1 //===- DWARFAbbreviationDeclaration.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_DWARFABBREVIATIONDECLARATION_H 11 #define LLVM_DEBUGINFO_DWARFABBREVIATIONDECLARATION_H 12 13 #include "llvm/ADT/iterator_range.h" 14 #include "llvm/ADT/Optional.h" 15 #include "llvm/ADT/SmallVector.h" 16 #include "llvm/Support/DataExtractor.h" 17 #include "llvm/Support/Dwarf.h" 18 #include <cassert> 19 #include <cstddef> 20 #include <cstdint> 21 22 namespace llvm { 23 24 class DWARFFormValue; 25 class DWARFUnit; 26 class raw_ostream; 27 28 class DWARFAbbreviationDeclaration { 29 public: 30 struct AttributeSpec { 31 AttributeSpec(dwarf::Attribute A, dwarf::Form F, Optional<int64_t> V) 32 : Attr(A), Form(F), ByteSizeOrValue(V) {} 33 34 dwarf::Attribute Attr; 35 dwarf::Form Form; 36 /// The following field is used for ByteSize for non-implicit_const 37 /// attributes and as value for implicit_const ones, indicated by 38 /// Form == DW_FORM_implicit_const. 39 /// The following cases are distinguished: 40 /// * Form != DW_FORM_implicit_const and ByteSizeOrValue has a value: 41 /// ByteSizeOrValue contains the fixed size in bytes 42 /// for the Form in this object. 43 /// * Form != DW_FORM_implicit_const and ByteSizeOrValue is None: 44 /// byte size of Form either varies according to the DWARFUnit 45 /// that it is contained in or the value size varies and must be 46 /// decoded from the debug information in order to determine its size. 47 /// * Form == DW_FORM_implicit_const: 48 /// ByteSizeOrValue contains value for the implicit_const attribute. 49 Optional<int64_t> ByteSizeOrValue; 50 51 bool isImplicitConst() const { 52 return Form == dwarf::DW_FORM_implicit_const; 53 } 54 55 /// Get the fixed byte size of this Form if possible. This function might 56 /// use the DWARFUnit to calculate the size of the Form, like for 57 /// DW_AT_address and DW_AT_ref_addr, so this isn't just an accessor for 58 /// the ByteSize member. 59 Optional<int64_t> getByteSize(const DWARFUnit &U) const; 60 }; 61 typedef SmallVector<AttributeSpec, 8> AttributeSpecVector; 62 63 DWARFAbbreviationDeclaration(); 64 65 uint32_t getCode() const { return Code; } 66 uint8_t getCodeByteSize() const { return CodeByteSize; } 67 dwarf::Tag getTag() const { return Tag; } 68 bool hasChildren() const { return HasChildren; } 69 70 typedef iterator_range<AttributeSpecVector::const_iterator> 71 attr_iterator_range; 72 73 attr_iterator_range attributes() const { 74 return attr_iterator_range(AttributeSpecs.begin(), AttributeSpecs.end()); 75 } 76 77 dwarf::Form getFormByIndex(uint32_t idx) const { 78 assert(idx < AttributeSpecs.size()); 79 return AttributeSpecs[idx].Form; 80 } 81 82 size_t getNumAttributes() const { 83 return AttributeSpecs.size(); 84 } 85 86 dwarf::Attribute getAttrByIndex(uint32_t idx) const { 87 assert(idx < AttributeSpecs.size()); 88 return AttributeSpecs[idx].Attr; 89 } 90 91 /// Get the index of the specified attribute. 92 /// 93 /// Searches the this abbreviation declaration for the index of the specified 94 /// attribute. 95 /// 96 /// \param attr DWARF attribute to search for. 97 /// \returns Optional index of the attribute if found, None otherwise. 98 Optional<uint32_t> findAttributeIndex(dwarf::Attribute attr) const; 99 100 /// Extract a DWARF form value from a DIE specified by DIE offset. 101 /// 102 /// Extract an attribute value for a DWARFUnit given the DIE offset and the 103 /// attribute. 104 /// 105 /// \param DIEOffset the DIE offset that points to the ULEB128 abbreviation 106 /// code in the .debug_info data. 107 /// \param Attr DWARF attribute to search for. 108 /// \param U the DWARFUnit the contains the DIE. 109 /// \returns Optional DWARF form value if the attribute was extracted. 110 Optional<DWARFFormValue> getAttributeValue(const uint32_t DIEOffset, 111 const dwarf::Attribute Attr, 112 const DWARFUnit &U) const; 113 114 bool extract(DataExtractor Data, uint32_t* OffsetPtr); 115 void dump(raw_ostream &OS) const; 116 117 // Return an optional byte size of all attribute data in this abbreviation 118 // if a constant byte size can be calculated given a DWARFUnit. This allows 119 // DWARF parsing to be faster as many DWARF DIEs have a fixed byte size. 120 Optional<size_t> getFixedAttributesByteSize(const DWARFUnit &U) const; 121 122 private: 123 void clear(); 124 125 /// A helper structure that can quickly determine the size in bytes of an 126 /// abbreviation declaration. 127 struct FixedSizeInfo { 128 /// The fixed byte size for fixed size forms. 129 uint16_t NumBytes = 0; 130 /// Number of DW_FORM_address forms in this abbrevation declaration. 131 uint8_t NumAddrs = 0; 132 /// Number of DW_FORM_ref_addr forms in this abbrevation declaration. 133 uint8_t NumRefAddrs = 0; 134 /// Number of 4 byte in DWARF32 and 8 byte in DWARF64 forms. 135 uint8_t NumDwarfOffsets = 0; 136 137 FixedSizeInfo() = default; 138 139 /// Calculate the fixed size in bytes given a DWARFUnit. 140 /// 141 /// \param U the DWARFUnit to use when determing the byte size. 142 /// \returns the size in bytes for all attribute data in this abbreviation. 143 /// The returned size does not include bytes for the ULEB128 abbreviation 144 /// code 145 size_t getByteSize(const DWARFUnit &U) const; 146 }; 147 148 uint32_t Code; 149 dwarf::Tag Tag; 150 uint8_t CodeByteSize; 151 bool HasChildren; 152 AttributeSpecVector AttributeSpecs; 153 /// If this abbreviation has a fixed byte size then FixedAttributeSize member 154 /// variable below will have a value. 155 Optional<FixedSizeInfo> FixedAttributeSize; 156 }; 157 158 } // end namespace llvm 159 160 #endif // LLVM_DEBUGINFO_DWARFABBREVIATIONDECLARATION_H 161
