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 signed 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
59 /// EmitCFAByte - Emit a .byte 42 directive for a DW_CFA_xxx value.
EmitCFAByte(unsigned Val) const60 void AsmPrinter::EmitCFAByte(unsigned Val) const {
61 if (isVerbose()) {
62 if (Val >= dwarf::DW_CFA_offset && Val < dwarf::DW_CFA_offset + 64)
63 OutStreamer->AddComment("DW_CFA_offset + Reg (" +
64 Twine(Val - dwarf::DW_CFA_offset) + ")");
65 else
66 OutStreamer->AddComment(dwarf::CallFrameString(Val));
67 }
68 OutStreamer->EmitIntValue(Val, 1);
69 }
70
DecodeDWARFEncoding(unsigned Encoding)71 static const char *DecodeDWARFEncoding(unsigned Encoding) {
72 switch (Encoding) {
73 case dwarf::DW_EH_PE_absptr:
74 return "absptr";
75 case dwarf::DW_EH_PE_omit:
76 return "omit";
77 case dwarf::DW_EH_PE_pcrel:
78 return "pcrel";
79 case dwarf::DW_EH_PE_udata4:
80 return "udata4";
81 case dwarf::DW_EH_PE_udata8:
82 return "udata8";
83 case dwarf::DW_EH_PE_sdata4:
84 return "sdata4";
85 case dwarf::DW_EH_PE_sdata8:
86 return "sdata8";
87 case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata4:
88 return "pcrel udata4";
89 case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4:
90 return "pcrel sdata4";
91 case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata8:
92 return "pcrel udata8";
93 case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata8:
94 return "pcrel sdata8";
95 case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata4
96 :
97 return "indirect pcrel udata4";
98 case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4
99 :
100 return "indirect pcrel sdata4";
101 case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata8
102 :
103 return "indirect pcrel udata8";
104 case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata8
105 :
106 return "indirect pcrel sdata8";
107 }
108
109 return "<unknown encoding>";
110 }
111
112 /// EmitEncodingByte - Emit a .byte 42 directive that corresponds to an
113 /// encoding. If verbose assembly output is enabled, we output comments
114 /// describing the encoding. Desc is an optional string saying what the
115 /// encoding is specifying (e.g. "LSDA").
EmitEncodingByte(unsigned Val,const char * Desc) const116 void AsmPrinter::EmitEncodingByte(unsigned Val, const char *Desc) const {
117 if (isVerbose()) {
118 if (Desc)
119 OutStreamer->AddComment(Twine(Desc) + " Encoding = " +
120 Twine(DecodeDWARFEncoding(Val)));
121 else
122 OutStreamer->AddComment(Twine("Encoding = ") + DecodeDWARFEncoding(Val));
123 }
124
125 OutStreamer->EmitIntValue(Val, 1);
126 }
127
128 /// GetSizeOfEncodedValue - Return the size of the encoding in bytes.
GetSizeOfEncodedValue(unsigned Encoding) const129 unsigned AsmPrinter::GetSizeOfEncodedValue(unsigned Encoding) const {
130 if (Encoding == dwarf::DW_EH_PE_omit)
131 return 0;
132
133 switch (Encoding & 0x07) {
134 default:
135 llvm_unreachable("Invalid encoded value.");
136 case dwarf::DW_EH_PE_absptr:
137 return TM.getDataLayout()->getPointerSize();
138 case dwarf::DW_EH_PE_udata2:
139 return 2;
140 case dwarf::DW_EH_PE_udata4:
141 return 4;
142 case dwarf::DW_EH_PE_udata8:
143 return 8;
144 }
145 }
146
EmitTTypeReference(const GlobalValue * GV,unsigned Encoding) const147 void AsmPrinter::EmitTTypeReference(const GlobalValue *GV,
148 unsigned Encoding) const {
149 if (GV) {
150 const TargetLoweringObjectFile &TLOF = getObjFileLowering();
151
152 const MCExpr *Exp =
153 TLOF.getTTypeGlobalReference(GV, Encoding, *Mang, TM, MMI,
154 *OutStreamer);
155 OutStreamer->EmitValue(Exp, GetSizeOfEncodedValue(Encoding));
156 } else
157 OutStreamer->EmitIntValue(0, GetSizeOfEncodedValue(Encoding));
158 }
159
emitDwarfSymbolReference(const MCSymbol * Label,bool ForceOffset) const160 void AsmPrinter::emitDwarfSymbolReference(const MCSymbol *Label,
161 bool ForceOffset) const {
162 if (!ForceOffset) {
163 // On COFF targets, we have to emit the special .secrel32 directive.
164 if (MAI->needsDwarfSectionOffsetDirective()) {
165 OutStreamer->EmitCOFFSecRel32(Label);
166 return;
167 }
168
169 // If the format uses relocations with dwarf, refer to the symbol directly.
170 if (MAI->doesDwarfUseRelocationsAcrossSections()) {
171 OutStreamer->EmitSymbolValue(Label, 4);
172 return;
173 }
174 }
175
176 // Otherwise, emit it as a label difference from the start of the section.
177 EmitLabelDifference(Label, Label->getSection().getBeginSymbol(), 4);
178 }
179
emitDwarfStringOffset(DwarfStringPoolEntryRef S) const180 void AsmPrinter::emitDwarfStringOffset(DwarfStringPoolEntryRef S) const {
181 if (MAI->doesDwarfUseRelocationsAcrossSections()) {
182 emitDwarfSymbolReference(S.getSymbol());
183 return;
184 }
185
186 // Just emit the offset directly; no need for symbol math.
187 EmitInt32(S.getOffset());
188 }
189
190 /// EmitDwarfRegOp - Emit dwarf register operation.
EmitDwarfRegOp(ByteStreamer & Streamer,const MachineLocation & MLoc) const191 void AsmPrinter::EmitDwarfRegOp(ByteStreamer &Streamer,
192 const MachineLocation &MLoc) const {
193 DebugLocDwarfExpression Expr(*MF->getSubtarget().getRegisterInfo(),
194 getDwarfDebug()->getDwarfVersion(), Streamer);
195 const MCRegisterInfo *MRI = MMI->getContext().getRegisterInfo();
196 int Reg = MRI->getDwarfRegNum(MLoc.getReg(), false);
197 if (Reg < 0) {
198 // We assume that pointers are always in an addressable register.
199 if (MLoc.isIndirect())
200 // FIXME: We have no reasonable way of handling errors in here. The
201 // caller might be in the middle of a dwarf expression. We should
202 // probably assert that Reg >= 0 once debug info generation is more
203 // mature.
204 return Expr.EmitOp(dwarf::DW_OP_nop,
205 "nop (could not find a dwarf register number)");
206
207 // Attempt to find a valid super- or sub-register.
208 if (!Expr.AddMachineRegPiece(MLoc.getReg()))
209 Expr.EmitOp(dwarf::DW_OP_nop,
210 "nop (could not find a dwarf register number)");
211 return;
212 }
213
214 if (MLoc.isIndirect())
215 Expr.AddRegIndirect(Reg, MLoc.getOffset());
216 else
217 Expr.AddReg(Reg);
218 }
219
220 //===----------------------------------------------------------------------===//
221 // Dwarf Lowering Routines
222 //===----------------------------------------------------------------------===//
223
emitCFIInstruction(const MCCFIInstruction & Inst) const224 void AsmPrinter::emitCFIInstruction(const MCCFIInstruction &Inst) const {
225 switch (Inst.getOperation()) {
226 default:
227 llvm_unreachable("Unexpected instruction");
228 case MCCFIInstruction::OpDefCfaOffset:
229 OutStreamer->EmitCFIDefCfaOffset(Inst.getOffset());
230 break;
231 case MCCFIInstruction::OpDefCfa:
232 OutStreamer->EmitCFIDefCfa(Inst.getRegister(), Inst.getOffset());
233 break;
234 case MCCFIInstruction::OpDefCfaRegister:
235 OutStreamer->EmitCFIDefCfaRegister(Inst.getRegister());
236 break;
237 case MCCFIInstruction::OpOffset:
238 OutStreamer->EmitCFIOffset(Inst.getRegister(), Inst.getOffset());
239 break;
240 case MCCFIInstruction::OpRegister:
241 OutStreamer->EmitCFIRegister(Inst.getRegister(), Inst.getRegister2());
242 break;
243 case MCCFIInstruction::OpWindowSave:
244 OutStreamer->EmitCFIWindowSave();
245 break;
246 case MCCFIInstruction::OpSameValue:
247 OutStreamer->EmitCFISameValue(Inst.getRegister());
248 break;
249 }
250 }
251
emitDwarfDIE(const DIE & Die) const252 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()));
259 EmitULEB128(Die.getAbbrevNumber());
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
emitDwarfAbbrevs(const std::vector<DIEAbbrev * > & Abbrevs) const288 AsmPrinter::emitDwarfAbbrevs(const std::vector<DIEAbbrev *>& Abbrevs) const {
289 // For each abbrevation.
290 for (const DIEAbbrev *Abbrev : Abbrevs) {
291 // Emit the abbrevations code (base 1 index.)
292 EmitULEB128(Abbrev->getNumber(), "Abbreviation Code");
293
294 // Emit the abbreviations data.
295 Abbrev->Emit(this);
296 }
297
298 // Mark end of abbreviations.
299 EmitULEB128(0, "EOM(3)");
300 }
301