llvm/lib/MC/MCSectionELF.cpp

   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/BinaryFormat/ELF.h"
  11 #include "llvm/MC/MCAsmInfo.h"
  12 #include "llvm/MC/MCExpr.h"
  13 #include "llvm/Support/ErrorHandling.h"
  14 #include "llvm/Support/raw_ostream.h"
  15 #include "llvm/TargetParser/Triple.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                                         uint32_t Subsection) const {
  56   if (shouldOmitSectionDirective(getName(), MAI)) {
  57     OS << '\t' << getName();
  58     if (Subsection)
  59       OS << '\t' << Subsection;
  60     OS << '\n';
  61     return;
  62   }
  63
  64   OS << "\t.section\t";
  65   printName(OS, getName());
  66
  67   // Handle the weird solaris syntax if desired.
  68   if (MAI.usesSunStyleELFSectionSwitchSyntax() &&
  69       !(Flags & ELF::SHF_MERGE)) {
  70     if (Flags & ELF::SHF_ALLOC)
  71       OS << ",#alloc";
  72     if (Flags & ELF::SHF_EXECINSTR)
  73       OS << ",#execinstr";
  74     if (Flags & ELF::SHF_WRITE)
  75       OS << ",#write";
  76     if (Flags & ELF::SHF_EXCLUDE)
  77       OS << ",#exclude";
  78     if (Flags & ELF::SHF_TLS)
  79       OS << ",#tls";
  80     OS << '\n';
  81     return;
  82   }
  83
  84   OS << ",\"";
  85   if (Flags & ELF::SHF_ALLOC)
  86     OS << 'a';
  87   if (Flags & ELF::SHF_EXCLUDE)
  88     OS << 'e';
  89   if (Flags & ELF::SHF_EXECINSTR)
  90     OS << 'x';
  91   if (Flags & ELF::SHF_WRITE)
  92     OS << 'w';
  93   if (Flags & ELF::SHF_MERGE)
  94     OS << 'M';
  95   if (Flags & ELF::SHF_STRINGS)
  96     OS << 'S';
  97   if (Flags & ELF::SHF_TLS)
  98     OS << 'T';
  99   if (Flags & ELF::SHF_LINK_ORDER)
 100     OS << 'o';
 101   if (Flags & ELF::SHF_GROUP)
 102     OS << 'G';
 103   if (Flags & ELF::SHF_GNU_RETAIN)
 104     OS << 'R';
 105
 106   // If there are os-specific flags, print them.
 107   if (T.isOSSolaris())
 108     if (Flags & ELF::SHF_SUNW_NODISCARD)
 109       OS << 'R';
 110
 111   // If there are target-specific flags, print them.
 112   Triple::ArchType Arch = T.getArch();
 113   if (Arch == Triple::xcore) {
 114     if (Flags & ELF::XCORE_SHF_CP_SECTION)
 115       OS << 'c';
 116     if (Flags & ELF::XCORE_SHF_DP_SECTION)
 117       OS << 'd';
 118   } else if (T.isARM() || T.isThumb()) {
 119     if (Flags & ELF::SHF_ARM_PURECODE)
 120       OS << 'y';
 121   } else if (Arch == Triple::hexagon) {
 122     if (Flags & ELF::SHF_HEX_GPREL)
 123       OS << 's';
 124   } else if (Arch == Triple::x86_64) {
 125     if (Flags & ELF::SHF_X86_64_LARGE)
 126       OS << 'l';
 127   }
 128
 129   OS << '"';
 130
 131   OS << ',';
 132
 133   // If comment string is '@', e.g. as on ARM - use '%' instead
 134   if (MAI.getCommentString()[0] == '@')
 135     OS << '%';
 136   else
 137     OS << '@';
 138
 139   if (Type == ELF::SHT_INIT_ARRAY)
 140     OS << "init_array";
 141   else if (Type == ELF::SHT_FINI_ARRAY)
 142     OS << "fini_array";
 143   else if (Type == ELF::SHT_PREINIT_ARRAY)
 144     OS << "preinit_array";
 145   else if (Type == ELF::SHT_NOBITS)
 146     OS << "nobits";
 147   else if (Type == ELF::SHT_NOTE)
 148     OS << "note";
 149   else if (Type == ELF::SHT_PROGBITS)
 150     OS << "progbits";
 151   else if (Type == ELF::SHT_X86_64_UNWIND)
 152     OS << "unwind";
 153   else if (Type == ELF::SHT_MIPS_DWARF)
 154     // Print hex value of the flag while we do not have
 155     // any standard symbolic representation of the flag.
 156     OS << "0x7000001e";
 157   else if (Type == ELF::SHT_LLVM_ODRTAB)
 158     OS << "llvm_odrtab";
 159   else if (Type == ELF::SHT_LLVM_LINKER_OPTIONS)
 160     OS << "llvm_linker_options";
 161   else if (Type == ELF::SHT_LLVM_CALL_GRAPH_PROFILE)
 162     OS << "llvm_call_graph_profile";
 163   else if (Type == ELF::SHT_LLVM_DEPENDENT_LIBRARIES)
 164     OS << "llvm_dependent_libraries";
 165   else if (Type == ELF::SHT_LLVM_SYMPART)
 166     OS << "llvm_sympart";
 167   else if (Type == ELF::SHT_LLVM_BB_ADDR_MAP)
 168     OS << "llvm_bb_addr_map";
 169   else if (Type == ELF::SHT_LLVM_BB_ADDR_MAP_V0)
 170     OS << "llvm_bb_addr_map_v0";
 171   else if (Type == ELF::SHT_LLVM_OFFLOADING)
 172     OS << "llvm_offloading";
 173   else if (Type == ELF::SHT_LLVM_LTO)
 174     OS << "llvm_lto";
 175   else
 176     OS << "0x" << Twine::utohexstr(Type);
 177
 178   if (EntrySize) {
 179     assert(Flags & ELF::SHF_MERGE);
 180     OS << "," << EntrySize;
 181   }
 182
 183   if (Flags & ELF::SHF_LINK_ORDER) {
 184     OS << ",";
 185     if (LinkedToSym)
 186       printName(OS, LinkedToSym->getName());
 187     else
 188       OS << '0';
 189   }
 190
 191   if (Flags & ELF::SHF_GROUP) {
 192     OS << ",";
 193     printName(OS, Group.getPointer()->getName());
 194     if (isComdat())
 195       OS << ",comdat";
 196   }
 197
 198   if (isUnique())
 199     OS << ",unique," << UniqueID;
 200
 201   OS << '\n';
 202
 203   if (Subsection) {
 204     OS << "\t.subsection\t" << Subsection;
 205     OS << '\n';
 206   }
 207 }
 208
 209 bool MCSectionELF::useCodeAlign() const {
 210   return getFlags() & ELF::SHF_EXECINSTR;
 211 }
 212
 213 StringRef MCSectionELF::getVirtualSectionKind() const { return "SHT_NOBITS"; }