1 //===- SLPVectorizer.h ------------------------------------------*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 // This pass implements the Bottom Up SLP vectorizer. It detects consecutive
9 // stores that can be put together into vector-stores. Next, it attempts to
10 // construct vectorizable tree using the use-def chains. If a profitable tree
11 // was found, the SLP vectorizer performs vectorization on the tree.
12 //
13 // The pass is inspired by the work described in the paper:
14 //  "Loop-Aware SLP in GCC" by Ira Rosen, Dorit Nuzman, Ayal Zaks.
15 //
16 //===----------------------------------------------------------------------===//
17 
18 #ifndef LLVM_TRANSFORMS_VECTORIZE_SLPVECTORIZER_H
19 #define LLVM_TRANSFORMS_VECTORIZE_SLPVECTORIZER_H
20 
21 #include "llvm/ADT/ArrayRef.h"
22 #include "llvm/ADT/MapVector.h"
23 #include "llvm/ADT/SetVector.h"
24 #include "llvm/ADT/SmallVector.h"
25 #include "llvm/IR/PassManager.h"
26 
27 namespace llvm {
28 
29 class AAResults;
30 class AssumptionCache;
31 class BasicBlock;
32 class DemandedBits;
33 class DominatorTree;
34 class Function;
35 class GetElementPtrInst;
36 class InsertElementInst;
37 class InsertValueInst;
38 class Instruction;
39 class LoopInfo;
40 class OptimizationRemarkEmitter;
41 class PHINode;
42 class ScalarEvolution;
43 class StoreInst;
44 class TargetLibraryInfo;
45 class TargetTransformInfo;
46 class Value;
47 class WeakTrackingVH;
48 
49 /// A private "module" namespace for types and utilities used by this pass.
50 /// These are implementation details and should not be used by clients.
51 namespace slpvectorizer {
52 
53 class BoUpSLP;
54 
55 } // end namespace slpvectorizer
56 
57 struct SLPVectorizerPass : public PassInfoMixin<SLPVectorizerPass> {
58   using StoreList = SmallVector<StoreInst *, 8>;
59   using StoreListMap = MapVector<Value *, StoreList>;
60   using GEPList = SmallVector<GetElementPtrInst *, 8>;
61   using GEPListMap = MapVector<Value *, GEPList>;
62   using InstSetVector = SmallSetVector<Instruction *, 8>;
63 
64   ScalarEvolution *SE = nullptr;
65   TargetTransformInfo *TTI = nullptr;
66   TargetLibraryInfo *TLI = nullptr;
67   AAResults *AA = nullptr;
68   LoopInfo *LI = nullptr;
69   DominatorTree *DT = nullptr;
70   AssumptionCache *AC = nullptr;
71   DemandedBits *DB = nullptr;
72   const DataLayout *DL = nullptr;
73 
74 public:
75   PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM);
76 
77   // Glue for old PM.
78   bool runImpl(Function &F, ScalarEvolution *SE_, TargetTransformInfo *TTI_,
79                TargetLibraryInfo *TLI_, AAResults *AA_, LoopInfo *LI_,
80                DominatorTree *DT_, AssumptionCache *AC_, DemandedBits *DB_,
81                OptimizationRemarkEmitter *ORE_);
82 
83 private:
84   /// Collect store and getelementptr instructions and organize them
85   /// according to the underlying object of their pointer operands. We sort the
86   /// instructions by their underlying objects to reduce the cost of
87   /// consecutive access queries.
88   ///
89   /// TODO: We can further reduce this cost if we flush the chain creation
90   ///       every time we run into a memory barrier.
91   void collectSeedInstructions(BasicBlock *BB);
92 
93   /// Try to vectorize a list of operands.
94   /// \param MaxVFOnly Vectorize only using maximal allowed register size.
95   /// \returns true if a value was vectorized.
96   bool tryToVectorizeList(ArrayRef<Value *> VL, slpvectorizer::BoUpSLP &R,
97                           bool MaxVFOnly = false);
98 
99   /// Try to vectorize a chain that may start at the operands of \p I.
100   bool tryToVectorize(Instruction *I, slpvectorizer::BoUpSLP &R);
101 
102   /// Try to vectorize chains that may start at the operands of
103   /// instructions in \p Insts.
104   bool tryToVectorize(ArrayRef<WeakTrackingVH> Insts,
105                       slpvectorizer::BoUpSLP &R);
106 
107   /// Vectorize the store instructions collected in Stores.
108   bool vectorizeStoreChains(slpvectorizer::BoUpSLP &R);
109 
110   /// Vectorize the index computations of the getelementptr instructions
111   /// collected in GEPs.
112   bool vectorizeGEPIndices(BasicBlock *BB, slpvectorizer::BoUpSLP &R);
113 
114   /// Try to find horizontal reduction or otherwise, collect instructions
115   /// for postponed vectorization attempts.
116   /// \a P if not null designates phi node the reduction is fed into
117   /// (with reduction operators \a Root or one of its operands, in a basic block
118   /// \a BB).
119   /// \returns true if a horizontal reduction was matched and reduced.
120   /// \returns false if \a V is null or not an instruction,
121   /// or a horizontal reduction was not matched or not possible.
122   bool vectorizeHorReduction(PHINode *P, Instruction *Root, BasicBlock *BB,
123                              slpvectorizer::BoUpSLP &R,
124                              TargetTransformInfo *TTI,
125                              SmallVectorImpl<WeakTrackingVH> &PostponedInsts);
126 
127   /// Make an attempt to vectorize reduction and then try to vectorize
128   /// postponed binary operations.
129   /// \returns true on any successfull vectorization.
130   bool vectorizeRootInstruction(PHINode *P, Instruction *Root, BasicBlock *BB,
131                                 slpvectorizer::BoUpSLP &R,
132                                 TargetTransformInfo *TTI);
133 
134   /// Try to vectorize trees that start at insertvalue instructions.
135   bool vectorizeInsertValueInst(InsertValueInst *IVI, BasicBlock *BB,
136                                 slpvectorizer::BoUpSLP &R);
137 
138   /// Try to vectorize trees that start at insertelement instructions.
139   bool vectorizeInsertElementInst(InsertElementInst *IEI, BasicBlock *BB,
140                                   slpvectorizer::BoUpSLP &R);
141 
142   /// Tries to vectorize \p CmpInts. \Returns true on success.
143   template <typename ItT>
144   bool vectorizeCmpInsts(iterator_range<ItT> CmpInsts, BasicBlock *BB,
145                          slpvectorizer::BoUpSLP &R);
146 
147   /// Tries to vectorize constructs started from InsertValueInst or
148   /// InsertElementInst instructions.
149   bool vectorizeInserts(InstSetVector &Instructions, BasicBlock *BB,
150                         slpvectorizer::BoUpSLP &R);
151 
152   /// Scan the basic block and look for patterns that are likely to start
153   /// a vectorization chain.
154   bool vectorizeChainsInBlock(BasicBlock *BB, slpvectorizer::BoUpSLP &R);
155 
156   bool vectorizeStoreChain(ArrayRef<Value *> Chain, slpvectorizer::BoUpSLP &R,
157                            unsigned Idx, unsigned MinVF);
158 
159   bool vectorizeStores(ArrayRef<StoreInst *> Stores, slpvectorizer::BoUpSLP &R);
160 
161   /// The store instructions in a basic block organized by base pointer.
162   StoreListMap Stores;
163 
164   /// The getelementptr instructions in a basic block organized by base pointer.
165   GEPListMap GEPs;
166 };
167 
168 } // end namespace llvm
169 
170 #endif // LLVM_TRANSFORMS_VECTORIZE_SLPVECTORIZER_H
171