1 //===- lib/MC/MCSectionELF.cpp - ELF Code Section Representation ----------===// 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 #include "llvm/MC/MCSectionELF.h" 10 #include "llvm/ADT/Triple.h" 11 #include "llvm/BinaryFormat/ELF.h" 12 #include "llvm/MC/MCAsmInfo.h" 13 #include "llvm/MC/MCExpr.h" 14 #include "llvm/Support/ErrorHandling.h" 15 #include "llvm/Support/raw_ostream.h" 16 #include <cassert> 17 18 using namespace llvm; 19 20 // Decides whether a '.section' directive 21 // should be printed before the section name. 22 bool MCSectionELF::shouldOmitSectionDirective(StringRef Name, 23 const MCAsmInfo &MAI) const { 24 if (isUnique()) 25 return false; 26 27 return MAI.shouldOmitSectionDirective(Name); 28 } 29 30 static void printName(raw_ostream &OS, StringRef Name) { 31 if (Name.find_first_not_of("0123456789_." 32 "abcdefghijklmnopqrstuvwxyz" 33 "ABCDEFGHIJKLMNOPQRSTUVWXYZ") == Name.npos) { 34 OS << Name; 35 return; 36 } 37 OS << '"'; 38 for (const char *B = Name.begin(), *E = Name.end(); B < E; ++B) { 39 if (*B == '"') // Unquoted " 40 OS << "\\\""; 41 else if (*B != '\\') // Neither " or backslash 42 OS << *B; 43 else if (B + 1 == E) // Trailing backslash 44 OS << "\\\\"; 45 else { 46 OS << B[0] << B[1]; // Quoted character 47 ++B; 48 } 49 } 50 OS << '"'; 51 } 52 53 void MCSectionELF::printSwitchToSection(const MCAsmInfo &MAI, const Triple &T, 54 raw_ostream &OS, 55 const MCExpr *Subsection) const { 56 if (shouldOmitSectionDirective(getName(), MAI)) { 57 OS << '\t' << getName(); 58 if (Subsection) { 59 OS << '\t'; 60 Subsection->print(OS, &MAI); 61 } 62 OS << '\n'; 63 return; 64 } 65 66 OS << "\t.section\t"; 67 printName(OS, getName()); 68 69 // Handle the weird solaris syntax if desired. 70 if (MAI.usesSunStyleELFSectionSwitchSyntax() && 71 !(Flags & ELF::SHF_MERGE)) { 72 if (Flags & ELF::SHF_ALLOC) 73 OS << ",#alloc"; 74 if (Flags & ELF::SHF_EXECINSTR) 75 OS << ",#execinstr"; 76 if (Flags & ELF::SHF_WRITE) 77 OS << ",#write"; 78 if (Flags & ELF::SHF_EXCLUDE) 79 OS << ",#exclude"; 80 if (Flags & ELF::SHF_TLS) 81 OS << ",#tls"; 82 OS << '\n'; 83 return; 84 } 85 86 OS << ",\""; 87 if (Flags & ELF::SHF_ALLOC) 88 OS << 'a'; 89 if (Flags & ELF::SHF_EXCLUDE) 90 OS << 'e'; 91 if (Flags & ELF::SHF_EXECINSTR) 92 OS << 'x'; 93 if (Flags & ELF::SHF_GROUP) 94 OS << 'G'; 95 if (Flags & ELF::SHF_WRITE) 96 OS << 'w'; 97 if (Flags & ELF::SHF_MERGE) 98 OS << 'M'; 99 if (Flags & ELF::SHF_STRINGS) 100 OS << 'S'; 101 if (Flags & ELF::SHF_TLS) 102 OS << 'T'; 103 if (Flags & ELF::SHF_LINK_ORDER) 104 OS << 'o'; 105 if (Flags & ELF::SHF_GNU_RETAIN) 106 OS << 'R'; 107 108 // If there are os-specific flags, print them. 109 if (T.isOSSolaris()) 110 if (Flags & ELF::SHF_SUNW_NODISCARD) 111 OS << 'R'; 112 113 // If there are target-specific flags, print them. 114 Triple::ArchType Arch = T.getArch(); 115 if (Arch == Triple::xcore) { 116 if (Flags & ELF::XCORE_SHF_CP_SECTION) 117 OS << 'c'; 118 if (Flags & ELF::XCORE_SHF_DP_SECTION) 119 OS << 'd'; 120 } else if (T.isARM() || T.isThumb()) { 121 if (Flags & ELF::SHF_ARM_PURECODE) 122 OS << 'y'; 123 } else if (Arch == Triple::hexagon) { 124 if (Flags & ELF::SHF_HEX_GPREL) 125 OS << 's'; 126 } 127 128 OS << '"'; 129 130 OS << ','; 131 132 // If comment string is '@', e.g. as on ARM - use '%' instead 133 if (MAI.getCommentString()[0] == '@') 134 OS << '%'; 135 else 136 OS << '@'; 137 138 if (Type == ELF::SHT_INIT_ARRAY) 139 OS << "init_array"; 140 else if (Type == ELF::SHT_FINI_ARRAY) 141 OS << "fini_array"; 142 else if (Type == ELF::SHT_PREINIT_ARRAY) 143 OS << "preinit_array"; 144 else if (Type == ELF::SHT_NOBITS) 145 OS << "nobits"; 146 else if (Type == ELF::SHT_NOTE) 147 OS << "note"; 148 else if (Type == ELF::SHT_PROGBITS) 149 OS << "progbits"; 150 else if (Type == ELF::SHT_X86_64_UNWIND) 151 OS << "unwind"; 152 else if (Type == ELF::SHT_MIPS_DWARF) 153 // Print hex value of the flag while we do not have 154 // any standard symbolic representation of the flag. 155 OS << "0x7000001e"; 156 else if (Type == ELF::SHT_LLVM_ODRTAB) 157 OS << "llvm_odrtab"; 158 else if (Type == ELF::SHT_LLVM_LINKER_OPTIONS) 159 OS << "llvm_linker_options"; 160 else if (Type == ELF::SHT_LLVM_CALL_GRAPH_PROFILE) 161 OS << "llvm_call_graph_profile"; 162 else if (Type == ELF::SHT_LLVM_DEPENDENT_LIBRARIES) 163 OS << "llvm_dependent_libraries"; 164 else if (Type == ELF::SHT_LLVM_SYMPART) 165 OS << "llvm_sympart"; 166 else if (Type == ELF::SHT_LLVM_BB_ADDR_MAP) 167 OS << "llvm_bb_addr_map"; 168 else if (Type == ELF::SHT_LLVM_BB_ADDR_MAP_V0) 169 OS << "llvm_bb_addr_map_v0"; 170 else if (Type == ELF::SHT_LLVM_OFFLOADING) 171 OS << "llvm_offloading"; 172 else 173 report_fatal_error("unsupported type 0x" + Twine::utohexstr(Type) + 174 " for section " + getName()); 175 176 if (EntrySize) { 177 assert(Flags & ELF::SHF_MERGE); 178 OS << "," << EntrySize; 179 } 180 181 if (Flags & ELF::SHF_GROUP) { 182 OS << ","; 183 printName(OS, Group.getPointer()->getName()); 184 if (isComdat()) 185 OS << ",comdat"; 186 } 187 188 if (Flags & ELF::SHF_LINK_ORDER) { 189 OS << ","; 190 if (LinkedToSym) 191 printName(OS, LinkedToSym->getName()); 192 else 193 OS << '0'; 194 } 195 196 if (isUnique()) 197 OS << ",unique," << UniqueID; 198 199 OS << '\n'; 200 201 if (Subsection) { 202 OS << "\t.subsection\t"; 203 Subsection->print(OS, &MAI); 204 OS << '\n'; 205 } 206 } 207 208 bool MCSectionELF::useCodeAlign() const { 209 return getFlags() & ELF::SHF_EXECINSTR; 210 } 211 212 bool MCSectionELF::isVirtualSection() const { 213 return getType() == ELF::SHT_NOBITS; 214 } 215 216 StringRef MCSectionELF::getVirtualSectionKind() const { return "SHT_NOBITS"; } 217