Make SK_PREFETCH work on Windows too.

include/core/SkPostConfig.h

Index: include/core/SkPostConfig.h
diff --git a/include/core/SkPostConfig.h b/include/core/SkPostConfig.h
index f22893730523a16b746698b23e2002d6c147f794..76f504f4592a7565934de72bd82abade588cca69 100644
--- a/include/core/SkPostConfig.h
+++ b/include/core/SkPostConfig.h
@@ -295,12 +295,15 @@
 
 //////////////////////////////////////////////////////////////////////
 
-#if defined(__clang__) || defined(__GNUC__)
-#  define SK_PREFETCH(ptr) __builtin_prefetch(ptr)
-#  define SK_WRITE_PREFETCH(ptr) __builtin_prefetch(ptr, 1)
+#if SK_CPU_SSE_LEVEL >= SK_CPU_SSE_LEVEL_SSE1
+    #define SK_PREFETCH(ptr)       _mm_prefetch(ptr, _MM_HINT_T0)
+    #define SK_WRITE_PREFETCH(ptr) _mm_prefetch(ptr, _MM_HINT_T0)
+#elif defined(__GNUC__)

[Stephen White, 2015/10/27 20:03:20]

We don't need "define(__clang__) ||" here anymore?

[mtklein, 2015/10/27 20:05:55]

Nah, Clang defines __GNUC__.  Seemed confusing to leave it there, as if to
suggest Clang didn't define __GNUC__.

(Usually I find checking for __clang__ is only useful when Clang needs to do
something differently than GCC.  Pretty rare.)

+    #define SK_PREFETCH(ptr)       __builtin_prefetch(ptr)
+    #define SK_WRITE_PREFETCH(ptr) __builtin_prefetch(ptr, 1)
 #else
-#  define SK_PREFETCH(ptr)
-#  define SK_WRITE_PREFETCH(ptr)
+    #define SK_PREFETCH(ptr)
+    #define SK_WRITE_PREFETCH(ptr)
 #endif
 
 //////////////////////////////////////////////////////////////////////