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 isLocation() const { return EntryKind == E_Location; }
63     bool isInt() const { return EntryKind == E_Integer; }
64     bool isConstantFP() const { return EntryKind == E_ConstantFP; }
65     bool isConstantInt() const { return EntryKind == E_ConstantInt; }
66     int64_t getInt() const { return Constant.Int; }
67     const ConstantFP *getConstantFP() const { return Constant.CFP; }
68     const ConstantInt *getConstantInt() const { return Constant.CIP; }
69     MachineLocation getLoc() const { return Loc; }
70     const MDNode *getVariableNode() const { return Variable; }
71     DIVariable getVariable() const { return DIVariable(Variable); }
72     bool isVariablePiece() const { return getVariable().isVariablePiece(); }
73     friend bool operator==(const Value &, const Value &);
74     friend bool operator<(const Value &, const Value &);
75   };
76 
77 private:
78   /// A nonempty list of locations/constants belonging to this entry,
79   /// sorted by offset.
80   SmallVector<Value, 1> Values;
81 
82 public:
83   DebugLocEntry(const MCSymbol *B, const MCSymbol *E, Value Val)
84       : Begin(B), End(E) {
85     Values.push_back(std::move(Val));
86   }
87 
88   /// \brief If this and Next are describing different pieces of the same
89   // variable, merge them by appending Next's values to the current
90   // list of values.
91   // Return true if the merge was successful.
92   bool MergeValues(const DebugLocEntry &Next) {
93     if (Begin == Next.Begin && Values.size() > 0 && Next.Values.size() > 0) {
94       DIVariable Var(Values[0].Variable);
95       DIVariable NextVar(Next.Values[0].Variable);
96       if (Var.getName() == NextVar.getName() &&
97           Var.isVariablePiece() && NextVar.isVariablePiece()) {
98         addValues(Next.Values);
99         End = Next.End;
100         return true;
101       }
102     }
103     return false;
104   }
105 
106   /// \brief Attempt to merge this DebugLocEntry with Next and return
107   /// true if the merge was successful. Entries can be merged if they
108   /// share the same Loc/Constant and if Next immediately follows this
109   /// Entry.
110   bool MergeRanges(const DebugLocEntry &Next) {
111     // If this and Next are describing the same variable, merge them.
112     if ((End == Next.Begin && Values == Next.Values)) {
113       End = Next.End;
114       return true;
115     }
116     return false;
117   }
118 
119   const MCSymbol *getBeginSym() const { return Begin; }
120   const MCSymbol *getEndSym() const { return End; }
121   const ArrayRef<Value> getValues() const { return Values; }
122   void addValues(ArrayRef<DebugLocEntry::Value> Vals) {
123     Values.append(Vals.begin(), Vals.end());
124     sortUniqueValues();
125     assert(std::all_of(Values.begin(), Values.end(), [](DebugLocEntry::Value V){
126           return V.isVariablePiece();
127         }) && "value must be a piece");
128   }
129 
130   // Sort the pieces by offset.
131   // Remove any duplicate entries by dropping all but the first.
132   void sortUniqueValues() {
133     std::sort(Values.begin(), Values.end());
134     Values.erase(std::unique(Values.begin(), Values.end(),
135                              [](const Value &A, const Value &B) {
136                                return A.getVariable() == B.getVariable();
137                                }), Values.end());
138   }
139 };
140 
141 /// Compare two Values for equality.
142 inline bool operator==(const DebugLocEntry::Value &A,
143                        const DebugLocEntry::Value &B) {
144   if (A.EntryKind != B.EntryKind)
145     return false;
146 
147   if (A.getVariable() != B.getVariable())
148     return false;
149 
150   switch (A.EntryKind) {
151   case DebugLocEntry::Value::E_Location:
152     return A.Loc == B.Loc;
153   case DebugLocEntry::Value::E_Integer:
154     return A.Constant.Int == B.Constant.Int;
155   case DebugLocEntry::Value::E_ConstantFP:
156     return A.Constant.CFP == B.Constant.CFP;
157   case DebugLocEntry::Value::E_ConstantInt:
158     return A.Constant.CIP == B.Constant.CIP;
159   }
160   llvm_unreachable("unhandled EntryKind");
161 }
162 
163 /// Compare two pieces based on their offset.
164 inline bool operator<(const DebugLocEntry::Value &A,
165                       const DebugLocEntry::Value &B) {
166   return A.getVariable().getPieceOffset() < B.getVariable().getPieceOffset();
167 }
168 
169 }
170 
171 #endif
172