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#include "llvm/ADT/SmallString.h"
13#include "llvm/IR/Constants.h"
14#include "llvm/IR/DebugInfo.h"
15#include "llvm/MC/MCSymbol.h"
16#include "llvm/MC/MachineLocation.h"
17
18namespace llvm {
19class AsmPrinter;
20class MDNode;
21/// \brief This struct describes location entries emitted in the .debug_loc
22/// section.
23class DebugLocEntry {
24  /// Begin and end symbols for the address range that this location is valid.
25  const MCSymbol *Begin;
26  const MCSymbol *End;
27
28public:
29  /// \brief A single location or constant.
30  struct Value {
31    Value(const MDNode *Var, const MDNode *Expr, int64_t i)
32        : Variable(Var), Expression(Expr), EntryKind(E_Integer) {
33      Constant.Int = i;
34    }
35    Value(const MDNode *Var, const MDNode *Expr, const ConstantFP *CFP)
36        : Variable(Var), Expression(Expr), EntryKind(E_ConstantFP) {
37      Constant.CFP = CFP;
38    }
39    Value(const MDNode *Var, const MDNode *Expr, const ConstantInt *CIP)
40        : Variable(Var), Expression(Expr), EntryKind(E_ConstantInt) {
41      Constant.CIP = CIP;
42    }
43    Value(const MDNode *Var, const MDNode *Expr, MachineLocation Loc)
44        : Variable(Var), Expression(Expr), EntryKind(E_Location), Loc(Loc) {
45      assert(isa<MDLocalVariable>(Var));
46      assert(cast<MDExpression>(Expr)->isValid());
47    }
48
49    /// The variable to which this location entry corresponds.
50    const MDNode *Variable;
51
52    /// Any complex address location expression for this Value.
53    const MDNode *Expression;
54
55    /// Type of entry that this represents.
56    enum EntryType { E_Location, E_Integer, E_ConstantFP, E_ConstantInt };
57    enum EntryType EntryKind;
58
59    /// Either a constant,
60    union {
61      int64_t Int;
62      const ConstantFP *CFP;
63      const ConstantInt *CIP;
64    } Constant;
65
66    // Or a location in the machine frame.
67    MachineLocation Loc;
68
69    bool isLocation() const { return EntryKind == E_Location; }
70    bool isInt() const { return EntryKind == E_Integer; }
71    bool isConstantFP() const { return EntryKind == E_ConstantFP; }
72    bool isConstantInt() const { return EntryKind == E_ConstantInt; }
73    int64_t getInt() const { return Constant.Int; }
74    const ConstantFP *getConstantFP() const { return Constant.CFP; }
75    const ConstantInt *getConstantInt() const { return Constant.CIP; }
76    MachineLocation getLoc() const { return Loc; }
77    DIVariable getVariable() const { return cast<MDLocalVariable>(Variable); }
78    bool isBitPiece() const { return getExpression()->isBitPiece(); }
79    DIExpression getExpression() const {
80      return cast_or_null<MDExpression>(Expression);
81    }
82    friend bool operator==(const Value &, const Value &);
83    friend bool operator<(const Value &, const Value &);
84  };
85
86private:
87  /// A nonempty list of locations/constants belonging to this entry,
88  /// sorted by offset.
89  SmallVector<Value, 1> Values;
90  SmallString<8> DWARFBytes;
91  SmallVector<std::string, 1> Comments;
92
93public:
94  DebugLocEntry(const MCSymbol *B, const MCSymbol *E, Value Val)
95      : Begin(B), End(E) {
96    Values.push_back(std::move(Val));
97  }
98
99  /// \brief If this and Next are describing different pieces of the same
100  /// variable, merge them by appending Next's values to the current
101  /// list of values.
102  /// Return true if the merge was successful.
103  bool MergeValues(const DebugLocEntry &Next) {
104    if (Begin == Next.Begin) {
105      DIExpression Expr = cast_or_null<MDExpression>(Values[0].Expression);
106      DIVariable Var = cast_or_null<MDLocalVariable>(Values[0].Variable);
107      DIExpression NextExpr =
108          cast_or_null<MDExpression>(Next.Values[0].Expression);
109      DIVariable NextVar = cast_or_null<MDLocalVariable>(Next.Values[0].Variable);
110      if (Var == NextVar && Expr->isBitPiece() && NextExpr->isBitPiece()) {
111        addValues(Next.Values);
112        End = Next.End;
113        return true;
114      }
115    }
116    return false;
117  }
118
119  /// \brief Attempt to merge this DebugLocEntry with Next and return
120  /// true if the merge was successful. Entries can be merged if they
121  /// share the same Loc/Constant and if Next immediately follows this
122  /// Entry.
123  bool MergeRanges(const DebugLocEntry &Next) {
124    // If this and Next are describing the same variable, merge them.
125    if ((End == Next.Begin && Values == Next.Values)) {
126      End = Next.End;
127      return true;
128    }
129    return false;
130  }
131
132  const MCSymbol *getBeginSym() const { return Begin; }
133  const MCSymbol *getEndSym() const { return End; }
134  ArrayRef<Value> getValues() const { return Values; }
135  void addValues(ArrayRef<DebugLocEntry::Value> Vals) {
136    Values.append(Vals.begin(), Vals.end());
137    sortUniqueValues();
138    assert(std::all_of(Values.begin(), Values.end(), [](DebugLocEntry::Value V){
139          return V.isBitPiece();
140        }) && "value must be a piece");
141  }
142
143  // \brief Sort the pieces by offset.
144  // Remove any duplicate entries by dropping all but the first.
145  void sortUniqueValues() {
146    std::sort(Values.begin(), Values.end());
147    Values.erase(std::unique(Values.begin(), Values.end(),
148                             [](const Value &A, const Value &B) {
149                   return A.getVariable() == B.getVariable() &&
150                          A.getExpression() == B.getExpression();
151                 }),
152                 Values.end());
153  }
154
155  /// \brief Lower this entry into a DWARF expression.
156  void finalize(const AsmPrinter &AP,
157                const DITypeIdentifierMap &TypeIdentifierMap);
158
159  /// \brief Return the lowered DWARF expression.
160  StringRef getDWARFBytes() const { return DWARFBytes; }
161  /// \brief Return the assembler comments for the lowered DWARF expression.
162  const SmallVectorImpl<std::string> &getComments() const { return Comments; }
163};
164
165/// \brief Compare two Values for equality.
166inline bool operator==(const DebugLocEntry::Value &A,
167                       const DebugLocEntry::Value &B) {
168  if (A.EntryKind != B.EntryKind)
169    return false;
170
171  if (A.Expression != B.Expression)
172    return false;
173
174  if (A.Variable != B.Variable)
175    return false;
176
177  switch (A.EntryKind) {
178  case DebugLocEntry::Value::E_Location:
179    return A.Loc == B.Loc;
180  case DebugLocEntry::Value::E_Integer:
181    return A.Constant.Int == B.Constant.Int;
182  case DebugLocEntry::Value::E_ConstantFP:
183    return A.Constant.CFP == B.Constant.CFP;
184  case DebugLocEntry::Value::E_ConstantInt:
185    return A.Constant.CIP == B.Constant.CIP;
186  }
187  llvm_unreachable("unhandled EntryKind");
188}
189
190/// \brief Compare two pieces based on their offset.
191inline bool operator<(const DebugLocEntry::Value &A,
192                      const DebugLocEntry::Value &B) {
193  return A.getExpression()->getBitPieceOffset() <
194         B.getExpression()->getBitPieceOffset();
195}
196
197}
198
199#endif
200