[llvm] [BDCE] Handle multi-use `and`/`or` on demanded bits (PR #79688)

[via llvm-commits]

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@@ -125,6 +125,28 @@ static bool bitTrackingDCE(Function &F, DemandedBits &DB) {
       }
     }
 
+    // Simplify `and` or `or` when their mask does not affect the demanded bits.
+    if (auto *BO = dyn_cast<BinaryOperator>(&I)) {
+      unsigned Opc = BO->getOpcode();
+      if (Opc == Instruction::And || Opc == Instruction::Or) {
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XChy wrote:

Could you turn it into a switch, please? I think there is room for other operators like `xor`, `add` to be here in the future.

https://github.com/llvm/llvm-project/pull/79688