[llvm] [SelectionDAG][PPC][SystemZ] Fix GET_DYNAMIC_AREA_OFFSET chain result (PR #116507)

[Sergei Barannikov via llvm-commits]

s-barannikov wrote:

No tests. The issue was discovered when working on a SDNode verification feature, I'll present an RFC later.


https://github.com/llvm/llvm-project/pull/116507