1//===-- DWARFContext.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 "llvm/DebugInfo/DWARF/DWARFContext.h"
11#include "llvm/ADT/SmallString.h"
12#include "llvm/ADT/StringSwitch.h"
13#include "llvm/DebugInfo/DWARF/DWARFAcceleratorTable.h"
14#include "llvm/DebugInfo/DWARF/DWARFDebugArangeSet.h"
15#include "llvm/DebugInfo/DWARF/DWARFUnitIndex.h"
16#include "llvm/Support/Compression.h"
17#include "llvm/Support/Dwarf.h"
18#include "llvm/Support/Format.h"
19#include "llvm/Support/Path.h"
20#include "llvm/Support/raw_ostream.h"
21#include <algorithm>
22using namespace llvm;
23using namespace dwarf;
24using namespace object;
25
26#define DEBUG_TYPE "dwarf"
27
28typedef DWARFDebugLine::LineTable DWARFLineTable;
29typedef DILineInfoSpecifier::FileLineInfoKind FileLineInfoKind;
30typedef DILineInfoSpecifier::FunctionNameKind FunctionNameKind;
31
32static void dumpPubSection(raw_ostream &OS, StringRef Name, StringRef Data,
33                           bool LittleEndian, bool GnuStyle) {
34  OS << "\n." << Name << " contents:\n";
35  DataExtractor pubNames(Data, LittleEndian, 0);
36  uint32_t offset = 0;
37  while (pubNames.isValidOffset(offset)) {
38    OS << "length = " << format("0x%08x", pubNames.getU32(&offset));
39    OS << " version = " << format("0x%04x", pubNames.getU16(&offset));
40    OS << " unit_offset = " << format("0x%08x", pubNames.getU32(&offset));
41    OS << " unit_size = " << format("0x%08x", pubNames.getU32(&offset)) << '\n';
42    if (GnuStyle)
43      OS << "Offset     Linkage  Kind     Name\n";
44    else
45      OS << "Offset     Name\n";
46
47    while (offset < Data.size()) {
48      uint32_t dieRef = pubNames.getU32(&offset);
49      if (dieRef == 0)
50        break;
51      OS << format("0x%8.8x ", dieRef);
52      if (GnuStyle) {
53        PubIndexEntryDescriptor desc(pubNames.getU8(&offset));
54        OS << format("%-8s", dwarf::GDBIndexEntryLinkageString(desc.Linkage))
55           << ' ' << format("%-8s", dwarf::GDBIndexEntryKindString(desc.Kind))
56           << ' ';
57      }
58      OS << '\"' << pubNames.getCStr(&offset) << "\"\n";
59    }
60  }
61}
62
63static void dumpAccelSection(raw_ostream &OS, StringRef Name,
64                             const DWARFSection& Section, StringRef StringSection,
65                             bool LittleEndian) {
66  DataExtractor AccelSection(Section.Data, LittleEndian, 0);
67  DataExtractor StrData(StringSection, LittleEndian, 0);
68  OS << "\n." << Name << " contents:\n";
69  DWARFAcceleratorTable Accel(AccelSection, StrData, Section.Relocs);
70  if (!Accel.extract())
71    return;
72  Accel.dump(OS);
73}
74
75void DWARFContext::dump(raw_ostream &OS, DIDumpType DumpType) {
76  if (DumpType == DIDT_All || DumpType == DIDT_Abbrev) {
77    OS << ".debug_abbrev contents:\n";
78    getDebugAbbrev()->dump(OS);
79  }
80
81  if (DumpType == DIDT_All || DumpType == DIDT_AbbrevDwo)
82    if (const DWARFDebugAbbrev *D = getDebugAbbrevDWO()) {
83      OS << "\n.debug_abbrev.dwo contents:\n";
84      D->dump(OS);
85    }
86
87  if (DumpType == DIDT_All || DumpType == DIDT_Info) {
88    OS << "\n.debug_info contents:\n";
89    for (const auto &CU : compile_units())
90      CU->dump(OS);
91  }
92
93  if ((DumpType == DIDT_All || DumpType == DIDT_InfoDwo) &&
94      getNumDWOCompileUnits()) {
95    OS << "\n.debug_info.dwo contents:\n";
96    for (const auto &DWOCU : dwo_compile_units())
97      DWOCU->dump(OS);
98  }
99
100  if ((DumpType == DIDT_All || DumpType == DIDT_Types) && getNumTypeUnits()) {
101    OS << "\n.debug_types contents:\n";
102    for (const auto &TUS : type_unit_sections())
103      for (const auto &TU : TUS)
104        TU->dump(OS);
105  }
106
107  if ((DumpType == DIDT_All || DumpType == DIDT_TypesDwo) &&
108      getNumDWOTypeUnits()) {
109    OS << "\n.debug_types.dwo contents:\n";
110    for (const auto &DWOTUS : dwo_type_unit_sections())
111      for (const auto &DWOTU : DWOTUS)
112        DWOTU->dump(OS);
113  }
114
115  if (DumpType == DIDT_All || DumpType == DIDT_Loc) {
116    OS << "\n.debug_loc contents:\n";
117    getDebugLoc()->dump(OS);
118  }
119
120  if (DumpType == DIDT_All || DumpType == DIDT_LocDwo) {
121    OS << "\n.debug_loc.dwo contents:\n";
122    getDebugLocDWO()->dump(OS);
123  }
124
125  if (DumpType == DIDT_All || DumpType == DIDT_Frames) {
126    OS << "\n.debug_frame contents:\n";
127    getDebugFrame()->dump(OS);
128  }
129
130  if (DumpType == DIDT_All || DumpType == DIDT_Macro) {
131    OS << "\n.debug_macinfo contents:\n";
132    getDebugMacro()->dump(OS);
133  }
134
135  uint32_t offset = 0;
136  if (DumpType == DIDT_All || DumpType == DIDT_Aranges) {
137    OS << "\n.debug_aranges contents:\n";
138    DataExtractor arangesData(getARangeSection(), isLittleEndian(), 0);
139    DWARFDebugArangeSet set;
140    while (set.extract(arangesData, &offset))
141      set.dump(OS);
142  }
143
144  uint8_t savedAddressByteSize = 0;
145  if (DumpType == DIDT_All || DumpType == DIDT_Line) {
146    OS << "\n.debug_line contents:\n";
147    for (const auto &CU : compile_units()) {
148      savedAddressByteSize = CU->getAddressByteSize();
149      const auto *CUDIE = CU->getUnitDIE();
150      if (CUDIE == nullptr)
151        continue;
152      unsigned stmtOffset = CUDIE->getAttributeValueAsSectionOffset(
153          CU.get(), DW_AT_stmt_list, -1U);
154      if (stmtOffset != -1U) {
155        DataExtractor lineData(getLineSection().Data, isLittleEndian(),
156                               savedAddressByteSize);
157        DWARFDebugLine::LineTable LineTable;
158        LineTable.parse(lineData, &getLineSection().Relocs, &stmtOffset);
159        LineTable.dump(OS);
160      }
161    }
162  }
163
164  if (DumpType == DIDT_All || DumpType == DIDT_CUIndex) {
165    OS << "\n.debug_cu_index contents:\n";
166    getCUIndex().dump(OS);
167  }
168
169  if (DumpType == DIDT_All || DumpType == DIDT_TUIndex) {
170    OS << "\n.debug_tu_index contents:\n";
171    getTUIndex().dump(OS);
172  }
173
174  if (DumpType == DIDT_All || DumpType == DIDT_LineDwo) {
175    OS << "\n.debug_line.dwo contents:\n";
176    unsigned stmtOffset = 0;
177    DataExtractor lineData(getLineDWOSection().Data, isLittleEndian(),
178                           savedAddressByteSize);
179    DWARFDebugLine::LineTable LineTable;
180    while (LineTable.Prologue.parse(lineData, &stmtOffset)) {
181      LineTable.dump(OS);
182      LineTable.clear();
183    }
184  }
185
186  if (DumpType == DIDT_All || DumpType == DIDT_Str) {
187    OS << "\n.debug_str contents:\n";
188    DataExtractor strData(getStringSection(), isLittleEndian(), 0);
189    offset = 0;
190    uint32_t strOffset = 0;
191    while (const char *s = strData.getCStr(&offset)) {
192      OS << format("0x%8.8x: \"%s\"\n", strOffset, s);
193      strOffset = offset;
194    }
195  }
196
197  if ((DumpType == DIDT_All || DumpType == DIDT_StrDwo) &&
198      !getStringDWOSection().empty()) {
199    OS << "\n.debug_str.dwo contents:\n";
200    DataExtractor strDWOData(getStringDWOSection(), isLittleEndian(), 0);
201    offset = 0;
202    uint32_t strDWOOffset = 0;
203    while (const char *s = strDWOData.getCStr(&offset)) {
204      OS << format("0x%8.8x: \"%s\"\n", strDWOOffset, s);
205      strDWOOffset = offset;
206    }
207  }
208
209  if (DumpType == DIDT_All || DumpType == DIDT_Ranges) {
210    OS << "\n.debug_ranges contents:\n";
211    // In fact, different compile units may have different address byte
212    // sizes, but for simplicity we just use the address byte size of the last
213    // compile unit (there is no easy and fast way to associate address range
214    // list and the compile unit it describes).
215    DataExtractor rangesData(getRangeSection(), isLittleEndian(),
216                             savedAddressByteSize);
217    offset = 0;
218    DWARFDebugRangeList rangeList;
219    while (rangeList.extract(rangesData, &offset))
220      rangeList.dump(OS);
221  }
222
223  if (DumpType == DIDT_All || DumpType == DIDT_Pubnames)
224    dumpPubSection(OS, "debug_pubnames", getPubNamesSection(),
225                   isLittleEndian(), false);
226
227  if (DumpType == DIDT_All || DumpType == DIDT_Pubtypes)
228    dumpPubSection(OS, "debug_pubtypes", getPubTypesSection(),
229                   isLittleEndian(), false);
230
231  if (DumpType == DIDT_All || DumpType == DIDT_GnuPubnames)
232    dumpPubSection(OS, "debug_gnu_pubnames", getGnuPubNamesSection(),
233                   isLittleEndian(), true /* GnuStyle */);
234
235  if (DumpType == DIDT_All || DumpType == DIDT_GnuPubtypes)
236    dumpPubSection(OS, "debug_gnu_pubtypes", getGnuPubTypesSection(),
237                   isLittleEndian(), true /* GnuStyle */);
238
239  if ((DumpType == DIDT_All || DumpType == DIDT_StrOffsetsDwo) &&
240      !getStringOffsetDWOSection().empty()) {
241    OS << "\n.debug_str_offsets.dwo contents:\n";
242    DataExtractor strOffsetExt(getStringOffsetDWOSection(), isLittleEndian(),
243                               0);
244    offset = 0;
245    uint64_t size = getStringOffsetDWOSection().size();
246    while (offset < size) {
247      OS << format("0x%8.8x: ", offset);
248      OS << format("%8.8x\n", strOffsetExt.getU32(&offset));
249    }
250  }
251
252  if (DumpType == DIDT_All || DumpType == DIDT_AppleNames)
253    dumpAccelSection(OS, "apple_names", getAppleNamesSection(),
254                     getStringSection(), isLittleEndian());
255
256  if (DumpType == DIDT_All || DumpType == DIDT_AppleTypes)
257    dumpAccelSection(OS, "apple_types", getAppleTypesSection(),
258                     getStringSection(), isLittleEndian());
259
260  if (DumpType == DIDT_All || DumpType == DIDT_AppleNamespaces)
261    dumpAccelSection(OS, "apple_namespaces", getAppleNamespacesSection(),
262                     getStringSection(), isLittleEndian());
263
264  if (DumpType == DIDT_All || DumpType == DIDT_AppleObjC)
265    dumpAccelSection(OS, "apple_objc", getAppleObjCSection(),
266                     getStringSection(), isLittleEndian());
267}
268
269const DWARFUnitIndex &DWARFContext::getCUIndex() {
270  if (CUIndex)
271    return *CUIndex;
272
273  DataExtractor CUIndexData(getCUIndexSection(), isLittleEndian(), 0);
274
275  CUIndex = llvm::make_unique<DWARFUnitIndex>(DW_SECT_INFO);
276  CUIndex->parse(CUIndexData);
277  return *CUIndex;
278}
279
280const DWARFUnitIndex &DWARFContext::getTUIndex() {
281  if (TUIndex)
282    return *TUIndex;
283
284  DataExtractor TUIndexData(getTUIndexSection(), isLittleEndian(), 0);
285
286  TUIndex = llvm::make_unique<DWARFUnitIndex>(DW_SECT_TYPES);
287  TUIndex->parse(TUIndexData);
288  return *TUIndex;
289}
290
291const DWARFDebugAbbrev *DWARFContext::getDebugAbbrev() {
292  if (Abbrev)
293    return Abbrev.get();
294
295  DataExtractor abbrData(getAbbrevSection(), isLittleEndian(), 0);
296
297  Abbrev.reset(new DWARFDebugAbbrev());
298  Abbrev->extract(abbrData);
299  return Abbrev.get();
300}
301
302const DWARFDebugAbbrev *DWARFContext::getDebugAbbrevDWO() {
303  if (AbbrevDWO)
304    return AbbrevDWO.get();
305
306  DataExtractor abbrData(getAbbrevDWOSection(), isLittleEndian(), 0);
307  AbbrevDWO.reset(new DWARFDebugAbbrev());
308  AbbrevDWO->extract(abbrData);
309  return AbbrevDWO.get();
310}
311
312const DWARFDebugLoc *DWARFContext::getDebugLoc() {
313  if (Loc)
314    return Loc.get();
315
316  DataExtractor LocData(getLocSection().Data, isLittleEndian(), 0);
317  Loc.reset(new DWARFDebugLoc(getLocSection().Relocs));
318  // assume all compile units have the same address byte size
319  if (getNumCompileUnits())
320    Loc->parse(LocData, getCompileUnitAtIndex(0)->getAddressByteSize());
321  return Loc.get();
322}
323
324const DWARFDebugLocDWO *DWARFContext::getDebugLocDWO() {
325  if (LocDWO)
326    return LocDWO.get();
327
328  DataExtractor LocData(getLocDWOSection().Data, isLittleEndian(), 0);
329  LocDWO.reset(new DWARFDebugLocDWO());
330  LocDWO->parse(LocData);
331  return LocDWO.get();
332}
333
334const DWARFDebugAranges *DWARFContext::getDebugAranges() {
335  if (Aranges)
336    return Aranges.get();
337
338  Aranges.reset(new DWARFDebugAranges());
339  Aranges->generate(this);
340  return Aranges.get();
341}
342
343const DWARFDebugFrame *DWARFContext::getDebugFrame() {
344  if (DebugFrame)
345    return DebugFrame.get();
346
347  // There's a "bug" in the DWARFv3 standard with respect to the target address
348  // size within debug frame sections. While DWARF is supposed to be independent
349  // of its container, FDEs have fields with size being "target address size",
350  // which isn't specified in DWARF in general. It's only specified for CUs, but
351  // .eh_frame can appear without a .debug_info section. Follow the example of
352  // other tools (libdwarf) and extract this from the container (ObjectFile
353  // provides this information). This problem is fixed in DWARFv4
354  // See this dwarf-discuss discussion for more details:
355  // http://lists.dwarfstd.org/htdig.cgi/dwarf-discuss-dwarfstd.org/2011-December/001173.html
356  DataExtractor debugFrameData(getDebugFrameSection(), isLittleEndian(),
357                               getAddressSize());
358  DebugFrame.reset(new DWARFDebugFrame());
359  DebugFrame->parse(debugFrameData);
360  return DebugFrame.get();
361}
362
363const DWARFDebugMacro *DWARFContext::getDebugMacro() {
364  if (Macro)
365    return Macro.get();
366
367  DataExtractor MacinfoData(getMacinfoSection(), isLittleEndian(), 0);
368  Macro.reset(new DWARFDebugMacro());
369  Macro->parse(MacinfoData);
370  return Macro.get();
371}
372
373const DWARFLineTable *
374DWARFContext::getLineTableForUnit(DWARFUnit *U) {
375  if (!Line)
376    Line.reset(new DWARFDebugLine(&getLineSection().Relocs));
377
378  const auto *UnitDIE = U->getUnitDIE();
379  if (UnitDIE == nullptr)
380    return nullptr;
381
382  unsigned stmtOffset =
383      UnitDIE->getAttributeValueAsSectionOffset(U, DW_AT_stmt_list, -1U);
384  if (stmtOffset == -1U)
385    return nullptr; // No line table for this compile unit.
386
387  stmtOffset += U->getLineTableOffset();
388  // See if the line table is cached.
389  if (const DWARFLineTable *lt = Line->getLineTable(stmtOffset))
390    return lt;
391
392  // We have to parse it first.
393  DataExtractor lineData(U->getLineSection(), isLittleEndian(),
394                         U->getAddressByteSize());
395  return Line->getOrParseLineTable(lineData, stmtOffset);
396}
397
398void DWARFContext::parseCompileUnits() {
399  CUs.parse(*this, getInfoSection());
400}
401
402void DWARFContext::parseTypeUnits() {
403  if (!TUs.empty())
404    return;
405  for (const auto &I : getTypesSections()) {
406    TUs.emplace_back();
407    TUs.back().parse(*this, I.second);
408  }
409}
410
411void DWARFContext::parseDWOCompileUnits() {
412  DWOCUs.parseDWO(*this, getInfoDWOSection());
413}
414
415void DWARFContext::parseDWOTypeUnits() {
416  if (!DWOTUs.empty())
417    return;
418  for (const auto &I : getTypesDWOSections()) {
419    DWOTUs.emplace_back();
420    DWOTUs.back().parseDWO(*this, I.second);
421  }
422}
423
424DWARFCompileUnit *DWARFContext::getCompileUnitForOffset(uint32_t Offset) {
425  parseCompileUnits();
426  return CUs.getUnitForOffset(Offset);
427}
428
429DWARFCompileUnit *DWARFContext::getCompileUnitForAddress(uint64_t Address) {
430  // First, get the offset of the compile unit.
431  uint32_t CUOffset = getDebugAranges()->findAddress(Address);
432  // Retrieve the compile unit.
433  return getCompileUnitForOffset(CUOffset);
434}
435
436static bool getFunctionNameForAddress(DWARFCompileUnit *CU, uint64_t Address,
437                                      FunctionNameKind Kind,
438                                      std::string &FunctionName) {
439  if (Kind == FunctionNameKind::None)
440    return false;
441  // The address may correspond to instruction in some inlined function,
442  // so we have to build the chain of inlined functions and take the
443  // name of the topmost function in it.
444  const DWARFDebugInfoEntryInlinedChain &InlinedChain =
445      CU->getInlinedChainForAddress(Address);
446  if (InlinedChain.DIEs.size() == 0)
447    return false;
448  const DWARFDebugInfoEntryMinimal &TopFunctionDIE = InlinedChain.DIEs[0];
449  if (const char *Name =
450          TopFunctionDIE.getSubroutineName(InlinedChain.U, Kind)) {
451    FunctionName = Name;
452    return true;
453  }
454  return false;
455}
456
457DILineInfo DWARFContext::getLineInfoForAddress(uint64_t Address,
458                                               DILineInfoSpecifier Spec) {
459  DILineInfo Result;
460
461  DWARFCompileUnit *CU = getCompileUnitForAddress(Address);
462  if (!CU)
463    return Result;
464  getFunctionNameForAddress(CU, Address, Spec.FNKind, Result.FunctionName);
465  if (Spec.FLIKind != FileLineInfoKind::None) {
466    if (const DWARFLineTable *LineTable = getLineTableForUnit(CU))
467      LineTable->getFileLineInfoForAddress(Address, CU->getCompilationDir(),
468                                           Spec.FLIKind, Result);
469  }
470  return Result;
471}
472
473DILineInfoTable
474DWARFContext::getLineInfoForAddressRange(uint64_t Address, uint64_t Size,
475                                         DILineInfoSpecifier Spec) {
476  DILineInfoTable  Lines;
477  DWARFCompileUnit *CU = getCompileUnitForAddress(Address);
478  if (!CU)
479    return Lines;
480
481  std::string FunctionName = "<invalid>";
482  getFunctionNameForAddress(CU, Address, Spec.FNKind, FunctionName);
483
484  // If the Specifier says we don't need FileLineInfo, just
485  // return the top-most function at the starting address.
486  if (Spec.FLIKind == FileLineInfoKind::None) {
487    DILineInfo Result;
488    Result.FunctionName = FunctionName;
489    Lines.push_back(std::make_pair(Address, Result));
490    return Lines;
491  }
492
493  const DWARFLineTable *LineTable = getLineTableForUnit(CU);
494
495  // Get the index of row we're looking for in the line table.
496  std::vector<uint32_t> RowVector;
497  if (!LineTable->lookupAddressRange(Address, Size, RowVector))
498    return Lines;
499
500  for (uint32_t RowIndex : RowVector) {
501    // Take file number and line/column from the row.
502    const DWARFDebugLine::Row &Row = LineTable->Rows[RowIndex];
503    DILineInfo Result;
504    LineTable->getFileNameByIndex(Row.File, CU->getCompilationDir(),
505                                  Spec.FLIKind, Result.FileName);
506    Result.FunctionName = FunctionName;
507    Result.Line = Row.Line;
508    Result.Column = Row.Column;
509    Lines.push_back(std::make_pair(Row.Address, Result));
510  }
511
512  return Lines;
513}
514
515DIInliningInfo
516DWARFContext::getInliningInfoForAddress(uint64_t Address,
517                                        DILineInfoSpecifier Spec) {
518  DIInliningInfo InliningInfo;
519
520  DWARFCompileUnit *CU = getCompileUnitForAddress(Address);
521  if (!CU)
522    return InliningInfo;
523
524  const DWARFLineTable *LineTable = nullptr;
525  const DWARFDebugInfoEntryInlinedChain &InlinedChain =
526      CU->getInlinedChainForAddress(Address);
527  if (InlinedChain.DIEs.size() == 0) {
528    // If there is no DIE for address (e.g. it is in unavailable .dwo file),
529    // try to at least get file/line info from symbol table.
530    if (Spec.FLIKind != FileLineInfoKind::None) {
531      DILineInfo Frame;
532      LineTable = getLineTableForUnit(CU);
533      if (LineTable &&
534          LineTable->getFileLineInfoForAddress(Address, CU->getCompilationDir(),
535                                               Spec.FLIKind, Frame))
536        InliningInfo.addFrame(Frame);
537    }
538    return InliningInfo;
539  }
540
541  uint32_t CallFile = 0, CallLine = 0, CallColumn = 0;
542  for (uint32_t i = 0, n = InlinedChain.DIEs.size(); i != n; i++) {
543    const DWARFDebugInfoEntryMinimal &FunctionDIE = InlinedChain.DIEs[i];
544    DILineInfo Frame;
545    // Get function name if necessary.
546    if (const char *Name =
547            FunctionDIE.getSubroutineName(InlinedChain.U, Spec.FNKind))
548      Frame.FunctionName = Name;
549    if (Spec.FLIKind != FileLineInfoKind::None) {
550      if (i == 0) {
551        // For the topmost frame, initialize the line table of this
552        // compile unit and fetch file/line info from it.
553        LineTable = getLineTableForUnit(CU);
554        // For the topmost routine, get file/line info from line table.
555        if (LineTable)
556          LineTable->getFileLineInfoForAddress(Address, CU->getCompilationDir(),
557                                               Spec.FLIKind, Frame);
558      } else {
559        // Otherwise, use call file, call line and call column from
560        // previous DIE in inlined chain.
561        if (LineTable)
562          LineTable->getFileNameByIndex(CallFile, CU->getCompilationDir(),
563                                        Spec.FLIKind, Frame.FileName);
564        Frame.Line = CallLine;
565        Frame.Column = CallColumn;
566      }
567      // Get call file/line/column of a current DIE.
568      if (i + 1 < n) {
569        FunctionDIE.getCallerFrame(InlinedChain.U, CallFile, CallLine,
570                                   CallColumn);
571      }
572    }
573    InliningInfo.addFrame(Frame);
574  }
575  return InliningInfo;
576}
577
578static bool consumeCompressedDebugSectionHeader(StringRef &data,
579                                                uint64_t &OriginalSize) {
580  // Consume "ZLIB" prefix.
581  if (!data.startswith("ZLIB"))
582    return false;
583  data = data.substr(4);
584  // Consume uncompressed section size (big-endian 8 bytes).
585  DataExtractor extractor(data, false, 8);
586  uint32_t Offset = 0;
587  OriginalSize = extractor.getU64(&Offset);
588  if (Offset == 0)
589    return false;
590  data = data.substr(Offset);
591  return true;
592}
593
594DWARFContextInMemory::DWARFContextInMemory(const object::ObjectFile &Obj,
595    const LoadedObjectInfo *L)
596    : IsLittleEndian(Obj.isLittleEndian()),
597      AddressSize(Obj.getBytesInAddress()) {
598  for (const SectionRef &Section : Obj.sections()) {
599    StringRef name;
600    Section.getName(name);
601    // Skip BSS and Virtual sections, they aren't interesting.
602    bool IsBSS = Section.isBSS();
603    if (IsBSS)
604      continue;
605    bool IsVirtual = Section.isVirtual();
606    if (IsVirtual)
607      continue;
608    StringRef data;
609
610    section_iterator RelocatedSection = Section.getRelocatedSection();
611    // Try to obtain an already relocated version of this section.
612    // Else use the unrelocated section from the object file. We'll have to
613    // apply relocations ourselves later.
614    if (!L || !L->getLoadedSectionContents(*RelocatedSection,data))
615      Section.getContents(data);
616
617    name = name.substr(name.find_first_not_of("._")); // Skip . and _ prefixes.
618
619    // Check if debug info section is compressed with zlib.
620    if (name.startswith("zdebug_")) {
621      uint64_t OriginalSize;
622      if (!zlib::isAvailable() ||
623          !consumeCompressedDebugSectionHeader(data, OriginalSize))
624        continue;
625      UncompressedSections.resize(UncompressedSections.size() + 1);
626      if (zlib::uncompress(data, UncompressedSections.back(), OriginalSize) !=
627          zlib::StatusOK) {
628        UncompressedSections.pop_back();
629        continue;
630      }
631      // Make data point to uncompressed section contents and save its contents.
632      name = name.substr(1);
633      data = UncompressedSections.back();
634    }
635
636    StringRef *SectionData =
637        StringSwitch<StringRef *>(name)
638            .Case("debug_info", &InfoSection.Data)
639            .Case("debug_abbrev", &AbbrevSection)
640            .Case("debug_loc", &LocSection.Data)
641            .Case("debug_line", &LineSection.Data)
642            .Case("debug_aranges", &ARangeSection)
643            .Case("debug_frame", &DebugFrameSection)
644            .Case("debug_str", &StringSection)
645            .Case("debug_ranges", &RangeSection)
646            .Case("debug_macinfo", &MacinfoSection)
647            .Case("debug_pubnames", &PubNamesSection)
648            .Case("debug_pubtypes", &PubTypesSection)
649            .Case("debug_gnu_pubnames", &GnuPubNamesSection)
650            .Case("debug_gnu_pubtypes", &GnuPubTypesSection)
651            .Case("debug_info.dwo", &InfoDWOSection.Data)
652            .Case("debug_abbrev.dwo", &AbbrevDWOSection)
653            .Case("debug_loc.dwo", &LocDWOSection.Data)
654            .Case("debug_line.dwo", &LineDWOSection.Data)
655            .Case("debug_str.dwo", &StringDWOSection)
656            .Case("debug_str_offsets.dwo", &StringOffsetDWOSection)
657            .Case("debug_addr", &AddrSection)
658            .Case("apple_names", &AppleNamesSection.Data)
659            .Case("apple_types", &AppleTypesSection.Data)
660            .Case("apple_namespaces", &AppleNamespacesSection.Data)
661            .Case("apple_namespac", &AppleNamespacesSection.Data)
662            .Case("apple_objc", &AppleObjCSection.Data)
663            .Case("debug_cu_index", &CUIndexSection)
664            .Case("debug_tu_index", &TUIndexSection)
665            // Any more debug info sections go here.
666            .Default(nullptr);
667    if (SectionData) {
668      *SectionData = data;
669      if (name == "debug_ranges") {
670        // FIXME: Use the other dwo range section when we emit it.
671        RangeDWOSection = data;
672      }
673    } else if (name == "debug_types") {
674      // Find debug_types data by section rather than name as there are
675      // multiple, comdat grouped, debug_types sections.
676      TypesSections[Section].Data = data;
677    } else if (name == "debug_types.dwo") {
678      TypesDWOSections[Section].Data = data;
679    }
680
681    if (RelocatedSection == Obj.section_end())
682      continue;
683
684    StringRef RelSecName;
685    StringRef RelSecData;
686    RelocatedSection->getName(RelSecName);
687
688    // If the section we're relocating was relocated already by the JIT,
689    // then we used the relocated version above, so we do not need to process
690    // relocations for it now.
691    if (L && L->getLoadedSectionContents(*RelocatedSection,RelSecData))
692      continue;
693
694    // In Mach-o files, the relocations do not need to be applied if
695    // there is no load offset to apply. The value read at the
696    // relocation point already factors in the section address
697    // (actually applying the relocations will produce wrong results
698    // as the section address will be added twice).
699    if (!L && isa<MachOObjectFile>(&Obj))
700      continue;
701
702    RelSecName = RelSecName.substr(
703        RelSecName.find_first_not_of("._")); // Skip . and _ prefixes.
704
705    // TODO: Add support for relocations in other sections as needed.
706    // Record relocations for the debug_info and debug_line sections.
707    RelocAddrMap *Map = StringSwitch<RelocAddrMap*>(RelSecName)
708        .Case("debug_info", &InfoSection.Relocs)
709        .Case("debug_loc", &LocSection.Relocs)
710        .Case("debug_info.dwo", &InfoDWOSection.Relocs)
711        .Case("debug_line", &LineSection.Relocs)
712        .Case("apple_names", &AppleNamesSection.Relocs)
713        .Case("apple_types", &AppleTypesSection.Relocs)
714        .Case("apple_namespaces", &AppleNamespacesSection.Relocs)
715        .Case("apple_namespac", &AppleNamespacesSection.Relocs)
716        .Case("apple_objc", &AppleObjCSection.Relocs)
717        .Default(nullptr);
718    if (!Map) {
719      // Find debug_types relocs by section rather than name as there are
720      // multiple, comdat grouped, debug_types sections.
721      if (RelSecName == "debug_types")
722        Map = &TypesSections[*RelocatedSection].Relocs;
723      else if (RelSecName == "debug_types.dwo")
724        Map = &TypesDWOSections[*RelocatedSection].Relocs;
725      else
726        continue;
727    }
728
729    if (Section.relocation_begin() != Section.relocation_end()) {
730      uint64_t SectionSize = RelocatedSection->getSize();
731      for (const RelocationRef &Reloc : Section.relocations()) {
732        uint64_t Address = Reloc.getOffset();
733        uint64_t Type = Reloc.getType();
734        uint64_t SymAddr = 0;
735        uint64_t SectionLoadAddress = 0;
736        object::symbol_iterator Sym = Reloc.getSymbol();
737        object::section_iterator RSec = Obj.section_end();
738
739        // First calculate the address of the symbol or section as it appears
740        // in the objct file
741        if (Sym != Obj.symbol_end()) {
742          ErrorOr<uint64_t> SymAddrOrErr = Sym->getAddress();
743          if (std::error_code EC = SymAddrOrErr.getError()) {
744            errs() << "error: failed to compute symbol address: "
745                   << EC.message() << '\n';
746            continue;
747          }
748          SymAddr = *SymAddrOrErr;
749          // Also remember what section this symbol is in for later
750          RSec = *Sym->getSection();
751        } else if (auto *MObj = dyn_cast<MachOObjectFile>(&Obj)) {
752          // MachO also has relocations that point to sections and
753          // scattered relocations.
754          auto RelocInfo = MObj->getRelocation(Reloc.getRawDataRefImpl());
755          if (MObj->isRelocationScattered(RelocInfo)) {
756            // FIXME: it's not clear how to correctly handle scattered
757            // relocations.
758            continue;
759          } else {
760            RSec = MObj->getRelocationSection(Reloc.getRawDataRefImpl());
761            SymAddr = RSec->getAddress();
762          }
763        }
764
765        // If we are given load addresses for the sections, we need to adjust:
766        // SymAddr = (Address of Symbol Or Section in File) -
767        //           (Address of Section in File) +
768        //           (Load Address of Section)
769        if (L != nullptr && RSec != Obj.section_end()) {
770          // RSec is now either the section being targeted or the section
771          // containing the symbol being targeted. In either case,
772          // we need to perform the same computation.
773          StringRef SecName;
774          RSec->getName(SecName);
775//           llvm::dbgs() << "Name: '" << SecName
776//                        << "', RSec: " << RSec->getRawDataRefImpl()
777//                        << ", Section: " << Section.getRawDataRefImpl() << "\n";
778          SectionLoadAddress = L->getSectionLoadAddress(*RSec);
779          if (SectionLoadAddress != 0)
780            SymAddr += SectionLoadAddress - RSec->getAddress();
781        }
782
783        object::RelocVisitor V(Obj);
784        object::RelocToApply R(V.visit(Type, Reloc, SymAddr));
785        if (V.error()) {
786          SmallString<32> Name;
787          Reloc.getTypeName(Name);
788          errs() << "error: failed to compute relocation: "
789                 << Name << "\n";
790          continue;
791        }
792
793        if (Address + R.Width > SectionSize) {
794          errs() << "error: " << R.Width << "-byte relocation starting "
795                 << Address << " bytes into section " << name << " which is "
796                 << SectionSize << " bytes long.\n";
797          continue;
798        }
799        if (R.Width > 8) {
800          errs() << "error: can't handle a relocation of more than 8 bytes at "
801                    "a time.\n";
802          continue;
803        }
804        DEBUG(dbgs() << "Writing " << format("%p", R.Value)
805                     << " at " << format("%p", Address)
806                     << " with width " << format("%d", R.Width)
807                     << "\n");
808        Map->insert(std::make_pair(Address, std::make_pair(R.Width, R.Value)));
809      }
810    }
811  }
812}
813
814void DWARFContextInMemory::anchor() { }
815