[PATCH] D125130: [CodeGen] Clarify the semantics of ADDCARRY/SUBCARRY

[Craig Topper via Phabricator via llvm-commits]

craig.topper added a comment.

In D125130#3497763 <https://reviews.llvm.org/D125130#3497763>, @efriedma wrote:

> I don't think most people are going to be familiar with "active high"/"active low" terminology.  At least, I had to look it up.
>
> I think it makes sense to:
>
> 1. Explicitly mention the relationship with UADDO/USUBO.
> 2. Explicitly call out that for subtraction, the native carry flag is the inverse of what USUBO produces.

What is meant by "native carry flag" here? X86's carry flag matches the USUBO output.

I wonder if the use of the word "carry" on subtract is misleading. Should it be "borrow" instead?


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https://reviews.llvm.org/D125130