Prefer builtin to inline assembly when built with -mprfchw.

PiperOrigin-RevId: 576884571
Change-Id: I7bfe68e5aedd8563f8e6dbdb5d7cc66e9af22567

absl/base/prefetch.h

@@ -157,7 +157,7 @@ ABSL_ATTRIBUTE_ALWAYS_INLINE inline void PrefetchToLocalCacheForWrite(
   // unless -march=broadwell or newer; this is not generally the default, so we
   // unless -march=broadwell or newer; this is not generally the default, so we
   // manually emit prefetchw. PREFETCHW is recognized as a no-op on older Intel
   // manually emit prefetchw. PREFETCHW is recognized as a no-op on older Intel
   // processors and has been present on AMD processors since the K6-2.
   // processors and has been present on AMD processors since the K6-2.
-#if defined(__x86_64__)
+#if defined(__x86_64__) && !defined(__PRFCHW__)
   asm("prefetchw %0" : : "m"(*reinterpret_cast<const char*>(addr)));
   asm("prefetchw %0" : : "m"(*reinterpret_cast<const char*>(addr)));
 #else
 #else
   __builtin_prefetch(addr, 1, 3);
   __builtin_prefetch(addr, 1, 3);