[llvm] [IPSCCP] Do not attempt `tryToReplaceWithConstant` if may break invariants (PR #102820)

[Nikita Popov via llvm-commits]

https://github.com/nikic requested changes to this pull request.

This doesn't make sense to me. Propagating the constant isn't useful only for DCE, it can also enable other optimizations that now work on a global variable instead of on an opaque value.

https://github.com/llvm/llvm-project/pull/102820