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