Build libfaiss with AVX2 support when requested, rather than libfaiss (#37)

Build only avx2 or generic; adapt faiss_c to whichever was built
Also force FAISS_OPT_LEVEL to "generic" when not building on x86_64.

Co-authored-by: Chris Hillery <ceejatec@users.noreply.github.com>

Author: abhinavdangeti

CMakeLists.txt

@@ -57,6 +57,11 @@ option(FAISS_ENABLE_RAFT "Enable RAFT for GPU indexes." OFF)
 option(FAISS_ENABLE_PYTHON "Build Python extension." ON)
 option(FAISS_ENABLE_C_API "Build C API." OFF)
 
+# Force FAISS_OPT_LEVEL to "generic" if not building on x86_64.
+if(NOT CMAKE_SYSTEM_PROCESSOR MATCHES "x86_64|AMD64")
+  set(FAISS_OPT_LEVEL "generic" CACHE STRING "No AVX since not building on x86_64" FORCE)
+endif()
+
 if(FAISS_ENABLE_GPU)
   set(CMAKE_CUDA_HOST_COMPILER ${CMAKE_CXX_COMPILER})
   enable_language(CUDA)

c_api/CMakeLists.txt

@@ -35,7 +35,13 @@ set(FAISS_C_SRC
   utils/distances_c.cpp
 )
 add_library(faiss_c ${FAISS_C_SRC})
-target_link_libraries(faiss_c PRIVATE faiss)
+if(FAISS_OPT_LEVEL STREQUAL "generic")
+  target_link_libraries(faiss_c PRIVATE faiss)
+elseif(FAISS_OPT_LEVEL STREQUAL "avx2")
+  target_link_libraries(faiss_c PRIVATE faiss_avx2)
+elseif(FAISS_OPT_LEVEL STREQUAL "avx512")
+  target_link_libraries(faiss_c PRIVATE faiss_avx512)
+endif()
 install(TARGETS faiss_c
   EXPORT faiss-targets
   RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR}

faiss/CMakeLists.txt

@@ -232,6 +232,9 @@ endif()
 set(FAISS_HEADERS ${FAISS_HEADERS} PARENT_SCOPE)
 
 add_library(faiss ${FAISS_SRC})
+if(NOT FAISS_OPT_LEVEL STREQUAL "generic")
+  set_target_properties(faiss PROPERTIES EXCLUDE_FROM_ALL TRUE)
+endif()
 if(CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
   target_compile_options(
     faiss PRIVATE
@@ -329,23 +332,28 @@ else()
   target_link_libraries(faiss_avx512 PRIVATE ${LAPACK_LIBRARIES})
 endif()
 
-install(TARGETS faiss
-  EXPORT faiss-targets
-  RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR}
-  ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR}
-  LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR}
-  INCLUDES DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}
-)
+
+if(FAISS_OPT_LEVEL STREQUAL "generic")
+  install(TARGETS faiss
+    EXPORT faiss-targets
+    RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR}
+    ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR}
+    LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR}
+    INCLUDES DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}
+  )
+endif()
 if(FAISS_OPT_LEVEL STREQUAL "avx2")
   install(TARGETS faiss_avx2
     EXPORT faiss-targets
+    RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR}
     ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR}
     LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR}
   )
 endif()
 if(FAISS_OPT_LEVEL STREQUAL "avx512")
   install(TARGETS faiss_avx2 faiss_avx512
     EXPORT faiss-targets
+    RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR}
     ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR}
     LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR}
   )