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DWARFLinkerCompileUnit.h
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1 //===- DWARFLinkerCompileUnit.h ---------------------------------*- 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_DWARFLINKER_DWARFLINKERCOMPILEUNIT_H
10 #define LLVM_DWARFLINKER_DWARFLINKERCOMPILEUNIT_H
11 
12 #include "llvm/ADT/IntervalMap.h"
13 #include "llvm/CodeGen/DIE.h"
16 
17 namespace llvm {
18 
19 class DeclContext;
20 
21 template <typename KeyT, typename ValT>
22 using HalfOpenIntervalMap =
23  IntervalMap<KeyT, ValT, IntervalMapImpl::NodeSizer<KeyT, ValT>::LeafSize,
25 
27 
28 // FIXME: Delete this structure.
29 struct PatchLocation {
31 
32  PatchLocation() = default;
34 
35  void set(uint64_t New) const {
36  assert(I);
37  const auto &Old = *I;
38  assert(Old.getType() == DIEValue::isInteger);
39  *I = DIEValue(Old.getAttribute(), Old.getForm(), DIEInteger(New));
40  }
41 
42  uint64_t get() const {
43  assert(I);
44  return I->getDIEInteger().getValue();
45  }
46 };
47 
48 /// Stores all information relating to a compile unit, be it in its original
49 /// instance in the object file to its brand new cloned and generated DIE tree.
50 class CompileUnit {
51 public:
52  /// Information gathered about a DIE in the object file.
53  struct DIEInfo {
54  /// Address offset to apply to the described entity.
55  int64_t AddrAdjust;
56 
57  /// ODR Declaration context.
59 
60  /// Cloned version of that DIE.
62 
63  /// The index of this DIE's parent.
65 
66  /// Is the DIE part of the linked output?
67  bool Keep : 1;
68 
69  /// Was this DIE's entity found in the map?
70  bool InDebugMap : 1;
71 
72  /// Is this a pure forward declaration we can strip?
73  bool Prune : 1;
74 
75  /// Does DIE transitively refer an incomplete decl?
76  bool Incomplete : 1;
77  };
78 
79  CompileUnit(DWARFUnit &OrigUnit, unsigned ID, bool CanUseODR,
80  StringRef ClangModuleName)
81  : OrigUnit(OrigUnit), ID(ID), Ranges(RangeAlloc),
82  ClangModuleName(ClangModuleName) {
83  Info.resize(OrigUnit.getNumDIEs());
84 
85  auto CUDie = OrigUnit.getUnitDIE(false);
86  if (!CUDie) {
87  HasODR = false;
88  return;
89  }
90  if (auto Lang = dwarf::toUnsigned(CUDie.find(dwarf::DW_AT_language)))
91  HasODR = CanUseODR && (*Lang == dwarf::DW_LANG_C_plus_plus ||
92  *Lang == dwarf::DW_LANG_C_plus_plus_03 ||
93  *Lang == dwarf::DW_LANG_C_plus_plus_11 ||
94  *Lang == dwarf::DW_LANG_C_plus_plus_14 ||
95  *Lang == dwarf::DW_LANG_ObjC_plus_plus);
96  else
97  HasODR = false;
98  }
99 
100  DWARFUnit &getOrigUnit() const { return OrigUnit; }
101 
102  unsigned getUniqueID() const { return ID; }
103 
104  void createOutputDIE() { NewUnit.emplace(OrigUnit.getUnitDIE().getTag()); }
105 
107  if (NewUnit)
108  return &const_cast<BasicDIEUnit &>(*NewUnit).getUnitDie();
109  return nullptr;
110  }
111 
112  bool hasODR() const { return HasODR; }
113  bool isClangModule() const { return !ClangModuleName.empty(); }
115  /// Return the DW_AT_LLVM_sysroot of the compile unit or an empty StringRef.
117 
118  const std::string &getClangModuleName() const { return ClangModuleName; }
119 
120  DIEInfo &getInfo(unsigned Idx) { return Info[Idx]; }
121  const DIEInfo &getInfo(unsigned Idx) const { return Info[Idx]; }
122 
123  DIEInfo &getInfo(const DWARFDie &Die) {
124  unsigned Idx = getOrigUnit().getDIEIndex(Die);
125  return Info[Idx];
126  }
127 
128  uint64_t getStartOffset() const { return StartOffset; }
129  uint64_t getNextUnitOffset() const { return NextUnitOffset; }
130  void setStartOffset(uint64_t DebugInfoSize) { StartOffset = DebugInfoSize; }
131 
132  uint64_t getLowPc() const { return LowPc; }
133  uint64_t getHighPc() const { return HighPc; }
134  bool hasLabelAt(uint64_t Addr) const { return Labels.count(Addr); }
135 
137  return UnitRangeAttribute;
138  }
139 
140  const FunctionIntervals &getFunctionRanges() const { return Ranges; }
141 
142  const std::vector<PatchLocation> &getRangesAttributes() const {
143  return RangeAttributes;
144  }
145 
146  const std::vector<std::pair<PatchLocation, int64_t>> &
148  return LocationAttributes;
149  }
150 
151  void setHasInterestingContent() { HasInterestingContent = true; }
152  bool hasInterestingContent() { return HasInterestingContent; }
153 
154  /// Mark every DIE in this unit as kept. This function also
155  /// marks variables as InDebugMap so that they appear in the
156  /// reconstructed accelerator tables.
157  void markEverythingAsKept();
158 
159  /// Compute the end offset for this unit. Must be called after the CU's DIEs
160  /// have been cloned. \returns the next unit offset (which is also the
161  /// current debug_info section size).
162  uint64_t computeNextUnitOffset(uint16_t DwarfVersion);
163 
164  /// Keep track of a forward reference to DIE \p Die in \p RefUnit by \p
165  /// Attr. The attribute should be fixed up later to point to the absolute
166  /// offset of \p Die in the debug_info section or to the canonical offset of
167  /// \p Ctxt if it is non-null.
168  void noteForwardReference(DIE *Die, const CompileUnit *RefUnit,
169  DeclContext *Ctxt, PatchLocation Attr);
170 
171  /// Apply all fixups recorded by noteForwardReference().
172  void fixupForwardReferences();
173 
174  /// Add the low_pc of a label that is relocated by applying
175  /// offset \p PCOffset.
176  void addLabelLowPc(uint64_t LabelLowPc, int64_t PcOffset);
177 
178  /// Add a function range [\p LowPC, \p HighPC) that is relocated by applying
179  /// offset \p PCOffset.
180  void addFunctionRange(uint64_t LowPC, uint64_t HighPC, int64_t PCOffset);
181 
182  /// Keep track of a DW_AT_range attribute that we will need to patch up later.
183  void noteRangeAttribute(const DIE &Die, PatchLocation Attr);
184 
185  /// Keep track of a location attribute pointing to a location list in the
186  /// debug_loc section.
187  void noteLocationAttribute(PatchLocation Attr, int64_t PcOffset);
188 
189  /// Add a name accelerator entry for \a Die with \a Name.
191 
192  /// Add a name accelerator entry for \a Die with \a Name.
194  bool SkipPubnamesSection = false);
195 
196  /// Add various accelerator entries for \p Die with \p Name which is stored
197  /// in the string table at \p Offset. \p Name must be an Objective-C
198  /// selector.
200  bool SkipPubnamesSection = false);
201 
202  /// Add a type accelerator entry for \p Die with \p Name which is stored in
203  /// the string table at \p Offset.
205  bool ObjcClassImplementation,
206  uint32_t QualifiedNameHash);
207 
208  struct AccelInfo {
209  /// Name of the entry.
211 
212  /// DIE this entry describes.
213  const DIE *Die;
214 
215  /// Hash of the fully qualified name.
217 
218  /// Emit this entry only in the apple_* sections.
220 
221  /// Is this an ObjC class implementation?
223 
225  bool SkipPubSection = false)
227 
229  uint32_t QualifiedNameHash, bool ObjCClassIsImplementation)
232  ObjcClassImplementation(ObjCClassIsImplementation) {}
233  };
234 
235  const std::vector<AccelInfo> &getPubnames() const { return Pubnames; }
236  const std::vector<AccelInfo> &getPubtypes() const { return Pubtypes; }
237  const std::vector<AccelInfo> &getNamespaces() const { return Namespaces; }
238  const std::vector<AccelInfo> &getObjC() const { return ObjC; }
239 
240  MCSymbol *getLabelBegin() { return LabelBegin; }
241  void setLabelBegin(MCSymbol *S) { LabelBegin = S; }
242 
243 private:
244  DWARFUnit &OrigUnit;
245  unsigned ID;
246  std::vector<DIEInfo> Info; ///< DIE info indexed by DIE index.
247  Optional<BasicDIEUnit> NewUnit;
248  MCSymbol *LabelBegin = nullptr;
249 
250  uint64_t StartOffset;
251  uint64_t NextUnitOffset;
252 
253  uint64_t LowPc = std::numeric_limits<uint64_t>::max();
254  uint64_t HighPc = 0;
255 
256  /// A list of attributes to fixup with the absolute offset of
257  /// a DIE in the debug_info section.
258  ///
259  /// The offsets for the attributes in this array couldn't be set while
260  /// cloning because for cross-cu forward references the target DIE's offset
261  /// isn't known you emit the reference attribute.
262  std::vector<
263  std::tuple<DIE *, const CompileUnit *, DeclContext *, PatchLocation>>
264  ForwardDIEReferences;
265 
266  FunctionIntervals::Allocator RangeAlloc;
267 
268  /// The ranges in that interval map are the PC ranges for
269  /// functions in this unit, associated with the PC offset to apply
270  /// to the addresses to get the linked address.
271  FunctionIntervals Ranges;
272 
273  /// The DW_AT_low_pc of each DW_TAG_label.
275 
276  /// DW_AT_ranges attributes to patch after we have gathered
277  /// all the unit's function addresses.
278  /// @{
279  std::vector<PatchLocation> RangeAttributes;
280  Optional<PatchLocation> UnitRangeAttribute;
281  /// @}
282 
283  /// Location attributes that need to be transferred from the
284  /// original debug_loc section to the liked one. They are stored
285  /// along with the PC offset that is to be applied to their
286  /// function's address.
287  std::vector<std::pair<PatchLocation, int64_t>> LocationAttributes;
288 
289  /// Accelerator entries for the unit, both for the pub*
290  /// sections and the apple* ones.
291  /// @{
292  std::vector<AccelInfo> Pubnames;
293  std::vector<AccelInfo> Pubtypes;
294  std::vector<AccelInfo> Namespaces;
295  std::vector<AccelInfo> ObjC;
296  /// @}
297 
298  /// Is this unit subject to the ODR rule?
299  bool HasODR;
300 
301  /// Did a DIE actually contain a valid reloc?
302  bool HasInterestingContent;
303 
304  /// The DW_AT_language of this unit.
305  uint16_t Language = 0;
306 
307  /// The DW_AT_LLVM_sysroot of this unit.
308  std::string SysRoot;
309 
310  /// If this is a Clang module, this holds the module's name.
311  std::string ClangModuleName;
312 };
313 
314 } // end namespace llvm
315 
316 #endif // LLVM_DWARFLINKER_DWARFLINKERCOMPILEUNIT_H
A DeclContext is a named program scope that is used for ODR uniquing of types.
This class represents lattice values for constants.
Definition: AllocatorList.h:23
DEBUG_TYPE to vector
void setLabelBegin(MCSymbol *S)
MCSymbol - Instances of this class represent a symbol name in the MC file, and MCSymbols are created ...
Definition: MCSymbol.h:41
uint64_t getLowPc() const
AccelInfo(DwarfStringPoolEntryRef Name, const DIE *Die, bool SkipPubSection=false)
bool hasLabelAt(uint64_t Addr) const
Stores all information relating to a compile unit, be it in its original instance in the object file ...
void markEverythingAsKept()
Mark every DIE in this unit as kept.
void addNamespaceAccelerator(const DIE *Die, DwarfStringPoolEntryRef Name)
Add a name accelerator entry for Die with Name.
bool SkipPubSection
Emit this entry only in the apple_* sections.
uint64_t getNextUnitOffset() const
bool InDebugMap
Was this DIE's entity found in the map?
void set(uint64_t New) const
int64_t AddrAdjust
Address offset to apply to the described entity.
const std::vector< PatchLocation > & getRangesAttributes() const
const DIE * getUnitDie() const
Climb up the parent chain to get the compile unit or type unit DIE that this DIE belongs to.
Definition: DIE.cpp:203
uint32_t ParentIdx
The index of this DIE's parent.
uint64_t Addr
PatchLocation()=default
CompileUnit(DWARFUnit &OrigUnit, unsigned ID, bool CanUseODR, StringRef ClangModuleName)
Hold the input and output of the debug info size in bytes.
Definition: DWARFLinker.cpp:38
void noteRangeAttribute(const DIE &Die, PatchLocation Attr)
Keep track of a DW_AT_range attribute that we will need to patch up later.
unsigned getNumDIEs()
Returns the number of DIEs in the unit.
Definition: DWARFUnit.h:436
void addObjCAccelerator(const DIE *Die, DwarfStringPoolEntryRef Name, bool SkipPubnamesSection=false)
Add various accelerator entries for Die with Name which is stored in the string table at Offset.
void addNameAccelerator(const DIE *Die, DwarfStringPoolEntryRef Name, bool SkipPubnamesSection=false)
Add a name accelerator entry for Die with Name.
const std::vector< std::pair< PatchLocation, int64_t > > & getLocationAttributes() const
StringRef getSysRoot()
Return the DW_AT_LLVM_sysroot of the compile unit or an empty StringRef.
Utility class that carries the DWARF compile/type unit and the debug info entry in an object.
Definition: DWARFDie.h:43
unsigned getUniqueID() const
void addTypeAccelerator(const DIE *Die, DwarfStringPoolEntryRef Name, bool ObjcClassImplementation, uint32_t QualifiedNameHash)
Add a type accelerator entry for Die with Name which is stored in the string table at Offset.
typename Sizer::Allocator Allocator
Definition: IntervalMap.h:959
A structured debug information entry.
Definition: DIE.h:722
bool Keep
Is the DIE part of the linked output?
DIE * Clone
Cloned version of that DIE.
uint64_t getStartOffset() const
bool Prune
Is this a pure forward declaration we can strip?
uint64_t computeNextUnitOffset(uint16_t DwarfVersion)
Compute the end offset for this unit.
Optional< PatchLocation > getUnitRangesAttribute() const
PatchLocation(DIE::value_iterator I)
uint32_t QualifiedNameHash
Hash of the fully qualified name.
DeclContext * Ctxt
ODR Declaration context.
DWARFDie getUnitDIE(bool ExtractUnitDIEOnly=true)
Definition: DWARFUnit.h:378
void noteLocationAttribute(PatchLocation Attr, int64_t PcOffset)
Keep track of a location attribute pointing to a location list in the debug_loc section.
DIE * getOutputUnitDIE() const
DIEInfo & getInfo(unsigned Idx)
Align max(MaybeAlign Lhs, Align Rhs)
Definition: Alignment.h:350
const std::string & getClangModuleName() const
const std::vector< AccelInfo > & getPubnames() const
void addLabelLowPc(uint64_t LabelLowPc, int64_t PcOffset)
Add the low_pc of a label that is relocated by applying offset PCOffset.
void fixupForwardReferences()
Apply all fixups recorded by noteForwardReference().
void noteForwardReference(DIE *Die, const CompileUnit *RefUnit, DeclContext *Ctxt, PatchLocation Attr)
Keep track of a forward reference to DIE Die in RefUnit by Attr.
const std::vector< AccelInfo > & getNamespaces() const
const std::vector< AccelInfo > & getObjC() const
DwarfStringPoolEntryRef Name
Name of the entry.
String pool entry reference.
void setStartOffset(uint64_t DebugInfoSize)
An integer value DIE.
Definition: DIE.h:163
const DIE * Die
DIE this entry describes.
const DIEInfo & getInfo(unsigned Idx) const
dwarf::Tag getTag() const
Definition: DWARFDie.h:72
IntervalMap< KeyT, ValT, IntervalMapImpl::NodeSizer< KeyT, ValT >::LeafSize, IntervalMapHalfOpenInfo< KeyT > > HalfOpenIntervalMap
const std::vector< AccelInfo > & getPubtypes() const
size_type count(const_arg_type_t< KeyT > Val) const
Return 1 if the specified key is in the map, 0 otherwise.
Definition: DenseMap.h:145
AccelInfo(DwarfStringPoolEntryRef Name, const DIE *Die, uint32_t QualifiedNameHash, bool ObjCClassIsImplementation)
const FunctionIntervals & getFunctionRanges() const
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
DIE::value_iterator I
bool ObjcClassImplementation
Is this an ObjC class implementation?
bool Incomplete
Does DIE transitively refer an incomplete decl?
uint64_t getHighPc() const
StringRef - Represent a constant reference to a string, i.e.
Definition: StringRef.h:57
Information gathered about a DIE in the object file.
DIEInfo & getInfo(const DWARFDie &Die)
Optional< uint64_t > toUnsigned(const Optional< DWARFFormValue > &V)
Take an optional DWARFFormValue and try to extract an unsigned constant.
void addFunctionRange(uint64_t LowPC, uint64_t HighPC, int64_t PCOffset)
Add a function range [LowPC, HighPC) that is relocated by applying offset PCOffset.
DWARFUnit & getOrigUnit() const