1 //===--- DIBuilder.cpp - Debug Information Builder ------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file implements the DIBuilder.
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #include "llvm/IR/DIBuilder.h"
14 #include "LLVMContextImpl.h"
15 #include "llvm/ADT/Optional.h"
16 #include "llvm/ADT/STLExtras.h"
17 #include "llvm/BinaryFormat/Dwarf.h"
18 #include "llvm/IR/Constants.h"
19 #include "llvm/IR/DebugInfo.h"
20 #include "llvm/IR/IRBuilder.h"
21 #include "llvm/IR/IntrinsicInst.h"
22 #include "llvm/IR/Module.h"
23 #include "llvm/Support/CommandLine.h"
24 #include "llvm/Support/Debug.h"
25 
26 using namespace llvm;
27 using namespace llvm::dwarf;
28 
29 static cl::opt<bool>
30     UseDbgAddr("use-dbg-addr",
31                llvm::cl::desc("Use llvm.dbg.addr for all local variables"),
32                cl::init(false), cl::Hidden);
33 
34 DIBuilder::DIBuilder(Module &m, bool AllowUnresolvedNodes, DICompileUnit *CU)
35   : M(m), VMContext(M.getContext()), CUNode(CU),
36       DeclareFn(nullptr), ValueFn(nullptr), LabelFn(nullptr),
37       AllowUnresolvedNodes(AllowUnresolvedNodes) {}
38 
39 void DIBuilder::trackIfUnresolved(MDNode *N) {
40   if (!N)
41     return;
42   if (N->isResolved())
43     return;
44 
45   assert(AllowUnresolvedNodes && "Cannot handle unresolved nodes");
46   UnresolvedNodes.emplace_back(N);
47 }
48 
49 void DIBuilder::finalizeSubprogram(DISubprogram *SP) {
50   MDTuple *Temp = SP->getRetainedNodes().get();
51   if (!Temp || !Temp->isTemporary())
52     return;
53 
54   SmallVector<Metadata *, 16> RetainedNodes;
55 
56   auto PV = PreservedVariables.find(SP);
57   if (PV != PreservedVariables.end())
58     RetainedNodes.append(PV->second.begin(), PV->second.end());
59 
60   auto PL = PreservedLabels.find(SP);
61   if (PL != PreservedLabels.end())
62     RetainedNodes.append(PL->second.begin(), PL->second.end());
63 
64   DINodeArray Node = getOrCreateArray(RetainedNodes);
65 
66   TempMDTuple(Temp)->replaceAllUsesWith(Node.get());
67 }
68 
69 void DIBuilder::finalize() {
70   if (!CUNode) {
71     assert(!AllowUnresolvedNodes &&
72            "creating type nodes without a CU is not supported");
73     return;
74   }
75 
76   CUNode->replaceEnumTypes(MDTuple::get(VMContext, AllEnumTypes));
77 
78   SmallVector<Metadata *, 16> RetainValues;
79   // Declarations and definitions of the same type may be retained. Some
80   // clients RAUW these pairs, leaving duplicates in the retained types
81   // list. Use a set to remove the duplicates while we transform the
82   // TrackingVHs back into Values.
83   SmallPtrSet<Metadata *, 16> RetainSet;
84   for (unsigned I = 0, E = AllRetainTypes.size(); I < E; I++)
85     if (RetainSet.insert(AllRetainTypes[I]).second)
86       RetainValues.push_back(AllRetainTypes[I]);
87 
88   if (!RetainValues.empty())
89     CUNode->replaceRetainedTypes(MDTuple::get(VMContext, RetainValues));
90 
91   DISubprogramArray SPs = MDTuple::get(VMContext, AllSubprograms);
92   for (auto *SP : SPs)
93     finalizeSubprogram(SP);
94   for (auto *N : RetainValues)
95     if (auto *SP = dyn_cast<DISubprogram>(N))
96       finalizeSubprogram(SP);
97 
98   if (!AllGVs.empty())
99     CUNode->replaceGlobalVariables(MDTuple::get(VMContext, AllGVs));
100 
101   if (!AllImportedModules.empty())
102     CUNode->replaceImportedEntities(MDTuple::get(
103         VMContext, SmallVector<Metadata *, 16>(AllImportedModules.begin(),
104                                                AllImportedModules.end())));
105 
106   for (const auto &I : AllMacrosPerParent) {
107     // DIMacroNode's with nullptr parent are DICompileUnit direct children.
108     if (!I.first) {
109       CUNode->replaceMacros(MDTuple::get(VMContext, I.second.getArrayRef()));
110       continue;
111     }
112     // Otherwise, it must be a temporary DIMacroFile that need to be resolved.
113     auto *TMF = cast<DIMacroFile>(I.first);
114     auto *MF = DIMacroFile::get(VMContext, dwarf::DW_MACINFO_start_file,
115                                 TMF->getLine(), TMF->getFile(),
116                                 getOrCreateMacroArray(I.second.getArrayRef()));
117     replaceTemporary(llvm::TempDIMacroNode(TMF), MF);
118   }
119 
120   // Now that all temp nodes have been replaced or deleted, resolve remaining
121   // cycles.
122   for (const auto &N : UnresolvedNodes)
123     if (N && !N->isResolved())
124       N->resolveCycles();
125   UnresolvedNodes.clear();
126 
127   // Can't handle unresolved nodes anymore.
128   AllowUnresolvedNodes = false;
129 }
130 
131 /// If N is compile unit return NULL otherwise return N.
132 static DIScope *getNonCompileUnitScope(DIScope *N) {
133   if (!N || isa<DICompileUnit>(N))
134     return nullptr;
135   return cast<DIScope>(N);
136 }
137 
138 DICompileUnit *DIBuilder::createCompileUnit(
139     unsigned Lang, DIFile *File, StringRef Producer, bool isOptimized,
140     StringRef Flags, unsigned RunTimeVer, StringRef SplitName,
141     DICompileUnit::DebugEmissionKind Kind, uint64_t DWOId,
142     bool SplitDebugInlining, bool DebugInfoForProfiling,
143     DICompileUnit::DebugNameTableKind NameTableKind, bool RangesBaseAddress) {
144 
145   assert(((Lang <= dwarf::DW_LANG_Fortran08 && Lang >= dwarf::DW_LANG_C89) ||
146           (Lang <= dwarf::DW_LANG_hi_user && Lang >= dwarf::DW_LANG_lo_user)) &&
147          "Invalid Language tag");
148 
149   assert(!CUNode && "Can only make one compile unit per DIBuilder instance");
150   CUNode = DICompileUnit::getDistinct(
151       VMContext, Lang, File, Producer, isOptimized, Flags, RunTimeVer,
152       SplitName, Kind, nullptr, nullptr, nullptr, nullptr, nullptr, DWOId,
153       SplitDebugInlining, DebugInfoForProfiling, NameTableKind,
154       RangesBaseAddress);
155 
156   // Create a named metadata so that it is easier to find cu in a module.
157   NamedMDNode *NMD = M.getOrInsertNamedMetadata("llvm.dbg.cu");
158   NMD->addOperand(CUNode);
159   trackIfUnresolved(CUNode);
160   return CUNode;
161 }
162 
163 static DIImportedEntity *
164 createImportedModule(LLVMContext &C, dwarf::Tag Tag, DIScope *Context,
165                      Metadata *NS, DIFile *File, unsigned Line, StringRef Name,
166                      SmallVectorImpl<TrackingMDNodeRef> &AllImportedModules) {
167   if (Line)
168     assert(File && "Source location has line number but no file");
169   unsigned EntitiesCount = C.pImpl->DIImportedEntitys.size();
170   auto *M = DIImportedEntity::get(C, Tag, Context, cast_or_null<DINode>(NS),
171                                   File, Line, Name);
172   if (EntitiesCount < C.pImpl->DIImportedEntitys.size())
173     // A new Imported Entity was just added to the context.
174     // Add it to the Imported Modules list.
175     AllImportedModules.emplace_back(M);
176   return M;
177 }
178 
179 DIImportedEntity *DIBuilder::createImportedModule(DIScope *Context,
180                                                   DINamespace *NS, DIFile *File,
181                                                   unsigned Line) {
182   return ::createImportedModule(VMContext, dwarf::DW_TAG_imported_module,
183                                 Context, NS, File, Line, StringRef(),
184                                 AllImportedModules);
185 }
186 
187 DIImportedEntity *DIBuilder::createImportedModule(DIScope *Context,
188                                                   DIImportedEntity *NS,
189                                                   DIFile *File, unsigned Line) {
190   return ::createImportedModule(VMContext, dwarf::DW_TAG_imported_module,
191                                 Context, NS, File, Line, StringRef(),
192                                 AllImportedModules);
193 }
194 
195 DIImportedEntity *DIBuilder::createImportedModule(DIScope *Context, DIModule *M,
196                                                   DIFile *File, unsigned Line) {
197   return ::createImportedModule(VMContext, dwarf::DW_TAG_imported_module,
198                                 Context, M, File, Line, StringRef(),
199                                 AllImportedModules);
200 }
201 
202 DIImportedEntity *DIBuilder::createImportedDeclaration(DIScope *Context,
203                                                        DINode *Decl,
204                                                        DIFile *File,
205                                                        unsigned Line,
206                                                        StringRef Name) {
207   // Make sure to use the unique identifier based metadata reference for
208   // types that have one.
209   return ::createImportedModule(VMContext, dwarf::DW_TAG_imported_declaration,
210                                 Context, Decl, File, Line, Name,
211                                 AllImportedModules);
212 }
213 
214 DIFile *DIBuilder::createFile(StringRef Filename, StringRef Directory,
215                               Optional<DIFile::ChecksumInfo<StringRef>> CS,
216                               Optional<StringRef> Source) {
217   return DIFile::get(VMContext, Filename, Directory, CS, Source);
218 }
219 
220 DIMacro *DIBuilder::createMacro(DIMacroFile *Parent, unsigned LineNumber,
221                                 unsigned MacroType, StringRef Name,
222                                 StringRef Value) {
223   assert(!Name.empty() && "Unable to create macro without name");
224   assert((MacroType == dwarf::DW_MACINFO_undef ||
225           MacroType == dwarf::DW_MACINFO_define) &&
226          "Unexpected macro type");
227   auto *M = DIMacro::get(VMContext, MacroType, LineNumber, Name, Value);
228   AllMacrosPerParent[Parent].insert(M);
229   return M;
230 }
231 
232 DIMacroFile *DIBuilder::createTempMacroFile(DIMacroFile *Parent,
233                                             unsigned LineNumber, DIFile *File) {
234   auto *MF = DIMacroFile::getTemporary(VMContext, dwarf::DW_MACINFO_start_file,
235                                        LineNumber, File, DIMacroNodeArray())
236                  .release();
237   AllMacrosPerParent[Parent].insert(MF);
238   // Add the new temporary DIMacroFile to the macro per parent map as a parent.
239   // This is needed to assure DIMacroFile with no children to have an entry in
240   // the map. Otherwise, it will not be resolved in DIBuilder::finalize().
241   AllMacrosPerParent.insert({MF, {}});
242   return MF;
243 }
244 
245 DIEnumerator *DIBuilder::createEnumerator(StringRef Name, int64_t Val,
246                                           bool IsUnsigned) {
247   assert(!Name.empty() && "Unable to create enumerator without name");
248   return DIEnumerator::get(VMContext, Val, IsUnsigned, Name);
249 }
250 
251 DIBasicType *DIBuilder::createUnspecifiedType(StringRef Name) {
252   assert(!Name.empty() && "Unable to create type without name");
253   return DIBasicType::get(VMContext, dwarf::DW_TAG_unspecified_type, Name);
254 }
255 
256 DIBasicType *DIBuilder::createNullPtrType() {
257   return createUnspecifiedType("decltype(nullptr)");
258 }
259 
260 DIBasicType *DIBuilder::createBasicType(StringRef Name, uint64_t SizeInBits,
261                                         unsigned Encoding,
262                                         DINode::DIFlags Flags) {
263   assert(!Name.empty() && "Unable to create type without name");
264   return DIBasicType::get(VMContext, dwarf::DW_TAG_base_type, Name, SizeInBits,
265                           0, Encoding, Flags);
266 }
267 
268 DIDerivedType *DIBuilder::createQualifiedType(unsigned Tag, DIType *FromTy) {
269   return DIDerivedType::get(VMContext, Tag, "", nullptr, 0, nullptr, FromTy, 0,
270                             0, 0, None, DINode::FlagZero);
271 }
272 
273 DIDerivedType *DIBuilder::createPointerType(
274     DIType *PointeeTy,
275     uint64_t SizeInBits,
276     uint32_t AlignInBits,
277     Optional<unsigned> DWARFAddressSpace,
278     StringRef Name) {
279   // FIXME: Why is there a name here?
280   return DIDerivedType::get(VMContext, dwarf::DW_TAG_pointer_type, Name,
281                             nullptr, 0, nullptr, PointeeTy, SizeInBits,
282                             AlignInBits, 0, DWARFAddressSpace,
283                             DINode::FlagZero);
284 }
285 
286 DIDerivedType *DIBuilder::createMemberPointerType(DIType *PointeeTy,
287                                                   DIType *Base,
288                                                   uint64_t SizeInBits,
289                                                   uint32_t AlignInBits,
290                                                   DINode::DIFlags Flags) {
291   return DIDerivedType::get(VMContext, dwarf::DW_TAG_ptr_to_member_type, "",
292                             nullptr, 0, nullptr, PointeeTy, SizeInBits,
293                             AlignInBits, 0, None, Flags, Base);
294 }
295 
296 DIDerivedType *DIBuilder::createReferenceType(
297     unsigned Tag, DIType *RTy,
298     uint64_t SizeInBits,
299     uint32_t AlignInBits,
300     Optional<unsigned> DWARFAddressSpace) {
301   assert(RTy && "Unable to create reference type");
302   return DIDerivedType::get(VMContext, Tag, "", nullptr, 0, nullptr, RTy,
303                             SizeInBits, AlignInBits, 0, DWARFAddressSpace,
304                             DINode::FlagZero);
305 }
306 
307 DIDerivedType *DIBuilder::createTypedef(DIType *Ty, StringRef Name,
308                                         DIFile *File, unsigned LineNo,
309                                         DIScope *Context,
310                                         uint32_t AlignInBits) {
311   return DIDerivedType::get(VMContext, dwarf::DW_TAG_typedef, Name, File,
312                             LineNo, getNonCompileUnitScope(Context), Ty, 0,
313                             AlignInBits, 0, None, DINode::FlagZero);
314 }
315 
316 DIDerivedType *DIBuilder::createFriend(DIType *Ty, DIType *FriendTy) {
317   assert(Ty && "Invalid type!");
318   assert(FriendTy && "Invalid friend type!");
319   return DIDerivedType::get(VMContext, dwarf::DW_TAG_friend, "", nullptr, 0, Ty,
320                             FriendTy, 0, 0, 0, None, DINode::FlagZero);
321 }
322 
323 DIDerivedType *DIBuilder::createInheritance(DIType *Ty, DIType *BaseTy,
324                                             uint64_t BaseOffset,
325                                             uint32_t VBPtrOffset,
326                                             DINode::DIFlags Flags) {
327   assert(Ty && "Unable to create inheritance");
328   Metadata *ExtraData = ConstantAsMetadata::get(
329       ConstantInt::get(IntegerType::get(VMContext, 32), VBPtrOffset));
330   return DIDerivedType::get(VMContext, dwarf::DW_TAG_inheritance, "", nullptr,
331                             0, Ty, BaseTy, 0, 0, BaseOffset, None,
332                             Flags, ExtraData);
333 }
334 
335 DIDerivedType *DIBuilder::createMemberType(DIScope *Scope, StringRef Name,
336                                            DIFile *File, unsigned LineNumber,
337                                            uint64_t SizeInBits,
338                                            uint32_t AlignInBits,
339                                            uint64_t OffsetInBits,
340                                            DINode::DIFlags Flags, DIType *Ty) {
341   return DIDerivedType::get(VMContext, dwarf::DW_TAG_member, Name, File,
342                             LineNumber, getNonCompileUnitScope(Scope), Ty,
343                             SizeInBits, AlignInBits, OffsetInBits, None, Flags);
344 }
345 
346 static ConstantAsMetadata *getConstantOrNull(Constant *C) {
347   if (C)
348     return ConstantAsMetadata::get(C);
349   return nullptr;
350 }
351 
352 DIDerivedType *DIBuilder::createVariantMemberType(
353     DIScope *Scope, StringRef Name, DIFile *File, unsigned LineNumber,
354     uint64_t SizeInBits, uint32_t AlignInBits, uint64_t OffsetInBits,
355     Constant *Discriminant, DINode::DIFlags Flags, DIType *Ty) {
356   return DIDerivedType::get(VMContext, dwarf::DW_TAG_member, Name, File,
357                             LineNumber, getNonCompileUnitScope(Scope), Ty,
358                             SizeInBits, AlignInBits, OffsetInBits, None, Flags,
359                             getConstantOrNull(Discriminant));
360 }
361 
362 DIDerivedType *DIBuilder::createBitFieldMemberType(
363     DIScope *Scope, StringRef Name, DIFile *File, unsigned LineNumber,
364     uint64_t SizeInBits, uint64_t OffsetInBits, uint64_t StorageOffsetInBits,
365     DINode::DIFlags Flags, DIType *Ty) {
366   Flags |= DINode::FlagBitField;
367   return DIDerivedType::get(
368       VMContext, dwarf::DW_TAG_member, Name, File, LineNumber,
369       getNonCompileUnitScope(Scope), Ty, SizeInBits, /* AlignInBits */ 0,
370       OffsetInBits, None, Flags,
371       ConstantAsMetadata::get(ConstantInt::get(IntegerType::get(VMContext, 64),
372                                                StorageOffsetInBits)));
373 }
374 
375 DIDerivedType *
376 DIBuilder::createStaticMemberType(DIScope *Scope, StringRef Name, DIFile *File,
377                                   unsigned LineNumber, DIType *Ty,
378                                   DINode::DIFlags Flags, llvm::Constant *Val,
379                                   uint32_t AlignInBits) {
380   Flags |= DINode::FlagStaticMember;
381   return DIDerivedType::get(VMContext, dwarf::DW_TAG_member, Name, File,
382                             LineNumber, getNonCompileUnitScope(Scope), Ty, 0,
383                             AlignInBits, 0, None, Flags,
384                             getConstantOrNull(Val));
385 }
386 
387 DIDerivedType *
388 DIBuilder::createObjCIVar(StringRef Name, DIFile *File, unsigned LineNumber,
389                           uint64_t SizeInBits, uint32_t AlignInBits,
390                           uint64_t OffsetInBits, DINode::DIFlags Flags,
391                           DIType *Ty, MDNode *PropertyNode) {
392   return DIDerivedType::get(VMContext, dwarf::DW_TAG_member, Name, File,
393                             LineNumber, getNonCompileUnitScope(File), Ty,
394                             SizeInBits, AlignInBits, OffsetInBits, None, Flags,
395                             PropertyNode);
396 }
397 
398 DIObjCProperty *
399 DIBuilder::createObjCProperty(StringRef Name, DIFile *File, unsigned LineNumber,
400                               StringRef GetterName, StringRef SetterName,
401                               unsigned PropertyAttributes, DIType *Ty) {
402   return DIObjCProperty::get(VMContext, Name, File, LineNumber, GetterName,
403                              SetterName, PropertyAttributes, Ty);
404 }
405 
406 DITemplateTypeParameter *
407 DIBuilder::createTemplateTypeParameter(DIScope *Context, StringRef Name,
408                                        DIType *Ty) {
409   assert((!Context || isa<DICompileUnit>(Context)) && "Expected compile unit");
410   return DITemplateTypeParameter::get(VMContext, Name, Ty);
411 }
412 
413 static DITemplateValueParameter *
414 createTemplateValueParameterHelper(LLVMContext &VMContext, unsigned Tag,
415                                    DIScope *Context, StringRef Name, DIType *Ty,
416                                    Metadata *MD) {
417   assert((!Context || isa<DICompileUnit>(Context)) && "Expected compile unit");
418   return DITemplateValueParameter::get(VMContext, Tag, Name, Ty, MD);
419 }
420 
421 DITemplateValueParameter *
422 DIBuilder::createTemplateValueParameter(DIScope *Context, StringRef Name,
423                                         DIType *Ty, Constant *Val) {
424   return createTemplateValueParameterHelper(
425       VMContext, dwarf::DW_TAG_template_value_parameter, Context, Name, Ty,
426       getConstantOrNull(Val));
427 }
428 
429 DITemplateValueParameter *
430 DIBuilder::createTemplateTemplateParameter(DIScope *Context, StringRef Name,
431                                            DIType *Ty, StringRef Val) {
432   return createTemplateValueParameterHelper(
433       VMContext, dwarf::DW_TAG_GNU_template_template_param, Context, Name, Ty,
434       MDString::get(VMContext, Val));
435 }
436 
437 DITemplateValueParameter *
438 DIBuilder::createTemplateParameterPack(DIScope *Context, StringRef Name,
439                                        DIType *Ty, DINodeArray Val) {
440   return createTemplateValueParameterHelper(
441       VMContext, dwarf::DW_TAG_GNU_template_parameter_pack, Context, Name, Ty,
442       Val.get());
443 }
444 
445 DICompositeType *DIBuilder::createClassType(
446     DIScope *Context, StringRef Name, DIFile *File, unsigned LineNumber,
447     uint64_t SizeInBits, uint32_t AlignInBits, uint64_t OffsetInBits,
448     DINode::DIFlags Flags, DIType *DerivedFrom, DINodeArray Elements,
449     DIType *VTableHolder, MDNode *TemplateParams, StringRef UniqueIdentifier) {
450   assert((!Context || isa<DIScope>(Context)) &&
451          "createClassType should be called with a valid Context");
452 
453   auto *R = DICompositeType::get(
454       VMContext, dwarf::DW_TAG_structure_type, Name, File, LineNumber,
455       getNonCompileUnitScope(Context), DerivedFrom, SizeInBits, AlignInBits,
456       OffsetInBits, Flags, Elements, 0, VTableHolder,
457       cast_or_null<MDTuple>(TemplateParams), UniqueIdentifier);
458   trackIfUnresolved(R);
459   return R;
460 }
461 
462 DICompositeType *DIBuilder::createStructType(
463     DIScope *Context, StringRef Name, DIFile *File, unsigned LineNumber,
464     uint64_t SizeInBits, uint32_t AlignInBits, DINode::DIFlags Flags,
465     DIType *DerivedFrom, DINodeArray Elements, unsigned RunTimeLang,
466     DIType *VTableHolder, StringRef UniqueIdentifier) {
467   auto *R = DICompositeType::get(
468       VMContext, dwarf::DW_TAG_structure_type, Name, File, LineNumber,
469       getNonCompileUnitScope(Context), DerivedFrom, SizeInBits, AlignInBits, 0,
470       Flags, Elements, RunTimeLang, VTableHolder, nullptr, UniqueIdentifier);
471   trackIfUnresolved(R);
472   return R;
473 }
474 
475 DICompositeType *DIBuilder::createUnionType(
476     DIScope *Scope, StringRef Name, DIFile *File, unsigned LineNumber,
477     uint64_t SizeInBits, uint32_t AlignInBits, DINode::DIFlags Flags,
478     DINodeArray Elements, unsigned RunTimeLang, StringRef UniqueIdentifier) {
479   auto *R = DICompositeType::get(
480       VMContext, dwarf::DW_TAG_union_type, Name, File, LineNumber,
481       getNonCompileUnitScope(Scope), nullptr, SizeInBits, AlignInBits, 0, Flags,
482       Elements, RunTimeLang, nullptr, nullptr, UniqueIdentifier);
483   trackIfUnresolved(R);
484   return R;
485 }
486 
487 DICompositeType *DIBuilder::createVariantPart(
488     DIScope *Scope, StringRef Name, DIFile *File, unsigned LineNumber,
489     uint64_t SizeInBits, uint32_t AlignInBits, DINode::DIFlags Flags,
490     DIDerivedType *Discriminator, DINodeArray Elements, StringRef UniqueIdentifier) {
491   auto *R = DICompositeType::get(
492       VMContext, dwarf::DW_TAG_variant_part, Name, File, LineNumber,
493       getNonCompileUnitScope(Scope), nullptr, SizeInBits, AlignInBits, 0, Flags,
494       Elements, 0, nullptr, nullptr, UniqueIdentifier, Discriminator);
495   trackIfUnresolved(R);
496   return R;
497 }
498 
499 DISubroutineType *DIBuilder::createSubroutineType(DITypeRefArray ParameterTypes,
500                                                   DINode::DIFlags Flags,
501                                                   unsigned CC) {
502   return DISubroutineType::get(VMContext, Flags, CC, ParameterTypes);
503 }
504 
505 DICompositeType *DIBuilder::createEnumerationType(
506     DIScope *Scope, StringRef Name, DIFile *File, unsigned LineNumber,
507     uint64_t SizeInBits, uint32_t AlignInBits, DINodeArray Elements,
508     DIType *UnderlyingType, StringRef UniqueIdentifier, bool IsScoped) {
509   auto *CTy = DICompositeType::get(
510       VMContext, dwarf::DW_TAG_enumeration_type, Name, File, LineNumber,
511       getNonCompileUnitScope(Scope), UnderlyingType, SizeInBits, AlignInBits, 0,
512       IsScoped ? DINode::FlagEnumClass : DINode::FlagZero, Elements, 0, nullptr,
513       nullptr, UniqueIdentifier);
514   AllEnumTypes.push_back(CTy);
515   trackIfUnresolved(CTy);
516   return CTy;
517 }
518 
519 DICompositeType *DIBuilder::createArrayType(uint64_t Size,
520                                             uint32_t AlignInBits, DIType *Ty,
521                                             DINodeArray Subscripts) {
522   auto *R = DICompositeType::get(VMContext, dwarf::DW_TAG_array_type, "",
523                                  nullptr, 0, nullptr, Ty, Size, AlignInBits, 0,
524                                  DINode::FlagZero, Subscripts, 0, nullptr);
525   trackIfUnresolved(R);
526   return R;
527 }
528 
529 DICompositeType *DIBuilder::createVectorType(uint64_t Size,
530                                              uint32_t AlignInBits, DIType *Ty,
531                                              DINodeArray Subscripts) {
532   auto *R = DICompositeType::get(VMContext, dwarf::DW_TAG_array_type, "",
533                                  nullptr, 0, nullptr, Ty, Size, AlignInBits, 0,
534                                  DINode::FlagVector, Subscripts, 0, nullptr);
535   trackIfUnresolved(R);
536   return R;
537 }
538 
539 DISubprogram *DIBuilder::createArtificialSubprogram(DISubprogram *SP) {
540   auto NewSP = SP->cloneWithFlags(SP->getFlags() | DINode::FlagArtificial);
541   return MDNode::replaceWithDistinct(std::move(NewSP));
542 }
543 
544 static DIType *createTypeWithFlags(const DIType *Ty,
545                                    DINode::DIFlags FlagsToSet) {
546   auto NewTy = Ty->cloneWithFlags(Ty->getFlags() | FlagsToSet);
547   return MDNode::replaceWithUniqued(std::move(NewTy));
548 }
549 
550 DIType *DIBuilder::createArtificialType(DIType *Ty) {
551   // FIXME: Restrict this to the nodes where it's valid.
552   if (Ty->isArtificial())
553     return Ty;
554   return createTypeWithFlags(Ty, DINode::FlagArtificial);
555 }
556 
557 DIType *DIBuilder::createObjectPointerType(DIType *Ty) {
558   // FIXME: Restrict this to the nodes where it's valid.
559   if (Ty->isObjectPointer())
560     return Ty;
561   DINode::DIFlags Flags = DINode::FlagObjectPointer | DINode::FlagArtificial;
562   return createTypeWithFlags(Ty, Flags);
563 }
564 
565 void DIBuilder::retainType(DIScope *T) {
566   assert(T && "Expected non-null type");
567   assert((isa<DIType>(T) || (isa<DISubprogram>(T) &&
568                              cast<DISubprogram>(T)->isDefinition() == false)) &&
569          "Expected type or subprogram declaration");
570   AllRetainTypes.emplace_back(T);
571 }
572 
573 DIBasicType *DIBuilder::createUnspecifiedParameter() { return nullptr; }
574 
575 DICompositeType *
576 DIBuilder::createForwardDecl(unsigned Tag, StringRef Name, DIScope *Scope,
577                              DIFile *F, unsigned Line, unsigned RuntimeLang,
578                              uint64_t SizeInBits, uint32_t AlignInBits,
579                              StringRef UniqueIdentifier) {
580   // FIXME: Define in terms of createReplaceableForwardDecl() by calling
581   // replaceWithUniqued().
582   auto *RetTy = DICompositeType::get(
583       VMContext, Tag, Name, F, Line, getNonCompileUnitScope(Scope), nullptr,
584       SizeInBits, AlignInBits, 0, DINode::FlagFwdDecl, nullptr, RuntimeLang,
585       nullptr, nullptr, UniqueIdentifier);
586   trackIfUnresolved(RetTy);
587   return RetTy;
588 }
589 
590 DICompositeType *DIBuilder::createReplaceableCompositeType(
591     unsigned Tag, StringRef Name, DIScope *Scope, DIFile *F, unsigned Line,
592     unsigned RuntimeLang, uint64_t SizeInBits, uint32_t AlignInBits,
593     DINode::DIFlags Flags, StringRef UniqueIdentifier) {
594   auto *RetTy =
595       DICompositeType::getTemporary(
596           VMContext, Tag, Name, F, Line, getNonCompileUnitScope(Scope), nullptr,
597           SizeInBits, AlignInBits, 0, Flags, nullptr, RuntimeLang, nullptr,
598           nullptr, UniqueIdentifier)
599           .release();
600   trackIfUnresolved(RetTy);
601   return RetTy;
602 }
603 
604 DINodeArray DIBuilder::getOrCreateArray(ArrayRef<Metadata *> Elements) {
605   return MDTuple::get(VMContext, Elements);
606 }
607 
608 DIMacroNodeArray
609 DIBuilder::getOrCreateMacroArray(ArrayRef<Metadata *> Elements) {
610   return MDTuple::get(VMContext, Elements);
611 }
612 
613 DITypeRefArray DIBuilder::getOrCreateTypeArray(ArrayRef<Metadata *> Elements) {
614   SmallVector<llvm::Metadata *, 16> Elts;
615   for (unsigned i = 0, e = Elements.size(); i != e; ++i) {
616     if (Elements[i] && isa<MDNode>(Elements[i]))
617       Elts.push_back(cast<DIType>(Elements[i]));
618     else
619       Elts.push_back(Elements[i]);
620   }
621   return DITypeRefArray(MDNode::get(VMContext, Elts));
622 }
623 
624 DISubrange *DIBuilder::getOrCreateSubrange(int64_t Lo, int64_t Count) {
625   return DISubrange::get(VMContext, Count, Lo);
626 }
627 
628 DISubrange *DIBuilder::getOrCreateSubrange(int64_t Lo, Metadata *CountNode) {
629   return DISubrange::get(VMContext, CountNode, Lo);
630 }
631 
632 static void checkGlobalVariableScope(DIScope *Context) {
633 #ifndef NDEBUG
634   if (auto *CT =
635           dyn_cast_or_null<DICompositeType>(getNonCompileUnitScope(Context)))
636     assert(CT->getIdentifier().empty() &&
637            "Context of a global variable should not be a type with identifier");
638 #endif
639 }
640 
641 DIGlobalVariableExpression *DIBuilder::createGlobalVariableExpression(
642     DIScope *Context, StringRef Name, StringRef LinkageName, DIFile *F,
643     unsigned LineNumber, DIType *Ty, bool IsLocalToUnit,
644     bool isDefined, DIExpression *Expr,
645     MDNode *Decl, MDTuple *TemplateParams, uint32_t AlignInBits) {
646   checkGlobalVariableScope(Context);
647 
648   auto *GV = DIGlobalVariable::getDistinct(
649       VMContext, cast_or_null<DIScope>(Context), Name, LinkageName, F,
650       LineNumber, Ty, IsLocalToUnit, isDefined, cast_or_null<DIDerivedType>(Decl),
651       TemplateParams, AlignInBits);
652   if (!Expr)
653     Expr = createExpression();
654   auto *N = DIGlobalVariableExpression::get(VMContext, GV, Expr);
655   AllGVs.push_back(N);
656   return N;
657 }
658 
659 DIGlobalVariable *DIBuilder::createTempGlobalVariableFwdDecl(
660     DIScope *Context, StringRef Name, StringRef LinkageName, DIFile *F,
661     unsigned LineNumber, DIType *Ty, bool IsLocalToUnit, MDNode *Decl,
662     MDTuple *TemplateParams, uint32_t AlignInBits) {
663   checkGlobalVariableScope(Context);
664 
665   return DIGlobalVariable::getTemporary(
666              VMContext, cast_or_null<DIScope>(Context), Name, LinkageName, F,
667              LineNumber, Ty, IsLocalToUnit, false,
668              cast_or_null<DIDerivedType>(Decl), TemplateParams, AlignInBits)
669       .release();
670 }
671 
672 static DILocalVariable *createLocalVariable(
673     LLVMContext &VMContext,
674     DenseMap<MDNode *, SmallVector<TrackingMDNodeRef, 1>> &PreservedVariables,
675     DIScope *Scope, StringRef Name, unsigned ArgNo, DIFile *File,
676     unsigned LineNo, DIType *Ty, bool AlwaysPreserve, DINode::DIFlags Flags,
677     uint32_t AlignInBits) {
678   // FIXME: Why getNonCompileUnitScope()?
679   // FIXME: Why is "!Context" okay here?
680   // FIXME: Why doesn't this check for a subprogram or lexical block (AFAICT
681   // the only valid scopes)?
682   DIScope *Context = getNonCompileUnitScope(Scope);
683 
684   auto *Node =
685       DILocalVariable::get(VMContext, cast_or_null<DILocalScope>(Context), Name,
686                            File, LineNo, Ty, ArgNo, Flags, AlignInBits);
687   if (AlwaysPreserve) {
688     // The optimizer may remove local variables. If there is an interest
689     // to preserve variable info in such situation then stash it in a
690     // named mdnode.
691     DISubprogram *Fn = getDISubprogram(Scope);
692     assert(Fn && "Missing subprogram for local variable");
693     PreservedVariables[Fn].emplace_back(Node);
694   }
695   return Node;
696 }
697 
698 DILocalVariable *DIBuilder::createAutoVariable(DIScope *Scope, StringRef Name,
699                                                DIFile *File, unsigned LineNo,
700                                                DIType *Ty, bool AlwaysPreserve,
701                                                DINode::DIFlags Flags,
702                                                uint32_t AlignInBits) {
703   return createLocalVariable(VMContext, PreservedVariables, Scope, Name,
704                              /* ArgNo */ 0, File, LineNo, Ty, AlwaysPreserve,
705                              Flags, AlignInBits);
706 }
707 
708 DILocalVariable *DIBuilder::createParameterVariable(
709     DIScope *Scope, StringRef Name, unsigned ArgNo, DIFile *File,
710     unsigned LineNo, DIType *Ty, bool AlwaysPreserve, DINode::DIFlags Flags) {
711   assert(ArgNo && "Expected non-zero argument number for parameter");
712   return createLocalVariable(VMContext, PreservedVariables, Scope, Name, ArgNo,
713                              File, LineNo, Ty, AlwaysPreserve, Flags,
714                              /* AlignInBits */0);
715 }
716 
717 DILabel *DIBuilder::createLabel(
718     DIScope *Scope, StringRef Name, DIFile *File,
719     unsigned LineNo, bool AlwaysPreserve) {
720   DIScope *Context = getNonCompileUnitScope(Scope);
721 
722   auto *Node =
723       DILabel::get(VMContext, cast_or_null<DILocalScope>(Context), Name,
724                    File, LineNo);
725 
726   if (AlwaysPreserve) {
727     /// The optimizer may remove labels. If there is an interest
728     /// to preserve label info in such situation then append it to
729     /// the list of retained nodes of the DISubprogram.
730     DISubprogram *Fn = getDISubprogram(Scope);
731     assert(Fn && "Missing subprogram for label");
732     PreservedLabels[Fn].emplace_back(Node);
733   }
734   return Node;
735 }
736 
737 DIExpression *DIBuilder::createExpression(ArrayRef<uint64_t> Addr) {
738   return DIExpression::get(VMContext, Addr);
739 }
740 
741 DIExpression *DIBuilder::createExpression(ArrayRef<int64_t> Signed) {
742   // TODO: Remove the callers of this signed version and delete.
743   SmallVector<uint64_t, 8> Addr(Signed.begin(), Signed.end());
744   return createExpression(Addr);
745 }
746 
747 template <class... Ts>
748 static DISubprogram *getSubprogram(bool IsDistinct, Ts &&... Args) {
749   if (IsDistinct)
750     return DISubprogram::getDistinct(std::forward<Ts>(Args)...);
751   return DISubprogram::get(std::forward<Ts>(Args)...);
752 }
753 
754 DISubprogram *DIBuilder::createFunction(
755     DIScope *Context, StringRef Name, StringRef LinkageName, DIFile *File,
756     unsigned LineNo, DISubroutineType *Ty, unsigned ScopeLine,
757     DINode::DIFlags Flags, DISubprogram::DISPFlags SPFlags,
758     DITemplateParameterArray TParams, DISubprogram *Decl,
759     DITypeArray ThrownTypes) {
760   bool IsDefinition = SPFlags & DISubprogram::SPFlagDefinition;
761   auto *Node = getSubprogram(
762       /*IsDistinct=*/IsDefinition, VMContext, getNonCompileUnitScope(Context),
763       Name, LinkageName, File, LineNo, Ty, ScopeLine, nullptr, 0, 0, Flags,
764       SPFlags, IsDefinition ? CUNode : nullptr, TParams, Decl,
765       MDTuple::getTemporary(VMContext, None).release(), ThrownTypes);
766 
767   if (IsDefinition)
768     AllSubprograms.push_back(Node);
769   trackIfUnresolved(Node);
770   return Node;
771 }
772 
773 DISubprogram *DIBuilder::createTempFunctionFwdDecl(
774     DIScope *Context, StringRef Name, StringRef LinkageName, DIFile *File,
775     unsigned LineNo, DISubroutineType *Ty, unsigned ScopeLine,
776     DINode::DIFlags Flags, DISubprogram::DISPFlags SPFlags,
777     DITemplateParameterArray TParams, DISubprogram *Decl,
778     DITypeArray ThrownTypes) {
779   bool IsDefinition = SPFlags & DISubprogram::SPFlagDefinition;
780   return DISubprogram::getTemporary(VMContext, getNonCompileUnitScope(Context),
781                                     Name, LinkageName, File, LineNo, Ty,
782                                     ScopeLine, nullptr, 0, 0, Flags, SPFlags,
783                                     IsDefinition ? CUNode : nullptr, TParams,
784                                     Decl, nullptr, ThrownTypes)
785       .release();
786 }
787 
788 DISubprogram *DIBuilder::createMethod(
789     DIScope *Context, StringRef Name, StringRef LinkageName, DIFile *F,
790     unsigned LineNo, DISubroutineType *Ty, unsigned VIndex, int ThisAdjustment,
791     DIType *VTableHolder, DINode::DIFlags Flags,
792     DISubprogram::DISPFlags SPFlags, DITemplateParameterArray TParams,
793     DITypeArray ThrownTypes) {
794   assert(getNonCompileUnitScope(Context) &&
795          "Methods should have both a Context and a context that isn't "
796          "the compile unit.");
797   // FIXME: Do we want to use different scope/lines?
798   bool IsDefinition = SPFlags & DISubprogram::SPFlagDefinition;
799   auto *SP = getSubprogram(
800       /*IsDistinct=*/IsDefinition, VMContext, cast<DIScope>(Context), Name,
801       LinkageName, F, LineNo, Ty, LineNo, VTableHolder, VIndex, ThisAdjustment,
802       Flags, SPFlags, IsDefinition ? CUNode : nullptr, TParams, nullptr,
803       nullptr, ThrownTypes);
804 
805   if (IsDefinition)
806     AllSubprograms.push_back(SP);
807   trackIfUnresolved(SP);
808   return SP;
809 }
810 
811 DICommonBlock *DIBuilder::createCommonBlock(
812     DIScope *Scope, DIGlobalVariable *Decl, StringRef Name, DIFile *File,
813     unsigned LineNo) {
814   return DICommonBlock::get(
815       VMContext, Scope, Decl, Name, File, LineNo);
816 }
817 
818 DINamespace *DIBuilder::createNameSpace(DIScope *Scope, StringRef Name,
819                                         bool ExportSymbols) {
820 
821   // It is okay to *not* make anonymous top-level namespaces distinct, because
822   // all nodes that have an anonymous namespace as their parent scope are
823   // guaranteed to be unique and/or are linked to their containing
824   // DICompileUnit. This decision is an explicit tradeoff of link time versus
825   // memory usage versus code simplicity and may get revisited in the future.
826   return DINamespace::get(VMContext, getNonCompileUnitScope(Scope), Name,
827                           ExportSymbols);
828 }
829 
830 DIModule *DIBuilder::createModule(DIScope *Scope, StringRef Name,
831                                   StringRef ConfigurationMacros,
832                                   StringRef IncludePath,
833                                   StringRef SysRoot) {
834  return DIModule::get(VMContext, getNonCompileUnitScope(Scope), Name,
835                       ConfigurationMacros, IncludePath, SysRoot);
836 }
837 
838 DILexicalBlockFile *DIBuilder::createLexicalBlockFile(DIScope *Scope,
839                                                       DIFile *File,
840                                                       unsigned Discriminator) {
841   return DILexicalBlockFile::get(VMContext, Scope, File, Discriminator);
842 }
843 
844 DILexicalBlock *DIBuilder::createLexicalBlock(DIScope *Scope, DIFile *File,
845                                               unsigned Line, unsigned Col) {
846   // Make these distinct, to avoid merging two lexical blocks on the same
847   // file/line/column.
848   return DILexicalBlock::getDistinct(VMContext, getNonCompileUnitScope(Scope),
849                                      File, Line, Col);
850 }
851 
852 Instruction *DIBuilder::insertDeclare(Value *Storage, DILocalVariable *VarInfo,
853                                       DIExpression *Expr, const DILocation *DL,
854                                       Instruction *InsertBefore) {
855   return insertDeclare(Storage, VarInfo, Expr, DL, InsertBefore->getParent(),
856                        InsertBefore);
857 }
858 
859 Instruction *DIBuilder::insertDeclare(Value *Storage, DILocalVariable *VarInfo,
860                                       DIExpression *Expr, const DILocation *DL,
861                                       BasicBlock *InsertAtEnd) {
862   // If this block already has a terminator then insert this intrinsic before
863   // the terminator. Otherwise, put it at the end of the block.
864   Instruction *InsertBefore = InsertAtEnd->getTerminator();
865   return insertDeclare(Storage, VarInfo, Expr, DL, InsertAtEnd, InsertBefore);
866 }
867 
868 Instruction *DIBuilder::insertLabel(DILabel *LabelInfo, const DILocation *DL,
869                                     Instruction *InsertBefore) {
870   return insertLabel(
871       LabelInfo, DL, InsertBefore ? InsertBefore->getParent() : nullptr,
872       InsertBefore);
873 }
874 
875 Instruction *DIBuilder::insertLabel(DILabel *LabelInfo, const DILocation *DL,
876                                     BasicBlock *InsertAtEnd) {
877   return insertLabel(LabelInfo, DL, InsertAtEnd, nullptr);
878 }
879 
880 Instruction *DIBuilder::insertDbgValueIntrinsic(Value *V,
881                                                 DILocalVariable *VarInfo,
882                                                 DIExpression *Expr,
883                                                 const DILocation *DL,
884                                                 Instruction *InsertBefore) {
885   return insertDbgValueIntrinsic(
886       V, VarInfo, Expr, DL, InsertBefore ? InsertBefore->getParent() : nullptr,
887       InsertBefore);
888 }
889 
890 Instruction *DIBuilder::insertDbgValueIntrinsic(Value *V,
891                                                 DILocalVariable *VarInfo,
892                                                 DIExpression *Expr,
893                                                 const DILocation *DL,
894                                                 BasicBlock *InsertAtEnd) {
895   return insertDbgValueIntrinsic(V, VarInfo, Expr, DL, InsertAtEnd, nullptr);
896 }
897 
898 /// Return an IRBuilder for inserting dbg.declare and dbg.value intrinsics. This
899 /// abstracts over the various ways to specify an insert position.
900 static IRBuilder<> getIRBForDbgInsertion(const DILocation *DL,
901                                          BasicBlock *InsertBB,
902                                          Instruction *InsertBefore) {
903   IRBuilder<> B(DL->getContext());
904   if (InsertBefore)
905     B.SetInsertPoint(InsertBefore);
906   else if (InsertBB)
907     B.SetInsertPoint(InsertBB);
908   B.SetCurrentDebugLocation(DL);
909   return B;
910 }
911 
912 static Value *getDbgIntrinsicValueImpl(LLVMContext &VMContext, Value *V) {
913   assert(V && "no value passed to dbg intrinsic");
914   return MetadataAsValue::get(VMContext, ValueAsMetadata::get(V));
915 }
916 
917 static Function *getDeclareIntrin(Module &M) {
918   return Intrinsic::getDeclaration(&M, UseDbgAddr ? Intrinsic::dbg_addr
919                                                   : Intrinsic::dbg_declare);
920 }
921 
922 Instruction *DIBuilder::insertDeclare(Value *Storage, DILocalVariable *VarInfo,
923                                       DIExpression *Expr, const DILocation *DL,
924                                       BasicBlock *InsertBB, Instruction *InsertBefore) {
925   assert(VarInfo && "empty or invalid DILocalVariable* passed to dbg.declare");
926   assert(DL && "Expected debug loc");
927   assert(DL->getScope()->getSubprogram() ==
928              VarInfo->getScope()->getSubprogram() &&
929          "Expected matching subprograms");
930   if (!DeclareFn)
931     DeclareFn = getDeclareIntrin(M);
932 
933   trackIfUnresolved(VarInfo);
934   trackIfUnresolved(Expr);
935   Value *Args[] = {getDbgIntrinsicValueImpl(VMContext, Storage),
936                    MetadataAsValue::get(VMContext, VarInfo),
937                    MetadataAsValue::get(VMContext, Expr)};
938 
939   IRBuilder<> B = getIRBForDbgInsertion(DL, InsertBB, InsertBefore);
940   return B.CreateCall(DeclareFn, Args);
941 }
942 
943 Instruction *DIBuilder::insertDbgValueIntrinsic(
944     Value *V, DILocalVariable *VarInfo, DIExpression *Expr,
945     const DILocation *DL, BasicBlock *InsertBB, Instruction *InsertBefore) {
946   assert(V && "no value passed to dbg.value");
947   assert(VarInfo && "empty or invalid DILocalVariable* passed to dbg.value");
948   assert(DL && "Expected debug loc");
949   assert(DL->getScope()->getSubprogram() ==
950              VarInfo->getScope()->getSubprogram() &&
951          "Expected matching subprograms");
952   if (!ValueFn)
953     ValueFn = Intrinsic::getDeclaration(&M, Intrinsic::dbg_value);
954 
955   trackIfUnresolved(VarInfo);
956   trackIfUnresolved(Expr);
957   Value *Args[] = {getDbgIntrinsicValueImpl(VMContext, V),
958                    MetadataAsValue::get(VMContext, VarInfo),
959                    MetadataAsValue::get(VMContext, Expr)};
960 
961   IRBuilder<> B = getIRBForDbgInsertion(DL, InsertBB, InsertBefore);
962   return B.CreateCall(ValueFn, Args);
963 }
964 
965 Instruction *DIBuilder::insertLabel(
966     DILabel *LabelInfo, const DILocation *DL,
967     BasicBlock *InsertBB, Instruction *InsertBefore) {
968   assert(LabelInfo && "empty or invalid DILabel* passed to dbg.label");
969   assert(DL && "Expected debug loc");
970   assert(DL->getScope()->getSubprogram() ==
971              LabelInfo->getScope()->getSubprogram() &&
972          "Expected matching subprograms");
973   if (!LabelFn)
974     LabelFn = Intrinsic::getDeclaration(&M, Intrinsic::dbg_label);
975 
976   trackIfUnresolved(LabelInfo);
977   Value *Args[] = {MetadataAsValue::get(VMContext, LabelInfo)};
978 
979   IRBuilder<> B = getIRBForDbgInsertion(DL, InsertBB, InsertBefore);
980   return B.CreateCall(LabelFn, Args);
981 }
982 
983 void DIBuilder::replaceVTableHolder(DICompositeType *&T,
984                                     DIType *VTableHolder) {
985   {
986     TypedTrackingMDRef<DICompositeType> N(T);
987     N->replaceVTableHolder(VTableHolder);
988     T = N.get();
989   }
990 
991   // If this didn't create a self-reference, just return.
992   if (T != VTableHolder)
993     return;
994 
995   // Look for unresolved operands.  T will drop RAUW support, orphaning any
996   // cycles underneath it.
997   if (T->isResolved())
998     for (const MDOperand &O : T->operands())
999       if (auto *N = dyn_cast_or_null<MDNode>(O))
1000         trackIfUnresolved(N);
1001 }
1002 
1003 void DIBuilder::replaceArrays(DICompositeType *&T, DINodeArray Elements,
1004                               DINodeArray TParams) {
1005   {
1006     TypedTrackingMDRef<DICompositeType> N(T);
1007     if (Elements)
1008       N->replaceElements(Elements);
1009     if (TParams)
1010       N->replaceTemplateParams(DITemplateParameterArray(TParams));
1011     T = N.get();
1012   }
1013 
1014   // If T isn't resolved, there's no problem.
1015   if (!T->isResolved())
1016     return;
1017 
1018   // If T is resolved, it may be due to a self-reference cycle.  Track the
1019   // arrays explicitly if they're unresolved, or else the cycles will be
1020   // orphaned.
1021   if (Elements)
1022     trackIfUnresolved(Elements.get());
1023   if (TParams)
1024     trackIfUnresolved(TParams.get());
1025 }
1026