[llvm] [LLVM][ConstantFold] Undefined values are not constant (PR #130713)

[Yingwei Zheng via llvm-commits]

dtcxzyw wrote:

> Obviously an undefined variable cannot be known at compile-time, so __builtin_constant_p() needs to return false.

IMO `undef/poison` can be refined to any constant value.


https://github.com/llvm/llvm-project/pull/130713