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"
18#include "llvm/CodeGen/AsmPrinter.h"
19#include "llvm/CodeGen/DIE.h"
20#include "llvm/CodeGen/MachineFunction.h"
21#include "llvm/CodeGen/MachineModuleInfo.h"
22#include "llvm/IR/DataLayout.h"
23#include "llvm/MC/MCAsmInfo.h"
24#include "llvm/MC/MCRegisterInfo.h"
25#include "llvm/MC/MCSection.h"
26#include "llvm/MC/MCStreamer.h"
27#include "llvm/MC/MCSymbol.h"
28#include "llvm/MC/MachineLocation.h"
29#include "llvm/Support/Dwarf.h"
30#include "llvm/Support/ErrorHandling.h"
31#include "llvm/Target/TargetLoweringObjectFile.h"
32#include "llvm/Target/TargetMachine.h"
33#include "llvm/Target/TargetSubtargetInfo.h"
34using 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.
43void 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.
51void 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
59static const char *DecodeDWARFEncoding(unsigned Encoding) {
60  switch (Encoding) {
61  case dwarf::DW_EH_PE_absptr:
62    return "absptr";
63  case dwarf::DW_EH_PE_omit:
64    return "omit";
65  case dwarf::DW_EH_PE_pcrel:
66    return "pcrel";
67  case dwarf::DW_EH_PE_udata4:
68    return "udata4";
69  case dwarf::DW_EH_PE_udata8:
70    return "udata8";
71  case dwarf::DW_EH_PE_sdata4:
72    return "sdata4";
73  case dwarf::DW_EH_PE_sdata8:
74    return "sdata8";
75  case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata4:
76    return "pcrel udata4";
77  case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4:
78    return "pcrel sdata4";
79  case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata8:
80    return "pcrel udata8";
81  case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata8:
82    return "pcrel sdata8";
83  case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata4
84      :
85    return "indirect pcrel udata4";
86  case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4
87      :
88    return "indirect pcrel sdata4";
89  case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata8
90      :
91    return "indirect pcrel udata8";
92  case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata8
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").
104void 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.
117unsigned 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.");
124  case dwarf::DW_EH_PE_absptr:
125    return MF->getDataLayout().getPointerSize();
126  case dwarf::DW_EH_PE_udata2:
127    return 2;
128  case dwarf::DW_EH_PE_udata4:
129    return 4;
130  case dwarf::DW_EH_PE_udata8:
131    return 8;
132  }
133}
134
135void AsmPrinter::EmitTTypeReference(const GlobalValue *GV,
136                                    unsigned Encoding) const {
137  if (GV) {
138    const TargetLoweringObjectFile &TLOF = getObjFileLowering();
139
140    const MCExpr *Exp =
141        TLOF.getTTypeGlobalReference(GV, Encoding, *Mang, TM, MMI,
142                                     *OutStreamer);
143    OutStreamer->EmitValue(Exp, GetSizeOfEncodedValue(Encoding));
144  } else
145    OutStreamer->EmitIntValue(0, GetSizeOfEncodedValue(Encoding));
146}
147
148void AsmPrinter::emitDwarfSymbolReference(const MCSymbol *Label,
149                                          bool ForceOffset) const {
150  if (!ForceOffset) {
151    // On COFF targets, we have to emit the special .secrel32 directive.
152    if (MAI->needsDwarfSectionOffsetDirective()) {
153      OutStreamer->EmitCOFFSecRel32(Label);
154      return;
155    }
156
157    // If the format uses relocations with dwarf, refer to the symbol directly.
158    if (MAI->doesDwarfUseRelocationsAcrossSections()) {
159      OutStreamer->EmitSymbolValue(Label, 4);
160      return;
161    }
162  }
163
164  // Otherwise, emit it as a label difference from the start of the section.
165  EmitLabelDifference(Label, Label->getSection().getBeginSymbol(), 4);
166}
167
168void AsmPrinter::emitDwarfStringOffset(DwarfStringPoolEntryRef S) const {
169  if (MAI->doesDwarfUseRelocationsAcrossSections()) {
170    emitDwarfSymbolReference(S.getSymbol());
171    return;
172  }
173
174  // Just emit the offset directly; no need for symbol math.
175  EmitInt32(S.getOffset());
176}
177
178/// EmitDwarfRegOp - Emit dwarf register operation.
179void AsmPrinter::EmitDwarfRegOp(ByteStreamer &Streamer,
180                                const MachineLocation &MLoc) const {
181  DebugLocDwarfExpression Expr(*MF->getSubtarget().getRegisterInfo(),
182                               getDwarfDebug()->getDwarfVersion(), Streamer);
183  const MCRegisterInfo *MRI = MMI->getContext().getRegisterInfo();
184  int Reg = MRI->getDwarfRegNum(MLoc.getReg(), false);
185  if (Reg < 0) {
186    // We assume that pointers are always in an addressable register.
187    if (MLoc.isIndirect())
188      // FIXME: We have no reasonable way of handling errors in here. The
189      // caller might be in the middle of a dwarf expression. We should
190      // probably assert that Reg >= 0 once debug info generation is more
191      // mature.
192      return Expr.EmitOp(dwarf::DW_OP_nop,
193                         "nop (could not find a dwarf register number)");
194
195    // Attempt to find a valid super- or sub-register.
196    if (!Expr.AddMachineRegPiece(MLoc.getReg()))
197      Expr.EmitOp(dwarf::DW_OP_nop,
198                  "nop (could not find a dwarf register number)");
199    return;
200  }
201
202  if (MLoc.isIndirect())
203    Expr.AddRegIndirect(Reg, MLoc.getOffset());
204  else
205    Expr.AddReg(Reg);
206}
207
208//===----------------------------------------------------------------------===//
209// Dwarf Lowering Routines
210//===----------------------------------------------------------------------===//
211
212void AsmPrinter::emitCFIInstruction(const MCCFIInstruction &Inst) const {
213  switch (Inst.getOperation()) {
214  default:
215    llvm_unreachable("Unexpected instruction");
216  case MCCFIInstruction::OpDefCfaOffset:
217    OutStreamer->EmitCFIDefCfaOffset(Inst.getOffset());
218    break;
219  case MCCFIInstruction::OpAdjustCfaOffset:
220    OutStreamer->EmitCFIAdjustCfaOffset(Inst.getOffset());
221    break;
222  case MCCFIInstruction::OpDefCfa:
223    OutStreamer->EmitCFIDefCfa(Inst.getRegister(), Inst.getOffset());
224    break;
225  case MCCFIInstruction::OpDefCfaRegister:
226    OutStreamer->EmitCFIDefCfaRegister(Inst.getRegister());
227    break;
228  case MCCFIInstruction::OpOffset:
229    OutStreamer->EmitCFIOffset(Inst.getRegister(), Inst.getOffset());
230    break;
231  case MCCFIInstruction::OpRegister:
232    OutStreamer->EmitCFIRegister(Inst.getRegister(), Inst.getRegister2());
233    break;
234  case MCCFIInstruction::OpWindowSave:
235    OutStreamer->EmitCFIWindowSave();
236    break;
237  case MCCFIInstruction::OpSameValue:
238    OutStreamer->EmitCFISameValue(Inst.getRegister());
239    break;
240  case MCCFIInstruction::OpGnuArgsSize:
241    OutStreamer->EmitCFIGnuArgsSize(Inst.getOffset());
242    break;
243  case MCCFIInstruction::OpEscape:
244    OutStreamer->EmitCFIEscape(Inst.getValues());
245    break;
246  }
247}
248
249void AsmPrinter::emitDwarfDIE(const DIE &Die) const {
250  // Emit the code (index) for the abbreviation.
251  if (isVerbose())
252    OutStreamer->AddComment("Abbrev [" + Twine(Die.getAbbrevNumber()) + "] 0x" +
253                            Twine::utohexstr(Die.getOffset()) + ":0x" +
254                            Twine::utohexstr(Die.getSize()) + " " +
255                            dwarf::TagString(Die.getTag()));
256  EmitULEB128(Die.getAbbrevNumber());
257
258  // Emit the DIE attribute values.
259  for (const auto &V : Die.values()) {
260    dwarf::Attribute Attr = V.getAttribute();
261    assert(V.getForm() && "Too many attributes for DIE (check abbreviation)");
262
263    if (isVerbose()) {
264      OutStreamer->AddComment(dwarf::AttributeString(Attr));
265      if (Attr == dwarf::DW_AT_accessibility)
266        OutStreamer->AddComment(
267            dwarf::AccessibilityString(V.getDIEInteger().getValue()));
268    }
269
270    // Emit an attribute using the defined form.
271    V.EmitValue(this);
272  }
273
274  // Emit the DIE children if any.
275  if (Die.hasChildren()) {
276    for (auto &Child : Die.children())
277      emitDwarfDIE(Child);
278
279    OutStreamer->AddComment("End Of Children Mark");
280    EmitInt8(0);
281  }
282}
283
284void AsmPrinter::emitDwarfAbbrev(const DIEAbbrev &Abbrev) const {
285  // Emit the abbreviations code (base 1 index.)
286  EmitULEB128(Abbrev.getNumber(), "Abbreviation Code");
287
288  // Emit the abbreviations data.
289  Abbrev.Emit(this);
290}
291