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      1 //===- MCContext.h - Machine Code Context -----------------------*- C++ -*-===//
      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 #ifndef LLVM_MC_MCCONTEXT_H
     11 #define LLVM_MC_MCCONTEXT_H
     12 
     13 #include "llvm/MC/SectionKind.h"
     14 #include "llvm/MC/MCDwarf.h"
     15 #include "llvm/ADT/DenseMap.h"
     16 #include "llvm/ADT/StringMap.h"
     17 #include "llvm/Support/Allocator.h"
     18 #include "llvm/Support/raw_ostream.h"
     19 #include <vector> // FIXME: Shouldn't be needed.
     20 
     21 namespace llvm {
     22   class MCAsmInfo;
     23   class MCExpr;
     24   class MCSection;
     25   class MCSymbol;
     26   class MCLabel;
     27   class MCDwarfFile;
     28   class MCDwarfLoc;
     29   class MCObjectFileInfo;
     30   class MCRegisterInfo;
     31   class MCLineSection;
     32   class StringRef;
     33   class Twine;
     34   class TargetAsmInfo;
     35   class MCSectionMachO;
     36   class MCSectionELF;
     37 
     38   /// MCContext - Context object for machine code objects.  This class owns all
     39   /// of the sections that it creates.
     40   ///
     41   class MCContext {
     42     MCContext(const MCContext&); // DO NOT IMPLEMENT
     43     MCContext &operator=(const MCContext&); // DO NOT IMPLEMENT
     44   public:
     45     typedef StringMap<MCSymbol*, BumpPtrAllocator&> SymbolTable;
     46   private:
     47 
     48     /// The MCAsmInfo for this target.
     49     const MCAsmInfo &MAI;
     50 
     51     /// The MCRegisterInfo for this target.
     52     const MCRegisterInfo &MRI;
     53 
     54     /// The MCObjectFileInfo for this target.
     55     const MCObjectFileInfo *MOFI;
     56 
     57     const TargetAsmInfo *TAI;
     58 
     59     /// Allocator - Allocator object used for creating machine code objects.
     60     ///
     61     /// We use a bump pointer allocator to avoid the need to track all allocated
     62     /// objects.
     63     BumpPtrAllocator Allocator;
     64 
     65     /// Symbols - Bindings of names to symbols.
     66     SymbolTable Symbols;
     67 
     68     /// UsedNames - Keeps tracks of names that were used both for used declared
     69     /// and artificial symbols.
     70     StringMap<bool, BumpPtrAllocator&> UsedNames;
     71 
     72     /// NextUniqueID - The next ID to dole out to an unnamed assembler temporary
     73     /// symbol.
     74     unsigned NextUniqueID;
     75 
     76     /// Instances of directional local labels.
     77     DenseMap<unsigned, MCLabel *> Instances;
     78     /// NextInstance() creates the next instance of the directional local label
     79     /// for the LocalLabelVal and adds it to the map if needed.
     80     unsigned NextInstance(int64_t LocalLabelVal);
     81     /// GetInstance() gets the current instance of the directional local label
     82     /// for the LocalLabelVal and adds it to the map if needed.
     83     unsigned GetInstance(int64_t LocalLabelVal);
     84 
     85     /// The file name of the log file from the environment variable
     86     /// AS_SECURE_LOG_FILE.  Which must be set before the .secure_log_unique
     87     /// directive is used or it is an error.
     88     char *SecureLogFile;
     89     /// The stream that gets written to for the .secure_log_unique directive.
     90     raw_ostream *SecureLog;
     91     /// Boolean toggled when .secure_log_unique / .secure_log_reset is seen to
     92     /// catch errors if .secure_log_unique appears twice without
     93     /// .secure_log_reset appearing between them.
     94     bool SecureLogUsed;
     95 
     96     /// The dwarf file and directory tables from the dwarf .file directive.
     97     std::vector<MCDwarfFile *> MCDwarfFiles;
     98     std::vector<StringRef> MCDwarfDirs;
     99 
    100     /// The current dwarf line information from the last dwarf .loc directive.
    101     MCDwarfLoc CurrentDwarfLoc;
    102     bool DwarfLocSeen;
    103 
    104     /// Honor temporary labels, this is useful for debugging semantic
    105     /// differences between temporary and non-temporary labels (primarily on
    106     /// Darwin).
    107     bool AllowTemporaryLabels;
    108 
    109     /// The dwarf line information from the .loc directives for the sections
    110     /// with assembled machine instructions have after seeing .loc directives.
    111     DenseMap<const MCSection *, MCLineSection *> MCLineSections;
    112     /// We need a deterministic iteration order, so we remember the order
    113     /// the elements were added.
    114     std::vector<const MCSection *> MCLineSectionOrder;
    115 
    116     void *MachOUniquingMap, *ELFUniquingMap, *COFFUniquingMap;
    117 
    118     MCSymbol *CreateSymbol(StringRef Name);
    119 
    120   public:
    121     explicit MCContext(const MCAsmInfo &MAI, const MCRegisterInfo &MRI,
    122                        const MCObjectFileInfo *MOFI, const TargetAsmInfo *TAI);
    123     ~MCContext();
    124 
    125     const MCAsmInfo &getAsmInfo() const { return MAI; }
    126 
    127     const MCRegisterInfo &getRegisterInfo() const { return MRI; }
    128 
    129     const MCObjectFileInfo *getObjectFileInfo() const { return MOFI; }
    130 
    131     const TargetAsmInfo &getTargetAsmInfo() const { return *TAI; }
    132 
    133     void setAllowTemporaryLabels(bool Value) { AllowTemporaryLabels = Value; }
    134 
    135     /// @name Symbol Management
    136     /// @{
    137 
    138     /// CreateTempSymbol - Create and return a new assembler temporary symbol
    139     /// with a unique but unspecified name.
    140     MCSymbol *CreateTempSymbol();
    141 
    142     /// CreateDirectionalLocalSymbol - Create the definition of a directional
    143     /// local symbol for numbered label (used for "1:" definitions).
    144     MCSymbol *CreateDirectionalLocalSymbol(int64_t LocalLabelVal);
    145 
    146     /// GetDirectionalLocalSymbol - Create and return a directional local
    147     /// symbol for numbered label (used for "1b" or 1f" references).
    148     MCSymbol *GetDirectionalLocalSymbol(int64_t LocalLabelVal, int bORf);
    149 
    150     /// GetOrCreateSymbol - Lookup the symbol inside with the specified
    151     /// @p Name.  If it exists, return it.  If not, create a forward
    152     /// reference and return it.
    153     ///
    154     /// @param Name - The symbol name, which must be unique across all symbols.
    155     MCSymbol *GetOrCreateSymbol(StringRef Name);
    156     MCSymbol *GetOrCreateSymbol(const Twine &Name);
    157 
    158     /// LookupSymbol - Get the symbol for \p Name, or null.
    159     MCSymbol *LookupSymbol(StringRef Name) const;
    160 
    161     /// getSymbols - Get a reference for the symbol table for clients that
    162     /// want to, for example, iterate over all symbols. 'const' because we
    163     /// still want any modifications to the table itself to use the MCContext
    164     /// APIs.
    165     const SymbolTable &getSymbols() const {
    166       return Symbols;
    167     }
    168 
    169     /// @}
    170 
    171     /// @name Section Management
    172     /// @{
    173 
    174     /// getMachOSection - Return the MCSection for the specified mach-o section.
    175     /// This requires the operands to be valid.
    176     const MCSectionMachO *getMachOSection(StringRef Segment,
    177                                           StringRef Section,
    178                                           unsigned TypeAndAttributes,
    179                                           unsigned Reserved2,
    180                                           SectionKind K);
    181     const MCSectionMachO *getMachOSection(StringRef Segment,
    182                                           StringRef Section,
    183                                           unsigned TypeAndAttributes,
    184                                           SectionKind K) {
    185       return getMachOSection(Segment, Section, TypeAndAttributes, 0, K);
    186     }
    187 
    188     const MCSectionELF *getELFSection(StringRef Section, unsigned Type,
    189                                       unsigned Flags, SectionKind Kind);
    190 
    191     const MCSectionELF *getELFSection(StringRef Section, unsigned Type,
    192                                       unsigned Flags, SectionKind Kind,
    193                                       unsigned EntrySize, StringRef Group);
    194 
    195     const MCSectionELF *CreateELFGroupSection();
    196 
    197     const MCSection *getCOFFSection(StringRef Section, unsigned Characteristics,
    198                                     int Selection, SectionKind Kind);
    199 
    200     const MCSection *getCOFFSection(StringRef Section, unsigned Characteristics,
    201                                     SectionKind Kind) {
    202       return getCOFFSection (Section, Characteristics, 0, Kind);
    203     }
    204 
    205 
    206     /// @}
    207 
    208     /// @name Dwarf Management
    209     /// @{
    210 
    211     /// GetDwarfFile - creates an entry in the dwarf file and directory tables.
    212     unsigned GetDwarfFile(StringRef FileName, unsigned FileNumber);
    213 
    214     bool isValidDwarfFileNumber(unsigned FileNumber);
    215 
    216     bool hasDwarfFiles() const {
    217       return !MCDwarfFiles.empty();
    218     }
    219 
    220     const std::vector<MCDwarfFile *> &getMCDwarfFiles() {
    221       return MCDwarfFiles;
    222     }
    223     const std::vector<StringRef> &getMCDwarfDirs() {
    224       return MCDwarfDirs;
    225     }
    226 
    227     const DenseMap<const MCSection *, MCLineSection *>
    228     &getMCLineSections() const {
    229       return MCLineSections;
    230     }
    231     const std::vector<const MCSection *> &getMCLineSectionOrder() const {
    232       return MCLineSectionOrder;
    233     }
    234     void addMCLineSection(const MCSection *Sec, MCLineSection *Line) {
    235       MCLineSections[Sec] = Line;
    236       MCLineSectionOrder.push_back(Sec);
    237     }
    238 
    239     /// setCurrentDwarfLoc - saves the information from the currently parsed
    240     /// dwarf .loc directive and sets DwarfLocSeen.  When the next instruction
    241     /// is assembled an entry in the line number table with this information and
    242     /// the address of the instruction will be created.
    243     void setCurrentDwarfLoc(unsigned FileNum, unsigned Line, unsigned Column,
    244                             unsigned Flags, unsigned Isa,
    245                             unsigned Discriminator) {
    246       CurrentDwarfLoc.setFileNum(FileNum);
    247       CurrentDwarfLoc.setLine(Line);
    248       CurrentDwarfLoc.setColumn(Column);
    249       CurrentDwarfLoc.setFlags(Flags);
    250       CurrentDwarfLoc.setIsa(Isa);
    251       CurrentDwarfLoc.setDiscriminator(Discriminator);
    252       DwarfLocSeen = true;
    253     }
    254     void ClearDwarfLocSeen() { DwarfLocSeen = false; }
    255 
    256     bool getDwarfLocSeen() { return DwarfLocSeen; }
    257     const MCDwarfLoc &getCurrentDwarfLoc() { return CurrentDwarfLoc; }
    258 
    259     /// @}
    260 
    261     char *getSecureLogFile() { return SecureLogFile; }
    262     raw_ostream *getSecureLog() { return SecureLog; }
    263     bool getSecureLogUsed() { return SecureLogUsed; }
    264     void setSecureLog(raw_ostream *Value) {
    265       SecureLog = Value;
    266     }
    267     void setSecureLogUsed(bool Value) {
    268       SecureLogUsed = Value;
    269     }
    270 
    271     void *Allocate(unsigned Size, unsigned Align = 8) {
    272       return Allocator.Allocate(Size, Align);
    273     }
    274     void Deallocate(void *Ptr) {
    275     }
    276   };
    277 
    278 } // end namespace llvm
    279 
    280 // operator new and delete aren't allowed inside namespaces.
    281 // The throw specifications are mandated by the standard.
    282 /// @brief Placement new for using the MCContext's allocator.
    283 ///
    284 /// This placement form of operator new uses the MCContext's allocator for
    285 /// obtaining memory. It is a non-throwing new, which means that it returns
    286 /// null on error. (If that is what the allocator does. The current does, so if
    287 /// this ever changes, this operator will have to be changed, too.)
    288 /// Usage looks like this (assuming there's an MCContext 'Context' in scope):
    289 /// @code
    290 /// // Default alignment (16)
    291 /// IntegerLiteral *Ex = new (Context) IntegerLiteral(arguments);
    292 /// // Specific alignment
    293 /// IntegerLiteral *Ex2 = new (Context, 8) IntegerLiteral(arguments);
    294 /// @endcode
    295 /// Please note that you cannot use delete on the pointer; it must be
    296 /// deallocated using an explicit destructor call followed by
    297 /// @c Context.Deallocate(Ptr).
    298 ///
    299 /// @param Bytes The number of bytes to allocate. Calculated by the compiler.
    300 /// @param C The MCContext that provides the allocator.
    301 /// @param Alignment The alignment of the allocated memory (if the underlying
    302 ///                  allocator supports it).
    303 /// @return The allocated memory. Could be NULL.
    304 inline void *operator new(size_t Bytes, llvm::MCContext &C,
    305                           size_t Alignment = 16) throw () {
    306   return C.Allocate(Bytes, Alignment);
    307 }
    308 /// @brief Placement delete companion to the new above.
    309 ///
    310 /// This operator is just a companion to the new above. There is no way of
    311 /// invoking it directly; see the new operator for more details. This operator
    312 /// is called implicitly by the compiler if a placement new expression using
    313 /// the MCContext throws in the object constructor.
    314 inline void operator delete(void *Ptr, llvm::MCContext &C, size_t)
    315               throw () {
    316   C.Deallocate(Ptr);
    317 }
    318 
    319 /// This placement form of operator new[] uses the MCContext's allocator for
    320 /// obtaining memory. It is a non-throwing new[], which means that it returns
    321 /// null on error.
    322 /// Usage looks like this (assuming there's an MCContext 'Context' in scope):
    323 /// @code
    324 /// // Default alignment (16)
    325 /// char *data = new (Context) char[10];
    326 /// // Specific alignment
    327 /// char *data = new (Context, 8) char[10];
    328 /// @endcode
    329 /// Please note that you cannot use delete on the pointer; it must be
    330 /// deallocated using an explicit destructor call followed by
    331 /// @c Context.Deallocate(Ptr).
    332 ///
    333 /// @param Bytes The number of bytes to allocate. Calculated by the compiler.
    334 /// @param C The MCContext that provides the allocator.
    335 /// @param Alignment The alignment of the allocated memory (if the underlying
    336 ///                  allocator supports it).
    337 /// @return The allocated memory. Could be NULL.
    338 inline void *operator new[](size_t Bytes, llvm::MCContext& C,
    339                             size_t Alignment = 16) throw () {
    340   return C.Allocate(Bytes, Alignment);
    341 }
    342 
    343 /// @brief Placement delete[] companion to the new[] above.
    344 ///
    345 /// This operator is just a companion to the new[] above. There is no way of
    346 /// invoking it directly; see the new[] operator for more details. This operator
    347 /// is called implicitly by the compiler if a placement new[] expression using
    348 /// the MCContext throws in the object constructor.
    349 inline void operator delete[](void *Ptr, llvm::MCContext &C) throw () {
    350   C.Deallocate(Ptr);
    351 }
    352 
    353 #endif
    354