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
20namespace llvm {
21class AsmPrinter;
22
23/// \brief This struct describes location entries emitted in the .debug_loc
24/// section.
25class DebugLocEntry {
26  /// Begin and end symbols for the address range that this location is valid.
27  const MCSymbol *Begin;
28  const MCSymbol *End;
29
30public:
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 isBitPiece() const { return getExpression()->isBitPiece(); }
76    const DIExpression *getExpression() const { return Expression; }
77    friend bool operator==(const Value &, const Value &);
78    friend bool operator<(const Value &, const Value &);
79  };
80
81private:
82  /// A nonempty list of locations/constants belonging to this entry,
83  /// sorted by offset.
84  SmallVector<Value, 1> Values;
85
86public:
87  DebugLocEntry(const MCSymbol *B, const MCSymbol *E, Value Val)
88      : Begin(B), End(E) {
89    Values.push_back(std::move(Val));
90  }
91
92  /// \brief If this and Next are describing different pieces of the same
93  /// variable, merge them by appending Next's values to the current
94  /// list of values.
95  /// Return true if the merge was successful.
96  bool MergeValues(const DebugLocEntry &Next) {
97    if (Begin == Next.Begin) {
98      auto *Expr = cast_or_null<DIExpression>(Values[0].Expression);
99      auto *NextExpr = cast_or_null<DIExpression>(Next.Values[0].Expression);
100      if (Expr->isBitPiece() && NextExpr->isBitPiece()) {
101        addValues(Next.Values);
102        End = Next.End;
103        return true;
104      }
105    }
106    return false;
107  }
108
109  /// \brief Attempt to merge this DebugLocEntry with Next and return
110  /// true if the merge was successful. Entries can be merged if they
111  /// share the same Loc/Constant and if Next immediately follows this
112  /// Entry.
113  bool MergeRanges(const DebugLocEntry &Next) {
114    // If this and Next are describing the same variable, merge them.
115    if ((End == Next.Begin && Values == Next.Values)) {
116      End = Next.End;
117      return true;
118    }
119    return false;
120  }
121
122  const MCSymbol *getBeginSym() const { return Begin; }
123  const MCSymbol *getEndSym() const { return End; }
124  ArrayRef<Value> getValues() const { return Values; }
125  void addValues(ArrayRef<DebugLocEntry::Value> Vals) {
126    Values.append(Vals.begin(), Vals.end());
127    sortUniqueValues();
128    assert(std::all_of(Values.begin(), Values.end(), [](DebugLocEntry::Value V){
129          return V.isBitPiece();
130        }) && "value must be a piece");
131  }
132
133  // \brief Sort the pieces by offset.
134  // Remove any duplicate entries by dropping all but the first.
135  void sortUniqueValues() {
136    std::sort(Values.begin(), Values.end());
137    Values.erase(
138        std::unique(
139            Values.begin(), Values.end(), [](const Value &A, const Value &B) {
140              return A.getExpression() == B.getExpression();
141            }),
142        Values.end());
143  }
144
145  /// \brief Lower this entry into a DWARF expression.
146  void finalize(const AsmPrinter &AP, DebugLocStream::ListBuilder &List,
147                const DIBasicType *BT);
148};
149
150/// \brief Compare two Values for equality.
151inline bool operator==(const DebugLocEntry::Value &A,
152                       const DebugLocEntry::Value &B) {
153  if (A.EntryKind != B.EntryKind)
154    return false;
155
156  if (A.Expression != B.Expression)
157    return false;
158
159  switch (A.EntryKind) {
160  case DebugLocEntry::Value::E_Location:
161    return A.Loc == B.Loc;
162  case DebugLocEntry::Value::E_Integer:
163    return A.Constant.Int == B.Constant.Int;
164  case DebugLocEntry::Value::E_ConstantFP:
165    return A.Constant.CFP == B.Constant.CFP;
166  case DebugLocEntry::Value::E_ConstantInt:
167    return A.Constant.CIP == B.Constant.CIP;
168  }
169  llvm_unreachable("unhandled EntryKind");
170}
171
172/// \brief Compare two pieces based on their offset.
173inline bool operator<(const DebugLocEntry::Value &A,
174                      const DebugLocEntry::Value &B) {
175  return A.getExpression()->getBitPieceOffset() <
176         B.getExpression()->getBitPieceOffset();
177}
178
179}
180
181#endif
182