[llvm] [InstCombine] Fold `(add X, (sext/zext (icmp eq X, C)))` (PR #93840)

[Yingwei Zheng via llvm-commits]

dtcxzyw wrote:

> > The IR diff LGTM. And there is no extra space for us to generalize this pattern (e.g., add->sub, eq -> ne) :)
> 
> What do you mean there is no extra space for us the generalize?

Both `(sub X, (sext/zext (icmp eq X, C)))` and `(add X, (sext/zext (icmp ne X, C)))` are not canonical forms.


https://github.com/llvm/llvm-project/pull/93840