[llvm] [RISCV] Check for null LIS before trying to move AVL in canMutatePriorConfig. (PR #196673)

[Craig Topper via llvm-commits]

================
@@ -776,6 +776,10 @@ bool RISCVInsertVSETVLI::canMutatePriorConfig(
       VNInfo *VNI = getVNInfoFromReg(AVL.getReg(), MI, LIS);
       VNInfo *PrevVNI = getVNInfoFromReg(AVL.getReg(), PrevMI, LIS);
       if (!VNI || !PrevVNI || VNI != PrevVNI) {
+        // If LIS is null, we were not able to get the VNInfo so we don't know 
----------------
topperc wrote:

```suggestion
        // If LIS is null, we were not able to get the VNInfo so we don't know
```

https://github.com/llvm/llvm-project/pull/196673