1 //===-- llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.h ----*- 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 file contains support for writing Microsoft CodeView debug info.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #ifndef LLVM_LIB_CODEGEN_ASMPRINTER_CODEVIEWDEBUG_H
15 #define LLVM_LIB_CODEGEN_ASMPRINTER_CODEVIEWDEBUG_H
16 
17 #include "DebugHandlerBase.h"
18 #include "llvm/ADT/DenseMap.h"
19 #include "llvm/ADT/StringMap.h"
20 #include "llvm/CodeGen/AsmPrinter.h"
21 #include "llvm/CodeGen/MachineFunction.h"
22 #include "llvm/CodeGen/MachineModuleInfo.h"
23 #include "llvm/DebugInfo/CodeView/MemoryTypeTableBuilder.h"
24 #include "llvm/DebugInfo/CodeView/TypeIndex.h"
25 #include "llvm/IR/DebugInfo.h"
26 #include "llvm/IR/DebugLoc.h"
27 #include "llvm/MC/MCStreamer.h"
28 #include "llvm/Target/TargetLoweringObjectFile.h"
29 
30 namespace llvm {
31 
32 class StringRef;
33 class LexicalScope;
34 struct ClassInfo;
35 
36 /// \brief Collects and handles line tables information in a CodeView format.
37 class LLVM_LIBRARY_VISIBILITY CodeViewDebug : public DebugHandlerBase {
38   MCStreamer &OS;
39   llvm::BumpPtrAllocator Allocator;
40   codeview::MemoryTypeTableBuilder TypeTable;
41 
42   /// Represents the most general definition range.
43   struct LocalVarDefRange {
44     /// Indicates that variable data is stored in memory relative to the
45     /// specified register.
46     int InMemory : 1;
47 
48     /// Offset of variable data in memory.
49     int DataOffset : 31;
50 
51     /// Non-zero if this is a piece of an aggregate.
52     uint16_t IsSubfield : 1;
53 
54     /// Offset into aggregate.
55     uint16_t StructOffset : 15;
56 
57     /// Register containing the data or the register base of the memory
58     /// location containing the data.
59     uint16_t CVRegister;
60 
61     /// Compares all location fields. This includes all fields except the label
62     /// ranges.
63     bool isDifferentLocation(LocalVarDefRange &O) {
64       return InMemory != O.InMemory || DataOffset != O.DataOffset ||
65              IsSubfield != O.IsSubfield || StructOffset != O.StructOffset ||
66              CVRegister != O.CVRegister;
67     }
68 
69     SmallVector<std::pair<const MCSymbol *, const MCSymbol *>, 1> Ranges;
70   };
71 
72   static LocalVarDefRange createDefRangeMem(uint16_t CVRegister, int Offset);
73   static LocalVarDefRange createDefRangeGeneral(uint16_t CVRegister,
74                                                 bool InMemory, int Offset,
75                                                 bool IsSubfield,
76                                                 uint16_t StructOffset);
77 
78   /// Similar to DbgVariable in DwarfDebug, but not dwarf-specific.
79   struct LocalVariable {
80     const DILocalVariable *DIVar = nullptr;
81     SmallVector<LocalVarDefRange, 1> DefRanges;
82   };
83 
84   struct InlineSite {
85     SmallVector<LocalVariable, 1> InlinedLocals;
86     SmallVector<const DILocation *, 1> ChildSites;
87     const DISubprogram *Inlinee = nullptr;
88 
89     /// The ID of the inline site or function used with .cv_loc. Not a type
90     /// index.
91     unsigned SiteFuncId = 0;
92   };
93 
94   // For each function, store a vector of labels to its instructions, as well as
95   // to the end of the function.
96   struct FunctionInfo {
97     /// Map from inlined call site to inlined instructions and child inlined
98     /// call sites. Listed in program order.
99     std::unordered_map<const DILocation *, InlineSite> InlineSites;
100 
101     /// Ordered list of top-level inlined call sites.
102     SmallVector<const DILocation *, 1> ChildSites;
103 
104     SmallVector<LocalVariable, 1> Locals;
105 
106     DebugLoc LastLoc;
107     const MCSymbol *Begin = nullptr;
108     const MCSymbol *End = nullptr;
109     unsigned FuncId = 0;
110     unsigned LastFileId = 0;
111     bool HaveLineInfo = false;
112   };
113   FunctionInfo *CurFn;
114 
115   /// The set of comdat .debug$S sections that we've seen so far. Each section
116   /// must start with a magic version number that must only be emitted once.
117   /// This set tracks which sections we've already opened.
118   DenseSet<MCSectionCOFF *> ComdatDebugSections;
119 
120   /// Switch to the appropriate .debug$S section for GVSym. If GVSym, the symbol
121   /// of an emitted global value, is in a comdat COFF section, this will switch
122   /// to a new .debug$S section in that comdat. This method ensures that the
123   /// section starts with the magic version number on first use. If GVSym is
124   /// null, uses the main .debug$S section.
125   void switchToDebugSectionForSymbol(const MCSymbol *GVSym);
126 
127   /// The next available function index for use with our .cv_* directives. Not
128   /// to be confused with type indices for LF_FUNC_ID records.
129   unsigned NextFuncId = 0;
130 
131   InlineSite &getInlineSite(const DILocation *InlinedAt,
132                             const DISubprogram *Inlinee);
133 
134   codeview::TypeIndex getFuncIdForSubprogram(const DISubprogram *SP);
135 
136   static void collectInlineSiteChildren(SmallVectorImpl<unsigned> &Children,
137                                         const FunctionInfo &FI,
138                                         const InlineSite &Site);
139 
140   /// Remember some debug info about each function. Keep it in a stable order to
141   /// emit at the end of the TU.
142   MapVector<const Function *, FunctionInfo> FnDebugInfo;
143 
144   /// Map from DIFile to .cv_file id.
145   DenseMap<const DIFile *, unsigned> FileIdMap;
146 
147   /// All inlined subprograms in the order they should be emitted.
148   SmallSetVector<const DISubprogram *, 4> InlinedSubprograms;
149 
150   /// Map from a pair of DI metadata nodes and its DI type (or scope) that can
151   /// be nullptr, to CodeView type indices. Primarily indexed by
152   /// {DIType*, DIType*} and {DISubprogram*, DIType*}.
153   ///
154   /// The second entry in the key is needed for methods as DISubroutineType
155   /// representing static method type are shared with non-method function type.
156   DenseMap<std::pair<const DINode *, const DIType *>, codeview::TypeIndex>
157       TypeIndices;
158 
159   /// Map from DICompositeType* to complete type index. Non-record types are
160   /// always looked up in the normal TypeIndices map.
161   DenseMap<const DICompositeType *, codeview::TypeIndex> CompleteTypeIndices;
162 
163   /// Complete record types to emit after all active type lowerings are
164   /// finished.
165   SmallVector<const DICompositeType *, 4> DeferredCompleteTypes;
166 
167   /// Number of type lowering frames active on the stack.
168   unsigned TypeEmissionLevel = 0;
169 
170   codeview::TypeIndex VBPType;
171 
172   const DISubprogram *CurrentSubprogram = nullptr;
173 
174   // The UDTs we have seen while processing types; each entry is a pair of type
175   // index and type name.
176   std::vector<std::pair<std::string, codeview::TypeIndex>> LocalUDTs,
177       GlobalUDTs;
178 
179   typedef std::map<const DIFile *, std::string> FileToFilepathMapTy;
180   FileToFilepathMapTy FileToFilepathMap;
181   StringRef getFullFilepath(const DIFile *S);
182 
183   unsigned maybeRecordFile(const DIFile *F);
184 
185   void maybeRecordLocation(const DebugLoc &DL, const MachineFunction *MF);
186 
187   void clear();
188 
189   void setCurrentSubprogram(const DISubprogram *SP) {
190     CurrentSubprogram = SP;
191     LocalUDTs.clear();
192   }
193 
194   /// Emit the magic version number at the start of a CodeView type or symbol
195   /// section. Appears at the front of every .debug$S or .debug$T section.
196   void emitCodeViewMagicVersion();
197 
198   void emitTypeInformation();
199 
200   void emitCompilerInformation();
201 
202   void emitInlineeLinesSubsection();
203 
204   void emitDebugInfoForFunction(const Function *GV, FunctionInfo &FI);
205 
206   void emitDebugInfoForGlobals();
207 
208   void emitDebugInfoForRetainedTypes();
209 
210   void emitDebugInfoForUDTs(
211       ArrayRef<std::pair<std::string, codeview::TypeIndex>> UDTs);
212 
213   void emitDebugInfoForGlobal(const DIGlobalVariable *DIGV,
214                               const GlobalVariable *GV, MCSymbol *GVSym);
215 
216   /// Opens a subsection of the given kind in a .debug$S codeview section.
217   /// Returns an end label for use with endCVSubsection when the subsection is
218   /// finished.
219   MCSymbol *beginCVSubsection(codeview::ModuleSubstreamKind Kind);
220 
221   void endCVSubsection(MCSymbol *EndLabel);
222 
223   void emitInlinedCallSite(const FunctionInfo &FI, const DILocation *InlinedAt,
224                            const InlineSite &Site);
225 
226   typedef DbgValueHistoryMap::InlinedVariable InlinedVariable;
227 
228   void collectVariableInfo(const DISubprogram *SP);
229 
230   void collectVariableInfoFromMMITable(DenseSet<InlinedVariable> &Processed);
231 
232   /// Records information about a local variable in the appropriate scope. In
233   /// particular, locals from inlined code live inside the inlining site.
234   void recordLocalVariable(LocalVariable &&Var, const DILocation *Loc);
235 
236   /// Emits local variables in the appropriate order.
237   void emitLocalVariableList(ArrayRef<LocalVariable> Locals);
238 
239   /// Emits an S_LOCAL record and its associated defined ranges.
240   void emitLocalVariable(const LocalVariable &Var);
241 
242   /// Translates the DIType to codeview if necessary and returns a type index
243   /// for it.
244   codeview::TypeIndex getTypeIndex(DITypeRef TypeRef,
245                                    DITypeRef ClassTyRef = DITypeRef());
246 
247   codeview::TypeIndex getMemberFunctionType(const DISubprogram *SP,
248                                             const DICompositeType *Class);
249 
250   codeview::TypeIndex getScopeIndex(const DIScope *Scope);
251 
252   codeview::TypeIndex getVBPTypeIndex();
253 
254   void addToUDTs(const DIType *Ty, codeview::TypeIndex TI);
255 
256   codeview::TypeIndex lowerType(const DIType *Ty, const DIType *ClassTy);
257   codeview::TypeIndex lowerTypeAlias(const DIDerivedType *Ty);
258   codeview::TypeIndex lowerTypeArray(const DICompositeType *Ty);
259   codeview::TypeIndex lowerTypeBasic(const DIBasicType *Ty);
260   codeview::TypeIndex lowerTypePointer(const DIDerivedType *Ty);
261   codeview::TypeIndex lowerTypeMemberPointer(const DIDerivedType *Ty);
262   codeview::TypeIndex lowerTypeModifier(const DIDerivedType *Ty);
263   codeview::TypeIndex lowerTypeFunction(const DISubroutineType *Ty);
264   codeview::TypeIndex lowerTypeVFTableShape(const DIDerivedType *Ty);
265   codeview::TypeIndex lowerTypeMemberFunction(const DISubroutineType *Ty,
266                                               const DIType *ClassTy,
267                                               int ThisAdjustment);
268   codeview::TypeIndex lowerTypeEnum(const DICompositeType *Ty);
269   codeview::TypeIndex lowerTypeClass(const DICompositeType *Ty);
270   codeview::TypeIndex lowerTypeUnion(const DICompositeType *Ty);
271 
272   /// Symbol records should point to complete types, but type records should
273   /// always point to incomplete types to avoid cycles in the type graph. Only
274   /// use this entry point when generating symbol records. The complete and
275   /// incomplete type indices only differ for record types. All other types use
276   /// the same index.
277   codeview::TypeIndex getCompleteTypeIndex(DITypeRef TypeRef);
278 
279   codeview::TypeIndex lowerCompleteTypeClass(const DICompositeType *Ty);
280   codeview::TypeIndex lowerCompleteTypeUnion(const DICompositeType *Ty);
281 
282   struct TypeLoweringScope;
283 
284   void emitDeferredCompleteTypes();
285 
286   void collectMemberInfo(ClassInfo &Info, const DIDerivedType *DDTy);
287   ClassInfo collectClassInfo(const DICompositeType *Ty);
288 
289   /// Common record member lowering functionality for record types, which are
290   /// structs, classes, and unions. Returns the field list index and the member
291   /// count.
292   std::tuple<codeview::TypeIndex, codeview::TypeIndex, unsigned, bool>
293   lowerRecordFieldList(const DICompositeType *Ty);
294 
295   /// Inserts {{Node, ClassTy}, TI} into TypeIndices and checks for duplicates.
296   codeview::TypeIndex recordTypeIndexForDINode(const DINode *Node,
297                                                codeview::TypeIndex TI,
298                                                const DIType *ClassTy = nullptr);
299 
300   unsigned getPointerSizeInBytes();
301 
302 public:
303   CodeViewDebug(AsmPrinter *Asm);
304 
305   void setSymbolSize(const llvm::MCSymbol *, uint64_t) override {}
306 
307   /// \brief Emit the COFF section that holds the line table information.
308   void endModule() override;
309 
310   /// \brief Gather pre-function debug information.
311   void beginFunction(const MachineFunction *MF) override;
312 
313   /// \brief Gather post-function debug information.
314   void endFunction(const MachineFunction *) override;
315 
316   /// \brief Process beginning of an instruction.
317   void beginInstruction(const MachineInstr *MI) override;
318 };
319 } // End of namespace llvm
320 
321 #endif
322