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_DWARF_DWARFABBREVIATIONDECLARATION_H 10 #define LLVM_DEBUGINFO_DWARF_DWARFABBREVIATIONDECLARATION_H 11 12 #include "llvm/ADT/Optional.h" 13 #include "llvm/ADT/SmallVector.h" 14 #include "llvm/ADT/iterator_range.h" 15 #include "llvm/BinaryFormat/Dwarf.h" 16 #include "llvm/Support/DataExtractor.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 27 class DWARFAbbreviationDeclaration { 28 public: 29 struct AttributeSpec { 30 AttributeSpec(dwarf::Attribute A, dwarf::Form F, int64_t Value) 31 : Attr(A), Form(F), Value(Value) { 32 assert(isImplicitConst()); 33 } 34 AttributeSpec(dwarf::Attribute A, dwarf::Form F, Optional<uint8_t> ByteSize) 35 : Attr(A), Form(F) { 36 assert(!isImplicitConst()); 37 this->ByteSize.HasByteSize = ByteSize.hasValue(); 38 if (this->ByteSize.HasByteSize) 39 this->ByteSize.ByteSize = *ByteSize; 40 } 41 42 dwarf::Attribute Attr; 43 dwarf::Form Form; 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 { 74 assert(isImplicitConst()); 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 }; 84 using AttributeSpecVector = SmallVector<AttributeSpec, 8>; 85 86 DWARFAbbreviationDeclaration(); 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 = 94 iterator_range<AttributeSpecVector::const_iterator>; 95 96 attr_iterator_range attributes() const { 97 return attr_iterator_range(AttributeSpecs.begin(), AttributeSpecs.end()); 98 } 99 100 dwarf::Form getFormByIndex(uint32_t idx) const { 101 assert(idx < AttributeSpecs.size()); 102 return AttributeSpecs[idx].Form; 103 } 104 105 size_t getNumAttributes() const { 106 return AttributeSpecs.size(); 107 } 108 109 dwarf::Attribute getAttrByIndex(uint32_t idx) const { 110 assert(idx < AttributeSpecs.size()); 111 return AttributeSpecs[idx].Attr; 112 } 113 114 bool getAttrIsImplicitConstByIndex(uint32_t idx) const { 115 assert(idx < AttributeSpecs.size()); 116 return AttributeSpecs[idx].isImplicitConst(); 117 } 118 119 int64_t getAttrImplicitConstValueByIndex(uint32_t idx) const { 120 assert(idx < AttributeSpecs.size()); 121 return AttributeSpecs[idx].getImplicitConstValue(); 122 } 123 124 /// Get the index of the specified attribute. 125 /// 126 /// Searches the this abbreviation declaration for the index of the specified 127 /// attribute. 128 /// 129 /// \param attr DWARF attribute to search for. 130 /// \returns Optional index of the attribute if found, None otherwise. 131 Optional<uint32_t> findAttributeIndex(dwarf::Attribute attr) const; 132 133 /// Extract a DWARF form value from a DIE specified by DIE offset. 134 /// 135 /// Extract an attribute value for a DWARFUnit given the DIE offset and the 136 /// attribute. 137 /// 138 /// \param DIEOffset the DIE offset that points to the ULEB128 abbreviation 139 /// code in the .debug_info data. 140 /// \param Attr DWARF attribute to search for. 141 /// \param U the DWARFUnit the contains the DIE. 142 /// \returns Optional DWARF form value if the attribute was extracted. 143 Optional<DWARFFormValue> getAttributeValue(const uint64_t DIEOffset, 144 const dwarf::Attribute Attr, 145 const DWARFUnit &U) const; 146 147 /// Compute an offset from a DIE specified by DIE offset and attribute index. 148 /// 149 /// \param AttrIndex an index of DWARF attribute. 150 /// \param DIEOffset the DIE offset that points to the ULEB128 abbreviation 151 /// code in the .debug_info data. 152 /// \param U the DWARFUnit the contains the DIE. 153 /// \returns an offset of the attribute. 154 uint64_t getAttributeOffsetFromIndex(uint32_t AttrIndex, uint64_t DIEOffset, 155 const DWARFUnit &U) const; 156 157 /// Extract a DWARF form value from a DIE speccified by attribute index and 158 /// its offset. 159 /// 160 /// \param AttrIndex an index of DWARF attribute. 161 /// \param Offset offset of the attribute. 162 /// \param U the DWARFUnit the contains the DIE. 163 /// \returns Optional DWARF form value if the attribute was extracted. 164 Optional<DWARFFormValue> 165 getAttributeValueFromOffset(uint32_t AttrIndex, uint64_t Offset, 166 const DWARFUnit &U) const; 167 168 bool extract(DataExtractor Data, uint64_t* OffsetPtr); 169 void dump(raw_ostream &OS) const; 170 171 // Return an optional byte size of all attribute data in this abbreviation 172 // if a constant byte size can be calculated given a DWARFUnit. This allows 173 // DWARF parsing to be faster as many DWARF DIEs have a fixed byte size. 174 Optional<size_t> getFixedAttributesByteSize(const DWARFUnit &U) const; 175 176 private: 177 void clear(); 178 179 /// A helper structure that can quickly determine the size in bytes of an 180 /// abbreviation declaration. 181 struct FixedSizeInfo { 182 /// The fixed byte size for fixed size forms. 183 uint16_t NumBytes = 0; 184 /// Number of DW_FORM_address forms in this abbrevation declaration. 185 uint8_t NumAddrs = 0; 186 /// Number of DW_FORM_ref_addr forms in this abbrevation declaration. 187 uint8_t NumRefAddrs = 0; 188 /// Number of 4 byte in DWARF32 and 8 byte in DWARF64 forms. 189 uint8_t NumDwarfOffsets = 0; 190 191 FixedSizeInfo() = default; 192 193 /// Calculate the fixed size in bytes given a DWARFUnit. 194 /// 195 /// \param U the DWARFUnit to use when determing the byte size. 196 /// \returns the size in bytes for all attribute data in this abbreviation. 197 /// The returned size does not include bytes for the ULEB128 abbreviation 198 /// code 199 size_t getByteSize(const DWARFUnit &U) const; 200 }; 201 202 uint32_t Code; 203 dwarf::Tag Tag; 204 uint8_t CodeByteSize; 205 bool HasChildren; 206 AttributeSpecVector AttributeSpecs; 207 /// If this abbreviation has a fixed byte size then FixedAttributeSize member 208 /// variable below will have a value. 209 Optional<FixedSizeInfo> FixedAttributeSize; 210 }; 211 212 } // end namespace llvm 213 214 #endif // LLVM_DEBUGINFO_DWARF_DWARFABBREVIATIONDECLARATION_H 215