[llvm] [VPlan] Add ReductionStartVector VPInstruction. (PR #142290)

via llvm-commits llvm-commits at lists.llvm.org
Sat May 31 14:13:19 PDT 2025


llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-backend-powerpc

Author: Florian Hahn (fhahn)

<details>
<summary>Changes</summary>

Add a new VPInstruction::ReductionStartVector opcode to create the start values for wide reductions. This more accurately models the start value creation in VPlan and simplifies VPReductionPHIRecipe::execute. Down the line it also allows removing VPReductionPHIRecipe::RdxDesc.

---

Patch is 35.23 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/142290.diff


14 Files Affected:

- (modified) llvm/lib/Transforms/Vectorize/LoopVectorize.cpp (+34-3) 
- (modified) llvm/lib/Transforms/Vectorize/VPlan.h (+4-7) 
- (modified) llvm/lib/Transforms/Vectorize/VPlanAnalysis.cpp (+2) 
- (modified) llvm/lib/Transforms/Vectorize/VPlanRecipes.cpp (+28-48) 
- (modified) llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp (+16) 
- (modified) llvm/lib/Transforms/Vectorize/VPlanUnroll.cpp (+14) 
- (modified) llvm/test/Transforms/LoopVectorize/AArch64/partial-reduce-dot-product-epilogue.ll (+1-1) 
- (modified) llvm/test/Transforms/LoopVectorize/PowerPC/exit-branch-cost.ll (+1-1) 
- (modified) llvm/test/Transforms/LoopVectorize/RISCV/vectorize-force-tail-with-evl-cond-reduction.ll (+3-3) 
- (modified) llvm/test/Transforms/LoopVectorize/RISCV/vectorize-force-tail-with-evl-reduction.ll (+2-2) 
- (modified) llvm/test/Transforms/LoopVectorize/X86/cost-model.ll (+1-1) 
- (modified) llvm/test/Transforms/LoopVectorize/if-pred-stores.ll (+1-1) 
- (modified) llvm/test/Transforms/LoopVectorize/induction.ll (+5-5) 
- (modified) llvm/test/Transforms/LoopVectorize/vplan-printing-reductions.ll (+12-6) 


``````````diff
diff --git a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
index e9ace195684b3..1830ea9678e85 100644
--- a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -7501,8 +7501,11 @@ static void fixReductionScalarResumeWhenVectorizingEpilog(
       cast<VPReductionPHIRecipe>(EpiRedResult->getOperand(0));
   const RecurrenceDescriptor &RdxDesc =
       EpiRedHeaderPhi->getRecurrenceDescriptor();
-  Value *MainResumeValue =
-      EpiRedHeaderPhi->getStartValue()->getUnderlyingValue();
+  Value *MainResumeValue;
+  if (auto *VPI = dyn_cast<VPInstruction>(EpiRedHeaderPhi->getStartValue()))
+    MainResumeValue = VPI->getOperand(0)->getUnderlyingValue();
+  else
+    MainResumeValue = EpiRedHeaderPhi->getStartValue()->getUnderlyingValue();
   if (RecurrenceDescriptor::isAnyOfRecurrenceKind(
           RdxDesc.getRecurrenceKind())) {
     auto *Cmp = cast<ICmpInst>(MainResumeValue);
@@ -8552,6 +8555,7 @@ VPRecipeBase *VPRecipeBuilder::tryToCreateWidenRecipe(VPSingleDefRecipe *R,
       // If the PHI is used by a partial reduction, set the scale factor.
       unsigned ScaleFactor =
           getScalingForReduction(RdxDesc.getLoopExitInstr()).value_or(1);
+
       PhiRecipe = new VPReductionPHIRecipe(
           Phi, RdxDesc, *StartV, CM.isInLoopReduction(Phi),
           CM.useOrderedReductions(RdxDesc), ScaleFactor);
@@ -9439,7 +9443,7 @@ void LoopVectorizationPlanner::adjustRecipesForReductions(
       continue;
 
     const RecurrenceDescriptor &RdxDesc = PhiR->getRecurrenceDescriptor();
-    Type *PhiTy = PhiR->getOperand(0)->getLiveInIRValue()->getType();
+    Type *PhiTy = PhiR->getUnderlyingValue()->getType();
     // If tail is folded by masking, introduce selects between the phi
     // and the users outside the vector region of each reduction, at the
     // beginning of the dedicated latch block.
@@ -9569,6 +9573,27 @@ void LoopVectorizationPlanner::adjustRecipesForReductions(
       // start value.
       PhiR->setOperand(0, Plan->getOrAddLiveIn(RdxDesc.getSentinelValue()));
     }
+    RecurKind RK = RdxDesc.getRecurrenceKind();
+    if (PhiR->isOrdered() || PhiR->isInLoop() ||
+        (!RecurrenceDescriptor::isAnyOfRecurrenceKind(RK) &&
+         !RecurrenceDescriptor::isFindLastIVRecurrenceKind(RK) &&
+         !RecurrenceDescriptor::isMinMaxRecurrenceKind(RK))) {
+      VPBuilder PHBuilder(Plan->getVectorPreheader());
+      VPValue *Iden = Plan->getOrAddLiveIn(
+          getRecurrenceIdentity(RK, PhiTy, RdxDesc.getFastMathFlags()));
+      // If the PHI is used by a partial reduction, set the scale factor.
+      unsigned ScaleFactor =
+          RecipeBuilder.getScalingForReduction(RdxDesc.getLoopExitInstr())
+              .value_or(1);
+      Type *I32Ty = IntegerType::getInt32Ty(PhiTy->getContext());
+      auto *ScalarFactorVPV =
+          Plan->getOrAddLiveIn(ConstantInt::get(I32Ty, ScaleFactor));
+      VPValue *StartV =
+          PHBuilder.createNaryOp(VPInstruction::ReductionStartVector,
+                                 {PhiR->getStartValue(), Iden, ScalarFactorVPV},
+                                 RdxDesc.getFastMathFlags());
+      PhiR->setOperand(0, StartV);
+    }
   }
   for (VPRecipeBase *R : ToDelete)
     R->eraseFromParent();
@@ -10081,6 +10106,12 @@ preparePlanForEpilogueVectorLoop(VPlan &Plan, Loop *L,
     }
     assert(ResumeV && "Must have a resume value");
     VPValue *StartVal = Plan.getOrAddLiveIn(ResumeV);
+    if (auto *PhiR = dyn_cast<VPReductionPHIRecipe>(&R)) {
+      if (auto *VPI = dyn_cast<VPInstruction>(PhiR->getStartValue())) {
+        VPI->setOperand(0, StartVal);
+        continue;
+      }
+    }
     cast<VPHeaderPHIRecipe>(&R)->setStartValue(StartVal);
   }
 
diff --git a/llvm/lib/Transforms/Vectorize/VPlan.h b/llvm/lib/Transforms/Vectorize/VPlan.h
index 44f0b6d964a6e..c49e20518b506 100644
--- a/llvm/lib/Transforms/Vectorize/VPlan.h
+++ b/llvm/lib/Transforms/Vectorize/VPlan.h
@@ -907,6 +907,10 @@ class VPInstruction : public VPRecipeWithIRFlags,
     BranchOnCount,
     BranchOnCond,
     Broadcast,
+    /// Start vector for reductions with 3 operands: the original start value,
+    /// the identity value for the reduction and an integer indicating the
+    /// scaling factor.
+    ReductionStartVector,
     ComputeFindLastIVResult,
     ComputeReductionResult,
     // Extracts the last lane from its operand if it is a vector, or the last
@@ -2225,13 +2229,6 @@ class VPReductionPHIRecipe : public VPHeaderPHIRecipe,
 
   /// Returns true, if the phi is part of an in-loop reduction.
   bool isInLoop() const { return IsInLoop; }
-
-  /// Returns true if the recipe only uses the first lane of operand \p Op.
-  bool onlyFirstLaneUsed(const VPValue *Op) const override {
-    assert(is_contained(operands(), Op) &&
-           "Op must be an operand of the recipe");
-    return Op == getStartValue();
-  }
 };
 
 /// A recipe for vectorizing a phi-node as a sequence of mask-based select
diff --git a/llvm/lib/Transforms/Vectorize/VPlanAnalysis.cpp b/llvm/lib/Transforms/Vectorize/VPlanAnalysis.cpp
index 926490bfad7d0..7cfb07ab25e48 100644
--- a/llvm/lib/Transforms/Vectorize/VPlanAnalysis.cpp
+++ b/llvm/lib/Transforms/Vectorize/VPlanAnalysis.cpp
@@ -87,6 +87,8 @@ Type *VPTypeAnalysis::inferScalarTypeForRecipe(const VPInstruction *R) {
                inferScalarType(R->getOperand(1)) &&
            "different types inferred for different operands");
     return IntegerType::get(Ctx, 1);
+  case VPInstruction::ReductionStartVector:
+    return inferScalarType(R->getOperand(0));
   case VPInstruction::ComputeFindLastIVResult:
   case VPInstruction::ComputeReductionResult: {
     auto *PhiR = cast<VPReductionPHIRecipe>(R->getOperand(0));
diff --git a/llvm/lib/Transforms/Vectorize/VPlanRecipes.cpp b/llvm/lib/Transforms/Vectorize/VPlanRecipes.cpp
index a4831ea7c11f7..0cdd3216288ea 100644
--- a/llvm/lib/Transforms/Vectorize/VPlanRecipes.cpp
+++ b/llvm/lib/Transforms/Vectorize/VPlanRecipes.cpp
@@ -604,6 +604,20 @@ Value *VPInstruction::generate(VPTransformState &State) {
     return Builder.CreateVectorSplat(
         State.VF, State.get(getOperand(0), /*IsScalar*/ true), "broadcast");
   }
+  case VPInstruction::ReductionStartVector: {
+    if (State.VF.isScalar())
+      return State.get(getOperand(0), true);
+    IRBuilderBase::FastMathFlagGuard FMFG(Builder);
+    Builder.setFastMathFlags(getFastMathFlags());
+    // If this start vector is scaled then it should produce a vector with fewer
+    // elements than the VF.
+    ElementCount VF = State.VF.divideCoefficientBy(
+        cast<ConstantInt>(getOperand(2)->getLiveInIRValue())->getZExtValue());
+    auto *Iden = Builder.CreateVectorSplat(VF, State.get(getOperand(1), true));
+    Constant *Zero = Builder.getInt32(0);
+    return Builder.CreateInsertElement(Iden, State.get(getOperand(0), true),
+                                       Zero);
+  }
   case VPInstruction::ComputeFindLastIVResult: {
     // FIXME: The cross-recipe dependency on VPReductionPHIRecipe is temporary
     // and will be removed by breaking up the recipe further.
@@ -892,6 +906,7 @@ bool VPInstruction::opcodeMayReadOrWriteFromMemory() const {
   case VPInstruction::PtrAdd:
   case VPInstruction::WideIVStep:
   case VPInstruction::StepVector:
+  case VPInstruction::ReductionStartVector:
     return false;
   default:
     return true;
@@ -922,6 +937,7 @@ bool VPInstruction::onlyFirstLaneUsed(const VPValue *Op) const {
   case VPInstruction::CanonicalIVIncrementForPart:
   case VPInstruction::BranchOnCount:
   case VPInstruction::BranchOnCond:
+  case VPInstruction::ReductionStartVector:
     return true;
   case VPInstruction::PtrAdd:
     return Op == getOperand(0) || vputils::onlyFirstLaneUsed(this);
@@ -1023,6 +1039,9 @@ void VPInstruction::print(raw_ostream &O, const Twine &Indent,
   case VPInstruction::FirstActiveLane:
     O << "first-active-lane";
     break;
+  case VPInstruction::ReductionStartVector:
+    O << "reduction-start-vector";
+    break;
   default:
     O << Instruction::getOpcodeName(getOpcode());
   }
@@ -1613,6 +1632,7 @@ bool VPIRFlags::flagsValidForOpcode(unsigned Opcode) const {
            Opcode == Instruction::FDiv || Opcode == Instruction::FRem ||
            Opcode == Instruction::FCmp || Opcode == Instruction::Select ||
            Opcode == VPInstruction::WideIVStep ||
+           Opcode == VPInstruction::ReductionStartVector ||
            Opcode == VPInstruction::ComputeReductionResult;
   case OperationType::NonNegOp:
     return Opcode == Instruction::ZExt;
@@ -3843,17 +3863,19 @@ void VPFirstOrderRecurrencePHIRecipe::print(raw_ostream &O, const Twine &Indent,
 #endif
 
 void VPReductionPHIRecipe::execute(VPTransformState &State) {
-  // If this phi is fed by a scaled reduction then it should output a
-  // vector with fewer elements than the VF.
-  ElementCount VF = State.VF.divideCoefficientBy(VFScaleFactor);
+  // Reductions do not have to start at zero. They can start with
+  // any loop invariant values.
+  VPValue *StartVPV = getStartValue();
 
   // In order to support recurrences we need to be able to vectorize Phi nodes.
   // Phi nodes have cycles, so we need to vectorize them in two stages. This is
   // stage #1: We create a new vector PHI node with no incoming edges. We'll use
   // this value when we vectorize all of the instructions that use the PHI.
-  auto *ScalarTy = State.TypeAnalysis.inferScalarType(this);
+  BasicBlock *VectorPH =
+      State.CFG.VPBB2IRBB.at(getParent()->getCFGPredecessor(0));
   bool ScalarPHI = State.VF.isScalar() || IsInLoop;
-  Type *VecTy = ScalarPHI ? ScalarTy : VectorType::get(ScalarTy, VF);
+  Value *StartV = State.get(StartVPV, ScalarPHI);
+  Type *VecTy = StartV->getType();
 
   BasicBlock *HeaderBB = State.CFG.PrevBB;
   assert(State.CurrentParentLoop->getHeader() == HeaderBB &&
@@ -3862,49 +3884,7 @@ void VPReductionPHIRecipe::execute(VPTransformState &State) {
   Phi->insertBefore(HeaderBB->getFirstInsertionPt());
   State.set(this, Phi, IsInLoop);
 
-  BasicBlock *VectorPH =
-      State.CFG.VPBB2IRBB.at(getParent()->getCFGPredecessor(0));
-  // Create start and identity vector values for the reduction in the preheader.
-  // TODO: Introduce recipes in VPlan preheader to create initial values.
-  IRBuilderBase::InsertPointGuard IPBuilder(State.Builder);
-  State.Builder.SetInsertPoint(VectorPH->getTerminator());
-
-  // Reductions do not have to start at zero. They can start with
-  // any loop invariant values.
-  VPValue *StartVPV = getStartValue();
-  RecurKind RK = RdxDesc.getRecurrenceKind();
-  if (RecurrenceDescriptor::isMinMaxRecurrenceKind(RK) ||
-      RecurrenceDescriptor::isAnyOfRecurrenceKind(RK) ||
-      RecurrenceDescriptor::isFindLastIVRecurrenceKind(RK)) {
-    // [I|F]FindLastIV will use a sentinel value to initialize the reduction
-    // phi or the resume value from the main vector loop when vectorizing the
-    // epilogue loop. In the exit block, ComputeReductionResult will generate
-    // checks to verify if the reduction result is the sentinel value. If the
-    // result is the sentinel value, it will be corrected back to the start
-    // value.
-    // TODO: The sentinel value is not always necessary. When the start value is
-    // a constant, and smaller than the start value of the induction variable,
-    // the start value can be directly used to initialize the reduction phi.
-    Phi->addIncoming(State.get(StartVPV, ScalarPHI), VectorPH);
-    return;
-  }
-
-  Value *Iden = getRecurrenceIdentity(RK, VecTy->getScalarType(),
-                                      RdxDesc.getFastMathFlags());
-  unsigned CurrentPart = getUnrollPart(*this);
-  Value *StartV = StartVPV->getLiveInIRValue();
-  if (!ScalarPHI) {
-    if (CurrentPart == 0) {
-      Iden = State.Builder.CreateVectorSplat(VF, Iden);
-      Constant *Zero = State.Builder.getInt32(0);
-      StartV = State.Builder.CreateInsertElement(Iden, StartV, Zero);
-    } else {
-      Iden = State.Builder.CreateVectorSplat(VF, Iden);
-    }
-  }
-
-  Value *StartVal = (CurrentPart == 0) ? StartV : Iden;
-  Phi->addIncoming(StartVal, VectorPH);
+  Phi->addIncoming(StartV, VectorPH);
 }
 
 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
diff --git a/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp b/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp
index 5c8849be3d23e..354dac84a0c83 100644
--- a/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp
+++ b/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp
@@ -1151,6 +1151,22 @@ static void simplifyRecipe(VPRecipeBase &R, VPTypeAnalysis &TypeInfo) {
     R.setOperand(0, Y);
     return;
   }
+
+  auto *Plan = R.getParent()->getPlan();
+  if (!Plan->isUnrolled())
+    return;
+  /// Simplify redundant ReductionStartVector recipes after unrolling.
+  VPValue *StartV;
+  if (match(&R, m_VPInstruction<VPInstruction::ReductionStartVector>(
+                    m_VPValue(StartV), m_VPValue(), m_VPValue()))) {
+    R.getVPSingleValue()->replaceUsesWithIf(
+        StartV, [&R](const VPUser &U, unsigned Idx) {
+          auto *PhiR = dyn_cast<VPReductionPHIRecipe>(&U);
+          return PhiR && R.getVPSingleValue() == PhiR->getOperand(Idx) &&
+                 PhiR->isInLoop();
+        });
+    return;
+  }
 }
 
 void VPlanTransforms::simplifyRecipes(VPlan &Plan, Type &CanonicalIVTy) {
diff --git a/llvm/lib/Transforms/Vectorize/VPlanUnroll.cpp b/llvm/lib/Transforms/Vectorize/VPlanUnroll.cpp
index e1fb3d476c58d..3a48feb8c4ef2 100644
--- a/llvm/lib/Transforms/Vectorize/VPlanUnroll.cpp
+++ b/llvm/lib/Transforms/Vectorize/VPlanUnroll.cpp
@@ -223,6 +223,20 @@ void UnrollState::unrollHeaderPHIByUF(VPHeaderPHIRecipe *R,
       Copy->addOperand(R);
       Copy->addOperand(getConstantVPV(Part));
     } else if (RdxPhi) {
+      // If the start value is a ReductionStartVector, use the identity value (second operand) for unrolled parts. If the scaling factor is > 1, create a new ReductionStartVector with the scale factor and both operands set to the identity value.
+      if (auto *VPI = dyn_cast<VPInstruction>(RdxPhi->getStartValue())) {
+        if (cast<ConstantInt>(VPI->getOperand(2)->getLiveInIRValue())
+                ->getZExtValue() == 1)
+          Copy->setOperand(0, VPI->getOperand(1));
+        else {
+          if (Part == 1) {
+            auto *C = VPI->clone();
+            C->setOperand(0, C->getOperand(1));
+            C->insertAfter(VPI);
+            addUniformForAllParts(C);
+          }
+        }
+      }
       Copy->addOperand(getConstantVPV(Part));
     } else {
       assert(isa<VPActiveLaneMaskPHIRecipe>(R) &&
diff --git a/llvm/test/Transforms/LoopVectorize/AArch64/partial-reduce-dot-product-epilogue.ll b/llvm/test/Transforms/LoopVectorize/AArch64/partial-reduce-dot-product-epilogue.ll
index 0e5e785a94636..c3fc91c4574f1 100644
--- a/llvm/test/Transforms/LoopVectorize/AArch64/partial-reduce-dot-product-epilogue.ll
+++ b/llvm/test/Transforms/LoopVectorize/AArch64/partial-reduce-dot-product-epilogue.ll
@@ -161,8 +161,8 @@ define void @dotp_small_epilogue_vf(i64 %idx.neg, i8 %a) #1 {
 ; CHECK-NEXT:    [[BROADCAST_SPLATINSERT6:%.*]] = insertelement <4 x i8> poison, i8 [[A]], i64 0
 ; CHECK-NEXT:    [[BROADCAST_SPLAT7:%.*]] = shufflevector <4 x i8> [[BROADCAST_SPLATINSERT6]], <4 x i8> poison, <4 x i32> zeroinitializer
 ; CHECK-NEXT:    [[IND_END:%.*]] = add i64 [[IDX_NEG]], [[N_VEC5]]
-; CHECK-NEXT:    [[TMP8:%.*]] = sext <4 x i8> [[BROADCAST_SPLAT7]] to <4 x i32>
 ; CHECK-NEXT:    [[TMP10:%.*]] = insertelement <4 x i32> zeroinitializer, i32 [[BC_MERGE_RDX]], i32 0
+; CHECK-NEXT:    [[TMP8:%.*]] = sext <4 x i8> [[BROADCAST_SPLAT7]] to <4 x i32>
 ; CHECK-NEXT:    br label [[VEC_EPILOG_VECTOR_BODY:%.*]]
 ; CHECK:       vec.epilog.vector.body:
 ; CHECK-NEXT:    [[INDEX9:%.*]] = phi i64 [ [[IV]], [[VEC_EPILOG_PH]] ], [ [[INDEX_NEXT14:%.*]], [[VEC_EPILOG_VECTOR_BODY]] ]
diff --git a/llvm/test/Transforms/LoopVectorize/PowerPC/exit-branch-cost.ll b/llvm/test/Transforms/LoopVectorize/PowerPC/exit-branch-cost.ll
index f1947dec2ea23..b4987127a513d 100644
--- a/llvm/test/Transforms/LoopVectorize/PowerPC/exit-branch-cost.ll
+++ b/llvm/test/Transforms/LoopVectorize/PowerPC/exit-branch-cost.ll
@@ -153,10 +153,10 @@ define i1 @select_exit_cond(ptr %start, ptr %end, i64 %N) {
 ; CHECK-NEXT:    [[N_MOD_VF24:%.*]] = urem i64 [[TMP2]], 2
 ; CHECK-NEXT:    [[N_VEC25:%.*]] = sub i64 [[TMP2]], [[N_MOD_VF24]]
 ; CHECK-NEXT:    [[TMP56:%.*]] = getelementptr i8, ptr [[START]], i64 [[N_VEC25]]
+; CHECK-NEXT:    [[TMP57:%.*]] = insertelement <2 x i64> zeroinitializer, i64 [[BC_MERGE_RDX]], i32 0
 ; CHECK-NEXT:    [[DOTSPLATINSERT:%.*]] = insertelement <2 x i64> poison, i64 [[VEC_EPILOG_RESUME_VAL]], i64 0
 ; CHECK-NEXT:    [[DOTSPLAT:%.*]] = shufflevector <2 x i64> [[DOTSPLATINSERT]], <2 x i64> poison, <2 x i32> zeroinitializer
 ; CHECK-NEXT:    [[INDUCTION:%.*]] = add <2 x i64> [[DOTSPLAT]], <i64 0, i64 1>
-; CHECK-NEXT:    [[TMP57:%.*]] = insertelement <2 x i64> zeroinitializer, i64 [[BC_MERGE_RDX]], i32 0
 ; CHECK-NEXT:    br label %[[VEC_EPILOG_VECTOR_BODY:.*]]
 ; CHECK:       [[VEC_EPILOG_VECTOR_BODY]]:
 ; CHECK-NEXT:    [[INDEX38:%.*]] = phi i64 [ [[VEC_EPILOG_RESUME_VAL]], %[[VEC_EPILOG_PH]] ], [ [[INDEX_NEXT32:%.*]], %[[VEC_EPILOG_VECTOR_BODY]] ]
diff --git a/llvm/test/Transforms/LoopVectorize/RISCV/vectorize-force-tail-with-evl-cond-reduction.ll b/llvm/test/Transforms/LoopVectorize/RISCV/vectorize-force-tail-with-evl-cond-reduction.ll
index 01a7ea4ffcd05..3f17c95f7ca95 100644
--- a/llvm/test/Transforms/LoopVectorize/RISCV/vectorize-force-tail-with-evl-cond-reduction.ll
+++ b/llvm/test/Transforms/LoopVectorize/RISCV/vectorize-force-tail-with-evl-cond-reduction.ll
@@ -277,9 +277,9 @@ define i32 @cond_add_pred(ptr %a, i64 %n, i32 %start) {
 ; IF-EVL-OUTLOOP-NEXT:    [[TRIP_COUNT_MINUS_1:%.*]] = sub i64 [[N]], 1
 ; IF-EVL-OUTLOOP-NEXT:    [[TMP7:%.*]] = call i64 @llvm.vscale.i64()
 ; IF-EVL-OUTLOOP-NEXT:    [[TMP8:%.*]] = mul i64 [[TMP7]], 4
+; IF-EVL-OUTLOOP-NEXT:    [[TMP9:%.*]] = insertelement <vscale x 4 x i32> zeroinitializer, i32 [[START]], i32 0
 ; IF-EVL-OUTLOOP-NEXT:    [[BROADCAST_SPLATINSERT1:%.*]] = insertelement <vscale x 4 x i64> poison, i64 [[TRIP_COUNT_MINUS_1]], i64 0
 ; IF-EVL-OUTLOOP-NEXT:    [[BROADCAST_SPLAT2:%.*]] = shufflevector <vscale x 4 x i64> [[BROADCAST_SPLATINSERT1]], <vscale x 4 x i64> poison, <vscale x 4 x i32> zeroinitializer
-; IF-EVL-OUTLOOP-NEXT:    [[TMP9:%.*]] = insertelement <vscale x 4 x i32> zeroinitializer, i32 [[START]], i32 0
 ; IF-EVL-OUTLOOP-NEXT:    br label [[VECTOR_BODY:%.*]]
 ; IF-EVL-OUTLOOP:       vector.body:
 ; IF-EVL-OUTLOOP-NEXT:    [[INDEX:%.*]] = phi i64 [ 0, [[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], [[VECTOR_BODY]] ]
@@ -581,8 +581,8 @@ define i32 @step_cond_add(ptr %a, i64 %n, i32 %start) {
 ; NO-VP-OUTLOOP-NEXT:    [[N_VEC:%.*]] = sub i64 [[N]], [[N_MOD_VF]]
 ; NO-VP-OUTLOOP-NEXT:    [[TMP9:%.*]] = call i64 @llvm.vscale.i64()
 ; NO-VP-OUTLOOP-NEXT:    [[TMP10:%.*]] = mul i64 [[TMP9]], 4
-; NO-VP-OUTLOOP-NEXT:    [[TMP12:%.*]] = call <vscale x 4 x i32> @llvm.stepvector.nxv4i32()
 ; NO-VP-OUTLOOP-NEXT:    [[TMP11:%.*]] = insertelement <vscale x 4 x i32> zeroinitializer, i32 [[START]], i32 0
+; NO-VP-OUTLOOP-NEXT:    [[TMP12:%.*]] = call <vscale x 4 x i32> @llvm.stepvector.nxv4i32()
 ; NO-VP-OUTLOOP-NEXT:    [[TMP14:%.*]] = mul <vscale x 4 x i32> [[TMP12]], splat (i32 1)
 ; NO-VP-OUTLOOP-NEXT:    [[INDUCTION:%.*]] = add <vscale x 4 x i32> zeroinitializer, [[TMP14]]
 ; NO-VP-OUTLOOP-NEXT:    [[TMP16:%.*]] = trunc i64 [[TMP10]] to i32
@@ -771,8 +771,8 @@ define i32 @step_cond_add_pred(ptr %a, i64 %n, i32 %start) {
 ; NO-VP-OUTLOOP-NEXT:    [[N_VEC:%.*]] = sub i64 [[N]], [[N_MOD_VF]]
 ; NO-VP-OUTLOOP-NEXT:    [[TMP9:%.*]] = call i64 @llvm.vscale.i64()
 ; NO-VP-OUTLOOP-NEXT:    [[TMP10:%.*]] = mul i64 [[TMP9]], 4
-; NO-VP-OUTLOOP-NEXT:    [[TMP12:%.*]] = call <vscale x 4 x i32> @llvm.stepvector.nxv4i32()
 ; NO-VP-OUTLOOP-NEXT:    [[TMP11:%.*]] = insertelement <vscale x 4 x i32> zeroinitializer, i32 [[START]], i32 0
+; NO-VP-OUTLOOP-NEXT:    [[TMP12:%.*]] = call <vscale x 4 x i32> @llvm.stepvector.nxv4i32()
 ; NO-VP-OUTLOOP-NEXT:    [[TMP14:%.*]] = mul <vscale x 4 x i32> [[TMP12]], splat (i32 1)
 ; NO-VP-OUTLOOP-NEXT:    [[INDUCTION:%.*]] = add <vscale x 4 x i32> zeroinitializer, [[TMP14]]
 ; NO-VP-OUTLOOP-NEXT:    [[TMP16:%.*]] = trunc i64 [[TMP10]] to i32
diff --...
[truncated]

``````````

</details>


https://github.com/llvm/llvm-project/pull/142290


More information about the llvm-commits mailing list