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/IR/DebugInfo.h"
14 #include "llvm/MC/MachineLocation.h"
15 #include "llvm/MC/MCSymbol.h"
16 
17 namespace llvm {
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 public:
94   DebugLocEntry() : Begin(nullptr), End(nullptr) {}
95   DebugLocEntry(const MCSymbol *B, const MCSymbol *E, Value Val)
96       : Begin(B), End(E) {
97     Values.push_back(std::move(Val));
98   }
99 
100   /// \brief Attempt to merge this DebugLocEntry with Next and return
101   /// true if the merge was successful. Entries can be merged if they
102   /// share the same Loc/Constant and if Next immediately follows this
103   /// Entry.
104   bool Merge(const DebugLocEntry &Next) {
105     // If this and Next are describing different pieces of the same
106     // variable, merge them by appending next's values to the current
107     // list of values.
108     if (Begin == Next.Begin && Values.size() > 0 && Next.Values.size() > 0) {
109       DIVariable Var(Values[0].Variable);
110       DIVariable NextVar(Next.Values[0].Variable);
111       if (Var.getName() == NextVar.getName() &&
112           Var.isVariablePiece() && NextVar.isVariablePiece()) {
113         Values.append(Next.Values.begin(), Next.Values.end());
114         End = Next.End;
115         return true;
116       }
117     }
118     // If this and Next are describing the same variable, merge them.
119     if ((End == Next.Begin && Values == Next.Values)) {
120       End = Next.End;
121       return true;
122     }
123     return false;
124   }
125 
126   const MCSymbol *getBeginSym() const { return Begin; }
127   const MCSymbol *getEndSym() const { return End; }
128   const ArrayRef<Value> getValues() const { return Values; }
129   void addValue(Value Val) {
130     assert(DIVariable(Val.Variable).isVariablePiece() &&
131            "multi-value DebugLocEntries must be pieces");
132     Values.push_back(Val);
133   }
134 };
135 
136 }
137 #endif
138