[llvm] [VPlan] Add transform to replace VPWidenCanonicalIV with wide IV. (PR #194267)

[Ramkumar Ramachandra via llvm-commits]

================
@@ -749,6 +749,56 @@ static void removeRedundantCanonicalIVs(VPlan &Plan) {
   WidenNewIV->eraseFromParent();
 }
 
+void VPlanTransforms::replaceWideCanonicalIVWithWideIV(
+    VPlan &Plan, ScalarEvolution &SE, const TargetTransformInfo &TTI,
+    TargetTransformInfo::TargetCostKind CostKind, ElementCount VF, unsigned UF,
+    const SmallPtrSetImpl<const Value *> &ValuesToIgnore) {
+  VPRegionBlock *LoopRegion = Plan.getVectorLoopRegion();
+  if (!LoopRegion || Plan.hasScalarVFOnly())
+    return;
+
+  VPValue *CanonicalIV = LoopRegion->getCanonicalIV();
+  auto *WideCanIV = vputils::findUserOf<VPWidenCanonicalIVRecipe>(CanonicalIV);
+  if (!WideCanIV || vputils::onlyFirstLaneUsed(WideCanIV) ||
+      vputils::onlyScalarValuesUsed(WideCanIV))
----------------
artagnon wrote:

```suggestion
  if (!WideCanIV ||
      vputils::onlyScalarValuesUsed(WideCanIV))
```

Isn't onlyScalarValuesUsed a strict superset of onlyFirstLaneUsed?

https://github.com/llvm/llvm-project/pull/194267