Replace or exclude MMX intrinsics in yuv_convert_simd_x86 due to lack of VS2010 support for them in…

media/base/yuv_convert.h

Index: media/base/yuv_convert.h
diff --git a/media/base/yuv_convert.h b/media/base/yuv_convert.h
index afd47d79ca1ea836a4a9852b8fb1cd224287344e..92b0a7f52dc0c7650204b16e46c9faf2606286e3 100644
--- a/media/base/yuv_convert.h
+++ b/media/base/yuv_convert.h
@@ -9,6 +9,16 @@
 
 namespace media {
 
+// Visual Studio 2010 does not support MMX intrinsics on x64.
+// Some win64 yuv_convert code paths use SSE+MMX yasm, so without rewriting
+// them, we use yasm EmptyRegisterState_MMX in place of _mm_empty() or
+// hide the versions implemented with heavy use of MMX intrinsics.
+// TODO(wolenetz): Use MMX intrinsics when compiling win64 with Visual
+// Studio 2012? (crbug.com/173450)

[scherkus (not reviewing), 2013/02/01 01:13:17]

pedantic nit: use "http://crbug.com/173450: without brackets or other
punctuation 'n stuff

(there are lots of random text editors and search engines that will appreciate
your easy-to-parse URL inside comments!)

[wolenetz, 2013/02/01 02:42:07]

Done.

+#if defined(ARCH_CPU_X86_64) && defined(COMPILER_MSVC)
+#define MEDIA_DO_NOT_USE_MMX_INTRINSICS

[scherkus (not reviewing), 2013/02/01 01:13:17]

nit: it'd be clearer to negate the define i.e., USE_MMX_INTRINSICS and have it
undefined for win64 msvc

(the !defined(MEDIA_DO_NOT_USE_MMX_INTRINSICS) makes my brain hurt)

[wolenetz, 2013/02/01 02:42:07]

Done.

+#endif

[scherkus (not reviewing), 2013/02/01 01:13:17]

I believe this can be moved to the .cc

[wolenetz, 2013/02/01 02:42:07]

Done.

+
 // Type of YUV surface.
 // The value of these enums matter as they are used to shift vertical indices.
 enum YUVType {
@@ -121,7 +131,6 @@ void ConvertNV21ToYUV(const uint8* src,
                       int height);
 
 // Empty SIMD register state after calling optimized scaler functions.
-// This method is only used in unit test after calling SIMD functions.
 void EmptyRegisterState();
 
 }  // namespace media