[VPlan] Add VPTypeAnalysis constructor taking a VPlan (NFC).

Add constructor that retrieves the scalar type from the trip count
expression, if no canonical IV is available. Used in the verifier, in
preparation for late verification, when the canonical IV has been
dissolved.

Author: fhahn

llvm/lib/Transforms/Vectorize/VPlanAnalysis.cpp

@@ -20,6 +20,26 @@ using namespace llvm;
 
 #define DEBUG_TYPE "vplan"
 
+VPTypeAnalysis::VPTypeAnalysis(const VPlan &Plan)
+    : Ctx(Plan.getScalarHeader()->getIRBasicBlock()->getContext()) {
+  if (auto LoopRegion = Plan.getVectorLoopRegion()) {
+    if (const auto *CanIV = dyn_cast<VPCanonicalIVPHIRecipe>(
+            &LoopRegion->getEntryBasicBlock()->front())) {
+      CanonicalIVTy = CanIV->getScalarType();
+      return;
+    }
+  }
+
+  // If there's no canonical IV, retrieve the type from the trip count
+  // expression.
+  auto *TC = Plan.getTripCount();
+  if (TC->isLiveIn()) {
+    CanonicalIVTy = TC->getLiveInIRValue()->getType();
+    return;
+  }
+  CanonicalIVTy = cast<VPExpandSCEVRecipe>(TC)->getSCEV()->getType();
+}
+
 Type *VPTypeAnalysis::inferScalarTypeForRecipe(const VPBlendRecipe *R) {
   Type *ResTy = inferScalarType(R->getIncomingValue(0));
   for (unsigned I = 1, E = R->getNumIncomingValues(); I != E; ++I) {

llvm/lib/Transforms/Vectorize/VPlanAnalysis.h

@@ -58,6 +58,8 @@ class VPTypeAnalysis {
   VPTypeAnalysis(Type *CanonicalIVTy)
       : CanonicalIVTy(CanonicalIVTy), Ctx(CanonicalIVTy->getContext()) {}
 
+  VPTypeAnalysis(const VPlan &Plan);
+
   /// Infer the type of \p V. Returns the scalar type of \p V.
   Type *inferScalarType(const VPValue *V);
 

llvm/lib/Transforms/Vectorize/VPlanVerifier.cpp

@@ -455,8 +455,7 @@ bool VPlanVerifier::verify(const VPlan &Plan) {
 bool llvm::verifyVPlanIsValid(const VPlan &Plan) {
   VPDominatorTree VPDT;
   VPDT.recalculate(const_cast<VPlan &>(Plan));
-  VPTypeAnalysis TypeInfo(
-      const_cast<VPlan &>(Plan).getCanonicalIV()->getScalarType());
+  VPTypeAnalysis TypeInfo(Plan);
   VPlanVerifier Verifier(VPDT, TypeInfo);
   return Verifier.verify(Plan);
 }