[MSVC, ARM64] Add __prefetch intrinsic (#67174)

Implement __prefetch intrinsic. 

MSVC docs:
https://learn.microsoft.com/en-us/cpp/intrinsics/arm64-intrinsics?view=msvc-170

Bug: #65405

Author: amykhuang

clang/include/clang/Basic/BuiltinsAArch64.def

@@ -283,6 +283,8 @@ TARGET_HEADER_BUILTIN(_CountLeadingZeros64, "UiULLi", "nh", INTRIN_H, ALL_MS_LAN
 TARGET_HEADER_BUILTIN(_CountOneBits, "UiUNi", "nh", INTRIN_H, ALL_MS_LANGUAGES, "")
 TARGET_HEADER_BUILTIN(_CountOneBits64, "UiULLi", "nh", INTRIN_H, ALL_MS_LANGUAGES, "")
 
+TARGET_HEADER_BUILTIN(__prefetch, "vv*", "nh", INTRIN_H, ALL_MS_LANGUAGES, "")
+
 #undef BUILTIN
 #undef LANGBUILTIN
 #undef TARGET_BUILTIN

clang/lib/CodeGen/CGBuiltin.cpp

@@ -10842,6 +10842,15 @@ Value *CodeGenFunction::EmitAArch64BuiltinExpr(unsigned BuiltinID,
     return Result;
   }
 
+  if (BuiltinID == AArch64::BI__prefetch) {
+    Value *Address = EmitScalarExpr(E->getArg(0));
+    Value *RW = llvm::ConstantInt::get(Int32Ty, 0);
+    Value *Locality = ConstantInt::get(Int32Ty, 3);
+    Value *Data = llvm::ConstantInt::get(Int32Ty, 1);
+    Function *F = CGM.getIntrinsic(Intrinsic::prefetch, Address->getType());
+    return Builder.CreateCall(F, {Address, RW, Locality, Data});
+  }
+
   // Handle MSVC intrinsics before argument evaluation to prevent double
   // evaluation.
   if (std::optional<MSVCIntrin> MsvcIntId =

clang/lib/Headers/intrin.h

@@ -586,6 +586,8 @@ unsigned int _CountLeadingZeros(unsigned long);
 unsigned int _CountLeadingZeros64(unsigned _int64);
 unsigned int _CountOneBits(unsigned long);
 unsigned int _CountOneBits64(unsigned __int64);
+
+void __cdecl __prefetch(void *);
 #endif
 
 /*----------------------------------------------------------------------------*\

clang/test/CodeGen/arm64-microsoft-intrinsics.c

@@ -402,6 +402,16 @@ unsigned int check_CountOneBits64(unsigned __int64 arg1) {
 // CHECK-MSCOMPAT: ret i32 %[[VAR2]]
 // CHECK-LINUX: error: call to undeclared function '_CountOneBits64'
 
+void check__prefetch(void *arg1) {
+  return __prefetch(arg1);
+}
+
+// CHECK-MSCOMPAT: %[[ARG1:.*]].addr = alloca ptr, align 8
+// CHECK-MSCOMPAT: store ptr %[[ARG1]], ptr %[[ARG1]].addr, align 8
+// CHECK-MSCOMPAT: %[[VAR0:.*]] = load ptr, ptr %[[ARG1]].addr, align 8
+// CHECK-MSCOMPAT: call void @llvm.prefetch.p0(ptr %[[VAR0]], i32 0, i32 3, i32 1)
+// CHECK-MSCOMPAT: ret void
+
 
 // CHECK-MSCOMPAT: ![[MD2]] = !{!"x18"}
 // CHECK-MSCOMPAT: ![[MD3]] = !{!"sp"}