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/CodeGen/MachineCycleAnalysis.h"
19#include "llvm/InitializePasses.h"
20
21using namespace llvm;
22
23#define DEBUG_TYPE "lazy-machine-block-freq"
24
25INITIALIZE_PASS_BEGIN(LazyMachineBlockFrequencyInfoPass, DEBUG_TYPE,
26 "Lazy Machine Block Frequency Analysis", true, true)
27INITIALIZE_PASS_DEPENDENCY(MachineBranchProbabilityInfoWrapperPass)
28INITIALIZE_PASS_DEPENDENCY(MachineCycleInfoWrapperPass)
29INITIALIZE_PASS_END(LazyMachineBlockFrequencyInfoPass, DEBUG_TYPE,
30 "Lazy Machine Block Frequency Analysis", true, true)
31
32char LazyMachineBlockFrequencyInfoPass::ID = 0;
33
34LazyMachineBlockFrequencyInfoPass::LazyMachineBlockFrequencyInfoPass()
35 : MachineFunctionPass(ID) {}
36
37void LazyMachineBlockFrequencyInfoPass::getAnalysisUsage(
38 AnalysisUsage &AU) const {
39 AU.addRequired<MachineBranchProbabilityInfoWrapperPass>();
40 AU.setPreservesAll();
41 MachineFunctionPass::getAnalysisUsage(AU);
42}
43
44void LazyMachineBlockFrequencyInfoPass::releaseMemory() {
45 OwnedMBFI.reset();
46 OwnedMCI.reset();
47}
48
49MachineBlockFrequencyInfo &
50LazyMachineBlockFrequencyInfoPass::calculateIfNotAvailable() const {
51 auto *MBFIWrapper =
52 getAnalysisIfAvailable<MachineBlockFrequencyInfoWrapperPass>();
53 if (MBFIWrapper) {
54 LLVM_DEBUG(dbgs() << "MachineBlockFrequencyInfo is available\n");
55 return MBFIWrapper->getMBFI();
56 }
57
58 auto &MBPI = getAnalysis<MachineBranchProbabilityInfoWrapperPass>().getMBPI();
59 auto *MCIWrapper = getAnalysisIfAvailable<MachineCycleInfoWrapperPass>();
60 auto *MCI = MCIWrapper ? &MCIWrapper->getCycleInfo() : nullptr;
61 LLVM_DEBUG(dbgs() << "Building MachineBlockFrequencyInfo on the fly\n");
62 LLVM_DEBUG(if (MCI) dbgs() << "CycleInfo is available\n");
63
64 if (!MCI) {
65 LLVM_DEBUG(dbgs() << "Building CycleInfo on the fly\n");
66 OwnedMCI = std::make_unique<MachineCycleInfo>();
67 OwnedMCI->compute(F&: *MF);
68 MCI = OwnedMCI.get();
69 }
70
71 OwnedMBFI = std::make_unique<MachineBlockFrequencyInfo>();
72 OwnedMBFI->calculate(F: *MF, MBPI, MCI: *MCI);
73 return *OwnedMBFI;
74}
75
76bool LazyMachineBlockFrequencyInfoPass::runOnMachineFunction(
77 MachineFunction &F) {
78 MF = &F;
79 return false;
80}
81