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/Type.h"
20 #include "clang/Basic/SourceLocation.h"
21 #include "clang/Frontend/CodeGenOptions.h"
22 #include "llvm/ADT/DenseMap.h"
23 #include "llvm/ADT/Optional.h"
24 #include "llvm/IR/DIBuilder.h"
25 #include "llvm/IR/DebugInfo.h"
26 #include "llvm/IR/ValueHandle.h"
27 #include "llvm/Support/Allocator.h"
28 
29 namespace llvm {
30 class MDNode;
31 }
32 
33 namespace clang {
34 class CXXMethodDecl;
35 class VarDecl;
36 class ObjCInterfaceDecl;
37 class ObjCIvarDecl;
38 class ClassTemplateSpecializationDecl;
39 class GlobalDecl;
40 class UsingDecl;
41 
42 namespace CodeGen {
43 class CodeGenModule;
44 class CodeGenFunction;
45 class CGBlockInfo;
46 
47 /// This class gathers all debug information during compilation and is
48 /// responsible for emitting to llvm globals or pass directly to the
49 /// backend.
50 class CGDebugInfo {
51   friend class ApplyDebugLocation;
52   friend class SaveAndRestoreLocation;
53   CodeGenModule &CGM;
54   const CodeGenOptions::DebugInfoKind DebugKind;
55   bool DebugTypeExtRefs;
56   llvm::DIBuilder DBuilder;
57   llvm::DICompileUnit *TheCU = nullptr;
58   SourceLocation CurLoc;
59   llvm::DIType *VTablePtrType = nullptr;
60   llvm::DIType *ClassTy = nullptr;
61   llvm::DICompositeType *ObjTy = nullptr;
62   llvm::DIType *SelTy = nullptr;
63   llvm::DIType *OCLImage1dDITy = nullptr;
64   llvm::DIType *OCLImage1dArrayDITy = nullptr;
65   llvm::DIType *OCLImage1dBufferDITy = nullptr;
66   llvm::DIType *OCLImage2dDITy = nullptr;
67   llvm::DIType *OCLImage2dArrayDITy = nullptr;
68   llvm::DIType *OCLImage2dDepthDITy = nullptr;
69   llvm::DIType *OCLImage2dArrayDepthDITy = nullptr;
70   llvm::DIType *OCLImage2dMSAADITy = nullptr;
71   llvm::DIType *OCLImage2dArrayMSAADITy = nullptr;
72   llvm::DIType *OCLImage2dMSAADepthDITy = nullptr;
73   llvm::DIType *OCLImage2dArrayMSAADepthDITy = nullptr;
74   llvm::DIType *OCLImage3dDITy = nullptr;
75   llvm::DIType *OCLEventDITy = nullptr;
76   llvm::DIType *OCLClkEventDITy = nullptr;
77   llvm::DIType *OCLQueueDITy = nullptr;
78   llvm::DIType *OCLNDRangeDITy = nullptr;
79   llvm::DIType *OCLReserveIDDITy = nullptr;
80 
81   /// Cache of previously constructed Types.
82   llvm::DenseMap<const void *, llvm::TrackingMDRef> TypeCache;
83 
84   struct ObjCInterfaceCacheEntry {
85     const ObjCInterfaceType *Type;
86     llvm::DIType *Decl;
87     llvm::DIFile *Unit;
88     ObjCInterfaceCacheEntry(const ObjCInterfaceType *Type, llvm::DIType *Decl,
89                             llvm::DIFile *Unit)
90         : Type(Type), Decl(Decl), Unit(Unit) {}
91   };
92 
93   /// Cache of previously constructed interfaces which may change.
94   llvm::SmallVector<ObjCInterfaceCacheEntry, 32> ObjCInterfaceCache;
95 
96   /// Cache of references to clang modules and precompiled headers.
97   llvm::StringMap<llvm::TrackingMDRef> ModuleRefCache;
98 
99   /// List of interfaces we want to keep even if orphaned.
100   std::vector<void *> RetainedTypes;
101 
102   /// Cache of forward declared types to RAUW at the end of
103   /// compilation.
104   std::vector<std::pair<const TagType *, llvm::TrackingMDRef>> ReplaceMap;
105 
106   /// Cache of replaceable forward declarartions (functions and
107   /// variables) to RAUW at the end of compilation.
108   std::vector<std::pair<const DeclaratorDecl *, llvm::TrackingMDRef>>
109       FwdDeclReplaceMap;
110 
111   /// Keep track of our current nested lexical block.
112   std::vector<llvm::TypedTrackingMDRef<llvm::DIScope>> LexicalBlockStack;
113   llvm::DenseMap<const Decl *, llvm::TrackingMDRef> RegionMap;
114   /// Keep track of LexicalBlockStack counter at the beginning of a
115   /// function. This is used to pop unbalanced regions at the end of a
116   /// function.
117   std::vector<unsigned> FnBeginRegionCount;
118 
119   /// This is a storage for names that are constructed on demand. For
120   /// example, C++ destructors, C++ operators etc..
121   llvm::BumpPtrAllocator DebugInfoNames;
122   StringRef CWDName;
123 
124   llvm::DenseMap<const char *, llvm::TrackingMDRef> DIFileCache;
125   llvm::DenseMap<const FunctionDecl *, llvm::TrackingMDRef> SPCache;
126   /// Cache declarations relevant to DW_TAG_imported_declarations (C++
127   /// using declarations) that aren't covered by other more specific caches.
128   llvm::DenseMap<const Decl *, llvm::TrackingMDRef> DeclCache;
129   llvm::DenseMap<const NamespaceDecl *, llvm::TrackingMDRef> NameSpaceCache;
130   llvm::DenseMap<const NamespaceAliasDecl *, llvm::TrackingMDRef>
131       NamespaceAliasCache;
132   llvm::DenseMap<const Decl *, llvm::TypedTrackingMDRef<llvm::DIDerivedType>>
133       StaticDataMemberCache;
134 
135   /// Helper functions for getOrCreateType.
136   /// @{
137   /// Currently the checksum of an interface includes the number of
138   /// ivars and property accessors.
139   unsigned Checksum(const ObjCInterfaceDecl *InterfaceDecl);
140   llvm::DIType *CreateType(const BuiltinType *Ty);
141   llvm::DIType *CreateType(const ComplexType *Ty);
142   llvm::DIType *CreateQualifiedType(QualType Ty, llvm::DIFile *Fg);
143   llvm::DIType *CreateType(const TypedefType *Ty, llvm::DIFile *Fg);
144   llvm::DIType *CreateType(const TemplateSpecializationType *Ty,
145                            llvm::DIFile *Fg);
146   llvm::DIType *CreateType(const ObjCObjectPointerType *Ty, llvm::DIFile *F);
147   llvm::DIType *CreateType(const PointerType *Ty, llvm::DIFile *F);
148   llvm::DIType *CreateType(const BlockPointerType *Ty, llvm::DIFile *F);
149   llvm::DIType *CreateType(const FunctionType *Ty, llvm::DIFile *F);
150   /// Get structure or union type.
151   llvm::DIType *CreateType(const RecordType *Tyg);
152   llvm::DIType *CreateTypeDefinition(const RecordType *Ty);
153   llvm::DICompositeType *CreateLimitedType(const RecordType *Ty);
154   void CollectContainingType(const CXXRecordDecl *RD,
155                              llvm::DICompositeType *CT);
156   /// Get Objective-C interface type.
157   llvm::DIType *CreateType(const ObjCInterfaceType *Ty, llvm::DIFile *F);
158   llvm::DIType *CreateTypeDefinition(const ObjCInterfaceType *Ty,
159                                      llvm::DIFile *F);
160   /// Get Objective-C object type.
161   llvm::DIType *CreateType(const ObjCObjectType *Ty, llvm::DIFile *F);
162   llvm::DIType *CreateType(const VectorType *Ty, llvm::DIFile *F);
163   llvm::DIType *CreateType(const ArrayType *Ty, llvm::DIFile *F);
164   llvm::DIType *CreateType(const LValueReferenceType *Ty, llvm::DIFile *F);
165   llvm::DIType *CreateType(const RValueReferenceType *Ty, llvm::DIFile *Unit);
166   llvm::DIType *CreateType(const MemberPointerType *Ty, llvm::DIFile *F);
167   llvm::DIType *CreateType(const AtomicType *Ty, llvm::DIFile *F);
168   /// Get enumeration type.
169   llvm::DIType *CreateEnumType(const EnumType *Ty);
170   llvm::DIType *CreateTypeDefinition(const EnumType *Ty);
171   /// Look up the completed type for a self pointer in the TypeCache and
172   /// create a copy of it with the ObjectPointer and Artificial flags
173   /// set. If the type is not cached, a new one is created. This should
174   /// never happen though, since creating a type for the implicit self
175   /// argument implies that we already parsed the interface definition
176   /// and the ivar declarations in the implementation.
177   llvm::DIType *CreateSelfType(const QualType &QualTy, llvm::DIType *Ty);
178   /// @}
179 
180   /// Get the type from the cache or return null type if it doesn't
181   /// exist.
182   llvm::DIType *getTypeOrNull(const QualType);
183   /// Return the debug type for a C++ method.
184   /// \arg CXXMethodDecl is of FunctionType. This function type is
185   /// not updated to include implicit \c this pointer. Use this routine
186   /// to get a method type which includes \c this pointer.
187   llvm::DISubroutineType *getOrCreateMethodType(const CXXMethodDecl *Method,
188                                                 llvm::DIFile *F);
189   llvm::DISubroutineType *
190   getOrCreateInstanceMethodType(QualType ThisPtr, const FunctionProtoType *Func,
191                                 llvm::DIFile *Unit);
192   llvm::DISubroutineType *
193   getOrCreateFunctionType(const Decl *D, QualType FnType, llvm::DIFile *F);
194   /// \return debug info descriptor for vtable.
195   llvm::DIType *getOrCreateVTablePtrType(llvm::DIFile *F);
196   /// \return namespace descriptor for the given namespace decl.
197   llvm::DINamespace *getOrCreateNameSpace(const NamespaceDecl *N);
198   llvm::DIType *getOrCreateTypeDeclaration(QualType PointeeTy, llvm::DIFile *F);
199   llvm::DIType *CreatePointerLikeType(llvm::dwarf::Tag Tag, const Type *Ty,
200                                       QualType PointeeTy, llvm::DIFile *F);
201 
202   llvm::Value *getCachedInterfaceTypeOrNull(const QualType Ty);
203   llvm::DIType *getOrCreateStructPtrType(StringRef Name, llvm::DIType *&Cache);
204 
205   /// A helper function to create a subprogram for a single member
206   /// function GlobalDecl.
207   llvm::DISubprogram *CreateCXXMemberFunction(const CXXMethodDecl *Method,
208                                               llvm::DIFile *F,
209                                               llvm::DIType *RecordTy);
210 
211   /// A helper function to collect debug info for C++ member
212   /// functions. This is used while creating debug info entry for a
213   /// Record.
214   void CollectCXXMemberFunctions(const CXXRecordDecl *Decl, llvm::DIFile *F,
215                                  SmallVectorImpl<llvm::Metadata *> &E,
216                                  llvm::DIType *T);
217 
218   /// A helper function to collect debug info for C++ base
219   /// classes. This is used while creating debug info entry for a
220   /// Record.
221   void CollectCXXBases(const CXXRecordDecl *Decl, llvm::DIFile *F,
222                        SmallVectorImpl<llvm::Metadata *> &EltTys,
223                        llvm::DIType *RecordTy);
224 
225   /// A helper function to collect template parameters.
226   llvm::DINodeArray CollectTemplateParams(const TemplateParameterList *TPList,
227                                           ArrayRef<TemplateArgument> TAList,
228                                           llvm::DIFile *Unit);
229   /// A helper function to collect debug info for function template
230   /// parameters.
231   llvm::DINodeArray CollectFunctionTemplateParams(const FunctionDecl *FD,
232                                                   llvm::DIFile *Unit);
233 
234   /// A helper function to collect debug info for template
235   /// parameters.
236   llvm::DINodeArray
237   CollectCXXTemplateParams(const ClassTemplateSpecializationDecl *TS,
238                            llvm::DIFile *F);
239 
240   llvm::DIType *createFieldType(StringRef name, QualType type,
241                                 uint64_t sizeInBitsOverride, SourceLocation loc,
242                                 AccessSpecifier AS, uint64_t offsetInBits,
243                                 llvm::DIFile *tunit, llvm::DIScope *scope,
244                                 const RecordDecl *RD = nullptr);
245 
246   /// Helpers for collecting fields of a record.
247   /// @{
248   void CollectRecordLambdaFields(const CXXRecordDecl *CXXDecl,
249                                  SmallVectorImpl<llvm::Metadata *> &E,
250                                  llvm::DIType *RecordTy);
251   llvm::DIDerivedType *CreateRecordStaticField(const VarDecl *Var,
252                                                llvm::DIType *RecordTy,
253                                                const RecordDecl *RD);
254   void CollectRecordNormalField(const FieldDecl *Field, uint64_t OffsetInBits,
255                                 llvm::DIFile *F,
256                                 SmallVectorImpl<llvm::Metadata *> &E,
257                                 llvm::DIType *RecordTy, const RecordDecl *RD);
258   void CollectRecordFields(const RecordDecl *Decl, llvm::DIFile *F,
259                            SmallVectorImpl<llvm::Metadata *> &E,
260                            llvm::DICompositeType *RecordTy);
261 
262   /// If the C++ class has vtable info then insert appropriate debug
263   /// info entry in EltTys vector.
264   void CollectVTableInfo(const CXXRecordDecl *Decl, llvm::DIFile *F,
265                          SmallVectorImpl<llvm::Metadata *> &EltTys);
266   /// @}
267 
268   /// Create a new lexical block node and push it on the stack.
269   void CreateLexicalBlock(SourceLocation Loc);
270 
271 public:
272   CGDebugInfo(CodeGenModule &CGM);
273   ~CGDebugInfo();
274 
275   void finalize();
276 
277   /// Update the current source location. If \arg loc is invalid it is
278   /// ignored.
279   void setLocation(SourceLocation Loc);
280 
281   /// Emit metadata to indicate a change in line/column information in
282   /// the source file. If the location is invalid, the previous
283   /// location will be reused.
284   void EmitLocation(CGBuilderTy &Builder, SourceLocation Loc);
285 
286   /// Emit a call to llvm.dbg.function.start to indicate
287   /// start of a new function.
288   /// \param Loc       The location of the function header.
289   /// \param ScopeLoc  The location of the function body.
290   void EmitFunctionStart(GlobalDecl GD, SourceLocation Loc,
291                          SourceLocation ScopeLoc, QualType FnType,
292                          llvm::Function *Fn, CGBuilderTy &Builder);
293 
294   /// Emit debug info for a function declaration.
295   void EmitFunctionDecl(GlobalDecl GD, SourceLocation Loc, QualType FnType);
296 
297   /// Constructs the debug code for exiting a function.
298   void EmitFunctionEnd(CGBuilderTy &Builder);
299 
300   /// Emit metadata to indicate the beginning of a new lexical block
301   /// and push the block onto the stack.
302   void EmitLexicalBlockStart(CGBuilderTy &Builder, SourceLocation Loc);
303 
304   /// Emit metadata to indicate the end of a new lexical block and pop
305   /// the current block.
306   void EmitLexicalBlockEnd(CGBuilderTy &Builder, SourceLocation Loc);
307 
308   /// Emit call to \c llvm.dbg.declare for an automatic variable
309   /// declaration.
310   void EmitDeclareOfAutoVariable(const VarDecl *Decl, llvm::Value *AI,
311                                  CGBuilderTy &Builder);
312 
313   /// Emit call to \c llvm.dbg.declare for an imported variable
314   /// declaration in a block.
315   void EmitDeclareOfBlockDeclRefVariable(const VarDecl *variable,
316                                          llvm::Value *storage,
317                                          CGBuilderTy &Builder,
318                                          const CGBlockInfo &blockInfo,
319                                          llvm::Instruction *InsertPoint = 0);
320 
321   /// Emit call to \c llvm.dbg.declare for an argument variable
322   /// declaration.
323   void EmitDeclareOfArgVariable(const VarDecl *Decl, llvm::Value *AI,
324                                 unsigned ArgNo, CGBuilderTy &Builder);
325 
326   /// Emit call to \c llvm.dbg.declare for the block-literal argument
327   /// to a block invocation function.
328   void EmitDeclareOfBlockLiteralArgVariable(const CGBlockInfo &block,
329                                             llvm::Value *Arg, unsigned ArgNo,
330                                             llvm::Value *LocalAddr,
331                                             CGBuilderTy &Builder);
332 
333   /// Emit information about a global variable.
334   void EmitGlobalVariable(llvm::GlobalVariable *GV, const VarDecl *Decl);
335 
336   /// Emit global variable's debug info.
337   void EmitGlobalVariable(const ValueDecl *VD, llvm::Constant *Init);
338 
339   /// Emit C++ using directive.
340   void EmitUsingDirective(const UsingDirectiveDecl &UD);
341 
342   /// Emit the type explicitly casted to.
343   void EmitExplicitCastType(QualType Ty);
344 
345   /// Emit C++ using declaration.
346   void EmitUsingDecl(const UsingDecl &UD);
347 
348   /// Emit an @import declaration.
349   void EmitImportDecl(const ImportDecl &ID);
350 
351   /// Emit C++ namespace alias.
352   llvm::DIImportedEntity *EmitNamespaceAlias(const NamespaceAliasDecl &NA);
353 
354   /// Emit record type's standalone debug info.
355   llvm::DIType *getOrCreateRecordType(QualType Ty, SourceLocation L);
356 
357   /// Emit an Objective-C interface type standalone debug info.
358   llvm::DIType *getOrCreateInterfaceType(QualType Ty, SourceLocation Loc);
359 
360   /// Emit standalone debug info for a type.
361   llvm::DIType *getOrCreateStandaloneType(QualType Ty, SourceLocation Loc);
362 
363   void completeType(const EnumDecl *ED);
364   void completeType(const RecordDecl *RD);
365   void completeRequiredType(const RecordDecl *RD);
366   void completeClassData(const RecordDecl *RD);
367 
368   void completeTemplateDefinition(const ClassTemplateSpecializationDecl &SD);
369 
370 private:
371   /// Emit call to llvm.dbg.declare for a variable declaration.
372   void EmitDeclare(const VarDecl *decl, llvm::Value *AI,
373                    llvm::Optional<unsigned> ArgNo, CGBuilderTy &Builder);
374 
375   /// Build up structure info for the byref.  See \a BuildByRefType.
376   llvm::DIType *EmitTypeForVarWithBlocksAttr(const VarDecl *VD,
377                                              uint64_t *OffSet);
378 
379   /// Get context info for the DeclContext of \p Decl.
380   llvm::DIScope *getDeclContextDescriptor(const Decl *D);
381   /// Get context info for a given DeclContext \p Decl.
382   llvm::DIScope *getContextDescriptor(const Decl *Context,
383                                       llvm::DIScope *Default);
384 
385   llvm::DIScope *getCurrentContextDescriptor(const Decl *Decl);
386 
387   /// Create a forward decl for a RecordType in a given context.
388   llvm::DICompositeType *getOrCreateRecordFwdDecl(const RecordType *,
389                                                   llvm::DIScope *);
390 
391   /// Return current directory name.
392   StringRef getCurrentDirname();
393 
394   /// Create new compile unit.
395   void CreateCompileUnit();
396 
397   /// Get the file debug info descriptor for the input location.
398   llvm::DIFile *getOrCreateFile(SourceLocation Loc);
399 
400   /// Get the file info for main compile unit.
401   llvm::DIFile *getOrCreateMainFile();
402 
403   /// Get the type from the cache or create a new type if necessary.
404   llvm::DIType *getOrCreateType(QualType Ty, llvm::DIFile *Fg);
405 
406   /// Get a reference to a clang module.  If \p CreateSkeletonCU is true,
407   /// this also creates a split dwarf skeleton compile unit.
408   llvm::DIModule *
409   getOrCreateModuleRef(ExternalASTSource::ASTSourceDescriptor Mod,
410                        bool CreateSkeletonCU);
411 
412   /// DebugTypeExtRefs: If \p D originated in a clang module, return it.
413   llvm::DIModule *getParentModuleOrNull(const Decl *D);
414 
415   /// Get the type from the cache or create a new partial type if
416   /// necessary.
417   llvm::DICompositeType *getOrCreateLimitedType(const RecordType *Ty,
418                                                 llvm::DIFile *F);
419 
420   /// Create type metadata for a source language type.
421   llvm::DIType *CreateTypeNode(QualType Ty, llvm::DIFile *Fg);
422 
423   /// Return the underlying ObjCInterfaceDecl if \arg Ty is an
424   /// ObjCInterface or a pointer to one.
425   ObjCInterfaceDecl *getObjCInterfaceDecl(QualType Ty);
426 
427   /// Create new member and increase Offset by FType's size.
428   llvm::DIType *CreateMemberType(llvm::DIFile *Unit, QualType FType,
429                                  StringRef Name, uint64_t *Offset);
430 
431   /// Retrieve the DIDescriptor, if any, for the canonical form of this
432   /// declaration.
433   llvm::DINode *getDeclarationOrDefinition(const Decl *D);
434 
435   /// \return debug info descriptor to describe method
436   /// declaration for the given method definition.
437   llvm::DISubprogram *getFunctionDeclaration(const Decl *D);
438 
439   /// \return debug info descriptor to describe in-class static data
440   /// member declaration for the given out-of-class definition.  If D
441   /// is an out-of-class definition of a static data member of a
442   /// class, find its corresponding in-class declaration.
443   llvm::DIDerivedType *
444   getOrCreateStaticDataMemberDeclarationOrNull(const VarDecl *D);
445 
446   /// Create a subprogram describing the forward declaration
447   /// represented in the given FunctionDecl.
448   llvm::DISubprogram *getFunctionForwardDeclaration(const FunctionDecl *FD);
449 
450   /// Create a global variable describing the forward decalration
451   /// represented in the given VarDecl.
452   llvm::DIGlobalVariable *
453   getGlobalVariableForwardDeclaration(const VarDecl *VD);
454 
455   /// \brief Return a global variable that represents one of the
456   /// collection of global variables created for an anonmyous union.
457   ///
458   /// Recursively collect all of the member fields of a global
459   /// anonymous decl and create static variables for them. The first
460   /// time this is called it needs to be on a union and then from
461   /// there we can have additional unnamed fields.
462   llvm::DIGlobalVariable *
463   CollectAnonRecordDecls(const RecordDecl *RD, llvm::DIFile *Unit,
464                          unsigned LineNo, StringRef LinkageName,
465                          llvm::GlobalVariable *Var, llvm::DIScope *DContext);
466 
467   /// Get function name for the given FunctionDecl. If the name is
468   /// constructed on demand (e.g., C++ destructor) then the name is
469   /// stored on the side.
470   StringRef getFunctionName(const FunctionDecl *FD);
471 
472   /// Returns the unmangled name of an Objective-C method.
473   /// This is the display name for the debugging info.
474   StringRef getObjCMethodName(const ObjCMethodDecl *FD);
475 
476   /// Return selector name. This is used for debugging
477   /// info.
478   StringRef getSelectorName(Selector S);
479 
480   /// Get class name including template argument list.
481   StringRef getClassName(const RecordDecl *RD);
482 
483   /// Get the vtable name for the given class.
484   StringRef getVTableName(const CXXRecordDecl *Decl);
485 
486   /// Get line number for the location. If location is invalid
487   /// then use current location.
488   unsigned getLineNumber(SourceLocation Loc);
489 
490   /// Get column number for the location. If location is
491   /// invalid then use current location.
492   /// \param Force  Assume DebugColumnInfo option is true.
493   unsigned getColumnNumber(SourceLocation Loc, bool Force = false);
494 
495   /// Collect various properties of a FunctionDecl.
496   /// \param GD  A GlobalDecl whose getDecl() must return a FunctionDecl.
497   void collectFunctionDeclProps(GlobalDecl GD, llvm::DIFile *Unit,
498                                 StringRef &Name, StringRef &LinkageName,
499                                 llvm::DIScope *&FDContext,
500                                 llvm::DINodeArray &TParamsArray,
501                                 unsigned &Flags);
502 
503   /// Collect various properties of a VarDecl.
504   void collectVarDeclProps(const VarDecl *VD, llvm::DIFile *&Unit,
505                            unsigned &LineNo, QualType &T, StringRef &Name,
506                            StringRef &LinkageName, llvm::DIScope *&VDContext);
507 
508   /// Allocate a copy of \p A using the DebugInfoNames allocator
509   /// and return a reference to it. If multiple arguments are given the strings
510   /// are concatenated.
511   StringRef internString(StringRef A, StringRef B = StringRef()) {
512     char *Data = DebugInfoNames.Allocate<char>(A.size() + B.size());
513     if (!A.empty())
514       std::memcpy(Data, A.data(), A.size());
515     if (!B.empty())
516       std::memcpy(Data + A.size(), B.data(), B.size());
517     return StringRef(Data, A.size() + B.size());
518   }
519 };
520 
521 /// A scoped helper to set the current debug location to the specified
522 /// location or preferred location of the specified Expr.
523 class ApplyDebugLocation {
524 private:
525   void init(SourceLocation TemporaryLocation, bool DefaultToEmpty = false);
526   ApplyDebugLocation(CodeGenFunction &CGF, bool DefaultToEmpty,
527                      SourceLocation TemporaryLocation);
528 
529   llvm::DebugLoc OriginalLocation;
530   CodeGenFunction *CGF;
531 
532 public:
533   /// Set the location to the (valid) TemporaryLocation.
534   ApplyDebugLocation(CodeGenFunction &CGF, SourceLocation TemporaryLocation);
535   ApplyDebugLocation(CodeGenFunction &CGF, const Expr *E);
536   ApplyDebugLocation(CodeGenFunction &CGF, llvm::DebugLoc Loc);
537   ApplyDebugLocation(ApplyDebugLocation &&Other) : CGF(Other.CGF) {
538     Other.CGF = nullptr;
539   }
540 
541   ~ApplyDebugLocation();
542 
543   /// \brief Apply TemporaryLocation if it is valid. Otherwise switch
544   /// to an artificial debug location that has a valid scope, but no
545   /// line information.
546   ///
547   /// Artificial locations are useful when emitting compiler-generated
548   /// helper functions that have no source location associated with
549   /// them. The DWARF specification allows the compiler to use the
550   /// special line number 0 to indicate code that can not be
551   /// attributed to any source location. Note that passing an empty
552   /// SourceLocation to CGDebugInfo::setLocation() will result in the
553   /// last valid location being reused.
554   static ApplyDebugLocation CreateArtificial(CodeGenFunction &CGF) {
555     return ApplyDebugLocation(CGF, false, SourceLocation());
556   }
557   /// \brief Apply TemporaryLocation if it is valid. Otherwise switch
558   /// to an artificial debug location that has a valid scope, but no
559   /// line information.
560   static ApplyDebugLocation
561   CreateDefaultArtificial(CodeGenFunction &CGF,
562                           SourceLocation TemporaryLocation) {
563     return ApplyDebugLocation(CGF, false, TemporaryLocation);
564   }
565 
566   /// Set the IRBuilder to not attach debug locations.  Note that
567   /// passing an empty SourceLocation to \a CGDebugInfo::setLocation()
568   /// will result in the last valid location being reused.  Note that
569   /// all instructions that do not have a location at the beginning of
570   /// a function are counted towards to funciton prologue.
571   static ApplyDebugLocation CreateEmpty(CodeGenFunction &CGF) {
572     return ApplyDebugLocation(CGF, true, SourceLocation());
573   }
574 
575   /// \brief Apply TemporaryLocation if it is valid. Otherwise set the IRBuilder
576   /// to not attach debug locations.
577   static ApplyDebugLocation
578   CreateDefaultEmpty(CodeGenFunction &CGF, SourceLocation TemporaryLocation) {
579     return ApplyDebugLocation(CGF, true, TemporaryLocation);
580   }
581 };
582 
583 } // namespace CodeGen
584 } // namespace clang
585 
586 #endif
587