1 | ///===- LazyMachineBlockFrequencyInfo.cpp - Lazy Machine Block Frequency --===// |
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 | /// This is an alternative analysis pass to MachineBlockFrequencyInfo. The |
10 | /// difference is that with this pass the block frequencies are not computed |
11 | /// when the analysis pass is executed but rather when the BFI result is |
12 | /// explicitly requested by the analysis client. |
13 | /// |
14 | ///===---------------------------------------------------------------------===// |
15 | |
16 | #include "llvm/CodeGen/LazyMachineBlockFrequencyInfo.h" |
17 | #include "llvm/CodeGen/MachineBranchProbabilityInfo.h" |
18 | #include "llvm/InitializePasses.h" |
19 | |
20 | using namespace llvm; |
21 | |
22 | #define DEBUG_TYPE "lazy-machine-block-freq" |
23 | |
24 | INITIALIZE_PASS_BEGIN(LazyMachineBlockFrequencyInfoPass, DEBUG_TYPE, |
25 | "Lazy Machine Block Frequency Analysis" , true, true) |
26 | INITIALIZE_PASS_DEPENDENCY(MachineBranchProbabilityInfo) |
27 | INITIALIZE_PASS_DEPENDENCY(MachineLoopInfo) |
28 | INITIALIZE_PASS_END(LazyMachineBlockFrequencyInfoPass, DEBUG_TYPE, |
29 | "Lazy Machine Block Frequency Analysis" , true, true) |
30 | |
31 | char LazyMachineBlockFrequencyInfoPass::ID = 0; |
32 | |
33 | LazyMachineBlockFrequencyInfoPass::LazyMachineBlockFrequencyInfoPass() |
34 | : MachineFunctionPass(ID) { |
35 | initializeLazyMachineBlockFrequencyInfoPassPass( |
36 | Registry&: *PassRegistry::getPassRegistry()); |
37 | } |
38 | |
39 | void LazyMachineBlockFrequencyInfoPass::print(raw_ostream &OS, |
40 | const Module *M) const { |
41 | getBFI().print(OS, M); |
42 | } |
43 | |
44 | void LazyMachineBlockFrequencyInfoPass::getAnalysisUsage( |
45 | AnalysisUsage &AU) const { |
46 | AU.addRequired<MachineBranchProbabilityInfo>(); |
47 | AU.setPreservesAll(); |
48 | MachineFunctionPass::getAnalysisUsage(AU); |
49 | } |
50 | |
51 | void LazyMachineBlockFrequencyInfoPass::releaseMemory() { |
52 | OwnedMBFI.reset(); |
53 | OwnedMLI.reset(); |
54 | OwnedMDT.reset(); |
55 | } |
56 | |
57 | MachineBlockFrequencyInfo & |
58 | LazyMachineBlockFrequencyInfoPass::calculateIfNotAvailable() const { |
59 | auto *MBFI = getAnalysisIfAvailable<MachineBlockFrequencyInfo>(); |
60 | if (MBFI) { |
61 | LLVM_DEBUG(dbgs() << "MachineBlockFrequencyInfo is available\n" ); |
62 | return *MBFI; |
63 | } |
64 | |
65 | auto &MBPI = getAnalysis<MachineBranchProbabilityInfo>(); |
66 | auto *MLI = getAnalysisIfAvailable<MachineLoopInfo>(); |
67 | auto *MDT = getAnalysisIfAvailable<MachineDominatorTree>(); |
68 | LLVM_DEBUG(dbgs() << "Building MachineBlockFrequencyInfo on the fly\n" ); |
69 | LLVM_DEBUG(if (MLI) dbgs() << "LoopInfo is available\n" ); |
70 | |
71 | if (!MLI) { |
72 | LLVM_DEBUG(dbgs() << "Building LoopInfo on the fly\n" ); |
73 | // First create a dominator tree. |
74 | LLVM_DEBUG(if (MDT) dbgs() << "DominatorTree is available\n" ); |
75 | |
76 | if (!MDT) { |
77 | LLVM_DEBUG(dbgs() << "Building DominatorTree on the fly\n" ); |
78 | OwnedMDT = std::make_unique<MachineDominatorTree>(); |
79 | OwnedMDT->getBase().recalculate(Func&: *MF); |
80 | MDT = OwnedMDT.get(); |
81 | } |
82 | |
83 | // Generate LoopInfo from it. |
84 | OwnedMLI = std::make_unique<MachineLoopInfo>(); |
85 | OwnedMLI->getBase().analyze(DomTree: MDT->getBase()); |
86 | MLI = OwnedMLI.get(); |
87 | } |
88 | |
89 | OwnedMBFI = std::make_unique<MachineBlockFrequencyInfo>(); |
90 | OwnedMBFI->calculate(F: *MF, MBPI, MLI: *MLI); |
91 | return *OwnedMBFI; |
92 | } |
93 | |
94 | bool LazyMachineBlockFrequencyInfoPass::runOnMachineFunction( |
95 | MachineFunction &F) { |
96 | MF = &F; |
97 | return false; |
98 | } |
99 | |