Update feature checks and headers for prefetch instructions

Author: rnk

clang/include/clang/Basic/BuiltinsX86.td

@@ -130,6 +130,10 @@ let Attributes = [Const, NoThrow, RequiredVectorWidth<128>] in {
   }
 }
 
+let Features = "sse", Header = "xmmintrin.h", Attributes = [NoThrow, Const] in {
+  def _mm_prefetch : X86LibBuiltin<"void(void const *, int)">;
+}
+
 // AVX
 let Attributes = [Const, NoThrow, RequiredVectorWidth<256>], Features = "avx" in {
   foreach Op = ["addsub", "hadd", "hsub", "max", "min"] in {
@@ -138,6 +142,12 @@ let Attributes = [Const, NoThrow, RequiredVectorWidth<256>], Features = "avx" in
   }
 }
 
+// PRFCHW
+let Features = "prfchw", Header = "x86intrin.h", Attributes = [NoThrow, Const] in {
+  def _m_prefetch : X86LibBuiltin<"void(void *)">;
+  def _m_prefetchw : X86LibBuiltin<"void(void volatile const *)">;
+}
+
 
 // Mechanically ported builtins from the original `.def` file.
 //
@@ -146,15 +156,6 @@ let Attributes = [Const, NoThrow, RequiredVectorWidth<256>], Features = "avx" in
 // current formulation is based on what was easiest to recognize from the
 // pre-TableGen version.
 
-let Features = "mmx", Header = "immintrin.h", Attributes = [NoThrow, Const] in {
-  def _mm_prefetch : X86LibBuiltin<"void(void const *, int)">;
-}
-
-let Features = "mmx", Header = "intrin.h", Attributes = [NoThrow, Const] in {
-  def _m_prefetch : X86LibBuiltin<"void(void *)">;
-  def _m_prefetchw : X86LibBuiltin<"void(void volatile const *)">;
-}
-
 let Features = "sse", Attributes = [NoThrow] in {
   def ldmxcsr : X86Builtin<"void(unsigned int)">;
 }