[llvm] [InstCombine] Teach tryFactorization to treat a disjoint Or like an Add. (PR #75691)

[Philip Reames via llvm-commits]

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@@ -646,6 +646,11 @@ static Value *tryFactorization(BinaryOperator &I, const SimplifyQuery &SQ,
   Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
   Instruction::BinaryOps TopLevelOpcode = I.getOpcode();
 
+  // Treat a disjoint Or like an Add if the inner opcode is a Mul.
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preames wrote:

If I'm reading this right, it should always be legal to treat the disjoint or as and add, and the inner opcode check is to ensure it can distribute?  i.e. it's basically a profitability check?  If so, can you adjust the comment to be a bit more clear about that?

https://github.com/llvm/llvm-project/pull/75691