xref: /freebsd/contrib/llvm-project/llvm/lib/MC/MCStreamer.cpp (revision 6be3386466ab79a84b48429ae66244f21526d3df) 
1 //===- lib/MC/MCStreamer.cpp - Streaming Machine Code Output --------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 #include "llvm/MC/MCStreamer.h"
10 #include "llvm/ADT/Optional.h"
11 #include "llvm/ADT/SmallString.h"
12 #include "llvm/ADT/StringRef.h"
13 #include "llvm/ADT/Twine.h"
14 #include "llvm/BinaryFormat/COFF.h"
15 #include "llvm/DebugInfo/CodeView/SymbolRecord.h"
16 #include "llvm/MC/MCAsmBackend.h"
17 #include "llvm/MC/MCAsmInfo.h"
18 #include "llvm/MC/MCCodeView.h"
19 #include "llvm/MC/MCContext.h"
20 #include "llvm/MC/MCDwarf.h"
21 #include "llvm/MC/MCExpr.h"
22 #include "llvm/MC/MCInst.h"
23 #include "llvm/MC/MCInstPrinter.h"
24 #include "llvm/MC/MCObjectFileInfo.h"
25 #include "llvm/MC/MCRegister.h"
26 #include "llvm/MC/MCRegisterInfo.h"
27 #include "llvm/MC/MCSection.h"
28 #include "llvm/MC/MCSectionCOFF.h"
29 #include "llvm/MC/MCSymbol.h"
30 #include "llvm/MC/MCWin64EH.h"
31 #include "llvm/MC/MCWinEH.h"
32 #include "llvm/Support/Casting.h"
33 #include "llvm/Support/ErrorHandling.h"
34 #include "llvm/Support/LEB128.h"
35 #include "llvm/Support/MathExtras.h"
36 #include "llvm/Support/raw_ostream.h"
37 #include <cassert>
38 #include <cstdint>
39 #include <cstdlib>
40 #include <utility>
41 
42 using namespace llvm;
43 
44 MCTargetStreamer::MCTargetStreamer(MCStreamer &S) : Streamer(S) {
45   S.setTargetStreamer(this);
46 }
47 
48 // Pin the vtables to this file.
49 MCTargetStreamer::~MCTargetStreamer() = default;
50 
51 void MCTargetStreamer::emitLabel(MCSymbol *Symbol) {}
52 
53 void MCTargetStreamer::finish() {}
54 
55 void MCTargetStreamer::changeSection(const MCSection *CurSection,
56                                      MCSection *Section,
57                                      const MCExpr *Subsection,
58                                      raw_ostream &OS) {
59   Section->PrintSwitchToSection(
60       *Streamer.getContext().getAsmInfo(),
61       Streamer.getContext().getObjectFileInfo()->getTargetTriple(), OS,
62       Subsection);
63 }
64 
65 void MCTargetStreamer::emitDwarfFileDirective(StringRef Directive) {
66   Streamer.emitRawText(Directive);
67 }
68 
69 void MCTargetStreamer::emitValue(const MCExpr *Value) {
70   SmallString<128> Str;
71   raw_svector_ostream OS(Str);
72 
73   Value->print(OS, Streamer.getContext().getAsmInfo());
74   Streamer.emitRawText(OS.str());
75 }
76 
77 void MCTargetStreamer::emitRawBytes(StringRef Data) {
78   const MCAsmInfo *MAI = Streamer.getContext().getAsmInfo();
79   const char *Directive = MAI->getData8bitsDirective();
80   for (const unsigned char C : Data.bytes()) {
81     SmallString<128> Str;
82     raw_svector_ostream OS(Str);
83 
84     OS << Directive << (unsigned)C;
85     Streamer.emitRawText(OS.str());
86   }
87 }
88 
89 void MCTargetStreamer::emitAssignment(MCSymbol *Symbol, const MCExpr *Value) {}
90 
91 MCStreamer::MCStreamer(MCContext &Ctx)
92     : Context(Ctx), CurrentWinFrameInfo(nullptr),
93       UseAssemblerInfoForParsing(false) {
94   SectionStack.push_back(std::pair<MCSectionSubPair, MCSectionSubPair>());
95 }
96 
97 MCStreamer::~MCStreamer() {}
98 
99 void MCStreamer::reset() {
100   DwarfFrameInfos.clear();
101   CurrentWinFrameInfo = nullptr;
102   WinFrameInfos.clear();
103   SymbolOrdering.clear();
104   SectionStack.clear();
105   SectionStack.push_back(std::pair<MCSectionSubPair, MCSectionSubPair>());
106 }
107 
108 raw_ostream &MCStreamer::GetCommentOS() {
109   // By default, discard comments.
110   return nulls();
111 }
112 
113 unsigned MCStreamer::getNumFrameInfos() { return DwarfFrameInfos.size(); }
114 ArrayRef<MCDwarfFrameInfo> MCStreamer::getDwarfFrameInfos() const {
115   return DwarfFrameInfos;
116 }
117 
118 void MCStreamer::emitRawComment(const Twine &T, bool TabPrefix) {}
119 
120 void MCStreamer::addExplicitComment(const Twine &T) {}
121 void MCStreamer::emitExplicitComments() {}
122 
123 void MCStreamer::generateCompactUnwindEncodings(MCAsmBackend *MAB) {
124   for (auto &FI : DwarfFrameInfos)
125     FI.CompactUnwindEncoding =
126         (MAB ? MAB->generateCompactUnwindEncoding(FI.Instructions) : 0);
127 }
128 
129 /// EmitIntValue - Special case of EmitValue that avoids the client having to
130 /// pass in a MCExpr for constant integers.
131 void MCStreamer::emitIntValue(uint64_t Value, unsigned Size) {
132   assert(1 <= Size && Size <= 8 && "Invalid size");
133   assert((isUIntN(8 * Size, Value) || isIntN(8 * Size, Value)) &&
134          "Invalid size");
135   const bool IsLittleEndian = Context.getAsmInfo()->isLittleEndian();
136   uint64_t Swapped = support::endian::byte_swap(
137       Value, IsLittleEndian ? support::little : support::big);
138   unsigned Index = IsLittleEndian ? 0 : 8 - Size;
139   emitBytes(StringRef(reinterpret_cast<char *>(&Swapped) + Index, Size));
140 }
141 
142 /// EmitULEB128IntValue - Special case of EmitULEB128Value that avoids the
143 /// client having to pass in a MCExpr for constant integers.
144 void MCStreamer::emitULEB128IntValue(uint64_t Value, unsigned PadTo) {
145   SmallString<128> Tmp;
146   raw_svector_ostream OSE(Tmp);
147   encodeULEB128(Value, OSE, PadTo);
148   emitBytes(OSE.str());
149 }
150 
151 /// EmitSLEB128IntValue - Special case of EmitSLEB128Value that avoids the
152 /// client having to pass in a MCExpr for constant integers.
153 void MCStreamer::emitSLEB128IntValue(int64_t Value) {
154   SmallString<128> Tmp;
155   raw_svector_ostream OSE(Tmp);
156   encodeSLEB128(Value, OSE);
157   emitBytes(OSE.str());
158 }
159 
160 void MCStreamer::emitValue(const MCExpr *Value, unsigned Size, SMLoc Loc) {
161   emitValueImpl(Value, Size, Loc);
162 }
163 
164 void MCStreamer::emitSymbolValue(const MCSymbol *Sym, unsigned Size,
165                                  bool IsSectionRelative) {
166   assert((!IsSectionRelative || Size == 4) &&
167          "SectionRelative value requires 4-bytes");
168 
169   if (!IsSectionRelative)
170     emitValueImpl(MCSymbolRefExpr::create(Sym, getContext()), Size);
171   else
172     EmitCOFFSecRel32(Sym, /*Offset=*/0);
173 }
174 
175 void MCStreamer::emitDTPRel64Value(const MCExpr *Value) {
176   report_fatal_error("unsupported directive in streamer");
177 }
178 
179 void MCStreamer::emitDTPRel32Value(const MCExpr *Value) {
180   report_fatal_error("unsupported directive in streamer");
181 }
182 
183 void MCStreamer::emitTPRel64Value(const MCExpr *Value) {
184   report_fatal_error("unsupported directive in streamer");
185 }
186 
187 void MCStreamer::emitTPRel32Value(const MCExpr *Value) {
188   report_fatal_error("unsupported directive in streamer");
189 }
190 
191 void MCStreamer::emitGPRel64Value(const MCExpr *Value) {
192   report_fatal_error("unsupported directive in streamer");
193 }
194 
195 void MCStreamer::emitGPRel32Value(const MCExpr *Value) {
196   report_fatal_error("unsupported directive in streamer");
197 }
198 
199 /// Emit NumBytes bytes worth of the value specified by FillValue.
200 /// This implements directives such as '.space'.
201 void MCStreamer::emitFill(uint64_t NumBytes, uint8_t FillValue) {
202   emitFill(*MCConstantExpr::create(NumBytes, getContext()), FillValue);
203 }
204 
205 /// The implementation in this class just redirects to emitFill.
206 void MCStreamer::emitZeros(uint64_t NumBytes) { emitFill(NumBytes, 0); }
207 
208 Expected<unsigned>
209 MCStreamer::tryEmitDwarfFileDirective(unsigned FileNo, StringRef Directory,
210                                       StringRef Filename,
211                                       Optional<MD5::MD5Result> Checksum,
212                                       Optional<StringRef> Source,
213                                       unsigned CUID) {
214   return getContext().getDwarfFile(Directory, Filename, FileNo, Checksum,
215                                    Source, CUID);
216 }
217 
218 void MCStreamer::emitDwarfFile0Directive(StringRef Directory,
219                                          StringRef Filename,
220                                          Optional<MD5::MD5Result> Checksum,
221                                          Optional<StringRef> Source,
222                                          unsigned CUID) {
223   getContext().setMCLineTableRootFile(CUID, Directory, Filename, Checksum,
224                                       Source);
225 }
226 
227 void MCStreamer::emitCFIBKeyFrame() {
228   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
229   if (!CurFrame)
230     return;
231   CurFrame->IsBKeyFrame = true;
232 }
233 
234 void MCStreamer::emitDwarfLocDirective(unsigned FileNo, unsigned Line,
235                                        unsigned Column, unsigned Flags,
236                                        unsigned Isa, unsigned Discriminator,
237                                        StringRef FileName) {
238   getContext().setCurrentDwarfLoc(FileNo, Line, Column, Flags, Isa,
239                                   Discriminator);
240 }
241 
242 MCSymbol *MCStreamer::getDwarfLineTableSymbol(unsigned CUID) {
243   MCDwarfLineTable &Table = getContext().getMCDwarfLineTable(CUID);
244   if (!Table.getLabel()) {
245     StringRef Prefix = Context.getAsmInfo()->getPrivateGlobalPrefix();
246     Table.setLabel(
247         Context.getOrCreateSymbol(Prefix + "line_table_start" + Twine(CUID)));
248   }
249   return Table.getLabel();
250 }
251 
252 bool MCStreamer::hasUnfinishedDwarfFrameInfo() {
253   return !DwarfFrameInfos.empty() && !DwarfFrameInfos.back().End;
254 }
255 
256 MCDwarfFrameInfo *MCStreamer::getCurrentDwarfFrameInfo() {
257   if (!hasUnfinishedDwarfFrameInfo()) {
258     getContext().reportError(SMLoc(), "this directive must appear between "
259                                       ".cfi_startproc and .cfi_endproc "
260                                       "directives");
261     return nullptr;
262   }
263   return &DwarfFrameInfos.back();
264 }
265 
266 bool MCStreamer::EmitCVFileDirective(unsigned FileNo, StringRef Filename,
267                                      ArrayRef<uint8_t> Checksum,
268                                      unsigned ChecksumKind) {
269   return getContext().getCVContext().addFile(*this, FileNo, Filename, Checksum,
270                                              ChecksumKind);
271 }
272 
273 bool MCStreamer::EmitCVFuncIdDirective(unsigned FunctionId) {
274   return getContext().getCVContext().recordFunctionId(FunctionId);
275 }
276 
277 bool MCStreamer::EmitCVInlineSiteIdDirective(unsigned FunctionId,
278                                              unsigned IAFunc, unsigned IAFile,
279                                              unsigned IALine, unsigned IACol,
280                                              SMLoc Loc) {
281   if (getContext().getCVContext().getCVFunctionInfo(IAFunc) == nullptr) {
282     getContext().reportError(Loc, "parent function id not introduced by "
283                                   ".cv_func_id or .cv_inline_site_id");
284     return true;
285   }
286 
287   return getContext().getCVContext().recordInlinedCallSiteId(
288       FunctionId, IAFunc, IAFile, IALine, IACol);
289 }
290 
291 void MCStreamer::emitCVLocDirective(unsigned FunctionId, unsigned FileNo,
292                                     unsigned Line, unsigned Column,
293                                     bool PrologueEnd, bool IsStmt,
294                                     StringRef FileName, SMLoc Loc) {}
295 
296 bool MCStreamer::checkCVLocSection(unsigned FuncId, unsigned FileNo,
297                                    SMLoc Loc) {
298   CodeViewContext &CVC = getContext().getCVContext();
299   MCCVFunctionInfo *FI = CVC.getCVFunctionInfo(FuncId);
300   if (!FI) {
301     getContext().reportError(
302         Loc, "function id not introduced by .cv_func_id or .cv_inline_site_id");
303     return false;
304   }
305 
306   // Track the section
307   if (FI->Section == nullptr)
308     FI->Section = getCurrentSectionOnly();
309   else if (FI->Section != getCurrentSectionOnly()) {
310     getContext().reportError(
311         Loc,
312         "all .cv_loc directives for a function must be in the same section");
313     return false;
314   }
315   return true;
316 }
317 
318 void MCStreamer::emitCVLinetableDirective(unsigned FunctionId,
319                                           const MCSymbol *Begin,
320                                           const MCSymbol *End) {}
321 
322 void MCStreamer::emitCVInlineLinetableDirective(unsigned PrimaryFunctionId,
323                                                 unsigned SourceFileId,
324                                                 unsigned SourceLineNum,
325                                                 const MCSymbol *FnStartSym,
326                                                 const MCSymbol *FnEndSym) {}
327 
328 /// Only call this on endian-specific types like ulittle16_t and little32_t, or
329 /// structs composed of them.
330 template <typename T>
331 static void copyBytesForDefRange(SmallString<20> &BytePrefix,
332                                  codeview::SymbolKind SymKind,
333                                  const T &DefRangeHeader) {
334   BytePrefix.resize(2 + sizeof(T));
335   codeview::ulittle16_t SymKindLE = codeview::ulittle16_t(SymKind);
336   memcpy(&BytePrefix[0], &SymKindLE, 2);
337   memcpy(&BytePrefix[2], &DefRangeHeader, sizeof(T));
338 }
339 
340 void MCStreamer::emitCVDefRangeDirective(
341     ArrayRef<std::pair<const MCSymbol *, const MCSymbol *>> Ranges,
342     StringRef FixedSizePortion) {}
343 
344 void MCStreamer::emitCVDefRangeDirective(
345     ArrayRef<std::pair<const MCSymbol *, const MCSymbol *>> Ranges,
346     codeview::DefRangeRegisterRelHeader DRHdr) {
347   SmallString<20> BytePrefix;
348   copyBytesForDefRange(BytePrefix, codeview::S_DEFRANGE_REGISTER_REL, DRHdr);
349   emitCVDefRangeDirective(Ranges, BytePrefix);
350 }
351 
352 void MCStreamer::emitCVDefRangeDirective(
353     ArrayRef<std::pair<const MCSymbol *, const MCSymbol *>> Ranges,
354     codeview::DefRangeSubfieldRegisterHeader DRHdr) {
355   SmallString<20> BytePrefix;
356   copyBytesForDefRange(BytePrefix, codeview::S_DEFRANGE_SUBFIELD_REGISTER,
357                        DRHdr);
358   emitCVDefRangeDirective(Ranges, BytePrefix);
359 }
360 
361 void MCStreamer::emitCVDefRangeDirective(
362     ArrayRef<std::pair<const MCSymbol *, const MCSymbol *>> Ranges,
363     codeview::DefRangeRegisterHeader DRHdr) {
364   SmallString<20> BytePrefix;
365   copyBytesForDefRange(BytePrefix, codeview::S_DEFRANGE_REGISTER, DRHdr);
366   emitCVDefRangeDirective(Ranges, BytePrefix);
367 }
368 
369 void MCStreamer::emitCVDefRangeDirective(
370     ArrayRef<std::pair<const MCSymbol *, const MCSymbol *>> Ranges,
371     codeview::DefRangeFramePointerRelHeader DRHdr) {
372   SmallString<20> BytePrefix;
373   copyBytesForDefRange(BytePrefix, codeview::S_DEFRANGE_FRAMEPOINTER_REL,
374                        DRHdr);
375   emitCVDefRangeDirective(Ranges, BytePrefix);
376 }
377 
378 void MCStreamer::emitEHSymAttributes(const MCSymbol *Symbol,
379                                      MCSymbol *EHSymbol) {
380 }
381 
382 void MCStreamer::InitSections(bool NoExecStack) {
383   SwitchSection(getContext().getObjectFileInfo()->getTextSection());
384 }
385 
386 void MCStreamer::AssignFragment(MCSymbol *Symbol, MCFragment *Fragment) {
387   assert(Fragment);
388   Symbol->setFragment(Fragment);
389 
390   // As we emit symbols into a section, track the order so that they can
391   // be sorted upon later. Zero is reserved to mean 'unemitted'.
392   SymbolOrdering[Symbol] = 1 + SymbolOrdering.size();
393 }
394 
395 void MCStreamer::emitLabel(MCSymbol *Symbol, SMLoc Loc) {
396   Symbol->redefineIfPossible();
397 
398   if (!Symbol->isUndefined() || Symbol->isVariable())
399     return getContext().reportError(Loc, "invalid symbol redefinition");
400 
401   assert(!Symbol->isVariable() && "Cannot emit a variable symbol!");
402   assert(getCurrentSectionOnly() && "Cannot emit before setting section!");
403   assert(!Symbol->getFragment() && "Unexpected fragment on symbol data!");
404   assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
405 
406   Symbol->setFragment(&getCurrentSectionOnly()->getDummyFragment());
407 
408   MCTargetStreamer *TS = getTargetStreamer();
409   if (TS)
410     TS->emitLabel(Symbol);
411 }
412 
413 void MCStreamer::emitCFISections(bool EH, bool Debug) {
414   assert(EH || Debug);
415 }
416 
417 void MCStreamer::emitCFIStartProc(bool IsSimple, SMLoc Loc) {
418   if (hasUnfinishedDwarfFrameInfo())
419     return getContext().reportError(
420         Loc, "starting new .cfi frame before finishing the previous one");
421 
422   MCDwarfFrameInfo Frame;
423   Frame.IsSimple = IsSimple;
424   emitCFIStartProcImpl(Frame);
425 
426   const MCAsmInfo* MAI = Context.getAsmInfo();
427   if (MAI) {
428     for (const MCCFIInstruction& Inst : MAI->getInitialFrameState()) {
429       if (Inst.getOperation() == MCCFIInstruction::OpDefCfa ||
430           Inst.getOperation() == MCCFIInstruction::OpDefCfaRegister) {
431         Frame.CurrentCfaRegister = Inst.getRegister();
432       }
433     }
434   }
435 
436   DwarfFrameInfos.push_back(Frame);
437 }
438 
439 void MCStreamer::emitCFIStartProcImpl(MCDwarfFrameInfo &Frame) {
440 }
441 
442 void MCStreamer::emitCFIEndProc() {
443   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
444   if (!CurFrame)
445     return;
446   emitCFIEndProcImpl(*CurFrame);
447 }
448 
449 void MCStreamer::emitCFIEndProcImpl(MCDwarfFrameInfo &Frame) {
450   // Put a dummy non-null value in Frame.End to mark that this frame has been
451   // closed.
452   Frame.End = (MCSymbol *)1;
453 }
454 
455 MCSymbol *MCStreamer::emitCFILabel() {
456   // Return a dummy non-null value so that label fields appear filled in when
457   // generating textual assembly.
458   return (MCSymbol *)1;
459 }
460 
461 void MCStreamer::emitCFIDefCfa(int64_t Register, int64_t Offset) {
462   MCSymbol *Label = emitCFILabel();
463   MCCFIInstruction Instruction =
464       MCCFIInstruction::cfiDefCfa(Label, Register, Offset);
465   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
466   if (!CurFrame)
467     return;
468   CurFrame->Instructions.push_back(Instruction);
469   CurFrame->CurrentCfaRegister = static_cast<unsigned>(Register);
470 }
471 
472 void MCStreamer::emitCFIDefCfaOffset(int64_t Offset) {
473   MCSymbol *Label = emitCFILabel();
474   MCCFIInstruction Instruction =
475       MCCFIInstruction::cfiDefCfaOffset(Label, Offset);
476   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
477   if (!CurFrame)
478     return;
479   CurFrame->Instructions.push_back(Instruction);
480 }
481 
482 void MCStreamer::emitCFIAdjustCfaOffset(int64_t Adjustment) {
483   MCSymbol *Label = emitCFILabel();
484   MCCFIInstruction Instruction =
485     MCCFIInstruction::createAdjustCfaOffset(Label, Adjustment);
486   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
487   if (!CurFrame)
488     return;
489   CurFrame->Instructions.push_back(Instruction);
490 }
491 
492 void MCStreamer::emitCFIDefCfaRegister(int64_t Register) {
493   MCSymbol *Label = emitCFILabel();
494   MCCFIInstruction Instruction =
495     MCCFIInstruction::createDefCfaRegister(Label, Register);
496   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
497   if (!CurFrame)
498     return;
499   CurFrame->Instructions.push_back(Instruction);
500   CurFrame->CurrentCfaRegister = static_cast<unsigned>(Register);
501 }
502 
503 void MCStreamer::emitCFIOffset(int64_t Register, int64_t Offset) {
504   MCSymbol *Label = emitCFILabel();
505   MCCFIInstruction Instruction =
506     MCCFIInstruction::createOffset(Label, Register, Offset);
507   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
508   if (!CurFrame)
509     return;
510   CurFrame->Instructions.push_back(Instruction);
511 }
512 
513 void MCStreamer::emitCFIRelOffset(int64_t Register, int64_t Offset) {
514   MCSymbol *Label = emitCFILabel();
515   MCCFIInstruction Instruction =
516     MCCFIInstruction::createRelOffset(Label, Register, Offset);
517   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
518   if (!CurFrame)
519     return;
520   CurFrame->Instructions.push_back(Instruction);
521 }
522 
523 void MCStreamer::emitCFIPersonality(const MCSymbol *Sym,
524                                     unsigned Encoding) {
525   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
526   if (!CurFrame)
527     return;
528   CurFrame->Personality = Sym;
529   CurFrame->PersonalityEncoding = Encoding;
530 }
531 
532 void MCStreamer::emitCFILsda(const MCSymbol *Sym, unsigned Encoding) {
533   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
534   if (!CurFrame)
535     return;
536   CurFrame->Lsda = Sym;
537   CurFrame->LsdaEncoding = Encoding;
538 }
539 
540 void MCStreamer::emitCFIRememberState() {
541   MCSymbol *Label = emitCFILabel();
542   MCCFIInstruction Instruction = MCCFIInstruction::createRememberState(Label);
543   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
544   if (!CurFrame)
545     return;
546   CurFrame->Instructions.push_back(Instruction);
547 }
548 
549 void MCStreamer::emitCFIRestoreState() {
550   // FIXME: Error if there is no matching cfi_remember_state.
551   MCSymbol *Label = emitCFILabel();
552   MCCFIInstruction Instruction = MCCFIInstruction::createRestoreState(Label);
553   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
554   if (!CurFrame)
555     return;
556   CurFrame->Instructions.push_back(Instruction);
557 }
558 
559 void MCStreamer::emitCFISameValue(int64_t Register) {
560   MCSymbol *Label = emitCFILabel();
561   MCCFIInstruction Instruction =
562     MCCFIInstruction::createSameValue(Label, Register);
563   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
564   if (!CurFrame)
565     return;
566   CurFrame->Instructions.push_back(Instruction);
567 }
568 
569 void MCStreamer::emitCFIRestore(int64_t Register) {
570   MCSymbol *Label = emitCFILabel();
571   MCCFIInstruction Instruction =
572     MCCFIInstruction::createRestore(Label, Register);
573   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
574   if (!CurFrame)
575     return;
576   CurFrame->Instructions.push_back(Instruction);
577 }
578 
579 void MCStreamer::emitCFIEscape(StringRef Values) {
580   MCSymbol *Label = emitCFILabel();
581   MCCFIInstruction Instruction = MCCFIInstruction::createEscape(Label, Values);
582   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
583   if (!CurFrame)
584     return;
585   CurFrame->Instructions.push_back(Instruction);
586 }
587 
588 void MCStreamer::emitCFIGnuArgsSize(int64_t Size) {
589   MCSymbol *Label = emitCFILabel();
590   MCCFIInstruction Instruction =
591     MCCFIInstruction::createGnuArgsSize(Label, Size);
592   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
593   if (!CurFrame)
594     return;
595   CurFrame->Instructions.push_back(Instruction);
596 }
597 
598 void MCStreamer::emitCFISignalFrame() {
599   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
600   if (!CurFrame)
601     return;
602   CurFrame->IsSignalFrame = true;
603 }
604 
605 void MCStreamer::emitCFIUndefined(int64_t Register) {
606   MCSymbol *Label = emitCFILabel();
607   MCCFIInstruction Instruction =
608     MCCFIInstruction::createUndefined(Label, Register);
609   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
610   if (!CurFrame)
611     return;
612   CurFrame->Instructions.push_back(Instruction);
613 }
614 
615 void MCStreamer::emitCFIRegister(int64_t Register1, int64_t Register2) {
616   MCSymbol *Label = emitCFILabel();
617   MCCFIInstruction Instruction =
618     MCCFIInstruction::createRegister(Label, Register1, Register2);
619   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
620   if (!CurFrame)
621     return;
622   CurFrame->Instructions.push_back(Instruction);
623 }
624 
625 void MCStreamer::emitCFIWindowSave() {
626   MCSymbol *Label = emitCFILabel();
627   MCCFIInstruction Instruction =
628     MCCFIInstruction::createWindowSave(Label);
629   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
630   if (!CurFrame)
631     return;
632   CurFrame->Instructions.push_back(Instruction);
633 }
634 
635 void MCStreamer::emitCFINegateRAState() {
636   MCSymbol *Label = emitCFILabel();
637   MCCFIInstruction Instruction = MCCFIInstruction::createNegateRAState(Label);
638   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
639   if (!CurFrame)
640     return;
641   CurFrame->Instructions.push_back(Instruction);
642 }
643 
644 void MCStreamer::emitCFIReturnColumn(int64_t Register) {
645   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
646   if (!CurFrame)
647     return;
648   CurFrame->RAReg = Register;
649 }
650 
651 WinEH::FrameInfo *MCStreamer::EnsureValidWinFrameInfo(SMLoc Loc) {
652   const MCAsmInfo *MAI = Context.getAsmInfo();
653   if (!MAI->usesWindowsCFI()) {
654     getContext().reportError(
655         Loc, ".seh_* directives are not supported on this target");
656     return nullptr;
657   }
658   if (!CurrentWinFrameInfo || CurrentWinFrameInfo->End) {
659     getContext().reportError(
660         Loc, ".seh_ directive must appear within an active frame");
661     return nullptr;
662   }
663   return CurrentWinFrameInfo;
664 }
665 
666 void MCStreamer::EmitWinCFIStartProc(const MCSymbol *Symbol, SMLoc Loc) {
667   const MCAsmInfo *MAI = Context.getAsmInfo();
668   if (!MAI->usesWindowsCFI())
669     return getContext().reportError(
670         Loc, ".seh_* directives are not supported on this target");
671   if (CurrentWinFrameInfo && !CurrentWinFrameInfo->End)
672     getContext().reportError(
673         Loc, "Starting a function before ending the previous one!");
674 
675   MCSymbol *StartProc = emitCFILabel();
676 
677   WinFrameInfos.emplace_back(
678       std::make_unique<WinEH::FrameInfo>(Symbol, StartProc));
679   CurrentWinFrameInfo = WinFrameInfos.back().get();
680   CurrentWinFrameInfo->TextSection = getCurrentSectionOnly();
681 }
682 
683 void MCStreamer::EmitWinCFIEndProc(SMLoc Loc) {
684   WinEH::FrameInfo *CurFrame = EnsureValidWinFrameInfo(Loc);
685   if (!CurFrame)
686     return;
687   if (CurFrame->ChainedParent)
688     getContext().reportError(Loc, "Not all chained regions terminated!");
689 
690   MCSymbol *Label = emitCFILabel();
691   CurFrame->End = Label;
692 }
693 
694 void MCStreamer::EmitWinCFIFuncletOrFuncEnd(SMLoc Loc) {
695   WinEH::FrameInfo *CurFrame = EnsureValidWinFrameInfo(Loc);
696   if (!CurFrame)
697     return;
698   if (CurFrame->ChainedParent)
699     getContext().reportError(Loc, "Not all chained regions terminated!");
700 
701   MCSymbol *Label = emitCFILabel();
702   CurFrame->FuncletOrFuncEnd = Label;
703 }
704 
705 void MCStreamer::EmitWinCFIStartChained(SMLoc Loc) {
706   WinEH::FrameInfo *CurFrame = EnsureValidWinFrameInfo(Loc);
707   if (!CurFrame)
708     return;
709 
710   MCSymbol *StartProc = emitCFILabel();
711 
712   WinFrameInfos.emplace_back(std::make_unique<WinEH::FrameInfo>(
713       CurFrame->Function, StartProc, CurFrame));
714   CurrentWinFrameInfo = WinFrameInfos.back().get();
715   CurrentWinFrameInfo->TextSection = getCurrentSectionOnly();
716 }
717 
718 void MCStreamer::EmitWinCFIEndChained(SMLoc Loc) {
719   WinEH::FrameInfo *CurFrame = EnsureValidWinFrameInfo(Loc);
720   if (!CurFrame)
721     return;
722   if (!CurFrame->ChainedParent)
723     return getContext().reportError(
724         Loc, "End of a chained region outside a chained region!");
725 
726   MCSymbol *Label = emitCFILabel();
727 
728   CurFrame->End = Label;
729   CurrentWinFrameInfo = const_cast<WinEH::FrameInfo *>(CurFrame->ChainedParent);
730 }
731 
732 void MCStreamer::EmitWinEHHandler(const MCSymbol *Sym, bool Unwind, bool Except,
733                                   SMLoc Loc) {
734   WinEH::FrameInfo *CurFrame = EnsureValidWinFrameInfo(Loc);
735   if (!CurFrame)
736     return;
737   if (CurFrame->ChainedParent)
738     return getContext().reportError(
739         Loc, "Chained unwind areas can't have handlers!");
740   CurFrame->ExceptionHandler = Sym;
741   if (!Except && !Unwind)
742     getContext().reportError(Loc, "Don't know what kind of handler this is!");
743   if (Unwind)
744     CurFrame->HandlesUnwind = true;
745   if (Except)
746     CurFrame->HandlesExceptions = true;
747 }
748 
749 void MCStreamer::EmitWinEHHandlerData(SMLoc Loc) {
750   WinEH::FrameInfo *CurFrame = EnsureValidWinFrameInfo(Loc);
751   if (!CurFrame)
752     return;
753   if (CurFrame->ChainedParent)
754     getContext().reportError(Loc, "Chained unwind areas can't have handlers!");
755 }
756 
757 void MCStreamer::emitCGProfileEntry(const MCSymbolRefExpr *From,
758                                     const MCSymbolRefExpr *To, uint64_t Count) {
759 }
760 
761 static MCSection *getWinCFISection(MCContext &Context, unsigned *NextWinCFIID,
762                                    MCSection *MainCFISec,
763                                    const MCSection *TextSec) {
764   // If this is the main .text section, use the main unwind info section.
765   if (TextSec == Context.getObjectFileInfo()->getTextSection())
766     return MainCFISec;
767 
768   const auto *TextSecCOFF = cast<MCSectionCOFF>(TextSec);
769   auto *MainCFISecCOFF = cast<MCSectionCOFF>(MainCFISec);
770   unsigned UniqueID = TextSecCOFF->getOrAssignWinCFISectionID(NextWinCFIID);
771 
772   // If this section is COMDAT, this unwind section should be COMDAT associative
773   // with its group.
774   const MCSymbol *KeySym = nullptr;
775   if (TextSecCOFF->getCharacteristics() & COFF::IMAGE_SCN_LNK_COMDAT) {
776     KeySym = TextSecCOFF->getCOMDATSymbol();
777 
778     // In a GNU environment, we can't use associative comdats. Instead, do what
779     // GCC does, which is to make plain comdat selectany section named like
780     // ".[px]data$_Z3foov".
781     if (!Context.getAsmInfo()->hasCOFFAssociativeComdats()) {
782       std::string SectionName = (MainCFISecCOFF->getName() + "$" +
783                                  TextSecCOFF->getName().split('$').second)
784                                     .str();
785       return Context.getCOFFSection(
786           SectionName,
787           MainCFISecCOFF->getCharacteristics() | COFF::IMAGE_SCN_LNK_COMDAT,
788           MainCFISecCOFF->getKind(), "", COFF::IMAGE_COMDAT_SELECT_ANY);
789     }
790   }
791 
792   return Context.getAssociativeCOFFSection(MainCFISecCOFF, KeySym, UniqueID);
793 }
794 
795 MCSection *MCStreamer::getAssociatedPDataSection(const MCSection *TextSec) {
796   return getWinCFISection(getContext(), &NextWinCFIID,
797                           getContext().getObjectFileInfo()->getPDataSection(),
798                           TextSec);
799 }
800 
801 MCSection *MCStreamer::getAssociatedXDataSection(const MCSection *TextSec) {
802   return getWinCFISection(getContext(), &NextWinCFIID,
803                           getContext().getObjectFileInfo()->getXDataSection(),
804                           TextSec);
805 }
806 
807 void MCStreamer::emitSyntaxDirective() {}
808 
809 static unsigned encodeSEHRegNum(MCContext &Ctx, MCRegister Reg) {
810   return Ctx.getRegisterInfo()->getSEHRegNum(Reg);
811 }
812 
813 void MCStreamer::EmitWinCFIPushReg(MCRegister Register, SMLoc Loc) {
814   WinEH::FrameInfo *CurFrame = EnsureValidWinFrameInfo(Loc);
815   if (!CurFrame)
816     return;
817 
818   MCSymbol *Label = emitCFILabel();
819 
820   WinEH::Instruction Inst = Win64EH::Instruction::PushNonVol(
821       Label, encodeSEHRegNum(Context, Register));
822   CurFrame->Instructions.push_back(Inst);
823 }
824 
825 void MCStreamer::EmitWinCFISetFrame(MCRegister Register, unsigned Offset,
826                                     SMLoc Loc) {
827   WinEH::FrameInfo *CurFrame = EnsureValidWinFrameInfo(Loc);
828   if (!CurFrame)
829     return;
830   if (CurFrame->LastFrameInst >= 0)
831     return getContext().reportError(
832         Loc, "frame register and offset can be set at most once");
833   if (Offset & 0x0F)
834     return getContext().reportError(Loc, "offset is not a multiple of 16");
835   if (Offset > 240)
836     return getContext().reportError(
837         Loc, "frame offset must be less than or equal to 240");
838 
839   MCSymbol *Label = emitCFILabel();
840 
841   WinEH::Instruction Inst = Win64EH::Instruction::SetFPReg(
842       Label, encodeSEHRegNum(getContext(), Register), Offset);
843   CurFrame->LastFrameInst = CurFrame->Instructions.size();
844   CurFrame->Instructions.push_back(Inst);
845 }
846 
847 void MCStreamer::EmitWinCFIAllocStack(unsigned Size, SMLoc Loc) {
848   WinEH::FrameInfo *CurFrame = EnsureValidWinFrameInfo(Loc);
849   if (!CurFrame)
850     return;
851   if (Size == 0)
852     return getContext().reportError(Loc,
853                                     "stack allocation size must be non-zero");
854   if (Size & 7)
855     return getContext().reportError(
856         Loc, "stack allocation size is not a multiple of 8");
857 
858   MCSymbol *Label = emitCFILabel();
859 
860   WinEH::Instruction Inst = Win64EH::Instruction::Alloc(Label, Size);
861   CurFrame->Instructions.push_back(Inst);
862 }
863 
864 void MCStreamer::EmitWinCFISaveReg(MCRegister Register, unsigned Offset,
865                                    SMLoc Loc) {
866   WinEH::FrameInfo *CurFrame = EnsureValidWinFrameInfo(Loc);
867   if (!CurFrame)
868     return;
869 
870   if (Offset & 7)
871     return getContext().reportError(
872         Loc, "register save offset is not 8 byte aligned");
873 
874   MCSymbol *Label = emitCFILabel();
875 
876   WinEH::Instruction Inst = Win64EH::Instruction::SaveNonVol(
877       Label, encodeSEHRegNum(Context, Register), Offset);
878   CurFrame->Instructions.push_back(Inst);
879 }
880 
881 void MCStreamer::EmitWinCFISaveXMM(MCRegister Register, unsigned Offset,
882                                    SMLoc Loc) {
883   WinEH::FrameInfo *CurFrame = EnsureValidWinFrameInfo(Loc);
884   if (!CurFrame)
885     return;
886   if (Offset & 0x0F)
887     return getContext().reportError(Loc, "offset is not a multiple of 16");
888 
889   MCSymbol *Label = emitCFILabel();
890 
891   WinEH::Instruction Inst = Win64EH::Instruction::SaveXMM(
892       Label, encodeSEHRegNum(Context, Register), Offset);
893   CurFrame->Instructions.push_back(Inst);
894 }
895 
896 void MCStreamer::EmitWinCFIPushFrame(bool Code, SMLoc Loc) {
897   WinEH::FrameInfo *CurFrame = EnsureValidWinFrameInfo(Loc);
898   if (!CurFrame)
899     return;
900   if (!CurFrame->Instructions.empty())
901     return getContext().reportError(
902         Loc, "If present, PushMachFrame must be the first UOP");
903 
904   MCSymbol *Label = emitCFILabel();
905 
906   WinEH::Instruction Inst = Win64EH::Instruction::PushMachFrame(Label, Code);
907   CurFrame->Instructions.push_back(Inst);
908 }
909 
910 void MCStreamer::EmitWinCFIEndProlog(SMLoc Loc) {
911   WinEH::FrameInfo *CurFrame = EnsureValidWinFrameInfo(Loc);
912   if (!CurFrame)
913     return;
914 
915   MCSymbol *Label = emitCFILabel();
916 
917   CurFrame->PrologEnd = Label;
918 }
919 
920 void MCStreamer::EmitCOFFSafeSEH(MCSymbol const *Symbol) {}
921 
922 void MCStreamer::EmitCOFFSymbolIndex(MCSymbol const *Symbol) {}
923 
924 void MCStreamer::EmitCOFFSectionIndex(MCSymbol const *Symbol) {}
925 
926 void MCStreamer::EmitCOFFSecRel32(MCSymbol const *Symbol, uint64_t Offset) {}
927 
928 void MCStreamer::EmitCOFFImgRel32(MCSymbol const *Symbol, int64_t Offset) {}
929 
930 /// EmitRawText - If this file is backed by an assembly streamer, this dumps
931 /// the specified string in the output .s file.  This capability is
932 /// indicated by the hasRawTextSupport() predicate.
933 void MCStreamer::emitRawTextImpl(StringRef String) {
934   // This is not llvm_unreachable for the sake of out of tree backend
935   // developers who may not have assembly streamers and should serve as a
936   // reminder to not accidentally call EmitRawText in the absence of such.
937   report_fatal_error("EmitRawText called on an MCStreamer that doesn't support "
938                      "it (target backend is likely missing an AsmStreamer "
939                      "implementation)");
940 }
941 
942 void MCStreamer::emitRawText(const Twine &T) {
943   SmallString<128> Str;
944   emitRawTextImpl(T.toStringRef(Str));
945 }
946 
947 void MCStreamer::EmitWindowsUnwindTables() {
948 }
949 
950 void MCStreamer::Finish() {
951   if ((!DwarfFrameInfos.empty() && !DwarfFrameInfos.back().End) ||
952       (!WinFrameInfos.empty() && !WinFrameInfos.back()->End)) {
953     getContext().reportError(SMLoc(), "Unfinished frame!");
954     return;
955   }
956 
957   MCTargetStreamer *TS = getTargetStreamer();
958   if (TS)
959     TS->finish();
960 
961   finishImpl();
962 }
963 
964 void MCStreamer::emitAssignment(MCSymbol *Symbol, const MCExpr *Value) {
965   visitUsedExpr(*Value);
966   Symbol->setVariableValue(Value);
967 
968   MCTargetStreamer *TS = getTargetStreamer();
969   if (TS)
970     TS->emitAssignment(Symbol, Value);
971 }
972 
973 void MCTargetStreamer::prettyPrintAsm(MCInstPrinter &InstPrinter,
974                                       uint64_t Address, const MCInst &Inst,
975                                       const MCSubtargetInfo &STI,
976                                       raw_ostream &OS) {
977   InstPrinter.printInst(&Inst, Address, "", STI, OS);
978 }
979 
980 void MCStreamer::visitUsedSymbol(const MCSymbol &Sym) {
981 }
982 
983 void MCStreamer::visitUsedExpr(const MCExpr &Expr) {
984   switch (Expr.getKind()) {
985   case MCExpr::Target:
986     cast<MCTargetExpr>(Expr).visitUsedExpr(*this);
987     break;
988 
989   case MCExpr::Constant:
990     break;
991 
992   case MCExpr::Binary: {
993     const MCBinaryExpr &BE = cast<MCBinaryExpr>(Expr);
994     visitUsedExpr(*BE.getLHS());
995     visitUsedExpr(*BE.getRHS());
996     break;
997   }
998 
999   case MCExpr::SymbolRef:
1000     visitUsedSymbol(cast<MCSymbolRefExpr>(Expr).getSymbol());
1001     break;
1002 
1003   case MCExpr::Unary:
1004     visitUsedExpr(*cast<MCUnaryExpr>(Expr).getSubExpr());
1005     break;
1006   }
1007 }
1008 
1009 void MCStreamer::emitInstruction(const MCInst &Inst, const MCSubtargetInfo &) {
1010   // Scan for values.
1011   for (unsigned i = Inst.getNumOperands(); i--;)
1012     if (Inst.getOperand(i).isExpr())
1013       visitUsedExpr(*Inst.getOperand(i).getExpr());
1014 }
1015 
1016 void MCStreamer::emitAbsoluteSymbolDiff(const MCSymbol *Hi, const MCSymbol *Lo,
1017                                         unsigned Size) {
1018   // Get the Hi-Lo expression.
1019   const MCExpr *Diff =
1020       MCBinaryExpr::createSub(MCSymbolRefExpr::create(Hi, Context),
1021                               MCSymbolRefExpr::create(Lo, Context), Context);
1022 
1023   const MCAsmInfo *MAI = Context.getAsmInfo();
1024   if (!MAI->doesSetDirectiveSuppressReloc()) {
1025     emitValue(Diff, Size);
1026     return;
1027   }
1028 
1029   // Otherwise, emit with .set (aka assignment).
1030   MCSymbol *SetLabel = Context.createTempSymbol("set", true);
1031   emitAssignment(SetLabel, Diff);
1032   emitSymbolValue(SetLabel, Size);
1033 }
1034 
1035 void MCStreamer::emitAbsoluteSymbolDiffAsULEB128(const MCSymbol *Hi,
1036                                                  const MCSymbol *Lo) {
1037   // Get the Hi-Lo expression.
1038   const MCExpr *Diff =
1039       MCBinaryExpr::createSub(MCSymbolRefExpr::create(Hi, Context),
1040                               MCSymbolRefExpr::create(Lo, Context), Context);
1041 
1042   emitULEB128Value(Diff);
1043 }
1044 
1045 void MCStreamer::emitAssemblerFlag(MCAssemblerFlag Flag) {}
1046 void MCStreamer::emitThumbFunc(MCSymbol *Func) {}
1047 void MCStreamer::emitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {}
1048 void MCStreamer::BeginCOFFSymbolDef(const MCSymbol *Symbol) {
1049   llvm_unreachable("this directive only supported on COFF targets");
1050 }
1051 void MCStreamer::EndCOFFSymbolDef() {
1052   llvm_unreachable("this directive only supported on COFF targets");
1053 }
1054 void MCStreamer::emitFileDirective(StringRef Filename) {}
1055 void MCStreamer::EmitCOFFSymbolStorageClass(int StorageClass) {
1056   llvm_unreachable("this directive only supported on COFF targets");
1057 }
1058 void MCStreamer::EmitCOFFSymbolType(int Type) {
1059   llvm_unreachable("this directive only supported on COFF targets");
1060 }
1061 void MCStreamer::emitXCOFFLocalCommonSymbol(MCSymbol *LabelSym, uint64_t Size,
1062                                             MCSymbol *CsectSym,
1063                                             unsigned ByteAlign) {
1064   llvm_unreachable("this directive only supported on XCOFF targets");
1065 }
1066 
1067 void MCStreamer::emitXCOFFSymbolLinkageWithVisibility(MCSymbol *Symbol,
1068                                                       MCSymbolAttr Linkage,
1069                                                       MCSymbolAttr Visibility) {
1070   llvm_unreachable("emitXCOFFSymbolLinkageWithVisibility is only supported on "
1071                    "XCOFF targets");
1072 }
1073 
1074 void MCStreamer::emitXCOFFRenameDirective(const MCSymbol *Name,
1075                                           StringRef Rename) {
1076   llvm_unreachable("emitXCOFFRenameDirective is only supported on "
1077                    "XCOFF targets");
1078 }
1079 
1080 void MCStreamer::emitELFSize(MCSymbol *Symbol, const MCExpr *Value) {}
1081 void MCStreamer::emitELFSymverDirective(StringRef AliasName,
1082                                         const MCSymbol *Aliasee) {}
1083 void MCStreamer::emitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,
1084                                        unsigned ByteAlignment) {}
1085 void MCStreamer::emitTBSSSymbol(MCSection *Section, MCSymbol *Symbol,
1086                                 uint64_t Size, unsigned ByteAlignment) {}
1087 void MCStreamer::changeSection(MCSection *, const MCExpr *) {}
1088 void MCStreamer::emitWeakReference(MCSymbol *Alias, const MCSymbol *Symbol) {}
1089 void MCStreamer::emitBytes(StringRef Data) {}
1090 void MCStreamer::emitBinaryData(StringRef Data) { emitBytes(Data); }
1091 void MCStreamer::emitValueImpl(const MCExpr *Value, unsigned Size, SMLoc Loc) {
1092   visitUsedExpr(*Value);
1093 }
1094 void MCStreamer::emitULEB128Value(const MCExpr *Value) {}
1095 void MCStreamer::emitSLEB128Value(const MCExpr *Value) {}
1096 void MCStreamer::emitFill(const MCExpr &NumBytes, uint64_t Value, SMLoc Loc) {}
1097 void MCStreamer::emitFill(const MCExpr &NumValues, int64_t Size, int64_t Expr,
1098                           SMLoc Loc) {}
1099 void MCStreamer::emitValueToAlignment(unsigned ByteAlignment, int64_t Value,
1100                                       unsigned ValueSize,
1101                                       unsigned MaxBytesToEmit) {}
1102 void MCStreamer::emitCodeAlignment(unsigned ByteAlignment,
1103                                    unsigned MaxBytesToEmit) {}
1104 void MCStreamer::emitValueToOffset(const MCExpr *Offset, unsigned char Value,
1105                                    SMLoc Loc) {}
1106 void MCStreamer::emitBundleAlignMode(unsigned AlignPow2) {}
1107 void MCStreamer::emitBundleLock(bool AlignToEnd) {}
1108 void MCStreamer::finishImpl() {}
1109 void MCStreamer::emitBundleUnlock() {}
1110 
1111 void MCStreamer::SwitchSection(MCSection *Section, const MCExpr *Subsection) {
1112   assert(Section && "Cannot switch to a null section!");
1113   MCSectionSubPair curSection = SectionStack.back().first;
1114   SectionStack.back().second = curSection;
1115   if (MCSectionSubPair(Section, Subsection) != curSection) {
1116     changeSection(Section, Subsection);
1117     SectionStack.back().first = MCSectionSubPair(Section, Subsection);
1118     assert(!Section->hasEnded() && "Section already ended");
1119     MCSymbol *Sym = Section->getBeginSymbol();
1120     if (Sym && !Sym->isInSection())
1121       emitLabel(Sym);
1122   }
1123 }
1124 
1125 MCSymbol *MCStreamer::endSection(MCSection *Section) {
1126   // TODO: keep track of the last subsection so that this symbol appears in the
1127   // correct place.
1128   MCSymbol *Sym = Section->getEndSymbol(Context);
1129   if (Sym->isInSection())
1130     return Sym;
1131 
1132   SwitchSection(Section);
1133   emitLabel(Sym);
1134   return Sym;
1135 }
1136 
1137 static VersionTuple
1138 targetVersionOrMinimumSupportedOSVersion(const Triple &Target,
1139                                          VersionTuple TargetVersion) {
1140   VersionTuple Min = Target.getMinimumSupportedOSVersion();
1141   return !Min.empty() && Min > TargetVersion ? Min : TargetVersion;
1142 }
1143 
1144 static MCVersionMinType
1145 getMachoVersionMinLoadCommandType(const Triple &Target) {
1146   assert(Target.isOSDarwin() && "expected a darwin OS");
1147   switch (Target.getOS()) {
1148   case Triple::MacOSX:
1149   case Triple::Darwin:
1150     return MCVM_OSXVersionMin;
1151   case Triple::IOS:
1152     assert(!Target.isMacCatalystEnvironment() &&
1153            "mac Catalyst should use LC_BUILD_VERSION");
1154     return MCVM_IOSVersionMin;
1155   case Triple::TvOS:
1156     return MCVM_TvOSVersionMin;
1157   case Triple::WatchOS:
1158     return MCVM_WatchOSVersionMin;
1159   default:
1160     break;
1161   }
1162   llvm_unreachable("unexpected OS type");
1163 }
1164 
1165 static VersionTuple getMachoBuildVersionSupportedOS(const Triple &Target) {
1166   assert(Target.isOSDarwin() && "expected a darwin OS");
1167   switch (Target.getOS()) {
1168   case Triple::MacOSX:
1169   case Triple::Darwin:
1170     return VersionTuple(10, 14);
1171   case Triple::IOS:
1172     // Mac Catalyst always uses the build version load command.
1173     if (Target.isMacCatalystEnvironment())
1174       return VersionTuple();
1175     LLVM_FALLTHROUGH;
1176   case Triple::TvOS:
1177     return VersionTuple(12);
1178   case Triple::WatchOS:
1179     return VersionTuple(5);
1180   default:
1181     break;
1182   }
1183   llvm_unreachable("unexpected OS type");
1184 }
1185 
1186 static MachO::PlatformType
1187 getMachoBuildVersionPlatformType(const Triple &Target) {
1188   assert(Target.isOSDarwin() && "expected a darwin OS");
1189   switch (Target.getOS()) {
1190   case Triple::MacOSX:
1191   case Triple::Darwin:
1192     return MachO::PLATFORM_MACOS;
1193   case Triple::IOS:
1194     if (Target.isMacCatalystEnvironment())
1195       return MachO::PLATFORM_MACCATALYST;
1196     return Target.isSimulatorEnvironment() ? MachO::PLATFORM_IOSSIMULATOR
1197                                            : MachO::PLATFORM_IOS;
1198   case Triple::TvOS:
1199     return Target.isSimulatorEnvironment() ? MachO::PLATFORM_TVOSSIMULATOR
1200                                            : MachO::PLATFORM_TVOS;
1201   case Triple::WatchOS:
1202     return Target.isSimulatorEnvironment() ? MachO::PLATFORM_WATCHOSSIMULATOR
1203                                            : MachO::PLATFORM_WATCHOS;
1204   default:
1205     break;
1206   }
1207   llvm_unreachable("unexpected OS type");
1208 }
1209 
1210 void MCStreamer::emitVersionForTarget(const Triple &Target,
1211                                       const VersionTuple &SDKVersion) {
1212   if (!Target.isOSBinFormatMachO() || !Target.isOSDarwin())
1213     return;
1214   // Do we even know the version?
1215   if (Target.getOSMajorVersion() == 0)
1216     return;
1217 
1218   unsigned Major = 0;
1219   unsigned Minor = 0;
1220   unsigned Update = 0;
1221   switch (Target.getOS()) {
1222   case Triple::MacOSX:
1223   case Triple::Darwin:
1224     Target.getMacOSXVersion(Major, Minor, Update);
1225     break;
1226   case Triple::IOS:
1227   case Triple::TvOS:
1228     Target.getiOSVersion(Major, Minor, Update);
1229     break;
1230   case Triple::WatchOS:
1231     Target.getWatchOSVersion(Major, Minor, Update);
1232     break;
1233   default:
1234     llvm_unreachable("unexpected OS type");
1235   }
1236   assert(Major != 0 && "A non-zero major version is expected");
1237   auto LinkedTargetVersion = targetVersionOrMinimumSupportedOSVersion(
1238       Target, VersionTuple(Major, Minor, Update));
1239   auto BuildVersionOSVersion = getMachoBuildVersionSupportedOS(Target);
1240   if (BuildVersionOSVersion.empty() ||
1241       LinkedTargetVersion >= BuildVersionOSVersion)
1242     return emitBuildVersion(getMachoBuildVersionPlatformType(Target),
1243                             LinkedTargetVersion.getMajor(),
1244                             *LinkedTargetVersion.getMinor(),
1245                             *LinkedTargetVersion.getSubminor(), SDKVersion);
1246 
1247   emitVersionMin(getMachoVersionMinLoadCommandType(Target),
1248                  LinkedTargetVersion.getMajor(),
1249                  *LinkedTargetVersion.getMinor(),
1250                  *LinkedTargetVersion.getSubminor(), SDKVersion);
1251 }
1252