Updating the VM to no longer treat the SIMD HWIntrinsic types as HFA or MultiReg structs

src/vm/class.cpp

@@ -1722,6 +1722,20 @@ EEClass::CheckForHFA()
     if (HasExplicitFieldOffsetLayout())
         return false;
 
+    // The SIMD Intrinsic types are meant to be handled specially and should not be treated as HFA
+    if (GetMethodTable()->IsIntrinsicType())
+    {
+        LPCUTF8 namespaceName;
+        LPCUTF8 className = GetMethodTable()->GetFullyQualifiedNameInfo(&namespaceName);
+
+        if ((strcmp(className, "Vector256`1") == 0) || (strcmp(className, "Vector128`1") == 0) ||
+            (strcmp(className, "Vector64`1") == 0))
+        {
+            assert(strcmp(namespaceName, "System.Runtime.Intrinsics") == 0);
+            return false;
+        }
+    }
+
     CorElementType hfaType = ELEMENT_TYPE_END;
 
     FieldDesc *pFieldDescList = GetFieldDescList();

src/vm/methodtable.cpp

@@ -2340,6 +2340,25 @@ bool MethodTable::ClassifyEightBytesWithManagedLayout(SystemVStructRegisterPassi
                nestingLevel * 5, "", this->GetDebugClassName()));
         return false;
     }
+
+    // The SIMD Intrinsic types are meant to be handled specially and should not be passed as struct registers
+    if (IsIntrinsicType())
+    {
+        LPCUTF8 namespaceName;
+        LPCUTF8 className = GetFullyQualifiedNameInfo(&namespaceName);
+
+        if ((strcmp(className, "Vector256`1") == 0) || (strcmp(className, "Vector128`1") == 0) ||
+            (strcmp(className, "Vector64`1") == 0))
+        {
+            assert(strcmp(namespaceName, "System.Runtime.Intrinsics") == 0);
+
+            LOG((LF_JIT, LL_EVERYTHING, "%*s**** ClassifyEightBytesWithManagedLayout: struct %s is a SIMD intrinsic type; will not be enregistered\n",
+                nestingLevel * 5, "", this->GetDebugClassName()));
+
+            return false;
+        }
+    }
+
 #ifdef _DEBUG
     LOG((LF_JIT, LL_EVERYTHING, "%*s**** Classify %s (%p), startOffset %d, total struct size %d\n",
         nestingLevel * 5, "", this->GetDebugClassName(), this, startOffsetOfStruct, helperPtr->structSize));
@@ -2619,6 +2638,24 @@ bool MethodTable::ClassifyEightBytesWithNativeLayout(SystemVStructRegisterPassin
         return false;
     }
 
+    // The SIMD Intrinsic types are meant to be handled specially and should not be passed as struct registers
+    if (IsIntrinsicType())
+    {
+        LPCUTF8 namespaceName;
+        LPCUTF8 className = GetFullyQualifiedNameInfo(&namespaceName);
+
+        if ((strcmp(className, "Vector256`1") == 0) || (strcmp(className, "Vector128`1") == 0) ||
+            (strcmp(className, "Vector64`1") == 0))
+        {
+            assert(strcmp(namespaceName, "System.Runtime.Intrinsics") == 0);
+
+            LOG((LF_JIT, LL_EVERYTHING, "%*s**** ClassifyEightBytesWithNativeLayout: struct %s is a SIMD intrinsic type; will not be enregistered\n",
+                nestingLevel * 5, "", this->GetDebugClassName()));
+
+            return false;
+        }
+    }
+
 #ifdef _DEBUG
     LOG((LF_JIT, LL_EVERYTHING, "%*s**** Classify for native struct %s (%p), startOffset %d, total struct size %d\n",
         nestingLevel * 5, "", this->GetDebugClassName(), this, startOffsetOfStruct, helperPtr->structSize));

src/vm/methodtablebuilder.cpp

@@ -1499,7 +1499,21 @@ MethodTableBuilder::BuildMethodTableThrowing(
         LPCUTF8 className;
         LPCUTF8 nameSpace;
         HRESULT hr = GetMDImport()->GetNameOfTypeDef(bmtInternal->pType->GetTypeDefToken(), &className, &nameSpace);
-
+
+        if (hr == S_OK && strcmp(nameSpace, "System.Runtime.Intrinsics") == 0)
+        {
+            if (IsCompilationProcess())
+            {
+                // Disable AOT compiling for the SIMD hardware intrinsic types. These types require special
+                // ABI handling as they represent fundamental data types (__m64, __m128, and __m256) and not
+                // aggregate or union types. See https://github.com/dotnet/coreclr/issues/15943
+                //
+                // Once they are properly handled according to the ABI requirements, we can remove this check
+                // and allow them to be used in crossgen/AOT scenarios.
+                COMPlusThrow(kTypeLoadException, IDS_EE_HWINTRINSIC_NGEN_DISALLOWED);
+            }
+        }
+
 #if defined(_TARGET_ARM64_)
         // All the funtions in System.Runtime.Intrinsics.Arm.Arm64 are hardware intrinsics.
         if (hr == S_OK && strcmp(nameSpace, "System.Runtime.Intrinsics.Arm.Arm64") == 0)
@@ -1844,6 +1858,24 @@ MethodTableBuilder::BuildMethodTableThrowing(
         pMT->SetIsByRefLike();
     }
 
+    // If this type is marked by [Intrinsic] attribute, it may be specially treated by the runtime/compiler
+    // Currently, only SIMD types have [Intrinsic] attribute
+    //
+    // We check this here, before the SystemVAmd64CheckForPass[Native]StructInRegister calls to ensure the SIMD
+    // intrinsics are not enregistered incorrectly.
+    if ((GetModule()->IsSystem() || GetAssembly()->IsSIMDVectorAssembly()) && IsValueClass() && bmtGenerics->HasInstantiation())
+    {
+        HRESULT hr = GetMDImport()->GetCustomAttributeByName(bmtInternal->pType->GetTypeDefToken(), 
+            g_CompilerServicesIntrinsicAttribute, 
+            NULL, 
+            NULL);
+
+        if (hr == S_OK)
+        {
+            pMT->SetIsIntrinsicType();
+        }
+    }
+
     if (IsValueClass())
     {
         if (bmtFP->NumInstanceFieldBytes != totalDeclaredFieldSize || HasOverLayedField())
@@ -2025,21 +2057,6 @@ MethodTableBuilder::BuildMethodTableThrowing(
         pMT->SetICastable();
     }
 #endif // FEATURE_ICASTABLE       
-
-    // If this type is marked by [Intrinsic] attribute, it may be specially treated by the runtime/compiler
-    // Currently, only SIMD types have [Intrinsic] attribute
-    if ((GetModule()->IsSystem() || GetAssembly()->IsSIMDVectorAssembly()) && IsValueClass() && bmtGenerics->HasInstantiation())
-    {
-        HRESULT hr = GetMDImport()->GetCustomAttributeByName(bmtInternal->pType->GetTypeDefToken(), 
-            g_CompilerServicesIntrinsicAttribute, 
-            NULL, 
-            NULL);
-
-        if (hr == S_OK)
-        {
-            pMT->SetIsIntrinsicType();
-        }
-    }
 
     // Grow the typedef ridmap in advance as we can't afford to
     // fail once we set the resolve bit