feat: add PrivateUse1 backend extension support

CMakeLists.txt

@@ -41,7 +41,15 @@ include_directories(${gflags_SOURCE_DIR}/include)
 # glog
 set(WITH_GFLAGS OFF CACHE BOOL "Disable glog finding system gflags" FORCE)
 set(WITH_GTEST OFF CACHE BOOL "Disable glog finding system gtest" FORCE)
-add_subdirectory(third_party/glog)
+get_property(_infinitrain_build_testing_was_cached CACHE BUILD_TESTING PROPERTY TYPE SET)
+block()
+  set(BUILD_TESTING OFF)
+  add_subdirectory(third_party/glog)
+endblock()
+if(NOT _infinitrain_build_testing_was_cached)
+  unset(BUILD_TESTING CACHE)
+endif()
+unset(_infinitrain_build_testing_was_cached)
 include_directories(${glog_SOURCE_DIR}/src)
 
 # eigen
@@ -131,19 +139,27 @@ endif()
 # ------------------------------------------------------------------------------
 
 add_library(infini_train STATIC ${SRC})
+add_library(InfiniTrain::infini_train ALIAS infini_train)
+add_library(InfiniTrain::cpu_kernels ALIAS infini_train_cpu_kernels)
+target_compile_features(infini_train PUBLIC cxx_std_20)
+target_include_directories(infini_train PUBLIC
+  "$<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}>"
+)
 target_link_libraries(infini_train
   PUBLIC
     glog
     gflags
-    infini_train_cpu_kernels
+    Eigen3::Eigen
 )
+if(USE_OMP)
+  target_link_libraries(infini_train PUBLIC OpenMP::OpenMP_CXX)
+endif()
 
 if(USE_CUDA)
   # infini_train contains cuda runtime wrappers (*.cc) like cuda_blas_handle.cc/cuda_guard.cc
   # Those may need CUDA runtime/driver/cublas symbols at final link, so attach them here too.
   target_link_libraries(infini_train
     PUBLIC
-      infini_train_cuda_kernels
       CUDA::cudart
       CUDA::cublas
       CUDA::cuda_driver
@@ -157,37 +173,66 @@ if(USE_CUDA)
 endif()
 
 # ------------------------------------------------------------------------------
-# Helper: link libraries in a group to fix static lib one-pass resolution
-# (THIS is what fixes "undefined reference" from cuda_kernels -> core symbols)
+# Final executable link interface
 # ------------------------------------------------------------------------------
+
+set(_infini_train_executable_archives
+  infini_train
+  infini_train_cpu_kernels
+)
+if(USE_CUDA)
+  list(APPEND _infini_train_executable_archives infini_train_cuda_kernels)
+endif()
+set_property(GLOBAL PROPERTY INFINI_TRAIN_EXECUTABLE_ARCHIVES
+  ${_infini_train_executable_archives})
+
 function(link_infini_train_exe target_name)
-  if(USE_CUDA)
-    target_link_libraries(${target_name} PRIVATE
-      "-Wl,--start-group"
-      "-Wl,--whole-archive"
-        infini_train
-        infini_train_cpu_kernels
-        infini_train_cuda_kernels
-      "-Wl,--no-whole-archive"
-      "-Wl,--end-group"
-    )
+  cmake_parse_arguments(LINK "" "" "EXTRA_ARCHIVES" ${ARGN})
+  if(LINK_KEYWORDS_MISSING_VALUES)
+    message(FATAL_ERROR
+      "link_infini_train_exe: missing values for ${LINK_KEYWORDS_MISSING_VALUES}")
+  endif()
+  if(LINK_UNPARSED_ARGUMENTS)
+    message(FATAL_ERROR
+      "link_infini_train_exe: unexpected arguments: ${LINK_UNPARSED_ARGUMENTS}")
+  endif()
+
+  get_target_property(_target_type ${target_name} TYPE)
+  if(_target_type STREQUAL "INTERFACE_LIBRARY")
+    set(_link_scope INTERFACE)
+  elseif(_target_type STREQUAL "EXECUTABLE")
+    set(_link_scope PRIVATE)
   else()
-    target_link_libraries(${target_name} PRIVATE
-      "-Wl,--start-group"
-      "-Wl,--whole-archive"
-        infini_train
-        infini_train_cpu_kernels
-      "-Wl,--no-whole-archive"
-      "-Wl,--end-group"
-    )
+    message(FATAL_ERROR
+      "link_infini_train_exe requires an executable or interface library target")
   endif()
+
+  get_property(_framework_archives GLOBAL PROPERTY INFINI_TRAIN_EXECUTABLE_ARCHIVES)
+  target_link_libraries(${target_name} ${_link_scope}
+    "-Wl,--start-group"
+    "-Wl,--whole-archive"
+    ${_framework_archives}
+    ${LINK_EXTRA_ARCHIVES}
+    "-Wl,--no-whole-archive"
+    "-Wl,--end-group"
+  )
 endfunction()
 
+# Libraries and providers link InfiniTrain::infini_train for the core API. Final
+# executables must link InfiniTrain::infini_train_executable or a provider-specific
+# executable interface; linking only InfiniTrain::infini_train may discard static
+# registration objects.
+# EXTRA_ARCHIVES is reserved for archives that still rely on static initialization.
+add_library(infini_train_executable INTERFACE)
+link_infini_train_exe(infini_train_executable)
+add_library(InfiniTrain::infini_train_executable ALIAS infini_train_executable)
+unset(_infini_train_executable_archives)
 
 # ------------------------------------------------------------------------------
 # Examples
 # ------------------------------------------------------------------------------
 
+if(PROJECT_IS_TOP_LEVEL)
 add_executable(mnist
   example/mnist/main.cc
   example/mnist/dataset.cc
@@ -220,10 +265,13 @@ add_executable(llama3
   example/llama3/checkpoint_loader.cc
 )
 link_infini_train_exe(llama3)
+endif()
 
 # Tools
+if(PROJECT_IS_TOP_LEVEL)
 add_subdirectory(tools/infini_run)
 set_target_properties(infini_run PROPERTIES RUNTIME_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR})
+endif()
 
 # Tests
 if(BUILD_TEST)