[mlir][sparse] Include sparse emit strategy in wrapping iterator (llvm#165611)

When we create a `SparseIterator`, we sometimes wrap it in a
`FilterIterator`, which delegates _some_ calls to the underlying
`SparseIterator`.

After construction, e.g. in `makeNonEmptySubSectIterator()`, we call
`setSparseEmitStrategy()`. This sets the strategy only in one of the
filters -- if we call `setSparseEmitStrategy()` immediately after
creating the `SparseIterator`, then the wrapped `SparseIterator` will
have the right strategy, and the `FilterIterator` strategy will be
unintialized; if we call `setSparseEmitStrategy()` after wrapping the
iterator in `FilterIterator`, then the opposite happens.

If we make `setSparseEmitStrategy()` a virtual method so that it's
included in the `FilterIterator` pattern, and then do all reads of
`emitStrategy` via a virtual method as well, it's pretty simple to
ensure that the value of `strategy` is being set consistently and
correctly.

Without this, the UB of strategy being uninitialized manifests as a
sporadic test failure in
mlir/test/Integration/Dialect/SparseTensor/CPU/sparse_strided_conv_2d_nhwc_hwcf.mlir,
when run downstream with the right flags (e.g. asan + assertions off).
The test sometimes fails with `ne_sub<trivial<dense[0,1]>>.begin' op
created with unregistered dialect`. It can also be directly observed w/
msan that this uninitialized read is the cause of that issue, but msan
causes other problems w/ this test.

Author: rupprecht

mlir/lib/Dialect/SparseTensor/Transforms/Utils/SparseTensorIterator.cpp

@@ -504,6 +504,14 @@ class SimpleWrapIterator : public SparseIterator {
                      unsigned extraCursorVal = 0)
       : SparseIterator(kind, *wrap, extraCursorVal), wrap(std::move(wrap)) {}
 
+  void setSparseEmitStrategy(SparseEmitStrategy strategy) override {
+    wrap->setSparseEmitStrategy(strategy);
+  }
+
+  SparseEmitStrategy getSparseEmitStrategy() const override {
+    return wrap->getSparseEmitStrategy();
+  }
+
   SmallVector<Type> getCursorValTypes(OpBuilder &b) const override {
     return wrap->getCursorValTypes(b);
   }
@@ -979,7 +987,7 @@ class SubSectIterator : public SparseIterator {
 
 void SparseIterator::genInit(OpBuilder &b, Location l,
                              const SparseIterator *p) {
-  if (emitStrategy == SparseEmitStrategy::kDebugInterface) {
+  if (getSparseEmitStrategy() == SparseEmitStrategy::kDebugInterface) {
     std::string prefix = getDebugInterfacePrefix();
     Operation *begin = b.create(l, b.getStringAttr(prefix + ".begin"), {},
                                 getCursorValTypes(b));
@@ -994,7 +1002,7 @@ void SparseIterator::genInit(OpBuilder &b, Location l,
 }
 
 Value SparseIterator::genNotEnd(OpBuilder &b, Location l) {
-  if (emitStrategy == SparseEmitStrategy::kDebugInterface) {
+  if (getSparseEmitStrategy() == SparseEmitStrategy::kDebugInterface) {
     std::string prefix = getDebugInterfacePrefix();
     Operation *notEnd = b.create(l, b.getStringAttr(prefix + ".not_end"),
                                  getCursor(), b.getI1Type());
@@ -1005,7 +1013,7 @@ Value SparseIterator::genNotEnd(OpBuilder &b, Location l) {
 }
 
 void SparseIterator::locate(OpBuilder &b, Location l, Value crd) {
-  if (emitStrategy == SparseEmitStrategy::kDebugInterface) {
+  if (getSparseEmitStrategy() == SparseEmitStrategy::kDebugInterface) {
     std::string prefix = getDebugInterfacePrefix();
     SmallVector<Value> args = getCursor();
     args.push_back(crd);
@@ -1019,7 +1027,7 @@ void SparseIterator::locate(OpBuilder &b, Location l, Value crd) {
 }
 
 Value SparseIterator::deref(OpBuilder &b, Location l) {
-  if (emitStrategy == SparseEmitStrategy::kDebugInterface) {
+  if (getSparseEmitStrategy() == SparseEmitStrategy::kDebugInterface) {
     std::string prefix = getDebugInterfacePrefix();
     SmallVector<Value> args = getCursor();
     Operation *deref = b.create(l, b.getStringAttr(prefix + ".deref"),
@@ -1032,7 +1040,7 @@ Value SparseIterator::deref(OpBuilder &b, Location l) {
 
 ValueRange SparseIterator::forward(OpBuilder &b, Location l) {
   assert(!randomAccessible());
-  if (emitStrategy == SparseEmitStrategy::kDebugInterface) {
+  if (getSparseEmitStrategy() == SparseEmitStrategy::kDebugInterface) {
     std::string prefix = getDebugInterfacePrefix();
     Operation *next = b.create(l, b.getStringAttr(prefix + ".next"),
                                getCursor(), getCursorValTypes(b));

mlir/lib/Dialect/SparseTensor/Transforms/Utils/SparseTensorIterator.h

@@ -177,10 +177,14 @@ class SparseIterator {
 public:
   virtual ~SparseIterator() = default;
 
-  void setSparseEmitStrategy(SparseEmitStrategy strategy) {
+  virtual void setSparseEmitStrategy(SparseEmitStrategy strategy) {
     emitStrategy = strategy;
   }
 
+  virtual SparseEmitStrategy getSparseEmitStrategy() const {
+    return emitStrategy;
+  }
+
   virtual std::string getDebugInterfacePrefix() const = 0;
   virtual SmallVector<Type> getCursorValTypes(OpBuilder &b) const = 0;