[llvm] [SDAG] Only apply sincos/frexp stack slot folding to IR pointers (PR #115346)

[via llvm-commits]

zmodem wrote:

Confirmed that this fixes the problem we hit in #115323. I'm not familiar enough with this part of SelectionDAG to say whether it's the Right Fix(tm) though.

https://github.com/llvm/llvm-project/pull/115346