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(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                  std::unique_ptr<MCObjectWriter> OW,
445                  std::unique_ptr<MCCodeEmitter> Emitter, bool IsThumb,
446                  bool IsAndroid)
447       : MCELFStreamer(Context, std::move(TAB), std::move(OW),
448                       std::move(Emitter)),
449         IsThumb(IsThumb), IsAndroid(IsAndroid) {
450     EHReset();
451   }
452 
453   ~ARMELFStreamer() override = default;
454 
455   void FinishImpl() override;
456 
457   // ARM exception handling directives
458   void emitFnStart();
459   void emitFnEnd();
460   void emitCantUnwind();
461   void emitPersonality(const MCSymbol *Per);
462   void emitPersonalityIndex(unsigned index);
463   void emitHandlerData();
464   void emitSetFP(unsigned NewFpReg, unsigned NewSpReg, int64_t Offset = 0);
465   void emitMovSP(unsigned Reg, int64_t Offset = 0);
466   void emitPad(int64_t Offset);
467   void emitRegSave(const SmallVectorImpl<unsigned> &RegList, bool isVector);
468   void emitUnwindRaw(int64_t Offset, const SmallVectorImpl<uint8_t> &Opcodes);
469   void emitFill(const MCExpr &NumBytes, uint64_t FillValue,
470                 SMLoc Loc) override {
471     EmitDataMappingSymbol();
472     MCObjectStreamer::emitFill(NumBytes, FillValue, Loc);
473   }
474 
475   void ChangeSection(MCSection *Section, const MCExpr *Subsection) override {
476     LastMappingSymbols[getCurrentSection().first] = std::move(LastEMSInfo);
477     MCELFStreamer::ChangeSection(Section, Subsection);
478     auto LastMappingSymbol = LastMappingSymbols.find(Section);
479     if (LastMappingSymbol != LastMappingSymbols.end()) {
480       LastEMSInfo = std::move(LastMappingSymbol->second);
481       return;
482     }
483     LastEMSInfo.reset(new ElfMappingSymbolInfo(SMLoc(), nullptr, 0));
484   }
485 
486   /// This function is the one used to emit instruction data into the ELF
487   /// streamer. We override it to add the appropriate mapping symbol if
488   /// necessary.
489   void EmitInstruction(const MCInst &Inst,
490                        const MCSubtargetInfo &STI) override {
491     if (IsThumb)
492       EmitThumbMappingSymbol();
493     else
494       EmitARMMappingSymbol();
495 
496     MCELFStreamer::EmitInstruction(Inst, STI);
497   }
498 
499   void emitInst(uint32_t Inst, char Suffix) {
500     unsigned Size;
501     char Buffer[4];
502     const bool LittleEndian = getContext().getAsmInfo()->isLittleEndian();
503 
504     switch (Suffix) {
505     case '\0':
506       Size = 4;
507 
508       assert(!IsThumb);
509       EmitARMMappingSymbol();
510       for (unsigned II = 0, IE = Size; II != IE; II++) {
511         const unsigned I = LittleEndian ? (Size - II - 1) : II;
512         Buffer[Size - II - 1] = uint8_t(Inst >> I * CHAR_BIT);
513       }
514 
515       break;
516     case 'n':
517     case 'w':
518       Size = (Suffix == 'n' ? 2 : 4);
519 
520       assert(IsThumb);
521       EmitThumbMappingSymbol();
522       // Thumb wide instructions are emitted as a pair of 16-bit words of the
523       // appropriate endianness.
524       for (unsigned II = 0, IE = Size; II != IE; II = II + 2) {
525         const unsigned I0 = LittleEndian ? II + 0 : II + 1;
526         const unsigned I1 = LittleEndian ? II + 1 : II + 0;
527         Buffer[Size - II - 2] = uint8_t(Inst >> I0 * CHAR_BIT);
528         Buffer[Size - II - 1] = uint8_t(Inst >> I1 * CHAR_BIT);
529       }
530 
531       break;
532     default:
533       llvm_unreachable("Invalid Suffix");
534     }
535 
536     MCELFStreamer::EmitBytes(StringRef(Buffer, Size));
537   }
538 
539   /// This is one of the functions used to emit data into an ELF section, so the
540   /// ARM streamer overrides it to add the appropriate mapping symbol ($d) if
541   /// necessary.
542   void EmitBytes(StringRef Data) override {
543     EmitDataMappingSymbol();
544     MCELFStreamer::EmitBytes(Data);
545   }
546 
547   void FlushPendingMappingSymbol() {
548     if (!LastEMSInfo->hasInfo())
549       return;
550     ElfMappingSymbolInfo *EMS = LastEMSInfo.get();
551     EmitMappingSymbol("$d", EMS->Loc, EMS->F, EMS->Offset);
552     EMS->resetInfo();
553   }
554 
555   /// This is one of the functions used to emit data into an ELF section, so the
556   /// ARM streamer overrides it to add the appropriate mapping symbol ($d) if
557   /// necessary.
558   void EmitValueImpl(const MCExpr *Value, unsigned Size, SMLoc Loc) override {
559     if (const MCSymbolRefExpr *SRE = dyn_cast_or_null<MCSymbolRefExpr>(Value)) {
560       if (SRE->getKind() == MCSymbolRefExpr::VK_ARM_SBREL && !(Size == 4)) {
561         getContext().reportError(Loc, "relocated expression must be 32-bit");
562         return;
563       }
564       getOrCreateDataFragment();
565     }
566 
567     EmitDataMappingSymbol();
568     MCELFStreamer::EmitValueImpl(Value, Size, Loc);
569   }
570 
571   void EmitAssemblerFlag(MCAssemblerFlag Flag) override {
572     MCELFStreamer::EmitAssemblerFlag(Flag);
573 
574     switch (Flag) {
575     case MCAF_SyntaxUnified:
576       return; // no-op here.
577     case MCAF_Code16:
578       IsThumb = true;
579       return; // Change to Thumb mode
580     case MCAF_Code32:
581       IsThumb = false;
582       return; // Change to ARM mode
583     case MCAF_Code64:
584       return;
585     case MCAF_SubsectionsViaSymbols:
586       return;
587     }
588   }
589 
590 private:
591   enum ElfMappingSymbol {
592     EMS_None,
593     EMS_ARM,
594     EMS_Thumb,
595     EMS_Data
596   };
597 
598   struct ElfMappingSymbolInfo {
599     explicit ElfMappingSymbolInfo(SMLoc Loc, MCFragment *F, uint64_t O)
600         : Loc(Loc), F(F), Offset(O), State(EMS_None) {}
601     void resetInfo() {
602       F = nullptr;
603       Offset = 0;
604     }
605     bool hasInfo() { return F != nullptr; }
606     SMLoc Loc;
607     MCFragment *F;
608     uint64_t Offset;
609     ElfMappingSymbol State;
610   };
611 
612   void EmitDataMappingSymbol() {
613     if (LastEMSInfo->State == EMS_Data)
614       return;
615     else if (LastEMSInfo->State == EMS_None) {
616       // This is a tentative symbol, it won't really be emitted until it's
617       // actually needed.
618       ElfMappingSymbolInfo *EMS = LastEMSInfo.get();
619       auto *DF = dyn_cast_or_null<MCDataFragment>(getCurrentFragment());
620       if (!DF)
621         return;
622       EMS->Loc = SMLoc();
623       EMS->F = getCurrentFragment();
624       EMS->Offset = DF->getContents().size();
625       LastEMSInfo->State = EMS_Data;
626       return;
627     }
628     EmitMappingSymbol("$d");
629     LastEMSInfo->State = EMS_Data;
630   }
631 
632   void EmitThumbMappingSymbol() {
633     if (LastEMSInfo->State == EMS_Thumb)
634       return;
635     FlushPendingMappingSymbol();
636     EmitMappingSymbol("$t");
637     LastEMSInfo->State = EMS_Thumb;
638   }
639 
640   void EmitARMMappingSymbol() {
641     if (LastEMSInfo->State == EMS_ARM)
642       return;
643     FlushPendingMappingSymbol();
644     EmitMappingSymbol("$a");
645     LastEMSInfo->State = EMS_ARM;
646   }
647 
648   void EmitMappingSymbol(StringRef Name) {
649     auto *Symbol = cast<MCSymbolELF>(getContext().getOrCreateSymbol(
650         Name + "." + Twine(MappingSymbolCounter++)));
651     EmitLabel(Symbol);
652 
653     Symbol->setType(ELF::STT_NOTYPE);
654     Symbol->setBinding(ELF::STB_LOCAL);
655     Symbol->setExternal(false);
656   }
657 
658   void EmitMappingSymbol(StringRef Name, SMLoc Loc, MCFragment *F,
659                          uint64_t Offset) {
660     auto *Symbol = cast<MCSymbolELF>(getContext().getOrCreateSymbol(
661         Name + "." + Twine(MappingSymbolCounter++)));
662     EmitLabelAtPos(Symbol, Loc, F, Offset);
663     Symbol->setType(ELF::STT_NOTYPE);
664     Symbol->setBinding(ELF::STB_LOCAL);
665     Symbol->setExternal(false);
666   }
667 
668   void EmitThumbFunc(MCSymbol *Func) override {
669     getAssembler().setIsThumbFunc(Func);
670     EmitSymbolAttribute(Func, MCSA_ELF_TypeFunction);
671   }
672 
673   // Helper functions for ARM exception handling directives
674   void EHReset();
675 
676   // Reset state between object emissions
677   void reset() override;
678 
679   void EmitPersonalityFixup(StringRef Name);
680   void FlushPendingOffset();
681   void FlushUnwindOpcodes(bool NoHandlerData);
682 
683   void SwitchToEHSection(StringRef Prefix, unsigned Type, unsigned Flags,
684                          SectionKind Kind, const MCSymbol &Fn);
685   void SwitchToExTabSection(const MCSymbol &FnStart);
686   void SwitchToExIdxSection(const MCSymbol &FnStart);
687 
688   void EmitFixup(const MCExpr *Expr, MCFixupKind Kind);
689 
690   bool IsThumb;
691   bool IsAndroid;
692   int64_t MappingSymbolCounter = 0;
693 
694   DenseMap<const MCSection *, std::unique_ptr<ElfMappingSymbolInfo>>
695       LastMappingSymbols;
696 
697   std::unique_ptr<ElfMappingSymbolInfo> LastEMSInfo;
698 
699   // ARM Exception Handling Frame Information
700   MCSymbol *ExTab;
701   MCSymbol *FnStart;
702   const MCSymbol *Personality;
703   unsigned PersonalityIndex;
704   unsigned FPReg; // Frame pointer register
705   int64_t FPOffset; // Offset: (final frame pointer) - (initial $sp)
706   int64_t SPOffset; // Offset: (final $sp) - (initial $sp)
707   int64_t PendingOffset; // Offset: (final $sp) - (emitted $sp)
708   bool UsedFP;
709   bool CantUnwind;
710   SmallVector<uint8_t, 64> Opcodes;
711   UnwindOpcodeAssembler UnwindOpAsm;
712 };
713 
714 } // end anonymous namespace
715 
716 ARMELFStreamer &ARMTargetELFStreamer::getStreamer() {
717   return static_cast<ARMELFStreamer &>(Streamer);
718 }
719 
720 void ARMTargetELFStreamer::emitFnStart() { getStreamer().emitFnStart(); }
721 void ARMTargetELFStreamer::emitFnEnd() { getStreamer().emitFnEnd(); }
722 void ARMTargetELFStreamer::emitCantUnwind() { getStreamer().emitCantUnwind(); }
723 
724 void ARMTargetELFStreamer::emitPersonality(const MCSymbol *Personality) {
725   getStreamer().emitPersonality(Personality);
726 }
727 
728 void ARMTargetELFStreamer::emitPersonalityIndex(unsigned Index) {
729   getStreamer().emitPersonalityIndex(Index);
730 }
731 
732 void ARMTargetELFStreamer::emitHandlerData() {
733   getStreamer().emitHandlerData();
734 }
735 
736 void ARMTargetELFStreamer::emitSetFP(unsigned FpReg, unsigned SpReg,
737                                      int64_t Offset) {
738   getStreamer().emitSetFP(FpReg, SpReg, Offset);
739 }
740 
741 void ARMTargetELFStreamer::emitMovSP(unsigned Reg, int64_t Offset) {
742   getStreamer().emitMovSP(Reg, Offset);
743 }
744 
745 void ARMTargetELFStreamer::emitPad(int64_t Offset) {
746   getStreamer().emitPad(Offset);
747 }
748 
749 void ARMTargetELFStreamer::emitRegSave(const SmallVectorImpl<unsigned> &RegList,
750                                        bool isVector) {
751   getStreamer().emitRegSave(RegList, isVector);
752 }
753 
754 void ARMTargetELFStreamer::emitUnwindRaw(int64_t Offset,
755                                       const SmallVectorImpl<uint8_t> &Opcodes) {
756   getStreamer().emitUnwindRaw(Offset, Opcodes);
757 }
758 
759 void ARMTargetELFStreamer::switchVendor(StringRef Vendor) {
760   assert(!Vendor.empty() && "Vendor cannot be empty.");
761 
762   if (CurrentVendor == Vendor)
763     return;
764 
765   if (!CurrentVendor.empty())
766     finishAttributeSection();
767 
768   assert(Contents.empty() &&
769          ".ARM.attributes should be flushed before changing vendor");
770   CurrentVendor = Vendor;
771 
772 }
773 
774 void ARMTargetELFStreamer::emitAttribute(unsigned Attribute, unsigned Value) {
775   setAttributeItem(Attribute, Value, /* OverwriteExisting= */ true);
776 }
777 
778 void ARMTargetELFStreamer::emitTextAttribute(unsigned Attribute,
779                                              StringRef Value) {
780   setAttributeItem(Attribute, Value, /* OverwriteExisting= */ true);
781 }
782 
783 void ARMTargetELFStreamer::emitIntTextAttribute(unsigned Attribute,
784                                                 unsigned IntValue,
785                                                 StringRef StringValue) {
786   setAttributeItems(Attribute, IntValue, StringValue,
787                     /* OverwriteExisting= */ true);
788 }
789 
790 void ARMTargetELFStreamer::emitArch(ARM::ArchKind Value) {
791   Arch = Value;
792 }
793 
794 void ARMTargetELFStreamer::emitObjectArch(ARM::ArchKind Value) {
795   EmittedArch = Value;
796 }
797 
798 void ARMTargetELFStreamer::emitArchDefaultAttributes() {
799   using namespace ARMBuildAttrs;
800 
801   setAttributeItem(CPU_name,
802                    ARM::getCPUAttr(Arch),
803                    false);
804 
805   if (EmittedArch == ARM::ArchKind::INVALID)
806     setAttributeItem(CPU_arch,
807                      ARM::getArchAttr(Arch),
808                      false);
809   else
810     setAttributeItem(CPU_arch,
811                      ARM::getArchAttr(EmittedArch),
812                      false);
813 
814   switch (Arch) {
815   case ARM::ArchKind::ARMV2:
816   case ARM::ArchKind::ARMV2A:
817   case ARM::ArchKind::ARMV3:
818   case ARM::ArchKind::ARMV3M:
819   case ARM::ArchKind::ARMV4:
820     setAttributeItem(ARM_ISA_use, Allowed, false);
821     break;
822 
823   case ARM::ArchKind::ARMV4T:
824   case ARM::ArchKind::ARMV5T:
825   case ARM::ArchKind::ARMV5TE:
826   case ARM::ArchKind::ARMV6:
827     setAttributeItem(ARM_ISA_use, Allowed, false);
828     setAttributeItem(THUMB_ISA_use, Allowed, false);
829     break;
830 
831   case ARM::ArchKind::ARMV6T2:
832     setAttributeItem(ARM_ISA_use, Allowed, false);
833     setAttributeItem(THUMB_ISA_use, AllowThumb32, false);
834     break;
835 
836   case ARM::ArchKind::ARMV6K:
837   case ARM::ArchKind::ARMV6KZ:
838     setAttributeItem(ARM_ISA_use, Allowed, false);
839     setAttributeItem(THUMB_ISA_use, Allowed, false);
840     setAttributeItem(Virtualization_use, AllowTZ, false);
841     break;
842 
843   case ARM::ArchKind::ARMV6M:
844     setAttributeItem(THUMB_ISA_use, Allowed, false);
845     break;
846 
847   case ARM::ArchKind::ARMV7A:
848     setAttributeItem(CPU_arch_profile, ApplicationProfile, false);
849     setAttributeItem(ARM_ISA_use, Allowed, false);
850     setAttributeItem(THUMB_ISA_use, AllowThumb32, false);
851     break;
852 
853   case ARM::ArchKind::ARMV7R:
854     setAttributeItem(CPU_arch_profile, RealTimeProfile, false);
855     setAttributeItem(ARM_ISA_use, Allowed, false);
856     setAttributeItem(THUMB_ISA_use, AllowThumb32, false);
857     break;
858 
859   case ARM::ArchKind::ARMV7EM:
860   case ARM::ArchKind::ARMV7M:
861     setAttributeItem(CPU_arch_profile, MicroControllerProfile, false);
862     setAttributeItem(THUMB_ISA_use, AllowThumb32, false);
863     break;
864 
865   case ARM::ArchKind::ARMV8A:
866   case ARM::ArchKind::ARMV8_1A:
867   case ARM::ArchKind::ARMV8_2A:
868   case ARM::ArchKind::ARMV8_3A:
869   case ARM::ArchKind::ARMV8_4A:
870   case ARM::ArchKind::ARMV8_5A:
871     setAttributeItem(CPU_arch_profile, ApplicationProfile, false);
872     setAttributeItem(ARM_ISA_use, Allowed, false);
873     setAttributeItem(THUMB_ISA_use, AllowThumb32, false);
874     setAttributeItem(MPextension_use, Allowed, false);
875     setAttributeItem(Virtualization_use, AllowTZVirtualization, false);
876     break;
877 
878   case ARM::ArchKind::ARMV8MBaseline:
879   case ARM::ArchKind::ARMV8MMainline:
880     setAttributeItem(THUMB_ISA_use, AllowThumbDerived, false);
881     setAttributeItem(CPU_arch_profile, MicroControllerProfile, false);
882     break;
883 
884   case ARM::ArchKind::IWMMXT:
885     setAttributeItem(ARM_ISA_use, Allowed, false);
886     setAttributeItem(THUMB_ISA_use, Allowed, false);
887     setAttributeItem(WMMX_arch, AllowWMMXv1, false);
888     break;
889 
890   case ARM::ArchKind::IWMMXT2:
891     setAttributeItem(ARM_ISA_use, Allowed, false);
892     setAttributeItem(THUMB_ISA_use, Allowed, false);
893     setAttributeItem(WMMX_arch, AllowWMMXv2, false);
894     break;
895 
896   default:
897     report_fatal_error("Unknown Arch: " + Twine(ARM::getArchName(Arch)));
898     break;
899   }
900 }
901 
902 void ARMTargetELFStreamer::emitFPU(unsigned Value) {
903   FPU = Value;
904 }
905 
906 void ARMTargetELFStreamer::emitFPUDefaultAttributes() {
907   switch (FPU) {
908   case ARM::FK_VFP:
909   case ARM::FK_VFPV2:
910     setAttributeItem(ARMBuildAttrs::FP_arch,
911                      ARMBuildAttrs::AllowFPv2,
912                      /* OverwriteExisting= */ false);
913     break;
914 
915   case ARM::FK_VFPV3:
916     setAttributeItem(ARMBuildAttrs::FP_arch,
917                      ARMBuildAttrs::AllowFPv3A,
918                      /* OverwriteExisting= */ false);
919     break;
920 
921   case ARM::FK_VFPV3_FP16:
922     setAttributeItem(ARMBuildAttrs::FP_arch,
923                      ARMBuildAttrs::AllowFPv3A,
924                      /* OverwriteExisting= */ false);
925     setAttributeItem(ARMBuildAttrs::FP_HP_extension,
926                      ARMBuildAttrs::AllowHPFP,
927                      /* OverwriteExisting= */ false);
928     break;
929 
930   case ARM::FK_VFPV3_D16:
931     setAttributeItem(ARMBuildAttrs::FP_arch,
932                      ARMBuildAttrs::AllowFPv3B,
933                      /* OverwriteExisting= */ false);
934     break;
935 
936   case ARM::FK_VFPV3_D16_FP16:
937     setAttributeItem(ARMBuildAttrs::FP_arch,
938                      ARMBuildAttrs::AllowFPv3B,
939                      /* OverwriteExisting= */ false);
940     setAttributeItem(ARMBuildAttrs::FP_HP_extension,
941                      ARMBuildAttrs::AllowHPFP,
942                      /* OverwriteExisting= */ false);
943     break;
944 
945   case ARM::FK_VFPV3XD:
946     setAttributeItem(ARMBuildAttrs::FP_arch,
947                      ARMBuildAttrs::AllowFPv3B,
948                      /* OverwriteExisting= */ false);
949     break;
950   case ARM::FK_VFPV3XD_FP16:
951     setAttributeItem(ARMBuildAttrs::FP_arch,
952                      ARMBuildAttrs::AllowFPv3B,
953                      /* OverwriteExisting= */ false);
954     setAttributeItem(ARMBuildAttrs::FP_HP_extension,
955                      ARMBuildAttrs::AllowHPFP,
956                      /* OverwriteExisting= */ false);
957     break;
958 
959   case ARM::FK_VFPV4:
960     setAttributeItem(ARMBuildAttrs::FP_arch,
961                      ARMBuildAttrs::AllowFPv4A,
962                      /* OverwriteExisting= */ false);
963     break;
964 
965   // ABI_HardFP_use is handled in ARMAsmPrinter, so _SP_D16 is treated the same
966   // as _D16 here.
967   case ARM::FK_FPV4_SP_D16:
968   case ARM::FK_VFPV4_D16:
969     setAttributeItem(ARMBuildAttrs::FP_arch,
970                      ARMBuildAttrs::AllowFPv4B,
971                      /* OverwriteExisting= */ false);
972     break;
973 
974   case ARM::FK_FP_ARMV8:
975     setAttributeItem(ARMBuildAttrs::FP_arch,
976                      ARMBuildAttrs::AllowFPARMv8A,
977                      /* OverwriteExisting= */ false);
978     break;
979 
980   // FPV5_D16 is identical to FP_ARMV8 except for the number of D registers, so
981   // uses the FP_ARMV8_D16 build attribute.
982   case ARM::FK_FPV5_SP_D16:
983   case ARM::FK_FPV5_D16:
984     setAttributeItem(ARMBuildAttrs::FP_arch,
985                      ARMBuildAttrs::AllowFPARMv8B,
986                      /* OverwriteExisting= */ false);
987     break;
988 
989   case ARM::FK_NEON:
990     setAttributeItem(ARMBuildAttrs::FP_arch,
991                      ARMBuildAttrs::AllowFPv3A,
992                      /* OverwriteExisting= */ false);
993     setAttributeItem(ARMBuildAttrs::Advanced_SIMD_arch,
994                      ARMBuildAttrs::AllowNeon,
995                      /* OverwriteExisting= */ false);
996     break;
997 
998   case ARM::FK_NEON_FP16:
999     setAttributeItem(ARMBuildAttrs::FP_arch,
1000                      ARMBuildAttrs::AllowFPv3A,
1001                      /* OverwriteExisting= */ false);
1002     setAttributeItem(ARMBuildAttrs::Advanced_SIMD_arch,
1003                      ARMBuildAttrs::AllowNeon,
1004                      /* OverwriteExisting= */ false);
1005     setAttributeItem(ARMBuildAttrs::FP_HP_extension,
1006                      ARMBuildAttrs::AllowHPFP,
1007                      /* OverwriteExisting= */ false);
1008     break;
1009 
1010   case ARM::FK_NEON_VFPV4:
1011     setAttributeItem(ARMBuildAttrs::FP_arch,
1012                      ARMBuildAttrs::AllowFPv4A,
1013                      /* OverwriteExisting= */ false);
1014     setAttributeItem(ARMBuildAttrs::Advanced_SIMD_arch,
1015                      ARMBuildAttrs::AllowNeon2,
1016                      /* OverwriteExisting= */ false);
1017     break;
1018 
1019   case ARM::FK_NEON_FP_ARMV8:
1020   case ARM::FK_CRYPTO_NEON_FP_ARMV8:
1021     setAttributeItem(ARMBuildAttrs::FP_arch,
1022                      ARMBuildAttrs::AllowFPARMv8A,
1023                      /* OverwriteExisting= */ false);
1024     // 'Advanced_SIMD_arch' must be emitted not here, but within
1025     // ARMAsmPrinter::emitAttributes(), depending on hasV8Ops() and hasV8_1a()
1026     break;
1027 
1028   case ARM::FK_SOFTVFP:
1029   case ARM::FK_NONE:
1030     break;
1031 
1032   default:
1033     report_fatal_error("Unknown FPU: " + Twine(FPU));
1034     break;
1035   }
1036 }
1037 
1038 size_t ARMTargetELFStreamer::calculateContentSize() const {
1039   size_t Result = 0;
1040   for (size_t i = 0; i < Contents.size(); ++i) {
1041     AttributeItem item = Contents[i];
1042     switch (item.Type) {
1043     case AttributeItem::HiddenAttribute:
1044       break;
1045     case AttributeItem::NumericAttribute:
1046       Result += getULEB128Size(item.Tag);
1047       Result += getULEB128Size(item.IntValue);
1048       break;
1049     case AttributeItem::TextAttribute:
1050       Result += getULEB128Size(item.Tag);
1051       Result += item.StringValue.size() + 1; // string + '\0'
1052       break;
1053     case AttributeItem::NumericAndTextAttributes:
1054       Result += getULEB128Size(item.Tag);
1055       Result += getULEB128Size(item.IntValue);
1056       Result += item.StringValue.size() + 1; // string + '\0';
1057       break;
1058     }
1059   }
1060   return Result;
1061 }
1062 
1063 void ARMTargetELFStreamer::finishAttributeSection() {
1064   // <format-version>
1065   // [ <section-length> "vendor-name"
1066   // [ <file-tag> <size> <attribute>*
1067   //   | <section-tag> <size> <section-number>* 0 <attribute>*
1068   //   | <symbol-tag> <size> <symbol-number>* 0 <attribute>*
1069   //   ]+
1070   // ]*
1071 
1072   if (FPU != ARM::FK_INVALID)
1073     emitFPUDefaultAttributes();
1074 
1075   if (Arch != ARM::ArchKind::INVALID)
1076     emitArchDefaultAttributes();
1077 
1078   if (Contents.empty())
1079     return;
1080 
1081   llvm::sort(Contents, AttributeItem::LessTag);
1082 
1083   ARMELFStreamer &Streamer = getStreamer();
1084 
1085   // Switch to .ARM.attributes section
1086   if (AttributeSection) {
1087     Streamer.SwitchSection(AttributeSection);
1088   } else {
1089     AttributeSection = Streamer.getContext().getELFSection(
1090         ".ARM.attributes", ELF::SHT_ARM_ATTRIBUTES, 0);
1091     Streamer.SwitchSection(AttributeSection);
1092 
1093     // Format version
1094     Streamer.EmitIntValue(0x41, 1);
1095   }
1096 
1097   // Vendor size + Vendor name + '\0'
1098   const size_t VendorHeaderSize = 4 + CurrentVendor.size() + 1;
1099 
1100   // Tag + Tag Size
1101   const size_t TagHeaderSize = 1 + 4;
1102 
1103   const size_t ContentsSize = calculateContentSize();
1104 
1105   Streamer.EmitIntValue(VendorHeaderSize + TagHeaderSize + ContentsSize, 4);
1106   Streamer.EmitBytes(CurrentVendor);
1107   Streamer.EmitIntValue(0, 1); // '\0'
1108 
1109   Streamer.EmitIntValue(ARMBuildAttrs::File, 1);
1110   Streamer.EmitIntValue(TagHeaderSize + ContentsSize, 4);
1111 
1112   // Size should have been accounted for already, now
1113   // emit each field as its type (ULEB or String)
1114   for (size_t i = 0; i < Contents.size(); ++i) {
1115     AttributeItem item = Contents[i];
1116     Streamer.EmitULEB128IntValue(item.Tag);
1117     switch (item.Type) {
1118     default: llvm_unreachable("Invalid attribute type");
1119     case AttributeItem::NumericAttribute:
1120       Streamer.EmitULEB128IntValue(item.IntValue);
1121       break;
1122     case AttributeItem::TextAttribute:
1123       Streamer.EmitBytes(item.StringValue);
1124       Streamer.EmitIntValue(0, 1); // '\0'
1125       break;
1126     case AttributeItem::NumericAndTextAttributes:
1127       Streamer.EmitULEB128IntValue(item.IntValue);
1128       Streamer.EmitBytes(item.StringValue);
1129       Streamer.EmitIntValue(0, 1); // '\0'
1130       break;
1131     }
1132   }
1133 
1134   Contents.clear();
1135   FPU = ARM::FK_INVALID;
1136 }
1137 
1138 void ARMTargetELFStreamer::emitLabel(MCSymbol *Symbol) {
1139   ARMELFStreamer &Streamer = getStreamer();
1140   if (!Streamer.IsThumb)
1141     return;
1142 
1143   Streamer.getAssembler().registerSymbol(*Symbol);
1144   unsigned Type = cast<MCSymbolELF>(Symbol)->getType();
1145   if (Type == ELF::STT_FUNC || Type == ELF::STT_GNU_IFUNC)
1146     Streamer.EmitThumbFunc(Symbol);
1147 }
1148 
1149 void
1150 ARMTargetELFStreamer::AnnotateTLSDescriptorSequence(const MCSymbolRefExpr *S) {
1151   getStreamer().EmitFixup(S, FK_Data_4);
1152 }
1153 
1154 void ARMTargetELFStreamer::emitThumbSet(MCSymbol *Symbol, const MCExpr *Value) {
1155   if (const MCSymbolRefExpr *SRE = dyn_cast<MCSymbolRefExpr>(Value)) {
1156     const MCSymbol &Sym = SRE->getSymbol();
1157     if (!Sym.isDefined()) {
1158       getStreamer().EmitAssignment(Symbol, Value);
1159       return;
1160     }
1161   }
1162 
1163   getStreamer().EmitThumbFunc(Symbol);
1164   getStreamer().EmitAssignment(Symbol, Value);
1165 }
1166 
1167 void ARMTargetELFStreamer::emitInst(uint32_t Inst, char Suffix) {
1168   getStreamer().emitInst(Inst, Suffix);
1169 }
1170 
1171 void ARMTargetELFStreamer::reset() { AttributeSection = nullptr; }
1172 
1173 void ARMELFStreamer::FinishImpl() {
1174   MCTargetStreamer &TS = *getTargetStreamer();
1175   ARMTargetStreamer &ATS = static_cast<ARMTargetStreamer &>(TS);
1176   ATS.finishAttributeSection();
1177 
1178   MCELFStreamer::FinishImpl();
1179 }
1180 
1181 void ARMELFStreamer::reset() {
1182   MCTargetStreamer &TS = *getTargetStreamer();
1183   ARMTargetStreamer &ATS = static_cast<ARMTargetStreamer &>(TS);
1184   ATS.reset();
1185   MappingSymbolCounter = 0;
1186   MCELFStreamer::reset();
1187   LastMappingSymbols.clear();
1188   LastEMSInfo.reset();
1189   // MCELFStreamer clear's the assembler's e_flags. However, for
1190   // arm we manually set the ABI version on streamer creation, so
1191   // do the same here
1192   getAssembler().setELFHeaderEFlags(ELF::EF_ARM_EABI_VER5);
1193 }
1194 
1195 inline void ARMELFStreamer::SwitchToEHSection(StringRef Prefix,
1196                                               unsigned Type,
1197                                               unsigned Flags,
1198                                               SectionKind Kind,
1199                                               const MCSymbol &Fn) {
1200   const MCSectionELF &FnSection =
1201     static_cast<const MCSectionELF &>(Fn.getSection());
1202 
1203   // Create the name for new section
1204   StringRef FnSecName(FnSection.getSectionName());
1205   SmallString<128> EHSecName(Prefix);
1206   if (FnSecName != ".text") {
1207     EHSecName += FnSecName;
1208   }
1209 
1210   // Get .ARM.extab or .ARM.exidx section
1211   const MCSymbolELF *Group = FnSection.getGroup();
1212   if (Group)
1213     Flags |= ELF::SHF_GROUP;
1214   MCSectionELF *EHSection = getContext().getELFSection(
1215       EHSecName, Type, Flags, 0, Group, FnSection.getUniqueID(),
1216       static_cast<const MCSymbolELF *>(&Fn));
1217 
1218   assert(EHSection && "Failed to get the required EH section");
1219 
1220   // Switch to .ARM.extab or .ARM.exidx section
1221   SwitchSection(EHSection);
1222   EmitCodeAlignment(4);
1223 }
1224 
1225 inline void ARMELFStreamer::SwitchToExTabSection(const MCSymbol &FnStart) {
1226   SwitchToEHSection(".ARM.extab", ELF::SHT_PROGBITS, ELF::SHF_ALLOC,
1227                     SectionKind::getData(), FnStart);
1228 }
1229 
1230 inline void ARMELFStreamer::SwitchToExIdxSection(const MCSymbol &FnStart) {
1231   SwitchToEHSection(".ARM.exidx", ELF::SHT_ARM_EXIDX,
1232                     ELF::SHF_ALLOC | ELF::SHF_LINK_ORDER,
1233                     SectionKind::getData(), FnStart);
1234 }
1235 
1236 void ARMELFStreamer::EmitFixup(const MCExpr *Expr, MCFixupKind Kind) {
1237   MCDataFragment *Frag = getOrCreateDataFragment();
1238   Frag->getFixups().push_back(MCFixup::create(Frag->getContents().size(), Expr,
1239                                               Kind));
1240 }
1241 
1242 void ARMELFStreamer::EHReset() {
1243   ExTab = nullptr;
1244   FnStart = nullptr;
1245   Personality = nullptr;
1246   PersonalityIndex = ARM::EHABI::NUM_PERSONALITY_INDEX;
1247   FPReg = ARM::SP;
1248   FPOffset = 0;
1249   SPOffset = 0;
1250   PendingOffset = 0;
1251   UsedFP = false;
1252   CantUnwind = false;
1253 
1254   Opcodes.clear();
1255   UnwindOpAsm.Reset();
1256 }
1257 
1258 void ARMELFStreamer::emitFnStart() {
1259   assert(FnStart == nullptr);
1260   FnStart = getContext().createTempSymbol();
1261   EmitLabel(FnStart);
1262 }
1263 
1264 void ARMELFStreamer::emitFnEnd() {
1265   assert(FnStart && ".fnstart must precedes .fnend");
1266 
1267   // Emit unwind opcodes if there is no .handlerdata directive
1268   if (!ExTab && !CantUnwind)
1269     FlushUnwindOpcodes(true);
1270 
1271   // Emit the exception index table entry
1272   SwitchToExIdxSection(*FnStart);
1273 
1274   // The EHABI requires a dependency preserving R_ARM_NONE relocation to the
1275   // personality routine to protect it from an arbitrary platform's static
1276   // linker garbage collection. We disable this for Android where the unwinder
1277   // is either dynamically linked or directly references the personality
1278   // routine.
1279   if (PersonalityIndex < ARM::EHABI::NUM_PERSONALITY_INDEX && !IsAndroid)
1280     EmitPersonalityFixup(GetAEABIUnwindPersonalityName(PersonalityIndex));
1281 
1282   const MCSymbolRefExpr *FnStartRef =
1283     MCSymbolRefExpr::create(FnStart,
1284                             MCSymbolRefExpr::VK_ARM_PREL31,
1285                             getContext());
1286 
1287   EmitValue(FnStartRef, 4);
1288 
1289   if (CantUnwind) {
1290     EmitIntValue(ARM::EHABI::EXIDX_CANTUNWIND, 4);
1291   } else if (ExTab) {
1292     // Emit a reference to the unwind opcodes in the ".ARM.extab" section.
1293     const MCSymbolRefExpr *ExTabEntryRef =
1294       MCSymbolRefExpr::create(ExTab,
1295                               MCSymbolRefExpr::VK_ARM_PREL31,
1296                               getContext());
1297     EmitValue(ExTabEntryRef, 4);
1298   } else {
1299     // For the __aeabi_unwind_cpp_pr0, we have to emit the unwind opcodes in
1300     // the second word of exception index table entry.  The size of the unwind
1301     // opcodes should always be 4 bytes.
1302     assert(PersonalityIndex == ARM::EHABI::AEABI_UNWIND_CPP_PR0 &&
1303            "Compact model must use __aeabi_unwind_cpp_pr0 as personality");
1304     assert(Opcodes.size() == 4u &&
1305            "Unwind opcode size for __aeabi_unwind_cpp_pr0 must be equal to 4");
1306     uint64_t Intval = Opcodes[0] |
1307                       Opcodes[1] << 8 |
1308                       Opcodes[2] << 16 |
1309                       Opcodes[3] << 24;
1310     EmitIntValue(Intval, Opcodes.size());
1311   }
1312 
1313   // Switch to the section containing FnStart
1314   SwitchSection(&FnStart->getSection());
1315 
1316   // Clean exception handling frame information
1317   EHReset();
1318 }
1319 
1320 void ARMELFStreamer::emitCantUnwind() { CantUnwind = true; }
1321 
1322 // Add the R_ARM_NONE fixup at the same position
1323 void ARMELFStreamer::EmitPersonalityFixup(StringRef Name) {
1324   const MCSymbol *PersonalitySym = getContext().getOrCreateSymbol(Name);
1325 
1326   const MCSymbolRefExpr *PersonalityRef = MCSymbolRefExpr::create(
1327       PersonalitySym, MCSymbolRefExpr::VK_ARM_NONE, getContext());
1328 
1329   visitUsedExpr(*PersonalityRef);
1330   MCDataFragment *DF = getOrCreateDataFragment();
1331   DF->getFixups().push_back(MCFixup::create(DF->getContents().size(),
1332                                             PersonalityRef,
1333                                             MCFixup::getKindForSize(4, false)));
1334 }
1335 
1336 void ARMELFStreamer::FlushPendingOffset() {
1337   if (PendingOffset != 0) {
1338     UnwindOpAsm.EmitSPOffset(-PendingOffset);
1339     PendingOffset = 0;
1340   }
1341 }
1342 
1343 void ARMELFStreamer::FlushUnwindOpcodes(bool NoHandlerData) {
1344   // Emit the unwind opcode to restore $sp.
1345   if (UsedFP) {
1346     const MCRegisterInfo *MRI = getContext().getRegisterInfo();
1347     int64_t LastRegSaveSPOffset = SPOffset - PendingOffset;
1348     UnwindOpAsm.EmitSPOffset(LastRegSaveSPOffset - FPOffset);
1349     UnwindOpAsm.EmitSetSP(MRI->getEncodingValue(FPReg));
1350   } else {
1351     FlushPendingOffset();
1352   }
1353 
1354   // Finalize the unwind opcode sequence
1355   UnwindOpAsm.Finalize(PersonalityIndex, Opcodes);
1356 
1357   // For compact model 0, we have to emit the unwind opcodes in the .ARM.exidx
1358   // section.  Thus, we don't have to create an entry in the .ARM.extab
1359   // section.
1360   if (NoHandlerData && PersonalityIndex == ARM::EHABI::AEABI_UNWIND_CPP_PR0)
1361     return;
1362 
1363   // Switch to .ARM.extab section.
1364   SwitchToExTabSection(*FnStart);
1365 
1366   // Create .ARM.extab label for offset in .ARM.exidx
1367   assert(!ExTab);
1368   ExTab = getContext().createTempSymbol();
1369   EmitLabel(ExTab);
1370 
1371   // Emit personality
1372   if (Personality) {
1373     const MCSymbolRefExpr *PersonalityRef =
1374       MCSymbolRefExpr::create(Personality,
1375                               MCSymbolRefExpr::VK_ARM_PREL31,
1376                               getContext());
1377 
1378     EmitValue(PersonalityRef, 4);
1379   }
1380 
1381   // Emit unwind opcodes
1382   assert((Opcodes.size() % 4) == 0 &&
1383          "Unwind opcode size for __aeabi_cpp_unwind_pr0 must be multiple of 4");
1384   for (unsigned I = 0; I != Opcodes.size(); I += 4) {
1385     uint64_t Intval = Opcodes[I] |
1386                       Opcodes[I + 1] << 8 |
1387                       Opcodes[I + 2] << 16 |
1388                       Opcodes[I + 3] << 24;
1389     EmitIntValue(Intval, 4);
1390   }
1391 
1392   // According to ARM EHABI section 9.2, if the __aeabi_unwind_cpp_pr1() or
1393   // __aeabi_unwind_cpp_pr2() is used, then the handler data must be emitted
1394   // after the unwind opcodes.  The handler data consists of several 32-bit
1395   // words, and should be terminated by zero.
1396   //
1397   // In case that the .handlerdata directive is not specified by the
1398   // programmer, we should emit zero to terminate the handler data.
1399   if (NoHandlerData && !Personality)
1400     EmitIntValue(0, 4);
1401 }
1402 
1403 void ARMELFStreamer::emitHandlerData() { FlushUnwindOpcodes(false); }
1404 
1405 void ARMELFStreamer::emitPersonality(const MCSymbol *Per) {
1406   Personality = Per;
1407   UnwindOpAsm.setPersonality(Per);
1408 }
1409 
1410 void ARMELFStreamer::emitPersonalityIndex(unsigned Index) {
1411   assert(Index < ARM::EHABI::NUM_PERSONALITY_INDEX && "invalid index");
1412   PersonalityIndex = Index;
1413 }
1414 
1415 void ARMELFStreamer::emitSetFP(unsigned NewFPReg, unsigned NewSPReg,
1416                                int64_t Offset) {
1417   assert((NewSPReg == ARM::SP || NewSPReg == FPReg) &&
1418          "the operand of .setfp directive should be either $sp or $fp");
1419 
1420   UsedFP = true;
1421   FPReg = NewFPReg;
1422 
1423   if (NewSPReg == ARM::SP)
1424     FPOffset = SPOffset + Offset;
1425   else
1426     FPOffset += Offset;
1427 }
1428 
1429 void ARMELFStreamer::emitMovSP(unsigned Reg, int64_t Offset) {
1430   assert((Reg != ARM::SP && Reg != ARM::PC) &&
1431          "the operand of .movsp cannot be either sp or pc");
1432   assert(FPReg == ARM::SP && "current FP must be SP");
1433 
1434   FlushPendingOffset();
1435 
1436   FPReg = Reg;
1437   FPOffset = SPOffset + Offset;
1438 
1439   const MCRegisterInfo *MRI = getContext().getRegisterInfo();
1440   UnwindOpAsm.EmitSetSP(MRI->getEncodingValue(FPReg));
1441 }
1442 
1443 void ARMELFStreamer::emitPad(int64_t Offset) {
1444   // Track the change of the $sp offset
1445   SPOffset -= Offset;
1446 
1447   // To squash multiple .pad directives, we should delay the unwind opcode
1448   // until the .save, .vsave, .handlerdata, or .fnend directives.
1449   PendingOffset -= Offset;
1450 }
1451 
1452 void ARMELFStreamer::emitRegSave(const SmallVectorImpl<unsigned> &RegList,
1453                                  bool IsVector) {
1454   // Collect the registers in the register list
1455   unsigned Count = 0;
1456   uint32_t Mask = 0;
1457   const MCRegisterInfo *MRI = getContext().getRegisterInfo();
1458   for (size_t i = 0; i < RegList.size(); ++i) {
1459     unsigned Reg = MRI->getEncodingValue(RegList[i]);
1460     assert(Reg < (IsVector ? 32U : 16U) && "Register out of range");
1461     unsigned Bit = (1u << Reg);
1462     if ((Mask & Bit) == 0) {
1463       Mask |= Bit;
1464       ++Count;
1465     }
1466   }
1467 
1468   // Track the change the $sp offset: For the .save directive, the
1469   // corresponding push instruction will decrease the $sp by (4 * Count).
1470   // For the .vsave directive, the corresponding vpush instruction will
1471   // decrease $sp by (8 * Count).
1472   SPOffset -= Count * (IsVector ? 8 : 4);
1473 
1474   // Emit the opcode
1475   FlushPendingOffset();
1476   if (IsVector)
1477     UnwindOpAsm.EmitVFPRegSave(Mask);
1478   else
1479     UnwindOpAsm.EmitRegSave(Mask);
1480 }
1481 
1482 void ARMELFStreamer::emitUnwindRaw(int64_t Offset,
1483                                    const SmallVectorImpl<uint8_t> &Opcodes) {
1484   FlushPendingOffset();
1485   SPOffset = SPOffset - Offset;
1486   UnwindOpAsm.EmitRaw(Opcodes);
1487 }
1488 
1489 namespace llvm {
1490 
1491 MCTargetStreamer *createARMTargetAsmStreamer(MCStreamer &S,
1492                                              formatted_raw_ostream &OS,
1493                                              MCInstPrinter *InstPrint,
1494                                              bool isVerboseAsm) {
1495   return new ARMTargetAsmStreamer(S, OS, *InstPrint, isVerboseAsm);
1496 }
1497 
1498 MCTargetStreamer *createARMNullTargetStreamer(MCStreamer &S) {
1499   return new ARMTargetStreamer(S);
1500 }
1501 
1502 MCTargetStreamer *createARMObjectTargetStreamer(MCStreamer &S,
1503                                                 const MCSubtargetInfo &STI) {
1504   const Triple &TT = STI.getTargetTriple();
1505   if (TT.isOSBinFormatELF())
1506     return new ARMTargetELFStreamer(S);
1507   return new ARMTargetStreamer(S);
1508 }
1509 
1510 MCELFStreamer *createARMELFStreamer(MCContext &Context,
1511                                     std::unique_ptr<MCAsmBackend> TAB,
1512                                     std::unique_ptr<MCObjectWriter> OW,
1513                                     std::unique_ptr<MCCodeEmitter> Emitter,
1514                                     bool RelaxAll, bool IsThumb,
1515                                     bool IsAndroid) {
1516   ARMELFStreamer *S =
1517       new ARMELFStreamer(Context, std::move(TAB), std::move(OW),
1518                          std::move(Emitter), IsThumb, IsAndroid);
1519   // FIXME: This should eventually end up somewhere else where more
1520   // intelligent flag decisions can be made. For now we are just maintaining
1521   // the status quo for ARM and setting EF_ARM_EABI_VER5 as the default.
1522   S->getAssembler().setELFHeaderEFlags(ELF::EF_ARM_EABI_VER5);
1523 
1524   if (RelaxAll)
1525     S->getAssembler().setRelaxAll(true);
1526   return S;
1527 }
1528 
1529 } // end namespace llvm
1530