[llvm] [InstCombine] Reassociate xor and disjoint or through zext (PR #214970)

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@@ -435,12 +435,19 @@ static bool simplifyAssocCastAssoc(BinaryOperator *BinOp1,
   if (!BinOp2 || !BinOp2->hasOneUse())
     return false;
 
-  // `or disjoint` is equivalent to xor.
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ParkHanbum wrote:

I believe SimplifyAssociativeOrCommutative should already be able to handle the commuted form. Was this logic added after confirming that the pattern does not reach BinOp2? I don't seem to see a test case covering that scenario.

https://github.com/llvm/llvm-project/pull/214970