include/llvm/Bitstream/BitCodes.h

   1 //===- BitCodes.h - Enum values for the bitstream format --------*- C++ -*-===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // This header defines bitstream enum values.
  10 //
  11 // The enum values defined in this file should be considered permanent.  If
  12 // new features are added, they should have values added at the end of the
  13 // respective lists.
  14 //
  15 //===----------------------------------------------------------------------===//
  16
  17 #ifndef LLVM_BITSTREAM_BITCODES_H
  18 #define LLVM_BITSTREAM_BITCODES_H
  19
  20 #include "llvm/ADT/SmallVector.h"
  21 #include "llvm/Support/DataTypes.h"
  22 #include "llvm/Support/ErrorHandling.h"
  23 #include <cassert>
  24
  25 namespace llvm {
  26 /// Offsets of the 32-bit fields of bitstream wrapper header.
  27 enum BitstreamWrapperHeader : unsigned {
  28   BWH_MagicField   = 0 * 4,
  29   BWH_VersionField = 1 * 4,
  30   BWH_OffsetField  = 2 * 4,
  31   BWH_SizeField    = 3 * 4,
  32   BWH_CPUTypeField = 4 * 4,
  33   BWH_HeaderSize   = 5 * 4
  34 };
  35
  36 namespace bitc {
  37   enum StandardWidths {
  38     BlockIDWidth   = 8,  // We use VBR-8 for block IDs.
  39     CodeLenWidth   = 4,  // Codelen are VBR-4.
  40     BlockSizeWidth = 32  // BlockSize up to 2^32 32-bit words = 16GB per block.
  41   };
  42
  43   // The standard abbrev namespace always has a way to exit a block, enter a
  44   // nested block, define abbrevs, and define an unabbreviated record.
  45   enum FixedAbbrevIDs {
  46     END_BLOCK = 0,  // Must be zero to guarantee termination for broken bitcode.
  47     ENTER_SUBBLOCK = 1,
  48
  49     /// DEFINE_ABBREV - Defines an abbrev for the current block.  It consists
  50     /// of a vbr5 for # operand infos.  Each operand info is emitted with a
  51     /// single bit to indicate if it is a literal encoding.  If so, the value is
  52     /// emitted with a vbr8.  If not, the encoding is emitted as 3 bits followed
  53     /// by the info value as a vbr5 if needed.
  54     DEFINE_ABBREV = 2,
  55
  56     // UNABBREV_RECORDs are emitted with a vbr6 for the record code, followed by
  57     // a vbr6 for the # operands, followed by vbr6's for each operand.
  58     UNABBREV_RECORD = 3,
  59
  60     // This is not a code, this is a marker for the first abbrev assignment.
  61     FIRST_APPLICATION_ABBREV = 4
  62   };
  63
  64   /// StandardBlockIDs - All bitcode files can optionally include a BLOCKINFO
  65   /// block, which contains metadata about other blocks in the file.
  66   enum StandardBlockIDs {
  67     /// BLOCKINFO_BLOCK is used to define metadata about blocks, for example,
  68     /// standard abbrevs that should be available to all blocks of a specified
  69     /// ID.
  70     BLOCKINFO_BLOCK_ID = 0,
  71
  72     // Block IDs 1-7 are reserved for future expansion.
  73     FIRST_APPLICATION_BLOCKID = 8
  74   };
  75
  76   /// BlockInfoCodes - The blockinfo block contains metadata about user-defined
  77   /// blocks.
  78   enum BlockInfoCodes {
  79     // DEFINE_ABBREV has magic semantics here, applying to the current SETBID'd
  80     // block, instead of the BlockInfo block.
  81
  82     BLOCKINFO_CODE_SETBID        = 1, // SETBID: [blockid#]
  83     BLOCKINFO_CODE_BLOCKNAME     = 2, // BLOCKNAME: [name]
  84     BLOCKINFO_CODE_SETRECORDNAME = 3  // BLOCKINFO_CODE_SETRECORDNAME:
  85                                       //                             [id, name]
  86   };
  87
  88 } // End bitc namespace
  89
  90 /// BitCodeAbbrevOp - This describes one or more operands in an abbreviation.
  91 /// This is actually a union of two different things:
  92 ///   1. It could be a literal integer value ("the operand is always 17").
  93 ///   2. It could be an encoding specification ("this operand encoded like so").
  94 ///
  95 class BitCodeAbbrevOp {
  96   uint64_t Val;           // A literal value or data for an encoding.
  97   bool IsLiteral : 1;     // Indicate whether this is a literal value or not.
  98   unsigned Enc   : 3;     // The encoding to use.
  99 public:
 100   enum Encoding {
 101     Fixed = 1,  // A fixed width field, Val specifies number of bits.
 102     VBR   = 2,  // A VBR field where Val specifies the width of each chunk.
 103     Array = 3,  // A sequence of fields, next field species elt encoding.
 104     Char6 = 4,  // A 6-bit fixed field which maps to [a-zA-Z0-9._].
 105     Blob  = 5   // 32-bit aligned array of 8-bit characters.
 106   };
 107
 108   explicit BitCodeAbbrevOp(uint64_t V) :  Val(V), IsLiteral(true) {}
 109   explicit BitCodeAbbrevOp(Encoding E, uint64_t Data = 0)
 110     : Val(Data), IsLiteral(false), Enc(E) {}
 111
 112   bool isLiteral() const  { return IsLiteral; }
 113   bool isEncoding() const { return !IsLiteral; }
 114
 115   // Accessors for literals.
 116   uint64_t getLiteralValue() const { assert(isLiteral()); return Val; }
 117
 118   // Accessors for encoding info.
 119   Encoding getEncoding() const { assert(isEncoding()); return (Encoding)Enc; }
 120   uint64_t getEncodingData() const {
 121     assert(isEncoding() && hasEncodingData());
 122     return Val;
 123   }
 124
 125   bool hasEncodingData() const { return hasEncodingData(getEncoding()); }
 126   static bool hasEncodingData(Encoding E) {
 127     switch (E) {
 128     case Fixed:
 129     case VBR:
 130       return true;
 131     case Array:
 132     case Char6:
 133     case Blob:
 134       return false;
 135     }
 136     report_fatal_error("Invalid encoding");
 137   }
 138
 139   /// isChar6 - Return true if this character is legal in the Char6 encoding.
 140   static bool isChar6(char C) {
 141     if (C >= 'a' && C <= 'z') return true;
 142     if (C >= 'A' && C <= 'Z') return true;
 143     if (C >= '0' && C <= '9') return true;
 144     if (C == '.' || C == '_') return true;
 145     return false;
 146   }
 147   static unsigned EncodeChar6(char C) {
 148     if (C >= 'a' && C <= 'z') return C-'a';
 149     if (C >= 'A' && C <= 'Z') return C-'A'+26;
 150     if (C >= '0' && C <= '9') return C-'0'+26+26;
 151     if (C == '.')             return 62;
 152     if (C == '_')             return 63;
 153     llvm_unreachable("Not a value Char6 character!");
 154   }
 155
 156   static char DecodeChar6(unsigned V) {
 157     assert((V & ~63) == 0 && "Not a Char6 encoded character!");
 158     return "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789._"
 159         [V];
 160   }
 161
 162 };
 163
 164 /// BitCodeAbbrev - This class represents an abbreviation record.  An
 165 /// abbreviation allows a complex record that has redundancy to be stored in a
 166 /// specialized format instead of the fully-general, fully-vbr, format.
 167 class BitCodeAbbrev {
 168   SmallVector<BitCodeAbbrevOp, 32> OperandList;
 169
 170 public:
 171   BitCodeAbbrev() = default;
 172
 173   explicit BitCodeAbbrev(std::initializer_list<BitCodeAbbrevOp> OperandList)
 174       : OperandList(OperandList) {}
 175
 176   unsigned getNumOperandInfos() const {
 177     return static_cast<unsigned>(OperandList.size());
 178   }
 179   const BitCodeAbbrevOp &getOperandInfo(unsigned N) const {
 180     return OperandList[N];
 181   }
 182
 183   void Add(const BitCodeAbbrevOp &OpInfo) {
 184     OperandList.push_back(OpInfo);
 185   }
 186 };
 187 } // End llvm namespace
 188
 189 #endif