[llvm] [ARM] Lower BSWAP on Pre-V6 ARM (PR #155113)

[Matt Arsenault via llvm-commits]

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@@ -9508,6 +9508,42 @@ static bool isAddSubZExt(SDNode *N, SelectionDAG &DAG) {
   return false;
 }
 
+static SDValue LowerBSWAP(SDValue Op, SelectionDAG &DAG) {
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arsenm wrote:

This is a generic expansion that doesn't belong in target code. Don't we already have this? 

https://github.com/llvm/llvm-project/pull/155113