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 target specific location.
24 struct TargetIndexLocation {
25   int Index;
26   int Offset;
27 
28   TargetIndexLocation() = default;
29   TargetIndexLocation(unsigned Idx, int64_t Offset)
30       : Index(Idx), Offset(Offset) {}
31 
32   bool operator==(const TargetIndexLocation &Other) const {
33     return Index == Other.Index && Offset == Other.Offset;
34   }
35 };
36 
37 /// A single location or constant within a variable location description, with
38 /// either a single entry (with an optional DIExpression) used for a DBG_VALUE,
39 /// or a list of entries used for a DBG_VALUE_LIST.
40 class DbgValueLocEntry {
41 
42   /// Type of entry that this represents.
43   enum EntryType {
44     E_Location,
45     E_Integer,
46     E_ConstantFP,
47     E_ConstantInt,
48     E_TargetIndexLocation
49   };
50   enum EntryType EntryKind;
51 
52   /// Either a constant,
53   union {
54     int64_t Int;
55     const ConstantFP *CFP;
56     const ConstantInt *CIP;
57   } Constant;
58 
59   union {
60     /// Or a location in the machine frame.
61     MachineLocation Loc;
62     /// Or a location from target specific location.
63     TargetIndexLocation TIL;
64   };
65 
66 public:
67   DbgValueLocEntry(int64_t i) : EntryKind(E_Integer) { Constant.Int = i; }
68   DbgValueLocEntry(const ConstantFP *CFP) : EntryKind(E_ConstantFP) {
69     Constant.CFP = CFP;
70   }
71   DbgValueLocEntry(const ConstantInt *CIP) : EntryKind(E_ConstantInt) {
72     Constant.CIP = CIP;
73   }
74   DbgValueLocEntry(MachineLocation Loc) : EntryKind(E_Location), Loc(Loc) {}
75   DbgValueLocEntry(TargetIndexLocation Loc)
76       : EntryKind(E_TargetIndexLocation), TIL(Loc) {}
77 
78   bool isLocation() const { return EntryKind == E_Location; }
79   bool isTargetIndexLocation() const {
80     return EntryKind == E_TargetIndexLocation;
81   }
82   bool isInt() const { return EntryKind == E_Integer; }
83   bool isConstantFP() const { return EntryKind == E_ConstantFP; }
84   bool isConstantInt() const { return EntryKind == E_ConstantInt; }
85   int64_t getInt() const { return Constant.Int; }
86   const ConstantFP *getConstantFP() const { return Constant.CFP; }
87   const ConstantInt *getConstantInt() const { return Constant.CIP; }
88   MachineLocation getLoc() const { return Loc; }
89   TargetIndexLocation getTargetIndexLocation() const { return TIL; }
90   friend bool operator==(const DbgValueLocEntry &, const DbgValueLocEntry &);
91 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
92   LLVM_DUMP_METHOD void dump() const {
93     if (isLocation()) {
94       llvm::dbgs() << "Loc = { reg=" << Loc.getReg() << " ";
95       if (Loc.isIndirect())
96         llvm::dbgs() << "+0";
97       llvm::dbgs() << "} ";
98     } else if (isConstantInt())
99       Constant.CIP->dump();
100     else if (isConstantFP())
101       Constant.CFP->dump();
102   }
103 #endif
104 };
105 
106 /// The location of a single variable, composed of an expression and 0 or more
107 /// DbgValueLocEntries.
108 class DbgValueLoc {
109   /// Any complex address location expression for this DbgValueLoc.
110   const DIExpression *Expression;
111 
112   SmallVector<DbgValueLocEntry, 2> ValueLocEntries;
113 
114   bool IsVariadic;
115 
116 public:
117   DbgValueLoc(const DIExpression *Expr, ArrayRef<DbgValueLocEntry> Locs)
118       : Expression(Expr), ValueLocEntries(Locs.begin(), Locs.end()),
119         IsVariadic(true) {
120 #ifndef NDEBUG
121     // Currently, DBG_VALUE_VAR expressions must use stack_value.
122     assert(Expr && Expr->isValid() &&
123            is_contained(Locs, dwarf::DW_OP_stack_value));
124 #endif
125   }
126 
127   DbgValueLoc(const DIExpression *Expr, ArrayRef<DbgValueLocEntry> Locs,
128               bool IsVariadic)
129       : Expression(Expr), ValueLocEntries(Locs.begin(), Locs.end()),
130         IsVariadic(IsVariadic) {
131 #ifndef NDEBUG
132     assert(cast<DIExpression>(Expr)->isValid() ||
133            !any_of(Locs, [](auto LE) { return LE.isLocation(); }));
134     if (!IsVariadic) {
135       assert(ValueLocEntries.size() == 1);
136     } else {
137       // Currently, DBG_VALUE_VAR expressions must use stack_value.
138       assert(Expr && Expr->isValid() &&
139              is_contained(Expr->getElements(), dwarf::DW_OP_stack_value));
140     }
141 #endif
142   }
143 
144   DbgValueLoc(const DIExpression *Expr, DbgValueLocEntry Loc)
145       : Expression(Expr), ValueLocEntries(1, Loc), IsVariadic(false) {
146     assert(((Expr && Expr->isValid()) || !Loc.isLocation()) &&
147            "DBG_VALUE with a machine location must have a valid expression.");
148   }
149 
150   bool isFragment() const { return getExpression()->isFragment(); }
151   bool isEntryVal() const { return getExpression()->isEntryValue(); }
152   bool isVariadic() const { return IsVariadic; }
153   const DIExpression *getExpression() const { return Expression; }
154   const ArrayRef<DbgValueLocEntry> getLocEntries() const {
155     return ValueLocEntries;
156   }
157   friend bool operator==(const DbgValueLoc &, const DbgValueLoc &);
158   friend bool operator<(const DbgValueLoc &, const DbgValueLoc &);
159 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
160   LLVM_DUMP_METHOD void dump() const {
161     for (const DbgValueLocEntry &DV : ValueLocEntries)
162       DV.dump();
163     if (Expression)
164       Expression->dump();
165   }
166 #endif
167 };
168 
169 /// This struct describes location entries emitted in the .debug_loc
170 /// section.
171 class DebugLocEntry {
172   /// Begin and end symbols for the address range that this location is valid.
173   const MCSymbol *Begin;
174   const MCSymbol *End;
175 
176   /// A nonempty list of locations/constants belonging to this entry,
177   /// sorted by offset.
178   SmallVector<DbgValueLoc, 1> Values;
179 
180 public:
181   /// Create a location list entry for the range [\p Begin, \p End).
182   ///
183   /// \param Vals One or more values describing (parts of) the variable.
184   DebugLocEntry(const MCSymbol *Begin, const MCSymbol *End,
185                 ArrayRef<DbgValueLoc> Vals)
186       : Begin(Begin), End(End) {
187     addValues(Vals);
188   }
189 
190   /// Attempt to merge this DebugLocEntry with Next and return
191   /// true if the merge was successful. Entries can be merged if they
192   /// share the same Loc/Constant and if Next immediately follows this
193   /// Entry.
194   bool MergeRanges(const DebugLocEntry &Next) {
195     // If this and Next are describing the same variable, merge them.
196     if ((End == Next.Begin && Values == Next.Values)) {
197       End = Next.End;
198       return true;
199     }
200     return false;
201   }
202 
203   const MCSymbol *getBeginSym() const { return Begin; }
204   const MCSymbol *getEndSym() const { return End; }
205   ArrayRef<DbgValueLoc> getValues() const { return Values; }
206   void addValues(ArrayRef<DbgValueLoc> Vals) {
207     Values.append(Vals.begin(), Vals.end());
208     sortUniqueValues();
209     assert((Values.size() == 1 || all_of(Values, [](DbgValueLoc V) {
210               return V.isFragment();
211             })) && "must either have a single value or multiple pieces");
212   }
213 
214   // Sort the pieces by offset.
215   // Remove any duplicate entries by dropping all but the first.
216   void sortUniqueValues() {
217     llvm::sort(Values);
218     Values.erase(std::unique(Values.begin(), Values.end(),
219                              [](const DbgValueLoc &A, const DbgValueLoc &B) {
220                                return A.getExpression() == B.getExpression();
221                              }),
222                  Values.end());
223   }
224 
225   /// Lower this entry into a DWARF expression.
226   void finalize(const AsmPrinter &AP,
227                 DebugLocStream::ListBuilder &List,
228                 const DIBasicType *BT,
229                 DwarfCompileUnit &TheCU);
230 };
231 
232 /// Compare two DbgValueLocEntries for equality.
233 inline bool operator==(const DbgValueLocEntry &A, const DbgValueLocEntry &B) {
234   if (A.EntryKind != B.EntryKind)
235     return false;
236 
237   switch (A.EntryKind) {
238   case DbgValueLocEntry::E_Location:
239     return A.Loc == B.Loc;
240   case DbgValueLocEntry::E_TargetIndexLocation:
241     return A.TIL == B.TIL;
242   case DbgValueLocEntry::E_Integer:
243     return A.Constant.Int == B.Constant.Int;
244   case DbgValueLocEntry::E_ConstantFP:
245     return A.Constant.CFP == B.Constant.CFP;
246   case DbgValueLocEntry::E_ConstantInt:
247     return A.Constant.CIP == B.Constant.CIP;
248   }
249   llvm_unreachable("unhandled EntryKind");
250 }
251 
252 /// Compare two DbgValueLocs for equality.
253 inline bool operator==(const DbgValueLoc &A, const DbgValueLoc &B) {
254   return A.ValueLocEntries == B.ValueLocEntries &&
255          A.Expression == B.Expression && A.IsVariadic == B.IsVariadic;
256 }
257 
258 /// Compare two fragments based on their offset.
259 inline bool operator<(const DbgValueLoc &A,
260                       const DbgValueLoc &B) {
261   return A.getExpression()->getFragmentInfo()->OffsetInBits <
262          B.getExpression()->getFragmentInfo()->OffsetInBits;
263 }
264 
265 }
266 
267 #endif
268