[llvm] [LV] Add initial legality checks for ee loops with stores (PR #145663)

[David Sherwood via llvm-commits]

================
@@ -1747,16 +1782,31 @@ bool LoopVectorizationLegality::isVectorizableEarlyExitLoop() {
     }
   };
 
+  bool HasStore = false;
   for (auto *BB : TheLoop->blocks())
     for (auto &I : *BB) {
+      if (StoreInst *SI = dyn_cast<StoreInst>(&I)) {
----------------
david-arm wrote:

I think you can fold this logic into the `if (I.mayWriteToMemory()) {` block below, i.e.

```
      if (I.mayWriteToMemory()) {
        if (isa<StoreInst>(&I) && cast<StoreInst>(&I)->isSimple()) {
          HasStore = true;
          continue;
        }

        reportVectorizationFailure(
            "Complex writes to memory unsupported in early exit loops",
            "Cannot vectorize early exit loop with complex writes to memory",
            "WritesInEarlyExitLoop", ORE, TheLoop);
        return false;
      }
```

https://github.com/llvm/llvm-project/pull/145663