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_DWARF_DWARFDATAEXTRACTOR_H
10#define LLVM_DEBUGINFO_DWARF_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_DWARF_DWARFDATAEXTRACTOR_H
91