1 //===-- llvm/CodeGen/DebugLocEntry.h - Entry in debug_loc list -*- C++ -*--===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 #ifndef LLVM_LIB_CODEGEN_ASMPRINTER_DEBUGLOCENTRY_H
10 #define LLVM_LIB_CODEGEN_ASMPRINTER_DEBUGLOCENTRY_H
11 
12 #include "DebugLocStream.h"
13 #include "llvm/Config/llvm-config.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 /// 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   /// 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() << "+0";
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   /// Create a location list entry for the range [\p Begin, \p End).
104   ///
105   /// \param Vals One or more values describing (parts of) the variable.
106   DebugLocEntry(const MCSymbol *Begin, const MCSymbol *End,
107                 ArrayRef<Value> Vals)
108       : Begin(Begin), End(End) {
109     addValues(Vals);
110   }
111 
112   /// Attempt to merge this DebugLocEntry with Next and return
113   /// true if the merge was successful. Entries can be merged if they
114   /// share the same Loc/Constant and if Next immediately follows this
115   /// Entry.
116   bool MergeRanges(const DebugLocEntry &Next) {
117     // If this and Next are describing the same variable, merge them.
118     if ((End == Next.Begin && Values == Next.Values)) {
119       End = Next.End;
120       return true;
121     }
122     return false;
123   }
124 
125   const MCSymbol *getBeginSym() const { return Begin; }
126   const MCSymbol *getEndSym() const { return End; }
127   ArrayRef<Value> getValues() const { return Values; }
128   void addValues(ArrayRef<DebugLocEntry::Value> Vals) {
129     Values.append(Vals.begin(), Vals.end());
130     sortUniqueValues();
131     assert((Values.size() == 1 ||
132             all_of(Values,
133                    [](DebugLocEntry::Value V) { return V.isFragment(); })) &&
134            "must either have a single value or multiple pieces");
135   }
136 
137   // Sort the pieces by offset.
138   // Remove any duplicate entries by dropping all but the first.
139   void sortUniqueValues() {
140     llvm::sort(Values);
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   /// Lower this entry into a DWARF expression.
150   void finalize(const AsmPrinter &AP,
151                 DebugLocStream::ListBuilder &List,
152                 const DIBasicType *BT,
153                 DwarfCompileUnit &TheCU);
154 };
155 
156 /// Compare two Values for equality.
157 inline bool operator==(const DebugLocEntry::Value &A,
158                        const DebugLocEntry::Value &B) {
159   if (A.EntryKind != B.EntryKind)
160     return false;
161 
162   if (A.Expression != B.Expression)
163     return false;
164 
165   switch (A.EntryKind) {
166   case DebugLocEntry::Value::E_Location:
167     return A.Loc == B.Loc;
168   case DebugLocEntry::Value::E_Integer:
169     return A.Constant.Int == B.Constant.Int;
170   case DebugLocEntry::Value::E_ConstantFP:
171     return A.Constant.CFP == B.Constant.CFP;
172   case DebugLocEntry::Value::E_ConstantInt:
173     return A.Constant.CIP == B.Constant.CIP;
174   }
175   llvm_unreachable("unhandled EntryKind");
176 }
177 
178 /// Compare two fragments based on their offset.
179 inline bool operator<(const DebugLocEntry::Value &A,
180                       const DebugLocEntry::Value &B) {
181   return A.getExpression()->getFragmentInfo()->OffsetInBits <
182          B.getExpression()->getFragmentInfo()->OffsetInBits;
183 }
184 
185 }
186 
187 #endif
188