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/MC/MCExpr.h"
18 #include "llvm/MC/MCSymbol.h"
19 #include "llvm/Support/DataTypes.h"
20 #include <cassert>
21 
22 namespace llvm {
23 class MCAsmInfo;
24 class raw_ostream;
25 
26 /// MCValue - This represents an "assembler immediate".  In its most
27 /// general form, this can hold ":Kind:(SymbolA - SymbolB + imm64)".
28 /// Not all targets supports relocations of this general form, but we
29 /// need to represent this anyway.
30 ///
31 /// In general both SymbolA and SymbolB will also have a modifier
32 /// analogous to the top-level Kind. Current targets are not expected
33 /// to make use of both though. The choice comes down to whether
34 /// relocation modifiers apply to the closest symbol or the whole
35 /// expression.
36 ///
37 /// In the general form, SymbolB can only be defined if SymbolA is, and both
38 /// must be in the same (non-external) section. The latter constraint is not
39 /// enforced, since a symbol's section may not be known at construction.
40 ///
41 /// Note that this class must remain a simple POD value class, because we need
42 /// it to live in unions etc.
43 class MCValue {
44   const MCSymbolRefExpr *SymA, *SymB;
45   int64_t Cst;
46   uint32_t RefKind;
47 public:
48 
getConstant()49   int64_t getConstant() const { return Cst; }
getSymA()50   const MCSymbolRefExpr *getSymA() const { return SymA; }
getSymB()51   const MCSymbolRefExpr *getSymB() const { return SymB; }
getRefKind()52   uint32_t getRefKind() const { return RefKind; }
53 
54   /// isAbsolute - Is this an absolute (as opposed to relocatable) value.
isAbsolute()55   bool isAbsolute() const { return !SymA && !SymB; }
56 
57   /// print - Print the value to the stream \p OS.
58   void print(raw_ostream &OS) const;
59 
60   /// dump - Print the value to stderr.
61   void dump() const;
62 
63   MCSymbolRefExpr::VariantKind getAccessVariant() const;
64 
65   static MCValue get(const MCSymbolRefExpr *SymA,
66                      const MCSymbolRefExpr *SymB = nullptr,
67                      int64_t Val = 0, uint32_t RefKind = 0) {
68     MCValue R;
69     assert((!SymB || SymA) && "Invalid relocatable MCValue!");
70     R.Cst = Val;
71     R.SymA = SymA;
72     R.SymB = SymB;
73     R.RefKind = RefKind;
74     return R;
75   }
76 
get(int64_t Val)77   static MCValue get(int64_t Val) {
78     MCValue R;
79     R.Cst = Val;
80     R.SymA = nullptr;
81     R.SymB = nullptr;
82     R.RefKind = 0;
83     return R;
84   }
85 
86 };
87 
88 } // end namespace llvm
89 
90 #endif
91