1 //===- MachineBlockFrequencyInfo.h - MBB 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_CODEGEN_MACHINEBLOCKFREQUENCYINFO_H
14 #define LLVM_CODEGEN_MACHINEBLOCKFREQUENCYINFO_H
15 
16 #include "llvm/ADT/Optional.h"
17 #include "llvm/CodeGen/MachineFunctionPass.h"
18 #include "llvm/Support/BlockFrequency.h"
19 #include <cstdint>
20 #include <memory>
21 
22 namespace llvm {
23 
24 template <class BlockT> class BlockFrequencyInfoImpl;
25 class MachineBasicBlock;
26 class MachineBranchProbabilityInfo;
27 class MachineFunction;
28 class MachineLoopInfo;
29 class raw_ostream;
30 
31 /// MachineBlockFrequencyInfo pass uses BlockFrequencyInfoImpl implementation
32 /// to estimate machine basic block frequencies.
33 class MachineBlockFrequencyInfo : public MachineFunctionPass {
34   using ImplType = BlockFrequencyInfoImpl<MachineBasicBlock>;
35   std::unique_ptr<ImplType> MBFI;
36 
37 public:
38   static char ID;
39 
40   MachineBlockFrequencyInfo();
41   explicit MachineBlockFrequencyInfo(MachineFunction &F,
42                                      MachineBranchProbabilityInfo &MBPI,
43                                      MachineLoopInfo &MLI);
44   ~MachineBlockFrequencyInfo() override;
45 
46   void getAnalysisUsage(AnalysisUsage &AU) const override;
47 
48   bool runOnMachineFunction(MachineFunction &F) override;
49 
50   /// calculate - compute block frequency info for the given function.
51   void calculate(const MachineFunction &F,
52                  const MachineBranchProbabilityInfo &MBPI,
53                  const MachineLoopInfo &MLI);
54 
55   void releaseMemory() override;
56 
57   /// getblockFreq - Return block frequency. Return 0 if we don't have the
58   /// information. Please note that initial frequency is equal to 1024. It means
59   /// that we should not rely on the value itself, but only on the comparison to
60   /// the other block frequencies. We do this to avoid using of floating points.
61   ///
62   BlockFrequency getBlockFreq(const MachineBasicBlock *MBB) const;
63 
64   Optional<uint64_t> getBlockProfileCount(const MachineBasicBlock *MBB) const;
65   Optional<uint64_t> getProfileCountFromFreq(uint64_t Freq) const;
66 
67   bool isIrrLoopHeader(const MachineBasicBlock *MBB);
68 
69   void setBlockFreq(const MachineBasicBlock *MBB, uint64_t Freq);
70 
71   const MachineFunction *getFunction() const;
72   const MachineBranchProbabilityInfo *getMBPI() const;
73   void view(const Twine &Name, bool isSimple = true) const;
74 
75   // Print the block frequency Freq to OS using the current functions entry
76   // frequency to convert freq into a relative decimal form.
77   raw_ostream &printBlockFreq(raw_ostream &OS, const BlockFrequency Freq) const;
78 
79   // Convenience method that attempts to look up the frequency associated with
80   // BB and print it to OS.
81   raw_ostream &printBlockFreq(raw_ostream &OS,
82                               const MachineBasicBlock *MBB) const;
83 
84   uint64_t getEntryFreq() const;
85 };
86 
87 } // end namespace llvm
88 
89 #endif // LLVM_CODEGEN_MACHINEBLOCKFREQUENCYINFO_H
90