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      1 //===-- llvm/CodeGen/DebugLocEntry.h - Entry in debug_loc list -*- 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 #ifndef CODEGEN_ASMPRINTER_DEBUGLOCENTRY_H__
     11 #define CODEGEN_ASMPRINTER_DEBUGLOCENTRY_H__
     12 #include "llvm/IR/Constants.h"
     13 #include "llvm/MC/MachineLocation.h"
     14 #include "llvm/MC/MCSymbol.h"
     15 
     16 namespace llvm {
     17 class DwarfCompileUnit;
     18 class MDNode;
     19 /// \brief This struct describes location entries emitted in the .debug_loc
     20 /// section.
     21 class DebugLocEntry {
     22   // Begin and end symbols for the address range that this location is valid.
     23   const MCSymbol *Begin;
     24   const MCSymbol *End;
     25 
     26 public:
     27   /// A single location or constant.
     28   struct Value {
     29     Value(const MDNode *Var, int64_t i)
     30       : Variable(Var), EntryKind(E_Integer) {
     31       Constant.Int = i;
     32     }
     33     Value(const MDNode *Var, const ConstantFP *CFP)
     34       : Variable(Var), EntryKind(E_ConstantFP) {
     35       Constant.CFP = CFP;
     36     }
     37     Value(const MDNode *Var, const ConstantInt *CIP)
     38       : Variable(Var), EntryKind(E_ConstantInt) {
     39       Constant.CIP = CIP;
     40     }
     41     Value(const MDNode *Var, MachineLocation Loc)
     42       : Variable(Var), EntryKind(E_Location), Loc(Loc) {
     43     }
     44 
     45     // The variable to which this location entry corresponds.
     46     const MDNode *Variable;
     47 
     48     // Type of entry that this represents.
     49     enum EntryType { E_Location, E_Integer, E_ConstantFP, E_ConstantInt };
     50     enum EntryType EntryKind;
     51 
     52     // Either a constant,
     53     union {
     54       int64_t Int;
     55       const ConstantFP *CFP;
     56       const ConstantInt *CIP;
     57     } Constant;
     58 
     59     // Or a location in the machine frame.
     60     MachineLocation Loc;
     61 
     62     bool operator==(const Value &other) const {
     63       if (EntryKind != other.EntryKind)
     64         return false;
     65 
     66       switch (EntryKind) {
     67       case E_Location:
     68         return Loc == other.Loc;
     69       case E_Integer:
     70         return Constant.Int == other.Constant.Int;
     71       case E_ConstantFP:
     72         return Constant.CFP == other.Constant.CFP;
     73       case E_ConstantInt:
     74         return Constant.CIP == other.Constant.CIP;
     75       }
     76       llvm_unreachable("unhandled EntryKind");
     77     }
     78 
     79     bool isLocation() const { return EntryKind == E_Location; }
     80     bool isInt() const { return EntryKind == E_Integer; }
     81     bool isConstantFP() const { return EntryKind == E_ConstantFP; }
     82     bool isConstantInt() const { return EntryKind == E_ConstantInt; }
     83     int64_t getInt() const { return Constant.Int; }
     84     const ConstantFP *getConstantFP() const { return Constant.CFP; }
     85     const ConstantInt *getConstantInt() const { return Constant.CIP; }
     86     MachineLocation getLoc() const { return Loc; }
     87     const MDNode *getVariable() const { return Variable; }
     88   };
     89 private:
     90   /// A list of locations/constants belonging to this entry.
     91   SmallVector<Value, 1> Values;
     92 
     93   /// The compile unit that this location entry is referenced by.
     94   const DwarfCompileUnit *Unit;
     95 
     96 public:
     97   DebugLocEntry() : Begin(nullptr), End(nullptr), Unit(nullptr) {}
     98   DebugLocEntry(const MCSymbol *B, const MCSymbol *E,
     99                 Value Val, const DwarfCompileUnit *U)
    100       : Begin(B), End(E), Unit(U) {
    101     Values.push_back(std::move(Val));
    102   }
    103 
    104   /// \brief Attempt to merge this DebugLocEntry with Next and return
    105   /// true if the merge was successful. Entries can be merged if they
    106   /// share the same Loc/Constant and if Next immediately follows this
    107   /// Entry.
    108   bool Merge(const DebugLocEntry &Next) {
    109     if ((End == Next.Begin && Values == Next.Values)) {
    110       End = Next.End;
    111       return true;
    112     }
    113     return false;
    114   }
    115   const MCSymbol *getBeginSym() const { return Begin; }
    116   const MCSymbol *getEndSym() const { return End; }
    117   const DwarfCompileUnit *getCU() const { return Unit; }
    118   const ArrayRef<Value> getValues() const { return Values; }
    119   void addValue(Value Val) { Values.push_back(Val); }
    120 };
    121 
    122 }
    123 #endif
    124