internal SystemVStructRegisterPassingHelper(int totalStructSize)
{
StructSize = totalStructSize;
EightByteCount = 0;
InEmbeddedStruct = false;
CurrentUniqueOffsetField = 0;
LargestFieldOffset = -1;
EightByteClassifications = new SystemVClassificationType[CLR_SYSTEMV_MAX_EIGHTBYTES_COUNT_TO_PASS_IN_REGISTERS];
EightByteSizes = new int[CLR_SYSTEMV_MAX_EIGHTBYTES_COUNT_TO_PASS_IN_REGISTERS];
EightByteOffsets = new int[CLR_SYSTEMV_MAX_EIGHTBYTES_COUNT_TO_PASS_IN_REGISTERS];
FieldClassifications = new SystemVClassificationType[SYSTEMV_MAX_NUM_FIELDS_IN_REGISTER_PASSED_STRUCT];
FieldSizes = new int[SYSTEMV_MAX_NUM_FIELDS_IN_REGISTER_PASSED_STRUCT];
FieldOffsets = new int[SYSTEMV_MAX_NUM_FIELDS_IN_REGISTER_PASSED_STRUCT];
for (int i = 0; i < CLR_SYSTEMV_MAX_EIGHTBYTES_COUNT_TO_PASS_IN_REGISTERS; i++)
{
EightByteClassifications[i] = SystemVClassificationTypeNoClass;
EightByteSizes[i] = 0;
EightByteOffsets[i] = 0;
}
// Initialize the work arrays
for (int i = 0; i < SYSTEMV_MAX_NUM_FIELDS_IN_REGISTER_PASSED_STRUCT; i++)
{
FieldClassifications[i] = SystemVClassificationTypeNoClass;
FieldSizes[i] = 0;
FieldOffsets[i] = 0;
}
}
// If we have a field classification already, but there is a union, we must merge the classification type of the field. Returns the
// new, merged classification type.
static SystemVClassificationType ReClassifyField(SystemVClassificationType originalClassification, SystemVClassificationType newFieldClassification)
{
Debug.Assert((newFieldClassification == SystemVClassificationTypeInteger) ||
(newFieldClassification == SystemVClassificationTypeIntegerReference) ||
(newFieldClassification == SystemVClassificationTypeIntegerByRef) ||
(newFieldClassification == SystemVClassificationTypeSSE));
switch (newFieldClassification)
{
case SystemVClassificationTypeInteger:
// Integer overrides everything; the resulting classification is Integer. Can't merge Integer and IntegerReference.
Debug.Assert((originalClassification == SystemVClassificationTypeInteger) ||
(originalClassification == SystemVClassificationTypeSSE));
return(SystemVClassificationTypeInteger);
case SystemVClassificationTypeSSE:
// If the old and new classifications are both SSE, then the merge is SSE, otherwise it will be integer. Can't merge SSE and IntegerReference.
Debug.Assert((originalClassification == SystemVClassificationTypeInteger) ||
(originalClassification == SystemVClassificationTypeSSE));
if (originalClassification == SystemVClassificationTypeSSE)
{
return(SystemVClassificationTypeSSE);
}
else
{
return(SystemVClassificationTypeInteger);
}
case SystemVClassificationTypeIntegerReference:
// IntegerReference can only merge with IntegerReference.
Debug.Assert(originalClassification == SystemVClassificationTypeIntegerReference);
return(SystemVClassificationTypeIntegerReference);
case SystemVClassificationTypeIntegerByRef:
// IntegerByReference can only merge with IntegerByReference.
Debug.Assert(originalClassification == SystemVClassificationTypeIntegerByRef);
return(SystemVClassificationTypeIntegerByRef);
default:
Debug.Assert(false); // Unexpected type.
return(SystemVClassificationTypeUnknown);
}
}
// Assigns the classification types to the array with eightbyte types.
private static void AssignClassifiedEightByteTypes(ref SystemVStructRegisterPassingHelper helper)
{
const int CLR_SYSTEMV_MAX_BYTES_TO_PASS_IN_REGISTERS = CLR_SYSTEMV_MAX_EIGHTBYTES_COUNT_TO_PASS_IN_REGISTERS * SYSTEMV_EIGHT_BYTE_SIZE_IN_BYTES;
Debug.Assert(CLR_SYSTEMV_MAX_BYTES_TO_PASS_IN_REGISTERS == SYSTEMV_MAX_NUM_FIELDS_IN_REGISTER_PASSED_STRUCT);
if (!helper.InEmbeddedStruct)
{
int largestFieldOffset = helper.LargestFieldOffset;
Debug.Assert(largestFieldOffset != -1);
// We're at the top level of the recursion, and we're done looking at the fields.
// Now sort the fields by offset and set the output data.
int[] sortedFieldOrder = new int[CLR_SYSTEMV_MAX_BYTES_TO_PASS_IN_REGISTERS];
for (int i = 0; i < CLR_SYSTEMV_MAX_BYTES_TO_PASS_IN_REGISTERS; i++)
{
sortedFieldOrder[i] = -1;
}
int numFields = helper.CurrentUniqueOffsetField;
for (int i = 0; i < numFields; i++)
{
Debug.Assert(helper.FieldOffsets[i] < CLR_SYSTEMV_MAX_BYTES_TO_PASS_IN_REGISTERS);
Debug.Assert(sortedFieldOrder[helper.FieldOffsets[i]] == -1); // we haven't seen this field offset yet.
sortedFieldOrder[helper.FieldOffsets[i]] = i;
}
// Calculate the eightbytes and their types.
int lastFieldOrdinal = sortedFieldOrder[largestFieldOffset];
int offsetAfterLastFieldByte = largestFieldOffset + helper.FieldSizes[lastFieldOrdinal];
SystemVClassificationType lastFieldClassification = helper.FieldClassifications[lastFieldOrdinal];
int usedEightBytes = 0;
int accumulatedSizeForEightBytes = 0;
bool foundFieldInEightByte = false;
for (int offset = 0; offset < helper.StructSize; offset++)
{
SystemVClassificationType fieldClassificationType;
int fieldSize = 0;
int ordinal = sortedFieldOrder[offset];
if (ordinal == -1)
{
if (offset < accumulatedSizeForEightBytes)
{
// We're within a field and there is not an overlapping field that starts here.
// There's no work we need to do, so go to the next loop iteration.
continue;
}
// If there is no field that starts as this offset and we are not within another field,
// treat its contents as padding.
// Any padding that follows the last field receives the same classification as the
// last field; padding between fields receives the NO_CLASS classification as per
// the SysV ABI spec.
fieldSize = 1;
fieldClassificationType = offset < offsetAfterLastFieldByte ? SystemVClassificationTypeNoClass : lastFieldClassification;
}
else
{
foundFieldInEightByte = true;
fieldSize = helper.FieldSizes[ordinal];
Debug.Assert(fieldSize > 0);
fieldClassificationType = helper.FieldClassifications[ordinal];
Debug.Assert(fieldClassificationType != SystemVClassificationTypeMemory && fieldClassificationType != SystemVClassificationTypeUnknown);
}
int fieldStartEightByte = offset / SYSTEMV_EIGHT_BYTE_SIZE_IN_BYTES;
int fieldEndEightByte = (offset + fieldSize - 1) / SYSTEMV_EIGHT_BYTE_SIZE_IN_BYTES;
Debug.Assert(fieldEndEightByte < CLR_SYSTEMV_MAX_EIGHTBYTES_COUNT_TO_PASS_IN_REGISTERS);
usedEightBytes = Math.Max(usedEightBytes, fieldEndEightByte + 1);
for (int currentFieldEightByte = fieldStartEightByte; currentFieldEightByte <= fieldEndEightByte; currentFieldEightByte++)
{
if (helper.EightByteClassifications[currentFieldEightByte] == fieldClassificationType)
{
// Do nothing. The eight-byte already has this classification.
}
else if (helper.EightByteClassifications[currentFieldEightByte] == SystemVClassificationTypeNoClass)
{
helper.EightByteClassifications[currentFieldEightByte] = fieldClassificationType;
}
else if ((helper.EightByteClassifications[currentFieldEightByte] == SystemVClassificationTypeInteger) ||
(fieldClassificationType == SystemVClassificationTypeInteger))
{
Debug.Assert((fieldClassificationType != SystemVClassificationTypeIntegerReference) &&
(fieldClassificationType != SystemVClassificationTypeIntegerByRef));
helper.EightByteClassifications[currentFieldEightByte] = SystemVClassificationTypeInteger;
}
else if ((helper.EightByteClassifications[currentFieldEightByte] == SystemVClassificationTypeIntegerReference) ||
(fieldClassificationType == SystemVClassificationTypeIntegerReference))
{
helper.EightByteClassifications[currentFieldEightByte] = SystemVClassificationTypeIntegerReference;
}
else if ((helper.EightByteClassifications[currentFieldEightByte] == SystemVClassificationTypeIntegerByRef) ||
(fieldClassificationType == SystemVClassificationTypeIntegerByRef))
{
helper.EightByteClassifications[currentFieldEightByte] = SystemVClassificationTypeIntegerByRef;
}
else
{
helper.EightByteClassifications[currentFieldEightByte] = SystemVClassificationTypeSSE;
}
}
if ((offset + 1) % SYSTEMV_EIGHT_BYTE_SIZE_IN_BYTES == 0) // If we just finished checking the last byte of an eightbyte
{
if (!foundFieldInEightByte)
{
// If we didn't find a field in an eight-byte (i.e. there are no explicit offsets that start a field in this eightbyte)
// then the classification of this eightbyte might be NoClass. We can't hand a classification of NoClass to the JIT
// so set the class to Integer (as though the struct has a char[8] padding) if the class is NoClass.
if (helper.EightByteClassifications[offset / SYSTEMV_EIGHT_BYTE_SIZE_IN_BYTES] == SystemVClassificationTypeNoClass)
{
helper.EightByteClassifications[offset / SYSTEMV_EIGHT_BYTE_SIZE_IN_BYTES] = SystemVClassificationTypeInteger;
}
}
foundFieldInEightByte = false;
}
accumulatedSizeForEightBytes = Math.Max(accumulatedSizeForEightBytes, offset + fieldSize);
}
for (int currentEightByte = 0; currentEightByte < usedEightBytes; currentEightByte++)
{
int eightByteSize = accumulatedSizeForEightBytes < (SYSTEMV_EIGHT_BYTE_SIZE_IN_BYTES * (currentEightByte + 1))
? accumulatedSizeForEightBytes % SYSTEMV_EIGHT_BYTE_SIZE_IN_BYTES
: SYSTEMV_EIGHT_BYTE_SIZE_IN_BYTES;
// Save data for this eightbyte.
helper.EightByteSizes[currentEightByte] = eightByteSize;
helper.EightByteOffsets[currentEightByte] = currentEightByte * SYSTEMV_EIGHT_BYTE_SIZE_IN_BYTES;
}
helper.EightByteCount = usedEightBytes;
Debug.Assert(helper.EightByteCount <= CLR_SYSTEMV_MAX_EIGHTBYTES_COUNT_TO_PASS_IN_REGISTERS);
#if DEBUG
for (int i = 0; i < helper.EightByteCount; i++)
{
Debug.Assert(helper.EightByteClassifications[i] != SystemVClassificationTypeNoClass);
}
#endif // DEBUG
}
}
/// <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 = 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);
}
