xref: /llvm-project/llvm/lib/MC/MCStreamer.cpp (revision 283dca56f8dddbf2f144730a01675c94b04f57cb) 
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/SmallString.h"
11 #include "llvm/ADT/StringRef.h"
12 #include "llvm/ADT/Twine.h"
13 #include "llvm/BinaryFormat/COFF.h"
14 #include "llvm/BinaryFormat/MachO.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/MCPseudoProbe.h"
26 #include "llvm/MC/MCRegister.h"
27 #include "llvm/MC/MCRegisterInfo.h"
28 #include "llvm/MC/MCSection.h"
29 #include "llvm/MC/MCSectionCOFF.h"
30 #include "llvm/MC/MCSymbol.h"
31 #include "llvm/MC/MCWin64EH.h"
32 #include "llvm/MC/MCWinEH.h"
33 #include "llvm/Support/Casting.h"
34 #include "llvm/Support/ErrorHandling.h"
35 #include "llvm/Support/LEB128.h"
36 #include "llvm/Support/MathExtras.h"
37 #include "llvm/Support/raw_ostream.h"
38 #include <cassert>
39 #include <cstdint>
40 #include <cstdlib>
41 #include <optional>
42 #include <utility>
43 
44 using namespace llvm;
45 
46 MCTargetStreamer::MCTargetStreamer(MCStreamer &S) : Streamer(S) {
47   S.setTargetStreamer(this);
48 }
49 
50 // Pin the vtables to this file.
51 MCTargetStreamer::~MCTargetStreamer() = default;
52 
53 void MCTargetStreamer::emitLabel(MCSymbol *Symbol) {}
54 
55 void MCTargetStreamer::finish() {}
56 
57 void MCTargetStreamer::emitConstantPools() {}
58 
59 void MCTargetStreamer::changeSection(const MCSection *CurSection,
60                                      MCSection *Section, uint32_t Subsection,
61                                      raw_ostream &OS) {
62   Section->printSwitchToSection(*Streamer.getContext().getAsmInfo(),
63                                 Streamer.getContext().getTargetTriple(), OS,
64                                 Subsection);
65 }
66 
67 void MCTargetStreamer::emitDwarfFileDirective(StringRef Directive) {
68   Streamer.emitRawText(Directive);
69 }
70 
71 void MCTargetStreamer::emitValue(const MCExpr *Value) {
72   SmallString<128> Str;
73   raw_svector_ostream OS(Str);
74 
75   Value->print(OS, Streamer.getContext().getAsmInfo());
76   Streamer.emitRawText(OS.str());
77 }
78 
79 void MCTargetStreamer::emitRawBytes(StringRef Data) {
80   const MCAsmInfo *MAI = Streamer.getContext().getAsmInfo();
81   const char *Directive = MAI->getData8bitsDirective();
82   for (const unsigned char C : Data.bytes()) {
83     SmallString<128> Str;
84     raw_svector_ostream OS(Str);
85 
86     OS << Directive << (unsigned)C;
87     Streamer.emitRawText(OS.str());
88   }
89 }
90 
91 void MCTargetStreamer::emitAssignment(MCSymbol *Symbol, const MCExpr *Value) {}
92 
93 MCStreamer::MCStreamer(MCContext &Ctx)
94     : Context(Ctx), CurrentWinFrameInfo(nullptr),
95       CurrentProcWinFrameInfoStartIndex(0) {
96   SectionStack.push_back(std::pair<MCSectionSubPair, MCSectionSubPair>());
97 }
98 
99 MCStreamer::~MCStreamer() = default;
100 
101 void MCStreamer::reset() {
102   DwarfFrameInfos.clear();
103   CurrentWinFrameInfo = nullptr;
104   WinFrameInfos.clear();
105   SectionStack.clear();
106   SectionStack.push_back(std::pair<MCSectionSubPair, MCSectionSubPair>());
107   CurFrag = nullptr;
108 }
109 
110 raw_ostream &MCStreamer::getCommentOS() {
111   // By default, discard comments.
112   return nulls();
113 }
114 
115 unsigned MCStreamer::getNumFrameInfos() { return DwarfFrameInfos.size(); }
116 ArrayRef<MCDwarfFrameInfo> MCStreamer::getDwarfFrameInfos() const {
117   return DwarfFrameInfos;
118 }
119 
120 void MCStreamer::emitRawComment(const Twine &T, bool TabPrefix) {}
121 
122 void MCStreamer::addExplicitComment(const Twine &T) {}
123 void MCStreamer::emitExplicitComments() {}
124 
125 void MCStreamer::generateCompactUnwindEncodings(MCAsmBackend *MAB) {
126   for (auto &FI : DwarfFrameInfos)
127     FI.CompactUnwindEncoding =
128         (MAB ? MAB->generateCompactUnwindEncoding(&FI, &Context) : 0);
129 }
130 
131 /// EmitIntValue - Special case of EmitValue that avoids the client having to
132 /// pass in a MCExpr for constant integers.
133 void MCStreamer::emitIntValue(uint64_t Value, unsigned Size) {
134   assert(1 <= Size && Size <= 8 && "Invalid size");
135   assert((isUIntN(8 * Size, Value) || isIntN(8 * Size, Value)) &&
136          "Invalid size");
137   const bool IsLittleEndian = Context.getAsmInfo()->isLittleEndian();
138   uint64_t Swapped = support::endian::byte_swap(
139       Value, IsLittleEndian ? llvm::endianness::little : llvm::endianness::big);
140   unsigned Index = IsLittleEndian ? 0 : 8 - Size;
141   emitBytes(StringRef(reinterpret_cast<char *>(&Swapped) + Index, Size));
142 }
143 void MCStreamer::emitIntValue(const APInt &Value) {
144   if (Value.getNumWords() == 1) {
145     emitIntValue(Value.getLimitedValue(), Value.getBitWidth() / 8);
146     return;
147   }
148 
149   const bool IsLittleEndianTarget = Context.getAsmInfo()->isLittleEndian();
150   const bool ShouldSwap = sys::IsLittleEndianHost != IsLittleEndianTarget;
151   const APInt Swapped = ShouldSwap ? Value.byteSwap() : Value;
152   const unsigned Size = Value.getBitWidth() / 8;
153   SmallString<10> Tmp;
154   Tmp.resize(Size);
155   StoreIntToMemory(Swapped, reinterpret_cast<uint8_t *>(Tmp.data()), Size);
156   emitBytes(Tmp.str());
157 }
158 
159 /// EmitULEB128IntValue - Special case of EmitULEB128Value that avoids the
160 /// client having to pass in a MCExpr for constant integers.
161 unsigned MCStreamer::emitULEB128IntValue(uint64_t Value, unsigned PadTo) {
162   SmallString<128> Tmp;
163   raw_svector_ostream OSE(Tmp);
164   encodeULEB128(Value, OSE, PadTo);
165   emitBytes(OSE.str());
166   return Tmp.size();
167 }
168 
169 /// EmitSLEB128IntValue - Special case of EmitSLEB128Value that avoids the
170 /// client having to pass in a MCExpr for constant integers.
171 unsigned MCStreamer::emitSLEB128IntValue(int64_t Value) {
172   SmallString<128> Tmp;
173   raw_svector_ostream OSE(Tmp);
174   encodeSLEB128(Value, OSE);
175   emitBytes(OSE.str());
176   return Tmp.size();
177 }
178 
179 void MCStreamer::emitValue(const MCExpr *Value, unsigned Size, SMLoc Loc) {
180   emitValueImpl(Value, Size, Loc);
181 }
182 
183 void MCStreamer::emitSymbolValue(const MCSymbol *Sym, unsigned Size,
184                                  bool IsSectionRelative) {
185   assert((!IsSectionRelative || Size == 4) &&
186          "SectionRelative value requires 4-bytes");
187 
188   if (!IsSectionRelative)
189     emitValueImpl(MCSymbolRefExpr::create(Sym, getContext()), Size);
190   else
191     emitCOFFSecRel32(Sym, /*Offset=*/0);
192 }
193 
194 void MCStreamer::emitDTPRel64Value(const MCExpr *Value) {
195   report_fatal_error("unsupported directive in streamer");
196 }
197 
198 void MCStreamer::emitDTPRel32Value(const MCExpr *Value) {
199   report_fatal_error("unsupported directive in streamer");
200 }
201 
202 void MCStreamer::emitTPRel64Value(const MCExpr *Value) {
203   report_fatal_error("unsupported directive in streamer");
204 }
205 
206 void MCStreamer::emitTPRel32Value(const MCExpr *Value) {
207   report_fatal_error("unsupported directive in streamer");
208 }
209 
210 void MCStreamer::emitGPRel64Value(const MCExpr *Value) {
211   report_fatal_error("unsupported directive in streamer");
212 }
213 
214 void MCStreamer::emitGPRel32Value(const MCExpr *Value) {
215   report_fatal_error("unsupported directive in streamer");
216 }
217 
218 /// Emit NumBytes bytes worth of the value specified by FillValue.
219 /// This implements directives such as '.space'.
220 void MCStreamer::emitFill(uint64_t NumBytes, uint8_t FillValue) {
221   if (NumBytes)
222     emitFill(*MCConstantExpr::create(NumBytes, getContext()), FillValue);
223 }
224 
225 void llvm::MCStreamer::emitNops(int64_t NumBytes, int64_t ControlledNopLen,
226                                 llvm::SMLoc, const MCSubtargetInfo& STI) {}
227 
228 /// The implementation in this class just redirects to emitFill.
229 void MCStreamer::emitZeros(uint64_t NumBytes) { emitFill(NumBytes, 0); }
230 
231 Expected<unsigned> MCStreamer::tryEmitDwarfFileDirective(
232     unsigned FileNo, StringRef Directory, StringRef Filename,
233     std::optional<MD5::MD5Result> Checksum, std::optional<StringRef> Source,
234     unsigned CUID) {
235   return getContext().getDwarfFile(Directory, Filename, FileNo, Checksum,
236                                    Source, CUID);
237 }
238 
239 void MCStreamer::emitDwarfFile0Directive(StringRef Directory,
240                                          StringRef Filename,
241                                          std::optional<MD5::MD5Result> Checksum,
242                                          std::optional<StringRef> Source,
243                                          unsigned CUID) {
244   getContext().setMCLineTableRootFile(CUID, Directory, Filename, Checksum,
245                                       Source);
246 }
247 
248 void MCStreamer::emitCFIBKeyFrame() {
249   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
250   if (!CurFrame)
251     return;
252   CurFrame->IsBKeyFrame = true;
253 }
254 
255 void MCStreamer::emitCFIMTETaggedFrame() {
256   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
257   if (!CurFrame)
258     return;
259   CurFrame->IsMTETaggedFrame = true;
260 }
261 
262 void MCStreamer::emitDwarfLocDirective(unsigned FileNo, unsigned Line,
263                                        unsigned Column, unsigned Flags,
264                                        unsigned Isa, unsigned Discriminator,
265                                        StringRef FileName) {
266   getContext().setCurrentDwarfLoc(FileNo, Line, Column, Flags, Isa,
267                                   Discriminator);
268 }
269 
270 void MCStreamer::emitDwarfLocLabelDirective(SMLoc Loc, StringRef Name) {
271   getContext()
272       .getMCDwarfLineTable(getContext().getDwarfCompileUnitID())
273       .endCurrentSeqAndEmitLineStreamLabel(this, Loc, Name);
274 }
275 
276 MCSymbol *MCStreamer::getDwarfLineTableSymbol(unsigned CUID) {
277   MCDwarfLineTable &Table = getContext().getMCDwarfLineTable(CUID);
278   if (!Table.getLabel()) {
279     StringRef Prefix = Context.getAsmInfo()->getPrivateGlobalPrefix();
280     Table.setLabel(
281         Context.getOrCreateSymbol(Prefix + "line_table_start" + Twine(CUID)));
282   }
283   return Table.getLabel();
284 }
285 
286 bool MCStreamer::hasUnfinishedDwarfFrameInfo() {
287   return !FrameInfoStack.empty();
288 }
289 
290 MCDwarfFrameInfo *MCStreamer::getCurrentDwarfFrameInfo() {
291   if (!hasUnfinishedDwarfFrameInfo()) {
292     getContext().reportError(getStartTokLoc(),
293                              "this directive must appear between "
294                              ".cfi_startproc and .cfi_endproc directives");
295     return nullptr;
296   }
297   return &DwarfFrameInfos[FrameInfoStack.back().first];
298 }
299 
300 bool MCStreamer::emitCVFileDirective(unsigned FileNo, StringRef Filename,
301                                      ArrayRef<uint8_t> Checksum,
302                                      unsigned ChecksumKind) {
303   return getContext().getCVContext().addFile(*this, FileNo, Filename, Checksum,
304                                              ChecksumKind);
305 }
306 
307 bool MCStreamer::emitCVFuncIdDirective(unsigned FunctionId) {
308   return getContext().getCVContext().recordFunctionId(FunctionId);
309 }
310 
311 bool MCStreamer::emitCVInlineSiteIdDirective(unsigned FunctionId,
312                                              unsigned IAFunc, unsigned IAFile,
313                                              unsigned IALine, unsigned IACol,
314                                              SMLoc Loc) {
315   if (getContext().getCVContext().getCVFunctionInfo(IAFunc) == nullptr) {
316     getContext().reportError(Loc, "parent function id not introduced by "
317                                   ".cv_func_id or .cv_inline_site_id");
318     return true;
319   }
320 
321   return getContext().getCVContext().recordInlinedCallSiteId(
322       FunctionId, IAFunc, IAFile, IALine, IACol);
323 }
324 
325 void MCStreamer::emitCVLocDirective(unsigned FunctionId, unsigned FileNo,
326                                     unsigned Line, unsigned Column,
327                                     bool PrologueEnd, bool IsStmt,
328                                     StringRef FileName, SMLoc Loc) {}
329 
330 bool MCStreamer::checkCVLocSection(unsigned FuncId, unsigned FileNo,
331                                    SMLoc Loc) {
332   CodeViewContext &CVC = getContext().getCVContext();
333   MCCVFunctionInfo *FI = CVC.getCVFunctionInfo(FuncId);
334   if (!FI) {
335     getContext().reportError(
336         Loc, "function id not introduced by .cv_func_id or .cv_inline_site_id");
337     return false;
338   }
339 
340   // Track the section
341   if (FI->Section == nullptr)
342     FI->Section = getCurrentSectionOnly();
343   else if (FI->Section != getCurrentSectionOnly()) {
344     getContext().reportError(
345         Loc,
346         "all .cv_loc directives for a function must be in the same section");
347     return false;
348   }
349   return true;
350 }
351 
352 void MCStreamer::emitCVLinetableDirective(unsigned FunctionId,
353                                           const MCSymbol *Begin,
354                                           const MCSymbol *End) {}
355 
356 void MCStreamer::emitCVInlineLinetableDirective(unsigned PrimaryFunctionId,
357                                                 unsigned SourceFileId,
358                                                 unsigned SourceLineNum,
359                                                 const MCSymbol *FnStartSym,
360                                                 const MCSymbol *FnEndSym) {}
361 
362 /// Only call this on endian-specific types like ulittle16_t and little32_t, or
363 /// structs composed of them.
364 template <typename T>
365 static void copyBytesForDefRange(SmallString<20> &BytePrefix,
366                                  codeview::SymbolKind SymKind,
367                                  const T &DefRangeHeader) {
368   BytePrefix.resize(2 + sizeof(T));
369   codeview::ulittle16_t SymKindLE = codeview::ulittle16_t(SymKind);
370   memcpy(&BytePrefix[0], &SymKindLE, 2);
371   memcpy(&BytePrefix[2], &DefRangeHeader, sizeof(T));
372 }
373 
374 void MCStreamer::emitCVDefRangeDirective(
375     ArrayRef<std::pair<const MCSymbol *, const MCSymbol *>> Ranges,
376     StringRef FixedSizePortion) {}
377 
378 void MCStreamer::emitCVDefRangeDirective(
379     ArrayRef<std::pair<const MCSymbol *, const MCSymbol *>> Ranges,
380     codeview::DefRangeRegisterRelHeader DRHdr) {
381   SmallString<20> BytePrefix;
382   copyBytesForDefRange(BytePrefix, codeview::S_DEFRANGE_REGISTER_REL, DRHdr);
383   emitCVDefRangeDirective(Ranges, BytePrefix);
384 }
385 
386 void MCStreamer::emitCVDefRangeDirective(
387     ArrayRef<std::pair<const MCSymbol *, const MCSymbol *>> Ranges,
388     codeview::DefRangeSubfieldRegisterHeader DRHdr) {
389   SmallString<20> BytePrefix;
390   copyBytesForDefRange(BytePrefix, codeview::S_DEFRANGE_SUBFIELD_REGISTER,
391                        DRHdr);
392   emitCVDefRangeDirective(Ranges, BytePrefix);
393 }
394 
395 void MCStreamer::emitCVDefRangeDirective(
396     ArrayRef<std::pair<const MCSymbol *, const MCSymbol *>> Ranges,
397     codeview::DefRangeRegisterHeader DRHdr) {
398   SmallString<20> BytePrefix;
399   copyBytesForDefRange(BytePrefix, codeview::S_DEFRANGE_REGISTER, DRHdr);
400   emitCVDefRangeDirective(Ranges, BytePrefix);
401 }
402 
403 void MCStreamer::emitCVDefRangeDirective(
404     ArrayRef<std::pair<const MCSymbol *, const MCSymbol *>> Ranges,
405     codeview::DefRangeFramePointerRelHeader DRHdr) {
406   SmallString<20> BytePrefix;
407   copyBytesForDefRange(BytePrefix, codeview::S_DEFRANGE_FRAMEPOINTER_REL,
408                        DRHdr);
409   emitCVDefRangeDirective(Ranges, BytePrefix);
410 }
411 
412 void MCStreamer::emitEHSymAttributes(const MCSymbol *Symbol,
413                                      MCSymbol *EHSymbol) {
414 }
415 
416 void MCStreamer::initSections(bool NoExecStack, const MCSubtargetInfo &STI) {
417   switchSectionNoPrint(getContext().getObjectFileInfo()->getTextSection());
418 }
419 
420 void MCStreamer::emitLabel(MCSymbol *Symbol, SMLoc Loc) {
421   Symbol->redefineIfPossible();
422 
423   if (!Symbol->isUndefined() || Symbol->isVariable())
424     return getContext().reportError(Loc, "symbol '" + Twine(Symbol->getName()) +
425                                              "' is already defined");
426 
427   assert(!Symbol->isVariable() && "Cannot emit a variable symbol!");
428   assert(getCurrentSectionOnly() && "Cannot emit before setting section!");
429   assert(!Symbol->getFragment() && "Unexpected fragment on symbol data!");
430   assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
431 
432   Symbol->setFragment(&getCurrentSectionOnly()->getDummyFragment());
433 
434   MCTargetStreamer *TS = getTargetStreamer();
435   if (TS)
436     TS->emitLabel(Symbol);
437 }
438 
439 void MCStreamer::emitConditionalAssignment(MCSymbol *Symbol,
440                                            const MCExpr *Value) {}
441 
442 void MCStreamer::emitCFISections(bool EH, bool Debug) {}
443 
444 void MCStreamer::emitCFIStartProc(bool IsSimple, SMLoc Loc) {
445   if (!FrameInfoStack.empty() &&
446       getCurrentSectionOnly() == FrameInfoStack.back().second)
447     return getContext().reportError(
448         Loc, "starting new .cfi frame before finishing the previous one");
449 
450   MCDwarfFrameInfo Frame;
451   Frame.IsSimple = IsSimple;
452   emitCFIStartProcImpl(Frame);
453 
454   const MCAsmInfo* MAI = Context.getAsmInfo();
455   if (MAI) {
456     for (const MCCFIInstruction& Inst : MAI->getInitialFrameState()) {
457       if (Inst.getOperation() == MCCFIInstruction::OpDefCfa ||
458           Inst.getOperation() == MCCFIInstruction::OpDefCfaRegister ||
459           Inst.getOperation() == MCCFIInstruction::OpLLVMDefAspaceCfa) {
460         Frame.CurrentCfaRegister = Inst.getRegister();
461       }
462     }
463   }
464 
465   FrameInfoStack.emplace_back(DwarfFrameInfos.size(), getCurrentSectionOnly());
466   DwarfFrameInfos.push_back(std::move(Frame));
467 }
468 
469 void MCStreamer::emitCFIStartProcImpl(MCDwarfFrameInfo &Frame) {
470 }
471 
472 void MCStreamer::emitCFIEndProc() {
473   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
474   if (!CurFrame)
475     return;
476   emitCFIEndProcImpl(*CurFrame);
477   FrameInfoStack.pop_back();
478 }
479 
480 void MCStreamer::emitCFIEndProcImpl(MCDwarfFrameInfo &Frame) {
481   // Put a dummy non-null value in Frame.End to mark that this frame has been
482   // closed.
483   Frame.End = (MCSymbol *)1;
484 }
485 
486 MCSymbol *MCStreamer::emitLineTableLabel() {
487   // Create a label and insert it into the line table and return this label
488   const MCDwarfLoc &DwarfLoc = getContext().getCurrentDwarfLoc();
489 
490   MCSymbol *LineStreamLabel = getContext().createTempSymbol();
491   MCDwarfLineEntry LabelLineEntry(nullptr, DwarfLoc, LineStreamLabel);
492   getContext()
493       .getMCDwarfLineTable(getContext().getDwarfCompileUnitID())
494       .getMCLineSections()
495       .addLineEntry(LabelLineEntry, getCurrentSectionOnly() /*Section*/);
496 
497   return LineStreamLabel;
498 }
499 
500 MCSymbol *MCStreamer::emitCFILabel() {
501   // Return a dummy non-null value so that label fields appear filled in when
502   // generating textual assembly.
503   return (MCSymbol *)1;
504 }
505 
506 void MCStreamer::emitCFIDefCfa(int64_t Register, int64_t Offset, SMLoc Loc) {
507   MCSymbol *Label = emitCFILabel();
508   MCCFIInstruction Instruction =
509       MCCFIInstruction::cfiDefCfa(Label, Register, Offset, Loc);
510   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
511   if (!CurFrame)
512     return;
513   CurFrame->Instructions.push_back(std::move(Instruction));
514   CurFrame->CurrentCfaRegister = static_cast<unsigned>(Register);
515 }
516 
517 void MCStreamer::emitCFIDefCfaOffset(int64_t Offset, SMLoc Loc) {
518   MCSymbol *Label = emitCFILabel();
519   MCCFIInstruction Instruction =
520       MCCFIInstruction::cfiDefCfaOffset(Label, Offset);
521   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
522   if (!CurFrame)
523     return;
524   CurFrame->Instructions.push_back(std::move(Instruction));
525 }
526 
527 void MCStreamer::emitCFIAdjustCfaOffset(int64_t Adjustment, SMLoc Loc) {
528   MCSymbol *Label = emitCFILabel();
529   MCCFIInstruction Instruction =
530       MCCFIInstruction::createAdjustCfaOffset(Label, Adjustment, Loc);
531   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
532   if (!CurFrame)
533     return;
534   CurFrame->Instructions.push_back(std::move(Instruction));
535 }
536 
537 void MCStreamer::emitCFIDefCfaRegister(int64_t Register, SMLoc Loc) {
538   MCSymbol *Label = emitCFILabel();
539   MCCFIInstruction Instruction =
540       MCCFIInstruction::createDefCfaRegister(Label, Register, Loc);
541   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
542   if (!CurFrame)
543     return;
544   CurFrame->Instructions.push_back(std::move(Instruction));
545   CurFrame->CurrentCfaRegister = static_cast<unsigned>(Register);
546 }
547 
548 void MCStreamer::emitCFILLVMDefAspaceCfa(int64_t Register, int64_t Offset,
549                                          int64_t AddressSpace, SMLoc Loc) {
550   MCSymbol *Label = emitCFILabel();
551   MCCFIInstruction Instruction = MCCFIInstruction::createLLVMDefAspaceCfa(
552       Label, Register, Offset, AddressSpace, Loc);
553   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
554   if (!CurFrame)
555     return;
556   CurFrame->Instructions.push_back(std::move(Instruction));
557   CurFrame->CurrentCfaRegister = static_cast<unsigned>(Register);
558 }
559 
560 void MCStreamer::emitCFIOffset(int64_t Register, int64_t Offset, SMLoc Loc) {
561   MCSymbol *Label = emitCFILabel();
562   MCCFIInstruction Instruction =
563       MCCFIInstruction::createOffset(Label, Register, Offset, Loc);
564   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
565   if (!CurFrame)
566     return;
567   CurFrame->Instructions.push_back(std::move(Instruction));
568 }
569 
570 void MCStreamer::emitCFIRelOffset(int64_t Register, int64_t Offset, SMLoc Loc) {
571   MCSymbol *Label = emitCFILabel();
572   MCCFIInstruction Instruction =
573       MCCFIInstruction::createRelOffset(Label, Register, Offset, Loc);
574   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
575   if (!CurFrame)
576     return;
577   CurFrame->Instructions.push_back(std::move(Instruction));
578 }
579 
580 void MCStreamer::emitCFIPersonality(const MCSymbol *Sym,
581                                     unsigned Encoding) {
582   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
583   if (!CurFrame)
584     return;
585   CurFrame->Personality = Sym;
586   CurFrame->PersonalityEncoding = Encoding;
587 }
588 
589 void MCStreamer::emitCFILsda(const MCSymbol *Sym, unsigned Encoding) {
590   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
591   if (!CurFrame)
592     return;
593   CurFrame->Lsda = Sym;
594   CurFrame->LsdaEncoding = Encoding;
595 }
596 
597 void MCStreamer::emitCFIRememberState(SMLoc Loc) {
598   MCSymbol *Label = emitCFILabel();
599   MCCFIInstruction Instruction =
600       MCCFIInstruction::createRememberState(Label, Loc);
601   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
602   if (!CurFrame)
603     return;
604   CurFrame->Instructions.push_back(std::move(Instruction));
605 }
606 
607 void MCStreamer::emitCFIRestoreState(SMLoc Loc) {
608   // FIXME: Error if there is no matching cfi_remember_state.
609   MCSymbol *Label = emitCFILabel();
610   MCCFIInstruction Instruction =
611       MCCFIInstruction::createRestoreState(Label, Loc);
612   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
613   if (!CurFrame)
614     return;
615   CurFrame->Instructions.push_back(std::move(Instruction));
616 }
617 
618 void MCStreamer::emitCFISameValue(int64_t Register, SMLoc Loc) {
619   MCSymbol *Label = emitCFILabel();
620   MCCFIInstruction Instruction =
621       MCCFIInstruction::createSameValue(Label, Register, Loc);
622   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
623   if (!CurFrame)
624     return;
625   CurFrame->Instructions.push_back(std::move(Instruction));
626 }
627 
628 void MCStreamer::emitCFIRestore(int64_t Register, SMLoc Loc) {
629   MCSymbol *Label = emitCFILabel();
630   MCCFIInstruction Instruction =
631       MCCFIInstruction::createRestore(Label, Register, Loc);
632   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
633   if (!CurFrame)
634     return;
635   CurFrame->Instructions.push_back(std::move(Instruction));
636 }
637 
638 void MCStreamer::emitCFIEscape(StringRef Values, SMLoc Loc) {
639   MCSymbol *Label = emitCFILabel();
640   MCCFIInstruction Instruction =
641       MCCFIInstruction::createEscape(Label, Values, Loc, "");
642   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
643   if (!CurFrame)
644     return;
645   CurFrame->Instructions.push_back(std::move(Instruction));
646 }
647 
648 void MCStreamer::emitCFIGnuArgsSize(int64_t Size, SMLoc Loc) {
649   MCSymbol *Label = emitCFILabel();
650   MCCFIInstruction Instruction =
651       MCCFIInstruction::createGnuArgsSize(Label, Size, Loc);
652   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
653   if (!CurFrame)
654     return;
655   CurFrame->Instructions.push_back(std::move(Instruction));
656 }
657 
658 void MCStreamer::emitCFISignalFrame() {
659   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
660   if (!CurFrame)
661     return;
662   CurFrame->IsSignalFrame = true;
663 }
664 
665 void MCStreamer::emitCFIUndefined(int64_t Register, SMLoc Loc) {
666   MCSymbol *Label = emitCFILabel();
667   MCCFIInstruction Instruction =
668       MCCFIInstruction::createUndefined(Label, Register, Loc);
669   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
670   if (!CurFrame)
671     return;
672   CurFrame->Instructions.push_back(std::move(Instruction));
673 }
674 
675 void MCStreamer::emitCFIRegister(int64_t Register1, int64_t Register2,
676                                  SMLoc Loc) {
677   MCSymbol *Label = emitCFILabel();
678   MCCFIInstruction Instruction =
679       MCCFIInstruction::createRegister(Label, Register1, Register2, Loc);
680   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
681   if (!CurFrame)
682     return;
683   CurFrame->Instructions.push_back(std::move(Instruction));
684 }
685 
686 void MCStreamer::emitCFIWindowSave(SMLoc Loc) {
687   MCSymbol *Label = emitCFILabel();
688   MCCFIInstruction Instruction = MCCFIInstruction::createWindowSave(Label, Loc);
689   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
690   if (!CurFrame)
691     return;
692   CurFrame->Instructions.push_back(std::move(Instruction));
693 }
694 
695 void MCStreamer::emitCFINegateRAState(SMLoc Loc) {
696   MCSymbol *Label = emitCFILabel();
697   MCCFIInstruction Instruction =
698       MCCFIInstruction::createNegateRAState(Label, Loc);
699   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
700   if (!CurFrame)
701     return;
702   CurFrame->Instructions.push_back(std::move(Instruction));
703 }
704 
705 void MCStreamer::emitCFINegateRAStateWithPC(SMLoc Loc) {
706   MCSymbol *Label = emitCFILabel();
707   MCCFIInstruction Instruction =
708       MCCFIInstruction::createNegateRAStateWithPC(Label, Loc);
709   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
710   if (!CurFrame)
711     return;
712   CurFrame->Instructions.push_back(std::move(Instruction));
713 }
714 
715 void MCStreamer::emitCFIReturnColumn(int64_t Register) {
716   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
717   if (!CurFrame)
718     return;
719   CurFrame->RAReg = Register;
720 }
721 
722 void MCStreamer::emitCFILabelDirective(SMLoc Loc, StringRef Name) {
723   MCSymbol *Label = emitCFILabel();
724   MCSymbol *Sym = getContext().getOrCreateSymbol(Name);
725   if (MCDwarfFrameInfo *F = getCurrentDwarfFrameInfo())
726     F->Instructions.push_back(MCCFIInstruction::createLabel(Label, Sym, Loc));
727 }
728 
729 void MCStreamer::emitCFIValOffset(int64_t Register, int64_t Offset, SMLoc Loc) {
730   MCSymbol *Label = emitCFILabel();
731   MCCFIInstruction Instruction =
732       MCCFIInstruction::createValOffset(Label, Register, Offset, Loc);
733   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
734   if (!CurFrame)
735     return;
736   CurFrame->Instructions.push_back(std::move(Instruction));
737 }
738 
739 WinEH::FrameInfo *MCStreamer::EnsureValidWinFrameInfo(SMLoc Loc) {
740   const MCAsmInfo *MAI = Context.getAsmInfo();
741   if (!MAI->usesWindowsCFI()) {
742     getContext().reportError(
743         Loc, ".seh_* directives are not supported on this target");
744     return nullptr;
745   }
746   if (!CurrentWinFrameInfo || CurrentWinFrameInfo->End) {
747     getContext().reportError(
748         Loc, ".seh_ directive must appear within an active frame");
749     return nullptr;
750   }
751   return CurrentWinFrameInfo;
752 }
753 
754 void MCStreamer::emitWinCFIStartProc(const MCSymbol *Symbol, SMLoc Loc) {
755   const MCAsmInfo *MAI = Context.getAsmInfo();
756   if (!MAI->usesWindowsCFI())
757     return getContext().reportError(
758         Loc, ".seh_* directives are not supported on this target");
759   if (CurrentWinFrameInfo && !CurrentWinFrameInfo->End)
760     getContext().reportError(
761         Loc, "Starting a function before ending the previous one!");
762 
763   MCSymbol *StartProc = emitCFILabel();
764 
765   CurrentProcWinFrameInfoStartIndex = WinFrameInfos.size();
766   WinFrameInfos.emplace_back(
767       std::make_unique<WinEH::FrameInfo>(Symbol, StartProc));
768   CurrentWinFrameInfo = WinFrameInfos.back().get();
769   CurrentWinFrameInfo->TextSection = getCurrentSectionOnly();
770 }
771 
772 void MCStreamer::emitWinCFIEndProc(SMLoc Loc) {
773   WinEH::FrameInfo *CurFrame = EnsureValidWinFrameInfo(Loc);
774   if (!CurFrame)
775     return;
776   if (CurFrame->ChainedParent)
777     getContext().reportError(Loc, "Not all chained regions terminated!");
778 
779   MCSymbol *Label = emitCFILabel();
780   CurFrame->End = Label;
781   if (!CurFrame->FuncletOrFuncEnd)
782     CurFrame->FuncletOrFuncEnd = CurFrame->End;
783 
784   for (size_t I = CurrentProcWinFrameInfoStartIndex, E = WinFrameInfos.size();
785        I != E; ++I)
786     emitWindowsUnwindTables(WinFrameInfos[I].get());
787   switchSection(CurFrame->TextSection);
788 }
789 
790 void MCStreamer::emitWinCFIFuncletOrFuncEnd(SMLoc Loc) {
791   WinEH::FrameInfo *CurFrame = EnsureValidWinFrameInfo(Loc);
792   if (!CurFrame)
793     return;
794   if (CurFrame->ChainedParent)
795     getContext().reportError(Loc, "Not all chained regions terminated!");
796 
797   MCSymbol *Label = emitCFILabel();
798   CurFrame->FuncletOrFuncEnd = Label;
799 }
800 
801 void MCStreamer::emitWinCFIStartChained(SMLoc Loc) {
802   WinEH::FrameInfo *CurFrame = EnsureValidWinFrameInfo(Loc);
803   if (!CurFrame)
804     return;
805 
806   MCSymbol *StartProc = emitCFILabel();
807 
808   WinFrameInfos.emplace_back(std::make_unique<WinEH::FrameInfo>(
809       CurFrame->Function, StartProc, CurFrame));
810   CurrentWinFrameInfo = WinFrameInfos.back().get();
811   CurrentWinFrameInfo->TextSection = getCurrentSectionOnly();
812 }
813 
814 void MCStreamer::emitWinCFIEndChained(SMLoc Loc) {
815   WinEH::FrameInfo *CurFrame = EnsureValidWinFrameInfo(Loc);
816   if (!CurFrame)
817     return;
818   if (!CurFrame->ChainedParent)
819     return getContext().reportError(
820         Loc, "End of a chained region outside a chained region!");
821 
822   MCSymbol *Label = emitCFILabel();
823 
824   CurFrame->End = Label;
825   CurrentWinFrameInfo = const_cast<WinEH::FrameInfo *>(CurFrame->ChainedParent);
826 }
827 
828 void MCStreamer::emitWinEHHandler(const MCSymbol *Sym, bool Unwind, bool Except,
829                                   SMLoc Loc) {
830   WinEH::FrameInfo *CurFrame = EnsureValidWinFrameInfo(Loc);
831   if (!CurFrame)
832     return;
833   if (CurFrame->ChainedParent)
834     return getContext().reportError(
835         Loc, "Chained unwind areas can't have handlers!");
836   CurFrame->ExceptionHandler = Sym;
837   if (!Except && !Unwind)
838     getContext().reportError(Loc, "Don't know what kind of handler this is!");
839   if (Unwind)
840     CurFrame->HandlesUnwind = true;
841   if (Except)
842     CurFrame->HandlesExceptions = true;
843 }
844 
845 void MCStreamer::emitWinEHHandlerData(SMLoc Loc) {
846   WinEH::FrameInfo *CurFrame = EnsureValidWinFrameInfo(Loc);
847   if (!CurFrame)
848     return;
849   if (CurFrame->ChainedParent)
850     getContext().reportError(Loc, "Chained unwind areas can't have handlers!");
851 }
852 
853 void MCStreamer::emitCGProfileEntry(const MCSymbolRefExpr *From,
854                                     const MCSymbolRefExpr *To, uint64_t Count) {
855 }
856 
857 static MCSection *getWinCFISection(MCContext &Context, unsigned *NextWinCFIID,
858                                    MCSection *MainCFISec,
859                                    const MCSection *TextSec) {
860   // If this is the main .text section, use the main unwind info section.
861   if (TextSec == Context.getObjectFileInfo()->getTextSection())
862     return MainCFISec;
863 
864   const auto *TextSecCOFF = cast<MCSectionCOFF>(TextSec);
865   auto *MainCFISecCOFF = cast<MCSectionCOFF>(MainCFISec);
866   unsigned UniqueID = TextSecCOFF->getOrAssignWinCFISectionID(NextWinCFIID);
867 
868   // If this section is COMDAT, this unwind section should be COMDAT associative
869   // with its group.
870   const MCSymbol *KeySym = nullptr;
871   if (TextSecCOFF->getCharacteristics() & COFF::IMAGE_SCN_LNK_COMDAT) {
872     KeySym = TextSecCOFF->getCOMDATSymbol();
873 
874     // In a GNU environment, we can't use associative comdats. Instead, do what
875     // GCC does, which is to make plain comdat selectany section named like
876     // ".[px]data$_Z3foov".
877     if (!Context.getAsmInfo()->hasCOFFAssociativeComdats()) {
878       std::string SectionName = (MainCFISecCOFF->getName() + "$" +
879                                  TextSecCOFF->getName().split('$').second)
880                                     .str();
881       return Context.getCOFFSection(SectionName,
882                                     MainCFISecCOFF->getCharacteristics() |
883                                         COFF::IMAGE_SCN_LNK_COMDAT,
884                                     "", COFF::IMAGE_COMDAT_SELECT_ANY);
885     }
886   }
887 
888   return Context.getAssociativeCOFFSection(MainCFISecCOFF, KeySym, UniqueID);
889 }
890 
891 MCSection *MCStreamer::getAssociatedPDataSection(const MCSection *TextSec) {
892   return getWinCFISection(getContext(), &NextWinCFIID,
893                           getContext().getObjectFileInfo()->getPDataSection(),
894                           TextSec);
895 }
896 
897 MCSection *MCStreamer::getAssociatedXDataSection(const MCSection *TextSec) {
898   return getWinCFISection(getContext(), &NextWinCFIID,
899                           getContext().getObjectFileInfo()->getXDataSection(),
900                           TextSec);
901 }
902 
903 void MCStreamer::emitSyntaxDirective() {}
904 
905 static unsigned encodeSEHRegNum(MCContext &Ctx, MCRegister Reg) {
906   return Ctx.getRegisterInfo()->getSEHRegNum(Reg);
907 }
908 
909 void MCStreamer::emitWinCFIPushReg(MCRegister Register, SMLoc Loc) {
910   WinEH::FrameInfo *CurFrame = EnsureValidWinFrameInfo(Loc);
911   if (!CurFrame)
912     return;
913 
914   MCSymbol *Label = emitCFILabel();
915 
916   WinEH::Instruction Inst = Win64EH::Instruction::PushNonVol(
917       Label, encodeSEHRegNum(Context, Register));
918   CurFrame->Instructions.push_back(Inst);
919 }
920 
921 void MCStreamer::emitWinCFISetFrame(MCRegister Register, unsigned Offset,
922                                     SMLoc Loc) {
923   WinEH::FrameInfo *CurFrame = EnsureValidWinFrameInfo(Loc);
924   if (!CurFrame)
925     return;
926   if (CurFrame->LastFrameInst >= 0)
927     return getContext().reportError(
928         Loc, "frame register and offset can be set at most once");
929   if (Offset & 0x0F)
930     return getContext().reportError(Loc, "offset is not a multiple of 16");
931   if (Offset > 240)
932     return getContext().reportError(
933         Loc, "frame offset must be less than or equal to 240");
934 
935   MCSymbol *Label = emitCFILabel();
936 
937   WinEH::Instruction Inst = Win64EH::Instruction::SetFPReg(
938       Label, encodeSEHRegNum(getContext(), Register), Offset);
939   CurFrame->LastFrameInst = CurFrame->Instructions.size();
940   CurFrame->Instructions.push_back(Inst);
941 }
942 
943 void MCStreamer::emitWinCFIAllocStack(unsigned Size, SMLoc Loc) {
944   WinEH::FrameInfo *CurFrame = EnsureValidWinFrameInfo(Loc);
945   if (!CurFrame)
946     return;
947   if (Size == 0)
948     return getContext().reportError(Loc,
949                                     "stack allocation size must be non-zero");
950   if (Size & 7)
951     return getContext().reportError(
952         Loc, "stack allocation size is not a multiple of 8");
953 
954   MCSymbol *Label = emitCFILabel();
955 
956   WinEH::Instruction Inst = Win64EH::Instruction::Alloc(Label, Size);
957   CurFrame->Instructions.push_back(Inst);
958 }
959 
960 void MCStreamer::emitWinCFISaveReg(MCRegister Register, unsigned Offset,
961                                    SMLoc Loc) {
962   WinEH::FrameInfo *CurFrame = EnsureValidWinFrameInfo(Loc);
963   if (!CurFrame)
964     return;
965 
966   if (Offset & 7)
967     return getContext().reportError(
968         Loc, "register save offset is not 8 byte aligned");
969 
970   MCSymbol *Label = emitCFILabel();
971 
972   WinEH::Instruction Inst = Win64EH::Instruction::SaveNonVol(
973       Label, encodeSEHRegNum(Context, Register), Offset);
974   CurFrame->Instructions.push_back(Inst);
975 }
976 
977 void MCStreamer::emitWinCFISaveXMM(MCRegister Register, unsigned Offset,
978                                    SMLoc Loc) {
979   WinEH::FrameInfo *CurFrame = EnsureValidWinFrameInfo(Loc);
980   if (!CurFrame)
981     return;
982   if (Offset & 0x0F)
983     return getContext().reportError(Loc, "offset is not a multiple of 16");
984 
985   MCSymbol *Label = emitCFILabel();
986 
987   WinEH::Instruction Inst = Win64EH::Instruction::SaveXMM(
988       Label, encodeSEHRegNum(Context, Register), Offset);
989   CurFrame->Instructions.push_back(Inst);
990 }
991 
992 void MCStreamer::emitWinCFIPushFrame(bool Code, SMLoc Loc) {
993   WinEH::FrameInfo *CurFrame = EnsureValidWinFrameInfo(Loc);
994   if (!CurFrame)
995     return;
996   if (!CurFrame->Instructions.empty())
997     return getContext().reportError(
998         Loc, "If present, PushMachFrame must be the first UOP");
999 
1000   MCSymbol *Label = emitCFILabel();
1001 
1002   WinEH::Instruction Inst = Win64EH::Instruction::PushMachFrame(Label, Code);
1003   CurFrame->Instructions.push_back(Inst);
1004 }
1005 
1006 void MCStreamer::emitWinCFIEndProlog(SMLoc Loc) {
1007   WinEH::FrameInfo *CurFrame = EnsureValidWinFrameInfo(Loc);
1008   if (!CurFrame)
1009     return;
1010 
1011   MCSymbol *Label = emitCFILabel();
1012 
1013   CurFrame->PrologEnd = Label;
1014 }
1015 
1016 void MCStreamer::emitCOFFSafeSEH(MCSymbol const *Symbol) {}
1017 
1018 void MCStreamer::emitCOFFSymbolIndex(MCSymbol const *Symbol) {}
1019 
1020 void MCStreamer::emitCOFFSectionIndex(MCSymbol const *Symbol) {}
1021 
1022 void MCStreamer::emitCOFFSecRel32(MCSymbol const *Symbol, uint64_t Offset) {}
1023 
1024 void MCStreamer::emitCOFFImgRel32(MCSymbol const *Symbol, int64_t Offset) {}
1025 
1026 void MCStreamer::emitCOFFSecNumber(MCSymbol const *Symbol) {}
1027 
1028 void MCStreamer::emitCOFFSecOffset(MCSymbol const *Symbol) {}
1029 
1030 /// EmitRawText - If this file is backed by an assembly streamer, this dumps
1031 /// the specified string in the output .s file.  This capability is
1032 /// indicated by the hasRawTextSupport() predicate.
1033 void MCStreamer::emitRawTextImpl(StringRef String) {
1034   // This is not llvm_unreachable for the sake of out of tree backend
1035   // developers who may not have assembly streamers and should serve as a
1036   // reminder to not accidentally call EmitRawText in the absence of such.
1037   report_fatal_error("EmitRawText called on an MCStreamer that doesn't support "
1038                      "it (target backend is likely missing an AsmStreamer "
1039                      "implementation)");
1040 }
1041 
1042 void MCStreamer::emitRawText(const Twine &T) {
1043   SmallString<128> Str;
1044   emitRawTextImpl(T.toStringRef(Str));
1045 }
1046 
1047 void MCStreamer::emitWindowsUnwindTables() {}
1048 
1049 void MCStreamer::emitWindowsUnwindTables(WinEH::FrameInfo *Frame) {}
1050 
1051 void MCStreamer::finish(SMLoc EndLoc) {
1052   if ((!DwarfFrameInfos.empty() && !DwarfFrameInfos.back().End) ||
1053       (!WinFrameInfos.empty() && !WinFrameInfos.back()->End)) {
1054     getContext().reportError(EndLoc, "Unfinished frame!");
1055     return;
1056   }
1057 
1058   MCTargetStreamer *TS = getTargetStreamer();
1059   if (TS)
1060     TS->finish();
1061 
1062   finishImpl();
1063 }
1064 
1065 void MCStreamer::maybeEmitDwarf64Mark() {
1066   if (Context.getDwarfFormat() != dwarf::DWARF64)
1067     return;
1068   AddComment("DWARF64 Mark");
1069   emitInt32(dwarf::DW_LENGTH_DWARF64);
1070 }
1071 
1072 void MCStreamer::emitDwarfUnitLength(uint64_t Length, const Twine &Comment) {
1073   assert(Context.getDwarfFormat() == dwarf::DWARF64 ||
1074          Length <= dwarf::DW_LENGTH_lo_reserved);
1075   maybeEmitDwarf64Mark();
1076   AddComment(Comment);
1077   emitIntValue(Length, dwarf::getDwarfOffsetByteSize(Context.getDwarfFormat()));
1078 }
1079 
1080 MCSymbol *MCStreamer::emitDwarfUnitLength(const Twine &Prefix,
1081                                           const Twine &Comment) {
1082   maybeEmitDwarf64Mark();
1083   AddComment(Comment);
1084   MCSymbol *Lo = Context.createTempSymbol(Prefix + "_start");
1085   MCSymbol *Hi = Context.createTempSymbol(Prefix + "_end");
1086 
1087   emitAbsoluteSymbolDiff(
1088       Hi, Lo, dwarf::getDwarfOffsetByteSize(Context.getDwarfFormat()));
1089   // emit the begin symbol after we generate the length field.
1090   emitLabel(Lo);
1091   // Return the Hi symbol to the caller.
1092   return Hi;
1093 }
1094 
1095 void MCStreamer::emitDwarfLineStartLabel(MCSymbol *StartSym) {
1096   // Set the value of the symbol, as we are at the start of the line table.
1097   emitLabel(StartSym);
1098 }
1099 
1100 void MCStreamer::emitAssignment(MCSymbol *Symbol, const MCExpr *Value) {
1101   visitUsedExpr(*Value);
1102   Symbol->setVariableValue(Value);
1103 
1104   MCTargetStreamer *TS = getTargetStreamer();
1105   if (TS)
1106     TS->emitAssignment(Symbol, Value);
1107 }
1108 
1109 void MCTargetStreamer::prettyPrintAsm(MCInstPrinter &InstPrinter,
1110                                       uint64_t Address, const MCInst &Inst,
1111                                       const MCSubtargetInfo &STI,
1112                                       raw_ostream &OS) {
1113   InstPrinter.printInst(&Inst, Address, "", STI, OS);
1114 }
1115 
1116 void MCStreamer::visitUsedSymbol(const MCSymbol &Sym) {
1117 }
1118 
1119 void MCStreamer::visitUsedExpr(const MCExpr &Expr) {
1120   switch (Expr.getKind()) {
1121   case MCExpr::Target:
1122     cast<MCTargetExpr>(Expr).visitUsedExpr(*this);
1123     break;
1124 
1125   case MCExpr::Constant:
1126     break;
1127 
1128   case MCExpr::Binary: {
1129     const MCBinaryExpr &BE = cast<MCBinaryExpr>(Expr);
1130     visitUsedExpr(*BE.getLHS());
1131     visitUsedExpr(*BE.getRHS());
1132     break;
1133   }
1134 
1135   case MCExpr::SymbolRef:
1136     visitUsedSymbol(cast<MCSymbolRefExpr>(Expr).getSymbol());
1137     break;
1138 
1139   case MCExpr::Unary:
1140     visitUsedExpr(*cast<MCUnaryExpr>(Expr).getSubExpr());
1141     break;
1142   }
1143 }
1144 
1145 void MCStreamer::emitInstruction(const MCInst &Inst, const MCSubtargetInfo &) {
1146   // Scan for values.
1147   for (unsigned i = Inst.getNumOperands(); i--;)
1148     if (Inst.getOperand(i).isExpr())
1149       visitUsedExpr(*Inst.getOperand(i).getExpr());
1150 }
1151 
1152 void MCStreamer::emitPseudoProbe(uint64_t Guid, uint64_t Index, uint64_t Type,
1153                                  uint64_t Attr, uint64_t Discriminator,
1154                                  const MCPseudoProbeInlineStack &InlineStack,
1155                                  MCSymbol *FnSym) {
1156   auto &Context = getContext();
1157 
1158   // Create a symbol at in the current section for use in the probe.
1159   MCSymbol *ProbeSym = Context.createTempSymbol();
1160 
1161   // Set the value of the symbol to use for the MCPseudoProbe.
1162   emitLabel(ProbeSym);
1163 
1164   // Create a (local) probe entry with the symbol.
1165   MCPseudoProbe Probe(ProbeSym, Guid, Index, Type, Attr, Discriminator);
1166 
1167   // Add the probe entry to this section's entries.
1168   Context.getMCPseudoProbeTable().getProbeSections().addPseudoProbe(
1169       FnSym, Probe, InlineStack);
1170 }
1171 
1172 void MCStreamer::emitAbsoluteSymbolDiff(const MCSymbol *Hi, const MCSymbol *Lo,
1173                                         unsigned Size) {
1174   // Get the Hi-Lo expression.
1175   const MCExpr *Diff =
1176       MCBinaryExpr::createSub(MCSymbolRefExpr::create(Hi, Context),
1177                               MCSymbolRefExpr::create(Lo, Context), Context);
1178 
1179   const MCAsmInfo *MAI = Context.getAsmInfo();
1180   if (!MAI->doesSetDirectiveSuppressReloc()) {
1181     emitValue(Diff, Size);
1182     return;
1183   }
1184 
1185   // Otherwise, emit with .set (aka assignment).
1186   MCSymbol *SetLabel = Context.createTempSymbol("set");
1187   emitAssignment(SetLabel, Diff);
1188   emitSymbolValue(SetLabel, Size);
1189 }
1190 
1191 void MCStreamer::emitAbsoluteSymbolDiffAsULEB128(const MCSymbol *Hi,
1192                                                  const MCSymbol *Lo) {
1193   // Get the Hi-Lo expression.
1194   const MCExpr *Diff =
1195       MCBinaryExpr::createSub(MCSymbolRefExpr::create(Hi, Context),
1196                               MCSymbolRefExpr::create(Lo, Context), Context);
1197 
1198   emitULEB128Value(Diff);
1199 }
1200 
1201 void MCStreamer::emitAssemblerFlag(MCAssemblerFlag Flag) {}
1202 void MCStreamer::emitThumbFunc(MCSymbol *Func) {}
1203 void MCStreamer::emitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {}
1204 void MCStreamer::beginCOFFSymbolDef(const MCSymbol *Symbol) {
1205   llvm_unreachable("this directive only supported on COFF targets");
1206 }
1207 void MCStreamer::endCOFFSymbolDef() {
1208   llvm_unreachable("this directive only supported on COFF targets");
1209 }
1210 void MCStreamer::emitFileDirective(StringRef Filename) {}
1211 void MCStreamer::emitFileDirective(StringRef Filename,
1212                                    StringRef CompilerVersion,
1213                                    StringRef TimeStamp, StringRef Description) {
1214 }
1215 void MCStreamer::emitCOFFSymbolStorageClass(int StorageClass) {
1216   llvm_unreachable("this directive only supported on COFF targets");
1217 }
1218 void MCStreamer::emitCOFFSymbolType(int Type) {
1219   llvm_unreachable("this directive only supported on COFF targets");
1220 }
1221 void MCStreamer::emitXCOFFLocalCommonSymbol(MCSymbol *LabelSym, uint64_t Size,
1222                                             MCSymbol *CsectSym,
1223                                             Align Alignment) {
1224   llvm_unreachable("this directive only supported on XCOFF targets");
1225 }
1226 
1227 void MCStreamer::emitXCOFFSymbolLinkageWithVisibility(MCSymbol *Symbol,
1228                                                       MCSymbolAttr Linkage,
1229                                                       MCSymbolAttr Visibility) {
1230   llvm_unreachable("emitXCOFFSymbolLinkageWithVisibility is only supported on "
1231                    "XCOFF targets");
1232 }
1233 
1234 void MCStreamer::emitXCOFFRenameDirective(const MCSymbol *Name,
1235                                           StringRef Rename) {}
1236 
1237 void MCStreamer::emitXCOFFRefDirective(const MCSymbol *Symbol) {
1238   llvm_unreachable("emitXCOFFRefDirective is only supported on XCOFF targets");
1239 }
1240 
1241 void MCStreamer::emitXCOFFExceptDirective(const MCSymbol *Symbol,
1242                                           const MCSymbol *Trap,
1243                                           unsigned Lang, unsigned Reason,
1244                                           unsigned FunctionSize,
1245                                           bool hasDebug) {
1246   report_fatal_error("emitXCOFFExceptDirective is only supported on "
1247                      "XCOFF targets");
1248 }
1249 
1250 void MCStreamer::emitXCOFFCInfoSym(StringRef Name, StringRef Metadata) {
1251   llvm_unreachable("emitXCOFFCInfoSym is only supported on"
1252                    "XCOFF targets");
1253 }
1254 
1255 void MCStreamer::emitELFSize(MCSymbol *Symbol, const MCExpr *Value) {}
1256 void MCStreamer::emitELFSymverDirective(const MCSymbol *OriginalSym,
1257                                         StringRef Name, bool KeepOriginalSym) {}
1258 void MCStreamer::emitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,
1259                                        Align ByteAlignment) {}
1260 void MCStreamer::emitTBSSSymbol(MCSection *Section, MCSymbol *Symbol,
1261                                 uint64_t Size, Align ByteAlignment) {}
1262 void MCStreamer::changeSection(MCSection *Section, uint32_t) {
1263   CurFrag = &Section->getDummyFragment();
1264 }
1265 void MCStreamer::emitWeakReference(MCSymbol *Alias, const MCSymbol *Symbol) {}
1266 void MCStreamer::emitBytes(StringRef Data) {}
1267 void MCStreamer::emitBinaryData(StringRef Data) { emitBytes(Data); }
1268 void MCStreamer::emitValueImpl(const MCExpr *Value, unsigned Size, SMLoc Loc) {
1269   visitUsedExpr(*Value);
1270 }
1271 void MCStreamer::emitULEB128Value(const MCExpr *Value) {}
1272 void MCStreamer::emitSLEB128Value(const MCExpr *Value) {}
1273 void MCStreamer::emitFill(const MCExpr &NumBytes, uint64_t Value, SMLoc Loc) {}
1274 void MCStreamer::emitFill(const MCExpr &NumValues, int64_t Size, int64_t Expr,
1275                           SMLoc Loc) {}
1276 void MCStreamer::emitValueToAlignment(Align Alignment, int64_t Value,
1277                                       unsigned ValueSize,
1278                                       unsigned MaxBytesToEmit) {}
1279 void MCStreamer::emitCodeAlignment(Align Alignment, const MCSubtargetInfo *STI,
1280                                    unsigned MaxBytesToEmit) {}
1281 void MCStreamer::emitValueToOffset(const MCExpr *Offset, unsigned char Value,
1282                                    SMLoc Loc) {}
1283 void MCStreamer::emitBundleAlignMode(Align Alignment) {}
1284 void MCStreamer::emitBundleLock(bool AlignToEnd) {}
1285 void MCStreamer::finishImpl() {}
1286 void MCStreamer::emitBundleUnlock() {}
1287 
1288 bool MCStreamer::popSection() {
1289   if (SectionStack.size() <= 1)
1290     return false;
1291   auto I = SectionStack.end();
1292   --I;
1293   MCSectionSubPair OldSec = I->first;
1294   --I;
1295   MCSectionSubPair NewSec = I->first;
1296 
1297   if (NewSec.first && OldSec != NewSec)
1298     changeSection(NewSec.first, NewSec.second);
1299   SectionStack.pop_back();
1300   return true;
1301 }
1302 
1303 void MCStreamer::switchSection(MCSection *Section, uint32_t Subsection) {
1304   assert(Section && "Cannot switch to a null section!");
1305   MCSectionSubPair curSection = SectionStack.back().first;
1306   SectionStack.back().second = curSection;
1307   if (MCSectionSubPair(Section, Subsection) != curSection) {
1308     changeSection(Section, Subsection);
1309     SectionStack.back().first = MCSectionSubPair(Section, Subsection);
1310     assert(!Section->hasEnded() && "Section already ended");
1311     MCSymbol *Sym = Section->getBeginSymbol();
1312     if (Sym && !Sym->isInSection())
1313       emitLabel(Sym);
1314   }
1315 }
1316 
1317 bool MCStreamer::switchSection(MCSection *Section, const MCExpr *SubsecExpr) {
1318   int64_t Subsec = 0;
1319   if (SubsecExpr) {
1320     if (!SubsecExpr->evaluateAsAbsolute(Subsec, getAssemblerPtr())) {
1321       getContext().reportError(SubsecExpr->getLoc(),
1322                                "cannot evaluate subsection number");
1323       return true;
1324     }
1325     if (!isUInt<31>(Subsec)) {
1326       getContext().reportError(SubsecExpr->getLoc(),
1327                                "subsection number " + Twine(Subsec) +
1328                                    " is not within [0,2147483647]");
1329       return true;
1330     }
1331   }
1332   switchSection(Section, Subsec);
1333   return false;
1334 }
1335 
1336 void MCStreamer::switchSectionNoPrint(MCSection *Section) {
1337   SectionStack.back().second = SectionStack.back().first;
1338   SectionStack.back().first = MCSectionSubPair(Section, 0);
1339   changeSection(Section, 0);
1340   MCSymbol *Sym = Section->getBeginSymbol();
1341   if (Sym && !Sym->isInSection())
1342     emitLabel(Sym);
1343 }
1344 
1345 MCSymbol *MCStreamer::endSection(MCSection *Section) {
1346   // TODO: keep track of the last subsection so that this symbol appears in the
1347   // correct place.
1348   MCSymbol *Sym = Section->getEndSymbol(Context);
1349   if (Sym->isInSection())
1350     return Sym;
1351 
1352   switchSection(Section);
1353   emitLabel(Sym);
1354   return Sym;
1355 }
1356 
1357 static VersionTuple
1358 targetVersionOrMinimumSupportedOSVersion(const Triple &Target,
1359                                          VersionTuple TargetVersion) {
1360   VersionTuple Min = Target.getMinimumSupportedOSVersion();
1361   return !Min.empty() && Min > TargetVersion ? Min : TargetVersion;
1362 }
1363 
1364 static MCVersionMinType
1365 getMachoVersionMinLoadCommandType(const Triple &Target) {
1366   assert(Target.isOSDarwin() && "expected a darwin OS");
1367   switch (Target.getOS()) {
1368   case Triple::MacOSX:
1369   case Triple::Darwin:
1370     return MCVM_OSXVersionMin;
1371   case Triple::IOS:
1372     assert(!Target.isMacCatalystEnvironment() &&
1373            "mac Catalyst should use LC_BUILD_VERSION");
1374     return MCVM_IOSVersionMin;
1375   case Triple::TvOS:
1376     return MCVM_TvOSVersionMin;
1377   case Triple::WatchOS:
1378     return MCVM_WatchOSVersionMin;
1379   default:
1380     break;
1381   }
1382   llvm_unreachable("unexpected OS type");
1383 }
1384 
1385 static VersionTuple getMachoBuildVersionSupportedOS(const Triple &Target) {
1386   assert(Target.isOSDarwin() && "expected a darwin OS");
1387   switch (Target.getOS()) {
1388   case Triple::MacOSX:
1389   case Triple::Darwin:
1390     return VersionTuple(10, 14);
1391   case Triple::IOS:
1392     // Mac Catalyst always uses the build version load command.
1393     if (Target.isMacCatalystEnvironment())
1394       return VersionTuple();
1395     [[fallthrough]];
1396   case Triple::TvOS:
1397     return VersionTuple(12);
1398   case Triple::WatchOS:
1399     return VersionTuple(5);
1400   case Triple::DriverKit:
1401     // DriverKit always uses the build version load command.
1402     return VersionTuple();
1403   case Triple::XROS:
1404     // XROS always uses the build version load command.
1405     return VersionTuple();
1406   default:
1407     break;
1408   }
1409   llvm_unreachable("unexpected OS type");
1410 }
1411 
1412 static MachO::PlatformType
1413 getMachoBuildVersionPlatformType(const Triple &Target) {
1414   assert(Target.isOSDarwin() && "expected a darwin OS");
1415   switch (Target.getOS()) {
1416   case Triple::MacOSX:
1417   case Triple::Darwin:
1418     return MachO::PLATFORM_MACOS;
1419   case Triple::IOS:
1420     if (Target.isMacCatalystEnvironment())
1421       return MachO::PLATFORM_MACCATALYST;
1422     return Target.isSimulatorEnvironment() ? MachO::PLATFORM_IOSSIMULATOR
1423                                            : MachO::PLATFORM_IOS;
1424   case Triple::TvOS:
1425     return Target.isSimulatorEnvironment() ? MachO::PLATFORM_TVOSSIMULATOR
1426                                            : MachO::PLATFORM_TVOS;
1427   case Triple::WatchOS:
1428     return Target.isSimulatorEnvironment() ? MachO::PLATFORM_WATCHOSSIMULATOR
1429                                            : MachO::PLATFORM_WATCHOS;
1430   case Triple::DriverKit:
1431     return MachO::PLATFORM_DRIVERKIT;
1432   case Triple::XROS:
1433     return Target.isSimulatorEnvironment() ? MachO::PLATFORM_XROS_SIMULATOR
1434                                            : MachO::PLATFORM_XROS;
1435   default:
1436     break;
1437   }
1438   llvm_unreachable("unexpected OS type");
1439 }
1440 
1441 void MCStreamer::emitVersionForTarget(
1442     const Triple &Target, const VersionTuple &SDKVersion,
1443     const Triple *DarwinTargetVariantTriple,
1444     const VersionTuple &DarwinTargetVariantSDKVersion) {
1445   if (!Target.isOSBinFormatMachO() || !Target.isOSDarwin())
1446     return;
1447   // Do we even know the version?
1448   if (Target.getOSMajorVersion() == 0)
1449     return;
1450 
1451   VersionTuple Version;
1452   switch (Target.getOS()) {
1453   case Triple::MacOSX:
1454   case Triple::Darwin:
1455     Target.getMacOSXVersion(Version);
1456     break;
1457   case Triple::IOS:
1458   case Triple::TvOS:
1459     Version = Target.getiOSVersion();
1460     break;
1461   case Triple::WatchOS:
1462     Version = Target.getWatchOSVersion();
1463     break;
1464   case Triple::DriverKit:
1465     Version = Target.getDriverKitVersion();
1466     break;
1467   case Triple::XROS:
1468     Version = Target.getOSVersion();
1469     break;
1470   default:
1471     llvm_unreachable("unexpected OS type");
1472   }
1473   assert(Version.getMajor() != 0 && "A non-zero major version is expected");
1474   auto LinkedTargetVersion =
1475       targetVersionOrMinimumSupportedOSVersion(Target, Version);
1476   auto BuildVersionOSVersion = getMachoBuildVersionSupportedOS(Target);
1477   bool ShouldEmitBuildVersion = false;
1478   if (BuildVersionOSVersion.empty() ||
1479       LinkedTargetVersion >= BuildVersionOSVersion) {
1480     if (Target.isMacCatalystEnvironment() && DarwinTargetVariantTriple &&
1481         DarwinTargetVariantTriple->isMacOSX()) {
1482       emitVersionForTarget(*DarwinTargetVariantTriple,
1483                            DarwinTargetVariantSDKVersion,
1484                            /*DarwinTargetVariantTriple=*/nullptr,
1485                            /*DarwinTargetVariantSDKVersion=*/VersionTuple());
1486       emitDarwinTargetVariantBuildVersion(
1487           getMachoBuildVersionPlatformType(Target),
1488           LinkedTargetVersion.getMajor(),
1489           LinkedTargetVersion.getMinor().value_or(0),
1490           LinkedTargetVersion.getSubminor().value_or(0), SDKVersion);
1491       return;
1492     }
1493     emitBuildVersion(getMachoBuildVersionPlatformType(Target),
1494                      LinkedTargetVersion.getMajor(),
1495                      LinkedTargetVersion.getMinor().value_or(0),
1496                      LinkedTargetVersion.getSubminor().value_or(0), SDKVersion);
1497     ShouldEmitBuildVersion = true;
1498   }
1499 
1500   if (const Triple *TVT = DarwinTargetVariantTriple) {
1501     if (Target.isMacOSX() && TVT->isMacCatalystEnvironment()) {
1502       auto TVLinkedTargetVersion =
1503           targetVersionOrMinimumSupportedOSVersion(*TVT, TVT->getiOSVersion());
1504       emitDarwinTargetVariantBuildVersion(
1505           getMachoBuildVersionPlatformType(*TVT),
1506           TVLinkedTargetVersion.getMajor(),
1507           TVLinkedTargetVersion.getMinor().value_or(0),
1508           TVLinkedTargetVersion.getSubminor().value_or(0),
1509           DarwinTargetVariantSDKVersion);
1510     }
1511   }
1512 
1513   if (ShouldEmitBuildVersion)
1514     return;
1515 
1516   emitVersionMin(getMachoVersionMinLoadCommandType(Target),
1517                  LinkedTargetVersion.getMajor(),
1518                  LinkedTargetVersion.getMinor().value_or(0),
1519                  LinkedTargetVersion.getSubminor().value_or(0), SDKVersion);
1520 }
1521