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   ~MachineBlockFrequencyInfo() override;
42 
43   void getAnalysisUsage(AnalysisUsage &AU) const override;
44 
45   bool runOnMachineFunction(MachineFunction &F) override;
46 
47   /// calculate - compute block frequency info for the given function.
48   void calculate(const MachineFunction &F,
49                  const MachineBranchProbabilityInfo &MBPI,
50                  const MachineLoopInfo &MLI);
51 
52   void releaseMemory() override;
53 
54   /// getblockFreq - Return block frequency. Return 0 if we don't have the
55   /// information. Please note that initial frequency is equal to 1024. It means
56   /// that we should not rely on the value itself, but only on the comparison to
57   /// the other block frequencies. We do this to avoid using of floating points.
58   ///
59   BlockFrequency getBlockFreq(const MachineBasicBlock *MBB) const;
60 
61   Optional<uint64_t> getBlockProfileCount(const MachineBasicBlock *MBB) const;
62   Optional<uint64_t> getProfileCountFromFreq(uint64_t Freq) const;
63 
64   bool isIrrLoopHeader(const MachineBasicBlock *MBB);
65 
66   const MachineFunction *getFunction() const;
67   const MachineBranchProbabilityInfo *getMBPI() const;
68   void view(const Twine &Name, bool isSimple = true) const;
69 
70   // Print the block frequency Freq to OS using the current functions entry
71   // frequency to convert freq into a relative decimal form.
72   raw_ostream &printBlockFreq(raw_ostream &OS, const BlockFrequency Freq) const;
73 
74   // Convenience method that attempts to look up the frequency associated with
75   // BB and print it to OS.
76   raw_ostream &printBlockFreq(raw_ostream &OS,
77                               const MachineBasicBlock *MBB) const;
78 
79   uint64_t getEntryFreq() const;
80 };
81 
82 } // end namespace llvm
83 
84 #endif // LLVM_CODEGEN_MACHINEBLOCKFREQUENCYINFO_H
85