vTensor cleanup 2/N - remove discard_and_reallocate API (pytorch#5422)

Summary:
Pull Request resolved: pytorch#5422

## Context

Remove the unused `discard_and_reallocate()` API. The purpose of this AP is to allow a `vTensor` instance to request a new memory allocation when being resized to a larger size than what the current memory allocation can support.

This was originally intended to support unbounded dynamic shapes in the ExecuTorch Vulkan delegate, but it is unlikely that this functionality will ever be used. The reason is that re-allocating memory would require re-encoding the command buffer, which goes against the execution philosophy of the Vulkan delegate (encode command buffer once, submit repeatedly).
ghstack-source-id: 243061031
exported-using-ghexport

Reviewed By: jorgep31415

Differential Revision: D62878649

fbshipit-source-id: e293fe2dfcbbec8c615370a370db14424b971369

Author: SS-JIA

backends/vulkan/runtime/api/containers/Tensor.cpp

@@ -396,30 +396,6 @@ bool vTensorStorage::is_copy_of(const vTensorStorage& other) const {
   return image_.is_copy_of(other.image_);
 }
 
-void vTensorStorage::discard_and_reallocate(
-    const std::vector<int64_t>& padded_sizes,
-    const std::vector<int64_t>& axis_map,
-    const utils::GPUMemoryLayout gpu_memory_layout,
-    const vkapi::ScalarType dtype) {
-  const bool image_owns_memory = image_.owns_memory();
-  const bool buffer_owns_memory = buffer_.owns_memory();
-
-  flush();
-
-  image_extents_ =
-      calculate_image_extents(padded_sizes, axis_map, gpu_memory_layout);
-  image_ = allocate_image(
-      context_,
-      image_extents_,
-      storage_type_,
-      to_vkformat(dtype),
-      image_owns_memory);
-
-  buffer_length_ = utils::multiply_integers(padded_sizes);
-  buffer_ = allocate_buffer(
-      context_, buffer_length_, storage_type_, dtype, buffer_owns_memory);
-}
-
 //
 // vTensor
 //
@@ -805,15 +781,5 @@ void vTensor::virtual_transpose(const int64_t dim0, const int64_t dim1) {
   update_metadata();
 }
 
-void vTensor::reallocate(const std::vector<int64_t>& new_sizes) {
-  sizes_ = new_sizes;
-  update_metadata();
-  storage_.discard_and_reallocate(
-      calculate_padded_sizes(new_sizes, memory_layout_),
-      axis_map_,
-      memory_layout_,
-      dtype_);
-}
-
 } // namespace api
 } // namespace vkcompute

backends/vulkan/runtime/api/containers/Tensor.h

@@ -157,12 +157,6 @@ class vTensorStorage final {
    * Used for checking if this vTensorStorage is a copy of another instance
    */
   bool is_copy_of(const vTensorStorage& other) const;
-
-  void discard_and_reallocate(
-      const std::vector<int64_t>& padded_sizes,
-      const std::vector<int64_t>& axis_map,
-      const utils::GPUMemoryLayout gpu_memory_layout,
-      const vkapi::ScalarType dtype);
 };
 
 class vTensor final {
@@ -535,12 +529,6 @@ class vTensor final {
    */
   void virtual_transpose(const int64_t dim0, const int64_t dim1);
 
-  /*
-   * Discard the underlying VkImage or VkBuffer and re-allocate based on new
-   * tensor sizes
-   */
-  void reallocate(const std::vector<int64_t>& new_sizes);
-
   /*
    * Check if this vTensor instance is a view of another vTensor instance
    */

backends/vulkan/test/vulkan_compute_api_test.cpp

@@ -940,64 +940,6 @@ TEST_F(VulkanComputeAPITest, use_non_bound_textures_fails) {
   EXPECT_THROW(fill_vtensor(a, data_a), vkapi::Error);
 }
 
-TEST_F(VulkanComputeAPITest, tensor_reallocation_test) {
-  std::vector<int64_t> sizes = {4, 4, 1};
-  vTensor a = CREATE_FLOAT_TEXTURE(sizes, /*allocate_memory = */ true);
-  vTensor b = CREATE_FLOAT_TEXTURE(sizes, /*allocate_memory = */ true);
-  vTensor c = CREATE_FLOAT_TEXTURE(sizes, /*allocate_memory = */ true);
-
-  execute_and_check_add(a, b, c, 3.0f, 5.0f);
-
-  // Redo with new sizes
-  std::vector<int64_t> new_sizes = {4, 6, 3};
-  a.reallocate(new_sizes);
-  b.reallocate(new_sizes);
-  c.reallocate(new_sizes);
-
-  // Flush everything
-  context()->flush();
-
-  execute_and_check_add(a, b, c, 12.0f, 10.0f);
-}
-
-TEST_F(
-    VulkanComputeAPITest,
-    tensor_reallocation_with_deferred_allocation_test) {
-  std::vector<int64_t> sizes = {8, 8, 8};
-  vTensor a = CREATE_FLOAT_TEXTURE(sizes, /*allocate_memory = */ false);
-  vTensor b = CREATE_FLOAT_TEXTURE(sizes, /*allocate_memory = */ false);
-  vTensor c = CREATE_FLOAT_TEXTURE(sizes, /*allocate_memory = */ false);
-
-  vkapi::Allocation a_mem = allocate_memory_for(a);
-  a.image().bind_allocation(a_mem);
-  vkapi::Allocation b_mem = allocate_memory_for(b);
-  b.image().bind_allocation(b_mem);
-  vkapi::Allocation c_mem = allocate_memory_for(c);
-  c.image().bind_allocation(c_mem);
-
-  execute_and_check_add(a, b, c, 4.0f, 8.0f);
-
-  std::vector<std::vector<int64_t>> new_sizes_list = {
-      {4, 3, 5}, {4, 1, 7}, {8, 3, 2}, {8, 7, 2}};
-
-  for (auto& new_sizes : new_sizes_list) {
-    // Redo with new sizes
-    a.reallocate(new_sizes);
-    b.reallocate(new_sizes);
-    c.reallocate(new_sizes);
-
-    // Flush everything
-    context()->flush();
-
-    a.image().bind_allocation(a_mem);
-    b.image().bind_allocation(b_mem);
-    c.image().bind_allocation(c_mem);
-
-    execute_and_check_add(
-        a, b, c, float(new_sizes[1] + 4.5f), float(new_sizes[2] + 13.0f));
-  }
-}
-
 TEST_F(VulkanComputeAPITest, texture_virtual_resize) {
   context()->set_cmd(/*reusable = */ true);
   std::vector<int64_t> sizes = {8, 12, 12};