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1 //===- lib/MC/MCDwarf.cpp - MCDwarf implementation ------------------------===//
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 #include "llvm/MC/MCDwarf.h"
11 #include "llvm/MC/MCAsmInfo.h"
12 #include "llvm/MC/MCContext.h"
13 #include "llvm/MC/MCObjectFileInfo.h"
14 #include "llvm/MC/MCObjectWriter.h"
15 #include "llvm/MC/MCRegisterInfo.h"
16 #include "llvm/MC/MCStreamer.h"
17 #include "llvm/MC/MCSymbol.h"
18 #include "llvm/MC/MCExpr.h"
19 #include "llvm/Support/Debug.h"
20 #include "llvm/Support/ErrorHandling.h"
21 #include "llvm/Support/raw_ostream.h"
22 #include "llvm/Target/TargetAsmInfo.h"
23 #include "llvm/ADT/FoldingSet.h"
24 #include "llvm/ADT/SmallString.h"
25 #include "llvm/ADT/StringExtras.h"
26 #include "llvm/ADT/Twine.h"
27 using namespace llvm;
28 
29 // Given a special op, return the address skip amount (in units of
30 // DWARF2_LINE_MIN_INSN_LENGTH.
31 #define SPECIAL_ADDR(op) (((op) - DWARF2_LINE_OPCODE_BASE)/DWARF2_LINE_RANGE)
32 
33 // The maximum address skip amount that can be encoded with a special op.
34 #define MAX_SPECIAL_ADDR_DELTA         SPECIAL_ADDR(255)
35 
36 // First special line opcode - leave room for the standard opcodes.
37 // Note: If you want to change this, you'll have to update the
38 // "standard_opcode_lengths" table that is emitted in DwarfFileTable::Emit().
39 #define DWARF2_LINE_OPCODE_BASE         13
40 
41 // Minimum line offset in a special line info. opcode.  This value
42 // was chosen to give a reasonable range of values.
43 #define DWARF2_LINE_BASE                -5
44 
45 // Range of line offsets in a special line info. opcode.
46 #define DWARF2_LINE_RANGE               14
47 
48 // Define the architecture-dependent minimum instruction length (in bytes).
49 // This value should be rather too small than too big.
50 #define DWARF2_LINE_MIN_INSN_LENGTH     1
51 
52 // Note: when DWARF2_LINE_MIN_INSN_LENGTH == 1 which is the current setting,
53 // this routine is a nop and will be optimized away.
ScaleAddrDelta(uint64_t AddrDelta)54 static inline uint64_t ScaleAddrDelta(uint64_t AddrDelta) {
55   if (DWARF2_LINE_MIN_INSN_LENGTH == 1)
56     return AddrDelta;
57   if (AddrDelta % DWARF2_LINE_MIN_INSN_LENGTH != 0) {
58     // TODO: report this error, but really only once.
59     ;
60   }
61   return AddrDelta / DWARF2_LINE_MIN_INSN_LENGTH;
62 }
63 
64 //
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.
68 //
Make(MCStreamer * MCOS,const MCSection * Section)69 void MCLineEntry::Make(MCStreamer *MCOS, const MCSection *Section) {
70   if (!MCOS->getContext().getDwarfLocSeen())
71     return;
72 
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);
77 
78   // Get the current .loc info saved in the context.
79   const MCDwarfLoc &DwarfLoc = MCOS->getContext().getCurrentDwarfLoc();
80 
81   // Create a (local) line entry with the symbol and the current .loc info.
82   MCLineEntry LineEntry(LineSym, DwarfLoc);
83 
84   // clear DwarfLocSeen saying the current .loc info is now used.
85   MCOS->getContext().ClearDwarfLocSeen();
86 
87   // Get the MCLineSection for this section, if one does not exist for this
88   // section create it.
89   const DenseMap<const MCSection *, MCLineSection *> &MCLineSections =
90     MCOS->getContext().getMCLineSections();
91   MCLineSection *LineSection = MCLineSections.lookup(Section);
92   if (!LineSection) {
93     // Create a new MCLineSection.  This will be deleted after the dwarf line
94     // table is created using it by iterating through the MCLineSections
95     // DenseMap.
96     LineSection = new MCLineSection;
97     // Save a pointer to the new LineSection into the MCLineSections DenseMap.
98     MCOS->getContext().addMCLineSection(Section, LineSection);
99   }
100 
101   // Add the line entry to this section's entries.
102   LineSection->addLineEntry(LineEntry);
103 }
104 
105 //
106 // This helper routine returns an expression of End - Start + IntVal .
107 //
MakeStartMinusEndExpr(const MCStreamer & MCOS,const MCSymbol & Start,const MCSymbol & End,int IntVal)108 static inline const MCExpr *MakeStartMinusEndExpr(const MCStreamer &MCOS,
109                                                   const MCSymbol &Start,
110                                                   const MCSymbol &End,
111                                                   int IntVal) {
112   MCSymbolRefExpr::VariantKind Variant = MCSymbolRefExpr::VK_None;
113   const MCExpr *Res =
114     MCSymbolRefExpr::Create(&End, Variant, MCOS.getContext());
115   const MCExpr *RHS =
116     MCSymbolRefExpr::Create(&Start, Variant, MCOS.getContext());
117   const MCExpr *Res1 =
118     MCBinaryExpr::Create(MCBinaryExpr::Sub, Res, RHS, MCOS.getContext());
119   const MCExpr *Res2 =
120     MCConstantExpr::Create(IntVal, MCOS.getContext());
121   const MCExpr *Res3 =
122     MCBinaryExpr::Create(MCBinaryExpr::Sub, Res1, Res2, MCOS.getContext());
123   return Res3;
124 }
125 
126 //
127 // This emits the Dwarf line table for the specified section from the entries
128 // in the LineSection.
129 //
EmitDwarfLineTable(MCStreamer * MCOS,const MCSection * Section,const MCLineSection * LineSection)130 static inline void EmitDwarfLineTable(MCStreamer *MCOS,
131                                       const MCSection *Section,
132                                       const MCLineSection *LineSection) {
133   unsigned FileNum = 1;
134   unsigned LastLine = 1;
135   unsigned Column = 0;
136   unsigned Flags = DWARF2_LINE_DEFAULT_IS_STMT ? DWARF2_FLAG_IS_STMT : 0;
137   unsigned Isa = 0;
138   MCSymbol *LastLabel = NULL;
139 
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) {
144 
145     if (FileNum != it->getFileNum()) {
146       FileNum = it->getFileNum();
147       MCOS->EmitIntValue(dwarf::DW_LNS_set_file, 1);
148       MCOS->EmitULEB128IntValue(FileNum);
149     }
150     if (Column != it->getColumn()) {
151       Column = it->getColumn();
152       MCOS->EmitIntValue(dwarf::DW_LNS_set_column, 1);
153       MCOS->EmitULEB128IntValue(Column);
154     }
155     if (Isa != it->getIsa()) {
156       Isa = it->getIsa();
157       MCOS->EmitIntValue(dwarf::DW_LNS_set_isa, 1);
158       MCOS->EmitULEB128IntValue(Isa);
159     }
160     if ((it->getFlags() ^ Flags) & DWARF2_FLAG_IS_STMT) {
161       Flags = it->getFlags();
162       MCOS->EmitIntValue(dwarf::DW_LNS_negate_stmt, 1);
163     }
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);
170 
171     int64_t LineDelta = static_cast<int64_t>(it->getLine()) - LastLine;
172     MCSymbol *Label = it->getLabel();
173 
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     const MCAsmInfo &asmInfo = MCOS->getContext().getAsmInfo();
178     MCOS->EmitDwarfAdvanceLineAddr(LineDelta, LastLabel, Label,
179                                    asmInfo.getPointerSize());
180 
181     LastLine = it->getLine();
182     LastLabel = Label;
183   }
184 
185   // Emit a DW_LNE_end_sequence for the end of the section.
186   // Using the pointer Section create a temporary label at the end of the
187   // section and use that and the LastLabel to compute the address delta
188   // and use INT64_MAX as the line delta which is the signal that this is
189   // actually a DW_LNE_end_sequence.
190 
191   // Switch to the section to be able to create a symbol at its end.
192   MCOS->SwitchSection(Section);
193 
194   MCContext &context = MCOS->getContext();
195   // Create a symbol at the end of the section.
196   MCSymbol *SectionEnd = context.CreateTempSymbol();
197   // Set the value of the symbol, as we are at the end of the section.
198   MCOS->EmitLabel(SectionEnd);
199 
200   // Switch back the the dwarf line section.
201   MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfLineSection());
202 
203   const MCAsmInfo &asmInfo = MCOS->getContext().getAsmInfo();
204   MCOS->EmitDwarfAdvanceLineAddr(INT64_MAX, LastLabel, SectionEnd,
205                                  asmInfo.getPointerSize());
206 }
207 
208 //
209 // This emits the Dwarf file and the line tables.
210 //
Emit(MCStreamer * MCOS)211 void MCDwarfFileTable::Emit(MCStreamer *MCOS) {
212   MCContext &context = MCOS->getContext();
213   // Switch to the section where the table will be emitted into.
214   MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfLineSection());
215 
216   // Create a symbol at the beginning of this section.
217   MCSymbol *LineStartSym = context.CreateTempSymbol();
218   // Set the value of the symbol, as we are at the start of the section.
219   MCOS->EmitLabel(LineStartSym);
220 
221   // Create a symbol for the end of the section (to be set when we get there).
222   MCSymbol *LineEndSym = context.CreateTempSymbol();
223 
224   // The first 4 bytes is the total length of the information for this
225   // compilation unit (not including these 4 bytes for the length).
226   MCOS->EmitAbsValue(MakeStartMinusEndExpr(*MCOS, *LineStartSym, *LineEndSym,4),
227                      4);
228 
229   // Next 2 bytes is the Version, which is Dwarf 2.
230   MCOS->EmitIntValue(2, 2);
231 
232   // Create a symbol for the end of the prologue (to be set when we get there).
233   MCSymbol *ProEndSym = context.CreateTempSymbol(); // Lprologue_end
234 
235   // Length of the prologue, is the next 4 bytes.  Which is the start of the
236   // section to the end of the prologue.  Not including the 4 bytes for the
237   // total length, the 2 bytes for the version, and these 4 bytes for the
238   // length of the prologue.
239   MCOS->EmitAbsValue(MakeStartMinusEndExpr(*MCOS, *LineStartSym, *ProEndSym,
240                                         (4 + 2 + 4)),
241                   4, 0);
242 
243   // Parameters of the state machine, are next.
244   MCOS->EmitIntValue(DWARF2_LINE_MIN_INSN_LENGTH, 1);
245   MCOS->EmitIntValue(DWARF2_LINE_DEFAULT_IS_STMT, 1);
246   MCOS->EmitIntValue(DWARF2_LINE_BASE, 1);
247   MCOS->EmitIntValue(DWARF2_LINE_RANGE, 1);
248   MCOS->EmitIntValue(DWARF2_LINE_OPCODE_BASE, 1);
249 
250   // Standard opcode lengths
251   MCOS->EmitIntValue(0, 1); // length of DW_LNS_copy
252   MCOS->EmitIntValue(1, 1); // length of DW_LNS_advance_pc
253   MCOS->EmitIntValue(1, 1); // length of DW_LNS_advance_line
254   MCOS->EmitIntValue(1, 1); // length of DW_LNS_set_file
255   MCOS->EmitIntValue(1, 1); // length of DW_LNS_set_column
256   MCOS->EmitIntValue(0, 1); // length of DW_LNS_negate_stmt
257   MCOS->EmitIntValue(0, 1); // length of DW_LNS_set_basic_block
258   MCOS->EmitIntValue(0, 1); // length of DW_LNS_const_add_pc
259   MCOS->EmitIntValue(1, 1); // length of DW_LNS_fixed_advance_pc
260   MCOS->EmitIntValue(0, 1); // length of DW_LNS_set_prologue_end
261   MCOS->EmitIntValue(0, 1); // length of DW_LNS_set_epilogue_begin
262   MCOS->EmitIntValue(1, 1); // DW_LNS_set_isa
263 
264   // Put out the directory and file tables.
265 
266   // First the directory table.
267   const std::vector<StringRef> &MCDwarfDirs =
268     context.getMCDwarfDirs();
269   for (unsigned i = 0; i < MCDwarfDirs.size(); i++) {
270     MCOS->EmitBytes(MCDwarfDirs[i], 0); // the DirectoryName
271     MCOS->EmitBytes(StringRef("\0", 1), 0); // the null term. of the string
272   }
273   MCOS->EmitIntValue(0, 1); // Terminate the directory list
274 
275   // Second the file table.
276   const std::vector<MCDwarfFile *> &MCDwarfFiles =
277     MCOS->getContext().getMCDwarfFiles();
278   for (unsigned i = 1; i < MCDwarfFiles.size(); i++) {
279     MCOS->EmitBytes(MCDwarfFiles[i]->getName(), 0); // FileName
280     MCOS->EmitBytes(StringRef("\0", 1), 0); // the null term. of the string
281     // the Directory num
282     MCOS->EmitULEB128IntValue(MCDwarfFiles[i]->getDirIndex());
283     MCOS->EmitIntValue(0, 1); // last modification timestamp (always 0)
284     MCOS->EmitIntValue(0, 1); // filesize (always 0)
285   }
286   MCOS->EmitIntValue(0, 1); // Terminate the file list
287 
288   // This is the end of the prologue, so set the value of the symbol at the
289   // end of the prologue (that was used in a previous expression).
290   MCOS->EmitLabel(ProEndSym);
291 
292   // Put out the line tables.
293   const DenseMap<const MCSection *, MCLineSection *> &MCLineSections =
294     MCOS->getContext().getMCLineSections();
295   const std::vector<const MCSection *> &MCLineSectionOrder =
296     MCOS->getContext().getMCLineSectionOrder();
297   for (std::vector<const MCSection*>::const_iterator it =
298          MCLineSectionOrder.begin(), ie = MCLineSectionOrder.end(); it != ie;
299        ++it) {
300     const MCSection *Sec = *it;
301     const MCLineSection *Line = MCLineSections.lookup(Sec);
302     EmitDwarfLineTable(MCOS, Sec, Line);
303 
304     // Now delete the MCLineSections that were created in MCLineEntry::Make()
305     // and used to emit the line table.
306     delete Line;
307   }
308 
309   if (MCOS->getContext().getAsmInfo().getLinkerRequiresNonEmptyDwarfLines()
310       && MCLineSectionOrder.begin() == MCLineSectionOrder.end()) {
311     // The darwin9 linker has a bug (see PR8715). For for 32-bit architectures
312     // it requires:
313     // total_length >= prologue_length + 10
314     // We are 4 bytes short, since we have total_length = 51 and
315     // prologue_length = 45
316 
317     // The regular end_sequence should be sufficient.
318     MCDwarfLineAddr::Emit(MCOS, INT64_MAX, 0);
319   }
320 
321   // This is the end of the section, so set the value of the symbol at the end
322   // of this section (that was used in a previous expression).
323   MCOS->EmitLabel(LineEndSym);
324 }
325 
326 /// Utility function to write the encoding to an object writer.
Write(MCObjectWriter * OW,int64_t LineDelta,uint64_t AddrDelta)327 void MCDwarfLineAddr::Write(MCObjectWriter *OW, int64_t LineDelta,
328                             uint64_t AddrDelta) {
329   SmallString<256> Tmp;
330   raw_svector_ostream OS(Tmp);
331   MCDwarfLineAddr::Encode(LineDelta, AddrDelta, OS);
332   OW->WriteBytes(OS.str());
333 }
334 
335 /// Utility function to emit the encoding to a streamer.
Emit(MCStreamer * MCOS,int64_t LineDelta,uint64_t AddrDelta)336 void MCDwarfLineAddr::Emit(MCStreamer *MCOS, int64_t LineDelta,
337                            uint64_t AddrDelta) {
338   SmallString<256> Tmp;
339   raw_svector_ostream OS(Tmp);
340   MCDwarfLineAddr::Encode(LineDelta, AddrDelta, OS);
341   MCOS->EmitBytes(OS.str(), /*AddrSpace=*/0);
342 }
343 
344 /// Utility function to encode a Dwarf pair of LineDelta and AddrDeltas.
Encode(int64_t LineDelta,uint64_t AddrDelta,raw_ostream & OS)345 void MCDwarfLineAddr::Encode(int64_t LineDelta, uint64_t AddrDelta,
346                              raw_ostream &OS) {
347   uint64_t Temp, Opcode;
348   bool NeedCopy = false;
349 
350   // Scale the address delta by the minimum instruction length.
351   AddrDelta = ScaleAddrDelta(AddrDelta);
352 
353   // A LineDelta of INT64_MAX is a signal that this is actually a
354   // DW_LNE_end_sequence. We cannot use special opcodes here, since we want the
355   // end_sequence to emit the matrix entry.
356   if (LineDelta == INT64_MAX) {
357     if (AddrDelta == MAX_SPECIAL_ADDR_DELTA)
358       OS << char(dwarf::DW_LNS_const_add_pc);
359     else {
360       OS << char(dwarf::DW_LNS_advance_pc);
361       MCObjectWriter::EncodeULEB128(AddrDelta, OS);
362     }
363     OS << char(dwarf::DW_LNS_extended_op);
364     OS << char(1);
365     OS << char(dwarf::DW_LNE_end_sequence);
366     return;
367   }
368 
369   // Bias the line delta by the base.
370   Temp = LineDelta - DWARF2_LINE_BASE;
371 
372   // If the line increment is out of range of a special opcode, we must encode
373   // it with DW_LNS_advance_line.
374   if (Temp >= DWARF2_LINE_RANGE) {
375     OS << char(dwarf::DW_LNS_advance_line);
376     SmallString<32> Tmp;
377     raw_svector_ostream OSE(Tmp);
378     MCObjectWriter::EncodeSLEB128(LineDelta, OSE);
379     OS << OSE.str();
380 
381     LineDelta = 0;
382     Temp = 0 - DWARF2_LINE_BASE;
383     NeedCopy = true;
384   }
385 
386   // Use DW_LNS_copy instead of a "line +0, addr +0" special opcode.
387   if (LineDelta == 0 && AddrDelta == 0) {
388     OS << char(dwarf::DW_LNS_copy);
389     return;
390   }
391 
392   // Bias the opcode by the special opcode base.
393   Temp += DWARF2_LINE_OPCODE_BASE;
394 
395   // Avoid overflow when addr_delta is large.
396   if (AddrDelta < 256 + MAX_SPECIAL_ADDR_DELTA) {
397     // Try using a special opcode.
398     Opcode = Temp + AddrDelta * DWARF2_LINE_RANGE;
399     if (Opcode <= 255) {
400       OS << char(Opcode);
401       return;
402     }
403 
404     // Try using DW_LNS_const_add_pc followed by special op.
405     Opcode = Temp + (AddrDelta - MAX_SPECIAL_ADDR_DELTA) * DWARF2_LINE_RANGE;
406     if (Opcode <= 255) {
407       OS << char(dwarf::DW_LNS_const_add_pc);
408       OS << char(Opcode);
409       return;
410     }
411   }
412 
413   // Otherwise use DW_LNS_advance_pc.
414   OS << char(dwarf::DW_LNS_advance_pc);
415   SmallString<32> Tmp;
416   raw_svector_ostream OSE(Tmp);
417   MCObjectWriter::EncodeULEB128(AddrDelta, OSE);
418   OS << OSE.str();
419 
420   if (NeedCopy)
421     OS << char(dwarf::DW_LNS_copy);
422   else
423     OS << char(Temp);
424 }
425 
print(raw_ostream & OS) const426 void MCDwarfFile::print(raw_ostream &OS) const {
427   OS << '"' << getName() << '"';
428 }
429 
dump() const430 void MCDwarfFile::dump() const {
431   print(dbgs());
432 }
433 
getDataAlignmentFactor(MCStreamer & streamer)434 static int getDataAlignmentFactor(MCStreamer &streamer) {
435   MCContext &context = streamer.getContext();
436   const MCAsmInfo &asmInfo = context.getAsmInfo();
437   int size = asmInfo.getPointerSize();
438   if (asmInfo.isStackGrowthDirectionUp())
439     return size;
440   else
441     return -size;
442 }
443 
getSizeForEncoding(MCStreamer & streamer,unsigned symbolEncoding)444 static unsigned getSizeForEncoding(MCStreamer &streamer,
445                                    unsigned symbolEncoding) {
446   MCContext &context = streamer.getContext();
447   unsigned format = symbolEncoding & 0x0f;
448   switch (format) {
449   default:
450     assert(0 && "Unknown Encoding");
451   case dwarf::DW_EH_PE_absptr:
452   case dwarf::DW_EH_PE_signed:
453     return context.getAsmInfo().getPointerSize();
454   case dwarf::DW_EH_PE_udata2:
455   case dwarf::DW_EH_PE_sdata2:
456     return 2;
457   case dwarf::DW_EH_PE_udata4:
458   case dwarf::DW_EH_PE_sdata4:
459     return 4;
460   case dwarf::DW_EH_PE_udata8:
461   case dwarf::DW_EH_PE_sdata8:
462     return 8;
463   }
464 }
465 
EmitSymbol(MCStreamer & streamer,const MCSymbol & symbol,unsigned symbolEncoding,const char * comment=0)466 static void EmitSymbol(MCStreamer &streamer, const MCSymbol &symbol,
467                        unsigned symbolEncoding, const char *comment = 0) {
468   MCContext &context = streamer.getContext();
469   const MCAsmInfo &asmInfo = context.getAsmInfo();
470   const MCExpr *v = asmInfo.getExprForFDESymbol(&symbol,
471                                                 symbolEncoding,
472                                                 streamer);
473   unsigned size = getSizeForEncoding(streamer, symbolEncoding);
474   if (streamer.isVerboseAsm() && comment) streamer.AddComment(comment);
475   streamer.EmitAbsValue(v, size);
476 }
477 
EmitPersonality(MCStreamer & streamer,const MCSymbol & symbol,unsigned symbolEncoding)478 static void EmitPersonality(MCStreamer &streamer, const MCSymbol &symbol,
479                             unsigned symbolEncoding) {
480   MCContext &context = streamer.getContext();
481   const MCAsmInfo &asmInfo = context.getAsmInfo();
482   const MCExpr *v = asmInfo.getExprForPersonalitySymbol(&symbol,
483                                                         symbolEncoding,
484                                                         streamer);
485   unsigned size = getSizeForEncoding(streamer, symbolEncoding);
486   streamer.EmitValue(v, size);
487 }
488 
TranslateMachineLocation(const MCRegisterInfo & MRI,const MachineLocation & Loc)489 static const MachineLocation TranslateMachineLocation(
490                                                   const MCRegisterInfo &MRI,
491                                                   const MachineLocation &Loc) {
492   unsigned Reg = Loc.getReg() == MachineLocation::VirtualFP ?
493     MachineLocation::VirtualFP :
494     unsigned(MRI.getDwarfRegNum(Loc.getReg(), true));
495   const MachineLocation &NewLoc = Loc.isReg() ?
496     MachineLocation(Reg) : MachineLocation(Reg, Loc.getOffset());
497   return NewLoc;
498 }
499 
500 namespace {
501   class FrameEmitterImpl {
502     int CFAOffset;
503     int CIENum;
504     bool UsingCFI;
505     bool IsEH;
506     const MCSymbol *SectionStart;
507   public:
FrameEmitterImpl(bool usingCFI,bool isEH,const MCSymbol * sectionStart)508     FrameEmitterImpl(bool usingCFI, bool isEH, const MCSymbol *sectionStart) :
509       CFAOffset(0), CIENum(0), UsingCFI(usingCFI), IsEH(isEH),
510       SectionStart(sectionStart) {
511     }
512 
513     /// EmitCompactUnwind - Emit the unwind information in a compact way. If
514     /// we're successful, return 'true'. Otherwise, return 'false' and it will
515     /// emit the normal CIE and FDE.
516     bool EmitCompactUnwind(MCStreamer &streamer,
517                            const MCDwarfFrameInfo &frame);
518 
519     const MCSymbol &EmitCIE(MCStreamer &streamer,
520                             const MCSymbol *personality,
521                             unsigned personalityEncoding,
522                             const MCSymbol *lsda,
523                             unsigned lsdaEncoding);
524     MCSymbol *EmitFDE(MCStreamer &streamer,
525                       const MCSymbol &cieStart,
526                       const MCDwarfFrameInfo &frame);
527     void EmitCFIInstructions(MCStreamer &streamer,
528                              const std::vector<MCCFIInstruction> &Instrs,
529                              MCSymbol *BaseLabel);
530     void EmitCFIInstruction(MCStreamer &Streamer,
531                             const MCCFIInstruction &Instr);
532   };
533 
534 } // end anonymous namespace
535 
EmitEncodingByte(MCStreamer & Streamer,unsigned Encoding,StringRef Prefix)536 static void EmitEncodingByte(MCStreamer &Streamer, unsigned Encoding,
537                              StringRef Prefix) {
538   if (Streamer.isVerboseAsm()) {
539     const char *EncStr = 0;
540     switch (Encoding) {
541     default: EncStr = "<unknown encoding>";
542     case dwarf::DW_EH_PE_absptr: EncStr = "absptr";
543     case dwarf::DW_EH_PE_omit:   EncStr = "omit";
544     case dwarf::DW_EH_PE_pcrel:  EncStr = "pcrel";
545     case dwarf::DW_EH_PE_udata4: EncStr = "udata4";
546     case dwarf::DW_EH_PE_udata8: EncStr = "udata8";
547     case dwarf::DW_EH_PE_sdata4: EncStr = "sdata4";
548     case dwarf::DW_EH_PE_sdata8: EncStr = "sdata8";
549     case dwarf::DW_EH_PE_pcrel |dwarf::DW_EH_PE_udata4: EncStr = "pcrel udata4";
550     case dwarf::DW_EH_PE_pcrel |dwarf::DW_EH_PE_sdata4: EncStr = "pcrel sdata4";
551     case dwarf::DW_EH_PE_pcrel |dwarf::DW_EH_PE_udata8: EncStr = "pcrel udata8";
552     case dwarf::DW_EH_PE_pcrel |dwarf::DW_EH_PE_sdata8: EncStr = "pcrel sdata8";
553     case dwarf::DW_EH_PE_indirect |dwarf::DW_EH_PE_pcrel|dwarf::DW_EH_PE_udata4:
554       EncStr = "indirect pcrel udata4";
555     case dwarf::DW_EH_PE_indirect |dwarf::DW_EH_PE_pcrel|dwarf::DW_EH_PE_sdata4:
556       EncStr = "indirect pcrel sdata4";
557     case dwarf::DW_EH_PE_indirect |dwarf::DW_EH_PE_pcrel|dwarf::DW_EH_PE_udata8:
558       EncStr = "indirect pcrel udata8";
559     case dwarf::DW_EH_PE_indirect |dwarf::DW_EH_PE_pcrel|dwarf::DW_EH_PE_sdata8:
560       EncStr = "indirect pcrel sdata8";
561     }
562 
563     Streamer.AddComment(Twine(Prefix) + " = " + EncStr);
564   }
565 
566   Streamer.EmitIntValue(Encoding, 1);
567 }
568 
EmitCFIInstruction(MCStreamer & Streamer,const MCCFIInstruction & Instr)569 void FrameEmitterImpl::EmitCFIInstruction(MCStreamer &Streamer,
570                                           const MCCFIInstruction &Instr) {
571   int dataAlignmentFactor = getDataAlignmentFactor(Streamer);
572   bool VerboseAsm = Streamer.isVerboseAsm();
573 
574   switch (Instr.getOperation()) {
575   case MCCFIInstruction::Move:
576   case MCCFIInstruction::RelMove: {
577     const MachineLocation &Dst = Instr.getDestination();
578     const MachineLocation &Src = Instr.getSource();
579     const bool IsRelative = Instr.getOperation() == MCCFIInstruction::RelMove;
580 
581     // If advancing cfa.
582     if (Dst.isReg() && Dst.getReg() == MachineLocation::VirtualFP) {
583       if (Src.getReg() == MachineLocation::VirtualFP) {
584         if (VerboseAsm) Streamer.AddComment("DW_CFA_def_cfa_offset");
585         Streamer.EmitIntValue(dwarf::DW_CFA_def_cfa_offset, 1);
586       } else {
587         if (VerboseAsm) Streamer.AddComment("DW_CFA_def_cfa");
588         Streamer.EmitIntValue(dwarf::DW_CFA_def_cfa, 1);
589         if (VerboseAsm) Streamer.AddComment(Twine("Reg ") +
590                                             Twine(Src.getReg()));
591         Streamer.EmitULEB128IntValue(Src.getReg());
592       }
593 
594       if (IsRelative)
595         CFAOffset += Src.getOffset();
596       else
597         CFAOffset = -Src.getOffset();
598 
599       if (VerboseAsm) Streamer.AddComment(Twine("Offset " + Twine(CFAOffset)));
600       Streamer.EmitULEB128IntValue(CFAOffset);
601       return;
602     }
603 
604     if (Src.isReg() && Src.getReg() == MachineLocation::VirtualFP) {
605       assert(Dst.isReg() && "Machine move not supported yet.");
606       if (VerboseAsm) Streamer.AddComment("DW_CFA_def_cfa_register");
607       Streamer.EmitIntValue(dwarf::DW_CFA_def_cfa_register, 1);
608       if (VerboseAsm) Streamer.AddComment(Twine("Reg ") + Twine(Dst.getReg()));
609       Streamer.EmitULEB128IntValue(Dst.getReg());
610       return;
611     }
612 
613     unsigned Reg = Src.getReg();
614     int Offset = Dst.getOffset();
615     if (IsRelative)
616       Offset -= CFAOffset;
617     Offset = Offset / dataAlignmentFactor;
618 
619     if (Offset < 0) {
620       if (VerboseAsm) Streamer.AddComment("DW_CFA_offset_extended_sf");
621       Streamer.EmitIntValue(dwarf::DW_CFA_offset_extended_sf, 1);
622       if (VerboseAsm) Streamer.AddComment(Twine("Reg ") + Twine(Reg));
623       Streamer.EmitULEB128IntValue(Reg);
624       if (VerboseAsm) Streamer.AddComment(Twine("Offset ") + Twine(Offset));
625       Streamer.EmitSLEB128IntValue(Offset);
626     } else if (Reg < 64) {
627       if (VerboseAsm) Streamer.AddComment(Twine("DW_CFA_offset + Reg(") +
628                                           Twine(Reg) + ")");
629       Streamer.EmitIntValue(dwarf::DW_CFA_offset + Reg, 1);
630       if (VerboseAsm) Streamer.AddComment(Twine("Offset ") + Twine(Offset));
631       Streamer.EmitULEB128IntValue(Offset);
632     } else {
633       if (VerboseAsm) Streamer.AddComment("DW_CFA_offset_extended");
634       Streamer.EmitIntValue(dwarf::DW_CFA_offset_extended, 1);
635       if (VerboseAsm) Streamer.AddComment(Twine("Reg ") + Twine(Reg));
636       Streamer.EmitULEB128IntValue(Reg);
637       if (VerboseAsm) Streamer.AddComment(Twine("Offset ") + Twine(Offset));
638       Streamer.EmitULEB128IntValue(Offset);
639     }
640     return;
641   }
642   case MCCFIInstruction::Remember:
643     if (VerboseAsm) Streamer.AddComment("DW_CFA_remember_state");
644     Streamer.EmitIntValue(dwarf::DW_CFA_remember_state, 1);
645     return;
646   case MCCFIInstruction::Restore:
647     if (VerboseAsm) Streamer.AddComment("DW_CFA_restore_state");
648     Streamer.EmitIntValue(dwarf::DW_CFA_restore_state, 1);
649     return;
650   case MCCFIInstruction::SameValue: {
651     unsigned Reg = Instr.getDestination().getReg();
652     if (VerboseAsm) Streamer.AddComment("DW_CFA_same_value");
653     Streamer.EmitIntValue(dwarf::DW_CFA_same_value, 1);
654     if (VerboseAsm) Streamer.AddComment(Twine("Reg ") + Twine(Reg));
655     Streamer.EmitULEB128IntValue(Reg);
656     return;
657   }
658   }
659   llvm_unreachable("Unhandled case in switch");
660 }
661 
662 /// EmitFrameMoves - Emit frame instructions to describe the layout of the
663 /// frame.
EmitCFIInstructions(MCStreamer & streamer,const std::vector<MCCFIInstruction> & Instrs,MCSymbol * BaseLabel)664 void FrameEmitterImpl::EmitCFIInstructions(MCStreamer &streamer,
665                                     const std::vector<MCCFIInstruction> &Instrs,
666                                            MCSymbol *BaseLabel) {
667   for (unsigned i = 0, N = Instrs.size(); i < N; ++i) {
668     const MCCFIInstruction &Instr = Instrs[i];
669     MCSymbol *Label = Instr.getLabel();
670     // Throw out move if the label is invalid.
671     if (Label && !Label->isDefined()) continue; // Not emitted, in dead code.
672 
673     // Advance row if new location.
674     if (BaseLabel && Label) {
675       MCSymbol *ThisSym = Label;
676       if (ThisSym != BaseLabel) {
677         if (streamer.isVerboseAsm()) streamer.AddComment("DW_CFA_advance_loc4");
678         streamer.EmitDwarfAdvanceFrameAddr(BaseLabel, ThisSym);
679         BaseLabel = ThisSym;
680       }
681     }
682 
683     EmitCFIInstruction(streamer, Instr);
684   }
685 }
686 
687 /// EmitCompactUnwind - Emit the unwind information in a compact way. If we're
688 /// successful, return 'true'. Otherwise, return 'false' and it will emit the
689 /// normal CIE and FDE.
EmitCompactUnwind(MCStreamer & Streamer,const MCDwarfFrameInfo & Frame)690 bool FrameEmitterImpl::EmitCompactUnwind(MCStreamer &Streamer,
691                                          const MCDwarfFrameInfo &Frame) {
692   MCContext &Context = Streamer.getContext();
693   const MCObjectFileInfo *MOFI = Context.getObjectFileInfo();
694   const TargetAsmInfo &TAI = Context.getTargetAsmInfo();
695   bool VerboseAsm = Streamer.isVerboseAsm();
696 
697   // range-start range-length  compact-unwind-enc personality-func   lsda
698   //  _foo       LfooEnd-_foo  0x00000023          0                 0
699   //  _bar       LbarEnd-_bar  0x00000025         __gxx_personality  except_tab1
700   //
701   //   .section __LD,__compact_unwind,regular,debug
702   //
703   //   # compact unwind for _foo
704   //   .quad _foo
705   //   .set L1,LfooEnd-_foo
706   //   .long L1
707   //   .long 0x01010001
708   //   .quad 0
709   //   .quad 0
710   //
711   //   # compact unwind for _bar
712   //   .quad _bar
713   //   .set L2,LbarEnd-_bar
714   //   .long L2
715   //   .long 0x01020011
716   //   .quad __gxx_personality
717   //   .quad except_tab1
718 
719   uint32_t Encoding = Frame.CompactUnwindEncoding;
720   if (!Encoding) return false;
721 
722   // The encoding needs to know we have an LSDA.
723   if (Frame.Lsda)
724     Encoding |= 0x40000000;
725 
726   Streamer.SwitchSection(MOFI->getCompactUnwindSection());
727 
728   // Range Start
729   unsigned FDEEncoding = TAI.getFDEEncoding(UsingCFI);
730   unsigned Size = getSizeForEncoding(Streamer, FDEEncoding);
731   if (VerboseAsm) Streamer.AddComment("Range Start");
732   Streamer.EmitSymbolValue(Frame.Function, Size);
733 
734   // Range Length
735   const MCExpr *Range = MakeStartMinusEndExpr(Streamer, *Frame.Begin,
736                                               *Frame.End, 0);
737   if (VerboseAsm) Streamer.AddComment("Range Length");
738   Streamer.EmitAbsValue(Range, 4);
739 
740   // Compact Encoding
741   Size = getSizeForEncoding(Streamer, dwarf::DW_EH_PE_udata4);
742   if (VerboseAsm) Streamer.AddComment(Twine("Compact Unwind Encoding: 0x") +
743                                       Twine(llvm::utohexstr(Encoding)));
744   Streamer.EmitIntValue(Encoding, Size);
745 
746 
747   // Personality Function
748   Size = getSizeForEncoding(Streamer, dwarf::DW_EH_PE_absptr);
749   if (VerboseAsm) Streamer.AddComment("Personality Function");
750   if (Frame.Personality)
751     Streamer.EmitSymbolValue(Frame.Personality, Size);
752   else
753     Streamer.EmitIntValue(0, Size); // No personality fn
754 
755   // LSDA
756   Size = getSizeForEncoding(Streamer, Frame.LsdaEncoding);
757   if (VerboseAsm) Streamer.AddComment("LSDA");
758   if (Frame.Lsda)
759     Streamer.EmitSymbolValue(Frame.Lsda, Size);
760   else
761     Streamer.EmitIntValue(0, Size); // No LSDA
762 
763   return true;
764 }
765 
EmitCIE(MCStreamer & streamer,const MCSymbol * personality,unsigned personalityEncoding,const MCSymbol * lsda,unsigned lsdaEncoding)766 const MCSymbol &FrameEmitterImpl::EmitCIE(MCStreamer &streamer,
767                                           const MCSymbol *personality,
768                                           unsigned personalityEncoding,
769                                           const MCSymbol *lsda,
770                                           unsigned lsdaEncoding) {
771   MCContext &context = streamer.getContext();
772   const MCRegisterInfo &MRI = context.getRegisterInfo();
773   const MCObjectFileInfo *MOFI = context.getObjectFileInfo();
774   const TargetAsmInfo &TAI = context.getTargetAsmInfo();
775   bool verboseAsm = streamer.isVerboseAsm();
776 
777   MCSymbol *sectionStart;
778   if (MOFI->isFunctionEHFrameSymbolPrivate() || !IsEH)
779     sectionStart = context.CreateTempSymbol();
780   else
781     sectionStart = context.GetOrCreateSymbol(Twine("EH_frame") + Twine(CIENum));
782 
783   streamer.EmitLabel(sectionStart);
784   CIENum++;
785 
786   MCSymbol *sectionEnd = context.CreateTempSymbol();
787 
788   // Length
789   const MCExpr *Length = MakeStartMinusEndExpr(streamer, *sectionStart,
790                                                *sectionEnd, 4);
791   if (verboseAsm) streamer.AddComment("CIE Length");
792   streamer.EmitAbsValue(Length, 4);
793 
794   // CIE ID
795   unsigned CIE_ID = IsEH ? 0 : -1;
796   if (verboseAsm) streamer.AddComment("CIE ID Tag");
797   streamer.EmitIntValue(CIE_ID, 4);
798 
799   // Version
800   if (verboseAsm) streamer.AddComment("DW_CIE_VERSION");
801   streamer.EmitIntValue(dwarf::DW_CIE_VERSION, 1);
802 
803   // Augmentation String
804   SmallString<8> Augmentation;
805   if (IsEH) {
806     if (verboseAsm) streamer.AddComment("CIE Augmentation");
807     Augmentation += "z";
808     if (personality)
809       Augmentation += "P";
810     if (lsda)
811       Augmentation += "L";
812     Augmentation += "R";
813     streamer.EmitBytes(Augmentation.str(), 0);
814   }
815   streamer.EmitIntValue(0, 1);
816 
817   // Code Alignment Factor
818   if (verboseAsm) streamer.AddComment("CIE Code Alignment Factor");
819   streamer.EmitULEB128IntValue(1);
820 
821   // Data Alignment Factor
822   if (verboseAsm) streamer.AddComment("CIE Data Alignment Factor");
823   streamer.EmitSLEB128IntValue(getDataAlignmentFactor(streamer));
824 
825   // Return Address Register
826   if (verboseAsm) streamer.AddComment("CIE Return Address Column");
827   streamer.EmitULEB128IntValue(MRI.getDwarfRegNum(MRI.getRARegister(), true));
828 
829   // Augmentation Data Length (optional)
830 
831   unsigned augmentationLength = 0;
832   if (IsEH) {
833     if (personality) {
834       // Personality Encoding
835       augmentationLength += 1;
836       // Personality
837       augmentationLength += getSizeForEncoding(streamer, personalityEncoding);
838     }
839     if (lsda)
840       augmentationLength += 1;
841     // Encoding of the FDE pointers
842     augmentationLength += 1;
843 
844     if (verboseAsm) streamer.AddComment("Augmentation Size");
845     streamer.EmitULEB128IntValue(augmentationLength);
846 
847     // Augmentation Data (optional)
848     if (personality) {
849       // Personality Encoding
850       EmitEncodingByte(streamer, personalityEncoding,
851                        "Personality Encoding");
852       // Personality
853       if (verboseAsm) streamer.AddComment("Personality");
854       EmitPersonality(streamer, *personality, personalityEncoding);
855     }
856 
857     if (lsda)
858       EmitEncodingByte(streamer, lsdaEncoding, "LSDA Encoding");
859 
860     // Encoding of the FDE pointers
861     EmitEncodingByte(streamer, TAI.getFDEEncoding(UsingCFI),
862                      "FDE Encoding");
863   }
864 
865   // Initial Instructions
866 
867   const MCAsmInfo &MAI = context.getAsmInfo();
868   const std::vector<MachineMove> &Moves = MAI.getInitialFrameState();
869   std::vector<MCCFIInstruction> Instructions;
870 
871   for (int i = 0, n = Moves.size(); i != n; ++i) {
872     MCSymbol *Label = Moves[i].getLabel();
873     const MachineLocation &Dst =
874       TranslateMachineLocation(MRI, Moves[i].getDestination());
875     const MachineLocation &Src =
876       TranslateMachineLocation(MRI, Moves[i].getSource());
877     MCCFIInstruction Inst(Label, Dst, Src);
878     Instructions.push_back(Inst);
879   }
880 
881   EmitCFIInstructions(streamer, Instructions, NULL);
882 
883   // Padding
884   streamer.EmitValueToAlignment(IsEH
885                                 ? 4 : context.getAsmInfo().getPointerSize());
886 
887   streamer.EmitLabel(sectionEnd);
888   return *sectionStart;
889 }
890 
EmitFDE(MCStreamer & streamer,const MCSymbol & cieStart,const MCDwarfFrameInfo & frame)891 MCSymbol *FrameEmitterImpl::EmitFDE(MCStreamer &streamer,
892                                     const MCSymbol &cieStart,
893                                     const MCDwarfFrameInfo &frame) {
894   MCContext &context = streamer.getContext();
895   MCSymbol *fdeStart = context.CreateTempSymbol();
896   MCSymbol *fdeEnd = context.CreateTempSymbol();
897   const MCObjectFileInfo *MOFI = context.getObjectFileInfo();
898   const TargetAsmInfo &TAI = context.getTargetAsmInfo();
899   bool verboseAsm = streamer.isVerboseAsm();
900 
901   if (!MOFI->isFunctionEHFrameSymbolPrivate() && IsEH) {
902     MCSymbol *EHSym =
903       context.GetOrCreateSymbol(frame.Function->getName() + Twine(".eh"));
904     streamer.EmitEHSymAttributes(frame.Function, EHSym);
905     streamer.EmitLabel(EHSym);
906   }
907 
908   // Length
909   const MCExpr *Length = MakeStartMinusEndExpr(streamer, *fdeStart, *fdeEnd, 0);
910   if (verboseAsm) streamer.AddComment("FDE Length");
911   streamer.EmitAbsValue(Length, 4);
912 
913   streamer.EmitLabel(fdeStart);
914 
915   // CIE Pointer
916   const MCAsmInfo &asmInfo = context.getAsmInfo();
917   if (IsEH) {
918     const MCExpr *offset = MakeStartMinusEndExpr(streamer, cieStart, *fdeStart,
919                                                  0);
920     if (verboseAsm) streamer.AddComment("FDE CIE Offset");
921     streamer.EmitAbsValue(offset, 4);
922   } else if (!asmInfo.doesDwarfRequireRelocationForSectionOffset()) {
923     const MCExpr *offset = MakeStartMinusEndExpr(streamer, *SectionStart,
924                                                  cieStart, 0);
925     streamer.EmitAbsValue(offset, 4);
926   } else {
927     streamer.EmitSymbolValue(&cieStart, 4);
928   }
929 
930   unsigned fdeEncoding = TAI.getFDEEncoding(UsingCFI);
931   unsigned size = getSizeForEncoding(streamer, fdeEncoding);
932 
933   // PC Begin
934   unsigned PCBeginEncoding = IsEH ? fdeEncoding :
935     (unsigned)dwarf::DW_EH_PE_absptr;
936   unsigned PCBeginSize = getSizeForEncoding(streamer, PCBeginEncoding);
937   EmitSymbol(streamer, *frame.Begin, PCBeginEncoding, "FDE initial location");
938 
939   // PC Range
940   const MCExpr *Range = MakeStartMinusEndExpr(streamer, *frame.Begin,
941                                               *frame.End, 0);
942   if (verboseAsm) streamer.AddComment("FDE address range");
943   streamer.EmitAbsValue(Range, size);
944 
945   if (IsEH) {
946     // Augmentation Data Length
947     unsigned augmentationLength = 0;
948 
949     if (frame.Lsda)
950       augmentationLength += getSizeForEncoding(streamer, frame.LsdaEncoding);
951 
952     if (verboseAsm) streamer.AddComment("Augmentation size");
953     streamer.EmitULEB128IntValue(augmentationLength);
954 
955     // Augmentation Data
956     if (frame.Lsda)
957       EmitSymbol(streamer, *frame.Lsda, frame.LsdaEncoding,
958                  "Language Specific Data Area");
959   }
960 
961   // Call Frame Instructions
962 
963   EmitCFIInstructions(streamer, frame.Instructions, frame.Begin);
964 
965   // Padding
966   streamer.EmitValueToAlignment(PCBeginSize);
967 
968   return fdeEnd;
969 }
970 
971 namespace {
972   struct CIEKey {
getEmptyKey__anon8fb851180211::CIEKey973     static const CIEKey getEmptyKey() { return CIEKey(0, 0, -1); }
getTombstoneKey__anon8fb851180211::CIEKey974     static const CIEKey getTombstoneKey() { return CIEKey(0, -1, 0); }
975 
CIEKey__anon8fb851180211::CIEKey976     CIEKey(const MCSymbol* Personality_, unsigned PersonalityEncoding_,
977            unsigned LsdaEncoding_) : Personality(Personality_),
978                                      PersonalityEncoding(PersonalityEncoding_),
979                                      LsdaEncoding(LsdaEncoding_) {
980     }
981     const MCSymbol* Personality;
982     unsigned PersonalityEncoding;
983     unsigned LsdaEncoding;
984   };
985 }
986 
987 namespace llvm {
988   template <>
989   struct DenseMapInfo<CIEKey> {
getEmptyKeyllvm::DenseMapInfo990     static CIEKey getEmptyKey() {
991       return CIEKey::getEmptyKey();
992     }
getTombstoneKeyllvm::DenseMapInfo993     static CIEKey getTombstoneKey() {
994       return CIEKey::getTombstoneKey();
995     }
getHashValuellvm::DenseMapInfo996     static unsigned getHashValue(const CIEKey &Key) {
997       FoldingSetNodeID ID;
998       ID.AddPointer(Key.Personality);
999       ID.AddInteger(Key.PersonalityEncoding);
1000       ID.AddInteger(Key.LsdaEncoding);
1001       return ID.ComputeHash();
1002     }
isEqualllvm::DenseMapInfo1003     static bool isEqual(const CIEKey &LHS,
1004                         const CIEKey &RHS) {
1005       return LHS.Personality == RHS.Personality &&
1006         LHS.PersonalityEncoding == RHS.PersonalityEncoding &&
1007         LHS.LsdaEncoding == RHS.LsdaEncoding;
1008     }
1009   };
1010 }
1011 
Emit(MCStreamer & Streamer,bool UsingCFI,bool IsEH)1012 void MCDwarfFrameEmitter::Emit(MCStreamer &Streamer,
1013                                bool UsingCFI,
1014                                bool IsEH) {
1015   MCContext &Context = Streamer.getContext();
1016   MCObjectFileInfo *MOFI =
1017     const_cast<MCObjectFileInfo*>(Context.getObjectFileInfo());
1018   const MCSection &Section = IsEH ? *MOFI->getEHFrameSection() :
1019                                     *MOFI->getDwarfFrameSection();
1020   Streamer.SwitchSection(&Section);
1021   MCSymbol *SectionStart = Context.CreateTempSymbol();
1022   Streamer.EmitLabel(SectionStart);
1023 
1024   MCSymbol *FDEEnd = NULL;
1025   DenseMap<CIEKey, const MCSymbol*> CIEStarts;
1026   FrameEmitterImpl Emitter(UsingCFI, IsEH, SectionStart);
1027 
1028   const MCSymbol *DummyDebugKey = NULL;
1029   for (unsigned i = 0, n = Streamer.getNumFrameInfos(); i < n; ++i) {
1030     const MCDwarfFrameInfo &Frame = Streamer.getFrameInfo(i);
1031     if (IsEH && MOFI->getCompactUnwindSection() &&
1032         Frame.CompactUnwindEncoding &&
1033         Emitter.EmitCompactUnwind(Streamer, Frame)) {
1034       FDEEnd = NULL;
1035       continue;
1036     }
1037 
1038     CIEKey Key(Frame.Personality, Frame.PersonalityEncoding,
1039                Frame.LsdaEncoding);
1040     const MCSymbol *&CIEStart = IsEH ? CIEStarts[Key] : DummyDebugKey;
1041     if (!CIEStart)
1042       CIEStart = &Emitter.EmitCIE(Streamer, Frame.Personality,
1043                                   Frame.PersonalityEncoding, Frame.Lsda,
1044                                   Frame.LsdaEncoding);
1045 
1046     FDEEnd = Emitter.EmitFDE(Streamer, *CIEStart, Frame);
1047 
1048     if (i != n - 1)
1049       Streamer.EmitLabel(FDEEnd);
1050   }
1051 
1052   Streamer.EmitValueToAlignment(Context.getAsmInfo().getPointerSize());
1053   if (FDEEnd)
1054     Streamer.EmitLabel(FDEEnd);
1055 }
1056 
EmitAdvanceLoc(MCStreamer & Streamer,uint64_t AddrDelta)1057 void MCDwarfFrameEmitter::EmitAdvanceLoc(MCStreamer &Streamer,
1058                                          uint64_t AddrDelta) {
1059   SmallString<256> Tmp;
1060   raw_svector_ostream OS(Tmp);
1061   MCDwarfFrameEmitter::EncodeAdvanceLoc(AddrDelta, OS);
1062   Streamer.EmitBytes(OS.str(), /*AddrSpace=*/0);
1063 }
1064 
EncodeAdvanceLoc(uint64_t AddrDelta,raw_ostream & OS)1065 void MCDwarfFrameEmitter::EncodeAdvanceLoc(uint64_t AddrDelta,
1066                                            raw_ostream &OS) {
1067   // FIXME: Assumes the code alignment factor is 1.
1068   if (AddrDelta == 0) {
1069   } else if (isUIntN(6, AddrDelta)) {
1070     uint8_t Opcode = dwarf::DW_CFA_advance_loc | AddrDelta;
1071     OS << Opcode;
1072   } else if (isUInt<8>(AddrDelta)) {
1073     OS << uint8_t(dwarf::DW_CFA_advance_loc1);
1074     OS << uint8_t(AddrDelta);
1075   } else if (isUInt<16>(AddrDelta)) {
1076     // FIXME: check what is the correct behavior on a big endian machine.
1077     OS << uint8_t(dwarf::DW_CFA_advance_loc2);
1078     OS << uint8_t( AddrDelta       & 0xff);
1079     OS << uint8_t((AddrDelta >> 8) & 0xff);
1080   } else {
1081     // FIXME: check what is the correct behavior on a big endian machine.
1082     assert(isUInt<32>(AddrDelta));
1083     OS << uint8_t(dwarf::DW_CFA_advance_loc4);
1084     OS << uint8_t( AddrDelta        & 0xff);
1085     OS << uint8_t((AddrDelta >> 8)  & 0xff);
1086     OS << uint8_t((AddrDelta >> 16) & 0xff);
1087     OS << uint8_t((AddrDelta >> 24) & 0xff);
1088 
1089   }
1090 }
1091