1 //===- llvm/MC/MCCodeEmitter.h - Instruction Encoding -----------*- 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 #ifndef LLVM_MC_MCCODEEMITTER_H
10 #define LLVM_MC_MCCODEEMITTER_H
11 
12 namespace llvm {
13 
14 class MCFixup;
15 class MCInst;
16 class MCSubtargetInfo;
17 class raw_ostream;
18 template<typename T> class SmallVectorImpl;
19 
20 /// MCCodeEmitter - Generic instruction encoding interface.
21 class MCCodeEmitter {
22 protected: // Can only create subclasses.
23   MCCodeEmitter();
24 
25   /// EncodeInstruction - Encode the given \p Inst to bytes on the output stream
26   /// \p OS. Allows for an implementation of encodeInstruction that uses streams
27   /// instead of a SmallVector.
28   virtual void encodeInstruction(const MCInst &Inst, raw_ostream &OS,
29                                  SmallVectorImpl<MCFixup> &Fixups,
30                                  const MCSubtargetInfo &STI) const {}
31 
32 public:
33   MCCodeEmitter(const MCCodeEmitter &) = delete;
34   MCCodeEmitter &operator=(const MCCodeEmitter &) = delete;
35   virtual ~MCCodeEmitter();
36 
37   /// Lifetime management
38   virtual void reset() {}
39 
40   /// Append the prefixes of given instruction to the code buffer.
41   ///
42   /// \param Inst a single low-level machine instruction.
43   /// \param CB code buffer
44   virtual void emitPrefix(const MCInst &Inst, SmallVectorImpl<char> &CB,
45                           const MCSubtargetInfo &STI) const {}
46   /// EncodeInstruction - Encode the given \p Inst to bytes and append to \p CB.
47   virtual void encodeInstruction(const MCInst &Inst, SmallVectorImpl<char> &CB,
48                                  SmallVectorImpl<MCFixup> &Fixups,
49                                  const MCSubtargetInfo &STI) const;
50 };
51 
52 } // end namespace llvm
53 
54 #endif // LLVM_MC_MCCODEEMITTER_H
55