[llvm] [VPlan] Remove redundant VPIRValue cast in ::computeCost (NFC) (PR #207525)

[Florian Hahn via llvm-commits]

https://github.com/fhahn created https://github.com/llvm/llvm-project/pull/207525

We can directly cast o VPConstantInt.

>From d1f08a031b2d8e5ea31efa65bba1fea95a8a10ac Mon Sep 17 00:00:00 2001
From: Florian Hahn <flo at fhahn.com>
Date: Wed, 24 Jun 2026 10:10:36 +0100
Subject: [PATCH] [VPlan] Remove redundant VPIRValue cast in ::computeCost
 (NFC)

We can directly cast o VPConstantInt.
---
 .../lib/Transforms/Vectorize/VPlanRecipes.cpp | 35 +++++++++----------
 1 file changed, 16 insertions(+), 19 deletions(-)

diff --git a/llvm/lib/Transforms/Vectorize/VPlanRecipes.cpp b/llvm/lib/Transforms/Vectorize/VPlanRecipes.cpp
index 24abcf7646066..258ca7296006b 100644
--- a/llvm/lib/Transforms/Vectorize/VPlanRecipes.cpp
+++ b/llvm/lib/Transforms/Vectorize/VPlanRecipes.cpp
@@ -2951,9 +2951,8 @@ InstructionCost VPDerivedIVRecipe::computeCost(ElementCount VF,
     bool NeedsMul = true, NeedsAdd = true, NeedsShl = false;
 
     // If the start value is zero the add gets folded away.
-    if (auto *VPV = dyn_cast<VPIRValue>(getStartValue()))
-      if (auto *StartC = dyn_cast<ConstantInt>(VPV->getValue()))
-        NeedsAdd = !StartC->isZero();
+    if (auto *StartC = dyn_cast<VPConstantInt>(getStartValue()))
+      NeedsAdd = !StartC->isZero();
 
     // For some values of step the arithmetic changes:
     //  1. A step of 1 requires no operation.
@@ -2961,22 +2960,20 @@ InstructionCost VPDerivedIVRecipe::computeCost(ElementCount VF,
     //  3. A power-of-2 step will use a shl, instead of a mul.
     Type *StepTy = getStepValue()->getScalarType();
     InstructionCost Cost(0);
-    if (auto *VPV = dyn_cast<VPIRValue>(getStepValue())) {
-      if (auto *StepC = dyn_cast<ConstantInt>(VPV->getValue())) {
-        if (StepC->isOne())
-          NeedsMul = false;
-        else if (StepC->isMinusOne()) {
-          // This will most likely end up as a negate in simplifyRecipe, and
-          // the negate will be combined with the add to make a sub.
-          // NOTE: This is perhaps an invalid assumption that the cost of an
-          // 'add' is the same as a 'sub'.
-          NeedsMul = false;
-          NeedsAdd = true;
-        } else if (StepC->getValue().isPowerOf2()) {
-          // This will most likely end up as a shift-left in simplifyRecipe
-          NeedsMul = false;
-          NeedsShl = true;
-        }
+    if (auto *StepC = dyn_cast<VPConstantInt>(getStepValue())) {
+      if (StepC->isOne())
+        NeedsMul = false;
+      else if (StepC->getAPInt().isAllOnes()) {
+        // This will most likely end up as a negate in simplifyRecipe, and
+        // the negate will be combined with the add to make a sub.
+        // NOTE: This is perhaps an invalid assumption that the cost of an
+        // 'add' is the same as a 'sub'.
+        NeedsMul = false;
+        NeedsAdd = true;
+      } else if (StepC->getAPInt().isPowerOf2()) {
+        // This will most likely end up as a shift-left in simplifyRecipe
+        NeedsMul = false;
+        NeedsShl = true;
       }
     }