summaryrefslogtreecommitdiff
path: root/lib/CodeGen/AsmPrinter/DwarfFile.cpp
blob: 737ee54f94b53c7b890a139f5ddc433b082bf10b (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
//===-- llvm/CodeGen/DwarfFile.cpp - Dwarf Debug Framework ----------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

#include "DwarfFile.h"

#include "DwarfDebug.h"
#include "DwarfUnit.h"
#include "llvm/MC/MCStreamer.h"
#include "llvm/Support/LEB128.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/Target/TargetLoweringObjectFile.h"

namespace llvm {
DwarfFile::DwarfFile(AsmPrinter *AP, StringRef Pref, BumpPtrAllocator &DA)
    : Asm(AP), StrPool(DA, *Asm, Pref) {}

DwarfFile::~DwarfFile() {}

// Define a unique number for the abbreviation.
//
void DwarfFile::assignAbbrevNumber(DIEAbbrev &Abbrev) {
  // Check the set for priors.
  DIEAbbrev *InSet = AbbreviationsSet.GetOrInsertNode(&Abbrev);

  // If it's newly added.
  if (InSet == &Abbrev) {
    // Add to abbreviation list.
    Abbreviations.push_back(&Abbrev);

    // Assign the vector position + 1 as its number.
    Abbrev.setNumber(Abbreviations.size());
  } else {
    // Assign existing abbreviation number.
    Abbrev.setNumber(InSet->getNumber());
  }
}

void DwarfFile::addUnit(std::unique_ptr<DwarfUnit> U) {
  CUs.push_back(std::move(U));
}

// Emit the various dwarf units to the unit section USection with
// the abbreviations going into ASection.
void DwarfFile::emitUnits(DwarfDebug *DD, const MCSymbol *ASectionSym) {
  for (const auto &TheU : CUs) {
    DIE &Die = TheU->getUnitDie();
    const MCSection *USection = TheU->getSection();
    Asm->OutStreamer.SwitchSection(USection);

    // Emit the compile units header.
    Asm->OutStreamer.EmitLabel(TheU->getLabelBegin());

    // Emit size of content not including length itself
    Asm->OutStreamer.AddComment("Length of Unit");
    Asm->EmitInt32(TheU->getHeaderSize() + Die.getSize());

    TheU->emitHeader(ASectionSym);

    DD->emitDIE(Die);
    Asm->OutStreamer.EmitLabel(TheU->getLabelEnd());
  }
}
// Compute the size and offset for each DIE.
void DwarfFile::computeSizeAndOffsets() {
  // Offset from the first CU in the debug info section is 0 initially.
  unsigned SecOffset = 0;

  // Iterate over each compile unit and set the size and offsets for each
  // DIE within each compile unit. All offsets are CU relative.
  for (const auto &TheU : CUs) {
    TheU->setDebugInfoOffset(SecOffset);

    // CU-relative offset is reset to 0 here.
    unsigned Offset = sizeof(int32_t) +      // Length of Unit Info
                      TheU->getHeaderSize(); // Unit-specific headers

    // EndOffset here is CU-relative, after laying out
    // all of the CU DIE.
    unsigned EndOffset = computeSizeAndOffset(TheU->getUnitDie(), Offset);
    SecOffset += EndOffset;
  }
}
// Compute the size and offset of a DIE. The offset is relative to start of the
// CU. It returns the offset after laying out the DIE.
unsigned DwarfFile::computeSizeAndOffset(DIE &Die, unsigned Offset) {
  // Record the abbreviation.
  assignAbbrevNumber(Die.getAbbrev());

  // Get the abbreviation for this DIE.
  const DIEAbbrev &Abbrev = Die.getAbbrev();

  // Set DIE offset
  Die.setOffset(Offset);

  // Start the size with the size of abbreviation code.
  Offset += getULEB128Size(Die.getAbbrevNumber());

  const SmallVectorImpl<DIEValue *> &Values = Die.getValues();
  const SmallVectorImpl<DIEAbbrevData> &AbbrevData = Abbrev.getData();

  // Size the DIE attribute values.
  for (unsigned i = 0, N = Values.size(); i < N; ++i)
    // Size attribute value.
    Offset += Values[i]->SizeOf(Asm, AbbrevData[i].getForm());

  // Get the children.
  const auto &Children = Die.getChildren();

  // Size the DIE children if any.
  if (!Children.empty()) {
    assert(Abbrev.hasChildren() && "Children flag not set");

    for (auto &Child : Children)
      Offset = computeSizeAndOffset(*Child, Offset);

    // End of children marker.
    Offset += sizeof(int8_t);
  }

  Die.setSize(Offset - Die.getOffset());
  return Offset;
}
void DwarfFile::emitAbbrevs(const MCSection *Section) {
  // Check to see if it is worth the effort.
  if (!Abbreviations.empty()) {
    // Start the debug abbrev section.
    Asm->OutStreamer.SwitchSection(Section);

    // For each abbrevation.
    for (const DIEAbbrev *Abbrev : Abbreviations) {
      // Emit the abbrevations code (base 1 index.)
      Asm->EmitULEB128(Abbrev->getNumber(), "Abbreviation Code");

      // Emit the abbreviations data.
      Abbrev->Emit(Asm);
    }

    // Mark end of abbreviations.
    Asm->EmitULEB128(0, "EOM(3)");
  }
}

// Emit strings into a string section.
void DwarfFile::emitStrings(const MCSection *StrSection,
                            const MCSection *OffsetSection,
                            const MCSymbol *StrSecSym) {
  StrPool.emit(*Asm, StrSection, OffsetSection, StrSecSym);
}
}