[PATCH] D108643: Introduce _BitInt, deprecate _ExtInt

Wed Sep 15 06:01:10 PDT 2021

erichkeane added a comment.

> Okay. Sorry if I came down on you personally, I know what it's like to be in the middle on things like this

Thank you, I very much appreciate that.

> I'm not sure if there's a way to get LLVM to treat loaded values as only having N valid bits.
>
> Do you have resources on the patterns of code that you expect to see for `_BitInt` types?  Like, what operations are most important here?
>
> If addition, subtraction, and comparison are the most important operations — especially if we don't consider shifts or multiplication important — the best ABI might actually be to keep the value left-shifted.

I don't have any such resources.  Our users treat them as 'just integers', and my understanding is that is the design intent we brought to WG14.  There is SOME experimentation to use these as 'Big Ints' as well.

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https://reviews.llvm.org/D108643