Make SK_PREFETCH work on Windows too.

- Use _mm_prefetch() if available, e.g. with MSVC.
- Some other tidying up.

No public API changes.
TBR=reed@google.com

BUG=skia:

Review URL: https://codereview.chromium.org/1427663002

diff --git a/include/core/SkPostConfig.h b/include/core/SkPostConfig.h
index f228937..76f504f 100644 (file)
--- 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__)
+    #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
 
 //////////////////////////////////////////////////////////////////////