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/IR/Constants.h"
15 #include "llvm/IR/DebugInfo.h"
16 #include "llvm/MC/MCSymbol.h"
17 #include "llvm/MC/MachineLocation.h"
18 #include "llvm/Support/Debug.h"
19 
20 namespace llvm {
21 class AsmPrinter;
22 
23 /// \brief This struct describes location entries emitted in the .debug_loc
24 /// section.
25 class DebugLocEntry {
26   /// Begin and end symbols for the address range that this location is valid.
27   const MCSymbol *Begin;
28   const MCSymbol *End;
29 
30 public:
31   /// \brief A single location or constant.
32   struct Value {
33     Value(const DIExpression *Expr, int64_t i)
34         : Expression(Expr), EntryKind(E_Integer) {
35       Constant.Int = i;
36     }
37     Value(const DIExpression *Expr, const ConstantFP *CFP)
38         : Expression(Expr), EntryKind(E_ConstantFP) {
39       Constant.CFP = CFP;
40     }
41     Value(const DIExpression *Expr, const ConstantInt *CIP)
42         : Expression(Expr), EntryKind(E_ConstantInt) {
43       Constant.CIP = CIP;
44     }
45     Value(const DIExpression *Expr, MachineLocation Loc)
46         : Expression(Expr), EntryKind(E_Location), Loc(Loc) {
47       assert(cast<DIExpression>(Expr)->isValid());
48     }
49 
50     /// Any complex address location expression for this Value.
51     const DIExpression *Expression;
52 
53     /// Type of entry that this represents.
54     enum EntryType { E_Location, E_Integer, E_ConstantFP, E_ConstantInt };
55     enum EntryType EntryKind;
56 
57     /// Either a constant,
58     union {
59       int64_t Int;
60       const ConstantFP *CFP;
61       const ConstantInt *CIP;
62     } Constant;
63 
64     // Or a location in the machine frame.
65     MachineLocation Loc;
66 
67     bool isLocation() const { return EntryKind == E_Location; }
68     bool isInt() const { return EntryKind == E_Integer; }
69     bool isConstantFP() const { return EntryKind == E_ConstantFP; }
70     bool isConstantInt() const { return EntryKind == E_ConstantInt; }
71     int64_t getInt() const { return Constant.Int; }
72     const ConstantFP *getConstantFP() const { return Constant.CFP; }
73     const ConstantInt *getConstantInt() const { return Constant.CIP; }
74     MachineLocation getLoc() const { return Loc; }
75     bool isFragment() const { return getExpression()->isFragment(); }
76     const DIExpression *getExpression() const { return Expression; }
77     friend bool operator==(const Value &, const Value &);
78     friend bool operator<(const Value &, const Value &);
79 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
80     LLVM_DUMP_METHOD 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 #endif
95   };
96 
97 private:
98   /// A nonempty list of locations/constants belonging to this entry,
99   /// sorted by offset.
100   SmallVector<Value, 1> Values;
101 
102 public:
103   DebugLocEntry(const MCSymbol *B, const MCSymbol *E, Value Val)
104       : Begin(B), End(E) {
105     Values.push_back(std::move(Val));
106   }
107 
108   /// \brief If this and Next are describing different pieces of the same
109   /// variable, merge them by appending Next's values to the current
110   /// list of values.
111   /// Return true if the merge was successful.
112   bool MergeValues(const DebugLocEntry &Next);
113 
114   /// \brief Attempt to merge this DebugLocEntry with Next and return
115   /// true if the merge was successful. Entries can be merged if they
116   /// share the same Loc/Constant and if Next immediately follows this
117   /// Entry.
118   bool MergeRanges(const DebugLocEntry &Next) {
119     // If this and Next are describing the same variable, merge them.
120     if ((End == Next.Begin && Values == Next.Values)) {
121       End = Next.End;
122       return true;
123     }
124     return false;
125   }
126 
127   const MCSymbol *getBeginSym() const { return Begin; }
128   const MCSymbol *getEndSym() const { return End; }
129   ArrayRef<Value> getValues() const { return Values; }
130   void addValues(ArrayRef<DebugLocEntry::Value> Vals) {
131     Values.append(Vals.begin(), Vals.end());
132     sortUniqueValues();
133     assert(all_of(Values, [](DebugLocEntry::Value V) {
134           return V.isFragment();
135         }) && "value must be a piece");
136   }
137 
138   // \brief Sort the pieces by offset.
139   // Remove any duplicate entries by dropping all but the first.
140   void sortUniqueValues() {
141     std::sort(Values.begin(), Values.end());
142     Values.erase(
143         std::unique(
144             Values.begin(), Values.end(), [](const Value &A, const Value &B) {
145               return A.getExpression() == B.getExpression();
146             }),
147         Values.end());
148   }
149 
150   /// \brief Lower this entry into a DWARF expression.
151   void finalize(const AsmPrinter &AP, DebugLocStream::ListBuilder &List,
152                 const DIBasicType *BT);
153 };
154 
155 /// \brief Compare two Values for equality.
156 inline bool operator==(const DebugLocEntry::Value &A,
157                        const DebugLocEntry::Value &B) {
158   if (A.EntryKind != B.EntryKind)
159     return false;
160 
161   if (A.Expression != B.Expression)
162     return false;
163 
164   switch (A.EntryKind) {
165   case DebugLocEntry::Value::E_Location:
166     return A.Loc == B.Loc;
167   case DebugLocEntry::Value::E_Integer:
168     return A.Constant.Int == B.Constant.Int;
169   case DebugLocEntry::Value::E_ConstantFP:
170     return A.Constant.CFP == B.Constant.CFP;
171   case DebugLocEntry::Value::E_ConstantInt:
172     return A.Constant.CIP == B.Constant.CIP;
173   }
174   llvm_unreachable("unhandled EntryKind");
175 }
176 
177 /// Compare two fragments based on their offset.
178 inline bool operator<(const DebugLocEntry::Value &A,
179                       const DebugLocEntry::Value &B) {
180   return A.getExpression()->getFragmentInfo()->OffsetInBits <
181          B.getExpression()->getFragmentInfo()->OffsetInBits;
182 }
183 
184 }
185 
186 #endif
187