[VPlan] Check type directly in ::isCanonical (NFC).

Directly check the type of the wide induction matches the canonical
induction.

Refactor suggested in and in preparation for
#89603

Author: fhahn

llvm/lib/Transforms/Vectorize/VPlan.h

@@ -1757,7 +1757,8 @@ class VPWidenIntOrFpInductionRecipe : public VPHeaderPHIRecipe {
   const InductionDescriptor &getInductionDescriptor() const { return IndDesc; }
 
   /// Returns true if the induction is canonical, i.e. starting at 0 and
-  /// incremented by UF * VF (= the original IV is incremented by 1).
+  /// incremented by UF * VF (= the original IV is incremented by 1) and has the
+  /// same type as the canonical induction.
   bool isCanonical() const;
 
   /// Returns the scalar type of the induction.

llvm/lib/Transforms/Vectorize/VPlanRecipes.cpp

@@ -1222,7 +1222,9 @@ bool VPWidenIntOrFpInductionRecipe::isCanonical() const {
     return false;
   auto *StepC = dyn_cast<ConstantInt>(getStepValue()->getLiveInIRValue());
   auto *StartC = dyn_cast<ConstantInt>(getStartValue()->getLiveInIRValue());
-  return StartC && StartC->isZero() && StepC && StepC->isOne();
+  auto *CanIV = cast<VPCanonicalIVPHIRecipe>(&*getParent()->begin());
+  return StartC && StartC->isZero() && StepC && StepC->isOne() &&
+         getScalarType() == CanIV->getScalarType();
 }
 
 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)

llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp

@@ -452,8 +452,7 @@ static void removeRedundantCanonicalIVs(VPlan &Plan) {
   for (VPRecipeBase &Phi : HeaderVPBB->phis()) {
     auto *WidenOriginalIV = dyn_cast<VPWidenIntOrFpInductionRecipe>(&Phi);
 
-    if (!WidenOriginalIV || !WidenOriginalIV->isCanonical() ||
-        WidenOriginalIV->getScalarType() != WidenNewIV->getScalarType())
+    if (!WidenOriginalIV || !WidenOriginalIV->isCanonical())
       continue;
 
     // Replace WidenNewIV with WidenOriginalIV if WidenOriginalIV provides