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      1 //===- DWARFAcceleratorTable.h ----------------------------------*- C++ -*-===//
      2 //
      3 //                     The LLVM Compiler Infrastructure
      4 //
      5 // This file is distributed under the University of Illinois Open Source
      6 // License. See LICENSE.TXT for details.
      7 //
      8 //===----------------------------------------------------------------------===//
      9 
     10 #ifndef LLVM_DEBUGINFO_DWARFACCELERATORTABLE_H
     11 #define LLVM_DEBUGINFO_DWARFACCELERATORTABLE_H
     12 
     13 #include "llvm/ADT/SmallVector.h"
     14 #include "llvm/BinaryFormat/Dwarf.h"
     15 #include "llvm/DebugInfo/DWARF/DWARFDataExtractor.h"
     16 #include "llvm/DebugInfo/DWARF/DWARFFormValue.h"
     17 #include <cstdint>
     18 #include <utility>
     19 
     20 namespace llvm {
     21 
     22 class raw_ostream;
     23 
     24 /// This implements the Apple accelerator table format, a precursor of the
     25 /// DWARF 5 accelerator table format.
     26 /// TODO: Factor out a common base class for both formats.
     27 class DWARFAcceleratorTable {
     28   struct Header {
     29     uint32_t Magic;
     30     uint16_t Version;
     31     uint16_t HashFunction;
     32     uint32_t NumBuckets;
     33     uint32_t NumHashes;
     34     uint32_t HeaderDataLength;
     35   };
     36 
     37   struct HeaderData {
     38     using AtomType = uint16_t;
     39     using Form = dwarf::Form;
     40 
     41     uint32_t DIEOffsetBase;
     42     SmallVector<std::pair<AtomType, Form>, 3> Atoms;
     43   };
     44 
     45   struct Header Hdr;
     46   struct HeaderData HdrData;
     47   DWARFDataExtractor AccelSection;
     48   DataExtractor StringSection;
     49   bool IsValid = false;
     50 
     51 public:
     52   /// An iterator for the entries associated with one key. Each entry can have
     53   /// multiple DWARFFormValues.
     54   class ValueIterator : public std::iterator<std::input_iterator_tag,
     55                                             ArrayRef<DWARFFormValue>> {
     56     const DWARFAcceleratorTable *AccelTable = nullptr;
     57     SmallVector<DWARFFormValue, 3> AtomForms; ///< The decoded data entry.
     58 
     59     unsigned DataOffset = 0; ///< Offset into the section.
     60     unsigned Data = 0; ///< Current data entry.
     61     unsigned NumData = 0; ///< Number of data entries.
     62 
     63     /// Advance the iterator.
     64     void Next();
     65   public:
     66     /// Construct a new iterator for the entries at \p DataOffset.
     67     ValueIterator(const DWARFAcceleratorTable &AccelTable, unsigned DataOffset);
     68     /// End marker.
     69     ValueIterator() = default;
     70 
     71     const ArrayRef<DWARFFormValue> operator*() const {
     72       return AtomForms;
     73     }
     74     ValueIterator &operator++() { Next(); return *this; }
     75     ValueIterator operator++(int) {
     76       ValueIterator I = *this;
     77       Next();
     78       return I;
     79     }
     80     friend bool operator==(const ValueIterator &A, const ValueIterator &B) {
     81       return A.NumData == B.NumData && A.DataOffset == B.DataOffset;
     82     }
     83     friend bool operator!=(const ValueIterator &A, const ValueIterator &B) {
     84       return !(A == B);
     85     }
     86   };
     87 
     88 
     89   DWARFAcceleratorTable(const DWARFDataExtractor &AccelSection,
     90                         DataExtractor StringSection)
     91       : AccelSection(AccelSection), StringSection(StringSection) {}
     92 
     93   bool extract();
     94   uint32_t getNumBuckets();
     95   uint32_t getNumHashes();
     96   uint32_t getSizeHdr();
     97   uint32_t getHeaderDataLength();
     98   ArrayRef<std::pair<HeaderData::AtomType, HeaderData::Form>> getAtomsDesc();
     99   bool validateForms();
    100 
    101   /// Return information related to the DWARF DIE we're looking for when
    102   /// performing a lookup by name.
    103   ///
    104   /// \param HashDataOffset an offset into the hash data table
    105   /// \returns <DieOffset, DieTag>
    106   /// DieOffset is the offset into the .debug_info section for the DIE
    107   /// related to the input hash data offset.
    108   /// DieTag is the tag of the DIE
    109   std::pair<uint32_t, dwarf::Tag> readAtoms(uint32_t &HashDataOffset);
    110   void dump(raw_ostream &OS) const;
    111 
    112   /// Look up all entries in the accelerator table matching \c Key.
    113   iterator_range<ValueIterator> equal_range(StringRef Key) const;
    114 };
    115 
    116 } // end namespace llvm
    117 
    118 #endif // LLVM_DEBUGINFO_DWARFACCELERATORTABLE_H
    119