[llvm] [GlobalISel] Add G_CONCAT_VECTOR computeKnownBits (PR #141933)

[Matt Arsenault via llvm-commits]

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@@ -675,6 +675,31 @@ void GISelValueTracking::computeKnownBitsImpl(Register R, KnownBits &Known,
     }
     break;
   }
+  case TargetOpcode::G_CONCAT_VECTORS: {
+    if (MRI.getType(MI.getOperand(0).getReg()).isScalableVector())
+      break;
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arsenm wrote:

Is this even a legal operation for scalable vectors? 

https://github.com/llvm/llvm-project/pull/141933