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      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 
     49   int64_t getConstant() const { return Cst; }
     50   const MCSymbolRefExpr *getSymA() const { return SymA; }
     51   const MCSymbolRefExpr *getSymB() const { return SymB; }
     52   uint32_t getRefKind() const { return RefKind; }
     53 
     54   /// isAbsolute - Is this an absolute (as opposed to relocatable) value.
     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 MCAsmInfo *MAI) 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 
     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