Allow custom sizes, dim order and strides for tensor view. (#14944)

shoumikhin · web-flow · commit 4bdd3df3ebeb · 2025-10-09T23:02:16.000-07:00
Summary: The `make_tensor_ptr(TensrPtr)` overload creates a view on an existing `Tensor`. Here we provide a way for users to customize the shape, etc. so that they can easily do squeeze/unsqueeze and other convenient operations.

Differential Revision: D84259597
diff --git a/extension/tensor/tensor_ptr.h b/extension/tensor/tensor_ptr.h
@@ -323,26 +323,54 @@ inline TensorPtr make_tensor_ptr(
 }
 
 /**
- * Creates a TensorPtr to manage a new Tensor with the same properties
- * as the given Tensor, sharing the same data without owning it.
+ * Creates a TensorPtr to manage a new Tensor that aliases the given Tensor's
+ * storage, with optional metadata overrides. Shape dynamism is inherited from
+ * the source tensor.
  *
- * @param tensor The Tensor whose properties are used to create a new TensorPtr.
- * @return A new TensorPtr managing a Tensor with the same properties as the
- * original.
+ * If an override is provided (non-empty), it is passed as-is. If an override is
+ * empty, the corresponding metadata is reused from the source tensor when it
+ * fits; otherwise it is left empty for the core factory to derive a valid
+ * configuration. If `dim_order` is empty but `strides` is provided, `dim_order`
+ * is left empty so the core may infer it from the provided strides.
+ *
+ * @param tensor The source tensor to alias.
+ * @param sizes Optional sizes override.
+ * @param dim_order Optional dimension order override.
+ * @param strides Optional strides override.
+ * @return A TensorPtr aliasing the same storage with requested metadata.
  */
-inline TensorPtr make_tensor_ptr(const executorch::aten::Tensor& tensor) {
-  return make_tensor_ptr(
-      std::vector<executorch::aten::SizesType>(
-          tensor.sizes().begin(), tensor.sizes().end()),
-      tensor.mutable_data_ptr(),
+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 = {}) {
+  if (sizes.empty()) {
+    sizes.assign(tensor.sizes().begin(), tensor.sizes().end());
+  }
+  const auto same_rank = sizes.size() == static_cast<size_t>(tensor.dim());
+  const auto same_shape = same_rank &&
+      std::equal(sizes.begin(), sizes.end(), tensor.sizes().begin());
+  const auto element_count =
+      executorch::aten::compute_numel(sizes.data(), sizes.size());
+  const auto parent_element_count = tensor.numel();
+  ET_CHECK_MSG(
+      element_count <= parent_element_count,
+      "Requested view has %zd elements, but source tensor only has %zd.",
+      static_cast<ssize_t>(element_count),
+      static_cast<ssize_t>(parent_element_count));
 #ifndef USE_ATEN_LIB
-      std::vector<executorch::aten::DimOrderType>(
-          tensor.dim_order().begin(), tensor.dim_order().end()),
-#else // USE_ATEN_LIB
-      {},
+  if (dim_order.empty() && strides.empty() && same_rank) {
+    dim_order.assign(tensor.dim_order().begin(), tensor.dim_order().end());
+  }
 #endif // USE_ATEN_LIB
-      std::vector<executorch::aten::StridesType>(
-          tensor.strides().begin(), tensor.strides().end()),
+  if (strides.empty() && dim_order.empty() && same_shape) {
+    strides.assign(tensor.strides().begin(), tensor.strides().end());
+  }
+  return make_tensor_ptr(
+      std::move(sizes),
+      tensor.mutable_data_ptr(),
+      std::move(dim_order),
+      std::move(strides),
       tensor.scalar_type()
 #ifndef USE_ATEN_LIB
           ,
@@ -352,21 +380,21 @@ inline TensorPtr make_tensor_ptr(const executorch::aten::Tensor& tensor) {
 }
 
 /**
- * Creates a TensorPtr to manage a new Tensor with the same properties
- * as the Tensor referenced by the given TensorPtr, sharing the same data
- * without owning it.
+ * Convenience overload identical to make_tensor_ptr(*tensor_ptr, ...).
  *
- * This is a convenience overload equivalent to make_tensor_ptr(*tensor_ptr).
- * It does not extend the lifetime of the underlying buffer; if the original
- * owner releases the storage, all views aliasing it become dangling.
- *
- * @param tensor_ptr The TensorPtr whose underlying Tensor is used to initialize
- *                   the returned view.
- * @return A new TensorPtr managing a Tensor with the same properties as the
- *         original.
+ * @param tensor_ptr The source tensor pointer to alias.
+ * @param sizes Optional sizes override.
+ * @param dim_order Optional dimension order override.
+ * @param strides Optional strides override.
+ * @return A TensorPtr aliasing the same storage with requested metadata.
  */
-inline TensorPtr make_tensor_ptr(const TensorPtr& tensor_ptr) {
-  return make_tensor_ptr(*tensor_ptr);
+inline TensorPtr make_tensor_ptr(
+    const TensorPtr& tensor_ptr,
+    std::vector<executorch::aten::SizesType> sizes = {},
+    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));
 }
 
 /**
diff --git a/extension/tensor/test/tensor_ptr_test.cpp b/extension/tensor/test/tensor_ptr_test.cpp
@@ -357,6 +357,204 @@ TEST_F(TensorPtrTest, MakeTensorPtrFromExistingTensorInt32) {
   EXPECT_EQ(new_tensor->scalar_type(), executorch::aten::ScalarType::Int);
 }
 
+TEST_F(TensorPtrTest, MakeViewOverrideSizesRankIncrease) {
+  std::vector<float> data = {1, 2, 3, 4, 5, 6};
+  auto tensor = make_tensor_ptr({2, 3}, std::move(data));
+  auto view = make_tensor_ptr(tensor, {1, 2, 3});
+
+  EXPECT_EQ(view->dim(), 3);
+  EXPECT_EQ(view->size(0), 1);
+  EXPECT_EQ(view->size(1), 2);
+  EXPECT_EQ(view->size(2), 3);
+  EXPECT_EQ(view->const_data_ptr<float>(), tensor->const_data_ptr<float>());
+  EXPECT_EQ(view->strides()[0], 6);
+  EXPECT_EQ(view->strides()[1], 3);
+  EXPECT_EQ(view->strides()[2], 1);
+}
+
+TEST_F(TensorPtrTest, MakeViewOverrideSizesSameRankRecomputesStrides) {
+  float data[12] = {0};
+  auto tensor = make_tensor_ptr({3, 4}, data);
+  auto view = make_tensor_ptr(tensor, {4, 3});
+
+  EXPECT_EQ(view->dim(), 2);
+  EXPECT_EQ(view->size(0), 4);
+  EXPECT_EQ(view->size(1), 3);
+  EXPECT_EQ(view->strides()[0], 3);
+  EXPECT_EQ(view->strides()[1], 1);
+}
+
+TEST_F(TensorPtrTest, MakeViewOverrideDimOrderOnly) {
+  float data[6] = {0};
+  auto tensor = make_tensor_ptr({2, 3}, data);
+  auto view = make_tensor_ptr(tensor, {}, {1, 0}, {});
+
+  EXPECT_EQ(view->dim(), 2);
+  EXPECT_EQ(view->size(0), 2);
+  EXPECT_EQ(view->size(1), 3);
+  EXPECT_EQ(view->strides()[0], 1);
+  EXPECT_EQ(view->strides()[1], 2);
+}
+
+TEST_F(TensorPtrTest, MakeViewOverrideStridesOnlyInfersDimOrder) {
+  float data[12] = {0};
+  auto tensor = make_tensor_ptr({3, 4}, data);
+  auto view = make_tensor_ptr(tensor, {}, {}, {1, 3});
+
+  EXPECT_EQ(view->dim(), 2);
+  EXPECT_EQ(view->size(0), 3);
+  EXPECT_EQ(view->size(1), 4);
+  EXPECT_EQ(view->strides()[0], 1);
+  EXPECT_EQ(view->strides()[1], 3);
+}
+
+TEST_F(TensorPtrTest, MakeViewReuseMetadataWhenShapeSame) {
+  float data[12] = {0};
+  auto tensor = make_tensor_ptr({3, 4}, data, {1, 0}, {1, 3});
+  auto view = make_tensor_ptr(tensor, {3, 4});
+
+  EXPECT_EQ(view->dim(), 2);
+  EXPECT_EQ(view->size(0), 3);
+  EXPECT_EQ(view->size(1), 4);
+  EXPECT_EQ(view->strides()[0], 1);
+  EXPECT_EQ(view->strides()[1], 3);
+}
+
+TEST_F(TensorPtrTest, MakeViewShapeChangeWithExplicitOldStridesExpectDeath) {
+  float data[12] = {0};
+  auto tensor = make_tensor_ptr({3, 4}, data);
+  std::vector<executorch::aten::StridesType> old_strides(
+      tensor->strides().begin(), tensor->strides().end());
+
+  ET_EXPECT_DEATH(
+      { auto _ = make_tensor_ptr(tensor, {2, 6}, {}, old_strides); }, "");
+}
+
+TEST_F(TensorPtrTest, MakeViewInvalidDimOrderExpectDeath) {
+  float data[12] = {0};
+  auto tensor = make_tensor_ptr({3, 4}, data);
+
+  ET_EXPECT_DEATH(
+      { auto _ = make_tensor_ptr(tensor, {3, 4}, {2, 1}, {1, 4}); }, "");
+}
+
+TEST_F(TensorPtrTest, MakeViewFromTensorPtrConvenienceOverload) {
+  float data[12] = {0};
+  auto tensor = make_tensor_ptr({3, 4}, data);
+  auto view = make_tensor_ptr(tensor, {}, {1, 0}, {});
+
+  EXPECT_EQ(view->dim(), 2);
+  EXPECT_EQ(view->size(0), 3);
+  EXPECT_EQ(view->size(1), 4);
+  EXPECT_EQ(view->strides()[0], 1);
+  EXPECT_EQ(view->strides()[1], 3);
+}
+
+TEST_F(TensorPtrTest, MakeViewRankDecreaseFlatten) {
+  float data[6] = {1, 2, 3, 4, 5, 6};
+  auto tensor = make_tensor_ptr(
+      {2, 3},
+      data,
+      {},
+      {},
+      executorch::aten::ScalarType::Float,
+      executorch::aten::TensorShapeDynamism::DYNAMIC_UNBOUND);
+  auto view = make_tensor_ptr(tensor, {6});
+  EXPECT_EQ(view->dim(), 1);
+  EXPECT_EQ(view->size(0), 6);
+  EXPECT_EQ(view->strides()[0], 1);
+  EXPECT_NE(tensor->unsafeGetTensorImpl(), view->unsafeGetTensorImpl());
+  EXPECT_EQ(resize_tensor_ptr(view, {3, 2}), Error::NotSupported);
+  EXPECT_EQ(view->dim(), 1);
+  EXPECT_EQ(view->size(0), 6);
+}
+
+TEST_F(TensorPtrTest, MakeViewFromScalarAliasAnd1D) {
+  float scalar_value = 7.f;
+  auto tensor = make_tensor_ptr({}, &scalar_value);
+  auto alias = make_tensor_ptr(tensor);
+  EXPECT_EQ(alias->dim(), 0);
+  EXPECT_EQ(alias->numel(), 1);
+  auto reshaped = make_tensor_ptr(tensor, {1});
+  EXPECT_EQ(reshaped->dim(), 1);
+  EXPECT_EQ(reshaped->size(0), 1);
+  EXPECT_EQ(reshaped->strides()[0], 1);
+  ET_EXPECT_DEATH({ auto unused = make_tensor_ptr(tensor, {}, {0}, {}); }, "");
+  ET_EXPECT_DEATH({ auto unused = make_tensor_ptr(tensor, {}, {}, {1}); }, "");
+}
+
+TEST_F(TensorPtrTest, MakeViewExplicitDimOrderAndStridesShapeChange) {
+  float data[6] = {0};
+  auto tensor = make_tensor_ptr({2, 3}, data);
+  auto view = make_tensor_ptr(tensor, {3, 2}, {1, 0}, {1, 3});
+  EXPECT_EQ(view->dim(), 2);
+  EXPECT_EQ(view->size(0), 3);
+  EXPECT_EQ(view->size(1), 2);
+  EXPECT_EQ(view->strides()[0], 1);
+  EXPECT_EQ(view->strides()[1], 3);
+}
+
+TEST_F(TensorPtrTest, TensorUint8dataInt16Type) {
+  std::vector<int16_t> int16_values = {-1, 2, -3, 4};
+  auto byte_pointer = reinterpret_cast<const uint8_t*>(int16_values.data());
+  std::vector<uint8_t> byte_data(
+      byte_pointer, byte_pointer + int16_values.size() * sizeof(int16_t));
+  auto tensor = make_tensor_ptr(
+      {4}, std::move(byte_data), executorch::aten::ScalarType::Short);
+  EXPECT_EQ(tensor->dim(), 1);
+  EXPECT_EQ(tensor->size(0), 4);
+  auto int16_data = tensor->const_data_ptr<int16_t>();
+  EXPECT_EQ(int16_data[0], -1);
+  EXPECT_EQ(int16_data[1], 2);
+  EXPECT_EQ(int16_data[2], -3);
+  EXPECT_EQ(int16_data[3], 4);
+}
+
+TEST_F(TensorPtrTest, MakeView3DDimOrderOnly) {
+  float data[24] = {0};
+  auto tensor = make_tensor_ptr({2, 3, 4}, data);
+  auto view = make_tensor_ptr(tensor, {}, {2, 0, 1}, {});
+  EXPECT_EQ(view->dim(), 3);
+  EXPECT_EQ(view->size(0), 2);
+  EXPECT_EQ(view->size(1), 3);
+  EXPECT_EQ(view->size(2), 4);
+  EXPECT_EQ(view->strides()[0], 3);
+  EXPECT_EQ(view->strides()[1], 1);
+  EXPECT_EQ(view->strides()[2], 6);
+}
+
+#ifndef USE_ATEN_LIB
+TEST_F(TensorPtrTest, MakeViewDynamismPropagationResizeAlias) {
+  float data[12] = {0};
+  auto tensor = make_tensor_ptr(
+      {3, 4},
+      data,
+      {},
+      {},
+      executorch::aten::ScalarType::Float,
+      executorch::aten::TensorShapeDynamism::DYNAMIC_UNBOUND);
+  auto alias = make_tensor_ptr(tensor);
+  EXPECT_EQ(resize_tensor_ptr(alias, {2, 6}), Error::Ok);
+  EXPECT_EQ(alias->size(0), 2);
+  EXPECT_EQ(alias->size(1), 6);
+  EXPECT_EQ(tensor->size(0), 3);
+  EXPECT_EQ(tensor->size(1), 4);
+}
+
+TEST_F(TensorPtrTest, MakeViewSameRankShapeChangeCopiesDimOrder) {
+  float data[24] = {0};
+  auto tensor = make_tensor_ptr({2, 3, 4}, data, {2, 0, 1}, {3, 1, 6});
+  auto view = make_tensor_ptr(tensor, {4, 2, 3});
+  EXPECT_EQ(view->dim(), 3);
+  EXPECT_EQ(view->size(0), 4);
+  EXPECT_EQ(view->size(1), 2);
+  EXPECT_EQ(view->size(2), 3);
+  EXPECT_EQ(view->strides()[0], 2);
+  EXPECT_EQ(view->strides()[1], 1);
+  EXPECT_EQ(view->strides()[2], 8);
+}
+#endif
+
 TEST_F(TensorPtrTest, CloneTensorPtrFromExistingTensorInt32) {
   std::vector<int32_t> data = {1, 2, 3, 4};
   auto tensor = make_tensor_ptr({2, 2}, std::move(data));
@@ -803,7 +1001,7 @@ TEST_F(TensorPtrTest, TensorDeducedScalarType) {
   EXPECT_EQ(tensor->const_data_ptr<double>()[3], 4.0);
 }
 
-TEST_F(TensorPtrTest, TensorUint8BufferWithFloatScalarType) {
+TEST_F(TensorPtrTest, TensorUint8dataWithFloatScalarType) {
   std::vector<uint8_t> data(
       4 * executorch::aten::elementSize(executorch::aten::ScalarType::Float));
 
@@ -827,14 +1025,14 @@ TEST_F(TensorPtrTest, TensorUint8BufferWithFloatScalarType) {
   EXPECT_EQ(tensor->const_data_ptr<float>()[3], 4.0f);
 }
 
-TEST_F(TensorPtrTest, TensorUint8BufferTooSmallExpectDeath) {
+TEST_F(TensorPtrTest, TensorUint8dataTooSmallExpectDeath) {
   std::vector<uint8_t> data(
       2 * executorch::aten::elementSize(executorch::aten::ScalarType::Float));
   ET_EXPECT_DEATH(
       { auto tensor = make_tensor_ptr({2, 2}, std::move(data)); }, "");
 }
 
-TEST_F(TensorPtrTest, TensorUint8BufferTooLargeExpectDeath) {
+TEST_F(TensorPtrTest, TensorUint8dataTooLargeExpectDeath) {
   std::vector<uint8_t> data(
       5 * executorch::aten::elementSize(executorch::aten::ScalarType::Float));
   ET_EXPECT_DEATH({ auto _ = make_tensor_ptr({2, 2}, std::move(data)); }, "");
