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