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