[llvm] [DAGCombiner] Fold min/max vscale, C -> C (PR #174708)

[Simon Pilgrim via llvm-commits]

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@@ -6253,6 +6243,34 @@ SDValue DAGCombiner::visitIMINMAX(SDNode *N) {
                                         SDLoc(N), VT, N0, N1))
     return SD;
 
+  // Fold operation with vscale operands.
+  if (N0.getOpcode() == ISD::VSCALE && N1.getOpcode() == ISD::VSCALE) {
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RKSimon wrote:

Are you looking at adding SelectionDAG computeConstantRange / computeConstantRangeIncludingKnownBits? 

https://github.com/llvm/llvm-project/pull/174708