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      1 //===- BitCodes.h - Enum values for the bitcode format ----------*- 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 header Bitcode enum values.
     11 //
     12 // The enum values defined in this file should be considered permanent.  If
     13 // new features are added, they should have values added at the end of the
     14 // respective lists.
     15 //
     16 //===----------------------------------------------------------------------===//
     17 
     18 #ifndef LLVM_BITCODE_BITCODES_H
     19 #define LLVM_BITCODE_BITCODES_H
     20 
     21 #include "llvm/ADT/SmallVector.h"
     22 #include "llvm/Support/DataTypes.h"
     23 #include "llvm/Support/ErrorHandling.h"
     24 #include <cassert>
     25 
     26 namespace llvm {
     27 namespace bitc {
     28   enum StandardWidths {
     29     BlockIDWidth   = 8,  // We use VBR-8 for block IDs.
     30     CodeLenWidth   = 4,  // Codelen are VBR-4.
     31     BlockSizeWidth = 32  // BlockSize up to 2^32 32-bit words = 16GB per block.
     32   };
     33 
     34   // The standard abbrev namespace always has a way to exit a block, enter a
     35   // nested block, define abbrevs, and define an unabbreviated record.
     36   enum FixedAbbrevIDs {
     37     END_BLOCK = 0,  // Must be zero to guarantee termination for broken bitcode.
     38     ENTER_SUBBLOCK = 1,
     39 
     40     /// DEFINE_ABBREV - Defines an abbrev for the current block.  It consists
     41     /// of a vbr5 for # operand infos.  Each operand info is emitted with a
     42     /// single bit to indicate if it is a literal encoding.  If so, the value is
     43     /// emitted with a vbr8.  If not, the encoding is emitted as 3 bits followed
     44     /// by the info value as a vbr5 if needed.
     45     DEFINE_ABBREV = 2,
     46 
     47     // UNABBREV_RECORDs are emitted with a vbr6 for the record code, followed by
     48     // a vbr6 for the # operands, followed by vbr6's for each operand.
     49     UNABBREV_RECORD = 3,
     50 
     51     // This is not a code, this is a marker for the first abbrev assignment.
     52     FIRST_APPLICATION_ABBREV = 4
     53   };
     54 
     55   /// StandardBlockIDs - All bitcode files can optionally include a BLOCKINFO
     56   /// block, which contains metadata about other blocks in the file.
     57   enum StandardBlockIDs {
     58     /// BLOCKINFO_BLOCK is used to define metadata about blocks, for example,
     59     /// standard abbrevs that should be available to all blocks of a specified
     60     /// ID.
     61     BLOCKINFO_BLOCK_ID = 0,
     62 
     63     // Block IDs 1-7 are reserved for future expansion.
     64     FIRST_APPLICATION_BLOCKID = 8
     65   };
     66 
     67   /// BlockInfoCodes - The blockinfo block contains metadata about user-defined
     68   /// blocks.
     69   enum BlockInfoCodes {
     70     // DEFINE_ABBREV has magic semantics here, applying to the current SETBID'd
     71     // block, instead of the BlockInfo block.
     72 
     73     BLOCKINFO_CODE_SETBID        = 1, // SETBID: [blockid#]
     74     BLOCKINFO_CODE_BLOCKNAME     = 2, // BLOCKNAME: [name]
     75     BLOCKINFO_CODE_SETRECORDNAME = 3  // BLOCKINFO_CODE_SETRECORDNAME:
     76                                       //                             [id, name]
     77   };
     78 
     79 } // End bitc namespace
     80 
     81 /// BitCodeAbbrevOp - This describes one or more operands in an abbreviation.
     82 /// This is actually a union of two different things:
     83 ///   1. It could be a literal integer value ("the operand is always 17").
     84 ///   2. It could be an encoding specification ("this operand encoded like so").
     85 ///
     86 class BitCodeAbbrevOp {
     87   uint64_t Val;           // A literal value or data for an encoding.
     88   bool IsLiteral : 1;     // Indicate whether this is a literal value or not.
     89   unsigned Enc   : 3;     // The encoding to use.
     90 public:
     91   enum Encoding {
     92     Fixed = 1,  // A fixed width field, Val specifies number of bits.
     93     VBR   = 2,  // A VBR field where Val specifies the width of each chunk.
     94     Array = 3,  // A sequence of fields, next field species elt encoding.
     95     Char6 = 4,  // A 6-bit fixed field which maps to [a-zA-Z0-9._].
     96     Blob  = 5   // 32-bit aligned array of 8-bit characters.
     97   };
     98 
     99   explicit BitCodeAbbrevOp(uint64_t V) :  Val(V), IsLiteral(true) {}
    100   explicit BitCodeAbbrevOp(Encoding E, uint64_t Data = 0)
    101     : Val(Data), IsLiteral(false), Enc(E) {}
    102 
    103   bool isLiteral() const  { return IsLiteral; }
    104   bool isEncoding() const { return !IsLiteral; }
    105 
    106   // Accessors for literals.
    107   uint64_t getLiteralValue() const { assert(isLiteral()); return Val; }
    108 
    109   // Accessors for encoding info.
    110   Encoding getEncoding() const { assert(isEncoding()); return (Encoding)Enc; }
    111   uint64_t getEncodingData() const {
    112     assert(isEncoding() && hasEncodingData());
    113     return Val;
    114   }
    115 
    116   bool hasEncodingData() const { return hasEncodingData(getEncoding()); }
    117   static bool hasEncodingData(Encoding E) {
    118     switch (E) {
    119     case Fixed:
    120     case VBR:
    121       return true;
    122     case Array:
    123     case Char6:
    124     case Blob:
    125       return false;
    126     }
    127     llvm_unreachable("Invalid encoding");
    128   }
    129 
    130   /// isChar6 - Return true if this character is legal in the Char6 encoding.
    131   static bool isChar6(char C) {
    132     if (C >= 'a' && C <= 'z') return true;
    133     if (C >= 'A' && C <= 'Z') return true;
    134     if (C >= '0' && C <= '9') return true;
    135     if (C == '.' || C == '_') return true;
    136     return false;
    137   }
    138   static unsigned EncodeChar6(char C) {
    139     if (C >= 'a' && C <= 'z') return C-'a';
    140     if (C >= 'A' && C <= 'Z') return C-'A'+26;
    141     if (C >= '0' && C <= '9') return C-'0'+26+26;
    142     if (C == '.')             return 62;
    143     if (C == '_')             return 63;
    144     llvm_unreachable("Not a value Char6 character!");
    145   }
    146 
    147   static char DecodeChar6(unsigned V) {
    148     assert((V & ~63) == 0 && "Not a Char6 encoded character!");
    149     if (V < 26)       return V+'a';
    150     if (V < 26+26)    return V-26+'A';
    151     if (V < 26+26+10) return V-26-26+'0';
    152     if (V == 62)      return '.';
    153     if (V == 63)      return '_';
    154     llvm_unreachable("Not a value Char6 character!");
    155   }
    156 
    157 };
    158 
    159 template <> struct isPodLike<BitCodeAbbrevOp> { static const bool value=true; };
    160 
    161 /// BitCodeAbbrev - This class represents an abbreviation record.  An
    162 /// abbreviation allows a complex record that has redundancy to be stored in a
    163 /// specialized format instead of the fully-general, fully-vbr, format.
    164 class BitCodeAbbrev {
    165   SmallVector<BitCodeAbbrevOp, 32> OperandList;
    166   unsigned char RefCount; // Number of things using this.
    167   ~BitCodeAbbrev() {}
    168 public:
    169   BitCodeAbbrev() : RefCount(1) {}
    170 
    171   void addRef() { ++RefCount; }
    172   void dropRef() { if (--RefCount == 0) delete this; }
    173 
    174   unsigned getNumOperandInfos() const {
    175     return static_cast<unsigned>(OperandList.size());
    176   }
    177   const BitCodeAbbrevOp &getOperandInfo(unsigned N) const {
    178     return OperandList[N];
    179   }
    180 
    181   void Add(const BitCodeAbbrevOp &OpInfo) {
    182     OperandList.push_back(OpInfo);
    183   }
    184 };
    185 } // End llvm namespace
    186 
    187 #endif
    188