From d8451a9048d09692994c40a6f9bc928e70ed79b5 Mon Sep 17 00:00:00 2001
From: James Hilliard <james.hilliard1@gmail.com>
Date: Mon, 28 Nov 2022 21:36:34 -0700
Subject: [PATCH] Add SYSTEM_FARMHASH cmake config flag

Since farmhash does not install a cmake package we need to
search for the library and headers to use the provided
version.

Signed-off-by: James Hilliard <james.hilliard1@gmail.com>
[james.hilliard1@gmail.com: backport from upstream commit
d8451a9048d09692994c40a6f9bc928e70ed79b5]
---
 tensorflow/lite/g3doc/guide/build_cmake.md    |  1 +
 .../tools/cmake/modules/Findfarmhash.cmake    | 30 +++++++++++++++----
 2 files changed, 26 insertions(+), 5 deletions(-)

diff --git a/tensorflow/lite/g3doc/guide/build_cmake.md b/tensorflow/lite/g3doc/guide/build_cmake.md
index 6950a365bb8..6de955e70b0 100644
--- a/tensorflow/lite/g3doc/guide/build_cmake.md
+++ b/tensorflow/lite/g3doc/guide/build_cmake.md
@@ -81,6 +81,7 @@ variables to point to your library installations.
 ```sh
 cmake ../tensorflow_src/tensorflow/lite -DTFLITE_ENABLE_INSTALL=ON \
   -DCMAKE_FIND_PACKAGE_PREFER_CONFIG=ON \
+  -DSYSTEM_FARMHASH=ON \
   -Dabsl_DIR=<install path>/lib/cmake/absl \
   -DEigen3_DIR=<install path>/share/eigen3/cmake \
   -DFlatbuffers_DIR=<install path>/lib/cmake/flatbuffers \
diff --git a/tensorflow/lite/tools/cmake/modules/Findfarmhash.cmake b/tensorflow/lite/tools/cmake/modules/Findfarmhash.cmake
index 1b0dc28f624..97b43298f13 100644
--- a/tensorflow/lite/tools/cmake/modules/Findfarmhash.cmake
+++ b/tensorflow/lite/tools/cmake/modules/Findfarmhash.cmake
@@ -13,12 +13,32 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-# tensorflow-lite uses find_package for this package, so override the system
-# installation and build from source instead.
-include(farmhash)
-if(farmhash_POPULATED)
+# tensorflow-lite uses find_package for this package, so build from
+# source if the system version is not enabled.
+
+if(SYSTEM_FARMHASH)
+  include(FindPackageHandleStandardArgs)
+  find_path(FARMHASH_ROOT_DIR NAMES include/farmhash.h)
+  find_library(FARMHASH_LIB NAMES farmhash PATHS ${FARMHASH_ROOT_DIR}/lib ${FARMHASH_LIB_PATH})
+  find_path(FARMHASH_INCLUDE_DIRS NAMES farmhash.h PATHS ${FARMHASH_ROOT_DIR}/include)
+  find_package_handle_standard_args(farmhash DEFAULT_MSG FARMHASH_LIB FARMHASH_INCLUDE_DIRS)
+endif()
+
+if(farmhash_FOUND)
+  add_library(farmhash SHARED IMPORTED GLOBAL)
+  set_target_properties(farmhash PROPERTIES
+    IMPORTED_LOCATION ${FARMHASH_LIB}
+    INTERFACE_INCLUDE_DIRECTORIES ${FARMHASH_INCLUDE_DIRS}
+  )
+else()
+  include(farmhash)
+  if(farmhash_POPULATED)
+    get_target_property(FARMHASH_INCLUDE_DIRS farmhash INTERFACE_DIRECTORIES)
+  endif()
+endif()
+
+if(farmhash_FOUND OR farmhash_POPULATED)
   set(FARMHASH_FOUND TRUE)
-  get_target_property(FARMHASH_INCLUDE_DIRS farmhash INTERFACE_DIRECTORIES)
   add_library(farmhash::farmhash ALIAS farmhash)
   set(FARMHASH_LIBRARIES farmhash::farmhash)
 endif()
-- 
2.34.1