Enable detection of HW intrinsics (dotnet/corert#6836)

I took the liberty of marking the types containing the hardware intrinsics as [Intrinsic] to avoid doing a name check on everything in the system module. It feels like we should take advantage of this attribute in CoreCLR too.

This doesn't actually enable the support because RyuJIT unconditionally disables HW intrinsics for prejit (both CoreRT and CPAOT are considered prejit). We might want to do something about this on the RyuJIT side to address that (for CPAOT, to be able to pregenerate best code possible ahead of time, assuming a fixed ISA; and for CoreRT without JIT, where the concerns about AVX-SSE penalty don't apply). See conversation in dotnet/coreclr#21603

Signed-off-by: dotnet-bot <dotnet-bot@microsoft.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/src/System.Private.CoreLib/shared/System/Runtime/Intrinsics/X86/Sse.cs b/src/System.Private.CoreLib/shared/System/Runtime/Intrinsics/X86/Sse.cs
index b11718e5d9..7c3e27023b 100644
--- a/src/System.Private.CoreLib/shared/System/Runtime/Intrinsics/X86/Sse.cs
+++ b/src/System.Private.CoreLib/shared/System/Runtime/Intrinsics/X86/Sse.cs
@@ -11,6 +11,7 @@ namespace System.Runtime.Intrinsics.X86
     /// <summary>
     /// This class provides access to Intel SSE hardware instructions via intrinsics
     /// </summary>
+    [Intrinsic]
     [CLSCompliant(false)]
     public abstract class Sse
     {
@@ -18,6 +19,7 @@ namespace System.Runtime.Intrinsics.X86
 
         public static bool IsSupported { get => IsSupported; }
 
+        [Intrinsic]
         public abstract class X64
         {
             internal X64() { }