Revert "Reapply "[LV] Improve AnyOf reduction codegen. (#78304)""

This reverts commit c6e38b9.

Causes miscompiles, see comments on #78304.

Author: aeubanks

llvm/include/llvm/Transforms/Utils/LoopUtils.h

@@ -372,6 +372,15 @@ RecurKind getMinMaxReductionRecurKind(Intrinsic::ID RdxID);
 /// Returns the comparison predicate used when expanding a min/max reduction.
 CmpInst::Predicate getMinMaxReductionPredicate(RecurKind RK);
 
+/// See RecurrenceDescriptor::isAnyOfPattern for a description of the pattern we
+/// are trying to match. In this pattern, we are only ever selecting between two
+/// values: 1) an initial start value \p StartVal of the reduction PHI, and 2) a
+/// loop invariant value. If any of lane value in \p Left, \p Right is not equal
+/// to \p StartVal, select the loop invariant value. This is done by selecting
+/// \p Right iff \p Left is equal to \p StartVal.
+Value *createAnyOfOp(IRBuilderBase &Builder, Value *StartVal, RecurKind RK,
+                     Value *Left, Value *Right);
+
 /// Returns a Min/Max operation corresponding to MinMaxRecurrenceKind.
 /// The Builder's fast-math-flags must be set to propagate the expected values.
 Value *createMinMaxOp(IRBuilderBase &Builder, RecurKind RK, Value *Left,

llvm/lib/Transforms/Utils/LoopUtils.cpp

@@ -1034,6 +1034,15 @@ CmpInst::Predicate llvm::getMinMaxReductionPredicate(RecurKind RK) {
   }
 }
 
+Value *llvm::createAnyOfOp(IRBuilderBase &Builder, Value *StartVal,
+                           RecurKind RK, Value *Left, Value *Right) {
+  if (auto VTy = dyn_cast<VectorType>(Left->getType()))
+    StartVal = Builder.CreateVectorSplat(VTy->getElementCount(), StartVal);
+  Value *Cmp =
+      Builder.CreateCmp(CmpInst::ICMP_NE, Left, StartVal, "rdx.select.cmp");
+  return Builder.CreateSelect(Cmp, Left, Right, "rdx.select");
+}
+
 Value *llvm::createMinMaxOp(IRBuilderBase &Builder, RecurKind RK, Value *Left,
                             Value *Right) {
   Type *Ty = Left->getType();
@@ -1142,13 +1151,16 @@ Value *llvm::createAnyOfTargetReduction(IRBuilderBase &Builder, Value *Src,
     NewVal = SI->getTrueValue();
   }
 
+  // Create a splat vector with the new value and compare this to the vector
+  // we want to reduce.
+  ElementCount EC = cast<VectorType>(Src->getType())->getElementCount();
+  Value *Right = Builder.CreateVectorSplat(EC, InitVal);
+  Value *Cmp =
+      Builder.CreateCmp(CmpInst::ICMP_NE, Src, Right, "rdx.select.cmp");
+
   // If any predicate is true it means that we want to select the new value.
-  Value *AnyOf =
-      Src->getType()->isVectorTy() ? Builder.CreateOrReduce(Src) : Src;
-  // The compares in the loop may yield poison, which propagates through the
-  // bitwise ORs. Freeze it here before the condition is used.
-  AnyOf = Builder.CreateFreeze(AnyOf);
-  return Builder.CreateSelect(AnyOf, NewVal, InitVal, "rdx.select");
+  Cmp = Builder.CreateOrReduce(Cmp);
+  return Builder.CreateSelect(Cmp, NewVal, InitVal, "rdx.select");
 }
 
 Value *llvm::createSimpleTargetReduction(IRBuilderBase &Builder, Value *Src,

llvm/lib/Transforms/Vectorize/LoopVectorizationPlanner.h

@@ -68,7 +68,9 @@ class VPBuilder {
 public:
   VPBuilder() = default;
   VPBuilder(VPBasicBlock *InsertBB) { setInsertPoint(InsertBB); }
-  VPBuilder(VPRecipeBase *InsertPt) { setInsertPoint(InsertPt); }
+  VPBuilder(VPRecipeBase *InsertPt) {
+    setInsertPoint(InsertPt->getParent(), InsertPt->getIterator());
+  }
 
   /// Clear the insertion point: created instructions will not be inserted into
   /// a block.

llvm/lib/Transforms/Vectorize/LoopVectorize.cpp

@@ -3051,8 +3051,9 @@ PHINode *InnerLoopVectorizer::createInductionResumeValue(
   }
 
   // Create phi nodes to merge from the  backedge-taken check block.
-  PHINode *BCResumeVal = PHINode::Create(OrigPhi->getType(), 3, "bc.resume.val",
-                                         LoopScalarPreHeader->getFirstNonPHI());
+  PHINode *BCResumeVal =
+      PHINode::Create(OrigPhi->getType(), 3, "bc.resume.val",
+                      LoopScalarPreHeader->getTerminator()->getIterator());
   // Copy original phi DL over to the new one.
   BCResumeVal->setDebugLoc(OrigPhi->getDebugLoc());
 
@@ -7450,6 +7451,7 @@ static void createAndCollectMergePhiForReduction(
   auto *PhiR = cast<VPReductionPHIRecipe>(RedResult->getOperand(0));
   const RecurrenceDescriptor &RdxDesc = PhiR->getRecurrenceDescriptor();
 
+  TrackingVH<Value> ReductionStartValue = RdxDesc.getRecurrenceStartValue();
   Value *FinalValue =
       State.get(RedResult, VPIteration(State.UF - 1, VPLane::getFirstLane()));
   auto *ResumePhi =
@@ -7474,7 +7476,7 @@ static void createAndCollectMergePhiForReduction(
       BCBlockPhi->addIncoming(ResumePhi->getIncomingValueForBlock(Incoming),
                               Incoming);
     else
-      BCBlockPhi->addIncoming(RdxDesc.getRecurrenceStartValue(), Incoming);
+      BCBlockPhi->addIncoming(ReductionStartValue, Incoming);
   }
 
   auto *OrigPhi = cast<PHINode>(PhiR->getUnderlyingValue());
@@ -7767,10 +7769,11 @@ EpilogueVectorizerEpilogueLoop::createEpilogueVectorizedLoopSkeleton(
 
   // Now, compare the remaining count and if there aren't enough iterations to
   // execute the vectorized epilogue skip to the scalar part.
-  LoopVectorPreHeader->setName("vec.epilog.ph");
-  BasicBlock *VecEpilogueIterationCountCheck =
-      SplitBlock(LoopVectorPreHeader, LoopVectorPreHeader->begin(), DT, LI,
-                 nullptr, "vec.epilog.iter.check", true);
+  BasicBlock *VecEpilogueIterationCountCheck = LoopVectorPreHeader;
+  VecEpilogueIterationCountCheck->setName("vec.epilog.iter.check");
+  LoopVectorPreHeader =
+      SplitBlock(LoopVectorPreHeader, LoopVectorPreHeader->getTerminator(), DT,
+                 LI, nullptr, "vec.epilog.ph");
   emitMinimumVectorEpilogueIterCountCheck(LoopScalarPreHeader,
                                           VecEpilogueIterationCountCheck);
 
@@ -8893,10 +8896,6 @@ VPlanPtr LoopVectorizationPlanner::buildVPlan(VFRange &Range) {
 // A ComputeReductionResult recipe is added to the middle block, also for
 // in-loop reductions which compute their result in-loop, because generating
 // the subsequent bc.merge.rdx phi is driven by ComputeReductionResult recipes.
-//
-// Adjust AnyOf reductions; replace the reduction phi for the selected value
-// with a boolean reduction phi node to check if the condition is true in any
-// iteration. The final value is selected by the final ComputeReductionResult.
 void LoopVectorizationPlanner::adjustRecipesForReductions(
     VPBasicBlock *LatchVPBB, VPlanPtr &Plan, VPRecipeBuilder &RecipeBuilder,
     ElementCount MinVF) {
@@ -9071,41 +9070,6 @@ void LoopVectorizationPlanner::adjustRecipesForReductions(
       continue;
 
     const RecurrenceDescriptor &RdxDesc = PhiR->getRecurrenceDescriptor();
-    // Adjust AnyOf reductions; replace the reduction phi for the selected value
-    // with a boolean reduction phi node to check if the condition is true in
-    // any iteration. The final value is selected by the final
-    // ComputeReductionResult.
-    if (RecurrenceDescriptor::isAnyOfRecurrenceKind(
-            RdxDesc.getRecurrenceKind())) {
-      auto *Select = cast<VPRecipeBase>(*find_if(PhiR->users(), [](VPUser *U) {
-        return isa<VPWidenSelectRecipe>(U) ||
-               (isa<VPReplicateRecipe>(U) &&
-                cast<VPReplicateRecipe>(U)->getUnderlyingInstr()->getOpcode() ==
-                    Instruction::Select);
-      }));
-      VPValue *Cmp = Select->getOperand(0);
-      // If the compare is checking the reduction PHI node, adjust it to check
-      // the start value.
-      if (VPRecipeBase *CmpR = Cmp->getDefiningRecipe()) {
-        for (unsigned I = 0; I != CmpR->getNumOperands(); ++I)
-          if (CmpR->getOperand(I) == PhiR)
-            CmpR->setOperand(I, PhiR->getStartValue());
-      }
-      VPBuilder::InsertPointGuard Guard(Builder);
-      Builder.setInsertPoint(Select);
-
-      // If the true value of the select is the reduction phi, the new value is
-      // selected if the negated condition is true in any iteration.
-      if (Select->getOperand(1) == PhiR)
-        Cmp = Builder.createNot(Cmp);
-      VPValue *Or = Builder.createOr(PhiR, Cmp);
-      Select->getVPSingleValue()->replaceAllUsesWith(Or);
-
-      // Convert the reduction phi to operate on bools.
-      PhiR->setOperand(0, Plan->getOrAddLiveIn(ConstantInt::getFalse(
-                              OrigLoop->getHeader()->getContext())));
-    }
-
     // If tail is folded by masking, introduce selects between the phi
     // and the live-out instruction of each reduction, at the beginning of the
     // dedicated latch block.
@@ -9138,9 +9102,7 @@ void LoopVectorizationPlanner::adjustRecipesForReductions(
     // then extend the loop exit value to enable InstCombine to evaluate the
     // entire expression in the smaller type.
     Type *PhiTy = PhiR->getStartValue()->getLiveInIRValue()->getType();
-    if (MinVF.isVector() && PhiTy != RdxDesc.getRecurrenceType() &&
-        !RecurrenceDescriptor::isAnyOfRecurrenceKind(
-            RdxDesc.getRecurrenceKind())) {
+    if (MinVF.isVector() && PhiTy != RdxDesc.getRecurrenceType()) {
       assert(!PhiR->isInLoop() && "Unexpected truncated inloop reduction!");
       Type *RdxTy = RdxDesc.getRecurrenceType();
       auto *Trunc =
@@ -10181,19 +10143,9 @@ bool LoopVectorizePass::processLoop(Loop *L) {
           Value *ResumeV = nullptr;
           // TODO: Move setting of resume values to prepareToExecute.
           if (auto *ReductionPhi = dyn_cast<VPReductionPHIRecipe>(&R)) {
-            const RecurrenceDescriptor &RdxDesc =
-                ReductionPhi->getRecurrenceDescriptor();
-            RecurKind RK = RdxDesc.getRecurrenceKind();
-            ResumeV = ReductionResumeValues.find(&RdxDesc)->second;
-            if (RecurrenceDescriptor::isAnyOfRecurrenceKind(RK)) {
-              // VPReductionPHIRecipes for AnyOf reductions expect a boolean as
-              // start value; compare the final value from the main vector loop
-              // to the start value.
-              IRBuilder<> Builder(
-                  cast<Instruction>(ResumeV)->getParent()->getFirstNonPHI());
-              ResumeV = Builder.CreateICmpNE(ResumeV,
-                                             RdxDesc.getRecurrenceStartValue());
-            }
+            ResumeV = ReductionResumeValues
+                          .find(&ReductionPhi->getRecurrenceDescriptor())
+                          ->second;
           } else {
             // Create induction resume values for both widened pointer and
             // integer/fp inductions and update the start value of the induction

llvm/lib/Transforms/Vectorize/VPlanRecipes.cpp

@@ -501,8 +501,6 @@ Value *VPInstruction::generatePerPart(VPTransformState &State, unsigned Part) {
     // Reduce all of the unrolled parts into a single vector.
     Value *ReducedPartRdx = RdxParts[0];
     unsigned Op = RecurrenceDescriptor::getOpcode(RK);
-    if (RecurrenceDescriptor::isAnyOfRecurrenceKind(RK))
-      Op = Instruction::Or;
 
     if (PhiR->isOrdered()) {
       ReducedPartRdx = RdxParts[State.UF - 1];
@@ -515,16 +513,19 @@ Value *VPInstruction::generatePerPart(VPTransformState &State, unsigned Part) {
         if (Op != Instruction::ICmp && Op != Instruction::FCmp)
           ReducedPartRdx = Builder.CreateBinOp(
               (Instruction::BinaryOps)Op, RdxPart, ReducedPartRdx, "bin.rdx");
-        else
+        else if (RecurrenceDescriptor::isAnyOfRecurrenceKind(RK)) {
+          TrackingVH<Value> ReductionStartValue =
+              RdxDesc.getRecurrenceStartValue();
+          ReducedPartRdx = createAnyOfOp(Builder, ReductionStartValue, RK,
+                                         ReducedPartRdx, RdxPart);
+        } else
           ReducedPartRdx = createMinMaxOp(Builder, RK, ReducedPartRdx, RdxPart);
       }
     }
 
     // Create the reduction after the loop. Note that inloop reductions create
     // the target reduction in the loop using a Reduction recipe.
-    if ((State.VF.isVector() ||
-         RecurrenceDescriptor::isAnyOfRecurrenceKind(RK)) &&
-        !PhiR->isInLoop()) {
+    if (State.VF.isVector() && !PhiR->isInLoop()) {
       ReducedPartRdx =
           createTargetReduction(Builder, RdxDesc, ReducedPartRdx, OrigPhi);
       // If the reduction can be performed in a smaller type, we need to extend