[PATCH] D105967: [TableGen] Allow isAllocatable inheritence from any superclass

[Carl Ritson via Phabricator via llvm-commits]

critson added a comment.

In D105967#2877328 <https://reviews.llvm.org/D105967#2877328>, @kparzysz wrote:

> I think it's ok, but it makes me wonder about the other properties.  If this one can vary depending on the topological ordering, can `VTs` or `CopyCost` (for example) change too?  Logically, `VTs` should be the intersection of `VTs` over all super classes, other properties may need different treatment.

I agree there may be other opportunities to improve the multi-inheritance.

For our usage we have an unallocatable superclass with a mix of allocatable and unallocatable subclasses.
All relevant classes have the same VTs, CopyCost, AllocationPriority, etc.
So at present it is the only the Allocatable flag that has been a problem.

VTs does seem to fit as an intersection.
AllocationPriority, CopyCost could be perhaps be maxima, although this could be restrictive.
No idea about AltOrderSelect.
That said, I do not want to increase the scope of this patch beyond Allocatable.


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