1 //===- lib/MC/MCDwarf.cpp - MCDwarf implementation ------------------------===//
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 #include "llvm/ADT/FoldingSet.h"
11 #include "llvm/MC/MCAsmInfo.h"
12 #include "llvm/MC/MCDwarf.h"
13 #include "llvm/MC/MCAssembler.h"
14 #include "llvm/MC/MCStreamer.h"
15 #include "llvm/MC/MCSymbol.h"
16 #include "llvm/MC/MCExpr.h"
17 #include "llvm/MC/MCContext.h"
18 #include "llvm/MC/MCObjectWriter.h"
19 #include "llvm/ADT/SmallString.h"
20 #include "llvm/ADT/Twine.h"
21 #include "llvm/Support/Debug.h"
22 #include "llvm/Support/ErrorHandling.h"
23 #include "llvm/Support/raw_ostream.h"
24 #include "llvm/Target/TargetAsmBackend.h"
25 #include "llvm/Target/TargetAsmInfo.h"
28 // Given a special op, return the address skip amount (in units of
29 // DWARF2_LINE_MIN_INSN_LENGTH.
30 #define SPECIAL_ADDR(op) (((op) - DWARF2_LINE_OPCODE_BASE)/DWARF2_LINE_RANGE)
32 // The maximum address skip amount that can be encoded with a special op.
33 #define MAX_SPECIAL_ADDR_DELTA SPECIAL_ADDR(255)
35 // First special line opcode - leave room for the standard opcodes.
36 // Note: If you want to change this, you'll have to update the
37 // "standard_opcode_lengths" table that is emitted in DwarfFileTable::Emit().
38 #define DWARF2_LINE_OPCODE_BASE 13
40 // Minimum line offset in a special line info. opcode. This value
41 // was chosen to give a reasonable range of values.
42 #define DWARF2_LINE_BASE -5
44 // Range of line offsets in a special line info. opcode.
45 # define DWARF2_LINE_RANGE 14
47 // Define the architecture-dependent minimum instruction length (in bytes).
48 // This value should be rather too small than too big.
49 # define DWARF2_LINE_MIN_INSN_LENGTH 1
51 // Note: when DWARF2_LINE_MIN_INSN_LENGTH == 1 which is the current setting,
52 // this routine is a nop and will be optimized away.
53 static inline uint64_t ScaleAddrDelta(uint64_t AddrDelta)
55 if (DWARF2_LINE_MIN_INSN_LENGTH == 1)
57 if (AddrDelta % DWARF2_LINE_MIN_INSN_LENGTH != 0) {
58 // TODO: report this error, but really only once.
61 return AddrDelta / DWARF2_LINE_MIN_INSN_LENGTH;
65 // This is called when an instruction is assembled into the specified section
66 // and if there is information from the last .loc directive that has yet to have
67 // a line entry made for it is made.
69 void MCLineEntry::Make(MCStreamer *MCOS, const MCSection *Section) {
70 if (!MCOS->getContext().getDwarfLocSeen())
73 // Create a symbol at in the current section for use in the line entry.
74 MCSymbol *LineSym = MCOS->getContext().CreateTempSymbol();
75 // Set the value of the symbol to use for the MCLineEntry.
76 MCOS->EmitLabel(LineSym);
78 // Get the current .loc info saved in the context.
79 const MCDwarfLoc &DwarfLoc = MCOS->getContext().getCurrentDwarfLoc();
81 // Create a (local) line entry with the symbol and the current .loc info.
82 MCLineEntry LineEntry(LineSym, DwarfLoc);
84 // clear DwarfLocSeen saying the current .loc info is now used.
85 MCOS->getContext().ClearDwarfLocSeen();
87 // Get the MCLineSection for this section, if one does not exist for this
89 const DenseMap<const MCSection *, MCLineSection *> &MCLineSections =
90 MCOS->getContext().getMCLineSections();
91 MCLineSection *LineSection = MCLineSections.lookup(Section);
93 // Create a new MCLineSection. This will be deleted after the dwarf line
94 // table is created using it by iterating through the MCLineSections
96 LineSection = new MCLineSection;
97 // Save a pointer to the new LineSection into the MCLineSections DenseMap.
98 MCOS->getContext().addMCLineSection(Section, LineSection);
101 // Add the line entry to this section's entries.
102 LineSection->addLineEntry(LineEntry);
106 // This helper routine returns an expression of End - Start + IntVal .
108 static inline const MCExpr *MakeStartMinusEndExpr(const MCStreamer &MCOS,
109 const MCSymbol &Start,
112 MCSymbolRefExpr::VariantKind Variant = MCSymbolRefExpr::VK_None;
114 MCSymbolRefExpr::Create(&End, Variant, MCOS.getContext());
116 MCSymbolRefExpr::Create(&Start, Variant, MCOS.getContext());
118 MCBinaryExpr::Create(MCBinaryExpr::Sub, Res, RHS, MCOS.getContext());
120 MCConstantExpr::Create(IntVal, MCOS.getContext());
122 MCBinaryExpr::Create(MCBinaryExpr::Sub, Res1, Res2, MCOS.getContext());
127 // This emits the Dwarf line table for the specified section from the entries
128 // in the LineSection.
130 static inline void EmitDwarfLineTable(MCStreamer *MCOS,
131 const MCSection *Section,
132 const MCLineSection *LineSection) {
133 unsigned FileNum = 1;
134 unsigned LastLine = 1;
136 unsigned Flags = DWARF2_LINE_DEFAULT_IS_STMT ? DWARF2_FLAG_IS_STMT : 0;
138 MCSymbol *LastLabel = NULL;
140 // Loop through each MCLineEntry and encode the dwarf line number table.
141 for (MCLineSection::const_iterator
142 it = LineSection->getMCLineEntries()->begin(),
143 ie = LineSection->getMCLineEntries()->end(); it != ie; ++it) {
145 if (FileNum != it->getFileNum()) {
146 FileNum = it->getFileNum();
147 MCOS->EmitIntValue(dwarf::DW_LNS_set_file, 1);
148 MCOS->EmitULEB128IntValue(FileNum);
150 if (Column != it->getColumn()) {
151 Column = it->getColumn();
152 MCOS->EmitIntValue(dwarf::DW_LNS_set_column, 1);
153 MCOS->EmitULEB128IntValue(Column);
155 if (Isa != it->getIsa()) {
157 MCOS->EmitIntValue(dwarf::DW_LNS_set_isa, 1);
158 MCOS->EmitULEB128IntValue(Isa);
160 if ((it->getFlags() ^ Flags) & DWARF2_FLAG_IS_STMT) {
161 Flags = it->getFlags();
162 MCOS->EmitIntValue(dwarf::DW_LNS_negate_stmt, 1);
164 if (it->getFlags() & DWARF2_FLAG_BASIC_BLOCK)
165 MCOS->EmitIntValue(dwarf::DW_LNS_set_basic_block, 1);
166 if (it->getFlags() & DWARF2_FLAG_PROLOGUE_END)
167 MCOS->EmitIntValue(dwarf::DW_LNS_set_prologue_end, 1);
168 if (it->getFlags() & DWARF2_FLAG_EPILOGUE_BEGIN)
169 MCOS->EmitIntValue(dwarf::DW_LNS_set_epilogue_begin, 1);
171 int64_t LineDelta = static_cast<int64_t>(it->getLine()) - LastLine;
172 MCSymbol *Label = it->getLabel();
174 // At this point we want to emit/create the sequence to encode the delta in
175 // line numbers and the increment of the address from the previous Label
176 // and the current Label.
177 MCOS->EmitDwarfAdvanceLineAddr(LineDelta, LastLabel, Label);
179 LastLine = it->getLine();
183 // Emit a DW_LNE_end_sequence for the end of the section.
184 // Using the pointer Section create a temporary label at the end of the
185 // section and use that and the LastLabel to compute the address delta
186 // and use INT64_MAX as the line delta which is the signal that this is
187 // actually a DW_LNE_end_sequence.
189 // Switch to the section to be able to create a symbol at its end.
190 MCOS->SwitchSection(Section);
192 MCContext &context = MCOS->getContext();
193 // Create a symbol at the end of the section.
194 MCSymbol *SectionEnd = context.CreateTempSymbol();
195 // Set the value of the symbol, as we are at the end of the section.
196 MCOS->EmitLabel(SectionEnd);
198 // Switch back the the dwarf line section.
199 MCOS->SwitchSection(context.getTargetAsmInfo().getDwarfLineSection());
201 MCOS->EmitDwarfAdvanceLineAddr(INT64_MAX, LastLabel, SectionEnd);
205 // This emits the Dwarf file and the line tables.
207 void MCDwarfFileTable::Emit(MCStreamer *MCOS) {
208 MCContext &context = MCOS->getContext();
209 // Switch to the section where the table will be emitted into.
210 MCOS->SwitchSection(context.getTargetAsmInfo().getDwarfLineSection());
212 // Create a symbol at the beginning of this section.
213 MCSymbol *LineStartSym = context.CreateTempSymbol();
214 // Set the value of the symbol, as we are at the start of the section.
215 MCOS->EmitLabel(LineStartSym);
217 // Create a symbol for the end of the section (to be set when we get there).
218 MCSymbol *LineEndSym = context.CreateTempSymbol();
220 // The first 4 bytes is the total length of the information for this
221 // compilation unit (not including these 4 bytes for the length).
222 MCOS->EmitAbsValue(MakeStartMinusEndExpr(*MCOS, *LineStartSym, *LineEndSym,4),
225 // Next 2 bytes is the Version, which is Dwarf 2.
226 MCOS->EmitIntValue(2, 2);
228 // Create a symbol for the end of the prologue (to be set when we get there).
229 MCSymbol *ProEndSym = context.CreateTempSymbol(); // Lprologue_end
231 // Length of the prologue, is the next 4 bytes. Which is the start of the
232 // section to the end of the prologue. Not including the 4 bytes for the
233 // total length, the 2 bytes for the version, and these 4 bytes for the
234 // length of the prologue.
235 MCOS->EmitAbsValue(MakeStartMinusEndExpr(*MCOS, *LineStartSym, *ProEndSym,
239 // Parameters of the state machine, are next.
240 MCOS->EmitIntValue(DWARF2_LINE_MIN_INSN_LENGTH, 1);
241 MCOS->EmitIntValue(DWARF2_LINE_DEFAULT_IS_STMT, 1);
242 MCOS->EmitIntValue(DWARF2_LINE_BASE, 1);
243 MCOS->EmitIntValue(DWARF2_LINE_RANGE, 1);
244 MCOS->EmitIntValue(DWARF2_LINE_OPCODE_BASE, 1);
246 // Standard opcode lengths
247 MCOS->EmitIntValue(0, 1); // length of DW_LNS_copy
248 MCOS->EmitIntValue(1, 1); // length of DW_LNS_advance_pc
249 MCOS->EmitIntValue(1, 1); // length of DW_LNS_advance_line
250 MCOS->EmitIntValue(1, 1); // length of DW_LNS_set_file
251 MCOS->EmitIntValue(1, 1); // length of DW_LNS_set_column
252 MCOS->EmitIntValue(0, 1); // length of DW_LNS_negate_stmt
253 MCOS->EmitIntValue(0, 1); // length of DW_LNS_set_basic_block
254 MCOS->EmitIntValue(0, 1); // length of DW_LNS_const_add_pc
255 MCOS->EmitIntValue(1, 1); // length of DW_LNS_fixed_advance_pc
256 MCOS->EmitIntValue(0, 1); // length of DW_LNS_set_prologue_end
257 MCOS->EmitIntValue(0, 1); // length of DW_LNS_set_epilogue_begin
258 MCOS->EmitIntValue(1, 1); // DW_LNS_set_isa
260 // Put out the directory and file tables.
262 // First the directory table.
263 const std::vector<StringRef> &MCDwarfDirs =
264 context.getMCDwarfDirs();
265 for (unsigned i = 0; i < MCDwarfDirs.size(); i++) {
266 MCOS->EmitBytes(MCDwarfDirs[i], 0); // the DirectoryName
267 MCOS->EmitBytes(StringRef("\0", 1), 0); // the null term. of the string
269 MCOS->EmitIntValue(0, 1); // Terminate the directory list
271 // Second the file table.
272 const std::vector<MCDwarfFile *> &MCDwarfFiles =
273 MCOS->getContext().getMCDwarfFiles();
274 for (unsigned i = 1; i < MCDwarfFiles.size(); i++) {
275 MCOS->EmitBytes(MCDwarfFiles[i]->getName(), 0); // FileName
276 MCOS->EmitBytes(StringRef("\0", 1), 0); // the null term. of the string
278 MCOS->EmitULEB128IntValue(MCDwarfFiles[i]->getDirIndex());
279 MCOS->EmitIntValue(0, 1); // last modification timestamp (always 0)
280 MCOS->EmitIntValue(0, 1); // filesize (always 0)
282 MCOS->EmitIntValue(0, 1); // Terminate the file list
284 // This is the end of the prologue, so set the value of the symbol at the
285 // end of the prologue (that was used in a previous expression).
286 MCOS->EmitLabel(ProEndSym);
288 // Put out the line tables.
289 const DenseMap<const MCSection *, MCLineSection *> &MCLineSections =
290 MCOS->getContext().getMCLineSections();
291 const std::vector<const MCSection *> &MCLineSectionOrder =
292 MCOS->getContext().getMCLineSectionOrder();
293 for (std::vector<const MCSection*>::const_iterator it =
294 MCLineSectionOrder.begin(), ie = MCLineSectionOrder.end(); it != ie;
296 const MCSection *Sec = *it;
297 const MCLineSection *Line = MCLineSections.lookup(Sec);
298 EmitDwarfLineTable(MCOS, Sec, Line);
300 // Now delete the MCLineSections that were created in MCLineEntry::Make()
301 // and used to emit the line table.
305 if (MCOS->getContext().getAsmInfo().getLinkerRequiresNonEmptyDwarfLines()
306 && MCLineSectionOrder.begin() == MCLineSectionOrder.end()) {
307 // The darwin9 linker has a bug (see PR8715). For for 32-bit architectures
309 // total_length >= prologue_length + 10
310 // We are 4 bytes short, since we have total_length = 51 and
311 // prologue_length = 45
313 // The regular end_sequence should be sufficient.
314 MCDwarfLineAddr::Emit(MCOS, INT64_MAX, 0);
317 // This is the end of the section, so set the value of the symbol at the end
318 // of this section (that was used in a previous expression).
319 MCOS->EmitLabel(LineEndSym);
322 /// Utility function to write the encoding to an object writer.
323 void MCDwarfLineAddr::Write(MCObjectWriter *OW, int64_t LineDelta,
324 uint64_t AddrDelta) {
325 SmallString<256> Tmp;
326 raw_svector_ostream OS(Tmp);
327 MCDwarfLineAddr::Encode(LineDelta, AddrDelta, OS);
328 OW->WriteBytes(OS.str());
331 /// Utility function to emit the encoding to a streamer.
332 void MCDwarfLineAddr::Emit(MCStreamer *MCOS, int64_t LineDelta,
333 uint64_t AddrDelta) {
334 SmallString<256> Tmp;
335 raw_svector_ostream OS(Tmp);
336 MCDwarfLineAddr::Encode(LineDelta, AddrDelta, OS);
337 MCOS->EmitBytes(OS.str(), /*AddrSpace=*/0);
340 /// Utility function to encode a Dwarf pair of LineDelta and AddrDeltas.
341 void MCDwarfLineAddr::Encode(int64_t LineDelta, uint64_t AddrDelta,
343 uint64_t Temp, Opcode;
344 bool NeedCopy = false;
346 // Scale the address delta by the minimum instruction length.
347 AddrDelta = ScaleAddrDelta(AddrDelta);
349 // A LineDelta of INT64_MAX is a signal that this is actually a
350 // DW_LNE_end_sequence. We cannot use special opcodes here, since we want the
351 // end_sequence to emit the matrix entry.
352 if (LineDelta == INT64_MAX) {
353 if (AddrDelta == MAX_SPECIAL_ADDR_DELTA)
354 OS << char(dwarf::DW_LNS_const_add_pc);
356 OS << char(dwarf::DW_LNS_advance_pc);
358 raw_svector_ostream OSE(Tmp);
359 MCObjectWriter::EncodeULEB128(AddrDelta, OSE);
362 OS << char(dwarf::DW_LNS_extended_op);
364 OS << char(dwarf::DW_LNE_end_sequence);
368 // Bias the line delta by the base.
369 Temp = LineDelta - DWARF2_LINE_BASE;
371 // If the line increment is out of range of a special opcode, we must encode
372 // it with DW_LNS_advance_line.
373 if (Temp >= DWARF2_LINE_RANGE) {
374 OS << char(dwarf::DW_LNS_advance_line);
376 raw_svector_ostream OSE(Tmp);
377 MCObjectWriter::EncodeSLEB128(LineDelta, OSE);
381 Temp = 0 - DWARF2_LINE_BASE;
385 // Use DW_LNS_copy instead of a "line +0, addr +0" special opcode.
386 if (LineDelta == 0 && AddrDelta == 0) {
387 OS << char(dwarf::DW_LNS_copy);
391 // Bias the opcode by the special opcode base.
392 Temp += DWARF2_LINE_OPCODE_BASE;
394 // Avoid overflow when addr_delta is large.
395 if (AddrDelta < 256 + MAX_SPECIAL_ADDR_DELTA) {
396 // Try using a special opcode.
397 Opcode = Temp + AddrDelta * DWARF2_LINE_RANGE;
403 // Try using DW_LNS_const_add_pc followed by special op.
404 Opcode = Temp + (AddrDelta - MAX_SPECIAL_ADDR_DELTA) * DWARF2_LINE_RANGE;
406 OS << char(dwarf::DW_LNS_const_add_pc);
412 // Otherwise use DW_LNS_advance_pc.
413 OS << char(dwarf::DW_LNS_advance_pc);
415 raw_svector_ostream OSE(Tmp);
416 MCObjectWriter::EncodeULEB128(AddrDelta, OSE);
420 OS << char(dwarf::DW_LNS_copy);
425 void MCDwarfFile::print(raw_ostream &OS) const {
426 OS << '"' << getName() << '"';
429 void MCDwarfFile::dump() const {
433 static int getDataAlignmentFactor(MCStreamer &streamer) {
434 MCContext &context = streamer.getContext();
435 const TargetAsmInfo &asmInfo = context.getTargetAsmInfo();
436 int size = asmInfo.getPointerSize();
437 if (asmInfo.getStackGrowthDirection() == TargetFrameLowering::StackGrowsUp)
443 static unsigned getSizeForEncoding(MCStreamer &streamer,
444 unsigned symbolEncoding) {
445 MCContext &context = streamer.getContext();
446 const TargetAsmInfo &asmInfo = context.getTargetAsmInfo();
447 unsigned format = symbolEncoding & 0x0f;
450 assert(0 && "Unknown Encoding");
451 case dwarf::DW_EH_PE_absptr:
452 case dwarf::DW_EH_PE_signed:
453 return asmInfo.getPointerSize();
454 case dwarf::DW_EH_PE_udata2:
455 case dwarf::DW_EH_PE_sdata2:
457 case dwarf::DW_EH_PE_udata4:
458 case dwarf::DW_EH_PE_sdata4:
460 case dwarf::DW_EH_PE_udata8:
461 case dwarf::DW_EH_PE_sdata8:
466 static void EmitSymbol(MCStreamer &streamer, const MCSymbol &symbol,
467 unsigned symbolEncoding) {
468 MCContext &context = streamer.getContext();
469 const MCAsmInfo &asmInfo = context.getAsmInfo();
470 const MCExpr *v = asmInfo.getExprForFDESymbol(&symbol,
472 unsigned size = getSizeForEncoding(streamer, symbolEncoding);
473 unsigned application = symbolEncoding & 0x70;
474 if (isa<MCSymbolRefExpr>(v) && application == dwarf::DW_EH_PE_pcrel)
475 streamer.EmitPCRelValue(v, size);
477 streamer.EmitAbsValue(v, size);
480 static void EmitPersonality(MCStreamer &streamer, const MCSymbol &symbol,
481 unsigned symbolEncoding) {
482 MCContext &context = streamer.getContext();
483 const MCAsmInfo &asmInfo = context.getAsmInfo();
484 const MCExpr *v = asmInfo.getExprForPersonalitySymbol(&symbol, streamer);
485 unsigned size = getSizeForEncoding(streamer, symbolEncoding);
486 unsigned application = symbolEncoding & 0x70;
487 if (isa<MCSymbolRefExpr>(v) && application == dwarf::DW_EH_PE_pcrel)
488 streamer.EmitPCRelValue(v, size);
490 streamer.EmitValue(v, size);
493 static const MachineLocation TranslateMachineLocation(
494 const TargetAsmInfo &AsmInfo,
495 const MachineLocation &Loc) {
496 unsigned Reg = Loc.getReg() == MachineLocation::VirtualFP ?
497 MachineLocation::VirtualFP :
498 unsigned(AsmInfo.getDwarfRegNum(Loc.getReg(), true));
499 const MachineLocation &NewLoc = Loc.isReg() ?
500 MachineLocation(Reg) : MachineLocation(Reg, Loc.getOffset());
505 class FrameEmitterImpl {
510 FrameEmitterImpl() : CFAOffset(0), CIENum(0) {
513 const MCSymbol &EmitCIE(MCStreamer &streamer,
514 const MCSymbol *personality,
515 unsigned personalityEncoding,
516 const MCSymbol *lsda,
517 unsigned lsdaEncoding);
518 MCSymbol *EmitFDE(MCStreamer &streamer,
519 const MCSymbol &cieStart,
520 const MCDwarfFrameInfo &frame);
521 void EmitCFIInstructions(MCStreamer &streamer,
522 const std::vector<MCCFIInstruction> &Instrs,
523 MCSymbol *BaseLabel);
524 void EmitCFIInstruction(MCStreamer &Streamer,
525 const MCCFIInstruction &Instr);
529 void FrameEmitterImpl::EmitCFIInstruction(MCStreamer &Streamer,
530 const MCCFIInstruction &Instr) {
531 int dataAlignmentFactor = getDataAlignmentFactor(Streamer);
533 switch (Instr.getOperation()) {
534 case MCCFIInstruction::Move:
535 case MCCFIInstruction::RelMove: {
536 const MachineLocation &Dst = Instr.getDestination();
537 const MachineLocation &Src = Instr.getSource();
538 const bool IsRelative = Instr.getOperation() == MCCFIInstruction::RelMove;
541 if (Dst.isReg() && Dst.getReg() == MachineLocation::VirtualFP) {
542 assert(!Src.isReg() && "Machine move not supported yet.");
544 if (Src.getReg() == MachineLocation::VirtualFP) {
545 Streamer.EmitIntValue(dwarf::DW_CFA_def_cfa_offset, 1);
547 Streamer.EmitIntValue(dwarf::DW_CFA_def_cfa, 1);
548 Streamer.EmitULEB128IntValue(Src.getReg());
552 CFAOffset += Src.getOffset();
554 CFAOffset = -Src.getOffset();
556 Streamer.EmitULEB128IntValue(CFAOffset);
560 if (Src.isReg() && Src.getReg() == MachineLocation::VirtualFP) {
561 assert(Dst.isReg() && "Machine move not supported yet.");
562 Streamer.EmitIntValue(dwarf::DW_CFA_def_cfa_register, 1);
563 Streamer.EmitULEB128IntValue(Dst.getReg());
567 unsigned Reg = Src.getReg();
569 int Offset = Dst.getOffset();
572 Offset = Offset / dataAlignmentFactor;
575 Streamer.EmitIntValue(dwarf::DW_CFA_offset_extended_sf, 1);
576 Streamer.EmitULEB128IntValue(Reg);
577 Streamer.EmitSLEB128IntValue(Offset);
578 } else if (Reg < 64) {
579 Streamer.EmitIntValue(dwarf::DW_CFA_offset + Reg, 1);
580 Streamer.EmitULEB128IntValue(Offset);
582 Streamer.EmitIntValue(dwarf::DW_CFA_offset_extended, 1);
583 Streamer.EmitULEB128IntValue(Reg);
584 Streamer.EmitULEB128IntValue(Offset);
588 case MCCFIInstruction::Remember:
589 Streamer.EmitIntValue(dwarf::DW_CFA_remember_state, 1);
591 case MCCFIInstruction::Restore:
592 Streamer.EmitIntValue(dwarf::DW_CFA_restore_state, 1);
594 case MCCFIInstruction::SameValue: {
595 unsigned Reg = Instr.getDestination().getReg();
596 Streamer.EmitIntValue(dwarf::DW_CFA_same_value, 1);
597 Streamer.EmitULEB128IntValue(Reg);
601 llvm_unreachable("Unhandled case in switch");
604 /// EmitFrameMoves - Emit frame instructions to describe the layout of the
606 void FrameEmitterImpl::EmitCFIInstructions(MCStreamer &streamer,
607 const std::vector<MCCFIInstruction> &Instrs,
608 MCSymbol *BaseLabel) {
609 for (unsigned i = 0, N = Instrs.size(); i < N; ++i) {
610 const MCCFIInstruction &Instr = Instrs[i];
611 MCSymbol *Label = Instr.getLabel();
612 // Throw out move if the label is invalid.
613 if (Label && !Label->isDefined()) continue; // Not emitted, in dead code.
615 // Advance row if new location.
616 if (BaseLabel && Label) {
617 MCSymbol *ThisSym = Label;
618 if (ThisSym != BaseLabel) {
619 streamer.EmitDwarfAdvanceFrameAddr(BaseLabel, ThisSym);
624 EmitCFIInstruction(streamer, Instr);
628 const MCSymbol &FrameEmitterImpl::EmitCIE(MCStreamer &streamer,
629 const MCSymbol *personality,
630 unsigned personalityEncoding,
631 const MCSymbol *lsda,
632 unsigned lsdaEncoding) {
633 MCContext &context = streamer.getContext();
634 const TargetAsmInfo &asmInfo = context.getTargetAsmInfo();
635 const MCSection §ion = *asmInfo.getEHFrameSection();
636 streamer.SwitchSection(§ion);
638 MCSymbol *sectionStart;
639 if (asmInfo.isFunctionEHFrameSymbolPrivate())
640 sectionStart = context.CreateTempSymbol();
642 sectionStart = context.GetOrCreateSymbol(Twine("EH_frame") + Twine(CIENum));
646 MCSymbol *sectionEnd = streamer.getContext().CreateTempSymbol();
649 const MCExpr *Length = MakeStartMinusEndExpr(streamer, *sectionStart,
651 streamer.EmitLabel(sectionStart);
652 streamer.EmitAbsValue(Length, 4);
655 streamer.EmitIntValue(0, 4);
658 streamer.EmitIntValue(dwarf::DW_CIE_VERSION, 1);
660 // Augmentation String
661 SmallString<8> Augmentation;
668 streamer.EmitBytes(Augmentation.str(), 0);
669 streamer.EmitIntValue(0, 1);
671 // Code Alignment Factor
672 streamer.EmitULEB128IntValue(1);
674 // Data Alignment Factor
675 streamer.EmitSLEB128IntValue(getDataAlignmentFactor(streamer));
677 // Return Address Register
678 streamer.EmitULEB128IntValue(asmInfo.getDwarfRARegNum(true));
680 // Augmentation Data Length (optional)
681 MCSymbol *augmentationStart = streamer.getContext().CreateTempSymbol();
682 MCSymbol *augmentationEnd = streamer.getContext().CreateTempSymbol();
683 const MCExpr *augmentationLength = MakeStartMinusEndExpr(streamer,
685 *augmentationEnd, 0);
686 streamer.EmitULEB128Value(augmentationLength);
688 // Augmentation Data (optional)
689 streamer.EmitLabel(augmentationStart);
691 // Personality Encoding
692 streamer.EmitIntValue(personalityEncoding, 1);
694 EmitPersonality(streamer, *personality, personalityEncoding);
698 streamer.EmitIntValue(lsdaEncoding, 1);
700 // Encoding of the FDE pointers
701 streamer.EmitIntValue(asmInfo.getFDEEncoding(), 1);
702 streamer.EmitLabel(augmentationEnd);
704 // Initial Instructions
706 const std::vector<MachineMove> Moves = asmInfo.getInitialFrameState();
707 std::vector<MCCFIInstruction> Instructions;
709 for (int i = 0, n = Moves.size(); i != n; ++i) {
710 MCSymbol *Label = Moves[i].getLabel();
711 const MachineLocation &Dst =
712 TranslateMachineLocation(asmInfo, Moves[i].getDestination());
713 const MachineLocation &Src =
714 TranslateMachineLocation(asmInfo, Moves[i].getSource());
715 MCCFIInstruction Inst(Label, Dst, Src);
716 Instructions.push_back(Inst);
719 EmitCFIInstructions(streamer, Instructions, NULL);
722 streamer.EmitValueToAlignment(4);
724 streamer.EmitLabel(sectionEnd);
725 return *sectionStart;
728 MCSymbol *FrameEmitterImpl::EmitFDE(MCStreamer &streamer,
729 const MCSymbol &cieStart,
730 const MCDwarfFrameInfo &frame) {
731 MCContext &context = streamer.getContext();
732 MCSymbol *fdeStart = context.CreateTempSymbol();
733 MCSymbol *fdeEnd = context.CreateTempSymbol();
734 const TargetAsmInfo &asmInfo = context.getTargetAsmInfo();
736 if (!asmInfo.isFunctionEHFrameSymbolPrivate()) {
737 Twine EHName = frame.Function->getName() + Twine(".eh");
738 MCSymbol *EHSym = context.GetOrCreateSymbol(EHName);
739 streamer.EmitEHSymAttributes(frame.Function, EHSym);
740 streamer.EmitLabel(EHSym);
744 const MCExpr *Length = MakeStartMinusEndExpr(streamer, *fdeStart, *fdeEnd, 0);
745 streamer.EmitAbsValue(Length, 4);
747 streamer.EmitLabel(fdeStart);
749 const MCExpr *offset = MakeStartMinusEndExpr(streamer, cieStart, *fdeStart,
751 streamer.EmitAbsValue(offset, 4);
752 unsigned fdeEncoding = asmInfo.getFDEEncoding();
753 unsigned size = getSizeForEncoding(streamer, fdeEncoding);
756 EmitSymbol(streamer, *frame.Begin, fdeEncoding);
759 const MCExpr *Range = MakeStartMinusEndExpr(streamer, *frame.Begin,
761 streamer.EmitAbsValue(Range, size);
763 // Augmentation Data Length
764 MCSymbol *augmentationStart = streamer.getContext().CreateTempSymbol();
765 MCSymbol *augmentationEnd = streamer.getContext().CreateTempSymbol();
766 const MCExpr *augmentationLength = MakeStartMinusEndExpr(streamer,
768 *augmentationEnd, 0);
769 streamer.EmitULEB128Value(augmentationLength);
772 streamer.EmitLabel(augmentationStart);
774 EmitSymbol(streamer, *frame.Lsda, frame.LsdaEncoding);
775 streamer.EmitLabel(augmentationEnd);
776 // Call Frame Instructions
778 EmitCFIInstructions(streamer, frame.Instructions, frame.Begin);
781 streamer.EmitValueToAlignment(size);
788 static const CIEKey getEmptyKey() { return CIEKey(0, 0, -1); }
789 static const CIEKey getTombstoneKey() { return CIEKey(0, -1, 0); }
791 CIEKey(const MCSymbol* Personality_, unsigned PersonalityEncoding_,
792 unsigned LsdaEncoding_) : Personality(Personality_),
793 PersonalityEncoding(PersonalityEncoding_),
794 LsdaEncoding(LsdaEncoding_) {
796 const MCSymbol* Personality;
797 unsigned PersonalityEncoding;
798 unsigned LsdaEncoding;
804 struct DenseMapInfo<CIEKey> {
805 static CIEKey getEmptyKey() {
806 return CIEKey::getEmptyKey();
808 static CIEKey getTombstoneKey() {
809 return CIEKey::getTombstoneKey();
811 static unsigned getHashValue(const CIEKey &Key) {
813 ID.AddPointer(Key.Personality);
814 ID.AddInteger(Key.PersonalityEncoding);
815 ID.AddInteger(Key.LsdaEncoding);
816 return ID.ComputeHash();
818 static bool isEqual(const CIEKey &LHS,
820 return LHS.Personality == RHS.Personality &&
821 LHS.PersonalityEncoding == RHS.PersonalityEncoding &&
822 LHS.LsdaEncoding == RHS.LsdaEncoding;
827 // This is an implementation of CIE and FDE emission that is bug by bug
828 // compatible with the one in CodeGen. It is useful during the transition
829 // to make it easy to compare the outputs, but should probably be removed
831 void MCDwarfFrameEmitter::EmitDarwin(MCStreamer &streamer) {
832 FrameEmitterImpl Emitter;
833 DenseMap<const MCSymbol*, const MCSymbol*> Personalities;
834 const MCSymbol *aCIE = NULL;
835 const MCDwarfFrameInfo *aFrame = NULL;
837 for (unsigned i = 0, n = streamer.getNumFrameInfos(); i < n; ++i) {
838 const MCDwarfFrameInfo &frame = streamer.getFrameInfo(i);
839 if (!frame.Personality)
841 if (Personalities.count(frame.Personality))
844 const MCSymbol *cieStart = &Emitter.EmitCIE(streamer, frame.Personality,
845 frame.PersonalityEncoding,
850 Personalities[frame.Personality] = cieStart;
853 if (Personalities.empty()) {
854 const MCDwarfFrameInfo &frame = streamer.getFrameInfo(0);
855 aCIE = &Emitter.EmitCIE(streamer, frame.Personality,
856 frame.PersonalityEncoding, frame.Lsda,
861 MCSymbol *fdeEnd = NULL;
862 for (unsigned i = 0, n = streamer.getNumFrameInfos(); i < n; ++i) {
863 const MCDwarfFrameInfo &frame = streamer.getFrameInfo(i);
864 const MCSymbol *cieStart = Personalities[frame.Personality];
868 fdeEnd = Emitter.EmitFDE(streamer, *cieStart, frame);
870 streamer.EmitLabel(fdeEnd);
873 const MCContext &context = streamer.getContext();
874 const TargetAsmInfo &asmInfo = context.getTargetAsmInfo();
875 streamer.EmitValueToAlignment(asmInfo.getPointerSize());
877 streamer.EmitLabel(fdeEnd);
880 void MCDwarfFrameEmitter::Emit(MCStreamer &streamer) {
881 const MCContext &context = streamer.getContext();
882 const TargetAsmInfo &asmInfo = context.getTargetAsmInfo();
883 if (!asmInfo.isFunctionEHFrameSymbolPrivate()) {
884 EmitDarwin(streamer);
888 MCSymbol *fdeEnd = NULL;
889 DenseMap<CIEKey, const MCSymbol*> CIEStarts;
890 FrameEmitterImpl Emitter;
892 for (unsigned i = 0, n = streamer.getNumFrameInfos(); i < n; ++i) {
893 const MCDwarfFrameInfo &frame = streamer.getFrameInfo(i);
894 CIEKey key(frame.Personality, frame.PersonalityEncoding,
896 const MCSymbol *&cieStart = CIEStarts[key];
898 cieStart = &Emitter.EmitCIE(streamer, frame.Personality,
899 frame.PersonalityEncoding, frame.Lsda,
901 fdeEnd = Emitter.EmitFDE(streamer, *cieStart, frame);
903 streamer.EmitLabel(fdeEnd);
906 streamer.EmitValueToAlignment(asmInfo.getPointerSize());
908 streamer.EmitLabel(fdeEnd);
911 void MCDwarfFrameEmitter::EmitAdvanceLoc(MCStreamer &Streamer,
912 uint64_t AddrDelta) {
913 SmallString<256> Tmp;
914 raw_svector_ostream OS(Tmp);
915 const TargetAsmInfo &AsmInfo = Streamer.getContext().getTargetAsmInfo();
916 MCDwarfFrameEmitter::EncodeAdvanceLoc(AddrDelta, OS, AsmInfo);
917 Streamer.EmitBytes(OS.str(), /*AddrSpace=*/0);
920 void MCDwarfFrameEmitter::EncodeAdvanceLoc(uint64_t AddrDelta,
922 const TargetAsmInfo &AsmInfo) {
923 // This is a small hack to facilitate the transition to CFI on OS X. It
924 // relaxes all address advances which lets us produces identical output
925 // to the one produce by CodeGen.
926 const bool Relax = !AsmInfo.isFunctionEHFrameSymbolPrivate();
928 // FIXME: Assumes the code alignment factor is 1.
929 if (AddrDelta == 0) {
930 } else if (isUIntN(6, AddrDelta) && !Relax) {
931 uint8_t Opcode = dwarf::DW_CFA_advance_loc | AddrDelta;
933 } else if (isUInt<8>(AddrDelta) && !Relax) {
934 OS << uint8_t(dwarf::DW_CFA_advance_loc1);
935 OS << uint8_t(AddrDelta);
936 } else if (isUInt<16>(AddrDelta) && !Relax) {
937 // FIXME: check what is the correct behavior on a big endian machine.
938 OS << uint8_t(dwarf::DW_CFA_advance_loc2);
939 OS << uint8_t( AddrDelta & 0xff);
940 OS << uint8_t((AddrDelta >> 8) & 0xff);
942 // FIXME: check what is the correct behavior on a big endian machine.
943 assert(isUInt<32>(AddrDelta));
944 OS << uint8_t(dwarf::DW_CFA_advance_loc4);
945 OS << uint8_t( AddrDelta & 0xff);
946 OS << uint8_t((AddrDelta >> 8) & 0xff);
947 OS << uint8_t((AddrDelta >> 16) & 0xff);
948 OS << uint8_t((AddrDelta >> 24) & 0xff);