[llvm] [InstCombine] Use sadd.sat for chained ldexp fold (PR #199274)

[Eli Friedman via llvm-commits]

https://github.com/efriedma-quic requested changes to this pull request.

Saturation only works if the largest/smallest signed integer are guaranteed to produce infinity/zero.

Please be more careful with AI-generated fixes.

https://github.com/llvm/llvm-project/pull/199274