Home | History | Annotate | Download | only in MC 
      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 using namespace llvm;
     24 
     25 typedef StringMap<const MCSectionMachO*> MachOUniqueMapTy;
     26 typedef StringMap<const MCSectionELF*> ELFUniqueMapTy;
     27 typedef StringMap<const MCSectionCOFF*> COFFUniqueMapTy;
     28 
     29 
     30 MCContext::MCContext(const MCAsmInfo &mai, const MCRegisterInfo &mri,
     31                      const MCObjectFileInfo *mofi) :
     32   MAI(mai), MRI(mri), MOFI(mofi),
     33   Allocator(), Symbols(Allocator), UsedNames(Allocator),
     34   NextUniqueID(0),
     35   CurrentDwarfLoc(0,0,0,DWARF2_FLAG_IS_STMT,0,0),
     36   AllowTemporaryLabels(true) {
     37   MachOUniquingMap = 0;
     38   ELFUniquingMap = 0;
     39   COFFUniquingMap = 0;
     40 
     41   SecureLogFile = getenv("AS_SECURE_LOG_FILE");
     42   SecureLog = 0;
     43   SecureLogUsed = false;
     44 
     45   DwarfLocSeen = false;
     46 }
     47 
     48 MCContext::~MCContext() {
     49   // NOTE: The symbols are all allocated out of a bump pointer allocator,
     50   // we don't need to free them here.
     51 
     52   // If we have the MachO uniquing map, free it.
     53   delete (MachOUniqueMapTy*)MachOUniquingMap;
     54   delete (ELFUniqueMapTy*)ELFUniquingMap;
     55   delete (COFFUniqueMapTy*)COFFUniquingMap;
     56 
     57   // If the stream for the .secure_log_unique directive was created free it.
     58   delete (raw_ostream*)SecureLog;
     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     DirIndex = 0;
    283     for (unsigned End = MCDwarfDirs.size(); DirIndex < End; DirIndex++) {
    284       if (Directory == MCDwarfDirs[DirIndex])
    285         break;
    286     }
    287     if (DirIndex >= MCDwarfDirs.size()) {
    288       char *Buf = static_cast<char *>(Allocate(Directory.size()));
    289       memcpy(Buf, Directory.data(), Directory.size());
    290       MCDwarfDirs.push_back(StringRef(Buf, Directory.size()));
    291     }
    292     // The DirIndex is one based, as DirIndex of 0 is used for FileNames with
    293     // no directories.  MCDwarfDirs[] is unlike MCDwarfFiles[] in that the
    294     // directory names are stored at MCDwarfDirs[DirIndex-1] where FileNames are
    295     // stored at MCDwarfFiles[FileNumber].Name .
    296     DirIndex++;
    297   }
    298 
    299   // Now make the MCDwarfFile entry and place it in the slot in the MCDwarfFiles
    300   // vector.
    301   char *Buf = static_cast<char *>(Allocate(Name.size()));
    302   memcpy(Buf, Name.data(), Name.size());
    303   File = new (*this) MCDwarfFile(StringRef(Buf, Name.size()), DirIndex);
    304 
    305   // return the allocated FileNumber.
    306   return FileNumber;
    307 }
    308 
    309 /// isValidDwarfFileNumber - takes a dwarf file number and returns true if it
    310 /// currently is assigned and false otherwise.
    311 bool MCContext::isValidDwarfFileNumber(unsigned FileNumber) {
    312   if(FileNumber == 0 || FileNumber >= MCDwarfFiles.size())
    313     return false;
    314 
    315   return MCDwarfFiles[FileNumber] != 0;
    316 }
    317