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/DWARFDebugPubTable.h"
16 #include "llvm/DebugInfo/DWARF/DWARFUnitIndex.h"
17 #include "llvm/Object/Decompressor.h"
18 #include "llvm/Object/MachO.h"
19 #include "llvm/Object/RelocVisitor.h"
20 #include "llvm/Support/Compression.h"
21 #include "llvm/Support/Dwarf.h"
22 #include "llvm/Support/ELF.h"
23 #include "llvm/Support/Format.h"
24 #include "llvm/Support/Path.h"
25 #include "llvm/Support/raw_ostream.h"
26 #include <algorithm>
27 using namespace llvm;
28 using namespace dwarf;
29 using namespace object;
30 
31 #define DEBUG_TYPE "dwarf"
32 
33 typedef DWARFDebugLine::LineTable DWARFLineTable;
34 typedef DILineInfoSpecifier::FileLineInfoKind FileLineInfoKind;
35 typedef DILineInfoSpecifier::FunctionNameKind FunctionNameKind;
36 
37 static void dumpAccelSection(raw_ostream &OS, StringRef Name,
38                              const DWARFSection& Section, StringRef StringSection,
39                              bool LittleEndian) {
40   DataExtractor AccelSection(Section.Data, LittleEndian, 0);
41   DataExtractor StrData(StringSection, LittleEndian, 0);
42   OS << "\n." << Name << " contents:\n";
43   DWARFAcceleratorTable Accel(AccelSection, StrData, Section.Relocs);
44   if (!Accel.extract())
45     return;
46   Accel.dump(OS);
47 }
48 
49 void DWARFContext::dump(raw_ostream &OS, DIDumpType DumpType, bool DumpEH,
50                         bool SummarizeTypes) {
51   if (DumpType == DIDT_All || DumpType == DIDT_Abbrev) {
52     OS << ".debug_abbrev contents:\n";
53     getDebugAbbrev()->dump(OS);
54   }
55 
56   if (DumpType == DIDT_All || DumpType == DIDT_AbbrevDwo)
57     if (const DWARFDebugAbbrev *D = getDebugAbbrevDWO()) {
58       OS << "\n.debug_abbrev.dwo contents:\n";
59       D->dump(OS);
60     }
61 
62   if (DumpType == DIDT_All || DumpType == DIDT_Info) {
63     OS << "\n.debug_info contents:\n";
64     for (const auto &CU : compile_units())
65       CU->dump(OS);
66   }
67 
68   if ((DumpType == DIDT_All || DumpType == DIDT_InfoDwo) &&
69       getNumDWOCompileUnits()) {
70     OS << "\n.debug_info.dwo contents:\n";
71     for (const auto &DWOCU : dwo_compile_units())
72       DWOCU->dump(OS);
73   }
74 
75   if ((DumpType == DIDT_All || DumpType == DIDT_Types) && getNumTypeUnits()) {
76     OS << "\n.debug_types contents:\n";
77     for (const auto &TUS : type_unit_sections())
78       for (const auto &TU : TUS)
79         TU->dump(OS, SummarizeTypes);
80   }
81 
82   if ((DumpType == DIDT_All || DumpType == DIDT_TypesDwo) &&
83       getNumDWOTypeUnits()) {
84     OS << "\n.debug_types.dwo contents:\n";
85     for (const auto &DWOTUS : dwo_type_unit_sections())
86       for (const auto &DWOTU : DWOTUS)
87         DWOTU->dump(OS, SummarizeTypes);
88   }
89 
90   if (DumpType == DIDT_All || DumpType == DIDT_Loc) {
91     OS << "\n.debug_loc contents:\n";
92     getDebugLoc()->dump(OS);
93   }
94 
95   if (DumpType == DIDT_All || DumpType == DIDT_LocDwo) {
96     OS << "\n.debug_loc.dwo contents:\n";
97     getDebugLocDWO()->dump(OS);
98   }
99 
100   if (DumpType == DIDT_All || DumpType == DIDT_Frames) {
101     OS << "\n.debug_frame contents:\n";
102     getDebugFrame()->dump(OS);
103     if (DumpEH) {
104       OS << "\n.eh_frame contents:\n";
105       getEHFrame()->dump(OS);
106     }
107   }
108 
109   if (DumpType == DIDT_All || DumpType == DIDT_Macro) {
110     OS << "\n.debug_macinfo contents:\n";
111     getDebugMacro()->dump(OS);
112   }
113 
114   uint32_t offset = 0;
115   if (DumpType == DIDT_All || DumpType == DIDT_Aranges) {
116     OS << "\n.debug_aranges contents:\n";
117     DataExtractor arangesData(getARangeSection(), isLittleEndian(), 0);
118     DWARFDebugArangeSet set;
119     while (set.extract(arangesData, &offset))
120       set.dump(OS);
121   }
122 
123   uint8_t savedAddressByteSize = 0;
124   if (DumpType == DIDT_All || DumpType == DIDT_Line) {
125     OS << "\n.debug_line contents:\n";
126     for (const auto &CU : compile_units()) {
127       savedAddressByteSize = CU->getAddressByteSize();
128       auto CUDIE = CU->getUnitDIE();
129       if (!CUDIE)
130         continue;
131       if (auto StmtOffset =
132               CUDIE.getAttributeValueAsSectionOffset(DW_AT_stmt_list)) {
133         DataExtractor lineData(getLineSection().Data, isLittleEndian(),
134                                savedAddressByteSize);
135         DWARFDebugLine::LineTable LineTable;
136         uint32_t Offset = *StmtOffset;
137         LineTable.parse(lineData, &getLineSection().Relocs, &Offset);
138         LineTable.dump(OS);
139       }
140     }
141   }
142 
143   if (DumpType == DIDT_All || DumpType == DIDT_CUIndex) {
144     OS << "\n.debug_cu_index contents:\n";
145     getCUIndex().dump(OS);
146   }
147 
148   if (DumpType == DIDT_All || DumpType == DIDT_TUIndex) {
149     OS << "\n.debug_tu_index contents:\n";
150     getTUIndex().dump(OS);
151   }
152 
153   if (DumpType == DIDT_All || DumpType == DIDT_LineDwo) {
154     OS << "\n.debug_line.dwo contents:\n";
155     unsigned stmtOffset = 0;
156     DataExtractor lineData(getLineDWOSection().Data, isLittleEndian(),
157                            savedAddressByteSize);
158     DWARFDebugLine::LineTable LineTable;
159     while (LineTable.Prologue.parse(lineData, &stmtOffset)) {
160       LineTable.dump(OS);
161       LineTable.clear();
162     }
163   }
164 
165   if (DumpType == DIDT_All || DumpType == DIDT_Str) {
166     OS << "\n.debug_str contents:\n";
167     DataExtractor strData(getStringSection(), isLittleEndian(), 0);
168     offset = 0;
169     uint32_t strOffset = 0;
170     while (const char *s = strData.getCStr(&offset)) {
171       OS << format("0x%8.8x: \"%s\"\n", strOffset, s);
172       strOffset = offset;
173     }
174   }
175 
176   if ((DumpType == DIDT_All || DumpType == DIDT_StrDwo) &&
177       !getStringDWOSection().empty()) {
178     OS << "\n.debug_str.dwo contents:\n";
179     DataExtractor strDWOData(getStringDWOSection(), isLittleEndian(), 0);
180     offset = 0;
181     uint32_t strDWOOffset = 0;
182     while (const char *s = strDWOData.getCStr(&offset)) {
183       OS << format("0x%8.8x: \"%s\"\n", strDWOOffset, s);
184       strDWOOffset = offset;
185     }
186   }
187 
188   if (DumpType == DIDT_All || DumpType == DIDT_Ranges) {
189     OS << "\n.debug_ranges contents:\n";
190     // In fact, different compile units may have different address byte
191     // sizes, but for simplicity we just use the address byte size of the last
192     // compile unit (there is no easy and fast way to associate address range
193     // list and the compile unit it describes).
194     DataExtractor rangesData(getRangeSection(), isLittleEndian(),
195                              savedAddressByteSize);
196     offset = 0;
197     DWARFDebugRangeList rangeList;
198     while (rangeList.extract(rangesData, &offset))
199       rangeList.dump(OS);
200   }
201 
202   if (DumpType == DIDT_All || DumpType == DIDT_Pubnames)
203     DWARFDebugPubTable(getPubNamesSection(), isLittleEndian(), false)
204         .dump("debug_pubnames", OS);
205 
206   if (DumpType == DIDT_All || DumpType == DIDT_Pubtypes)
207     DWARFDebugPubTable(getPubTypesSection(), isLittleEndian(), false)
208         .dump("debug_pubtypes", OS);
209 
210   if (DumpType == DIDT_All || DumpType == DIDT_GnuPubnames)
211     DWARFDebugPubTable(getGnuPubNamesSection(), isLittleEndian(),
212                        true /* GnuStyle */)
213         .dump("debug_gnu_pubnames", OS);
214 
215   if (DumpType == DIDT_All || DumpType == DIDT_GnuPubtypes)
216     DWARFDebugPubTable(getGnuPubTypesSection(), isLittleEndian(),
217                        true /* GnuStyle */)
218         .dump("debug_gnu_pubtypes", OS);
219 
220   if ((DumpType == DIDT_All || DumpType == DIDT_StrOffsetsDwo) &&
221       !getStringOffsetDWOSection().empty()) {
222     OS << "\n.debug_str_offsets.dwo contents:\n";
223     DataExtractor strOffsetExt(getStringOffsetDWOSection(), isLittleEndian(),
224                                0);
225     offset = 0;
226     uint64_t size = getStringOffsetDWOSection().size();
227     while (offset < size) {
228       OS << format("0x%8.8x: ", offset);
229       OS << format("%8.8x\n", strOffsetExt.getU32(&offset));
230     }
231   }
232 
233   if ((DumpType == DIDT_All || DumpType == DIDT_GdbIndex) &&
234       !getGdbIndexSection().empty()) {
235     OS << "\n.gnu_index contents:\n";
236     getGdbIndex().dump(OS);
237   }
238 
239   if (DumpType == DIDT_All || DumpType == DIDT_AppleNames)
240     dumpAccelSection(OS, "apple_names", getAppleNamesSection(),
241                      getStringSection(), isLittleEndian());
242 
243   if (DumpType == DIDT_All || DumpType == DIDT_AppleTypes)
244     dumpAccelSection(OS, "apple_types", getAppleTypesSection(),
245                      getStringSection(), isLittleEndian());
246 
247   if (DumpType == DIDT_All || DumpType == DIDT_AppleNamespaces)
248     dumpAccelSection(OS, "apple_namespaces", getAppleNamespacesSection(),
249                      getStringSection(), isLittleEndian());
250 
251   if (DumpType == DIDT_All || DumpType == DIDT_AppleObjC)
252     dumpAccelSection(OS, "apple_objc", getAppleObjCSection(),
253                      getStringSection(), isLittleEndian());
254 }
255 
256 const DWARFUnitIndex &DWARFContext::getCUIndex() {
257   if (CUIndex)
258     return *CUIndex;
259 
260   DataExtractor CUIndexData(getCUIndexSection(), isLittleEndian(), 0);
261 
262   CUIndex = llvm::make_unique<DWARFUnitIndex>(DW_SECT_INFO);
263   CUIndex->parse(CUIndexData);
264   return *CUIndex;
265 }
266 
267 const DWARFUnitIndex &DWARFContext::getTUIndex() {
268   if (TUIndex)
269     return *TUIndex;
270 
271   DataExtractor TUIndexData(getTUIndexSection(), isLittleEndian(), 0);
272 
273   TUIndex = llvm::make_unique<DWARFUnitIndex>(DW_SECT_TYPES);
274   TUIndex->parse(TUIndexData);
275   return *TUIndex;
276 }
277 
278 DWARFGdbIndex &DWARFContext::getGdbIndex() {
279   if (GdbIndex)
280     return *GdbIndex;
281 
282   DataExtractor GdbIndexData(getGdbIndexSection(), true /*LE*/, 0);
283   GdbIndex = llvm::make_unique<DWARFGdbIndex>();
284   GdbIndex->parse(GdbIndexData);
285   return *GdbIndex;
286 }
287 
288 const DWARFDebugAbbrev *DWARFContext::getDebugAbbrev() {
289   if (Abbrev)
290     return Abbrev.get();
291 
292   DataExtractor abbrData(getAbbrevSection(), isLittleEndian(), 0);
293 
294   Abbrev.reset(new DWARFDebugAbbrev());
295   Abbrev->extract(abbrData);
296   return Abbrev.get();
297 }
298 
299 const DWARFDebugAbbrev *DWARFContext::getDebugAbbrevDWO() {
300   if (AbbrevDWO)
301     return AbbrevDWO.get();
302 
303   DataExtractor abbrData(getAbbrevDWOSection(), isLittleEndian(), 0);
304   AbbrevDWO.reset(new DWARFDebugAbbrev());
305   AbbrevDWO->extract(abbrData);
306   return AbbrevDWO.get();
307 }
308 
309 const DWARFDebugLoc *DWARFContext::getDebugLoc() {
310   if (Loc)
311     return Loc.get();
312 
313   DataExtractor LocData(getLocSection().Data, isLittleEndian(), 0);
314   Loc.reset(new DWARFDebugLoc(getLocSection().Relocs));
315   // assume all compile units have the same address byte size
316   if (getNumCompileUnits())
317     Loc->parse(LocData, getCompileUnitAtIndex(0)->getAddressByteSize());
318   return Loc.get();
319 }
320 
321 const DWARFDebugLocDWO *DWARFContext::getDebugLocDWO() {
322   if (LocDWO)
323     return LocDWO.get();
324 
325   DataExtractor LocData(getLocDWOSection().Data, isLittleEndian(), 0);
326   LocDWO.reset(new DWARFDebugLocDWO());
327   LocDWO->parse(LocData);
328   return LocDWO.get();
329 }
330 
331 const DWARFDebugAranges *DWARFContext::getDebugAranges() {
332   if (Aranges)
333     return Aranges.get();
334 
335   Aranges.reset(new DWARFDebugAranges());
336   Aranges->generate(this);
337   return Aranges.get();
338 }
339 
340 const DWARFDebugFrame *DWARFContext::getDebugFrame() {
341   if (DebugFrame)
342     return DebugFrame.get();
343 
344   // There's a "bug" in the DWARFv3 standard with respect to the target address
345   // size within debug frame sections. While DWARF is supposed to be independent
346   // of its container, FDEs have fields with size being "target address size",
347   // which isn't specified in DWARF in general. It's only specified for CUs, but
348   // .eh_frame can appear without a .debug_info section. Follow the example of
349   // other tools (libdwarf) and extract this from the container (ObjectFile
350   // provides this information). This problem is fixed in DWARFv4
351   // See this dwarf-discuss discussion for more details:
352   // http://lists.dwarfstd.org/htdig.cgi/dwarf-discuss-dwarfstd.org/2011-December/001173.html
353   DataExtractor debugFrameData(getDebugFrameSection(), isLittleEndian(),
354                                getAddressSize());
355   DebugFrame.reset(new DWARFDebugFrame(false /* IsEH */));
356   DebugFrame->parse(debugFrameData);
357   return DebugFrame.get();
358 }
359 
360 const DWARFDebugFrame *DWARFContext::getEHFrame() {
361   if (EHFrame)
362     return EHFrame.get();
363 
364   DataExtractor debugFrameData(getEHFrameSection(), isLittleEndian(),
365                                getAddressSize());
366   DebugFrame.reset(new DWARFDebugFrame(true /* IsEH */));
367   DebugFrame->parse(debugFrameData);
368   return DebugFrame.get();
369 }
370 
371 const DWARFDebugMacro *DWARFContext::getDebugMacro() {
372   if (Macro)
373     return Macro.get();
374 
375   DataExtractor MacinfoData(getMacinfoSection(), isLittleEndian(), 0);
376   Macro.reset(new DWARFDebugMacro());
377   Macro->parse(MacinfoData);
378   return Macro.get();
379 }
380 
381 const DWARFLineTable *
382 DWARFContext::getLineTableForUnit(DWARFUnit *U) {
383   if (!Line)
384     Line.reset(new DWARFDebugLine(&getLineSection().Relocs));
385 
386   auto UnitDIE = U->getUnitDIE();
387   if (!UnitDIE)
388     return nullptr;
389 
390   auto Offset = UnitDIE.getAttributeValueAsSectionOffset(DW_AT_stmt_list);
391   if (!Offset)
392     return nullptr; // No line table for this compile unit.
393 
394   uint32_t stmtOffset = *Offset + U->getLineTableOffset();
395   // See if the line table is cached.
396   if (const DWARFLineTable *lt = Line->getLineTable(stmtOffset))
397     return lt;
398 
399   // We have to parse it first.
400   DataExtractor lineData(U->getLineSection(), isLittleEndian(),
401                          U->getAddressByteSize());
402   return Line->getOrParseLineTable(lineData, stmtOffset);
403 }
404 
405 void DWARFContext::parseCompileUnits() {
406   CUs.parse(*this, getInfoSection());
407 }
408 
409 void DWARFContext::parseTypeUnits() {
410   if (!TUs.empty())
411     return;
412   for (const auto &I : getTypesSections()) {
413     TUs.emplace_back();
414     TUs.back().parse(*this, I.second);
415   }
416 }
417 
418 void DWARFContext::parseDWOCompileUnits() {
419   DWOCUs.parseDWO(*this, getInfoDWOSection());
420 }
421 
422 void DWARFContext::parseDWOTypeUnits() {
423   if (!DWOTUs.empty())
424     return;
425   for (const auto &I : getTypesDWOSections()) {
426     DWOTUs.emplace_back();
427     DWOTUs.back().parseDWO(*this, I.second);
428   }
429 }
430 
431 DWARFCompileUnit *DWARFContext::getCompileUnitForOffset(uint32_t Offset) {
432   parseCompileUnits();
433   return CUs.getUnitForOffset(Offset);
434 }
435 
436 DWARFCompileUnit *DWARFContext::getCompileUnitForAddress(uint64_t Address) {
437   // First, get the offset of the compile unit.
438   uint32_t CUOffset = getDebugAranges()->findAddress(Address);
439   // Retrieve the compile unit.
440   return getCompileUnitForOffset(CUOffset);
441 }
442 
443 static bool getFunctionNameForAddress(DWARFCompileUnit *CU, uint64_t Address,
444                                       FunctionNameKind Kind,
445                                       std::string &FunctionName) {
446   if (Kind == FunctionNameKind::None)
447     return false;
448   // The address may correspond to instruction in some inlined function,
449   // so we have to build the chain of inlined functions and take the
450   // name of the topmost function in it.SmallVectorImpl<DWARFDie> &InlinedChain
451   SmallVector<DWARFDie, 4> InlinedChain;
452   CU->getInlinedChainForAddress(Address, InlinedChain);
453   if (InlinedChain.size() == 0)
454     return false;
455   if (const char *Name = InlinedChain[0].getSubroutineName(Kind)) {
456     FunctionName = Name;
457     return true;
458   }
459   return false;
460 }
461 
462 DILineInfo DWARFContext::getLineInfoForAddress(uint64_t Address,
463                                                DILineInfoSpecifier Spec) {
464   DILineInfo Result;
465 
466   DWARFCompileUnit *CU = getCompileUnitForAddress(Address);
467   if (!CU)
468     return Result;
469   getFunctionNameForAddress(CU, Address, Spec.FNKind, Result.FunctionName);
470   if (Spec.FLIKind != FileLineInfoKind::None) {
471     if (const DWARFLineTable *LineTable = getLineTableForUnit(CU))
472       LineTable->getFileLineInfoForAddress(Address, CU->getCompilationDir(),
473                                            Spec.FLIKind, Result);
474   }
475   return Result;
476 }
477 
478 DILineInfoTable
479 DWARFContext::getLineInfoForAddressRange(uint64_t Address, uint64_t Size,
480                                          DILineInfoSpecifier Spec) {
481   DILineInfoTable  Lines;
482   DWARFCompileUnit *CU = getCompileUnitForAddress(Address);
483   if (!CU)
484     return Lines;
485 
486   std::string FunctionName = "<invalid>";
487   getFunctionNameForAddress(CU, Address, Spec.FNKind, FunctionName);
488 
489   // If the Specifier says we don't need FileLineInfo, just
490   // return the top-most function at the starting address.
491   if (Spec.FLIKind == FileLineInfoKind::None) {
492     DILineInfo Result;
493     Result.FunctionName = FunctionName;
494     Lines.push_back(std::make_pair(Address, Result));
495     return Lines;
496   }
497 
498   const DWARFLineTable *LineTable = getLineTableForUnit(CU);
499 
500   // Get the index of row we're looking for in the line table.
501   std::vector<uint32_t> RowVector;
502   if (!LineTable->lookupAddressRange(Address, Size, RowVector))
503     return Lines;
504 
505   for (uint32_t RowIndex : RowVector) {
506     // Take file number and line/column from the row.
507     const DWARFDebugLine::Row &Row = LineTable->Rows[RowIndex];
508     DILineInfo Result;
509     LineTable->getFileNameByIndex(Row.File, CU->getCompilationDir(),
510                                   Spec.FLIKind, Result.FileName);
511     Result.FunctionName = FunctionName;
512     Result.Line = Row.Line;
513     Result.Column = Row.Column;
514     Lines.push_back(std::make_pair(Row.Address, Result));
515   }
516 
517   return Lines;
518 }
519 
520 DIInliningInfo
521 DWARFContext::getInliningInfoForAddress(uint64_t Address,
522                                         DILineInfoSpecifier Spec) {
523   DIInliningInfo InliningInfo;
524 
525   DWARFCompileUnit *CU = getCompileUnitForAddress(Address);
526   if (!CU)
527     return InliningInfo;
528 
529   const DWARFLineTable *LineTable = nullptr;
530   SmallVector<DWARFDie, 4> InlinedChain;
531   CU->getInlinedChainForAddress(Address, InlinedChain);
532   if (InlinedChain.size() == 0) {
533     // If there is no DIE for address (e.g. it is in unavailable .dwo file),
534     // try to at least get file/line info from symbol table.
535     if (Spec.FLIKind != FileLineInfoKind::None) {
536       DILineInfo Frame;
537       LineTable = getLineTableForUnit(CU);
538       if (LineTable &&
539           LineTable->getFileLineInfoForAddress(Address, CU->getCompilationDir(),
540                                                Spec.FLIKind, Frame))
541         InliningInfo.addFrame(Frame);
542     }
543     return InliningInfo;
544   }
545 
546   uint32_t CallFile = 0, CallLine = 0, CallColumn = 0;
547   for (uint32_t i = 0, n = InlinedChain.size(); i != n; i++) {
548     DWARFDie &FunctionDIE = InlinedChain[i];
549     DILineInfo Frame;
550     // Get function name if necessary.
551     if (const char *Name = FunctionDIE.getSubroutineName(Spec.FNKind))
552       Frame.FunctionName = Name;
553     if (Spec.FLIKind != FileLineInfoKind::None) {
554       if (i == 0) {
555         // For the topmost frame, initialize the line table of this
556         // compile unit and fetch file/line info from it.
557         LineTable = getLineTableForUnit(CU);
558         // For the topmost routine, get file/line info from line table.
559         if (LineTable)
560           LineTable->getFileLineInfoForAddress(Address, CU->getCompilationDir(),
561                                                Spec.FLIKind, Frame);
562       } else {
563         // Otherwise, use call file, call line and call column from
564         // previous DIE in inlined chain.
565         if (LineTable)
566           LineTable->getFileNameByIndex(CallFile, CU->getCompilationDir(),
567                                         Spec.FLIKind, Frame.FileName);
568         Frame.Line = CallLine;
569         Frame.Column = CallColumn;
570       }
571       // Get call file/line/column of a current DIE.
572       if (i + 1 < n) {
573         FunctionDIE.getCallerFrame(CallFile, CallLine, CallColumn);
574       }
575     }
576     InliningInfo.addFrame(Frame);
577   }
578   return InliningInfo;
579 }
580 
581 DWARFContextInMemory::DWARFContextInMemory(const object::ObjectFile &Obj,
582     const LoadedObjectInfo *L)
583     : IsLittleEndian(Obj.isLittleEndian()),
584       AddressSize(Obj.getBytesInAddress()) {
585   for (const SectionRef &Section : Obj.sections()) {
586     StringRef name;
587     Section.getName(name);
588     // Skip BSS and Virtual sections, they aren't interesting.
589     bool IsBSS = Section.isBSS();
590     if (IsBSS)
591       continue;
592     bool IsVirtual = Section.isVirtual();
593     if (IsVirtual)
594       continue;
595     StringRef data;
596 
597     section_iterator RelocatedSection = Section.getRelocatedSection();
598     // Try to obtain an already relocated version of this section.
599     // Else use the unrelocated section from the object file. We'll have to
600     // apply relocations ourselves later.
601     if (!L || !L->getLoadedSectionContents(*RelocatedSection,data))
602       Section.getContents(data);
603 
604     if (Decompressor::isCompressed(Section)) {
605       Expected<Decompressor> Decompressor =
606           Decompressor::create(name, data, IsLittleEndian, AddressSize == 8);
607       if (!Decompressor)
608         continue;
609       SmallString<32> Out;
610       if (auto Err = Decompressor->decompress(Out))
611         continue;
612       UncompressedSections.emplace_back(std::move(Out));
613       data = UncompressedSections.back();
614     }
615 
616     // Compressed sections names in GNU style starts from ".z",
617     // at this point section is decompressed and we drop compression prefix.
618     name = name.substr(
619         name.find_first_not_of("._z")); // Skip ".", "z" and "_" prefixes.
620 
621     StringRef *SectionData =
622         StringSwitch<StringRef *>(name)
623             .Case("debug_info", &InfoSection.Data)
624             .Case("debug_abbrev", &AbbrevSection)
625             .Case("debug_loc", &LocSection.Data)
626             .Case("debug_line", &LineSection.Data)
627             .Case("debug_aranges", &ARangeSection)
628             .Case("debug_frame", &DebugFrameSection)
629             .Case("eh_frame", &EHFrameSection)
630             .Case("debug_str", &StringSection)
631             .Case("debug_ranges", &RangeSection)
632             .Case("debug_macinfo", &MacinfoSection)
633             .Case("debug_pubnames", &PubNamesSection)
634             .Case("debug_pubtypes", &PubTypesSection)
635             .Case("debug_gnu_pubnames", &GnuPubNamesSection)
636             .Case("debug_gnu_pubtypes", &GnuPubTypesSection)
637             .Case("debug_info.dwo", &InfoDWOSection.Data)
638             .Case("debug_abbrev.dwo", &AbbrevDWOSection)
639             .Case("debug_loc.dwo", &LocDWOSection.Data)
640             .Case("debug_line.dwo", &LineDWOSection.Data)
641             .Case("debug_str.dwo", &StringDWOSection)
642             .Case("debug_str_offsets.dwo", &StringOffsetDWOSection)
643             .Case("debug_addr", &AddrSection)
644             .Case("apple_names", &AppleNamesSection.Data)
645             .Case("apple_types", &AppleTypesSection.Data)
646             .Case("apple_namespaces", &AppleNamespacesSection.Data)
647             .Case("apple_namespac", &AppleNamespacesSection.Data)
648             .Case("apple_objc", &AppleObjCSection.Data)
649             .Case("debug_cu_index", &CUIndexSection)
650             .Case("debug_tu_index", &TUIndexSection)
651             .Case("gdb_index", &GdbIndexSection)
652             // Any more debug info sections go here.
653             .Default(nullptr);
654     if (SectionData) {
655       *SectionData = data;
656       if (name == "debug_ranges") {
657         // FIXME: Use the other dwo range section when we emit it.
658         RangeDWOSection = data;
659       }
660     } else if (name == "debug_types") {
661       // Find debug_types data by section rather than name as there are
662       // multiple, comdat grouped, debug_types sections.
663       TypesSections[Section].Data = data;
664     } else if (name == "debug_types.dwo") {
665       TypesDWOSections[Section].Data = data;
666     }
667 
668     if (RelocatedSection == Obj.section_end())
669       continue;
670 
671     StringRef RelSecName;
672     StringRef RelSecData;
673     RelocatedSection->getName(RelSecName);
674 
675     // If the section we're relocating was relocated already by the JIT,
676     // then we used the relocated version above, so we do not need to process
677     // relocations for it now.
678     if (L && L->getLoadedSectionContents(*RelocatedSection,RelSecData))
679       continue;
680 
681     // In Mach-o files, the relocations do not need to be applied if
682     // there is no load offset to apply. The value read at the
683     // relocation point already factors in the section address
684     // (actually applying the relocations will produce wrong results
685     // as the section address will be added twice).
686     if (!L && isa<MachOObjectFile>(&Obj))
687       continue;
688 
689     RelSecName = RelSecName.substr(
690         RelSecName.find_first_not_of("._")); // Skip . and _ prefixes.
691 
692     // TODO: Add support for relocations in other sections as needed.
693     // Record relocations for the debug_info and debug_line sections.
694     RelocAddrMap *Map = StringSwitch<RelocAddrMap*>(RelSecName)
695         .Case("debug_info", &InfoSection.Relocs)
696         .Case("debug_loc", &LocSection.Relocs)
697         .Case("debug_info.dwo", &InfoDWOSection.Relocs)
698         .Case("debug_line", &LineSection.Relocs)
699         .Case("apple_names", &AppleNamesSection.Relocs)
700         .Case("apple_types", &AppleTypesSection.Relocs)
701         .Case("apple_namespaces", &AppleNamespacesSection.Relocs)
702         .Case("apple_namespac", &AppleNamespacesSection.Relocs)
703         .Case("apple_objc", &AppleObjCSection.Relocs)
704         .Default(nullptr);
705     if (!Map) {
706       // Find debug_types relocs by section rather than name as there are
707       // multiple, comdat grouped, debug_types sections.
708       if (RelSecName == "debug_types")
709         Map = &TypesSections[*RelocatedSection].Relocs;
710       else if (RelSecName == "debug_types.dwo")
711         Map = &TypesDWOSections[*RelocatedSection].Relocs;
712       else
713         continue;
714     }
715 
716     if (Section.relocation_begin() != Section.relocation_end()) {
717       uint64_t SectionSize = RelocatedSection->getSize();
718       for (const RelocationRef &Reloc : Section.relocations()) {
719         uint64_t Address = Reloc.getOffset();
720         uint64_t Type = Reloc.getType();
721         uint64_t SymAddr = 0;
722         uint64_t SectionLoadAddress = 0;
723         object::symbol_iterator Sym = Reloc.getSymbol();
724         object::section_iterator RSec = Obj.section_end();
725 
726         // First calculate the address of the symbol or section as it appears
727         // in the objct file
728         if (Sym != Obj.symbol_end()) {
729           Expected<uint64_t> SymAddrOrErr = Sym->getAddress();
730           if (!SymAddrOrErr) {
731             std::string Buf;
732             raw_string_ostream OS(Buf);
733             logAllUnhandledErrors(SymAddrOrErr.takeError(), OS, "");
734             OS.flush();
735             errs() << "error: failed to compute symbol address: "
736                    << Buf << '\n';
737             continue;
738           }
739           SymAddr = *SymAddrOrErr;
740           // Also remember what section this symbol is in for later
741           auto SectOrErr = Sym->getSection();
742           if (!SectOrErr) {
743             std::string Buf;
744             raw_string_ostream OS(Buf);
745             logAllUnhandledErrors(SectOrErr.takeError(), OS, "");
746             OS.flush();
747             errs() << "error: failed to get symbol section: "
748                    << Buf << '\n';
749             continue;
750           }
751           RSec = *SectOrErr;
752         } else if (auto *MObj = dyn_cast<MachOObjectFile>(&Obj)) {
753           // MachO also has relocations that point to sections and
754           // scattered relocations.
755           auto RelocInfo = MObj->getRelocation(Reloc.getRawDataRefImpl());
756           if (MObj->isRelocationScattered(RelocInfo)) {
757             // FIXME: it's not clear how to correctly handle scattered
758             // relocations.
759             continue;
760           } else {
761             RSec = MObj->getRelocationSection(Reloc.getRawDataRefImpl());
762             SymAddr = RSec->getAddress();
763           }
764         }
765 
766         // If we are given load addresses for the sections, we need to adjust:
767         // SymAddr = (Address of Symbol Or Section in File) -
768         //           (Address of Section in File) +
769         //           (Load Address of Section)
770         if (L != nullptr && RSec != Obj.section_end()) {
771           // RSec is now either the section being targeted or the section
772           // containing the symbol being targeted. In either case,
773           // we need to perform the same computation.
774           StringRef SecName;
775           RSec->getName(SecName);
776 //           llvm::dbgs() << "Name: '" << SecName
777 //                        << "', RSec: " << RSec->getRawDataRefImpl()
778 //                        << ", Section: " << Section.getRawDataRefImpl() << "\n";
779           SectionLoadAddress = L->getSectionLoadAddress(*RSec);
780           if (SectionLoadAddress != 0)
781             SymAddr += SectionLoadAddress - RSec->getAddress();
782         }
783 
784         object::RelocVisitor V(Obj);
785         object::RelocToApply R(V.visit(Type, Reloc, SymAddr));
786         if (V.error()) {
787           SmallString<32> Name;
788           Reloc.getTypeName(Name);
789           errs() << "error: failed to compute relocation: "
790                  << Name << "\n";
791           continue;
792         }
793 
794         if (Address + R.Width > SectionSize) {
795           errs() << "error: " << R.Width << "-byte relocation starting "
796                  << Address << " bytes into section " << name << " which is "
797                  << SectionSize << " bytes long.\n";
798           continue;
799         }
800         if (R.Width > 8) {
801           errs() << "error: can't handle a relocation of more than 8 bytes at "
802                     "a time.\n";
803           continue;
804         }
805         DEBUG(dbgs() << "Writing " << format("%p", R.Value)
806                      << " at " << format("%p", Address)
807                      << " with width " << format("%d", R.Width)
808                      << "\n");
809         Map->insert(std::make_pair(Address, std::make_pair(R.Width, R.Value)));
810       }
811     }
812   }
813 }
814 
815 void DWARFContextInMemory::anchor() { }
816