1 //===-- SpeculateAnalyses.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 // \file
9 /// Contains the Analyses and Result Interpretation to select likely functions
10 /// to Speculatively compile before they are called. [Purely Experimentation]
11 //===----------------------------------------------------------------------===//
12 
13 #ifndef LLVM_EXECUTIONENGINE_ORC_SPECULATEANALYSES_H
14 #define LLVM_EXECUTIONENGINE_ORC_SPECULATEANALYSES_H
15 
16 #include "llvm/Analysis/BranchProbabilityInfo.h"
17 #include "llvm/ExecutionEngine/Orc/Core.h"
18 #include "llvm/ExecutionEngine/Orc/Speculation.h"
19 
20 #include <vector>
21 
22 namespace llvm {
23 
24 namespace orc {
25 
26 // Provides common code.
27 class SpeculateQuery {
28 protected:
29   void findCalles(const BasicBlock *, DenseSet<StringRef> &);
30   bool isStraightLine(const Function &F);
31 
32 public:
33   using ResultTy = Optional<DenseMap<StringRef, DenseSet<StringRef>>>;
34 };
35 
36 // Direct calls in high frequency basic blocks are extracted.
37 class BlockFreqQuery : public SpeculateQuery {
38   size_t numBBToGet(size_t);
39 
40 public:
41   // Find likely next executables based on IR Block Frequency
42   ResultTy operator()(Function &F);
43 };
44 
45 // This Query generates a sequence of basic blocks which follows the order of
46 // execution.
47 // A handful of BB with higher block frequencies are taken, then path to entry
48 // and end BB are discovered by traversing up & down the CFG.
49 class SequenceBBQuery : public SpeculateQuery {
50   struct WalkDirection {
51     bool Upward = true, Downward = true;
52     // the block associated contain a call
53     bool CallerBlock = false;
54   };
55 
56 public:
57   using VisitedBlocksInfoTy = DenseMap<const BasicBlock *, WalkDirection>;
58   using BlockListTy = SmallVector<const BasicBlock *, 8>;
59   using BackEdgesInfoTy =
60       SmallVector<std::pair<const BasicBlock *, const BasicBlock *>, 8>;
61   using BlockFreqInfoTy =
62       SmallVector<std::pair<const BasicBlock *, uint64_t>, 8>;
63 
64 private:
65   std::size_t getHottestBlocks(std::size_t TotalBlocks);
66   BlockListTy rearrangeBB(const Function &, const BlockListTy &);
67   BlockListTy queryCFG(Function &, const BlockListTy &);
68   void traverseToEntryBlock(const BasicBlock *, const BlockListTy &,
69                             const BackEdgesInfoTy &,
70                             const BranchProbabilityInfo *,
71                             VisitedBlocksInfoTy &);
72   void traverseToExitBlock(const BasicBlock *, const BlockListTy &,
73                            const BackEdgesInfoTy &,
74                            const BranchProbabilityInfo *,
75                            VisitedBlocksInfoTy &);
76 
77 public:
78   ResultTy operator()(Function &F);
79 };
80 
81 } // namespace orc
82 } // namespace llvm
83 
84 #endif // LLVM_EXECUTIONENGINE_ORC_SPECULATEANALYSES_H
85