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 "DWARFFormValue.h"
13#include "llvm/Support/Dwarf.h"
14#include "llvm/Support/Format.h"
15#include "llvm/Support/raw_ostream.h"
16using namespace llvm;
17using namespace dwarf;
18
19DataExtractor DWARFCompileUnit::getDebugInfoExtractor() const {
20  return DataExtractor(Context.getInfoSection(),
21                       Context.isLittleEndian(), getAddressByteSize());
22}
23
24bool DWARFCompileUnit::extract(DataExtractor debug_info, uint32_t *offset_ptr) {
25  clear();
26
27  Offset = *offset_ptr;
28
29  if (debug_info.isValidOffset(*offset_ptr)) {
30    uint64_t abbrOffset;
31    const DWARFDebugAbbrev *abbr = Context.getDebugAbbrev();
32    Length = debug_info.getU32(offset_ptr);
33    Version = debug_info.getU16(offset_ptr);
34    abbrOffset = debug_info.getU32(offset_ptr);
35    AddrSize = debug_info.getU8(offset_ptr);
36
37    bool lengthOK = debug_info.isValidOffset(getNextCompileUnitOffset()-1);
38    bool versionOK = DWARFContext::isSupportedVersion(Version);
39    bool abbrOffsetOK = Context.getAbbrevSection().size() > abbrOffset;
40    bool addrSizeOK = AddrSize == 4 || AddrSize == 8;
41
42    if (lengthOK && versionOK && addrSizeOK && abbrOffsetOK && abbr != NULL) {
43      Abbrevs = abbr->getAbbreviationDeclarationSet(abbrOffset);
44      return true;
45    }
46
47    // reset the offset to where we tried to parse from if anything went wrong
48    *offset_ptr = Offset;
49  }
50
51  return false;
52}
53
54uint32_t
55DWARFCompileUnit::extract(uint32_t offset, DataExtractor debug_info_data,
56                          const DWARFAbbreviationDeclarationSet *abbrevs) {
57  clear();
58
59  Offset = offset;
60
61  if (debug_info_data.isValidOffset(offset)) {
62    Length = debug_info_data.getU32(&offset);
63    Version = debug_info_data.getU16(&offset);
64    bool abbrevsOK = debug_info_data.getU32(&offset) == abbrevs->getOffset();
65    Abbrevs = abbrevs;
66    AddrSize = debug_info_data.getU8 (&offset);
67
68    bool versionOK = DWARFContext::isSupportedVersion(Version);
69    bool addrSizeOK = AddrSize == 4 || AddrSize == 8;
70
71    if (versionOK && addrSizeOK && abbrevsOK &&
72        debug_info_data.isValidOffset(offset))
73      return offset;
74  }
75  return 0;
76}
77
78void DWARFCompileUnit::clear() {
79  Offset = 0;
80  Length = 0;
81  Version = 0;
82  Abbrevs = 0;
83  AddrSize = 0;
84  BaseAddr = 0;
85  DieArray.clear();
86}
87
88void DWARFCompileUnit::dump(raw_ostream &OS) {
89  OS << format("0x%08x", Offset) << ": Compile Unit:"
90     << " length = " << format("0x%08x", Length)
91     << " version = " << format("0x%04x", Version)
92     << " abbr_offset = " << format("0x%04x", Abbrevs->getOffset())
93     << " addr_size = " << format("0x%02x", AddrSize)
94     << " (next CU at " << format("0x%08x", getNextCompileUnitOffset())
95     << ")\n";
96
97  getCompileUnitDIE(false)->dump(OS, this, -1U);
98}
99
100void DWARFCompileUnit::setDIERelations() {
101  if (DieArray.empty())
102    return;
103  DWARFDebugInfoEntryMinimal *die_array_begin = &DieArray.front();
104  DWARFDebugInfoEntryMinimal *die_array_end = &DieArray.back();
105  DWARFDebugInfoEntryMinimal *curr_die;
106  // We purposely are skipping the last element in the array in the loop below
107  // so that we can always have a valid next item
108  for (curr_die = die_array_begin; curr_die < die_array_end; ++curr_die) {
109    // Since our loop doesn't include the last element, we can always
110    // safely access the next die in the array.
111    DWARFDebugInfoEntryMinimal *next_die = curr_die + 1;
112
113    const DWARFAbbreviationDeclaration *curr_die_abbrev =
114      curr_die->getAbbreviationDeclarationPtr();
115
116    if (curr_die_abbrev) {
117      // Normal DIE
118      if (curr_die_abbrev->hasChildren())
119        next_die->setParent(curr_die);
120      else
121        curr_die->setSibling(next_die);
122    } else {
123      // NULL DIE that terminates a sibling chain
124      DWARFDebugInfoEntryMinimal *parent = curr_die->getParent();
125      if (parent)
126        parent->setSibling(next_die);
127    }
128  }
129
130  // Since we skipped the last element, we need to fix it up!
131  if (die_array_begin < die_array_end)
132    curr_die->setParent(die_array_begin);
133}
134
135size_t DWARFCompileUnit::extractDIEsIfNeeded(bool cu_die_only) {
136  const size_t initial_die_array_size = DieArray.size();
137  if ((cu_die_only && initial_die_array_size > 0) ||
138      initial_die_array_size > 1)
139    return 0; // Already parsed
140
141  // Set the offset to that of the first DIE and calculate the start of the
142  // next compilation unit header.
143  uint32_t offset = getFirstDIEOffset();
144  uint32_t next_cu_offset = getNextCompileUnitOffset();
145
146  DWARFDebugInfoEntryMinimal die;
147  // Keep a flat array of the DIE for binary lookup by DIE offset
148  uint32_t depth = 0;
149  // We are in our compile unit, parse starting at the offset
150  // we were told to parse
151
152  const uint8_t *fixed_form_sizes =
153    DWARFFormValue::getFixedFormSizesForAddressSize(getAddressByteSize());
154
155  while (offset < next_cu_offset &&
156         die.extractFast(this, fixed_form_sizes, &offset)) {
157
158    if (depth == 0) {
159      uint64_t base_addr =
160        die.getAttributeValueAsUnsigned(this, DW_AT_low_pc, -1U);
161      if (base_addr == -1U)
162        base_addr = die.getAttributeValueAsUnsigned(this, DW_AT_entry_pc, 0);
163      setBaseAddress(base_addr);
164    }
165
166    if (cu_die_only) {
167      addDIE(die);
168      return 1;
169    }
170    else if (depth == 0 && initial_die_array_size == 1) {
171      // Don't append the CU die as we already did that
172    } else {
173      addDIE (die);
174    }
175
176    const DWARFAbbreviationDeclaration *abbrDecl =
177      die.getAbbreviationDeclarationPtr();
178    if (abbrDecl) {
179      // Normal DIE
180      if (abbrDecl->hasChildren())
181        ++depth;
182    } else {
183      // NULL DIE.
184      if (depth > 0)
185        --depth;
186      if (depth == 0)
187        break;  // We are done with this compile unit!
188    }
189
190  }
191
192  // Give a little bit of info if we encounter corrupt DWARF (our offset
193  // should always terminate at or before the start of the next compilation
194  // unit header).
195  if (offset > next_cu_offset) {
196    fprintf (stderr, "warning: DWARF compile unit extends beyond its bounds cu 0x%8.8x at 0x%8.8x'\n", getOffset(), offset);
197  }
198
199  setDIERelations();
200  return DieArray.size();
201}
202
203void DWARFCompileUnit::clearDIEs(bool keep_compile_unit_die) {
204  if (DieArray.size() > 1) {
205    // std::vectors never get any smaller when resized to a smaller size,
206    // or when clear() or erase() are called, the size will report that it
207    // is smaller, but the memory allocated remains intact (call capacity()
208    // to see this). So we need to create a temporary vector and swap the
209    // contents which will cause just the internal pointers to be swapped
210    // so that when "tmp_array" goes out of scope, it will destroy the
211    // contents.
212
213    // Save at least the compile unit DIE
214    std::vector<DWARFDebugInfoEntryMinimal> tmpArray;
215    DieArray.swap(tmpArray);
216    if (keep_compile_unit_die)
217      DieArray.push_back(tmpArray.front());
218  }
219}
220
221void
222DWARFCompileUnit::buildAddressRangeTable(DWARFDebugAranges *debug_aranges,
223                                         bool clear_dies_if_already_not_parsed){
224  // This function is usually called if there in no .debug_aranges section
225  // in order to produce a compile unit level set of address ranges that
226  // is accurate. If the DIEs weren't parsed, then we don't want all dies for
227  // all compile units to stay loaded when they weren't needed. So we can end
228  // up parsing the DWARF and then throwing them all away to keep memory usage
229  // down.
230  const bool clear_dies = extractDIEsIfNeeded(false) > 1;
231
232  DieArray[0].buildAddressRangeTable(this, debug_aranges);
233
234  // Keep memory down by clearing DIEs if this generate function
235  // caused them to be parsed.
236  if (clear_dies)
237    clearDIEs(true);
238}
239