text: //===- llvm/CodeGen/DwarfCompileUnit.h - Dwarf Compile Unit -----*- C++ -*-===//
  //
  // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
  // See https://llvm.org/LICENSE.txt for license information.
  // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
  //
  //===----------------------------------------------------------------------===//
  //
  // This file contains support for writing dwarf compile unit.
  //
  //===----------------------------------------------------------------------===//
  
  #ifndef LLVM_LIB_CODEGEN_ASMPRINTER_DWARFCOMPILEUNIT_H
  #define LLVM_LIB_CODEGEN_ASMPRINTER_DWARFCOMPILEUNIT_H
  
  #include "DwarfDebug.h"
  #include "DwarfUnit.h"
  #include "llvm/ADT/ArrayRef.h"
  #include "llvm/ADT/DenseMap.h"
  #include "llvm/ADT/SmallVector.h"
  #include "llvm/ADT/StringMap.h"
  #include "llvm/ADT/StringRef.h"
  #include "llvm/BinaryFormat/Dwarf.h"
  #include "llvm/CodeGen/DbgEntityHistoryCalculator.h"
  #include "llvm/CodeGen/LexicalScopes.h"
  #include "llvm/IR/DebugInfoMetadata.h"
  #include "llvm/Support/Casting.h"
  #include <algorithm>
  #include <cassert>
  #include <cstdint>
  #include <memory>
  
  namespace llvm {
  
  class AsmPrinter;
  class DIE;
  class DIELoc;
  class DIEValueList;
  class DwarfFile;
  class GlobalVariable;
  class MCExpr;
  class MCSymbol;
  class MDNode;
  
  enum class UnitKind { Skeleton, Full };
  
  class DwarfCompileUnit final : public DwarfUnit {
    /// A numeric ID unique among all CUs in the module
    unsigned UniqueID;
    bool HasRangeLists = false;
  
    /// The start of the unit line section, this is also
    /// reused in appyStmtList.
    MCSymbol *LineTableStartSym;
  
    /// Skeleton unit associated with this unit.
    DwarfCompileUnit *Skeleton = nullptr;
  
    /// The start of the unit within its section.
    MCSymbol *LabelBegin = nullptr;
  
    /// The start of the unit macro info within macro section.
    MCSymbol *MacroLabelBegin;
  
    using ImportedEntityList = SmallVector<const MDNode *, 8>;
    using ImportedEntityMap = DenseMap<const MDNode *, ImportedEntityList>;
  
    ImportedEntityMap ImportedEntities;
  
    /// GlobalNames - A map of globally visible named entities for this unit.
    StringMap<const DIE *> GlobalNames;
  
    /// GlobalTypes - A map of globally visible types for this unit.
    StringMap<const DIE *> GlobalTypes;
  
    // List of ranges for a given compile unit.
    SmallVector<RangeSpan, 2> CURanges;
  
    // The base address of this unit, if any. Used for relative references in
    // ranges/locs.
    const MCSymbol *BaseAddress = nullptr;
  
    DenseMap<const MDNode *, DIE *> AbstractSPDies;
    DenseMap<const DINode *, std::unique_ptr<DbgEntity>> AbstractEntities;
  
    /// DWO ID for correlating skeleton and split units.
    uint64_t DWOId = 0;
  
    /// Construct a DIE for the given DbgVariable without initializing the
    /// DbgVariable's DIE reference.
    DIE *constructVariableDIEImpl(const DbgVariable &DV, bool Abstract);
  
    bool isDwoUnit() const override;
  
    DenseMap<const MDNode *, DIE *> &getAbstractSPDies() {
      if (isDwoUnit() && !DD->shareAcrossDWOCUs())
        return AbstractSPDies;
      return DU->getAbstractSPDies();
    }
  
    DenseMap<const DINode *, std::unique_ptr<DbgEntity>> &getAbstractEntities() {
      if (isDwoUnit() && !DD->shareAcrossDWOCUs())
        return AbstractEntities;
      return DU->getAbstractEntities();
    }
  
    void finishNonUnitTypeDIE(DIE& D, const DICompositeType *CTy) override;
  
  public:
    DwarfCompileUnit(unsigned UID, const DICompileUnit *Node, AsmPrinter *A,
                     DwarfDebug *DW, DwarfFile *DWU,
                     UnitKind Kind = UnitKind::Full);
  
    bool hasRangeLists() const { return HasRangeLists; }
    unsigned getUniqueID() const { return UniqueID; }
  
    DwarfCompileUnit *getSkeleton() const {
      return Skeleton;
    }
  
    bool includeMinimalInlineScopes() const;
  
    void initStmtList();
  
    /// Apply the DW_AT_stmt_list from this compile unit to the specified DIE.
    void applyStmtList(DIE &D);
  
    /// Get line table start symbol for this unit.
    MCSymbol *getLineTableStartSym() const { return LineTableStartSym; }
  
    /// A pair of GlobalVariable and DIExpression.
    struct GlobalExpr {
      const GlobalVariable *Var;
      const DIExpression *Expr;
    };
  
    struct BaseTypeRef {
      BaseTypeRef(unsigned BitSize, dwarf::TypeKind Encoding) :
        BitSize(BitSize), Encoding(Encoding) {}
      unsigned BitSize;
      dwarf::TypeKind Encoding;
      DIE *Die = nullptr;
    };
  
    std::vector<BaseTypeRef> ExprRefedBaseTypes;
  
    /// Get or create global variable DIE.
    DIE *
    getOrCreateGlobalVariableDIE(const DIGlobalVariable *GV,
                                 ArrayRef<GlobalExpr> GlobalExprs);
  
    DIE *getOrCreateCommonBlock(const DICommonBlock *CB,
                                ArrayRef<GlobalExpr> GlobalExprs);
  
    void addLocationAttribute(DIE *ToDIE, const DIGlobalVariable *GV,
                              ArrayRef<GlobalExpr> GlobalExprs);
  
    /// addLabelAddress - Add a dwarf label attribute data and value using
    /// either DW_FORM_addr or DW_FORM_GNU_addr_index.
    void addLabelAddress(DIE &Die, dwarf::Attribute Attribute,
                         const MCSymbol *Label);
  
    /// addLocalLabelAddress - Add a dwarf label attribute data and value using
    /// DW_FORM_addr only.
    void addLocalLabelAddress(DIE &Die, dwarf::Attribute Attribute,
                              const MCSymbol *Label);
  
    DwarfCompileUnit &getCU() override { return *this; }
  
    unsigned getOrCreateSourceID(const DIFile *File) override;
  
    void addImportedEntity(const DIImportedEntity* IE) {
      DIScope *Scope = IE->getScope();
      assert(Scope && "Invalid Scope encoding!");
      if (!isa<DILocalScope>(Scope))
        // No need to add imported enities that are not local declaration.
        return;
  
      auto *LocalScope = cast<DILocalScope>(Scope)->getNonLexicalBlockFileScope();
      ImportedEntities[LocalScope].push_back(IE);
    }
  
    /// addRange - Add an address range to the list of ranges for this unit.
    void addRange(RangeSpan Range);
  
    void attachLowHighPC(DIE &D, const MCSymbol *Begin, const MCSymbol *End);
  
    /// Find DIE for the given subprogram and attach appropriate
    /// DW_AT_low_pc and DW_AT_high_pc attributes. If there are global
    /// variables in this scope then create and insert DIEs for these
    /// variables.
    DIE &updateSubprogramScopeDIE(const DISubprogram *SP);
  
    void constructScopeDIE(LexicalScope *Scope,
                           SmallVectorImpl<DIE *> &FinalChildren);
  
    /// A helper function to construct a RangeSpanList for a given
    /// lexical scope.
    void addScopeRangeList(DIE &ScopeDIE, SmallVector<RangeSpan, 2> Range);
  
    void attachRangesOrLowHighPC(DIE &D, SmallVector<RangeSpan, 2> Ranges);
  
    void attachRangesOrLowHighPC(DIE &D,
                                 const SmallVectorImpl<InsnRange> &Ranges);
  
    /// This scope represents inlined body of a function. Construct
    /// DIE to represent this concrete inlined copy of the function.
    DIE *constructInlinedScopeDIE(LexicalScope *Scope);
  
    /// Construct new DW_TAG_lexical_block for this scope and
    /// attach DW_AT_low_pc/DW_AT_high_pc labels.
    DIE *constructLexicalScopeDIE(LexicalScope *Scope);
  
    /// constructVariableDIE - Construct a DIE for the given DbgVariable.
    DIE *constructVariableDIE(DbgVariable &DV, bool Abstract = false);
  
    DIE *constructVariableDIE(DbgVariable &DV, const LexicalScope &Scope,
                              DIE *&ObjectPointer);
  
    /// Construct a DIE for the given DbgLabel.
    DIE *constructLabelDIE(DbgLabel &DL, const LexicalScope &Scope);
  
    /// A helper function to create children of a Scope DIE.
    DIE *createScopeChildrenDIE(LexicalScope *Scope,
                                SmallVectorImpl<DIE *> &Children,
                                bool *HasNonScopeChildren = nullptr);
  
    void createBaseTypeDIEs();
  
    /// Construct a DIE for this subprogram scope.
    DIE &constructSubprogramScopeDIE(const DISubprogram *Sub,
                                     LexicalScope *Scope);
  
    DIE *createAndAddScopeChildren(LexicalScope *Scope, DIE &ScopeDIE);
  
    void constructAbstractSubprogramScopeDIE(LexicalScope *Scope);
  
    /// Whether to use the GNU analog for a DWARF5 tag, attribute, or location
    /// atom. Only applicable when emitting otherwise DWARF4-compliant debug info.
    bool useGNUAnalogForDwarf5Feature() const;
  
    /// This takes a DWARF 5 tag and returns it or a GNU analog.
    dwarf::Tag getDwarf5OrGNUTag(dwarf::Tag Tag) const;
  
    /// This takes a DWARF 5 attribute and returns it or a GNU analog.
    dwarf::Attribute getDwarf5OrGNUAttr(dwarf::Attribute Attr) const;
  
    /// This takes a DWARF 5 location atom and either returns it or a GNU analog.
    dwarf::LocationAtom getDwarf5OrGNULocationAtom(dwarf::LocationAtom Loc) const;
  
    /// Construct a call site entry DIE describing a call within \p Scope to a
    /// callee described by \p CalleeDIE.
    /// \p CalleeDIE is a declaration or definition subprogram DIE for the callee.
    /// For indirect calls \p CalleeDIE is set to nullptr.
    /// \p IsTail specifies whether the call is a tail call.
    /// \p PCAddr points to the PC value after the call instruction.
    /// \p CallAddr points to the PC value at the call instruction (or is null).
    /// \p CallReg is a register location for an indirect call. For direct calls
    /// the \p CallReg is set to 0.
    DIE &constructCallSiteEntryDIE(DIE &ScopeDIE, DIE *CalleeDIE, bool IsTail,
                                   const MCSymbol *PCAddr,
                                   const MCSymbol *CallAddr, unsigned CallReg);
    /// Construct call site parameter DIEs for the \p CallSiteDIE. The \p Params
    /// were collected by the \ref collectCallSiteParameters.
    /// Note: The order of parameters does not matter, since debuggers recognize
    ///       call site parameters by the DW_AT_location attribute.
    void constructCallSiteParmEntryDIEs(DIE &CallSiteDIE,
                                        SmallVector<DbgCallSiteParam, 4> &Params);
  
    /// Construct import_module DIE.
    DIE *constructImportedEntityDIE(const DIImportedEntity *Module);
  
    void finishSubprogramDefinition(const DISubprogram *SP);
    void finishEntityDefinition(const DbgEntity *Entity);
  
    /// Find abstract variable associated with Var.
    using InlinedEntity = DbgValueHistoryMap::InlinedEntity;
    DbgEntity *getExistingAbstractEntity(const DINode *Node);
    void createAbstractEntity(const DINode *Node, LexicalScope *Scope);
  
    /// Set the skeleton unit associated with this unit.
    void setSkeleton(DwarfCompileUnit &Skel) { Skeleton = &Skel; }
  
    unsigned getHeaderSize() const override {
      // DWARF v5 added the DWO ID to the header for split/skeleton units.
      unsigned DWOIdSize =
          DD->getDwarfVersion() >= 5 && DD->useSplitDwarf() ? sizeof(uint64_t)
                                                            : 0;
      return DwarfUnit::getHeaderSize() + DWOIdSize;
    }
    unsigned getLength() {
      return sizeof(uint32_t) + // Length field
          getHeaderSize() + getUnitDie().getSize();
    }
  
    void emitHeader(bool UseOffsets) override;
  
    /// Add the DW_AT_addr_base attribute to the unit DIE.
    void addAddrTableBase();
  
    MCSymbol *getLabelBegin() const {
      assert(LabelBegin && "LabelBegin is not initialized");
      return LabelBegin;
    }
  
    MCSymbol *getMacroLabelBegin() const {
      return MacroLabelBegin;
    }
  
    /// Add a new global name to the compile unit.
    void addGlobalName(StringRef Name, const DIE &Die,
                       const DIScope *Context) override;
  
    /// Add a new global name present in a type unit to this compile unit.
    void addGlobalNameForTypeUnit(StringRef Name, const DIScope *Context);
  
    /// Add a new global type to the compile unit.
    void addGlobalType(const DIType *Ty, const DIE &Die,
                       const DIScope *Context) override;
  
    /// Add a new global type present in a type unit to this compile unit.
    void addGlobalTypeUnitType(const DIType *Ty, const DIScope *Context);
  
    const StringMap<const DIE *> &getGlobalNames() const { return GlobalNames; }
    const StringMap<const DIE *> &getGlobalTypes() const { return GlobalTypes; }
  
    /// Add DW_AT_location attribute for a DbgVariable based on provided
    /// MachineLocation.
    void addVariableAddress(const DbgVariable &DV, DIE &Die,
                            MachineLocation Location);
    /// Add an address attribute to a die based on the location provided.
    void addAddress(DIE &Die, dwarf::Attribute Attribute,
                    const MachineLocation &Location);
  
    /// Start with the address based on the location provided, and generate the
    /// DWARF information necessary to find the actual variable (navigating the
    /// extra location information encoded in the type) based on the starting
    /// location.  Add the DWARF information to the die.
    void addComplexAddress(const DbgVariable &DV, DIE &Die,
                           dwarf::Attribute Attribute,
                           const MachineLocation &Location);
  
    /// Add a Dwarf loclistptr attribute data and value.
    void addLocationList(DIE &Die, dwarf::Attribute Attribute, unsigned Index);
    void applyVariableAttributes(const DbgVariable &Var, DIE &VariableDie);
  
    /// Add a Dwarf expression attribute data and value.
    void addExpr(DIELoc &Die, dwarf::Form Form, const MCExpr *Expr);
  
    void applySubprogramAttributesToDefinition(const DISubprogram *SP,
                                               DIE &SPDie);
  
    void applyLabelAttributes(const DbgLabel &Label, DIE &LabelDie);
  
    /// getRanges - Get the list of ranges for this unit.
    const SmallVectorImpl<RangeSpan> &getRanges() const { return CURanges; }
    SmallVector<RangeSpan, 2> takeRanges() { return std::move(CURanges); }
  
    void setBaseAddress(const MCSymbol *Base) { BaseAddress = Base; }
    const MCSymbol *getBaseAddress() const { return BaseAddress; }
  
    uint64_t getDWOId() const { return DWOId; }
    void setDWOId(uint64_t DwoId) { DWOId = DwoId; }
  
    bool hasDwarfPubSections() const;
  
    void addBaseTypeRef(DIEValueList &Die, int64_t Idx);
  };
  
  } // end namespace llvm
  
  #endif // LLVM_LIB_CODEGEN_ASMPRINTER_DWARFCOMPILEUNIT_H
  