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

[Sergei Barannikov via llvm-commits]

s-barannikov wrote:

I got confused by the wording "offset to the most recent dynamic alloca". On my target stack grows up, and the offset is therefore a dynamic value (equal to the size of the most recent allocation). However, LangRef says:

> For targets where stack grows upwards, the situation is a bit more complicated, because subtracting this value from stack pointer would get the address one past the end of the most recent dynamic alloca.

So this "offset" should not be read as "offset to the beginning".

I abandoning this patch then.


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