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, OutStreamer);
154 OutStreamer.EmitValue(Exp, GetSizeOfEncodedValue(Encoding));
155 } else
156 OutStreamer.EmitIntValue(0, GetSizeOfEncodedValue(Encoding));
157 }
158
159 /// EmitSectionOffset - Emit the 4-byte offset of Label from the start of its
160 /// section. This can be done with a special directive if the target supports
161 /// it (e.g. cygwin) or by emitting it as an offset from a label at the start
162 /// of the section.
163 ///
164 /// SectionLabel is a temporary label emitted at the start of the section that
165 /// Label lives in.
emitSectionOffset(const MCSymbol * Label) const166 void AsmPrinter::emitSectionOffset(const MCSymbol *Label) const {
167 // On COFF targets, we have to emit the special .secrel32 directive.
168 if (MAI->needsDwarfSectionOffsetDirective()) {
169 OutStreamer.EmitCOFFSecRel32(Label);
170 return;
171 }
172
173 // If the format uses relocations with dwarf, refer to the symbol directly.
174 if (MAI->doesDwarfUseRelocationsAcrossSections()) {
175 OutStreamer.EmitSymbolValue(Label, 4);
176 return;
177 }
178
179 // Otherwise, emit it as a label difference from the start of the section.
180 EmitLabelDifference(Label, Label->getSection().getBeginSymbol(), 4);
181 }
182
183 /// EmitDwarfRegOp - Emit dwarf register operation.
EmitDwarfRegOp(ByteStreamer & Streamer,const MachineLocation & MLoc) const184 void AsmPrinter::EmitDwarfRegOp(ByteStreamer &Streamer,
185 const MachineLocation &MLoc) const {
186 DebugLocDwarfExpression Expr(*MF->getSubtarget().getRegisterInfo(),
187 getDwarfDebug()->getDwarfVersion(), Streamer);
188 const MCRegisterInfo *MRI = MMI->getContext().getRegisterInfo();
189 int Reg = MRI->getDwarfRegNum(MLoc.getReg(), false);
190 if (Reg < 0) {
191 // We assume that pointers are always in an addressable register.
192 if (MLoc.isIndirect())
193 // FIXME: We have no reasonable way of handling errors in here. The
194 // caller might be in the middle of a dwarf expression. We should
195 // probably assert that Reg >= 0 once debug info generation is more
196 // mature.
197 return Expr.EmitOp(dwarf::DW_OP_nop,
198 "nop (could not find a dwarf register number)");
199
200 // Attempt to find a valid super- or sub-register.
201 if (!Expr.AddMachineRegPiece(MLoc.getReg()))
202 Expr.EmitOp(dwarf::DW_OP_nop,
203 "nop (could not find a dwarf register number)");
204 return;
205 }
206
207 if (MLoc.isIndirect())
208 Expr.AddRegIndirect(Reg, MLoc.getOffset());
209 else
210 Expr.AddReg(Reg);
211 }
212
213 //===----------------------------------------------------------------------===//
214 // Dwarf Lowering Routines
215 //===----------------------------------------------------------------------===//
216
emitCFIInstruction(const MCCFIInstruction & Inst) const217 void AsmPrinter::emitCFIInstruction(const MCCFIInstruction &Inst) const {
218 switch (Inst.getOperation()) {
219 default:
220 llvm_unreachable("Unexpected instruction");
221 case MCCFIInstruction::OpDefCfaOffset:
222 OutStreamer.EmitCFIDefCfaOffset(Inst.getOffset());
223 break;
224 case MCCFIInstruction::OpDefCfa:
225 OutStreamer.EmitCFIDefCfa(Inst.getRegister(), Inst.getOffset());
226 break;
227 case MCCFIInstruction::OpDefCfaRegister:
228 OutStreamer.EmitCFIDefCfaRegister(Inst.getRegister());
229 break;
230 case MCCFIInstruction::OpOffset:
231 OutStreamer.EmitCFIOffset(Inst.getRegister(), Inst.getOffset());
232 break;
233 case MCCFIInstruction::OpRegister:
234 OutStreamer.EmitCFIRegister(Inst.getRegister(), Inst.getRegister2());
235 break;
236 case MCCFIInstruction::OpWindowSave:
237 OutStreamer.EmitCFIWindowSave();
238 break;
239 case MCCFIInstruction::OpSameValue:
240 OutStreamer.EmitCFISameValue(Inst.getRegister());
241 break;
242 }
243 }
244
emitDwarfDIE(const DIE & Die) const245 void AsmPrinter::emitDwarfDIE(const DIE &Die) const {
246 // Get the abbreviation for this DIE.
247 const DIEAbbrev &Abbrev = Die.getAbbrev();
248
249 // Emit the code (index) for the abbreviation.
250 if (isVerbose())
251 OutStreamer.AddComment("Abbrev [" + Twine(Abbrev.getNumber()) +
252 "] 0x" + Twine::utohexstr(Die.getOffset()) +
253 ":0x" + Twine::utohexstr(Die.getSize()) + " " +
254 dwarf::TagString(Abbrev.getTag()));
255 EmitULEB128(Abbrev.getNumber());
256
257 const SmallVectorImpl<DIEValue *> &Values = Die.getValues();
258 const SmallVectorImpl<DIEAbbrevData> &AbbrevData = Abbrev.getData();
259
260 // Emit the DIE attribute values.
261 for (unsigned i = 0, N = Values.size(); i < N; ++i) {
262 dwarf::Attribute Attr = AbbrevData[i].getAttribute();
263 dwarf::Form Form = AbbrevData[i].getForm();
264 assert(Form && "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(dwarf::AccessibilityString(
270 cast<DIEInteger>(Values[i])->getValue()));
271 }
272
273 // Emit an attribute using the defined form.
274 Values[i]->EmitValue(this, Form);
275 }
276
277 // Emit the DIE children if any.
278 if (Abbrev.hasChildren()) {
279 for (auto &Child : Die.getChildren())
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