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 "DbgValueHistoryCalculator.h"
18 #include "DebugHandlerBase.h"
19 #include "llvm/ADT/ArrayRef.h"
20 #include "llvm/ADT/DenseMap.h"
21 #include "llvm/ADT/DenseSet.h"
22 #include "llvm/ADT/MapVector.h"
23 #include "llvm/ADT/SetVector.h"
24 #include "llvm/ADT/SmallVector.h"
25 #include "llvm/DebugInfo/CodeView/CodeView.h"
26 #include "llvm/DebugInfo/CodeView/TypeIndex.h"
27 #include "llvm/DebugInfo/CodeView/TypeTableBuilder.h"
28 #include "llvm/IR/DebugLoc.h"
29 #include "llvm/Support/Allocator.h"
30 #include "llvm/Support/Compiler.h"
31 #include <cstdint>
32 #include <map>
33 #include <string>
34 #include <tuple>
35 #include <unordered_map>
36 #include <utility>
37 #include <vector>
38 
39 namespace llvm {
40 
41 struct ClassInfo;
42 class StringRef;
43 class AsmPrinter;
44 class Function;
45 class GlobalVariable;
46 class MCSectionCOFF;
47 class MCStreamer;
48 class MCSymbol;
49 class MachineFunction;
50 
51 /// \brief Collects and handles line tables information in a CodeView format.
52 class LLVM_LIBRARY_VISIBILITY CodeViewDebug : public DebugHandlerBase {
53   MCStreamer &OS;
54   BumpPtrAllocator Allocator;
55   codeview::TypeTableBuilder TypeTable;
56 
57   /// Represents the most general definition range.
58   struct LocalVarDefRange {
59     /// Indicates that variable data is stored in memory relative to the
60     /// specified register.
61     int InMemory : 1;
62 
63     /// Offset of variable data in memory.
64     int DataOffset : 31;
65 
66     /// Non-zero if this is a piece of an aggregate.
67     uint16_t IsSubfield : 1;
68 
69     /// Offset into aggregate.
70     uint16_t StructOffset : 15;
71 
72     /// Register containing the data or the register base of the memory
73     /// location containing the data.
74     uint16_t CVRegister;
75 
76     /// Compares all location fields. This includes all fields except the label
77     /// ranges.
78     bool isDifferentLocation(LocalVarDefRange &O) {
79       return InMemory != O.InMemory || DataOffset != O.DataOffset ||
80              IsSubfield != O.IsSubfield || StructOffset != O.StructOffset ||
81              CVRegister != O.CVRegister;
82     }
83 
84     SmallVector<std::pair<const MCSymbol *, const MCSymbol *>, 1> Ranges;
85   };
86 
87   static LocalVarDefRange createDefRangeMem(uint16_t CVRegister, int Offset);
88   static LocalVarDefRange createDefRangeGeneral(uint16_t CVRegister,
89                                                 bool InMemory, int Offset,
90                                                 bool IsSubfield,
91                                                 uint16_t StructOffset);
92 
93   /// Similar to DbgVariable in DwarfDebug, but not dwarf-specific.
94   struct LocalVariable {
95     const DILocalVariable *DIVar = nullptr;
96     SmallVector<LocalVarDefRange, 1> DefRanges;
97   };
98 
99   struct InlineSite {
100     SmallVector<LocalVariable, 1> InlinedLocals;
101     SmallVector<const DILocation *, 1> ChildSites;
102     const DISubprogram *Inlinee = nullptr;
103 
104     /// The ID of the inline site or function used with .cv_loc. Not a type
105     /// index.
106     unsigned SiteFuncId = 0;
107   };
108 
109   // For each function, store a vector of labels to its instructions, as well as
110   // to the end of the function.
111   struct FunctionInfo {
112     /// Map from inlined call site to inlined instructions and child inlined
113     /// call sites. Listed in program order.
114     std::unordered_map<const DILocation *, InlineSite> InlineSites;
115 
116     /// Ordered list of top-level inlined call sites.
117     SmallVector<const DILocation *, 1> ChildSites;
118 
119     SmallVector<LocalVariable, 1> Locals;
120 
121     DebugLoc LastLoc;
122     const MCSymbol *Begin = nullptr;
123     const MCSymbol *End = nullptr;
124     unsigned FuncId = 0;
125     unsigned LastFileId = 0;
126     bool HaveLineInfo = false;
127   };
128   FunctionInfo *CurFn = nullptr;
129 
130   /// The set of comdat .debug$S sections that we've seen so far. Each section
131   /// must start with a magic version number that must only be emitted once.
132   /// This set tracks which sections we've already opened.
133   DenseSet<MCSectionCOFF *> ComdatDebugSections;
134 
135   /// Switch to the appropriate .debug$S section for GVSym. If GVSym, the symbol
136   /// of an emitted global value, is in a comdat COFF section, this will switch
137   /// to a new .debug$S section in that comdat. This method ensures that the
138   /// section starts with the magic version number on first use. If GVSym is
139   /// null, uses the main .debug$S section.
140   void switchToDebugSectionForSymbol(const MCSymbol *GVSym);
141 
142   /// The next available function index for use with our .cv_* directives. Not
143   /// to be confused with type indices for LF_FUNC_ID records.
144   unsigned NextFuncId = 0;
145 
146   InlineSite &getInlineSite(const DILocation *InlinedAt,
147                             const DISubprogram *Inlinee);
148 
149   codeview::TypeIndex getFuncIdForSubprogram(const DISubprogram *SP);
150 
151   static void collectInlineSiteChildren(SmallVectorImpl<unsigned> &Children,
152                                         const FunctionInfo &FI,
153                                         const InlineSite &Site);
154 
155   /// Remember some debug info about each function. Keep it in a stable order to
156   /// emit at the end of the TU.
157   MapVector<const Function *, FunctionInfo> FnDebugInfo;
158 
159   /// Map from DIFile to .cv_file id.
160   DenseMap<const DIFile *, unsigned> FileIdMap;
161 
162   /// All inlined subprograms in the order they should be emitted.
163   SmallSetVector<const DISubprogram *, 4> InlinedSubprograms;
164 
165   /// Map from a pair of DI metadata nodes and its DI type (or scope) that can
166   /// be nullptr, to CodeView type indices. Primarily indexed by
167   /// {DIType*, DIType*} and {DISubprogram*, DIType*}.
168   ///
169   /// The second entry in the key is needed for methods as DISubroutineType
170   /// representing static method type are shared with non-method function type.
171   DenseMap<std::pair<const DINode *, const DIType *>, codeview::TypeIndex>
172       TypeIndices;
173 
174   /// Map from DICompositeType* to complete type index. Non-record types are
175   /// always looked up in the normal TypeIndices map.
176   DenseMap<const DICompositeType *, codeview::TypeIndex> CompleteTypeIndices;
177 
178   /// Complete record types to emit after all active type lowerings are
179   /// finished.
180   SmallVector<const DICompositeType *, 4> DeferredCompleteTypes;
181 
182   /// Number of type lowering frames active on the stack.
183   unsigned TypeEmissionLevel = 0;
184 
185   codeview::TypeIndex VBPType;
186 
187   const DISubprogram *CurrentSubprogram = nullptr;
188 
189   // The UDTs we have seen while processing types; each entry is a pair of type
190   // index and type name.
191   std::vector<std::pair<std::string, codeview::TypeIndex>> LocalUDTs,
192       GlobalUDTs;
193 
194   using FileToFilepathMapTy = std::map<const DIFile *, std::string>;
195   FileToFilepathMapTy FileToFilepathMap;
196 
197   StringRef getFullFilepath(const DIFile *S);
198 
199   unsigned maybeRecordFile(const DIFile *F);
200 
201   void maybeRecordLocation(const DebugLoc &DL, const MachineFunction *MF);
202 
203   void clear();
204 
205   void setCurrentSubprogram(const DISubprogram *SP) {
206     CurrentSubprogram = SP;
207     LocalUDTs.clear();
208   }
209 
210   /// Emit the magic version number at the start of a CodeView type or symbol
211   /// section. Appears at the front of every .debug$S or .debug$T section.
212   void emitCodeViewMagicVersion();
213 
214   void emitTypeInformation();
215 
216   void emitCompilerInformation();
217 
218   void emitInlineeLinesSubsection();
219 
220   void emitDebugInfoForFunction(const Function *GV, FunctionInfo &FI);
221 
222   void emitDebugInfoForGlobals();
223 
224   void emitDebugInfoForRetainedTypes();
225 
226   void emitDebugInfoForUDTs(
227       ArrayRef<std::pair<std::string, codeview::TypeIndex>> UDTs);
228 
229   void emitDebugInfoForGlobal(const DIGlobalVariable *DIGV,
230                               const GlobalVariable *GV, MCSymbol *GVSym);
231 
232   /// Opens a subsection of the given kind in a .debug$S codeview section.
233   /// Returns an end label for use with endCVSubsection when the subsection is
234   /// finished.
235   MCSymbol *beginCVSubsection(codeview::DebugSubsectionKind Kind);
236 
237   void endCVSubsection(MCSymbol *EndLabel);
238 
239   void emitInlinedCallSite(const FunctionInfo &FI, const DILocation *InlinedAt,
240                            const InlineSite &Site);
241 
242   using InlinedVariable = DbgValueHistoryMap::InlinedVariable;
243 
244   void collectVariableInfo(const DISubprogram *SP);
245 
246   void collectVariableInfoFromMFTable(DenseSet<InlinedVariable> &Processed);
247 
248   /// Records information about a local variable in the appropriate scope. In
249   /// particular, locals from inlined code live inside the inlining site.
250   void recordLocalVariable(LocalVariable &&Var, const DILocation *Loc);
251 
252   /// Emits local variables in the appropriate order.
253   void emitLocalVariableList(ArrayRef<LocalVariable> Locals);
254 
255   /// Emits an S_LOCAL record and its associated defined ranges.
256   void emitLocalVariable(const LocalVariable &Var);
257 
258   /// Translates the DIType to codeview if necessary and returns a type index
259   /// for it.
260   codeview::TypeIndex getTypeIndex(DITypeRef TypeRef,
261                                    DITypeRef ClassTyRef = DITypeRef());
262 
263   codeview::TypeIndex getMemberFunctionType(const DISubprogram *SP,
264                                             const DICompositeType *Class);
265 
266   codeview::TypeIndex getScopeIndex(const DIScope *Scope);
267 
268   codeview::TypeIndex getVBPTypeIndex();
269 
270   void addToUDTs(const DIType *Ty, codeview::TypeIndex TI);
271 
272   codeview::TypeIndex lowerType(const DIType *Ty, const DIType *ClassTy);
273   codeview::TypeIndex lowerTypeAlias(const DIDerivedType *Ty);
274   codeview::TypeIndex lowerTypeArray(const DICompositeType *Ty);
275   codeview::TypeIndex lowerTypeBasic(const DIBasicType *Ty);
276   codeview::TypeIndex lowerTypePointer(const DIDerivedType *Ty);
277   codeview::TypeIndex lowerTypeMemberPointer(const DIDerivedType *Ty);
278   codeview::TypeIndex lowerTypeModifier(const DIDerivedType *Ty);
279   codeview::TypeIndex lowerTypeFunction(const DISubroutineType *Ty);
280   codeview::TypeIndex lowerTypeVFTableShape(const DIDerivedType *Ty);
281   codeview::TypeIndex lowerTypeMemberFunction(const DISubroutineType *Ty,
282                                               const DIType *ClassTy,
283                                               int ThisAdjustment);
284   codeview::TypeIndex lowerTypeEnum(const DICompositeType *Ty);
285   codeview::TypeIndex lowerTypeClass(const DICompositeType *Ty);
286   codeview::TypeIndex lowerTypeUnion(const DICompositeType *Ty);
287 
288   /// Symbol records should point to complete types, but type records should
289   /// always point to incomplete types to avoid cycles in the type graph. Only
290   /// use this entry point when generating symbol records. The complete and
291   /// incomplete type indices only differ for record types. All other types use
292   /// the same index.
293   codeview::TypeIndex getCompleteTypeIndex(DITypeRef TypeRef);
294 
295   codeview::TypeIndex lowerCompleteTypeClass(const DICompositeType *Ty);
296   codeview::TypeIndex lowerCompleteTypeUnion(const DICompositeType *Ty);
297 
298   struct TypeLoweringScope;
299 
300   void emitDeferredCompleteTypes();
301 
302   void collectMemberInfo(ClassInfo &Info, const DIDerivedType *DDTy);
303   ClassInfo collectClassInfo(const DICompositeType *Ty);
304 
305   /// Common record member lowering functionality for record types, which are
306   /// structs, classes, and unions. Returns the field list index and the member
307   /// count.
308   std::tuple<codeview::TypeIndex, codeview::TypeIndex, unsigned, bool>
309   lowerRecordFieldList(const DICompositeType *Ty);
310 
311   /// Inserts {{Node, ClassTy}, TI} into TypeIndices and checks for duplicates.
312   codeview::TypeIndex recordTypeIndexForDINode(const DINode *Node,
313                                                codeview::TypeIndex TI,
314                                                const DIType *ClassTy = nullptr);
315 
316   unsigned getPointerSizeInBytes();
317 
318 protected:
319   /// \brief Gather pre-function debug information.
320   void beginFunctionImpl(const MachineFunction *MF) override;
321 
322   /// \brief Gather post-function debug information.
323   void endFunctionImpl(const MachineFunction *) override;
324 
325 public:
326   CodeViewDebug(AsmPrinter *Asm);
327 
328   void setSymbolSize(const MCSymbol *, uint64_t) override {}
329 
330   /// \brief Emit the COFF section that holds the line table information.
331   void endModule() override;
332 
333   /// \brief Process beginning of an instruction.
334   void beginInstruction(const MachineInstr *MI) override;
335 };
336 
337 } // end namespace llvm
338 
339 #endif // LLVM_LIB_CODEGEN_ASMPRINTER_CODEVIEWDEBUG_H
340