lib/MC/MCSectionMachO.cpp

   1 //===- lib/MC/MCSectionMachO.cpp - MachO Code Section Representation ------===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9
  10 #include "llvm/MC/MCSectionMachO.h"
  11 #include "llvm/MC/MCContext.h"
  12 #include "llvm/Support/raw_ostream.h"
  13 using namespace llvm;
  14
  15 /// SectionTypeDescriptors - These are strings that describe the various section
  16 /// types.  This *must* be kept in order with and stay synchronized with the
  17 /// section type list.
  18 static const struct {
  19   const char *AssemblerName, *EnumName;
  20 } SectionTypeDescriptors[MCSectionMachO::LAST_KNOWN_SECTION_TYPE+1] = {
  21   { "regular",                  "S_REGULAR" },                    // 0x00
  22   { 0,                          "S_ZEROFILL" },                   // 0x01
  23   { "cstring_literals",         "S_CSTRING_LITERALS" },           // 0x02
  24   { "4byte_literals",           "S_4BYTE_LITERALS" },             // 0x03
  25   { "8byte_literals",           "S_8BYTE_LITERALS" },             // 0x04
  26   { "literal_pointers",         "S_LITERAL_POINTERS" },           // 0x05
  27   { "non_lazy_symbol_pointers", "S_NON_LAZY_SYMBOL_POINTERS" },   // 0x06
  28   { "lazy_symbol_pointers",     "S_LAZY_SYMBOL_POINTERS" },       // 0x07
  29   { "symbol_stubs",             "S_SYMBOL_STUBS" },               // 0x08
  30   { "mod_init_funcs",           "S_MOD_INIT_FUNC_POINTERS" },     // 0x09
  31   { "mod_term_funcs",           "S_MOD_TERM_FUNC_POINTERS" },     // 0x0A
  32   { "coalesced",                "S_COALESCED" },                  // 0x0B
  33   { 0, /*FIXME??*/              "S_GB_ZEROFILL" },                // 0x0C
  34   { "interposing",              "S_INTERPOSING" },                // 0x0D
  35   { "16byte_literals",          "S_16BYTE_LITERALS" },            // 0x0E
  36   { 0, /*FIXME??*/              "S_DTRACE_DOF" },                 // 0x0F
  37   { 0, /*FIXME??*/              "S_LAZY_DYLIB_SYMBOL_POINTERS" }  // 0x10
  38 };
  39
  40
  41 /// SectionAttrDescriptors - This is an array of descriptors for section
  42 /// attributes.  Unlike the SectionTypeDescriptors, this is not directly indexed
  43 /// by attribute, instead it is searched.  The last entry has a zero AttrFlag
  44 /// value.
  45 static const struct {
  46   unsigned AttrFlag;
  47   const char *AssemblerName, *EnumName;
  48 } SectionAttrDescriptors[] = {
  49 #define ENTRY(ASMNAME, ENUM) \
  50   { MCSectionMachO::ENUM, ASMNAME, #ENUM },
  51 ENTRY("pure_instructions",   S_ATTR_PURE_INSTRUCTIONS)
  52 ENTRY("no_toc",              S_ATTR_NO_TOC)
  53 ENTRY("strip_static_syms",   S_ATTR_STRIP_STATIC_SYMS)
  54 ENTRY("no_dead_strip",       S_ATTR_NO_DEAD_STRIP)
  55 ENTRY("live_support",        S_ATTR_LIVE_SUPPORT)
  56 ENTRY("self_modifying_code", S_ATTR_SELF_MODIFYING_CODE)
  57 ENTRY("debug",               S_ATTR_DEBUG)
  58 ENTRY(0 /*FIXME*/,           S_ATTR_SOME_INSTRUCTIONS)
  59 ENTRY(0 /*FIXME*/,           S_ATTR_EXT_RELOC)
  60 ENTRY(0 /*FIXME*/,           S_ATTR_LOC_RELOC)
  61 #undef ENTRY
  62   { 0, "none", 0 }
  63 };
  64
  65
  66 MCSectionMachO *MCSectionMachO::
  67 Create(const StringRef &Segment, const StringRef &Section,
  68        unsigned TypeAndAttributes, unsigned Reserved2,
  69        SectionKind K, MCContext &Ctx) {
  70   // S_SYMBOL_STUBS must be set for Reserved2 to be non-zero.
  71   return new (Ctx) MCSectionMachO(Segment, Section, TypeAndAttributes,
  72                                   Reserved2, K);
  73 }
  74
  75 void MCSectionMachO::PrintSwitchToSection(const MCAsmInfo &MAI,
  76                                           raw_ostream &OS) const {
  77   OS << "\t.section\t" << getSegmentName() << ',' << getSectionName();
  78
  79   // Get the section type and attributes.
  80   unsigned TAA = getTypeAndAttributes();
  81   if (TAA == 0) {
  82     OS << '\n';
  83     return;
  84   }
  85
  86   OS << ',';
  87
  88   unsigned SectionType = TAA & MCSectionMachO::SECTION_TYPE;
  89   assert(SectionType <= MCSectionMachO::LAST_KNOWN_SECTION_TYPE &&
  90          "Invalid SectionType specified!");
  91
  92   if (SectionTypeDescriptors[SectionType].AssemblerName)
  93     OS << SectionTypeDescriptors[SectionType].AssemblerName;
  94   else
  95     OS << "<<" << SectionTypeDescriptors[SectionType].EnumName << ">>";
  96
  97   // If we don't have any attributes, we're done.
  98   unsigned SectionAttrs = TAA & MCSectionMachO::SECTION_ATTRIBUTES;
  99   if (SectionAttrs == 0) {
 100     // If we have a S_SYMBOL_STUBS size specified, print it along with 'none' as
 101     // the attribute specifier.
 102     if (Reserved2 != 0)
 103       OS << ",none," << Reserved2;
 104     OS << '\n';
 105     return;
 106   }
 107
 108   // Check each attribute to see if we have it.
 109   char Separator = ',';
 110   for (unsigned i = 0; SectionAttrDescriptors[i].AttrFlag; ++i) {
 111     // Check to see if we have this attribute.
 112     if ((SectionAttrDescriptors[i].AttrFlag & SectionAttrs) == 0)
 113       continue;
 114
 115     // Yep, clear it and print it.
 116     SectionAttrs &= ~SectionAttrDescriptors[i].AttrFlag;
 117
 118     OS << Separator;
 119     if (SectionAttrDescriptors[i].AssemblerName)
 120       OS << SectionAttrDescriptors[i].AssemblerName;
 121     else
 122       OS << "<<" << SectionAttrDescriptors[i].EnumName << ">>";
 123     Separator = '+';
 124   }
 125
 126   assert(SectionAttrs == 0 && "Unknown section attributes!");
 127
 128   // If we have a S_SYMBOL_STUBS size specified, print it.
 129   if (Reserved2 != 0)
 130     OS << ',' << Reserved2;
 131   OS << '\n';
 132 }
 133
 134 /// StripSpaces - This removes leading and trailing spaces from the StringRef.
 135 static void StripSpaces(StringRef &Str) {
 136   while (!Str.empty() && isspace(Str[0]))
 137     Str = Str.substr(1);
 138   while (!Str.empty() && isspace(Str.back()))
 139     Str = Str.substr(0, Str.size()-1);
 140 }
 141
 142 /// ParseSectionSpecifier - Parse the section specifier indicated by "Spec".
 143 /// This is a string that can appear after a .section directive in a mach-o
 144 /// flavored .s file.  If successful, this fills in the specified Out
 145 /// parameters and returns an empty string.  When an invalid section
 146 /// specifier is present, this returns a string indicating the problem.
 147 std::string MCSectionMachO::ParseSectionSpecifier(StringRef Spec,        // In.
 148                                                   StringRef &Segment,    // Out.
 149                                                   StringRef &Section,    // Out.
 150                                                   unsigned  &TAA,        // Out.
 151                                                   unsigned  &StubSize) { // Out.
 152   // Find the first comma.
 153   std::pair<StringRef, StringRef> Comma = Spec.split(',');
 154
 155   // If there is no comma, we fail.
 156   if (Comma.second.empty())
 157     return "mach-o section specifier requires a segment and section "
 158            "separated by a comma";
 159
 160   // Capture segment, remove leading and trailing whitespace.
 161   Segment = Comma.first;
 162   StripSpaces(Segment);
 163
 164   // Verify that the segment is present and not too long.
 165   if (Segment.empty() || Segment.size() > 16)
 166     return "mach-o section specifier requires a segment whose length is "
 167            "between 1 and 16 characters";
 168
 169   // Split the section name off from any attributes if present.
 170   Comma = Comma.second.split(',');
 171
 172   // Capture section, remove leading and trailing whitespace.
 173   Section = Comma.first;
 174   StripSpaces(Section);
 175
 176   // Verify that the section is present and not too long.
 177   if (Section.empty() || Section.size() > 16)
 178     return "mach-o section specifier requires a section whose length is "
 179            "between 1 and 16 characters";
 180
 181   // If there is no comma after the section, we're done.
 182   TAA = 0;
 183   StubSize = 0;
 184   if (Comma.second.empty())
 185     return "";
 186
 187   // Otherwise, we need to parse the section type and attributes.
 188   Comma = Comma.second.split(',');
 189
 190   // Get the section type.
 191   StringRef SectionType = Comma.first;
 192   StripSpaces(SectionType);
 193
 194   // Figure out which section type it is.
 195   unsigned TypeID;
 196   for (TypeID = 0; TypeID !=MCSectionMachO::LAST_KNOWN_SECTION_TYPE+1; ++TypeID)
 197     if (SectionTypeDescriptors[TypeID].AssemblerName &&
 198         SectionType == SectionTypeDescriptors[TypeID].AssemblerName)
 199       break;
 200
 201   // If we didn't find the section type, reject it.
 202   if (TypeID > MCSectionMachO::LAST_KNOWN_SECTION_TYPE)
 203     return "mach-o section specifier uses an unknown section type";
 204
 205   // Remember the TypeID.
 206   TAA = TypeID;
 207
 208   // If we have no comma after the section type, there are no attributes.
 209   if (Comma.second.empty()) {
 210     // S_SYMBOL_STUBS always require a symbol stub size specifier.
 211     if (TAA == MCSectionMachO::S_SYMBOL_STUBS)
 212       return "mach-o section specifier of type 'symbol_stubs' requires a size "
 213              "specifier";
 214     return "";
 215   }
 216
 217   // Otherwise, we do have some attributes.  Split off the size specifier if
 218   // present.
 219   Comma = Comma.second.split(',');
 220   StringRef Attrs = Comma.first;
 221
 222   // The attribute list is a '+' separated list of attributes.
 223   std::pair<StringRef, StringRef> Plus = Attrs.split('+');
 224
 225   while (1) {
 226     StringRef Attr = Plus.first;
 227     StripSpaces(Attr);
 228
 229     // Look up the attribute.
 230     for (unsigned i = 0; ; ++i) {
 231       if (SectionAttrDescriptors[i].AttrFlag == 0)
 232         return "mach-o section specifier has invalid attribute";
 233
 234       if (SectionAttrDescriptors[i].AssemblerName &&
 235           Attr == SectionAttrDescriptors[i].AssemblerName) {
 236         TAA |= SectionAttrDescriptors[i].AttrFlag;
 237         break;
 238       }
 239     }
 240
 241     if (Plus.second.empty()) break;
 242     Plus = Plus.second.split('+');
 243   };
 244
 245   // Okay, we've parsed the section attributes, see if we have a stub size spec.
 246   if (Comma.second.empty()) {
 247     // S_SYMBOL_STUBS always require a symbol stub size specifier.
 248     if (TAA == MCSectionMachO::S_SYMBOL_STUBS)
 249       return "mach-o section specifier of type 'symbol_stubs' requires a size "
 250       "specifier";
 251     return "";
 252   }
 253
 254   // If we have a stub size spec, we must have a sectiontype of S_SYMBOL_STUBS.
 255   if ((TAA & MCSectionMachO::SECTION_TYPE) != MCSectionMachO::S_SYMBOL_STUBS)
 256     return "mach-o section specifier cannot have a stub size specified because "
 257            "it does not have type 'symbol_stubs'";
 258
 259   // Okay, if we do, it must be a number.
 260   StringRef StubSizeStr = Comma.second;
 261   StripSpaces(StubSizeStr);
 262
 263   // Convert the a null terminated buffer for strtoul.
 264   char TmpBuffer[32];
 265   if (StubSizeStr.size() >= 32)
 266     return"mach-o section specifier has a stub size specifier that is too long";
 267
 268   memcpy(TmpBuffer, StubSizeStr.data(), StubSizeStr.size());
 269   TmpBuffer[StubSizeStr.size()] = 0;
 270
 271   char *EndPtr;
 272   StubSize = strtoul(TmpBuffer, &EndPtr, 0);
 273
 274   if (EndPtr[0] != 0)
 275     return "mach-o section specifier has a malformed stub size";
 276
 277   return "";
 278 }
 279