[llvm] [InstCombine] Fix poison propagation in select of bitwise fold (PR #89701)

[Nikita Popov via llvm-commits]

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@@ -2596,6 +2602,13 @@ m_Not(const ValTy &V) {
   return m_c_Xor(m_AllOnes(), V);
 }
 
+template <typename ValTy>
+inline BinaryOp_match<cst_pred_ty<is_all_ones, false>, ValTy, Instruction::Xor,
+                      true>
+m_NotForbidPoison(const ValTy &V) {
+  return m_c_Xor(m_AllOnesForbidPoison(), V);
+}
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nikic wrote:

I prefer not to have unit tests for anything that has lit test coverage.

https://github.com/llvm/llvm-project/pull/89701