Coverage Report

Created: 2017-10-03 07:32

/Users/buildslave/jenkins/sharedspace/clang-stage2-coverage-R@2/llvm/include/llvm/MC/MCSymbol.h
Line
Count
Source (jump to first uncovered line)
1
//===- MCSymbol.h - Machine Code Symbols ------------------------*- 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
// This file contains the declaration of the MCSymbol class.
11
//
12
//===----------------------------------------------------------------------===//
13
14
#ifndef LLVM_MC_MCSYMBOL_H
15
#define LLVM_MC_MCSYMBOL_H
16
17
#include "llvm/ADT/PointerIntPair.h"
18
#include "llvm/ADT/StringMap.h"
19
#include "llvm/ADT/StringRef.h"
20
#include "llvm/MC/MCFragment.h"
21
#include "llvm/Support/ErrorHandling.h"
22
#include "llvm/Support/MathExtras.h"
23
#include <cassert>
24
#include <cstddef>
25
#include <cstdint>
26
27
namespace llvm {
28
29
class MCAsmInfo;
30
class MCContext;
31
class MCExpr;
32
class MCSection;
33
class raw_ostream;
34
35
/// MCSymbol - Instances of this class represent a symbol name in the MC file,
36
/// and MCSymbols are created and uniqued by the MCContext class.  MCSymbols
37
/// should only be constructed with valid names for the object file.
38
///
39
/// If the symbol is defined/emitted into the current translation unit, the
40
/// Section member is set to indicate what section it lives in.  Otherwise, if
41
/// it is a reference to an external entity, it has a null section.
42
class MCSymbol {
43
protected:
44
  /// The kind of the symbol.  If it is any value other than unset then this
45
  /// class is actually one of the appropriate subclasses of MCSymbol.
46
  enum SymbolKind {
47
    SymbolKindUnset,
48
    SymbolKindCOFF,
49
    SymbolKindELF,
50
    SymbolKindMachO,
51
    SymbolKindWasm,
52
  };
53
54
  /// A symbol can contain an Offset, or Value, or be Common, but never more
55
  /// than one of these.
56
  enum Contents : uint8_t {
57
    SymContentsUnset,
58
    SymContentsOffset,
59
    SymContentsVariable,
60
    SymContentsCommon,
61
  };
62
63
  // Special sentinal value for the absolute pseudo fragment.
64
  static MCFragment *AbsolutePseudoFragment;
65
66
  /// If a symbol has a Fragment, the section is implied, so we only need
67
  /// one pointer.
68
  /// The special AbsolutePseudoFragment value is for absolute symbols.
69
  /// If this is a variable symbol, this caches the variable value's fragment.
70
  /// FIXME: We might be able to simplify this by having the asm streamer create
71
  /// dummy fragments.
72
  /// If this is a section, then it gives the symbol is defined in. This is null
73
  /// for undefined symbols.
74
  ///
75
  /// If this is a fragment, then it gives the fragment this symbol's value is
76
  /// relative to, if any.
77
  ///
78
  /// For the 'HasName' integer, this is true if this symbol is named.
79
  /// A named symbol will have a pointer to the name allocated in the bytes
80
  /// immediately prior to the MCSymbol.
81
  mutable PointerIntPair<MCFragment *, 1> FragmentAndHasName;
82
83
  /// IsTemporary - True if this is an assembler temporary label, which
84
  /// typically does not survive in the .o file's symbol table.  Usually
85
  /// "Lfoo" or ".foo".
86
  unsigned IsTemporary : 1;
87
88
  /// \brief True if this symbol can be redefined.
89
  unsigned IsRedefinable : 1;
90
91
  /// IsUsed - True if this symbol has been used.
92
  mutable unsigned IsUsed : 1;
93
94
  mutable unsigned IsRegistered : 1;
95
96
  /// This symbol is visible outside this translation unit.
97
  mutable unsigned IsExternal : 1;
98
99
  /// This symbol is private extern.
100
  mutable unsigned IsPrivateExtern : 1;
101
102
  /// LLVM RTTI discriminator. This is actually a SymbolKind enumerator, but is
103
  /// unsigned to avoid sign extension and achieve better bitpacking with MSVC.
104
  unsigned Kind : 3;
105
106
  /// True if we have created a relocation that uses this symbol.
107
  mutable unsigned IsUsedInReloc : 1;
108
109
  /// This is actually a Contents enumerator, but is unsigned to avoid sign
110
  /// extension and achieve better bitpacking with MSVC.
111
  unsigned SymbolContents : 2;
112
113
  /// The alignment of the symbol, if it is 'common', or -1.
114
  ///
115
  /// The alignment is stored as log2(align) + 1.  This allows all values from
116
  /// 0 to 2^31 to be stored which is every power of 2 representable by an
117
  /// unsigned.
118
  enum : unsigned { NumCommonAlignmentBits = 5 };
119
  unsigned CommonAlignLog2 : NumCommonAlignmentBits;
120
121
  /// The Flags field is used by object file implementations to store
122
  /// additional per symbol information which is not easily classified.
123
  enum : unsigned { NumFlagsBits = 16 };
124
  mutable uint32_t Flags : NumFlagsBits;
125
126
  /// Index field, for use by the object file implementation.
127
  mutable uint32_t Index = 0;
128
129
  union {
130
    /// The offset to apply to the fragment address to form this symbol's value.
131
    uint64_t Offset;
132
133
    /// The size of the symbol, if it is 'common'.
134
    uint64_t CommonSize;
135
136
    /// If non-null, the value for a variable symbol.
137
    const MCExpr *Value;
138
  };
139
140
  // MCContext creates and uniques these.
141
  friend class MCExpr;
142
  friend class MCContext;
143
144
  /// \brief The name for a symbol.
145
  /// MCSymbol contains a uint64_t so is probably aligned to 8.  On a 32-bit
146
  /// system, the name is a pointer so isn't going to satisfy the 8 byte
147
  /// alignment of uint64_t.  Account for that here.
148
  using NameEntryStorageTy = union {
149
    const StringMapEntry<bool> *NameEntry;
150
    uint64_t AlignmentPadding;
151
  };
152
153
  MCSymbol(SymbolKind Kind, const StringMapEntry<bool> *Name, bool isTemporary)
154
      : IsTemporary(isTemporary), IsRedefinable(false), IsUsed(false),
155
        IsRegistered(false), IsExternal(false), IsPrivateExtern(false),
156
        Kind(Kind), IsUsedInReloc(false), SymbolContents(SymContentsUnset),
157
8.63M
        CommonAlignLog2(0), Flags(0) {
158
8.63M
    Offset = 0;
159
8.63M
    FragmentAndHasName.setInt(!!Name);
160
8.63M
    if (Name)
161
4.94M
      getNameEntryPtr() = Name;
162
8.63M
  }
163
164
  // Provide custom new/delete as we will only allocate space for a name
165
  // if we need one.
166
  void *operator new(size_t s, const StringMapEntry<bool> *Name,
167
                     MCContext &Ctx);
168
169
private:
170
  void operator delete(void *);
171
  /// \brief Placement delete - required by std, but never called.
172
0
  void operator delete(void*, unsigned) {
173
0
    llvm_unreachable("Constructor throws?");
174
0
  }
175
  /// \brief Placement delete - required by std, but never called.
176
0
  void operator delete(void*, unsigned, bool) {
177
0
    llvm_unreachable("Constructor throws?");
178
0
  }
179
180
6.00M
  MCSection *getSectionPtr(bool SetUsed = true) const {
181
6.00M
    if (MCFragment *
F6.00M
= getFragment(SetUsed)) {
182
6.00M
      assert(F != AbsolutePseudoFragment);
183
6.00M
      return F->getParent();
184
6.00M
    }
185
1
    return nullptr;
186
6.00M
  }
187
188
  /// \brief Get a reference to the name field.  Requires that we have a name
189
21.3M
  const StringMapEntry<bool> *&getNameEntryPtr() {
190
21.3M
    assert(FragmentAndHasName.getInt() && "Name is required");
191
21.3M
    NameEntryStorageTy *Name = reinterpret_cast<NameEntryStorageTy *>(this);
192
21.3M
    return (*(Name - 1)).NameEntry;
193
21.3M
  }
194
16.3M
  const StringMapEntry<bool> *&getNameEntryPtr() const {
195
16.3M
    return const_cast<MCSymbol*>(this)->getNameEntryPtr();
196
16.3M
  }
197
198
public:
199
  MCSymbol(const MCSymbol &) = delete;
200
  MCSymbol &operator=(const MCSymbol &) = delete;
201
202
  /// getName - Get the symbol name.
203
16.3M
  StringRef getName() const {
204
16.3M
    if (!FragmentAndHasName.getInt())
205
560
      return StringRef();
206
16.3M
207
16.3M
    return getNameEntryPtr()->first();
208
16.3M
  }
209
210
16.1M
  bool isRegistered() const { return IsRegistered; }
211
7.15M
  void setIsRegistered(bool Value) const { IsRegistered = Value; }
212
213
9.66k
  void setUsedInReloc() const { IsUsedInReloc = true; }
214
21.0M
  bool isUsedInReloc() const { return IsUsedInReloc; }
215
216
  /// \name Accessors
217
  /// @{
218
219
  /// isTemporary - Check if this is an assembler temporary symbol.
220
47.8M
  bool isTemporary() const { return IsTemporary; }
221
222
  /// isUsed - Check if this is used.
223
335
  bool isUsed() const { return IsUsed; }
224
0
  void setUsed(bool Value) const { IsUsed |= Value; }
225
226
  /// \brief Check if this symbol is redefinable.
227
0
  bool isRedefinable() const { return IsRedefinable; }
228
  /// \brief Mark this symbol as redefinable.
229
655
  void setRedefinable(bool Value) { IsRedefinable = Value; }
230
  /// \brief Prepare this symbol to be redefined.
231
8.05M
  void redefineIfPossible() {
232
8.05M
    if (
IsRedefinable8.05M
) {
233
3
      if (
SymbolContents == SymContentsVariable3
) {
234
3
        Value = nullptr;
235
3
        SymbolContents = SymContentsUnset;
236
3
      }
237
3
      setUndefined();
238
3
      IsRedefinable = false;
239
3
    }
240
8.05M
  }
241
242
  /// @}
243
  /// \name Associated Sections
244
  /// @{
245
246
  /// isDefined - Check if this symbol is defined (i.e., it has an address).
247
  ///
248
  /// Defined symbols are either absolute or in some section.
249
69.1M
  bool isDefined(bool SetUsed = true) const {
250
69.1M
    return getFragment(SetUsed) != nullptr;
251
69.1M
  }
252
253
  /// isInSection - Check if this symbol is defined in some section (i.e., it
254
  /// is defined but not absolute).
255
38.2M
  bool isInSection(bool SetUsed = true) const {
256
31.9M
    return isDefined(SetUsed) && !isAbsolute(SetUsed);
257
38.2M
  }
258
259
  /// isUndefined - Check if this symbol undefined (i.e., implicitly defined).
260
20.2M
  bool isUndefined(bool SetUsed = true) const { return !isDefined(SetUsed); }
261
262
  /// isAbsolute - Check if this is an absolute symbol.
263
34.5M
  bool isAbsolute(bool SetUsed = true) const {
264
34.5M
    return getFragment(SetUsed) == AbsolutePseudoFragment;
265
34.5M
  }
266
267
  /// Get the section associated with a defined, non-absolute symbol.
268
6.00M
  MCSection &getSection(bool SetUsed = true) const {
269
6.00M
    assert(isInSection(SetUsed) && "Invalid accessor!");
270
6.00M
    return *getSectionPtr(SetUsed);
271
6.00M
  }
272
273
  /// Mark the symbol as defined in the fragment \p F.
274
14.3M
  void setFragment(MCFragment *F) const {
275
14.3M
    assert(!isVariable() && "Cannot set fragment of variable");
276
14.3M
    FragmentAndHasName.setPointer(F);
277
14.3M
  }
278
279
  /// Mark the symbol as undefined.
280
174k
  void setUndefined() { FragmentAndHasName.setPointer(nullptr); }
281
282
62.9k
  bool isELF() const { return Kind == SymbolKindELF; }
283
284
0
  bool isCOFF() const { return Kind == SymbolKindCOFF; }
285
286
0
  bool isMachO() const { return Kind == SymbolKindMachO; }
287
288
0
  bool isWasm() const { return Kind == SymbolKindWasm; }
289
290
  /// @}
291
  /// \name Variable Symbols
292
  /// @{
293
294
  /// isVariable - Check if this is a variable symbol.
295
72.7M
  bool isVariable() const {
296
72.7M
    return SymbolContents == SymContentsVariable;
297
72.7M
  }
298
299
  /// getVariableValue - Get the value for variable symbols.
300
904k
  const MCExpr *getVariableValue(bool SetUsed = true) const {
301
904k
    assert(isVariable() && "Invalid accessor!");
302
904k
    IsUsed |= SetUsed;
303
904k
    return Value;
304
904k
  }
305
306
  void setVariableValue(const MCExpr *Value);
307
308
  /// @}
309
310
  /// Get the (implementation defined) index.
311
4.87M
  uint32_t getIndex() const {
312
4.87M
    return Index;
313
4.87M
  }
314
315
  /// Set the (implementation defined) index.
316
1.49M
  void setIndex(uint32_t Value) const {
317
1.49M
    Index = Value;
318
1.49M
  }
319
320
14.5M
  uint64_t getOffset() const {
321
14.5M
    assert((SymbolContents == SymContentsUnset ||
322
14.5M
            SymbolContents == SymContentsOffset) &&
323
14.5M
           "Cannot get offset for a common/variable symbol");
324
14.5M
    return Offset;
325
14.5M
  }
326
6.41M
  void setOffset(uint64_t Value) {
327
6.41M
    assert((SymbolContents == SymContentsUnset ||
328
6.41M
            SymbolContents == SymContentsOffset) &&
329
6.41M
           "Cannot set offset for a common/variable symbol");
330
6.41M
    Offset = Value;
331
6.41M
    SymbolContents = SymContentsOffset;
332
6.41M
  }
333
334
  /// Return the size of a 'common' symbol.
335
21.4k
  uint64_t getCommonSize() const {
336
21.4k
    assert(isCommon() && "Not a 'common' symbol!");
337
21.4k
    return CommonSize;
338
21.4k
  }
339
340
  /// Mark this symbol as being 'common'.
341
  ///
342
  /// \param Size - The size of the symbol.
343
  /// \param Align - The alignment of the symbol.
344
21.6k
  void setCommon(uint64_t Size, unsigned Align) {
345
21.6k
    assert(getOffset() == 0);
346
21.6k
    CommonSize = Size;
347
21.6k
    SymbolContents = SymContentsCommon;
348
21.6k
349
21.6k
    assert((!Align || isPowerOf2_32(Align)) &&
350
21.6k
           "Alignment must be a power of 2");
351
21.6k
    unsigned Log2Align = Log2_32(Align) + 1;
352
21.6k
    assert(Log2Align < (1U << NumCommonAlignmentBits) &&
353
21.6k
           "Out of range alignment");
354
21.6k
    CommonAlignLog2 = Log2Align;
355
21.6k
  }
356
357
  ///  Return the alignment of a 'common' symbol.
358
21.6k
  unsigned getCommonAlignment() const {
359
21.6k
    assert(isCommon() && "Not a 'common' symbol!");
360
21.6k
    return CommonAlignLog2 ? 
(1U << (CommonAlignLog2 - 1))21.5k
:
021
;
361
21.6k
  }
362
363
  /// Declare this symbol as being 'common'.
364
  ///
365
  /// \param Size - The size of the symbol.
366
  /// \param Align - The alignment of the symbol.
367
  /// \return True if symbol was already declared as a different type
368
138
  bool declareCommon(uint64_t Size, unsigned Align) {
369
138
    assert(isCommon() || getOffset() == 0);
370
138
    if(
isCommon()138
) {
371
3
      if(
CommonSize != Size || 3
getCommonAlignment() != Align2
)
372
1
       return true;
373
3
    } else
374
135
      setCommon(Size, Align);
375
137
    return false;
376
138
  }
377
378
  /// Is this a 'common' symbol.
379
1.73M
  bool isCommon() const {
380
1.73M
    return SymbolContents == SymContentsCommon;
381
1.73M
  }
382
383
152M
  MCFragment *getFragment(bool SetUsed = true) const {
384
152M
    MCFragment *Fragment = FragmentAndHasName.getPointer();
385
152M
    if (
Fragment || 152M
!isVariable()17.6M
)
386
152M
      return Fragment;
387
170k
    Fragment = getVariableValue(SetUsed)->findAssociatedFragment();
388
170k
    FragmentAndHasName.setPointer(Fragment);
389
170k
    return Fragment;
390
152M
  }
391
392
4.45M
  bool isExternal() const { return IsExternal; }
393
586k
  void setExternal(bool Value) const { IsExternal = Value; }
394
395
1.48M
  bool isPrivateExtern() const { return IsPrivateExtern; }
396
17.4k
  void setPrivateExtern(bool Value) { IsPrivateExtern = Value; }
397
398
  /// print - Print the value to the stream \p OS.
399
  void print(raw_ostream &OS, const MCAsmInfo *MAI) const;
400
401
  /// dump - Print the value to stderr.
402
  void dump() const;
403
404
protected:
405
  /// Get the (implementation defined) symbol flags.
406
9.69M
  uint32_t getFlags() const { return Flags; }
407
408
  /// Set the (implementation defined) symbol flags.
409
3.48M
  void setFlags(uint32_t Value) const {
410
3.48M
    assert(Value < (1U << NumFlagsBits) && "Out of range flags");
411
3.48M
    Flags = Value;
412
3.48M
  }
413
414
  /// Modify the flags via a mask
415
7.41M
  void modifyFlags(uint32_t Value, uint32_t Mask) const {
416
7.41M
    assert(Value < (1U << NumFlagsBits) && "Out of range flags");
417
7.41M
    Flags = (Flags & ~Mask) | Value;
418
7.41M
  }
419
};
420
421
14
inline raw_ostream &operator<<(raw_ostream &OS, const MCSymbol &Sym) {
422
14
  Sym.print(OS, nullptr);
423
14
  return OS;
424
14
}
425
426
} // end namespace llvm
427
428
#endif // LLVM_MC_MCSYMBOL_H