[llvm] [VPlan] Factor out isUnrolled() helper in VPWidenIntOrFpInductionRecipe. NFC (PR #137635)

[Luke Lau via llvm-commits]

https://github.com/lukel97 created https://github.com/llvm/llvm-project/pull/137635

Split off from #129508, this generalizes getSplatVFValue and getLastUnrolledPartOperand so they don't need changed if another operand is added.


>From 1a2ec3e9de2a30d6645f168ffa072daf7f732209 Mon Sep 17 00:00:00 2001
From: Luke Lau <luke at igalia.com>
Date: Mon, 28 Apr 2025 21:54:03 +0800
Subject: [PATCH] [VPlan] Factor out isUnrolled() helper in
 VPWidenIntOrFpInductionRecipe. NFC

Split off from #129508, this generalizes getSplatVFValue and getLastUnrolledPartOperand so they don't need changed if another operand is added.
---
 llvm/lib/Transforms/Vectorize/VPlan.h | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/llvm/lib/Transforms/Vectorize/VPlan.h b/llvm/lib/Transforms/Vectorize/VPlan.h
index 147ca5b4475b5..73ffacb7cc2f9 100644
--- a/llvm/lib/Transforms/Vectorize/VPlan.h
+++ b/llvm/lib/Transforms/Vectorize/VPlan.h
@@ -1851,6 +1851,8 @@ class VPWidenInductionRecipe : public VPHeaderPHIRecipe {
 class VPWidenIntOrFpInductionRecipe : public VPWidenInductionRecipe {
   TruncInst *Trunc;
 
+  bool isUnrolled() const { return getNumOperands() == 5; }
+
 public:
   VPWidenIntOrFpInductionRecipe(PHINode *IV, VPValue *Start, VPValue *Step,
                                 VPValue *VF, const InductionDescriptor &IndDesc,
@@ -1901,7 +1903,7 @@ class VPWidenIntOrFpInductionRecipe : public VPWidenInductionRecipe {
   VPValue *getSplatVFValue() {
     // If the recipe has been unrolled (4 operands), return the VPValue for the
     // induction increment.
-    return getNumOperands() == 5 ? getOperand(3) : nullptr;
+    return isUnrolled() ? getOperand(getNumOperands() - 2) : nullptr;
   }
 
   /// Returns the first defined value as TruncInst, if it is one or nullptr
@@ -1923,7 +1925,7 @@ class VPWidenIntOrFpInductionRecipe : public VPWidenInductionRecipe {
   /// the last unrolled part, if it exists. Returns itself if unrolling did not
   /// take place.
   VPValue *getLastUnrolledPartOperand() {
-    return getNumOperands() == 5 ? getOperand(4) : this;
+    return isUnrolled() ? getOperand(getNumOperands() - 1) : this;
   }
 };