public override FieldLayoutAlgorithm GetLayoutAlgorithmForType(DefType type) { if (type == UniversalCanonType) { return(UniversalCanonLayoutAlgorithm.Instance); } else if (VectorFieldLayoutAlgorithm.IsVectorType(type)) { return(_vectorFieldLayoutAlgorithm); } else if (Int128FieldLayoutAlgorithm.IsIntegerType(type)) { return(_int128FieldLayoutAlgorithm); } return(_metadataFieldLayout); }
/// <summary> /// Returns 'true' if the struct is passed in registers, 'false' otherwise. /// </summary> private static bool ClassifyEightBytes(TypeDesc typeDesc, ref SystemVStructRegisterPassingHelper helper, int startOffsetOfStruct) { FieldDesc firstField = null; int numIntroducedFields = 0; foreach (FieldDesc field in typeDesc.GetFields()) { if (!field.IsStatic) { if (firstField == null) { firstField = field; } numIntroducedFields++; } } if (numIntroducedFields == 0) { return(false); } // The SIMD and Int128 Intrinsic types are meant to be handled specially and should not be passed as struct registers if (typeDesc.IsIntrinsic) { InstantiatedType instantiatedType = typeDesc as InstantiatedType; if (instantiatedType != null) { if (VectorFieldLayoutAlgorithm.IsVectorType(instantiatedType) || VectorOfTFieldLayoutAlgorithm.IsVectorOfTType(instantiatedType) || Int128FieldLayoutAlgorithm.IsIntegerType(instantiatedType)) { return(false); } } } MetadataType mdType = typeDesc as MetadataType; Debug.Assert(mdType != null); TypeDesc firstFieldElementType = firstField.FieldType; int firstFieldSize = firstFieldElementType.GetElementSize().AsInt; // A fixed buffer type is always a value type that has exactly one value type field at offset 0 // and who's size is an exact multiple of the size of the field. // It is possible that we catch a false positive with this check, but that chance is extremely slim // and the user can always change their structure to something more descriptive of what they want // instead of adding additional padding at the end of a one-field structure. // We do this check here to save looking up the FixedBufferAttribute when loading the field // from metadata. bool isFixedBuffer = numIntroducedFields == 1 && firstFieldElementType.IsValueType && firstField.Offset.AsInt == 0 && mdType.HasLayout() && ((typeDesc.GetElementSize().AsInt % firstFieldSize) == 0); if (isFixedBuffer) { numIntroducedFields = typeDesc.GetElementSize().AsInt / firstFieldSize; } int fieldIndex = 0; foreach (FieldDesc field in FieldEnumerator.GetInstanceFields(typeDesc, isFixedBuffer, numIntroducedFields)) { Debug.Assert(fieldIndex < numIntroducedFields); int fieldOffset = isFixedBuffer ? fieldIndex * firstFieldSize : field.Offset.AsInt; int normalizedFieldOffset = fieldOffset + startOffsetOfStruct; int fieldSize = field.FieldType.GetElementSize().AsInt; // The field can't span past the end of the struct. if ((normalizedFieldOffset + fieldSize) > helper.StructSize) { Debug.Assert(false, "Invalid struct size. The size of fields and overall size don't agree"); return(false); } SystemVClassificationType fieldClassificationType; if (typeDesc.IsByReferenceOfT) { // ByReference<T> is a special type whose single IntPtr field holds a by-ref potentially interior pointer to GC // memory, so classify its field as such Debug.Assert(numIntroducedFields == 1); Debug.Assert(field.FieldType.IsWellKnownType(WellKnownType.IntPtr)); fieldClassificationType = SystemVClassificationTypeIntegerByRef; } else { fieldClassificationType = TypeDef2SystemVClassification(field.FieldType); } if (fieldClassificationType == SystemVClassificationTypeStruct) { bool inEmbeddedStructPrev = helper.InEmbeddedStruct; helper.InEmbeddedStruct = true; bool structRet = false; structRet = ClassifyEightBytes(field.FieldType, ref helper, normalizedFieldOffset); helper.InEmbeddedStruct = inEmbeddedStructPrev; if (!structRet) { // If the nested struct says not to enregister, there's no need to continue analyzing at this level. Just return do not enregister. return(false); } continue; } if ((normalizedFieldOffset % fieldSize) != 0) { // The spec requires that struct values on the stack from register passed fields expects // those fields to be at their natural alignment. return(false); } if (normalizedFieldOffset <= helper.LargestFieldOffset) { // Find the field corresponding to this offset and update the size if needed. // If the offset matches a previously encountered offset, update the classification and field size. int i; for (i = helper.CurrentUniqueOffsetField - 1; i >= 0; i--) { if (helper.FieldOffsets[i] == normalizedFieldOffset) { if (fieldSize > helper.FieldSizes[i]) { helper.FieldSizes[i] = fieldSize; } helper.FieldClassifications[i] = ReClassifyField(helper.FieldClassifications[i], fieldClassificationType); break; } } if (i >= 0) { // The proper size of the union set of fields has been set above; continue to the next field. continue; } } else { helper.LargestFieldOffset = (int)normalizedFieldOffset; } // Set the data for a new field. // The new field classification must not have been initialized yet. Debug.Assert(helper.FieldClassifications[helper.CurrentUniqueOffsetField] == SystemVClassificationTypeNoClass); // There are only a few field classifications that are allowed. Debug.Assert((fieldClassificationType == SystemVClassificationTypeInteger) || (fieldClassificationType == SystemVClassificationTypeIntegerReference) || (fieldClassificationType == SystemVClassificationTypeIntegerByRef) || (fieldClassificationType == SystemVClassificationTypeSSE)); helper.FieldClassifications[helper.CurrentUniqueOffsetField] = fieldClassificationType; helper.FieldSizes[helper.CurrentUniqueOffsetField] = fieldSize; helper.FieldOffsets[helper.CurrentUniqueOffsetField] = normalizedFieldOffset; Debug.Assert(helper.CurrentUniqueOffsetField < SYSTEMV_MAX_NUM_FIELDS_IN_REGISTER_PASSED_STRUCT); helper.CurrentUniqueOffsetField++; fieldIndex++; } AssignClassifiedEightByteTypes(ref helper); return(true); }