hacks

Author: JacobSzwejbka

backends/cuda/CMakeLists.txt

@@ -47,8 +47,11 @@ set(_aoti_cuda_sources
 # Build as SHARED library (.dll) on Windows MSVC, otherwise STATIC
 if(MSVC)
   add_library(aoti_cuda SHARED ${_aoti_cuda_sources})
-  # Define export macro for Windows DLL
-  target_compile_definitions(aoti_cuda PRIVATE EXPORT_AOTI_FUNCTIONS)
+  # Define export macros for Windows DLL
+  target_compile_definitions(aoti_cuda PRIVATE
+    EXPORT_AOTI_FUNCTIONS
+    BUILDING_CUDA_BACKEND
+  )
   # Ensure proper DLL import/export library naming on Windows with config-specific paths
   set_target_properties(aoti_cuda PROPERTIES
     WINDOWS_EXPORT_ALL_SYMBOLS OFF  # We use explicit exports via AOTI_CUDA_EXPORT

backends/cuda/runtime/cuda_backend.cpp

@@ -21,6 +21,7 @@
 // Include our shim layer headers
 #include <executorch/backends/aoti/aoti_delegate_handle.h>
 #include <executorch/backends/aoti/common_shims.h>
+#include <executorch/backends/cuda/runtime/cuda_backend_init.h>
 #include <executorch/backends/cuda/runtime/platform/platform.h>
 #include <executorch/backends/cuda/runtime/shims/memory.h>
 #include <executorch/backends/cuda/runtime/utils.h>
@@ -383,14 +384,8 @@ static executorch::runtime::Error success_with_compiler =
 
 } // namespace
 
-// Export an initialization function for explicit backend registration
-#ifdef _WIN32
-#define CUDA_BACKEND_INIT_EXPORT __declspec(dllexport)
-#else
-#define CUDA_BACKEND_INIT_EXPORT __attribute__((visibility("default")))
-#endif
-
-extern "C" CUDA_BACKEND_INIT_EXPORT void InitCudaBackend() {
+// InitCudaBackend is exported for explicit backend registration on Windows
+extern "C" CUDA_BACKEND_INIT_API void InitCudaBackend() {
   // Log immediately to confirm function is entered
   ET_LOG(Info, "InitCudaBackend: Function entered");
 

backends/cuda/runtime/cuda_backend_init.h

@@ -0,0 +1,35 @@
+// (c) Meta Platforms, Inc. and affiliates. Confidential and proprietary.
+
+#pragma once
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#ifdef _WIN32
+#define CUDA_BACKEND_INIT_EXPORT __declspec(dllexport)
+#define CUDA_BACKEND_INIT_IMPORT __declspec(dllimport)
+#else
+#define CUDA_BACKEND_INIT_EXPORT __attribute__((visibility("default")))
+#define CUDA_BACKEND_INIT_IMPORT
+#endif
+
+// When building the DLL, define BUILDING_CUDA_BACKEND
+// When using the DLL, this will import the function
+#ifdef BUILDING_CUDA_BACKEND
+#define CUDA_BACKEND_INIT_API CUDA_BACKEND_INIT_EXPORT
+#else
+#define CUDA_BACKEND_INIT_API CUDA_BACKEND_INIT_IMPORT
+#endif
+
+/**
+ * Initialize the CUDA backend and register it with the ExecutorTorch runtime.
+ * On Windows, this must be called explicitly before loading models that use
+ * the CUDA backend. On other platforms, the backend is registered automatically
+ * via static initialization.
+ */
+CUDA_BACKEND_INIT_API void InitCudaBackend();
+
+#ifdef __cplusplus
+}
+#endif

examples/models/voxtral/multimodal.cpp

@@ -282,15 +282,12 @@ MultimodalInput processAudioFile(
 
 } // namespace
 
-// Forward declare the initialization function from aoti_cuda
-#ifdef _WIN32
-extern "C" __declspec(dllimport) void InitCudaBackend();
-#else
-extern "C" void InitCudaBackend();
+#ifdef EXECUTORCH_BUILD_CUDA
+#include <executorch/backends/cuda/runtime/cuda_backend_init.h>
 #endif
 
 int32_t main(int32_t argc, char** argv) {
-#ifdef _WIN32
+#ifdef EXECUTORCH_BUILD_CUDA
   // On Windows, explicitly initialize the CUDA backend to ensure
   // static initializers in the DLL run
   ET_LOG(Info, "About to call InitCudaBackend");