1 //===- llvm/CodeGen/DwarfCompileUnit.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_DWARFCOMPILEUNIT_H
14 #define LLVM_LIB_CODEGEN_ASMPRINTER_DWARFCOMPILEUNIT_H
15 
16 #include "DwarfDebug.h"
17 #include "DwarfUnit.h"
18 #include "llvm/ADT/ArrayRef.h"
19 #include "llvm/ADT/DenseMap.h"
20 #include "llvm/ADT/SmallVector.h"
21 #include "llvm/ADT/StringMap.h"
22 #include "llvm/ADT/StringRef.h"
23 #include "llvm/BinaryFormat/Dwarf.h"
24 #include "llvm/CodeGen/DbgEntityHistoryCalculator.h"
25 #include "llvm/CodeGen/DIE.h"
26 #include "llvm/CodeGen/LexicalScopes.h"
27 #include "llvm/IR/DebugInfoMetadata.h"
28 #include "llvm/Support/Casting.h"
29 #include <algorithm>
30 #include <cassert>
31 #include <cstdint>
32 #include <memory>
33 
34 namespace llvm {
35 
36 class AsmPrinter;
37 class DwarfFile;
38 class GlobalVariable;
39 class MCExpr;
40 class MCSymbol;
41 class MDNode;
42 
43 enum class UnitKind { Skeleton, Full };
44 
45 class DwarfCompileUnit final : public DwarfUnit {
46   /// A numeric ID unique among all CUs in the module
47   unsigned UniqueID;
48   bool HasRangeLists = false;
49 
50   /// The attribute index of DW_AT_stmt_list in the compile unit DIE, avoiding
51   /// the need to search for it in applyStmtList.
52   DIE::value_iterator StmtListValue;
53 
54   /// Skeleton unit associated with this unit.
55   DwarfCompileUnit *Skeleton = nullptr;
56 
57   /// The start of the unit within its section.
58   MCSymbol *LabelBegin;
59 
60   /// The start of the unit macro info within macro section.
61   MCSymbol *MacroLabelBegin;
62 
63   using ImportedEntityList = SmallVector<const MDNode *, 8>;
64   using ImportedEntityMap = DenseMap<const MDNode *, ImportedEntityList>;
65 
66   ImportedEntityMap ImportedEntities;
67 
68   /// GlobalNames - A map of globally visible named entities for this unit.
69   StringMap<const DIE *> GlobalNames;
70 
71   /// GlobalTypes - A map of globally visible types for this unit.
72   StringMap<const DIE *> GlobalTypes;
73 
74   // List of ranges for a given compile unit.
75   SmallVector<RangeSpan, 2> CURanges;
76 
77   // The base address of this unit, if any. Used for relative references in
78   // ranges/locs.
79   const MCSymbol *BaseAddress = nullptr;
80 
81   DenseMap<const MDNode *, DIE *> AbstractSPDies;
82   DenseMap<const DINode *, std::unique_ptr<DbgEntity>> AbstractEntities;
83 
84   /// DWO ID for correlating skeleton and split units.
85   uint64_t DWOId = 0;
86 
87   /// Construct a DIE for the given DbgVariable without initializing the
88   /// DbgVariable's DIE reference.
89   DIE *constructVariableDIEImpl(const DbgVariable &DV, bool Abstract);
90 
91   bool isDwoUnit() const override;
92 
93   DenseMap<const MDNode *, DIE *> &getAbstractSPDies() {
94     if (isDwoUnit() && !DD->shareAcrossDWOCUs())
95       return AbstractSPDies;
96     return DU->getAbstractSPDies();
97   }
98 
99   DenseMap<const DINode *, std::unique_ptr<DbgEntity>> &getAbstractEntities() {
100     if (isDwoUnit() && !DD->shareAcrossDWOCUs())
101       return AbstractEntities;
102     return DU->getAbstractEntities();
103   }
104 
105   void finishNonUnitTypeDIE(DIE& D, const DICompositeType *CTy) override;
106 
107 public:
108   DwarfCompileUnit(unsigned UID, const DICompileUnit *Node, AsmPrinter *A,
109                    DwarfDebug *DW, DwarfFile *DWU,
110                    UnitKind Kind = UnitKind::Full);
111 
112   bool hasRangeLists() const { return HasRangeLists; }
113   unsigned getUniqueID() const { return UniqueID; }
114 
115   DwarfCompileUnit *getSkeleton() const {
116     return Skeleton;
117   }
118 
119   bool includeMinimalInlineScopes() const;
120 
121   void initStmtList();
122 
123   /// Apply the DW_AT_stmt_list from this compile unit to the specified DIE.
124   void applyStmtList(DIE &D);
125 
126   /// A pair of GlobalVariable and DIExpression.
127   struct GlobalExpr {
128     const GlobalVariable *Var;
129     const DIExpression *Expr;
130   };
131 
132   struct BaseTypeRef {
133     BaseTypeRef(unsigned BitSize, dwarf::TypeKind Encoding) :
134       BitSize(BitSize), Encoding(Encoding) {}
135     unsigned BitSize;
136     dwarf::TypeKind Encoding;
137     DIE *Die = nullptr;
138   };
139 
140   std::vector<BaseTypeRef> ExprRefedBaseTypes;
141 
142   /// Get or create global variable DIE.
143   DIE *
144   getOrCreateGlobalVariableDIE(const DIGlobalVariable *GV,
145                                ArrayRef<GlobalExpr> GlobalExprs);
146 
147   DIE *getOrCreateCommonBlock(const DICommonBlock *CB,
148                               ArrayRef<GlobalExpr> GlobalExprs);
149 
150   void addLocationAttribute(DIE *ToDIE, const DIGlobalVariable *GV,
151                             ArrayRef<GlobalExpr> GlobalExprs);
152 
153   /// addLabelAddress - Add a dwarf label attribute data and value using
154   /// either DW_FORM_addr or DW_FORM_GNU_addr_index.
155   void addLabelAddress(DIE &Die, dwarf::Attribute Attribute,
156                        const MCSymbol *Label);
157 
158   /// addLocalLabelAddress - Add a dwarf label attribute data and value using
159   /// DW_FORM_addr only.
160   void addLocalLabelAddress(DIE &Die, dwarf::Attribute Attribute,
161                             const MCSymbol *Label);
162 
163   DwarfCompileUnit &getCU() override { return *this; }
164 
165   unsigned getOrCreateSourceID(const DIFile *File) override;
166 
167   void addImportedEntity(const DIImportedEntity* IE) {
168     DIScope *Scope = IE->getScope();
169     assert(Scope && "Invalid Scope encoding!");
170     if (!isa<DILocalScope>(Scope))
171       // No need to add imported enities that are not local declaration.
172       return;
173 
174     auto *LocalScope = cast<DILocalScope>(Scope)->getNonLexicalBlockFileScope();
175     ImportedEntities[LocalScope].push_back(IE);
176   }
177 
178   /// addRange - Add an address range to the list of ranges for this unit.
179   void addRange(RangeSpan Range);
180 
181   void attachLowHighPC(DIE &D, const MCSymbol *Begin, const MCSymbol *End);
182 
183   /// Find DIE for the given subprogram and attach appropriate
184   /// DW_AT_low_pc and DW_AT_high_pc attributes. If there are global
185   /// variables in this scope then create and insert DIEs for these
186   /// variables.
187   DIE &updateSubprogramScopeDIE(const DISubprogram *SP);
188 
189   void constructScopeDIE(LexicalScope *Scope,
190                          SmallVectorImpl<DIE *> &FinalChildren);
191 
192   /// A helper function to construct a RangeSpanList for a given
193   /// lexical scope.
194   void addScopeRangeList(DIE &ScopeDIE, SmallVector<RangeSpan, 2> Range);
195 
196   void attachRangesOrLowHighPC(DIE &D, SmallVector<RangeSpan, 2> Ranges);
197 
198   void attachRangesOrLowHighPC(DIE &D,
199                                const SmallVectorImpl<InsnRange> &Ranges);
200 
201   /// This scope represents inlined body of a function. Construct
202   /// DIE to represent this concrete inlined copy of the function.
203   DIE *constructInlinedScopeDIE(LexicalScope *Scope);
204 
205   /// Construct new DW_TAG_lexical_block for this scope and
206   /// attach DW_AT_low_pc/DW_AT_high_pc labels.
207   DIE *constructLexicalScopeDIE(LexicalScope *Scope);
208 
209   /// constructVariableDIE - Construct a DIE for the given DbgVariable.
210   DIE *constructVariableDIE(DbgVariable &DV, bool Abstract = false);
211 
212   DIE *constructVariableDIE(DbgVariable &DV, const LexicalScope &Scope,
213                             DIE *&ObjectPointer);
214 
215   /// Construct a DIE for the given DbgLabel.
216   DIE *constructLabelDIE(DbgLabel &DL, const LexicalScope &Scope);
217 
218   /// A helper function to create children of a Scope DIE.
219   DIE *createScopeChildrenDIE(LexicalScope *Scope,
220                               SmallVectorImpl<DIE *> &Children,
221                               bool *HasNonScopeChildren = nullptr);
222 
223   void createBaseTypeDIEs();
224 
225   /// Construct a DIE for this subprogram scope.
226   DIE &constructSubprogramScopeDIE(const DISubprogram *Sub,
227                                    LexicalScope *Scope);
228 
229   DIE *createAndAddScopeChildren(LexicalScope *Scope, DIE &ScopeDIE);
230 
231   void constructAbstractSubprogramScopeDIE(LexicalScope *Scope);
232 
233   /// Whether to use the GNU analog for a DWARF5 tag, attribute, or location
234   /// atom. Only applicable when emitting otherwise DWARF4-compliant debug info.
235   bool useGNUAnalogForDwarf5Feature() const;
236 
237   /// This takes a DWARF 5 tag and returns it or a GNU analog.
238   dwarf::Tag getDwarf5OrGNUTag(dwarf::Tag Tag) const;
239 
240   /// This takes a DWARF 5 attribute and returns it or a GNU analog.
241   dwarf::Attribute getDwarf5OrGNUAttr(dwarf::Attribute Attr) const;
242 
243   /// This takes a DWARF 5 location atom and either returns it or a GNU analog.
244   dwarf::LocationAtom getDwarf5OrGNULocationAtom(dwarf::LocationAtom Loc) const;
245 
246   /// Construct a call site entry DIE describing a call within \p Scope to a
247   /// callee described by \p CalleeDIE.
248   /// \p CalleeDIE is a declaration or definition subprogram DIE for the callee.
249   /// For indirect calls \p CalleeDIE is set to nullptr.
250   /// \p IsTail specifies whether the call is a tail call.
251   /// \p PCAddr points to the PC value after the call instruction.
252   /// \p CallAddr points to the PC value at the call instruction (or is null).
253   /// \p CallReg is a register location for an indirect call. For direct calls
254   /// the \p CallReg is set to 0.
255   DIE &constructCallSiteEntryDIE(DIE &ScopeDIE, DIE *CalleeDIE, bool IsTail,
256                                  const MCSymbol *PCAddr,
257                                  const MCSymbol *CallAddr, unsigned CallReg);
258   /// Construct call site parameter DIEs for the \p CallSiteDIE. The \p Params
259   /// were collected by the \ref collectCallSiteParameters.
260   /// Note: The order of parameters does not matter, since debuggers recognize
261   ///       call site parameters by the DW_AT_location attribute.
262   void constructCallSiteParmEntryDIEs(DIE &CallSiteDIE,
263                                       SmallVector<DbgCallSiteParam, 4> &Params);
264 
265   /// Construct import_module DIE.
266   DIE *constructImportedEntityDIE(const DIImportedEntity *Module);
267 
268   void finishSubprogramDefinition(const DISubprogram *SP);
269   void finishEntityDefinition(const DbgEntity *Entity);
270 
271   /// Find abstract variable associated with Var.
272   using InlinedEntity = DbgValueHistoryMap::InlinedEntity;
273   DbgEntity *getExistingAbstractEntity(const DINode *Node);
274   void createAbstractEntity(const DINode *Node, LexicalScope *Scope);
275 
276   /// Set the skeleton unit associated with this unit.
277   void setSkeleton(DwarfCompileUnit &Skel) { Skeleton = &Skel; }
278 
279   unsigned getHeaderSize() const override {
280     // DWARF v5 added the DWO ID to the header for split/skeleton units.
281     unsigned DWOIdSize =
282         DD->getDwarfVersion() >= 5 && DD->useSplitDwarf() ? sizeof(uint64_t)
283                                                           : 0;
284     return DwarfUnit::getHeaderSize() + DWOIdSize;
285   }
286   unsigned getLength() {
287     return sizeof(uint32_t) + // Length field
288         getHeaderSize() + getUnitDie().getSize();
289   }
290 
291   void emitHeader(bool UseOffsets) override;
292 
293   /// Add the DW_AT_addr_base attribute to the unit DIE.
294   void addAddrTableBase();
295 
296   MCSymbol *getLabelBegin() const {
297     assert(getSection());
298     return LabelBegin;
299   }
300 
301   MCSymbol *getMacroLabelBegin() const {
302     return MacroLabelBegin;
303   }
304 
305   /// Add a new global name to the compile unit.
306   void addGlobalName(StringRef Name, const DIE &Die,
307                      const DIScope *Context) override;
308 
309   /// Add a new global name present in a type unit to this compile unit.
310   void addGlobalNameForTypeUnit(StringRef Name, const DIScope *Context);
311 
312   /// Add a new global type to the compile unit.
313   void addGlobalType(const DIType *Ty, const DIE &Die,
314                      const DIScope *Context) override;
315 
316   /// Add a new global type present in a type unit to this compile unit.
317   void addGlobalTypeUnitType(const DIType *Ty, const DIScope *Context);
318 
319   const StringMap<const DIE *> &getGlobalNames() const { return GlobalNames; }
320   const StringMap<const DIE *> &getGlobalTypes() const { return GlobalTypes; }
321 
322   /// Add DW_AT_location attribute for a DbgVariable based on provided
323   /// MachineLocation.
324   void addVariableAddress(const DbgVariable &DV, DIE &Die,
325                           MachineLocation Location);
326   /// Add an address attribute to a die based on the location provided.
327   void addAddress(DIE &Die, dwarf::Attribute Attribute,
328                   const MachineLocation &Location);
329 
330   /// Start with the address based on the location provided, and generate the
331   /// DWARF information necessary to find the actual variable (navigating the
332   /// extra location information encoded in the type) based on the starting
333   /// location.  Add the DWARF information to the die.
334   void addComplexAddress(const DbgVariable &DV, DIE &Die,
335                          dwarf::Attribute Attribute,
336                          const MachineLocation &Location);
337 
338   /// Add a Dwarf loclistptr attribute data and value.
339   void addLocationList(DIE &Die, dwarf::Attribute Attribute, unsigned Index);
340   void applyVariableAttributes(const DbgVariable &Var, DIE &VariableDie);
341 
342   /// Add a Dwarf expression attribute data and value.
343   void addExpr(DIELoc &Die, dwarf::Form Form, const MCExpr *Expr);
344 
345   void applySubprogramAttributesToDefinition(const DISubprogram *SP,
346                                              DIE &SPDie);
347 
348   void applyLabelAttributes(const DbgLabel &Label, DIE &LabelDie);
349 
350   /// getRanges - Get the list of ranges for this unit.
351   const SmallVectorImpl<RangeSpan> &getRanges() const { return CURanges; }
352   SmallVector<RangeSpan, 2> takeRanges() { return std::move(CURanges); }
353 
354   void setBaseAddress(const MCSymbol *Base) { BaseAddress = Base; }
355   const MCSymbol *getBaseAddress() const { return BaseAddress; }
356 
357   uint64_t getDWOId() const { return DWOId; }
358   void setDWOId(uint64_t DwoId) { DWOId = DwoId; }
359 
360   bool hasDwarfPubSections() const;
361 
362   void addBaseTypeRef(DIEValueList &Die, int64_t Idx);
363 };
364 
365 } // end namespace llvm
366 
367 #endif // LLVM_LIB_CODEGEN_ASMPRINTER_DWARFCOMPILEUNIT_H
368