1 //===- lib/MC/ARMELFStreamer.cpp - ELF Object Output for ARM --------------===//
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 // This file assembles .s files and emits ARM ELF .o object files. Different
10 // from generic ELF streamer in emitting mapping symbols ($a, $t and $d) to
11 // delimit regions of data and code.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #include "ARMRegisterInfo.h"
16 #include "ARMUnwindOpAsm.h"
17 #include "llvm/ADT/DenseMap.h"
18 #include "llvm/ADT/SmallString.h"
19 #include "llvm/ADT/SmallVector.h"
20 #include "llvm/ADT/StringRef.h"
21 #include "llvm/ADT/Triple.h"
22 #include "llvm/ADT/Twine.h"
23 #include "llvm/BinaryFormat/ELF.h"
24 #include "llvm/MC/MCAsmBackend.h"
25 #include "llvm/MC/MCAsmInfo.h"
26 #include "llvm/MC/MCAssembler.h"
27 #include "llvm/MC/MCCodeEmitter.h"
28 #include "llvm/MC/MCContext.h"
29 #include "llvm/MC/MCELFStreamer.h"
30 #include "llvm/MC/MCExpr.h"
31 #include "llvm/MC/MCFixup.h"
32 #include "llvm/MC/MCFragment.h"
33 #include "llvm/MC/MCInst.h"
34 #include "llvm/MC/MCInstPrinter.h"
35 #include "llvm/MC/MCObjectWriter.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(uint64_t 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 =
181         ELFAttrs::attrTypeAsString(Attribute, ARMBuildAttrs::ARMAttributeTags);
182     if (!Name.empty())
183       OS << "\t@ " << Name;
184   }
185   OS << "\n";
186 }
187 
188 void ARMTargetAsmStreamer::emitTextAttribute(unsigned Attribute,
189                                              StringRef String) {
190   switch (Attribute) {
191   case ARMBuildAttrs::CPU_name:
192     OS << "\t.cpu\t" << String.lower();
193     break;
194   default:
195     OS << "\t.eabi_attribute\t" << Attribute << ", \"" << String << "\"";
196     if (IsVerboseAsm) {
197       StringRef Name = ELFAttrs::attrTypeAsString(
198           Attribute, ARMBuildAttrs::ARMAttributeTags);
199       if (!Name.empty())
200         OS << "\t@ " << Name;
201     }
202     break;
203   }
204   OS << "\n";
205 }
206 
207 void ARMTargetAsmStreamer::emitIntTextAttribute(unsigned Attribute,
208                                                 unsigned IntValue,
209                                                 StringRef StringValue) {
210   switch (Attribute) {
211   default: llvm_unreachable("unsupported multi-value attribute in asm mode");
212   case ARMBuildAttrs::compatibility:
213     OS << "\t.eabi_attribute\t" << Attribute << ", " << IntValue;
214     if (!StringValue.empty())
215       OS << ", \"" << StringValue << "\"";
216     if (IsVerboseAsm)
217       OS << "\t@ "
218          << ELFAttrs::attrTypeAsString(Attribute,
219                                        ARMBuildAttrs::ARMAttributeTags);
220     break;
221   }
222   OS << "\n";
223 }
224 
225 void ARMTargetAsmStreamer::emitArch(ARM::ArchKind Arch) {
226   OS << "\t.arch\t" << ARM::getArchName(Arch) << "\n";
227 }
228 
229 void ARMTargetAsmStreamer::emitArchExtension(uint64_t ArchExt) {
230   OS << "\t.arch_extension\t" << ARM::getArchExtName(ArchExt) << "\n";
231 }
232 
233 void ARMTargetAsmStreamer::emitObjectArch(ARM::ArchKind Arch) {
234   OS << "\t.object_arch\t" << ARM::getArchName(Arch) << '\n';
235 }
236 
237 void ARMTargetAsmStreamer::emitFPU(unsigned FPU) {
238   OS << "\t.fpu\t" << ARM::getFPUName(FPU) << "\n";
239 }
240 
241 void ARMTargetAsmStreamer::finishAttributeSection() {}
242 
243 void
244 ARMTargetAsmStreamer::AnnotateTLSDescriptorSequence(const MCSymbolRefExpr *S) {
245   OS << "\t.tlsdescseq\t" << S->getSymbol().getName() << "\n";
246 }
247 
248 void ARMTargetAsmStreamer::emitThumbSet(MCSymbol *Symbol, const MCExpr *Value) {
249   const MCAsmInfo *MAI = Streamer.getContext().getAsmInfo();
250 
251   OS << "\t.thumb_set\t";
252   Symbol->print(OS, MAI);
253   OS << ", ";
254   Value->print(OS, MAI);
255   OS << '\n';
256 }
257 
258 void ARMTargetAsmStreamer::emitInst(uint32_t Inst, char Suffix) {
259   OS << "\t.inst";
260   if (Suffix)
261     OS << "." << Suffix;
262   OS << "\t0x" << Twine::utohexstr(Inst) << "\n";
263 }
264 
265 void ARMTargetAsmStreamer::emitUnwindRaw(int64_t Offset,
266                                       const SmallVectorImpl<uint8_t> &Opcodes) {
267   OS << "\t.unwind_raw " << Offset;
268   for (SmallVectorImpl<uint8_t>::const_iterator OCI = Opcodes.begin(),
269                                                 OCE = Opcodes.end();
270        OCI != OCE; ++OCI)
271     OS << ", 0x" << Twine::utohexstr(*OCI);
272   OS << '\n';
273 }
274 
275 class ARMTargetELFStreamer : public ARMTargetStreamer {
276 private:
277   // This structure holds all attributes, accounting for
278   // their string/numeric value, so we can later emit them
279   // in declaration order, keeping all in the same vector
280   struct AttributeItem {
281     enum {
282       HiddenAttribute = 0,
283       NumericAttribute,
284       TextAttribute,
285       NumericAndTextAttributes
286     } Type;
287     unsigned Tag;
288     unsigned IntValue;
289     std::string StringValue;
290 
291     static bool LessTag(const AttributeItem &LHS, const AttributeItem &RHS) {
292       // The conformance tag must be emitted first when serialised
293       // into an object file. Specifically, the addenda to the ARM ABI
294       // states that (2.3.7.4):
295       //
296       // "To simplify recognition by consumers in the common case of
297       // claiming conformity for the whole file, this tag should be
298       // emitted first in a file-scope sub-subsection of the first
299       // public subsection of the attributes section."
300       //
301       // So it is special-cased in this comparison predicate when the
302       // attributes are sorted in finishAttributeSection().
303       return (RHS.Tag != ARMBuildAttrs::conformance) &&
304              ((LHS.Tag == ARMBuildAttrs::conformance) || (LHS.Tag < RHS.Tag));
305     }
306   };
307 
308   StringRef CurrentVendor;
309   unsigned FPU = ARM::FK_INVALID;
310   ARM::ArchKind Arch = ARM::ArchKind::INVALID;
311   ARM::ArchKind EmittedArch = ARM::ArchKind::INVALID;
312   SmallVector<AttributeItem, 64> Contents;
313 
314   MCSection *AttributeSection = nullptr;
315 
316   AttributeItem *getAttributeItem(unsigned Attribute) {
317     for (size_t i = 0; i < Contents.size(); ++i)
318       if (Contents[i].Tag == Attribute)
319         return &Contents[i];
320     return nullptr;
321   }
322 
323   void setAttributeItem(unsigned Attribute, unsigned Value,
324                         bool OverwriteExisting) {
325     // Look for existing attribute item
326     if (AttributeItem *Item = getAttributeItem(Attribute)) {
327       if (!OverwriteExisting)
328         return;
329       Item->Type = AttributeItem::NumericAttribute;
330       Item->IntValue = Value;
331       return;
332     }
333 
334     // Create new attribute item
335     AttributeItem Item = {AttributeItem::NumericAttribute, Attribute, Value,
336                           std::string(StringRef(""))};
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 = std::string(Value);
348       return;
349     }
350 
351     // Create new attribute item
352     AttributeItem Item = {AttributeItem::TextAttribute, Attribute, 0,
353                           std::string(Value)};
354     Contents.push_back(Item);
355   }
356 
357   void setAttributeItems(unsigned Attribute, unsigned IntValue,
358                          StringRef StringValue, bool OverwriteExisting) {
359     // Look for existing attribute item
360     if (AttributeItem *Item = getAttributeItem(Attribute)) {
361       if (!OverwriteExisting)
362         return;
363       Item->Type = AttributeItem::NumericAndTextAttributes;
364       Item->IntValue = IntValue;
365       Item->StringValue = std::string(StringValue);
366       return;
367     }
368 
369     // Create new attribute item
370     AttributeItem Item = {AttributeItem::NumericAndTextAttributes, Attribute,
371                           IntValue, std::string(StringValue)};
372     Contents.push_back(Item);
373   }
374 
375   void emitArchDefaultAttributes();
376   void emitFPUDefaultAttributes();
377 
378   ARMELFStreamer &getStreamer();
379 
380   void emitFnStart() override;
381   void emitFnEnd() override;
382   void emitCantUnwind() override;
383   void emitPersonality(const MCSymbol *Personality) override;
384   void emitPersonalityIndex(unsigned Index) override;
385   void emitHandlerData() override;
386   void emitSetFP(unsigned FpReg, unsigned SpReg, int64_t Offset = 0) override;
387   void emitMovSP(unsigned Reg, int64_t Offset = 0) override;
388   void emitPad(int64_t Offset) override;
389   void emitRegSave(const SmallVectorImpl<unsigned> &RegList,
390                    bool isVector) override;
391   void emitUnwindRaw(int64_t Offset,
392                      const SmallVectorImpl<uint8_t> &Opcodes) override;
393 
394   void switchVendor(StringRef Vendor) override;
395   void emitAttribute(unsigned Attribute, unsigned Value) override;
396   void emitTextAttribute(unsigned Attribute, StringRef String) override;
397   void emitIntTextAttribute(unsigned Attribute, unsigned IntValue,
398                             StringRef StringValue) override;
399   void emitArch(ARM::ArchKind Arch) override;
400   void emitObjectArch(ARM::ArchKind Arch) override;
401   void emitFPU(unsigned FPU) override;
402   void emitInst(uint32_t Inst, char Suffix = '\0') override;
403   void finishAttributeSection() override;
404   void emitLabel(MCSymbol *Symbol) override;
405 
406   void AnnotateTLSDescriptorSequence(const MCSymbolRefExpr *SRE) override;
407   void emitThumbSet(MCSymbol *Symbol, const MCExpr *Value) override;
408 
409   size_t calculateContentSize() const;
410 
411   // Reset state between object emissions
412   void reset() override;
413 
414 public:
415   ARMTargetELFStreamer(MCStreamer &S)
416     : ARMTargetStreamer(S), CurrentVendor("aeabi") {}
417 };
418 
419 /// Extend the generic ELFStreamer class so that it can emit mapping symbols at
420 /// the appropriate points in the object files. These symbols are defined in the
421 /// ARM ELF ABI: infocenter.arm.com/help/topic/com.arm.../IHI0044D_aaelf.pdf.
422 ///
423 /// In brief: $a, $t or $d should be emitted at the start of each contiguous
424 /// region of ARM code, Thumb code or data in a section. In practice, this
425 /// emission does not rely on explicit assembler directives but on inherent
426 /// properties of the directives doing the emission (e.g. ".byte" is data, "add
427 /// r0, r0, r0" an instruction).
428 ///
429 /// As a result this system is orthogonal to the DataRegion infrastructure used
430 /// by MachO. Beware!
431 class ARMELFStreamer : public MCELFStreamer {
432 public:
433   friend class ARMTargetELFStreamer;
434 
435   ARMELFStreamer(MCContext &Context, std::unique_ptr<MCAsmBackend> TAB,
436                  std::unique_ptr<MCObjectWriter> OW,
437                  std::unique_ptr<MCCodeEmitter> Emitter, bool IsThumb,
438                  bool IsAndroid)
439       : MCELFStreamer(Context, std::move(TAB), std::move(OW),
440                       std::move(Emitter)),
441         IsThumb(IsThumb), IsAndroid(IsAndroid) {
442     EHReset();
443   }
444 
445   ~ARMELFStreamer() override = default;
446 
447   void finishImpl() override;
448 
449   // ARM exception handling directives
450   void emitFnStart();
451   void emitFnEnd();
452   void emitCantUnwind();
453   void emitPersonality(const MCSymbol *Per);
454   void emitPersonalityIndex(unsigned index);
455   void emitHandlerData();
456   void emitSetFP(unsigned NewFpReg, unsigned NewSpReg, int64_t Offset = 0);
457   void emitMovSP(unsigned Reg, int64_t Offset = 0);
458   void emitPad(int64_t Offset);
459   void emitRegSave(const SmallVectorImpl<unsigned> &RegList, bool isVector);
460   void emitUnwindRaw(int64_t Offset, const SmallVectorImpl<uint8_t> &Opcodes);
461   void emitFill(const MCExpr &NumBytes, uint64_t FillValue,
462                 SMLoc Loc) override {
463     emitDataMappingSymbol();
464     MCObjectStreamer::emitFill(NumBytes, FillValue, Loc);
465   }
466 
467   void changeSection(MCSection *Section, const MCExpr *Subsection) override {
468     LastMappingSymbols[getCurrentSection().first] = std::move(LastEMSInfo);
469     MCELFStreamer::changeSection(Section, Subsection);
470     auto LastMappingSymbol = LastMappingSymbols.find(Section);
471     if (LastMappingSymbol != LastMappingSymbols.end()) {
472       LastEMSInfo = std::move(LastMappingSymbol->second);
473       return;
474     }
475     LastEMSInfo.reset(new ElfMappingSymbolInfo(SMLoc(), nullptr, 0));
476   }
477 
478   /// This function is the one used to emit instruction data into the ELF
479   /// streamer. We override it to add the appropriate mapping symbol if
480   /// necessary.
481   void emitInstruction(const MCInst &Inst,
482                        const MCSubtargetInfo &STI) override {
483     if (IsThumb)
484       EmitThumbMappingSymbol();
485     else
486       EmitARMMappingSymbol();
487 
488     MCELFStreamer::emitInstruction(Inst, STI);
489   }
490 
491   void emitInst(uint32_t Inst, char Suffix) {
492     unsigned Size;
493     char Buffer[4];
494     const bool LittleEndian = getContext().getAsmInfo()->isLittleEndian();
495 
496     switch (Suffix) {
497     case '\0':
498       Size = 4;
499 
500       assert(!IsThumb);
501       EmitARMMappingSymbol();
502       for (unsigned II = 0, IE = Size; II != IE; II++) {
503         const unsigned I = LittleEndian ? (Size - II - 1) : II;
504         Buffer[Size - II - 1] = uint8_t(Inst >> I * CHAR_BIT);
505       }
506 
507       break;
508     case 'n':
509     case 'w':
510       Size = (Suffix == 'n' ? 2 : 4);
511 
512       assert(IsThumb);
513       EmitThumbMappingSymbol();
514       // Thumb wide instructions are emitted as a pair of 16-bit words of the
515       // appropriate endianness.
516       for (unsigned II = 0, IE = Size; II != IE; II = II + 2) {
517         const unsigned I0 = LittleEndian ? II + 0 : II + 1;
518         const unsigned I1 = LittleEndian ? II + 1 : II + 0;
519         Buffer[Size - II - 2] = uint8_t(Inst >> I0 * CHAR_BIT);
520         Buffer[Size - II - 1] = uint8_t(Inst >> I1 * CHAR_BIT);
521       }
522 
523       break;
524     default:
525       llvm_unreachable("Invalid Suffix");
526     }
527 
528     MCELFStreamer::emitBytes(StringRef(Buffer, Size));
529   }
530 
531   /// This is one of the functions used to emit data into an ELF section, so the
532   /// ARM streamer overrides it to add the appropriate mapping symbol ($d) if
533   /// necessary.
534   void emitBytes(StringRef Data) override {
535     emitDataMappingSymbol();
536     MCELFStreamer::emitBytes(Data);
537   }
538 
539   void FlushPendingMappingSymbol() {
540     if (!LastEMSInfo->hasInfo())
541       return;
542     ElfMappingSymbolInfo *EMS = LastEMSInfo.get();
543     EmitMappingSymbol("$d", EMS->Loc, EMS->F, EMS->Offset);
544     EMS->resetInfo();
545   }
546 
547   /// This is one of the functions used to emit data into an ELF section, so the
548   /// ARM streamer overrides it to add the appropriate mapping symbol ($d) if
549   /// necessary.
550   void emitValueImpl(const MCExpr *Value, unsigned Size, SMLoc Loc) override {
551     if (const MCSymbolRefExpr *SRE = dyn_cast_or_null<MCSymbolRefExpr>(Value)) {
552       if (SRE->getKind() == MCSymbolRefExpr::VK_ARM_SBREL && !(Size == 4)) {
553         getContext().reportError(Loc, "relocated expression must be 32-bit");
554         return;
555       }
556       getOrCreateDataFragment();
557     }
558 
559     emitDataMappingSymbol();
560     MCELFStreamer::emitValueImpl(Value, Size, Loc);
561   }
562 
563   void emitAssemblerFlag(MCAssemblerFlag Flag) override {
564     MCELFStreamer::emitAssemblerFlag(Flag);
565 
566     switch (Flag) {
567     case MCAF_SyntaxUnified:
568       return; // no-op here.
569     case MCAF_Code16:
570       IsThumb = true;
571       return; // Change to Thumb mode
572     case MCAF_Code32:
573       IsThumb = false;
574       return; // Change to ARM mode
575     case MCAF_Code64:
576       return;
577     case MCAF_SubsectionsViaSymbols:
578       return;
579     }
580   }
581 
582   /// If a label is defined before the .type directive sets the label's type
583   /// then the label can't be recorded as thumb function when the label is
584   /// defined. We override emitSymbolAttribute() which is called as part of the
585   /// parsing of .type so that if the symbol has already been defined we can
586   /// record the label as Thumb. FIXME: there is a corner case where the state
587   /// is changed in between the label definition and the .type directive, this
588   /// is not expected to occur in practice and handling it would require the
589   /// backend to track IsThumb for every label.
590   bool emitSymbolAttribute(MCSymbol *Symbol, MCSymbolAttr Attribute) override {
591     bool Val = MCELFStreamer::emitSymbolAttribute(Symbol, Attribute);
592 
593     if (!IsThumb)
594       return Val;
595 
596     unsigned Type = cast<MCSymbolELF>(Symbol)->getType();
597     if ((Type == ELF::STT_FUNC || Type == ELF::STT_GNU_IFUNC) &&
598         Symbol->isDefined())
599       getAssembler().setIsThumbFunc(Symbol);
600 
601     return Val;
602   };
603 
604 private:
605   enum ElfMappingSymbol {
606     EMS_None,
607     EMS_ARM,
608     EMS_Thumb,
609     EMS_Data
610   };
611 
612   struct ElfMappingSymbolInfo {
613     explicit ElfMappingSymbolInfo(SMLoc Loc, MCFragment *F, uint64_t O)
614         : Loc(Loc), F(F), Offset(O), State(EMS_None) {}
615     void resetInfo() {
616       F = nullptr;
617       Offset = 0;
618     }
619     bool hasInfo() { return F != nullptr; }
620     SMLoc Loc;
621     MCFragment *F;
622     uint64_t Offset;
623     ElfMappingSymbol State;
624   };
625 
626   void emitDataMappingSymbol() {
627     if (LastEMSInfo->State == EMS_Data)
628       return;
629     else if (LastEMSInfo->State == EMS_None) {
630       // This is a tentative symbol, it won't really be emitted until it's
631       // actually needed.
632       ElfMappingSymbolInfo *EMS = LastEMSInfo.get();
633       auto *DF = dyn_cast_or_null<MCDataFragment>(getCurrentFragment());
634       if (!DF)
635         return;
636       EMS->Loc = SMLoc();
637       EMS->F = getCurrentFragment();
638       EMS->Offset = DF->getContents().size();
639       LastEMSInfo->State = EMS_Data;
640       return;
641     }
642     EmitMappingSymbol("$d");
643     LastEMSInfo->State = EMS_Data;
644   }
645 
646   void EmitThumbMappingSymbol() {
647     if (LastEMSInfo->State == EMS_Thumb)
648       return;
649     FlushPendingMappingSymbol();
650     EmitMappingSymbol("$t");
651     LastEMSInfo->State = EMS_Thumb;
652   }
653 
654   void EmitARMMappingSymbol() {
655     if (LastEMSInfo->State == EMS_ARM)
656       return;
657     FlushPendingMappingSymbol();
658     EmitMappingSymbol("$a");
659     LastEMSInfo->State = EMS_ARM;
660   }
661 
662   void EmitMappingSymbol(StringRef Name) {
663     auto *Symbol = cast<MCSymbolELF>(getContext().getOrCreateSymbol(
664         Name + "." + Twine(MappingSymbolCounter++)));
665     emitLabel(Symbol);
666 
667     Symbol->setType(ELF::STT_NOTYPE);
668     Symbol->setBinding(ELF::STB_LOCAL);
669   }
670 
671   void EmitMappingSymbol(StringRef Name, SMLoc Loc, MCFragment *F,
672                          uint64_t Offset) {
673     auto *Symbol = cast<MCSymbolELF>(getContext().getOrCreateSymbol(
674         Name + "." + Twine(MappingSymbolCounter++)));
675     emitLabelAtPos(Symbol, Loc, F, Offset);
676     Symbol->setType(ELF::STT_NOTYPE);
677     Symbol->setBinding(ELF::STB_LOCAL);
678   }
679 
680   void emitThumbFunc(MCSymbol *Func) override {
681     getAssembler().setIsThumbFunc(Func);
682     emitSymbolAttribute(Func, MCSA_ELF_TypeFunction);
683   }
684 
685   // Helper functions for ARM exception handling directives
686   void EHReset();
687 
688   // Reset state between object emissions
689   void reset() override;
690 
691   void EmitPersonalityFixup(StringRef Name);
692   void FlushPendingOffset();
693   void FlushUnwindOpcodes(bool NoHandlerData);
694 
695   void SwitchToEHSection(StringRef Prefix, unsigned Type, unsigned Flags,
696                          SectionKind Kind, const MCSymbol &Fn);
697   void SwitchToExTabSection(const MCSymbol &FnStart);
698   void SwitchToExIdxSection(const MCSymbol &FnStart);
699 
700   void EmitFixup(const MCExpr *Expr, MCFixupKind Kind);
701 
702   bool IsThumb;
703   bool IsAndroid;
704   int64_t MappingSymbolCounter = 0;
705 
706   DenseMap<const MCSection *, std::unique_ptr<ElfMappingSymbolInfo>>
707       LastMappingSymbols;
708 
709   std::unique_ptr<ElfMappingSymbolInfo> LastEMSInfo;
710 
711   // ARM Exception Handling Frame Information
712   MCSymbol *ExTab;
713   MCSymbol *FnStart;
714   const MCSymbol *Personality;
715   unsigned PersonalityIndex;
716   unsigned FPReg; // Frame pointer register
717   int64_t FPOffset; // Offset: (final frame pointer) - (initial $sp)
718   int64_t SPOffset; // Offset: (final $sp) - (initial $sp)
719   int64_t PendingOffset; // Offset: (final $sp) - (emitted $sp)
720   bool UsedFP;
721   bool CantUnwind;
722   SmallVector<uint8_t, 64> Opcodes;
723   UnwindOpcodeAssembler UnwindOpAsm;
724 };
725 
726 } // end anonymous namespace
727 
728 ARMELFStreamer &ARMTargetELFStreamer::getStreamer() {
729   return static_cast<ARMELFStreamer &>(Streamer);
730 }
731 
732 void ARMTargetELFStreamer::emitFnStart() { getStreamer().emitFnStart(); }
733 void ARMTargetELFStreamer::emitFnEnd() { getStreamer().emitFnEnd(); }
734 void ARMTargetELFStreamer::emitCantUnwind() { getStreamer().emitCantUnwind(); }
735 
736 void ARMTargetELFStreamer::emitPersonality(const MCSymbol *Personality) {
737   getStreamer().emitPersonality(Personality);
738 }
739 
740 void ARMTargetELFStreamer::emitPersonalityIndex(unsigned Index) {
741   getStreamer().emitPersonalityIndex(Index);
742 }
743 
744 void ARMTargetELFStreamer::emitHandlerData() {
745   getStreamer().emitHandlerData();
746 }
747 
748 void ARMTargetELFStreamer::emitSetFP(unsigned FpReg, unsigned SpReg,
749                                      int64_t Offset) {
750   getStreamer().emitSetFP(FpReg, SpReg, Offset);
751 }
752 
753 void ARMTargetELFStreamer::emitMovSP(unsigned Reg, int64_t Offset) {
754   getStreamer().emitMovSP(Reg, Offset);
755 }
756 
757 void ARMTargetELFStreamer::emitPad(int64_t Offset) {
758   getStreamer().emitPad(Offset);
759 }
760 
761 void ARMTargetELFStreamer::emitRegSave(const SmallVectorImpl<unsigned> &RegList,
762                                        bool isVector) {
763   getStreamer().emitRegSave(RegList, isVector);
764 }
765 
766 void ARMTargetELFStreamer::emitUnwindRaw(int64_t Offset,
767                                       const SmallVectorImpl<uint8_t> &Opcodes) {
768   getStreamer().emitUnwindRaw(Offset, Opcodes);
769 }
770 
771 void ARMTargetELFStreamer::switchVendor(StringRef Vendor) {
772   assert(!Vendor.empty() && "Vendor cannot be empty.");
773 
774   if (CurrentVendor == Vendor)
775     return;
776 
777   if (!CurrentVendor.empty())
778     finishAttributeSection();
779 
780   assert(Contents.empty() &&
781          ".ARM.attributes should be flushed before changing vendor");
782   CurrentVendor = Vendor;
783 
784 }
785 
786 void ARMTargetELFStreamer::emitAttribute(unsigned Attribute, unsigned Value) {
787   setAttributeItem(Attribute, Value, /* OverwriteExisting= */ true);
788 }
789 
790 void ARMTargetELFStreamer::emitTextAttribute(unsigned Attribute,
791                                              StringRef Value) {
792   setAttributeItem(Attribute, Value, /* OverwriteExisting= */ true);
793 }
794 
795 void ARMTargetELFStreamer::emitIntTextAttribute(unsigned Attribute,
796                                                 unsigned IntValue,
797                                                 StringRef StringValue) {
798   setAttributeItems(Attribute, IntValue, StringValue,
799                     /* OverwriteExisting= */ true);
800 }
801 
802 void ARMTargetELFStreamer::emitArch(ARM::ArchKind Value) {
803   Arch = Value;
804 }
805 
806 void ARMTargetELFStreamer::emitObjectArch(ARM::ArchKind Value) {
807   EmittedArch = Value;
808 }
809 
810 void ARMTargetELFStreamer::emitArchDefaultAttributes() {
811   using namespace ARMBuildAttrs;
812 
813   setAttributeItem(CPU_name,
814                    ARM::getCPUAttr(Arch),
815                    false);
816 
817   if (EmittedArch == ARM::ArchKind::INVALID)
818     setAttributeItem(CPU_arch,
819                      ARM::getArchAttr(Arch),
820                      false);
821   else
822     setAttributeItem(CPU_arch,
823                      ARM::getArchAttr(EmittedArch),
824                      false);
825 
826   switch (Arch) {
827   case ARM::ArchKind::ARMV2:
828   case ARM::ArchKind::ARMV2A:
829   case ARM::ArchKind::ARMV3:
830   case ARM::ArchKind::ARMV3M:
831   case ARM::ArchKind::ARMV4:
832     setAttributeItem(ARM_ISA_use, Allowed, false);
833     break;
834 
835   case ARM::ArchKind::ARMV4T:
836   case ARM::ArchKind::ARMV5T:
837   case ARM::ArchKind::ARMV5TE:
838   case ARM::ArchKind::ARMV6:
839     setAttributeItem(ARM_ISA_use, Allowed, false);
840     setAttributeItem(THUMB_ISA_use, Allowed, false);
841     break;
842 
843   case ARM::ArchKind::ARMV6T2:
844     setAttributeItem(ARM_ISA_use, Allowed, false);
845     setAttributeItem(THUMB_ISA_use, AllowThumb32, false);
846     break;
847 
848   case ARM::ArchKind::ARMV6K:
849   case ARM::ArchKind::ARMV6KZ:
850     setAttributeItem(ARM_ISA_use, Allowed, false);
851     setAttributeItem(THUMB_ISA_use, Allowed, false);
852     setAttributeItem(Virtualization_use, AllowTZ, false);
853     break;
854 
855   case ARM::ArchKind::ARMV6M:
856     setAttributeItem(THUMB_ISA_use, Allowed, false);
857     break;
858 
859   case ARM::ArchKind::ARMV7A:
860     setAttributeItem(CPU_arch_profile, ApplicationProfile, false);
861     setAttributeItem(ARM_ISA_use, Allowed, false);
862     setAttributeItem(THUMB_ISA_use, AllowThumb32, false);
863     break;
864 
865   case ARM::ArchKind::ARMV7R:
866     setAttributeItem(CPU_arch_profile, RealTimeProfile, false);
867     setAttributeItem(ARM_ISA_use, Allowed, false);
868     setAttributeItem(THUMB_ISA_use, AllowThumb32, false);
869     break;
870 
871   case ARM::ArchKind::ARMV7EM:
872   case ARM::ArchKind::ARMV7M:
873     setAttributeItem(CPU_arch_profile, MicroControllerProfile, false);
874     setAttributeItem(THUMB_ISA_use, AllowThumb32, false);
875     break;
876 
877   case ARM::ArchKind::ARMV8A:
878   case ARM::ArchKind::ARMV8_1A:
879   case ARM::ArchKind::ARMV8_2A:
880   case ARM::ArchKind::ARMV8_3A:
881   case ARM::ArchKind::ARMV8_4A:
882   case ARM::ArchKind::ARMV8_5A:
883   case ARM::ArchKind::ARMV8_6A:
884     setAttributeItem(CPU_arch_profile, ApplicationProfile, false);
885     setAttributeItem(ARM_ISA_use, Allowed, false);
886     setAttributeItem(THUMB_ISA_use, AllowThumb32, false);
887     setAttributeItem(MPextension_use, Allowed, false);
888     setAttributeItem(Virtualization_use, AllowTZVirtualization, false);
889     break;
890 
891   case ARM::ArchKind::ARMV8MBaseline:
892   case ARM::ArchKind::ARMV8MMainline:
893     setAttributeItem(THUMB_ISA_use, AllowThumbDerived, false);
894     setAttributeItem(CPU_arch_profile, MicroControllerProfile, false);
895     break;
896 
897   case ARM::ArchKind::IWMMXT:
898     setAttributeItem(ARM_ISA_use, Allowed, false);
899     setAttributeItem(THUMB_ISA_use, Allowed, false);
900     setAttributeItem(WMMX_arch, AllowWMMXv1, false);
901     break;
902 
903   case ARM::ArchKind::IWMMXT2:
904     setAttributeItem(ARM_ISA_use, Allowed, false);
905     setAttributeItem(THUMB_ISA_use, Allowed, false);
906     setAttributeItem(WMMX_arch, AllowWMMXv2, false);
907     break;
908 
909   default:
910     report_fatal_error("Unknown Arch: " + Twine(ARM::getArchName(Arch)));
911     break;
912   }
913 }
914 
915 void ARMTargetELFStreamer::emitFPU(unsigned Value) {
916   FPU = Value;
917 }
918 
919 void ARMTargetELFStreamer::emitFPUDefaultAttributes() {
920   switch (FPU) {
921   case ARM::FK_VFP:
922   case ARM::FK_VFPV2:
923     setAttributeItem(ARMBuildAttrs::FP_arch,
924                      ARMBuildAttrs::AllowFPv2,
925                      /* OverwriteExisting= */ false);
926     break;
927 
928   case ARM::FK_VFPV3:
929     setAttributeItem(ARMBuildAttrs::FP_arch,
930                      ARMBuildAttrs::AllowFPv3A,
931                      /* OverwriteExisting= */ false);
932     break;
933 
934   case ARM::FK_VFPV3_FP16:
935     setAttributeItem(ARMBuildAttrs::FP_arch,
936                      ARMBuildAttrs::AllowFPv3A,
937                      /* OverwriteExisting= */ false);
938     setAttributeItem(ARMBuildAttrs::FP_HP_extension,
939                      ARMBuildAttrs::AllowHPFP,
940                      /* OverwriteExisting= */ false);
941     break;
942 
943   case ARM::FK_VFPV3_D16:
944     setAttributeItem(ARMBuildAttrs::FP_arch,
945                      ARMBuildAttrs::AllowFPv3B,
946                      /* OverwriteExisting= */ false);
947     break;
948 
949   case ARM::FK_VFPV3_D16_FP16:
950     setAttributeItem(ARMBuildAttrs::FP_arch,
951                      ARMBuildAttrs::AllowFPv3B,
952                      /* OverwriteExisting= */ false);
953     setAttributeItem(ARMBuildAttrs::FP_HP_extension,
954                      ARMBuildAttrs::AllowHPFP,
955                      /* OverwriteExisting= */ false);
956     break;
957 
958   case ARM::FK_VFPV3XD:
959     setAttributeItem(ARMBuildAttrs::FP_arch,
960                      ARMBuildAttrs::AllowFPv3B,
961                      /* OverwriteExisting= */ false);
962     break;
963   case ARM::FK_VFPV3XD_FP16:
964     setAttributeItem(ARMBuildAttrs::FP_arch,
965                      ARMBuildAttrs::AllowFPv3B,
966                      /* OverwriteExisting= */ false);
967     setAttributeItem(ARMBuildAttrs::FP_HP_extension,
968                      ARMBuildAttrs::AllowHPFP,
969                      /* OverwriteExisting= */ false);
970     break;
971 
972   case ARM::FK_VFPV4:
973     setAttributeItem(ARMBuildAttrs::FP_arch,
974                      ARMBuildAttrs::AllowFPv4A,
975                      /* OverwriteExisting= */ false);
976     break;
977 
978   // ABI_HardFP_use is handled in ARMAsmPrinter, so _SP_D16 is treated the same
979   // as _D16 here.
980   case ARM::FK_FPV4_SP_D16:
981   case ARM::FK_VFPV4_D16:
982     setAttributeItem(ARMBuildAttrs::FP_arch,
983                      ARMBuildAttrs::AllowFPv4B,
984                      /* OverwriteExisting= */ false);
985     break;
986 
987   case ARM::FK_FP_ARMV8:
988     setAttributeItem(ARMBuildAttrs::FP_arch,
989                      ARMBuildAttrs::AllowFPARMv8A,
990                      /* OverwriteExisting= */ false);
991     break;
992 
993   // FPV5_D16 is identical to FP_ARMV8 except for the number of D registers, so
994   // uses the FP_ARMV8_D16 build attribute.
995   case ARM::FK_FPV5_SP_D16:
996   case ARM::FK_FPV5_D16:
997     setAttributeItem(ARMBuildAttrs::FP_arch,
998                      ARMBuildAttrs::AllowFPARMv8B,
999                      /* OverwriteExisting= */ false);
1000     break;
1001 
1002   case ARM::FK_NEON:
1003     setAttributeItem(ARMBuildAttrs::FP_arch,
1004                      ARMBuildAttrs::AllowFPv3A,
1005                      /* OverwriteExisting= */ false);
1006     setAttributeItem(ARMBuildAttrs::Advanced_SIMD_arch,
1007                      ARMBuildAttrs::AllowNeon,
1008                      /* OverwriteExisting= */ false);
1009     break;
1010 
1011   case ARM::FK_NEON_FP16:
1012     setAttributeItem(ARMBuildAttrs::FP_arch,
1013                      ARMBuildAttrs::AllowFPv3A,
1014                      /* OverwriteExisting= */ false);
1015     setAttributeItem(ARMBuildAttrs::Advanced_SIMD_arch,
1016                      ARMBuildAttrs::AllowNeon,
1017                      /* OverwriteExisting= */ false);
1018     setAttributeItem(ARMBuildAttrs::FP_HP_extension,
1019                      ARMBuildAttrs::AllowHPFP,
1020                      /* OverwriteExisting= */ false);
1021     break;
1022 
1023   case ARM::FK_NEON_VFPV4:
1024     setAttributeItem(ARMBuildAttrs::FP_arch,
1025                      ARMBuildAttrs::AllowFPv4A,
1026                      /* OverwriteExisting= */ false);
1027     setAttributeItem(ARMBuildAttrs::Advanced_SIMD_arch,
1028                      ARMBuildAttrs::AllowNeon2,
1029                      /* OverwriteExisting= */ false);
1030     break;
1031 
1032   case ARM::FK_NEON_FP_ARMV8:
1033   case ARM::FK_CRYPTO_NEON_FP_ARMV8:
1034     setAttributeItem(ARMBuildAttrs::FP_arch,
1035                      ARMBuildAttrs::AllowFPARMv8A,
1036                      /* OverwriteExisting= */ false);
1037     // 'Advanced_SIMD_arch' must be emitted not here, but within
1038     // ARMAsmPrinter::emitAttributes(), depending on hasV8Ops() and hasV8_1a()
1039     break;
1040 
1041   case ARM::FK_SOFTVFP:
1042   case ARM::FK_NONE:
1043     break;
1044 
1045   default:
1046     report_fatal_error("Unknown FPU: " + Twine(FPU));
1047     break;
1048   }
1049 }
1050 
1051 size_t ARMTargetELFStreamer::calculateContentSize() const {
1052   size_t Result = 0;
1053   for (size_t i = 0; i < Contents.size(); ++i) {
1054     AttributeItem item = Contents[i];
1055     switch (item.Type) {
1056     case AttributeItem::HiddenAttribute:
1057       break;
1058     case AttributeItem::NumericAttribute:
1059       Result += getULEB128Size(item.Tag);
1060       Result += getULEB128Size(item.IntValue);
1061       break;
1062     case AttributeItem::TextAttribute:
1063       Result += getULEB128Size(item.Tag);
1064       Result += item.StringValue.size() + 1; // string + '\0'
1065       break;
1066     case AttributeItem::NumericAndTextAttributes:
1067       Result += getULEB128Size(item.Tag);
1068       Result += getULEB128Size(item.IntValue);
1069       Result += item.StringValue.size() + 1; // string + '\0';
1070       break;
1071     }
1072   }
1073   return Result;
1074 }
1075 
1076 void ARMTargetELFStreamer::finishAttributeSection() {
1077   // <format-version>
1078   // [ <section-length> "vendor-name"
1079   // [ <file-tag> <size> <attribute>*
1080   //   | <section-tag> <size> <section-number>* 0 <attribute>*
1081   //   | <symbol-tag> <size> <symbol-number>* 0 <attribute>*
1082   //   ]+
1083   // ]*
1084 
1085   if (FPU != ARM::FK_INVALID)
1086     emitFPUDefaultAttributes();
1087 
1088   if (Arch != ARM::ArchKind::INVALID)
1089     emitArchDefaultAttributes();
1090 
1091   if (Contents.empty())
1092     return;
1093 
1094   llvm::sort(Contents, AttributeItem::LessTag);
1095 
1096   ARMELFStreamer &Streamer = getStreamer();
1097 
1098   // Switch to .ARM.attributes section
1099   if (AttributeSection) {
1100     Streamer.SwitchSection(AttributeSection);
1101   } else {
1102     AttributeSection = Streamer.getContext().getELFSection(
1103         ".ARM.attributes", ELF::SHT_ARM_ATTRIBUTES, 0);
1104     Streamer.SwitchSection(AttributeSection);
1105 
1106     // Format version
1107     Streamer.emitInt8(0x41);
1108   }
1109 
1110   // Vendor size + Vendor name + '\0'
1111   const size_t VendorHeaderSize = 4 + CurrentVendor.size() + 1;
1112 
1113   // Tag + Tag Size
1114   const size_t TagHeaderSize = 1 + 4;
1115 
1116   const size_t ContentsSize = calculateContentSize();
1117 
1118   Streamer.emitInt32(VendorHeaderSize + TagHeaderSize + ContentsSize);
1119   Streamer.emitBytes(CurrentVendor);
1120   Streamer.emitInt8(0); // '\0'
1121 
1122   Streamer.emitInt8(ARMBuildAttrs::File);
1123   Streamer.emitInt32(TagHeaderSize + ContentsSize);
1124 
1125   // Size should have been accounted for already, now
1126   // emit each field as its type (ULEB or String)
1127   for (size_t i = 0; i < Contents.size(); ++i) {
1128     AttributeItem item = Contents[i];
1129     Streamer.emitULEB128IntValue(item.Tag);
1130     switch (item.Type) {
1131     default: llvm_unreachable("Invalid attribute type");
1132     case AttributeItem::NumericAttribute:
1133       Streamer.emitULEB128IntValue(item.IntValue);
1134       break;
1135     case AttributeItem::TextAttribute:
1136       Streamer.emitBytes(item.StringValue);
1137       Streamer.emitInt8(0); // '\0'
1138       break;
1139     case AttributeItem::NumericAndTextAttributes:
1140       Streamer.emitULEB128IntValue(item.IntValue);
1141       Streamer.emitBytes(item.StringValue);
1142       Streamer.emitInt8(0); // '\0'
1143       break;
1144     }
1145   }
1146 
1147   Contents.clear();
1148   FPU = ARM::FK_INVALID;
1149 }
1150 
1151 void ARMTargetELFStreamer::emitLabel(MCSymbol *Symbol) {
1152   ARMELFStreamer &Streamer = getStreamer();
1153   if (!Streamer.IsThumb)
1154     return;
1155 
1156   Streamer.getAssembler().registerSymbol(*Symbol);
1157   unsigned Type = cast<MCSymbolELF>(Symbol)->getType();
1158   if (Type == ELF::STT_FUNC || Type == ELF::STT_GNU_IFUNC)
1159     Streamer.emitThumbFunc(Symbol);
1160 }
1161 
1162 void
1163 ARMTargetELFStreamer::AnnotateTLSDescriptorSequence(const MCSymbolRefExpr *S) {
1164   getStreamer().EmitFixup(S, FK_Data_4);
1165 }
1166 
1167 void ARMTargetELFStreamer::emitThumbSet(MCSymbol *Symbol, const MCExpr *Value) {
1168   if (const MCSymbolRefExpr *SRE = dyn_cast<MCSymbolRefExpr>(Value)) {
1169     const MCSymbol &Sym = SRE->getSymbol();
1170     if (!Sym.isDefined()) {
1171       getStreamer().emitAssignment(Symbol, Value);
1172       return;
1173     }
1174   }
1175 
1176   getStreamer().emitThumbFunc(Symbol);
1177   getStreamer().emitAssignment(Symbol, Value);
1178 }
1179 
1180 void ARMTargetELFStreamer::emitInst(uint32_t Inst, char Suffix) {
1181   getStreamer().emitInst(Inst, Suffix);
1182 }
1183 
1184 void ARMTargetELFStreamer::reset() { AttributeSection = nullptr; }
1185 
1186 void ARMELFStreamer::finishImpl() {
1187   MCTargetStreamer &TS = *getTargetStreamer();
1188   ARMTargetStreamer &ATS = static_cast<ARMTargetStreamer &>(TS);
1189   ATS.finishAttributeSection();
1190 
1191   MCELFStreamer::finishImpl();
1192 }
1193 
1194 void ARMELFStreamer::reset() {
1195   MCTargetStreamer &TS = *getTargetStreamer();
1196   ARMTargetStreamer &ATS = static_cast<ARMTargetStreamer &>(TS);
1197   ATS.reset();
1198   MappingSymbolCounter = 0;
1199   MCELFStreamer::reset();
1200   LastMappingSymbols.clear();
1201   LastEMSInfo.reset();
1202   // MCELFStreamer clear's the assembler's e_flags. However, for
1203   // arm we manually set the ABI version on streamer creation, so
1204   // do the same here
1205   getAssembler().setELFHeaderEFlags(ELF::EF_ARM_EABI_VER5);
1206 }
1207 
1208 inline void ARMELFStreamer::SwitchToEHSection(StringRef Prefix,
1209                                               unsigned Type,
1210                                               unsigned Flags,
1211                                               SectionKind Kind,
1212                                               const MCSymbol &Fn) {
1213   const MCSectionELF &FnSection =
1214     static_cast<const MCSectionELF &>(Fn.getSection());
1215 
1216   // Create the name for new section
1217   StringRef FnSecName(FnSection.getName());
1218   SmallString<128> EHSecName(Prefix);
1219   if (FnSecName != ".text") {
1220     EHSecName += FnSecName;
1221   }
1222 
1223   // Get .ARM.extab or .ARM.exidx section
1224   const MCSymbolELF *Group = FnSection.getGroup();
1225   if (Group)
1226     Flags |= ELF::SHF_GROUP;
1227   MCSectionELF *EHSection = getContext().getELFSection(
1228       EHSecName, Type, Flags, 0, Group, /*IsComdat=*/true,
1229       FnSection.getUniqueID(),
1230       static_cast<const MCSymbolELF *>(FnSection.getBeginSymbol()));
1231 
1232   assert(EHSection && "Failed to get the required EH section");
1233 
1234   // Switch to .ARM.extab or .ARM.exidx section
1235   SwitchSection(EHSection);
1236   emitCodeAlignment(4);
1237 }
1238 
1239 inline void ARMELFStreamer::SwitchToExTabSection(const MCSymbol &FnStart) {
1240   SwitchToEHSection(".ARM.extab", ELF::SHT_PROGBITS, ELF::SHF_ALLOC,
1241                     SectionKind::getData(), FnStart);
1242 }
1243 
1244 inline void ARMELFStreamer::SwitchToExIdxSection(const MCSymbol &FnStart) {
1245   SwitchToEHSection(".ARM.exidx", ELF::SHT_ARM_EXIDX,
1246                     ELF::SHF_ALLOC | ELF::SHF_LINK_ORDER,
1247                     SectionKind::getData(), FnStart);
1248 }
1249 
1250 void ARMELFStreamer::EmitFixup(const MCExpr *Expr, MCFixupKind Kind) {
1251   MCDataFragment *Frag = getOrCreateDataFragment();
1252   Frag->getFixups().push_back(MCFixup::create(Frag->getContents().size(), Expr,
1253                                               Kind));
1254 }
1255 
1256 void ARMELFStreamer::EHReset() {
1257   ExTab = nullptr;
1258   FnStart = nullptr;
1259   Personality = nullptr;
1260   PersonalityIndex = ARM::EHABI::NUM_PERSONALITY_INDEX;
1261   FPReg = ARM::SP;
1262   FPOffset = 0;
1263   SPOffset = 0;
1264   PendingOffset = 0;
1265   UsedFP = false;
1266   CantUnwind = false;
1267 
1268   Opcodes.clear();
1269   UnwindOpAsm.Reset();
1270 }
1271 
1272 void ARMELFStreamer::emitFnStart() {
1273   assert(FnStart == nullptr);
1274   FnStart = getContext().createTempSymbol();
1275   emitLabel(FnStart);
1276 }
1277 
1278 void ARMELFStreamer::emitFnEnd() {
1279   assert(FnStart && ".fnstart must precedes .fnend");
1280 
1281   // Emit unwind opcodes if there is no .handlerdata directive
1282   if (!ExTab && !CantUnwind)
1283     FlushUnwindOpcodes(true);
1284 
1285   // Emit the exception index table entry
1286   SwitchToExIdxSection(*FnStart);
1287 
1288   // The EHABI requires a dependency preserving R_ARM_NONE relocation to the
1289   // personality routine to protect it from an arbitrary platform's static
1290   // linker garbage collection. We disable this for Android where the unwinder
1291   // is either dynamically linked or directly references the personality
1292   // routine.
1293   if (PersonalityIndex < ARM::EHABI::NUM_PERSONALITY_INDEX && !IsAndroid)
1294     EmitPersonalityFixup(GetAEABIUnwindPersonalityName(PersonalityIndex));
1295 
1296   const MCSymbolRefExpr *FnStartRef =
1297     MCSymbolRefExpr::create(FnStart,
1298                             MCSymbolRefExpr::VK_ARM_PREL31,
1299                             getContext());
1300 
1301   emitValue(FnStartRef, 4);
1302 
1303   if (CantUnwind) {
1304     emitInt32(ARM::EHABI::EXIDX_CANTUNWIND);
1305   } else if (ExTab) {
1306     // Emit a reference to the unwind opcodes in the ".ARM.extab" section.
1307     const MCSymbolRefExpr *ExTabEntryRef =
1308       MCSymbolRefExpr::create(ExTab,
1309                               MCSymbolRefExpr::VK_ARM_PREL31,
1310                               getContext());
1311     emitValue(ExTabEntryRef, 4);
1312   } else {
1313     // For the __aeabi_unwind_cpp_pr0, we have to emit the unwind opcodes in
1314     // the second word of exception index table entry.  The size of the unwind
1315     // opcodes should always be 4 bytes.
1316     assert(PersonalityIndex == ARM::EHABI::AEABI_UNWIND_CPP_PR0 &&
1317            "Compact model must use __aeabi_unwind_cpp_pr0 as personality");
1318     assert(Opcodes.size() == 4u &&
1319            "Unwind opcode size for __aeabi_unwind_cpp_pr0 must be equal to 4");
1320     uint64_t Intval = Opcodes[0] |
1321                       Opcodes[1] << 8 |
1322                       Opcodes[2] << 16 |
1323                       Opcodes[3] << 24;
1324     emitIntValue(Intval, Opcodes.size());
1325   }
1326 
1327   // Switch to the section containing FnStart
1328   SwitchSection(&FnStart->getSection());
1329 
1330   // Clean exception handling frame information
1331   EHReset();
1332 }
1333 
1334 void ARMELFStreamer::emitCantUnwind() { CantUnwind = true; }
1335 
1336 // Add the R_ARM_NONE fixup at the same position
1337 void ARMELFStreamer::EmitPersonalityFixup(StringRef Name) {
1338   const MCSymbol *PersonalitySym = getContext().getOrCreateSymbol(Name);
1339 
1340   const MCSymbolRefExpr *PersonalityRef = MCSymbolRefExpr::create(
1341       PersonalitySym, MCSymbolRefExpr::VK_ARM_NONE, getContext());
1342 
1343   visitUsedExpr(*PersonalityRef);
1344   MCDataFragment *DF = getOrCreateDataFragment();
1345   DF->getFixups().push_back(MCFixup::create(DF->getContents().size(),
1346                                             PersonalityRef,
1347                                             MCFixup::getKindForSize(4, false)));
1348 }
1349 
1350 void ARMELFStreamer::FlushPendingOffset() {
1351   if (PendingOffset != 0) {
1352     UnwindOpAsm.EmitSPOffset(-PendingOffset);
1353     PendingOffset = 0;
1354   }
1355 }
1356 
1357 void ARMELFStreamer::FlushUnwindOpcodes(bool NoHandlerData) {
1358   // Emit the unwind opcode to restore $sp.
1359   if (UsedFP) {
1360     const MCRegisterInfo *MRI = getContext().getRegisterInfo();
1361     int64_t LastRegSaveSPOffset = SPOffset - PendingOffset;
1362     UnwindOpAsm.EmitSPOffset(LastRegSaveSPOffset - FPOffset);
1363     UnwindOpAsm.EmitSetSP(MRI->getEncodingValue(FPReg));
1364   } else {
1365     FlushPendingOffset();
1366   }
1367 
1368   // Finalize the unwind opcode sequence
1369   UnwindOpAsm.Finalize(PersonalityIndex, Opcodes);
1370 
1371   // For compact model 0, we have to emit the unwind opcodes in the .ARM.exidx
1372   // section.  Thus, we don't have to create an entry in the .ARM.extab
1373   // section.
1374   if (NoHandlerData && PersonalityIndex == ARM::EHABI::AEABI_UNWIND_CPP_PR0)
1375     return;
1376 
1377   // Switch to .ARM.extab section.
1378   SwitchToExTabSection(*FnStart);
1379 
1380   // Create .ARM.extab label for offset in .ARM.exidx
1381   assert(!ExTab);
1382   ExTab = getContext().createTempSymbol();
1383   emitLabel(ExTab);
1384 
1385   // Emit personality
1386   if (Personality) {
1387     const MCSymbolRefExpr *PersonalityRef =
1388       MCSymbolRefExpr::create(Personality,
1389                               MCSymbolRefExpr::VK_ARM_PREL31,
1390                               getContext());
1391 
1392     emitValue(PersonalityRef, 4);
1393   }
1394 
1395   // Emit unwind opcodes
1396   assert((Opcodes.size() % 4) == 0 &&
1397          "Unwind opcode size for __aeabi_cpp_unwind_pr0 must be multiple of 4");
1398   for (unsigned I = 0; I != Opcodes.size(); I += 4) {
1399     uint64_t Intval = Opcodes[I] |
1400                       Opcodes[I + 1] << 8 |
1401                       Opcodes[I + 2] << 16 |
1402                       Opcodes[I + 3] << 24;
1403     emitInt32(Intval);
1404   }
1405 
1406   // According to ARM EHABI section 9.2, if the __aeabi_unwind_cpp_pr1() or
1407   // __aeabi_unwind_cpp_pr2() is used, then the handler data must be emitted
1408   // after the unwind opcodes.  The handler data consists of several 32-bit
1409   // words, and should be terminated by zero.
1410   //
1411   // In case that the .handlerdata directive is not specified by the
1412   // programmer, we should emit zero to terminate the handler data.
1413   if (NoHandlerData && !Personality)
1414     emitInt32(0);
1415 }
1416 
1417 void ARMELFStreamer::emitHandlerData() { FlushUnwindOpcodes(false); }
1418 
1419 void ARMELFStreamer::emitPersonality(const MCSymbol *Per) {
1420   Personality = Per;
1421   UnwindOpAsm.setPersonality(Per);
1422 }
1423 
1424 void ARMELFStreamer::emitPersonalityIndex(unsigned Index) {
1425   assert(Index < ARM::EHABI::NUM_PERSONALITY_INDEX && "invalid index");
1426   PersonalityIndex = Index;
1427 }
1428 
1429 void ARMELFStreamer::emitSetFP(unsigned NewFPReg, unsigned NewSPReg,
1430                                int64_t Offset) {
1431   assert((NewSPReg == ARM::SP || NewSPReg == FPReg) &&
1432          "the operand of .setfp directive should be either $sp or $fp");
1433 
1434   UsedFP = true;
1435   FPReg = NewFPReg;
1436 
1437   if (NewSPReg == ARM::SP)
1438     FPOffset = SPOffset + Offset;
1439   else
1440     FPOffset += Offset;
1441 }
1442 
1443 void ARMELFStreamer::emitMovSP(unsigned Reg, int64_t Offset) {
1444   assert((Reg != ARM::SP && Reg != ARM::PC) &&
1445          "the operand of .movsp cannot be either sp or pc");
1446   assert(FPReg == ARM::SP && "current FP must be SP");
1447 
1448   FlushPendingOffset();
1449 
1450   FPReg = Reg;
1451   FPOffset = SPOffset + Offset;
1452 
1453   const MCRegisterInfo *MRI = getContext().getRegisterInfo();
1454   UnwindOpAsm.EmitSetSP(MRI->getEncodingValue(FPReg));
1455 }
1456 
1457 void ARMELFStreamer::emitPad(int64_t Offset) {
1458   // Track the change of the $sp offset
1459   SPOffset -= Offset;
1460 
1461   // To squash multiple .pad directives, we should delay the unwind opcode
1462   // until the .save, .vsave, .handlerdata, or .fnend directives.
1463   PendingOffset -= Offset;
1464 }
1465 
1466 void ARMELFStreamer::emitRegSave(const SmallVectorImpl<unsigned> &RegList,
1467                                  bool IsVector) {
1468   // Collect the registers in the register list
1469   unsigned Count = 0;
1470   uint32_t Mask = 0;
1471   const MCRegisterInfo *MRI = getContext().getRegisterInfo();
1472   for (size_t i = 0; i < RegList.size(); ++i) {
1473     unsigned Reg = MRI->getEncodingValue(RegList[i]);
1474     assert(Reg < (IsVector ? 32U : 16U) && "Register out of range");
1475     unsigned Bit = (1u << Reg);
1476     if ((Mask & Bit) == 0) {
1477       Mask |= Bit;
1478       ++Count;
1479     }
1480   }
1481 
1482   // Track the change the $sp offset: For the .save directive, the
1483   // corresponding push instruction will decrease the $sp by (4 * Count).
1484   // For the .vsave directive, the corresponding vpush instruction will
1485   // decrease $sp by (8 * Count).
1486   SPOffset -= Count * (IsVector ? 8 : 4);
1487 
1488   // Emit the opcode
1489   FlushPendingOffset();
1490   if (IsVector)
1491     UnwindOpAsm.EmitVFPRegSave(Mask);
1492   else
1493     UnwindOpAsm.EmitRegSave(Mask);
1494 }
1495 
1496 void ARMELFStreamer::emitUnwindRaw(int64_t Offset,
1497                                    const SmallVectorImpl<uint8_t> &Opcodes) {
1498   FlushPendingOffset();
1499   SPOffset = SPOffset - Offset;
1500   UnwindOpAsm.EmitRaw(Opcodes);
1501 }
1502 
1503 namespace llvm {
1504 
1505 MCTargetStreamer *createARMTargetAsmStreamer(MCStreamer &S,
1506                                              formatted_raw_ostream &OS,
1507                                              MCInstPrinter *InstPrint,
1508                                              bool isVerboseAsm) {
1509   return new ARMTargetAsmStreamer(S, OS, *InstPrint, isVerboseAsm);
1510 }
1511 
1512 MCTargetStreamer *createARMNullTargetStreamer(MCStreamer &S) {
1513   return new ARMTargetStreamer(S);
1514 }
1515 
1516 MCTargetStreamer *createARMObjectTargetStreamer(MCStreamer &S,
1517                                                 const MCSubtargetInfo &STI) {
1518   const Triple &TT = STI.getTargetTriple();
1519   if (TT.isOSBinFormatELF())
1520     return new ARMTargetELFStreamer(S);
1521   return new ARMTargetStreamer(S);
1522 }
1523 
1524 MCELFStreamer *createARMELFStreamer(MCContext &Context,
1525                                     std::unique_ptr<MCAsmBackend> TAB,
1526                                     std::unique_ptr<MCObjectWriter> OW,
1527                                     std::unique_ptr<MCCodeEmitter> Emitter,
1528                                     bool RelaxAll, bool IsThumb,
1529                                     bool IsAndroid) {
1530   ARMELFStreamer *S =
1531       new ARMELFStreamer(Context, std::move(TAB), std::move(OW),
1532                          std::move(Emitter), IsThumb, IsAndroid);
1533   // FIXME: This should eventually end up somewhere else where more
1534   // intelligent flag decisions can be made. For now we are just maintaining
1535   // the status quo for ARM and setting EF_ARM_EABI_VER5 as the default.
1536   S->getAssembler().setELFHeaderEFlags(ELF::EF_ARM_EABI_VER5);
1537 
1538   if (RelaxAll)
1539     S->getAssembler().setRelaxAll(true);
1540   return S;
1541 }
1542 
1543 } // end namespace llvm
1544