1 //===--- lib/CodeGen/DIE.cpp - DWARF Info Entries -------------------------===//
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 // Data structures for DWARF info entries.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "llvm/CodeGen/DIE.h"
15 #include "DwarfCompileUnit.h"
16 #include "DwarfDebug.h"
17 #include "DwarfUnit.h"
18 #include "llvm/ADT/Twine.h"
19 #include "llvm/CodeGen/AsmPrinter.h"
20 #include "llvm/IR/DataLayout.h"
21 #include "llvm/MC/MCAsmInfo.h"
22 #include "llvm/MC/MCContext.h"
23 #include "llvm/MC/MCStreamer.h"
24 #include "llvm/MC/MCSymbol.h"
25 #include "llvm/Support/Debug.h"
26 #include "llvm/Support/ErrorHandling.h"
27 #include "llvm/Support/Format.h"
28 #include "llvm/Support/FormattedStream.h"
29 #include "llvm/Support/LEB128.h"
30 #include "llvm/Support/MD5.h"
31 #include "llvm/Support/raw_ostream.h"
32 using namespace llvm;
33 
34 #define DEBUG_TYPE "dwarfdebug"
35 
36 //===----------------------------------------------------------------------===//
37 // DIEAbbrevData Implementation
38 //===----------------------------------------------------------------------===//
39 
40 /// Profile - Used to gather unique data for the abbreviation folding set.
41 ///
42 void DIEAbbrevData::Profile(FoldingSetNodeID &ID) const {
43   // Explicitly cast to an integer type for which FoldingSetNodeID has
44   // overloads.  Otherwise MSVC 2010 thinks this call is ambiguous.
45   ID.AddInteger(unsigned(Attribute));
46   ID.AddInteger(unsigned(Form));
47   if (Form == dwarf::DW_FORM_implicit_const)
48     ID.AddInteger(Value);
49 }
50 
51 //===----------------------------------------------------------------------===//
52 // DIEAbbrev Implementation
53 //===----------------------------------------------------------------------===//
54 
55 /// Profile - Used to gather unique data for the abbreviation folding set.
56 ///
57 void DIEAbbrev::Profile(FoldingSetNodeID &ID) const {
58   ID.AddInteger(unsigned(Tag));
59   ID.AddInteger(unsigned(Children));
60 
61   // For each attribute description.
62   for (unsigned i = 0, N = Data.size(); i < N; ++i)
63     Data[i].Profile(ID);
64 }
65 
66 /// Emit - Print the abbreviation using the specified asm printer.
67 ///
68 void DIEAbbrev::Emit(const AsmPrinter *AP) const {
69   // Emit its Dwarf tag type.
70   AP->EmitULEB128(Tag, dwarf::TagString(Tag).data());
71 
72   // Emit whether it has children DIEs.
73   AP->EmitULEB128((unsigned)Children, dwarf::ChildrenString(Children).data());
74 
75   // For each attribute description.
76   for (unsigned i = 0, N = Data.size(); i < N; ++i) {
77     const DIEAbbrevData &AttrData = Data[i];
78 
79     // Emit attribute type.
80     AP->EmitULEB128(AttrData.getAttribute(),
81                     dwarf::AttributeString(AttrData.getAttribute()).data());
82 
83     // Emit form type.
84 #ifndef NDEBUG
85     // Could be an assertion, but this way we can see the failing form code
86     // easily, which helps track down where it came from.
87     if (!dwarf::isValidFormForVersion(AttrData.getForm(),
88                                       AP->getDwarfVersion())) {
89       DEBUG(dbgs() << "Invalid form " << format("0x%x", AttrData.getForm())
90                    << " for DWARF version " << AP->getDwarfVersion() << "\n");
91       llvm_unreachable("Invalid form for specified DWARF version");
92     }
93 #endif
94     AP->EmitULEB128(AttrData.getForm(),
95                     dwarf::FormEncodingString(AttrData.getForm()).data());
96 
97     // Emit value for DW_FORM_implicit_const.
98     if (AttrData.getForm() == dwarf::DW_FORM_implicit_const)
99       AP->EmitSLEB128(AttrData.getValue());
100   }
101 
102   // Mark end of abbreviation.
103   AP->EmitULEB128(0, "EOM(1)");
104   AP->EmitULEB128(0, "EOM(2)");
105 }
106 
107 LLVM_DUMP_METHOD
108 void DIEAbbrev::print(raw_ostream &O) const {
109   O << "Abbreviation @"
110     << format("0x%lx", (long)(intptr_t)this)
111     << "  "
112     << dwarf::TagString(Tag)
113     << " "
114     << dwarf::ChildrenString(Children)
115     << '\n';
116 
117   for (unsigned i = 0, N = Data.size(); i < N; ++i) {
118     O << "  "
119       << dwarf::AttributeString(Data[i].getAttribute())
120       << "  "
121       << dwarf::FormEncodingString(Data[i].getForm());
122 
123     if (Data[i].getForm() == dwarf::DW_FORM_implicit_const)
124       O << " " << Data[i].getValue();
125 
126     O << '\n';
127   }
128 }
129 
130 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
131 LLVM_DUMP_METHOD void DIEAbbrev::dump() const {
132   print(dbgs());
133 }
134 #endif
135 
136 //===----------------------------------------------------------------------===//
137 // DIEAbbrevSet Implementation
138 //===----------------------------------------------------------------------===//
139 
140 DIEAbbrevSet::~DIEAbbrevSet() {
141   for (DIEAbbrev *Abbrev : Abbreviations)
142     Abbrev->~DIEAbbrev();
143 }
144 
145 DIEAbbrev &DIEAbbrevSet::uniqueAbbreviation(DIE &Die) {
146 
147   FoldingSetNodeID ID;
148   DIEAbbrev Abbrev = Die.generateAbbrev();
149   Abbrev.Profile(ID);
150 
151   void *InsertPos;
152   if (DIEAbbrev *Existing =
153           AbbreviationsSet.FindNodeOrInsertPos(ID, InsertPos)) {
154     Die.setAbbrevNumber(Existing->getNumber());
155     return *Existing;
156   }
157 
158   // Move the abbreviation to the heap and assign a number.
159   DIEAbbrev *New = new (Alloc) DIEAbbrev(std::move(Abbrev));
160   Abbreviations.push_back(New);
161   New->setNumber(Abbreviations.size());
162   Die.setAbbrevNumber(Abbreviations.size());
163 
164   // Store it for lookup.
165   AbbreviationsSet.InsertNode(New, InsertPos);
166   return *New;
167 }
168 
169 void DIEAbbrevSet::Emit(const AsmPrinter *AP, MCSection *Section) const {
170   if (!Abbreviations.empty()) {
171     // Start the debug abbrev section.
172     AP->OutStreamer->SwitchSection(Section);
173     AP->emitDwarfAbbrevs(Abbreviations);
174   }
175 }
176 
177 //===----------------------------------------------------------------------===//
178 // DIE Implementation
179 //===----------------------------------------------------------------------===//
180 
181 DIE *DIE::getParent() const {
182   return Owner.dyn_cast<DIE*>();
183 }
184 
185 DIEAbbrev DIE::generateAbbrev() const {
186   DIEAbbrev Abbrev(Tag, hasChildren());
187   for (const DIEValue &V : values())
188     if (V.getForm() == dwarf::DW_FORM_implicit_const)
189       Abbrev.AddImplicitConstAttribute(V.getAttribute(),
190                                        V.getDIEInteger().getValue());
191     else
192       Abbrev.AddAttribute(V.getAttribute(), V.getForm());
193   return Abbrev;
194 }
195 
196 unsigned DIE::getDebugSectionOffset() const {
197   const DIEUnit *Unit = getUnit();
198   assert(Unit && "DIE must be owned by a DIEUnit to get its absolute offset");
199   return Unit->getDebugSectionOffset() + getOffset();
200 }
201 
202 const DIE *DIE::getUnitDie() const {
203   const DIE *p = this;
204   while (p) {
205     if (p->getTag() == dwarf::DW_TAG_compile_unit ||
206         p->getTag() == dwarf::DW_TAG_type_unit)
207       return p;
208     p = p->getParent();
209   }
210   return nullptr;
211 }
212 
213 const DIEUnit *DIE::getUnit() const {
214   const DIE *UnitDie = getUnitDie();
215   if (UnitDie)
216     return UnitDie->Owner.dyn_cast<DIEUnit*>();
217   return nullptr;
218 }
219 
220 DIEValue DIE::findAttribute(dwarf::Attribute Attribute) const {
221   // Iterate through all the attributes until we find the one we're
222   // looking for, if we can't find it return NULL.
223   for (const auto &V : values())
224     if (V.getAttribute() == Attribute)
225       return V;
226   return DIEValue();
227 }
228 
229 LLVM_DUMP_METHOD
230 static void printValues(raw_ostream &O, const DIEValueList &Values,
231                         StringRef Type, unsigned Size, unsigned IndentCount) {
232   O << Type << ": Size: " << Size << "\n";
233 
234   unsigned I = 0;
235   const std::string Indent(IndentCount, ' ');
236   for (const auto &V : Values.values()) {
237     O << Indent;
238     O << "Blk[" << I++ << "]";
239     O << "  " << dwarf::FormEncodingString(V.getForm()) << " ";
240     V.print(O);
241     O << "\n";
242   }
243 }
244 
245 LLVM_DUMP_METHOD
246 void DIE::print(raw_ostream &O, unsigned IndentCount) const {
247   const std::string Indent(IndentCount, ' ');
248   O << Indent << "Die: " << format("0x%lx", (long)(intptr_t) this)
249     << ", Offset: " << Offset << ", Size: " << Size << "\n";
250 
251   O << Indent << dwarf::TagString(getTag()) << " "
252     << dwarf::ChildrenString(hasChildren()) << "\n";
253 
254   IndentCount += 2;
255   for (const auto &V : values()) {
256     O << Indent;
257     O << dwarf::AttributeString(V.getAttribute());
258     O << "  " << dwarf::FormEncodingString(V.getForm()) << " ";
259     V.print(O);
260     O << "\n";
261   }
262   IndentCount -= 2;
263 
264   for (const auto &Child : children())
265     Child.print(O, IndentCount + 4);
266 
267   O << "\n";
268 }
269 
270 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
271 LLVM_DUMP_METHOD void DIE::dump() const {
272   print(dbgs());
273 }
274 #endif
275 
276 unsigned DIE::computeOffsetsAndAbbrevs(const AsmPrinter *AP,
277                                        DIEAbbrevSet &AbbrevSet,
278                                        unsigned CUOffset) {
279   // Unique the abbreviation and fill in the abbreviation number so this DIE
280   // can be emitted.
281   const DIEAbbrev &Abbrev = AbbrevSet.uniqueAbbreviation(*this);
282 
283   // Set compile/type unit relative offset of this DIE.
284   setOffset(CUOffset);
285 
286   // Add the byte size of the abbreviation code.
287   CUOffset += getULEB128Size(getAbbrevNumber());
288 
289   // Add the byte size of all the DIE attribute values.
290   for (const auto &V : values())
291     CUOffset += V.SizeOf(AP);
292 
293   // Let the children compute their offsets and abbreviation numbers.
294   if (hasChildren()) {
295     (void)Abbrev;
296     assert(Abbrev.hasChildren() && "Children flag not set");
297 
298     for (auto &Child : children())
299       CUOffset = Child.computeOffsetsAndAbbrevs(AP, AbbrevSet, CUOffset);
300 
301     // Each child chain is terminated with a zero byte, adjust the offset.
302     CUOffset += sizeof(int8_t);
303   }
304 
305   // Compute the byte size of this DIE and all of its children correctly. This
306   // is needed so that top level DIE can help the compile unit set its length
307   // correctly.
308   setSize(CUOffset - getOffset());
309   return CUOffset;
310 }
311 
312 //===----------------------------------------------------------------------===//
313 // DIEUnit Implementation
314 //===----------------------------------------------------------------------===//
315 DIEUnit::DIEUnit(uint16_t V, uint8_t A, dwarf::Tag UnitTag)
316     : Die(UnitTag), Section(nullptr), Offset(0), Length(0), Version(V),
317       AddrSize(A)
318 {
319   Die.Owner = this;
320   assert((UnitTag == dwarf::DW_TAG_compile_unit ||
321           UnitTag == dwarf::DW_TAG_type_unit ||
322           UnitTag == dwarf::DW_TAG_partial_unit) && "expected a unit TAG");
323 }
324 
325 void DIEValue::EmitValue(const AsmPrinter *AP) const {
326   switch (Ty) {
327   case isNone:
328     llvm_unreachable("Expected valid DIEValue");
329 #define HANDLE_DIEVALUE(T)                                                     \
330   case is##T:                                                                  \
331     getDIE##T().EmitValue(AP, Form);                                           \
332     break;
333 #include "llvm/CodeGen/DIEValue.def"
334   }
335 }
336 
337 unsigned DIEValue::SizeOf(const AsmPrinter *AP) const {
338   switch (Ty) {
339   case isNone:
340     llvm_unreachable("Expected valid DIEValue");
341 #define HANDLE_DIEVALUE(T)                                                     \
342   case is##T:                                                                  \
343     return getDIE##T().SizeOf(AP, Form);
344 #include "llvm/CodeGen/DIEValue.def"
345   }
346   llvm_unreachable("Unknown DIE kind");
347 }
348 
349 LLVM_DUMP_METHOD
350 void DIEValue::print(raw_ostream &O) const {
351   switch (Ty) {
352   case isNone:
353     llvm_unreachable("Expected valid DIEValue");
354 #define HANDLE_DIEVALUE(T)                                                     \
355   case is##T:                                                                  \
356     getDIE##T().print(O);                                                      \
357     break;
358 #include "llvm/CodeGen/DIEValue.def"
359   }
360 }
361 
362 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
363 LLVM_DUMP_METHOD void DIEValue::dump() const {
364   print(dbgs());
365 }
366 #endif
367 
368 //===----------------------------------------------------------------------===//
369 // DIEInteger Implementation
370 //===----------------------------------------------------------------------===//
371 
372 /// EmitValue - Emit integer of appropriate size.
373 ///
374 void DIEInteger::EmitValue(const AsmPrinter *Asm, dwarf::Form Form) const {
375   switch (Form) {
376   case dwarf::DW_FORM_implicit_const:
377   case dwarf::DW_FORM_flag_present:
378     // Emit something to keep the lines and comments in sync.
379     // FIXME: Is there a better way to do this?
380     Asm->OutStreamer->AddBlankLine();
381     return;
382   case dwarf::DW_FORM_flag:
383   case dwarf::DW_FORM_ref1:
384   case dwarf::DW_FORM_data1:
385   case dwarf::DW_FORM_strx1:
386   case dwarf::DW_FORM_addrx1:
387   case dwarf::DW_FORM_ref2:
388   case dwarf::DW_FORM_data2:
389   case dwarf::DW_FORM_strx2:
390   case dwarf::DW_FORM_addrx2:
391   case dwarf::DW_FORM_strx3:
392   case dwarf::DW_FORM_strp:
393   case dwarf::DW_FORM_ref4:
394   case dwarf::DW_FORM_data4:
395   case dwarf::DW_FORM_ref_sup4:
396   case dwarf::DW_FORM_strx4:
397   case dwarf::DW_FORM_addrx4:
398   case dwarf::DW_FORM_ref8:
399   case dwarf::DW_FORM_ref_sig8:
400   case dwarf::DW_FORM_data8:
401   case dwarf::DW_FORM_ref_sup8:
402   case dwarf::DW_FORM_GNU_ref_alt:
403   case dwarf::DW_FORM_GNU_strp_alt:
404   case dwarf::DW_FORM_line_strp:
405   case dwarf::DW_FORM_sec_offset:
406   case dwarf::DW_FORM_strp_sup:
407   case dwarf::DW_FORM_addr:
408   case dwarf::DW_FORM_ref_addr:
409     Asm->OutStreamer->EmitIntValue(Integer, SizeOf(Asm, Form));
410     return;
411   case dwarf::DW_FORM_GNU_str_index:
412   case dwarf::DW_FORM_GNU_addr_index:
413   case dwarf::DW_FORM_ref_udata:
414   case dwarf::DW_FORM_strx:
415   case dwarf::DW_FORM_udata:
416     Asm->EmitULEB128(Integer);
417     return;
418   case dwarf::DW_FORM_sdata:
419     Asm->EmitSLEB128(Integer);
420     return;
421   default: llvm_unreachable("DIE Value form not supported yet");
422   }
423 }
424 
425 /// SizeOf - Determine size of integer value in bytes.
426 ///
427 unsigned DIEInteger::SizeOf(const AsmPrinter *AP, dwarf::Form Form) const {
428   dwarf::FormParams Params = {0, 0, dwarf::DWARF32};
429   if (AP)
430     Params = {AP->getDwarfVersion(), uint8_t(AP->getPointerSize()),
431               AP->OutStreamer->getContext().getDwarfFormat()};
432 
433   if (Optional<uint8_t> FixedSize = dwarf::getFixedFormByteSize(Form, Params))
434     return *FixedSize;
435 
436   switch (Form) {
437   case dwarf::DW_FORM_GNU_str_index:
438   case dwarf::DW_FORM_GNU_addr_index:
439   case dwarf::DW_FORM_ref_udata:
440   case dwarf::DW_FORM_strx:
441   case dwarf::DW_FORM_udata:
442     return getULEB128Size(Integer);
443   case dwarf::DW_FORM_sdata:
444     return getSLEB128Size(Integer);
445   default: llvm_unreachable("DIE Value form not supported yet");
446   }
447 }
448 
449 LLVM_DUMP_METHOD
450 void DIEInteger::print(raw_ostream &O) const {
451   O << "Int: " << (int64_t)Integer << "  0x";
452   O.write_hex(Integer);
453 }
454 
455 //===----------------------------------------------------------------------===//
456 // DIEExpr Implementation
457 //===----------------------------------------------------------------------===//
458 
459 /// EmitValue - Emit expression value.
460 ///
461 void DIEExpr::EmitValue(const AsmPrinter *AP, dwarf::Form Form) const {
462   AP->EmitDebugThreadLocal(Expr, SizeOf(AP, Form));
463 }
464 
465 /// SizeOf - Determine size of expression value in bytes.
466 ///
467 unsigned DIEExpr::SizeOf(const AsmPrinter *AP, dwarf::Form Form) const {
468   if (Form == dwarf::DW_FORM_data4) return 4;
469   if (Form == dwarf::DW_FORM_sec_offset) return 4;
470   if (Form == dwarf::DW_FORM_strp) return 4;
471   return AP->getPointerSize();
472 }
473 
474 LLVM_DUMP_METHOD
475 void DIEExpr::print(raw_ostream &O) const { O << "Expr: " << *Expr; }
476 
477 //===----------------------------------------------------------------------===//
478 // DIELabel Implementation
479 //===----------------------------------------------------------------------===//
480 
481 /// EmitValue - Emit label value.
482 ///
483 void DIELabel::EmitValue(const AsmPrinter *AP, dwarf::Form Form) const {
484   AP->EmitLabelReference(Label, SizeOf(AP, Form),
485                          Form == dwarf::DW_FORM_strp ||
486                              Form == dwarf::DW_FORM_sec_offset ||
487                              Form == dwarf::DW_FORM_ref_addr ||
488                              Form == dwarf::DW_FORM_data4);
489 }
490 
491 /// SizeOf - Determine size of label value in bytes.
492 ///
493 unsigned DIELabel::SizeOf(const AsmPrinter *AP, dwarf::Form Form) const {
494   if (Form == dwarf::DW_FORM_data4) return 4;
495   if (Form == dwarf::DW_FORM_sec_offset) return 4;
496   if (Form == dwarf::DW_FORM_strp) return 4;
497   return AP->MAI->getCodePointerSize();
498 }
499 
500 LLVM_DUMP_METHOD
501 void DIELabel::print(raw_ostream &O) const { O << "Lbl: " << Label->getName(); }
502 
503 //===----------------------------------------------------------------------===//
504 // DIEDelta Implementation
505 //===----------------------------------------------------------------------===//
506 
507 /// EmitValue - Emit delta value.
508 ///
509 void DIEDelta::EmitValue(const AsmPrinter *AP, dwarf::Form Form) const {
510   AP->EmitLabelDifference(LabelHi, LabelLo, SizeOf(AP, Form));
511 }
512 
513 /// SizeOf - Determine size of delta value in bytes.
514 ///
515 unsigned DIEDelta::SizeOf(const AsmPrinter *AP, dwarf::Form Form) const {
516   if (Form == dwarf::DW_FORM_data4) return 4;
517   if (Form == dwarf::DW_FORM_sec_offset) return 4;
518   if (Form == dwarf::DW_FORM_strp) return 4;
519   return AP->MAI->getCodePointerSize();
520 }
521 
522 LLVM_DUMP_METHOD
523 void DIEDelta::print(raw_ostream &O) const {
524   O << "Del: " << LabelHi->getName() << "-" << LabelLo->getName();
525 }
526 
527 //===----------------------------------------------------------------------===//
528 // DIEString Implementation
529 //===----------------------------------------------------------------------===//
530 
531 /// EmitValue - Emit string value.
532 ///
533 void DIEString::EmitValue(const AsmPrinter *AP, dwarf::Form Form) const {
534   // Index of string in symbol table.
535   switch (Form) {
536   case dwarf::DW_FORM_GNU_str_index:
537   case dwarf::DW_FORM_strx:
538   case dwarf::DW_FORM_strx1:
539   case dwarf::DW_FORM_strx2:
540   case dwarf::DW_FORM_strx3:
541   case dwarf::DW_FORM_strx4:
542     DIEInteger(S.getIndex()).EmitValue(AP, Form);
543     return;
544   case dwarf::DW_FORM_strp:
545     if (AP->MAI->doesDwarfUseRelocationsAcrossSections())
546       DIELabel(S.getSymbol()).EmitValue(AP, Form);
547     else
548       DIEInteger(S.getOffset()).EmitValue(AP, Form);
549     return;
550   default:
551     llvm_unreachable("Expected valid string form");
552   }
553 }
554 
555 /// SizeOf - Determine size of delta value in bytes.
556 ///
557 unsigned DIEString::SizeOf(const AsmPrinter *AP, dwarf::Form Form) const {
558   // Index of string in symbol table.
559   switch (Form) {
560   case dwarf::DW_FORM_GNU_str_index:
561   case dwarf::DW_FORM_strx:
562   case dwarf::DW_FORM_strx1:
563   case dwarf::DW_FORM_strx2:
564   case dwarf::DW_FORM_strx3:
565   case dwarf::DW_FORM_strx4:
566     return DIEInteger(S.getIndex()).SizeOf(AP, Form);
567   case dwarf::DW_FORM_strp:
568     if (AP->MAI->doesDwarfUseRelocationsAcrossSections())
569       return DIELabel(S.getSymbol()).SizeOf(AP, Form);
570     return DIEInteger(S.getOffset()).SizeOf(AP, Form);
571   default:
572     llvm_unreachable("Expected valid string form");
573   }
574 }
575 
576 LLVM_DUMP_METHOD
577 void DIEString::print(raw_ostream &O) const {
578   O << "String: " << S.getString();
579 }
580 
581 //===----------------------------------------------------------------------===//
582 // DIEInlineString Implementation
583 //===----------------------------------------------------------------------===//
584 void DIEInlineString::EmitValue(const AsmPrinter *AP, dwarf::Form Form) const {
585   if (Form == dwarf::DW_FORM_string) {
586     for (char ch : S)
587       AP->emitInt8(ch);
588     AP->emitInt8(0);
589     return;
590   }
591   llvm_unreachable("Expected valid string form");
592 }
593 
594 unsigned DIEInlineString::SizeOf(const AsmPrinter *AP, dwarf::Form Form) const {
595   // Emit string bytes + NULL byte.
596   return S.size() + 1;
597 }
598 
599 LLVM_DUMP_METHOD
600 void DIEInlineString::print(raw_ostream &O) const {
601   O << "InlineString: " << S;
602 }
603 
604 //===----------------------------------------------------------------------===//
605 // DIEEntry Implementation
606 //===----------------------------------------------------------------------===//
607 
608 /// EmitValue - Emit debug information entry offset.
609 ///
610 void DIEEntry::EmitValue(const AsmPrinter *AP, dwarf::Form Form) const {
611 
612   switch (Form) {
613   case dwarf::DW_FORM_ref1:
614   case dwarf::DW_FORM_ref2:
615   case dwarf::DW_FORM_ref4:
616   case dwarf::DW_FORM_ref8:
617     AP->OutStreamer->EmitIntValue(Entry->getOffset(), SizeOf(AP, Form));
618     return;
619 
620   case dwarf::DW_FORM_ref_udata:
621     AP->EmitULEB128(Entry->getOffset());
622     return;
623 
624   case dwarf::DW_FORM_ref_addr: {
625     // Get the absolute offset for this DIE within the debug info/types section.
626     unsigned Addr = Entry->getDebugSectionOffset();
627     if (const MCSymbol *SectionSym =
628             Entry->getUnit()->getCrossSectionRelativeBaseAddress()) {
629       AP->EmitLabelPlusOffset(SectionSym, Addr, SizeOf(AP, Form), true);
630       return;
631     }
632 
633     AP->OutStreamer->EmitIntValue(Addr, SizeOf(AP, Form));
634     return;
635   }
636   default:
637     llvm_unreachable("Improper form for DIE reference");
638   }
639 }
640 
641 unsigned DIEEntry::SizeOf(const AsmPrinter *AP, dwarf::Form Form) const {
642   switch (Form) {
643   case dwarf::DW_FORM_ref1:
644     return 1;
645   case dwarf::DW_FORM_ref2:
646     return 2;
647   case dwarf::DW_FORM_ref4:
648     return 4;
649   case dwarf::DW_FORM_ref8:
650     return 8;
651   case dwarf::DW_FORM_ref_udata:
652     return getULEB128Size(Entry->getOffset());
653   case dwarf::DW_FORM_ref_addr:
654     if (AP->getDwarfVersion() == 2)
655       return AP->MAI->getCodePointerSize();
656     switch (AP->OutStreamer->getContext().getDwarfFormat()) {
657     case dwarf::DWARF32:
658       return 4;
659     case dwarf::DWARF64:
660       return 8;
661     }
662     llvm_unreachable("Invalid DWARF format");
663 
664   default:
665     llvm_unreachable("Improper form for DIE reference");
666   }
667 }
668 
669 LLVM_DUMP_METHOD
670 void DIEEntry::print(raw_ostream &O) const {
671   O << format("Die: 0x%lx", (long)(intptr_t)&Entry);
672 }
673 
674 //===----------------------------------------------------------------------===//
675 // DIELoc Implementation
676 //===----------------------------------------------------------------------===//
677 
678 /// ComputeSize - calculate the size of the location expression.
679 ///
680 unsigned DIELoc::ComputeSize(const AsmPrinter *AP) const {
681   if (!Size) {
682     for (const auto &V : values())
683       Size += V.SizeOf(AP);
684   }
685 
686   return Size;
687 }
688 
689 /// EmitValue - Emit location data.
690 ///
691 void DIELoc::EmitValue(const AsmPrinter *Asm, dwarf::Form Form) const {
692   switch (Form) {
693   default: llvm_unreachable("Improper form for block");
694   case dwarf::DW_FORM_block1: Asm->emitInt8(Size);    break;
695   case dwarf::DW_FORM_block2: Asm->emitInt16(Size);   break;
696   case dwarf::DW_FORM_block4: Asm->emitInt32(Size);   break;
697   case dwarf::DW_FORM_block:
698   case dwarf::DW_FORM_exprloc:
699     Asm->EmitULEB128(Size); break;
700   }
701 
702   for (const auto &V : values())
703     V.EmitValue(Asm);
704 }
705 
706 /// SizeOf - Determine size of location data in bytes.
707 ///
708 unsigned DIELoc::SizeOf(const AsmPrinter *AP, dwarf::Form Form) const {
709   switch (Form) {
710   case dwarf::DW_FORM_block1: return Size + sizeof(int8_t);
711   case dwarf::DW_FORM_block2: return Size + sizeof(int16_t);
712   case dwarf::DW_FORM_block4: return Size + sizeof(int32_t);
713   case dwarf::DW_FORM_block:
714   case dwarf::DW_FORM_exprloc:
715     return Size + getULEB128Size(Size);
716   default: llvm_unreachable("Improper form for block");
717   }
718 }
719 
720 LLVM_DUMP_METHOD
721 void DIELoc::print(raw_ostream &O) const {
722   printValues(O, *this, "ExprLoc", Size, 5);
723 }
724 
725 //===----------------------------------------------------------------------===//
726 // DIEBlock Implementation
727 //===----------------------------------------------------------------------===//
728 
729 /// ComputeSize - calculate the size of the block.
730 ///
731 unsigned DIEBlock::ComputeSize(const AsmPrinter *AP) const {
732   if (!Size) {
733     for (const auto &V : values())
734       Size += V.SizeOf(AP);
735   }
736 
737   return Size;
738 }
739 
740 /// EmitValue - Emit block data.
741 ///
742 void DIEBlock::EmitValue(const AsmPrinter *Asm, dwarf::Form Form) const {
743   switch (Form) {
744   default: llvm_unreachable("Improper form for block");
745   case dwarf::DW_FORM_block1: Asm->emitInt8(Size);    break;
746   case dwarf::DW_FORM_block2: Asm->emitInt16(Size);   break;
747   case dwarf::DW_FORM_block4: Asm->emitInt32(Size);   break;
748   case dwarf::DW_FORM_block:  Asm->EmitULEB128(Size); break;
749   case dwarf::DW_FORM_string: break;
750   case dwarf::DW_FORM_data16: break;
751   }
752 
753   for (const auto &V : values())
754     V.EmitValue(Asm);
755 }
756 
757 /// SizeOf - Determine size of block data in bytes.
758 ///
759 unsigned DIEBlock::SizeOf(const AsmPrinter *AP, dwarf::Form Form) const {
760   switch (Form) {
761   case dwarf::DW_FORM_block1: return Size + sizeof(int8_t);
762   case dwarf::DW_FORM_block2: return Size + sizeof(int16_t);
763   case dwarf::DW_FORM_block4: return Size + sizeof(int32_t);
764   case dwarf::DW_FORM_block:  return Size + getULEB128Size(Size);
765   case dwarf::DW_FORM_data16: return 16;
766   default: llvm_unreachable("Improper form for block");
767   }
768 }
769 
770 LLVM_DUMP_METHOD
771 void DIEBlock::print(raw_ostream &O) const {
772   printValues(O, *this, "Blk", Size, 5);
773 }
774 
775 //===----------------------------------------------------------------------===//
776 // DIELocList Implementation
777 //===----------------------------------------------------------------------===//
778 
779 unsigned DIELocList::SizeOf(const AsmPrinter *AP, dwarf::Form Form) const {
780   if (Form == dwarf::DW_FORM_data4)
781     return 4;
782   if (Form == dwarf::DW_FORM_sec_offset)
783     return 4;
784   return AP->MAI->getCodePointerSize();
785 }
786 
787 /// EmitValue - Emit label value.
788 ///
789 void DIELocList::EmitValue(const AsmPrinter *AP, dwarf::Form Form) const {
790   DwarfDebug *DD = AP->getDwarfDebug();
791   MCSymbol *Label = DD->getDebugLocs().getList(Index).Label;
792   AP->emitDwarfSymbolReference(Label, /*ForceOffset*/ DD->useSplitDwarf());
793 }
794 
795 LLVM_DUMP_METHOD
796 void DIELocList::print(raw_ostream &O) const { O << "LocList: " << Index; }
797