DebugInfo/DWARF/DWARFDebugLine.h

//===- DWARFDebugLine.h -----------------------------------------*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_DEBUGINFO_DWARFDEBUGLINE_H
#define LLVM_DEBUGINFO_DWARFDEBUGLINE_H

#include "llvm/DebugInfo/DIContext.h"
#include "llvm/DebugInfo/DWARF/DWARFRelocMap.h"
#include "llvm/Support/DataExtractor.h"
#include <cstdint>
#include <map>
#include <string>
#include <vector>

namespace llvm {

class raw_ostream;

class DWARFDebugLine {
public:
  DWARFDebugLine(const RelocAddrMap* LineInfoRelocMap) : RelocMap(LineInfoRelocMap) {}

  struct FileNameEntry {
    FileNameEntry() = default;

    const char *Name = nullptr;
    uint64_t DirIdx = 0;
    uint64_t ModTime = 0;
    uint64_t Length = 0;
  };

  struct Prologue {
    Prologue();

    // The size in bytes of the statement information for this compilation unit
    // (not including the total_length field itself).
    uint64_t TotalLength;
    // Version identifier for the statement information format.
    uint16_t Version;
    // The number of bytes following the prologue_length field to the beginning
    // of the first byte of the statement program itself.
    uint64_t PrologueLength;
    // The size in bytes of the smallest target machine instruction. Statement
    // program opcodes that alter the address register first multiply their
    // operands by this value.
    uint8_t MinInstLength;
    // The maximum number of individual operations that may be encoded in an
    // instruction.
    uint8_t MaxOpsPerInst;
    // The initial value of theis_stmtregister.
    uint8_t DefaultIsStmt;
    // This parameter affects the meaning of the special opcodes. See below.
    int8_t LineBase;
    // This parameter affects the meaning of the special opcodes. See below.
    uint8_t LineRange;
    // The number assigned to the first special opcode.
    uint8_t OpcodeBase;
    std::vector<uint8_t> StandardOpcodeLengths;
    std::vector<const char*> IncludeDirectories;
    std::vector<FileNameEntry> FileNames;

    bool IsDWARF64;

    uint32_t sizeofTotalLength() const {
      return IsDWARF64 ? 12 : 4;
    }

    uint32_t sizeofPrologueLength() const {
      return IsDWARF64 ? 8 : 4;
    }

    // Length of the prologue in bytes.
    uint32_t getLength() const {
      return PrologueLength + sizeofTotalLength() + sizeof(Version) +
             sizeofPrologueLength();
    }

    // Length of the line table data in bytes (not including the prologue).
    uint32_t getStatementTableLength() const {
      return TotalLength + sizeofTotalLength() - getLength();
    }

    int32_t getMaxLineIncrementForSpecialOpcode() const {
      return LineBase + (int8_t)LineRange - 1;
    }

    void clear();
    void dump(raw_ostream &OS) const;
    bool parse(DataExtractor debug_line_data, uint32_t *offset_ptr);
  };

  // Standard .debug_line state machine structure.
  struct Row {
    explicit Row(bool default_is_stmt = false);

    /// Called after a row is appended to the matrix.
    void postAppend();
    void reset(bool default_is_stmt);
    void dump(raw_ostream &OS) const;

    static bool orderByAddress(const Row& LHS, const Row& RHS) {
      return LHS.Address < RHS.Address;
    }

    // The program-counter value corresponding to a machine instruction
    // generated by the compiler.
    uint64_t Address;
    // An unsigned integer indicating a source line number. Lines are numbered
    // beginning at 1. The compiler may emit the value 0 in cases where an
    // instruction cannot be attributed to any source line.
    uint32_t Line;
    // An unsigned integer indicating a column number within a source line.
    // Columns are numbered beginning at 1. The value 0 is reserved to indicate
    // that a statement begins at the 'left edge' of the line.
    uint16_t Column;
    // An unsigned integer indicating the identity of the source file
    // corresponding to a machine instruction.
    uint16_t File;
    // An unsigned integer representing the DWARF path discriminator value
    // for this location.
    uint32_t Discriminator;
    // An unsigned integer whose value encodes the applicable instruction set
    // architecture for the current instruction.
    uint8_t Isa;
    // A boolean indicating that the current instruction is the beginning of a
    // statement.
    uint8_t IsStmt:1,
            // A boolean indicating that the current instruction is the
            // beginning of a basic block.
            BasicBlock:1,
            // A boolean indicating that the current address is that of the
            // first byte after the end of a sequence of target machine
            // instructions.
            EndSequence:1,
            // A boolean indicating that the current address is one (of possibly
            // many) where execution should be suspended for an entry breakpoint
            // of a function.
            PrologueEnd:1,
            // A boolean indicating that the current address is one (of possibly
            // many) where execution should be suspended for an exit breakpoint
            // of a function.
            EpilogueBegin:1;
  };

  // Represents a series of contiguous machine instructions. Line table for each
  // compilation unit may consist of multiple sequences, which are not
  // guaranteed to be in the order of ascending instruction address.
  struct Sequence {
    Sequence();

    // Sequence describes instructions at address range [LowPC, HighPC)
    // and is described by line table rows [FirstRowIndex, LastRowIndex).
    uint64_t LowPC;
    uint64_t HighPC;
    unsigned FirstRowIndex;
    unsigned LastRowIndex;
    bool Empty;

    void reset();

    static bool orderByLowPC(const Sequence& LHS, const Sequence& RHS) {
      return LHS.LowPC < RHS.LowPC;
    }

    bool isValid() const {
      return !Empty && (LowPC < HighPC) && (FirstRowIndex < LastRowIndex);
    }

    bool containsPC(uint64_t pc) const {
      return (LowPC <= pc && pc < HighPC);
    }
  };

  struct LineTable {
    LineTable();

    // Represents an invalid row
    const uint32_t UnknownRowIndex = UINT32_MAX;

    void appendRow(const DWARFDebugLine::Row &R) {
      Rows.push_back(R);
    }

    void appendSequence(const DWARFDebugLine::Sequence &S) {
      Sequences.push_back(S);
    }

    // Returns the index of the row with file/line info for a given address,
    // or UnknownRowIndex if there is no such row.
    uint32_t lookupAddress(uint64_t address) const;

    bool lookupAddressRange(uint64_t address, uint64_t size,
                            std::vector<uint32_t> &result) const;

    bool hasFileAtIndex(uint64_t FileIndex) const;

    // Extracts filename by its index in filename table in prologue.
    // Returns true on success.
    bool getFileNameByIndex(uint64_t FileIndex, const char *CompDir,
                            DILineInfoSpecifier::FileLineInfoKind Kind,
                            std::string &Result) const;

    // Fills the Result argument with the file and line information
    // corresponding to Address. Returns true on success.
    bool getFileLineInfoForAddress(uint64_t Address, const char *CompDir,
                                   DILineInfoSpecifier::FileLineInfoKind Kind,
                                   DILineInfo &Result) const;

    void dump(raw_ostream &OS) const;
    void clear();

    /// Parse prologue and all rows.
    bool parse(DataExtractor debug_line_data, const RelocAddrMap *RMap,
               uint32_t *offset_ptr);

    struct Prologue Prologue;
    typedef std::vector<Row> RowVector;
    typedef RowVector::const_iterator RowIter;
    typedef std::vector<Sequence> SequenceVector;
    typedef SequenceVector::const_iterator SequenceIter;
    RowVector Rows;
    SequenceVector Sequences;

  private:
    uint32_t findRowInSeq(const DWARFDebugLine::Sequence &seq,
                          uint64_t address) const;
  };

  const LineTable *getLineTable(uint32_t offset) const;
  const LineTable *getOrParseLineTable(DataExtractor debug_line_data,
                                       uint32_t offset);

private:
  struct ParsingState {
    ParsingState(struct LineTable *LT);

    void resetRowAndSequence();
    void appendRowToMatrix(uint32_t offset);

    // Line table we're currently parsing.
    struct LineTable *LineTable;
    // The row number that starts at zero for the prologue, and increases for
    // each row added to the matrix.
    unsigned RowNumber;
    struct Row Row;
    struct Sequence Sequence;
  };

  typedef std::map<uint32_t, LineTable> LineTableMapTy;
  typedef LineTableMapTy::iterator LineTableIter;
  typedef LineTableMapTy::const_iterator LineTableConstIter;

  const RelocAddrMap *RelocMap;
  LineTableMapTy LineTableMap;
};

} // end namespace llvm

#endif // LLVM_DEBUGINFO_DWARFDEBUGLINE_H