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 LLVM_LIB_CODEGEN_ASMPRINTER_DEBUGLOCENTRY_H
11 #define LLVM_LIB_CODEGEN_ASMPRINTER_DEBUGLOCENTRY_H
12 
13 #include "DebugLocStream.h"
14 #include "llvm/ADT/SmallString.h"
15 #include "llvm/IR/Constants.h"
16 #include "llvm/IR/DebugInfo.h"
17 #include "llvm/MC/MCSymbol.h"
18 #include "llvm/MC/MachineLocation.h"
19 #include "llvm/Support/Debug.h"
20 
21 namespace llvm {
22 class AsmPrinter;
23 
24 /// \brief This struct describes location entries emitted in the .debug_loc
25 /// section.
26 class DebugLocEntry {
27   /// Begin and end symbols for the address range that this location is valid.
28   const MCSymbol *Begin;
29   const MCSymbol *End;
30 
31 public:
32   /// \brief A single location or constant.
33   struct Value {
34     Value(const DIExpression *Expr, int64_t i)
35         : Expression(Expr), EntryKind(E_Integer) {
36       Constant.Int = i;
37     }
38     Value(const DIExpression *Expr, const ConstantFP *CFP)
39         : Expression(Expr), EntryKind(E_ConstantFP) {
40       Constant.CFP = CFP;
41     }
42     Value(const DIExpression *Expr, const ConstantInt *CIP)
43         : Expression(Expr), EntryKind(E_ConstantInt) {
44       Constant.CIP = CIP;
45     }
46     Value(const DIExpression *Expr, MachineLocation Loc)
47         : Expression(Expr), EntryKind(E_Location), Loc(Loc) {
48       assert(cast<DIExpression>(Expr)->isValid());
49     }
50 
51     /// Any complex address location expression for this Value.
52     const DIExpression *Expression;
53 
54     /// Type of entry that this represents.
55     enum EntryType { E_Location, E_Integer, E_ConstantFP, E_ConstantInt };
56     enum EntryType EntryKind;
57 
58     /// Either a constant,
59     union {
60       int64_t Int;
61       const ConstantFP *CFP;
62       const ConstantInt *CIP;
63     } Constant;
64 
65     // Or a location in the machine frame.
66     MachineLocation Loc;
67 
68     bool isLocation() const { return EntryKind == E_Location; }
69     bool isInt() const { return EntryKind == E_Integer; }
70     bool isConstantFP() const { return EntryKind == E_ConstantFP; }
71     bool isConstantInt() const { return EntryKind == E_ConstantInt; }
72     int64_t getInt() const { return Constant.Int; }
73     const ConstantFP *getConstantFP() const { return Constant.CFP; }
74     const ConstantInt *getConstantInt() const { return Constant.CIP; }
75     MachineLocation getLoc() const { return Loc; }
76     bool isBitPiece() const { return getExpression()->isBitPiece(); }
77     const DIExpression *getExpression() const { return Expression; }
78     friend bool operator==(const Value &, const Value &);
79     friend bool operator<(const Value &, const Value &);
80     void dump() const {
81       if (isLocation()) {
82         llvm::dbgs() << "Loc = { reg=" << Loc.getReg() << " ";
83         if (Loc.isIndirect())
84           llvm::dbgs() << '+' << Loc.getOffset();
85         llvm::dbgs() << "} ";
86       }
87       else if (isConstantInt())
88         Constant.CIP->dump();
89       else if (isConstantFP())
90         Constant.CFP->dump();
91       if (Expression)
92         Expression->dump();
93     }
94   };
95 
96 private:
97   /// A nonempty list of locations/constants belonging to this entry,
98   /// sorted by offset.
99   SmallVector<Value, 1> Values;
100 
101 public:
102   DebugLocEntry(const MCSymbol *B, const MCSymbol *E, Value Val)
103       : Begin(B), End(E) {
104     Values.push_back(std::move(Val));
105   }
106 
107   /// \brief If this and Next are describing different pieces of the same
108   /// variable, merge them by appending Next's values to the current
109   /// list of values.
110   /// Return true if the merge was successful.
111   bool MergeValues(const DebugLocEntry &Next);
112 
113   /// \brief Attempt to merge this DebugLocEntry with Next and return
114   /// true if the merge was successful. Entries can be merged if they
115   /// share the same Loc/Constant and if Next immediately follows this
116   /// Entry.
117   bool MergeRanges(const DebugLocEntry &Next) {
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   ArrayRef<Value> getValues() const { return Values; }
129   void addValues(ArrayRef<DebugLocEntry::Value> Vals) {
130     Values.append(Vals.begin(), Vals.end());
131     sortUniqueValues();
132     assert(std::all_of(Values.begin(), Values.end(), [](DebugLocEntry::Value V){
133           return V.isBitPiece();
134         }) && "value must be a piece");
135   }
136 
137   // \brief Sort the pieces by offset.
138   // Remove any duplicate entries by dropping all but the first.
139   void sortUniqueValues() {
140     std::sort(Values.begin(), Values.end());
141     Values.erase(
142         std::unique(
143             Values.begin(), Values.end(), [](const Value &A, const Value &B) {
144               return A.getExpression() == B.getExpression();
145             }),
146         Values.end());
147   }
148 
149   /// \brief Lower this entry into a DWARF expression.
150   void finalize(const AsmPrinter &AP, DebugLocStream::ListBuilder &List,
151                 const DIBasicType *BT);
152 };
153 
154 /// \brief Compare two Values for equality.
155 inline bool operator==(const DebugLocEntry::Value &A,
156                        const DebugLocEntry::Value &B) {
157   if (A.EntryKind != B.EntryKind)
158     return false;
159 
160   if (A.Expression != B.Expression)
161     return false;
162 
163   switch (A.EntryKind) {
164   case DebugLocEntry::Value::E_Location:
165     return A.Loc == B.Loc;
166   case DebugLocEntry::Value::E_Integer:
167     return A.Constant.Int == B.Constant.Int;
168   case DebugLocEntry::Value::E_ConstantFP:
169     return A.Constant.CFP == B.Constant.CFP;
170   case DebugLocEntry::Value::E_ConstantInt:
171     return A.Constant.CIP == B.Constant.CIP;
172   }
173   llvm_unreachable("unhandled EntryKind");
174 }
175 
176 /// \brief Compare two pieces based on their offset.
177 inline bool operator<(const DebugLocEntry::Value &A,
178                       const DebugLocEntry::Value &B) {
179   return A.getExpression()->getBitPieceOffset() <
180          B.getExpression()->getBitPieceOffset();
181 }
182 
183 }
184 
185 #endif
186