Add helper function to create empty, full, ones and zeros tensors. (#5261)

Summary:
Pull Request resolved: #5261

.

Differential Revision: D62486240

Author: shoumikhin

extension/tensor/targets.bzl

@@ -15,6 +15,7 @@ def define_common_targets():
             srcs = [
                 "tensor_impl_ptr.cpp",
                 "tensor_ptr.cpp",
+                "tensor_ptr_maker.cpp",
             ],
             exported_headers = [
                 "tensor.h",

extension/tensor/tensor_ptr.h

@@ -142,8 +142,7 @@ inline TensorPtr make_tensor_ptr(
  *
  * This template overload is specialized for cases where the tensor data is
  * provided as a vector. The scalar type is automatically deduced from the
- * vector's data type. The deleter ensures that the data vector is properly
- * managed and its lifetime is tied to the TensorImpl.
+ * vector's data type.
  *
  * @tparam T The C++ type of the tensor elements, deduced from the vector.
  * @param sizes A vector specifying the size of each dimension.
@@ -174,8 +173,7 @@ TensorPtr make_tensor_ptr(
  *
  * This template overload is specialized for cases where the tensor data is
  * provided as a vector. The scalar type is automatically deduced from the
- * vector's data type. The deleter ensures that the data vector is properly
- * managed and its lifetime is tied to the TensorImpl.
+ * vector's data type.
  *
  * @tparam T The C++ type of the tensor elements, deduced from the vector.
  * @param data A vector containing the tensor's data.
@@ -190,6 +188,27 @@ TensorPtr make_tensor_ptr(
   return make_tensor_ptr(make_tensor_impl_ptr(std::move(data), dynamism));
 }
 
+/**
+ * Creates a TensorPtr that manages a Tensor with the specified properties.
+ *
+ * This template overload allows creating a Tensor from an initializer list
+ * of data. The scalar type is automatically deduced from the type of the
+ * initializer list's elements.
+ *
+ * @tparam T The C++ type of the tensor elements, deduced from the initializer
+ * list.
+ * @param data An initializer list containing the tensor's data.
+ * @param dynamism Specifies the mutability of the tensor's shape.
+ * @return A TensorPtr that manages the newly created TensorImpl.
+ */
+template <typename T = float>
+TensorPtr make_tensor_ptr(
+    std::initializer_list<T> data,
+    exec_aten::TensorShapeDynamism dynamism =
+        exec_aten::TensorShapeDynamism::DYNAMIC_BOUND) {
+  return make_tensor_ptr(std::vector<T>(data), dynamism);
+}
+
 /**
  * Creates a TensorPtr that manages a Tensor with the specified properties.
  *

extension/tensor/tensor_ptr_maker.cpp

@@ -0,0 +1,114 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#include <executorch/extension/tensor/tensor_ptr_maker.h>
+
+namespace executorch {
+namespace extension {
+namespace {
+template <
+    typename INT_T,
+    typename std::enable_if<
+        std::is_integral<INT_T>::value && !std::is_same<INT_T, bool>::value,
+        bool>::type = true>
+bool extract_scalar(exec_aten::Scalar scalar, INT_T* out_val) {
+  if (!scalar.isIntegral(/*includeBool=*/false)) {
+    return false;
+  }
+  int64_t val = scalar.to<int64_t>();
+  if (val < std::numeric_limits<INT_T>::lowest() ||
+      val > std::numeric_limits<INT_T>::max()) {
+    return false;
+  }
+  *out_val = static_cast<INT_T>(val);
+  return true;
+}
+
+template <
+    typename FLOAT_T,
+    typename std::enable_if<std::is_floating_point<FLOAT_T>::value, bool>::
+        type = true>
+bool extract_scalar(exec_aten::Scalar scalar, FLOAT_T* out_val) {
+  double val;
+  if (scalar.isFloatingPoint()) {
+    val = scalar.to<double>();
+    if (std::isfinite(val) &&
+        (val < std::numeric_limits<FLOAT_T>::lowest() ||
+         val > std::numeric_limits<FLOAT_T>::max())) {
+      return false;
+    }
+  } else if (scalar.isIntegral(/*includeBool=*/false)) {
+    val = static_cast<double>(scalar.to<int64_t>());
+  } else {
+    return false;
+  }
+  *out_val = static_cast<FLOAT_T>(val);
+  return true;
+}
+
+template <
+    typename BOOL_T,
+    typename std::enable_if<std::is_same<BOOL_T, bool>::value, bool>::type =
+        true>
+bool extract_scalar(exec_aten::Scalar scalar, BOOL_T* out_val) {
+  if (scalar.isIntegral(false)) {
+    *out_val = static_cast<bool>(scalar.to<int64_t>());
+    return true;
+  }
+  if (scalar.isBoolean()) {
+    *out_val = scalar.to<bool>();
+    return true;
+  }
+  return false;
+}
+
+#define ET_EXTRACT_SCALAR(scalar, out_val) \
+  ET_CHECK_MSG(                            \
+      extract_scalar(scalar, &out_val),    \
+      #scalar " could not be extracted: wrong type or out of range");
+
+} // namespace
+
+TensorPtr empty_strided(
+    std::vector<exec_aten::SizesType> sizes,
+    std::vector<exec_aten::StridesType> strides,
+    exec_aten::ScalarType type,
+    exec_aten::TensorShapeDynamism dynamism) {
+  std::vector<uint8_t> data(
+      exec_aten::compute_numel(sizes.data(), sizes.size()) *
+      exec_aten::elementSize(type));
+  return make_tensor_ptr(
+      type,
+      std::move(sizes),
+      std::move(data),
+      {},
+      std::move(strides),
+      dynamism);
+}
+
+TensorPtr full_strided(
+    std::vector<exec_aten::SizesType> sizes,
+    std::vector<exec_aten::StridesType> strides,
+    exec_aten::Scalar fill_value,
+    exec_aten::ScalarType type,
+    exec_aten::TensorShapeDynamism dynamism) {
+  auto tensor =
+      empty_strided(std::move(sizes), std::move(strides), type, dynamism);
+  ET_SWITCH_REALB_TYPES(type, nullptr, "full_strided", CTYPE, [&] {
+    CTYPE value;
+    ET_EXTRACT_SCALAR(fill_value, value);
+    std::fill(
+        tensor->mutable_data_ptr<CTYPE>(),
+        tensor->mutable_data_ptr<CTYPE>() + tensor->numel(),
+        value);
+  });
+  return tensor;
+}
+
+} // namespace extension
+} // namespace executorch