DwarfFile.cpp revision 37ed9c199ca639565f6ce88105f9e39e898d82d0
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 20namespace llvm { 21DwarfFile::DwarfFile(AsmPrinter *AP, DwarfDebug &DD, StringRef Pref, 22 BumpPtrAllocator &DA) 23 : Asm(AP), DD(DD), StrPool(DA, *Asm, Pref) {} 24 25DwarfFile::~DwarfFile() {} 26 27// Define a unique number for the abbreviation. 28// 29void DwarfFile::assignAbbrevNumber(DIEAbbrev &Abbrev) { 30 // Check the set for priors. 31 DIEAbbrev *InSet = AbbreviationsSet.GetOrInsertNode(&Abbrev); 32 33 // If it's newly added. 34 if (InSet == &Abbrev) { 35 // Add to abbreviation list. 36 Abbreviations.push_back(&Abbrev); 37 38 // Assign the vector position + 1 as its number. 39 Abbrev.setNumber(Abbreviations.size()); 40 } else { 41 // Assign existing abbreviation number. 42 Abbrev.setNumber(InSet->getNumber()); 43 } 44} 45 46void DwarfFile::addUnit(std::unique_ptr<DwarfUnit> U) { 47 CUs.push_back(std::move(U)); 48} 49 50// Emit the various dwarf units to the unit section USection with 51// the abbreviations going into ASection. 52void DwarfFile::emitUnits(const MCSymbol *ASectionSym) { 53 for (const auto &TheU : CUs) { 54 DIE &Die = TheU->getUnitDie(); 55 const MCSection *USection = TheU->getSection(); 56 Asm->OutStreamer.SwitchSection(USection); 57 58 TheU->emitHeader(ASectionSym); 59 60 DD.emitDIE(Die); 61 } 62} 63 64// Compute the size and offset for each DIE. 65void DwarfFile::computeSizeAndOffsets() { 66 // Offset from the first CU in the debug info section is 0 initially. 67 unsigned SecOffset = 0; 68 69 // Iterate over each compile unit and set the size and offsets for each 70 // DIE within each compile unit. All offsets are CU relative. 71 for (const auto &TheU : CUs) { 72 TheU->setDebugInfoOffset(SecOffset); 73 74 // CU-relative offset is reset to 0 here. 75 unsigned Offset = sizeof(int32_t) + // Length of Unit Info 76 TheU->getHeaderSize(); // Unit-specific headers 77 78 // EndOffset here is CU-relative, after laying out 79 // all of the CU DIE. 80 unsigned EndOffset = computeSizeAndOffset(TheU->getUnitDie(), Offset); 81 SecOffset += EndOffset; 82 } 83} 84// Compute the size and offset of a DIE. The offset is relative to start of the 85// CU. It returns the offset after laying out the DIE. 86unsigned DwarfFile::computeSizeAndOffset(DIE &Die, unsigned Offset) { 87 // Record the abbreviation. 88 assignAbbrevNumber(Die.getAbbrev()); 89 90 // Get the abbreviation for this DIE. 91 const DIEAbbrev &Abbrev = Die.getAbbrev(); 92 93 // Set DIE offset 94 Die.setOffset(Offset); 95 96 // Start the size with the size of abbreviation code. 97 Offset += getULEB128Size(Die.getAbbrevNumber()); 98 99 const SmallVectorImpl<DIEValue *> &Values = Die.getValues(); 100 const SmallVectorImpl<DIEAbbrevData> &AbbrevData = Abbrev.getData(); 101 102 // Size the DIE attribute values. 103 for (unsigned i = 0, N = Values.size(); i < N; ++i) 104 // Size attribute value. 105 Offset += Values[i]->SizeOf(Asm, AbbrevData[i].getForm()); 106 107 // Get the children. 108 const auto &Children = Die.getChildren(); 109 110 // Size the DIE children if any. 111 if (!Children.empty()) { 112 assert(Abbrev.hasChildren() && "Children flag not set"); 113 114 for (auto &Child : Children) 115 Offset = computeSizeAndOffset(*Child, Offset); 116 117 // End of children marker. 118 Offset += sizeof(int8_t); 119 } 120 121 Die.setSize(Offset - Die.getOffset()); 122 return Offset; 123} 124void DwarfFile::emitAbbrevs(const MCSection *Section) { 125 // Check to see if it is worth the effort. 126 if (!Abbreviations.empty()) { 127 // Start the debug abbrev section. 128 Asm->OutStreamer.SwitchSection(Section); 129 130 // For each abbrevation. 131 for (const DIEAbbrev *Abbrev : Abbreviations) { 132 // Emit the abbrevations code (base 1 index.) 133 Asm->EmitULEB128(Abbrev->getNumber(), "Abbreviation Code"); 134 135 // Emit the abbreviations data. 136 Abbrev->Emit(Asm); 137 } 138 139 // Mark end of abbreviations. 140 Asm->EmitULEB128(0, "EOM(3)"); 141 } 142} 143 144// Emit strings into a string section. 145void DwarfFile::emitStrings(const MCSection *StrSection, 146 const MCSection *OffsetSection) { 147 StrPool.emit(*Asm, StrSection, OffsetSection); 148} 149 150void DwarfFile::addScopeVariable(LexicalScope *LS, DbgVariable *Var) { 151 SmallVectorImpl<DbgVariable *> &Vars = ScopeVariables[LS]; 152 DIVariable DV = Var->getVariable(); 153 // Variables with positive arg numbers are parameters. 154 if (unsigned ArgNum = DV.getArgNumber()) { 155 // Keep all parameters in order at the start of the variable list to ensure 156 // function types are correct (no out-of-order parameters) 157 // 158 // This could be improved by only doing it for optimized builds (unoptimized 159 // builds have the right order to begin with), searching from the back (this 160 // would catch the unoptimized case quickly), or doing a binary search 161 // rather than linear search. 162 auto I = Vars.begin(); 163 while (I != Vars.end()) { 164 unsigned CurNum = (*I)->getVariable().getArgNumber(); 165 // A local (non-parameter) variable has been found, insert immediately 166 // before it. 167 if (CurNum == 0) 168 break; 169 // A later indexed parameter has been found, insert immediately before it. 170 if (CurNum > ArgNum) 171 break; 172 // FIXME: There are still some cases where two inlined functions are 173 // conflated together (two calls to the same function at the same 174 // location (eg: via a macro, or without column info, etc)) and then 175 // their arguments are conflated as well. 176 assert((LS->getParent() || CurNum != ArgNum) && 177 "Duplicate argument for top level (non-inlined) function"); 178 ++I; 179 } 180 Vars.insert(I, Var); 181 return; 182 } 183 184 Vars.push_back(Var); 185} 186} 187