[llvm] [InstCombine] fold `(icmp eq/ne (or disjoint x, C0), C1)` -> `(icmp eq/ne x, C0^C1)` (PR #87734)

[via llvm-commits]

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@@ -2049,6 +2050,16 @@ Instruction *InstCombinerImpl::foldICmpOrConstant(ICmpInst &Cmp,
   }
 
   Value *OrOp0 = Or->getOperand(0), *OrOp1 = Or->getOperand(1);
+
+  // (icmp eq/ne (or disjoint x, C0), C1)
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goldsteinn wrote:

We have some other equality folds here, I think we should move them all when/if we move them.

https://github.com/llvm/llvm-project/pull/87734