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AsmPrinterDwarf.cpp
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1 //===-- AsmPrinterDwarf.cpp - AsmPrinter Dwarf Support --------------------===//
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 // This file implements the Dwarf emissions parts of AsmPrinter.
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #include "ByteStreamer.h"
14 #include "llvm/ADT/Twine.h"
17 #include "llvm/CodeGen/DIE.h"
19 #include "llvm/IR/DataLayout.h"
20 #include "llvm/MC/MCAsmInfo.h"
21 #include "llvm/MC/MCDwarf.h"
22 #include "llvm/MC/MCRegisterInfo.h"
23 #include "llvm/MC/MCSection.h"
24 #include "llvm/MC/MCStreamer.h"
25 #include "llvm/MC/MCSymbol.h"
30 using namespace llvm;
31 
32 #define DEBUG_TYPE "asm-printer"
33 
34 //===----------------------------------------------------------------------===//
35 // Dwarf Emission Helper Routines
36 //===----------------------------------------------------------------------===//
37 
38 /// EmitSLEB128 - emit the specified signed leb128 value.
39 void AsmPrinter::EmitSLEB128(int64_t Value, const char *Desc) const {
40  if (isVerbose() && Desc)
41  OutStreamer->AddComment(Desc);
42 
43  OutStreamer->EmitSLEB128IntValue(Value);
44 }
45 
46 void AsmPrinter::EmitULEB128(uint64_t Value, const char *Desc, unsigned PadTo) const {
47  if (isVerbose() && Desc)
48  OutStreamer->AddComment(Desc);
49 
50  OutStreamer->EmitULEB128IntValue(Value, PadTo);
51 }
52 
53 /// Emit something like ".uleb128 Hi-Lo".
55  const MCSymbol *Lo) const {
56  OutStreamer->emitAbsoluteSymbolDiffAsULEB128(Hi, Lo);
57 }
58 
59 static const char *DecodeDWARFEncoding(unsigned Encoding) {
60  switch (Encoding) {
62  return "absptr";
64  return "omit";
66  return "pcrel";
68  return "uleb128";
70  return "sleb128";
72  return "udata4";
74  return "udata8";
76  return "sdata4";
78  return "sdata8";
80  return "pcrel udata4";
82  return "pcrel sdata4";
84  return "pcrel udata8";
86  return "pcrel sdata8";
88  :
89  return "indirect pcrel udata4";
91  :
92  return "indirect pcrel sdata4";
94  :
95  return "indirect pcrel udata8";
97  :
98  return "indirect pcrel sdata8";
99  }
100 
101  return "<unknown encoding>";
102 }
103 
104 /// EmitEncodingByte - Emit a .byte 42 directive that corresponds to an
105 /// encoding. If verbose assembly output is enabled, we output comments
106 /// describing the encoding. Desc is an optional string saying what the
107 /// encoding is specifying (e.g. "LSDA").
108 void AsmPrinter::EmitEncodingByte(unsigned Val, const char *Desc) const {
109  if (isVerbose()) {
110  if (Desc)
111  OutStreamer->AddComment(Twine(Desc) + " Encoding = " +
112  Twine(DecodeDWARFEncoding(Val)));
113  else
114  OutStreamer->AddComment(Twine("Encoding = ") + DecodeDWARFEncoding(Val));
115  }
116 
117  OutStreamer->EmitIntValue(Val, 1);
118 }
119 
120 /// GetSizeOfEncodedValue - Return the size of the encoding in bytes.
121 unsigned AsmPrinter::GetSizeOfEncodedValue(unsigned Encoding) const {
122  if (Encoding == dwarf::DW_EH_PE_omit)
123  return 0;
124 
125  switch (Encoding & 0x07) {
126  default:
127  llvm_unreachable("Invalid encoded value.");
129  return MF->getDataLayout().getPointerSize();
131  return 2;
133  return 4;
135  return 8;
136  }
137 }
138 
140  unsigned Encoding) const {
141  if (GV) {
143 
144  const MCExpr *Exp =
145  TLOF.getTTypeGlobalReference(GV, Encoding, TM, MMI, *OutStreamer);
146  OutStreamer->EmitValue(Exp, GetSizeOfEncodedValue(Encoding));
147  } else
148  OutStreamer->EmitIntValue(0, GetSizeOfEncodedValue(Encoding));
149 }
150 
152  bool ForceOffset) const {
153  if (!ForceOffset) {
154  // On COFF targets, we have to emit the special .secrel32 directive.
156  OutStreamer->EmitCOFFSecRel32(Label, /*Offset=*/0);
157  return;
158  }
159 
160  // If the format uses relocations with dwarf, refer to the symbol directly.
162  OutStreamer->EmitSymbolValue(Label, 4);
163  return;
164  }
165  }
166 
167  // Otherwise, emit it as a label difference from the start of the section.
168  EmitLabelDifference(Label, Label->getSection().getBeginSymbol(), 4);
169 }
170 
173  assert(S.Symbol && "No symbol available");
175  return;
176  }
177 
178  // Just emit the offset directly; no need for symbol math.
179  emitInt32(S.Offset);
180 }
181 
182 void AsmPrinter::EmitDwarfOffset(const MCSymbol *Label, uint64_t Offset) const {
183  EmitLabelPlusOffset(Label, Offset, MAI->getCodePointerSize());
184 }
185 
187  const MCSymbol *Lo,
188  unsigned Encoding) const {
189  // The least significant 3 bits specify the width of the encoding
190  if ((Encoding & 0x7) == dwarf::DW_EH_PE_uleb128)
192  else
193  EmitLabelDifference(Hi, Lo, GetSizeOfEncodedValue(Encoding));
194 }
195 
197  unsigned Encoding) const {
198  // The least significant 3 bits specify the width of the encoding
199  if ((Encoding & 0x7) == dwarf::DW_EH_PE_uleb128)
200  EmitULEB128(Value);
201  else
202  OutStreamer->EmitIntValue(Value, GetSizeOfEncodedValue(Encoding));
203 }
204 
205 //===----------------------------------------------------------------------===//
206 // Dwarf Lowering Routines
207 //===----------------------------------------------------------------------===//
208 
210  switch (Inst.getOperation()) {
211  default:
212  llvm_unreachable("Unexpected instruction");
214  OutStreamer->EmitCFIDefCfaOffset(Inst.getOffset());
215  break;
217  OutStreamer->EmitCFIAdjustCfaOffset(Inst.getOffset());
218  break;
220  OutStreamer->EmitCFIDefCfa(Inst.getRegister(), Inst.getOffset());
221  break;
223  OutStreamer->EmitCFIDefCfaRegister(Inst.getRegister());
224  break;
226  OutStreamer->EmitCFIOffset(Inst.getRegister(), Inst.getOffset());
227  break;
229  OutStreamer->EmitCFIRegister(Inst.getRegister(), Inst.getRegister2());
230  break;
232  OutStreamer->EmitCFIWindowSave();
233  break;
235  OutStreamer->EmitCFINegateRAState();
236  break;
238  OutStreamer->EmitCFISameValue(Inst.getRegister());
239  break;
241  OutStreamer->EmitCFIGnuArgsSize(Inst.getOffset());
242  break;
244  OutStreamer->EmitCFIEscape(Inst.getValues());
245  break;
247  OutStreamer->EmitCFIRestore(Inst.getRegister());
248  break;
249  }
250 }
251 
252 void AsmPrinter::emitDwarfDIE(const DIE &Die) const {
253  // Emit the code (index) for the abbreviation.
254  if (isVerbose())
255  OutStreamer->AddComment("Abbrev [" + Twine(Die.getAbbrevNumber()) + "] 0x" +
256  Twine::utohexstr(Die.getOffset()) + ":0x" +
257  Twine::utohexstr(Die.getSize()) + " " +
258  dwarf::TagString(Die.getTag()));
260 
261  // Emit the DIE attribute values.
262  for (const auto &V : Die.values()) {
263  dwarf::Attribute Attr = V.getAttribute();
264  assert(V.getForm() && "Too many attributes for DIE (check abbreviation)");
265 
266  if (isVerbose()) {
267  OutStreamer->AddComment(dwarf::AttributeString(Attr));
268  if (Attr == dwarf::DW_AT_accessibility)
269  OutStreamer->AddComment(
270  dwarf::AccessibilityString(V.getDIEInteger().getValue()));
271  }
272 
273  // Emit an attribute using the defined form.
274  V.EmitValue(this);
275  }
276 
277  // Emit the DIE children if any.
278  if (Die.hasChildren()) {
279  for (auto &Child : Die.children())
280  emitDwarfDIE(Child);
281 
282  OutStreamer->AddComment("End Of Children Mark");
283  emitInt8(0);
284  }
285 }
286 
287 void AsmPrinter::emitDwarfAbbrev(const DIEAbbrev &Abbrev) const {
288  // Emit the abbreviations code (base 1 index.)
289  EmitULEB128(Abbrev.getNumber(), "Abbreviation Code");
290 
291  // Emit the abbreviations data.
292  Abbrev.Emit(this);
293 }
void EmitCallSiteOffset(const MCSymbol *Hi, const MCSymbol *Lo, unsigned Encoding) const
Emit reference to a call site with a specified encoding.
unsigned getSize() const
Definition: DIE.h:751
const TargetLoweringObjectFile & getObjFileLowering() const
Return information about object file lowering.
Definition: AsmPrinter.cpp:216
std::unique_ptr< MCStreamer > OutStreamer
This is the MCStreamer object for the file we are generating.
Definition: AsmPrinter.h:93
This class represents lattice values for constants.
Definition: AllocatorList.h:23
MCSymbol - Instances of this class represent a symbol name in the MC file, and MCSymbols are created ...
Definition: MCSymbol.h:41
Attribute
Attributes.
Definition: Dwarf.h:102
child_range children()
Definition: DIE.h:760
bool hasChildren() const
Definition: DIE.h:752
bool needsDwarfSectionOffsetDirective() const
Definition: MCAsmInfo.h:478
void emitDwarfSymbolReference(const MCSymbol *Label, bool ForceOffset=false) const
Emit a reference to a symbol for use in dwarf.
MachineFunction * MF
The current machine function.
Definition: AsmPrinter.h:96
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:80
Base class for the full range of assembler expressions which are needed for parsing.
Definition: MCExpr.h:35
StringRef AttributeString(unsigned Attribute)
Definition: Dwarf.cpp:72
bool doesDwarfUseRelocationsAcrossSections() const
Definition: MCAsmInfo.h:613
bool isVerbose() const
Return true if assembly output should contain comments.
Definition: AsmPrinter.h:203
Data for a string pool entry.
void EmitLabelDifferenceAsULEB128(const MCSymbol *Hi, const MCSymbol *Lo) const
Emit something like ".uleb128 Hi-Lo".
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 EmitLabelPlusOffset(const MCSymbol *Label, uint64_t Offset, unsigned Size, bool IsSectionRelative=false) const
Emit something like ".long Label+Offset" where the size in bytes of the directive is specified by Siz...
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:264
unsigned getRegister2() const
Definition: MCDwarf.h:588
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:700
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:654
A structured debug information entry.
Definition: DIE.h:712
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:81
int getOffset() const
Definition: MCDwarf.h:593
OpType getOperation() const
Definition: MCDwarf.h:577
void EmitCallSiteValue(uint64_t Value, unsigned Encoding) const
Emit an integer value corresponding to the call site encoding.
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:600
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:580
void emitCFIInstruction(const MachineInstr &MI)
Definition: AsmPrinter.cpp:953
void EmitSLEB128(int64_t Value, const char *Desc=nullptr) const
Emit the specified signed leb128 value.
void emitDwarfStringOffset(DwarfStringPoolEntry S) const
Emit the 4-byte offset of a string from the start of its section.
static Twine utohexstr(const uint64_t &Val)
Definition: Twine.h:387
MCSymbol * getBeginSymbol()
Definition: MCSection.h:110
void EmitTTypeReference(const GlobalValue *GV, unsigned Encoding) const
Emit reference to a ttype global with a specified encoding.
void emitInt32(int Value) const
Emit a long directive and value.
static const char * DecodeDWARFEncoding(unsigned Encoding)
This file contains constants used for implementing Dwarf debug support.
MCSection & getSection() const
Get the section associated with a defined, non-absolute symbol.
Definition: MCSymbol.h:268
void emitDwarfAbbrev(const DIEAbbrev &Abbrev) const
dwarf::Tag getTag() const
Definition: DIE.h:748
Dwarf abbreviation, describes the organization of a debug information object.
Definition: DIE.h:79
StringRef TagString(unsigned Tag)
Definition: Dwarf.cpp:21
void EmitDwarfOffset(const MCSymbol *Label, uint64_t Offset) const
Emit something like ".long Label + Offset".
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 getCodePointerSize() const
Get the code pointer size in bytes.
Definition: MCAsmInfo.h:407
unsigned getAbbrevNumber() const
Definition: DIE.h:747
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
void emitInt8(int Value) const
Emit a byte directive and value.
LLVM Value Representation.
Definition: Value.h:74
unsigned getNumber() const
Definition: DIE.h:101
unsigned getOffset() const
Get the compile/type unit relative offset of this DIE.
Definition: DIE.h:750