[llvm] [LV] Strip createStepForVF (NFC) (PR #185668)

[Ramkumar Ramachandra via llvm-commits]

https://github.com/artagnon updated https://github.com/llvm/llvm-project/pull/185668

>From 28067380a9c2086b3fb2898ee7fa8059cd256c67 Mon Sep 17 00:00:00 2001
From: Ramkumar Ramachandra <artagnon at tenstorrent.com>
Date: Tue, 10 Mar 2026 15:11:46 +0000
Subject: [PATCH] [LV] Strip createStepForVF (NFC)

The mul -> shl simplification is already done in VPlan.
---
 llvm/lib/Transforms/Vectorize/LoopVectorize.cpp | 14 --------------
 llvm/lib/Transforms/Vectorize/VPlanHelpers.h    |  4 ----
 llvm/lib/Transforms/Vectorize/VPlanRecipes.cpp  |  5 ++---
 3 files changed, 2 insertions(+), 21 deletions(-)

diff --git a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
index 32ef10e530187..5ddb47a22e84f 100644
--- a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -786,20 +786,6 @@ createLVAnalysis(const char *PassName, StringRef RemarkName, Loop *TheLoop,
 
 namespace llvm {
 
-/// Return a value for Step multiplied by VF.
-Value *createStepForVF(IRBuilderBase &B, Type *Ty, ElementCount VF,
-                       int64_t Step) {
-  assert(Ty->isIntegerTy() && "Expected an integer step");
-  ElementCount VFxStep = VF.multiplyCoefficientBy(Step);
-  assert(isPowerOf2_64(VF.getKnownMinValue()) && "must pass power-of-2 VF");
-  if (VF.isScalable() && isPowerOf2_64(Step)) {
-    return B.CreateShl(
-        B.CreateVScale(Ty),
-        ConstantInt::get(Ty, Log2_64(VFxStep.getKnownMinValue())), "", true);
-  }
-  return B.CreateElementCount(Ty, VFxStep);
-}
-
 /// Return the runtime value for VF.
 Value *getRuntimeVF(IRBuilderBase &B, Type *Ty, ElementCount VF) {
   return B.CreateElementCount(Ty, VF);
diff --git a/llvm/lib/Transforms/Vectorize/VPlanHelpers.h b/llvm/lib/Transforms/Vectorize/VPlanHelpers.h
index 0d4a842c700f6..5de7ab36a6d75 100644
--- a/llvm/lib/Transforms/Vectorize/VPlanHelpers.h
+++ b/llvm/lib/Transforms/Vectorize/VPlanHelpers.h
@@ -46,10 +46,6 @@ class Value;
 /// vectors it is an expression determined at runtime.
 Value *getRuntimeVF(IRBuilderBase &B, Type *Ty, ElementCount VF);
 
-/// Return a value for Step multiplied by VF.
-Value *createStepForVF(IRBuilderBase &B, Type *Ty, ElementCount VF,
-                       int64_t Step);
-
 /// Compute the transformed value of Index at offset StartValue using step
 /// StepValue.
 /// For integer induction, returns StartValue + Index * StepValue.
diff --git a/llvm/lib/Transforms/Vectorize/VPlanRecipes.cpp b/llvm/lib/Transforms/Vectorize/VPlanRecipes.cpp
index 7eefd77045050..05a47273b799a 100644
--- a/llvm/lib/Transforms/Vectorize/VPlanRecipes.cpp
+++ b/llvm/lib/Transforms/Vectorize/VPlanRecipes.cpp
@@ -2606,8 +2606,6 @@ void VPScalarIVStepsRecipe::execute(VPTransformState &State) {
                                /*ImplicitTrunc=*/true)
             : ConstantFP::get(BaseIVTy, Lane);
     Value *StartIdx = Builder.CreateBinOp(AddOp, StartIdx0, LaneValue);
-    // The step returned by `createStepForVF` is a runtime-evaluated value
-    // when VF is scalable. Otherwise, it should be folded into a Constant.
     assert((State.VF.isScalable() || isa<Constant>(StartIdx)) &&
            "Expected StartIdx to be folded to a constant when VF is not "
            "scalable");
@@ -4571,7 +4569,8 @@ void VPWidenCanonicalIVRecipe::execute(VPTransformState &State) {
   Value *VStart = VF.isScalar()
                       ? CanonicalIV
                       : Builder.CreateVectorSplat(VF, CanonicalIV, "broadcast");
-  Value *VStep = createStepForVF(Builder, STy, VF, getUnrollPart(*this));
+  Value *VStep = Builder.CreateElementCount(
+      STy, VF.multiplyCoefficientBy(getUnrollPart(*this)));
   if (VF.isVector()) {
     VStep = Builder.CreateVectorSplat(VF, VStep);
     VStep =