Tensor view keeps original tensor alive. (#15056)

Summary: TensorPtr view created with TensorPtr should keep it alive to
match ATen behavior.

Differential Revision: D84512176

Author: shoumikhin

extension/apple/ExecuTorch/Exported/ExecuTorchTensor.mm

@@ -129,7 +129,7 @@ - (instancetype)initWithNativeInstance:(void *)nativeInstance {
 - (instancetype)initWithTensor:(ExecuTorchTensor *)otherTensor {
   ET_CHECK(otherTensor);
   auto tensor = make_tensor_ptr(
-    **reinterpret_cast<TensorPtr *>(otherTensor.nativeInstance)
+    *reinterpret_cast<TensorPtr *>(otherTensor.nativeInstance)
   );
   return [self initWithNativeInstance:&tensor];
 }

extension/tensor/tensor_ptr.h

@@ -339,13 +339,16 @@ inline TensorPtr make_tensor_ptr(
  * @param sizes Optional sizes override.
  * @param dim_order Optional dimension order override.
  * @param strides Optional strides override.
+ * @param deleter A custom deleter function for managing the lifetime of the
+ * original Tensor.
  * @return A TensorPtr aliasing the same storage with requested metadata.
  */
 inline TensorPtr make_tensor_ptr(
     const executorch::aten::Tensor& tensor,
     std::vector<executorch::aten::SizesType> sizes = {},
     std::vector<executorch::aten::DimOrderType> dim_order = {},
-    std::vector<executorch::aten::StridesType> strides = {}) {
+    std::vector<executorch::aten::StridesType> strides = {},
+    std::function<void(void*)> deleter = nullptr) {
   if (sizes.empty()) {
     sizes.assign(tensor.sizes().begin(), tensor.sizes().end());
   }
@@ -373,16 +376,18 @@ inline TensorPtr make_tensor_ptr(
       tensor.mutable_data_ptr(),
       std::move(dim_order),
       std::move(strides),
-      tensor.scalar_type()
+      tensor.scalar_type(),
 #ifndef USE_ATEN_LIB
-          ,
-      tensor.shape_dynamism()
+      tensor.shape_dynamism(),
+#else // USE_ATEN_LIB
+      executorch::aten::TensorShapeDynamism::DYNAMIC_BOUND,
 #endif // USE_ATEN_LIB
-  );
+      std::move(deleter));
 }
 
 /**
  * Convenience overload identical to make_tensor_ptr(*tensor_ptr, ...).
+ * Keeps the original TensorPtr alive until the returned TensorPtr is destroyed.
  *
  * @param tensor_ptr The source tensor pointer to alias.
  * @param sizes Optional sizes override.
@@ -396,7 +401,11 @@ inline TensorPtr make_tensor_ptr(
     std::vector<executorch::aten::DimOrderType> dim_order = {},
     std::vector<executorch::aten::StridesType> strides = {}) {
   return make_tensor_ptr(
-      *tensor_ptr, std::move(sizes), std::move(dim_order), std::move(strides));
+      *tensor_ptr,
+      std::move(sizes),
+      std::move(dim_order),
+      std::move(strides),
+      [tensor_ptr](void*) {});
 }
 
 /**

extension/tensor/test/tensor_ptr_test.cpp

@@ -1038,6 +1038,74 @@ TEST_F(TensorPtrTest, TensorUint8dataTooLargeExpectDeath) {
   ET_EXPECT_DEATH({ auto _ = make_tensor_ptr({2, 2}, std::move(data)); }, "");
 }
 
+TEST_F(TensorPtrTest, MakeViewFromTensorPtrKeepsSourceAlive) {
+  bool freed = false;
+  auto* data = new float[6]{1, 2, 3, 4, 5, 6};
+  auto tensor = make_tensor_ptr(
+      {2, 3},
+      data,
+      {},
+      {},
+      executorch::aten::ScalarType::Float,
+      executorch::aten::TensorShapeDynamism::DYNAMIC_BOUND,
+      [&freed](void* p) {
+        freed = true;
+        delete[] static_cast<float*>(p);
+      });
+  auto view = make_tensor_ptr(tensor);
+  tensor.reset();
+  EXPECT_FALSE(freed);
+  EXPECT_EQ(view->const_data_ptr<float>()[0], 1.0f);
+  view->mutable_data_ptr<float>()[0] = 42.0f;
+  EXPECT_EQ(view->const_data_ptr<float>()[0], 42.0f);
+  view.reset();
+  EXPECT_TRUE(freed);
+}
+
+TEST_F(TensorPtrTest, MakeViewFromTensorDoesNotKeepAliveByDefault) {
+  bool freed = false;
+  auto* data = new float[2]{7.0f, 8.0f};
+  auto tensor = make_tensor_ptr(
+      {2, 1},
+      data,
+      {},
+      {},
+      executorch::aten::ScalarType::Float,
+      executorch::aten::TensorShapeDynamism::DYNAMIC_BOUND,
+      [&freed](void* p) {
+        freed = true;
+        delete[] static_cast<float*>(p);
+      });
+  auto view = make_tensor_ptr(*tensor);
+  auto raw = view->const_data_ptr<float>();
+  EXPECT_EQ(raw, data);
+  tensor.reset();
+  EXPECT_TRUE(freed);
+  view.reset();
+}
+
+TEST_F(TensorPtrTest, MakeViewFromTensorWithDeleterKeepsAlive) {
+  bool freed = false;
+  auto* data = new float[3]{1.0f, 2.0f, 3.0f};
+  auto tensor = make_tensor_ptr(
+      {3},
+      data,
+      {},
+      {},
+      executorch::aten::ScalarType::Float,
+      executorch::aten::TensorShapeDynamism::DYNAMIC_BOUND,
+      [&freed](void* p) {
+        freed = true;
+        delete[] static_cast<float*>(p);
+      });
+  auto view = make_tensor_ptr(*tensor, {}, {}, {}, [tensor](void*) {});
+  tensor.reset();
+  EXPECT_FALSE(freed);
+  EXPECT_EQ(view->const_data_ptr<float>()[2], 3.0f);
+  view.reset();
+  EXPECT_TRUE(freed);
+}
+
 TEST_F(TensorPtrTest, VectorFloatTooSmallExpectDeath) {
   std::vector<float> data(9, 1.f);
   ET_EXPECT_DEATH({ auto _ = make_tensor_ptr({2, 5}, std::move(data)); }, "");