1 //===- lib/MC/ARMELFStreamer.cpp - ELF Object Output for ARM --------------===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file assembles .s files and emits ARM ELF .o object files. Different
11 // from generic ELF streamer in emitting mapping symbols ($a, $t and $d) to
12 // delimit regions of data and code.
13 //
14 //===----------------------------------------------------------------------===//
15 
16 #include "ARMRegisterInfo.h"
17 #include "ARMUnwindOpAsm.h"
18 #include "llvm/ADT/DenseMap.h"
19 #include "llvm/ADT/SmallString.h"
20 #include "llvm/ADT/SmallVector.h"
21 #include "llvm/ADT/StringRef.h"
22 #include "llvm/ADT/Triple.h"
23 #include "llvm/ADT/Twine.h"
24 #include "llvm/BinaryFormat/ELF.h"
25 #include "llvm/MC/MCAsmBackend.h"
26 #include "llvm/MC/MCAsmInfo.h"
27 #include "llvm/MC/MCAssembler.h"
28 #include "llvm/MC/MCCodeEmitter.h"
29 #include "llvm/MC/MCContext.h"
30 #include "llvm/MC/MCELFStreamer.h"
31 #include "llvm/MC/MCExpr.h"
32 #include "llvm/MC/MCFixup.h"
33 #include "llvm/MC/MCFragment.h"
34 #include "llvm/MC/MCInst.h"
35 #include "llvm/MC/MCInstPrinter.h"
36 #include "llvm/MC/MCRegisterInfo.h"
37 #include "llvm/MC/MCSection.h"
38 #include "llvm/MC/MCSectionELF.h"
39 #include "llvm/MC/MCStreamer.h"
40 #include "llvm/MC/MCSubtargetInfo.h"
41 #include "llvm/MC/MCSymbol.h"
42 #include "llvm/MC/MCSymbolELF.h"
43 #include "llvm/MC/SectionKind.h"
44 #include "llvm/Support/ARMBuildAttributes.h"
45 #include "llvm/Support/ARMEHABI.h"
46 #include "llvm/Support/Casting.h"
47 #include "llvm/Support/ErrorHandling.h"
48 #include "llvm/Support/FormattedStream.h"
49 #include "llvm/Support/LEB128.h"
50 #include "llvm/Support/TargetParser.h"
51 #include "llvm/Support/raw_ostream.h"
52 #include <algorithm>
53 #include <cassert>
54 #include <climits>
55 #include <cstddef>
56 #include <cstdint>
57 #include <string>
58 
59 using namespace llvm;
60 
61 static std::string GetAEABIUnwindPersonalityName(unsigned Index) {
62   assert(Index < ARM::EHABI::NUM_PERSONALITY_INDEX &&
63          "Invalid personality index");
64   return (Twine("__aeabi_unwind_cpp_pr") + Twine(Index)).str();
65 }
66 
67 namespace {
68 
69 class ARMELFStreamer;
70 
71 class ARMTargetAsmStreamer : public ARMTargetStreamer {
72   formatted_raw_ostream &OS;
73   MCInstPrinter &InstPrinter;
74   bool IsVerboseAsm;
75 
76   void emitFnStart() override;
77   void emitFnEnd() override;
78   void emitCantUnwind() override;
79   void emitPersonality(const MCSymbol *Personality) override;
80   void emitPersonalityIndex(unsigned Index) override;
81   void emitHandlerData() override;
82   void emitSetFP(unsigned FpReg, unsigned SpReg, int64_t Offset = 0) override;
83   void emitMovSP(unsigned Reg, int64_t Offset = 0) override;
84   void emitPad(int64_t Offset) override;
85   void emitRegSave(const SmallVectorImpl<unsigned> &RegList,
86                    bool isVector) override;
87   void emitUnwindRaw(int64_t Offset,
88                      const SmallVectorImpl<uint8_t> &Opcodes) override;
89 
90   void switchVendor(StringRef Vendor) override;
91   void emitAttribute(unsigned Attribute, unsigned Value) override;
92   void emitTextAttribute(unsigned Attribute, StringRef String) override;
93   void emitIntTextAttribute(unsigned Attribute, unsigned IntValue,
94                             StringRef StringValue) override;
95   void emitArch(ARM::ArchKind Arch) override;
96   void emitArchExtension(unsigned ArchExt) override;
97   void emitObjectArch(ARM::ArchKind Arch) override;
98   void emitFPU(unsigned FPU) override;
99   void emitInst(uint32_t Inst, char Suffix = '\0') override;
100   void finishAttributeSection() override;
101 
102   void AnnotateTLSDescriptorSequence(const MCSymbolRefExpr *SRE) override;
103   void emitThumbSet(MCSymbol *Symbol, const MCExpr *Value) override;
104 
105 public:
106   ARMTargetAsmStreamer(MCStreamer &S, formatted_raw_ostream &OS,
107                        MCInstPrinter &InstPrinter, bool VerboseAsm);
108 };
109 
110 ARMTargetAsmStreamer::ARMTargetAsmStreamer(MCStreamer &S,
111                                            formatted_raw_ostream &OS,
112                                            MCInstPrinter &InstPrinter,
113                                            bool VerboseAsm)
114     : ARMTargetStreamer(S), OS(OS), InstPrinter(InstPrinter),
115       IsVerboseAsm(VerboseAsm) {}
116 
117 void ARMTargetAsmStreamer::emitFnStart() { OS << "\t.fnstart\n"; }
118 void ARMTargetAsmStreamer::emitFnEnd() { OS << "\t.fnend\n"; }
119 void ARMTargetAsmStreamer::emitCantUnwind() { OS << "\t.cantunwind\n"; }
120 
121 void ARMTargetAsmStreamer::emitPersonality(const MCSymbol *Personality) {
122   OS << "\t.personality " << Personality->getName() << '\n';
123 }
124 
125 void ARMTargetAsmStreamer::emitPersonalityIndex(unsigned Index) {
126   OS << "\t.personalityindex " << Index << '\n';
127 }
128 
129 void ARMTargetAsmStreamer::emitHandlerData() { OS << "\t.handlerdata\n"; }
130 
131 void ARMTargetAsmStreamer::emitSetFP(unsigned FpReg, unsigned SpReg,
132                                      int64_t Offset) {
133   OS << "\t.setfp\t";
134   InstPrinter.printRegName(OS, FpReg);
135   OS << ", ";
136   InstPrinter.printRegName(OS, SpReg);
137   if (Offset)
138     OS << ", #" << Offset;
139   OS << '\n';
140 }
141 
142 void ARMTargetAsmStreamer::emitMovSP(unsigned Reg, int64_t Offset) {
143   assert((Reg != ARM::SP && Reg != ARM::PC) &&
144          "the operand of .movsp cannot be either sp or pc");
145 
146   OS << "\t.movsp\t";
147   InstPrinter.printRegName(OS, Reg);
148   if (Offset)
149     OS << ", #" << Offset;
150   OS << '\n';
151 }
152 
153 void ARMTargetAsmStreamer::emitPad(int64_t Offset) {
154   OS << "\t.pad\t#" << Offset << '\n';
155 }
156 
157 void ARMTargetAsmStreamer::emitRegSave(const SmallVectorImpl<unsigned> &RegList,
158                                        bool isVector) {
159   assert(RegList.size() && "RegList should not be empty");
160   if (isVector)
161     OS << "\t.vsave\t{";
162   else
163     OS << "\t.save\t{";
164 
165   InstPrinter.printRegName(OS, RegList[0]);
166 
167   for (unsigned i = 1, e = RegList.size(); i != e; ++i) {
168     OS << ", ";
169     InstPrinter.printRegName(OS, RegList[i]);
170   }
171 
172   OS << "}\n";
173 }
174 
175 void ARMTargetAsmStreamer::switchVendor(StringRef Vendor) {}
176 
177 void ARMTargetAsmStreamer::emitAttribute(unsigned Attribute, unsigned Value) {
178   OS << "\t.eabi_attribute\t" << Attribute << ", " << Twine(Value);
179   if (IsVerboseAsm) {
180     StringRef Name = ARMBuildAttrs::AttrTypeAsString(Attribute);
181     if (!Name.empty())
182       OS << "\t@ " << Name;
183   }
184   OS << "\n";
185 }
186 
187 void ARMTargetAsmStreamer::emitTextAttribute(unsigned Attribute,
188                                              StringRef String) {
189   switch (Attribute) {
190   case ARMBuildAttrs::CPU_name:
191     OS << "\t.cpu\t" << String.lower();
192     break;
193   default:
194     OS << "\t.eabi_attribute\t" << Attribute << ", \"" << String << "\"";
195     if (IsVerboseAsm) {
196       StringRef Name = ARMBuildAttrs::AttrTypeAsString(Attribute);
197       if (!Name.empty())
198         OS << "\t@ " << Name;
199     }
200     break;
201   }
202   OS << "\n";
203 }
204 
205 void ARMTargetAsmStreamer::emitIntTextAttribute(unsigned Attribute,
206                                                 unsigned IntValue,
207                                                 StringRef StringValue) {
208   switch (Attribute) {
209   default: llvm_unreachable("unsupported multi-value attribute in asm mode");
210   case ARMBuildAttrs::compatibility:
211     OS << "\t.eabi_attribute\t" << Attribute << ", " << IntValue;
212     if (!StringValue.empty())
213       OS << ", \"" << StringValue << "\"";
214     if (IsVerboseAsm)
215       OS << "\t@ " << ARMBuildAttrs::AttrTypeAsString(Attribute);
216     break;
217   }
218   OS << "\n";
219 }
220 
221 void ARMTargetAsmStreamer::emitArch(ARM::ArchKind Arch) {
222   OS << "\t.arch\t" << ARM::getArchName(Arch) << "\n";
223 }
224 
225 void ARMTargetAsmStreamer::emitArchExtension(unsigned ArchExt) {
226   OS << "\t.arch_extension\t" << ARM::getArchExtName(ArchExt) << "\n";
227 }
228 
229 void ARMTargetAsmStreamer::emitObjectArch(ARM::ArchKind Arch) {
230   OS << "\t.object_arch\t" << ARM::getArchName(Arch) << '\n';
231 }
232 
233 void ARMTargetAsmStreamer::emitFPU(unsigned FPU) {
234   OS << "\t.fpu\t" << ARM::getFPUName(FPU) << "\n";
235 }
236 
237 void ARMTargetAsmStreamer::finishAttributeSection() {}
238 
239 void
240 ARMTargetAsmStreamer::AnnotateTLSDescriptorSequence(const MCSymbolRefExpr *S) {
241   OS << "\t.tlsdescseq\t" << S->getSymbol().getName();
242 }
243 
244 void ARMTargetAsmStreamer::emitThumbSet(MCSymbol *Symbol, const MCExpr *Value) {
245   const MCAsmInfo *MAI = Streamer.getContext().getAsmInfo();
246 
247   OS << "\t.thumb_set\t";
248   Symbol->print(OS, MAI);
249   OS << ", ";
250   Value->print(OS, MAI);
251   OS << '\n';
252 }
253 
254 void ARMTargetAsmStreamer::emitInst(uint32_t Inst, char Suffix) {
255   OS << "\t.inst";
256   if (Suffix)
257     OS << "." << Suffix;
258   OS << "\t0x" << Twine::utohexstr(Inst) << "\n";
259 }
260 
261 void ARMTargetAsmStreamer::emitUnwindRaw(int64_t Offset,
262                                       const SmallVectorImpl<uint8_t> &Opcodes) {
263   OS << "\t.unwind_raw " << Offset;
264   for (SmallVectorImpl<uint8_t>::const_iterator OCI = Opcodes.begin(),
265                                                 OCE = Opcodes.end();
266        OCI != OCE; ++OCI)
267     OS << ", 0x" << Twine::utohexstr(*OCI);
268   OS << '\n';
269 }
270 
271 class ARMTargetELFStreamer : public ARMTargetStreamer {
272 private:
273   // This structure holds all attributes, accounting for
274   // their string/numeric value, so we can later emit them
275   // in declaration order, keeping all in the same vector
276   struct AttributeItem {
277     enum {
278       HiddenAttribute = 0,
279       NumericAttribute,
280       TextAttribute,
281       NumericAndTextAttributes
282     } Type;
283     unsigned Tag;
284     unsigned IntValue;
285     std::string StringValue;
286 
287     static bool LessTag(const AttributeItem &LHS, const AttributeItem &RHS) {
288       // The conformance tag must be emitted first when serialised
289       // into an object file. Specifically, the addenda to the ARM ABI
290       // states that (2.3.7.4):
291       //
292       // "To simplify recognition by consumers in the common case of
293       // claiming conformity for the whole file, this tag should be
294       // emitted first in a file-scope sub-subsection of the first
295       // public subsection of the attributes section."
296       //
297       // So it is special-cased in this comparison predicate when the
298       // attributes are sorted in finishAttributeSection().
299       return (RHS.Tag != ARMBuildAttrs::conformance) &&
300              ((LHS.Tag == ARMBuildAttrs::conformance) || (LHS.Tag < RHS.Tag));
301     }
302   };
303 
304   StringRef CurrentVendor;
305   unsigned FPU = ARM::FK_INVALID;
306   ARM::ArchKind Arch = ARM::ArchKind::INVALID;
307   ARM::ArchKind EmittedArch = ARM::ArchKind::INVALID;
308   SmallVector<AttributeItem, 64> Contents;
309 
310   MCSection *AttributeSection = nullptr;
311 
312   AttributeItem *getAttributeItem(unsigned Attribute) {
313     for (size_t i = 0; i < Contents.size(); ++i)
314       if (Contents[i].Tag == Attribute)
315         return &Contents[i];
316     return nullptr;
317   }
318 
319   void setAttributeItem(unsigned Attribute, unsigned Value,
320                         bool OverwriteExisting) {
321     // Look for existing attribute item
322     if (AttributeItem *Item = getAttributeItem(Attribute)) {
323       if (!OverwriteExisting)
324         return;
325       Item->Type = AttributeItem::NumericAttribute;
326       Item->IntValue = Value;
327       return;
328     }
329 
330     // Create new attribute item
331     AttributeItem Item = {
332       AttributeItem::NumericAttribute,
333       Attribute,
334       Value,
335       StringRef("")
336     };
337     Contents.push_back(Item);
338   }
339 
340   void setAttributeItem(unsigned Attribute, StringRef Value,
341                         bool OverwriteExisting) {
342     // Look for existing attribute item
343     if (AttributeItem *Item = getAttributeItem(Attribute)) {
344       if (!OverwriteExisting)
345         return;
346       Item->Type = AttributeItem::TextAttribute;
347       Item->StringValue = Value;
348       return;
349     }
350 
351     // Create new attribute item
352     AttributeItem Item = {
353       AttributeItem::TextAttribute,
354       Attribute,
355       0,
356       Value
357     };
358     Contents.push_back(Item);
359   }
360 
361   void setAttributeItems(unsigned Attribute, unsigned IntValue,
362                          StringRef StringValue, bool OverwriteExisting) {
363     // Look for existing attribute item
364     if (AttributeItem *Item = getAttributeItem(Attribute)) {
365       if (!OverwriteExisting)
366         return;
367       Item->Type = AttributeItem::NumericAndTextAttributes;
368       Item->IntValue = IntValue;
369       Item->StringValue = StringValue;
370       return;
371     }
372 
373     // Create new attribute item
374     AttributeItem Item = {
375       AttributeItem::NumericAndTextAttributes,
376       Attribute,
377       IntValue,
378       StringValue
379     };
380     Contents.push_back(Item);
381   }
382 
383   void emitArchDefaultAttributes();
384   void emitFPUDefaultAttributes();
385 
386   ARMELFStreamer &getStreamer();
387 
388   void emitFnStart() override;
389   void emitFnEnd() override;
390   void emitCantUnwind() override;
391   void emitPersonality(const MCSymbol *Personality) override;
392   void emitPersonalityIndex(unsigned Index) override;
393   void emitHandlerData() override;
394   void emitSetFP(unsigned FpReg, unsigned SpReg, int64_t Offset = 0) override;
395   void emitMovSP(unsigned Reg, int64_t Offset = 0) override;
396   void emitPad(int64_t Offset) override;
397   void emitRegSave(const SmallVectorImpl<unsigned> &RegList,
398                    bool isVector) override;
399   void emitUnwindRaw(int64_t Offset,
400                      const SmallVectorImpl<uint8_t> &Opcodes) override;
401 
402   void switchVendor(StringRef Vendor) override;
403   void emitAttribute(unsigned Attribute, unsigned Value) override;
404   void emitTextAttribute(unsigned Attribute, StringRef String) override;
405   void emitIntTextAttribute(unsigned Attribute, unsigned IntValue,
406                             StringRef StringValue) override;
407   void emitArch(ARM::ArchKind Arch) override;
408   void emitObjectArch(ARM::ArchKind Arch) override;
409   void emitFPU(unsigned FPU) override;
410   void emitInst(uint32_t Inst, char Suffix = '\0') override;
411   void finishAttributeSection() override;
412   void emitLabel(MCSymbol *Symbol) override;
413 
414   void AnnotateTLSDescriptorSequence(const MCSymbolRefExpr *SRE) override;
415   void emitThumbSet(MCSymbol *Symbol, const MCExpr *Value) override;
416 
417   size_t calculateContentSize() const;
418 
419   // Reset state between object emissions
420   void reset() override;
421 
422 public:
423   ARMTargetELFStreamer(MCStreamer &S)
424     : ARMTargetStreamer(S), CurrentVendor("aeabi") {}
425 };
426 
427 /// Extend the generic ELFStreamer class so that it can emit mapping symbols at
428 /// the appropriate points in the object files. These symbols are defined in the
429 /// ARM ELF ABI: infocenter.arm.com/help/topic/com.arm.../IHI0044D_aaelf.pdf.
430 ///
431 /// In brief: $a, $t or $d should be emitted at the start of each contiguous
432 /// region of ARM code, Thumb code or data in a section. In practice, this
433 /// emission does not rely on explicit assembler directives but on inherent
434 /// properties of the directives doing the emission (e.g. ".byte" is data, "add
435 /// r0, r0, r0" an instruction).
436 ///
437 /// As a result this system is orthogonal to the DataRegion infrastructure used
438 /// by MachO. Beware!
439 class ARMELFStreamer : public MCELFStreamer {
440 public:
441   friend class ARMTargetELFStreamer;
442 
443   ARMELFStreamer(MCContext &Context, std::unique_ptr<MCAsmBackend> TAB,
444                  raw_pwrite_stream &OS, std::unique_ptr<MCCodeEmitter> Emitter,
445                  bool IsThumb)
446       : MCELFStreamer(Context, std::move(TAB), OS, std::move(Emitter)),
447         IsThumb(IsThumb) {
448     EHReset();
449   }
450 
451   ~ARMELFStreamer() override = default;
452 
453   void FinishImpl() override;
454 
455   // ARM exception handling directives
456   void emitFnStart();
457   void emitFnEnd();
458   void emitCantUnwind();
459   void emitPersonality(const MCSymbol *Per);
460   void emitPersonalityIndex(unsigned index);
461   void emitHandlerData();
462   void emitSetFP(unsigned NewFpReg, unsigned NewSpReg, int64_t Offset = 0);
463   void emitMovSP(unsigned Reg, int64_t Offset = 0);
464   void emitPad(int64_t Offset);
465   void emitRegSave(const SmallVectorImpl<unsigned> &RegList, bool isVector);
466   void emitUnwindRaw(int64_t Offset, const SmallVectorImpl<uint8_t> &Opcodes);
467 
468   void ChangeSection(MCSection *Section, const MCExpr *Subsection) override {
469     LastMappingSymbols[getCurrentSection().first] = std::move(LastEMSInfo);
470     MCELFStreamer::ChangeSection(Section, Subsection);
471     auto LastMappingSymbol = LastMappingSymbols.find(Section);
472     if (LastMappingSymbol != LastMappingSymbols.end()) {
473       LastEMSInfo = std::move(LastMappingSymbol->second);
474       return;
475     }
476     LastEMSInfo.reset(new ElfMappingSymbolInfo(SMLoc(), nullptr, 0));
477   }
478 
479   /// This function is the one used to emit instruction data into the ELF
480   /// streamer. We override it to add the appropriate mapping symbol if
481   /// necessary.
482   void EmitInstruction(const MCInst &Inst, const MCSubtargetInfo &STI,
483                        bool) override {
484     if (IsThumb)
485       EmitThumbMappingSymbol();
486     else
487       EmitARMMappingSymbol();
488 
489     MCELFStreamer::EmitInstruction(Inst, STI);
490   }
491 
492   void emitInst(uint32_t Inst, char Suffix) {
493     unsigned Size;
494     char Buffer[4];
495     const bool LittleEndian = getContext().getAsmInfo()->isLittleEndian();
496 
497     switch (Suffix) {
498     case '\0':
499       Size = 4;
500 
501       assert(!IsThumb);
502       EmitARMMappingSymbol();
503       for (unsigned II = 0, IE = Size; II != IE; II++) {
504         const unsigned I = LittleEndian ? (Size - II - 1) : II;
505         Buffer[Size - II - 1] = uint8_t(Inst >> I * CHAR_BIT);
506       }
507 
508       break;
509     case 'n':
510     case 'w':
511       Size = (Suffix == 'n' ? 2 : 4);
512 
513       assert(IsThumb);
514       EmitThumbMappingSymbol();
515       for (unsigned II = 0, IE = Size; II != IE; II = II + 2) {
516         const unsigned I0 = LittleEndian ? II + 0 : (Size - II - 1);
517         const unsigned I1 = LittleEndian ? II + 1 : (Size - II - 2);
518         Buffer[Size - II - 2] = uint8_t(Inst >> I0 * CHAR_BIT);
519         Buffer[Size - II - 1] = uint8_t(Inst >> I1 * CHAR_BIT);
520       }
521 
522       break;
523     default:
524       llvm_unreachable("Invalid Suffix");
525     }
526 
527     MCELFStreamer::EmitBytes(StringRef(Buffer, Size));
528   }
529 
530   /// This is one of the functions used to emit data into an ELF section, so the
531   /// ARM streamer overrides it to add the appropriate mapping symbol ($d) if
532   /// necessary.
533   void EmitBytes(StringRef Data) override {
534     EmitDataMappingSymbol();
535     MCELFStreamer::EmitBytes(Data);
536   }
537 
538   void FlushPendingMappingSymbol() {
539     if (!LastEMSInfo->hasInfo())
540       return;
541     ElfMappingSymbolInfo *EMS = LastEMSInfo.get();
542     EmitMappingSymbol("$d", EMS->Loc, EMS->F, EMS->Offset);
543     EMS->resetInfo();
544   }
545 
546   /// This is one of the functions used to emit data into an ELF section, so the
547   /// ARM streamer overrides it to add the appropriate mapping symbol ($d) if
548   /// necessary.
549   void EmitValueImpl(const MCExpr *Value, unsigned Size, SMLoc Loc) override {
550     if (const MCSymbolRefExpr *SRE = dyn_cast_or_null<MCSymbolRefExpr>(Value)) {
551       if (SRE->getKind() == MCSymbolRefExpr::VK_ARM_SBREL && !(Size == 4)) {
552         getContext().reportError(Loc, "relocated expression must be 32-bit");
553         return;
554       }
555       getOrCreateDataFragment();
556     }
557 
558     EmitDataMappingSymbol();
559     MCELFStreamer::EmitValueImpl(Value, Size, Loc);
560   }
561 
562   void EmitAssemblerFlag(MCAssemblerFlag Flag) override {
563     MCELFStreamer::EmitAssemblerFlag(Flag);
564 
565     switch (Flag) {
566     case MCAF_SyntaxUnified:
567       return; // no-op here.
568     case MCAF_Code16:
569       IsThumb = true;
570       return; // Change to Thumb mode
571     case MCAF_Code32:
572       IsThumb = false;
573       return; // Change to ARM mode
574     case MCAF_Code64:
575       return;
576     case MCAF_SubsectionsViaSymbols:
577       return;
578     }
579   }
580 
581 private:
582   enum ElfMappingSymbol {
583     EMS_None,
584     EMS_ARM,
585     EMS_Thumb,
586     EMS_Data
587   };
588 
589   struct ElfMappingSymbolInfo {
590     explicit ElfMappingSymbolInfo(SMLoc Loc, MCFragment *F, uint64_t O)
591         : Loc(Loc), F(F), Offset(O), State(EMS_None) {}
592     void resetInfo() {
593       F = nullptr;
594       Offset = 0;
595     }
596     bool hasInfo() { return F != nullptr; }
597     SMLoc Loc;
598     MCFragment *F;
599     uint64_t Offset;
600     ElfMappingSymbol State;
601   };
602 
603   void EmitDataMappingSymbol() {
604     if (LastEMSInfo->State == EMS_Data)
605       return;
606     else if (LastEMSInfo->State == EMS_None) {
607       // This is a tentative symbol, it won't really be emitted until it's
608       // actually needed.
609       ElfMappingSymbolInfo *EMS = LastEMSInfo.get();
610       auto *DF = dyn_cast_or_null<MCDataFragment>(getCurrentFragment());
611       if (!DF)
612         return;
613       EMS->Loc = SMLoc();
614       EMS->F = getCurrentFragment();
615       EMS->Offset = DF->getContents().size();
616       LastEMSInfo->State = EMS_Data;
617       return;
618     }
619     EmitMappingSymbol("$d");
620     LastEMSInfo->State = EMS_Data;
621   }
622 
623   void EmitThumbMappingSymbol() {
624     if (LastEMSInfo->State == EMS_Thumb)
625       return;
626     FlushPendingMappingSymbol();
627     EmitMappingSymbol("$t");
628     LastEMSInfo->State = EMS_Thumb;
629   }
630 
631   void EmitARMMappingSymbol() {
632     if (LastEMSInfo->State == EMS_ARM)
633       return;
634     FlushPendingMappingSymbol();
635     EmitMappingSymbol("$a");
636     LastEMSInfo->State = EMS_ARM;
637   }
638 
639   void EmitMappingSymbol(StringRef Name) {
640     auto *Symbol = cast<MCSymbolELF>(getContext().getOrCreateSymbol(
641         Name + "." + Twine(MappingSymbolCounter++)));
642     EmitLabel(Symbol);
643 
644     Symbol->setType(ELF::STT_NOTYPE);
645     Symbol->setBinding(ELF::STB_LOCAL);
646     Symbol->setExternal(false);
647   }
648 
649   void EmitMappingSymbol(StringRef Name, SMLoc Loc, MCFragment *F,
650                          uint64_t Offset) {
651     auto *Symbol = cast<MCSymbolELF>(getContext().getOrCreateSymbol(
652         Name + "." + Twine(MappingSymbolCounter++)));
653     EmitLabel(Symbol, Loc, F);
654     Symbol->setType(ELF::STT_NOTYPE);
655     Symbol->setBinding(ELF::STB_LOCAL);
656     Symbol->setExternal(false);
657     Symbol->setOffset(Offset);
658   }
659 
660   void EmitThumbFunc(MCSymbol *Func) override {
661     getAssembler().setIsThumbFunc(Func);
662     EmitSymbolAttribute(Func, MCSA_ELF_TypeFunction);
663   }
664 
665   // Helper functions for ARM exception handling directives
666   void EHReset();
667 
668   // Reset state between object emissions
669   void reset() override;
670 
671   void EmitPersonalityFixup(StringRef Name);
672   void FlushPendingOffset();
673   void FlushUnwindOpcodes(bool NoHandlerData);
674 
675   void SwitchToEHSection(StringRef Prefix, unsigned Type, unsigned Flags,
676                          SectionKind Kind, const MCSymbol &Fn);
677   void SwitchToExTabSection(const MCSymbol &FnStart);
678   void SwitchToExIdxSection(const MCSymbol &FnStart);
679 
680   void EmitFixup(const MCExpr *Expr, MCFixupKind Kind);
681 
682   bool IsThumb;
683   int64_t MappingSymbolCounter = 0;
684 
685   DenseMap<const MCSection *, std::unique_ptr<ElfMappingSymbolInfo>>
686       LastMappingSymbols;
687 
688   std::unique_ptr<ElfMappingSymbolInfo> LastEMSInfo;
689 
690   // ARM Exception Handling Frame Information
691   MCSymbol *ExTab;
692   MCSymbol *FnStart;
693   const MCSymbol *Personality;
694   unsigned PersonalityIndex;
695   unsigned FPReg; // Frame pointer register
696   int64_t FPOffset; // Offset: (final frame pointer) - (initial $sp)
697   int64_t SPOffset; // Offset: (final $sp) - (initial $sp)
698   int64_t PendingOffset; // Offset: (final $sp) - (emitted $sp)
699   bool UsedFP;
700   bool CantUnwind;
701   SmallVector<uint8_t, 64> Opcodes;
702   UnwindOpcodeAssembler UnwindOpAsm;
703 };
704 
705 } // end anonymous namespace
706 
707 ARMELFStreamer &ARMTargetELFStreamer::getStreamer() {
708   return static_cast<ARMELFStreamer &>(Streamer);
709 }
710 
711 void ARMTargetELFStreamer::emitFnStart() { getStreamer().emitFnStart(); }
712 void ARMTargetELFStreamer::emitFnEnd() { getStreamer().emitFnEnd(); }
713 void ARMTargetELFStreamer::emitCantUnwind() { getStreamer().emitCantUnwind(); }
714 
715 void ARMTargetELFStreamer::emitPersonality(const MCSymbol *Personality) {
716   getStreamer().emitPersonality(Personality);
717 }
718 
719 void ARMTargetELFStreamer::emitPersonalityIndex(unsigned Index) {
720   getStreamer().emitPersonalityIndex(Index);
721 }
722 
723 void ARMTargetELFStreamer::emitHandlerData() {
724   getStreamer().emitHandlerData();
725 }
726 
727 void ARMTargetELFStreamer::emitSetFP(unsigned FpReg, unsigned SpReg,
728                                      int64_t Offset) {
729   getStreamer().emitSetFP(FpReg, SpReg, Offset);
730 }
731 
732 void ARMTargetELFStreamer::emitMovSP(unsigned Reg, int64_t Offset) {
733   getStreamer().emitMovSP(Reg, Offset);
734 }
735 
736 void ARMTargetELFStreamer::emitPad(int64_t Offset) {
737   getStreamer().emitPad(Offset);
738 }
739 
740 void ARMTargetELFStreamer::emitRegSave(const SmallVectorImpl<unsigned> &RegList,
741                                        bool isVector) {
742   getStreamer().emitRegSave(RegList, isVector);
743 }
744 
745 void ARMTargetELFStreamer::emitUnwindRaw(int64_t Offset,
746                                       const SmallVectorImpl<uint8_t> &Opcodes) {
747   getStreamer().emitUnwindRaw(Offset, Opcodes);
748 }
749 
750 void ARMTargetELFStreamer::switchVendor(StringRef Vendor) {
751   assert(!Vendor.empty() && "Vendor cannot be empty.");
752 
753   if (CurrentVendor == Vendor)
754     return;
755 
756   if (!CurrentVendor.empty())
757     finishAttributeSection();
758 
759   assert(Contents.empty() &&
760          ".ARM.attributes should be flushed before changing vendor");
761   CurrentVendor = Vendor;
762 
763 }
764 
765 void ARMTargetELFStreamer::emitAttribute(unsigned Attribute, unsigned Value) {
766   setAttributeItem(Attribute, Value, /* OverwriteExisting= */ true);
767 }
768 
769 void ARMTargetELFStreamer::emitTextAttribute(unsigned Attribute,
770                                              StringRef Value) {
771   setAttributeItem(Attribute, Value, /* OverwriteExisting= */ true);
772 }
773 
774 void ARMTargetELFStreamer::emitIntTextAttribute(unsigned Attribute,
775                                                 unsigned IntValue,
776                                                 StringRef StringValue) {
777   setAttributeItems(Attribute, IntValue, StringValue,
778                     /* OverwriteExisting= */ true);
779 }
780 
781 void ARMTargetELFStreamer::emitArch(ARM::ArchKind Value) {
782   Arch = Value;
783 }
784 
785 void ARMTargetELFStreamer::emitObjectArch(ARM::ArchKind Value) {
786   EmittedArch = Value;
787 }
788 
789 void ARMTargetELFStreamer::emitArchDefaultAttributes() {
790   using namespace ARMBuildAttrs;
791 
792   setAttributeItem(CPU_name,
793                    ARM::getCPUAttr(Arch),
794                    false);
795 
796   if (EmittedArch == ARM::ArchKind::INVALID)
797     setAttributeItem(CPU_arch,
798                      ARM::getArchAttr(Arch),
799                      false);
800   else
801     setAttributeItem(CPU_arch,
802                      ARM::getArchAttr(EmittedArch),
803                      false);
804 
805   switch (Arch) {
806   case ARM::ArchKind::ARMV2:
807   case ARM::ArchKind::ARMV2A:
808   case ARM::ArchKind::ARMV3:
809   case ARM::ArchKind::ARMV3M:
810   case ARM::ArchKind::ARMV4:
811     setAttributeItem(ARM_ISA_use, Allowed, false);
812     break;
813 
814   case ARM::ArchKind::ARMV4T:
815   case ARM::ArchKind::ARMV5T:
816   case ARM::ArchKind::ARMV5TE:
817   case ARM::ArchKind::ARMV6:
818     setAttributeItem(ARM_ISA_use, Allowed, false);
819     setAttributeItem(THUMB_ISA_use, Allowed, false);
820     break;
821 
822   case ARM::ArchKind::ARMV6T2:
823     setAttributeItem(ARM_ISA_use, Allowed, false);
824     setAttributeItem(THUMB_ISA_use, AllowThumb32, false);
825     break;
826 
827   case ARM::ArchKind::ARMV6K:
828   case ARM::ArchKind::ARMV6KZ:
829     setAttributeItem(ARM_ISA_use, Allowed, false);
830     setAttributeItem(THUMB_ISA_use, Allowed, false);
831     setAttributeItem(Virtualization_use, AllowTZ, false);
832     break;
833 
834   case ARM::ArchKind::ARMV6M:
835     setAttributeItem(THUMB_ISA_use, Allowed, false);
836     break;
837 
838   case ARM::ArchKind::ARMV7A:
839     setAttributeItem(CPU_arch_profile, ApplicationProfile, false);
840     setAttributeItem(ARM_ISA_use, Allowed, false);
841     setAttributeItem(THUMB_ISA_use, AllowThumb32, false);
842     break;
843 
844   case ARM::ArchKind::ARMV7R:
845     setAttributeItem(CPU_arch_profile, RealTimeProfile, false);
846     setAttributeItem(ARM_ISA_use, Allowed, false);
847     setAttributeItem(THUMB_ISA_use, AllowThumb32, false);
848     break;
849 
850   case ARM::ArchKind::ARMV7M:
851     setAttributeItem(CPU_arch_profile, MicroControllerProfile, false);
852     setAttributeItem(THUMB_ISA_use, AllowThumb32, false);
853     break;
854 
855   case ARM::ArchKind::ARMV8A:
856   case ARM::ArchKind::ARMV8_1A:
857   case ARM::ArchKind::ARMV8_2A:
858     setAttributeItem(CPU_arch_profile, ApplicationProfile, false);
859     setAttributeItem(ARM_ISA_use, Allowed, false);
860     setAttributeItem(THUMB_ISA_use, AllowThumb32, false);
861     setAttributeItem(MPextension_use, Allowed, false);
862     setAttributeItem(Virtualization_use, AllowTZVirtualization, false);
863     break;
864 
865   case ARM::ArchKind::ARMV8MBaseline:
866   case ARM::ArchKind::ARMV8MMainline:
867     setAttributeItem(THUMB_ISA_use, AllowThumbDerived, false);
868     setAttributeItem(CPU_arch_profile, MicroControllerProfile, false);
869     break;
870 
871   case ARM::ArchKind::IWMMXT:
872     setAttributeItem(ARM_ISA_use, Allowed, false);
873     setAttributeItem(THUMB_ISA_use, Allowed, false);
874     setAttributeItem(WMMX_arch, AllowWMMXv1, false);
875     break;
876 
877   case ARM::ArchKind::IWMMXT2:
878     setAttributeItem(ARM_ISA_use, Allowed, false);
879     setAttributeItem(THUMB_ISA_use, Allowed, false);
880     setAttributeItem(WMMX_arch, AllowWMMXv2, false);
881     break;
882 
883   default:
884     report_fatal_error("Unknown Arch: " + Twine(ARM::getArchName(Arch)));
885     break;
886   }
887 }
888 
889 void ARMTargetELFStreamer::emitFPU(unsigned Value) {
890   FPU = Value;
891 }
892 
893 void ARMTargetELFStreamer::emitFPUDefaultAttributes() {
894   switch (FPU) {
895   case ARM::FK_VFP:
896   case ARM::FK_VFPV2:
897     setAttributeItem(ARMBuildAttrs::FP_arch,
898                      ARMBuildAttrs::AllowFPv2,
899                      /* OverwriteExisting= */ false);
900     break;
901 
902   case ARM::FK_VFPV3:
903     setAttributeItem(ARMBuildAttrs::FP_arch,
904                      ARMBuildAttrs::AllowFPv3A,
905                      /* OverwriteExisting= */ false);
906     break;
907 
908   case ARM::FK_VFPV3_FP16:
909     setAttributeItem(ARMBuildAttrs::FP_arch,
910                      ARMBuildAttrs::AllowFPv3A,
911                      /* OverwriteExisting= */ false);
912     setAttributeItem(ARMBuildAttrs::FP_HP_extension,
913                      ARMBuildAttrs::AllowHPFP,
914                      /* OverwriteExisting= */ false);
915     break;
916 
917   case ARM::FK_VFPV3_D16:
918     setAttributeItem(ARMBuildAttrs::FP_arch,
919                      ARMBuildAttrs::AllowFPv3B,
920                      /* OverwriteExisting= */ false);
921     break;
922 
923   case ARM::FK_VFPV3_D16_FP16:
924     setAttributeItem(ARMBuildAttrs::FP_arch,
925                      ARMBuildAttrs::AllowFPv3B,
926                      /* OverwriteExisting= */ false);
927     setAttributeItem(ARMBuildAttrs::FP_HP_extension,
928                      ARMBuildAttrs::AllowHPFP,
929                      /* OverwriteExisting= */ false);
930     break;
931 
932   case ARM::FK_VFPV3XD:
933     setAttributeItem(ARMBuildAttrs::FP_arch,
934                      ARMBuildAttrs::AllowFPv3B,
935                      /* OverwriteExisting= */ false);
936     break;
937   case ARM::FK_VFPV3XD_FP16:
938     setAttributeItem(ARMBuildAttrs::FP_arch,
939                      ARMBuildAttrs::AllowFPv3B,
940                      /* OverwriteExisting= */ false);
941     setAttributeItem(ARMBuildAttrs::FP_HP_extension,
942                      ARMBuildAttrs::AllowHPFP,
943                      /* OverwriteExisting= */ false);
944     break;
945 
946   case ARM::FK_VFPV4:
947     setAttributeItem(ARMBuildAttrs::FP_arch,
948                      ARMBuildAttrs::AllowFPv4A,
949                      /* OverwriteExisting= */ false);
950     break;
951 
952   // ABI_HardFP_use is handled in ARMAsmPrinter, so _SP_D16 is treated the same
953   // as _D16 here.
954   case ARM::FK_FPV4_SP_D16:
955   case ARM::FK_VFPV4_D16:
956     setAttributeItem(ARMBuildAttrs::FP_arch,
957                      ARMBuildAttrs::AllowFPv4B,
958                      /* OverwriteExisting= */ false);
959     break;
960 
961   case ARM::FK_FP_ARMV8:
962     setAttributeItem(ARMBuildAttrs::FP_arch,
963                      ARMBuildAttrs::AllowFPARMv8A,
964                      /* OverwriteExisting= */ false);
965     break;
966 
967   // FPV5_D16 is identical to FP_ARMV8 except for the number of D registers, so
968   // uses the FP_ARMV8_D16 build attribute.
969   case ARM::FK_FPV5_SP_D16:
970   case ARM::FK_FPV5_D16:
971     setAttributeItem(ARMBuildAttrs::FP_arch,
972                      ARMBuildAttrs::AllowFPARMv8B,
973                      /* OverwriteExisting= */ false);
974     break;
975 
976   case ARM::FK_NEON:
977     setAttributeItem(ARMBuildAttrs::FP_arch,
978                      ARMBuildAttrs::AllowFPv3A,
979                      /* OverwriteExisting= */ false);
980     setAttributeItem(ARMBuildAttrs::Advanced_SIMD_arch,
981                      ARMBuildAttrs::AllowNeon,
982                      /* OverwriteExisting= */ false);
983     break;
984 
985   case ARM::FK_NEON_FP16:
986     setAttributeItem(ARMBuildAttrs::FP_arch,
987                      ARMBuildAttrs::AllowFPv3A,
988                      /* OverwriteExisting= */ false);
989     setAttributeItem(ARMBuildAttrs::Advanced_SIMD_arch,
990                      ARMBuildAttrs::AllowNeon,
991                      /* OverwriteExisting= */ false);
992     setAttributeItem(ARMBuildAttrs::FP_HP_extension,
993                      ARMBuildAttrs::AllowHPFP,
994                      /* OverwriteExisting= */ false);
995     break;
996 
997   case ARM::FK_NEON_VFPV4:
998     setAttributeItem(ARMBuildAttrs::FP_arch,
999                      ARMBuildAttrs::AllowFPv4A,
1000                      /* OverwriteExisting= */ false);
1001     setAttributeItem(ARMBuildAttrs::Advanced_SIMD_arch,
1002                      ARMBuildAttrs::AllowNeon2,
1003                      /* OverwriteExisting= */ false);
1004     break;
1005 
1006   case ARM::FK_NEON_FP_ARMV8:
1007   case ARM::FK_CRYPTO_NEON_FP_ARMV8:
1008     setAttributeItem(ARMBuildAttrs::FP_arch,
1009                      ARMBuildAttrs::AllowFPARMv8A,
1010                      /* OverwriteExisting= */ false);
1011     // 'Advanced_SIMD_arch' must be emitted not here, but within
1012     // ARMAsmPrinter::emitAttributes(), depending on hasV8Ops() and hasV8_1a()
1013     break;
1014 
1015   case ARM::FK_SOFTVFP:
1016   case ARM::FK_NONE:
1017     break;
1018 
1019   default:
1020     report_fatal_error("Unknown FPU: " + Twine(FPU));
1021     break;
1022   }
1023 }
1024 
1025 size_t ARMTargetELFStreamer::calculateContentSize() const {
1026   size_t Result = 0;
1027   for (size_t i = 0; i < Contents.size(); ++i) {
1028     AttributeItem item = Contents[i];
1029     switch (item.Type) {
1030     case AttributeItem::HiddenAttribute:
1031       break;
1032     case AttributeItem::NumericAttribute:
1033       Result += getULEB128Size(item.Tag);
1034       Result += getULEB128Size(item.IntValue);
1035       break;
1036     case AttributeItem::TextAttribute:
1037       Result += getULEB128Size(item.Tag);
1038       Result += item.StringValue.size() + 1; // string + '\0'
1039       break;
1040     case AttributeItem::NumericAndTextAttributes:
1041       Result += getULEB128Size(item.Tag);
1042       Result += getULEB128Size(item.IntValue);
1043       Result += item.StringValue.size() + 1; // string + '\0';
1044       break;
1045     }
1046   }
1047   return Result;
1048 }
1049 
1050 void ARMTargetELFStreamer::finishAttributeSection() {
1051   // <format-version>
1052   // [ <section-length> "vendor-name"
1053   // [ <file-tag> <size> <attribute>*
1054   //   | <section-tag> <size> <section-number>* 0 <attribute>*
1055   //   | <symbol-tag> <size> <symbol-number>* 0 <attribute>*
1056   //   ]+
1057   // ]*
1058 
1059   if (FPU != ARM::FK_INVALID)
1060     emitFPUDefaultAttributes();
1061 
1062   if (Arch != ARM::ArchKind::INVALID)
1063     emitArchDefaultAttributes();
1064 
1065   if (Contents.empty())
1066     return;
1067 
1068   std::sort(Contents.begin(), Contents.end(), AttributeItem::LessTag);
1069 
1070   ARMELFStreamer &Streamer = getStreamer();
1071 
1072   // Switch to .ARM.attributes section
1073   if (AttributeSection) {
1074     Streamer.SwitchSection(AttributeSection);
1075   } else {
1076     AttributeSection = Streamer.getContext().getELFSection(
1077         ".ARM.attributes", ELF::SHT_ARM_ATTRIBUTES, 0);
1078     Streamer.SwitchSection(AttributeSection);
1079 
1080     // Format version
1081     Streamer.EmitIntValue(0x41, 1);
1082   }
1083 
1084   // Vendor size + Vendor name + '\0'
1085   const size_t VendorHeaderSize = 4 + CurrentVendor.size() + 1;
1086 
1087   // Tag + Tag Size
1088   const size_t TagHeaderSize = 1 + 4;
1089 
1090   const size_t ContentsSize = calculateContentSize();
1091 
1092   Streamer.EmitIntValue(VendorHeaderSize + TagHeaderSize + ContentsSize, 4);
1093   Streamer.EmitBytes(CurrentVendor);
1094   Streamer.EmitIntValue(0, 1); // '\0'
1095 
1096   Streamer.EmitIntValue(ARMBuildAttrs::File, 1);
1097   Streamer.EmitIntValue(TagHeaderSize + ContentsSize, 4);
1098 
1099   // Size should have been accounted for already, now
1100   // emit each field as its type (ULEB or String)
1101   for (size_t i = 0; i < Contents.size(); ++i) {
1102     AttributeItem item = Contents[i];
1103     Streamer.EmitULEB128IntValue(item.Tag);
1104     switch (item.Type) {
1105     default: llvm_unreachable("Invalid attribute type");
1106     case AttributeItem::NumericAttribute:
1107       Streamer.EmitULEB128IntValue(item.IntValue);
1108       break;
1109     case AttributeItem::TextAttribute:
1110       Streamer.EmitBytes(item.StringValue);
1111       Streamer.EmitIntValue(0, 1); // '\0'
1112       break;
1113     case AttributeItem::NumericAndTextAttributes:
1114       Streamer.EmitULEB128IntValue(item.IntValue);
1115       Streamer.EmitBytes(item.StringValue);
1116       Streamer.EmitIntValue(0, 1); // '\0'
1117       break;
1118     }
1119   }
1120 
1121   Contents.clear();
1122   FPU = ARM::FK_INVALID;
1123 }
1124 
1125 void ARMTargetELFStreamer::emitLabel(MCSymbol *Symbol) {
1126   ARMELFStreamer &Streamer = getStreamer();
1127   if (!Streamer.IsThumb)
1128     return;
1129 
1130   Streamer.getAssembler().registerSymbol(*Symbol);
1131   unsigned Type = cast<MCSymbolELF>(Symbol)->getType();
1132   if (Type == ELF::STT_FUNC || Type == ELF::STT_GNU_IFUNC)
1133     Streamer.EmitThumbFunc(Symbol);
1134 }
1135 
1136 void
1137 ARMTargetELFStreamer::AnnotateTLSDescriptorSequence(const MCSymbolRefExpr *S) {
1138   getStreamer().EmitFixup(S, FK_Data_4);
1139 }
1140 
1141 void ARMTargetELFStreamer::emitThumbSet(MCSymbol *Symbol, const MCExpr *Value) {
1142   if (const MCSymbolRefExpr *SRE = dyn_cast<MCSymbolRefExpr>(Value)) {
1143     const MCSymbol &Sym = SRE->getSymbol();
1144     if (!Sym.isDefined()) {
1145       getStreamer().EmitAssignment(Symbol, Value);
1146       return;
1147     }
1148   }
1149 
1150   getStreamer().EmitThumbFunc(Symbol);
1151   getStreamer().EmitAssignment(Symbol, Value);
1152 }
1153 
1154 void ARMTargetELFStreamer::emitInst(uint32_t Inst, char Suffix) {
1155   getStreamer().emitInst(Inst, Suffix);
1156 }
1157 
1158 void ARMTargetELFStreamer::reset() { AttributeSection = nullptr; }
1159 
1160 void ARMELFStreamer::FinishImpl() {
1161   MCTargetStreamer &TS = *getTargetStreamer();
1162   ARMTargetStreamer &ATS = static_cast<ARMTargetStreamer &>(TS);
1163   ATS.finishAttributeSection();
1164 
1165   MCELFStreamer::FinishImpl();
1166 }
1167 
1168 void ARMELFStreamer::reset() {
1169   MCTargetStreamer &TS = *getTargetStreamer();
1170   ARMTargetStreamer &ATS = static_cast<ARMTargetStreamer &>(TS);
1171   ATS.reset();
1172   MappingSymbolCounter = 0;
1173   MCELFStreamer::reset();
1174   LastMappingSymbols.clear();
1175   LastEMSInfo.reset();
1176   // MCELFStreamer clear's the assembler's e_flags. However, for
1177   // arm we manually set the ABI version on streamer creation, so
1178   // do the same here
1179   getAssembler().setELFHeaderEFlags(ELF::EF_ARM_EABI_VER5);
1180 }
1181 
1182 inline void ARMELFStreamer::SwitchToEHSection(StringRef Prefix,
1183                                               unsigned Type,
1184                                               unsigned Flags,
1185                                               SectionKind Kind,
1186                                               const MCSymbol &Fn) {
1187   const MCSectionELF &FnSection =
1188     static_cast<const MCSectionELF &>(Fn.getSection());
1189 
1190   // Create the name for new section
1191   StringRef FnSecName(FnSection.getSectionName());
1192   SmallString<128> EHSecName(Prefix);
1193   if (FnSecName != ".text") {
1194     EHSecName += FnSecName;
1195   }
1196 
1197   // Get .ARM.extab or .ARM.exidx section
1198   const MCSymbolELF *Group = FnSection.getGroup();
1199   if (Group)
1200     Flags |= ELF::SHF_GROUP;
1201   MCSectionELF *EHSection = getContext().getELFSection(
1202       EHSecName, Type, Flags, 0, Group, FnSection.getUniqueID(),
1203       static_cast<const MCSymbolELF *>(&Fn));
1204 
1205   assert(EHSection && "Failed to get the required EH section");
1206 
1207   // Switch to .ARM.extab or .ARM.exidx section
1208   SwitchSection(EHSection);
1209   EmitCodeAlignment(4);
1210 }
1211 
1212 inline void ARMELFStreamer::SwitchToExTabSection(const MCSymbol &FnStart) {
1213   SwitchToEHSection(".ARM.extab", ELF::SHT_PROGBITS, ELF::SHF_ALLOC,
1214                     SectionKind::getData(), FnStart);
1215 }
1216 
1217 inline void ARMELFStreamer::SwitchToExIdxSection(const MCSymbol &FnStart) {
1218   SwitchToEHSection(".ARM.exidx", ELF::SHT_ARM_EXIDX,
1219                     ELF::SHF_ALLOC | ELF::SHF_LINK_ORDER,
1220                     SectionKind::getData(), FnStart);
1221 }
1222 
1223 void ARMELFStreamer::EmitFixup(const MCExpr *Expr, MCFixupKind Kind) {
1224   MCDataFragment *Frag = getOrCreateDataFragment();
1225   Frag->getFixups().push_back(MCFixup::create(Frag->getContents().size(), Expr,
1226                                               Kind));
1227 }
1228 
1229 void ARMELFStreamer::EHReset() {
1230   ExTab = nullptr;
1231   FnStart = nullptr;
1232   Personality = nullptr;
1233   PersonalityIndex = ARM::EHABI::NUM_PERSONALITY_INDEX;
1234   FPReg = ARM::SP;
1235   FPOffset = 0;
1236   SPOffset = 0;
1237   PendingOffset = 0;
1238   UsedFP = false;
1239   CantUnwind = false;
1240 
1241   Opcodes.clear();
1242   UnwindOpAsm.Reset();
1243 }
1244 
1245 void ARMELFStreamer::emitFnStart() {
1246   assert(FnStart == nullptr);
1247   FnStart = getContext().createTempSymbol();
1248   EmitLabel(FnStart);
1249 }
1250 
1251 void ARMELFStreamer::emitFnEnd() {
1252   assert(FnStart && ".fnstart must precedes .fnend");
1253 
1254   // Emit unwind opcodes if there is no .handlerdata directive
1255   if (!ExTab && !CantUnwind)
1256     FlushUnwindOpcodes(true);
1257 
1258   // Emit the exception index table entry
1259   SwitchToExIdxSection(*FnStart);
1260 
1261   if (PersonalityIndex < ARM::EHABI::NUM_PERSONALITY_INDEX)
1262     EmitPersonalityFixup(GetAEABIUnwindPersonalityName(PersonalityIndex));
1263 
1264   const MCSymbolRefExpr *FnStartRef =
1265     MCSymbolRefExpr::create(FnStart,
1266                             MCSymbolRefExpr::VK_ARM_PREL31,
1267                             getContext());
1268 
1269   EmitValue(FnStartRef, 4);
1270 
1271   if (CantUnwind) {
1272     EmitIntValue(ARM::EHABI::EXIDX_CANTUNWIND, 4);
1273   } else if (ExTab) {
1274     // Emit a reference to the unwind opcodes in the ".ARM.extab" section.
1275     const MCSymbolRefExpr *ExTabEntryRef =
1276       MCSymbolRefExpr::create(ExTab,
1277                               MCSymbolRefExpr::VK_ARM_PREL31,
1278                               getContext());
1279     EmitValue(ExTabEntryRef, 4);
1280   } else {
1281     // For the __aeabi_unwind_cpp_pr0, we have to emit the unwind opcodes in
1282     // the second word of exception index table entry.  The size of the unwind
1283     // opcodes should always be 4 bytes.
1284     assert(PersonalityIndex == ARM::EHABI::AEABI_UNWIND_CPP_PR0 &&
1285            "Compact model must use __aeabi_unwind_cpp_pr0 as personality");
1286     assert(Opcodes.size() == 4u &&
1287            "Unwind opcode size for __aeabi_unwind_cpp_pr0 must be equal to 4");
1288     uint64_t Intval = Opcodes[0] |
1289                       Opcodes[1] << 8 |
1290                       Opcodes[2] << 16 |
1291                       Opcodes[3] << 24;
1292     EmitIntValue(Intval, Opcodes.size());
1293   }
1294 
1295   // Switch to the section containing FnStart
1296   SwitchSection(&FnStart->getSection());
1297 
1298   // Clean exception handling frame information
1299   EHReset();
1300 }
1301 
1302 void ARMELFStreamer::emitCantUnwind() { CantUnwind = true; }
1303 
1304 // Add the R_ARM_NONE fixup at the same position
1305 void ARMELFStreamer::EmitPersonalityFixup(StringRef Name) {
1306   const MCSymbol *PersonalitySym = getContext().getOrCreateSymbol(Name);
1307 
1308   const MCSymbolRefExpr *PersonalityRef = MCSymbolRefExpr::create(
1309       PersonalitySym, MCSymbolRefExpr::VK_ARM_NONE, getContext());
1310 
1311   visitUsedExpr(*PersonalityRef);
1312   MCDataFragment *DF = getOrCreateDataFragment();
1313   DF->getFixups().push_back(MCFixup::create(DF->getContents().size(),
1314                                             PersonalityRef,
1315                                             MCFixup::getKindForSize(4, false)));
1316 }
1317 
1318 void ARMELFStreamer::FlushPendingOffset() {
1319   if (PendingOffset != 0) {
1320     UnwindOpAsm.EmitSPOffset(-PendingOffset);
1321     PendingOffset = 0;
1322   }
1323 }
1324 
1325 void ARMELFStreamer::FlushUnwindOpcodes(bool NoHandlerData) {
1326   // Emit the unwind opcode to restore $sp.
1327   if (UsedFP) {
1328     const MCRegisterInfo *MRI = getContext().getRegisterInfo();
1329     int64_t LastRegSaveSPOffset = SPOffset - PendingOffset;
1330     UnwindOpAsm.EmitSPOffset(LastRegSaveSPOffset - FPOffset);
1331     UnwindOpAsm.EmitSetSP(MRI->getEncodingValue(FPReg));
1332   } else {
1333     FlushPendingOffset();
1334   }
1335 
1336   // Finalize the unwind opcode sequence
1337   UnwindOpAsm.Finalize(PersonalityIndex, Opcodes);
1338 
1339   // For compact model 0, we have to emit the unwind opcodes in the .ARM.exidx
1340   // section.  Thus, we don't have to create an entry in the .ARM.extab
1341   // section.
1342   if (NoHandlerData && PersonalityIndex == ARM::EHABI::AEABI_UNWIND_CPP_PR0)
1343     return;
1344 
1345   // Switch to .ARM.extab section.
1346   SwitchToExTabSection(*FnStart);
1347 
1348   // Create .ARM.extab label for offset in .ARM.exidx
1349   assert(!ExTab);
1350   ExTab = getContext().createTempSymbol();
1351   EmitLabel(ExTab);
1352 
1353   // Emit personality
1354   if (Personality) {
1355     const MCSymbolRefExpr *PersonalityRef =
1356       MCSymbolRefExpr::create(Personality,
1357                               MCSymbolRefExpr::VK_ARM_PREL31,
1358                               getContext());
1359 
1360     EmitValue(PersonalityRef, 4);
1361   }
1362 
1363   // Emit unwind opcodes
1364   assert((Opcodes.size() % 4) == 0 &&
1365          "Unwind opcode size for __aeabi_cpp_unwind_pr0 must be multiple of 4");
1366   for (unsigned I = 0; I != Opcodes.size(); I += 4) {
1367     uint64_t Intval = Opcodes[I] |
1368                       Opcodes[I + 1] << 8 |
1369                       Opcodes[I + 2] << 16 |
1370                       Opcodes[I + 3] << 24;
1371     EmitIntValue(Intval, 4);
1372   }
1373 
1374   // According to ARM EHABI section 9.2, if the __aeabi_unwind_cpp_pr1() or
1375   // __aeabi_unwind_cpp_pr2() is used, then the handler data must be emitted
1376   // after the unwind opcodes.  The handler data consists of several 32-bit
1377   // words, and should be terminated by zero.
1378   //
1379   // In case that the .handlerdata directive is not specified by the
1380   // programmer, we should emit zero to terminate the handler data.
1381   if (NoHandlerData && !Personality)
1382     EmitIntValue(0, 4);
1383 }
1384 
1385 void ARMELFStreamer::emitHandlerData() { FlushUnwindOpcodes(false); }
1386 
1387 void ARMELFStreamer::emitPersonality(const MCSymbol *Per) {
1388   Personality = Per;
1389   UnwindOpAsm.setPersonality(Per);
1390 }
1391 
1392 void ARMELFStreamer::emitPersonalityIndex(unsigned Index) {
1393   assert(Index < ARM::EHABI::NUM_PERSONALITY_INDEX && "invalid index");
1394   PersonalityIndex = Index;
1395 }
1396 
1397 void ARMELFStreamer::emitSetFP(unsigned NewFPReg, unsigned NewSPReg,
1398                                int64_t Offset) {
1399   assert((NewSPReg == ARM::SP || NewSPReg == FPReg) &&
1400          "the operand of .setfp directive should be either $sp or $fp");
1401 
1402   UsedFP = true;
1403   FPReg = NewFPReg;
1404 
1405   if (NewSPReg == ARM::SP)
1406     FPOffset = SPOffset + Offset;
1407   else
1408     FPOffset += Offset;
1409 }
1410 
1411 void ARMELFStreamer::emitMovSP(unsigned Reg, int64_t Offset) {
1412   assert((Reg != ARM::SP && Reg != ARM::PC) &&
1413          "the operand of .movsp cannot be either sp or pc");
1414   assert(FPReg == ARM::SP && "current FP must be SP");
1415 
1416   FlushPendingOffset();
1417 
1418   FPReg = Reg;
1419   FPOffset = SPOffset + Offset;
1420 
1421   const MCRegisterInfo *MRI = getContext().getRegisterInfo();
1422   UnwindOpAsm.EmitSetSP(MRI->getEncodingValue(FPReg));
1423 }
1424 
1425 void ARMELFStreamer::emitPad(int64_t Offset) {
1426   // Track the change of the $sp offset
1427   SPOffset -= Offset;
1428 
1429   // To squash multiple .pad directives, we should delay the unwind opcode
1430   // until the .save, .vsave, .handlerdata, or .fnend directives.
1431   PendingOffset -= Offset;
1432 }
1433 
1434 void ARMELFStreamer::emitRegSave(const SmallVectorImpl<unsigned> &RegList,
1435                                  bool IsVector) {
1436   // Collect the registers in the register list
1437   unsigned Count = 0;
1438   uint32_t Mask = 0;
1439   const MCRegisterInfo *MRI = getContext().getRegisterInfo();
1440   for (size_t i = 0; i < RegList.size(); ++i) {
1441     unsigned Reg = MRI->getEncodingValue(RegList[i]);
1442     assert(Reg < (IsVector ? 32U : 16U) && "Register out of range");
1443     unsigned Bit = (1u << Reg);
1444     if ((Mask & Bit) == 0) {
1445       Mask |= Bit;
1446       ++Count;
1447     }
1448   }
1449 
1450   // Track the change the $sp offset: For the .save directive, the
1451   // corresponding push instruction will decrease the $sp by (4 * Count).
1452   // For the .vsave directive, the corresponding vpush instruction will
1453   // decrease $sp by (8 * Count).
1454   SPOffset -= Count * (IsVector ? 8 : 4);
1455 
1456   // Emit the opcode
1457   FlushPendingOffset();
1458   if (IsVector)
1459     UnwindOpAsm.EmitVFPRegSave(Mask);
1460   else
1461     UnwindOpAsm.EmitRegSave(Mask);
1462 }
1463 
1464 void ARMELFStreamer::emitUnwindRaw(int64_t Offset,
1465                                    const SmallVectorImpl<uint8_t> &Opcodes) {
1466   FlushPendingOffset();
1467   SPOffset = SPOffset - Offset;
1468   UnwindOpAsm.EmitRaw(Opcodes);
1469 }
1470 
1471 namespace llvm {
1472 
1473 MCTargetStreamer *createARMTargetAsmStreamer(MCStreamer &S,
1474                                              formatted_raw_ostream &OS,
1475                                              MCInstPrinter *InstPrint,
1476                                              bool isVerboseAsm) {
1477   return new ARMTargetAsmStreamer(S, OS, *InstPrint, isVerboseAsm);
1478 }
1479 
1480 MCTargetStreamer *createARMNullTargetStreamer(MCStreamer &S) {
1481   return new ARMTargetStreamer(S);
1482 }
1483 
1484 MCTargetStreamer *createARMObjectTargetStreamer(MCStreamer &S,
1485                                                 const MCSubtargetInfo &STI) {
1486   const Triple &TT = STI.getTargetTriple();
1487   if (TT.isOSBinFormatELF())
1488     return new ARMTargetELFStreamer(S);
1489   return new ARMTargetStreamer(S);
1490 }
1491 
1492 MCELFStreamer *createARMELFStreamer(MCContext &Context,
1493                                     std::unique_ptr<MCAsmBackend> TAB,
1494                                     raw_pwrite_stream &OS,
1495                                     std::unique_ptr<MCCodeEmitter> Emitter,
1496                                     bool RelaxAll, bool IsThumb) {
1497   ARMELFStreamer *S = new ARMELFStreamer(Context, std::move(TAB), OS,
1498                                          std::move(Emitter), IsThumb);
1499   // FIXME: This should eventually end up somewhere else where more
1500   // intelligent flag decisions can be made. For now we are just maintaining
1501   // the status quo for ARM and setting EF_ARM_EABI_VER5 as the default.
1502   S->getAssembler().setELFHeaderEFlags(ELF::EF_ARM_EABI_VER5);
1503 
1504   if (RelaxAll)
1505     S->getAssembler().setRelaxAll(true);
1506   return S;
1507 }
1508 
1509 } // end namespace llvm
1510