Be able to compile in offline mode (pytorch#7305)

Author: mergennachin

.gitignore

@@ -1,5 +1,6 @@
 .hypothesis
 buck-out/
+buck2-bin/
 cmake-out*
 .DS_Store
 cmake-android-out/

CMakeLists.txt

@@ -257,6 +257,17 @@ if(EXECUTORCH_BUILD_KERNELS_CUSTOM)
   set(EXECUTORCH_BUILD_KERNELS_OPTIMIZED ON)
 endif()
 
+if(NOT DEFINED FXDIV_SOURCE_DIR)
+  set(ORIGINAL_CMAKE_POSITION_INDEPENDENT_CODE_FLAG
+    ${CMAKE_POSITION_INDEPENDENT_CODE}
+  )
+  set(FXDIV_SOURCE_DIR "backends/xnnpack/third-party/FXdiv")
+  add_subdirectory("${FXDIV_SOURCE_DIR}")
+  set(CMAKE_POSITION_INDEPENDENT_CODE
+      ${ORIGINAL_CMAKE_POSITION_INDEPENDENT_CODE_FLAG}
+  )
+endif()
+
 if(EXECUTORCH_BUILD_CPUINFO)
   # --- cpuinfo
   set(ORIGINAL_CMAKE_POSITION_INDEPENDENT_CODE_FLAG

build/Utils.cmake

@@ -235,7 +235,7 @@ function(resolve_buck2)
 
   set(resolve_buck2_command
       ${PYTHON_EXECUTABLE} ${executorch_root}/build/resolve_buck.py
-      --cache_dir=${CMAKE_CURRENT_BINARY_DIR}/buck2-bin
+      --cache_dir=buck2-bin
   )
 
   if(NOT ${BUCK2} STREQUAL "")