common library for et-aoti-driven operators

Summary:
This diff introduce common functions for all aoti-driven backends under executorch like cuda and mps. 

It contain two major function families: container functions for holding and running aoti programs,. and common shim layers for aoti-lib.

 Worth to note that functions living here should be backend-agnostic. For backend-specific functions please make it live inside each backend directory.

Differential Revision: D83003496

Author: Gasoonjia

backends/aoti/CMakeLists.txt

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+# 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.
+#
+# Build AOTI backend for runtime.
+#
+# ### Editing this file ###
+#
+# This file should be formatted with
+# ~~~
+# cmake-format -i CMakeLists.txt
+# ~~~
+# It should also be cmake-lint clean.
+#
+set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
+
+# Source root directory for executorch.
+if(NOT EXECUTORCH_ROOT)
+  set(EXECUTORCH_ROOT ${CMAKE_CURRENT_SOURCE_DIR}/../..)
+endif()
+
+# Use ExecuTorch's standard way to find PyTorch libraries for AOTI
+include(${EXECUTORCH_ROOT}/tools/cmake/Utils.cmake)
+find_package_torch()
+
+# Common AOTI functionality - combines all AOTI common components
+set(_aoti_common_sources aoti_model_container.cpp common_shims.cpp)
+add_library(aoti_common STATIC ${_aoti_common_sources})
+target_include_directories(
+  aoti_common
+  PUBLIC $<BUILD_INTERFACE:${EXECUTORCH_ROOT}> $<INSTALL_INTERFACE:include>
+         # PyTorch AOTI headers from ExecuTorch's torch detection
+         ${TORCH_INCLUDE_DIRS}
+)
+target_compile_options(aoti_common PUBLIC -fexceptions -frtti -fPIC)
+# Ensure symbols are exported properly
+target_link_options(aoti_common PUBLIC -Wl,--export-dynamic)
+
+# Link against PyTorch libraries and standard libraries
+target_link_libraries(
+  aoti_common
+  PUBLIC extension_tensor ${CMAKE_DL_LIBS}
+         # Link PyTorch libraries for AOTI functions
+         ${TORCH_LIBRARIES}
+)
+executorch_target_link_options_shared_lib(aoti_common)
+
+install(
+  TARGETS aoti_common
+  EXPORT ExecuTorchTargets
+  DESTINATION lib
+)

backends/aoti/README.md

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+# AOTI Common Library
+
+This directory contains **common library components** for AOTI (Ahead-of-Time Inference) driven backends in ExecutorTorch, **not a standalone backend**.
+
+## Purpose
+
+The code in this directory provides shared functionality and utilities that are used by actual AOTI-driven backends such as:
+
+- **CUDA backend** - Uses AOTI for GPU acceleration
+- Other AOTI-powered backends
+
+## Components
+
+- **`common_shims.cpp/h`** - Common shim functions that bridge ExecuTorch tensor operations with AOTI requirements
+- **`aoti_model_container.cpp/h`** - Model container functionality for AOTI models
+- **`utils.h`** - Utility functions and type definitions
+- **`tests/`** - Unit tests for the common functionality
+
+## Usage
+
+This library is intended to be used as a dependency by actual AOTI backend implementations. It is not a backend that can be used directly for model execution.
+
+For example backend implementations that use this common library, see:
+- `executorch/backends/cuda/` - CUDA AOTI backend
+
+## Building
+
+The common library components are built as part of the AOTI backend build process. See the `TARGETS` file for build configurations.

backends/aoti/TARGETS

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+load("targets.bzl", "define_common_targets")
+
+define_common_targets()

backends/aoti/aoti_model_container.cpp

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+/*
+ * 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/backends/aoti/aoti_model_container.h>
+
+namespace executorch {
+namespace backends {
+namespace aoti {
+
+extern "C" {
+
+// Global function pointers for AOT Inductor model container operations
+// These will be loaded dynamically from the shared library
+AOTInductorModelContainerCreateWithDeviceFunc
+    AOTInductorModelContainerCreateWithDevice = nullptr;
+AOTInductorModelContainerDeleteFunc AOTInductorModelContainerDelete = nullptr;
+AOTInductorModelContainerGetNumInputsFunc
+    AOTInductorModelContainerGetNumInputs = nullptr;
+AOTInductorModelContainerGetNumOutputsFunc
+    AOTInductorModelContainerGetNumOutputs = nullptr;
+AOTInductorModelContainerRunFunc AOTInductorModelContainerRun = nullptr;
+
+} // extern "C"
+
+} // namespace aoti
+} // namespace backends
+} // namespace executorch

backends/aoti/aoti_model_container.h

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+/*
+ * 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.
+ */
+
+#pragma once
+
+#include <executorch/extension/tensor/tensor.h>
+#include <executorch/runtime/core/error.h>
+
+namespace executorch {
+namespace backends {
+namespace aoti {
+
+using executorch::runtime::Error;
+using executorch::runtime::etensor::Tensor;
+
+extern "C" {
+
+// Type definitions
+using AOTITensorHandle = Tensor*;
+using AOTIRuntimeError = Error;
+
+// Forward declarations for AOT Inductor model container
+struct AOTInductorModelContainerOpaque;
+using AOTInductorModelContainerHandle = AOTInductorModelContainerOpaque*;
+using AOTInductorStreamHandle = void*;
+using AOTIProxyExecutorHandle = void*;
+
+// Function pointer types for AOT Inductor model container operations
+using AOTInductorModelContainerCreateWithDeviceFunc = AOTIRuntimeError (*)(
+    AOTInductorModelContainerHandle* container_handle,
+    size_t num_models,
+    const char* device_str,
+    const char* cubin_dir);
+
+using AOTInductorModelContainerDeleteFunc =
+    AOTIRuntimeError (*)(AOTInductorModelContainerHandle container_handle);
+
+using AOTInductorModelContainerGetNumInputsFunc = AOTIRuntimeError (*)(
+    AOTInductorModelContainerHandle container_handle,
+    size_t* num_inputs);
+
+using AOTInductorModelContainerGetNumOutputsFunc = AOTIRuntimeError (*)(
+    AOTInductorModelContainerHandle container_handle,
+    size_t* num_outputs);
+
+using AOTInductorModelContainerRunFunc = AOTIRuntimeError (*)(
+    AOTInductorModelContainerHandle container_handle,
+    AOTITensorHandle* input_handles, // array of input AOTITensorHandle; handles
+                                     // are stolen; the array itself is borrowed
+    size_t num_inputs,
+    AOTITensorHandle*
+        output_handles, // array for writing output AOTITensorHandle; handles
+                        // will be stolen by the caller; the array itself is
+                        // borrowed
+    size_t n_outputs,
+    AOTInductorStreamHandle stream_handle,
+    AOTIProxyExecutorHandle proxy_executor_handle);
+
+// Global function pointers (will be loaded dynamically)
+extern AOTInductorModelContainerCreateWithDeviceFunc
+    AOTInductorModelContainerCreateWithDevice;
+extern AOTInductorModelContainerDeleteFunc AOTInductorModelContainerDelete;
+extern AOTInductorModelContainerGetNumInputsFunc
+    AOTInductorModelContainerGetNumInputs;
+extern AOTInductorModelContainerGetNumOutputsFunc
+    AOTInductorModelContainerGetNumOutputs;
+extern AOTInductorModelContainerRunFunc AOTInductorModelContainerRun;
+
+} // extern "C"
+
+// AOTI Delegate Handle structure
+struct AOTIDelegateHandle {
+  void* so_handle;
+  AOTInductorModelContainerHandle container_handle;
+};
+
+} // namespace aoti
+} // namespace backends
+} // namespace executorch

backends/aoti/common_shims.cpp

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+/*
+ * 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/backends/aoti/common_shims.h>
+#include <executorch/runtime/platform/log.h>
+#include <cstdint>
+
+namespace executorch {
+namespace backends {
+namespace aoti {
+
+namespace internal {
+
+// Global storage for tensor metadata
+std::unordered_map<Tensor*, std::vector<int64_t>> tensor_to_sizes;
+std::unordered_map<Tensor*, std::vector<int64_t>> tensor_to_strides;
+} // namespace internal
+
+extern "C" {
+
+// Autograd mode functions
+int32_t aoti_torch_grad_mode_is_enabled() {
+  // No autograd ever
+  return false;
+}
+
+void aoti_torch_grad_mode_set_enabled(bool enabled) {
+  if (enabled) {
+    throw std::runtime_error("Cannot enable autograd");
+  }
+}
+
+// Tensor attribute operations
+AOTITorchError aoti_torch_get_data_ptr(
+    AOTITensorHandle tensor,
+    void** ret_data_ptr) {
+  *ret_data_ptr = tensor->mutable_data_ptr();
+  return Error::Ok;
+}
+
+AOTITorchError aoti_torch_get_storage_offset(
+    AOTITensorHandle tensor,
+    int64_t* ret_storage_offset) {
+  // Storage offset is always 0 in ET
+  *ret_storage_offset = 0;
+
+  return Error::Ok;
+}
+
+AOTITorchError aoti_torch_get_strides(
+    AOTITensorHandle tensor,
+    int64_t** ret_strides) {
+  auto it = internal::tensor_to_strides.find(tensor);
+  if (it == internal::tensor_to_strides.end()) {
+    std::vector<int64_t> strides(tensor->dim());
+    auto tensor_strides = tensor->strides();
+    for (int i = 0; i < tensor->dim(); i++) {
+      strides[i] = tensor_strides[i];
+    }
+    it = internal::tensor_to_strides.emplace(tensor, std::move(strides)).first;
+  }
+
+  // For 0D tensors, data() returns nullptr on empty vectors, but we need to
+  // return a valid pointer
+  if (it->second.empty()) {
+    static int64_t empty_strides_placeholder = 0;
+    *ret_strides = &empty_strides_placeholder;
+  } else {
+    *ret_strides = it->second.data();
+  }
+
+  return Error::Ok;
+}
+
+AOTITorchError aoti_torch_get_dtype(
+    AOTITensorHandle tensor,
+    int32_t* ret_dtype) {
+  *ret_dtype = static_cast<int32_t>(tensor->scalar_type());
+
+  return Error::Ok;
+}
+
+AOTITorchError aoti_torch_get_sizes(
+    AOTITensorHandle tensor,
+    int64_t** ret_sizes) {
+  auto it = internal::tensor_to_sizes.find(tensor);
+  if (it == internal::tensor_to_sizes.end()) {
+    std::vector<int64_t> sizes(tensor->dim());
+    auto tensor_sizes = tensor->sizes();
+    for (int i = 0; i < tensor->dim(); i++) {
+      sizes[i] = tensor_sizes[i];
+    }
+    it = internal::tensor_to_sizes.emplace(tensor, std::move(sizes)).first;
+  }
+
+  // For 0D tensors, data() returns nullptr on empty vectors, but we need to
+  // return a valid pointer
+  if (it->second.empty()) {
+    static int64_t empty_sizes_placeholder = 0;
+    *ret_sizes = &empty_sizes_placeholder;
+  } else {
+    *ret_sizes = it->second.data();
+  }
+
+  return Error::Ok;
+}
+
+AOTITorchError aoti_torch_get_storage_size(
+    AOTITensorHandle tensor,
+    int64_t* ret_size) {
+  return Error::NotSupported;
+}
+
+AOTITorchError aoti_torch_get_device_index(
+    AOTITensorHandle tensor,
+    int32_t* ret_device_index) {
+  // Let's assume all tensors AOTI using are on CUDA:0
+  *ret_device_index = 0;
+  return Error::Ok;
+}
+
+AOTITorchError aoti_torch_get_dim(AOTITensorHandle tensor, int64_t* ret_dim) {
+  *ret_dim = static_cast<int64_t>(tensor->dim());
+  return Error::Ok;
+}
+
+// Device and layout utility functions
+int32_t aoti_torch_device_type_cpu() {
+  // Let's say cpu is 0 for ET as well
+  return 0;
+}
+
+__attribute__((__visibility__("default"))) int32_t aoti_torch_layout_strided() {
+  // ET only support strided layout, the return value will always be 0, a.k.a
+  // at::Layout::Strided;
+  return 0;
+}
+
+// Dtype constants - these return the PyTorch dtype codes
+// Currently only float32 is supported, but using robust enum-based approach
+__attribute__((__visibility__("default"))) int32_t aoti_torch_dtype_float32() {
+  return 6; // PyTorch's float32 dtype code
+}
+
+// Cleanup functions
+void cleanup_tensor_metadata() {
+  internal::tensor_to_sizes.clear();
+  internal::tensor_to_strides.clear();
+}
+
+} // extern "C"
+
+} // namespace aoti
+} // namespace backends
+} // namespace executorch