1 //===-- llvm/CodeGen/DwarfFile.cpp - Dwarf Debug Framework ----------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 #include "DwarfFile.h"
12 #include "DwarfDebug.h"
13 #include "DwarfUnit.h"
14 #include "llvm/MC/MCStreamer.h"
15 #include "llvm/Support/LEB128.h"
16 #include "llvm/IR/DataLayout.h"
17 #include "llvm/ADT/STLExtras.h"
18 #include "llvm/Target/TargetLoweringObjectFile.h"
21 DwarfFile::DwarfFile(AsmPrinter *AP, DwarfDebug &DD, StringRef Pref,
23 : Asm(AP), DD(DD), StrPool(DA, *Asm, Pref) {
27 DwarfFile::~DwarfFile() {}
29 // Define a unique number for the abbreviation.
31 void DwarfFile::assignAbbrevNumber(DIEAbbrev &Abbrev) {
32 // Check the set for priors.
33 DIEAbbrev *InSet = AbbreviationsSet.GetOrInsertNode(&Abbrev);
35 // If it's newly added.
36 if (InSet == &Abbrev) {
37 // Add to abbreviation list.
38 Abbreviations.push_back(&Abbrev);
40 // Assign the vector position + 1 as its number.
41 Abbrev.setNumber(Abbreviations.size());
43 // Assign existing abbreviation number.
44 Abbrev.setNumber(InSet->getNumber());
48 void DwarfFile::addUnit(std::unique_ptr<DwarfUnit> U) {
49 CUs.push_back(std::move(U));
52 // Emit the various dwarf units to the unit section USection with
53 // the abbreviations going into ASection.
54 void DwarfFile::emitUnits(const MCSymbol *ASectionSym) {
55 for (const auto &TheU : CUs) {
56 DIE &Die = TheU->getUnitDie();
57 const MCSection *USection = TheU->getSection();
58 Asm->OutStreamer.SwitchSection(USection);
60 // Emit the compile units header.
61 Asm->OutStreamer.EmitLabel(TheU->getLabelBegin());
63 // Emit size of content not including length itself
64 Asm->OutStreamer.AddComment("Length of Unit");
65 Asm->EmitInt32(TheU->getHeaderSize() + Die.getSize());
67 TheU->emitHeader(ASectionSym);
70 Asm->OutStreamer.EmitLabel(TheU->getLabelEnd());
73 // Compute the size and offset for each DIE.
74 void DwarfFile::computeSizeAndOffsets() {
75 // Offset from the first CU in the debug info section is 0 initially.
76 unsigned SecOffset = 0;
78 // Iterate over each compile unit and set the size and offsets for each
79 // DIE within each compile unit. All offsets are CU relative.
80 for (const auto &TheU : CUs) {
81 TheU->setDebugInfoOffset(SecOffset);
83 // CU-relative offset is reset to 0 here.
84 unsigned Offset = sizeof(int32_t) + // Length of Unit Info
85 TheU->getHeaderSize(); // Unit-specific headers
87 // EndOffset here is CU-relative, after laying out
89 unsigned EndOffset = computeSizeAndOffset(TheU->getUnitDie(), Offset);
90 SecOffset += EndOffset;
93 // Compute the size and offset of a DIE. The offset is relative to start of the
94 // CU. It returns the offset after laying out the DIE.
95 unsigned DwarfFile::computeSizeAndOffset(DIE &Die, unsigned Offset) {
96 // Record the abbreviation.
97 assignAbbrevNumber(Die.getAbbrev());
99 // Get the abbreviation for this DIE.
100 const DIEAbbrev &Abbrev = Die.getAbbrev();
103 Die.setOffset(Offset);
105 // Start the size with the size of abbreviation code.
106 Offset += getULEB128Size(Die.getAbbrevNumber());
108 const SmallVectorImpl<DIEValue *> &Values = Die.getValues();
109 const SmallVectorImpl<DIEAbbrevData> &AbbrevData = Abbrev.getData();
111 // Size the DIE attribute values.
112 for (unsigned i = 0, N = Values.size(); i < N; ++i)
113 // Size attribute value.
114 Offset += Values[i]->SizeOf(Asm, AbbrevData[i].getForm());
117 const auto &Children = Die.getChildren();
119 // Size the DIE children if any.
120 if (!Children.empty()) {
121 assert(Abbrev.hasChildren() && "Children flag not set");
123 for (auto &Child : Children)
124 Offset = computeSizeAndOffset(*Child, Offset);
126 // End of children marker.
127 Offset += sizeof(int8_t);
130 Die.setSize(Offset - Die.getOffset());
133 void DwarfFile::emitAbbrevs(const MCSection *Section) {
134 // Check to see if it is worth the effort.
135 if (!Abbreviations.empty()) {
136 // Start the debug abbrev section.
137 Asm->OutStreamer.SwitchSection(Section);
139 // For each abbrevation.
140 for (const DIEAbbrev *Abbrev : Abbreviations) {
141 // Emit the abbrevations code (base 1 index.)
142 Asm->EmitULEB128(Abbrev->getNumber(), "Abbreviation Code");
144 // Emit the abbreviations data.
148 // Mark end of abbreviations.
149 Asm->EmitULEB128(0, "EOM(3)");
153 // Emit strings into a string section.
154 void DwarfFile::emitStrings(const MCSection *StrSection,
155 const MCSection *OffsetSection) {
156 StrPool.emit(*Asm, StrSection, OffsetSection);