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  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/ADT/StringExtras.h"
  22. #include "llvm/Bitstream/BitCodeEnums.h"
  23. #include "llvm/Support/DataTypes.h"
  24. #include "llvm/Support/ErrorHandling.h"
  25. #include <cassert>
  26.  
  27. namespace llvm {
  28. /// BitCodeAbbrevOp - This describes one or more operands in an abbreviation.
  29. /// This is actually a union of two different things:
  30. ///   1. It could be a literal integer value ("the operand is always 17").
  31. ///   2. It could be an encoding specification ("this operand encoded like so").
  32. ///
  33. class BitCodeAbbrevOp {
  34.   uint64_t Val;           // A literal value or data for an encoding.
  35.   bool IsLiteral : 1;     // Indicate whether this is a literal value or not.
  36.   unsigned Enc   : 3;     // The encoding to use.
  37. public:
  38.   enum Encoding {
  39.     Fixed = 1,  // A fixed width field, Val specifies number of bits.
  40.     VBR   = 2,  // A VBR field where Val specifies the width of each chunk.
  41.     Array = 3,  // A sequence of fields, next field species elt encoding.
  42.     Char6 = 4,  // A 6-bit fixed field which maps to [a-zA-Z0-9._].
  43.     Blob  = 5   // 32-bit aligned array of 8-bit characters.
  44.   };
  45.  
  46.   static bool isValidEncoding(uint64_t E) {
  47.     return E >= 1 && E <= 5;
  48.   }
  49.  
  50.   explicit BitCodeAbbrevOp(uint64_t V) :  Val(V), IsLiteral(true) {}
  51.   explicit BitCodeAbbrevOp(Encoding E, uint64_t Data = 0)
  52.     : Val(Data), IsLiteral(false), Enc(E) {}
  53.  
  54.   bool isLiteral() const  { return IsLiteral; }
  55.   bool isEncoding() const { return !IsLiteral; }
  56.  
  57.   // Accessors for literals.
  58.   uint64_t getLiteralValue() const { assert(isLiteral()); return Val; }
  59.  
  60.   // Accessors for encoding info.
  61.   Encoding getEncoding() const { assert(isEncoding()); return (Encoding)Enc; }
  62.   uint64_t getEncodingData() const {
  63.     assert(isEncoding() && hasEncodingData());
  64.     return Val;
  65.   }
  66.  
  67.   bool hasEncodingData() const { return hasEncodingData(getEncoding()); }
  68.   static bool hasEncodingData(Encoding E) {
  69.     switch (E) {
  70.     case Fixed:
  71.     case VBR:
  72.       return true;
  73.     case Array:
  74.     case Char6:
  75.     case Blob:
  76.       return false;
  77.     }
  78.     report_fatal_error("Invalid encoding");
  79.   }
  80.  
  81.   /// isChar6 - Return true if this character is legal in the Char6 encoding.
  82.   static bool isChar6(char C) { return isAlnum(C) || C == '.' || C == '_'; }
  83.   static unsigned EncodeChar6(char C) {
  84.     if (C >= 'a' && C <= 'z') return C-'a';
  85.     if (C >= 'A' && C <= 'Z') return C-'A'+26;
  86.     if (C >= '0' && C <= '9') return C-'0'+26+26;
  87.     if (C == '.')             return 62;
  88.     if (C == '_')             return 63;
  89.     llvm_unreachable("Not a value Char6 character!");
  90.   }
  91.  
  92.   static char DecodeChar6(unsigned V) {
  93.     assert((V & ~63) == 0 && "Not a Char6 encoded character!");
  94.     return "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789._"
  95.         [V];
  96.   }
  97.  
  98. };
  99.  
  100. /// BitCodeAbbrev - This class represents an abbreviation record.  An
  101. /// abbreviation allows a complex record that has redundancy to be stored in a
  102. /// specialized format instead of the fully-general, fully-vbr, format.
  103. class BitCodeAbbrev {
  104.   SmallVector<BitCodeAbbrevOp, 32> OperandList;
  105.  
  106. public:
  107.   BitCodeAbbrev() = default;
  108.  
  109.   explicit BitCodeAbbrev(std::initializer_list<BitCodeAbbrevOp> OperandList)
  110.       : OperandList(OperandList) {}
  111.  
  112.   unsigned getNumOperandInfos() const {
  113.     return static_cast<unsigned>(OperandList.size());
  114.   }
  115.   const BitCodeAbbrevOp &getOperandInfo(unsigned N) const {
  116.     return OperandList[N];
  117.   }
  118.  
  119.   void Add(const BitCodeAbbrevOp &OpInfo) {
  120.     OperandList.push_back(OpInfo);
  121.   }
  122. };
  123. } // namespace llvm
  124.  
  125. #endif
  126.