[PATCH] D70237: [X86] Add more addcarry tests

[Paweł Bylica via Phabricator via llvm-commits]

chfast added a comment.

> Thanks for the update. Where is the original source for sub_U256_without_i128_or_recursive? The IR is strange. It seems to use two different strategies for merging carry flags.

I don't really have a standalone implementation for it at the moment. It is code for this procedure for uint256 type: https://github.com/chfast/intx/blob/master/include/intx/intx.hpp#L528-L532. It is the same as the one for add, just `+` replaced with `-` and `<` with `>` for checking the carry flag. But probably LLVM has disturbed it a bit because add is proffered over sub in some places.


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https://reviews.llvm.org/D70237