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DFG: Special case representation of AstSel

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AstSel is a ternary node, but the 'widthp' is always constant and is
hence redundant, and 'lsbp' is very often constant. As AstSel is fairly
common, we special case as a DfgSel for the constant 'lsbp', and as
'DfgMux` for the non-constant 'lsbp'.
This commit is contained in:
Geza Lore
2022-10-06 19:59:01 +01:00
parent 0570cb8d9f
commit 29a080dd9b
5 changed files with 309 additions and 284 deletions
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src/V3Dfg.cpp
+33 -53
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@@ -539,12 +539,6 @@ void DfgGraph::runToFixedPoint(std::function<bool(DfgVertex&)> f) {
static const string toDotId(const DfgVertex& vtx) { return '"' + cvtToHex(&vtx) + '"'; }
static bool isSimpleSel(const DfgSel* vtxp) {
const DfgConst* const lp = vtxp->lsbp()->cast<DfgConst>();
const DfgConst* const wp = vtxp->widthp()->cast<DfgConst>();
return lp && wp && !lp->hasMultipleSinks() && !wp->hasMultipleSinks();
}
// Dump one DfgVertex in Graphviz format
static void dumpDotVertex(std::ostream& os, const DfgVertex& vtx) {
@@ -598,11 +592,6 @@ static void dumpDotVertex(std::ostream& os, const DfgVertex& vtx) {
}
if (const DfgConst* const constVtxp = vtx.cast<DfgConst>()) {
const bool feedsSimpleSel = !constVtxp->findSink<DfgVertex>([](const DfgVertex& v) { //
return !v.is<DfgSel>() || !isSimpleSel(v.as<DfgSel>());
});
if (feedsSimpleSel) return; // Will draw it in the sel node as it is very common
const V3Number& num = constVtxp->constp()->num();
os << toDotId(vtx);
@@ -620,20 +609,18 @@ static void dumpDotVertex(std::ostream& os, const DfgVertex& vtx) {
}
if (const DfgSel* const selVtxp = vtx.cast<DfgSel>()) {
if (isSimpleSel(selVtxp)) {
const uint32_t lsb = selVtxp->lsbp()->as<DfgConst>()->toU32();
const uint32_t msb = lsb + selVtxp->width() - 1;
os << toDotId(vtx);
os << " [label=\"SEL\n_[" << msb << ":" << lsb << "]\nW" << vtx.width() << " / F"
<< vtx.fanout() << '"';
if (vtx.hasMultipleSinks()) {
os << ", shape=doublecircle";
} else {
os << ", shape=circle";
}
os << "]" << endl;
return;
const uint32_t lsb = selVtxp->lsb();
const uint32_t msb = lsb + selVtxp->width() - 1;
os << toDotId(vtx);
os << " [label=\"SEL\n_[" << msb << ":" << lsb << "]\nW" << vtx.width() << " / F"
<< vtx.fanout() << '"';
if (vtx.hasMultipleSinks()) {
os << ", shape=doublecircle";
} else {
os << ", shape=circle";
}
os << "]" << endl;
return;
}
os << toDotId(vtx);
@@ -656,16 +643,6 @@ static void dumpDotEdge(std::ostream& os, const DfgEdge& edge, const string& hea
// Dump one DfgVertex and all of its source DfgEdges in Graphviz format
static void dumpDotVertexAndSourceEdges(std::ostream& os, const DfgVertex& vtx) {
dumpDotVertex(os, vtx);
if (const DfgSel* const selVtxp = vtx.cast<const DfgSel>()) {
if (isSimpleSel(selVtxp)) {
UASSERT_OBJ(selVtxp->sourceEdge<0>()->sourcep() == selVtxp->fromp(), selVtxp,
"Operand ordering changed");
dumpDotEdge(os, *selVtxp->sourceEdge<0>(), "");
return;
}
}
vtx.forEachSourceEdge([&](const DfgEdge& edge, size_t idx) { //
if (edge.sourcep()) {
string headLabel;
@@ -852,14 +829,14 @@ DfgVertex::~DfgVertex() {
if (VN_IS(m_dtypep, UnpackArrayDType)) VL_DO_DANGLING(delete m_dtypep, m_dtypep);
}
bool DfgVertex::selfEquals(const DfgVertex& that) const {
return this->m_type == that.m_type && this->dtypep() == that.dtypep();
}
bool DfgVertex::selfEquals(const DfgVertex& that) const { return true; }
V3Hash DfgVertex::selfHash() const { return V3Hash{m_type} + width(); }
V3Hash DfgVertex::selfHash() const { return V3Hash{}; }
bool DfgVertex::equals(const DfgVertex& that, EqualsCache& cache) const {
if (this == &that) return true;
if (this->type() != that.type()) return false;
if (this->dtypep() != that.dtypep()) return false;
if (!this->selfEquals(that)) return false;
const auto key = (this < &that) ? EqualsCache::key_type{this, &that} //
@@ -893,6 +870,8 @@ V3Hash DfgVertex::hash() {
V3Hash& result = user<V3Hash>();
if (!result.value()) {
V3Hash hash;
hash += m_type;
hash += width();
hash += selfHash();
// Variables are defined by themselves, so there is no need to hash the sources. This
// enables sound hashing of graphs circular only through variables, which we rely on.
@@ -933,13 +912,25 @@ void DfgVertex::replaceWith(DfgVertex* newSorucep) {
// Vertex classes
//------------------------------------------------------------------------------
// DfgConst ----------
bool DfgConst::selfEquals(const DfgVertex& that) const {
return constp()->sameTree(that.as<DfgConst>()->constp());
}
V3Hash DfgConst::selfHash() const { return m_constp->num().toHash(); }
// DfgSel ----------
bool DfgSel::selfEquals(const DfgVertex& that) const { return lsb() == that.as<DfgSel>()->lsb(); }
V3Hash DfgSel::selfHash() const { return V3Hash{lsb()}; }
// DfgVertexVar ----------
bool DfgVertexVar::selfEquals(const DfgVertex& that) const {
if (const DfgVertexVar* otherp = that.cast<DfgVertexVar>()) {
UASSERT_OBJ(varp() != otherp->varp(), this,
"There should only be one DfgVarPacked for a given AstVar");
}
UASSERT_OBJ(varp() != that.as<DfgVertexVar>()->varp(), this,
"There should only be one DfgVarPacked for a given AstVar");
return false;
}
@@ -950,17 +941,6 @@ V3Hash DfgVertexVar::selfHash() const {
return hash;
}
// DfgConst ----------
bool DfgConst::selfEquals(const DfgVertex& that) const {
if (const DfgConst* otherp = that.cast<DfgConst>()) {
return constp()->sameTree(otherp->constp());
}
return false;
}
V3Hash DfgConst::selfHash() const { return m_constp->num().toHash(); }
//------------------------------------------------------------------------------
// DfgVisitor
//------------------------------------------------------------------------------