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Support a sequence used as an event control (#7797) (#7846)

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This commit is contained in:
Yilou Wang
2026-07-06 13:12:01 -04:00
committed by GitHub
parent 39b646349f
commit 8ed0acf1ec
23 changed files with 465 additions and 28 deletions
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src/V3Assert.cpp
+69 -6
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@@ -90,6 +90,58 @@ public:
explicit DefaultDisablePropagateVisitor(AstNetlist* nodep) { iterate(nodep); }
};
// Lower a sequence used as an event control ('@seq', IEEE 1800-2023 9.4.2.4) into a
// synthesized event fired by an internal 'cover sequence' on each end-of-match
class SeqEventLowerVisitor final : public VNVisitor {
// STATE
AstNodeModule* m_modp = nullptr; // Current module
V3UniqueNames m_names{"__VseqEvent"}; // Synthesized event names
// VISITORS
void visit(AstNodeModule* nodep) override {
VL_RESTORER(m_modp);
m_modp = nodep;
iterateChildren(nodep);
}
void visit(AstSenItem* nodep) override {
AstFuncRef* const funcrefp = VN_CAST(nodep->sensp(), FuncRef);
if (funcrefp && VN_IS(funcrefp->taskp(), Sequence)) {
FileLine* const flp = nodep->fileline();
AstVar* const eventp = new AstVar{flp, VVarType::MODULETEMP, m_names.get(nodep),
m_modp->findBasicDType(VBasicDTypeKwd::EVENT)};
eventp->lifetime(VLifetime::STATIC_EXPLICIT);
m_modp->addStmtsp(eventp);
v3Global.setHasEvents();
funcrefp->unlinkFrBack();
nodep->sensp(new AstVarRef{flp, eventp, VAccess::READ});
const bool automaticActual = funcrefp->exists([](const AstNodeVarRef* refp) {
return refp->varp() && refp->varp()->lifetime().isAutomatic();
});
if (automaticActual) {
nodep->v3error("Arguments to a sequence used as an event control must be"
" static (IEEE 1800-2023 9.4.2.4)");
VN_AS(funcrefp->taskp(), Sequence)->isReferenced(false);
VL_DO_DANGLING(pushDeletep(funcrefp), funcrefp);
return;
}
AstFireEvent* const firep
= new AstFireEvent{flp, new AstVarRef{flp, eventp, VAccess::WRITE}, false};
AstCover* const coverp
= new AstCover{flp, new AstPropSpec{flp, nullptr, nullptr, funcrefp}, firep,
VAssertType::CONCURRENT};
coverp->isCoverSeq(true);
coverp->isSeqEvent(true);
m_modp->addStmtsp(coverp);
return;
}
iterateChildren(nodep);
}
void visit(AstNode* nodep) override { iterateChildren(nodep); }
public:
explicit SeqEventLowerVisitor(AstNetlist* nodep) { iterate(nodep); }
};
} // namespace
void V3AssertCommon::collectDefaultDisable(AstNetlist* nodep) {
@@ -97,6 +149,11 @@ void V3AssertCommon::collectDefaultDisable(AstNetlist* nodep) {
{ DefaultDisablePropagateVisitor{nodep}; }
}
void V3AssertCommon::lowerSequenceEvents(AstNetlist* nodep) {
{ SeqEventLowerVisitor{nodep}; }
V3Global::dumpCheckGlobalTree("assertseqevent", 0, dumpTreeEitherLevel() >= 3);
}
//######################################################################
// AssertDeFutureVisitor
// If any AstFuture, then move all non-future varrefs to be one cycle behind,
@@ -546,14 +603,19 @@ class AssertVisitor final : public VNVisitor {
bool selfDestruct = false;
bool passspGated = false;
if (const AstCover* const snodep = VN_CAST(nodep, Cover)) {
const AstCover* const coverp = VN_CAST(nodep, Cover);
// A sequence event control is not an assertion directive; no assertion control
const bool seqEvent = coverp && coverp->isSeqEvent();
if (coverp) {
++m_statCover;
if (!v3Global.opt.coverageUser()) {
if (seqEvent) {
// Keep the event-fire action, with no coverage bucket
} else if (!v3Global.opt.coverageUser()) {
selfDestruct = true;
} else {
// V3Coverage assigned us a bucket to increment.
AstCoverInc* const covincp = VN_AS(snodep->coverincsp(), CoverInc);
UASSERT_OBJ(covincp, snodep, "Missing AstCoverInc under assertion");
AstCoverInc* const covincp = VN_AS(coverp->coverincsp(), CoverInc);
UASSERT_OBJ(covincp, coverp, "Missing AstCoverInc under assertion");
covincp->unlinkFrBackWithNext(); // next() might have AstAssign for trace
if (message != "") covincp->declp()->comment(message);
if (passsp) {
@@ -597,7 +659,8 @@ class AssertVisitor final : public VNVisitor {
FileLine* const flp = nodep->fileline();
bool passspAlreadyGated = false;
if (passsp && VN_IS(passsp, If)) passspAlreadyGated = VN_AS(passsp, If)->user1();
if (passsp && !passspGated && !passspAlreadyGated && !VN_IS(propExprp, PExpr)) {
if (passsp && !passspGated && !passspAlreadyGated && !VN_IS(propExprp, PExpr)
&& !seqEvent) {
passsp = newIfAssertPassOn(passsp, nodep->directive(), nodep->userType(),
/*vacuous=*/false);
}
@@ -607,7 +670,7 @@ class AssertVisitor final : public VNVisitor {
AstNode* bodysp = assertBody(nodep, propExprp, passsp, failsp);
if (disablep) bodysp = new AstIf{flp, new AstLogNot{flp, disablep}, bodysp};
// Add assertOn check last, for better combining
bodysp = newIfAssertOn(bodysp, nodep->directive(), nodep->userType());
if (!seqEvent) bodysp = newIfAssertOn(bodysp, nodep->directive(), nodep->userType());
if (sentreep) bodysp = new AstAlways{flp, VAlwaysKwd::ALWAYS, sentreep, bodysp};
if (passsp && !passsp->backp()) VL_DO_DANGLING(pushDeletep(passsp), passsp);