message: [LMHLO] Simplify FusionOp::getInputBuffers() and friends.
  No need to walk the entire region, instead just iterate over the top level operations in
  the region attached to the fusion op.
diff: @@ -687,39 +687,35 @@ def FusionOp : LHLO_Op<"fusion", [SingleBlockImplicitTerminator<"TerminatorOp">]
  ];
  let extraClassDeclaration = [{
  - SmallVector<Value, 4> getInputBuffers() {
  - SmallVector<Value, 4> buffers;
  - this->region().walk([&](memref::TensorLoadOp load) {
  - if (load.memref().getParentRegion()->isProperAncestor(&region()))
  + SmallVector<Value> getInputBuffers() {
  + SmallVector<Value> buffers;
  + for (auto load : region().front().getOps<memref::TensorLoadOp>()) {
  buffers.push_back(load.memref());
  - });
  + }
  return buffers;
  }
  - SmallVector<Value, 4> getOutputBuffers() {
  - SmallVector<Value, 4> buffers;
  - this->region().walk([&](memref::TensorStoreOp store) {
  - if (store.memref().getParentRegion()->isProperAncestor(&region()))
  + SmallVector<Value> getOutputBuffers() {
  + SmallVector<Value> buffers;
  + for (auto store : region().front().getOps<memref::TensorStoreOp>()) {
  buffers.push_back(store.memref());
  - });
  + }
  return buffers;
  }
  - SmallVector<Value, 4> getFusionParameters() {
  - SmallVector<Value, 4> buffers;
  - this->region().walk([&](memref::TensorLoadOp load) {
  - if (load.memref().getParentRegion()->isProperAncestor(&region()))
  + SmallVector<Value> getFusionParameters() {
  + SmallVector<Value> buffers;
  + for (auto load : region().front().getOps<memref::TensorLoadOp>()) {
  buffers.push_back(load);
  - });
  + }
  return buffers;
  }
  - SmallVector<Value, 4> getFusionResults() {
  - SmallVector<Value, 4> buffers;
  - this->region().walk([&](memref::TensorStoreOp store) {
  - if (store.memref().getParentRegion()->isProperAncestor(&region()))
  + SmallVector<Value> getFusionResults() {
  + SmallVector<Value> buffers;
  + for (auto store : region().front().getOps<memref::TensorStoreOp>()) {
  buffers.push_back(store.tensor());
  - });
  + }
  return buffers;
  }
  }];
  