1 //===-- AsmPrinterDwarf.cpp - AsmPrinter Dwarf Support --------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements the Dwarf emissions parts of AsmPrinter.
12 //===----------------------------------------------------------------------===//
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"
36 #define DEBUG_TYPE "asm-printer"
38 //===----------------------------------------------------------------------===//
39 // Dwarf Emission Helper Routines
40 //===----------------------------------------------------------------------===//
42 /// EmitSLEB128 - emit the specified signed leb128 value.
43 void AsmPrinter::EmitSLEB128(int64_t Value, const char *Desc) const {
44 if (isVerbose() && Desc)
45 OutStreamer->AddComment(Desc);
47 OutStreamer->EmitSLEB128IntValue(Value);
50 /// EmitULEB128 - emit the specified unsigned leb128 value.
51 void AsmPrinter::EmitULEB128(uint64_t Value, const char *Desc,
52 unsigned PadTo) const {
53 if (isVerbose() && Desc)
54 OutStreamer->AddComment(Desc);
56 OutStreamer->EmitULEB128IntValue(Value, PadTo);
59 static const char *DecodeDWARFEncoding(unsigned Encoding) {
61 case dwarf::DW_EH_PE_absptr:
63 case dwarf::DW_EH_PE_omit:
65 case dwarf::DW_EH_PE_pcrel:
67 case dwarf::DW_EH_PE_udata4:
69 case dwarf::DW_EH_PE_udata8:
71 case dwarf::DW_EH_PE_sdata4:
73 case dwarf::DW_EH_PE_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
85 return "indirect pcrel udata4";
86 case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4
88 return "indirect pcrel sdata4";
89 case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata8
91 return "indirect pcrel udata8";
92 case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata8
94 return "indirect pcrel sdata8";
97 return "<unknown encoding>";
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").
104 void AsmPrinter::EmitEncodingByte(unsigned Val, const char *Desc) const {
107 OutStreamer->AddComment(Twine(Desc) + " Encoding = " +
108 Twine(DecodeDWARFEncoding(Val)));
110 OutStreamer->AddComment(Twine("Encoding = ") + DecodeDWARFEncoding(Val));
113 OutStreamer->EmitIntValue(Val, 1);
116 /// GetSizeOfEncodedValue - Return the size of the encoding in bytes.
117 unsigned AsmPrinter::GetSizeOfEncodedValue(unsigned Encoding) const {
118 if (Encoding == dwarf::DW_EH_PE_omit)
121 switch (Encoding & 0x07) {
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:
128 case dwarf::DW_EH_PE_udata4:
130 case dwarf::DW_EH_PE_udata8:
135 void AsmPrinter::EmitTTypeReference(const GlobalValue *GV,
136 unsigned Encoding) const {
138 const TargetLoweringObjectFile &TLOF = getObjFileLowering();
141 TLOF.getTTypeGlobalReference(GV, Encoding, *Mang, TM, MMI,
143 OutStreamer->EmitValue(Exp, GetSizeOfEncodedValue(Encoding));
145 OutStreamer->EmitIntValue(0, GetSizeOfEncodedValue(Encoding));
148 void AsmPrinter::emitDwarfSymbolReference(const MCSymbol *Label,
149 bool ForceOffset) const {
151 // On COFF targets, we have to emit the special .secrel32 directive.
152 if (MAI->needsDwarfSectionOffsetDirective()) {
153 OutStreamer->EmitCOFFSecRel32(Label);
157 // If the format uses relocations with dwarf, refer to the symbol directly.
158 if (MAI->doesDwarfUseRelocationsAcrossSections()) {
159 OutStreamer->EmitSymbolValue(Label, 4);
164 // Otherwise, emit it as a label difference from the start of the section.
165 EmitLabelDifference(Label, Label->getSection().getBeginSymbol(), 4);
168 void AsmPrinter::emitDwarfStringOffset(DwarfStringPoolEntryRef S) const {
169 if (MAI->doesDwarfUseRelocationsAcrossSections()) {
170 emitDwarfSymbolReference(S.getSymbol());
174 // Just emit the offset directly; no need for symbol math.
175 EmitInt32(S.getOffset());
178 /// EmitDwarfRegOp - Emit dwarf register operation.
179 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);
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
192 return Expr.EmitOp(dwarf::DW_OP_nop,
193 "nop (could not find a dwarf register number)");
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)");
202 if (MLoc.isIndirect())
203 Expr.AddRegIndirect(Reg, MLoc.getOffset());
208 //===----------------------------------------------------------------------===//
209 // Dwarf Lowering Routines
210 //===----------------------------------------------------------------------===//
212 void AsmPrinter::emitCFIInstruction(const MCCFIInstruction &Inst) const {
213 switch (Inst.getOperation()) {
215 llvm_unreachable("Unexpected instruction");
216 case MCCFIInstruction::OpDefCfaOffset:
217 OutStreamer->EmitCFIDefCfaOffset(Inst.getOffset());
219 case MCCFIInstruction::OpDefCfa:
220 OutStreamer->EmitCFIDefCfa(Inst.getRegister(), Inst.getOffset());
222 case MCCFIInstruction::OpDefCfaRegister:
223 OutStreamer->EmitCFIDefCfaRegister(Inst.getRegister());
225 case MCCFIInstruction::OpOffset:
226 OutStreamer->EmitCFIOffset(Inst.getRegister(), Inst.getOffset());
228 case MCCFIInstruction::OpRegister:
229 OutStreamer->EmitCFIRegister(Inst.getRegister(), Inst.getRegister2());
231 case MCCFIInstruction::OpWindowSave:
232 OutStreamer->EmitCFIWindowSave();
234 case MCCFIInstruction::OpSameValue:
235 OutStreamer->EmitCFISameValue(Inst.getRegister());
237 case MCCFIInstruction::OpGnuArgsSize:
238 OutStreamer->EmitCFIGnuArgsSize(Inst.getOffset());
240 case MCCFIInstruction::OpEscape:
241 OutStreamer->EmitCFIEscape(Inst.getValues());
246 void AsmPrinter::emitDwarfDIE(const DIE &Die) const {
247 // Emit the code (index) for the abbreviation.
249 OutStreamer->AddComment("Abbrev [" + Twine(Die.getAbbrevNumber()) + "] 0x" +
250 Twine::utohexstr(Die.getOffset()) + ":0x" +
251 Twine::utohexstr(Die.getSize()) + " " +
252 dwarf::TagString(Die.getTag()));
253 EmitULEB128(Die.getAbbrevNumber());
255 // Emit the DIE attribute values.
256 for (const auto &V : Die.values()) {
257 dwarf::Attribute Attr = V.getAttribute();
258 assert(V.getForm() && "Too many attributes for DIE (check abbreviation)");
261 OutStreamer->AddComment(dwarf::AttributeString(Attr));
262 if (Attr == dwarf::DW_AT_accessibility)
263 OutStreamer->AddComment(
264 dwarf::AccessibilityString(V.getDIEInteger().getValue()));
267 // Emit an attribute using the defined form.
271 // Emit the DIE children if any.
272 if (Die.hasChildren()) {
273 for (auto &Child : Die.children())
276 OutStreamer->AddComment("End Of Children Mark");
282 AsmPrinter::emitDwarfAbbrevs(const std::vector<DIEAbbrev *>& Abbrevs) const {
283 // For each abbreviation.
284 for (const DIEAbbrev *Abbrev : Abbrevs) {
285 // Emit the abbreviations code (base 1 index.)
286 EmitULEB128(Abbrev->getNumber(), "Abbreviation Code");
288 // Emit the abbreviations data.
292 // Mark end of abbreviations.
293 EmitULEB128(0, "EOM(3)");