[llvm] [RISCV][VLOPT] Add support for checkUsers when UserMI is a Single-Width Integer Reduction (PR #120345)

[Craig Topper via llvm-commits]

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@@ -930,26 +960,64 @@ bool RISCVVLOptimizer::isCandidate(const MachineInstr &MI) const {
   return true;
 }
 
-bool RISCVVLOptimizer::checkUsers(const MachineOperand *&CommonVL,
-                                  MachineInstr &MI) {
+std::optional<const MachineOperand>
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topperc wrote:

The `const` here doesn't do anything

https://github.com/llvm/llvm-project/pull/120345