DWARFDebugLine.h

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//===- 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/ADT/Optional.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/DebugInfo/DIContext.h"
#include "llvm/DebugInfo/DWARF/DWARFCompileUnit.h"
#include "llvm/DebugInfo/DWARF/DWARFDataExtractor.h"
#include "llvm/DebugInfo/DWARF/DWARFFormValue.h"
#include "llvm/DebugInfo/DWARF/DWARFRelocMap.h"
#include "llvm/DebugInfo/DWARF/DWARFTypeUnit.h"
#include "llvm/Support/MD5.h"
#include <cstdint>
#include <map>
#include <string>
#include <vector>

namespace llvm {

class DWARFUnit;
class raw_ostream;

class DWARFDebugLine {
public:
  struct FileNameEntry {
    FileNameEntry() = default;

    DWARFFormValue Name;
    uint64_t DirIdx = 0;
    uint64_t ModTime = 0;
    uint64_t Length = 0;
    MD5::MD5Result Checksum;
    DWARFFormValue Source;
  };

  /// Tracks which optional content types are present in a DWARF file name
  /// entry format.
  struct ContentTypeTracker {
    ContentTypeTracker() = default;

    /// Whether filename entries provide a modification timestamp.
    bool HasModTime = false;
    /// Whether filename entries provide a file size.
    bool HasLength = false;
    /// For v5, whether filename entries provide an MD5 checksum.
    bool HasMD5 = false;
    /// For v5, whether filename entries provide source text.
    bool HasSource = false;

    /// Update tracked content types with \p ContentType.
    void trackContentType(dwarf::LineNumberEntryFormat ContentType);
  };

  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, address size (starting in v5), and DWARF32/64 format; these
    /// parameters affect interpretation of forms (used in the directory and
    /// file tables starting with v5).
    dwarf::FormParams FormParams;
    /// The number of bytes following the prologue_length field to the beginning
    /// of the first byte of the statement program itself.
    uint64_t PrologueLength;
    /// In v5, size in bytes of a segment selector.
    uint8_t SegSelectorSize;
    /// 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;
    /// This tracks which optional file format content types are present.
    ContentTypeTracker ContentTypes;
    std::vector<uint8_t> StandardOpcodeLengths;
    std::vector<DWARFFormValue> IncludeDirectories;
    std::vector<FileNameEntry> FileNames;

    const dwarf::FormParams getFormParams() const { return FormParams; }
    uint16_t getVersion() const { return FormParams.Version; }
    uint8_t getAddressSize() const { return FormParams.AddrSize; }
    bool isDWARF64() const { return FormParams.Format == dwarf::DWARF64; }

    uint32_t sizeofTotalLength() const { return isDWARF64() ? 12 : 4; }

    uint32_t sizeofPrologueLength() const { return isDWARF64() ? 8 : 4; }

    bool totalLengthIsValid() const;

    /// Length of the prologue in bytes.
    uint32_t getLength() const {
      return PrologueLength + sizeofTotalLength() + sizeof(getVersion()) +
             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, DIDumpOptions DumpOptions) const;
    Error parse(const DWARFDataExtractor &DebugLineData, uint32_t *OffsetPtr,
                const DWARFContext &Ctx, const DWARFUnit *U = nullptr);
  };

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

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

    static void dumpTableHeader(raw_ostream &OS);

    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, DIDumpOptions DumpOptions) const;
    void clear();

    /// Parse prologue and all rows.
    Error parse(
        DWARFDataExtractor &DebugLineData, uint32_t *OffsetPtr,
        const DWARFContext &Ctx, const DWARFUnit *U,
        std::function<void(Error)> RecoverableErrorCallback,
        raw_ostream *OS = nullptr);

    using RowVector = std::vector<Row>;
    using RowIter = RowVector::const_iterator;
    using SequenceVector = std::vector<Sequence>;
    using SequenceIter = SequenceVector::const_iterator;

    struct Prologue Prologue;
    RowVector Rows;
    SequenceVector Sequences;

  private:
    uint32_t findRowInSeq(const DWARFDebugLine::Sequence &Seq,
                          uint64_t Address) const;
    Optional<StringRef>
    getSourceByIndex(uint64_t FileIndex,
                     DILineInfoSpecifier::FileLineInfoKind Kind) const;
  };

  const LineTable *getLineTable(uint32_t Offset) const;
  Expected<const LineTable *> getOrParseLineTable(
      DWARFDataExtractor &DebugLineData, uint32_t Offset,
      const DWARFContext &Ctx, const DWARFUnit *U,
      std::function<void(Error)> RecoverableErrorCallback);

  /// Helper to allow for parsing of an entire .debug_line section in sequence.
  class SectionParser {
  public:
    using cu_range = DWARFUnitVector::iterator_range;
    using tu_range = DWARFUnitVector::iterator_range;
    using LineToUnitMap = std::map<uint64_t, DWARFUnit *>;

    SectionParser(DWARFDataExtractor &Data, const DWARFContext &C, cu_range CUs,
                  tu_range TUs);

    /// Get the next line table from the section. Report any issues via the
    /// callbacks.
    ///
    /// \param RecoverableErrorCallback - any issues that don't prevent further
    /// parsing of the table will be reported through this callback.
    /// \param UnrecoverableErrorCallback - any issues that prevent further
    /// parsing of the table will be reported through this callback.
    /// \param OS - if not null, the parser will print information about the
    /// table as it parses it.
    LineTable
    parseNext(
        function_ref<void(Error)> RecoverableErrorCallback,
        function_ref<void(Error)> UnrecoverableErrorCallback,
        raw_ostream *OS = nullptr);

    /// Skip the current line table and go to the following line table (if
    /// present) immediately.
    ///
    /// \param ErrorCallback - report any prologue parsing issues via this
    /// callback.
    void skip(function_ref<void(Error)> ErrorCallback);

    /// Indicates if the parser has parsed as much as possible.
    ///
    /// \note Certain problems with the line table structure might mean that
    /// parsing stops before the end of the section is reached.
    bool done() const { return Done; }

    /// Get the offset the parser has reached.
    uint32_t getOffset() const { return Offset; }

  private:
    DWARFUnit *prepareToParse(uint32_t Offset);
    void moveToNextTable(uint32_t OldOffset, const Prologue &P);

    LineToUnitMap LineToUnit;

    DWARFDataExtractor &DebugLineData;
    const DWARFContext &Context;
    uint32_t Offset = 0;
    bool Done = false;
  };

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 = 0;
    struct Row Row;
    struct Sequence Sequence;
  };

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

  LineTableMapTy LineTableMap;
};

} // end namespace llvm

#endif // LLVM_DEBUGINFO_DWARFDEBUGLINE_H