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   { "thread_local_regular",     "S_THREAD_LOCAL_REGULAR" },       // 0x11
  39   { "thread_local_zerofill",    "S_THREAD_LOCAL_ZEROFILL" },      // 0x12
  40   { "thread_local_variables",   "S_THREAD_LOCAL_VARIABLES" },     // 0x13
  41   { "thread_local_variable_pointers",
  42     "S_THREAD_LOCAL_VARIABLE_POINTERS" },                         // 0x14
  43   { "thread_local_init_function_pointers",
  44     "S_THREAD_LOCAL_INIT_FUNCTION_POINTERS"},                     // 0x15
  45 };
  46
  47
  48 /// SectionAttrDescriptors - This is an array of descriptors for section
  49 /// attributes.  Unlike the SectionTypeDescriptors, this is not directly indexed
  50 /// by attribute, instead it is searched.  The last entry has an AttrFlagEnd
  51 /// AttrFlag value.
  52 static const struct {
  53   unsigned AttrFlag;
  54   const char *AssemblerName, *EnumName;
  55 } SectionAttrDescriptors[] = {
  56 #define ENTRY(ASMNAME, ENUM) \
  57   { MCSectionMachO::ENUM, ASMNAME, #ENUM },
  58 ENTRY("pure_instructions",   S_ATTR_PURE_INSTRUCTIONS)
  59 ENTRY("no_toc",              S_ATTR_NO_TOC)
  60 ENTRY("strip_static_syms",   S_ATTR_STRIP_STATIC_SYMS)
  61 ENTRY("no_dead_strip",       S_ATTR_NO_DEAD_STRIP)
  62 ENTRY("live_support",        S_ATTR_LIVE_SUPPORT)
  63 ENTRY("self_modifying_code", S_ATTR_SELF_MODIFYING_CODE)
  64 ENTRY("debug",               S_ATTR_DEBUG)
  65 ENTRY(0 /*FIXME*/,           S_ATTR_SOME_INSTRUCTIONS)
  66 ENTRY(0 /*FIXME*/,           S_ATTR_EXT_RELOC)
  67 ENTRY(0 /*FIXME*/,           S_ATTR_LOC_RELOC)
  68 #undef ENTRY
  69   { 0, "none", 0 }, // used if section has no attributes but has a stub size
  70 #define AttrFlagEnd 0xffffffff // non legal value, multiple attribute bits set
  71   { AttrFlagEnd, 0, 0 }
  72 };
  73
  74 MCSectionMachO::MCSectionMachO(StringRef Segment, StringRef Section,
  75                                unsigned TAA, unsigned reserved2, SectionKind K)
  76   : MCSection(SV_MachO, K), TypeAndAttributes(TAA), Reserved2(reserved2) {
  77   assert(Segment.size() <= 16 && Section.size() <= 16 &&
  78          "Segment or section string too long");
  79   for (unsigned i = 0; i != 16; ++i) {
  80     if (i < Segment.size())
  81       SegmentName[i] = Segment[i];
  82     else
  83       SegmentName[i] = 0;
  84
  85     if (i < Section.size())
  86       SectionName[i] = Section[i];
  87     else
  88       SectionName[i] = 0;
  89   }
  90 }
  91
  92 void MCSectionMachO::PrintSwitchToSection(const MCAsmInfo &MAI,
  93                                           raw_ostream &OS) const {
  94   OS << "\t.section\t" << getSegmentName() << ',' << getSectionName();
  95
  96   // Get the section type and attributes.
  97   unsigned TAA = getTypeAndAttributes();
  98   if (TAA == 0) {
  99     OS << '\n';
 100     return;
 101   }
 102
 103   OS << ',';
 104
 105   unsigned SectionType = TAA & MCSectionMachO::SECTION_TYPE;
 106   assert(SectionType <= MCSectionMachO::LAST_KNOWN_SECTION_TYPE &&
 107          "Invalid SectionType specified!");
 108
 109   if (SectionTypeDescriptors[SectionType].AssemblerName)
 110     OS << SectionTypeDescriptors[SectionType].AssemblerName;
 111   else
 112     OS << "<<" << SectionTypeDescriptors[SectionType].EnumName << ">>";
 113
 114   // If we don't have any attributes, we're done.
 115   unsigned SectionAttrs = TAA & MCSectionMachO::SECTION_ATTRIBUTES;
 116   if (SectionAttrs == 0) {
 117     // If we have a S_SYMBOL_STUBS size specified, print it along with 'none' as
 118     // the attribute specifier.
 119     if (Reserved2 != 0)
 120       OS << ",none," << Reserved2;
 121     OS << '\n';
 122     return;
 123   }
 124
 125   // Check each attribute to see if we have it.
 126   char Separator = ',';
 127   for (unsigned i = 0; SectionAttrDescriptors[i].AttrFlag; ++i) {
 128     // Check to see if we have this attribute.
 129     if ((SectionAttrDescriptors[i].AttrFlag & SectionAttrs) == 0)
 130       continue;
 131
 132     // Yep, clear it and print it.
 133     SectionAttrs &= ~SectionAttrDescriptors[i].AttrFlag;
 134
 135     OS << Separator;
 136     if (SectionAttrDescriptors[i].AssemblerName)
 137       OS << SectionAttrDescriptors[i].AssemblerName;
 138     else
 139       OS << "<<" << SectionAttrDescriptors[i].EnumName << ">>";
 140     Separator = '+';
 141   }
 142
 143   assert(SectionAttrs == 0 && "Unknown section attributes!");
 144
 145   // If we have a S_SYMBOL_STUBS size specified, print it.
 146   if (Reserved2 != 0)
 147     OS << ',' << Reserved2;
 148   OS << '\n';
 149 }
 150
 151 bool MCSectionMachO::UseCodeAlign() const {
 152   return hasAttribute(MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS);
 153 }
 154
 155 /// StripSpaces - This removes leading and trailing spaces from the StringRef.
 156 static void StripSpaces(StringRef &Str) {
 157   while (!Str.empty() && isspace(Str[0]))
 158     Str = Str.substr(1);
 159   while (!Str.empty() && isspace(Str.back()))
 160     Str = Str.substr(0, Str.size()-1);
 161 }
 162
 163 /// ParseSectionSpecifier - Parse the section specifier indicated by "Spec".
 164 /// This is a string that can appear after a .section directive in a mach-o
 165 /// flavored .s file.  If successful, this fills in the specified Out
 166 /// parameters and returns an empty string.  When an invalid section
 167 /// specifier is present, this returns a string indicating the problem.
 168 std::string MCSectionMachO::ParseSectionSpecifier(StringRef Spec,        // In.
 169                                                   StringRef &Segment,    // Out.
 170                                                   StringRef &Section,    // Out.
 171                                                   unsigned  &TAA,        // Out.
 172                                                   unsigned  &StubSize) { // Out.
 173   // Find the first comma.
 174   std::pair<StringRef, StringRef> Comma = Spec.split(',');
 175
 176   // If there is no comma, we fail.
 177   if (Comma.second.empty())
 178     return "mach-o section specifier requires a segment and section "
 179            "separated by a comma";
 180
 181   // Capture segment, remove leading and trailing whitespace.
 182   Segment = Comma.first;
 183   StripSpaces(Segment);
 184
 185   // Verify that the segment is present and not too long.
 186   if (Segment.empty() || Segment.size() > 16)
 187     return "mach-o section specifier requires a segment whose length is "
 188            "between 1 and 16 characters";
 189
 190   // Split the section name off from any attributes if present.
 191   Comma = Comma.second.split(',');
 192
 193   // Capture section, remove leading and trailing whitespace.
 194   Section = Comma.first;
 195   StripSpaces(Section);
 196
 197   // Verify that the section is present and not too long.
 198   if (Section.empty() || Section.size() > 16)
 199     return "mach-o section specifier requires a section whose length is "
 200            "between 1 and 16 characters";
 201
 202   // If there is no comma after the section, we're done.
 203   TAA = 0;
 204   StubSize = 0;
 205   if (Comma.second.empty())
 206     return "";
 207
 208   // Otherwise, we need to parse the section type and attributes.
 209   Comma = Comma.second.split(',');
 210
 211   // Get the section type.
 212   StringRef SectionType = Comma.first;
 213   StripSpaces(SectionType);
 214
 215   // Figure out which section type it is.
 216   unsigned TypeID;
 217   for (TypeID = 0; TypeID !=MCSectionMachO::LAST_KNOWN_SECTION_TYPE+1; ++TypeID)
 218     if (SectionTypeDescriptors[TypeID].AssemblerName &&
 219         SectionType == SectionTypeDescriptors[TypeID].AssemblerName)
 220       break;
 221
 222   // If we didn't find the section type, reject it.
 223   if (TypeID > MCSectionMachO::LAST_KNOWN_SECTION_TYPE)
 224     return "mach-o section specifier uses an unknown section type";
 225
 226   // Remember the TypeID.
 227   TAA = TypeID;
 228
 229   // If we have no comma after the section type, there are no attributes.
 230   if (Comma.second.empty()) {
 231     // S_SYMBOL_STUBS always require a symbol stub size specifier.
 232     if (TAA == MCSectionMachO::S_SYMBOL_STUBS)
 233       return "mach-o section specifier of type 'symbol_stubs' requires a size "
 234              "specifier";
 235     return "";
 236   }
 237
 238   // Otherwise, we do have some attributes.  Split off the size specifier if
 239   // present.
 240   Comma = Comma.second.split(',');
 241   StringRef Attrs = Comma.first;
 242
 243   // The attribute list is a '+' separated list of attributes.
 244   std::pair<StringRef, StringRef> Plus = Attrs.split('+');
 245
 246   while (1) {
 247     StringRef Attr = Plus.first;
 248     StripSpaces(Attr);
 249
 250     // Look up the attribute.
 251     for (unsigned i = 0; ; ++i) {
 252       if (SectionAttrDescriptors[i].AttrFlag == AttrFlagEnd)
 253         return "mach-o section specifier has invalid attribute";
 254
 255       if (SectionAttrDescriptors[i].AssemblerName &&
 256           Attr == SectionAttrDescriptors[i].AssemblerName) {
 257         TAA |= SectionAttrDescriptors[i].AttrFlag;
 258         break;
 259       }
 260     }
 261
 262     if (Plus.second.empty()) break;
 263     Plus = Plus.second.split('+');
 264   };
 265
 266   // Okay, we've parsed the section attributes, see if we have a stub size spec.
 267   if (Comma.second.empty()) {
 268     // S_SYMBOL_STUBS always require a symbol stub size specifier.
 269     if (TAA == MCSectionMachO::S_SYMBOL_STUBS)
 270       return "mach-o section specifier of type 'symbol_stubs' requires a size "
 271       "specifier";
 272     return "";
 273   }
 274
 275   // If we have a stub size spec, we must have a sectiontype of S_SYMBOL_STUBS.
 276   if ((TAA & MCSectionMachO::SECTION_TYPE) != MCSectionMachO::S_SYMBOL_STUBS)
 277     return "mach-o section specifier cannot have a stub size specified because "
 278            "it does not have type 'symbol_stubs'";
 279
 280   // Okay, if we do, it must be a number.
 281   StringRef StubSizeStr = Comma.second;
 282   StripSpaces(StubSizeStr);
 283
 284   // Convert the stub size from a string to an integer.
 285   if (StubSizeStr.getAsInteger(0, StubSize))
 286     return "mach-o section specifier has a malformed stub size";
 287
 288   return "";
 289 }