[clang] [Win/X86] Make _m_prefetch[w] builtins to avoid winnt.h conflicts (PR #115099)

[Reid Kleckner via cfe-commits]

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@@ -146,8 +146,13 @@ 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", Attributes = [NoThrow, Const] in {
-  def _mm_prefetch : X86NoPrefixBuiltin<"void(char const *, int)">;
+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 *)">;
----------------
rnk wrote:

Yes, it should! I looked at the Intel intrinsic documentation, and it said these intrinsics were part of the deprecated 3dnow ISA extension, and I wasn't sure what to. However, I took the time to check the Intel ISA manual and I updated this feature set and the _mm_prefetch feature check to "sse", since that seems to be the correct feature. PTAL, since I've expanded scope a bit.

https://github.com/llvm/llvm-project/pull/115099