// Recursively figure out how many bytes of xfb buffer are used by the given type.
// Return the size of type, in bytes.
// Sets containsDouble to true if the type contains a double.
// N.B. Caller must set containsDouble to false before calling.
unsigned int TIntermediate::computeTypeXfbSize(const TType& type, bool& containsDouble) const
{
// "...if applied to an aggregate containing a double, the offset must also be a multiple of 8,
// and the space taken in the buffer will be a multiple of 8.
// ...within the qualified entity, subsequent components are each
// assigned, in order, to the next available offset aligned to a multiple of
// that component's size. Aggregate types are flattened down to the component
// level to get this sequence of components."
if (type.isArray()) {
// TODO: perf: this can be flattened by using getCumulativeArraySize(), and a deref that discards all arrayness
assert(type.isExplicitlySizedArray());
TType elementType(type, 0);
return type.getOuterArraySize() * computeTypeXfbSize(elementType, containsDouble);
}
if (type.isStruct()) {
unsigned int size = 0;
bool structContainsDouble = false;
for (int member = 0; member < (int)type.getStruct()->size(); ++member) {
TType memberType(type, member);
// "... if applied to
// an aggregate containing a double, the offset must also be a multiple of 8,
// and the space taken in the buffer will be a multiple of 8."
bool memberContainsDouble = false;
int memberSize = computeTypeXfbSize(memberType, memberContainsDouble);
if (memberContainsDouble) {
structContainsDouble = true;
RoundToPow2(size, 8);
}
size += memberSize;
}
if (structContainsDouble) {
containsDouble = true;
RoundToPow2(size, 8);
}
return size;
}
int numComponents;
if (type.isScalar())
numComponents = 1;
else if (type.isVector())
numComponents = type.getVectorSize();
else if (type.isMatrix())
numComponents = type.getMatrixCols() * type.getMatrixRows();
else {
assert(0);
numComponents = 1;
}
if (type.getBasicType() == EbtDouble) {
containsDouble = true;
return 8 * numComponents;
} else
return 4 * numComponents;
}
