VSX toolchains: check for SSE2 support (#4845)

Improves compatibility with Clang 11.

Also rename NCNN_SSE* options to NCNN_VSX_SSE* to avoid conflict between
x86 and POWER (went unnoticed before because x86 doesn't have an option
for toggling SSE 4.1).

Co-authored-by: Jeremy Rand <jeremyrand@danwin1210.de>

CMakeLists.txt

@@ -368,14 +368,24 @@ elseif(CMAKE_SYSTEM_PROCESSOR MATCHES "^(powerpc|ppc)")
     if(NCNN_PPC64LE_VSX)
         set(NCNN_TARGET_ARCH x86)
 
+        set(CMAKE_REQUIRED_FLAGS "-DNO_WARN_X86_INTRINSICS -D__SSE2__")
+        check_cxx_source_compiles("#include <emmintrin.h>\nint main() { return 0; }" NCNN_COMPILER_SUPPORT_PPC64LE_SSE2)
+        unset(CMAKE_REQUIRED_FLAGS)
+
         set(CMAKE_REQUIRED_FLAGS "-DNO_WARN_X86_INTRINSICS -D__SSE4_1__")
         check_cxx_source_compiles("#include <smmintrin.h>\nint main() { __m128i _v, _a, _b; _v = _mm_packus_epi32(_a, _b); return 0; }" NCNN_COMPILER_SUPPORT_PPC64LE_SSE41)
         unset(CMAKE_REQUIRED_FLAGS)
 
+        if(NCNN_COMPILER_SUPPORT_PPC64LE_SSE2)
+            option(NCNN_VSX_SSE2 "optimize ppc64le platform with sse2 extension" ON)
+        else()
+            message(WARNING "The compiler does not support sse2 extension. NCNN_VSX_SSE2 will be OFF.")
+        endif()
+
         if(NCNN_COMPILER_SUPPORT_PPC64LE_SSE41)
-            option(NCNN_SSE41 "optimize ppc64le platform with sse4.1 extension" ON)
+            option(NCNN_VSX_SSE41 "optimize ppc64le platform with sse4.1 extension" ON)
         else()
-            message(WARNING "The compiler does not support sse4.1 extension. NCNN_SSE41 will be OFF.")
+            message(WARNING "The compiler does not support sse4.1 extension. NCNN_VSX_SSE41 will be OFF.")
         endif()
     endif()
 elseif(CMAKE_SYSTEM_PROCESSOR MATCHES "^(xtensa)")

src/CMakeLists.txt

@@ -503,8 +503,13 @@ if(NCNN_TARGET_ARCH STREQUAL "riscv" AND NOT C906)
 endif()
 
 if(NCNN_PPC64LE_VSX)
+    # Auto-translate SSE2 to VSX if compiler is new enough.
+    if(NCNN_VSX_SSE2)
+        target_compile_options(ncnn PRIVATE -DNO_WARN_X86_INTRINSICS -D__SSE2__)
+    endif()
+
     # Auto-translate SSE4.1 to VSX if compiler is new enough.
-    if(NCNN_SSE41)
+    if(NCNN_VSX_SSE41)
         target_compile_options(ncnn PRIVATE -DNO_WARN_X86_INTRINSICS -D__SSE4_1__)
     endif()
 endif()

toolchains/power9le-linux-gnu-vsx.clang.toolchain.cmake

@@ -8,8 +8,8 @@ set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
 set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
 set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
 
-set(CMAKE_C_FLAGS "-target powerpc64le-linux-gnu -I/usr/powerpc64le-linux-gnu/include -mcpu=power9 -mtune=power9 -DNO_WARN_X86_INTRINSICS -D__MMX__ -D__SSE__ -D__SSE2__ -D__SSSE3__")
-set(CMAKE_CXX_FLAGS "-target powerpc64le-linux-gnu -I/usr/powerpc64le-linux-gnu/include -I/usr/powerpc64le-linux-gnu/include/c++/10/powerpc64le-linux-gnu -mcpu=power9 -mtune=power9 -DNO_WARN_X86_INTRINSICS -D__MMX__ -D__SSE__ -D__SSE2__ -D__SSSE3__")
+set(CMAKE_C_FLAGS "-target powerpc64le-linux-gnu -I/usr/powerpc64le-linux-gnu/include -mcpu=power9 -mtune=power9 -DNO_WARN_X86_INTRINSICS -D__MMX__ -D__SSE__ -D__SSSE3__")
+set(CMAKE_CXX_FLAGS "-target powerpc64le-linux-gnu -I/usr/powerpc64le-linux-gnu/include -I/usr/powerpc64le-linux-gnu/include/c++/10/powerpc64le-linux-gnu -mcpu=power9 -mtune=power9 -DNO_WARN_X86_INTRINSICS -D__MMX__ -D__SSE__ -D__SSSE3__")
 
 # cache flags
 set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS}" CACHE STRING "c flags")

toolchains/power9le-linux-gnu-vsx.toolchain.cmake

@@ -8,8 +8,8 @@ set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
 set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
 set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
 
-set(CMAKE_C_FLAGS "-mcpu=power9 -mtune=power9 -DNO_WARN_X86_INTRINSICS -D__MMX__ -D__SSE__ -D__SSE2__ -D__SSSE3__")
-set(CMAKE_CXX_FLAGS "-mcpu=power9 -mtune=power9 -DNO_WARN_X86_INTRINSICS -D__MMX__ -D__SSE__ -D__SSE2__ -D__SSSE3__")
+set(CMAKE_C_FLAGS "-mcpu=power9 -mtune=power9 -DNO_WARN_X86_INTRINSICS -D__MMX__ -D__SSE__ -D__SSSE3__")
+set(CMAKE_CXX_FLAGS "-mcpu=power9 -mtune=power9 -DNO_WARN_X86_INTRINSICS -D__MMX__ -D__SSE__ -D__SSSE3__")
 
 # cache flags
 set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS}" CACHE STRING "c flags")