MCValue.h revision 10b318bcb39218d2ed525e4862c854bc8d1baf63 
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/System/DataTypes.h"
18#include "llvm/MC/MCSymbol.h"
19#include <cassert>
20
21namespace llvm {
22class MCSymbol;
23class MCAsmInfo;
24class raw_ostream;
25
26/// MCValue - This represents an "assembler immediate".  In its most general
27/// form, this can hold "SymbolA - SymbolB + imm64".  Not all targets supports
28/// relocations of this general form, but we need to represent this anyway.
29///
30/// In the general form, SymbolB can only be defined if SymbolA is, and both
31/// must be in the same (non-external) section. The latter constraint is not
32/// enforced, since a symbol's section may not be known at construction.
33///
34/// Note that this class must remain a simple POD value class, because we need
35/// it to live in unions etc.
36class MCValue {
37  const MCSymbol *SymA, *SymB;
38  int64_t Cst;
39public:
40
41  int64_t getConstant() const { return Cst; }
42  const MCSymbol *getSymA() const { return SymA; }
43  const MCSymbol *getSymB() const { return SymB; }
44
45  /// isAbsolute - Is this an absolute (as opposed to relocatable) value.
46  bool isAbsolute() const { return !SymA && !SymB; }
47
48  /// getAssociatedSection - For relocatable values, return the section the
49  /// value is associated with.
50  ///
51  /// @result - The value's associated section, or null for external or constant
52  /// values.
53  //
54  // FIXME: Switch to a tagged section, so this can return the tagged section
55  // value.
56  const MCSection *getAssociatedSection() const;
57
58  /// print - Print the value to the stream \arg OS.
59  void print(raw_ostream &OS, const MCAsmInfo *MAI) const;
60
61  /// dump - Print the value to stderr.
62  void dump() const;
63
64  static MCValue get(const MCSymbol *SymA, const MCSymbol *SymB = 0,
65                     int64_t Val = 0) {
66    MCValue R;
67    assert((!SymB || SymA) && "Invalid relocatable MCValue!");
68    R.Cst = Val;
69    R.SymA = SymA;
70    R.SymB = SymB;
71    return R;
72  }
73
74  static MCValue get(int64_t Val) {
75    MCValue R;
76    R.Cst = Val;
77    R.SymA = 0;
78    R.SymB = 0;
79    return R;
80  }
81
82};
83
84} // end namespace llvm
85
86#endif
87