MCValue.h revision 1f6efa3996dd1929fbc129203ce5009b620e6969 
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 MCAsmInfo;
23class MCSymbol;
24class MCSymbolRefExpr;
25class raw_ostream;
26
27/// MCValue - This represents an "assembler immediate".  In its most general
28/// form, this can hold "SymbolA - SymbolB + imm64".  Not all targets supports
29/// relocations of this general form, but we need to represent this anyway.
30///
31/// In the general form, SymbolB can only be defined if SymbolA is, and both
32/// must be in the same (non-external) section. The latter constraint is not
33/// enforced, since a symbol's section may not be known at construction.
34///
35/// Note that this class must remain a simple POD value class, because we need
36/// it to live in unions etc.
37class MCValue {
38  const MCSymbolRefExpr *SymA, *SymB;
39  int64_t Cst;
40public:
41
42  int64_t getConstant() const { return Cst; }
43  const MCSymbolRefExpr *getSymA() const { return SymA; }
44  const MCSymbolRefExpr *getSymB() const { return SymB; }
45
46  /// isAbsolute - Is this an absolute (as opposed to relocatable) value.
47  bool isAbsolute() const { return !SymA && !SymB; }
48
49  /// getAssociatedSection - For relocatable values, return the section the
50  /// value is associated with.
51  ///
52  /// @result - The value's associated section, or null for external or constant
53  /// values.
54  //
55  // FIXME: Switch to a tagged section, so this can return the tagged section
56  // value.
57  const MCSection *getAssociatedSection() const;
58
59  /// print - Print the value to the stream \arg OS.
60  void print(raw_ostream &OS, const MCAsmInfo *MAI) const;
61
62  /// dump - Print the value to stderr.
63  void dump() const;
64
65  static MCValue get(const MCSymbolRefExpr *SymA, const MCSymbolRefExpr *SymB=0,
66                     int64_t Val = 0) {
67    MCValue R;
68    assert((!SymB || SymA) && "Invalid relocatable MCValue!");
69    R.Cst = Val;
70    R.SymA = SymA;
71    R.SymB = SymB;
72    return R;
73  }
74
75  static MCValue get(int64_t Val) {
76    MCValue R;
77    R.Cst = Val;
78    R.SymA = 0;
79    R.SymB = 0;
80    return R;
81  }
82
83};
84
85} // end namespace llvm
86
87#endif
88