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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 "llvm/Support/Compiler.h"
     23 #include <vector>
     24 
     25 namespace llvm {
     26   class MCContext;
     27   class MCObjectWriter;
     28   class MCSection;
     29   class MCStreamer;
     30   class MCSymbol;
     31   class SourceMgr;
     32   class SMLoc;
     33 
     34   /// MCDwarfFile - Instances of this class represent the name of the dwarf
     35   /// .file directive and its associated dwarf file number in the MC file,
     36   /// and MCDwarfFile's are created and unique'd by the MCContext class where
     37   /// the file number for each is its index into the vector of DwarfFiles (note
     38   /// index 0 is not used and not a valid dwarf file number).
     39   class MCDwarfFile {
     40     // Name - the base name of the file without its directory path.
     41     // The StringRef references memory allocated in the MCContext.
     42     StringRef Name;
     43 
     44     // DirIndex - the index into the list of directory names for this file name.
     45     unsigned DirIndex;
     46 
     47   private:  // MCContext creates and uniques these.
     48     friend class MCContext;
     49     MCDwarfFile(StringRef name, unsigned dirIndex)
     50       : Name(name), DirIndex(dirIndex) {}
     51 
     52     MCDwarfFile(const MCDwarfFile&) LLVM_DELETED_FUNCTION;
     53     void operator=(const MCDwarfFile&) LLVM_DELETED_FUNCTION;
     54   public:
     55     /// getName - Get the base name of this MCDwarfFile.
     56     StringRef getName() const { return Name; }
     57 
     58     /// getDirIndex - Get the dirIndex of this MCDwarfFile.
     59     unsigned getDirIndex() const { return DirIndex; }
     60 
     61 
     62     /// print - Print the value to the stream \arg OS.
     63     void print(raw_ostream &OS) const;
     64 
     65     /// dump - Print the value to stderr.
     66     void dump() const;
     67   };
     68 
     69   inline raw_ostream &operator<<(raw_ostream &OS, const MCDwarfFile &DwarfFile){
     70     DwarfFile.print(OS);
     71     return OS;
     72   }
     73 
     74   /// MCDwarfLoc - Instances of this class represent the information from a
     75   /// dwarf .loc directive.
     76   class MCDwarfLoc {
     77     // FileNum - the file number.
     78     unsigned FileNum;
     79     // Line - the line number.
     80     unsigned Line;
     81     // Column - the column position.
     82     unsigned Column;
     83     // Flags (see #define's below)
     84     unsigned Flags;
     85     // Isa
     86     unsigned Isa;
     87     // Discriminator
     88     unsigned Discriminator;
     89 
     90 // Flag that indicates the initial value of the is_stmt_start flag.
     91 #define DWARF2_LINE_DEFAULT_IS_STMT     1
     92 
     93 #define DWARF2_FLAG_IS_STMT        (1 << 0)
     94 #define DWARF2_FLAG_BASIC_BLOCK    (1 << 1)
     95 #define DWARF2_FLAG_PROLOGUE_END   (1 << 2)
     96 #define DWARF2_FLAG_EPILOGUE_BEGIN (1 << 3)
     97 
     98   private:  // MCContext manages these
     99     friend class MCContext;
    100     friend class MCLineEntry;
    101     MCDwarfLoc(unsigned fileNum, unsigned line, unsigned column, unsigned flags,
    102                unsigned isa, unsigned discriminator)
    103       : FileNum(fileNum), Line(line), Column(column), Flags(flags), Isa(isa),
    104         Discriminator(discriminator) {}
    105 
    106     // Allow the default copy constructor and assignment operator to be used
    107     // for an MCDwarfLoc object.
    108 
    109   public:
    110     /// getFileNum - Get the FileNum of this MCDwarfLoc.
    111     unsigned getFileNum() const { return FileNum; }
    112 
    113     /// getLine - Get the Line of this MCDwarfLoc.
    114     unsigned getLine() const { return Line; }
    115 
    116     /// getColumn - Get the Column of this MCDwarfLoc.
    117     unsigned getColumn() const { return Column; }
    118 
    119     /// getFlags - Get the Flags of this MCDwarfLoc.
    120     unsigned getFlags() const { return Flags; }
    121 
    122     /// getIsa - Get the Isa of this MCDwarfLoc.
    123     unsigned getIsa() const { return Isa; }
    124 
    125     /// getDiscriminator - Get the Discriminator of this MCDwarfLoc.
    126     unsigned getDiscriminator() const { return Discriminator; }
    127 
    128     /// setFileNum - Set the FileNum of this MCDwarfLoc.
    129     void setFileNum(unsigned fileNum) { FileNum = fileNum; }
    130 
    131     /// setLine - Set the Line of this MCDwarfLoc.
    132     void setLine(unsigned line) { Line = line; }
    133 
    134     /// setColumn - Set the Column of this MCDwarfLoc.
    135     void setColumn(unsigned column) { Column = column; }
    136 
    137     /// setFlags - Set the Flags of this MCDwarfLoc.
    138     void setFlags(unsigned flags) { Flags = flags; }
    139 
    140     /// setIsa - Set the Isa of this MCDwarfLoc.
    141     void setIsa(unsigned isa) { Isa = isa; }
    142 
    143     /// setDiscriminator - Set the Discriminator of this MCDwarfLoc.
    144     void setDiscriminator(unsigned discriminator) {
    145       Discriminator = discriminator;
    146     }
    147   };
    148 
    149   /// MCLineEntry - Instances of this class represent the line information for
    150   /// the dwarf line table entries.  Which is created after a machine
    151   /// instruction is assembled and uses an address from a temporary label
    152   /// created at the current address in the current section and the info from
    153   /// the last .loc directive seen as stored in the context.
    154   class MCLineEntry : public MCDwarfLoc {
    155     MCSymbol *Label;
    156 
    157   private:
    158     // Allow the default copy constructor and assignment operator to be used
    159     // for an MCLineEntry object.
    160 
    161   public:
    162     // Constructor to create an MCLineEntry given a symbol and the dwarf loc.
    163     MCLineEntry(MCSymbol *label, const MCDwarfLoc loc) : MCDwarfLoc(loc),
    164                 Label(label) {}
    165 
    166     MCSymbol *getLabel() const { return Label; }
    167 
    168     // This is called when an instruction is assembled into the specified
    169     // section and if there is information from the last .loc directive that
    170     // has yet to have a line entry made for it is made.
    171     static void Make(MCStreamer *MCOS, const MCSection *Section);
    172   };
    173 
    174   /// MCLineSection - Instances of this class represent the line information
    175   /// for a section where machine instructions have been assembled after seeing
    176   /// .loc directives.  This is the information used to build the dwarf line
    177   /// table for a section.
    178   class MCLineSection {
    179 
    180   private:
    181     MCLineSection(const MCLineSection&);  // DO NOT IMPLEMENT
    182     void operator=(const MCLineSection&); // DO NOT IMPLEMENT
    183 
    184   public:
    185     // Constructor to create an MCLineSection with an empty MCLineEntries
    186     // vector.
    187     MCLineSection() {}
    188 
    189     // addLineEntry - adds an entry to this MCLineSection's line entries
    190     void addLineEntry(const MCLineEntry &LineEntry) {
    191       MCLineEntries.push_back(LineEntry);
    192     }
    193 
    194     typedef std::vector<MCLineEntry> MCLineEntryCollection;
    195     typedef MCLineEntryCollection::iterator iterator;
    196     typedef MCLineEntryCollection::const_iterator const_iterator;
    197 
    198   private:
    199     MCLineEntryCollection MCLineEntries;
    200 
    201   public:
    202     const MCLineEntryCollection *getMCLineEntries() const {
    203       return &MCLineEntries;
    204     }
    205   };
    206 
    207   class MCDwarfFileTable {
    208   public:
    209     //
    210     // This emits the Dwarf file and the line tables.
    211     //
    212     static const MCSymbol *Emit(MCStreamer *MCOS);
    213   };
    214 
    215   class MCDwarfLineAddr {
    216   public:
    217     /// Utility function to encode a Dwarf pair of LineDelta and AddrDeltas.
    218     static void Encode(int64_t LineDelta, uint64_t AddrDelta, raw_ostream &OS);
    219 
    220     /// Utility function to emit the encoding to a streamer.
    221     static void Emit(MCStreamer *MCOS,
    222                      int64_t LineDelta,uint64_t AddrDelta);
    223 
    224     /// Utility function to write the encoding to an object writer.
    225     static void Write(MCObjectWriter *OW,
    226                       int64_t LineDelta, uint64_t AddrDelta);
    227   };
    228 
    229   class MCGenDwarfInfo {
    230   public:
    231     //
    232     // When generating dwarf for assembly source files this emits the Dwarf
    233     // sections.
    234     //
    235     static void Emit(MCStreamer *MCOS, const MCSymbol *LineSectionSymbol);
    236   };
    237 
    238   // When generating dwarf for assembly source files this is the info that is
    239   // needed to be gathered for each symbol that will have a dwarf label.
    240   class MCGenDwarfLabelEntry {
    241   private:
    242     // Name of the symbol without a leading underbar, if any.
    243     StringRef Name;
    244     // The dwarf file number this symbol is in.
    245     unsigned FileNumber;
    246     // The line number this symbol is at.
    247     unsigned LineNumber;
    248     // The low_pc for the dwarf label is taken from this symbol.
    249     MCSymbol *Label;
    250 
    251   public:
    252     MCGenDwarfLabelEntry(StringRef name, unsigned fileNumber,
    253                          unsigned lineNumber, MCSymbol *label) :
    254       Name(name), FileNumber(fileNumber), LineNumber(lineNumber), Label(label){}
    255 
    256     StringRef getName() const { return Name; }
    257     unsigned getFileNumber() const { return FileNumber; }
    258     unsigned getLineNumber() const { return LineNumber; }
    259     MCSymbol *getLabel() const { return Label; }
    260 
    261     // This is called when label is created when we are generating dwarf for
    262     // assembly source files.
    263     static void Make(MCSymbol *Symbol, MCStreamer *MCOS, SourceMgr &SrcMgr,
    264                      SMLoc &Loc);
    265   };
    266 
    267   class MCCFIInstruction {
    268   public:
    269     enum OpType { SameValue, RememberState, RestoreState, Move, RelMove, Escape,
    270                   Restore};
    271   private:
    272     OpType Operation;
    273     MCSymbol *Label;
    274     // Move to & from location.
    275     MachineLocation Destination;
    276     MachineLocation Source;
    277     std::vector<char> Values;
    278   public:
    279     MCCFIInstruction(OpType Op, MCSymbol *L)
    280       : Operation(Op), Label(L) {
    281       assert(Op == RememberState || Op == RestoreState);
    282     }
    283     MCCFIInstruction(OpType Op, MCSymbol *L, unsigned Register)
    284       : Operation(Op), Label(L), Destination(Register) {
    285       assert(Op == SameValue || Op == Restore);
    286     }
    287     MCCFIInstruction(MCSymbol *L, const MachineLocation &D,
    288                      const MachineLocation &S)
    289       : Operation(Move), Label(L), Destination(D), Source(S) {
    290     }
    291     MCCFIInstruction(OpType Op, MCSymbol *L, const MachineLocation &D,
    292                      const MachineLocation &S)
    293       : Operation(Op), Label(L), Destination(D), Source(S) {
    294       assert(Op == RelMove);
    295     }
    296     MCCFIInstruction(OpType Op, MCSymbol *L, StringRef Vals)
    297       : Operation(Op), Label(L), Values(Vals.begin(), Vals.end()) {
    298       assert(Op == Escape);
    299     }
    300     OpType getOperation() const { return Operation; }
    301     MCSymbol *getLabel() const { return Label; }
    302     const MachineLocation &getDestination() const { return Destination; }
    303     const MachineLocation &getSource() const { return Source; }
    304     const StringRef getValues() const {
    305       return StringRef(&Values[0], Values.size());
    306     }
    307   };
    308 
    309   struct MCDwarfFrameInfo {
    310     MCDwarfFrameInfo() : Begin(0), End(0), Personality(0), Lsda(0),
    311                          Function(0), Instructions(), PersonalityEncoding(),
    312                          LsdaEncoding(0), CompactUnwindEncoding(0),
    313                          IsSignalFrame(false) {}
    314     MCSymbol *Begin;
    315     MCSymbol *End;
    316     const MCSymbol *Personality;
    317     const MCSymbol *Lsda;
    318     const MCSymbol *Function;
    319     std::vector<MCCFIInstruction> Instructions;
    320     unsigned PersonalityEncoding;
    321     unsigned LsdaEncoding;
    322     uint32_t CompactUnwindEncoding;
    323     bool IsSignalFrame;
    324   };
    325 
    326   class MCDwarfFrameEmitter {
    327   public:
    328     //
    329     // This emits the frame info section.
    330     //
    331     static void Emit(MCStreamer &streamer, bool usingCFI,
    332                      bool isEH);
    333     static void EmitAdvanceLoc(MCStreamer &Streamer, uint64_t AddrDelta);
    334     static void EncodeAdvanceLoc(uint64_t AddrDelta, raw_ostream &OS);
    335   };
    336 } // end namespace llvm
    337 
    338 #endif
    339