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());
74 // Compute the size and offset for each DIE.
75 void DwarfFile::computeSizeAndOffsets() {
76 // Offset from the first CU in the debug info section is 0 initially.
77 unsigned SecOffset = 0;
79 // Iterate over each compile unit and set the size and offsets for each
80 // DIE within each compile unit. All offsets are CU relative.
81 for (const auto &TheU : CUs) {
82 TheU->setDebugInfoOffset(SecOffset);
84 // CU-relative offset is reset to 0 here.
85 unsigned Offset = sizeof(int32_t) + // Length of Unit Info
86 TheU->getHeaderSize(); // Unit-specific headers
88 // EndOffset here is CU-relative, after laying out
90 unsigned EndOffset = computeSizeAndOffset(TheU->getUnitDie(), Offset);
91 SecOffset += EndOffset;
94 // Compute the size and offset of a DIE. The offset is relative to start of the
95 // CU. It returns the offset after laying out the DIE.
96 unsigned DwarfFile::computeSizeAndOffset(DIE &Die, unsigned Offset) {
97 // Record the abbreviation.
98 assignAbbrevNumber(Die.getAbbrev());
100 // Get the abbreviation for this DIE.
101 const DIEAbbrev &Abbrev = Die.getAbbrev();
104 Die.setOffset(Offset);
106 // Start the size with the size of abbreviation code.
107 Offset += getULEB128Size(Die.getAbbrevNumber());
109 const SmallVectorImpl<DIEValue *> &Values = Die.getValues();
110 const SmallVectorImpl<DIEAbbrevData> &AbbrevData = Abbrev.getData();
112 // Size the DIE attribute values.
113 for (unsigned i = 0, N = Values.size(); i < N; ++i)
114 // Size attribute value.
115 Offset += Values[i]->SizeOf(Asm, AbbrevData[i].getForm());
118 const auto &Children = Die.getChildren();
120 // Size the DIE children if any.
121 if (!Children.empty()) {
122 assert(Abbrev.hasChildren() && "Children flag not set");
124 for (auto &Child : Children)
125 Offset = computeSizeAndOffset(*Child, Offset);
127 // End of children marker.
128 Offset += sizeof(int8_t);
131 Die.setSize(Offset - Die.getOffset());
134 void DwarfFile::emitAbbrevs(const MCSection *Section) {
135 // Check to see if it is worth the effort.
136 if (!Abbreviations.empty()) {
137 // Start the debug abbrev section.
138 Asm->OutStreamer.SwitchSection(Section);
140 // For each abbrevation.
141 for (const DIEAbbrev *Abbrev : Abbreviations) {
142 // Emit the abbrevations code (base 1 index.)
143 Asm->EmitULEB128(Abbrev->getNumber(), "Abbreviation Code");
145 // Emit the abbreviations data.
149 // Mark end of abbreviations.
150 Asm->EmitULEB128(0, "EOM(3)");
154 // Emit strings into a string section.
155 void DwarfFile::emitStrings(const MCSection *StrSection,
156 const MCSection *OffsetSection) {
157 StrPool.emit(*Asm, StrSection, OffsetSection);
160 // If Var is a current function argument then add it to CurrentFnArguments list.
161 bool DwarfFile::addCurrentFnArgument(DbgVariable *Var, LexicalScope *Scope) {
162 if (Scope->getParent())
164 DIVariable DV = Var->getVariable();
165 if (DV.getTag() != dwarf::DW_TAG_arg_variable)
167 unsigned ArgNo = DV.getArgNumber();
171 auto &CurrentFnArguments = DD.getCurrentFnArguments();
173 // llvm::Function argument size is not good indicator of how many
174 // arguments does the function have at source level.
175 if (ArgNo > CurrentFnArguments.size())
176 CurrentFnArguments.resize(ArgNo * 2);
177 assert(!CurrentFnArguments[ArgNo - 1]);
178 CurrentFnArguments[ArgNo - 1] = Var;