1//===- DWARFDataExtractor.h -------------------------------------*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#ifndef LLVM_DEBUGINFO_DWARFDATAEXTRACTOR_H
10#define LLVM_DEBUGINFO_DWARFDATAEXTRACTOR_H
11
12#include "llvm/BinaryFormat/Dwarf.h"
13#include "llvm/DebugInfo/DWARF/DWARFSection.h"
14#include "llvm/Support/DataExtractor.h"
15
16namespace llvm {
17class DWARFObject;
18
19/// A DataExtractor (typically for an in-memory copy of an object-file section)
20/// plus a relocation map for that section, if there is one.
21class DWARFDataExtractor : public DataExtractor {
22  const DWARFObject *Obj = nullptr;
23  const DWARFSection *Section = nullptr;
24
25public:
26  /// Constructor for the normal case of extracting data from a DWARF section.
27  /// The DWARFSection's lifetime must be at least as long as the extractor's.
28  DWARFDataExtractor(const DWARFObject &Obj, const DWARFSection &Section,
29                     bool IsLittleEndian, uint8_t AddressSize)
30      : DataExtractor(Section.Data, IsLittleEndian, AddressSize), Obj(&Obj),
31        Section(&Section) {}
32
33  /// Constructor for cases when there are no relocations.
34  DWARFDataExtractor(StringRef Data, bool IsLittleEndian, uint8_t AddressSize)
35    : DataExtractor(Data, IsLittleEndian, AddressSize) {}
36  DWARFDataExtractor(ArrayRef<uint8_t> Data, bool IsLittleEndian,
37                     uint8_t AddressSize)
38      : DataExtractor(
39            StringRef(reinterpret_cast<const char *>(Data.data()), Data.size()),
40            IsLittleEndian, AddressSize) {}
41
42  /// Truncating constructor
43  DWARFDataExtractor(const DWARFDataExtractor &Other, size_t Length)
44      : DataExtractor(Other.getData().substr(0, Length), Other.isLittleEndian(),
45                      Other.getAddressSize()),
46        Obj(Other.Obj), Section(Other.Section) {}
47
48  /// Extracts the DWARF "initial length" field, which can either be a 32-bit
49  /// value smaller than 0xfffffff0, or the value 0xffffffff followed by a
50  /// 64-bit length. Returns the actual length, and the DWARF format which is
51  /// encoded in the field. In case of errors, it returns {0, DWARF32} and
52  /// leaves the offset unchanged.
53  std::pair<uint64_t, dwarf::DwarfFormat>
54  getInitialLength(uint64_t *Off, Error *Err = nullptr) const;
55
56  std::pair<uint64_t, dwarf::DwarfFormat> getInitialLength(Cursor &C) const {
57    return getInitialLength(&getOffset(C), &getError(C));
58  }
59
60  /// Extracts a value and applies a relocation to the result if
61  /// one exists for the given offset.
62  uint64_t getRelocatedValue(uint32_t Size, uint64_t *Off,
63                             uint64_t *SectionIndex = nullptr,
64                             Error *Err = nullptr) const;
65  uint64_t getRelocatedValue(Cursor &C, uint32_t Size,
66                             uint64_t *SectionIndex = nullptr) const {
67    return getRelocatedValue(Size, &getOffset(C), SectionIndex, &getError(C));
68  }
69
70  /// Extracts an address-sized value and applies a relocation to the result if
71  /// one exists for the given offset.
72  uint64_t getRelocatedAddress(uint64_t *Off, uint64_t *SecIx = nullptr) const {
73    return getRelocatedValue(getAddressSize(), Off, SecIx);
74  }
75  uint64_t getRelocatedAddress(Cursor &C, uint64_t *SecIx = nullptr) const {
76    return getRelocatedValue(getAddressSize(), &getOffset(C), SecIx,
77                             &getError(C));
78  }
79
80  /// Extracts a DWARF-encoded pointer in \p Offset using \p Encoding.
81  /// There is a DWARF encoding that uses a PC-relative adjustment.
82  /// For these values, \p AbsPosOffset is used to fix them, which should
83  /// reflect the absolute address of this pointer.
84  Optional<uint64_t> getEncodedPointer(uint64_t *Offset, uint8_t Encoding,
85                                       uint64_t AbsPosOffset = 0) const;
86};
87
88} // end namespace llvm
89
90#endif // LLVM_DEBUGINFO_DWARFDATAEXTRACTOR_H
91