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 "llvm/ADT/Twine.h"
16 #include "llvm/BinaryFormat/Dwarf.h"
17 #include "llvm/CodeGen/AsmPrinter.h"
18 #include "llvm/CodeGen/DIE.h"
19 #include "llvm/CodeGen/MachineFunction.h"
20 #include "llvm/IR/DataLayout.h"
21 #include "llvm/MC/MCAsmInfo.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"
26 #include "llvm/MC/MachineLocation.h"
27 #include "llvm/Support/ErrorHandling.h"
28 #include "llvm/Target/TargetLoweringObjectFile.h"
29 #include "llvm/Target/TargetMachine.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.
EmitSLEB128(int64_t Value,const char * Desc) const39 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
EmitULEB128(uint64_t Value,const char * Desc) const46 void AsmPrinter::EmitULEB128(uint64_t Value, const char *Desc) const {
47 if (isVerbose() && Desc)
48 OutStreamer->AddComment(Desc);
49
50 OutStreamer->EmitULEB128IntValue(Value);
51 }
52
53 /// Emit something like ".uleb128 Hi-Lo".
EmitLabelDifferenceAsULEB128(const MCSymbol * Hi,const MCSymbol * Lo) const54 void AsmPrinter::EmitLabelDifferenceAsULEB128(const MCSymbol *Hi,
55 const MCSymbol *Lo) const {
56 OutStreamer->emitAbsoluteSymbolDiffAsULEB128(Hi, Lo);
57 }
58
DecodeDWARFEncoding(unsigned Encoding)59 static 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_uleb128:
68 return "uleb128";
69 case dwarf::DW_EH_PE_sleb128:
70 return "sleb128";
71 case dwarf::DW_EH_PE_udata4:
72 return "udata4";
73 case dwarf::DW_EH_PE_udata8:
74 return "udata8";
75 case dwarf::DW_EH_PE_sdata4:
76 return "sdata4";
77 case dwarf::DW_EH_PE_sdata8:
78 return "sdata8";
79 case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata4:
80 return "pcrel udata4";
81 case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4:
82 return "pcrel sdata4";
83 case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata8:
84 return "pcrel udata8";
85 case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata8:
86 return "pcrel sdata8";
87 case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata4
88 :
89 return "indirect pcrel udata4";
90 case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4
91 :
92 return "indirect pcrel sdata4";
93 case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata8
94 :
95 return "indirect pcrel udata8";
96 case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata8
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").
EmitEncodingByte(unsigned Val,const char * Desc) const108 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.
GetSizeOfEncodedValue(unsigned Encoding) const121 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.");
128 case dwarf::DW_EH_PE_absptr:
129 return MF->getDataLayout().getPointerSize();
130 case dwarf::DW_EH_PE_udata2:
131 return 2;
132 case dwarf::DW_EH_PE_udata4:
133 return 4;
134 case dwarf::DW_EH_PE_udata8:
135 return 8;
136 }
137 }
138
EmitTTypeReference(const GlobalValue * GV,unsigned Encoding) const139 void AsmPrinter::EmitTTypeReference(const GlobalValue *GV,
140 unsigned Encoding) const {
141 if (GV) {
142 const TargetLoweringObjectFile &TLOF = getObjFileLowering();
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
emitDwarfSymbolReference(const MCSymbol * Label,bool ForceOffset) const151 void AsmPrinter::emitDwarfSymbolReference(const MCSymbol *Label,
152 bool ForceOffset) const {
153 if (!ForceOffset) {
154 // On COFF targets, we have to emit the special .secrel32 directive.
155 if (MAI->needsDwarfSectionOffsetDirective()) {
156 OutStreamer->EmitCOFFSecRel32(Label, /*Offset=*/0);
157 return;
158 }
159
160 // If the format uses relocations with dwarf, refer to the symbol directly.
161 if (MAI->doesDwarfUseRelocationsAcrossSections()) {
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
emitDwarfStringOffset(DwarfStringPoolEntry S) const171 void AsmPrinter::emitDwarfStringOffset(DwarfStringPoolEntry S) const {
172 if (MAI->doesDwarfUseRelocationsAcrossSections()) {
173 assert(S.Symbol && "No symbol available");
174 emitDwarfSymbolReference(S.Symbol);
175 return;
176 }
177
178 // Just emit the offset directly; no need for symbol math.
179 emitInt32(S.Offset);
180 }
181
EmitDwarfOffset(const MCSymbol * Label,uint64_t Offset) const182 void AsmPrinter::EmitDwarfOffset(const MCSymbol *Label, uint64_t Offset) const {
183 EmitLabelPlusOffset(Label, Offset, MAI->getCodePointerSize());
184 }
185
186 //===----------------------------------------------------------------------===//
187 // Dwarf Lowering Routines
188 //===----------------------------------------------------------------------===//
189
emitCFIInstruction(const MCCFIInstruction & Inst) const190 void AsmPrinter::emitCFIInstruction(const MCCFIInstruction &Inst) const {
191 switch (Inst.getOperation()) {
192 default:
193 llvm_unreachable("Unexpected instruction");
194 case MCCFIInstruction::OpDefCfaOffset:
195 OutStreamer->EmitCFIDefCfaOffset(Inst.getOffset());
196 break;
197 case MCCFIInstruction::OpAdjustCfaOffset:
198 OutStreamer->EmitCFIAdjustCfaOffset(Inst.getOffset());
199 break;
200 case MCCFIInstruction::OpDefCfa:
201 OutStreamer->EmitCFIDefCfa(Inst.getRegister(), Inst.getOffset());
202 break;
203 case MCCFIInstruction::OpDefCfaRegister:
204 OutStreamer->EmitCFIDefCfaRegister(Inst.getRegister());
205 break;
206 case MCCFIInstruction::OpOffset:
207 OutStreamer->EmitCFIOffset(Inst.getRegister(), Inst.getOffset());
208 break;
209 case MCCFIInstruction::OpRegister:
210 OutStreamer->EmitCFIRegister(Inst.getRegister(), Inst.getRegister2());
211 break;
212 case MCCFIInstruction::OpWindowSave:
213 OutStreamer->EmitCFIWindowSave();
214 break;
215 case MCCFIInstruction::OpSameValue:
216 OutStreamer->EmitCFISameValue(Inst.getRegister());
217 break;
218 case MCCFIInstruction::OpGnuArgsSize:
219 OutStreamer->EmitCFIGnuArgsSize(Inst.getOffset());
220 break;
221 case MCCFIInstruction::OpEscape:
222 OutStreamer->EmitCFIEscape(Inst.getValues());
223 break;
224 case MCCFIInstruction::OpRestore:
225 OutStreamer->EmitCFIRestore(Inst.getRegister());
226 break;
227 }
228 }
229
emitDwarfDIE(const DIE & Die) const230 void AsmPrinter::emitDwarfDIE(const DIE &Die) const {
231 // Emit the code (index) for the abbreviation.
232 if (isVerbose())
233 OutStreamer->AddComment("Abbrev [" + Twine(Die.getAbbrevNumber()) + "] 0x" +
234 Twine::utohexstr(Die.getOffset()) + ":0x" +
235 Twine::utohexstr(Die.getSize()) + " " +
236 dwarf::TagString(Die.getTag()));
237 EmitULEB128(Die.getAbbrevNumber());
238
239 // Emit the DIE attribute values.
240 for (const auto &V : Die.values()) {
241 dwarf::Attribute Attr = V.getAttribute();
242 assert(V.getForm() && "Too many attributes for DIE (check abbreviation)");
243
244 if (isVerbose()) {
245 OutStreamer->AddComment(dwarf::AttributeString(Attr));
246 if (Attr == dwarf::DW_AT_accessibility)
247 OutStreamer->AddComment(
248 dwarf::AccessibilityString(V.getDIEInteger().getValue()));
249 }
250
251 // Emit an attribute using the defined form.
252 V.EmitValue(this);
253 }
254
255 // Emit the DIE children if any.
256 if (Die.hasChildren()) {
257 for (auto &Child : Die.children())
258 emitDwarfDIE(Child);
259
260 OutStreamer->AddComment("End Of Children Mark");
261 emitInt8(0);
262 }
263 }
264
emitDwarfAbbrev(const DIEAbbrev & Abbrev) const265 void AsmPrinter::emitDwarfAbbrev(const DIEAbbrev &Abbrev) const {
266 // Emit the abbreviations code (base 1 index.)
267 EmitULEB128(Abbrev.getNumber(), "Abbreviation Code");
268
269 // Emit the abbreviations data.
270 Abbrev.Emit(this);
271 }
272