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

[Graham Hunter via llvm-commits]

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@@ -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)) {
+        HasStore = true;
+        if (SI->isSimple())
+          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;
+      }
+
       if (I.mayWriteToMemory()) {
         // We don't support writes to memory.
         reportVectorizationFailure(
-            "Writes to memory unsupported in early exit loops",
-            "Cannot vectorize early exit loop with writes to memory",
+            "Complex writes to memory unsupported in early exit loops",
+            "Cannot vectorize early exit loop with complex writes to memory",
             "WritesInEarlyExitLoop", ORE, TheLoop);
         return false;
-      } else if (!IsSafeOperation(&I)) {
+      }
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huntergr-arm wrote:

Ah, that was just an unrelated NFC change to comply with the coding standards (no else/else if after a return).

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