lib/MC/MCContext.cpp

   1 //===- lib/MC/MCContext.cpp - Machine Code Context ------------------------===//
   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/MCContext.h"
  11 #include "llvm/MC/MCAsmInfo.h"
  12 #include "llvm/MC/MCSectionMachO.h"
  13 #include "llvm/MC/MCSectionELF.h"
  14 #include "llvm/MC/MCSectionCOFF.h"
  15 #include "llvm/MC/MCSymbol.h"
  16 #include "llvm/MC/MCLabel.h"
  17 #include "llvm/MC/MCDwarf.h"
  18 #include "llvm/Target/TargetAsmInfo.h"
  19 #include "llvm/ADT/SmallString.h"
  20 #include "llvm/ADT/Twine.h"
  21 #include "llvm/Support/ELF.h"
  22 using namespace llvm;
  23
  24 typedef StringMap<const MCSectionMachO*> MachOUniqueMapTy;
  25 typedef StringMap<const MCSectionELF*> ELFUniqueMapTy;
  26 typedef StringMap<const MCSectionCOFF*> COFFUniqueMapTy;
  27
  28
  29 MCContext::MCContext(const MCAsmInfo &mai, const TargetAsmInfo *tai) :
  30   MAI(mai), TAI(tai),
  31   Allocator(), Symbols(Allocator), UsedNames(Allocator),
  32   NextUniqueID(0),
  33   CurrentDwarfLoc(0,0,0,DWARF2_FLAG_IS_STMT,0,0),
  34   AllowTemporaryLabels(true) {
  35   MachOUniquingMap = 0;
  36   ELFUniquingMap = 0;
  37   COFFUniquingMap = 0;
  38
  39   SecureLogFile = getenv("AS_SECURE_LOG_FILE");
  40   SecureLog = 0;
  41   SecureLogUsed = false;
  42
  43   DwarfLocSeen = false;
  44 }
  45
  46 MCContext::~MCContext() {
  47   // NOTE: The symbols are all allocated out of a bump pointer allocator,
  48   // we don't need to free them here.
  49
  50   // If we have the MachO uniquing map, free it.
  51   delete (MachOUniqueMapTy*)MachOUniquingMap;
  52   delete (ELFUniqueMapTy*)ELFUniquingMap;
  53   delete (COFFUniqueMapTy*)COFFUniquingMap;
  54
  55   // If the stream for the .secure_log_unique directive was created free it.
  56   delete (raw_ostream*)SecureLog;
  57
  58   delete TAI;
  59 }
  60
  61 //===----------------------------------------------------------------------===//
  62 // Symbol Manipulation
  63 //===----------------------------------------------------------------------===//
  64
  65 MCSymbol *MCContext::GetOrCreateSymbol(StringRef Name) {
  66   assert(!Name.empty() && "Normal symbols cannot be unnamed!");
  67
  68   // Do the lookup and get the entire StringMapEntry.  We want access to the
  69   // key if we are creating the entry.
  70   StringMapEntry<MCSymbol*> &Entry = Symbols.GetOrCreateValue(Name);
  71   MCSymbol *Sym = Entry.getValue();
  72
  73   if (Sym)
  74     return Sym;
  75
  76   Sym = CreateSymbol(Name);
  77   Entry.setValue(Sym);
  78   return Sym;
  79 }
  80
  81 MCSymbol *MCContext::CreateSymbol(StringRef Name) {
  82   // Determine whether this is an assembler temporary or normal label, if used.
  83   bool isTemporary = false;
  84   if (AllowTemporaryLabels)
  85     isTemporary = Name.startswith(MAI.getPrivateGlobalPrefix());
  86
  87   StringMapEntry<bool> *NameEntry = &UsedNames.GetOrCreateValue(Name);
  88   if (NameEntry->getValue()) {
  89     assert(isTemporary && "Cannot rename non temporary symbols");
  90     SmallString<128> NewName = Name;
  91     do {
  92       NewName.resize(Name.size());
  93       raw_svector_ostream(NewName) << NextUniqueID++;
  94       NameEntry = &UsedNames.GetOrCreateValue(NewName);
  95     } while (NameEntry->getValue());
  96   }
  97   NameEntry->setValue(true);
  98
  99   // Ok, the entry doesn't already exist.  Have the MCSymbol object itself refer
 100   // to the copy of the string that is embedded in the UsedNames entry.
 101   MCSymbol *Result = new (*this) MCSymbol(NameEntry->getKey(), isTemporary);
 102
 103   return Result;
 104 }
 105
 106 MCSymbol *MCContext::GetOrCreateSymbol(const Twine &Name) {
 107   SmallString<128> NameSV;
 108   Name.toVector(NameSV);
 109   return GetOrCreateSymbol(NameSV.str());
 110 }
 111
 112 MCSymbol *MCContext::CreateTempSymbol() {
 113   SmallString<128> NameSV;
 114   raw_svector_ostream(NameSV)
 115     << MAI.getPrivateGlobalPrefix() << "tmp" << NextUniqueID++;
 116   return CreateSymbol(NameSV);
 117 }
 118
 119 unsigned MCContext::NextInstance(int64_t LocalLabelVal) {
 120   MCLabel *&Label = Instances[LocalLabelVal];
 121   if (!Label)
 122     Label = new (*this) MCLabel(0);
 123   return Label->incInstance();
 124 }
 125
 126 unsigned MCContext::GetInstance(int64_t LocalLabelVal) {
 127   MCLabel *&Label = Instances[LocalLabelVal];
 128   if (!Label)
 129     Label = new (*this) MCLabel(0);
 130   return Label->getInstance();
 131 }
 132
 133 MCSymbol *MCContext::CreateDirectionalLocalSymbol(int64_t LocalLabelVal) {
 134   return GetOrCreateSymbol(Twine(MAI.getPrivateGlobalPrefix()) +
 135                            Twine(LocalLabelVal) +
 136                            "\2" +
 137                            Twine(NextInstance(LocalLabelVal)));
 138 }
 139 MCSymbol *MCContext::GetDirectionalLocalSymbol(int64_t LocalLabelVal,
 140                                                int bORf) {
 141   return GetOrCreateSymbol(Twine(MAI.getPrivateGlobalPrefix()) +
 142                            Twine(LocalLabelVal) +
 143                            "\2" +
 144                            Twine(GetInstance(LocalLabelVal) + bORf));
 145 }
 146
 147 MCSymbol *MCContext::LookupSymbol(StringRef Name) const {
 148   return Symbols.lookup(Name);
 149 }
 150
 151 //===----------------------------------------------------------------------===//
 152 // Section Management
 153 //===----------------------------------------------------------------------===//
 154
 155 const MCSectionMachO *MCContext::
 156 getMachOSection(StringRef Segment, StringRef Section,
 157                 unsigned TypeAndAttributes,
 158                 unsigned Reserved2, SectionKind Kind) {
 159
 160   // We unique sections by their segment/section pair.  The returned section
 161   // may not have the same flags as the requested section, if so this should be
 162   // diagnosed by the client as an error.
 163
 164   // Create the map if it doesn't already exist.
 165   if (MachOUniquingMap == 0)
 166     MachOUniquingMap = new MachOUniqueMapTy();
 167   MachOUniqueMapTy &Map = *(MachOUniqueMapTy*)MachOUniquingMap;
 168
 169   // Form the name to look up.
 170   SmallString<64> Name;
 171   Name += Segment;
 172   Name.push_back(',');
 173   Name += Section;
 174
 175   // Do the lookup, if we have a hit, return it.
 176   const MCSectionMachO *&Entry = Map[Name.str()];
 177   if (Entry) return Entry;
 178
 179   // Otherwise, return a new section.
 180   return Entry = new (*this) MCSectionMachO(Segment, Section, TypeAndAttributes,
 181                                             Reserved2, Kind);
 182 }
 183
 184 const MCSectionELF *MCContext::
 185 getELFSection(StringRef Section, unsigned Type, unsigned Flags,
 186               SectionKind Kind) {
 187   return getELFSection(Section, Type, Flags, Kind, 0, "");
 188 }
 189
 190 const MCSectionELF *MCContext::
 191 getELFSection(StringRef Section, unsigned Type, unsigned Flags,
 192               SectionKind Kind, unsigned EntrySize, StringRef Group) {
 193   if (ELFUniquingMap == 0)
 194     ELFUniquingMap = new ELFUniqueMapTy();
 195   ELFUniqueMapTy &Map = *(ELFUniqueMapTy*)ELFUniquingMap;
 196
 197   // Do the lookup, if we have a hit, return it.
 198   StringMapEntry<const MCSectionELF*> &Entry = Map.GetOrCreateValue(Section);
 199   if (Entry.getValue()) return Entry.getValue();
 200
 201   // Possibly refine the entry size first.
 202   if (!EntrySize) {
 203     EntrySize = MCSectionELF::DetermineEntrySize(Kind);
 204   }
 205
 206   MCSymbol *GroupSym = NULL;
 207   if (!Group.empty())
 208     GroupSym = GetOrCreateSymbol(Group);
 209
 210   MCSectionELF *Result = new (*this) MCSectionELF(Entry.getKey(), Type, Flags,
 211                                                   Kind, EntrySize, GroupSym);
 212   Entry.setValue(Result);
 213   return Result;
 214 }
 215
 216 const MCSectionELF *MCContext::CreateELFGroupSection() {
 217   MCSectionELF *Result =
 218     new (*this) MCSectionELF(".group", ELF::SHT_GROUP, 0,
 219                              SectionKind::getReadOnly(), 4, NULL);
 220   return Result;
 221 }
 222
 223 const MCSection *MCContext::getCOFFSection(StringRef Section,
 224                                            unsigned Characteristics,
 225                                            int Selection,
 226                                            SectionKind Kind) {
 227   if (COFFUniquingMap == 0)
 228     COFFUniquingMap = new COFFUniqueMapTy();
 229   COFFUniqueMapTy &Map = *(COFFUniqueMapTy*)COFFUniquingMap;
 230
 231   // Do the lookup, if we have a hit, return it.
 232   StringMapEntry<const MCSectionCOFF*> &Entry = Map.GetOrCreateValue(Section);
 233   if (Entry.getValue()) return Entry.getValue();
 234
 235   MCSectionCOFF *Result = new (*this) MCSectionCOFF(Entry.getKey(),
 236                                                     Characteristics,
 237                                                     Selection, Kind);
 238
 239   Entry.setValue(Result);
 240   return Result;
 241 }
 242
 243 //===----------------------------------------------------------------------===//
 244 // Dwarf Management
 245 //===----------------------------------------------------------------------===//
 246
 247 /// GetDwarfFile - takes a file name an number to place in the dwarf file and
 248 /// directory tables.  If the file number has already been allocated it is an
 249 /// error and zero is returned and the client reports the error, else the
 250 /// allocated file number is returned.  The file numbers may be in any order.
 251 unsigned MCContext::GetDwarfFile(StringRef FileName, unsigned FileNumber) {
 252   // TODO: a FileNumber of zero says to use the next available file number.
 253   // Note: in GenericAsmParser::ParseDirectiveFile() FileNumber was checked
 254   // to not be less than one.  This needs to be change to be not less than zero.
 255
 256   // Make space for this FileNumber in the MCDwarfFiles vector if needed.
 257   if (FileNumber >= MCDwarfFiles.size()) {
 258     MCDwarfFiles.resize(FileNumber + 1);
 259   } else {
 260     MCDwarfFile *&ExistingFile = MCDwarfFiles[FileNumber];
 261     if (ExistingFile)
 262       // It is an error to use see the same number more than once.
 263       return 0;
 264   }
 265
 266   // Get the new MCDwarfFile slot for this FileNumber.
 267   MCDwarfFile *&File = MCDwarfFiles[FileNumber];
 268
 269   // Separate the directory part from the basename of the FileName.
 270   std::pair<StringRef, StringRef> Slash = FileName.rsplit('/');
 271
 272   // Find or make a entry in the MCDwarfDirs vector for this Directory.
 273   StringRef Name;
 274   unsigned DirIndex;
 275   // Capture directory name.
 276   if (Slash.second.empty()) {
 277     Name = Slash.first;
 278     DirIndex = 0; // For FileNames with no directories a DirIndex of 0 is used.
 279   } else {
 280     StringRef Directory = Slash.first;
 281     Name = Slash.second;
 282     for (DirIndex = 0; DirIndex < MCDwarfDirs.size(); DirIndex++) {
 283       if (Directory == MCDwarfDirs[DirIndex])
 284         break;
 285     }
 286     if (DirIndex >= MCDwarfDirs.size()) {
 287       char *Buf = static_cast<char *>(Allocate(Directory.size()));
 288       memcpy(Buf, Directory.data(), Directory.size());
 289       MCDwarfDirs.push_back(StringRef(Buf, Directory.size()));
 290     }
 291     // The DirIndex is one based, as DirIndex of 0 is used for FileNames with
 292     // no directories.  MCDwarfDirs[] is unlike MCDwarfFiles[] in that the
 293     // directory names are stored at MCDwarfDirs[DirIndex-1] where FileNames are
 294     // stored at MCDwarfFiles[FileNumber].Name .
 295     DirIndex++;
 296   }
 297
 298   // Now make the MCDwarfFile entry and place it in the slot in the MCDwarfFiles
 299   // vector.
 300   char *Buf = static_cast<char *>(Allocate(Name.size()));
 301   memcpy(Buf, Name.data(), Name.size());
 302   File = new (*this) MCDwarfFile(StringRef(Buf, Name.size()), DirIndex);
 303
 304   // return the allocated FileNumber.
 305   return FileNumber;
 306 }
 307
 308 /// isValidDwarfFileNumber - takes a dwarf file number and returns true if it
 309 /// currently is assigned and false otherwise.
 310 bool MCContext::isValidDwarfFileNumber(unsigned FileNumber) {
 311   if(FileNumber == 0 || FileNumber >= MCDwarfFiles.size())
 312     return false;
 313
 314   return MCDwarfFiles[FileNumber] != 0;
 315 }