[llvm] Port `NVPTXTargetLowering::LowerCONCAT_VECTORS` to SelectionDAG (PR #120030)

[Matt Arsenault via llvm-commits]

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@@ -279,9 +285,14 @@ define <4 x i32> @concat_v4i32(<2 x i32> %op1, <2 x i32> %op2)  {
 ;
 ; NONEON-NOSVE-LABEL: concat_v4i32:
 ; NONEON-NOSVE:       // %bb.0:
-; NONEON-NOSVE-NEXT:    stp d0, d1, [sp, #-16]!
-; NONEON-NOSVE-NEXT:    .cfi_def_cfa_offset 16
-; NONEON-NOSVE-NEXT:    ldr q0, [sp], #16
+; NONEON-NOSVE-NEXT:    stp d0, d1, [sp, #-32]!
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arsenm wrote:

Not sure if aarch64 would prefer to keep the old stack path.

https://github.com/llvm/llvm-project/pull/120030