[PATCH] D70462: [InstCombine] Change InstCombineAddSub to not perform constant folding when there is an intermediate use of the source register.

[Danilo Carvalho Grael via Phabricator via llvm-commits]

dancgr added a comment.

In D70462#1752506 <https://reviews.llvm.org/D70462#1752506>, @lebedev.ri wrote:

> -1 to adding more artificial one-use restrictions.
>  I agree there is a general problem of unability to see if
>  there exists a particular instruction already.


I'm wondering why we should avoid one-use restrictions. Is there any discussion that I'm not aware of?

In this case, we only want to apply the folding if there is only one use of first expression. If there is any more than that, the folding won't give any improvement or cause issues with other optimizations. How would you suggest that I avoid this issue without checking for one-use?


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https://reviews.llvm.org/D70462