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      1 //===- MCDwarf.h - Machine Code Dwarf support -------------------*- 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 // This file contains the declaration of the MCDwarfFile to support the dwarf
     11 // .file directive and the .loc directive.
     12 //
     13 //===----------------------------------------------------------------------===//
     14 
     15 #ifndef LLVM_MC_MCDWARF_H
     16 #define LLVM_MC_MCDWARF_H
     17 
     18 #include "llvm/ADT/StringRef.h"
     19 #include "llvm/MC/MachineLocation.h"
     20 #include "llvm/Support/raw_ostream.h"
     21 #include "llvm/Support/Dwarf.h"
     22 #include <vector>
     23 
     24 namespace llvm {
     25   class MCContext;
     26   class MCObjectWriter;
     27   class MCSection;
     28   class MCStreamer;
     29   class MCSymbol;
     30   class SourceMgr;
     31   class SMLoc;
     32 
     33   /// MCDwarfFile - Instances of this class represent the name of the dwarf
     34   /// .file directive and its associated dwarf file number in the MC file,
     35   /// and MCDwarfFile's are created and unique'd by the MCContext class where
     36   /// the file number for each is its index into the vector of DwarfFiles (note
     37   /// index 0 is not used and not a valid dwarf file number).
     38   class MCDwarfFile {
     39     // Name - the base name of the file without its directory path.
     40     // The StringRef references memory allocated in the MCContext.
     41     StringRef Name;
     42 
     43     // DirIndex - the index into the list of directory names for this file name.
     44     unsigned DirIndex;
     45 
     46   private:  // MCContext creates and uniques these.
     47     friend class MCContext;
     48     MCDwarfFile(StringRef name, unsigned dirIndex)
     49       : Name(name), DirIndex(dirIndex) {}
     50 
     51     MCDwarfFile(const MCDwarfFile&);       // DO NOT IMPLEMENT
     52     void operator=(const MCDwarfFile&); // DO NOT IMPLEMENT
     53   public:
     54     /// getName - Get the base name of this MCDwarfFile.
     55     StringRef getName() const { return Name; }
     56 
     57     /// getDirIndex - Get the dirIndex of this MCDwarfFile.
     58     unsigned getDirIndex() const { return DirIndex; }
     59 
     60 
     61     /// print - Print the value to the stream \arg OS.
     62     void print(raw_ostream &OS) const;
     63 
     64     /// dump - Print the value to stderr.
     65     void dump() const;
     66   };
     67 
     68   inline raw_ostream &operator<<(raw_ostream &OS, const MCDwarfFile &DwarfFile){
     69     DwarfFile.print(OS);
     70     return OS;
     71   }
     72 
     73   /// MCDwarfLoc - Instances of this class represent the information from a
     74   /// dwarf .loc directive.
     75   class MCDwarfLoc {
     76     // FileNum - the file number.
     77     unsigned FileNum;
     78     // Line - the line number.
     79     unsigned Line;
     80     // Column - the column position.
     81     unsigned Column;
     82     // Flags (see #define's below)
     83     unsigned Flags;
     84     // Isa
     85     unsigned Isa;
     86     // Discriminator
     87     unsigned Discriminator;
     88 
     89 // Flag that indicates the initial value of the is_stmt_start flag.
     90 #define DWARF2_LINE_DEFAULT_IS_STMT     1
     91 
     92 #define DWARF2_FLAG_IS_STMT        (1 << 0)
     93 #define DWARF2_FLAG_BASIC_BLOCK    (1 << 1)
     94 #define DWARF2_FLAG_PROLOGUE_END   (1 << 2)
     95 #define DWARF2_FLAG_EPILOGUE_BEGIN (1 << 3)
     96 
     97   private:  // MCContext manages these
     98     friend class MCContext;
     99     friend class MCLineEntry;
    100     MCDwarfLoc(unsigned fileNum, unsigned line, unsigned column, unsigned flags,
    101                unsigned isa, unsigned discriminator)
    102       : FileNum(fileNum), Line(line), Column(column), Flags(flags), Isa(isa),
    103         Discriminator(discriminator) {}
    104 
    105     // Allow the default copy constructor and assignment operator to be used
    106     // for an MCDwarfLoc object.
    107 
    108   public:
    109     /// getFileNum - Get the FileNum of this MCDwarfLoc.
    110     unsigned getFileNum() const { return FileNum; }
    111 
    112     /// getLine - Get the Line of this MCDwarfLoc.
    113     unsigned getLine() const { return Line; }
    114 
    115     /// getColumn - Get the Column of this MCDwarfLoc.
    116     unsigned getColumn() const { return Column; }
    117 
    118     /// getFlags - Get the Flags of this MCDwarfLoc.
    119     unsigned getFlags() const { return Flags; }
    120 
    121     /// getIsa - Get the Isa of this MCDwarfLoc.
    122     unsigned getIsa() const { return Isa; }
    123 
    124     /// getDiscriminator - Get the Discriminator of this MCDwarfLoc.
    125     unsigned getDiscriminator() const { return Discriminator; }
    126 
    127     /// setFileNum - Set the FileNum of this MCDwarfLoc.
    128     void setFileNum(unsigned fileNum) { FileNum = fileNum; }
    129 
    130     /// setLine - Set the Line of this MCDwarfLoc.
    131     void setLine(unsigned line) { Line = line; }
    132 
    133     /// setColumn - Set the Column of this MCDwarfLoc.
    134     void setColumn(unsigned column) { Column = column; }
    135 
    136     /// setFlags - Set the Flags of this MCDwarfLoc.
    137     void setFlags(unsigned flags) { Flags = flags; }
    138 
    139     /// setIsa - Set the Isa of this MCDwarfLoc.
    140     void setIsa(unsigned isa) { Isa = isa; }
    141 
    142     /// setDiscriminator - Set the Discriminator of this MCDwarfLoc.
    143     void setDiscriminator(unsigned discriminator) {
    144       Discriminator = discriminator;
    145     }
    146   };
    147 
    148   /// MCLineEntry - Instances of this class represent the line information for
    149   /// the dwarf line table entries.  Which is created after a machine
    150   /// instruction is assembled and uses an address from a temporary label
    151   /// created at the current address in the current section and the info from
    152   /// the last .loc directive seen as stored in the context.
    153   class MCLineEntry : public MCDwarfLoc {
    154     MCSymbol *Label;
    155 
    156   private:
    157     // Allow the default copy constructor and assignment operator to be used
    158     // for an MCLineEntry object.
    159 
    160   public:
    161     // Constructor to create an MCLineEntry given a symbol and the dwarf loc.
    162     MCLineEntry(MCSymbol *label, const MCDwarfLoc loc) : MCDwarfLoc(loc),
    163                 Label(label) {}
    164 
    165     MCSymbol *getLabel() const { return Label; }
    166 
    167     // This is called when an instruction is assembled into the specified
    168     // section and if there is information from the last .loc directive that
    169     // has yet to have a line entry made for it is made.
    170     static void Make(MCStreamer *MCOS, const MCSection *Section);
    171   };
    172 
    173   /// MCLineSection - Instances of this class represent the line information
    174   /// for a section where machine instructions have been assembled after seeing
    175   /// .loc directives.  This is the information used to build the dwarf line
    176   /// table for a section.
    177   class MCLineSection {
    178 
    179   private:
    180     MCLineSection(const MCLineSection&);  // DO NOT IMPLEMENT
    181     void operator=(const MCLineSection&); // DO NOT IMPLEMENT
    182 
    183   public:
    184     // Constructor to create an MCLineSection with an empty MCLineEntries
    185     // vector.
    186     MCLineSection() {}
    187 
    188     // addLineEntry - adds an entry to this MCLineSection's line entries
    189     void addLineEntry(const MCLineEntry &LineEntry) {
    190       MCLineEntries.push_back(LineEntry);
    191     }
    192 
    193     typedef std::vector<MCLineEntry> MCLineEntryCollection;
    194     typedef MCLineEntryCollection::iterator iterator;
    195     typedef MCLineEntryCollection::const_iterator const_iterator;
    196 
    197   private:
    198     MCLineEntryCollection MCLineEntries;
    199 
    200   public:
    201     const MCLineEntryCollection *getMCLineEntries() const {
    202       return &MCLineEntries;
    203     }
    204   };
    205 
    206   class MCDwarfFileTable {
    207   public:
    208     //
    209     // This emits the Dwarf file and the line tables.
    210     //
    211     static const MCSymbol *Emit(MCStreamer *MCOS);
    212   };
    213 
    214   class MCDwarfLineAddr {
    215   public:
    216     /// Utility function to encode a Dwarf pair of LineDelta and AddrDeltas.
    217     static void Encode(int64_t LineDelta, uint64_t AddrDelta, raw_ostream &OS);
    218 
    219     /// Utility function to emit the encoding to a streamer.
    220     static void Emit(MCStreamer *MCOS,
    221                      int64_t LineDelta,uint64_t AddrDelta);
    222 
    223     /// Utility function to write the encoding to an object writer.
    224     static void Write(MCObjectWriter *OW,
    225                       int64_t LineDelta, uint64_t AddrDelta);
    226   };
    227 
    228   class MCGenDwarfInfo {
    229   public:
    230     //
    231     // When generating dwarf for assembly source files this emits the Dwarf
    232     // sections.
    233     //
    234     static void Emit(MCStreamer *MCOS, const MCSymbol *LineSectionSymbol);
    235   };
    236 
    237   // When generating dwarf for assembly source files this is the info that is
    238   // needed to be gathered for each symbol that will have a dwarf label.
    239   class MCGenDwarfLabelEntry {
    240   private:
    241     // Name of the symbol without a leading underbar, if any.
    242     StringRef Name;
    243     // The dwarf file number this symbol is in.
    244     unsigned FileNumber;
    245     // The line number this symbol is at.
    246     unsigned LineNumber;
    247     // The low_pc for the dwarf label is taken from this symbol.
    248     MCSymbol *Label;
    249 
    250   public:
    251     MCGenDwarfLabelEntry(StringRef name, unsigned fileNumber,
    252                          unsigned lineNumber, MCSymbol *label) :
    253       Name(name), FileNumber(fileNumber), LineNumber(lineNumber), Label(label){}
    254 
    255     StringRef getName() const { return Name; }
    256     unsigned getFileNumber() const { return FileNumber; }
    257     unsigned getLineNumber() const { return LineNumber; }
    258     MCSymbol *getLabel() const { return Label; }
    259 
    260     // This is called when label is created when we are generating dwarf for
    261     // assembly source files.
    262     static void Make(MCSymbol *Symbol, MCStreamer *MCOS, SourceMgr &SrcMgr,
    263                      SMLoc &Loc);
    264   };
    265 
    266   class MCCFIInstruction {
    267   public:
    268     enum OpType { SameValue, RememberState, RestoreState, Move, RelMove, Escape,
    269                   Restore};
    270   private:
    271     OpType Operation;
    272     MCSymbol *Label;
    273     // Move to & from location.
    274     MachineLocation Destination;
    275     MachineLocation Source;
    276     std::vector<char> Values;
    277   public:
    278     MCCFIInstruction(OpType Op, MCSymbol *L)
    279       : Operation(Op), Label(L) {
    280       assert(Op == RememberState || Op == RestoreState);
    281     }
    282     MCCFIInstruction(OpType Op, MCSymbol *L, unsigned Register)
    283       : Operation(Op), Label(L), Destination(Register) {
    284       assert(Op == SameValue || Op == Restore);
    285     }
    286     MCCFIInstruction(MCSymbol *L, const MachineLocation &D,
    287                      const MachineLocation &S)
    288       : Operation(Move), Label(L), Destination(D), Source(S) {
    289     }
    290     MCCFIInstruction(OpType Op, MCSymbol *L, const MachineLocation &D,
    291                      const MachineLocation &S)
    292       : Operation(Op), Label(L), Destination(D), Source(S) {
    293       assert(Op == RelMove);
    294     }
    295     MCCFIInstruction(OpType Op, MCSymbol *L, StringRef Vals)
    296       : Operation(Op), Label(L), Values(Vals.begin(), Vals.end()) {
    297       assert(Op == Escape);
    298     }
    299     OpType getOperation() const { return Operation; }
    300     MCSymbol *getLabel() const { return Label; }
    301     const MachineLocation &getDestination() const { return Destination; }
    302     const MachineLocation &getSource() const { return Source; }
    303     const StringRef getValues() const {
    304       return StringRef(&Values[0], Values.size());
    305     }
    306   };
    307 
    308   struct MCDwarfFrameInfo {
    309     MCDwarfFrameInfo() : Begin(0), End(0), Personality(0), Lsda(0),
    310                          Function(0), Instructions(), PersonalityEncoding(),
    311                          LsdaEncoding(0), CompactUnwindEncoding(0),
    312                          IsSignalFrame(false) {}
    313     MCSymbol *Begin;
    314     MCSymbol *End;
    315     const MCSymbol *Personality;
    316     const MCSymbol *Lsda;
    317     const MCSymbol *Function;
    318     std::vector<MCCFIInstruction> Instructions;
    319     unsigned PersonalityEncoding;
    320     unsigned LsdaEncoding;
    321     uint32_t CompactUnwindEncoding;
    322     bool IsSignalFrame;
    323   };
    324 
    325   class MCDwarfFrameEmitter {
    326   public:
    327     //
    328     // This emits the frame info section.
    329     //
    330     static void Emit(MCStreamer &streamer, bool usingCFI,
    331                      bool isEH);
    332     static void EmitAdvanceLoc(MCStreamer &Streamer, uint64_t AddrDelta);
    333     static void EncodeAdvanceLoc(uint64_t AddrDelta, raw_ostream &OS);
    334   };
    335 } // end namespace llvm
    336 
    337 #endif
    338