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Internals: Move Dfg CSE into separate source file (#6363)

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Parts of this algorithm were distributed over many files some
masquerading as re-usable APIs, they were not. Move everything into one
file and avoid unnecessary virtual functions.
This commit is contained in:
Geza Lore
2025-09-03 17:34:55 +01:00
committed by GitHub
parent 5161cea8cd
commit a49334f3e4
8 changed files with 338 additions and 202 deletions
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src/V3Dfg.cpp
-57
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@@ -555,63 +555,6 @@ DfgVertex::DfgVertex(DfgGraph& dfg, VDfgType type, FileLine* flp, AstNodeDType*
dfg.addVertex(*this);
}
bool DfgVertex::equals(const DfgVertex& that, EqualsCache& cache) const {
// If same vertex, then equal
if (this == &that) return true;
// If different type, then not equal
if (this->type() != that.type()) return false;
// If different data type, then not equal
if (this->dtypep() != that.dtypep()) return false;
// If different number of inputs, then not equal
if (this->nInputs() != that.nInputs()) return false;
// Check vertex specifics
if (!this->selfEquals(that)) return false;
// Check sources
const auto key = (this < &that) ? EqualsCache::key_type{this, &that} //
: EqualsCache::key_type{&that, this};
// Note: the recursive invocation can cause a re-hash but that will not invalidate references
uint8_t& result = cache[key];
if (!result) {
const bool equal = [&]() {
for (size_t i = 0; i < nInputs(); ++i) {
const DfgVertex* const ap = this->inputp(i);
const DfgVertex* const bp = that.inputp(i);
if (!ap && !bp) continue;
if (!ap || !bp) return false;
if (!ap->equals(*bp, cache)) return false;
}
return true;
}();
result = (static_cast<uint8_t>(equal) << 1) | 1;
}
return result >> 1;
}
V3Hash DfgVertex::hash(DfgUserMap<V3Hash>& cache) {
V3Hash& result = cache[this];
if (!result.value()) {
V3Hash hash{selfHash()};
// Variables are defined by themselves, so there is no need to hash them further
// (especially the sources). This enables sound hashing of graphs circular only through
// variables, which we rely on.
if (!is<DfgVertexVar>()) {
hash += m_type;
hash += size();
foreachSource([&](DfgVertex& vtx) {
hash += vtx.hash(cache);
return false;
});
}
result = hash;
}
return result;
}
uint32_t DfgVertex::fanout() const {
uint32_t result = 0;
foreachSink([&](const DfgVertex&) {