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[MLIR][analysis] Lattice: Fix automatic delegation of meet to lattice value classes #82620

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Merged
merged 1 commit into from
May 17, 2024
Merged

[MLIR][analysis] Lattice: Fix automatic delegation of meet to lattice value classes #82620

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8 changes: 5 additions & 3 deletions mlir/include/mlir/Analysis/DataFlow/SparseAnalysis.h
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Original file line number Diff line number Diff line change
Expand Up @@ -132,14 +132,15 @@ class Lattice : public AbstractSparseLattice {
/// analysis, lattices will only have a `join`, no `meet`, but we want to use
/// the same `Lattice` class for both directions.
template <typename T, typename... Args>
using has_meet = decltype(std::declval<T>().meet());
using has_meet = decltype(&T::meet);
template <typename T>
using lattice_has_meet = llvm::is_detected<has_meet, T>;

/// Meet (intersect) the information contained in the 'rhs' value with this
/// lattice. Returns if the state of the current lattice changed. If the
/// lattice elements don't have a `meet` method, this is a no-op (see below.)
template <typename VT, std::enable_if_t<lattice_has_meet<VT>::value>>
template <typename VT,
std::enable_if_t<lattice_has_meet<VT>::value> * = nullptr>
ChangeResult meet(const VT &rhs) {
ValueT newValue = ValueT::meet(value, rhs);
assert(ValueT::meet(newValue, value) == newValue &&
Expand All @@ -155,7 +156,8 @@ class Lattice : public AbstractSparseLattice {
return ChangeResult::Change;
}

template <typename VT>
template <typename VT,
std::enable_if_t<!lattice_has_meet<VT>::value> * = nullptr>
ChangeResult meet(const VT &rhs) {
return ChangeResult::NoChange;
}
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60 changes: 42 additions & 18 deletions mlir/test/lib/Analysis/DataFlow/TestSparseBackwardDataFlowAnalysis.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -18,33 +18,54 @@ using namespace mlir::dataflow;

namespace {

/// This lattice represents, for a given value, the set of memory resources that
/// this value, or anything derived from this value, is potentially written to.
struct WrittenTo : public AbstractSparseLattice {
MLIR_DEFINE_EXPLICIT_INTERNAL_INLINE_TYPE_ID(WrittenTo)
using AbstractSparseLattice::AbstractSparseLattice;
/// Lattice value storing the a set of memory resources that something
/// is written to.
struct WrittenToLatticeValue {
bool operator==(const WrittenToLatticeValue &other) {
return this->writes == other.writes;
}

void print(raw_ostream &os) const override {
os << "[";
llvm::interleave(
writes, os, [&](const StringAttr &a) { os << a.str(); }, " ");
os << "]";
static WrittenToLatticeValue meet(const WrittenToLatticeValue &lhs,
const WrittenToLatticeValue &rhs) {
WrittenToLatticeValue res = lhs;
(void)res.addWrites(rhs.writes);

return res;
}

static WrittenToLatticeValue join(const WrittenToLatticeValue &lhs,
const WrittenToLatticeValue &rhs) {
// Should not be triggered by this test, but required by `Lattice<T>`
llvm_unreachable("Join should not be triggered by this test");
}

ChangeResult addWrites(const SetVector<StringAttr> &writes) {
int sizeBefore = this->writes.size();
this->writes.insert(writes.begin(), writes.end());
int sizeAfter = this->writes.size();
return sizeBefore == sizeAfter ? ChangeResult::NoChange
: ChangeResult::Change;
}
ChangeResult meet(const AbstractSparseLattice &other) override {
const auto *rhs = reinterpret_cast<const WrittenTo *>(&other);
return addWrites(rhs->writes);

void print(raw_ostream &os) const {
os << "[";
llvm::interleave(
writes, os, [&](const StringAttr &a) { os << a.str(); }, " ");
os << "]";
}

void clear() { writes.clear(); }

SetVector<StringAttr> writes;
};

/// This lattice represents, for a given value, the set of memory resources that
/// this value, or anything derived from this value, is potentially written to.
struct WrittenTo : public Lattice<WrittenToLatticeValue> {
MLIR_DEFINE_EXPLICIT_INTERNAL_INLINE_TYPE_ID(WrittenTo)
using Lattice::Lattice;
};

/// An analysis that, by going backwards along the dataflow graph, annotates
/// each value with all the memory resources it (or anything derived from it)
/// is eventually written to.
Expand All @@ -65,7 +86,9 @@ class WrittenToAnalysis : public SparseBackwardDataFlowAnalysis<WrittenTo> {
void visitExternalCall(CallOpInterface call, ArrayRef<WrittenTo *> operands,
ArrayRef<const WrittenTo *> results) override;

void setToExitState(WrittenTo *lattice) override { lattice->writes.clear(); }
void setToExitState(WrittenTo *lattice) override {
lattice->getValue().clear();
}

private:
bool assumeFuncWrites;
Expand All @@ -77,7 +100,8 @@ void WrittenToAnalysis::visitOperation(Operation *op,
if (auto store = dyn_cast<memref::StoreOp>(op)) {
SetVector<StringAttr> newWrites;
newWrites.insert(op->getAttrOfType<StringAttr>("tag_name"));
propagateIfChanged(operands[0], operands[0]->addWrites(newWrites));
propagateIfChanged(operands[0],
operands[0]->getValue().addWrites(newWrites));
return;
} // By default, every result of an op depends on every operand.
for (const WrittenTo *r : results) {
Expand All @@ -95,7 +119,7 @@ void WrittenToAnalysis::visitBranchOperand(OpOperand &operand) {
newWrites.insert(
StringAttr::get(operand.getOwner()->getContext(),
"brancharg" + Twine(operand.getOperandNumber())));
propagateIfChanged(lattice, lattice->addWrites(newWrites));
propagateIfChanged(lattice, lattice->getValue().addWrites(newWrites));
}

void WrittenToAnalysis::visitCallOperand(OpOperand &operand) {
Expand All @@ -105,7 +129,7 @@ void WrittenToAnalysis::visitCallOperand(OpOperand &operand) {
newWrites.insert(
StringAttr::get(operand.getOwner()->getContext(),
"callarg" + Twine(operand.getOperandNumber())));
propagateIfChanged(lattice, lattice->addWrites(newWrites));
propagateIfChanged(lattice, lattice->getValue().addWrites(newWrites));
}

void WrittenToAnalysis::visitExternalCall(CallOpInterface call,
Expand All @@ -124,7 +148,7 @@ void WrittenToAnalysis::visitExternalCall(CallOpInterface call,
call.getOperation()->getName().getStringRef());
}
newWrites.insert(name);
propagateIfChanged(lattice, lattice->addWrites(newWrites));
propagateIfChanged(lattice, lattice->getValue().addWrites(newWrites));
}
}

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