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Fix nonblocking event trigger never firing in suspendable processes (#8485)

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This commit is contained in:
Marco Bartoli
2026-09-29 16:48:09 -04:00
committed by GitHub
parent 21bae44b03
commit 68439fbb72
7 changed files with 293 additions and 12 deletions
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src/V3Delayed.cpp
+38 -12
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@@ -300,6 +300,7 @@ class DelayedVisitor final : public VNVisitor {
bool m_ignoreBlkAndNBlk = false; // Suppress delayed assignment BLKANDNBLK
bool m_inNonCombLogic = false; // We are in non-combinational logic
bool m_needsInitialTrigger = false; // Whether a NodeProcedure needs a initial trigger
std::vector<AstSenTree*> m_nbaEventSenTreeps; // Sensitivities of '->>' in the process
AstVarRef* m_currNbaLhsRefp = nullptr; // Current NBA LHS variable reference
// STATE - during NBA conversion (after visit)
@@ -1190,6 +1191,7 @@ class DelayedVisitor final : public VNVisitor {
}
void visit(AstNodeProcedure* nodep) override {
VL_RESTORER(m_needsInitialTrigger);
VL_RESTORER_CLEAR(m_nbaEventSenTreeps);
const size_t firstNBAAddedIndex = m_nbas.size();
{
VL_RESTORER(m_inSuspendableOrFork);
@@ -1241,6 +1243,8 @@ class DelayedVisitor final : public VNVisitor {
for (size_t i = firstNBAAddedIndex; i < m_nbas.size(); ++i) {
m_vscpInfo(m_nbas[i].vscp).addSensitivity(senItemp);
}
for (AstSenTree* const senTreep : m_nbaEventSenTreeps)
senTreep->addSensesp(senItemp->cloneTree(true));
// Done with these
VL_DO_DANGLING(senItemp->deleteTree(), senItemp);
}
@@ -1266,8 +1270,15 @@ class DelayedVisitor final : public VNVisitor {
cstmtp->add(");");
AstNode* newp = cstmtp;
if (nodep->isDelayed()) {
const AstVarRef* const vrefp = VN_AS(eventp, VarRef);
const AstVarRef* const vrefp = VN_CAST(eventp, VarRef);
if (nodep->isDelayed() && (m_cfuncp || !vrefp)) {
// V3Timing converts these with --timing
nodep->v3warn(E_NOTIMING, "Nonblocking event trigger "
<< (m_cfuncp ? "in a non-inlined function/task"
: "of a class or interface member or "
"array element")
<< " requires --timing");
} else if (nodep->isDelayed()) {
const std::string newvarname = "__Vdly__" + vrefp->varp()->shortName();
AstVarScope* const dlyvscp
= createTemp(flp, vrefp->varScopep()->scopep(), newvarname, 1);
@@ -1276,20 +1287,35 @@ class DelayedVisitor final : public VNVisitor {
return new AstVarRef{flp, dlyvscp, access};
};
AstAlwaysPre* const prep = new AstAlwaysPre{flp};
prep->addStmtsp(new AstAssign{flp, dlyRef(VAccess::WRITE),
new AstConst{flp, AstConst::BitFalse{}}});
AstAlwaysPost* const postp = new AstAlwaysPost{flp};
{
AstIf* const ifp = new AstIf{flp, dlyRef(VAccess::READ)};
postp->addStmtsp(ifp);
ifp->addThensp(newp);
}
AstIf* const ifp = new AstIf{flp, dlyRef(VAccess::READ)};
postp->addStmtsp(ifp);
UASSERT_OBJ(m_activep, nodep, "No active to handle FireEvent");
AstActive* const activep = new AstActive{flp, "nba-event", m_activep->sentreep()};
AstSenTree* senTreep = m_activep->sentreep();
AstActive* activep = nullptr;
if (m_inSuspendableOrFork && (senTreep->hasInitial() || senTreep->hasClocked())) {
// Suspendable code can trigger whenever it resumes, so fire when its NBAs are
// committed (see visit(AstNodeProcedure*)), clearing the flag like
// Scheme::FlagUnique
senTreep = new AstSenTree{
flp, senTreep->hasClocked() ? senTreep->sensesp()->cloneTree(true) : nullptr};
m_nbaEventSenTreeps.push_back(senTreep);
m_needsInitialTrigger |= m_timingDomains.empty();
dlyvscp->varp()->setIgnorePostWrite();
ifp->addThensp(new AstAssign{flp, dlyRef(VAccess::WRITE),
new AstConst{flp, AstConst::BitFalse{}}});
activep = new AstActive{flp, "nba-event", senTreep};
activep->senTreeStorep(senTreep);
} else {
activep = new AstActive{flp, "nba-event", senTreep};
AstAlwaysPre* const prep = new AstAlwaysPre{flp};
prep->addStmtsp(new AstAssign{flp, dlyRef(VAccess::WRITE),
new AstConst{flp, AstConst::BitFalse{}}});
activep->addStmtsp(prep);
}
ifp->addThensp(newp);
m_activep->addNextHere(activep);
activep->addStmtsp(prep);
activep->addStmtsp(postp);
newp = new AstAssign{flp, dlyRef(VAccess::WRITE),