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     const MCSymbol *Begin = nullptr;
122     const MCSymbol *End = nullptr;
123     unsigned FuncId = 0;
124     unsigned LastFileId = 0;
125     bool HaveLineInfo = false;
126   };
127   FunctionInfo *CurFn = nullptr;
128 
129   /// The set of comdat .debug$S sections that we've seen so far. Each section
130   /// must start with a magic version number that must only be emitted once.
131   /// This set tracks which sections we've already opened.
132   DenseSet<MCSectionCOFF *> ComdatDebugSections;
133 
134   /// Switch to the appropriate .debug$S section for GVSym. If GVSym, the symbol
135   /// of an emitted global value, is in a comdat COFF section, this will switch
136   /// to a new .debug$S section in that comdat. This method ensures that the
137   /// section starts with the magic version number on first use. If GVSym is
138   /// null, uses the main .debug$S section.
139   void switchToDebugSectionForSymbol(const MCSymbol *GVSym);
140 
141   /// The next available function index for use with our .cv_* directives. Not
142   /// to be confused with type indices for LF_FUNC_ID records.
143   unsigned NextFuncId = 0;
144 
145   InlineSite &getInlineSite(const DILocation *InlinedAt,
146                             const DISubprogram *Inlinee);
147 
148   codeview::TypeIndex getFuncIdForSubprogram(const DISubprogram *SP);
149 
150   static void collectInlineSiteChildren(SmallVectorImpl<unsigned> &Children,
151                                         const FunctionInfo &FI,
152                                         const InlineSite &Site);
153 
154   /// Remember some debug info about each function. Keep it in a stable order to
155   /// emit at the end of the TU.
156   MapVector<const Function *, FunctionInfo> FnDebugInfo;
157 
158   /// Map from DIFile to .cv_file id.
159   DenseMap<const DIFile *, unsigned> FileIdMap;
160 
161   /// All inlined subprograms in the order they should be emitted.
162   SmallSetVector<const DISubprogram *, 4> InlinedSubprograms;
163 
164   /// Map from a pair of DI metadata nodes and its DI type (or scope) that can
165   /// be nullptr, to CodeView type indices. Primarily indexed by
166   /// {DIType*, DIType*} and {DISubprogram*, DIType*}.
167   ///
168   /// The second entry in the key is needed for methods as DISubroutineType
169   /// representing static method type are shared with non-method function type.
170   DenseMap<std::pair<const DINode *, const DIType *>, codeview::TypeIndex>
171       TypeIndices;
172 
173   /// Map from DICompositeType* to complete type index. Non-record types are
174   /// always looked up in the normal TypeIndices map.
175   DenseMap<const DICompositeType *, codeview::TypeIndex> CompleteTypeIndices;
176 
177   /// Complete record types to emit after all active type lowerings are
178   /// finished.
179   SmallVector<const DICompositeType *, 4> DeferredCompleteTypes;
180 
181   /// Number of type lowering frames active on the stack.
182   unsigned TypeEmissionLevel = 0;
183 
184   codeview::TypeIndex VBPType;
185 
186   const DISubprogram *CurrentSubprogram = nullptr;
187 
188   // The UDTs we have seen while processing types; each entry is a pair of type
189   // index and type name.
190   std::vector<std::pair<std::string, codeview::TypeIndex>> LocalUDTs,
191       GlobalUDTs;
192 
193   using FileToFilepathMapTy = std::map<const DIFile *, std::string>;
194   FileToFilepathMapTy FileToFilepathMap;
195 
196   StringRef getFullFilepath(const DIFile *S);
197 
198   unsigned maybeRecordFile(const DIFile *F);
199 
200   void maybeRecordLocation(const DebugLoc &DL, const MachineFunction *MF);
201 
202   void clear();
203 
204   void setCurrentSubprogram(const DISubprogram *SP) {
205     CurrentSubprogram = SP;
206     LocalUDTs.clear();
207   }
208 
209   /// Emit the magic version number at the start of a CodeView type or symbol
210   /// section. Appears at the front of every .debug$S or .debug$T section.
211   void emitCodeViewMagicVersion();
212 
213   void emitTypeInformation();
214 
215   void emitCompilerInformation();
216 
217   void emitInlineeLinesSubsection();
218 
219   void emitDebugInfoForFunction(const Function *GV, FunctionInfo &FI);
220 
221   void emitDebugInfoForGlobals();
222 
223   void emitDebugInfoForRetainedTypes();
224 
225   void emitDebugInfoForUDTs(
226       ArrayRef<std::pair<std::string, codeview::TypeIndex>> UDTs);
227 
228   void emitDebugInfoForGlobal(const DIGlobalVariable *DIGV,
229                               const GlobalVariable *GV, MCSymbol *GVSym);
230 
231   /// Opens a subsection of the given kind in a .debug$S codeview section.
232   /// Returns an end label for use with endCVSubsection when the subsection is
233   /// finished.
234   MCSymbol *beginCVSubsection(codeview::DebugSubsectionKind Kind);
235 
236   void endCVSubsection(MCSymbol *EndLabel);
237 
238   void emitInlinedCallSite(const FunctionInfo &FI, const DILocation *InlinedAt,
239                            const InlineSite &Site);
240 
241   using InlinedVariable = DbgValueHistoryMap::InlinedVariable;
242 
243   void collectVariableInfo(const DISubprogram *SP);
244 
245   void collectVariableInfoFromMFTable(DenseSet<InlinedVariable> &Processed);
246 
247   /// Records information about a local variable in the appropriate scope. In
248   /// particular, locals from inlined code live inside the inlining site.
249   void recordLocalVariable(LocalVariable &&Var, const DILocation *Loc);
250 
251   /// Emits local variables in the appropriate order.
252   void emitLocalVariableList(ArrayRef<LocalVariable> Locals);
253 
254   /// Emits an S_LOCAL record and its associated defined ranges.
255   void emitLocalVariable(const LocalVariable &Var);
256 
257   /// Translates the DIType to codeview if necessary and returns a type index
258   /// for it.
259   codeview::TypeIndex getTypeIndex(DITypeRef TypeRef,
260                                    DITypeRef ClassTyRef = DITypeRef());
261 
262   codeview::TypeIndex getMemberFunctionType(const DISubprogram *SP,
263                                             const DICompositeType *Class);
264 
265   codeview::TypeIndex getScopeIndex(const DIScope *Scope);
266 
267   codeview::TypeIndex getVBPTypeIndex();
268 
269   void addToUDTs(const DIType *Ty, codeview::TypeIndex TI);
270 
271   codeview::TypeIndex lowerType(const DIType *Ty, const DIType *ClassTy);
272   codeview::TypeIndex lowerTypeAlias(const DIDerivedType *Ty);
273   codeview::TypeIndex lowerTypeArray(const DICompositeType *Ty);
274   codeview::TypeIndex lowerTypeBasic(const DIBasicType *Ty);
275   codeview::TypeIndex lowerTypePointer(const DIDerivedType *Ty);
276   codeview::TypeIndex lowerTypeMemberPointer(const DIDerivedType *Ty);
277   codeview::TypeIndex lowerTypeModifier(const DIDerivedType *Ty);
278   codeview::TypeIndex lowerTypeFunction(const DISubroutineType *Ty);
279   codeview::TypeIndex lowerTypeVFTableShape(const DIDerivedType *Ty);
280   codeview::TypeIndex lowerTypeMemberFunction(const DISubroutineType *Ty,
281                                               const DIType *ClassTy,
282                                               int ThisAdjustment);
283   codeview::TypeIndex lowerTypeEnum(const DICompositeType *Ty);
284   codeview::TypeIndex lowerTypeClass(const DICompositeType *Ty);
285   codeview::TypeIndex lowerTypeUnion(const DICompositeType *Ty);
286 
287   /// Symbol records should point to complete types, but type records should
288   /// always point to incomplete types to avoid cycles in the type graph. Only
289   /// use this entry point when generating symbol records. The complete and
290   /// incomplete type indices only differ for record types. All other types use
291   /// the same index.
292   codeview::TypeIndex getCompleteTypeIndex(DITypeRef TypeRef);
293 
294   codeview::TypeIndex lowerCompleteTypeClass(const DICompositeType *Ty);
295   codeview::TypeIndex lowerCompleteTypeUnion(const DICompositeType *Ty);
296 
297   struct TypeLoweringScope;
298 
299   void emitDeferredCompleteTypes();
300 
301   void collectMemberInfo(ClassInfo &Info, const DIDerivedType *DDTy);
302   ClassInfo collectClassInfo(const DICompositeType *Ty);
303 
304   /// Common record member lowering functionality for record types, which are
305   /// structs, classes, and unions. Returns the field list index and the member
306   /// count.
307   std::tuple<codeview::TypeIndex, codeview::TypeIndex, unsigned, bool>
308   lowerRecordFieldList(const DICompositeType *Ty);
309 
310   /// Inserts {{Node, ClassTy}, TI} into TypeIndices and checks for duplicates.
311   codeview::TypeIndex recordTypeIndexForDINode(const DINode *Node,
312                                                codeview::TypeIndex TI,
313                                                const DIType *ClassTy = nullptr);
314 
315   unsigned getPointerSizeInBytes();
316 
317 protected:
318   /// \brief Gather pre-function debug information.
319   void beginFunctionImpl(const MachineFunction *MF) override;
320 
321   /// \brief Gather post-function debug information.
322   void endFunctionImpl(const MachineFunction *) override;
323 
324 public:
325   CodeViewDebug(AsmPrinter *Asm);
326 
327   void setSymbolSize(const MCSymbol *, uint64_t) override {}
328 
329   /// \brief Emit the COFF section that holds the line table information.
330   void endModule() override;
331 
332   /// \brief Process beginning of an instruction.
333   void beginInstruction(const MachineInstr *MI) override;
334 };
335 
336 } // end namespace llvm
337 
338 #endif // LLVM_LIB_CODEGEN_ASMPRINTER_CODEVIEWDEBUG_H
339