[llvm] [VPlan] Unify inner and outer loop paths (NFCI). (PR #192868)

[Ramkumar Ramachandra via llvm-commits]

================
@@ -7657,30 +7646,38 @@ VPRecipeBuilder::tryToCreateWidenNonPhiRecipe(VPSingleDefRecipe *R,
 // optimizations.
 static void printOptimizedVPlan(VPlan &) {}
 
-void LoopVectorizationPlanner::buildVPlansWithVPRecipes(ElementCount MinVF,
-                                                        ElementCount MaxVF) {
+void LoopVectorizationPlanner::buildVPlans(ElementCount MinVF,
+                                           ElementCount MaxVF) {
   if (ElementCount::isKnownGT(MinVF, MaxVF))
     return;
 
-  assert(OrigLoop->isInnermost() && "Inner loop expected.");
-
-  const LoopAccessInfo *LAI = Legal->getLAI();
-  LoopVersioning LVer(*LAI, LAI->getRuntimePointerChecking()->getChecks(),
-                      OrigLoop, LI, DT, PSE.getSE());
-  if (!LAI->getRuntimePointerChecking()->getChecks().empty() &&
-      !LAI->getRuntimePointerChecking()->getDiffChecks()) {
-    // Only use noalias metadata when using memory checks guaranteeing no
-    // overlap across all iterations.
-    LVer.prepareNoAliasMetadata();
+  bool IsInnerLoop = OrigLoop->isInnermost();
+
+  // Set up loop versioning for inner loops with memory runtime checks.
+  // Outer loops don't have LoopAccessInfo since canVectorizeMemory() is not
+  // called for them.
+  std::optional<LoopVersioning> LVer;
+  if (IsInnerLoop) {
+    const LoopAccessInfo *LAI = Legal->getLAI();
+    LVer.emplace(*LAI, LAI->getRuntimePointerChecking()->getChecks(), OrigLoop,
+                 LI, DT, PSE.getSE());
+    if (!LAI->getRuntimePointerChecking()->getChecks().empty() &&
+        !LAI->getRuntimePointerChecking()->getDiffChecks()) {
+      // Only use noalias metadata when using memory checks guaranteeing no
+      // overlap across all iterations.
+      LVer->prepareNoAliasMetadata();
+    }
   }
 
   // Create initial base VPlan0, to serve as common starting point for all
   // candidates built later for specific VF ranges.
   auto VPlan0 = VPlanTransforms::buildVPlan0(
       OrigLoop, *LI, Legal->getWidestInductionType(),
-      getDebugLocFromInstOrOperands(Legal->getPrimaryInduction()), PSE, &LVer);
+      getDebugLocFromInstOrOperands(Legal->getPrimaryInduction()), PSE,
+      LVer ? &*LVer : nullptr);
----------------
artagnon wrote:

```suggestion
      LVer);
```

Hm, would be better to refactor buildVPlan0 to take an optional LVer, and land that change independently?

https://github.com/llvm/llvm-project/pull/192868