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