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/CodeGen/MachineFunctionPass.h" |
17 | #include "llvm/Support/BlockFrequency.h" |
18 | #include <cstdint> |
19 | #include <memory> |
20 | #include <optional> |
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 | /// For example, to get the frequency of a block relative to the entry block, |
62 | /// divide the integral value returned by this function (the |
63 | /// BlockFrequency::getFrequency() value) by getEntryFreq(). |
64 | BlockFrequency getBlockFreq(const MachineBasicBlock *MBB) const; |
65 | |
66 | /// Compute the frequency of the block, relative to the entry block. |
67 | /// This API assumes getEntryFreq() is non-zero. |
68 | double getBlockFreqRelativeToEntryBlock(const MachineBasicBlock *MBB) const { |
69 | assert(getEntryFreq() != BlockFrequency(0) && |
70 | "getEntryFreq() should not return 0 here!" ); |
71 | return static_cast<double>(getBlockFreq(MBB).getFrequency()) / |
72 | static_cast<double>(getEntryFreq().getFrequency()); |
73 | } |
74 | |
75 | std::optional<uint64_t> |
76 | getBlockProfileCount(const MachineBasicBlock *MBB) const; |
77 | std::optional<uint64_t> getProfileCountFromFreq(BlockFrequency Freq) const; |
78 | |
79 | bool (const MachineBasicBlock *MBB) const; |
80 | |
81 | /// incrementally calculate block frequencies when we split edges, to avoid |
82 | /// full CFG traversal. |
83 | void onEdgeSplit(const MachineBasicBlock &NewPredecessor, |
84 | const MachineBasicBlock &NewSuccessor, |
85 | const MachineBranchProbabilityInfo &MBPI); |
86 | |
87 | const MachineFunction *getFunction() const; |
88 | const MachineBranchProbabilityInfo *getMBPI() const; |
89 | |
90 | /// Pop up a ghostview window with the current block frequency propagation |
91 | /// rendered using dot. |
92 | void view(const Twine &Name, bool isSimple = true) const; |
93 | |
94 | /// Divide a block's BlockFrequency::getFrequency() value by this value to |
95 | /// obtain the entry block - relative frequency of said block. |
96 | BlockFrequency getEntryFreq() const; |
97 | }; |
98 | |
99 | /// Print the block frequency @p Freq relative to the current functions entry |
100 | /// frequency. Returns a Printable object that can be piped via `<<` to a |
101 | /// `raw_ostream`. |
102 | Printable printBlockFreq(const MachineBlockFrequencyInfo &MBFI, |
103 | BlockFrequency Freq); |
104 | |
105 | /// Convenience function equivalent to calling |
106 | /// `printBlockFreq(MBFI, MBFI.getBlockFreq(&MBB))`. |
107 | Printable printBlockFreq(const MachineBlockFrequencyInfo &MBFI, |
108 | const MachineBasicBlock &MBB); |
109 | |
110 | } // end namespace llvm |
111 | |
112 | #endif // LLVM_CODEGEN_MACHINEBLOCKFREQUENCYINFO_H |
113 | |