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Fix false assertion failure on failed Dfg driver tracing (#6459)

This commit is contained in:
Geza Lore 2025-09-19 14:31:07 +02:00 committed by GitHub
parent c1ac2a79db
commit e24f84f713
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1 changed files with 15 additions and 10 deletions
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25
src/V3DfgBreakCycles.cpp
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@ -176,45 +176,50 @@ class TraceDriver final : public DfgVisitor {
// Trace the vertex
onStackr = true;
// The resulting driver that is not part of m_component
DfgVertex* resp = nullptr;
// If the currently traced vertex is in a different component,
// then we found what we were looking for.
if (m_vtx2Scc[vtxp] != m_component) {
m_resp = vtxp;
resp = vtxp;
// If the result is a splice, we need to insert a temporary for it
// as a splice cannot be fed into arbitray logic
if (DfgVertexSplice* const splicep = m_resp->cast<DfgVertexSplice>()) {
if (DfgVertexSplice* const splicep = resp->cast<DfgVertexSplice>()) {
DfgVertexVar* const tmpp = createTmp("TraceDriver", splicep);
splicep->replaceWith(tmpp);
tmpp->srcp(splicep);
m_resp = tmpp;
resp = tmpp;
}
// Apply a Sel to extract the relevant bits if only a part is needed
if (msb != m_resp->width() - 1 || lsb != 0) {
DfgSel* const selp = make<DfgSel>(m_resp, msb - lsb + 1);
selp->fromp(m_resp);
if (msb != resp->width() - 1 || lsb != 0) {
DfgSel* const selp = make<DfgSel>(resp, msb - lsb + 1);
selp->fromp(resp);
selp->lsb(lsb);
m_resp = selp;
resp = selp;
}
} else {
// Otherwise visit the vertex
VL_RESTORER(m_msb);
VL_RESTORER(m_lsb);
VL_RESTORER(m_resp);
m_msb = msb;
m_lsb = lsb;
m_resp = nullptr;
iterate(vtxp);
resp = m_resp;
}
UASSERT_OBJ(!m_resp || m_resp->width() == (msb - lsb + 1), vtxp, "Wrong result width");
UASSERT_OBJ(!resp || resp->width() == (msb - lsb + 1), vtxp, "Wrong result width");
// Pop from stack
onStackr = false;
m_stack.pop_back();
// Done
if (!m_resp) {
if (!resp) {
UINFO(9, "TraceDriver - Failed to trace vertex of type: " << vtxp->typeName());
}
return m_resp;
return resp;
}
template <typename Vertex>