OptimizationRemarkEmitter.cpp revision 360660 
1//===- OptimizationRemarkEmitter.cpp - Optimization Diagnostic --*- 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// Optimization diagnostic interfaces.  It's packaged as an analysis pass so
10// that by using this service passes become dependent on BFI as well.  BFI is
11// used to compute the "hotness" of the diagnostic message.
12//===----------------------------------------------------------------------===//
13
14#include "llvm/Analysis/OptimizationRemarkEmitter.h"
15#include "llvm/Analysis/BranchProbabilityInfo.h"
16#include "llvm/Analysis/LazyBlockFrequencyInfo.h"
17#include "llvm/Analysis/LoopInfo.h"
18#include "llvm/IR/DiagnosticInfo.h"
19#include "llvm/IR/Dominators.h"
20#include "llvm/IR/LLVMContext.h"
21
22using namespace llvm;
23
24OptimizationRemarkEmitter::OptimizationRemarkEmitter(const Function *F)
25    : F(F), BFI(nullptr) {
26  if (!F->getContext().getDiagnosticsHotnessRequested())
27    return;
28
29  // First create a dominator tree.
30  DominatorTree DT;
31  DT.recalculate(*const_cast<Function *>(F));
32
33  // Generate LoopInfo from it.
34  LoopInfo LI;
35  LI.analyze(DT);
36
37  // Then compute BranchProbabilityInfo.
38  BranchProbabilityInfo BPI;
39  BPI.calculate(*F, LI);
40
41  // Finally compute BFI.
42  OwnedBFI = llvm::make_unique<BlockFrequencyInfo>(*F, BPI, LI);
43  BFI = OwnedBFI.get();
44}
45
46bool OptimizationRemarkEmitter::invalidate(
47    Function &F, const PreservedAnalyses &PA,
48    FunctionAnalysisManager::Invalidator &Inv) {
49  // This analysis has no state and so can be trivially preserved but it needs
50  // a fresh view of BFI if it was constructed with one.
51  if (BFI && Inv.invalidate<BlockFrequencyAnalysis>(F, PA))
52    return true;
53
54  // Otherwise this analysis result remains valid.
55  return false;
56}
57
58Optional<uint64_t> OptimizationRemarkEmitter::computeHotness(const Value *V) {
59  if (!BFI)
60    return None;
61
62  return BFI->getBlockProfileCount(cast<BasicBlock>(V));
63}
64
65void OptimizationRemarkEmitter::computeHotness(
66    DiagnosticInfoIROptimization &OptDiag) {
67  const Value *V = OptDiag.getCodeRegion();
68  if (V)
69    OptDiag.setHotness(computeHotness(V));
70}
71
72void OptimizationRemarkEmitter::emit(
73    DiagnosticInfoOptimizationBase &OptDiagBase) {
74  auto &OptDiag = cast<DiagnosticInfoIROptimization>(OptDiagBase);
75  computeHotness(OptDiag);
76
77  // Only emit it if its hotness meets the threshold.
78  if (OptDiag.getHotness().getValueOr(0) <
79      F->getContext().getDiagnosticsHotnessThreshold()) {
80    return;
81  }
82
83  F->getContext().diagnose(OptDiag);
84}
85
86OptimizationRemarkEmitterWrapperPass::OptimizationRemarkEmitterWrapperPass()
87    : FunctionPass(ID) {
88  initializeOptimizationRemarkEmitterWrapperPassPass(
89      *PassRegistry::getPassRegistry());
90}
91
92bool OptimizationRemarkEmitterWrapperPass::runOnFunction(Function &Fn) {
93  BlockFrequencyInfo *BFI;
94
95  if (Fn.getContext().getDiagnosticsHotnessRequested())
96    BFI = &getAnalysis<LazyBlockFrequencyInfoPass>().getBFI();
97  else
98    BFI = nullptr;
99
100  ORE = llvm::make_unique<OptimizationRemarkEmitter>(&Fn, BFI);
101  return false;
102}
103
104void OptimizationRemarkEmitterWrapperPass::getAnalysisUsage(
105    AnalysisUsage &AU) const {
106  LazyBlockFrequencyInfoPass::getLazyBFIAnalysisUsage(AU);
107  AU.setPreservesAll();
108}
109
110AnalysisKey OptimizationRemarkEmitterAnalysis::Key;
111
112OptimizationRemarkEmitter
113OptimizationRemarkEmitterAnalysis::run(Function &F,
114                                       FunctionAnalysisManager &AM) {
115  BlockFrequencyInfo *BFI;
116
117  if (F.getContext().getDiagnosticsHotnessRequested())
118    BFI = &AM.getResult<BlockFrequencyAnalysis>(F);
119  else
120    BFI = nullptr;
121
122  return OptimizationRemarkEmitter(&F, BFI);
123}
124
125char OptimizationRemarkEmitterWrapperPass::ID = 0;
126static const char ore_name[] = "Optimization Remark Emitter";
127#define ORE_NAME "opt-remark-emitter"
128
129INITIALIZE_PASS_BEGIN(OptimizationRemarkEmitterWrapperPass, ORE_NAME, ore_name,
130                      false, true)
131INITIALIZE_PASS_DEPENDENCY(LazyBFIPass)
132INITIALIZE_PASS_END(OptimizationRemarkEmitterWrapperPass, ORE_NAME, ore_name,
133                    false, true)
134