[llvm] [ValueTracking][X86] Compute KnownBits for phadd/phsub (PR #92429)

[via llvm-commits]

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@@ -37262,6 +37262,27 @@ void X86TargetLowering::computeKnownBitsForTargetNode(const SDValue Op,
     }
     break;
   }
+  case X86ISD::HADD: {
+    Known = DAG.computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
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mskamp wrote:

I've added the implementation with 4 `computeKnownBits` calls in the hope that it does not slow down the analysis too much.

https://github.com/llvm/llvm-project/pull/92429