DwarfFile.cpp revision 2c3e0051c31c3f5b2328b447eadf1cf9c4427442
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#include "DwarfDebug.h" 12#include "DwarfUnit.h" 13#include "llvm/ADT/STLExtras.h" 14#include "llvm/IR/DataLayout.h" 15#include "llvm/MC/MCStreamer.h" 16#include "llvm/Support/LEB128.h" 17#include "llvm/Target/TargetLoweringObjectFile.h" 18 19namespace llvm { 20DwarfFile::DwarfFile(AsmPrinter *AP, StringRef Pref, BumpPtrAllocator &DA) 21 : Asm(AP), StrPool(DA, *Asm, Pref) {} 22 23DwarfFile::~DwarfFile() {} 24 25// Define a unique number for the abbreviation. 26// 27void DwarfFile::assignAbbrevNumber(DIEAbbrev &Abbrev) { 28 // Check the set for priors. 29 DIEAbbrev *InSet = AbbreviationsSet.GetOrInsertNode(&Abbrev); 30 31 // If it's newly added. 32 if (InSet == &Abbrev) { 33 // Add to abbreviation list. 34 Abbreviations.push_back(&Abbrev); 35 36 // Assign the vector position + 1 as its number. 37 Abbrev.setNumber(Abbreviations.size()); 38 } else { 39 // Assign existing abbreviation number. 40 Abbrev.setNumber(InSet->getNumber()); 41 } 42} 43 44void DwarfFile::addUnit(std::unique_ptr<DwarfUnit> U) { 45 CUs.push_back(std::move(U)); 46} 47 48// Emit the various dwarf units to the unit section USection with 49// the abbreviations going into ASection. 50void DwarfFile::emitUnits(bool UseOffsets) { 51 for (const auto &TheU : CUs) { 52 DIE &Die = TheU->getUnitDie(); 53 const MCSection *USection = TheU->getSection(); 54 Asm->OutStreamer.SwitchSection(USection); 55 56 TheU->emitHeader(UseOffsets); 57 58 Asm->emitDwarfDIE(Die); 59 } 60} 61 62// Compute the size and offset for each DIE. 63void DwarfFile::computeSizeAndOffsets() { 64 // Offset from the first CU in the debug info section is 0 initially. 65 unsigned SecOffset = 0; 66 67 // Iterate over each compile unit and set the size and offsets for each 68 // DIE within each compile unit. All offsets are CU relative. 69 for (const auto &TheU : CUs) { 70 TheU->setDebugInfoOffset(SecOffset); 71 72 // CU-relative offset is reset to 0 here. 73 unsigned Offset = sizeof(int32_t) + // Length of Unit Info 74 TheU->getHeaderSize(); // Unit-specific headers 75 76 // EndOffset here is CU-relative, after laying out 77 // all of the CU DIE. 78 unsigned EndOffset = computeSizeAndOffset(TheU->getUnitDie(), Offset); 79 SecOffset += EndOffset; 80 } 81} 82// Compute the size and offset of a DIE. The offset is relative to start of the 83// CU. It returns the offset after laying out the DIE. 84unsigned DwarfFile::computeSizeAndOffset(DIE &Die, unsigned Offset) { 85 // Record the abbreviation. 86 assignAbbrevNumber(Die.getAbbrev()); 87 88 // Get the abbreviation for this DIE. 89 const DIEAbbrev &Abbrev = Die.getAbbrev(); 90 91 // Set DIE offset 92 Die.setOffset(Offset); 93 94 // Start the size with the size of abbreviation code. 95 Offset += getULEB128Size(Die.getAbbrevNumber()); 96 97 const SmallVectorImpl<DIEValue *> &Values = Die.getValues(); 98 const SmallVectorImpl<DIEAbbrevData> &AbbrevData = Abbrev.getData(); 99 100 // Size the DIE attribute values. 101 for (unsigned i = 0, N = Values.size(); i < N; ++i) 102 // Size attribute value. 103 Offset += Values[i]->SizeOf(Asm, AbbrevData[i].getForm()); 104 105 // Get the children. 106 const auto &Children = Die.getChildren(); 107 108 // Size the DIE children if any. 109 if (!Children.empty()) { 110 assert(Abbrev.hasChildren() && "Children flag not set"); 111 112 for (auto &Child : Children) 113 Offset = computeSizeAndOffset(*Child, Offset); 114 115 // End of children marker. 116 Offset += sizeof(int8_t); 117 } 118 119 Die.setSize(Offset - Die.getOffset()); 120 return Offset; 121} 122 123void DwarfFile::emitAbbrevs(const MCSection *Section) { 124 // Check to see if it is worth the effort. 125 if (!Abbreviations.empty()) { 126 // Start the debug abbrev section. 127 Asm->OutStreamer.SwitchSection(Section); 128 Asm->emitDwarfAbbrevs(Abbreviations); 129 } 130} 131 132// Emit strings into a string section. 133void DwarfFile::emitStrings(const MCSection *StrSection, 134 const MCSection *OffsetSection) { 135 StrPool.emit(*Asm, StrSection, OffsetSection); 136} 137 138bool DwarfFile::addScopeVariable(LexicalScope *LS, DbgVariable *Var) { 139 SmallVectorImpl<DbgVariable *> &Vars = ScopeVariables[LS]; 140 DIVariable DV = Var->getVariable(); 141 // Variables with positive arg numbers are parameters. 142 if (unsigned ArgNum = DV->getArg()) { 143 // Keep all parameters in order at the start of the variable list to ensure 144 // function types are correct (no out-of-order parameters) 145 // 146 // This could be improved by only doing it for optimized builds (unoptimized 147 // builds have the right order to begin with), searching from the back (this 148 // would catch the unoptimized case quickly), or doing a binary search 149 // rather than linear search. 150 auto I = Vars.begin(); 151 while (I != Vars.end()) { 152 unsigned CurNum = (*I)->getVariable()->getArg(); 153 // A local (non-parameter) variable has been found, insert immediately 154 // before it. 155 if (CurNum == 0) 156 break; 157 // A later indexed parameter has been found, insert immediately before it. 158 if (CurNum > ArgNum) 159 break; 160 if (CurNum == ArgNum) { 161 (*I)->addMMIEntry(*Var); 162 return false; 163 } 164 ++I; 165 } 166 Vars.insert(I, Var); 167 return true; 168 } 169 170 Vars.push_back(Var); 171 return true; 172} 173} 174