LLVM  10.0.0svn
DWARFAbbreviationDeclaration.h
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1 //===- DWARFAbbreviationDeclaration.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_DWARFABBREVIATIONDECLARATION_H
10 #define LLVM_DEBUGINFO_DWARFABBREVIATIONDECLARATION_H
11 
12 #include "llvm/ADT/Optional.h"
13 #include "llvm/ADT/SmallVector.h"
17 #include <cassert>
18 #include <cstddef>
19 #include <cstdint>
20 
21 namespace llvm {
22 
23 class DWARFFormValue;
24 class DWARFUnit;
25 class raw_ostream;
26 
28 public:
29  struct AttributeSpec {
31  : Attr(A), Form(F), Value(Value) {
33  }
35  : Attr(A), Form(F) {
37  this->ByteSize.HasByteSize = ByteSize.hasValue();
38  if (this->ByteSize.HasByteSize)
39  this->ByteSize.ByteSize = *ByteSize;
40  }
41 
44 
45  private:
46  /// The following field is used for ByteSize for non-implicit_const
47  /// attributes and as value for implicit_const ones, indicated by
48  /// Form == DW_FORM_implicit_const.
49  /// The following cases are distinguished:
50  /// * Form != DW_FORM_implicit_const and HasByteSize is true:
51  /// ByteSize contains the fixed size in bytes for the Form in this
52  /// object.
53  /// * Form != DW_FORM_implicit_const and HasByteSize is false:
54  /// byte size of Form either varies according to the DWARFUnit
55  /// that it is contained in or the value size varies and must be
56  /// decoded from the debug information in order to determine its size.
57  /// * Form == DW_FORM_implicit_const:
58  /// Value contains value for the implicit_const attribute.
59  struct ByteSizeStorage {
60  bool HasByteSize;
61  uint8_t ByteSize;
62  };
63  union {
64  ByteSizeStorage ByteSize;
65  int64_t Value;
66  };
67 
68  public:
69  bool isImplicitConst() const {
70  return Form == dwarf::DW_FORM_implicit_const;
71  }
72 
73  int64_t getImplicitConstValue() const {
75  return Value;
76  }
77 
78  /// Get the fixed byte size of this Form if possible. This function might
79  /// use the DWARFUnit to calculate the size of the Form, like for
80  /// DW_AT_address and DW_AT_ref_addr, so this isn't just an accessor for
81  /// the ByteSize member.
82  Optional<int64_t> getByteSize(const DWARFUnit &U) const;
83  };
85 
87 
88  uint32_t getCode() const { return Code; }
89  uint8_t getCodeByteSize() const { return CodeByteSize; }
90  dwarf::Tag getTag() const { return Tag; }
91  bool hasChildren() const { return HasChildren; }
92 
93  using attr_iterator_range =
95 
97  return attr_iterator_range(AttributeSpecs.begin(), AttributeSpecs.end());
98  }
99 
101  assert(idx < AttributeSpecs.size());
102  return AttributeSpecs[idx].Form;
103  }
104 
105  size_t getNumAttributes() const {
106  return AttributeSpecs.size();
107  }
108 
110  assert(idx < AttributeSpecs.size());
111  return AttributeSpecs[idx].Attr;
112  }
113 
114  /// Get the index of the specified attribute.
115  ///
116  /// Searches the this abbreviation declaration for the index of the specified
117  /// attribute.
118  ///
119  /// \param attr DWARF attribute to search for.
120  /// \returns Optional index of the attribute if found, None otherwise.
122 
123  /// Extract a DWARF form value from a DIE specified by DIE offset.
124  ///
125  /// Extract an attribute value for a DWARFUnit given the DIE offset and the
126  /// attribute.
127  ///
128  /// \param DIEOffset the DIE offset that points to the ULEB128 abbreviation
129  /// code in the .debug_info data.
130  /// \param Attr DWARF attribute to search for.
131  /// \param U the DWARFUnit the contains the DIE.
132  /// \returns Optional DWARF form value if the attribute was extracted.
133  Optional<DWARFFormValue> getAttributeValue(const uint64_t DIEOffset,
134  const dwarf::Attribute Attr,
135  const DWARFUnit &U) const;
136 
137  bool extract(DataExtractor Data, uint64_t* OffsetPtr);
138  void dump(raw_ostream &OS) const;
139 
140  // Return an optional byte size of all attribute data in this abbreviation
141  // if a constant byte size can be calculated given a DWARFUnit. This allows
142  // DWARF parsing to be faster as many DWARF DIEs have a fixed byte size.
144 
145 private:
146  void clear();
147 
148  /// A helper structure that can quickly determine the size in bytes of an
149  /// abbreviation declaration.
150  struct FixedSizeInfo {
151  /// The fixed byte size for fixed size forms.
152  uint16_t NumBytes = 0;
153  /// Number of DW_FORM_address forms in this abbrevation declaration.
154  uint8_t NumAddrs = 0;
155  /// Number of DW_FORM_ref_addr forms in this abbrevation declaration.
156  uint8_t NumRefAddrs = 0;
157  /// Number of 4 byte in DWARF32 and 8 byte in DWARF64 forms.
158  uint8_t NumDwarfOffsets = 0;
159 
160  FixedSizeInfo() = default;
161 
162  /// Calculate the fixed size in bytes given a DWARFUnit.
163  ///
164  /// \param U the DWARFUnit to use when determing the byte size.
165  /// \returns the size in bytes for all attribute data in this abbreviation.
166  /// The returned size does not include bytes for the ULEB128 abbreviation
167  /// code
168  size_t getByteSize(const DWARFUnit &U) const;
169  };
170 
171  uint32_t Code;
172  dwarf::Tag Tag;
173  uint8_t CodeByteSize;
174  bool HasChildren;
175  AttributeSpecVector AttributeSpecs;
176  /// If this abbreviation has a fixed byte size then FixedAttributeSize member
177  /// variable below will have a value.
178  Optional<FixedSizeInfo> FixedAttributeSize;
179 };
180 
181 } // end namespace llvm
182 
183 #endif // LLVM_DEBUGINFO_DWARFABBREVIATIONDECLARATION_H
This class represents lattice values for constants.
Definition: AllocatorList.h:23
Optional< int64_t > getByteSize(const DWARFUnit &U) const
Get the fixed byte size of this Form if possible.
Attribute
Attributes.
Definition: Dwarf.h:102
This provides a very simple, boring adaptor for a begin and end iterator into a range type...
Optional< size_t > getFixedAttributesByteSize(const DWARFUnit &U) const
F(f)
Optional< uint32_t > findAttributeIndex(dwarf::Attribute attr) const
Get the index of the specified attribute.
AttributeSpec(dwarf::Attribute A, dwarf::Form F, int64_t Value)
dwarf::Form getFormByIndex(uint32_t idx) const
AttributeSpec(dwarf::Attribute A, dwarf::Form F, Optional< uint8_t > ByteSize)
Optional< DWARFFormValue > getAttributeValue(const uint64_t DIEOffset, const dwarf::Attribute Attr, const DWARFUnit &U) const
Extract a DWARF form value from a DIE specified by DIE offset.
A range adaptor for a pair of iterators.
This file contains constants used for implementing Dwarf debug support.
bool extract(DataExtractor Data, uint64_t *OffsetPtr)
bool hasValue() const
Definition: Optional.h:259
dwarf::Attribute getAttrByIndex(uint32_t idx) const
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
LLVM Value Representation.
Definition: Value.h:74
This class implements an extremely fast bulk output stream that can only output to a stream...
Definition: raw_ostream.h:45
iterator_range< AttributeSpecVector::const_iterator > attr_iterator_range