Enable sse2neon in BLI_simd except for hydra/USD

This should get all of the tests to pass on Windows ARM64 platforms.

Sadly it needs disabling for hydra/USD stuff as currently it doesn't play nicely with the new preprocessor. @LazyDodo suggested a USD version update may fix this, which is something I can investigate in due course - right now, let's get daily builds up and working :)

Pull Request: https://projects.blender.org/blender/blender/pulls/121361

source/blender/blenlib/BLI_simd.hh

@@ -16,9 +16,8 @@
 #  error Including BLI_simd.hh requires C++
 #endif
 
-// TODO: Re-enable this once blenlib is converted to C++
-#if (defined(__ARM_NEON) /* || (defined(_M_ARM64) && defined(_MSC_VER))*/) && \
-    defined(WITH_SSE2NEON)
+#if (defined(__ARM_NEON) || (defined(_M_ARM64) && defined(_MSC_VER))) && \
+    defined(WITH_SSE2NEON) && !defined(DISABLE_SSE2NEON)
 /* SSE/SSE2 emulation on ARM Neon. Match SSE precision. */
 #  if !defined(SSE2NEON_PRECISE_MINMAX)
 #    define SSE2NEON_PRECISE_MINMAX 1
@@ -39,7 +38,8 @@
 #  define BLI_HAVE_SSE2 0
 #endif
 
-#if defined(__ARM_NEON) && defined(WITH_SSE2NEON)
+#if (defined(__ARM_NEON) || (defined(_M_ARM64) && defined(_MSC_VER))) && \
+    defined(WITH_SSE2NEON) && !defined(DISABLE_SSE2NEON)
 /* SSE4 is emulated via sse2neon. */
 #  define BLI_HAVE_SSE4 1
 #elif defined(__SSE4_2__)

source/blender/io/usd/CMakeLists.txt

@@ -54,8 +54,9 @@ if(WIN32)
   remove_cc_flag("/w34100")
   if(CMAKE_SYSTEM_PROCESSOR STREQUAL "ARM64")
     # USD currently does not support the new preprocessor,
-    # and does not use sse2neon, so we can remove it here
+    # so we remove it here and disable sse2neon
     remove_cc_flag("/Zc:preprocessor")
+    add_definitions(-DDISABLE_SSE2NEON)
   endif()
 endif()
 

source/blender/render/hydra/CMakeLists.txt

@@ -35,8 +35,9 @@ if(WIN32)
   remove_cc_flag("/w34100")
   if(CMAKE_SYSTEM_PROCESSOR STREQUAL "ARM64")
     # USD currently does not support the new preprocessor,
-    # and does not use sse2neon, so we can remove it here
+    # so we remove it here and disable sse2neon
     remove_cc_flag("/Zc:preprocessor")
+    add_definitions(-DDISABLE_SSE2NEON)
   endif()
 endif()