[llvm] [RISCV] Adjust LMUL if not used to avoid VL toggle (PR #69259)

[Philip Reames via llvm-commits]

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@@ -1484,6 +1535,15 @@ void RISCVInsertVSETVLI::doLocalPostpass(MachineBasicBlock &MBB) {
       Used.demandVL();
 
     if (NextMI) {
+      if (auto NewVType = canAdjustSEWLMULRatio(MI, *NextMI, Used)) {
+        MI.getOperand(2).setImm(*NewVType);
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preames wrote:

Have we properly guarded for the save/restore form which has a vreg as operand 2?

https://github.com/llvm/llvm-project/pull/69259