[clang] [llvm] [AArch64][SelectionDAG] Add CodeGen support for scalar FEAT_CPA (PR #105669)

[Rodolfo Wottrich via cfe-commits]

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@@ -10382,6 +10382,26 @@ let Predicates = [HasCPA] in {
   // Scalar multiply-add/subtract
   def MADDPT : MulAccumCPA<0, "maddpt">;
   def MSUBPT : MulAccumCPA<1, "msubpt">;
+
+  // Rules to use CPA instructions in pointer arithmetic patterns which are not
+  // folded into loads/stores. The AddedComplexity serves to help supersede
+  // other simpler (non-CPA) patterns and make sure CPA is used instead.
+  let AddedComplexity = 20 in {
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rgwott wrote:

That is a remainder from the previous PR, in which SelectionDAG did not differentiate between ptr and integer arithmetic (which was wrong), and this made instr selection "correct". I removed it now, well spotted.

https://github.com/llvm/llvm-project/pull/105669