[llvm] [X86] Improve KnownBits for X86ISD::PSADBW nodes (PR #83830)

[via llvm-commits]

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@@ -54916,6 +54952,11 @@ static SDValue combineVectorCompare(SDNode *N, SelectionDAG &DAG,
       return DAG.getConstant(0, DL, VT);
   }
 
+  const TargetLowering &TLI = DAG.getTargetLoweringInfo();
+  if (TLI.SimplifyDemandedBits(
+          SDValue(N, 0), APInt::getAllOnes(VT.getScalarSizeInBits()), DCI))
+    return SDValue(N, 0);
+
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goldsteinn wrote:

Will this not get called else where?
Either way, this seems like it should be a seperate commit.

https://github.com/llvm/llvm-project/pull/83830