1 //===- FunctionInfo.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_GSYM_FUNCTIONINFO_H 10 #define LLVM_DEBUGINFO_GSYM_FUNCTIONINFO_H 11 12 #include "llvm/ADT/SmallString.h" 13 #include "llvm/DebugInfo/GSYM/ExtractRanges.h" 14 #include "llvm/DebugInfo/GSYM/InlineInfo.h" 15 #include "llvm/DebugInfo/GSYM/LineTable.h" 16 #include "llvm/DebugInfo/GSYM/LookupResult.h" 17 #include "llvm/DebugInfo/GSYM/MergedFunctionsInfo.h" 18 #include "llvm/DebugInfo/GSYM/StringTable.h" 19 #include <cstdint> 20 21 namespace llvm { 22 class raw_ostream; 23 24 namespace gsym { 25 26 class GsymReader; 27 /// Function information in GSYM files encodes information for one contiguous 28 /// address range. If a function has discontiguous address ranges, they will 29 /// need to be encoded using multiple FunctionInfo objects. 30 /// 31 /// ENCODING 32 /// 33 /// The function information gets the function start address as an argument 34 /// to the FunctionInfo::decode(...) function. This information is calculated 35 /// from the GSYM header and an address offset from the GSYM address offsets 36 /// table. The encoded FunctionInfo information must be aligned to a 4 byte 37 /// boundary. 38 /// 39 /// The encoded data for a FunctionInfo starts with fixed data that all 40 /// function info objects have: 41 /// 42 /// ENCODING NAME DESCRIPTION 43 /// ========= =========== ==================================================== 44 /// uint32_t Size The size in bytes of this function. 45 /// uint32_t Name The string table offset of the function name. 46 /// 47 /// The optional data in a FunctionInfo object follows this fixed information 48 /// and consists of a stream of tuples that consist of: 49 /// 50 /// ENCODING NAME DESCRIPTION 51 /// ========= =========== ==================================================== 52 /// uint32_t InfoType An "InfoType" enumeration that describes the type 53 /// of optional data that is encoded. 54 /// uint32_t InfoLength The size in bytes of the encoded data that 55 /// immediately follows this length if this value is 56 /// greater than zero. 57 /// uint8_t[] InfoData Encoded bytes that represent the data for the 58 /// "InfoType". These bytes are only present if 59 /// "InfoLength" is greater than zero. 60 /// 61 /// The "InfoType" is an enumeration: 62 /// 63 /// enum InfoType { 64 /// EndOfList = 0u, 65 /// LineTableInfo = 1u, 66 /// InlineInfo = 2u 67 /// }; 68 /// 69 /// This stream of tuples is terminated by a "InfoType" whose value is 70 /// InfoType::EndOfList and a zero for "InfoLength". This signifies the end of 71 /// the optional information list. This format allows us to add new optional 72 /// information data to a FunctionInfo object over time and allows older 73 /// clients to still parse the format and skip over any data that they don't 74 /// understand or want to parse. 75 /// 76 /// So the function information encoding essientially looks like: 77 /// 78 /// struct { 79 /// uint32_t Size; 80 /// uint32_t Name; 81 /// struct { 82 /// uint32_t InfoType; 83 /// uint32_t InfoLength; 84 /// uint8_t InfoData[InfoLength]; 85 /// }[N]; 86 /// } 87 /// 88 /// Where "N" is the number of tuples. 89 struct FunctionInfo { 90 AddressRange Range; 91 uint32_t Name; ///< String table offset in the string table. 92 std::optional<LineTable> OptLineTable; 93 std::optional<InlineInfo> Inline; 94 std::optional<MergedFunctionsInfo> MergedFunctions; 95 /// If we encode a FunctionInfo during segmenting so we know its size, we can 96 /// cache that encoding here so we don't need to re-encode it when saving the 97 /// GSYM file. 98 SmallString<32> EncodingCache; 99 100 FunctionInfo(uint64_t Addr = 0, uint64_t Size = 0, uint32_t N = 0) 101 : Range(Addr, Addr + Size), Name(N) {} 102 103 /// Query if a FunctionInfo has rich debug info. 104 /// 105 /// \returns A bool that indicates if this object has something else than 106 /// range and name. When converting information from a symbol table and from 107 /// debug info, we might end up with multiple FunctionInfo objects for the 108 /// same range and we need to be able to tell which one is the better object 109 /// to use. hasRichInfoFunctionInfo110 bool hasRichInfo() const { return OptLineTable || Inline; } 111 112 /// Query if a FunctionInfo object is valid. 113 /// 114 /// Address and size can be zero and there can be no line entries for a 115 /// symbol so the only indication this entry is valid is if the name is 116 /// not zero. This can happen when extracting information from symbol 117 /// tables that do not encode symbol sizes. In that case only the 118 /// address and name will be filled in. 119 /// 120 /// \returns A boolean indicating if this FunctionInfo is valid. isValidFunctionInfo121 bool isValid() const { 122 return Name != 0; 123 } 124 125 /// Decode an object from a binary data stream. 126 /// 127 /// \param Data The binary stream to read the data from. This object must 128 /// have the data for the object starting at offset zero. The data 129 /// can contain more data than needed. 130 /// 131 /// \param BaseAddr The FunctionInfo's start address and will be used as the 132 /// base address when decoding any contained information like the line table 133 /// and the inline info. 134 /// 135 /// \returns An FunctionInfo or an error describing the issue that was 136 /// encountered during decoding. 137 static llvm::Expected<FunctionInfo> decode(DataExtractor &Data, 138 uint64_t BaseAddr); 139 140 /// Encode this object into FileWriter stream. 141 /// 142 /// \param O The binary stream to write the data to at the current file 143 /// position. 144 /// 145 /// \param NoPadding Directly write the FunctionInfo data, without any padding 146 /// By default, FunctionInfo will be 4-byte aligned by padding with 147 /// 0's at the start. This is OK since the function will return the offset of 148 /// actual data in the stream. However when writing FunctionInfo's as a 149 /// stream, the padding will break the decoding of the data - since the offset 150 /// where the FunctionInfo starts is not kept in this scenario. 151 /// 152 /// \returns An error object that indicates failure or the offset of the 153 /// function info that was successfully written into the stream. 154 llvm::Expected<uint64_t> encode(FileWriter &O, bool NoPadding = false) const; 155 156 /// Encode this function info into the internal byte cache and return the size 157 /// in bytes. 158 /// 159 /// When segmenting GSYM files we need to know how big each FunctionInfo will 160 /// encode into so we can generate segments of the right size. We don't want 161 /// to have to encode a FunctionInfo twice, so we can cache the encoded bytes 162 /// and re-use then when calling FunctionInfo::encode(...). 163 /// 164 /// \returns The size in bytes of the FunctionInfo if it were to be encoded 165 /// into a byte stream. 166 uint64_t cacheEncoding(); 167 168 /// Lookup an address within a FunctionInfo object's data stream. 169 /// 170 /// Instead of decoding an entire FunctionInfo object when doing lookups, 171 /// we can decode only the information we need from the FunctionInfo's data 172 /// for the specific address. The lookup result information is returned as 173 /// a LookupResult. 174 /// 175 /// \param Data The binary stream to read the data from. This object must 176 /// have the data for the object starting at offset zero. The data 177 /// can contain more data than needed. 178 /// 179 /// \param GR The GSYM reader that contains the string and file table that 180 /// will be used to fill in information in the returned result. 181 /// 182 /// \param FuncAddr The function start address decoded from the GsymReader. 183 /// 184 /// \param Addr The address to lookup. 185 /// 186 /// \returns An LookupResult or an error describing the issue that was 187 /// encountered during decoding. An error should only be returned if the 188 /// address is not contained in the FunctionInfo or if the data is corrupted. 189 static llvm::Expected<LookupResult> lookup(DataExtractor &Data, 190 const GsymReader &GR, 191 uint64_t FuncAddr, 192 uint64_t Addr); 193 startAddressFunctionInfo194 uint64_t startAddress() const { return Range.start(); } endAddressFunctionInfo195 uint64_t endAddress() const { return Range.end(); } sizeFunctionInfo196 uint64_t size() const { return Range.size(); } 197 clearFunctionInfo198 void clear() { 199 Range = {0, 0}; 200 Name = 0; 201 OptLineTable = std::nullopt; 202 Inline = std::nullopt; 203 } 204 }; 205 206 inline bool operator==(const FunctionInfo &LHS, const FunctionInfo &RHS) { 207 return LHS.Range == RHS.Range && LHS.Name == RHS.Name && 208 LHS.OptLineTable == RHS.OptLineTable && LHS.Inline == RHS.Inline; 209 } 210 inline bool operator!=(const FunctionInfo &LHS, const FunctionInfo &RHS) { 211 return !(LHS == RHS); 212 } 213 /// This sorting will order things consistently by address range first, but 214 /// then followed by increasing levels of debug info like inline information 215 /// and line tables. We might end up with a FunctionInfo from debug info that 216 /// will have the same range as one from the symbol table, but we want to 217 /// quickly be able to sort and use the best version when creating the final 218 /// GSYM file. This function compares the inline information as we have seen 219 /// cases where LTO can generate a wide array of differing inline information, 220 /// mostly due to messing up the address ranges for inlined functions, so the 221 /// inline information with the most entries will appeear last. If the inline 222 /// information match, either by both function infos not having any or both 223 /// being exactly the same, we will then compare line tables. Comparing line 224 /// tables allows the entry with the most line entries to appear last. This 225 /// ensures we are able to save the FunctionInfo with the most debug info into 226 /// the GSYM file. 227 inline bool operator<(const FunctionInfo &LHS, const FunctionInfo &RHS) { 228 // First sort by address range 229 if (LHS.Range != RHS.Range) 230 return LHS.Range < RHS.Range; 231 if (LHS.Inline == RHS.Inline) 232 return LHS.OptLineTable < RHS.OptLineTable; 233 return LHS.Inline < RHS.Inline; 234 } 235 236 raw_ostream &operator<<(raw_ostream &OS, const FunctionInfo &R); 237 238 } // namespace gsym 239 } // namespace llvm 240 241 #endif // LLVM_DEBUGINFO_GSYM_FUNCTIONINFO_H 242