CoreCLR support for InlineArrayAttribute. (struct layout part)

src/coreclr/System.Private.CoreLib/src/System/Reflection/Emit/DynamicMethod.CoreCLR.cs

@@ -150,8 +150,8 @@ Signature LazyCreateSignature()
                 {
                     Debug.Assert(parameters != null);
                     StackAllocedArguments argStorage = default;
-                    Span<object?> copyOfParameters = new(ref argStorage._arg0, argCount);
-                    Span<ParameterCopyBackAction> shouldCopyBackParameters = new(ref argStorage._copyBack0, argCount);
+                    Span<object?> copyOfParameters = argStorage._args.AsSpan(argCount);
+                    Span<ParameterCopyBackAction> shouldCopyBackParameters = argStorage._copyBacks.AsSpan(argCount);
 
                     StackAllocatedByRefs byrefStorage = default;
 #pragma warning disable CS8500

src/coreclr/System.Private.CoreLib/src/System/Reflection/RuntimeMethodInfo.CoreCLR.cs

@@ -311,9 +311,9 @@ public override MethodImplAttributes GetMethodImplementationFlags()
             unsafe
             {
                 StackAllocedArguments argStorage = default;
-                Span<object?> copyOfParameters = new(ref argStorage._arg0, 1);
+                Span<object?> copyOfParameters = argStorage._args.AsSpan(1);
                 ReadOnlySpan<object?> parameters = new(in parameter);
-                Span<ParameterCopyBackAction> shouldCopyBackParameters = new(ref argStorage._copyBack0, 1);
+                Span<ParameterCopyBackAction> shouldCopyBackParameters = argStorage._copyBacks.AsSpan(1);
 
                 StackAllocatedByRefs byrefStorage = default;
 #pragma warning disable 8500

src/coreclr/dlls/mscorrc/mscorrc.rc

@@ -310,6 +310,10 @@ BEGIN
 	IDS_CLASSLOAD_GENERICTYPE_RECURSIVE     "Could not load type '%1' from assembly '%2' because it has recursive generic definition."
     IDS_CLASSLOAD_TOOMANYGENERICARGS        "Could not load type '%1' from assembly '%2'. Internal limitation: Too many generic arguments."
 
+    IDS_CLASSLOAD_INLINE_ARRAY_FIELD_COUNT  "InlineArrayAttribute requires that the target type has a single instance field. Type: '%1'.  Assembly: '%2'."
+    IDS_CLASSLOAD_INLINE_ARRAY_LENGTH       "InlineArrayAttribute requires that the length argument is greater than 0. Type: '%1'.  Assembly: '%2'."
+    IDS_CLASSLOAD_INLINE_ARRAY_EXPLICIT     "InlineArrayAttribute cannot be applied to a type with explicit layout. Type: '%1'.  Assembly: '%2'."
+
 #if FEATURE_COMINTEROP
     IDS_EE_CANNOTCAST_NOMARSHAL                 "The Windows Runtime Object can only be used in the threading context where it was created, because it implements INoMarshal or has MarshalingBehaviorAttribute(MarshalingType.None) set."
 #endif

src/coreclr/dlls/mscorrc/resource.h

@@ -168,6 +168,10 @@
 
 #define IDS_CLASSLOAD_TOOMANYGENERICARGS        0x17ab
 
+#define IDS_CLASSLOAD_INLINE_ARRAY_FIELD_COUNT  0x17ac
+#define IDS_CLASSLOAD_INLINE_ARRAY_LENGTH       0x17ad
+#define IDS_CLASSLOAD_INLINE_ARRAY_EXPLICIT     0x17ae
+
 #define IDS_DEBUG_USERBREAKPOINT                0x17b6
 
 #define IDS_PERFORMANCEMON_FUNCNOTFOUND         0x17bb

src/coreclr/inc/corinfo.h

@@ -852,11 +852,11 @@ enum CorInfoFlag
     CORINFO_FLG_ARRAY                 = 0x00080000, // class is an array class (initialized differently)
     CORINFO_FLG_OVERLAPPING_FIELDS    = 0x00100000, // struct or class has fields that overlap (aka union)
     CORINFO_FLG_INTERFACE             = 0x00200000, // it is an interface
-    CORINFO_FLG_DONT_DIG_FIELDS       = 0x00400000, // don't ask field info, AOT can't rely on it (used for types outside of AOT compilation version bubble)
+    CORINFO_FLG_DONT_DIG_FIELDS       = 0x00400000, // don't ask field info (used for types outside of AOT compilation version bubble)
     CORINFO_FLG_CUSTOMLAYOUT          = 0x00800000, // does this struct have custom layout?
     CORINFO_FLG_CONTAINS_GC_PTR       = 0x01000000, // does the class contain a gc ptr ?
     CORINFO_FLG_DELEGATE              = 0x02000000, // is this a subclass of delegate or multicast delegate ?
-    // CORINFO_FLG_UNUSED             = 0x04000000,
+    CORINFO_FLG_INDEXABLE_FIELDS      = 0x04000000, // struct fields may be accessed via indexing (used for inline arrays)
     CORINFO_FLG_BYREF_LIKE            = 0x08000000, // it is byref-like value type
     CORINFO_FLG_VARIANCE              = 0x10000000, // MethodTable::HasVariance (sealed does *not* mean uncast-able)
     CORINFO_FLG_BEFOREFIELDINIT       = 0x20000000, // Additional flexibility for when to run .cctor (see code:#ClassConstructionFlags)

src/coreclr/jit/compiler.hpp

@@ -4369,6 +4369,11 @@ inline static bool StructHasDontDigFieldsFlagSet(DWORD attribs)
     return ((attribs & CORINFO_FLG_DONT_DIG_FIELDS) != 0);
 }
 
+inline static bool StructHasIndexableFields(DWORD attribs)
+{
+    return ((attribs & CORINFO_FLG_INDEXABLE_FIELDS) != 0);
+}
+
 //------------------------------------------------------------------------------
 // DEBUG_DESTROY_NODE: sets value of tree to garbage to catch extra references
 //

src/coreclr/jit/importercalls.cpp

@@ -2893,7 +2893,7 @@ GenTree* Compiler::impIntrinsic(GenTree*                newobjThis,
                 GenTree* indexClone     = nullptr;
                 GenTree* ptrToSpanClone = nullptr;
                 assert(genActualType(index) == TYP_INT);
-                assert(ptrToSpan->TypeGet() == TYP_BYREF);
+                assert(ptrToSpan->TypeGet() == TYP_BYREF || ptrToSpan->TypeGet() == TYP_I_IMPL);
 
 #if defined(DEBUG)
                 if (verbose)

src/coreclr/jit/lclvars.cpp

@@ -1772,6 +1772,11 @@ bool Compiler::StructPromotionHelper::CanPromoteStructType(CORINFO_CLASS_HANDLE
         return false;
     }
 
+    if (StructHasIndexableFields(typeFlags))
+    {
+        return false;
+    }
+
     // Don't struct promote if we have an CUSTOMLAYOUT flag on an HFA type
     if (StructHasCustomLayout(typeFlags) && compiler->IsHfa(typeHnd))
     {

src/coreclr/nativeaot/System.Private.CoreLib/src/Internal/Runtime/TypeLoaderExceptionHelper.cs

@@ -80,6 +80,12 @@ private static string GetFormatString(ExceptionStringID id)
                     return SR.ClassLoad_ExplicitLayout;
                 case ExceptionStringID.ClassLoadRankTooLarge:
                     return SR.ClassLoad_RankTooLarge;
+                case ExceptionStringID.ClassLoadInlineArrayFieldCount:
+                    return SR.ClassLoad_InlineArrayFieldCount;
+                case ExceptionStringID.ClassLoadInlineArrayLength:
+                    return SR.ClassLoad_InlineArrayLength;
+                case ExceptionStringID.ClassLoadInlineArrayExplicit:
+                    return SR.ClassLoad_InlineArrayExplicit;
                 case ExceptionStringID.InvalidProgramDefault:
                     return SR.InvalidProgram_Default;
                 case ExceptionStringID.InvalidProgramSpecific:

src/coreclr/nativeaot/System.Private.CoreLib/src/System/Reflection/DynamicInvokeInfo.cs

@@ -482,27 +482,17 @@ private unsafe object ReturnTransform(ref byte byref, bool wrapInTargetInvocatio
         // and pass it to CheckArguments().
         // For argument count > MaxStackAllocArgCount, do a stackalloc of void* pointers along with
         // GCReportingRegistration to safely track references.
-        [StructLayout(LayoutKind.Sequential)]
+        [InlineArray(MaxStackAllocArgCount)]
         private ref struct StackAllocedArguments
         {
             internal object? _arg0;
-#pragma warning disable CA1823, CS0169, IDE0051 // accessed via 'CheckArguments' ref arithmetic
-            private object? _arg1;
-            private object? _arg2;
-            private object? _arg3;
-#pragma warning restore CA1823, CS0169, IDE0051
         }
 
         // Helper struct to avoid intermediate IntPtr[] allocation and RegisterForGCReporting in calls to the native reflection stack.
-        [StructLayout(LayoutKind.Sequential)]
+        [InlineArray(MaxStackAllocArgCount)]
         private ref struct StackAllocatedByRefs
         {
             internal ref byte _arg0;
-#pragma warning disable CA1823, CS0169, IDE0051 // accessed via 'CheckArguments' ref arithmetic
-            private ref byte _arg1;
-            private ref byte _arg2;
-            private ref byte _arg3;
-#pragma warning restore CA1823, CS0169, IDE0051
         }
     }
 }

src/coreclr/tools/Common/Internal/Runtime/GCDescEncoder.cs

@@ -28,7 +28,7 @@ public static int GetGCDescSize(TypeDesc type)
                 }
                 else if (elementType.IsDefType)
                 {
-                    var defType = (DefType)elementType;
+                    var defType = (MetadataType)elementType;
                     if (defType.ContainsGCPointers)
                     {
                         GCPointerMap pointerMap = GCPointerMap.FromInstanceLayout(defType);
@@ -48,7 +48,7 @@ public static int GetGCDescSize(TypeDesc type)
             }
             else
             {
-                var defType = (DefType)type;
+                var defType = (MetadataType)type;
                 if (defType.ContainsGCPointers)
                 {
                     int numSeries = GCPointerMap.FromInstanceLayout(defType).NumSeries;
@@ -84,7 +84,7 @@ public static void EncodeGCDesc<T>(ref T builder, TypeDesc type)
                 }
                 else if (elementType.IsDefType)
                 {
-                    var elementDefType = (DefType)elementType;
+                    var elementDefType = (MetadataType)elementType;
                     if (elementDefType.ContainsGCPointers)
                     {
                         GCPointerMap pointerMap = GCPointerMap.FromInstanceLayout(elementDefType);
@@ -101,7 +101,7 @@ public static void EncodeGCDesc<T>(ref T builder, TypeDesc type)
             }
             else
             {
-                var defType = (DefType)type;
+                var defType = (MetadataType)type;
                 if (defType.ContainsGCPointers)
                 {
                     // Computing the layout for the boxed version if this is a value type.

src/coreclr/tools/Common/JitInterface/CorInfoImpl.cs

@@ -2010,6 +2010,9 @@ private uint getClassAttribsInternal(TypeDesc type)
 
                 if (metadataType.IsUnsafeValueType)
                     result |= CorInfoFlag.CORINFO_FLG_UNSAFE_VALUECLASS;
+
+                if (metadataType.IsInlineArray)
+                    result |= CorInfoFlag.CORINFO_FLG_INDEXABLE_FIELDS;
             }
 
             if (type.IsCanonicalSubtype(CanonicalFormKind.Any))
@@ -2240,9 +2243,10 @@ private int MarkGcField(byte* gcPtrs, CorInfoGCType gcType)
             }
         }
 
-        private int GatherClassGCLayout(TypeDesc type, byte* gcPtrs)
+        private int GatherClassGCLayout(MetadataType type, byte* gcPtrs)
         {
             int result = 0;
+            bool isInlineArray = type.IsInlineArray;
 
             foreach (var field in type.GetFields())
             {
@@ -2278,12 +2282,31 @@ private int GatherClassGCLayout(TypeDesc type, byte* gcPtrs)
 
                 if (gcType == CorInfoGCType.TYPE_GC_OTHER)
                 {
-                    result += GatherClassGCLayout(fieldType, fieldGcPtrs);
+                    result += GatherClassGCLayout((MetadataType)fieldType, fieldGcPtrs);
                 }
                 else
                 {
                     result += MarkGcField(fieldGcPtrs, gcType);
                 }
+
+                if (isInlineArray)
+                {
+                    if (result > 0)
+                    {
+                        Debug.Assert(field.Offset.AsInt == 0);
+                        int totalLayoutSize = type.GetElementSize().AsInt / PointerSize;
+                        int elementLayoutSize = fieldType.GetElementSize().AsInt / PointerSize;
+                        int gcPointersInElement = result;
+                        for (int offset = elementLayoutSize; offset < totalLayoutSize; offset += elementLayoutSize)
+                        {
+                            Buffer.MemoryCopy(gcPtrs, gcPtrs + offset, elementLayoutSize, elementLayoutSize);
+                            result += gcPointersInElement;
+                        }
+                    }
+
+                    // inline array has only one element field
+                    break;
+                }
             }
             return result;
         }
@@ -2292,7 +2315,7 @@ private uint getClassGClayout(CORINFO_CLASS_STRUCT_* cls, byte* gcPtrs)
         {
             uint result = 0;
 
-            DefType type = (DefType)HandleToObject(cls);
+            MetadataType type = (MetadataType)HandleToObject(cls);
 
             int pointerSize = PointerSize;
 

src/coreclr/tools/Common/JitInterface/CorInfoTypes.cs

@@ -606,7 +606,7 @@ public enum CorInfoFlag : uint
         CORINFO_FLG_CUSTOMLAYOUT = 0x00800000, // does this struct have custom layout?
         CORINFO_FLG_CONTAINS_GC_PTR = 0x01000000, // does the class contain a gc ptr ?
         CORINFO_FLG_DELEGATE = 0x02000000, // is this a subclass of delegate or multicast delegate ?
-        // CORINFO_FLG_UNUSED = 0x04000000,
+        CORINFO_FLG_INDEXABLE_FIELDS = 0x04000000, // struct fields may be accessed via indexing (used for inline arrays)
         CORINFO_FLG_BYREF_LIKE = 0x08000000, // it is byref-like value type
         CORINFO_FLG_VARIANCE = 0x10000000, // MethodTable::HasVariance (sealed does *not* mean uncast-able)
         CORINFO_FLG_BEFOREFIELDINIT = 0x20000000, // Additional flexibility for when to run .cctor (see code:#ClassConstructionFlags)

src/coreclr/tools/Common/TypeSystem/Canon/CanonTypes.Metadata.cs

@@ -57,6 +57,12 @@ public override bool HasCustomAttribute(string attributeNamespace, string attrib
         {
             return false;
         }
+
+        public override int GetInlineArrayLength()
+        {
+            Debug.Fail("if this can be an inline array, implement GetInlineArrayLength");
+            throw new InvalidOperationException();
+        }
     }
 
     internal sealed partial class CanonType

src/coreclr/tools/Common/TypeSystem/CodeGen/TypeDesc.CodeGen.cs

@@ -25,5 +25,11 @@ partial void AddComputedIntrinsicFlag(ref TypeFlags flags)
             if (_typeDef.IsIntrinsic)
                 flags |= TypeFlags.IsIntrinsic;
         }
+
+        partial void AddComputedInlineArrayFlag(ref TypeFlags flags)
+        {
+            if (((MetadataType)_typeDef).IsInlineArray)
+                flags |= TypeFlags.IsInlineArray;
+        }
     }
 }

src/coreclr/tools/Common/TypeSystem/Common/ExceptionStringID.cs

@@ -16,6 +16,10 @@ public enum ExceptionStringID
         ClassLoadValueClassTooLarge,
         ClassLoadRankTooLarge,
 
+        ClassLoadInlineArrayFieldCount,
+        ClassLoadInlineArrayLength,
+        ClassLoadInlineArrayExplicit,
+
         // MissingMethodException
         MissingMethod,
 

src/coreclr/tools/Common/TypeSystem/Common/InstantiatedType.Metadata.cs

@@ -86,6 +86,11 @@ public override bool HasCustomAttribute(string attributeNamespace, string attrib
             return _typeDef.HasCustomAttribute(attributeNamespace, attributeName);
         }
 
+        public override int GetInlineArrayLength()
+        {
+            return _typeDef.GetInlineArrayLength();
+        }
+
         public override MetadataType GetNestedType(string name)
         {
             // Return the result from the typical type definition.

src/coreclr/tools/Common/TypeSystem/Common/InstantiatedType.cs

@@ -74,6 +74,10 @@ public override DefType BaseType
         // will provide an implementation that adds the flag if necessary.
         partial void AddComputedIntrinsicFlag(ref TypeFlags flags);
 
+        // Type system implementations that support the notion of inline arrays
+        // will provide an implementation that adds the flag if necessary.
+        partial void AddComputedInlineArrayFlag(ref TypeFlags flags);
+
         protected override TypeFlags ComputeTypeFlags(TypeFlags mask)
         {
             TypeFlags flags = 0;
@@ -106,6 +110,8 @@ protected override TypeFlags ComputeTypeFlags(TypeFlags mask)
                 if (_typeDef.IsByRefLike)
                     flags |= TypeFlags.IsByRefLike;
 
+                AddComputedInlineArrayFlag(ref flags);
+
                 AddComputedIntrinsicFlag(ref flags);
             }