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Optimize DFG before V3Gate (#6141)

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This commit is contained in:
Geza Lore
2025-07-01 17:55:08 -04:00
committed by GitHub
parent e015805194
commit 7a3f1f16ca
26 changed files with 555 additions and 181 deletions
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src/V3Dfg.cpp
+70 -17
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@@ -26,8 +26,8 @@ VL_DEFINE_DEBUG_FUNCTIONS;
// DfgGraph
//------------------------------------------------------------------------------
DfgGraph::DfgGraph(AstModule& module, const string& name)
: m_modulep{&module}
DfgGraph::DfgGraph(AstModule* modulep, const string& name)
: m_modulep{modulep}
, m_name{name} {}
DfgGraph::~DfgGraph() {
@@ -69,14 +69,31 @@ std::string DfgGraph::makeUniqueName(const std::string& prefix, size_t n) {
return "__Vdfg" + prefix + m_tmpNameStub + std::to_string(n);
}
DfgVertexVar* DfgGraph::makeNewVar(FileLine* flp, const std::string& name, AstNodeDType* dtypep) {
// Add AstVar to containing module
AstVar* const varp = new AstVar{flp, VVarType::MODULETEMP, name, dtypep};
modulep()->addStmtsp(varp);
DfgVertexVar* DfgGraph::makeNewVar(FileLine* flp, const std::string& name, AstNodeDType* dtypep,
AstScope* scopep) {
UASSERT_OBJ(!!scopep != !!modulep(), flp,
"makeNewVar scopep should only be provided for a scoped DfgGraph");
// Create and return the corresponding variable vertex
if (VN_IS(varp->dtypeSkipRefp(), UnpackArrayDType)) return new DfgVarArray{*this, varp};
return new DfgVarPacked{*this, varp};
// Create AstVar
AstVar* const varp = new AstVar{flp, VVarType::MODULETEMP, name, dtypep};
if (scopep) {
// Add AstVar to the scope's module
scopep->modp()->addStmtsp(varp);
// Create AstVarScope
AstVarScope* const vscp = new AstVarScope{flp, scopep, varp};
// Add to scope
scopep->addVarsp(vscp);
// Create and return the corresponding variable vertex
if (VN_IS(varp->dtypeSkipRefp(), UnpackArrayDType)) return new DfgVarArray{*this, vscp};
return new DfgVarPacked{*this, vscp};
} else {
// Add AstVar to containing module
modulep()->addStmtsp(varp);
// Create and return the corresponding variable vertex
if (VN_IS(varp->dtypeSkipRefp(), UnpackArrayDType)) return new DfgVarArray{*this, varp};
return new DfgVarPacked{*this, varp};
}
}
static const string toDotId(const DfgVertex& vtx) { return '"' + cvtToHex(&vtx) + '"'; }
@@ -85,9 +102,10 @@ static const string toDotId(const DfgVertex& vtx) { return '"' + cvtToHex(&vtx)
static void dumpDotVertex(std::ostream& os, const DfgVertex& vtx) {
if (const DfgVarPacked* const varVtxp = vtx.cast<DfgVarPacked>()) {
AstNode* const nodep = varVtxp->nodep();
AstVar* const varp = varVtxp->varp();
os << toDotId(vtx);
os << " [label=\"" << varp->name() << "\nW" << varVtxp->width() << " / F"
os << " [label=\"" << nodep->name() << "\nW" << varVtxp->width() << " / F"
<< varVtxp->fanout() << '"';
if (varp->direction() == VDirection::INPUT) {
@@ -112,10 +130,11 @@ static void dumpDotVertex(std::ostream& os, const DfgVertex& vtx) {
}
if (const DfgVarArray* const arrVtxp = vtx.cast<DfgVarArray>()) {
AstNode* const nodep = arrVtxp->nodep();
AstVar* const varp = arrVtxp->varp();
const int elements = VN_AS(arrVtxp->dtypep(), UnpackArrayDType)->elementsConst();
os << toDotId(vtx);
os << " [label=\"" << varp->name() << "[" << elements << "]\"";
os << " [label=\"" << nodep->name() << "[" << elements << "]\"";
if (varp->direction() == VDirection::INPUT) {
os << ", shape=box3d, style=filled, fillcolor=chartreuse2"; // Green
} else if (varp->direction() == VDirection::OUTPUT) {
@@ -299,7 +318,7 @@ void DfgGraph::dumpDotAllVarConesPrefixed(const string& label) const {
if (!sinkp) return;
// Open output file
const string coneName{prefix + sinkp->varp()->name()};
const string coneName{prefix + sinkp->nodep()->name()};
const string fileName{v3Global.debugFilename(coneName) + ".dot"};
const std::unique_ptr<std::ofstream> os{V3File::new_ofstream(fileName)};
if (os->fail()) v3fatal("Can't write file: " << fileName);
@@ -476,7 +495,7 @@ DfgVarPacked* DfgVertex::getResultVar() {
return;
}
// Prefer the one with the lexically smaller name
if (const int cmp = resp->varp()->name().compare(varp->varp()->name())) {
if (const int cmp = resp->nodep()->name().compare(varp->nodep()->name())) {
if (cmp > 0) resp = varp;
return;
}
@@ -485,6 +504,38 @@ DfgVarPacked* DfgVertex::getResultVar() {
return resp;
}
AstScope* DfgVertex::scopep(ScopeCache& cache, bool tryResultVar) VL_MT_DISABLED {
// If this is a variable, we are done
if (DfgVertexVar* const varp = this->cast<DfgVertexVar>()) return varp->varScopep()->scopep();
// Try the result var first if instructed (usully only in the recursive case)
if (tryResultVar) {
if (DfgVertexVar* const varp = this->getResultVar()) return varp->varScopep()->scopep();
}
// Look up cache
const auto pair = cache.emplace(this, nullptr);
if (pair.second) {
// Find scope based on sources, falling back on the root scope
AstScope* const rootp = v3Global.rootp()->topScopep()->scopep();
AstScope* foundp = rootp;
const auto edges = sourceEdges();
for (size_t i = 0; i < edges.second; ++i) {
DfgEdge& edge = edges.first[i];
foundp = edge.sourcep()->scopep(cache, true);
if (foundp != rootp) break;
}
pair.first->second = foundp;
}
// If the cache entry exists, but have not set the mapping yet, then we have a circualr graph
UASSERT_OBJ(pair.first->second, this,
"DfgVertex::scopep called on graph with circular operations");
// Done
return pair.first->second;
}
void DfgVertex::unlinkDelete(DfgGraph& dfg) {
// Unlink source edges
forEachSourceEdge([](DfgEdge& edge, size_t) { edge.unlinkSource(); });
@@ -521,15 +572,17 @@ V3Hash DfgSel::selfHash() const { return V3Hash{lsb()}; }
// DfgVertexVar ----------
bool DfgVertexVar::selfEquals(const DfgVertex& that) const {
UASSERT_OBJ(varp() != that.as<DfgVertexVar>()->varp(), this,
"There should only be one DfgVertexVar for a given AstVar");
UASSERT_OBJ(nodep()->type() == that.as<DfgVertexVar>()->nodep()->type(), this,
"Both DfgVertexVar should be scoped or unscoped");
UASSERT_OBJ(nodep() != that.as<DfgVertexVar>()->nodep(), this,
"There should only be one DfgVertexVar for a given AstVar or AstVarScope");
return false;
}
V3Hash DfgVertexVar::selfHash() const {
V3Hash hash;
hash += m_varp->name();
hash += m_varp->varType();
hash += nodep()->name();
hash += varp()->varType();
return hash;
}