Enable AVX2 optimistically with AVX on NAOT

src/coreclr/jit/hwintrinsic.cpp

@@ -1089,7 +1089,7 @@ NamedIntrinsic HWIntrinsicInfo::lookupId(Compiler*         comp,
             {
                 return NI_IsSupported_True;
             }
-            else
+            else if (isSupportedProp)
             {
                 assert(comp->IsTargetAbi(CORINFO_NATIVEAOT_ABI));
                 return NI_IsSupported_Dynamic;

src/coreclr/tools/Common/InstructionSetHelpers.cs

@@ -198,21 +198,24 @@ public static InstructionSetSupport ConfigureInstructionSetSupport(string instru
 
                 // If AVX was enabled, we can opportunistically enable instruction sets which use the VEX encodings
                 Debug.Assert(InstructionSet.X64_AVX == InstructionSet.X86_AVX);
+                Debug.Assert(InstructionSet.X64_AVX2 == InstructionSet.X86_AVX2);
                 if (supportedInstructionSet.HasInstructionSet(InstructionSet.X64_AVX))
                 {
-                    // TODO: Enable optimistic usage of AVX2 once we validate it doesn't break Vector<T> usage
-                    // optimisticInstructionSetSupportBuilder.AddSupportedInstructionSet("avx2");
-
-                    if (supportedInstructionSet.HasInstructionSet(InstructionSet.X64_AVX2))
-                    {
-                        optimisticInstructionSetSupportBuilder.AddSupportedInstructionSet("avxvnni");
-                    }
-
+                    optimisticInstructionSetSupportBuilder.AddSupportedInstructionSet("avx2");
                     optimisticInstructionSetSupportBuilder.AddSupportedInstructionSet("fma");
                     optimisticInstructionSetSupportBuilder.AddSupportedInstructionSet("bmi");
                     optimisticInstructionSetSupportBuilder.AddSupportedInstructionSet("bmi2");
+                    optimisticInstructionSetSupportBuilder.AddSupportedInstructionSet("avxvnni");
                     optimisticInstructionSetSupportBuilder.AddSupportedInstructionSet("vpclmul");
                     optimisticInstructionSetSupportBuilder.AddSupportedInstructionSet("gfni_v256");
+
+                    // If AVX2 is not in the supported set, we need to restrict the optimistic Vector<T> size, because
+                    // 256-bit Vector<T> cannot be fully accelerated based on AVX2 being in the optimistic set only.
+
+                    if (!supportedInstructionSet.HasInstructionSet(InstructionSet.X64_AVX2))
+                    {
+                        maxVectorTBitWidth = 128;
+                    }
                 }
 
                 Debug.Assert(InstructionSet.X64_AVX512F == InstructionSet.X86_AVX512F);

src/tests/nativeaot/SmokeTests/HardwareIntrinsics/Program.cs

@@ -114,11 +114,39 @@ static int Main()
         bool? ExpectedSse42 = true;
         bool? ExpectedPopcnt = null;
         bool? ExpectedAvx = true;
-        bool? ExpectedAvx2 = false; // TODO: Fix once opportunistic Avx2 is allowed
+        bool? ExpectedAvx2 = null;
         bool? ExpectedFma = null;
         bool? ExpectedBmi1 = null;
         bool? ExpectedBmi2 = null;
-        bool? ExpectedAvxVnni = false; // TODO: Fix once opportunistic Avx2 is allowed
+        bool? ExpectedAvxVnni = null;
+        bool? ExpectedAvx10v1 = false;
+        bool? ExpectedAvx10v1V512 = false;
+        bool? ExpectedAvx512F = false;
+        bool? ExpectedAvx512BW = false;
+        bool? ExpectedAvx512CD = false;
+        bool? ExpectedAvx512DQ = false;
+        bool? ExpectedAvx512Vbmi = false;
+        bool? ExpectedX86Serialize = null;
+        bool? ExpectedGfni = null;
+        bool? ExpectedGfniV256 = null;
+        bool? ExpectedGfniV512 = false;
+#elif AVX_INTRINSICS_NO_AVX2
+        bool? ExpectedSse3 = true;
+        bool? ExpectedSsse3 = true;
+        bool? ExpectedAes = null;
+        bool? ExpectedLzcnt = null;
+        bool? ExpectedPclmulqdq = null;
+        bool? ExpectedPclmulqdqV256 = null;
+        bool? ExpectedPclmulqdqV512 = false;
+        bool? ExpectedSse41 = true;
+        bool? ExpectedSse42 = true;
+        bool? ExpectedPopcnt = null;
+        bool? ExpectedAvx = true;
+        bool? ExpectedAvx2 = false;
+        bool? ExpectedFma = null;
+        bool? ExpectedBmi1 = null;
+        bool? ExpectedBmi2 = null;
+        bool? ExpectedAvxVnni = false;
         bool? ExpectedAvx10v1 = false;
         bool? ExpectedAvx10v1V512 = false;
         bool? ExpectedAvx512F = false;

src/tests/nativeaot/SmokeTests/HardwareIntrinsics/X64Avx_NoAvx2.csproj

@@ -8,7 +8,7 @@
     <!-- Test infra issue on apple devices: https://github.com/dotnet/runtime/issues/89917 -->
     <CLRTestTargetUnsupported Condition="'$(TargetsAppleMobile)' == 'true'">true</CLRTestTargetUnsupported>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
-    <DefineConstants>$(DefineConstants);AVX_INTRINSICS;VECTORT128_INTRINSICS</DefineConstants>
+    <DefineConstants>$(DefineConstants);AVX_INTRINSICS_NO_AVX2;VECTORT128_INTRINSICS</DefineConstants>
     <RequiresProcessIsolation>true</RequiresProcessIsolation>
     <ReferenceXUnitWrapperGenerator>false</ReferenceXUnitWrapperGenerator>
   </PropertyGroup>