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_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"; }