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

[David Sherwood via llvm-commits]

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@@ -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;
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david-arm wrote:

Thanks for this! I think the comment above also looks out of date because there are 5 operands. Might be worth cleaning this up while you're here? Or perhaps even just move the comment above `isUnrolled`?

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