[llvm] [AArch64][SME2] Add FORM_STRIDED_TUPLE pseudo nodes (PR #116399)

[Benjamin Maxwell via llvm-commits]

================
@@ -28,6 +28,17 @@ def AArch64_restore_zt : SDNode<"AArch64ISD::RESTORE_ZT", SDTypeProfile<0, 2,
 def AArch64_save_zt : SDNode<"AArch64ISD::SAVE_ZT", SDTypeProfile<0, 2,
                              [SDTCisInt<0>, SDTCisPtrTy<1>]>,
                              [SDNPHasChain, SDNPSideEffect, SDNPMayStore]>;
+
+def SDT_FORM_STRIDED_TUPLE_X2 : SDTypeProfile<4, 4,
----------------
MacDue wrote:

Might be wrong, but shouldn't this be two results and two operands?
```suggestion
def SDT_FORM_STRIDED_TUPLE_X2 : SDTypeProfile<2, 2,
```

https://github.com/llvm/llvm-project/pull/116399