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 target-specific flags, print them. 109 Triple::ArchType Arch = T.getArch(); 110 if (Arch == Triple::xcore) { 111 if (Flags & ELF::XCORE_SHF_CP_SECTION) 112 OS << 'c'; 113 if (Flags & ELF::XCORE_SHF_DP_SECTION) 114 OS << 'd'; 115 } else if (T.isARM() || T.isThumb()) { 116 if (Flags & ELF::SHF_ARM_PURECODE) 117 OS << 'y'; 118 } else if (Arch == Triple::hexagon) { 119 if (Flags & ELF::SHF_HEX_GPREL) 120 OS << 's'; 121 } 122 123 OS << '"'; 124 125 OS << ','; 126 127 // If comment string is '@', e.g. as on ARM - use '%' instead 128 if (MAI.getCommentString()[0] == '@') 129 OS << '%'; 130 else 131 OS << '@'; 132 133 if (Type == ELF::SHT_INIT_ARRAY) 134 OS << "init_array"; 135 else if (Type == ELF::SHT_FINI_ARRAY) 136 OS << "fini_array"; 137 else if (Type == ELF::SHT_PREINIT_ARRAY) 138 OS << "preinit_array"; 139 else if (Type == ELF::SHT_NOBITS) 140 OS << "nobits"; 141 else if (Type == ELF::SHT_NOTE) 142 OS << "note"; 143 else if (Type == ELF::SHT_PROGBITS) 144 OS << "progbits"; 145 else if (Type == ELF::SHT_X86_64_UNWIND) 146 OS << "unwind"; 147 else if (Type == ELF::SHT_MIPS_DWARF) 148 // Print hex value of the flag while we do not have 149 // any standard symbolic representation of the flag. 150 OS << "0x7000001e"; 151 else if (Type == ELF::SHT_LLVM_ODRTAB) 152 OS << "llvm_odrtab"; 153 else if (Type == ELF::SHT_LLVM_LINKER_OPTIONS) 154 OS << "llvm_linker_options"; 155 else if (Type == ELF::SHT_LLVM_CALL_GRAPH_PROFILE) 156 OS << "llvm_call_graph_profile"; 157 else if (Type == ELF::SHT_LLVM_DEPENDENT_LIBRARIES) 158 OS << "llvm_dependent_libraries"; 159 else if (Type == ELF::SHT_LLVM_SYMPART) 160 OS << "llvm_sympart"; 161 else if (Type == ELF::SHT_LLVM_BB_ADDR_MAP) 162 OS << "llvm_bb_addr_map"; 163 else 164 report_fatal_error("unsupported type 0x" + Twine::utohexstr(Type) + 165 " for section " + getName()); 166 167 if (EntrySize) { 168 assert(Flags & ELF::SHF_MERGE); 169 OS << "," << EntrySize; 170 } 171 172 if (Flags & ELF::SHF_GROUP) { 173 OS << ","; 174 printName(OS, Group.getPointer()->getName()); 175 if (isComdat()) 176 OS << ",comdat"; 177 } 178 179 if (Flags & ELF::SHF_LINK_ORDER) { 180 OS << ","; 181 if (LinkedToSym) 182 printName(OS, LinkedToSym->getName()); 183 else 184 OS << '0'; 185 } 186 187 if (isUnique()) 188 OS << ",unique," << UniqueID; 189 190 OS << '\n'; 191 192 if (Subsection) { 193 OS << "\t.subsection\t"; 194 Subsection->print(OS, &MAI); 195 OS << '\n'; 196 } 197 } 198 199 bool MCSectionELF::UseCodeAlign() const { 200 return getFlags() & ELF::SHF_EXECINSTR; 201 } 202 203 bool MCSectionELF::isVirtualSection() const { 204 return getType() == ELF::SHT_NOBITS; 205 } 206 207 StringRef MCSectionELF::getVirtualSectionKind() const { return "SHT_NOBITS"; } 208