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AsmPrinterDwarf.cpp
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1 //===-- AsmPrinterDwarf.cpp - AsmPrinter Dwarf Support --------------------===//
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 implements the Dwarf emissions parts of AsmPrinter.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "ByteStreamer.h"
15 #include "DwarfDebug.h"
16 #include "DwarfExpression.h"
17 #include "llvm/ADT/Twine.h"
20 #include "llvm/CodeGen/DIE.h"
23 #include "llvm/IR/DataLayout.h"
24 #include "llvm/MC/MCAsmInfo.h"
25 #include "llvm/MC/MCRegisterInfo.h"
26 #include "llvm/MC/MCSection.h"
27 #include "llvm/MC/MCStreamer.h"
28 #include "llvm/MC/MCSymbol.h"
34 using namespace llvm;
35 
36 #define DEBUG_TYPE "asm-printer"
37 
38 //===----------------------------------------------------------------------===//
39 // Dwarf Emission Helper Routines
40 //===----------------------------------------------------------------------===//
41 
42 /// EmitSLEB128 - emit the specified signed leb128 value.
43 void AsmPrinter::EmitSLEB128(int64_t Value, const char *Desc) const {
44  if (isVerbose() && Desc)
45  OutStreamer->AddComment(Desc);
46 
47  OutStreamer->EmitSLEB128IntValue(Value);
48 }
49 
50 /// EmitULEB128 - emit the specified unsigned leb128 value.
51 void AsmPrinter::EmitULEB128(uint64_t Value, const char *Desc,
52  unsigned PadTo) const {
53  if (isVerbose() && Desc)
54  OutStreamer->AddComment(Desc);
55 
56  OutStreamer->EmitULEB128IntValue(Value, PadTo);
57 }
58 
59 static const char *DecodeDWARFEncoding(unsigned Encoding) {
60  switch (Encoding) {
62  return "absptr";
64  return "omit";
66  return "pcrel";
68  return "udata4";
70  return "udata8";
72  return "sdata4";
74  return "sdata8";
76  return "pcrel udata4";
78  return "pcrel sdata4";
80  return "pcrel udata8";
82  return "pcrel sdata8";
84  :
85  return "indirect pcrel udata4";
87  :
88  return "indirect pcrel sdata4";
90  :
91  return "indirect pcrel udata8";
93  :
94  return "indirect pcrel sdata8";
95  }
96 
97  return "<unknown encoding>";
98 }
99 
100 /// EmitEncodingByte - Emit a .byte 42 directive that corresponds to an
101 /// encoding. If verbose assembly output is enabled, we output comments
102 /// describing the encoding. Desc is an optional string saying what the
103 /// encoding is specifying (e.g. "LSDA").
104 void AsmPrinter::EmitEncodingByte(unsigned Val, const char *Desc) const {
105  if (isVerbose()) {
106  if (Desc)
107  OutStreamer->AddComment(Twine(Desc) + " Encoding = " +
108  Twine(DecodeDWARFEncoding(Val)));
109  else
110  OutStreamer->AddComment(Twine("Encoding = ") + DecodeDWARFEncoding(Val));
111  }
112 
113  OutStreamer->EmitIntValue(Val, 1);
114 }
115 
116 /// GetSizeOfEncodedValue - Return the size of the encoding in bytes.
117 unsigned AsmPrinter::GetSizeOfEncodedValue(unsigned Encoding) const {
118  if (Encoding == dwarf::DW_EH_PE_omit)
119  return 0;
120 
121  switch (Encoding & 0x07) {
122  default:
123  llvm_unreachable("Invalid encoded value.");
125  return MF->getDataLayout().getPointerSize();
127  return 2;
129  return 4;
131  return 8;
132  }
133 }
134 
136  unsigned Encoding) const {
137  if (GV) {
139 
140  const MCExpr *Exp =
141  TLOF.getTTypeGlobalReference(GV, Encoding, TM, MMI, *OutStreamer);
142  OutStreamer->EmitValue(Exp, GetSizeOfEncodedValue(Encoding));
143  } else
144  OutStreamer->EmitIntValue(0, GetSizeOfEncodedValue(Encoding));
145 }
146 
148  bool ForceOffset) const {
149  if (!ForceOffset) {
150  // On COFF targets, we have to emit the special .secrel32 directive.
152  OutStreamer->EmitCOFFSecRel32(Label, /*Offset=*/0);
153  return;
154  }
155 
156  // If the format uses relocations with dwarf, refer to the symbol directly.
158  OutStreamer->EmitSymbolValue(Label, 4);
159  return;
160  }
161  }
162 
163  // Otherwise, emit it as a label difference from the start of the section.
164  EmitLabelDifference(Label, Label->getSection().getBeginSymbol(), 4);
165 }
166 
170  return;
171  }
172 
173  // Just emit the offset directly; no need for symbol math.
174  EmitInt32(S.getOffset());
175 }
176 
177 //===----------------------------------------------------------------------===//
178 // Dwarf Lowering Routines
179 //===----------------------------------------------------------------------===//
180 
182  switch (Inst.getOperation()) {
183  default:
184  llvm_unreachable("Unexpected instruction");
186  OutStreamer->EmitCFIDefCfaOffset(Inst.getOffset());
187  break;
189  OutStreamer->EmitCFIAdjustCfaOffset(Inst.getOffset());
190  break;
192  OutStreamer->EmitCFIDefCfa(Inst.getRegister(), Inst.getOffset());
193  break;
195  OutStreamer->EmitCFIDefCfaRegister(Inst.getRegister());
196  break;
198  OutStreamer->EmitCFIOffset(Inst.getRegister(), Inst.getOffset());
199  break;
201  OutStreamer->EmitCFIRegister(Inst.getRegister(), Inst.getRegister2());
202  break;
204  OutStreamer->EmitCFIWindowSave();
205  break;
207  OutStreamer->EmitCFISameValue(Inst.getRegister());
208  break;
210  OutStreamer->EmitCFIGnuArgsSize(Inst.getOffset());
211  break;
213  OutStreamer->EmitCFIEscape(Inst.getValues());
214  break;
215  }
216 }
217 
218 void AsmPrinter::emitDwarfDIE(const DIE &Die) const {
219  // Emit the code (index) for the abbreviation.
220  if (isVerbose())
221  OutStreamer->AddComment("Abbrev [" + Twine(Die.getAbbrevNumber()) + "] 0x" +
222  Twine::utohexstr(Die.getOffset()) + ":0x" +
223  Twine::utohexstr(Die.getSize()) + " " +
224  dwarf::TagString(Die.getTag()));
226 
227  // Emit the DIE attribute values.
228  for (const auto &V : Die.values()) {
229  dwarf::Attribute Attr = V.getAttribute();
230  assert(V.getForm() && "Too many attributes for DIE (check abbreviation)");
231 
232  if (isVerbose()) {
233  OutStreamer->AddComment(dwarf::AttributeString(Attr));
234  if (Attr == dwarf::DW_AT_accessibility)
235  OutStreamer->AddComment(
236  dwarf::AccessibilityString(V.getDIEInteger().getValue()));
237  }
238 
239  // Emit an attribute using the defined form.
240  V.EmitValue(this);
241  }
242 
243  // Emit the DIE children if any.
244  if (Die.hasChildren()) {
245  for (auto &Child : Die.children())
246  emitDwarfDIE(Child);
247 
248  OutStreamer->AddComment("End Of Children Mark");
249  EmitInt8(0);
250  }
251 }
252 
253 void AsmPrinter::emitDwarfAbbrev(const DIEAbbrev &Abbrev) const {
254  // Emit the abbreviations code (base 1 index.)
255  EmitULEB128(Abbrev.getNumber(), "Abbreviation Code");
256 
257  // Emit the abbreviations data.
258  Abbrev.Emit(this);
259 }
unsigned getSize() const
Definition: DIE.h:701
const TargetLoweringObjectFile & getObjFileLowering() const
Return information about object file lowering.
Definition: AsmPrinter.cpp:192
std::unique_ptr< MCStreamer > OutStreamer
This is the MCStreamer object for the file we are generating.
Definition: AsmPrinter.h:93
Compute iterated dominance frontiers using a linear time algorithm.
Definition: AllocatorList.h:24
void EmitInt8(int Value) const
Emit a byte directive and value.
MCSymbol - Instances of this class represent a symbol name in the MC file, and MCSymbols are created ...
Definition: MCSymbol.h:42
MCSection & getSection(bool SetUsed=true) const
Get the section associated with a defined, non-absolute symbol.
Definition: MCSymbol.h:268
Attribute
Attributes.
Definition: Dwarf.h:105
child_range children()
Definition: DIE.h:710
const MachineFunction * MF
The current machine function.
Definition: AsmPrinter.h:96
bool hasChildren() const
Definition: DIE.h:702
bool needsDwarfSectionOffsetDirective() const
Definition: MCAsmInfo.h:453
void emitDwarfSymbolReference(const MCSymbol *Label, bool ForceOffset=false) const
Emit a reference to a symbol for use in dwarf.
void emitDwarfStringOffset(DwarfStringPoolEntryRef S) const
Emit the 4-byte offset of a string from the start of its section.
void emitDwarfDIE(const DIE &Die) const
Recursively emit Dwarf DIE tree.
Twine - A lightweight data structure for efficiently representing the concatenation of temporary valu...
Definition: Twine.h:81
String pool entry reference.
Base class for the full range of assembler expressions which are needed for parsing.
Definition: MCExpr.h:36
StringRef AttributeString(unsigned Attribute)
Definition: Dwarf.cpp:72
bool doesDwarfUseRelocationsAcrossSections() const
Definition: MCAsmInfo.h:574
bool isVerbose() const
Return true if assembly output should contain comments.
Definition: AsmPrinter.h:191
MachineModuleInfo * MMI
This is a pointer to the current MachineModuleInfo.
Definition: AsmPrinter.h:99
const DataLayout & getDataLayout() const
Return the DataLayout attached to the Module associated to this MF.
void EmitInt32(int Value) const
Emit a long directive and value.
void Emit(const AsmPrinter *AP) const
Print the abbreviation using the specified asm printer.
Definition: DIE.cpp:68
StringRef AccessibilityString(unsigned Access)
Definition: Dwarf.cpp:255
unsigned getRegister2() const
Definition: MCDwarf.h:480
const MCAsmInfo * MAI
Target Asm Printer information.
Definition: AsmPrinter.h:84
void EmitULEB128(uint64_t Value, const char *Desc=nullptr, unsigned PadTo=0) const
Emit the specified unsigned leb128 value.
value_range values()
Definition: DIE.h:650
unsigned getPointerSize(unsigned AS=0) const
Layout pointer size FIXME: The defaults need to be removed once all of the backends/clients are updat...
Definition: DataLayout.cpp:605
A structured debug information entry.
Definition: DIE.h:662
void EmitEncodingByte(unsigned Val, const char *Desc=nullptr) const
Emit a .byte 42 directive that corresponds to an encoding.
TargetMachine & TM
Target machine description.
Definition: AsmPrinter.h:80
int getOffset() const
Definition: MCDwarf.h:485
OpType getOperation() const
Definition: MCDwarf.h:469
virtual const MCExpr * getTTypeGlobalReference(const GlobalValue *GV, unsigned Encoding, const TargetMachine &TM, MachineModuleInfo *MMI, MCStreamer &Streamer) const
Return an MCExpr to use for a reference to the specified global variable from exception handling info...
StringRef getValues() const
Definition: MCDwarf.h:492
unsigned GetSizeOfEncodedValue(unsigned Encoding) const
Return the size of the encoding in bytes.
#define llvm_unreachable(msg)
Marks that the current location is not supposed to be reachable.
unsigned getRegister() const
Definition: MCDwarf.h:472
void emitCFIInstruction(const MachineInstr &MI)
Definition: AsmPrinter.cpp:919
void EmitSLEB128(int64_t Value, const char *Desc=nullptr) const
Emit the specified signed leb128 value.
static Twine utohexstr(const uint64_t &Val)
Definition: Twine.h:395
MCSymbol * getBeginSymbol()
Definition: MCSection.h:106
void EmitTTypeReference(const GlobalValue *GV, unsigned Encoding) const
Emit reference to a ttype global with a specified encoding.
static const char * DecodeDWARFEncoding(unsigned Encoding)
void emitDwarfAbbrev(const DIEAbbrev &Abbrev) const
dwarf::Tag getTag() const
Definition: DIE.h:698
Dwarf abbreviation, describes the organization of a debug information object.
Definition: DIE.h:79
StringRef TagString(unsigned Tag)
Definition: Dwarf.cpp:21
void EmitLabelDifference(const MCSymbol *Hi, const MCSymbol *Lo, unsigned Size) const
Emit something like ".long Hi-Lo" where the size in bytes of the directive is specified by Size and H...
unsigned getAbbrevNumber() const
Definition: DIE.h:697
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
LLVM Value Representation.
Definition: Value.h:73
unsigned getNumber() const
Definition: DIE.h:101
unsigned getOffset() const
Get the compile/type unit relative offset of this DIE.
Definition: DIE.h:700