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"
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.
EmitSLEB128(int64_t Value,const char * Desc) const43 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.
EmitULEB128(uint64_t Value,const char * Desc,unsigned PadTo) const51 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
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_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").
EmitEncodingByte(unsigned Val,const char * Desc) const104 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.
GetSizeOfEncodedValue(unsigned Encoding) const117 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.");
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
EmitTTypeReference(const GlobalValue * GV,unsigned Encoding) const135 void 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
emitDwarfSymbolReference(const MCSymbol * Label,bool ForceOffset) const148 void 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
emitDwarfStringOffset(DwarfStringPoolEntryRef S) const168 void 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.
EmitDwarfRegOp(ByteStreamer & Streamer,const MachineLocation & MLoc) const179 void 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
emitCFIInstruction(const MCCFIInstruction & Inst) const212 void 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
emitDwarfDIE(const DIE & Die) const249 void 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
emitDwarfAbbrev(const DIEAbbrev & Abbrev) const284 void 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