1//===- BlockFrequencyInfo.h - Block Frequency Analysis ----------*- 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//
9// Loops should be simplified before this analysis.
10//
11//===----------------------------------------------------------------------===//
12
13#ifndef LLVM_ANALYSIS_BLOCKFREQUENCYINFO_H
14#define LLVM_ANALYSIS_BLOCKFREQUENCYINFO_H
15
16#include "llvm/ADT/Optional.h"
17#include "llvm/IR/PassManager.h"
18#include "llvm/Pass.h"
19#include "llvm/Support/BlockFrequency.h"
20#include <cstdint>
21#include <memory>
22
23namespace llvm {
24
25class BasicBlock;
26class BranchProbabilityInfo;
27class Function;
28class LoopInfo;
29class Module;
30class raw_ostream;
31template <class BlockT> class BlockFrequencyInfoImpl;
32
33enum PGOViewCountsType { PGOVCT_None, PGOVCT_Graph, PGOVCT_Text };
34
35/// BlockFrequencyInfo pass uses BlockFrequencyInfoImpl implementation to
36/// estimate IR basic block frequencies.
37class BlockFrequencyInfo {
38 using ImplType = BlockFrequencyInfoImpl<BasicBlock>;
39
40 std::unique_ptr<ImplType> BFI;
41
42public:
43 BlockFrequencyInfo();
44 BlockFrequencyInfo(const Function &F, const BranchProbabilityInfo &BPI,
45 const LoopInfo &LI);
46 BlockFrequencyInfo(const BlockFrequencyInfo &) = delete;
47 BlockFrequencyInfo &operator=(const BlockFrequencyInfo &) = delete;
48 BlockFrequencyInfo(BlockFrequencyInfo &&Arg);
49 BlockFrequencyInfo &operator=(BlockFrequencyInfo &&RHS);
50 ~BlockFrequencyInfo();
51
52 /// Handle invalidation explicitly.
53 bool invalidate(Function &F, const PreservedAnalyses &PA,
54 FunctionAnalysisManager::Invalidator &);
55
56 const Function *getFunction() const;
57 const BranchProbabilityInfo *getBPI() const;
58 void view(StringRef = "BlockFrequencyDAGs") const;
59
60 /// getblockFreq - Return block frequency. Return 0 if we don't have the
61 /// information. Please note that initial frequency is equal to ENTRY_FREQ. It
62 /// means that we should not rely on the value itself, but only on the
63 /// comparison to the other block frequencies. We do this to avoid using of
64 /// floating points.
65 BlockFrequency getBlockFreq(const BasicBlock *BB) const;
66
67 /// Returns the estimated profile count of \p BB.
68 /// This computes the relative block frequency of \p BB and multiplies it by
69 /// the enclosing function's count (if available) and returns the value.
70 Optional<uint64_t> getBlockProfileCount(const BasicBlock *BB,
71 bool AllowSynthetic = false) const;
72
73 /// Returns the estimated profile count of \p Freq.
74 /// This uses the frequency \p Freq and multiplies it by
75 /// the enclosing function's count (if available) and returns the value.
76 Optional<uint64_t> getProfileCountFromFreq(uint64_t Freq) const;
77
78 /// Returns true if \p BB is an irreducible loop header
79 /// block. Otherwise false.
80 bool isIrrLoopHeader(const BasicBlock *BB);
81
82 // Set the frequency of the given basic block.
83 void setBlockFreq(const BasicBlock *BB, uint64_t Freq);
84
85 /// Set the frequency of \p ReferenceBB to \p Freq and scale the frequencies
86 /// of the blocks in \p BlocksToScale such that their frequencies relative
87 /// to \p ReferenceBB remain unchanged.
88 void setBlockFreqAndScale(const BasicBlock *ReferenceBB, uint64_t Freq,
89 SmallPtrSetImpl<BasicBlock *> &BlocksToScale);
90
91 /// calculate - compute block frequency info for the given function.
92 void calculate(const Function &F, const BranchProbabilityInfo &BPI,
93 const LoopInfo &LI);
94
95 // Print the block frequency Freq to OS using the current functions entry
96 // frequency to convert freq into a relative decimal form.
97 raw_ostream &printBlockFreq(raw_ostream &OS, const BlockFrequency Freq) const;
98
99 // Convenience method that attempts to look up the frequency associated with
100 // BB and print it to OS.
101 raw_ostream &printBlockFreq(raw_ostream &OS, const BasicBlock *BB) const;
102
103 uint64_t getEntryFreq() const;
104 void releaseMemory();
105 void print(raw_ostream &OS) const;
106
107 // Compare to the other BFI and verify they match.
108 void verifyMatch(BlockFrequencyInfo &Other) const;
109};
110
111/// Analysis pass which computes \c BlockFrequencyInfo.
112class BlockFrequencyAnalysis
113 : public AnalysisInfoMixin<BlockFrequencyAnalysis> {
114 friend AnalysisInfoMixin<BlockFrequencyAnalysis>;
115
116 static AnalysisKey Key;
117
118public:
119 /// Provide the result type for this analysis pass.
120 using Result = BlockFrequencyInfo;
121
122 /// Run the analysis pass over a function and produce BFI.
123 Result run(Function &F, FunctionAnalysisManager &AM);
124};
125
126/// Printer pass for the \c BlockFrequencyInfo results.
127class BlockFrequencyPrinterPass
128 : public PassInfoMixin<BlockFrequencyPrinterPass> {
129 raw_ostream &OS;
130
131public:
132 explicit BlockFrequencyPrinterPass(raw_ostream &OS) : OS(OS) {}
133
134 PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM);
135};
136
137/// Legacy analysis pass which computes \c BlockFrequencyInfo.
138class BlockFrequencyInfoWrapperPass : public FunctionPass {
139 BlockFrequencyInfo BFI;
140
141public:
142 static char ID;
143
144 BlockFrequencyInfoWrapperPass();
145 ~BlockFrequencyInfoWrapperPass() override;
146
147 BlockFrequencyInfo &getBFI() { return BFI; }
148 const BlockFrequencyInfo &getBFI() const { return BFI; }
149
150 void getAnalysisUsage(AnalysisUsage &AU) const override;
151
152 bool runOnFunction(Function &F) override;
153 void releaseMemory() override;
154 void print(raw_ostream &OS, const Module *M) const override;
155};
156
157} // end namespace llvm
158
159#endif // LLVM_ANALYSIS_BLOCKFREQUENCYINFO_H
160