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 signed 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 /// EmitCFAByte - Emit a .byte 42 directive for a DW_CFA_xxx value.
60 void AsmPrinter::EmitCFAByte(unsigned Val) const {
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) + ")");
66 OutStreamer->AddComment(dwarf::CallFrameString(Val));
68 OutStreamer->EmitIntValue(Val, 1);
71 static const char *DecodeDWARFEncoding(unsigned Encoding) {
73 case dwarf::DW_EH_PE_absptr:
75 case dwarf::DW_EH_PE_omit:
77 case dwarf::DW_EH_PE_pcrel:
79 case dwarf::DW_EH_PE_udata4:
81 case dwarf::DW_EH_PE_udata8:
83 case dwarf::DW_EH_PE_sdata4:
85 case dwarf::DW_EH_PE_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
97 return "indirect pcrel udata4";
98 case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4
100 return "indirect pcrel sdata4";
101 case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata8
103 return "indirect pcrel udata8";
104 case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata8
106 return "indirect pcrel sdata8";
109 return "<unknown encoding>";
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").
116 void AsmPrinter::EmitEncodingByte(unsigned Val, const char *Desc) const {
119 OutStreamer->AddComment(Twine(Desc) + " Encoding = " +
120 Twine(DecodeDWARFEncoding(Val)));
122 OutStreamer->AddComment(Twine("Encoding = ") + DecodeDWARFEncoding(Val));
125 OutStreamer->EmitIntValue(Val, 1);
128 /// GetSizeOfEncodedValue - Return the size of the encoding in bytes.
129 unsigned AsmPrinter::GetSizeOfEncodedValue(unsigned Encoding) const {
130 if (Encoding == dwarf::DW_EH_PE_omit)
133 switch (Encoding & 0x07) {
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:
140 case dwarf::DW_EH_PE_udata4:
142 case dwarf::DW_EH_PE_udata8:
147 void AsmPrinter::EmitTTypeReference(const GlobalValue *GV,
148 unsigned Encoding) const {
150 const TargetLoweringObjectFile &TLOF = getObjFileLowering();
153 TLOF.getTTypeGlobalReference(GV, Encoding, *Mang, TM, MMI,
155 OutStreamer->EmitValue(Exp, GetSizeOfEncodedValue(Encoding));
157 OutStreamer->EmitIntValue(0, GetSizeOfEncodedValue(Encoding));
160 /// EmitSectionOffset - Emit the 4-byte offset of Label from the start of its
161 /// section. This can be done with a special directive if the target supports
162 /// it (e.g. cygwin) or by emitting it as an offset from a label at the start
165 /// SectionLabel is a temporary label emitted at the start of the section that
167 void AsmPrinter::emitSectionOffset(const MCSymbol *Label) const {
168 // On COFF targets, we have to emit the special .secrel32 directive.
169 if (MAI->needsDwarfSectionOffsetDirective()) {
170 OutStreamer->EmitCOFFSecRel32(Label);
174 // If the format uses relocations with dwarf, refer to the symbol directly.
175 if (MAI->doesDwarfUseRelocationsAcrossSections()) {
176 OutStreamer->EmitSymbolValue(Label, 4);
180 // Otherwise, emit it as a label difference from the start of the section.
181 EmitLabelDifference(Label, Label->getSection().getBeginSymbol(), 4);
184 void AsmPrinter::emitDwarfStringOffset(DwarfStringPoolEntryRef S) const {
185 if (MAI->doesDwarfUseRelocationsAcrossSections()) {
186 emitSectionOffset(S.getSymbol());
190 // Just emit the offset directly; no need for symbol math.
191 EmitInt32(S.getOffset());
194 /// EmitDwarfRegOp - Emit dwarf register operation.
195 void AsmPrinter::EmitDwarfRegOp(ByteStreamer &Streamer,
196 const MachineLocation &MLoc) const {
197 DebugLocDwarfExpression Expr(*MF->getSubtarget().getRegisterInfo(),
198 getDwarfDebug()->getDwarfVersion(), Streamer);
199 const MCRegisterInfo *MRI = MMI->getContext().getRegisterInfo();
200 int Reg = MRI->getDwarfRegNum(MLoc.getReg(), false);
202 // We assume that pointers are always in an addressable register.
203 if (MLoc.isIndirect())
204 // FIXME: We have no reasonable way of handling errors in here. The
205 // caller might be in the middle of a dwarf expression. We should
206 // probably assert that Reg >= 0 once debug info generation is more
208 return Expr.EmitOp(dwarf::DW_OP_nop,
209 "nop (could not find a dwarf register number)");
211 // Attempt to find a valid super- or sub-register.
212 if (!Expr.AddMachineRegPiece(MLoc.getReg()))
213 Expr.EmitOp(dwarf::DW_OP_nop,
214 "nop (could not find a dwarf register number)");
218 if (MLoc.isIndirect())
219 Expr.AddRegIndirect(Reg, MLoc.getOffset());
224 //===----------------------------------------------------------------------===//
225 // Dwarf Lowering Routines
226 //===----------------------------------------------------------------------===//
228 void AsmPrinter::emitCFIInstruction(const MCCFIInstruction &Inst) const {
229 switch (Inst.getOperation()) {
231 llvm_unreachable("Unexpected instruction");
232 case MCCFIInstruction::OpDefCfaOffset:
233 OutStreamer->EmitCFIDefCfaOffset(Inst.getOffset());
235 case MCCFIInstruction::OpDefCfa:
236 OutStreamer->EmitCFIDefCfa(Inst.getRegister(), Inst.getOffset());
238 case MCCFIInstruction::OpDefCfaRegister:
239 OutStreamer->EmitCFIDefCfaRegister(Inst.getRegister());
241 case MCCFIInstruction::OpOffset:
242 OutStreamer->EmitCFIOffset(Inst.getRegister(), Inst.getOffset());
244 case MCCFIInstruction::OpRegister:
245 OutStreamer->EmitCFIRegister(Inst.getRegister(), Inst.getRegister2());
247 case MCCFIInstruction::OpWindowSave:
248 OutStreamer->EmitCFIWindowSave();
250 case MCCFIInstruction::OpSameValue:
251 OutStreamer->EmitCFISameValue(Inst.getRegister());
256 void AsmPrinter::emitDwarfDIE(const DIE &Die) const {
257 // Emit the code (index) for the abbreviation.
259 OutStreamer->AddComment("Abbrev [" + Twine(Die.getAbbrevNumber()) + "] 0x" +
260 Twine::utohexstr(Die.getOffset()) + ":0x" +
261 Twine::utohexstr(Die.getSize()) + " " +
262 dwarf::TagString(Die.getTag()));
263 EmitULEB128(Die.getAbbrevNumber());
265 // Emit the DIE attribute values.
266 for (const auto &V : Die.values()) {
267 dwarf::Attribute Attr = V.getAttribute();
268 dwarf::Form Form = V.getForm();
269 assert(Form && "Too many attributes for DIE (check abbreviation)");
272 OutStreamer->AddComment(dwarf::AttributeString(Attr));
273 if (Attr == dwarf::DW_AT_accessibility)
274 OutStreamer->AddComment(
275 dwarf::AccessibilityString(V.getDIEInteger().getValue()));
278 // Emit an attribute using the defined form.
279 V.EmitValue(this, Form);
282 // Emit the DIE children if any.
283 if (Die.hasChildren()) {
284 for (auto &Child : Die.children())
285 emitDwarfDIE(*Child);
287 OutStreamer->AddComment("End Of Children Mark");
293 AsmPrinter::emitDwarfAbbrevs(const std::vector<DIEAbbrev *>& Abbrevs) const {
294 // For each abbrevation.
295 for (const DIEAbbrev *Abbrev : Abbrevs) {
296 // Emit the abbrevations code (base 1 index.)
297 EmitULEB128(Abbrev->getNumber(), "Abbreviation Code");
299 // Emit the abbreviations data.
303 // Mark end of abbreviations.
304 EmitULEB128(0, "EOM(3)");