[llvm] [VPlan] Add VPRegionBlock::getCanonicalIVType (NFC). (PR #164127)

[Florian Hahn via llvm-commits]

https://github.com/fhahn updated https://github.com/llvm/llvm-project/pull/164127

>From 9736ed5e80dc65e4685b22ca0b6828e9f3ab4901 Mon Sep 17 00:00:00 2001
From: Florian Hahn <flo at fhahn.com>
Date: Sat, 18 Oct 2025 21:47:25 +0100
Subject: [PATCH] [VPlan] Add getCanonicalIVType (NFC).

Split off from https://github.com/llvm/llvm-project/pull/156262.

Similar to VPRegionBlock::getCanonicalIV, add helper to get the type of
the canonical IV, in preparation for removing VPCanonicalIVPHIRecipe.
---
 llvm/lib/Transforms/Vectorize/VPlan.h         |  6 ++++++
 .../lib/Transforms/Vectorize/VPlanRecipes.cpp |  3 +--
 .../Transforms/Vectorize/VPlanTransforms.cpp  | 19 ++++++++++---------
 llvm/lib/Transforms/Vectorize/VPlanUnroll.cpp |  3 +--
 4 files changed, 18 insertions(+), 13 deletions(-)

diff --git a/llvm/lib/Transforms/Vectorize/VPlan.h b/llvm/lib/Transforms/Vectorize/VPlan.h
index 2591df8943752..dced581e42237 100644
--- a/llvm/lib/Transforms/Vectorize/VPlan.h
+++ b/llvm/lib/Transforms/Vectorize/VPlan.h
@@ -4103,6 +4103,12 @@ class LLVM_ABI_FOR_TEST VPRegionBlock : public VPBlockBase {
   const VPCanonicalIVPHIRecipe *getCanonicalIV() const {
     return const_cast<VPRegionBlock *>(this)->getCanonicalIV();
   }
+
+  /// Return the type of the canonical IV for loop regions.
+  Type *getCanonicalIVType() { return getCanonicalIV()->getScalarType(); }
+  const Type *getCanonicalIVType() const {
+    return getCanonicalIV()->getScalarType();
+  }
 };
 
 inline VPRegionBlock *VPRecipeBase::getRegion() {
diff --git a/llvm/lib/Transforms/Vectorize/VPlanRecipes.cpp b/llvm/lib/Transforms/Vectorize/VPlanRecipes.cpp
index 931a5b7582c4e..49598ba30f6b6 100644
--- a/llvm/lib/Transforms/Vectorize/VPlanRecipes.cpp
+++ b/llvm/lib/Transforms/Vectorize/VPlanRecipes.cpp
@@ -2368,9 +2368,8 @@ bool VPWidenIntOrFpInductionRecipe::isCanonical() const {
     return false;
   auto *StepC = dyn_cast<ConstantInt>(getStepValue()->getLiveInIRValue());
   auto *StartC = dyn_cast<ConstantInt>(getStartValue()->getLiveInIRValue());
-  auto *CanIV = getRegion()->getCanonicalIV();
   return StartC && StartC->isZero() && StepC && StepC->isOne() &&
-         getScalarType() == CanIV->getScalarType();
+         getScalarType() == getRegion()->getCanonicalIVType();
 }
 
 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
diff --git a/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp b/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp
index 84817d78a077a..25c184ddd3258 100644
--- a/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp
+++ b/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp
@@ -801,7 +801,7 @@ static VPValue *optimizeEarlyExitInductionUser(VPlan &Plan,
   // Calculate the final index.
   VPRegionBlock *LoopRegion = Plan.getVectorLoopRegion();
   auto *CanonicalIV = LoopRegion->getCanonicalIV();
-  Type *CanonicalIVType = CanonicalIV->getScalarType();
+  Type *CanonicalIVType = LoopRegion->getCanonicalIVType();
   VPBuilder B(cast<VPBasicBlock>(PredVPBB));
 
   DebugLoc DL = cast<VPInstruction>(Op)->getDebugLoc();
@@ -2404,8 +2404,8 @@ static VPActiveLaneMaskPHIRecipe *addVPLaneMaskPhiAndUpdateExitBranch(
       "index.part.next");
 
   // Create the active lane mask instruction in the VPlan preheader.
-  VPValue *ALMMultiplier = Plan.getOrAddLiveIn(
-      ConstantInt::get(TopRegion->getCanonicalIV()->getScalarType(), 1));
+  VPValue *ALMMultiplier =
+      Plan.getOrAddLiveIn(ConstantInt::get(TopRegion->getCanonicalIVType(), 1));
   auto *EntryALM = Builder.createNaryOp(VPInstruction::ActiveLaneMask,
                                         {EntryIncrement, TC, ALMMultiplier}, DL,
                                         "active.lane.mask.entry");
@@ -2491,8 +2491,9 @@ void VPlanTransforms::addActiveLaneMask(
          "UseActiveLaneMaskForControlFlow");
 
   VPRegionBlock *LoopRegion = Plan.getVectorLoopRegion();
-  auto *FoundWidenCanonicalIVUser = find_if(
-      LoopRegion->getCanonicalIV()->users(), IsaPred<VPWidenCanonicalIVRecipe>);
+  auto *CanonicalIV = LoopRegion->getCanonicalIV();
+  auto *FoundWidenCanonicalIVUser =
+      find_if(CanonicalIV->users(), IsaPred<VPWidenCanonicalIVRecipe>);
   assert(FoundWidenCanonicalIVUser &&
          "Must have widened canonical IV when tail folding!");
   VPSingleDefRecipe *HeaderMask = findHeaderMask(Plan);
@@ -2505,7 +2506,7 @@ void VPlanTransforms::addActiveLaneMask(
   } else {
     VPBuilder B = VPBuilder::getToInsertAfter(WideCanonicalIV);
     VPValue *ALMMultiplier = Plan.getOrAddLiveIn(
-        ConstantInt::get(LoopRegion->getCanonicalIV()->getScalarType(), 1));
+        ConstantInt::get(LoopRegion->getCanonicalIVType(), 1));
     LaneMask =
         B.createNaryOp(VPInstruction::ActiveLaneMask,
                        {WideCanonicalIV, Plan.getTripCount(), ALMMultiplier},
@@ -2777,7 +2778,7 @@ void VPlanTransforms::addExplicitVectorLength(
   VPBasicBlock *Header = LoopRegion->getEntryBasicBlock();
 
   auto *CanonicalIVPHI = LoopRegion->getCanonicalIV();
-  auto *CanIVTy = CanonicalIVPHI->getScalarType();
+  auto *CanIVTy = LoopRegion->getCanonicalIVType();
   VPValue *StartV = CanonicalIVPHI->getStartValue();
 
   // Create the ExplicitVectorLengthPhi recipe in the main loop.
@@ -4295,10 +4296,10 @@ void VPlanTransforms::narrowInterleaveGroups(VPlan &Plan, ElementCount VF,
   VPBuilder PHBuilder(Plan.getVectorPreheader());
 
   VPValue *UF = Plan.getOrAddLiveIn(
-      ConstantInt::get(CanIV->getScalarType(), 1 * Plan.getUF()));
+      ConstantInt::get(VectorLoop->getCanonicalIVType(), 1 * Plan.getUF()));
   if (VF.isScalable()) {
     VPValue *VScale = PHBuilder.createElementCount(
-        CanIV->getScalarType(), ElementCount::getScalable(1));
+        VectorLoop->getCanonicalIVType(), ElementCount::getScalable(1));
     VPValue *VScaleUF = PHBuilder.createNaryOp(Instruction::Mul, {VScale, UF});
     Inc->setOperand(1, VScaleUF);
     Plan.getVF().replaceAllUsesWith(VScale);
diff --git a/llvm/lib/Transforms/Vectorize/VPlanUnroll.cpp b/llvm/lib/Transforms/Vectorize/VPlanUnroll.cpp
index cfd1a741ee841..f15113c6293bc 100644
--- a/llvm/lib/Transforms/Vectorize/VPlanUnroll.cpp
+++ b/llvm/lib/Transforms/Vectorize/VPlanUnroll.cpp
@@ -69,8 +69,7 @@ class UnrollState {
                                 VPBasicBlock::iterator InsertPtForPhi);
 
   VPValue *getConstantVPV(unsigned Part) {
-    Type *CanIVIntTy =
-        Plan.getVectorLoopRegion()->getCanonicalIV()->getScalarType();
+    Type *CanIVIntTy = Plan.getVectorLoopRegion()->getCanonicalIVType();
     return Plan.getOrAddLiveIn(ConstantInt::get(CanIVIntTy, Part));
   }