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                                         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_WRITE)
  94     OS << 'w';
  95   if (Flags & ELF::SHF_MERGE)
  96     OS << 'M';
  97   if (Flags & ELF::SHF_STRINGS)
  98     OS << 'S';
  99   if (Flags & ELF::SHF_TLS)
 100     OS << 'T';
 101   if (Flags & ELF::SHF_LINK_ORDER)
 102     OS << 'o';
 103   if (Flags & ELF::SHF_GROUP)
 104     OS << 'G';
 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   } else if (Arch == Triple::x86_64) {
 127     if (Flags & ELF::SHF_X86_64_LARGE)
 128       OS << 'l';
 129   }
 130
 131   OS << '"';
 132
 133   OS << ',';
 134
 135   // If comment string is '@', e.g. as on ARM - use '%' instead
 136   if (MAI.getCommentString()[0] == '@')
 137     OS << '%';
 138   else
 139     OS << '@';
 140
 141   if (Type == ELF::SHT_INIT_ARRAY)
 142     OS << "init_array";
 143   else if (Type == ELF::SHT_FINI_ARRAY)
 144     OS << "fini_array";
 145   else if (Type == ELF::SHT_PREINIT_ARRAY)
 146     OS << "preinit_array";
 147   else if (Type == ELF::SHT_NOBITS)
 148     OS << "nobits";
 149   else if (Type == ELF::SHT_NOTE)
 150     OS << "note";
 151   else if (Type == ELF::SHT_PROGBITS)
 152     OS << "progbits";
 153   else if (Type == ELF::SHT_X86_64_UNWIND)
 154     OS << "unwind";
 155   else if (Type == ELF::SHT_MIPS_DWARF)
 156     // Print hex value of the flag while we do not have
 157     // any standard symbolic representation of the flag.
 158     OS << "0x7000001e";
 159   else if (Type == ELF::SHT_LLVM_ODRTAB)
 160     OS << "llvm_odrtab";
 161   else if (Type == ELF::SHT_LLVM_LINKER_OPTIONS)
 162     OS << "llvm_linker_options";
 163   else if (Type == ELF::SHT_LLVM_CALL_GRAPH_PROFILE)
 164     OS << "llvm_call_graph_profile";
 165   else if (Type == ELF::SHT_LLVM_DEPENDENT_LIBRARIES)
 166     OS << "llvm_dependent_libraries";
 167   else if (Type == ELF::SHT_LLVM_SYMPART)
 168     OS << "llvm_sympart";
 169   else if (Type == ELF::SHT_LLVM_BB_ADDR_MAP)
 170     OS << "llvm_bb_addr_map";
 171   else if (Type == ELF::SHT_LLVM_BB_ADDR_MAP_V0)
 172     OS << "llvm_bb_addr_map_v0";
 173   else if (Type == ELF::SHT_LLVM_OFFLOADING)
 174     OS << "llvm_offloading";
 175   else if (Type == ELF::SHT_LLVM_LTO)
 176     OS << "llvm_lto";
 177   else
 178     report_fatal_error("unsupported type 0x" + Twine::utohexstr(Type) +
 179                        " for section " + getName());
 180
 181   if (EntrySize) {
 182     assert(Flags & ELF::SHF_MERGE);
 183     OS << "," << EntrySize;
 184   }
 185
 186   if (Flags & ELF::SHF_LINK_ORDER) {
 187     OS << ",";
 188     if (LinkedToSym)
 189       printName(OS, LinkedToSym->getName());
 190     else
 191       OS << '0';
 192   }
 193
 194   if (Flags & ELF::SHF_GROUP) {
 195     OS << ",";
 196     printName(OS, Group.getPointer()->getName());
 197     if (isComdat())
 198       OS << ",comdat";
 199   }
 200
 201   if (isUnique())
 202     OS << ",unique," << UniqueID;
 203
 204   OS << '\n';
 205
 206   if (Subsection) {
 207     OS << "\t.subsection\t";
 208     Subsection->print(OS, &MAI);
 209     OS << '\n';
 210   }
 211 }
 212
 213 bool MCSectionELF::useCodeAlign() const {
 214   return getFlags() & ELF::SHF_EXECINSTR;
 215 }
 216
 217 bool MCSectionELF::isVirtualSection() const {
 218   return getType() == ELF::SHT_NOBITS;
 219 }
 220
 221 StringRef MCSectionELF::getVirtualSectionKind() const { return "SHT_NOBITS"; }