1 //===-- llvm/CodeGen/DwarfUnit.h - Dwarf Compile Unit ---*- C++ -*--===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file contains support for writing dwarf compile unit.
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #ifndef LLVM_LIB_CODEGEN_ASMPRINTER_DWARFUNIT_H
14 #define LLVM_LIB_CODEGEN_ASMPRINTER_DWARFUNIT_H
15 
16 #include "DwarfDebug.h"
17 #include "llvm/ADT/DenseMap.h"
18 #include "llvm/ADT/Optional.h"
19 #include "llvm/CodeGen/AsmPrinter.h"
20 #include "llvm/CodeGen/DIE.h"
21 #include <string>
22 
23 namespace llvm {
24 
25 class ConstantFP;
26 class ConstantInt;
27 class DbgVariable;
28 class DwarfCompileUnit;
29 class MachineOperand;
30 class MCDwarfDwoLineTable;
31 class MCSymbol;
32 
33 //===----------------------------------------------------------------------===//
34 /// This dwarf writer support class manages information associated with a
35 /// source file.
36 class DwarfUnit : public DIEUnit {
37 protected:
38   /// MDNode for the compile unit.
39   const DICompileUnit *CUNode;
40 
41   // All DIEValues are allocated through this allocator.
42   BumpPtrAllocator DIEValueAllocator;
43 
44   /// Target of Dwarf emission.
45   AsmPrinter *Asm;
46 
47   /// Emitted at the end of the CU and used to compute the CU Length field.
48   MCSymbol *EndLabel = nullptr;
49 
50   // Holders for some common dwarf information.
51   DwarfDebug *DD;
52   DwarfFile *DU;
53 
54   /// An anonymous type for index type.  Owned by DIEUnit.
55   DIE *IndexTyDie;
56 
57   /// Tracks the mapping of unit level debug information variables to debug
58   /// information entries.
59   DenseMap<const MDNode *, DIE *> MDNodeToDieMap;
60 
61   /// A list of all the DIEBlocks in use.
62   std::vector<DIEBlock *> DIEBlocks;
63 
64   /// A list of all the DIELocs in use.
65   std::vector<DIELoc *> DIELocs;
66 
67   /// This map is used to keep track of subprogram DIEs that need
68   /// DW_AT_containing_type attribute. This attribute points to a DIE that
69   /// corresponds to the MDNode mapped with the subprogram DIE.
70   DenseMap<DIE *, const DINode *> ContainingTypeMap;
71 
72   DwarfUnit(dwarf::Tag, const DICompileUnit *Node, AsmPrinter *A, DwarfDebug *DW,
73             DwarfFile *DWU);
74 
75   bool applySubprogramDefinitionAttributes(const DISubprogram *SP, DIE &SPDie);
76 
77   bool isShareableAcrossCUs(const DINode *D) const;
78 
79 public:
80   // Accessors.
81   AsmPrinter* getAsmPrinter() const { return Asm; }
82   MCSymbol *getEndLabel() const { return EndLabel; }
83   uint16_t getLanguage() const { return CUNode->getSourceLanguage(); }
84   const DICompileUnit *getCUNode() const { return CUNode; }
85   DwarfDebug &getDwarfDebug() const { return *DD; }
86 
87   /// Return true if this compile unit has something to write out.
88   bool hasContent() const { return getUnitDie().hasChildren(); }
89 
90   /// Get string containing language specific context for a global name.
91   ///
92   /// Walks the metadata parent chain in a language specific manner (using the
93   /// compile unit language) and returns it as a string. This is done at the
94   /// metadata level because DIEs may not currently have been added to the
95   /// parent context and walking the DIEs looking for names is more expensive
96   /// than walking the metadata.
97   std::string getParentContextString(const DIScope *Context) const;
98 
99   /// Add a new global name to the compile unit.
100   virtual void addGlobalName(StringRef Name, const DIE &Die,
101                              const DIScope *Context) = 0;
102 
103   /// Add a new global type to the compile unit.
104   virtual void addGlobalType(const DIType *Ty, const DIE &Die,
105                              const DIScope *Context) = 0;
106 
107   /// Returns the DIE map slot for the specified debug variable.
108   ///
109   /// We delegate the request to DwarfDebug when the MDNode can be part of the
110   /// type system, since DIEs for the type system can be shared across CUs and
111   /// the mappings are kept in DwarfDebug.
112   DIE *getDIE(const DINode *D) const;
113 
114   /// Returns a fresh newly allocated DIELoc.
115   DIELoc *getDIELoc() { return new (DIEValueAllocator) DIELoc; }
116 
117   /// Insert DIE into the map.
118   ///
119   /// We delegate the request to DwarfDebug when the MDNode can be part of the
120   /// type system, since DIEs for the type system can be shared across CUs and
121   /// the mappings are kept in DwarfDebug.
122   void insertDIE(const DINode *Desc, DIE *D);
123 
124   void insertDIE(DIE *D);
125 
126   /// Add a flag that is true to the DIE.
127   void addFlag(DIE &Die, dwarf::Attribute Attribute);
128 
129   /// Add an unsigned integer attribute data and value.
130   void addUInt(DIEValueList &Die, dwarf::Attribute Attribute,
131                Optional<dwarf::Form> Form, uint64_t Integer);
132 
133   void addUInt(DIEValueList &Block, dwarf::Form Form, uint64_t Integer);
134 
135   /// Add an signed integer attribute data and value.
136   void addSInt(DIEValueList &Die, dwarf::Attribute Attribute,
137                Optional<dwarf::Form> Form, int64_t Integer);
138 
139   void addSInt(DIELoc &Die, Optional<dwarf::Form> Form, int64_t Integer);
140 
141   /// Add a string attribute data and value.
142   ///
143   /// We always emit a reference to the string pool instead of immediate
144   /// strings so that DIEs have more predictable sizes. In the case of split
145   /// dwarf we emit an index into another table which gets us the static offset
146   /// into the string table.
147   void addString(DIE &Die, dwarf::Attribute Attribute, StringRef Str);
148 
149   /// Add a Dwarf label attribute data and value.
150   DIEValueList::value_iterator addLabel(DIEValueList &Die,
151                                         dwarf::Attribute Attribute,
152                                         dwarf::Form Form,
153                                         const MCSymbol *Label);
154 
155   void addLabel(DIELoc &Die, dwarf::Form Form, const MCSymbol *Label);
156 
157   /// Add an offset into a section attribute data and value.
158   void addSectionOffset(DIE &Die, dwarf::Attribute Attribute, uint64_t Integer);
159 
160   /// Add a dwarf op address data and value using the form given and an
161   /// op of either DW_FORM_addr or DW_FORM_GNU_addr_index.
162   void addOpAddress(DIELoc &Die, const MCSymbol *Sym);
163   void addPoolOpAddress(DIEValueList &Die, const MCSymbol *Label);
164 
165   /// Add a label delta attribute data and value.
166   void addLabelDelta(DIEValueList &Die, dwarf::Attribute Attribute,
167                      const MCSymbol *Hi, const MCSymbol *Lo);
168 
169   /// Add a DIE attribute data and value.
170   void addDIEEntry(DIE &Die, dwarf::Attribute Attribute, DIE &Entry);
171 
172   /// Add a DIE attribute data and value.
173   void addDIEEntry(DIE &Die, dwarf::Attribute Attribute, DIEEntry Entry);
174 
175   /// Add a type's DW_AT_signature and set the  declaration flag.
176   void addDIETypeSignature(DIE &Die, uint64_t Signature);
177 
178   /// Add block data.
179   void addBlock(DIE &Die, dwarf::Attribute Attribute, DIELoc *Loc);
180 
181   /// Add block data.
182   void addBlock(DIE &Die, dwarf::Attribute Attribute, DIEBlock *Block);
183   void addBlock(DIE &Die, dwarf::Attribute Attribute, dwarf::Form Form,
184                 DIEBlock *Block);
185 
186   /// Add location information to specified debug information entry.
187   void addSourceLine(DIE &Die, unsigned Line, const DIFile *File);
188   void addSourceLine(DIE &Die, const DILocalVariable *V);
189   void addSourceLine(DIE &Die, const DIGlobalVariable *G);
190   void addSourceLine(DIE &Die, const DISubprogram *SP);
191   void addSourceLine(DIE &Die, const DILabel *L);
192   void addSourceLine(DIE &Die, const DIType *Ty);
193   void addSourceLine(DIE &Die, const DIObjCProperty *Ty);
194 
195   /// Add constant value entry in variable DIE.
196   void addConstantValue(DIE &Die, const ConstantInt *CI, const DIType *Ty);
197   void addConstantValue(DIE &Die, const APInt &Val, const DIType *Ty);
198   void addConstantValue(DIE &Die, const APInt &Val, bool Unsigned);
199   void addConstantValue(DIE &Die, uint64_t Val, const DIType *Ty);
200   void addConstantValue(DIE &Die, bool Unsigned, uint64_t Val);
201 
202   /// Add constant value entry in variable DIE.
203   void addConstantFPValue(DIE &Die, const ConstantFP *CFP);
204 
205   /// Add a linkage name, if it isn't empty.
206   void addLinkageName(DIE &Die, StringRef LinkageName);
207 
208   /// Add template parameters in buffer.
209   void addTemplateParams(DIE &Buffer, DINodeArray TParams);
210 
211   /// Add thrown types.
212   void addThrownTypes(DIE &Die, DINodeArray ThrownTypes);
213 
214   /// Add a new type attribute to the specified entity.
215   ///
216   /// This takes and attribute parameter because DW_AT_friend attributes are
217   /// also type references.
218   void addType(DIE &Entity, const DIType *Ty,
219                dwarf::Attribute Attribute = dwarf::DW_AT_type);
220 
221   DIE *getOrCreateNameSpace(const DINamespace *NS);
222   DIE *getOrCreateModule(const DIModule *M);
223   DIE *getOrCreateSubprogramDIE(const DISubprogram *SP, bool Minimal = false);
224 
225   void applySubprogramAttributes(const DISubprogram *SP, DIE &SPDie,
226                                  bool SkipSPAttributes = false);
227 
228   /// Creates type DIE with specific context.
229   DIE *createTypeDIE(const DIScope *Context, DIE &ContextDIE, const DIType *Ty);
230 
231   /// Find existing DIE or create new DIE for the given type.
232   DIE *getOrCreateTypeDIE(const MDNode *TyNode);
233 
234   /// Get context owner's DIE.
235   DIE *getOrCreateContextDIE(const DIScope *Context);
236 
237   /// Construct DIEs for types that contain vtables.
238   void constructContainingTypeDIEs();
239 
240   /// Construct function argument DIEs.
241   void constructSubprogramArguments(DIE &Buffer, DITypeRefArray Args);
242 
243   /// Create a DIE with the given Tag, add the DIE to its parent, and
244   /// call insertDIE if MD is not null.
245   DIE &createAndAddDIE(unsigned Tag, DIE &Parent, const DINode *N = nullptr);
246 
247   bool useSegmentedStringOffsetsTable() const {
248     return DD->useSegmentedStringOffsetsTable();
249   }
250 
251   /// Compute the size of a header for this unit, not including the initial
252   /// length field.
253   virtual unsigned getHeaderSize() const {
254     return sizeof(int16_t) +               // DWARF version number
255            Asm->getDwarfOffsetByteSize() + // Offset Into Abbrev. Section
256            sizeof(int8_t) +                // Pointer Size (in bytes)
257            (DD->getDwarfVersion() >= 5 ? sizeof(int8_t)
258                                        : 0); // DWARF v5 unit type
259   }
260 
261   /// Emit the header for this unit, not including the initial length field.
262   virtual void emitHeader(bool UseOffsets) = 0;
263 
264   /// Add the DW_AT_str_offsets_base attribute to the unit DIE.
265   void addStringOffsetsStart();
266 
267   /// Add the DW_AT_rnglists_base attribute to the unit DIE.
268   void addRnglistsBase();
269 
270   virtual DwarfCompileUnit &getCU() = 0;
271 
272   void constructTypeDIE(DIE &Buffer, const DICompositeType *CTy);
273 
274   /// addSectionDelta - Add a label delta attribute data and value.
275   DIE::value_iterator addSectionDelta(DIE &Die, dwarf::Attribute Attribute,
276                                       const MCSymbol *Hi, const MCSymbol *Lo);
277 
278   /// Add a Dwarf section label attribute data and value.
279   DIE::value_iterator addSectionLabel(DIE &Die, dwarf::Attribute Attribute,
280                                       const MCSymbol *Label,
281                                       const MCSymbol *Sec);
282 
283   /// Get context owner's DIE.
284   DIE *createTypeDIE(const DICompositeType *Ty);
285 
286 protected:
287   ~DwarfUnit();
288 
289   /// Create new static data member DIE.
290   DIE *getOrCreateStaticMemberDIE(const DIDerivedType *DT);
291 
292   /// Look up the source ID for the given file. If none currently exists,
293   /// create a new ID and insert it in the line table.
294   virtual unsigned getOrCreateSourceID(const DIFile *File) = 0;
295 
296   /// Emit the common part of the header for this unit.
297   void emitCommonHeader(bool UseOffsets, dwarf::UnitType UT);
298 
299 private:
300   void constructTypeDIE(DIE &Buffer, const DIBasicType *BTy);
301   void constructTypeDIE(DIE &Buffer, const DIStringType *BTy);
302   void constructTypeDIE(DIE &Buffer, const DIDerivedType *DTy);
303   void constructTypeDIE(DIE &Buffer, const DISubroutineType *CTy);
304   void constructSubrangeDIE(DIE &Buffer, const DISubrange *SR, DIE *IndexTy);
305   void constructGenericSubrangeDIE(DIE &Buffer, const DIGenericSubrange *SR,
306                                    DIE *IndexTy);
307   void constructArrayTypeDIE(DIE &Buffer, const DICompositeType *CTy);
308   void constructEnumTypeDIE(DIE &Buffer, const DICompositeType *CTy);
309   DIE &constructMemberDIE(DIE &Buffer, const DIDerivedType *DT);
310   void constructTemplateTypeParameterDIE(DIE &Buffer,
311                                          const DITemplateTypeParameter *TP);
312   void constructTemplateValueParameterDIE(DIE &Buffer,
313                                           const DITemplateValueParameter *TVP);
314 
315   /// Return the default lower bound for an array.
316   ///
317   /// If the DWARF version doesn't handle the language, return -1.
318   int64_t getDefaultLowerBound() const;
319 
320   /// Get an anonymous type for index type.
321   DIE *getIndexTyDie();
322 
323   /// Set D as anonymous type for index which can be reused later.
324   void setIndexTyDie(DIE *D) { IndexTyDie = D; }
325 
326   virtual void finishNonUnitTypeDIE(DIE& D, const DICompositeType *CTy) = 0;
327 
328   /// If this is a named finished type then include it in the list of types for
329   /// the accelerator tables.
330   void updateAcceleratorTables(const DIScope *Context, const DIType *Ty,
331                                const DIE &TyDIE);
332 
333   virtual bool isDwoUnit() const = 0;
334   const MCSymbol *getCrossSectionRelativeBaseAddress() const override;
335 };
336 
337 class DwarfTypeUnit final : public DwarfUnit {
338   uint64_t TypeSignature;
339   const DIE *Ty;
340   DwarfCompileUnit &CU;
341   MCDwarfDwoLineTable *SplitLineTable;
342   bool UsedLineTable = false;
343 
344   unsigned getOrCreateSourceID(const DIFile *File) override;
345   void finishNonUnitTypeDIE(DIE& D, const DICompositeType *CTy) override;
346   bool isDwoUnit() const override;
347 
348 public:
349   DwarfTypeUnit(DwarfCompileUnit &CU, AsmPrinter *A, DwarfDebug *DW,
350                 DwarfFile *DWU, MCDwarfDwoLineTable *SplitLineTable = nullptr);
351 
352   void setTypeSignature(uint64_t Signature) { TypeSignature = Signature; }
353   void setType(const DIE *Ty) { this->Ty = Ty; }
354 
355   /// Emit the header for this unit, not including the initial length field.
356   void emitHeader(bool UseOffsets) override;
357   unsigned getHeaderSize() const override {
358     return DwarfUnit::getHeaderSize() + sizeof(uint64_t) + // Type Signature
359            Asm->getDwarfOffsetByteSize();                  // Type DIE Offset
360   }
361   void addGlobalName(StringRef Name, const DIE &Die,
362                      const DIScope *Context) override;
363   void addGlobalType(const DIType *Ty, const DIE &Die,
364                      const DIScope *Context) override;
365   DwarfCompileUnit &getCU() override { return CU; }
366 };
367 } // end llvm namespace
368 #endif
369