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Internals: Dump Ast expression pattern statistics like Dfg (#7818)

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Remove the expression combination counts from the default stats file,
and add a new `--dump-ast-patterns` option, which will dump new
`*_ast_patterns_*.txt` files. These contain the expression combinations
in a similar S-expression format as Dfg already produces with
`--dump-dfg-stats`. These dumps are not produced by just `--stats` as
they are fairly expensive to compute. Currently the new option will dump
at two points: just before we change to C types via widthMin usage, and
just before emit.
This commit is contained in:
Geza Lore
2026-06-21 22:17:36 +01:00
committed by GitHub
parent fbea10b427
commit eafe9636cf
17 changed files with 633 additions and 115 deletions
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src/V3Stats.cpp
-20
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@@ -35,15 +35,12 @@ class StatsVisitor final : public VNVisitorConst {
struct Counters final {
// Nodes of given type
std::array<uint64_t, VNType::NUM_TYPES()> m_statTypeCount{};
// Nodes of given type with given type immediate child
std::array<std::array<uint64_t, VNType::NUM_TYPES()>, VNType::NUM_TYPES()> m_statAbove{};
// Prediction of given type
std::array<uint64_t, VBranchPred::_ENUM_END> m_statPred{};
};
// STATE
const bool m_fastOnly; // When true, consider only fast functions
const AstNodeExpr* m_parentExprp = nullptr; // Parent expression
Counters m_counters; // The actual counts we will display
Counters m_dumpster; // Alternate buffer to make discarding parts of the tree easier
Counters* m_accump; // The currently active accumulator
@@ -75,14 +72,6 @@ class StatsVisitor final : public VNVisitorConst {
countThenIterateChildren(nodep);
}
void visit(AstNodeExpr* nodep) override {
// Count expression combinations
if (m_parentExprp) ++m_accump->m_statAbove[m_parentExprp->type()][nodep->type()];
VL_RESTORER(m_parentExprp);
m_parentExprp = nodep;
countThenIterateChildren(nodep);
}
void visit(AstNodeIf* nodep) override {
// Track prediction
++m_accump->m_statPred[nodep->branchPred()];
@@ -148,15 +137,6 @@ public:
}
}
// Expression combinations
for (size_t t1 = 0; t1 < VNType::NUM_TYPES(); ++t1) {
for (size_t t2 = 0; t2 < VNType::NUM_TYPES(); ++t2) {
if (const uint64_t c = m_counters.m_statAbove[t1][t2]) {
addStat("Expr combination, " + typeName(t1) + " over " + typeName(t2), c);
}
}
}
// Branch predictions
for (int t = 0; t < VBranchPred::_ENUM_END; ++t) {
if (const uint64_t c = m_counters.m_statPred[t]) {