1 //===--- DIBuilder.cpp - Debug Information Builder ------------------------===//
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 // This file implements the DIBuilder.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "llvm/IR/DIBuilder.h"
15 #include "llvm/ADT/STLExtras.h"
16 #include "llvm/IR/Constants.h"
17 #include "llvm/IR/DebugInfo.h"
18 #include "llvm/IR/IntrinsicInst.h"
19 #include "llvm/IR/Module.h"
20 #include "llvm/Support/Debug.h"
21 #include "llvm/Support/Dwarf.h"
22 
23 using namespace llvm;
24 using namespace llvm::dwarf;
25 
26 namespace {
27 class HeaderBuilder {
28   /// \brief Whether there are any fields yet.
29   ///
30   /// Note that this is not equivalent to \c Chars.empty(), since \a concat()
31   /// may have been called already with an empty string.
32   bool IsEmpty;
33   SmallVector<char, 256> Chars;
34 
35 public:
36   HeaderBuilder() : IsEmpty(true) {}
37   HeaderBuilder(const HeaderBuilder &X) : IsEmpty(X.IsEmpty), Chars(X.Chars) {}
38   HeaderBuilder(HeaderBuilder &&X)
39       : IsEmpty(X.IsEmpty), Chars(std::move(X.Chars)) {}
40 
41   template <class Twineable> HeaderBuilder &concat(Twineable &&X) {
42     if (IsEmpty)
43       IsEmpty = false;
44     else
45       Chars.push_back(0);
46     Twine(X).toVector(Chars);
47     return *this;
48   }
49 
50   MDString *get(LLVMContext &Context) const {
51     return MDString::get(Context, StringRef(Chars.begin(), Chars.size()));
52   }
53 
54   static HeaderBuilder get(unsigned Tag) {
55     return HeaderBuilder().concat("0x" + Twine::utohexstr(Tag));
56   }
57 };
58 }
59 
60 DIBuilder::DIBuilder(Module &m, bool AllowUnresolvedNodes)
61   : M(m), VMContext(M.getContext()), CUNode(nullptr),
62       DeclareFn(nullptr), ValueFn(nullptr),
63       AllowUnresolvedNodes(AllowUnresolvedNodes) {}
64 
65 void DIBuilder::trackIfUnresolved(MDNode *N) {
66   if (!N)
67     return;
68   if (N->isResolved())
69     return;
70 
71   assert(AllowUnresolvedNodes && "Cannot handle unresolved nodes");
72   UnresolvedNodes.emplace_back(N);
73 }
74 
75 void DIBuilder::finalize() {
76   if (!CUNode) {
77     assert(!AllowUnresolvedNodes &&
78            "creating type nodes without a CU is not supported");
79     return;
80   }
81 
82   CUNode->replaceEnumTypes(MDTuple::get(VMContext, AllEnumTypes));
83 
84   SmallVector<Metadata *, 16> RetainValues;
85   // Declarations and definitions of the same type may be retained. Some
86   // clients RAUW these pairs, leaving duplicates in the retained types
87   // list. Use a set to remove the duplicates while we transform the
88   // TrackingVHs back into Values.
89   SmallPtrSet<Metadata *, 16> RetainSet;
90   for (unsigned I = 0, E = AllRetainTypes.size(); I < E; I++)
91     if (RetainSet.insert(AllRetainTypes[I]).second)
92       RetainValues.push_back(AllRetainTypes[I]);
93 
94   if (!RetainValues.empty())
95     CUNode->replaceRetainedTypes(MDTuple::get(VMContext, RetainValues));
96 
97   DISubprogramArray SPs = MDTuple::get(VMContext, AllSubprograms);
98   if (!AllSubprograms.empty())
99     CUNode->replaceSubprograms(SPs.get());
100 
101   for (auto *SP : SPs) {
102     if (MDTuple *Temp = SP->getVariables().get()) {
103       const auto &PV = PreservedVariables.lookup(SP);
104       SmallVector<Metadata *, 4> Variables(PV.begin(), PV.end());
105       DINodeArray AV = getOrCreateArray(Variables);
106       TempMDTuple(Temp)->replaceAllUsesWith(AV.get());
107     }
108   }
109 
110   if (!AllGVs.empty())
111     CUNode->replaceGlobalVariables(MDTuple::get(VMContext, AllGVs));
112 
113   if (!AllImportedModules.empty())
114     CUNode->replaceImportedEntities(MDTuple::get(
115         VMContext, SmallVector<Metadata *, 16>(AllImportedModules.begin(),
116                                                AllImportedModules.end())));
117 
118   // Now that all temp nodes have been replaced or deleted, resolve remaining
119   // cycles.
120   for (const auto &N : UnresolvedNodes)
121     if (N && !N->isResolved())
122       N->resolveCycles();
123   UnresolvedNodes.clear();
124 
125   // Can't handle unresolved nodes anymore.
126   AllowUnresolvedNodes = false;
127 }
128 
129 /// If N is compile unit return NULL otherwise return N.
130 static DIScope *getNonCompileUnitScope(DIScope *N) {
131   if (!N || isa<DICompileUnit>(N))
132     return nullptr;
133   return cast<DIScope>(N);
134 }
135 
136 DICompileUnit *DIBuilder::createCompileUnit(
137     unsigned Lang, StringRef Filename, StringRef Directory, StringRef Producer,
138     bool isOptimized, StringRef Flags, unsigned RunTimeVer, StringRef SplitName,
139     DebugEmissionKind Kind, uint64_t DWOId, bool EmitDebugInfo) {
140 
141   assert(((Lang <= dwarf::DW_LANG_Fortran08 && Lang >= dwarf::DW_LANG_C89) ||
142           (Lang <= dwarf::DW_LANG_hi_user && Lang >= dwarf::DW_LANG_lo_user)) &&
143          "Invalid Language tag");
144   assert(!Filename.empty() &&
145          "Unable to create compile unit without filename");
146 
147   assert(!CUNode && "Can only make one compile unit per DIBuilder instance");
148   CUNode = DICompileUnit::getDistinct(
149       VMContext, Lang, DIFile::get(VMContext, Filename, Directory), Producer,
150       isOptimized, Flags, RunTimeVer, SplitName, Kind, nullptr,
151       nullptr, nullptr, nullptr, nullptr, DWOId);
152 
153   // Create a named metadata so that it is easier to find cu in a module.
154   // Note that we only generate this when the caller wants to actually
155   // emit debug information. When we are only interested in tracking
156   // source line locations throughout the backend, we prevent codegen from
157   // emitting debug info in the final output by not generating llvm.dbg.cu.
158   if (EmitDebugInfo) {
159     NamedMDNode *NMD = M.getOrInsertNamedMetadata("llvm.dbg.cu");
160     NMD->addOperand(CUNode);
161   }
162 
163   trackIfUnresolved(CUNode);
164   return CUNode;
165 }
166 
167 static DIImportedEntity *
168 createImportedModule(LLVMContext &C, dwarf::Tag Tag, DIScope *Context,
169                      Metadata *NS, unsigned Line, StringRef Name,
170                      SmallVectorImpl<TrackingMDNodeRef> &AllImportedModules) {
171   auto *M = DIImportedEntity::get(C, Tag, Context, DINodeRef(NS), Line, Name);
172   AllImportedModules.emplace_back(M);
173   return M;
174 }
175 
176 DIImportedEntity *DIBuilder::createImportedModule(DIScope *Context,
177                                                   DINamespace *NS,
178                                                   unsigned Line) {
179   return ::createImportedModule(VMContext, dwarf::DW_TAG_imported_module,
180                                 Context, NS, Line, StringRef(), AllImportedModules);
181 }
182 
183 DIImportedEntity *DIBuilder::createImportedModule(DIScope *Context,
184                                                   DIImportedEntity *NS,
185                                                   unsigned Line) {
186   return ::createImportedModule(VMContext, dwarf::DW_TAG_imported_module,
187                                 Context, NS, Line, StringRef(), AllImportedModules);
188 }
189 
190 DIImportedEntity *DIBuilder::createImportedModule(DIScope *Context, DIModule *M,
191                                                   unsigned Line) {
192   return ::createImportedModule(VMContext, dwarf::DW_TAG_imported_module,
193                                 Context, M, Line, StringRef(), AllImportedModules);
194 }
195 
196 DIImportedEntity *DIBuilder::createImportedDeclaration(DIScope *Context,
197                                                        DINode *Decl,
198                                                        unsigned Line,
199                                                        StringRef Name) {
200   // Make sure to use the unique identifier based metadata reference for
201   // types that have one.
202   return ::createImportedModule(VMContext, dwarf::DW_TAG_imported_declaration,
203                                 Context, DINodeRef::get(Decl), Line, Name,
204                                 AllImportedModules);
205 }
206 
207 DIFile *DIBuilder::createFile(StringRef Filename, StringRef Directory) {
208   return DIFile::get(VMContext, Filename, Directory);
209 }
210 
211 DIEnumerator *DIBuilder::createEnumerator(StringRef Name, int64_t Val) {
212   assert(!Name.empty() && "Unable to create enumerator without name");
213   return DIEnumerator::get(VMContext, Val, Name);
214 }
215 
216 DIBasicType *DIBuilder::createUnspecifiedType(StringRef Name) {
217   assert(!Name.empty() && "Unable to create type without name");
218   return DIBasicType::get(VMContext, dwarf::DW_TAG_unspecified_type, Name);
219 }
220 
221 DIBasicType *DIBuilder::createNullPtrType() {
222   return createUnspecifiedType("decltype(nullptr)");
223 }
224 
225 DIBasicType *DIBuilder::createBasicType(StringRef Name, uint64_t SizeInBits,
226                                         uint64_t AlignInBits,
227                                         unsigned Encoding) {
228   assert(!Name.empty() && "Unable to create type without name");
229   return DIBasicType::get(VMContext, dwarf::DW_TAG_base_type, Name, SizeInBits,
230                           AlignInBits, Encoding);
231 }
232 
233 DIDerivedType *DIBuilder::createQualifiedType(unsigned Tag, DIType *FromTy) {
234   return DIDerivedType::get(VMContext, Tag, "", nullptr, 0, nullptr,
235                             DITypeRef::get(FromTy), 0, 0, 0, 0);
236 }
237 
238 DIDerivedType *DIBuilder::createPointerType(DIType *PointeeTy,
239                                             uint64_t SizeInBits,
240                                             uint64_t AlignInBits,
241                                             StringRef Name) {
242   // FIXME: Why is there a name here?
243   return DIDerivedType::get(VMContext, dwarf::DW_TAG_pointer_type, Name,
244                             nullptr, 0, nullptr, DITypeRef::get(PointeeTy),
245                             SizeInBits, AlignInBits, 0, 0);
246 }
247 
248 DIDerivedType *DIBuilder::createMemberPointerType(DIType *PointeeTy,
249                                                   DIType *Base,
250                                                   uint64_t SizeInBits,
251                                                   uint64_t AlignInBits) {
252   return DIDerivedType::get(VMContext, dwarf::DW_TAG_ptr_to_member_type, "",
253                             nullptr, 0, nullptr, DITypeRef::get(PointeeTy),
254                             SizeInBits, AlignInBits, 0, 0,
255                             DITypeRef::get(Base));
256 }
257 
258 DIDerivedType *DIBuilder::createReferenceType(unsigned Tag, DIType *RTy) {
259   assert(RTy && "Unable to create reference type");
260   return DIDerivedType::get(VMContext, Tag, "", nullptr, 0, nullptr,
261                             DITypeRef::get(RTy), 0, 0, 0, 0);
262 }
263 
264 DIDerivedType *DIBuilder::createTypedef(DIType *Ty, StringRef Name,
265                                         DIFile *File, unsigned LineNo,
266                                         DIScope *Context) {
267   return DIDerivedType::get(VMContext, dwarf::DW_TAG_typedef, Name, File,
268                             LineNo,
269                             DIScopeRef::get(getNonCompileUnitScope(Context)),
270                             DITypeRef::get(Ty), 0, 0, 0, 0);
271 }
272 
273 DIDerivedType *DIBuilder::createFriend(DIType *Ty, DIType *FriendTy) {
274   assert(Ty && "Invalid type!");
275   assert(FriendTy && "Invalid friend type!");
276   return DIDerivedType::get(VMContext, dwarf::DW_TAG_friend, "", nullptr, 0,
277                             DITypeRef::get(Ty), DITypeRef::get(FriendTy), 0, 0,
278                             0, 0);
279 }
280 
281 DIDerivedType *DIBuilder::createInheritance(DIType *Ty, DIType *BaseTy,
282                                             uint64_t BaseOffset,
283                                             unsigned Flags) {
284   assert(Ty && "Unable to create inheritance");
285   return DIDerivedType::get(VMContext, dwarf::DW_TAG_inheritance, "", nullptr,
286                             0, DITypeRef::get(Ty), DITypeRef::get(BaseTy), 0, 0,
287                             BaseOffset, Flags);
288 }
289 
290 DIDerivedType *DIBuilder::createMemberType(DIScope *Scope, StringRef Name,
291                                            DIFile *File, unsigned LineNumber,
292                                            uint64_t SizeInBits,
293                                            uint64_t AlignInBits,
294                                            uint64_t OffsetInBits,
295                                            unsigned Flags, DIType *Ty) {
296   return DIDerivedType::get(
297       VMContext, dwarf::DW_TAG_member, Name, File, LineNumber,
298       DIScopeRef::get(getNonCompileUnitScope(Scope)), DITypeRef::get(Ty),
299       SizeInBits, AlignInBits, OffsetInBits, Flags);
300 }
301 
302 static ConstantAsMetadata *getConstantOrNull(Constant *C) {
303   if (C)
304     return ConstantAsMetadata::get(C);
305   return nullptr;
306 }
307 
308 DIDerivedType *DIBuilder::createStaticMemberType(DIScope *Scope, StringRef Name,
309                                                  DIFile *File,
310                                                  unsigned LineNumber,
311                                                  DIType *Ty, unsigned Flags,
312                                                  llvm::Constant *Val) {
313   Flags |= DINode::FlagStaticMember;
314   return DIDerivedType::get(
315       VMContext, dwarf::DW_TAG_member, Name, File, LineNumber,
316       DIScopeRef::get(getNonCompileUnitScope(Scope)), DITypeRef::get(Ty), 0, 0,
317       0, Flags, getConstantOrNull(Val));
318 }
319 
320 DIDerivedType *DIBuilder::createObjCIVar(StringRef Name, DIFile *File,
321                                          unsigned LineNumber,
322                                          uint64_t SizeInBits,
323                                          uint64_t AlignInBits,
324                                          uint64_t OffsetInBits, unsigned Flags,
325                                          DIType *Ty, MDNode *PropertyNode) {
326   return DIDerivedType::get(
327       VMContext, dwarf::DW_TAG_member, Name, File, LineNumber,
328       DIScopeRef::get(getNonCompileUnitScope(File)), DITypeRef::get(Ty),
329       SizeInBits, AlignInBits, OffsetInBits, Flags, PropertyNode);
330 }
331 
332 DIObjCProperty *
333 DIBuilder::createObjCProperty(StringRef Name, DIFile *File, unsigned LineNumber,
334                               StringRef GetterName, StringRef SetterName,
335                               unsigned PropertyAttributes, DIType *Ty) {
336   return DIObjCProperty::get(VMContext, Name, File, LineNumber, GetterName,
337                              SetterName, PropertyAttributes,
338                              DITypeRef::get(Ty));
339 }
340 
341 DITemplateTypeParameter *
342 DIBuilder::createTemplateTypeParameter(DIScope *Context, StringRef Name,
343                                        DIType *Ty) {
344   assert((!Context || isa<DICompileUnit>(Context)) && "Expected compile unit");
345   return DITemplateTypeParameter::get(VMContext, Name, DITypeRef::get(Ty));
346 }
347 
348 static DITemplateValueParameter *
349 createTemplateValueParameterHelper(LLVMContext &VMContext, unsigned Tag,
350                                    DIScope *Context, StringRef Name, DIType *Ty,
351                                    Metadata *MD) {
352   assert((!Context || isa<DICompileUnit>(Context)) && "Expected compile unit");
353   return DITemplateValueParameter::get(VMContext, Tag, Name, DITypeRef::get(Ty),
354                                        MD);
355 }
356 
357 DITemplateValueParameter *
358 DIBuilder::createTemplateValueParameter(DIScope *Context, StringRef Name,
359                                         DIType *Ty, Constant *Val) {
360   return createTemplateValueParameterHelper(
361       VMContext, dwarf::DW_TAG_template_value_parameter, Context, Name, Ty,
362       getConstantOrNull(Val));
363 }
364 
365 DITemplateValueParameter *
366 DIBuilder::createTemplateTemplateParameter(DIScope *Context, StringRef Name,
367                                            DIType *Ty, StringRef Val) {
368   return createTemplateValueParameterHelper(
369       VMContext, dwarf::DW_TAG_GNU_template_template_param, Context, Name, Ty,
370       MDString::get(VMContext, Val));
371 }
372 
373 DITemplateValueParameter *
374 DIBuilder::createTemplateParameterPack(DIScope *Context, StringRef Name,
375                                        DIType *Ty, DINodeArray Val) {
376   return createTemplateValueParameterHelper(
377       VMContext, dwarf::DW_TAG_GNU_template_parameter_pack, Context, Name, Ty,
378       Val.get());
379 }
380 
381 DICompositeType *DIBuilder::createClassType(
382     DIScope *Context, StringRef Name, DIFile *File, unsigned LineNumber,
383     uint64_t SizeInBits, uint64_t AlignInBits, uint64_t OffsetInBits,
384     unsigned Flags, DIType *DerivedFrom, DINodeArray Elements,
385     DIType *VTableHolder, MDNode *TemplateParams, StringRef UniqueIdentifier) {
386   assert((!Context || isa<DIScope>(Context)) &&
387          "createClassType should be called with a valid Context");
388 
389   auto *R = DICompositeType::get(
390       VMContext, dwarf::DW_TAG_structure_type, Name, File, LineNumber,
391       DIScopeRef::get(getNonCompileUnitScope(Context)),
392       DITypeRef::get(DerivedFrom), SizeInBits, AlignInBits, OffsetInBits, Flags,
393       Elements, 0, DITypeRef::get(VTableHolder),
394       cast_or_null<MDTuple>(TemplateParams), UniqueIdentifier);
395   if (!UniqueIdentifier.empty())
396     retainType(R);
397   trackIfUnresolved(R);
398   return R;
399 }
400 
401 DICompositeType *DIBuilder::createStructType(
402     DIScope *Context, StringRef Name, DIFile *File, unsigned LineNumber,
403     uint64_t SizeInBits, uint64_t AlignInBits, unsigned Flags,
404     DIType *DerivedFrom, DINodeArray Elements, unsigned RunTimeLang,
405     DIType *VTableHolder, StringRef UniqueIdentifier) {
406   auto *R = DICompositeType::get(
407       VMContext, dwarf::DW_TAG_structure_type, Name, File, LineNumber,
408       DIScopeRef::get(getNonCompileUnitScope(Context)),
409       DITypeRef::get(DerivedFrom), SizeInBits, AlignInBits, 0, Flags, Elements,
410       RunTimeLang, DITypeRef::get(VTableHolder), nullptr, UniqueIdentifier);
411   if (!UniqueIdentifier.empty())
412     retainType(R);
413   trackIfUnresolved(R);
414   return R;
415 }
416 
417 DICompositeType *DIBuilder::createUnionType(
418     DIScope *Scope, StringRef Name, DIFile *File, unsigned LineNumber,
419     uint64_t SizeInBits, uint64_t AlignInBits, unsigned Flags,
420     DINodeArray Elements, unsigned RunTimeLang, StringRef UniqueIdentifier) {
421   auto *R = DICompositeType::get(
422       VMContext, dwarf::DW_TAG_union_type, Name, File, LineNumber,
423       DIScopeRef::get(getNonCompileUnitScope(Scope)), nullptr, SizeInBits,
424       AlignInBits, 0, Flags, Elements, RunTimeLang, nullptr, nullptr,
425       UniqueIdentifier);
426   if (!UniqueIdentifier.empty())
427     retainType(R);
428   trackIfUnresolved(R);
429   return R;
430 }
431 
432 DISubroutineType *DIBuilder::createSubroutineType(DIFile *File,
433                                                   DITypeRefArray ParameterTypes,
434                                                   unsigned Flags) {
435   return DISubroutineType::get(VMContext, Flags, ParameterTypes);
436 }
437 
438 DICompositeType *DIBuilder::createExternalTypeRef(unsigned Tag, DIFile *File,
439                                                   StringRef UniqueIdentifier) {
440   assert(!UniqueIdentifier.empty() && "external type ref without uid");
441   auto *CTy =
442       DICompositeType::get(VMContext, Tag, "", nullptr, 0, nullptr, nullptr, 0,
443                            0, 0, DINode::FlagExternalTypeRef, nullptr, 0,
444                            nullptr, nullptr, UniqueIdentifier);
445   // Types with unique IDs need to be in the type map.
446   retainType(CTy);
447   return CTy;
448 }
449 
450 DICompositeType *DIBuilder::createEnumerationType(
451     DIScope *Scope, StringRef Name, DIFile *File, unsigned LineNumber,
452     uint64_t SizeInBits, uint64_t AlignInBits, DINodeArray Elements,
453     DIType *UnderlyingType, StringRef UniqueIdentifier) {
454   auto *CTy = DICompositeType::get(
455       VMContext, dwarf::DW_TAG_enumeration_type, Name, File, LineNumber,
456       DIScopeRef::get(getNonCompileUnitScope(Scope)),
457       DITypeRef::get(UnderlyingType), SizeInBits, AlignInBits, 0, 0, Elements,
458       0, nullptr, nullptr, UniqueIdentifier);
459   AllEnumTypes.push_back(CTy);
460   if (!UniqueIdentifier.empty())
461     retainType(CTy);
462   trackIfUnresolved(CTy);
463   return CTy;
464 }
465 
466 DICompositeType *DIBuilder::createArrayType(uint64_t Size, uint64_t AlignInBits,
467                                             DIType *Ty,
468                                             DINodeArray Subscripts) {
469   auto *R = DICompositeType::get(VMContext, dwarf::DW_TAG_array_type, "",
470                                  nullptr, 0, nullptr, DITypeRef::get(Ty), Size,
471                                  AlignInBits, 0, 0, Subscripts, 0, nullptr);
472   trackIfUnresolved(R);
473   return R;
474 }
475 
476 DICompositeType *DIBuilder::createVectorType(uint64_t Size,
477                                              uint64_t AlignInBits, DIType *Ty,
478                                              DINodeArray Subscripts) {
479   auto *R =
480       DICompositeType::get(VMContext, dwarf::DW_TAG_array_type, "", nullptr, 0,
481                            nullptr, DITypeRef::get(Ty), Size, AlignInBits, 0,
482                            DINode::FlagVector, Subscripts, 0, nullptr);
483   trackIfUnresolved(R);
484   return R;
485 }
486 
487 static DIType *createTypeWithFlags(LLVMContext &Context, DIType *Ty,
488                                    unsigned FlagsToSet) {
489   auto NewTy = Ty->clone();
490   NewTy->setFlags(NewTy->getFlags() | FlagsToSet);
491   return MDNode::replaceWithUniqued(std::move(NewTy));
492 }
493 
494 DIType *DIBuilder::createArtificialType(DIType *Ty) {
495   // FIXME: Restrict this to the nodes where it's valid.
496   if (Ty->isArtificial())
497     return Ty;
498   return createTypeWithFlags(VMContext, Ty, DINode::FlagArtificial);
499 }
500 
501 DIType *DIBuilder::createObjectPointerType(DIType *Ty) {
502   // FIXME: Restrict this to the nodes where it's valid.
503   if (Ty->isObjectPointer())
504     return Ty;
505   unsigned Flags = DINode::FlagObjectPointer | DINode::FlagArtificial;
506   return createTypeWithFlags(VMContext, Ty, Flags);
507 }
508 
509 void DIBuilder::retainType(DIType *T) {
510   assert(T && "Expected non-null type");
511   AllRetainTypes.emplace_back(T);
512 }
513 
514 DIBasicType *DIBuilder::createUnspecifiedParameter() { return nullptr; }
515 
516 DICompositeType *
517 DIBuilder::createForwardDecl(unsigned Tag, StringRef Name, DIScope *Scope,
518                              DIFile *F, unsigned Line, unsigned RuntimeLang,
519                              uint64_t SizeInBits, uint64_t AlignInBits,
520                              StringRef UniqueIdentifier) {
521   // FIXME: Define in terms of createReplaceableForwardDecl() by calling
522   // replaceWithUniqued().
523   auto *RetTy = DICompositeType::get(
524       VMContext, Tag, Name, F, Line,
525       DIScopeRef::get(getNonCompileUnitScope(Scope)), nullptr, SizeInBits,
526       AlignInBits, 0, DINode::FlagFwdDecl, nullptr, RuntimeLang, nullptr,
527       nullptr, UniqueIdentifier);
528   if (!UniqueIdentifier.empty())
529     retainType(RetTy);
530   trackIfUnresolved(RetTy);
531   return RetTy;
532 }
533 
534 DICompositeType *DIBuilder::createReplaceableCompositeType(
535     unsigned Tag, StringRef Name, DIScope *Scope, DIFile *F, unsigned Line,
536     unsigned RuntimeLang, uint64_t SizeInBits, uint64_t AlignInBits,
537     unsigned Flags, StringRef UniqueIdentifier) {
538   auto *RetTy = DICompositeType::getTemporary(
539                     VMContext, Tag, Name, F, Line,
540                     DIScopeRef::get(getNonCompileUnitScope(Scope)), nullptr,
541                     SizeInBits, AlignInBits, 0, Flags, nullptr, RuntimeLang,
542                     nullptr, nullptr, UniqueIdentifier)
543                     .release();
544   if (!UniqueIdentifier.empty())
545     retainType(RetTy);
546   trackIfUnresolved(RetTy);
547   return RetTy;
548 }
549 
550 DINodeArray DIBuilder::getOrCreateArray(ArrayRef<Metadata *> Elements) {
551   return MDTuple::get(VMContext, Elements);
552 }
553 
554 DITypeRefArray DIBuilder::getOrCreateTypeArray(ArrayRef<Metadata *> Elements) {
555   SmallVector<llvm::Metadata *, 16> Elts;
556   for (unsigned i = 0, e = Elements.size(); i != e; ++i) {
557     if (Elements[i] && isa<MDNode>(Elements[i]))
558       Elts.push_back(DITypeRef::get(cast<DIType>(Elements[i])));
559     else
560       Elts.push_back(Elements[i]);
561   }
562   return DITypeRefArray(MDNode::get(VMContext, Elts));
563 }
564 
565 DISubrange *DIBuilder::getOrCreateSubrange(int64_t Lo, int64_t Count) {
566   return DISubrange::get(VMContext, Count, Lo);
567 }
568 
569 static void checkGlobalVariableScope(DIScope *Context) {
570 #ifndef NDEBUG
571   if (auto *CT =
572           dyn_cast_or_null<DICompositeType>(getNonCompileUnitScope(Context)))
573     assert(CT->getIdentifier().empty() &&
574            "Context of a global variable should not be a type with identifier");
575 #endif
576 }
577 
578 DIGlobalVariable *DIBuilder::createGlobalVariable(
579     DIScope *Context, StringRef Name, StringRef LinkageName, DIFile *F,
580     unsigned LineNumber, DIType *Ty, bool isLocalToUnit, Constant *Val,
581     MDNode *Decl) {
582   checkGlobalVariableScope(Context);
583 
584   auto *N = DIGlobalVariable::get(VMContext, cast_or_null<DIScope>(Context),
585                                   Name, LinkageName, F, LineNumber,
586                                   DITypeRef::get(Ty), isLocalToUnit, true, Val,
587                                   cast_or_null<DIDerivedType>(Decl));
588   AllGVs.push_back(N);
589   return N;
590 }
591 
592 DIGlobalVariable *DIBuilder::createTempGlobalVariableFwdDecl(
593     DIScope *Context, StringRef Name, StringRef LinkageName, DIFile *F,
594     unsigned LineNumber, DIType *Ty, bool isLocalToUnit, Constant *Val,
595     MDNode *Decl) {
596   checkGlobalVariableScope(Context);
597 
598   return DIGlobalVariable::getTemporary(
599              VMContext, cast_or_null<DIScope>(Context), Name, LinkageName, F,
600              LineNumber, DITypeRef::get(Ty), isLocalToUnit, false, Val,
601              cast_or_null<DIDerivedType>(Decl))
602       .release();
603 }
604 
605 static DILocalVariable *createLocalVariable(
606     LLVMContext &VMContext,
607     DenseMap<MDNode *, std::vector<TrackingMDNodeRef>> &PreservedVariables,
608     DIScope *Scope, StringRef Name, unsigned ArgNo, DIFile *File,
609     unsigned LineNo, DIType *Ty, bool AlwaysPreserve, unsigned Flags) {
610   // FIXME: Why getNonCompileUnitScope()?
611   // FIXME: Why is "!Context" okay here?
612   // FIXME: Why doesn't this check for a subprogram or lexical block (AFAICT
613   // the only valid scopes)?
614   DIScope *Context = getNonCompileUnitScope(Scope);
615 
616   auto *Node =
617       DILocalVariable::get(VMContext, cast_or_null<DILocalScope>(Context), Name,
618                            File, LineNo, DITypeRef::get(Ty), ArgNo, Flags);
619   if (AlwaysPreserve) {
620     // The optimizer may remove local variables. If there is an interest
621     // to preserve variable info in such situation then stash it in a
622     // named mdnode.
623     DISubprogram *Fn = getDISubprogram(Scope);
624     assert(Fn && "Missing subprogram for local variable");
625     PreservedVariables[Fn].emplace_back(Node);
626   }
627   return Node;
628 }
629 
630 DILocalVariable *DIBuilder::createAutoVariable(DIScope *Scope, StringRef Name,
631                                                DIFile *File, unsigned LineNo,
632                                                DIType *Ty, bool AlwaysPreserve,
633                                                unsigned Flags) {
634   return createLocalVariable(VMContext, PreservedVariables, Scope, Name,
635                              /* ArgNo */ 0, File, LineNo, Ty, AlwaysPreserve,
636                              Flags);
637 }
638 
639 DILocalVariable *DIBuilder::createParameterVariable(
640     DIScope *Scope, StringRef Name, unsigned ArgNo, DIFile *File,
641     unsigned LineNo, DIType *Ty, bool AlwaysPreserve, unsigned Flags) {
642   assert(ArgNo && "Expected non-zero argument number for parameter");
643   return createLocalVariable(VMContext, PreservedVariables, Scope, Name, ArgNo,
644                              File, LineNo, Ty, AlwaysPreserve, Flags);
645 }
646 
647 DIExpression *DIBuilder::createExpression(ArrayRef<uint64_t> Addr) {
648   return DIExpression::get(VMContext, Addr);
649 }
650 
651 DIExpression *DIBuilder::createExpression(ArrayRef<int64_t> Signed) {
652   // TODO: Remove the callers of this signed version and delete.
653   SmallVector<uint64_t, 8> Addr(Signed.begin(), Signed.end());
654   return createExpression(Addr);
655 }
656 
657 DIExpression *DIBuilder::createBitPieceExpression(unsigned OffsetInBytes,
658                                                   unsigned SizeInBytes) {
659   uint64_t Addr[] = {dwarf::DW_OP_bit_piece, OffsetInBytes, SizeInBytes};
660   return DIExpression::get(VMContext, Addr);
661 }
662 
663 DISubprogram *DIBuilder::createFunction(DIScopeRef Context, StringRef Name,
664                                         StringRef LinkageName, DIFile *File,
665                                         unsigned LineNo, DISubroutineType *Ty,
666                                         bool isLocalToUnit, bool isDefinition,
667                                         unsigned ScopeLine, unsigned Flags,
668                                         bool isOptimized, Function *Fn,
669                                         MDNode *TParams, MDNode *Decl) {
670   // dragonegg does not generate identifier for types, so using an empty map
671   // to resolve the context should be fine.
672   DITypeIdentifierMap EmptyMap;
673   return createFunction(Context.resolve(EmptyMap), Name, LinkageName, File,
674                         LineNo, Ty, isLocalToUnit, isDefinition, ScopeLine,
675                         Flags, isOptimized, Fn, TParams, Decl);
676 }
677 
678 template <class... Ts>
679 static DISubprogram *getSubprogram(bool IsDistinct, Ts &&... Args) {
680   if (IsDistinct)
681     return DISubprogram::getDistinct(std::forward<Ts>(Args)...);
682   return DISubprogram::get(std::forward<Ts>(Args)...);
683 }
684 
685 DISubprogram *DIBuilder::createFunction(DIScope *Context, StringRef Name,
686                                         StringRef LinkageName, DIFile *File,
687                                         unsigned LineNo, DISubroutineType *Ty,
688                                         bool isLocalToUnit, bool isDefinition,
689                                         unsigned ScopeLine, unsigned Flags,
690                                         bool isOptimized, Function *Fn,
691                                         MDNode *TParams, MDNode *Decl) {
692   auto *Node = getSubprogram(/* IsDistinct = */ isDefinition, VMContext,
693                              DIScopeRef::get(getNonCompileUnitScope(Context)),
694                              Name, LinkageName, File, LineNo, Ty, isLocalToUnit,
695                              isDefinition, ScopeLine, nullptr, 0, 0, Flags,
696                              isOptimized, Fn, cast_or_null<MDTuple>(TParams),
697                              cast_or_null<DISubprogram>(Decl),
698                              MDTuple::getTemporary(VMContext, None).release());
699 
700   if (isDefinition)
701     AllSubprograms.push_back(Node);
702   trackIfUnresolved(Node);
703   return Node;
704 }
705 
706 DISubprogram *DIBuilder::createTempFunctionFwdDecl(
707     DIScope *Context, StringRef Name, StringRef LinkageName, DIFile *File,
708     unsigned LineNo, DISubroutineType *Ty, bool isLocalToUnit,
709     bool isDefinition, unsigned ScopeLine, unsigned Flags, bool isOptimized,
710     Function *Fn, MDNode *TParams, MDNode *Decl) {
711   return DISubprogram::getTemporary(
712              VMContext, DIScopeRef::get(getNonCompileUnitScope(Context)), Name,
713              LinkageName, File, LineNo, Ty, isLocalToUnit, isDefinition,
714              ScopeLine, nullptr, 0, 0, Flags, isOptimized, Fn,
715              cast_or_null<MDTuple>(TParams), cast_or_null<DISubprogram>(Decl),
716              nullptr)
717       .release();
718 }
719 
720 DISubprogram *
721 DIBuilder::createMethod(DIScope *Context, StringRef Name, StringRef LinkageName,
722                         DIFile *F, unsigned LineNo, DISubroutineType *Ty,
723                         bool isLocalToUnit, bool isDefinition, unsigned VK,
724                         unsigned VIndex, DIType *VTableHolder, unsigned Flags,
725                         bool isOptimized, Function *Fn, MDNode *TParam) {
726   assert(getNonCompileUnitScope(Context) &&
727          "Methods should have both a Context and a context that isn't "
728          "the compile unit.");
729   // FIXME: Do we want to use different scope/lines?
730   auto *SP = getSubprogram(/* IsDistinct = */ isDefinition, VMContext,
731                            DIScopeRef::get(cast<DIScope>(Context)), Name,
732                            LinkageName, F, LineNo, Ty, isLocalToUnit,
733                            isDefinition, LineNo, DITypeRef::get(VTableHolder),
734                            VK, VIndex, Flags, isOptimized, Fn,
735                            cast_or_null<MDTuple>(TParam), nullptr, nullptr);
736 
737   if (isDefinition)
738     AllSubprograms.push_back(SP);
739   trackIfUnresolved(SP);
740   return SP;
741 }
742 
743 DINamespace *DIBuilder::createNameSpace(DIScope *Scope, StringRef Name,
744                                         DIFile *File, unsigned LineNo) {
745   return DINamespace::get(VMContext, getNonCompileUnitScope(Scope), File, Name,
746                           LineNo);
747 }
748 
749 DIModule *DIBuilder::createModule(DIScope *Scope, StringRef Name,
750                                   StringRef ConfigurationMacros,
751                                   StringRef IncludePath,
752                                   StringRef ISysRoot) {
753  return DIModule::get(VMContext, getNonCompileUnitScope(Scope), Name,
754                       ConfigurationMacros, IncludePath, ISysRoot);
755 }
756 
757 DILexicalBlockFile *DIBuilder::createLexicalBlockFile(DIScope *Scope,
758                                                       DIFile *File,
759                                                       unsigned Discriminator) {
760   return DILexicalBlockFile::get(VMContext, Scope, File, Discriminator);
761 }
762 
763 DILexicalBlock *DIBuilder::createLexicalBlock(DIScope *Scope, DIFile *File,
764                                               unsigned Line, unsigned Col) {
765   // Make these distinct, to avoid merging two lexical blocks on the same
766   // file/line/column.
767   return DILexicalBlock::getDistinct(VMContext, getNonCompileUnitScope(Scope),
768                                      File, Line, Col);
769 }
770 
771 static Value *getDbgIntrinsicValueImpl(LLVMContext &VMContext, Value *V) {
772   assert(V && "no value passed to dbg intrinsic");
773   return MetadataAsValue::get(VMContext, ValueAsMetadata::get(V));
774 }
775 
776 static Instruction *withDebugLoc(Instruction *I, const DILocation *DL) {
777   I->setDebugLoc(const_cast<DILocation *>(DL));
778   return I;
779 }
780 
781 Instruction *DIBuilder::insertDeclare(Value *Storage, DILocalVariable *VarInfo,
782                                       DIExpression *Expr, const DILocation *DL,
783                                       Instruction *InsertBefore) {
784   assert(VarInfo && "empty or invalid DILocalVariable* passed to dbg.declare");
785   assert(DL && "Expected debug loc");
786   assert(DL->getScope()->getSubprogram() ==
787              VarInfo->getScope()->getSubprogram() &&
788          "Expected matching subprograms");
789   if (!DeclareFn)
790     DeclareFn = Intrinsic::getDeclaration(&M, Intrinsic::dbg_declare);
791 
792   trackIfUnresolved(VarInfo);
793   trackIfUnresolved(Expr);
794   Value *Args[] = {getDbgIntrinsicValueImpl(VMContext, Storage),
795                    MetadataAsValue::get(VMContext, VarInfo),
796                    MetadataAsValue::get(VMContext, Expr)};
797   return withDebugLoc(CallInst::Create(DeclareFn, Args, "", InsertBefore), DL);
798 }
799 
800 Instruction *DIBuilder::insertDeclare(Value *Storage, DILocalVariable *VarInfo,
801                                       DIExpression *Expr, const DILocation *DL,
802                                       BasicBlock *InsertAtEnd) {
803   assert(VarInfo && "empty or invalid DILocalVariable* passed to dbg.declare");
804   assert(DL && "Expected debug loc");
805   assert(DL->getScope()->getSubprogram() ==
806              VarInfo->getScope()->getSubprogram() &&
807          "Expected matching subprograms");
808   if (!DeclareFn)
809     DeclareFn = Intrinsic::getDeclaration(&M, Intrinsic::dbg_declare);
810 
811   trackIfUnresolved(VarInfo);
812   trackIfUnresolved(Expr);
813   Value *Args[] = {getDbgIntrinsicValueImpl(VMContext, Storage),
814                    MetadataAsValue::get(VMContext, VarInfo),
815                    MetadataAsValue::get(VMContext, Expr)};
816 
817   // If this block already has a terminator then insert this intrinsic
818   // before the terminator.
819   if (TerminatorInst *T = InsertAtEnd->getTerminator())
820     return withDebugLoc(CallInst::Create(DeclareFn, Args, "", T), DL);
821   return withDebugLoc(CallInst::Create(DeclareFn, Args, "", InsertAtEnd), DL);
822 }
823 
824 Instruction *DIBuilder::insertDbgValueIntrinsic(Value *V, uint64_t Offset,
825                                                 DILocalVariable *VarInfo,
826                                                 DIExpression *Expr,
827                                                 const DILocation *DL,
828                                                 Instruction *InsertBefore) {
829   assert(V && "no value passed to dbg.value");
830   assert(VarInfo && "empty or invalid DILocalVariable* passed to dbg.value");
831   assert(DL && "Expected debug loc");
832   assert(DL->getScope()->getSubprogram() ==
833              VarInfo->getScope()->getSubprogram() &&
834          "Expected matching subprograms");
835   if (!ValueFn)
836     ValueFn = Intrinsic::getDeclaration(&M, Intrinsic::dbg_value);
837 
838   trackIfUnresolved(VarInfo);
839   trackIfUnresolved(Expr);
840   Value *Args[] = {getDbgIntrinsicValueImpl(VMContext, V),
841                    ConstantInt::get(Type::getInt64Ty(VMContext), Offset),
842                    MetadataAsValue::get(VMContext, VarInfo),
843                    MetadataAsValue::get(VMContext, Expr)};
844   return withDebugLoc(CallInst::Create(ValueFn, Args, "", InsertBefore), DL);
845 }
846 
847 Instruction *DIBuilder::insertDbgValueIntrinsic(Value *V, uint64_t Offset,
848                                                 DILocalVariable *VarInfo,
849                                                 DIExpression *Expr,
850                                                 const DILocation *DL,
851                                                 BasicBlock *InsertAtEnd) {
852   assert(V && "no value passed to dbg.value");
853   assert(VarInfo && "empty or invalid DILocalVariable* passed to dbg.value");
854   assert(DL && "Expected debug loc");
855   assert(DL->getScope()->getSubprogram() ==
856              VarInfo->getScope()->getSubprogram() &&
857          "Expected matching subprograms");
858   if (!ValueFn)
859     ValueFn = Intrinsic::getDeclaration(&M, Intrinsic::dbg_value);
860 
861   trackIfUnresolved(VarInfo);
862   trackIfUnresolved(Expr);
863   Value *Args[] = {getDbgIntrinsicValueImpl(VMContext, V),
864                    ConstantInt::get(Type::getInt64Ty(VMContext), Offset),
865                    MetadataAsValue::get(VMContext, VarInfo),
866                    MetadataAsValue::get(VMContext, Expr)};
867 
868   return withDebugLoc(CallInst::Create(ValueFn, Args, "", InsertAtEnd), DL);
869 }
870 
871 void DIBuilder::replaceVTableHolder(DICompositeType *&T,
872                                     DICompositeType *VTableHolder) {
873   {
874     TypedTrackingMDRef<DICompositeType> N(T);
875     N->replaceVTableHolder(DITypeRef::get(VTableHolder));
876     T = N.get();
877   }
878 
879   // If this didn't create a self-reference, just return.
880   if (T != VTableHolder)
881     return;
882 
883   // Look for unresolved operands.  T will drop RAUW support, orphaning any
884   // cycles underneath it.
885   if (T->isResolved())
886     for (const MDOperand &O : T->operands())
887       if (auto *N = dyn_cast_or_null<MDNode>(O))
888         trackIfUnresolved(N);
889 }
890 
891 void DIBuilder::replaceArrays(DICompositeType *&T, DINodeArray Elements,
892                               DINodeArray TParams) {
893   {
894     TypedTrackingMDRef<DICompositeType> N(T);
895     if (Elements)
896       N->replaceElements(Elements);
897     if (TParams)
898       N->replaceTemplateParams(DITemplateParameterArray(TParams));
899     T = N.get();
900   }
901 
902   // If T isn't resolved, there's no problem.
903   if (!T->isResolved())
904     return;
905 
906   // If T is resolved, it may be due to a self-reference cycle.  Track the
907   // arrays explicitly if they're unresolved, or else the cycles will be
908   // orphaned.
909   if (Elements)
910     trackIfUnresolved(Elements.get());
911   if (TParams)
912     trackIfUnresolved(TParams.get());
913 }
914