1 ///===- LazyMachineBlockFrequencyInfo.cpp - Lazy Machine Block Frequency --===//
2 ///
3 /// The LLVM Compiler Infrastructure
4 ///
5 /// This file is distributed under the University of Illinois Open Source
6 /// License. See LICENSE.TXT for details.
7 ///
8 ///===---------------------------------------------------------------------===//
9 /// \file
10 /// This is an alternative analysis pass to MachineBlockFrequencyInfo. The
11 /// difference is that with this pass the block frequencies are not computed
12 /// when the analysis pass is executed but rather when the BFI result is
13 /// explicitly requested by the analysis client.
14 ///
15 ///===---------------------------------------------------------------------===//
16
17 #include "llvm/CodeGen/LazyMachineBlockFrequencyInfo.h"
18
19 using namespace llvm;
20
21 #define DEBUG_TYPE "lazy-machine-block-freq"
22
23 INITIALIZE_PASS_BEGIN(LazyMachineBlockFrequencyInfoPass, DEBUG_TYPE,
24 "Lazy Machine Block Frequency Analysis", true, true)
25 INITIALIZE_PASS_DEPENDENCY(MachineBranchProbabilityInfo)
26 INITIALIZE_PASS_DEPENDENCY(MachineLoopInfo)
27 INITIALIZE_PASS_END(LazyMachineBlockFrequencyInfoPass, DEBUG_TYPE,
28 "Lazy Machine Block Frequency Analysis", true, true)
29
30 char LazyMachineBlockFrequencyInfoPass::ID = 0;
31
LazyMachineBlockFrequencyInfoPass()32 LazyMachineBlockFrequencyInfoPass::LazyMachineBlockFrequencyInfoPass()
33 : MachineFunctionPass(ID) {
34 initializeLazyMachineBlockFrequencyInfoPassPass(
35 *PassRegistry::getPassRegistry());
36 }
37
print(raw_ostream & OS,const Module * M) const38 void LazyMachineBlockFrequencyInfoPass::print(raw_ostream &OS,
39 const Module *M) const {
40 getBFI().print(OS, M);
41 }
42
getAnalysisUsage(AnalysisUsage & AU) const43 void LazyMachineBlockFrequencyInfoPass::getAnalysisUsage(
44 AnalysisUsage &AU) const {
45 AU.addRequired<MachineBranchProbabilityInfo>();
46 AU.setPreservesAll();
47 MachineFunctionPass::getAnalysisUsage(AU);
48 }
49
releaseMemory()50 void LazyMachineBlockFrequencyInfoPass::releaseMemory() {
51 OwnedMBFI.reset();
52 OwnedMLI.reset();
53 OwnedMDT.reset();
54 }
55
56 MachineBlockFrequencyInfo &
calculateIfNotAvailable() const57 LazyMachineBlockFrequencyInfoPass::calculateIfNotAvailable() const {
58 auto *MBFI = getAnalysisIfAvailable<MachineBlockFrequencyInfo>();
59 if (MBFI) {
60 LLVM_DEBUG(dbgs() << "MachineBlockFrequencyInfo is available\n");
61 return *MBFI;
62 }
63
64 auto &MBPI = getAnalysis<MachineBranchProbabilityInfo>();
65 auto *MLI = getAnalysisIfAvailable<MachineLoopInfo>();
66 auto *MDT = getAnalysisIfAvailable<MachineDominatorTree>();
67 LLVM_DEBUG(dbgs() << "Building MachineBlockFrequencyInfo on the fly\n");
68 LLVM_DEBUG(if (MLI) dbgs() << "LoopInfo is available\n");
69
70 if (!MLI) {
71 LLVM_DEBUG(dbgs() << "Building LoopInfo on the fly\n");
72 // First create a dominator tree.
73 LLVM_DEBUG(if (MDT) dbgs() << "DominatorTree is available\n");
74
75 if (!MDT) {
76 LLVM_DEBUG(dbgs() << "Building DominatorTree on the fly\n");
77 OwnedMDT = make_unique<MachineDominatorTree>();
78 OwnedMDT->getBase().recalculate(*MF);
79 MDT = OwnedMDT.get();
80 }
81
82 // Generate LoopInfo from it.
83 OwnedMLI = make_unique<MachineLoopInfo>();
84 OwnedMLI->getBase().analyze(MDT->getBase());
85 MLI = OwnedMLI.get();
86 }
87
88 OwnedMBFI = make_unique<MachineBlockFrequencyInfo>();
89 OwnedMBFI->calculate(*MF, MBPI, *MLI);
90 return *OwnedMBFI.get();
91 }
92
runOnMachineFunction(MachineFunction & F)93 bool LazyMachineBlockFrequencyInfoPass::runOnMachineFunction(
94 MachineFunction &F) {
95 MF = &F;
96 return false;
97 }
98