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      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/MCObjectFileInfo.h"
     13 #include "llvm/MC/MCRegisterInfo.h"
     14 #include "llvm/MC/MCSectionMachO.h"
     15 #include "llvm/MC/MCSectionELF.h"
     16 #include "llvm/MC/MCSectionCOFF.h"
     17 #include "llvm/MC/MCSymbol.h"
     18 #include "llvm/MC/MCLabel.h"
     19 #include "llvm/MC/MCDwarf.h"
     20 #include "llvm/ADT/SmallString.h"
     21 #include "llvm/ADT/Twine.h"
     22 #include "llvm/Support/ELF.h"
     23 #include "llvm/Support/ErrorHandling.h"
     24 #include "llvm/Support/SourceMgr.h"
     25 #include "llvm/Support/Signals.h"
     26 using namespace llvm;
     27 
     28 typedef StringMap<const MCSectionMachO*> MachOUniqueMapTy;
     29 typedef StringMap<const MCSectionELF*> ELFUniqueMapTy;
     30 typedef StringMap<const MCSectionCOFF*> COFFUniqueMapTy;
     31 
     32 
     33 MCContext::MCContext(const MCAsmInfo &mai, const MCRegisterInfo &mri,
     34                      const MCObjectFileInfo *mofi, const SourceMgr *mgr) :
     35   SrcMgr(mgr), MAI(mai), MRI(mri), MOFI(mofi),
     36   Allocator(), Symbols(Allocator), UsedNames(Allocator),
     37   NextUniqueID(0),
     38   CurrentDwarfLoc(0,0,0,DWARF2_FLAG_IS_STMT,0,0),
     39   AllowTemporaryLabels(true) {
     40   MachOUniquingMap = 0;
     41   ELFUniquingMap = 0;
     42   COFFUniquingMap = 0;
     43 
     44   SecureLogFile = getenv("AS_SECURE_LOG_FILE");
     45   SecureLog = 0;
     46   SecureLogUsed = false;
     47 
     48   DwarfLocSeen = false;
     49   GenDwarfForAssembly = false;
     50   GenDwarfFileNumber = 0;
     51 }
     52 
     53 MCContext::~MCContext() {
     54   // NOTE: The symbols are all allocated out of a bump pointer allocator,
     55   // we don't need to free them here.
     56 
     57   // If we have the MachO uniquing map, free it.
     58   delete (MachOUniqueMapTy*)MachOUniquingMap;
     59   delete (ELFUniqueMapTy*)ELFUniquingMap;
     60   delete (COFFUniqueMapTy*)COFFUniquingMap;
     61 
     62   // If the stream for the .secure_log_unique directive was created free it.
     63   delete (raw_ostream*)SecureLog;
     64 }
     65 
     66 //===----------------------------------------------------------------------===//
     67 // Symbol Manipulation
     68 //===----------------------------------------------------------------------===//
     69 
     70 MCSymbol *MCContext::GetOrCreateSymbol(StringRef Name) {
     71   assert(!Name.empty() && "Normal symbols cannot be unnamed!");
     72 
     73   // Do the lookup and get the entire StringMapEntry.  We want access to the
     74   // key if we are creating the entry.
     75   StringMapEntry<MCSymbol*> &Entry = Symbols.GetOrCreateValue(Name);
     76   MCSymbol *Sym = Entry.getValue();
     77 
     78   if (Sym)
     79     return Sym;
     80 
     81   Sym = CreateSymbol(Name);
     82   Entry.setValue(Sym);
     83   return Sym;
     84 }
     85 
     86 MCSymbol *MCContext::CreateSymbol(StringRef Name) {
     87   // Determine whether this is an assembler temporary or normal label, if used.
     88   bool isTemporary = false;
     89   if (AllowTemporaryLabels)
     90     isTemporary = Name.startswith(MAI.getPrivateGlobalPrefix());
     91 
     92   StringMapEntry<bool> *NameEntry = &UsedNames.GetOrCreateValue(Name);
     93   if (NameEntry->getValue()) {
     94     assert(isTemporary && "Cannot rename non temporary symbols");
     95     SmallString<128> NewName = Name;
     96     do {
     97       NewName.resize(Name.size());
     98       raw_svector_ostream(NewName) << NextUniqueID++;
     99       NameEntry = &UsedNames.GetOrCreateValue(NewName);
    100     } while (NameEntry->getValue());
    101   }
    102   NameEntry->setValue(true);
    103 
    104   // Ok, the entry doesn't already exist.  Have the MCSymbol object itself refer
    105   // to the copy of the string that is embedded in the UsedNames entry.
    106   MCSymbol *Result = new (*this) MCSymbol(NameEntry->getKey(), isTemporary);
    107 
    108   return Result;
    109 }
    110 
    111 MCSymbol *MCContext::GetOrCreateSymbol(const Twine &Name) {
    112   SmallString<128> NameSV;
    113   Name.toVector(NameSV);
    114   return GetOrCreateSymbol(NameSV.str());
    115 }
    116 
    117 MCSymbol *MCContext::CreateTempSymbol() {
    118   SmallString<128> NameSV;
    119   raw_svector_ostream(NameSV)
    120     << MAI.getPrivateGlobalPrefix() << "tmp" << NextUniqueID++;
    121   return CreateSymbol(NameSV);
    122 }
    123 
    124 unsigned MCContext::NextInstance(int64_t LocalLabelVal) {
    125   MCLabel *&Label = Instances[LocalLabelVal];
    126   if (!Label)
    127     Label = new (*this) MCLabel(0);
    128   return Label->incInstance();
    129 }
    130 
    131 unsigned MCContext::GetInstance(int64_t LocalLabelVal) {
    132   MCLabel *&Label = Instances[LocalLabelVal];
    133   if (!Label)
    134     Label = new (*this) MCLabel(0);
    135   return Label->getInstance();
    136 }
    137 
    138 MCSymbol *MCContext::CreateDirectionalLocalSymbol(int64_t LocalLabelVal) {
    139   return GetOrCreateSymbol(Twine(MAI.getPrivateGlobalPrefix()) +
    140                            Twine(LocalLabelVal) +
    141                            "\2" +
    142                            Twine(NextInstance(LocalLabelVal)));
    143 }
    144 MCSymbol *MCContext::GetDirectionalLocalSymbol(int64_t LocalLabelVal,
    145                                                int bORf) {
    146   return GetOrCreateSymbol(Twine(MAI.getPrivateGlobalPrefix()) +
    147                            Twine(LocalLabelVal) +
    148                            "\2" +
    149                            Twine(GetInstance(LocalLabelVal) + bORf));
    150 }
    151 
    152 MCSymbol *MCContext::LookupSymbol(StringRef Name) const {
    153   return Symbols.lookup(Name);
    154 }
    155 
    156 //===----------------------------------------------------------------------===//
    157 // Section Management
    158 //===----------------------------------------------------------------------===//
    159 
    160 const MCSectionMachO *MCContext::
    161 getMachOSection(StringRef Segment, StringRef Section,
    162                 unsigned TypeAndAttributes,
    163                 unsigned Reserved2, SectionKind Kind) {
    164 
    165   // We unique sections by their segment/section pair.  The returned section
    166   // may not have the same flags as the requested section, if so this should be
    167   // diagnosed by the client as an error.
    168 
    169   // Create the map if it doesn't already exist.
    170   if (MachOUniquingMap == 0)
    171     MachOUniquingMap = new MachOUniqueMapTy();
    172   MachOUniqueMapTy &Map = *(MachOUniqueMapTy*)MachOUniquingMap;
    173 
    174   // Form the name to look up.
    175   SmallString<64> Name;
    176   Name += Segment;
    177   Name.push_back(',');
    178   Name += Section;
    179 
    180   // Do the lookup, if we have a hit, return it.
    181   const MCSectionMachO *&Entry = Map[Name.str()];
    182   if (Entry) return Entry;
    183 
    184   // Otherwise, return a new section.
    185   return Entry = new (*this) MCSectionMachO(Segment, Section, TypeAndAttributes,
    186                                             Reserved2, Kind);
    187 }
    188 
    189 const MCSectionELF *MCContext::
    190 getELFSection(StringRef Section, unsigned Type, unsigned Flags,
    191               SectionKind Kind) {
    192   return getELFSection(Section, Type, Flags, Kind, 0, "");
    193 }
    194 
    195 const MCSectionELF *MCContext::
    196 getELFSection(StringRef Section, unsigned Type, unsigned Flags,
    197               SectionKind Kind, unsigned EntrySize, StringRef Group) {
    198   if (ELFUniquingMap == 0)
    199     ELFUniquingMap = new ELFUniqueMapTy();
    200   ELFUniqueMapTy &Map = *(ELFUniqueMapTy*)ELFUniquingMap;
    201 
    202   // Do the lookup, if we have a hit, return it.
    203   StringMapEntry<const MCSectionELF*> &Entry = Map.GetOrCreateValue(Section);
    204   if (Entry.getValue()) return Entry.getValue();
    205 
    206   // Possibly refine the entry size first.
    207   if (!EntrySize) {
    208     EntrySize = MCSectionELF::DetermineEntrySize(Kind);
    209   }
    210 
    211   MCSymbol *GroupSym = NULL;
    212   if (!Group.empty())
    213     GroupSym = GetOrCreateSymbol(Group);
    214 
    215   MCSectionELF *Result = new (*this) MCSectionELF(Entry.getKey(), Type, Flags,
    216                                                   Kind, EntrySize, GroupSym);
    217   Entry.setValue(Result);
    218   return Result;
    219 }
    220 
    221 const MCSectionELF *MCContext::CreateELFGroupSection() {
    222   MCSectionELF *Result =
    223     new (*this) MCSectionELF(".group", ELF::SHT_GROUP, 0,
    224                              SectionKind::getReadOnly(), 4, NULL);
    225   return Result;
    226 }
    227 
    228 const MCSection *MCContext::getCOFFSection(StringRef Section,
    229                                            unsigned Characteristics,
    230                                            int Selection,
    231                                            SectionKind Kind) {
    232   if (COFFUniquingMap == 0)
    233     COFFUniquingMap = new COFFUniqueMapTy();
    234   COFFUniqueMapTy &Map = *(COFFUniqueMapTy*)COFFUniquingMap;
    235 
    236   // Do the lookup, if we have a hit, return it.
    237   StringMapEntry<const MCSectionCOFF*> &Entry = Map.GetOrCreateValue(Section);
    238   if (Entry.getValue()) return Entry.getValue();
    239 
    240   MCSectionCOFF *Result = new (*this) MCSectionCOFF(Entry.getKey(),
    241                                                     Characteristics,
    242                                                     Selection, Kind);
    243 
    244   Entry.setValue(Result);
    245   return Result;
    246 }
    247 
    248 //===----------------------------------------------------------------------===//
    249 // Dwarf Management
    250 //===----------------------------------------------------------------------===//
    251 
    252 /// GetDwarfFile - takes a file name an number to place in the dwarf file and
    253 /// directory tables.  If the file number has already been allocated it is an
    254 /// error and zero is returned and the client reports the error, else the
    255 /// allocated file number is returned.  The file numbers may be in any order.
    256 unsigned MCContext::GetDwarfFile(StringRef Directory, StringRef FileName,
    257                                  unsigned FileNumber) {
    258   // TODO: a FileNumber of zero says to use the next available file number.
    259   // Note: in GenericAsmParser::ParseDirectiveFile() FileNumber was checked
    260   // to not be less than one.  This needs to be change to be not less than zero.
    261 
    262   // Make space for this FileNumber in the MCDwarfFiles vector if needed.
    263   if (FileNumber >= MCDwarfFiles.size()) {
    264     MCDwarfFiles.resize(FileNumber + 1);
    265   } else {
    266     MCDwarfFile *&ExistingFile = MCDwarfFiles[FileNumber];
    267     if (ExistingFile)
    268       // It is an error to use see the same number more than once.
    269       return 0;
    270   }
    271 
    272   // Get the new MCDwarfFile slot for this FileNumber.
    273   MCDwarfFile *&File = MCDwarfFiles[FileNumber];
    274 
    275   if (Directory.empty()) {
    276     // Separate the directory part from the basename of the FileName.
    277     std::pair<StringRef, StringRef> Slash = FileName.rsplit('/');
    278     Directory = Slash.second;
    279     if (!Directory.empty()) {
    280       Directory = Slash.first;
    281       FileName = Slash.second;
    282     }
    283   }
    284 
    285   // Find or make a entry in the MCDwarfDirs vector for this Directory.
    286   // Capture directory name.
    287   unsigned DirIndex;
    288   if (Directory.empty()) {
    289     // For FileNames with no directories a DirIndex of 0 is used.
    290     DirIndex = 0;
    291   } else {
    292     DirIndex = 0;
    293     for (unsigned End = MCDwarfDirs.size(); DirIndex < End; DirIndex++) {
    294       if (Directory == MCDwarfDirs[DirIndex])
    295         break;
    296     }
    297     if (DirIndex >= MCDwarfDirs.size()) {
    298       char *Buf = static_cast<char *>(Allocate(Directory.size()));
    299       memcpy(Buf, Directory.data(), Directory.size());
    300       MCDwarfDirs.push_back(StringRef(Buf, Directory.size()));
    301     }
    302     // The DirIndex is one based, as DirIndex of 0 is used for FileNames with
    303     // no directories.  MCDwarfDirs[] is unlike MCDwarfFiles[] in that the
    304     // directory names are stored at MCDwarfDirs[DirIndex-1] where FileNames
    305     // are stored at MCDwarfFiles[FileNumber].Name .
    306     DirIndex++;
    307   }
    308 
    309   // Now make the MCDwarfFile entry and place it in the slot in the MCDwarfFiles
    310   // vector.
    311   char *Buf = static_cast<char *>(Allocate(FileName.size()));
    312   memcpy(Buf, FileName.data(), FileName.size());
    313   File = new (*this) MCDwarfFile(StringRef(Buf, FileName.size()), DirIndex);
    314 
    315   // return the allocated FileNumber.
    316   return FileNumber;
    317 }
    318 
    319 /// isValidDwarfFileNumber - takes a dwarf file number and returns true if it
    320 /// currently is assigned and false otherwise.
    321 bool MCContext::isValidDwarfFileNumber(unsigned FileNumber) {
    322   if(FileNumber == 0 || FileNumber >= MCDwarfFiles.size())
    323     return false;
    324 
    325   return MCDwarfFiles[FileNumber] != 0;
    326 }
    327 
    328 void MCContext::FatalError(SMLoc Loc, const Twine &Msg) {
    329   // If we have a source manager and a location, use it. Otherwise just
    330   // use the generic report_fatal_error().
    331   if (!SrcMgr || Loc == SMLoc())
    332     report_fatal_error(Msg);
    333 
    334   // Use the source manager to print the message.
    335   SrcMgr->PrintMessage(Loc, SourceMgr::DK_Error, Msg);
    336 
    337   // If we reached here, we are failing ungracefully. Run the interrupt handlers
    338   // to make sure any special cleanups get done, in particular that we remove
    339   // files registered with RemoveFileOnSignal.
    340   sys::RunInterruptHandlers();
    341   exit(1);
    342 }
    343