1 //===-- llvm/CodeGen/DwarfDebug.h - Dwarf Debug Framework ------*- C++ -*--===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file contains support for writing dwarf debug info into asm files.
12 //===----------------------------------------------------------------------===//
14 #ifndef LLVM_LIB_CODEGEN_ASMPRINTER_DWARFDEBUG_H
15 #define LLVM_LIB_CODEGEN_ASMPRINTER_DWARFDEBUG_H
17 #include "AsmPrinterHandler.h"
18 #include "DbgValueHistoryCalculator.h"
19 #include "DebugLocEntry.h"
20 #include "DebugLocList.h"
21 #include "DwarfAccelTable.h"
22 #include "DwarfFile.h"
23 #include "llvm/ADT/DenseMap.h"
24 #include "llvm/ADT/FoldingSet.h"
25 #include "llvm/ADT/MapVector.h"
26 #include "llvm/ADT/SmallPtrSet.h"
27 #include "llvm/ADT/StringMap.h"
28 #include "llvm/CodeGen/DIE.h"
29 #include "llvm/CodeGen/LexicalScopes.h"
30 #include "llvm/CodeGen/MachineInstr.h"
31 #include "llvm/IR/DebugInfo.h"
32 #include "llvm/IR/DebugLoc.h"
33 #include "llvm/MC/MCDwarf.h"
34 #include "llvm/MC/MachineLocation.h"
35 #include "llvm/Support/Allocator.h"
44 class DwarfCompileUnit;
48 class MachineModuleInfo;
50 //===----------------------------------------------------------------------===//
51 /// \brief This class is used to record source line correspondence.
53 unsigned Line; // Source line number.
54 unsigned Column; // Source column.
55 unsigned SourceID; // Source ID number.
56 MCSymbol *Label; // Label in code ID number.
58 SrcLineInfo(unsigned L, unsigned C, unsigned S, MCSymbol *label)
59 : Line(L), Column(C), SourceID(S), Label(label) {}
62 unsigned getLine() const { return Line; }
63 unsigned getColumn() const { return Column; }
64 unsigned getSourceID() const { return SourceID; }
65 MCSymbol *getLabel() const { return Label; }
68 //===----------------------------------------------------------------------===//
69 /// \brief This class is used to track local variable information.
71 /// - Variables whose location changes over time have a DotDebugLocOffset and
72 /// the other fields are not used.
74 /// - Variables that are described by multiple MMI table entries have multiple
75 /// expressions and frame indices.
77 DIVariable Var; /// Variable Descriptor.
78 SmallVector<DIExpression, 1> Expr; /// Complex address location expression.
79 DIE *TheDIE; /// Variable DIE.
80 unsigned DotDebugLocOffset; /// Offset in DotDebugLocEntries.
81 const MachineInstr *MInsn; /// DBG_VALUE instruction of the variable.
82 SmallVector<int, 1> FrameIndex; /// Frame index of the variable.
86 /// Construct a DbgVariable from a DIVariable.
87 DbgVariable(DIVariable V, DIExpression E, DwarfDebug *DD, int FI = ~0)
88 : Var(V), Expr(1, E), TheDIE(nullptr), DotDebugLocOffset(~0U),
89 MInsn(nullptr), DD(DD) {
90 FrameIndex.push_back(FI);
92 assert(!E || E->isValid());
95 /// Construct a DbgVariable from a DEBUG_VALUE.
96 /// AbstractVar may be NULL.
97 DbgVariable(const MachineInstr *DbgValue, DwarfDebug *DD)
98 : Var(DbgValue->getDebugVariable()),
99 Expr(1, DbgValue->getDebugExpression()), TheDIE(nullptr),
100 DotDebugLocOffset(~0U), MInsn(DbgValue), DD(DD) {
101 FrameIndex.push_back(~0);
105 DIVariable getVariable() const { return Var; }
106 const ArrayRef<DIExpression> getExpression() const { return Expr; }
107 void setDIE(DIE &D) { TheDIE = &D; }
108 DIE *getDIE() const { return TheDIE; }
109 void setDotDebugLocOffset(unsigned O) { DotDebugLocOffset = O; }
110 unsigned getDotDebugLocOffset() const { return DotDebugLocOffset; }
111 StringRef getName() const { return Var.getName(); }
112 const MachineInstr *getMInsn() const { return MInsn; }
113 const ArrayRef<int> getFrameIndex() const { return FrameIndex; }
115 void addMMIEntry(const DbgVariable &V) {
116 assert( DotDebugLocOffset == ~0U && !MInsn && "not an MMI entry");
117 assert(V.DotDebugLocOffset == ~0U && !V.MInsn && "not an MMI entry");
118 assert(V.Var == Var && "conflicting DIVariable");
120 if (V.getFrameIndex().back() != ~0) {
121 auto E = V.getExpression();
122 auto FI = V.getFrameIndex();
123 Expr.append(E.begin(), E.end());
124 FrameIndex.append(FI.begin(), FI.end());
126 assert(Expr.size() > 1
127 ? std::all_of(Expr.begin(), Expr.end(),
128 [](DIExpression &E) { return E.isBitPiece(); })
129 : (true && "conflicting locations for variable"));
132 // Translate tag to proper Dwarf tag.
133 dwarf::Tag getTag() const {
134 if (Var.getTag() == dwarf::DW_TAG_arg_variable)
135 return dwarf::DW_TAG_formal_parameter;
137 return dwarf::DW_TAG_variable;
139 /// \brief Return true if DbgVariable is artificial.
140 bool isArtificial() const {
141 if (Var.isArtificial())
143 if (getType().isArtificial())
148 bool isObjectPointer() const {
149 if (Var.isObjectPointer())
151 if (getType().isObjectPointer())
156 bool variableHasComplexAddress() const {
157 assert(Var.isVariable() && "Invalid complex DbgVariable!");
158 assert(Expr.size() == 1 &&
159 "variableHasComplexAddress() invoked on multi-FI variable");
160 return Expr.back().getNumElements() > 0;
162 bool isBlockByrefVariable() const;
163 DIType getType() const;
166 /// resolve - Look in the DwarfDebug map for the MDNode that
167 /// corresponds to the reference.
168 template <typename T> T resolve(DIRef<T> Ref) const;
172 /// \brief Helper used to pair up a symbol and its DWARF compile unit.
174 SymbolCU(DwarfCompileUnit *CU, const MCSymbol *Sym) : Sym(Sym), CU(CU) {}
176 DwarfCompileUnit *CU;
179 /// \brief Collects and handles dwarf debug information.
180 class DwarfDebug : public AsmPrinterHandler {
181 // Target of Dwarf emission.
184 // Collected machine module information.
185 MachineModuleInfo *MMI;
187 // All DIEValues are allocated through this allocator.
188 BumpPtrAllocator DIEValueAllocator;
190 // Maps MDNode with its corresponding DwarfCompileUnit.
191 MapVector<const MDNode *, DwarfCompileUnit *> CUMap;
193 // Maps subprogram MDNode with its corresponding DwarfCompileUnit.
194 MapVector<const MDNode *, DwarfCompileUnit *> SPMap;
196 // Maps a CU DIE with its corresponding DwarfCompileUnit.
197 DenseMap<const DIE *, DwarfCompileUnit *> CUDieMap;
199 // List of all labels used in aranges generation.
200 std::vector<SymbolCU> ArangeLabels;
202 // Size of each symbol emitted (for those symbols that have a specific size).
203 DenseMap<const MCSymbol *, uint64_t> SymSize;
205 LexicalScopes LScopes;
207 // Collection of abstract variables.
208 DenseMap<const MDNode *, std::unique_ptr<DbgVariable>> AbstractVariables;
209 SmallVector<std::unique_ptr<DbgVariable>, 64> ConcreteVariables;
211 // Collection of DebugLocEntry. Stored in a linked list so that DIELocLists
212 // can refer to them in spite of insertions into this list.
213 SmallVector<DebugLocList, 4> DotDebugLocEntries;
215 // This is a collection of subprogram MDNodes that are processed to
217 SmallPtrSet<const MDNode *, 16> ProcessedSPNodes;
219 // Maps instruction with label emitted before instruction.
220 DenseMap<const MachineInstr *, MCSymbol *> LabelsBeforeInsn;
222 // Maps instruction with label emitted after instruction.
223 DenseMap<const MachineInstr *, MCSymbol *> LabelsAfterInsn;
225 // History of DBG_VALUE and clobber instructions for each user variable.
226 // Variables are listed in order of appearance.
227 DbgValueHistoryMap DbgValues;
229 // Previous instruction's location information. This is used to determine
230 // label location to indicate scope boundries in dwarf debug info.
231 DebugLoc PrevInstLoc;
234 // This location indicates end of function prologue and beginning of function
236 DebugLoc PrologEndLoc;
238 // If nonnull, stores the current machine function we're processing.
239 const MachineFunction *CurFn;
241 // If nonnull, stores the current machine instruction we're processing.
242 const MachineInstr *CurMI;
244 // If nonnull, stores the CU in which the previous subprogram was contained.
245 const DwarfCompileUnit *PrevCU;
247 // As an optimization, there is no need to emit an entry in the directory
248 // table for the same directory as DW_AT_comp_dir.
249 StringRef CompilationDir;
251 // Counter for assigning globally unique IDs for ranges.
252 unsigned GlobalRangeCount;
254 // Holder for the file specific debug information.
255 DwarfFile InfoHolder;
257 // Holders for the various debug information flags that we might need to
258 // have exposed. See accessor functions below for description.
260 // Holder for imported entities.
261 typedef SmallVector<std::pair<const MDNode *, const MDNode *>, 32>
263 ImportedEntityMap ScopesWithImportedEntities;
265 // Map from MDNodes for user-defined types to the type units that describe
267 DenseMap<const MDNode *, const DwarfTypeUnit *> DwarfTypeUnits;
269 SmallVector<std::pair<std::unique_ptr<DwarfTypeUnit>, DICompositeType>, 1>
270 TypeUnitsUnderConstruction;
272 // Whether to emit the pubnames/pubtypes sections.
273 bool HasDwarfPubSections;
275 // Whether or not to use AT_ranges for compilation units.
278 // Whether we emitted a function into a section other than the default
280 bool UsedNonDefaultText;
282 // Whether to use the GNU TLS opcode (instead of the standard opcode).
283 bool UseGNUTLSOpcode;
285 // Version of dwarf we're emitting.
286 unsigned DwarfVersion;
288 // Maps from a type identifier to the actual MDNode.
289 DITypeIdentifierMap TypeIdentifierMap;
291 // DWARF5 Experimental Options
292 bool HasDwarfAccelTables;
295 // Separated Dwarf Variables
296 // In general these will all be for bits that are left in the
297 // original object file, rather than things that are meant
298 // to be in the .dwo sections.
300 // Holder for the skeleton information.
301 DwarfFile SkeletonHolder;
303 /// Store file names for type units under fission in a line table header that
304 /// will be emitted into debug_line.dwo.
305 // FIXME: replace this with a map from comp_dir to table so that we can emit
306 // multiple tables during LTO each of which uses directory 0, referencing the
307 // comp_dir of all the type units that use it.
308 MCDwarfDwoLineTable SplitTypeUnitFileTable;
310 // True iff there are multiple CUs in this module.
315 AddressPool AddrPool;
317 DwarfAccelTable AccelNames;
318 DwarfAccelTable AccelObjC;
319 DwarfAccelTable AccelNamespace;
320 DwarfAccelTable AccelTypes;
322 DenseMap<const Function *, DISubprogram> FunctionDIs;
324 MCDwarfDwoLineTable *getDwoLineTable(const DwarfCompileUnit &);
326 const SmallVectorImpl<std::unique_ptr<DwarfUnit>> &getUnits() {
327 return InfoHolder.getUnits();
330 /// \brief Find abstract variable associated with Var.
331 DbgVariable *getExistingAbstractVariable(const DIVariable &DV,
332 DIVariable &Cleansed);
333 DbgVariable *getExistingAbstractVariable(const DIVariable &DV);
334 void createAbstractVariable(const DIVariable &DV, LexicalScope *Scope);
335 void ensureAbstractVariableIsCreated(const DIVariable &Var,
336 const MDNode *Scope);
337 void ensureAbstractVariableIsCreatedIfScoped(const DIVariable &Var,
338 const MDNode *Scope);
340 /// \brief Construct a DIE for this abstract scope.
341 void constructAbstractSubprogramScopeDIE(LexicalScope *Scope);
343 /// \brief Compute the size and offset of a DIE given an incoming Offset.
344 unsigned computeSizeAndOffset(DIE *Die, unsigned Offset);
346 /// \brief Compute the size and offset of all the DIEs.
347 void computeSizeAndOffsets();
349 /// \brief Collect info for variables that were optimized out.
350 void collectDeadVariables();
352 void finishVariableDefinitions();
354 void finishSubprogramDefinitions();
356 /// \brief Finish off debug information after all functions have been
358 void finalizeModuleInfo();
360 /// \brief Emit the debug info section.
361 void emitDebugInfo();
363 /// \brief Emit the abbreviation section.
364 void emitAbbreviations();
366 /// \brief Emit a specified accelerator table.
367 void emitAccel(DwarfAccelTable &Accel, const MCSection *Section,
368 StringRef TableName);
370 /// \brief Emit visible names into a hashed accelerator table section.
371 void emitAccelNames();
373 /// \brief Emit objective C classes and categories into a hashed
374 /// accelerator table section.
375 void emitAccelObjC();
377 /// \brief Emit namespace dies into a hashed accelerator table.
378 void emitAccelNamespaces();
380 /// \brief Emit type dies into a hashed accelerator table.
381 void emitAccelTypes();
383 /// \brief Emit visible names into a debug pubnames section.
384 /// \param GnuStyle determines whether or not we want to emit
385 /// additional information into the table ala newer gcc for gdb
387 void emitDebugPubNames(bool GnuStyle = false);
389 /// \brief Emit visible types into a debug pubtypes section.
390 /// \param GnuStyle determines whether or not we want to emit
391 /// additional information into the table ala newer gcc for gdb
393 void emitDebugPubTypes(bool GnuStyle = false);
395 void emitDebugPubSection(
396 bool GnuStyle, const MCSection *PSec, StringRef Name,
397 const StringMap<const DIE *> &(DwarfCompileUnit::*Accessor)() const);
399 /// \brief Emit visible names into a debug str section.
402 /// \brief Emit visible names into a debug loc section.
405 /// \brief Emit visible names into a debug loc dwo section.
406 void emitDebugLocDWO();
408 /// \brief Emit visible names into a debug aranges section.
409 void emitDebugARanges();
411 /// \brief Emit visible names into a debug ranges section.
412 void emitDebugRanges();
414 /// \brief Emit inline info using custom format.
415 void emitDebugInlineInfo();
417 /// DWARF 5 Experimental Split Dwarf Emitters
419 /// \brief Initialize common features of skeleton units.
420 void initSkeletonUnit(const DwarfUnit &U, DIE &Die,
421 std::unique_ptr<DwarfUnit> NewU);
423 /// \brief Construct the split debug info compile unit for the debug info
425 DwarfCompileUnit &constructSkeletonCU(const DwarfCompileUnit &CU);
427 /// \brief Construct the split debug info compile unit for the debug info
429 DwarfTypeUnit &constructSkeletonTU(DwarfTypeUnit &TU);
431 /// \brief Emit the debug info dwo section.
432 void emitDebugInfoDWO();
434 /// \brief Emit the debug abbrev dwo section.
435 void emitDebugAbbrevDWO();
437 /// \brief Emit the debug line dwo section.
438 void emitDebugLineDWO();
440 /// \brief Emit the debug str dwo section.
441 void emitDebugStrDWO();
443 /// Flags to let the linker know we have emitted new style pubnames. Only
444 /// emit it here if we don't have a skeleton CU for split dwarf.
445 void addGnuPubAttributes(DwarfUnit &U, DIE &D) const;
447 /// \brief Create new DwarfCompileUnit for the given metadata node with tag
448 /// DW_TAG_compile_unit.
449 DwarfCompileUnit &constructDwarfCompileUnit(DICompileUnit DIUnit);
451 /// \brief Construct imported_module or imported_declaration DIE.
452 void constructAndAddImportedEntityDIE(DwarfCompileUnit &TheCU,
455 /// \brief Register a source line with debug info. Returns the unique
456 /// label that was emitted and which provides correspondence to the
457 /// source line list.
458 void recordSourceLine(unsigned Line, unsigned Col, const MDNode *Scope,
461 /// \brief Indentify instructions that are marking the beginning of or
462 /// ending of a scope.
463 void identifyScopeMarkers();
465 /// \brief Populate LexicalScope entries with variables' info.
466 void collectVariableInfo(DwarfCompileUnit &TheCU, DISubprogram SP,
467 SmallPtrSetImpl<const MDNode *> &ProcessedVars);
469 /// \brief Build the location list for all DBG_VALUEs in the
470 /// function that describe the same variable.
471 void buildLocationList(SmallVectorImpl<DebugLocEntry> &DebugLoc,
472 const DbgValueHistoryMap::InstrRanges &Ranges);
474 /// \brief Collect variable information from the side table maintained
476 void collectVariableInfoFromMMITable(SmallPtrSetImpl<const MDNode *> &P);
478 /// \brief Ensure that a label will be emitted before MI.
479 void requestLabelBeforeInsn(const MachineInstr *MI) {
480 LabelsBeforeInsn.insert(std::make_pair(MI, nullptr));
483 /// \brief Ensure that a label will be emitted after MI.
484 void requestLabelAfterInsn(const MachineInstr *MI) {
485 LabelsAfterInsn.insert(std::make_pair(MI, nullptr));
489 //===--------------------------------------------------------------------===//
490 // Main entry points.
492 DwarfDebug(AsmPrinter *A, Module *M);
494 ~DwarfDebug() override;
496 /// \brief Emit all Dwarf sections that should come prior to the
500 /// \brief Emit all Dwarf sections that should come after the content.
501 void endModule() override;
503 /// \brief Gather pre-function debug information.
504 void beginFunction(const MachineFunction *MF) override;
506 /// \brief Gather and emit post-function debug information.
507 void endFunction(const MachineFunction *MF) override;
509 /// \brief Process beginning of an instruction.
510 void beginInstruction(const MachineInstr *MI) override;
512 /// \brief Process end of an instruction.
513 void endInstruction() override;
515 /// \brief Add a DIE to the set of types that we're going to pull into
517 void addDwarfTypeUnitType(DwarfCompileUnit &CU, StringRef Identifier,
518 DIE &Die, DICompositeType CTy);
520 /// \brief Add a label so that arange data can be generated for it.
521 void addArangeLabel(SymbolCU SCU) { ArangeLabels.push_back(SCU); }
523 /// \brief For symbols that have a size designated (e.g. common symbols),
524 /// this tracks that size.
525 void setSymbolSize(const MCSymbol *Sym, uint64_t Size) override {
529 /// \brief Returns whether to use DW_OP_GNU_push_tls_address, instead of the
530 /// standard DW_OP_form_tls_address opcode
531 bool useGNUTLSOpcode() const { return UseGNUTLSOpcode; }
533 // Experimental DWARF5 features.
535 /// \brief Returns whether or not to emit tables that dwarf consumers can
536 /// use to accelerate lookup.
537 bool useDwarfAccelTables() const { return HasDwarfAccelTables; }
539 /// \brief Returns whether or not to change the current debug info for the
540 /// split dwarf proposal support.
541 bool useSplitDwarf() const { return HasSplitDwarf; }
543 /// Returns the Dwarf Version.
544 unsigned getDwarfVersion() const { return DwarfVersion; }
546 /// Returns the previous CU that was being updated
547 const DwarfCompileUnit *getPrevCU() const { return PrevCU; }
548 void setPrevCU(const DwarfCompileUnit *PrevCU) { this->PrevCU = PrevCU; }
550 /// Returns the entries for the .debug_loc section.
551 const SmallVectorImpl<DebugLocList> &
552 getDebugLocEntries() const {
553 return DotDebugLocEntries;
556 /// \brief Emit an entry for the debug loc section. This can be used to
557 /// handle an entry that's going to be emitted into the debug loc section.
558 void emitDebugLocEntry(ByteStreamer &Streamer,
559 const DebugLocEntry &Entry);
560 /// \brief emit a single value for the debug loc section.
561 void emitDebugLocValue(ByteStreamer &Streamer,
562 const DebugLocEntry::Value &Value,
563 unsigned PieceOffsetInBits = 0);
564 /// Emits an optimal (=sorted) sequence of DW_OP_pieces.
565 void emitLocPieces(ByteStreamer &Streamer,
566 const DITypeIdentifierMap &Map,
567 ArrayRef<DebugLocEntry::Value> Values);
569 /// Emit the location for a debug loc entry, including the size header.
570 void emitDebugLocEntryLocation(const DebugLocEntry &Entry);
572 /// Find the MDNode for the given reference.
573 template <typename T> T resolve(DIRef<T> Ref) const {
574 return Ref.resolve(TypeIdentifierMap);
577 /// \brief Return the TypeIdentifierMap.
578 const DITypeIdentifierMap &getTypeIdentifierMap() const {
579 return TypeIdentifierMap;
582 /// Find the DwarfCompileUnit for the given CU Die.
583 DwarfCompileUnit *lookupUnit(const DIE *CU) const {
584 return CUDieMap.lookup(CU);
586 /// isSubprogramContext - Return true if Context is either a subprogram
587 /// or another context nested inside a subprogram.
588 bool isSubprogramContext(const MDNode *Context);
590 void addSubprogramNames(DISubprogram SP, DIE &Die);
592 AddressPool &getAddressPool() { return AddrPool; }
594 void addAccelName(StringRef Name, const DIE &Die);
596 void addAccelObjC(StringRef Name, const DIE &Die);
598 void addAccelNamespace(StringRef Name, const DIE &Die);
600 void addAccelType(StringRef Name, const DIE &Die, char Flags);
602 const MachineFunction *getCurrentFunction() const { return CurFn; }
604 iterator_range<ImportedEntityMap::const_iterator>
605 findImportedEntitiesForScope(const MDNode *Scope) const {
606 return make_range(std::equal_range(
607 ScopesWithImportedEntities.begin(), ScopesWithImportedEntities.end(),
608 std::pair<const MDNode *, const MDNode *>(Scope, nullptr),
612 /// \brief A helper function to check whether the DIE for a given Scope is
613 /// going to be null.
614 bool isLexicalScopeDIENull(LexicalScope *Scope);
616 /// \brief Return Label preceding the instruction.
617 MCSymbol *getLabelBeforeInsn(const MachineInstr *MI);
619 /// \brief Return Label immediately following the instruction.
620 MCSymbol *getLabelAfterInsn(const MachineInstr *MI);
622 // FIXME: Consider rolling ranges up into DwarfDebug since we use a single
623 // range_base anyway, so there's no need to keep them as separate per-CU range
624 // lists. (though one day we might end up with a range.dwo section, in which
625 // case it'd go to DwarfFile)
626 unsigned getNextRangeNumber() { return GlobalRangeCount++; }
628 // FIXME: Sink these functions down into DwarfFile/Dwarf*Unit.
630 SmallPtrSet<const MDNode *, 16> &getProcessedSPNodes() {
631 return ProcessedSPNodes;
634 } // End of namespace llvm