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

[Sander de Smalen via llvm-commits]

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@@ -8666,6 +8717,29 @@ void AArch64TargetLowering::AdjustInstrPostInstrSelection(MachineInstr &MI,
     }
   }
 
+  if (MI.getOpcode() == AArch64::FORM_TRANSPOSED_REG_TUPLE_X2_PSEUDO ||
+      MI.getOpcode() == AArch64::FORM_TRANSPOSED_REG_TUPLE_X4_PSEUDO) {
+    // If input values to the FORM_TRANSPOSED_REG_TUPLE pseudo aren't copies
+    // from a StridedOrContiguous class, fall back on REG_SEQUENCE node.
+    if (!shouldUseFormStridedPseudo(MI)) {
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sdesmalen-arm wrote:

nit: Maybe fold those conditions into one? or otherwise bail out early if `shouldUseFormStridedPseudo(MI) == true`, to avoid a level of indentation?

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