Neuron buffer allocator decouple from ExecuTorch framework (#8760)

### Summary
1. Decouple out Neuron buffer allocator as a standalone shared library
2. Refactor and update the build scripts
3. Pending the release of the new buffer allocator lib

Fixes #6074 
Fixes #7549 
Fixes #10389 

cc @cccclai @cbilgin

---------

Co-authored-by: neuropilot-captain <[email protected]>
Co-authored-by: Poyuan Jeng <[email protected]>
Co-authored-by: cccclai <[email protected]>

Author: 4 people

backends/mediatek/CMakeLists.txt

@@ -10,13 +10,11 @@
 
 # Let include directory as "executorch/..."
 set(_common_include_directories ${CMAKE_CURRENT_SOURCE_DIR}/../../..)
-set(NEURON_BUFFER_ALLOCATOR_LIB
-    ""
-    CACHE PATH "Path to Neuron Buffer Allocator library"
-)
-message(
-  STATUS "Looking for neuron_buffer_allocator in ${NEURON_BUFFER_ALLOCATOR_LIB}"
-)
+
+if(EXECUTORCH_BUILD_NEURON_BUFFER_ALLOCATOR)
+  message(STATUS "Neuron buffer allocator Build is enabled")
+  add_subdirectory(runtime/proprietary)
+endif()
 
 include_directories(BEFORE ${_common_include_directories})
 
@@ -31,7 +29,6 @@ target_link_libraries(neuron_backend
     executorch_core
     android
     log
-    ${NEURON_BUFFER_ALLOCATOR_LIB}
 )
 target_sources(
   neuron_backend
@@ -43,6 +40,7 @@ target_sources(
             ${CMAKE_CURRENT_LIST_DIR}/runtime/include/api/NeuronAdapterShim.h
   PRIVATE ${CMAKE_CURRENT_LIST_DIR}/runtime/NeuronBackend.cpp
           ${CMAKE_CURRENT_LIST_DIR}/runtime/NeuronExecutor.cpp
+          ${CMAKE_CURRENT_LIST_DIR}/runtime/NeuronBufferAllocator.cpp
 )
 target_link_options_shared_lib(neuron_backend)
 

backends/mediatek/runtime/NeuronBackend.cpp

@@ -111,8 +111,8 @@ Error NeuronExecuTorchDelegate::execute(
     return Error::InvalidState;
   };
 
-  auto allocator = dynamic_cast<torch::executor::neuron::BufferAllocator*>(
-      context.get_temp_allocator());
+  auto allocator =
+      dynamic_cast<neuron::BufferAllocator*>(context.get_temp_allocator());
   size_t inputCount = mInputSizes.size(), outputCount = mOutputSizes.size();
 
   for (int i = 0; i < inputCount; i++) {

backends/mediatek/runtime/NeuronBufferAllocator.cpp

@@ -0,0 +1,89 @@
+/*
+ * Copyright (c) 2025 MediaTek Inc.
+ *
+ * Licensed under the BSD License (the "License"); you may not use this file
+ * except in compliance with the License. See the license file in the root
+ * directory of this source tree for more details.
+ */
+
+#include "include/NeuronBufferAllocator.h"
+
+#include <algorithm>
+#include <cstddef>
+#include <mutex>
+
+namespace executorch {
+namespace backends {
+namespace neuron {
+
+bool loadLibrary() {
+  handle = dlopen("libneuron_buffer_allocator.so", RTLD_LAZY);
+  if (!handle) {
+    std::cerr << "Failed to load library: " << dlerror() << std::endl;
+    return false;
+  }
+
+  create_func = (CreateFunc)dlsym(handle, "neuron_buffer_allocator_create");
+  allocate_func = (AllocateFunc)dlsym(handle, "neuron_buffer_allocate");
+  remove_func = (RemoveFunc)dlsym(handle, "neuron_buffer_remove");
+  find_func = (FindFunc)dlsym(handle, "neuron_buffer_find");
+  clear_func = (ClearFunc)dlsym(handle, "neuron_buffer_clear");
+
+  if (!create_func || !allocate_func || !remove_func || !find_func ||
+      !clear_func) {
+    std::cerr << "Failed to retrieve symbols: " << dlerror() << std::endl;
+    dlclose(handle);
+    handle = nullptr;
+    return false;
+  }
+
+  return true;
+}
+
+void unloadLibrary() {
+  if (handle) {
+    dlclose(handle);
+    handle = nullptr;
+  }
+}
+
+BufferAllocator& BufferAllocator::GetInstance() {
+  static BufferAllocator instance;
+
+  if (handle == nullptr) {
+    loadLibrary();
+    if (allocatorHandle == nullptr) {
+      allocatorHandle = create_func();
+    }
+  }
+
+  return instance;
+};
+
+void* BufferAllocator::Allocate(size_t size) {
+  std::scoped_lock Guard(mMutex);
+  return allocate_func(allocatorHandle, size);
+}
+
+bool BufferAllocator::RemoveBuffer(void* address) {
+  std::scoped_lock Guard(mMutex);
+  return remove_func(allocatorHandle, address);
+}
+
+const MemoryUnit* BufferAllocator::Find(void* address) {
+  std::scoped_lock Guard(mMutex);
+  return static_cast<const MemoryUnit*>(find_func(allocatorHandle, address));
+}
+
+void BufferAllocator::Clear() {
+  std::scoped_lock Guard(mMutex);
+  clear_func(allocatorHandle);
+}
+
+} // namespace neuron
+} // namespace backends
+} // namespace executorch
+
+namespace {
+static auto& singletonInstance = GET_NEURON_ALLOCATOR;
+} // namespace

backends/mediatek/runtime/include/NeuronBufferAllocator.h

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2024 MediaTek Inc.
+ * Copyright (c) 2025 MediaTek Inc.
  *
  * Licensed under the BSD License (the "License"); you may not use this file
  * except in compliance with the License. See the license file in the root
@@ -16,18 +16,33 @@
 
 #include <executorch/runtime/core/memory_allocator.h>
 
+#include <dlfcn.h>
+#include <iostream>
 #include <map>
 #include <memory>
 #include <mutex>
 #include <new>
 
 #define GET_NEURON_ALLOCATOR \
-  ::torch::executor::neuron::BufferAllocator::GetInstance()
-
-// TODO: Move this code to the executorch::backends::neuron namespace.
-// The torch:: namespace is deprecated for ExecuTorch code.
-namespace torch {
-namespace executor {
+  ::executorch::backends::neuron::BufferAllocator::GetInstance()
+
+// Define the types for the function pointers
+typedef void* (*CreateFunc)();
+typedef void* (*AllocateFunc)(void*, size_t);
+typedef bool (*RemoveFunc)(void*, void*);
+typedef const void* (*FindFunc)(void*, void*);
+typedef void (*ClearFunc)(void*);
+
+static CreateFunc create_func = nullptr;
+static AllocateFunc allocate_func = nullptr;
+static RemoveFunc remove_func = nullptr;
+static FindFunc find_func = nullptr;
+static ClearFunc clear_func = nullptr;
+static void* handle = nullptr;
+static void* allocatorHandle = nullptr;
+
+namespace executorch {
+namespace backends {
 namespace neuron {
 
 struct BufferDeleter {
@@ -135,11 +150,9 @@ class BufferAllocator : public executorch::runtime::MemoryAllocator {
   }
 
  private:
-  std::map<void*, std::unique_ptr<MemoryUnit>> mPool;
-
   std::mutex mMutex;
 };
 
 } // namespace neuron
-} // namespace executor
-} // namespace torch
+} // namespace backends
+} // namespace executorch

backends/mediatek/scripts/mtk_build.sh

@@ -18,29 +18,24 @@ if [ -z "$ANDROID_NDK" ]; then
     exit 1
 fi
 
-# Check if the NEURON_BUFFER_ALLOCATOR_LIB environment variable is set
-if [ -z "$NEURON_BUFFER_ALLOCATOR_LIB" ]; then
-    echo "Error: NEURON_BUFFER_ALLOCATOR_LIB environment variable is not set." >&2
-    exit 1
-fi
-
 # Create and enter the build directory
+# Set build directory
+build_dir="cmake-android-out"
 cd "$SOURCE_DIR"
-rm -rf cmake-android-out && mkdir cmake-android-out && cd cmake-android-out
+rm -rf "${build_dir}"
 
 # Configure the project with CMake
 # Note: Add any additional configuration options you need here
-cmake -DBUCK2="$BUCK_PATH" \
+cmake -DCMAKE_INSTALL_PREFIX="${build_dir}" \
       -DCMAKE_TOOLCHAIN_FILE="$ANDROID_NDK/build/cmake/android.toolchain.cmake" \
       -DANDROID_ABI=arm64-v8a \
+      -DANDROID_NATIVE_API_LEVEL=26 \
       -DANDROID_PLATFORM=android-26 \
       -DEXECUTORCH_BUILD_NEURON=ON \
-      -DNEURON_BUFFER_ALLOCATOR_LIB="$NEURON_BUFFER_ALLOCATOR_LIB" \
-      ..
+      -B"${build_dir}"
 
 # Build the project
-cd ..
-cmake --build cmake-android-out -j4
+cmake --build "${build_dir}" --target install --config Release -j5
 
 # Switch back to the original directory
 cd - > /dev/null

examples/mediatek/CMakeLists.txt

@@ -167,7 +167,6 @@ if(${ANDROID})
   target_link_libraries(
     mtk_llama_executor_runner
     ${_executor_runner_libs}
-    ${NEURON_BUFFER_ALLOCATOR_LIB}
     neuron_backend
     gflags
     mtk_llama_executor_lib

examples/mediatek/mtk_build_examples.sh

@@ -19,12 +19,6 @@ if [ -z "$ANDROID_NDK" ]; then
     exit 1
 fi
 
-# Check if the NEURON_BUFFER_ALLOCATOR_LIB environment variable is set
-if [ -z "$NEURON_BUFFER_ALLOCATOR_LIB" ]; then
-    echo "Error: NEURON_BUFFER_ALLOCATOR_LIB environment variable is not set." >&2
-    exit 1
-fi
-
 main() {
     # Set build directory
     local build_dir="cmake-android-out"
@@ -39,15 +33,14 @@ main() {
           -DBUCK2="$BUCK_PATH" \
           -DCMAKE_TOOLCHAIN_FILE="$ANDROID_NDK/build/cmake/android.toolchain.cmake" \
           -DANDROID_ABI=arm64-v8a \
+          -DANDROID_NATIVE_API_LEVEL=26 \
           -DANDROID_PLATFORM=android-26 \
-          -DANDROID_NATIVE_API_LEVEL=23 \
           -DEXECUTORCH_BUILD_NEURON=ON \
-          -DNEURON_BUFFER_ALLOCATOR_LIB="$NEURON_BUFFER_ALLOCATOR_LIB" \
           -B"${build_dir}"
 
 
     # Build the project
-    cmake --build cmake-android-out --target install --config Release -j5
+    cmake --build "${build_dir}" --target install --config Release -j5
 
     ## Build example
     local example_dir=examples/mediatek
@@ -59,6 +52,7 @@ main() {
     cmake -DCMAKE_PREFIX_PATH="${cmake_prefix_path}" \
           -DCMAKE_TOOLCHAIN_FILE="$ANDROID_NDK/build/cmake/android.toolchain.cmake" \
           -DANDROID_ABI=arm64-v8a \
+          -DANDROID_NATIVE_API_LEVEL=26 \
           -DANDROID_PLATFORM=android-26 \
           -DCMAKE_FIND_ROOT_PATH_MODE_PACKAGE=BOTH \
           -DNEURON_BUFFER_ALLOCATOR_LIB="$NEURON_BUFFER_ALLOCATOR_LIB" \