MCValue.h revision 8906ff1b9dfde28f1ff00706643ca10843b26e01 
1//===-- llvm/MC/MCValue.h - MCValue class -----------------------*- 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 file contains the declaration of the MCValue class.
11//
12//===----------------------------------------------------------------------===//
13
14#ifndef LLVM_MC_MCVALUE_H
15#define LLVM_MC_MCVALUE_H
16
17#include "llvm/Support/DataTypes.h"
18#include "llvm/MC/MCSymbol.h"
19#include <cassert>
20
21namespace llvm {
22class MCSymbol;
23class raw_ostream;
24
25/// MCValue - This represents an "assembler immediate".  In its most general
26/// form, this can hold "SymbolA - SymbolB + imm64".  Not all targets supports
27/// relocations of this general form, but we need to represent this anyway.
28///
29/// In the general form, SymbolB can only be defined if SymbolA is, and both
30/// must be in the same (non-external) section. The latter constraint is not
31/// enforced, since a symbol's section may not be known at construction.
32///
33/// Note that this class must remain a simple POD value class, because we need
34/// it to live in unions etc.
35class MCValue {
36  MCSymbol *SymA, *SymB;
37  int64_t Cst;
38public:
39
40  int64_t getConstant() const { return Cst; }
41  MCSymbol *getSymA() const { return SymA; }
42  MCSymbol *getSymB() const { return SymB; }
43
44  /// isAbsolute - Is this an absolute (as opposed to relocatable) value.
45  bool isAbsolute() const { return !SymA && !SymB; }
46
47  /// getAssociatedSection - For relocatable values, return the section the
48  /// value is associated with.
49  ///
50  /// @result - The value's associated section, or null for external or constant
51  /// values.
52  //
53  // FIXME: Switch to a tagged section, so this can return the tagged section
54  // value.
55  const MCSection *getAssociatedSection() const;
56
57  /// print - Print the value to the stream \arg OS.
58  void print(raw_ostream &OS) const;
59
60  /// dump - Print the value to stderr.
61  void dump() const;
62
63  static MCValue get(MCSymbol *SymA, MCSymbol *SymB = 0, int64_t Val = 0) {
64    MCValue R;
65    assert((!SymB || SymA) && "Invalid relocatable MCValue!");
66    R.Cst = Val;
67    R.SymA = SymA;
68    R.SymB = SymB;
69    return R;
70  }
71
72  static MCValue get(int64_t Val) {
73    MCValue R;
74    R.Cst = Val;
75    R.SymA = 0;
76    R.SymB = 0;
77    return R;
78  }
79
80};
81
82} // end namespace llvm
83
84#endif
85