osamahammad21 osamahammad21 Apr 9, 2026

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Does this relate to non-determinism? I don’t see how preserving insertion order would introduce non-deterministic behavior.

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@eder-matheus eder-matheus Apr 9, 2026

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It doesn't impact the final result in terms of routing (wire and via location, wire count, etc) but it can impact the final ODB. In the issue, the main concern was different sha1 between the ODBs generated on different runs that must produce the same output. This change in dbITerm ensures that the ODB files will be consistent.

} else {
iterm->aps_[pin->getImpl()->getOID()] = dbId<_dbAccessPoint>();
}
Expand Down Expand Up @@ -861,8 +863,16 @@ std::vector<dbAccessPoint*> dbITerm::getPrefAccessPoints() const
void dbITerm::clearPrefAccessPoints()
{
_dbITerm* iterm = (_dbITerm*) this;
// Clear aps_ map instead of destroying dbAccessPoint object to prevent
// destroying APs of other iterms.
_dbBlock* block = (_dbBlock*) iterm->getOwner();
// Remove this iterm from each AP's back-reference list before clearing.
for (auto& [pin_id, ap_id] : iterm->aps_) {
if (ap_id.isValid()) {
auto* ap = block->ap_tbl_->getPtr(ap_id);
auto& iterms = ap->iterms_;
iterms.erase(std::remove(iterms.begin(), iterms.end(), iterm->getOID()),
iterms.end());
}
}
iterm->aps_.clear();
}

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