[SLP] Vectorize reversed stores.

[ABataev]

Summary

Patch adds support for vectorization of the reversed stores. The value
operands are vectorized and then shuffled in the reverse order before
store.

[ABataev]

Updated to latest version

[ABataev]

Rebase

[RKSimon]

lib/Transforms/Vectorize/SLPVectorizer.cpp

2665 ↗

(On Diff #218721)

You don't need the getZExtValue()

Diff->getAPInt() == (VL.size() - 1) * Size

[ABataev]

Fix comment + rebase

[RKSimon]

couple of minors

llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp

2669–2678

or if we need to swizzle them.

2721

Add brackets to make what you're incrementing more obvious?

[ABataev]

Address comments.

[RKSimon]

LGTM

[RKSimon]

BTW - we can probably replace "reversed" with "jumbled"

[ABataev]

In D43339#1727261, @RKSimon wrote:

BTW - we can probably replace "reversed" with "jumbled"

Ok, will rename it.

[ABataev]

Reopen since it was reverted

[ABataev]

It was committed back.

llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp

case Instruction::GetElementPtr: {
           Operands.push_back(cast<Instruction>(V)->getOperand(i));
 
         buildTree_rec(Operands, Depth + 1, {TE, i});
       }
       return;
     }
     case Instruction::Store: {
       // Check if the stores are consecutive or if we need to swizzle them.
-      for (unsigned i = 0, e = VL.size() - 1; i < e; ++i)
-        if (!isConsecutiveAccess(VL[i], VL[i + 1], *DL, *SE)) {
+      llvm::Type *ScalarTy = cast<StoreInst>(VL0)->getValueOperand()->getType();
+      // Make sure all stores in the bundle are simple - we can't vectorize
+      // atomic or volatile stores.
+      SmallVector<Value *, 4> PointerOps(VL.size());
+      ValueList Operands(VL.size());
+      auto POIter = PointerOps.begin();
+      auto OIter = Operands.begin();
+      for (Value *V : VL) {
+        auto *SI = cast<StoreInst>(V);
+        if (!SI->isSimple()) {
           BS.cancelScheduling(VL, VL0);
           newTreeEntry(VL, None /*not vectorized*/, S, UserTreeIdx,
                        ReuseShuffleIndicies);
-          LLVM_DEBUG(dbgs() << "SLP: Non-consecutive store.\n");
+          LLVM_DEBUG(dbgs() << "SLP: Gathering non-simple stores.\n");
           return;
         }
+        *POIter = SI->getPointerOperand();
+        *OIter = SI->getValueOperand();
+        ++POIter;
+        ++OIter;
+      }
 
-      TreeEntry *TE = newTreeEntry(VL, Bundle /*vectorized*/, S, UserTreeIdx,
-                                   ReuseShuffleIndicies);
+      OrdersType CurrentOrder;
+      // Check the order of pointer operands.
+      if (llvm::sortPtrAccesses(PointerOps, *DL, *SE, CurrentOrder)) {
+        Value *Ptr0;
+        Value *PtrN;
+        if (CurrentOrder.empty()) {
+          Ptr0 = PointerOps.front();
+          PtrN = PointerOps.back();
+        } else {
+          Ptr0 = PointerOps[CurrentOrder.front()];
+          PtrN = PointerOps[CurrentOrder.back()];
+        }
+        const SCEV *Scev0 = SE->getSCEV(Ptr0);
+        const SCEV *ScevN = SE->getSCEV(PtrN);
+        const auto *Diff =
+            dyn_cast<SCEVConstant>(SE->getMinusSCEV(ScevN, Scev0));
+        uint64_t Size = DL->getTypeAllocSize(ScalarTy);
+        // Check that the sorted pointer operands are consecutive.
+        if (Diff && Diff->getAPInt() == (VL.size() - 1) * Size) {
+          if (CurrentOrder.empty()) {
+            // Original stores are consecutive and does not require reordering.
+            ++NumOpsWantToKeepOriginalOrder;
+            TreeEntry *TE = newTreeEntry(VL, Bundle /*vectorized*/, S,
+                                         UserTreeIdx, ReuseShuffleIndicies);
+            TE->setOperandsInOrder();
+            buildTree_rec(Operands, Depth + 1, {TE, 0});
             LLVM_DEBUG(dbgs() << "SLP: added a vector of stores.\n");
-
-      ValueList Operands;
-      for (Value *V : VL)
-        Operands.push_back(cast<Instruction>(V)->getOperand(0));
+          } else {
+            // Need to reorder.
+            auto I = NumOpsWantToKeepOrder.try_emplace(CurrentOrder).first;
+            ++(I->getSecond());
+            TreeEntry *TE =
+                newTreeEntry(VL, Bundle /*vectorized*/, S, UserTreeIdx,
+                             ReuseShuffleIndicies, I->getFirst());
             TE->setOperandsInOrder();
             buildTree_rec(Operands, Depth + 1, {TE, 0});
+            LLVM_DEBUG(dbgs() << "SLP: added a vector of jumbled stores.\n");
+          }
+          return;
+        }
+      }
+
+      BS.cancelScheduling(VL, VL0);
+      newTreeEntry(VL, None /*not vectorized*/, S, UserTreeIdx,
+                   ReuseShuffleIndicies);
+      LLVM_DEBUG(dbgs() << "SLP: Non-consecutive store.\n");
       return;
     }
     case Instruction::Call: {
       // Check if the calls are all to the same vectorizable intrinsic.
       CallInst *CI = cast<CallInst>(VL0);
       // Check if this is an Intrinsic call or something that can be
       // represented by an intrinsic call
       Intrinsic::ID ID = getVectorIntrinsicIDForCall(CI, TLI);
case Instruction::Load: {
         // TODO: Merge this shuffle with the ReuseShuffleCost.
         VecLdCost += TTI->getShuffleCost(
             TargetTransformInfo::SK_PermuteSingleSrc, VecTy);
       }
       return ReuseShuffleCost + VecLdCost - ScalarLdCost;
     }
     case Instruction::Store: {
       // We know that we can merge the stores. Calculate the cost.
-      MaybeAlign alignment(cast<StoreInst>(VL0)->getAlignment());
+      bool IsReorder = !E->ReorderIndices.empty();
+      auto *SI =
+          cast<StoreInst>(IsReorder ? VL[E->ReorderIndices.front()] : VL0);
+      MaybeAlign Alignment(SI->getAlignment());
       int ScalarEltCost =
-          TTI->getMemoryOpCost(Instruction::Store, ScalarTy, alignment, 0, VL0);
+          TTI->getMemoryOpCost(Instruction::Store, ScalarTy, Alignment, 0, VL0);
       if (NeedToShuffleReuses) {
         ReuseShuffleCost -= (ReuseShuffleNumbers - VL.size()) * ScalarEltCost;
       }
       int ScalarStCost = VecTy->getNumElements() * ScalarEltCost;
-      int VecStCost =
-          TTI->getMemoryOpCost(Instruction::Store, VecTy, alignment, 0, VL0);
+      int VecStCost = TTI->getMemoryOpCost(Instruction::Store,
+                                           VecTy, Alignment, 0, VL0);
+      if (IsReorder) {
+        // TODO: Merge this shuffle with the ReuseShuffleCost.
+        VecStCost += TTI->getShuffleCost(
+            TargetTransformInfo::SK_PermuteSingleSrc, VecTy);
+      }
       return ReuseShuffleCost + VecStCost - ScalarStCost;
     }
     case Instruction::Call: {
       CallInst *CI = cast<CallInst>(VL0);
       Intrinsic::ID ID = getVectorIntrinsicIDForCall(CI, TLI);
 
       // Calculate the cost of the scalar and vector calls.
       SmallVector<Type *, 4> ScalarTys;
case Instruction::Load: {
         V = Builder.CreateShuffleVector(V, UndefValue::get(VecTy),
                                         E->ReuseShuffleIndices, "shuffle");
       }
       E->VectorizedValue = V;
       ++NumVectorInstructions;
       return V;
     }
     case Instruction::Store: {
-      StoreInst *SI = cast<StoreInst>(VL0);
+      bool IsReorder = !E->ReorderIndices.empty();
+      auto *SI = cast<StoreInst>(
+          IsReorder ? E->Scalars[E->ReorderIndices.front()] : VL0);
       unsigned Alignment = SI->getAlignment();
       unsigned AS = SI->getPointerAddressSpace();
 
       setInsertPointAfterBundle(E);
 
       Value *VecValue = vectorizeTree(E->getOperand(0));
+      if (IsReorder) {
+        OrdersType Mask;
+        inversePermutation(E->ReorderIndices, Mask);
+        VecValue = Builder.CreateShuffleVector(
+            VecValue, UndefValue::get(VecValue->getType()), E->ReorderIndices,
+            "reorder_shuffle");
+      }
       Value *ScalarPtr = SI->getPointerOperand();
       Value *VecPtr = Builder.CreateBitCast(ScalarPtr, VecTy->getPointerTo(AS));
       StoreInst *ST = Builder.CreateStore(VecValue, VecPtr);
 
       // The pointer operand uses an in-tree scalar, so add the new BitCast to
       // ExternalUses to make sure that an extract will be generated in the
       // future.
       if (getTreeEntry(ScalarPtr))
bool SLPVectorizerPass::vectorizeStoreChain(ArrayRef<Value *> Chain, BoUpSLP &R,
 
   if (!isPowerOf2_32(Sz) || !isPowerOf2_32(VF) || VF < 2 || VF < MinVF)
     return false;
 
   LLVM_DEBUG(dbgs() << "SLP: Analyzing " << VF << " stores at offset " << Idx
                     << "\n");
 
   R.buildTree(Chain);
+  Optional<ArrayRef<unsigned>> Order = R.bestOrder();
+  if (Order) {
+    // TODO: reorder tree nodes without tree rebuilding.
+    SmallVector<Value *, 4> ReorderedOps(Chain.rbegin(), Chain.rend());
+    llvm::transform(*Order, ReorderedOps.begin(),
+                    [Chain](const unsigned Idx) { return Chain[Idx]; });
+    R.buildTree(ReorderedOps);
+  }
   if (R.isTreeTinyAndNotFullyVectorizable())
     return false;
 
   R.computeMinimumValueSizes();
 
   int Cost = R.getTreeCost();
 
   LLVM_DEBUG(dbgs() << "SLP: Found cost=" << Cost << " for VF=" << VF << "\n");

llvm/test/Transforms/SLPVectorizer/X86/store-jumbled.ll

 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
 ; RUN: opt < %s -S -mtriple=x86_64-unknown -mattr=+avx -slp-vectorizer | FileCheck %s
 
 
 
 define i32 @jumbled-load(i32* noalias nocapture %in, i32* noalias nocapture %inn, i32* noalias nocapture %out) {
 ; CHECK-LABEL: @jumbled-load(
 ; CHECK-NEXT:    [[IN_ADDR:%.*]] = getelementptr inbounds i32, i32* [[IN:%.*]], i64 0
 ; CHECK-NEXT:    [[GEP_1:%.*]] = getelementptr inbounds i32, i32* [[IN_ADDR]], i64 1
 ; CHECK-NEXT:    [[GEP_2:%.*]] = getelementptr inbounds i32, i32* [[IN_ADDR]], i64 2
 ; CHECK-NEXT:    [[GEP_3:%.*]] = getelementptr inbounds i32, i32* [[IN_ADDR]], i64 3
 ; CHECK-NEXT:    [[TMP1:%.*]] = bitcast i32* [[IN_ADDR]] to <4 x i32>*
 ; CHECK-NEXT:    [[TMP2:%.*]] = load <4 x i32>, <4 x i32>* [[TMP1]], align 4
-; CHECK-NEXT:    [[REORDER_SHUFFLE:%.*]] = shufflevector <4 x i32> [[TMP2]], <4 x i32> undef, <4 x i32> <i32 1, i32 3, i32 0, i32 2>
 ; CHECK-NEXT:    [[INN_ADDR:%.*]] = getelementptr inbounds i32, i32* [[INN:%.*]], i64 0
 ; CHECK-NEXT:    [[GEP_4:%.*]] = getelementptr inbounds i32, i32* [[INN_ADDR]], i64 1
 ; CHECK-NEXT:    [[GEP_5:%.*]] = getelementptr inbounds i32, i32* [[INN_ADDR]], i64 2
 ; CHECK-NEXT:    [[GEP_6:%.*]] = getelementptr inbounds i32, i32* [[INN_ADDR]], i64 3
 ; CHECK-NEXT:    [[TMP3:%.*]] = bitcast i32* [[INN_ADDR]] to <4 x i32>*
 ; CHECK-NEXT:    [[TMP4:%.*]] = load <4 x i32>, <4 x i32>* [[TMP3]], align 4
-; CHECK-NEXT:    [[REORDER_SHUFFLE1:%.*]] = shufflevector <4 x i32> [[TMP4]], <4 x i32> undef, <4 x i32> <i32 1, i32 3, i32 0, i32 2>
-; CHECK-NEXT:    [[TMP5:%.*]] = mul <4 x i32> [[REORDER_SHUFFLE]], [[REORDER_SHUFFLE1]]
+; CHECK-NEXT:    [[TMP5:%.*]] = mul <4 x i32> [[TMP2]], [[TMP4]]
 ; CHECK-NEXT:    [[GEP_7:%.*]] = getelementptr inbounds i32, i32* [[OUT:%.*]], i64 0
 ; CHECK-NEXT:    [[GEP_8:%.*]] = getelementptr inbounds i32, i32* [[OUT]], i64 1
 ; CHECK-NEXT:    [[GEP_9:%.*]] = getelementptr inbounds i32, i32* [[OUT]], i64 2
 ; CHECK-NEXT:    [[GEP_10:%.*]] = getelementptr inbounds i32, i32* [[OUT]], i64 3
+; CHECK-NEXT:    [[REORDER_SHUFFLE:%.*]] = shufflevector <4 x i32> [[TMP5]], <4 x i32> undef, <4 x i32> <i32 1, i32 3, i32 0, i32 2>
 ; CHECK-NEXT:    [[TMP6:%.*]] = bitcast i32* [[GEP_7]] to <4 x i32>*
-; CHECK-NEXT:    store <4 x i32> [[TMP5]], <4 x i32>* [[TMP6]], align 4
+; CHECK-NEXT:    store <4 x i32> [[REORDER_SHUFFLE]], <4 x i32>* [[TMP6]], align 4
 ; CHECK-NEXT:    ret i32 undef
 ;
   %in.addr = getelementptr inbounds i32, i32* %in, i64 0
   %load.1 = load i32, i32* %in.addr, align 4
   %gep.1 = getelementptr inbounds i32, i32* %in.addr, i64 1
   %load.2 = load i32, i32* %gep.1, align 4
   %gep.2 = getelementptr inbounds i32, i32* %in.addr, i64 2
   %load.3 = load i32, i32* %gep.2, align 4

llvm/test/Transforms/SLPVectorizer/X86/stores_vectorize.ll

 ; CHECK-NEXT:    [[ARRAYIDX4:%.*]] = getelementptr inbounds i64, i64* [[P3]], i64 9
 ; CHECK-NEXT:    [[ARRAYIDX6:%.*]] = getelementptr inbounds i64, i64* [[P3]], i64 6
 ; CHECK-NEXT:    [[ARRAYIDX7:%.*]] = getelementptr inbounds i64, i64* [[P3]], i64 2
 ; CHECK-NEXT:    [[ARRAYIDX8:%.*]] = getelementptr inbounds i64, i64* [[P3]], i64 10
 ; CHECK-NEXT:    [[ARRAYIDX10:%.*]] = getelementptr inbounds i64, i64* [[P3]], i64 5
 ; CHECK-NEXT:    [[ARRAYIDX11:%.*]] = getelementptr inbounds i64, i64* [[P3]], i64 3
 ; CHECK-NEXT:    [[TMP0:%.*]] = bitcast i64* [[P3]] to <4 x i64>*
 ; CHECK-NEXT:    [[TMP1:%.*]] = load <4 x i64>, <4 x i64>* [[TMP0]], align 8
-; CHECK-NEXT:    [[REORDER_SHUFFLE:%.*]] = shufflevector <4 x i64> [[TMP1]], <4 x i64> undef, <4 x i32> <i32 3, i32 2, i32 1, i32 0>
 ; CHECK-NEXT:    [[ARRAYIDX12:%.*]] = getelementptr inbounds i64, i64* [[P3]], i64 11
 ; CHECK-NEXT:    [[TMP2:%.*]] = bitcast i64* [[ARRAYIDX1]] to <4 x i64>*
 ; CHECK-NEXT:    [[TMP3:%.*]] = load <4 x i64>, <4 x i64>* [[TMP2]], align 8
-; CHECK-NEXT:    [[REORDER_SHUFFLE1:%.*]] = shufflevector <4 x i64> [[TMP3]], <4 x i64> undef, <4 x i32> <i32 3, i32 2, i32 1, i32 0>
-; CHECK-NEXT:    [[TMP4:%.*]] = shl <4 x i64> [[REORDER_SHUFFLE]], [[REORDER_SHUFFLE1]]
+; CHECK-NEXT:    [[TMP4:%.*]] = shl <4 x i64> [[TMP1]], [[TMP3]]
 ; CHECK-NEXT:    [[ARRAYIDX14:%.*]] = getelementptr inbounds i64, i64* [[P3]], i64 4
-; CHECK-NEXT:    [[TMP5:%.*]] = bitcast i64* [[ARRAYIDX14]] to <4 x i64>*
-; CHECK-NEXT:    store <4 x i64> [[TMP4]], <4 x i64>* [[TMP5]], align 8
+; CHECK-NEXT:    [[TMP5:%.*]] = shufflevector <4 x i64> [[TMP4]], <4 x i64> undef, <4 x i32> <i32 3, i32 2, i32 1, i32 0>
+; CHECK-NEXT:    [[TMP6:%.*]] = bitcast i64* [[ARRAYIDX14]] to <4 x i64>*
+; CHECK-NEXT:    store <4 x i64> [[TMP5]], <4 x i64>* [[TMP6]], align 8
 ; CHECK-NEXT:    ret void
 ;
 entry:
   %0 = load i64, i64* %p3, align 8
   %arrayidx1 = getelementptr inbounds i64, i64* %p3, i64 8
   %1 = load i64, i64* %arrayidx1, align 8
   %shl = shl i64 %0, %1
   %arrayidx2 = getelementptr inbounds i64, i64* %p3, i64 7