1//===- LazyBlockFrequencyInfo.cpp - Lazy Block Frequency Analysis ---------===//
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// This is an alternative analysis pass to BlockFrequencyInfoWrapperPass. The
10// difference is that with this pass the block frequencies are not computed when
11// the analysis pass is executed but rather when the BFI result is explicitly
12// requested by the analysis client.
13//
14//===----------------------------------------------------------------------===//
15
16#include "llvm/Analysis/LazyBlockFrequencyInfo.h"
17#include "llvm/Analysis/LazyBranchProbabilityInfo.h"
18#include "llvm/Analysis/LoopInfo.h"
19#include "llvm/IR/Dominators.h"
20#include "llvm/InitializePasses.h"
21
22using namespace llvm;
23
24#define DEBUG_TYPE "lazy-block-freq"
25
26INITIALIZE_PASS_BEGIN(LazyBlockFrequencyInfoPass, DEBUG_TYPE,
27 "Lazy Block Frequency Analysis", true, true)
28INITIALIZE_PASS_DEPENDENCY(LazyBPIPass)
29INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass)
30INITIALIZE_PASS_END(LazyBlockFrequencyInfoPass, DEBUG_TYPE,
31 "Lazy Block Frequency Analysis", true, true)
32
33char LazyBlockFrequencyInfoPass::ID = 0;
34
35LazyBlockFrequencyInfoPass::LazyBlockFrequencyInfoPass() : FunctionPass(ID) {
36 initializeLazyBlockFrequencyInfoPassPass(Registry&: *PassRegistry::getPassRegistry());
37}
38
39void LazyBlockFrequencyInfoPass::print(raw_ostream &OS, const Module *) const {
40 LBFI.getCalculated().print(OS);
41}
42
43void LazyBlockFrequencyInfoPass::getAnalysisUsage(AnalysisUsage &AU) const {
44 LazyBranchProbabilityInfoPass::getLazyBPIAnalysisUsage(AU);
45 // We require DT so it's available when LI is available. The LI updating code
46 // asserts that DT is also present so if we don't make sure that we have DT
47 // here, that assert will trigger.
48 AU.addRequiredTransitive<DominatorTreeWrapperPass>();
49 AU.addRequiredTransitive<LoopInfoWrapperPass>();
50 AU.setPreservesAll();
51}
52
53void LazyBlockFrequencyInfoPass::releaseMemory() { LBFI.releaseMemory(); }
54
55bool LazyBlockFrequencyInfoPass::runOnFunction(Function &F) {
56 auto &BPIPass = getAnalysis<LazyBranchProbabilityInfoPass>();
57 LoopInfo &LI = getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
58 LBFI.setAnalysis(F: &F, BPIPass: &BPIPass, LI: &LI);
59 return false;
60}
61
62void LazyBlockFrequencyInfoPass::getLazyBFIAnalysisUsage(AnalysisUsage &AU) {
63 LazyBranchProbabilityInfoPass::getLazyBPIAnalysisUsage(AU);
64 AU.addRequiredTransitive<LazyBlockFrequencyInfoPass>();
65 AU.addRequiredTransitive<LoopInfoWrapperPass>();
66}
67
68void llvm::initializeLazyBFIPassPass(PassRegistry &Registry) {
69 initializeLazyBPIPassPass(Registry);
70 INITIALIZE_PASS_DEPENDENCY(LazyBlockFrequencyInfoPass);
71 INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass);
72}
73

source code of llvm/lib/Analysis/LazyBlockFrequencyInfo.cpp