DwarfCompileUnit.h

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//===- 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/MapVector.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 <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 {
  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 macro info within macro section.
  MCSymbol *MacroLabelBegin;
 
  /// 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;
 
  using MDNodeSetVector =
      SetVector<const MDNode *, SmallVector<const MDNode *, 4>,
                SmallPtrSet<const MDNode *, 4>>;
 
  // List of entities (either static locals, types or imports) that
  // belong to subprograms within this CU.
  MDNodeSetVector DeferredLocalDecls;
 
  // List of concrete lexical block scopes belong to subprograms within this CU.
  DenseMap<const DILocalScope *, DIE *> LexicalBlockDIEs;
 
  // List of abstract local scopes (either DISubprogram or DILexicalBlock).
  DenseMap<const DILocalScope *, DIE *> AbstractLocalScopeDIEs;
  SmallPtrSet<const DISubprogram *, 8> FinalizedAbstractSubprograms;
 
  // Local scopes (either DISubprogram or DILexicalBlock) used as a context of
  // DIEs before it was known whether their subprograms have abstract DIEs,
  // mapped to the pending DIEs holding those DIEs until
  // resolvePendingLocalScopeDIEs() moves them to the final scope DIEs.
  MapVector<const DILocalScope *, DIE *> PendingLocalScopeDIEs;
 
  // Parent of the pending DIEs. It is the first child of the unit DIE until
  // resolvePendingLocalScopeDIEs() removes it.
  DIE *PendingLocalScopesDIE = nullptr;
 
  // List of inlined lexical block scopes that belong to subprograms within this
  // CU.
  DenseMap<const DILocalScope *, SmallVector<DIE *, 2>> InlinedLocalScopeDIEs;
 
  DenseMap<const DINode *, std::unique_ptr<DbgEntity>> AbstractEntities;
 
  /// Cache of artificial DIEs created for DW_OP_LLVM_implicit_pointer
  /// lowering, keyed by (pointee type, constant value). Enables reuse when
  /// multiple pointer variables reference the same constant.
  DenseMap<std::pair<const DIType *, int64_t>, DIE *> ImplicitPointerDIEs;
 
  /// DWO ID for correlating skeleton and split units.
  uint64_t DWOId = 0;
 
  const DIFile *LastFile = nullptr;
  unsigned LastFileID;
 
  /// \anchor applyConcreteDbgVariableAttribute
  /// \name applyConcreteDbgVariableAttribute
  /// Overload set which applies attributes to \c VariableDie based on
  /// the active variant of \c DV, which is passed as the first argument.
  ///@{
 
  /// See \ref applyConcreteDbgVariableAttribute
  void applyConcreteDbgVariableAttributes(const Loc::Single &Single,
                                          const DbgVariable &DV,
                                          DIE &VariableDie);
  /// See \ref applyConcreteDbgVariableAttribute
  void applyConcreteDbgVariableAttributes(const Loc::Multi &Multi,
                                          const DbgVariable &DV,
                                          DIE &VariableDie);
  /// See \ref applyConcreteDbgVariableAttribute
  void applyConcreteDbgVariableAttributes(const Loc::MMI &MMI,
                                          const DbgVariable &DV,
                                          DIE &VariableDie);
  /// See \ref applyConcreteDbgVariableAttribute
  void applyConcreteDbgVariableAttributes(const Loc::EntryValue &EntryValue,
                                          const DbgVariable &DV,
                                          DIE &VariableDie);
  /// See \ref applyConcreteDbgVariableAttribute
  void applyConcreteDbgVariableAttributes(const std::monostate &,
                                          const DbgVariable &DV,
                                          DIE &VariableDie);
 
  ///@}
 
  /// Lower DW_OP_LLVM_implicit_pointer by creating an artificial variable DIE
  /// for the dereferenced value and emitting DW_OP_implicit_pointer (DWARF 5)
  /// or DW_OP_GNU_implicit_pointer (DWARF 4) for the pointer's location.
  ///
  /// \returns true if the implicit pointer was handled successfully.
  bool emitImplicitPointerLocation(const Loc::Single &Single,
                                   const DbgVariable &DV, DIE &VariableDie);
 
  bool isDwoUnit() const override;
 
  DenseMap<const DILocalScope *, DIE *> &getAbstractScopeDIEs() {
    if (isDwoUnit() && !DD->shareAcrossDWOCUs())
      return AbstractLocalScopeDIEs;
    return DU->getAbstractScopeDIEs();
  }
 
  DenseMap<const DINode *, std::unique_ptr<DbgEntity>> &getAbstractEntities() {
    if (isDwoUnit() && !DD->shareAcrossDWOCUs())
      return AbstractEntities;
    return DU->getAbstractEntities();
  }
 
  auto &getFinalizedAbstractSubprograms() {
    if (isDwoUnit() && !DD->shareAcrossDWOCUs())
      return FinalizedAbstractSubprograms;
    return DU->getFinalizedAbstractSubprograms();
  }
 
  void finishNonUnitTypeDIE(DIE& D, const DICompositeType *CTy) override;
 
  /// Add info for Wasm-global-based relocation.
  void addWasmRelocBaseGlobal(DIELoc *Loc, StringRef GlobalName,
                              uint64_t GlobalIndex);
 
  /// Create context DIE for abstract subprogram.
  /// \returns The context DIE and the compile unit where abstract
  ///          DIE should be constructed.
  std::pair<DIE *, DwarfCompileUnit *>
  getOrCreateAbstractSubprogramContextDIE(const DISubprogram *SP);
 
  /// Create new DIE for abstract subprogram.
  DIE &createAbstractSubprogramDIE(const DISubprogram *SP, DIE *ContextDIE,
                                   DwarfCompileUnit *ContextCU);
 
  /// Get the DIE to be used as a parent of DIEs of entities local to \p Scope,
  /// which must not be a DILexicalBlockFile.
  ///
  /// The DIE belongs to the abstract tree if the subprogram of \p Scope has an
  /// abstract DIE, and to the concrete tree otherwise. Until all functions are
  /// processed, this may be a pending DIE, see
  /// resolvePendingLocalScopeDIEs(). If there is no DIE for \p Scope in the
  /// tree, the DIE of the closest enclosing scope is returned.
  DIE *getOrCreateLocalScopeDIE(const DILocalScope *Scope);
 
  /// Get or create the pending DIE of \p Scope.
  DIE &getOrCreatePendingLocalScopeDIE(const DILocalScope *Scope);
 
  /// Add a location exprloc to \p DIE with attribute \p Attribute at
  /// for \p Location modified by raw DIExpression \p Expr.
  void addLocationWithExpr(DIE &Die, dwarf::Attribute Attribute,
                           const MachineLocation &Location,
                           ArrayRef<uint64_t> Expr);
 
public:
  DwarfCompileUnit(unsigned UID, const DICompileUnit *Node, AsmPrinter *A,
                   DwarfDebug *DW, DwarfFile *DWU,
                   UnitKind Kind = UnitKind::Full);
 
  bool hasRangeLists() const { return HasRangeLists; }
 
  DwarfCompileUnit *getSkeleton() const {
    return Skeleton;
  }
 
  bool includeMinimalInlineScopes() const;
 
  bool emitFuncLineTableOffsets() 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;
 
  /// 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, DW_AT_high_pc and DW_AT_LLVM_stmt_sequence attributes.
  /// If there are global variables in this scope then create and insert DIEs
  /// for these variables.
  DIE &updateSubprogramScopeDIE(const DISubprogram *SP, const Function &F,
                                MCSymbol *LineTableSym);
 
  void constructScopeDIE(LexicalScope *Scope, DIE &ParentScopeDIE);
 
  /// 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 an inlined body of a function. Construct a
  /// DIE to represent this concrete inlined copy of the function.
  DIE *constructInlinedScopeDIE(LexicalScope *Scope, DIE &ParentScopeDIE);
 
  /// Get if available or create a new DW_TAG_lexical_block for the given
  /// LexicalScope and attach DW_AT_low_pc/DW_AT_high_pc labels.
  DIE *getOrCreateLexicalBlockDIE(LexicalScope *Scope, DIE &ParentDIE);
 
  /// Construct a DIE for the given DbgVariable.
  DIE *constructVariableDIE(DbgVariable &DV, bool Abstract = false);
 
  /// Convenience overload which writes the DIE pointer into an out variable
  /// ObjectPointer in addition to returning it.
  DIE *constructVariableDIE(DbgVariable &DV, const LexicalScope &Scope,
                            DIE *&ObjectPointer);
 
  /// Construct a DIE for the given DbgLabel.
  DIE *constructLabelDIE(DbgLabel &DL, const LexicalScope &Scope);
 
  void createBaseTypeDIEs();
 
  /// Construct a DIE for a given scope.
  /// This instance of 'getOrCreateContextDIE()' can handle DILocalScope.
  DIE *getOrCreateContextDIE(const DIScope *Ty) override;
 
  /// Move DIEs of function-local entities from pending DIEs to the DIEs of
  /// their scopes in abstract or concrete trees. Must be called after all
  /// functions are processed, when it is known which subprograms have
  /// abstract DIEs.
  void resolvePendingLocalScopeDIEs();
 
  DIE *getOrCreateSubprogramDIE(const DISubprogram *SP, const Function *F,
                                bool Minimal = false) override;
 
  /// Construct a DIE for this subprogram scope.
  DIE &constructSubprogramScopeDIE(const DISubprogram *Sub, const Function &F,
                                   LexicalScope *Scope, MCSymbol *LineTableSym);
 
  DIE *createAndAddScopeChildren(LexicalScope *Scope, DIE &ScopeDIE);
 
  /// Create an abstract subprogram DIE, that should later be populated
  /// by \ref constructAbstractSubprogramScopeDIE.
  DIE &getOrCreateAbstractSubprogramDIE(const DISubprogram *SP);
  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 CalleeSP and \p CalleeF.
  /// \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 CallTarget a location holding the target address for an indirect call.
  ///               For direct calls \p CallTarget register is set to 0.
  /// \p Offset from \p CallTarget register value if the location is indirect.
  DIE &constructCallSiteEntryDIE(DIE &ScopeDIE, const DISubprogram *CalleeSP,
                                 const Function *CalleeF, bool IsTail,
                                 const MCSymbol *PCAddr,
                                 const MCSymbol *CallAddr,
                                 MachineLocation CallTarget, int64_t Offset,
                                 DIType *AllocSiteTy);
  /// 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);
 
  /// Get or create a DIE for an imported entity.
  DIE *getOrCreateImportedEntityDIE(const DIImportedEntity *IE);
  DIE *constructImportedEntityDIE(const DIImportedEntity *IE);
 
  void finishSubprogramDefinition(const DISubprogram *SP);
  void finishEntityDefinition(const DbgEntity *Entity);
  void attachLexicalScopesAbstractOrigins();
 
  /// 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 Asm->getUnitLengthFieldByteSize() + // Length field
           getHeaderSize() + getUnitDie().getSize();
  }
 
  void emitHeader(bool UseOffsets) override;
 
  /// Add the DW_AT_addr_base attribute to the unit DIE.
  void addAddrTableBase();
 
  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 addGlobalTypeImpl(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);
 
  /// Add a memory location exprloc to \p DIE with attribute \p Attribute
  /// at \p Location + \p Offset.
  void addMemoryLocation(DIE &Die, dwarf::Attribute Attribute,
                         const MachineLocation &Location, int64_t Offset);
  /// 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 DIExpression *DIExpr, 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);
 
  /// Add attributes to \p Var which reflect the common attributes of \p
  /// VariableDie, namely those which are not dependant on the active variant.
  void applyCommonDbgVariableAttributes(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);
 
  MDNodeSetVector &getDeferredLocalDecls() { return DeferredLocalDecls; }
 
  void addLinkageNamesToDeclarations(const DwarfDebug &DD,
                                     const DISubprogram &CalleeSP,
                                     DIE &CalleeDIE);
};
 
} // end namespace llvm
 
#endif // LLVM_LIB_CODEGEN_ASMPRINTER_DWARFCOMPILEUNIT_H