[InstCombine] Fold (X == 0 ? Y : 0) | X to X == 0 ? Y : X

[s-barannikov]

https://gcc.godbolt.org/z/9vG3fEv8M

In this example (taken from compiler-rt), select could be folded with or: https://alive2.llvm.org/ce/z/NqzEaM

[YLChenZ]

I'd like to work on this issue. Could I get assigned?

[nikic]

I found the issue description/title here confusing. The actual proposed fold is this one: https://alive2.llvm.org/ce/z/KSanC2

As far as I can tell, there is no relation to the disjoint flag and the fold from the PR title is incorrect: https://alive2.llvm.org/ce/z/87DVSD

[s-barannikov]

Sorry for the confusion and thanks for the correction.
I dropped the setence mentioning disjoint from the description.