[llvm] Fix build by marking possibly unused variable such. (PR #135689)

[via llvm-commits]

https://github.com/Sterling-Augustine created https://github.com/llvm/llvm-project/pull/135689

None

>From 367b2ba0e4ce4e56246d45eeec95d36d588a3973 Mon Sep 17 00:00:00 2001
From: Sterling Augustine <saugustine at google.com>
Date: Mon, 14 Apr 2025 15:22:39 -0700
Subject: [PATCH] Fix build by marking possibly unused variable such.

---
 llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp b/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp
index b2f495d445686..d0cb1c3ac590f 100644
--- a/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp
+++ b/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp
@@ -2414,7 +2414,7 @@ void VPlanTransforms::convertToConcreteRecipes(VPlan &Plan,
         VectorStep = Builder.createWidenCast(CastOp, VectorStep, IVTy);
       }
 
-      auto *ConstStep =
+      [[maybe_unused]] auto *ConstStep =
           ScalarStep->isLiveIn()
               ? dyn_cast<ConstantInt>(ScalarStep->getLiveInIRValue())
               : nullptr;