1 //===--- CGDebugInfo.h - DebugInfo for LLVM CodeGen -------------*- C++ -*-===//
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 is the source-level debug info generator for llvm translation.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #ifndef LLVM_CLANG_LIB_CODEGEN_CGDEBUGINFO_H
15 #define LLVM_CLANG_LIB_CODEGEN_CGDEBUGINFO_H
16 
17 #include "CGBuilder.h"
18 #include "clang/AST/Expr.h"
19 #include "clang/AST/ExternalASTSource.h"
20 #include "clang/AST/Type.h"
21 #include "clang/Basic/SourceLocation.h"
22 #include "clang/Frontend/CodeGenOptions.h"
23 #include "llvm/ADT/DenseMap.h"
24 #include "llvm/ADT/Optional.h"
25 #include "llvm/IR/DIBuilder.h"
26 #include "llvm/IR/DebugInfo.h"
27 #include "llvm/IR/ValueHandle.h"
28 #include "llvm/Support/Allocator.h"
29 
30 namespace llvm {
31 class MDNode;
32 }
33 
34 namespace clang {
35 class CXXMethodDecl;
36 class ClassTemplateSpecializationDecl;
37 class GlobalDecl;
38 class ModuleMap;
39 class ObjCInterfaceDecl;
40 class ObjCIvarDecl;
41 class UsingDecl;
42 class VarDecl;
43 
44 namespace CodeGen {
45 class CodeGenModule;
46 class CodeGenFunction;
47 class CGBlockInfo;
48 
49 /// This class gathers all debug information during compilation and is
50 /// responsible for emitting to llvm globals or pass directly to the
51 /// backend.
52 class CGDebugInfo {
53   friend class ApplyDebugLocation;
54   friend class SaveAndRestoreLocation;
55   CodeGenModule &CGM;
56   const codegenoptions::DebugInfoKind DebugKind;
57   bool DebugTypeExtRefs;
58   llvm::DIBuilder DBuilder;
59   llvm::DICompileUnit *TheCU = nullptr;
60   ModuleMap *ClangModuleMap = nullptr;
61   ExternalASTSource::ASTSourceDescriptor PCHDescriptor;
62   SourceLocation CurLoc;
63   llvm::DIType *VTablePtrType = nullptr;
64   llvm::DIType *ClassTy = nullptr;
65   llvm::DICompositeType *ObjTy = nullptr;
66   llvm::DIType *SelTy = nullptr;
67 #define IMAGE_TYPE(ImgType, Id, SingletonId, Access, Suffix) \
68   llvm::DIType *SingletonId = nullptr;
69 #include "clang/Basic/OpenCLImageTypes.def"
70   llvm::DIType *OCLEventDITy = nullptr;
71   llvm::DIType *OCLClkEventDITy = nullptr;
72   llvm::DIType *OCLQueueDITy = nullptr;
73   llvm::DIType *OCLNDRangeDITy = nullptr;
74   llvm::DIType *OCLReserveIDDITy = nullptr;
75 
76   /// Cache of previously constructed Types.
77   llvm::DenseMap<const void *, llvm::TrackingMDRef> TypeCache;
78 
79   llvm::SmallDenseMap<llvm::StringRef, llvm::StringRef> DebugPrefixMap;
80 
81   struct ObjCInterfaceCacheEntry {
82     const ObjCInterfaceType *Type;
83     llvm::DIType *Decl;
84     llvm::DIFile *Unit;
85     ObjCInterfaceCacheEntry(const ObjCInterfaceType *Type, llvm::DIType *Decl,
86                             llvm::DIFile *Unit)
87         : Type(Type), Decl(Decl), Unit(Unit) {}
88   };
89 
90   /// Cache of previously constructed interfaces which may change.
91   llvm::SmallVector<ObjCInterfaceCacheEntry, 32> ObjCInterfaceCache;
92 
93   /// Cache of references to clang modules and precompiled headers.
94   llvm::DenseMap<const Module *, llvm::TrackingMDRef> ModuleCache;
95 
96   /// List of interfaces we want to keep even if orphaned.
97   std::vector<void *> RetainedTypes;
98 
99   /// Cache of forward declared types to RAUW at the end of
100   /// compilation.
101   std::vector<std::pair<const TagType *, llvm::TrackingMDRef>> ReplaceMap;
102 
103   /// Cache of replaceable forward declarations (functions and
104   /// variables) to RAUW at the end of compilation.
105   std::vector<std::pair<const DeclaratorDecl *, llvm::TrackingMDRef>>
106       FwdDeclReplaceMap;
107 
108   /// Keep track of our current nested lexical block.
109   std::vector<llvm::TypedTrackingMDRef<llvm::DIScope>> LexicalBlockStack;
110   llvm::DenseMap<const Decl *, llvm::TrackingMDRef> RegionMap;
111   /// Keep track of LexicalBlockStack counter at the beginning of a
112   /// function. This is used to pop unbalanced regions at the end of a
113   /// function.
114   std::vector<unsigned> FnBeginRegionCount;
115 
116   /// This is a storage for names that are constructed on demand. For
117   /// example, C++ destructors, C++ operators etc..
118   llvm::BumpPtrAllocator DebugInfoNames;
119   StringRef CWDName;
120 
121   llvm::DenseMap<const char *, llvm::TrackingMDRef> DIFileCache;
122   llvm::DenseMap<const FunctionDecl *, llvm::TrackingMDRef> SPCache;
123   /// Cache declarations relevant to DW_TAG_imported_declarations (C++
124   /// using declarations) that aren't covered by other more specific caches.
125   llvm::DenseMap<const Decl *, llvm::TrackingMDRef> DeclCache;
126   llvm::DenseMap<const NamespaceDecl *, llvm::TrackingMDRef> NameSpaceCache;
127   llvm::DenseMap<const NamespaceAliasDecl *, llvm::TrackingMDRef>
128       NamespaceAliasCache;
129   llvm::DenseMap<const Decl *, llvm::TypedTrackingMDRef<llvm::DIDerivedType>>
130       StaticDataMemberCache;
131 
132   /// Helper functions for getOrCreateType.
133   /// @{
134   /// Currently the checksum of an interface includes the number of
135   /// ivars and property accessors.
136   llvm::DIType *CreateType(const BuiltinType *Ty);
137   llvm::DIType *CreateType(const ComplexType *Ty);
138   llvm::DIType *CreateQualifiedType(QualType Ty, llvm::DIFile *Fg);
139   llvm::DIType *CreateType(const TypedefType *Ty, llvm::DIFile *Fg);
140   llvm::DIType *CreateType(const TemplateSpecializationType *Ty,
141                            llvm::DIFile *Fg);
142   llvm::DIType *CreateType(const ObjCObjectPointerType *Ty, llvm::DIFile *F);
143   llvm::DIType *CreateType(const PointerType *Ty, llvm::DIFile *F);
144   llvm::DIType *CreateType(const BlockPointerType *Ty, llvm::DIFile *F);
145   llvm::DIType *CreateType(const FunctionType *Ty, llvm::DIFile *F);
146   /// Get structure or union type.
147   llvm::DIType *CreateType(const RecordType *Tyg);
148   llvm::DIType *CreateTypeDefinition(const RecordType *Ty);
149   llvm::DICompositeType *CreateLimitedType(const RecordType *Ty);
150   void CollectContainingType(const CXXRecordDecl *RD,
151                              llvm::DICompositeType *CT);
152   /// Get Objective-C interface type.
153   llvm::DIType *CreateType(const ObjCInterfaceType *Ty, llvm::DIFile *F);
154   llvm::DIType *CreateTypeDefinition(const ObjCInterfaceType *Ty,
155                                      llvm::DIFile *F);
156   /// Get Objective-C object type.
157   llvm::DIType *CreateType(const ObjCObjectType *Ty, llvm::DIFile *F);
158   llvm::DIType *CreateType(const VectorType *Ty, llvm::DIFile *F);
159   llvm::DIType *CreateType(const ArrayType *Ty, llvm::DIFile *F);
160   llvm::DIType *CreateType(const LValueReferenceType *Ty, llvm::DIFile *F);
161   llvm::DIType *CreateType(const RValueReferenceType *Ty, llvm::DIFile *Unit);
162   llvm::DIType *CreateType(const MemberPointerType *Ty, llvm::DIFile *F);
163   llvm::DIType *CreateType(const AtomicType *Ty, llvm::DIFile *F);
164   llvm::DIType *CreateType(const PipeType *Ty, llvm::DIFile *F);
165   /// Get enumeration type.
166   llvm::DIType *CreateEnumType(const EnumType *Ty);
167   llvm::DIType *CreateTypeDefinition(const EnumType *Ty);
168   /// Look up the completed type for a self pointer in the TypeCache and
169   /// create a copy of it with the ObjectPointer and Artificial flags
170   /// set. If the type is not cached, a new one is created. This should
171   /// never happen though, since creating a type for the implicit self
172   /// argument implies that we already parsed the interface definition
173   /// and the ivar declarations in the implementation.
174   llvm::DIType *CreateSelfType(const QualType &QualTy, llvm::DIType *Ty);
175   /// @}
176 
177   /// Get the type from the cache or return null type if it doesn't
178   /// exist.
179   llvm::DIType *getTypeOrNull(const QualType);
180   /// Return the debug type for a C++ method.
181   /// \arg CXXMethodDecl is of FunctionType. This function type is
182   /// not updated to include implicit \c this pointer. Use this routine
183   /// to get a method type which includes \c this pointer.
184   llvm::DISubroutineType *getOrCreateMethodType(const CXXMethodDecl *Method,
185                                                 llvm::DIFile *F);
186   llvm::DISubroutineType *
187   getOrCreateInstanceMethodType(QualType ThisPtr, const FunctionProtoType *Func,
188                                 llvm::DIFile *Unit);
189   llvm::DISubroutineType *
190   getOrCreateFunctionType(const Decl *D, QualType FnType, llvm::DIFile *F);
191   /// \return debug info descriptor for vtable.
192   llvm::DIType *getOrCreateVTablePtrType(llvm::DIFile *F);
193   /// \return namespace descriptor for the given namespace decl.
194   llvm::DINamespace *getOrCreateNameSpace(const NamespaceDecl *N);
195   llvm::DIType *CreatePointerLikeType(llvm::dwarf::Tag Tag, const Type *Ty,
196                                       QualType PointeeTy, llvm::DIFile *F);
197   llvm::DIType *getOrCreateStructPtrType(StringRef Name, llvm::DIType *&Cache);
198 
199   /// A helper function to create a subprogram for a single member
200   /// function GlobalDecl.
201   llvm::DISubprogram *CreateCXXMemberFunction(const CXXMethodDecl *Method,
202                                               llvm::DIFile *F,
203                                               llvm::DIType *RecordTy);
204 
205   /// A helper function to collect debug info for C++ member
206   /// functions. This is used while creating debug info entry for a
207   /// Record.
208   void CollectCXXMemberFunctions(const CXXRecordDecl *Decl, llvm::DIFile *F,
209                                  SmallVectorImpl<llvm::Metadata *> &E,
210                                  llvm::DIType *T);
211 
212   /// A helper function to collect debug info for C++ base
213   /// classes. This is used while creating debug info entry for a
214   /// Record.
215   void CollectCXXBases(const CXXRecordDecl *Decl, llvm::DIFile *F,
216                        SmallVectorImpl<llvm::Metadata *> &EltTys,
217                        llvm::DIType *RecordTy);
218 
219   /// A helper function to collect template parameters.
220   llvm::DINodeArray CollectTemplateParams(const TemplateParameterList *TPList,
221                                           ArrayRef<TemplateArgument> TAList,
222                                           llvm::DIFile *Unit);
223   /// A helper function to collect debug info for function template
224   /// parameters.
225   llvm::DINodeArray CollectFunctionTemplateParams(const FunctionDecl *FD,
226                                                   llvm::DIFile *Unit);
227 
228   /// A helper function to collect debug info for template
229   /// parameters.
230   llvm::DINodeArray
231   CollectCXXTemplateParams(const ClassTemplateSpecializationDecl *TS,
232                            llvm::DIFile *F);
233 
234   llvm::DIType *createFieldType(StringRef name, QualType type,
235                                 uint64_t sizeInBitsOverride, SourceLocation loc,
236                                 AccessSpecifier AS, uint64_t offsetInBits,
237                                 llvm::DIFile *tunit, llvm::DIScope *scope,
238                                 const RecordDecl *RD = nullptr);
239 
240   /// Helpers for collecting fields of a record.
241   /// @{
242   void CollectRecordLambdaFields(const CXXRecordDecl *CXXDecl,
243                                  SmallVectorImpl<llvm::Metadata *> &E,
244                                  llvm::DIType *RecordTy);
245   llvm::DIDerivedType *CreateRecordStaticField(const VarDecl *Var,
246                                                llvm::DIType *RecordTy,
247                                                const RecordDecl *RD);
248   void CollectRecordNormalField(const FieldDecl *Field, uint64_t OffsetInBits,
249                                 llvm::DIFile *F,
250                                 SmallVectorImpl<llvm::Metadata *> &E,
251                                 llvm::DIType *RecordTy, const RecordDecl *RD);
252   void CollectRecordFields(const RecordDecl *Decl, llvm::DIFile *F,
253                            SmallVectorImpl<llvm::Metadata *> &E,
254                            llvm::DICompositeType *RecordTy);
255 
256   /// If the C++ class has vtable info then insert appropriate debug
257   /// info entry in EltTys vector.
258   void CollectVTableInfo(const CXXRecordDecl *Decl, llvm::DIFile *F,
259                          SmallVectorImpl<llvm::Metadata *> &EltTys);
260   /// @}
261 
262   /// Create a new lexical block node and push it on the stack.
263   void CreateLexicalBlock(SourceLocation Loc);
264 
265 public:
266   CGDebugInfo(CodeGenModule &CGM);
267   ~CGDebugInfo();
268 
269   void finalize();
270 
271   /// Module debugging: Support for building PCMs.
272   /// @{
273   /// Set the main CU's DwoId field to \p Signature.
274   void setDwoId(uint64_t Signature);
275 
276   /// When generating debug information for a clang module or
277   /// precompiled header, this module map will be used to determine
278   /// the module of origin of each Decl.
279   void setModuleMap(ModuleMap &MMap) { ClangModuleMap = &MMap; }
280 
281   /// When generating debug information for a clang module or
282   /// precompiled header, this module map will be used to determine
283   /// the module of origin of each Decl.
284   void setPCHDescriptor(ExternalASTSource::ASTSourceDescriptor PCH) {
285     PCHDescriptor = PCH;
286   }
287   /// @}
288 
289   /// Update the current source location. If \arg loc is invalid it is
290   /// ignored.
291   void setLocation(SourceLocation Loc);
292 
293   /// Emit metadata to indicate a change in line/column information in
294   /// the source file. If the location is invalid, the previous
295   /// location will be reused.
296   void EmitLocation(CGBuilderTy &Builder, SourceLocation Loc);
297 
298   /// Emit a call to llvm.dbg.function.start to indicate
299   /// start of a new function.
300   /// \param Loc       The location of the function header.
301   /// \param ScopeLoc  The location of the function body.
302   void EmitFunctionStart(GlobalDecl GD, SourceLocation Loc,
303                          SourceLocation ScopeLoc, QualType FnType,
304                          llvm::Function *Fn, CGBuilderTy &Builder);
305 
306   /// Emit debug info for a function declaration.
307   void EmitFunctionDecl(GlobalDecl GD, SourceLocation Loc, QualType FnType);
308 
309   /// Constructs the debug code for exiting a function.
310   void EmitFunctionEnd(CGBuilderTy &Builder);
311 
312   /// Emit metadata to indicate the beginning of a new lexical block
313   /// and push the block onto the stack.
314   void EmitLexicalBlockStart(CGBuilderTy &Builder, SourceLocation Loc);
315 
316   /// Emit metadata to indicate the end of a new lexical block and pop
317   /// the current block.
318   void EmitLexicalBlockEnd(CGBuilderTy &Builder, SourceLocation Loc);
319 
320   /// Emit call to \c llvm.dbg.declare for an automatic variable
321   /// declaration.
322   void EmitDeclareOfAutoVariable(const VarDecl *Decl, llvm::Value *AI,
323                                  CGBuilderTy &Builder);
324 
325   /// Emit call to \c llvm.dbg.declare for an imported variable
326   /// declaration in a block.
327   void EmitDeclareOfBlockDeclRefVariable(const VarDecl *variable,
328                                          llvm::Value *storage,
329                                          CGBuilderTy &Builder,
330                                          const CGBlockInfo &blockInfo,
331                                          llvm::Instruction *InsertPoint = nullptr);
332 
333   /// Emit call to \c llvm.dbg.declare for an argument variable
334   /// declaration.
335   void EmitDeclareOfArgVariable(const VarDecl *Decl, llvm::Value *AI,
336                                 unsigned ArgNo, CGBuilderTy &Builder);
337 
338   /// Emit call to \c llvm.dbg.declare for the block-literal argument
339   /// to a block invocation function.
340   void EmitDeclareOfBlockLiteralArgVariable(const CGBlockInfo &block,
341                                             llvm::Value *Arg, unsigned ArgNo,
342                                             llvm::Value *LocalAddr,
343                                             CGBuilderTy &Builder);
344 
345   /// Emit information about a global variable.
346   void EmitGlobalVariable(llvm::GlobalVariable *GV, const VarDecl *Decl);
347 
348   /// Emit global variable's debug info.
349   void EmitGlobalVariable(const ValueDecl *VD, llvm::Constant *Init);
350 
351   /// Emit C++ using directive.
352   void EmitUsingDirective(const UsingDirectiveDecl &UD);
353 
354   /// Emit the type explicitly casted to.
355   void EmitExplicitCastType(QualType Ty);
356 
357   /// Emit C++ using declaration.
358   void EmitUsingDecl(const UsingDecl &UD);
359 
360   /// Emit an @import declaration.
361   void EmitImportDecl(const ImportDecl &ID);
362 
363   /// Emit C++ namespace alias.
364   llvm::DIImportedEntity *EmitNamespaceAlias(const NamespaceAliasDecl &NA);
365 
366   /// Emit record type's standalone debug info.
367   llvm::DIType *getOrCreateRecordType(QualType Ty, SourceLocation L);
368 
369   /// Emit an Objective-C interface type standalone debug info.
370   llvm::DIType *getOrCreateInterfaceType(QualType Ty, SourceLocation Loc);
371 
372   /// Emit standalone debug info for a type.
373   llvm::DIType *getOrCreateStandaloneType(QualType Ty, SourceLocation Loc);
374 
375   void completeType(const EnumDecl *ED);
376   void completeType(const RecordDecl *RD);
377   void completeRequiredType(const RecordDecl *RD);
378   void completeClassData(const RecordDecl *RD);
379 
380   void completeTemplateDefinition(const ClassTemplateSpecializationDecl &SD);
381 
382 private:
383   /// Emit call to llvm.dbg.declare for a variable declaration.
384   void EmitDeclare(const VarDecl *decl, llvm::Value *AI,
385                    llvm::Optional<unsigned> ArgNo, CGBuilderTy &Builder);
386 
387   /// Build up structure info for the byref.  See \a BuildByRefType.
388   llvm::DIType *EmitTypeForVarWithBlocksAttr(const VarDecl *VD,
389                                              uint64_t *OffSet);
390 
391   /// Get context info for the DeclContext of \p Decl.
392   llvm::DIScope *getDeclContextDescriptor(const Decl *D);
393   /// Get context info for a given DeclContext \p Decl.
394   llvm::DIScope *getContextDescriptor(const Decl *Context,
395                                       llvm::DIScope *Default);
396 
397   llvm::DIScope *getCurrentContextDescriptor(const Decl *Decl);
398 
399   /// Create a forward decl for a RecordType in a given context.
400   llvm::DICompositeType *getOrCreateRecordFwdDecl(const RecordType *,
401                                                   llvm::DIScope *);
402 
403   /// Return current directory name.
404   StringRef getCurrentDirname();
405 
406   /// Create new compile unit.
407   void CreateCompileUnit();
408 
409   /// Remap a given path with the current debug prefix map
410   std::string remapDIPath(StringRef) const;
411 
412   /// Get the file debug info descriptor for the input location.
413   llvm::DIFile *getOrCreateFile(SourceLocation Loc);
414 
415   /// Get the file info for main compile unit.
416   llvm::DIFile *getOrCreateMainFile();
417 
418   /// Get the type from the cache or create a new type if necessary.
419   llvm::DIType *getOrCreateType(QualType Ty, llvm::DIFile *Fg);
420 
421   /// Get a reference to a clang module.  If \p CreateSkeletonCU is true,
422   /// this also creates a split dwarf skeleton compile unit.
423   llvm::DIModule *
424   getOrCreateModuleRef(ExternalASTSource::ASTSourceDescriptor Mod,
425                        bool CreateSkeletonCU);
426 
427   /// DebugTypeExtRefs: If \p D originated in a clang module, return it.
428   llvm::DIModule *getParentModuleOrNull(const Decl *D);
429 
430   /// Get the type from the cache or create a new partial type if
431   /// necessary.
432   llvm::DICompositeType *getOrCreateLimitedType(const RecordType *Ty,
433                                                 llvm::DIFile *F);
434 
435   /// Create type metadata for a source language type.
436   llvm::DIType *CreateTypeNode(QualType Ty, llvm::DIFile *Fg);
437 
438   /// Create new member and increase Offset by FType's size.
439   llvm::DIType *CreateMemberType(llvm::DIFile *Unit, QualType FType,
440                                  StringRef Name, uint64_t *Offset);
441 
442   /// Retrieve the DIDescriptor, if any, for the canonical form of this
443   /// declaration.
444   llvm::DINode *getDeclarationOrDefinition(const Decl *D);
445 
446   /// \return debug info descriptor to describe method
447   /// declaration for the given method definition.
448   llvm::DISubprogram *getFunctionDeclaration(const Decl *D);
449 
450   /// \return debug info descriptor to describe in-class static data
451   /// member declaration for the given out-of-class definition.  If D
452   /// is an out-of-class definition of a static data member of a
453   /// class, find its corresponding in-class declaration.
454   llvm::DIDerivedType *
455   getOrCreateStaticDataMemberDeclarationOrNull(const VarDecl *D);
456 
457   /// Create a subprogram describing the forward declaration
458   /// represented in the given FunctionDecl.
459   llvm::DISubprogram *getFunctionForwardDeclaration(const FunctionDecl *FD);
460 
461   /// Create a global variable describing the forward decalration
462   /// represented in the given VarDecl.
463   llvm::DIGlobalVariable *
464   getGlobalVariableForwardDeclaration(const VarDecl *VD);
465 
466   /// \brief Return a global variable that represents one of the
467   /// collection of global variables created for an anonmyous union.
468   ///
469   /// Recursively collect all of the member fields of a global
470   /// anonymous decl and create static variables for them. The first
471   /// time this is called it needs to be on a union and then from
472   /// there we can have additional unnamed fields.
473   llvm::DIGlobalVariable *
474   CollectAnonRecordDecls(const RecordDecl *RD, llvm::DIFile *Unit,
475                          unsigned LineNo, StringRef LinkageName,
476                          llvm::GlobalVariable *Var, llvm::DIScope *DContext);
477 
478   /// Get function name for the given FunctionDecl. If the name is
479   /// constructed on demand (e.g., C++ destructor) then the name is
480   /// stored on the side.
481   StringRef getFunctionName(const FunctionDecl *FD);
482 
483   /// Returns the unmangled name of an Objective-C method.
484   /// This is the display name for the debugging info.
485   StringRef getObjCMethodName(const ObjCMethodDecl *FD);
486 
487   /// Return selector name. This is used for debugging
488   /// info.
489   StringRef getSelectorName(Selector S);
490 
491   /// Get class name including template argument list.
492   StringRef getClassName(const RecordDecl *RD);
493 
494   /// Get the vtable name for the given class.
495   StringRef getVTableName(const CXXRecordDecl *Decl);
496 
497   /// Get line number for the location. If location is invalid
498   /// then use current location.
499   unsigned getLineNumber(SourceLocation Loc);
500 
501   /// Get column number for the location. If location is
502   /// invalid then use current location.
503   /// \param Force  Assume DebugColumnInfo option is true.
504   unsigned getColumnNumber(SourceLocation Loc, bool Force = false);
505 
506   /// Collect various properties of a FunctionDecl.
507   /// \param GD  A GlobalDecl whose getDecl() must return a FunctionDecl.
508   void collectFunctionDeclProps(GlobalDecl GD, llvm::DIFile *Unit,
509                                 StringRef &Name, StringRef &LinkageName,
510                                 llvm::DIScope *&FDContext,
511                                 llvm::DINodeArray &TParamsArray,
512                                 unsigned &Flags);
513 
514   /// Collect various properties of a VarDecl.
515   void collectVarDeclProps(const VarDecl *VD, llvm::DIFile *&Unit,
516                            unsigned &LineNo, QualType &T, StringRef &Name,
517                            StringRef &LinkageName, llvm::DIScope *&VDContext);
518 
519   /// Allocate a copy of \p A using the DebugInfoNames allocator
520   /// and return a reference to it. If multiple arguments are given the strings
521   /// are concatenated.
522   StringRef internString(StringRef A, StringRef B = StringRef()) {
523     char *Data = DebugInfoNames.Allocate<char>(A.size() + B.size());
524     if (!A.empty())
525       std::memcpy(Data, A.data(), A.size());
526     if (!B.empty())
527       std::memcpy(Data + A.size(), B.data(), B.size());
528     return StringRef(Data, A.size() + B.size());
529   }
530 };
531 
532 /// A scoped helper to set the current debug location to the specified
533 /// location or preferred location of the specified Expr.
534 class ApplyDebugLocation {
535 private:
536   void init(SourceLocation TemporaryLocation, bool DefaultToEmpty = false);
537   ApplyDebugLocation(CodeGenFunction &CGF, bool DefaultToEmpty,
538                      SourceLocation TemporaryLocation);
539 
540   llvm::DebugLoc OriginalLocation;
541   CodeGenFunction *CGF;
542 
543 public:
544   /// Set the location to the (valid) TemporaryLocation.
545   ApplyDebugLocation(CodeGenFunction &CGF, SourceLocation TemporaryLocation);
546   ApplyDebugLocation(CodeGenFunction &CGF, const Expr *E);
547   ApplyDebugLocation(CodeGenFunction &CGF, llvm::DebugLoc Loc);
548   ApplyDebugLocation(ApplyDebugLocation &&Other) : CGF(Other.CGF) {
549     Other.CGF = nullptr;
550   }
551 
552   ~ApplyDebugLocation();
553 
554   /// \brief Apply TemporaryLocation if it is valid. Otherwise switch
555   /// to an artificial debug location that has a valid scope, but no
556   /// line information.
557   ///
558   /// Artificial locations are useful when emitting compiler-generated
559   /// helper functions that have no source location associated with
560   /// them. The DWARF specification allows the compiler to use the
561   /// special line number 0 to indicate code that can not be
562   /// attributed to any source location. Note that passing an empty
563   /// SourceLocation to CGDebugInfo::setLocation() will result in the
564   /// last valid location being reused.
565   static ApplyDebugLocation CreateArtificial(CodeGenFunction &CGF) {
566     return ApplyDebugLocation(CGF, false, SourceLocation());
567   }
568   /// \brief Apply TemporaryLocation if it is valid. Otherwise switch
569   /// to an artificial debug location that has a valid scope, but no
570   /// line information.
571   static ApplyDebugLocation
572   CreateDefaultArtificial(CodeGenFunction &CGF,
573                           SourceLocation TemporaryLocation) {
574     return ApplyDebugLocation(CGF, false, TemporaryLocation);
575   }
576 
577   /// Set the IRBuilder to not attach debug locations.  Note that
578   /// passing an empty SourceLocation to \a CGDebugInfo::setLocation()
579   /// will result in the last valid location being reused.  Note that
580   /// all instructions that do not have a location at the beginning of
581   /// a function are counted towards to function prologue.
582   static ApplyDebugLocation CreateEmpty(CodeGenFunction &CGF) {
583     return ApplyDebugLocation(CGF, true, SourceLocation());
584   }
585 
586 };
587 
588 } // namespace CodeGen
589 } // namespace clang
590 
591 #endif // LLVM_CLANG_LIB_CODEGEN_CGDEBUGINFO_H
592