Home | History | Annotate | Download | only in DebugInfo 
      1 //===-- DWARFCompileUnit.cpp ----------------------------------------------===//
      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 "DWARFCompileUnit.h"
     11 #include "DWARFContext.h"
     12 #include "llvm/DebugInfo/DWARFFormValue.h"
     13 #include "llvm/Support/Dwarf.h"
     14 #include "llvm/Support/Format.h"
     15 #include "llvm/Support/raw_ostream.h"
     16 using namespace llvm;
     17 using namespace dwarf;
     18 
     19 DataExtractor DWARFCompileUnit::getDebugInfoExtractor() const {
     20   return DataExtractor(InfoSection, isLittleEndian, AddrSize);
     21 }
     22 
     23 bool DWARFCompileUnit::extract(DataExtractor debug_info, uint32_t *offset_ptr) {
     24   clear();
     25 
     26   Offset = *offset_ptr;
     27 
     28   if (debug_info.isValidOffset(*offset_ptr)) {
     29     uint64_t abbrOffset;
     30     Length = debug_info.getU32(offset_ptr);
     31     Version = debug_info.getU16(offset_ptr);
     32     abbrOffset = debug_info.getU32(offset_ptr);
     33     AddrSize = debug_info.getU8(offset_ptr);
     34 
     35     bool lengthOK = debug_info.isValidOffset(getNextCompileUnitOffset()-1);
     36     bool versionOK = DWARFContext::isSupportedVersion(Version);
     37     bool abbrOffsetOK = AbbrevSection.size() > abbrOffset;
     38     bool addrSizeOK = AddrSize == 4 || AddrSize == 8;
     39 
     40     if (lengthOK && versionOK && addrSizeOK && abbrOffsetOK && Abbrev != NULL) {
     41       Abbrevs = Abbrev->getAbbreviationDeclarationSet(abbrOffset);
     42       return true;
     43     }
     44 
     45     // reset the offset to where we tried to parse from if anything went wrong
     46     *offset_ptr = Offset;
     47   }
     48 
     49   return false;
     50 }
     51 
     52 uint32_t
     53 DWARFCompileUnit::extract(uint32_t offset, DataExtractor debug_info_data,
     54                           const DWARFAbbreviationDeclarationSet *abbrevs) {
     55   clear();
     56 
     57   Offset = offset;
     58 
     59   if (debug_info_data.isValidOffset(offset)) {
     60     Length = debug_info_data.getU32(&offset);
     61     Version = debug_info_data.getU16(&offset);
     62     bool abbrevsOK = debug_info_data.getU32(&offset) == abbrevs->getOffset();
     63     Abbrevs = abbrevs;
     64     AddrSize = debug_info_data.getU8(&offset);
     65 
     66     bool versionOK = DWARFContext::isSupportedVersion(Version);
     67     bool addrSizeOK = AddrSize == 4 || AddrSize == 8;
     68 
     69     if (versionOK && addrSizeOK && abbrevsOK &&
     70         debug_info_data.isValidOffset(offset))
     71       return offset;
     72   }
     73   return 0;
     74 }
     75 
     76 bool DWARFCompileUnit::extractRangeList(uint32_t RangeListOffset,
     77                                         DWARFDebugRangeList &RangeList) const {
     78   // Require that compile unit is extracted.
     79   assert(DieArray.size() > 0);
     80   DataExtractor RangesData(RangeSection, isLittleEndian, AddrSize);
     81   return RangeList.extract(RangesData, &RangeListOffset);
     82 }
     83 
     84 void DWARFCompileUnit::clear() {
     85   Offset = 0;
     86   Length = 0;
     87   Version = 0;
     88   Abbrevs = 0;
     89   AddrSize = 0;
     90   BaseAddr = 0;
     91   clearDIEs(false);
     92 }
     93 
     94 void DWARFCompileUnit::dump(raw_ostream &OS) {
     95   OS << format("0x%08x", Offset) << ": Compile Unit:"
     96      << " length = " << format("0x%08x", Length)
     97      << " version = " << format("0x%04x", Version)
     98      << " abbr_offset = " << format("0x%04x", Abbrevs->getOffset())
     99      << " addr_size = " << format("0x%02x", AddrSize)
    100      << " (next CU at " << format("0x%08x", getNextCompileUnitOffset())
    101      << ")\n";
    102 
    103   const DWARFDebugInfoEntryMinimal *CU = getCompileUnitDIE(false);
    104   assert(CU && "Null Compile Unit?");
    105   CU->dump(OS, this, -1U);
    106 }
    107 
    108 const char *DWARFCompileUnit::getCompilationDir() {
    109   extractDIEsIfNeeded(true);
    110   if (DieArray.empty())
    111     return 0;
    112   return DieArray[0].getAttributeValueAsString(this, DW_AT_comp_dir, 0);
    113 }
    114 
    115 void DWARFCompileUnit::setDIERelations() {
    116   if (DieArray.empty())
    117     return;
    118   DWARFDebugInfoEntryMinimal *die_array_begin = &DieArray.front();
    119   DWARFDebugInfoEntryMinimal *die_array_end = &DieArray.back();
    120   DWARFDebugInfoEntryMinimal *curr_die;
    121   // We purposely are skipping the last element in the array in the loop below
    122   // so that we can always have a valid next item
    123   for (curr_die = die_array_begin; curr_die < die_array_end; ++curr_die) {
    124     // Since our loop doesn't include the last element, we can always
    125     // safely access the next die in the array.
    126     DWARFDebugInfoEntryMinimal *next_die = curr_die + 1;
    127 
    128     const DWARFAbbreviationDeclaration *curr_die_abbrev =
    129       curr_die->getAbbreviationDeclarationPtr();
    130 
    131     if (curr_die_abbrev) {
    132       // Normal DIE
    133       if (curr_die_abbrev->hasChildren())
    134         next_die->setParent(curr_die);
    135       else
    136         curr_die->setSibling(next_die);
    137     } else {
    138       // NULL DIE that terminates a sibling chain
    139       DWARFDebugInfoEntryMinimal *parent = curr_die->getParent();
    140       if (parent)
    141         parent->setSibling(next_die);
    142     }
    143   }
    144 
    145   // Since we skipped the last element, we need to fix it up!
    146   if (die_array_begin < die_array_end)
    147     curr_die->setParent(die_array_begin);
    148 }
    149 
    150 void DWARFCompileUnit::extractDIEsToVector(
    151     bool AppendCUDie, bool AppendNonCUDies,
    152     std::vector<DWARFDebugInfoEntryMinimal> &Dies) const {
    153   if (!AppendCUDie && !AppendNonCUDies)
    154     return;
    155 
    156   // Set the offset to that of the first DIE and calculate the start of the
    157   // next compilation unit header.
    158   uint32_t Offset = getFirstDIEOffset();
    159   uint32_t NextCUOffset = getNextCompileUnitOffset();
    160   DWARFDebugInfoEntryMinimal DIE;
    161   uint32_t Depth = 0;
    162   const uint8_t *FixedFormSizes =
    163     DWARFFormValue::getFixedFormSizes(getAddressByteSize(), getVersion());
    164   bool IsCUDie = true;
    165 
    166   while (Offset < NextCUOffset &&
    167          DIE.extractFast(this, FixedFormSizes, &Offset)) {
    168     if (IsCUDie) {
    169       if (AppendCUDie)
    170         Dies.push_back(DIE);
    171       if (!AppendNonCUDies)
    172         break;
    173       // The average bytes per DIE entry has been seen to be
    174       // around 14-20 so let's pre-reserve the needed memory for
    175       // our DIE entries accordingly.
    176       Dies.reserve(Dies.size() + getDebugInfoSize() / 14);
    177       IsCUDie = false;
    178     } else {
    179       Dies.push_back(DIE);
    180     }
    181 
    182     const DWARFAbbreviationDeclaration *AbbrDecl =
    183       DIE.getAbbreviationDeclarationPtr();
    184     if (AbbrDecl) {
    185       // Normal DIE
    186       if (AbbrDecl->hasChildren())
    187         ++Depth;
    188     } else {
    189       // NULL DIE.
    190       if (Depth > 0)
    191         --Depth;
    192       if (Depth == 0)
    193         break;  // We are done with this compile unit!
    194     }
    195   }
    196 
    197   // Give a little bit of info if we encounter corrupt DWARF (our offset
    198   // should always terminate at or before the start of the next compilation
    199   // unit header).
    200   if (Offset > NextCUOffset)
    201     fprintf(stderr, "warning: DWARF compile unit extends beyond its "
    202                     "bounds cu 0x%8.8x at 0x%8.8x'\n", getOffset(), Offset);
    203 }
    204 
    205 size_t DWARFCompileUnit::extractDIEsIfNeeded(bool CUDieOnly) {
    206   if ((CUDieOnly && DieArray.size() > 0) ||
    207       DieArray.size() > 1)
    208     return 0; // Already parsed.
    209 
    210   extractDIEsToVector(DieArray.empty(), !CUDieOnly, DieArray);
    211 
    212   // Set the base address of current compile unit.
    213   if (!DieArray.empty()) {
    214     uint64_t BaseAddr =
    215       DieArray[0].getAttributeValueAsUnsigned(this, DW_AT_low_pc, -1U);
    216     if (BaseAddr == -1U)
    217       BaseAddr = DieArray[0].getAttributeValueAsUnsigned(this, DW_AT_entry_pc, 0);
    218     setBaseAddress(BaseAddr);
    219   }
    220 
    221   setDIERelations();
    222   return DieArray.size();
    223 }
    224 
    225 void DWARFCompileUnit::clearDIEs(bool KeepCUDie) {
    226   if (DieArray.size() > (unsigned)KeepCUDie) {
    227     // std::vectors never get any smaller when resized to a smaller size,
    228     // or when clear() or erase() are called, the size will report that it
    229     // is smaller, but the memory allocated remains intact (call capacity()
    230     // to see this). So we need to create a temporary vector and swap the
    231     // contents which will cause just the internal pointers to be swapped
    232     // so that when temporary vector goes out of scope, it will destroy the
    233     // contents.
    234     std::vector<DWARFDebugInfoEntryMinimal> TmpArray;
    235     DieArray.swap(TmpArray);
    236     // Save at least the compile unit DIE
    237     if (KeepCUDie)
    238       DieArray.push_back(TmpArray.front());
    239   }
    240 }
    241 
    242 void
    243 DWARFCompileUnit::buildAddressRangeTable(DWARFDebugAranges *debug_aranges,
    244                                          bool clear_dies_if_already_not_parsed){
    245   // This function is usually called if there in no .debug_aranges section
    246   // in order to produce a compile unit level set of address ranges that
    247   // is accurate. If the DIEs weren't parsed, then we don't want all dies for
    248   // all compile units to stay loaded when they weren't needed. So we can end
    249   // up parsing the DWARF and then throwing them all away to keep memory usage
    250   // down.
    251   const bool clear_dies = extractDIEsIfNeeded(false) > 1 &&
    252                           clear_dies_if_already_not_parsed;
    253   DieArray[0].buildAddressRangeTable(this, debug_aranges);
    254 
    255   // Keep memory down by clearing DIEs if this generate function
    256   // caused them to be parsed.
    257   if (clear_dies)
    258     clearDIEs(true);
    259 }
    260 
    261 DWARFDebugInfoEntryInlinedChain
    262 DWARFCompileUnit::getInlinedChainForAddress(uint64_t Address) {
    263   // First, find a subprogram that contains the given address (the root
    264   // of inlined chain).
    265   extractDIEsIfNeeded(false);
    266   const DWARFDebugInfoEntryMinimal *SubprogramDIE = 0;
    267   for (size_t i = 0, n = DieArray.size(); i != n; i++) {
    268     if (DieArray[i].isSubprogramDIE() &&
    269         DieArray[i].addressRangeContainsAddress(this, Address)) {
    270       SubprogramDIE = &DieArray[i];
    271       break;
    272     }
    273   }
    274   // Get inlined chain rooted at this subprogram DIE.
    275   if (!SubprogramDIE)
    276     return DWARFDebugInfoEntryInlinedChain();
    277   return SubprogramDIE->getInlinedChainForAddress(this, Address);
    278 }
    279