virtual AstNUser* visit(GateVarVertex *vvertexp, AstNUser*) {
// Check that we haven't been here before
if (vvertexp->varScp()->user2()) return NULL;
vvertexp->varScp()->user2(true);
AstNodeVarRef* dupVarRefp = (AstNodeVarRef*) vvertexp->iterateInEdges(*this, (AstNUser*) vvertexp);
if (dupVarRefp && vvertexp->inSize1()) {
V3GraphEdge* edgep = vvertexp->inBeginp();
GateLogicVertex* lvertexp = (GateLogicVertex*)edgep->fromp();
if (!vvertexp->dedupable()) vvertexp->varScp()->v3fatalSrc("GateLogicVertex* visit should have returned NULL if consumer var vertex is not dedupable.");
GateOkVisitor okVisitor(lvertexp->nodep(), false, true);
if (okVisitor.isSimple()) {
AstVarScope* dupVarScopep = dupVarRefp->varScopep();
GateVarVertex* dupVvertexp = (GateVarVertex*) (dupVarScopep->user1p());
UINFO(4,"replacing " << vvertexp << " with " << dupVvertexp << endl);
++m_numDeduped;
// Replace all of this varvertex's consumers with dupVarRefp
for (V3GraphEdge* outedgep = vvertexp->outBeginp();outedgep;) {
GateLogicVertex* consumeVertexp = dynamic_cast<GateLogicVertex*>(outedgep->top());
AstNode* consumerp = consumeVertexp->nodep();
GateElimVisitor elimVisitor(consumerp,vvertexp->varScp(),dupVarRefp);
outedgep = outedgep->relinkFromp(dupVvertexp);
}
// Propogate attributes
dupVvertexp->propagateAttrClocksFrom(vvertexp);
// Remove inputs links
while (V3GraphEdge* inedgep = vvertexp->inBeginp()) {
inedgep->unlinkDelete(); VL_DANGLING(inedgep);
}
// replaceAssigns() does the deleteTree on lvertexNodep in a later step
AstNode* lvertexNodep = lvertexp->nodep();
lvertexNodep->unlinkFrBack();
vvertexp->varScp()->valuep(lvertexNodep);
lvertexNodep = NULL;
vvertexp->user(true);
lvertexp->user(true);
}
}
return NULL;
}
void GateVisitor::optimizeSignals(bool allowMultiIn) {
for (V3GraphVertex* itp = m_graph.verticesBeginp(); itp; itp=itp->verticesNextp()) {
if (GateVarVertex* vvertexp = dynamic_cast<GateVarVertex*>(itp)) {
if (vvertexp->inEmpty()) {
vvertexp->clearReducibleAndDedupable("inEmpty"); // Can't deal with no sources
if (!vvertexp->isTop() // Ok if top inputs are driverless
&& !vvertexp->varScp()->varp()->valuep()
&& !vvertexp->varScp()->varp()->isSigPublic()) {
UINFO(4, "No drivers "<<vvertexp->varScp()<<endl);
if (0) {
// If we warned here after constant propagation, what the user considered
// reasonable logic may have disappeared. Issuing a warning would
// thus be confusing. V3Undriven now handles this.
vvertexp->varScp()->varp()->v3warn(UNDRIVEN,"Signal has no drivers "
<<vvertexp->scopep()->prettyName()<<"."
<<vvertexp->varScp()->varp()->prettyName());
}
}
}
else if (!vvertexp->inSize1()) {
vvertexp->clearReducibleAndDedupable("size!1"); // Can't deal with more than one src
}
// Reduce it?
if (!vvertexp->reducible()) {
UINFO(8, "SigNotRed "<<vvertexp->name()<<endl);
} else {
UINFO(8, "Sig "<<vvertexp->name()<<endl);
GateLogicVertex* logicVertexp = dynamic_cast<GateLogicVertex*>
(vvertexp->inBeginp()->fromp());
UINFO(8, " From "<<logicVertexp->name()<<endl);
AstNode* logicp = logicVertexp->nodep();
if (logicVertexp->reducible()) {
// Can we eliminate?
GateOkVisitor okVisitor(logicp, vvertexp->isClock(), false);
bool multiInputs = okVisitor.rhsVarRefs().size() > 1;
// Was it ok?
bool doit = okVisitor.isSimple();
if (doit && multiInputs) {
if (!allowMultiIn) doit = false;
// Doit if one input, or not used, or used only once, ignoring traces
int n=0;
for (V3GraphEdge* edgep = vvertexp->outBeginp(); edgep; edgep = edgep->outNextp()) {
GateLogicVertex* consumeVertexp = dynamic_cast<GateLogicVertex*>(edgep->top());
if (!consumeVertexp->slow()) { // Not tracing or other slow path junk
if (edgep->top()->outBeginp()) { // Destination is itself used
n += edgep->weight();
}
}
if (n>1) {
doit = false;
break;
}
}
}
// Process it
if (!doit) {
if (allowMultiIn && (debug()>=9)) {
UINFO(9, "Not ok simp"<<okVisitor.isSimple()<<" mi"<<multiInputs
<<" ob"<<vvertexp->outBeginp()<<" on"<<(vvertexp->outBeginp()?vvertexp->outBeginp()->outNextp():0)
<<" "<<vvertexp->name()
<<endl);
for (V3GraphEdge* edgep = vvertexp->outBeginp(); edgep; edgep = edgep->outNextp()) {
GateLogicVertex* consumeVertexp = dynamic_cast<GateLogicVertex*>(edgep->top());
UINFO(9, " edge "<<edgep<<" to: "<<consumeVertexp->nodep()<<endl);
}
for (V3GraphEdge* edgep = vvertexp->inBeginp(); edgep; edgep = edgep->inNextp()) {
GateLogicVertex* consumeVertexp = dynamic_cast<GateLogicVertex*>(edgep->fromp());
UINFO(9, " edge "<<edgep<<" from: "<<consumeVertexp->nodep()<<endl);
}
}
}
else {
AstNode* substp = okVisitor.substTree();
if (debug()>=5) logicp->dumpTree(cout,"\telimVar: ");
if (debug()>=5) substp->dumpTree(cout,"\t subst: ");
++m_statSigs;
bool removedAllUsages = true;
for (V3GraphEdge* edgep = vvertexp->outBeginp();
edgep; ) {
GateLogicVertex* consumeVertexp = dynamic_cast<GateLogicVertex*>(edgep->top());
AstNode* consumerp = consumeVertexp->nodep();
if (!elimLogicOkOutputs(consumeVertexp, okVisitor/*ref*/)) {
// Cannot optimize this replacement
removedAllUsages = false;
edgep = edgep->outNextp();
} else {
optimizeElimVar(vvertexp->varScp(), substp, consumerp);
// If the new replacement referred to a signal,
// Correct the graph to point to this new generating variable
const GateVarRefList& rhsVarRefs = okVisitor.rhsVarRefs();
for (GateVarRefList::const_iterator it = rhsVarRefs.begin();
it != rhsVarRefs.end(); ++it) {
AstVarScope* newvarscp = (*it)->varScopep();
UINFO(9," Point-to-new vertex "<<newvarscp<<endl);
GateVarVertex* varvertexp = makeVarVertex(newvarscp);
new V3GraphEdge(&m_graph, varvertexp, consumeVertexp, 1);
// Propagate clock attribute onto generating node
varvertexp->propagateAttrClocksFrom(vvertexp);
}
// Remove the edge
edgep->unlinkDelete(); VL_DANGLING(edgep);
++m_statRefs;
edgep = vvertexp->outBeginp();
}
}
if (removedAllUsages) {
// Remove input links
while (V3GraphEdge* edgep = vvertexp->inBeginp()) {
edgep->unlinkDelete(); VL_DANGLING(edgep);
}
// Clone tree so we remember it for tracing, and keep the pointer
// to the "ALWAYS" part of the tree as part of this statement
// That way if a later signal optimization that retained a pointer to the always
// can optimize it further
logicp->unlinkFrBack();
vvertexp->varScp()->valuep(logicp);
logicp = NULL;
// Mark the vertex so we don't mark it as being unconsumed in the next step
vvertexp->user(true);
logicVertexp->user(true);
}
}
}
}
}
}
}