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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/ADT/SmallString.h"
     12 #include "llvm/ADT/Twine.h"
     13 #include "llvm/MC/MCAsmInfo.h"
     14 #include "llvm/MC/MCDwarf.h"
     15 #include "llvm/MC/MCLabel.h"
     16 #include "llvm/MC/MCObjectFileInfo.h"
     17 #include "llvm/MC/MCRegisterInfo.h"
     18 #include "llvm/MC/MCSectionCOFF.h"
     19 #include "llvm/MC/MCSectionELF.h"
     20 #include "llvm/MC/MCSectionMachO.h"
     21 #include "llvm/MC/MCSymbol.h"
     22 #include "llvm/Support/ELF.h"
     23 #include "llvm/Support/ErrorHandling.h"
     24 #include "llvm/Support/MemoryBuffer.h"
     25 #include "llvm/Support/Signals.h"
     26 #include "llvm/Support/SourceMgr.h"
     27 using namespace llvm;
     28 
     29 typedef StringMap<const MCSectionMachO*> MachOUniqueMapTy;
     30 typedef StringMap<const MCSectionELF*> ELFUniqueMapTy;
     31 typedef StringMap<const MCSectionCOFF*> COFFUniqueMapTy;
     32 
     33 
     34 MCContext::MCContext(const MCAsmInfo &mai, const MCRegisterInfo &mri,
     35                      const MCObjectFileInfo *mofi, const SourceMgr *mgr,
     36                      bool DoAutoReset) :
     37   SrcMgr(mgr), MAI(mai), MRI(mri), MOFI(mofi),
     38   Allocator(), Symbols(Allocator), UsedNames(Allocator),
     39   NextUniqueID(0),
     40   CompilationDir(llvm::sys::Path::GetCurrentDirectory().str()),
     41   CurrentDwarfLoc(0,0,0,DWARF2_FLAG_IS_STMT,0,0),
     42   DwarfLocSeen(false), GenDwarfForAssembly(false), GenDwarfFileNumber(0),
     43   AllowTemporaryLabels(true), DwarfCompileUnitID(0), AutoReset(DoAutoReset) {
     44 
     45   MachOUniquingMap = 0;
     46   ELFUniquingMap = 0;
     47   COFFUniquingMap = 0;
     48 
     49   SecureLogFile = getenv("AS_SECURE_LOG_FILE");
     50   SecureLog = 0;
     51   SecureLogUsed = false;
     52 
     53   if (SrcMgr && SrcMgr->getNumBuffers() > 0)
     54     MainFileName = SrcMgr->getMemoryBuffer(0)->getBufferIdentifier();
     55   else
     56     MainFileName = "";
     57 }
     58 
     59 MCContext::~MCContext() {
     60 
     61   if (AutoReset)
     62     reset();
     63 
     64   // NOTE: The symbols are all allocated out of a bump pointer allocator,
     65   // we don't need to free them here.
     66 
     67   // If the stream for the .secure_log_unique directive was created free it.
     68   delete (raw_ostream*)SecureLog;
     69 }
     70 
     71 //===----------------------------------------------------------------------===//
     72 // Module Lifetime Management
     73 //===----------------------------------------------------------------------===//
     74 
     75 void MCContext::reset() {
     76   UsedNames.clear();
     77   Symbols.clear();
     78   Allocator.Reset();
     79   Instances.clear();
     80   MCDwarfFilesCUMap.clear();
     81   MCDwarfDirsCUMap.clear();
     82   MCGenDwarfLabelEntries.clear();
     83   DwarfDebugFlags = StringRef();
     84   MCLineSections.clear();
     85   MCLineSectionOrder.clear();
     86   DwarfCompileUnitID = 0;
     87   MCLineTableSymbols.clear();
     88   CurrentDwarfLoc = MCDwarfLoc(0,0,0,DWARF2_FLAG_IS_STMT,0,0);
     89 
     90   // If we have the MachO uniquing map, free it.
     91   delete (MachOUniqueMapTy*)MachOUniquingMap;
     92   delete (ELFUniqueMapTy*)ELFUniquingMap;
     93   delete (COFFUniqueMapTy*)COFFUniquingMap;
     94   MachOUniquingMap = 0;
     95   ELFUniquingMap = 0;
     96   COFFUniquingMap = 0;
     97 
     98   NextUniqueID = 0;
     99   AllowTemporaryLabels = true;
    100   DwarfLocSeen = false;
    101   GenDwarfForAssembly = false;
    102   GenDwarfFileNumber = 0;
    103 }
    104 
    105 //===----------------------------------------------------------------------===//
    106 // Symbol Manipulation
    107 //===----------------------------------------------------------------------===//
    108 
    109 MCSymbol *MCContext::GetOrCreateSymbol(StringRef Name) {
    110   assert(!Name.empty() && "Normal symbols cannot be unnamed!");
    111 
    112   // Do the lookup and get the entire StringMapEntry.  We want access to the
    113   // key if we are creating the entry.
    114   StringMapEntry<MCSymbol*> &Entry = Symbols.GetOrCreateValue(Name);
    115   MCSymbol *Sym = Entry.getValue();
    116 
    117   if (Sym)
    118     return Sym;
    119 
    120   Sym = CreateSymbol(Name);
    121   Entry.setValue(Sym);
    122   return Sym;
    123 }
    124 
    125 MCSymbol *MCContext::CreateSymbol(StringRef Name) {
    126   // Determine whether this is an assembler temporary or normal label, if used.
    127   bool isTemporary = false;
    128   if (AllowTemporaryLabels)
    129     isTemporary = Name.startswith(MAI.getPrivateGlobalPrefix());
    130 
    131   StringMapEntry<bool> *NameEntry = &UsedNames.GetOrCreateValue(Name);
    132   if (NameEntry->getValue()) {
    133     assert(isTemporary && "Cannot rename non temporary symbols");
    134     SmallString<128> NewName = Name;
    135     do {
    136       NewName.resize(Name.size());
    137       raw_svector_ostream(NewName) << NextUniqueID++;
    138       NameEntry = &UsedNames.GetOrCreateValue(NewName);
    139     } while (NameEntry->getValue());
    140   }
    141   NameEntry->setValue(true);
    142 
    143   // Ok, the entry doesn't already exist.  Have the MCSymbol object itself refer
    144   // to the copy of the string that is embedded in the UsedNames entry.
    145   MCSymbol *Result = new (*this) MCSymbol(NameEntry->getKey(), isTemporary);
    146 
    147   return Result;
    148 }
    149 
    150 MCSymbol *MCContext::GetOrCreateSymbol(const Twine &Name) {
    151   SmallString<128> NameSV;
    152   Name.toVector(NameSV);
    153   return GetOrCreateSymbol(NameSV.str());
    154 }
    155 
    156 MCSymbol *MCContext::CreateTempSymbol() {
    157   SmallString<128> NameSV;
    158   raw_svector_ostream(NameSV)
    159     << MAI.getPrivateGlobalPrefix() << "tmp" << NextUniqueID++;
    160   return CreateSymbol(NameSV);
    161 }
    162 
    163 unsigned MCContext::NextInstance(int64_t LocalLabelVal) {
    164   MCLabel *&Label = Instances[LocalLabelVal];
    165   if (!Label)
    166     Label = new (*this) MCLabel(0);
    167   return Label->incInstance();
    168 }
    169 
    170 unsigned MCContext::GetInstance(int64_t LocalLabelVal) {
    171   MCLabel *&Label = Instances[LocalLabelVal];
    172   if (!Label)
    173     Label = new (*this) MCLabel(0);
    174   return Label->getInstance();
    175 }
    176 
    177 MCSymbol *MCContext::CreateDirectionalLocalSymbol(int64_t LocalLabelVal) {
    178   return GetOrCreateSymbol(Twine(MAI.getPrivateGlobalPrefix()) +
    179                            Twine(LocalLabelVal) +
    180                            "\2" +
    181                            Twine(NextInstance(LocalLabelVal)));
    182 }
    183 MCSymbol *MCContext::GetDirectionalLocalSymbol(int64_t LocalLabelVal,
    184                                                int bORf) {
    185   return GetOrCreateSymbol(Twine(MAI.getPrivateGlobalPrefix()) +
    186                            Twine(LocalLabelVal) +
    187                            "\2" +
    188                            Twine(GetInstance(LocalLabelVal) + bORf));
    189 }
    190 
    191 MCSymbol *MCContext::LookupSymbol(StringRef Name) const {
    192   return Symbols.lookup(Name);
    193 }
    194 
    195 MCSymbol *MCContext::LookupSymbol(const Twine &Name) const {
    196   SmallString<128> NameSV;
    197   Name.toVector(NameSV);
    198   return LookupSymbol(NameSV.str());
    199 }
    200 
    201 //===----------------------------------------------------------------------===//
    202 // Section Management
    203 //===----------------------------------------------------------------------===//
    204 
    205 const MCSectionMachO *MCContext::
    206 getMachOSection(StringRef Segment, StringRef Section,
    207                 unsigned TypeAndAttributes,
    208                 unsigned Reserved2, SectionKind Kind) {
    209 
    210   // We unique sections by their segment/section pair.  The returned section
    211   // may not have the same flags as the requested section, if so this should be
    212   // diagnosed by the client as an error.
    213 
    214   // Create the map if it doesn't already exist.
    215   if (MachOUniquingMap == 0)
    216     MachOUniquingMap = new MachOUniqueMapTy();
    217   MachOUniqueMapTy &Map = *(MachOUniqueMapTy*)MachOUniquingMap;
    218 
    219   // Form the name to look up.
    220   SmallString<64> Name;
    221   Name += Segment;
    222   Name.push_back(',');
    223   Name += Section;
    224 
    225   // Do the lookup, if we have a hit, return it.
    226   const MCSectionMachO *&Entry = Map[Name.str()];
    227   if (Entry) return Entry;
    228 
    229   // Otherwise, return a new section.
    230   return Entry = new (*this) MCSectionMachO(Segment, Section, TypeAndAttributes,
    231                                             Reserved2, Kind);
    232 }
    233 
    234 const MCSectionELF *MCContext::
    235 getELFSection(StringRef Section, unsigned Type, unsigned Flags,
    236               SectionKind Kind) {
    237   return getELFSection(Section, Type, Flags, Kind, 0, "");
    238 }
    239 
    240 const MCSectionELF *MCContext::
    241 getELFSection(StringRef Section, unsigned Type, unsigned Flags,
    242               SectionKind Kind, unsigned EntrySize, StringRef Group) {
    243   if (ELFUniquingMap == 0)
    244     ELFUniquingMap = new ELFUniqueMapTy();
    245   ELFUniqueMapTy &Map = *(ELFUniqueMapTy*)ELFUniquingMap;
    246 
    247   // Do the lookup, if we have a hit, return it.
    248   StringMapEntry<const MCSectionELF*> &Entry = Map.GetOrCreateValue(Section);
    249   if (Entry.getValue()) return Entry.getValue();
    250 
    251   // Possibly refine the entry size first.
    252   if (!EntrySize) {
    253     EntrySize = MCSectionELF::DetermineEntrySize(Kind);
    254   }
    255 
    256   MCSymbol *GroupSym = NULL;
    257   if (!Group.empty())
    258     GroupSym = GetOrCreateSymbol(Group);
    259 
    260   MCSectionELF *Result = new (*this) MCSectionELF(Entry.getKey(), Type, Flags,
    261                                                   Kind, EntrySize, GroupSym);
    262   Entry.setValue(Result);
    263   return Result;
    264 }
    265 
    266 const MCSectionELF *MCContext::CreateELFGroupSection() {
    267   MCSectionELF *Result =
    268     new (*this) MCSectionELF(".group", ELF::SHT_GROUP, 0,
    269                              SectionKind::getReadOnly(), 4, NULL);
    270   return Result;
    271 }
    272 
    273 const MCSection *MCContext::getCOFFSection(StringRef Section,
    274                                            unsigned Characteristics,
    275                                            int Selection,
    276                                            SectionKind Kind) {
    277   if (COFFUniquingMap == 0)
    278     COFFUniquingMap = new COFFUniqueMapTy();
    279   COFFUniqueMapTy &Map = *(COFFUniqueMapTy*)COFFUniquingMap;
    280 
    281   // Do the lookup, if we have a hit, return it.
    282   StringMapEntry<const MCSectionCOFF*> &Entry = Map.GetOrCreateValue(Section);
    283   if (Entry.getValue()) return Entry.getValue();
    284 
    285   MCSectionCOFF *Result = new (*this) MCSectionCOFF(Entry.getKey(),
    286                                                     Characteristics,
    287                                                     Selection, Kind);
    288 
    289   Entry.setValue(Result);
    290   return Result;
    291 }
    292 
    293 //===----------------------------------------------------------------------===//
    294 // Dwarf Management
    295 //===----------------------------------------------------------------------===//
    296 
    297 /// GetDwarfFile - takes a file name an number to place in the dwarf file and
    298 /// directory tables.  If the file number has already been allocated it is an
    299 /// error and zero is returned and the client reports the error, else the
    300 /// allocated file number is returned.  The file numbers may be in any order.
    301 unsigned MCContext::GetDwarfFile(StringRef Directory, StringRef FileName,
    302                                  unsigned FileNumber, unsigned CUID) {
    303   // TODO: a FileNumber of zero says to use the next available file number.
    304   // Note: in GenericAsmParser::ParseDirectiveFile() FileNumber was checked
    305   // to not be less than one.  This needs to be change to be not less than zero.
    306 
    307   SmallVectorImpl<MCDwarfFile *>& MCDwarfFiles = MCDwarfFilesCUMap[CUID];
    308   SmallVectorImpl<StringRef>& MCDwarfDirs = MCDwarfDirsCUMap[CUID];
    309   // Make space for this FileNumber in the MCDwarfFiles vector if needed.
    310   if (FileNumber >= MCDwarfFiles.size()) {
    311     MCDwarfFiles.resize(FileNumber + 1);
    312   } else {
    313     MCDwarfFile *&ExistingFile = MCDwarfFiles[FileNumber];
    314     if (ExistingFile)
    315       // It is an error to use see the same number more than once.
    316       return 0;
    317   }
    318 
    319   // Get the new MCDwarfFile slot for this FileNumber.
    320   MCDwarfFile *&File = MCDwarfFiles[FileNumber];
    321 
    322   if (Directory.empty()) {
    323     // Separate the directory part from the basename of the FileName.
    324     StringRef tFileName = sys::path::filename(FileName);
    325     if (!tFileName.empty()) {
    326       Directory = sys::path::parent_path(FileName);
    327       if (!Directory.empty())
    328         FileName = tFileName;
    329     }
    330   }
    331 
    332   // Find or make a entry in the MCDwarfDirs vector for this Directory.
    333   // Capture directory name.
    334   unsigned DirIndex;
    335   if (Directory.empty()) {
    336     // For FileNames with no directories a DirIndex of 0 is used.
    337     DirIndex = 0;
    338   } else {
    339     DirIndex = 0;
    340     for (unsigned End = MCDwarfDirs.size(); DirIndex < End; DirIndex++) {
    341       if (Directory == MCDwarfDirs[DirIndex])
    342         break;
    343     }
    344     if (DirIndex >= MCDwarfDirs.size()) {
    345       char *Buf = static_cast<char *>(Allocate(Directory.size()));
    346       memcpy(Buf, Directory.data(), Directory.size());
    347       MCDwarfDirs.push_back(StringRef(Buf, Directory.size()));
    348     }
    349     // The DirIndex is one based, as DirIndex of 0 is used for FileNames with
    350     // no directories.  MCDwarfDirs[] is unlike MCDwarfFiles[] in that the
    351     // directory names are stored at MCDwarfDirs[DirIndex-1] where FileNames
    352     // are stored at MCDwarfFiles[FileNumber].Name .
    353     DirIndex++;
    354   }
    355 
    356   // Now make the MCDwarfFile entry and place it in the slot in the MCDwarfFiles
    357   // vector.
    358   char *Buf = static_cast<char *>(Allocate(FileName.size()));
    359   memcpy(Buf, FileName.data(), FileName.size());
    360   File = new (*this) MCDwarfFile(StringRef(Buf, FileName.size()), DirIndex);
    361 
    362   // return the allocated FileNumber.
    363   return FileNumber;
    364 }
    365 
    366 /// isValidDwarfFileNumber - takes a dwarf file number and returns true if it
    367 /// currently is assigned and false otherwise.
    368 bool MCContext::isValidDwarfFileNumber(unsigned FileNumber, unsigned CUID) {
    369   SmallVectorImpl<MCDwarfFile *>& MCDwarfFiles = MCDwarfFilesCUMap[CUID];
    370   if(FileNumber == 0 || FileNumber >= MCDwarfFiles.size())
    371     return false;
    372 
    373   return MCDwarfFiles[FileNumber] != 0;
    374 }
    375 
    376 void MCContext::FatalError(SMLoc Loc, const Twine &Msg) {
    377   // If we have a source manager and a location, use it. Otherwise just
    378   // use the generic report_fatal_error().
    379   if (!SrcMgr || Loc == SMLoc())
    380     report_fatal_error(Msg);
    381 
    382   // Use the source manager to print the message.
    383   SrcMgr->PrintMessage(Loc, SourceMgr::DK_Error, Msg);
    384 
    385   // If we reached here, we are failing ungracefully. Run the interrupt handlers
    386   // to make sure any special cleanups get done, in particular that we remove
    387   // files registered with RemoveFileOnSignal.
    388   sys::RunInterruptHandlers();
    389   exit(1);
    390 }
    391