// VISITORS
virtual void visit(AstNodeVarRef* nodep, AstNUser*) {
nodep->iterateChildren(*this);
// We only allow a LHS ref for the var being set, and a RHS ref for something else being read.
if (nodep->varScopep()->varp()->isSc()) {
clearSimple("SystemC sig"); // Don't want to eliminate the VL_ASSIGN_SI's
}
if (nodep->lvalue()) {
if (m_lhsVarRef) clearSimple(">1 lhs varRefs");
m_lhsVarRef = nodep;
} else {
if (m_rhsVarRefs.size()>1) {
AstNodeVarRef* lastRefp = m_rhsVarRefs.back();
if (0) { // Diable the multiple-input optimization
clearSimple(">1 rhs varRefs");
} else {
if (m_buffersOnly) clearSimple(">1 rhs varRefs");
if (!nodep->varScopep()->varp()->gateMultiInputOptimizable()
// We didn't check multiInput on the first varref, so check it here
|| !lastRefp->varScopep()->varp()->gateMultiInputOptimizable()) {
clearSimple("!gateMultiInputOptimizable");
}
}
}
m_rhsVarRefs.push_back(nodep);
}
}
virtual void visit(AstNodeAssign* nodep, AstNUser*) {
m_substTreep = nodep->rhsp();
if (!nodep->lhsp()->castNodeVarRef())
clearSimple("ASSIGN(non-VARREF)");
else nodep->iterateChildren(*this);
// We don't push logic other then assignments/NOTs into SenItems
// This avoids a mess in computing what exactly a POSEDGE is
// V3Const cleans up any NOTs by flipping the edges for us
if (m_buffersOnly
&& !(nodep->rhsp()->castVarRef()
// Avoid making non-clocked logic into clocked,
// as it slows down the verilator_sim_benchmark
|| (nodep->rhsp()->castNot()
&& nodep->rhsp()->castNot()->lhsp()->castVarRef()
&& nodep->rhsp()->castNot()->lhsp()->castVarRef()->varp()->isUsedClock())
)) {
clearSimple("Not a buffer (goes to a clock)");
}
}
//--------------------
// Default
virtual void visit(AstNode* nodep, AstNUser*) {
// *** Special iterator
if (!m_isSimple) return; // Fastpath
if (!(m_dedupe ? nodep->isGateDedupable() : nodep->isGateOptimizable())
|| !nodep->isPure()
|| nodep->isBrancher()) {
UINFO(5, "Non optimizable type: "<<nodep<<endl);
clearSimple("Non optimizable type");
}
else nodep->iterateChildren(*this);
}
// CONSTUCTORS
GateOkVisitor(AstNode* nodep, bool buffersOnly) {
m_isSimple = true;
m_substTreep = NULL;
m_buffersOnly = buffersOnly;
m_lhsVarRef = NULL;
// Iterate
nodep->accept(*this);
// Check results
if (!m_substTreep) {
clearSimple("No assignment found\n");
}
for (GateVarRefList::const_iterator it = rhsVarRefs().begin();
it != rhsVarRefs().end(); ++it) {
if (m_lhsVarRef && m_lhsVarRef->varScopep() == (*it)->varScopep()) {
clearSimple("Circular logic\n"); // Oh my, we'll get a UNOPTFLAT much later.
}
}
if (debug()>=9 && !m_isSimple) {
nodep->dumpTree(cout,"\tgate!Ok: ");
}
}
