MCCodeEmitter.h revision 9754ab010e3897457e75cbf0aa74e276fc944174 
1//===-- llvm/MC/MCCodeEmitter.h - Instruction Encoding ----------*- 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#ifndef LLVM_MC_MCCODEEMITTER_H
11#define LLVM_MC_MCCODEEMITTER_H
12
13#include "llvm/MC/MCFixup.h"
14
15#include <cassert>
16
17namespace llvm {
18class MCExpr;
19class MCInst;
20class raw_ostream;
21template<typename T> class SmallVectorImpl;
22
23/// MCFixupKindInfo - Target independent information on a fixup kind.
24struct MCFixupKindInfo {
25  enum FixupKindFlags {
26    /// Is this fixup kind PCrelative? This is used by the assembler backend to
27    /// evaluate fixup values in a target independent manner when possible.
28    FKF_IsPCRel = (1 << 0),
29
30    /// Should this fixup kind force a 4-byte aligned effective PC value?
31    FKF_IsAlignedDownTo32Bits = (1 << 1)
32  };
33
34  /// A target specific name for the fixup kind. The names will be unique for
35  /// distinct kinds on any given target.
36  const char *Name;
37
38  /// The bit offset to write the relocation into.
39  unsigned TargetOffset;
40
41  /// The number of bits written by this fixup. The bits are assumed to be
42  /// contiguous.
43  unsigned TargetSize;
44
45  /// Flags describing additional information on this fixup kind.
46  unsigned Flags;
47};
48
49/// MCCodeEmitter - Generic instruction encoding interface.
50class MCCodeEmitter {
51private:
52  MCCodeEmitter(const MCCodeEmitter &);   // DO NOT IMPLEMENT
53  void operator=(const MCCodeEmitter &);  // DO NOT IMPLEMENT
54protected: // Can only create subclasses.
55  MCCodeEmitter();
56
57public:
58  virtual ~MCCodeEmitter();
59
60  /// @name Target Independent Fixup Information
61  /// @{
62
63  /// getNumFixupKinds - Get the number of target specific fixup kinds.
64  virtual unsigned getNumFixupKinds() const = 0;
65
66  /// getFixupKindInfo - Get information on a fixup kind.
67  virtual const MCFixupKindInfo &getFixupKindInfo(MCFixupKind Kind) const;
68
69  /// @}
70
71  /// EncodeInstruction - Encode the given \arg Inst to bytes on the output
72  /// stream \arg OS.
73  virtual void EncodeInstruction(const MCInst &Inst, raw_ostream &OS,
74                                 SmallVectorImpl<MCFixup> &Fixups) const = 0;
75};
76
77} // End llvm namespace
78
79#endif
80