Fix CXX_AVX2_FLAGS (#4823)

Summary:
X-link: facebookresearch/FBGEMM#1851

- Remove quotes from CXX_AVX2_FLAGS to avoid compilation issue (see P1932287429)

Pull Request resolved: #4823

Reviewed By: cthi

Differential Revision: D81732858

Pulled By: q10

fbshipit-source-id: 9a52b09436013d8f520b21bdbaa19a81e0bdf9b3

Author: q10

CMakeLists.txt

@@ -64,6 +64,11 @@ include(GNUInstallDirs)
 # Check AVX
 set(CHECK_AVX_COMPILE ON)
 include(${MODULE_PATH}/FindAVX.cmake)
+# For some reason, AVX flag values end up being packed into a single quoted
+# string when FBGEMM is built as part of PyTorch build, so we need to separate
+# the flags here back into list-string format
+separate_arguments(CXX_AVX2_FLAGS)
+separate_arguments(CXX_AVX512_FLAGS)
 
 # Load Python
 find_package(Python)

cmake/modules/FindAVX.cmake

@@ -106,3 +106,7 @@ foreach(lang C;CXX)
     CHECK_SSE(${lang} "AVX512" "-mavx512f -mavx512dq -mavx512vl -mavx512bw -mfma;/arch:AVX512")
   endif()
 endforeach()
+
+MESSAGE(STATUS "CXX_AVX_FLAGS: ${CXX_AVX_FLAGS}")
+MESSAGE(STATUS "CXX_AVX2_FLAGS: ${CXX_AVX2_FLAGS}")
+MESSAGE(STATUS "CXX_AVX512_FLAGS: ${CXX_AVX512_FLAGS}")