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