[llvm] [AArch64] Stack probing for dynamic allocas in SelectionDAG (PR #66525)

[Eli Friedman via llvm-commits]

efriedma-quic wrote:

The `assert(MFI.hasVarSizedObjects() && "non-reserved call frame without var sized objects?");` is asserting that hasReservedCallFrame checks exactly that condition.

https://github.com/llvm/llvm-project/pull/66525