1 //===-- llvm/CodeGen/DwarfFile.cpp - Dwarf Debug Framework ----------------===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 10 #include "DwarfFile.h" 11 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" 19 20 namespace llvm { 21 DwarfFile::DwarfFile(AsmPrinter *AP, StringRef Pref, BumpPtrAllocator &DA) 22 : Asm(AP), StrPool(DA, *Asm, Pref) {} 23 24 DwarfFile::~DwarfFile() {} 25 26 // Define a unique number for the abbreviation. 27 // 28 void DwarfFile::assignAbbrevNumber(DIEAbbrev &Abbrev) { 29 // Check the set for priors. 30 DIEAbbrev *InSet = AbbreviationsSet.GetOrInsertNode(&Abbrev); 31 32 // If it's newly added. 33 if (InSet == &Abbrev) { 34 // Add to abbreviation list. 35 Abbreviations.push_back(&Abbrev); 36 37 // Assign the vector position + 1 as its number. 38 Abbrev.setNumber(Abbreviations.size()); 39 } else { 40 // Assign existing abbreviation number. 41 Abbrev.setNumber(InSet->getNumber()); 42 } 43 } 44 45 void DwarfFile::addUnit(std::unique_ptr<DwarfUnit> U) { 46 CUs.push_back(std::move(U)); 47 } 48 49 // Emit the various dwarf units to the unit section USection with 50 // the abbreviations going into ASection. 51 void DwarfFile::emitUnits(DwarfDebug *DD, const MCSymbol *ASectionSym) { 52 for (const auto &TheU : CUs) { 53 DIE &Die = TheU->getUnitDie(); 54 const MCSection *USection = TheU->getSection(); 55 Asm->OutStreamer.SwitchSection(USection); 56 57 // Emit the compile units header. 58 Asm->OutStreamer.EmitLabel(TheU->getLabelBegin()); 59 60 // Emit size of content not including length itself 61 Asm->OutStreamer.AddComment("Length of Unit"); 62 Asm->EmitInt32(TheU->getHeaderSize() + Die.getSize()); 63 64 TheU->emitHeader(ASectionSym); 65 66 DD->emitDIE(Die); 67 Asm->OutStreamer.EmitLabel(TheU->getLabelEnd()); 68 } 69 } 70 // Compute the size and offset for each DIE. 71 void DwarfFile::computeSizeAndOffsets() { 72 // Offset from the first CU in the debug info section is 0 initially. 73 unsigned SecOffset = 0; 74 75 // Iterate over each compile unit and set the size and offsets for each 76 // DIE within each compile unit. All offsets are CU relative. 77 for (const auto &TheU : CUs) { 78 TheU->setDebugInfoOffset(SecOffset); 79 80 // CU-relative offset is reset to 0 here. 81 unsigned Offset = sizeof(int32_t) + // Length of Unit Info 82 TheU->getHeaderSize(); // Unit-specific headers 83 84 // EndOffset here is CU-relative, after laying out 85 // all of the CU DIE. 86 unsigned EndOffset = computeSizeAndOffset(TheU->getUnitDie(), Offset); 87 SecOffset += EndOffset; 88 } 89 } 90 // Compute the size and offset of a DIE. The offset is relative to start of the 91 // CU. It returns the offset after laying out the DIE. 92 unsigned DwarfFile::computeSizeAndOffset(DIE &Die, unsigned Offset) { 93 // Record the abbreviation. 94 assignAbbrevNumber(Die.getAbbrev()); 95 96 // Get the abbreviation for this DIE. 97 const DIEAbbrev &Abbrev = Die.getAbbrev(); 98 99 // Set DIE offset 100 Die.setOffset(Offset); 101 102 // Start the size with the size of abbreviation code. 103 Offset += getULEB128Size(Die.getAbbrevNumber()); 104 105 const SmallVectorImpl<DIEValue *> &Values = Die.getValues(); 106 const SmallVectorImpl<DIEAbbrevData> &AbbrevData = Abbrev.getData(); 107 108 // Size the DIE attribute values. 109 for (unsigned i = 0, N = Values.size(); i < N; ++i) 110 // Size attribute value. 111 Offset += Values[i]->SizeOf(Asm, AbbrevData[i].getForm()); 112 113 // Get the children. 114 const auto &Children = Die.getChildren(); 115 116 // Size the DIE children if any. 117 if (!Children.empty()) { 118 assert(Abbrev.hasChildren() && "Children flag not set"); 119 120 for (auto &Child : Children) 121 Offset = computeSizeAndOffset(*Child, Offset); 122 123 // End of children marker. 124 Offset += sizeof(int8_t); 125 } 126 127 Die.setSize(Offset - Die.getOffset()); 128 return Offset; 129 } 130 void DwarfFile::emitAbbrevs(const MCSection *Section) { 131 // Check to see if it is worth the effort. 132 if (!Abbreviations.empty()) { 133 // Start the debug abbrev section. 134 Asm->OutStreamer.SwitchSection(Section); 135 136 // For each abbrevation. 137 for (const DIEAbbrev *Abbrev : Abbreviations) { 138 // Emit the abbrevations code (base 1 index.) 139 Asm->EmitULEB128(Abbrev->getNumber(), "Abbreviation Code"); 140 141 // Emit the abbreviations data. 142 Abbrev->Emit(Asm); 143 } 144 145 // Mark end of abbreviations. 146 Asm->EmitULEB128(0, "EOM(3)"); 147 } 148 } 149 150 // Emit strings into a string section. 151 void DwarfFile::emitStrings(const MCSection *StrSection, 152 const MCSection *OffsetSection, 153 const MCSymbol *StrSecSym) { 154 StrPool.emit(*Asm, StrSection, OffsetSection, StrSecSym); 155 } 156 } 157
