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Fix soft constraint relaxation dropping compatible constraints (#7271)

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* Fix soft constraint relaxation dropping compatible constraints

* patch changes the soft handle ordering so update the out files
This commit is contained in:
Yilou Wang
2026-03-18 10:15:50 +01:00
committed by GitHub
parent 612d1611b6
commit 4b34bfffcb
6 changed files with 102 additions and 13 deletions
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include/verilated_random.cpp
+35 -9
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@@ -468,16 +468,36 @@ bool VlRandomizer::next(VlRNG& rngr) {
const size_t nSoft = m_softConstraints.size();
bool sat = false;
for (size_t phase = 0; phase <= nSoft && !sat; ++phase) {
const bool hasSoft = (phase < nSoft);
if (hasSoft) {
os << "(push 1)\n";
for (size_t i = phase; i < nSoft; ++i)
os << "(assert (= #b1 " << m_softConstraints[i] << "))\n";
}
if (nSoft > 0) {
// Fast path: try all soft constraints at once
os << "(push 1)\n";
for (const auto& s : m_softConstraints) os << "(assert (= #b1 " << s << "))\n";
os << "(check-sat)\n";
sat = parseSolution(os, /*log=*/phase == nSoft);
if (!sat && hasSoft) os << "(pop 1)\n";
sat = parseSolution(os, false);
if (!sat) {
// Some soft constraints conflict. Incrementally add from back
// (highest priority first), keeping only compatible ones.
// This preserves the maximum set of compatible soft constraints.
os << "(pop 1)\n";
for (int i = static_cast<int>(nSoft) - 1; i >= 0; --i) {
os << "(push 1)\n";
os << "(assert (= #b1 " << m_softConstraints[i] << "))\n";
os << "(check-sat)\n";
if (checkSat(os)) {
// Compatible -- keep this push level
} else {
// Incompatible -- remove this soft constraint
os << "(pop 1)\n";
}
}
// Read solution with remaining compatible soft constraints
os << "(check-sat)\n";
sat = parseSolution(os, false);
}
} else {
// No soft constraints -- hard-only
os << "(check-sat)\n";
sat = parseSolution(os, false);
}
if (!sat) {
@@ -530,6 +550,12 @@ bool VlRandomizer::next(VlRNG& rngr) {
return false; // Should not reach here
}
bool VlRandomizer::checkSat(std::iostream& os) {
std::string result;
do { std::getline(os, result); } while (result.empty());
return result == "sat";
}
bool VlRandomizer::parseSolution(std::iostream& os, bool log) {
std::string sat;
do { std::getline(os, sat); } while (sat == "");