xref: /freebsd/contrib/llvm-project/llvm/lib/MC/MCStreamer.cpp (revision d4eeb02986980bf33dd56c41ceb9fc5f180c0d47) 
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/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 <utility>
42 
43 using namespace llvm;
44 
45 MCTargetStreamer::MCTargetStreamer(MCStreamer &S) : Streamer(S) {
46   S.setTargetStreamer(this);
47 }
48 
49 // Pin the vtables to this file.
50 MCTargetStreamer::~MCTargetStreamer() = default;
51 
52 void MCTargetStreamer::emitLabel(MCSymbol *Symbol) {}
53 
54 void MCTargetStreamer::finish() {}
55 
56 void MCTargetStreamer::emitConstantPools() {}
57 
58 void MCTargetStreamer::changeSection(const MCSection *CurSection,
59                                      MCSection *Section,
60                                      const MCExpr *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), UseAssemblerInfoForParsing(false) {
96   SectionStack.push_back(std::pair<MCSectionSubPair, MCSectionSubPair>());
97 }
98 
99 MCStreamer::~MCStreamer() {}
100 
101 void MCStreamer::reset() {
102   DwarfFrameInfos.clear();
103   CurrentWinFrameInfo = nullptr;
104   WinFrameInfos.clear();
105   SymbolOrdering.clear();
106   SectionStack.clear();
107   SectionStack.push_back(std::pair<MCSectionSubPair, MCSectionSubPair>());
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.Instructions) : 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 ? support::little : support::big);
140   unsigned Index = IsLittleEndian ? 0 : 8 - Size;
141   emitBytes(StringRef(reinterpret_cast<char *>(&Swapped) + Index, Size));
142 }
143 void MCStreamer::emitIntValue(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 void 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 }
167 
168 /// EmitSLEB128IntValue - Special case of EmitSLEB128Value that avoids the
169 /// client having to pass in a MCExpr for constant integers.
170 void MCStreamer::emitSLEB128IntValue(int64_t Value) {
171   SmallString<128> Tmp;
172   raw_svector_ostream OSE(Tmp);
173   encodeSLEB128(Value, OSE);
174   emitBytes(OSE.str());
175 }
176 
177 void MCStreamer::emitValue(const MCExpr *Value, unsigned Size, SMLoc Loc) {
178   emitValueImpl(Value, Size, Loc);
179 }
180 
181 void MCStreamer::emitSymbolValue(const MCSymbol *Sym, unsigned Size,
182                                  bool IsSectionRelative) {
183   assert((!IsSectionRelative || Size == 4) &&
184          "SectionRelative value requires 4-bytes");
185 
186   if (!IsSectionRelative)
187     emitValueImpl(MCSymbolRefExpr::create(Sym, getContext()), Size);
188   else
189     EmitCOFFSecRel32(Sym, /*Offset=*/0);
190 }
191 
192 void MCStreamer::emitDTPRel64Value(const MCExpr *Value) {
193   report_fatal_error("unsupported directive in streamer");
194 }
195 
196 void MCStreamer::emitDTPRel32Value(const MCExpr *Value) {
197   report_fatal_error("unsupported directive in streamer");
198 }
199 
200 void MCStreamer::emitTPRel64Value(const MCExpr *Value) {
201   report_fatal_error("unsupported directive in streamer");
202 }
203 
204 void MCStreamer::emitTPRel32Value(const MCExpr *Value) {
205   report_fatal_error("unsupported directive in streamer");
206 }
207 
208 void MCStreamer::emitGPRel64Value(const MCExpr *Value) {
209   report_fatal_error("unsupported directive in streamer");
210 }
211 
212 void MCStreamer::emitGPRel32Value(const MCExpr *Value) {
213   report_fatal_error("unsupported directive in streamer");
214 }
215 
216 /// Emit NumBytes bytes worth of the value specified by FillValue.
217 /// This implements directives such as '.space'.
218 void MCStreamer::emitFill(uint64_t NumBytes, uint8_t FillValue) {
219   emitFill(*MCConstantExpr::create(NumBytes, getContext()), FillValue);
220 }
221 
222 void llvm::MCStreamer::emitNops(int64_t NumBytes, int64_t ControlledNopLen,
223                                 llvm::SMLoc, const MCSubtargetInfo& STI) {}
224 
225 /// The implementation in this class just redirects to emitFill.
226 void MCStreamer::emitZeros(uint64_t NumBytes) { emitFill(NumBytes, 0); }
227 
228 Expected<unsigned>
229 MCStreamer::tryEmitDwarfFileDirective(unsigned FileNo, StringRef Directory,
230                                       StringRef Filename,
231                                       Optional<MD5::MD5Result> Checksum,
232                                       Optional<StringRef> Source,
233                                       unsigned CUID) {
234   return getContext().getDwarfFile(Directory, Filename, FileNo, Checksum,
235                                    Source, CUID);
236 }
237 
238 void MCStreamer::emitDwarfFile0Directive(StringRef Directory,
239                                          StringRef Filename,
240                                          Optional<MD5::MD5Result> Checksum,
241                                          Optional<StringRef> Source,
242                                          unsigned CUID) {
243   getContext().setMCLineTableRootFile(CUID, Directory, Filename, Checksum,
244                                       Source);
245 }
246 
247 void MCStreamer::emitCFIBKeyFrame() {
248   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
249   if (!CurFrame)
250     return;
251   CurFrame->IsBKeyFrame = true;
252 }
253 
254 void MCStreamer::emitDwarfLocDirective(unsigned FileNo, unsigned Line,
255                                        unsigned Column, unsigned Flags,
256                                        unsigned Isa, unsigned Discriminator,
257                                        StringRef FileName) {
258   getContext().setCurrentDwarfLoc(FileNo, Line, Column, Flags, Isa,
259                                   Discriminator);
260 }
261 
262 MCSymbol *MCStreamer::getDwarfLineTableSymbol(unsigned CUID) {
263   MCDwarfLineTable &Table = getContext().getMCDwarfLineTable(CUID);
264   if (!Table.getLabel()) {
265     StringRef Prefix = Context.getAsmInfo()->getPrivateGlobalPrefix();
266     Table.setLabel(
267         Context.getOrCreateSymbol(Prefix + "line_table_start" + Twine(CUID)));
268   }
269   return Table.getLabel();
270 }
271 
272 bool MCStreamer::hasUnfinishedDwarfFrameInfo() {
273   return !DwarfFrameInfos.empty() && !DwarfFrameInfos.back().End;
274 }
275 
276 MCDwarfFrameInfo *MCStreamer::getCurrentDwarfFrameInfo() {
277   if (!hasUnfinishedDwarfFrameInfo()) {
278     getContext().reportError(getStartTokLoc(),
279                              "this directive must appear between "
280                              ".cfi_startproc and .cfi_endproc directives");
281     return nullptr;
282   }
283   return &DwarfFrameInfos.back();
284 }
285 
286 bool MCStreamer::EmitCVFileDirective(unsigned FileNo, StringRef Filename,
287                                      ArrayRef<uint8_t> Checksum,
288                                      unsigned ChecksumKind) {
289   return getContext().getCVContext().addFile(*this, FileNo, Filename, Checksum,
290                                              ChecksumKind);
291 }
292 
293 bool MCStreamer::EmitCVFuncIdDirective(unsigned FunctionId) {
294   return getContext().getCVContext().recordFunctionId(FunctionId);
295 }
296 
297 bool MCStreamer::EmitCVInlineSiteIdDirective(unsigned FunctionId,
298                                              unsigned IAFunc, unsigned IAFile,
299                                              unsigned IALine, unsigned IACol,
300                                              SMLoc Loc) {
301   if (getContext().getCVContext().getCVFunctionInfo(IAFunc) == nullptr) {
302     getContext().reportError(Loc, "parent function id not introduced by "
303                                   ".cv_func_id or .cv_inline_site_id");
304     return true;
305   }
306 
307   return getContext().getCVContext().recordInlinedCallSiteId(
308       FunctionId, IAFunc, IAFile, IALine, IACol);
309 }
310 
311 void MCStreamer::emitCVLocDirective(unsigned FunctionId, unsigned FileNo,
312                                     unsigned Line, unsigned Column,
313                                     bool PrologueEnd, bool IsStmt,
314                                     StringRef FileName, SMLoc Loc) {}
315 
316 bool MCStreamer::checkCVLocSection(unsigned FuncId, unsigned FileNo,
317                                    SMLoc Loc) {
318   CodeViewContext &CVC = getContext().getCVContext();
319   MCCVFunctionInfo *FI = CVC.getCVFunctionInfo(FuncId);
320   if (!FI) {
321     getContext().reportError(
322         Loc, "function id not introduced by .cv_func_id or .cv_inline_site_id");
323     return false;
324   }
325 
326   // Track the section
327   if (FI->Section == nullptr)
328     FI->Section = getCurrentSectionOnly();
329   else if (FI->Section != getCurrentSectionOnly()) {
330     getContext().reportError(
331         Loc,
332         "all .cv_loc directives for a function must be in the same section");
333     return false;
334   }
335   return true;
336 }
337 
338 void MCStreamer::emitCVLinetableDirective(unsigned FunctionId,
339                                           const MCSymbol *Begin,
340                                           const MCSymbol *End) {}
341 
342 void MCStreamer::emitCVInlineLinetableDirective(unsigned PrimaryFunctionId,
343                                                 unsigned SourceFileId,
344                                                 unsigned SourceLineNum,
345                                                 const MCSymbol *FnStartSym,
346                                                 const MCSymbol *FnEndSym) {}
347 
348 /// Only call this on endian-specific types like ulittle16_t and little32_t, or
349 /// structs composed of them.
350 template <typename T>
351 static void copyBytesForDefRange(SmallString<20> &BytePrefix,
352                                  codeview::SymbolKind SymKind,
353                                  const T &DefRangeHeader) {
354   BytePrefix.resize(2 + sizeof(T));
355   codeview::ulittle16_t SymKindLE = codeview::ulittle16_t(SymKind);
356   memcpy(&BytePrefix[0], &SymKindLE, 2);
357   memcpy(&BytePrefix[2], &DefRangeHeader, sizeof(T));
358 }
359 
360 void MCStreamer::emitCVDefRangeDirective(
361     ArrayRef<std::pair<const MCSymbol *, const MCSymbol *>> Ranges,
362     StringRef FixedSizePortion) {}
363 
364 void MCStreamer::emitCVDefRangeDirective(
365     ArrayRef<std::pair<const MCSymbol *, const MCSymbol *>> Ranges,
366     codeview::DefRangeRegisterRelHeader DRHdr) {
367   SmallString<20> BytePrefix;
368   copyBytesForDefRange(BytePrefix, codeview::S_DEFRANGE_REGISTER_REL, DRHdr);
369   emitCVDefRangeDirective(Ranges, BytePrefix);
370 }
371 
372 void MCStreamer::emitCVDefRangeDirective(
373     ArrayRef<std::pair<const MCSymbol *, const MCSymbol *>> Ranges,
374     codeview::DefRangeSubfieldRegisterHeader DRHdr) {
375   SmallString<20> BytePrefix;
376   copyBytesForDefRange(BytePrefix, codeview::S_DEFRANGE_SUBFIELD_REGISTER,
377                        DRHdr);
378   emitCVDefRangeDirective(Ranges, BytePrefix);
379 }
380 
381 void MCStreamer::emitCVDefRangeDirective(
382     ArrayRef<std::pair<const MCSymbol *, const MCSymbol *>> Ranges,
383     codeview::DefRangeRegisterHeader DRHdr) {
384   SmallString<20> BytePrefix;
385   copyBytesForDefRange(BytePrefix, codeview::S_DEFRANGE_REGISTER, DRHdr);
386   emitCVDefRangeDirective(Ranges, BytePrefix);
387 }
388 
389 void MCStreamer::emitCVDefRangeDirective(
390     ArrayRef<std::pair<const MCSymbol *, const MCSymbol *>> Ranges,
391     codeview::DefRangeFramePointerRelHeader DRHdr) {
392   SmallString<20> BytePrefix;
393   copyBytesForDefRange(BytePrefix, codeview::S_DEFRANGE_FRAMEPOINTER_REL,
394                        DRHdr);
395   emitCVDefRangeDirective(Ranges, BytePrefix);
396 }
397 
398 void MCStreamer::emitEHSymAttributes(const MCSymbol *Symbol,
399                                      MCSymbol *EHSymbol) {
400 }
401 
402 void MCStreamer::initSections(bool NoExecStack, const MCSubtargetInfo &STI) {
403   SwitchSection(getContext().getObjectFileInfo()->getTextSection());
404 }
405 
406 void MCStreamer::AssignFragment(MCSymbol *Symbol, MCFragment *Fragment) {
407   assert(Fragment);
408   Symbol->setFragment(Fragment);
409 
410   // As we emit symbols into a section, track the order so that they can
411   // be sorted upon later. Zero is reserved to mean 'unemitted'.
412   SymbolOrdering[Symbol] = 1 + SymbolOrdering.size();
413 }
414 
415 void MCStreamer::emitLabel(MCSymbol *Symbol, SMLoc Loc) {
416   Symbol->redefineIfPossible();
417 
418   if (!Symbol->isUndefined() || Symbol->isVariable())
419     return getContext().reportError(Loc, "symbol '" + Twine(Symbol->getName()) +
420                                              "' is already defined");
421 
422   assert(!Symbol->isVariable() && "Cannot emit a variable symbol!");
423   assert(getCurrentSectionOnly() && "Cannot emit before setting section!");
424   assert(!Symbol->getFragment() && "Unexpected fragment on symbol data!");
425   assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
426 
427   Symbol->setFragment(&getCurrentSectionOnly()->getDummyFragment());
428 
429   MCTargetStreamer *TS = getTargetStreamer();
430   if (TS)
431     TS->emitLabel(Symbol);
432 }
433 
434 void MCStreamer::emitConditionalAssignment(MCSymbol *Symbol,
435                                            const MCExpr *Value) {}
436 
437 void MCStreamer::emitCFISections(bool EH, bool Debug) {}
438 
439 void MCStreamer::emitCFIStartProc(bool IsSimple, SMLoc Loc) {
440   if (hasUnfinishedDwarfFrameInfo())
441     return getContext().reportError(
442         Loc, "starting new .cfi frame before finishing the previous one");
443 
444   MCDwarfFrameInfo Frame;
445   Frame.IsSimple = IsSimple;
446   emitCFIStartProcImpl(Frame);
447 
448   const MCAsmInfo* MAI = Context.getAsmInfo();
449   if (MAI) {
450     for (const MCCFIInstruction& Inst : MAI->getInitialFrameState()) {
451       if (Inst.getOperation() == MCCFIInstruction::OpDefCfa ||
452           Inst.getOperation() == MCCFIInstruction::OpDefCfaRegister ||
453           Inst.getOperation() == MCCFIInstruction::OpLLVMDefAspaceCfa) {
454         Frame.CurrentCfaRegister = Inst.getRegister();
455       }
456     }
457   }
458 
459   DwarfFrameInfos.push_back(Frame);
460 }
461 
462 void MCStreamer::emitCFIStartProcImpl(MCDwarfFrameInfo &Frame) {
463 }
464 
465 void MCStreamer::emitCFIEndProc() {
466   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
467   if (!CurFrame)
468     return;
469   emitCFIEndProcImpl(*CurFrame);
470 }
471 
472 void MCStreamer::emitCFIEndProcImpl(MCDwarfFrameInfo &Frame) {
473   // Put a dummy non-null value in Frame.End to mark that this frame has been
474   // closed.
475   Frame.End = (MCSymbol *)1;
476 }
477 
478 MCSymbol *MCStreamer::emitCFILabel() {
479   // Return a dummy non-null value so that label fields appear filled in when
480   // generating textual assembly.
481   return (MCSymbol *)1;
482 }
483 
484 void MCStreamer::emitCFIDefCfa(int64_t Register, int64_t Offset) {
485   MCSymbol *Label = emitCFILabel();
486   MCCFIInstruction Instruction =
487       MCCFIInstruction::cfiDefCfa(Label, Register, Offset);
488   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
489   if (!CurFrame)
490     return;
491   CurFrame->Instructions.push_back(Instruction);
492   CurFrame->CurrentCfaRegister = static_cast<unsigned>(Register);
493 }
494 
495 void MCStreamer::emitCFIDefCfaOffset(int64_t Offset) {
496   MCSymbol *Label = emitCFILabel();
497   MCCFIInstruction Instruction =
498       MCCFIInstruction::cfiDefCfaOffset(Label, Offset);
499   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
500   if (!CurFrame)
501     return;
502   CurFrame->Instructions.push_back(Instruction);
503 }
504 
505 void MCStreamer::emitCFIAdjustCfaOffset(int64_t Adjustment) {
506   MCSymbol *Label = emitCFILabel();
507   MCCFIInstruction Instruction =
508     MCCFIInstruction::createAdjustCfaOffset(Label, Adjustment);
509   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
510   if (!CurFrame)
511     return;
512   CurFrame->Instructions.push_back(Instruction);
513 }
514 
515 void MCStreamer::emitCFIDefCfaRegister(int64_t Register) {
516   MCSymbol *Label = emitCFILabel();
517   MCCFIInstruction Instruction =
518     MCCFIInstruction::createDefCfaRegister(Label, Register);
519   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
520   if (!CurFrame)
521     return;
522   CurFrame->Instructions.push_back(Instruction);
523   CurFrame->CurrentCfaRegister = static_cast<unsigned>(Register);
524 }
525 
526 void MCStreamer::emitCFILLVMDefAspaceCfa(int64_t Register, int64_t Offset,
527                                          int64_t AddressSpace) {
528   MCSymbol *Label = emitCFILabel();
529   MCCFIInstruction Instruction = MCCFIInstruction::createLLVMDefAspaceCfa(
530       Label, Register, Offset, AddressSpace);
531   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
532   if (!CurFrame)
533     return;
534   CurFrame->Instructions.push_back(Instruction);
535   CurFrame->CurrentCfaRegister = static_cast<unsigned>(Register);
536 }
537 
538 void MCStreamer::emitCFIOffset(int64_t Register, int64_t Offset) {
539   MCSymbol *Label = emitCFILabel();
540   MCCFIInstruction Instruction =
541     MCCFIInstruction::createOffset(Label, Register, Offset);
542   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
543   if (!CurFrame)
544     return;
545   CurFrame->Instructions.push_back(Instruction);
546 }
547 
548 void MCStreamer::emitCFIRelOffset(int64_t Register, int64_t Offset) {
549   MCSymbol *Label = emitCFILabel();
550   MCCFIInstruction Instruction =
551     MCCFIInstruction::createRelOffset(Label, Register, Offset);
552   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
553   if (!CurFrame)
554     return;
555   CurFrame->Instructions.push_back(Instruction);
556 }
557 
558 void MCStreamer::emitCFIPersonality(const MCSymbol *Sym,
559                                     unsigned Encoding) {
560   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
561   if (!CurFrame)
562     return;
563   CurFrame->Personality = Sym;
564   CurFrame->PersonalityEncoding = Encoding;
565 }
566 
567 void MCStreamer::emitCFILsda(const MCSymbol *Sym, unsigned Encoding) {
568   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
569   if (!CurFrame)
570     return;
571   CurFrame->Lsda = Sym;
572   CurFrame->LsdaEncoding = Encoding;
573 }
574 
575 void MCStreamer::emitCFIRememberState() {
576   MCSymbol *Label = emitCFILabel();
577   MCCFIInstruction Instruction = MCCFIInstruction::createRememberState(Label);
578   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
579   if (!CurFrame)
580     return;
581   CurFrame->Instructions.push_back(Instruction);
582 }
583 
584 void MCStreamer::emitCFIRestoreState() {
585   // FIXME: Error if there is no matching cfi_remember_state.
586   MCSymbol *Label = emitCFILabel();
587   MCCFIInstruction Instruction = MCCFIInstruction::createRestoreState(Label);
588   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
589   if (!CurFrame)
590     return;
591   CurFrame->Instructions.push_back(Instruction);
592 }
593 
594 void MCStreamer::emitCFISameValue(int64_t Register) {
595   MCSymbol *Label = emitCFILabel();
596   MCCFIInstruction Instruction =
597     MCCFIInstruction::createSameValue(Label, Register);
598   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
599   if (!CurFrame)
600     return;
601   CurFrame->Instructions.push_back(Instruction);
602 }
603 
604 void MCStreamer::emitCFIRestore(int64_t Register) {
605   MCSymbol *Label = emitCFILabel();
606   MCCFIInstruction Instruction =
607     MCCFIInstruction::createRestore(Label, Register);
608   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
609   if (!CurFrame)
610     return;
611   CurFrame->Instructions.push_back(Instruction);
612 }
613 
614 void MCStreamer::emitCFIEscape(StringRef Values) {
615   MCSymbol *Label = emitCFILabel();
616   MCCFIInstruction Instruction = MCCFIInstruction::createEscape(Label, Values);
617   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
618   if (!CurFrame)
619     return;
620   CurFrame->Instructions.push_back(Instruction);
621 }
622 
623 void MCStreamer::emitCFIGnuArgsSize(int64_t Size) {
624   MCSymbol *Label = emitCFILabel();
625   MCCFIInstruction Instruction =
626     MCCFIInstruction::createGnuArgsSize(Label, Size);
627   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
628   if (!CurFrame)
629     return;
630   CurFrame->Instructions.push_back(Instruction);
631 }
632 
633 void MCStreamer::emitCFISignalFrame() {
634   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
635   if (!CurFrame)
636     return;
637   CurFrame->IsSignalFrame = true;
638 }
639 
640 void MCStreamer::emitCFIUndefined(int64_t Register) {
641   MCSymbol *Label = emitCFILabel();
642   MCCFIInstruction Instruction =
643     MCCFIInstruction::createUndefined(Label, Register);
644   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
645   if (!CurFrame)
646     return;
647   CurFrame->Instructions.push_back(Instruction);
648 }
649 
650 void MCStreamer::emitCFIRegister(int64_t Register1, int64_t Register2) {
651   MCSymbol *Label = emitCFILabel();
652   MCCFIInstruction Instruction =
653     MCCFIInstruction::createRegister(Label, Register1, Register2);
654   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
655   if (!CurFrame)
656     return;
657   CurFrame->Instructions.push_back(Instruction);
658 }
659 
660 void MCStreamer::emitCFIWindowSave() {
661   MCSymbol *Label = emitCFILabel();
662   MCCFIInstruction Instruction =
663     MCCFIInstruction::createWindowSave(Label);
664   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
665   if (!CurFrame)
666     return;
667   CurFrame->Instructions.push_back(Instruction);
668 }
669 
670 void MCStreamer::emitCFINegateRAState() {
671   MCSymbol *Label = emitCFILabel();
672   MCCFIInstruction Instruction = MCCFIInstruction::createNegateRAState(Label);
673   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
674   if (!CurFrame)
675     return;
676   CurFrame->Instructions.push_back(Instruction);
677 }
678 
679 void MCStreamer::emitCFIReturnColumn(int64_t Register) {
680   MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
681   if (!CurFrame)
682     return;
683   CurFrame->RAReg = Register;
684 }
685 
686 WinEH::FrameInfo *MCStreamer::EnsureValidWinFrameInfo(SMLoc Loc) {
687   const MCAsmInfo *MAI = Context.getAsmInfo();
688   if (!MAI->usesWindowsCFI()) {
689     getContext().reportError(
690         Loc, ".seh_* directives are not supported on this target");
691     return nullptr;
692   }
693   if (!CurrentWinFrameInfo || CurrentWinFrameInfo->End) {
694     getContext().reportError(
695         Loc, ".seh_ directive must appear within an active frame");
696     return nullptr;
697   }
698   return CurrentWinFrameInfo;
699 }
700 
701 void MCStreamer::EmitWinCFIStartProc(const MCSymbol *Symbol, SMLoc Loc) {
702   const MCAsmInfo *MAI = Context.getAsmInfo();
703   if (!MAI->usesWindowsCFI())
704     return getContext().reportError(
705         Loc, ".seh_* directives are not supported on this target");
706   if (CurrentWinFrameInfo && !CurrentWinFrameInfo->End)
707     getContext().reportError(
708         Loc, "Starting a function before ending the previous one!");
709 
710   MCSymbol *StartProc = emitCFILabel();
711 
712   CurrentProcWinFrameInfoStartIndex = WinFrameInfos.size();
713   WinFrameInfos.emplace_back(
714       std::make_unique<WinEH::FrameInfo>(Symbol, StartProc));
715   CurrentWinFrameInfo = WinFrameInfos.back().get();
716   CurrentWinFrameInfo->TextSection = getCurrentSectionOnly();
717 }
718 
719 void MCStreamer::EmitWinCFIEndProc(SMLoc Loc) {
720   WinEH::FrameInfo *CurFrame = EnsureValidWinFrameInfo(Loc);
721   if (!CurFrame)
722     return;
723   if (CurFrame->ChainedParent)
724     getContext().reportError(Loc, "Not all chained regions terminated!");
725 
726   MCSymbol *Label = emitCFILabel();
727   CurFrame->End = Label;
728   if (!CurFrame->FuncletOrFuncEnd)
729     CurFrame->FuncletOrFuncEnd = CurFrame->End;
730 
731   for (size_t I = CurrentProcWinFrameInfoStartIndex, E = WinFrameInfos.size();
732        I != E; ++I)
733     EmitWindowsUnwindTables(WinFrameInfos[I].get());
734   SwitchSection(CurFrame->TextSection);
735 }
736 
737 void MCStreamer::EmitWinCFIFuncletOrFuncEnd(SMLoc Loc) {
738   WinEH::FrameInfo *CurFrame = EnsureValidWinFrameInfo(Loc);
739   if (!CurFrame)
740     return;
741   if (CurFrame->ChainedParent)
742     getContext().reportError(Loc, "Not all chained regions terminated!");
743 
744   MCSymbol *Label = emitCFILabel();
745   CurFrame->FuncletOrFuncEnd = Label;
746 }
747 
748 void MCStreamer::EmitWinCFIStartChained(SMLoc Loc) {
749   WinEH::FrameInfo *CurFrame = EnsureValidWinFrameInfo(Loc);
750   if (!CurFrame)
751     return;
752 
753   MCSymbol *StartProc = emitCFILabel();
754 
755   WinFrameInfos.emplace_back(std::make_unique<WinEH::FrameInfo>(
756       CurFrame->Function, StartProc, CurFrame));
757   CurrentWinFrameInfo = WinFrameInfos.back().get();
758   CurrentWinFrameInfo->TextSection = getCurrentSectionOnly();
759 }
760 
761 void MCStreamer::EmitWinCFIEndChained(SMLoc Loc) {
762   WinEH::FrameInfo *CurFrame = EnsureValidWinFrameInfo(Loc);
763   if (!CurFrame)
764     return;
765   if (!CurFrame->ChainedParent)
766     return getContext().reportError(
767         Loc, "End of a chained region outside a chained region!");
768 
769   MCSymbol *Label = emitCFILabel();
770 
771   CurFrame->End = Label;
772   CurrentWinFrameInfo = const_cast<WinEH::FrameInfo *>(CurFrame->ChainedParent);
773 }
774 
775 void MCStreamer::EmitWinEHHandler(const MCSymbol *Sym, bool Unwind, bool Except,
776                                   SMLoc Loc) {
777   WinEH::FrameInfo *CurFrame = EnsureValidWinFrameInfo(Loc);
778   if (!CurFrame)
779     return;
780   if (CurFrame->ChainedParent)
781     return getContext().reportError(
782         Loc, "Chained unwind areas can't have handlers!");
783   CurFrame->ExceptionHandler = Sym;
784   if (!Except && !Unwind)
785     getContext().reportError(Loc, "Don't know what kind of handler this is!");
786   if (Unwind)
787     CurFrame->HandlesUnwind = true;
788   if (Except)
789     CurFrame->HandlesExceptions = true;
790 }
791 
792 void MCStreamer::EmitWinEHHandlerData(SMLoc Loc) {
793   WinEH::FrameInfo *CurFrame = EnsureValidWinFrameInfo(Loc);
794   if (!CurFrame)
795     return;
796   if (CurFrame->ChainedParent)
797     getContext().reportError(Loc, "Chained unwind areas can't have handlers!");
798 }
799 
800 void MCStreamer::emitCGProfileEntry(const MCSymbolRefExpr *From,
801                                     const MCSymbolRefExpr *To, uint64_t Count) {
802 }
803 
804 static MCSection *getWinCFISection(MCContext &Context, unsigned *NextWinCFIID,
805                                    MCSection *MainCFISec,
806                                    const MCSection *TextSec) {
807   // If this is the main .text section, use the main unwind info section.
808   if (TextSec == Context.getObjectFileInfo()->getTextSection())
809     return MainCFISec;
810 
811   const auto *TextSecCOFF = cast<MCSectionCOFF>(TextSec);
812   auto *MainCFISecCOFF = cast<MCSectionCOFF>(MainCFISec);
813   unsigned UniqueID = TextSecCOFF->getOrAssignWinCFISectionID(NextWinCFIID);
814 
815   // If this section is COMDAT, this unwind section should be COMDAT associative
816   // with its group.
817   const MCSymbol *KeySym = nullptr;
818   if (TextSecCOFF->getCharacteristics() & COFF::IMAGE_SCN_LNK_COMDAT) {
819     KeySym = TextSecCOFF->getCOMDATSymbol();
820 
821     // In a GNU environment, we can't use associative comdats. Instead, do what
822     // GCC does, which is to make plain comdat selectany section named like
823     // ".[px]data$_Z3foov".
824     if (!Context.getAsmInfo()->hasCOFFAssociativeComdats()) {
825       std::string SectionName = (MainCFISecCOFF->getName() + "$" +
826                                  TextSecCOFF->getName().split('$').second)
827                                     .str();
828       return Context.getCOFFSection(
829           SectionName,
830           MainCFISecCOFF->getCharacteristics() | COFF::IMAGE_SCN_LNK_COMDAT,
831           MainCFISecCOFF->getKind(), "", COFF::IMAGE_COMDAT_SELECT_ANY);
832     }
833   }
834 
835   return Context.getAssociativeCOFFSection(MainCFISecCOFF, KeySym, UniqueID);
836 }
837 
838 MCSection *MCStreamer::getAssociatedPDataSection(const MCSection *TextSec) {
839   return getWinCFISection(getContext(), &NextWinCFIID,
840                           getContext().getObjectFileInfo()->getPDataSection(),
841                           TextSec);
842 }
843 
844 MCSection *MCStreamer::getAssociatedXDataSection(const MCSection *TextSec) {
845   return getWinCFISection(getContext(), &NextWinCFIID,
846                           getContext().getObjectFileInfo()->getXDataSection(),
847                           TextSec);
848 }
849 
850 void MCStreamer::emitSyntaxDirective() {}
851 
852 static unsigned encodeSEHRegNum(MCContext &Ctx, MCRegister Reg) {
853   return Ctx.getRegisterInfo()->getSEHRegNum(Reg);
854 }
855 
856 void MCStreamer::EmitWinCFIPushReg(MCRegister Register, SMLoc Loc) {
857   WinEH::FrameInfo *CurFrame = EnsureValidWinFrameInfo(Loc);
858   if (!CurFrame)
859     return;
860 
861   MCSymbol *Label = emitCFILabel();
862 
863   WinEH::Instruction Inst = Win64EH::Instruction::PushNonVol(
864       Label, encodeSEHRegNum(Context, Register));
865   CurFrame->Instructions.push_back(Inst);
866 }
867 
868 void MCStreamer::EmitWinCFISetFrame(MCRegister Register, unsigned Offset,
869                                     SMLoc Loc) {
870   WinEH::FrameInfo *CurFrame = EnsureValidWinFrameInfo(Loc);
871   if (!CurFrame)
872     return;
873   if (CurFrame->LastFrameInst >= 0)
874     return getContext().reportError(
875         Loc, "frame register and offset can be set at most once");
876   if (Offset & 0x0F)
877     return getContext().reportError(Loc, "offset is not a multiple of 16");
878   if (Offset > 240)
879     return getContext().reportError(
880         Loc, "frame offset must be less than or equal to 240");
881 
882   MCSymbol *Label = emitCFILabel();
883 
884   WinEH::Instruction Inst = Win64EH::Instruction::SetFPReg(
885       Label, encodeSEHRegNum(getContext(), Register), Offset);
886   CurFrame->LastFrameInst = CurFrame->Instructions.size();
887   CurFrame->Instructions.push_back(Inst);
888 }
889 
890 void MCStreamer::EmitWinCFIAllocStack(unsigned Size, SMLoc Loc) {
891   WinEH::FrameInfo *CurFrame = EnsureValidWinFrameInfo(Loc);
892   if (!CurFrame)
893     return;
894   if (Size == 0)
895     return getContext().reportError(Loc,
896                                     "stack allocation size must be non-zero");
897   if (Size & 7)
898     return getContext().reportError(
899         Loc, "stack allocation size is not a multiple of 8");
900 
901   MCSymbol *Label = emitCFILabel();
902 
903   WinEH::Instruction Inst = Win64EH::Instruction::Alloc(Label, Size);
904   CurFrame->Instructions.push_back(Inst);
905 }
906 
907 void MCStreamer::EmitWinCFISaveReg(MCRegister Register, unsigned Offset,
908                                    SMLoc Loc) {
909   WinEH::FrameInfo *CurFrame = EnsureValidWinFrameInfo(Loc);
910   if (!CurFrame)
911     return;
912 
913   if (Offset & 7)
914     return getContext().reportError(
915         Loc, "register save offset is not 8 byte aligned");
916 
917   MCSymbol *Label = emitCFILabel();
918 
919   WinEH::Instruction Inst = Win64EH::Instruction::SaveNonVol(
920       Label, encodeSEHRegNum(Context, Register), Offset);
921   CurFrame->Instructions.push_back(Inst);
922 }
923 
924 void MCStreamer::EmitWinCFISaveXMM(MCRegister Register, unsigned Offset,
925                                    SMLoc Loc) {
926   WinEH::FrameInfo *CurFrame = EnsureValidWinFrameInfo(Loc);
927   if (!CurFrame)
928     return;
929   if (Offset & 0x0F)
930     return getContext().reportError(Loc, "offset is not a multiple of 16");
931 
932   MCSymbol *Label = emitCFILabel();
933 
934   WinEH::Instruction Inst = Win64EH::Instruction::SaveXMM(
935       Label, encodeSEHRegNum(Context, Register), Offset);
936   CurFrame->Instructions.push_back(Inst);
937 }
938 
939 void MCStreamer::EmitWinCFIPushFrame(bool Code, SMLoc Loc) {
940   WinEH::FrameInfo *CurFrame = EnsureValidWinFrameInfo(Loc);
941   if (!CurFrame)
942     return;
943   if (!CurFrame->Instructions.empty())
944     return getContext().reportError(
945         Loc, "If present, PushMachFrame must be the first UOP");
946 
947   MCSymbol *Label = emitCFILabel();
948 
949   WinEH::Instruction Inst = Win64EH::Instruction::PushMachFrame(Label, Code);
950   CurFrame->Instructions.push_back(Inst);
951 }
952 
953 void MCStreamer::EmitWinCFIEndProlog(SMLoc Loc) {
954   WinEH::FrameInfo *CurFrame = EnsureValidWinFrameInfo(Loc);
955   if (!CurFrame)
956     return;
957 
958   MCSymbol *Label = emitCFILabel();
959 
960   CurFrame->PrologEnd = Label;
961 }
962 
963 void MCStreamer::EmitCOFFSafeSEH(MCSymbol const *Symbol) {}
964 
965 void MCStreamer::EmitCOFFSymbolIndex(MCSymbol const *Symbol) {}
966 
967 void MCStreamer::EmitCOFFSectionIndex(MCSymbol const *Symbol) {}
968 
969 void MCStreamer::EmitCOFFSecRel32(MCSymbol const *Symbol, uint64_t Offset) {}
970 
971 void MCStreamer::EmitCOFFImgRel32(MCSymbol const *Symbol, int64_t Offset) {}
972 
973 /// EmitRawText - If this file is backed by an assembly streamer, this dumps
974 /// the specified string in the output .s file.  This capability is
975 /// indicated by the hasRawTextSupport() predicate.
976 void MCStreamer::emitRawTextImpl(StringRef String) {
977   // This is not llvm_unreachable for the sake of out of tree backend
978   // developers who may not have assembly streamers and should serve as a
979   // reminder to not accidentally call EmitRawText in the absence of such.
980   report_fatal_error("EmitRawText called on an MCStreamer that doesn't support "
981                      "it (target backend is likely missing an AsmStreamer "
982                      "implementation)");
983 }
984 
985 void MCStreamer::emitRawText(const Twine &T) {
986   SmallString<128> Str;
987   emitRawTextImpl(T.toStringRef(Str));
988 }
989 
990 void MCStreamer::EmitWindowsUnwindTables() {
991 }
992 
993 void MCStreamer::EmitWindowsUnwindTables(WinEH::FrameInfo *Frame) {
994 }
995 
996 void MCStreamer::Finish(SMLoc EndLoc) {
997   if ((!DwarfFrameInfos.empty() && !DwarfFrameInfos.back().End) ||
998       (!WinFrameInfos.empty() && !WinFrameInfos.back()->End)) {
999     getContext().reportError(EndLoc, "Unfinished frame!");
1000     return;
1001   }
1002 
1003   MCTargetStreamer *TS = getTargetStreamer();
1004   if (TS)
1005     TS->finish();
1006 
1007   finishImpl();
1008 }
1009 
1010 void MCStreamer::maybeEmitDwarf64Mark() {
1011   if (Context.getDwarfFormat() != dwarf::DWARF64)
1012     return;
1013   AddComment("DWARF64 Mark");
1014   emitInt32(dwarf::DW_LENGTH_DWARF64);
1015 }
1016 
1017 void MCStreamer::emitDwarfUnitLength(uint64_t Length, const Twine &Comment) {
1018   assert(Context.getDwarfFormat() == dwarf::DWARF64 ||
1019          Length <= dwarf::DW_LENGTH_lo_reserved);
1020   maybeEmitDwarf64Mark();
1021   AddComment(Comment);
1022   emitIntValue(Length, dwarf::getDwarfOffsetByteSize(Context.getDwarfFormat()));
1023 }
1024 
1025 MCSymbol *MCStreamer::emitDwarfUnitLength(const Twine &Prefix,
1026                                           const Twine &Comment) {
1027   maybeEmitDwarf64Mark();
1028   AddComment(Comment);
1029   MCSymbol *Lo = Context.createTempSymbol(Prefix + "_start");
1030   MCSymbol *Hi = Context.createTempSymbol(Prefix + "_end");
1031 
1032   emitAbsoluteSymbolDiff(
1033       Hi, Lo, dwarf::getDwarfOffsetByteSize(Context.getDwarfFormat()));
1034   // emit the begin symbol after we generate the length field.
1035   emitLabel(Lo);
1036   // Return the Hi symbol to the caller.
1037   return Hi;
1038 }
1039 
1040 void MCStreamer::emitDwarfLineStartLabel(MCSymbol *StartSym) {
1041   // Set the value of the symbol, as we are at the start of the line table.
1042   emitLabel(StartSym);
1043 }
1044 
1045 void MCStreamer::emitAssignment(MCSymbol *Symbol, const MCExpr *Value) {
1046   visitUsedExpr(*Value);
1047   Symbol->setVariableValue(Value);
1048 
1049   MCTargetStreamer *TS = getTargetStreamer();
1050   if (TS)
1051     TS->emitAssignment(Symbol, Value);
1052 }
1053 
1054 void MCTargetStreamer::prettyPrintAsm(MCInstPrinter &InstPrinter,
1055                                       uint64_t Address, const MCInst &Inst,
1056                                       const MCSubtargetInfo &STI,
1057                                       raw_ostream &OS) {
1058   InstPrinter.printInst(&Inst, Address, "", STI, OS);
1059 }
1060 
1061 void MCStreamer::visitUsedSymbol(const MCSymbol &Sym) {
1062 }
1063 
1064 void MCStreamer::visitUsedExpr(const MCExpr &Expr) {
1065   switch (Expr.getKind()) {
1066   case MCExpr::Target:
1067     cast<MCTargetExpr>(Expr).visitUsedExpr(*this);
1068     break;
1069 
1070   case MCExpr::Constant:
1071     break;
1072 
1073   case MCExpr::Binary: {
1074     const MCBinaryExpr &BE = cast<MCBinaryExpr>(Expr);
1075     visitUsedExpr(*BE.getLHS());
1076     visitUsedExpr(*BE.getRHS());
1077     break;
1078   }
1079 
1080   case MCExpr::SymbolRef:
1081     visitUsedSymbol(cast<MCSymbolRefExpr>(Expr).getSymbol());
1082     break;
1083 
1084   case MCExpr::Unary:
1085     visitUsedExpr(*cast<MCUnaryExpr>(Expr).getSubExpr());
1086     break;
1087   }
1088 }
1089 
1090 void MCStreamer::emitInstruction(const MCInst &Inst, const MCSubtargetInfo &) {
1091   // Scan for values.
1092   for (unsigned i = Inst.getNumOperands(); i--;)
1093     if (Inst.getOperand(i).isExpr())
1094       visitUsedExpr(*Inst.getOperand(i).getExpr());
1095 }
1096 
1097 void MCStreamer::emitPseudoProbe(uint64_t Guid, uint64_t Index, uint64_t Type,
1098                                  uint64_t Attr,
1099                                  const MCPseudoProbeInlineStack &InlineStack) {
1100   auto &Context = getContext();
1101 
1102   // Create a symbol at in the current section for use in the probe.
1103   MCSymbol *ProbeSym = Context.createTempSymbol();
1104 
1105   // Set the value of the symbol to use for the MCPseudoProbe.
1106   emitLabel(ProbeSym);
1107 
1108   // Create a (local) probe entry with the symbol.
1109   MCPseudoProbe Probe(ProbeSym, Guid, Index, Type, Attr);
1110 
1111   // Add the probe entry to this section's entries.
1112   Context.getMCPseudoProbeTable().getProbeSections().addPseudoProbe(
1113       getCurrentSectionOnly(), Probe, InlineStack);
1114 }
1115 
1116 void MCStreamer::emitAbsoluteSymbolDiff(const MCSymbol *Hi, const MCSymbol *Lo,
1117                                         unsigned Size) {
1118   // Get the Hi-Lo expression.
1119   const MCExpr *Diff =
1120       MCBinaryExpr::createSub(MCSymbolRefExpr::create(Hi, Context),
1121                               MCSymbolRefExpr::create(Lo, Context), Context);
1122 
1123   const MCAsmInfo *MAI = Context.getAsmInfo();
1124   if (!MAI->doesSetDirectiveSuppressReloc()) {
1125     emitValue(Diff, Size);
1126     return;
1127   }
1128 
1129   // Otherwise, emit with .set (aka assignment).
1130   MCSymbol *SetLabel = Context.createTempSymbol("set");
1131   emitAssignment(SetLabel, Diff);
1132   emitSymbolValue(SetLabel, Size);
1133 }
1134 
1135 void MCStreamer::emitAbsoluteSymbolDiffAsULEB128(const MCSymbol *Hi,
1136                                                  const MCSymbol *Lo) {
1137   // Get the Hi-Lo expression.
1138   const MCExpr *Diff =
1139       MCBinaryExpr::createSub(MCSymbolRefExpr::create(Hi, Context),
1140                               MCSymbolRefExpr::create(Lo, Context), Context);
1141 
1142   emitULEB128Value(Diff);
1143 }
1144 
1145 void MCStreamer::emitAssemblerFlag(MCAssemblerFlag Flag) {}
1146 void MCStreamer::emitThumbFunc(MCSymbol *Func) {}
1147 void MCStreamer::emitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {}
1148 void MCStreamer::BeginCOFFSymbolDef(const MCSymbol *Symbol) {
1149   llvm_unreachable("this directive only supported on COFF targets");
1150 }
1151 void MCStreamer::EndCOFFSymbolDef() {
1152   llvm_unreachable("this directive only supported on COFF targets");
1153 }
1154 void MCStreamer::emitFileDirective(StringRef Filename) {}
1155 void MCStreamer::emitFileDirective(StringRef Filename, StringRef CompilerVerion,
1156                                    StringRef TimeStamp, StringRef Description) {
1157 }
1158 void MCStreamer::EmitCOFFSymbolStorageClass(int StorageClass) {
1159   llvm_unreachable("this directive only supported on COFF targets");
1160 }
1161 void MCStreamer::EmitCOFFSymbolType(int Type) {
1162   llvm_unreachable("this directive only supported on COFF targets");
1163 }
1164 void MCStreamer::emitXCOFFLocalCommonSymbol(MCSymbol *LabelSym, uint64_t Size,
1165                                             MCSymbol *CsectSym,
1166                                             unsigned ByteAlign) {
1167   llvm_unreachable("this directive only supported on XCOFF targets");
1168 }
1169 
1170 void MCStreamer::emitXCOFFSymbolLinkageWithVisibility(MCSymbol *Symbol,
1171                                                       MCSymbolAttr Linkage,
1172                                                       MCSymbolAttr Visibility) {
1173   llvm_unreachable("emitXCOFFSymbolLinkageWithVisibility is only supported on "
1174                    "XCOFF targets");
1175 }
1176 
1177 void MCStreamer::emitXCOFFRenameDirective(const MCSymbol *Name,
1178                                           StringRef Rename) {
1179   llvm_unreachable("emitXCOFFRenameDirective is only supported on "
1180                    "XCOFF targets");
1181 }
1182 
1183 void MCStreamer::emitELFSize(MCSymbol *Symbol, const MCExpr *Value) {}
1184 void MCStreamer::emitELFSymverDirective(const MCSymbol *OriginalSym,
1185                                         StringRef Name, bool KeepOriginalSym) {}
1186 void MCStreamer::emitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,
1187                                        unsigned ByteAlignment) {}
1188 void MCStreamer::emitTBSSSymbol(MCSection *Section, MCSymbol *Symbol,
1189                                 uint64_t Size, unsigned ByteAlignment) {}
1190 void MCStreamer::changeSection(MCSection *, const MCExpr *) {}
1191 void MCStreamer::emitWeakReference(MCSymbol *Alias, const MCSymbol *Symbol) {}
1192 void MCStreamer::emitBytes(StringRef Data) {}
1193 void MCStreamer::emitBinaryData(StringRef Data) { emitBytes(Data); }
1194 void MCStreamer::emitValueImpl(const MCExpr *Value, unsigned Size, SMLoc Loc) {
1195   visitUsedExpr(*Value);
1196 }
1197 void MCStreamer::emitULEB128Value(const MCExpr *Value) {}
1198 void MCStreamer::emitSLEB128Value(const MCExpr *Value) {}
1199 void MCStreamer::emitFill(const MCExpr &NumBytes, uint64_t Value, SMLoc Loc) {}
1200 void MCStreamer::emitFill(const MCExpr &NumValues, int64_t Size, int64_t Expr,
1201                           SMLoc Loc) {}
1202 void MCStreamer::emitValueToAlignment(unsigned ByteAlignment, int64_t Value,
1203                                       unsigned ValueSize,
1204                                       unsigned MaxBytesToEmit) {}
1205 void MCStreamer::emitCodeAlignment(unsigned ByteAlignment,
1206                                    const MCSubtargetInfo *STI,
1207                                    unsigned MaxBytesToEmit) {}
1208 void MCStreamer::emitValueToOffset(const MCExpr *Offset, unsigned char Value,
1209                                    SMLoc Loc) {}
1210 void MCStreamer::emitBundleAlignMode(unsigned AlignPow2) {}
1211 void MCStreamer::emitBundleLock(bool AlignToEnd) {}
1212 void MCStreamer::finishImpl() {}
1213 void MCStreamer::emitBundleUnlock() {}
1214 
1215 void MCStreamer::SwitchSection(MCSection *Section, const MCExpr *Subsection) {
1216   assert(Section && "Cannot switch to a null section!");
1217   MCSectionSubPair curSection = SectionStack.back().first;
1218   SectionStack.back().second = curSection;
1219   if (MCSectionSubPair(Section, Subsection) != curSection) {
1220     changeSection(Section, Subsection);
1221     SectionStack.back().first = MCSectionSubPair(Section, Subsection);
1222     assert(!Section->hasEnded() && "Section already ended");
1223     MCSymbol *Sym = Section->getBeginSymbol();
1224     if (Sym && !Sym->isInSection())
1225       emitLabel(Sym);
1226   }
1227 }
1228 
1229 MCSymbol *MCStreamer::endSection(MCSection *Section) {
1230   // TODO: keep track of the last subsection so that this symbol appears in the
1231   // correct place.
1232   MCSymbol *Sym = Section->getEndSymbol(Context);
1233   if (Sym->isInSection())
1234     return Sym;
1235 
1236   SwitchSection(Section);
1237   emitLabel(Sym);
1238   return Sym;
1239 }
1240 
1241 static VersionTuple
1242 targetVersionOrMinimumSupportedOSVersion(const Triple &Target,
1243                                          VersionTuple TargetVersion) {
1244   VersionTuple Min = Target.getMinimumSupportedOSVersion();
1245   return !Min.empty() && Min > TargetVersion ? Min : TargetVersion;
1246 }
1247 
1248 static MCVersionMinType
1249 getMachoVersionMinLoadCommandType(const Triple &Target) {
1250   assert(Target.isOSDarwin() && "expected a darwin OS");
1251   switch (Target.getOS()) {
1252   case Triple::MacOSX:
1253   case Triple::Darwin:
1254     return MCVM_OSXVersionMin;
1255   case Triple::IOS:
1256     assert(!Target.isMacCatalystEnvironment() &&
1257            "mac Catalyst should use LC_BUILD_VERSION");
1258     return MCVM_IOSVersionMin;
1259   case Triple::TvOS:
1260     return MCVM_TvOSVersionMin;
1261   case Triple::WatchOS:
1262     return MCVM_WatchOSVersionMin;
1263   default:
1264     break;
1265   }
1266   llvm_unreachable("unexpected OS type");
1267 }
1268 
1269 static VersionTuple getMachoBuildVersionSupportedOS(const Triple &Target) {
1270   assert(Target.isOSDarwin() && "expected a darwin OS");
1271   switch (Target.getOS()) {
1272   case Triple::MacOSX:
1273   case Triple::Darwin:
1274     return VersionTuple(10, 14);
1275   case Triple::IOS:
1276     // Mac Catalyst always uses the build version load command.
1277     if (Target.isMacCatalystEnvironment())
1278       return VersionTuple();
1279     LLVM_FALLTHROUGH;
1280   case Triple::TvOS:
1281     return VersionTuple(12);
1282   case Triple::WatchOS:
1283     return VersionTuple(5);
1284   default:
1285     break;
1286   }
1287   llvm_unreachable("unexpected OS type");
1288 }
1289 
1290 static MachO::PlatformType
1291 getMachoBuildVersionPlatformType(const Triple &Target) {
1292   assert(Target.isOSDarwin() && "expected a darwin OS");
1293   switch (Target.getOS()) {
1294   case Triple::MacOSX:
1295   case Triple::Darwin:
1296     return MachO::PLATFORM_MACOS;
1297   case Triple::IOS:
1298     if (Target.isMacCatalystEnvironment())
1299       return MachO::PLATFORM_MACCATALYST;
1300     return Target.isSimulatorEnvironment() ? MachO::PLATFORM_IOSSIMULATOR
1301                                            : MachO::PLATFORM_IOS;
1302   case Triple::TvOS:
1303     return Target.isSimulatorEnvironment() ? MachO::PLATFORM_TVOSSIMULATOR
1304                                            : MachO::PLATFORM_TVOS;
1305   case Triple::WatchOS:
1306     return Target.isSimulatorEnvironment() ? MachO::PLATFORM_WATCHOSSIMULATOR
1307                                            : MachO::PLATFORM_WATCHOS;
1308   default:
1309     break;
1310   }
1311   llvm_unreachable("unexpected OS type");
1312 }
1313 
1314 void MCStreamer::emitVersionForTarget(
1315     const Triple &Target, const VersionTuple &SDKVersion,
1316     const Triple *DarwinTargetVariantTriple,
1317     const VersionTuple &DarwinTargetVariantSDKVersion) {
1318   if (!Target.isOSBinFormatMachO() || !Target.isOSDarwin())
1319     return;
1320   // Do we even know the version?
1321   if (Target.getOSMajorVersion() == 0)
1322     return;
1323 
1324   VersionTuple Version;
1325   switch (Target.getOS()) {
1326   case Triple::MacOSX:
1327   case Triple::Darwin:
1328     Target.getMacOSXVersion(Version);
1329     break;
1330   case Triple::IOS:
1331   case Triple::TvOS:
1332     Version = Target.getiOSVersion();
1333     break;
1334   case Triple::WatchOS:
1335     Version = Target.getWatchOSVersion();
1336     break;
1337   default:
1338     llvm_unreachable("unexpected OS type");
1339   }
1340   assert(Version.getMajor() != 0 && "A non-zero major version is expected");
1341   auto LinkedTargetVersion =
1342       targetVersionOrMinimumSupportedOSVersion(Target, Version);
1343   auto BuildVersionOSVersion = getMachoBuildVersionSupportedOS(Target);
1344   bool ShouldEmitBuildVersion = false;
1345   if (BuildVersionOSVersion.empty() ||
1346       LinkedTargetVersion >= BuildVersionOSVersion) {
1347     if (Target.isMacCatalystEnvironment() && DarwinTargetVariantTriple &&
1348         DarwinTargetVariantTriple->isMacOSX()) {
1349       emitVersionForTarget(*DarwinTargetVariantTriple,
1350                            DarwinTargetVariantSDKVersion,
1351                            /*DarwinTargetVariantTriple=*/nullptr,
1352                            /*DarwinTargetVariantSDKVersion=*/VersionTuple());
1353       emitDarwinTargetVariantBuildVersion(
1354           getMachoBuildVersionPlatformType(Target),
1355           LinkedTargetVersion.getMajor(),
1356           LinkedTargetVersion.getMinor().getValueOr(0),
1357           LinkedTargetVersion.getSubminor().getValueOr(0), SDKVersion);
1358       return;
1359     }
1360     emitBuildVersion(getMachoBuildVersionPlatformType(Target),
1361                      LinkedTargetVersion.getMajor(),
1362                      LinkedTargetVersion.getMinor().getValueOr(0),
1363                      LinkedTargetVersion.getSubminor().getValueOr(0),
1364                      SDKVersion);
1365     ShouldEmitBuildVersion = true;
1366   }
1367 
1368   if (const Triple *TVT = DarwinTargetVariantTriple) {
1369     if (Target.isMacOSX() && TVT->isMacCatalystEnvironment()) {
1370       auto TVLinkedTargetVersion =
1371           targetVersionOrMinimumSupportedOSVersion(*TVT, TVT->getiOSVersion());
1372       emitDarwinTargetVariantBuildVersion(
1373           getMachoBuildVersionPlatformType(*TVT),
1374           TVLinkedTargetVersion.getMajor(),
1375           TVLinkedTargetVersion.getMinor().getValueOr(0),
1376           TVLinkedTargetVersion.getSubminor().getValueOr(0),
1377           DarwinTargetVariantSDKVersion);
1378     }
1379   }
1380 
1381   if (ShouldEmitBuildVersion)
1382     return;
1383 
1384   emitVersionMin(getMachoVersionMinLoadCommandType(Target),
1385                  LinkedTargetVersion.getMajor(),
1386                  LinkedTargetVersion.getMinor().getValueOr(0),
1387                  LinkedTargetVersion.getSubminor().getValueOr(0), SDKVersion);
1388 }
1389