[llvm] [SDAG] Read-only intrinsics must have WillReturn attribute to be treated as loads (PR #99999)

[Matt Arsenault via llvm-commits]

arsenm wrote:

So after #98968, you no longer have a case that actually hits this situation?

It seems malformed to me to permit an intrinsic that is treated as side-effect free, but also can exit the program. If you add an error in IntrinsicEmitter for any cases that hit this, does anything break? 

https://github.com/llvm/llvm-project/pull/99999