1 //===- lib/MC/ARMELFStreamer.cpp - ELF Object Output for ARM --------------===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file assembles .s files and emits ARM ELF .o object files. Different
11 // from generic ELF streamer in emitting mapping symbols ($a, $t and $d) to
12 // delimit regions of data and code.
13 //
14 //===----------------------------------------------------------------------===//
15 
16 #include "ARMArchName.h"
17 #include "ARMFPUName.h"
18 #include "ARMArchExtName.h"
19 #include "ARMRegisterInfo.h"
20 #include "ARMUnwindOpAsm.h"
21 #include "llvm/ADT/StringExtras.h"
22 #include "llvm/ADT/Twine.h"
23 #include "llvm/MC/MCAsmBackend.h"
24 #include "llvm/MC/MCAsmInfo.h"
25 #include "llvm/MC/MCAssembler.h"
26 #include "llvm/MC/MCCodeEmitter.h"
27 #include "llvm/MC/MCContext.h"
28 #include "llvm/MC/MCELF.h"
29 #include "llvm/MC/MCELFStreamer.h"
30 #include "llvm/MC/MCELFSymbolFlags.h"
31 #include "llvm/MC/MCExpr.h"
32 #include "llvm/MC/MCInst.h"
33 #include "llvm/MC/MCInstPrinter.h"
34 #include "llvm/MC/MCObjectFileInfo.h"
35 #include "llvm/MC/MCObjectStreamer.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/MCSymbol.h"
41 #include "llvm/MC/MCValue.h"
42 #include "llvm/Support/ARMBuildAttributes.h"
43 #include "llvm/Support/ARMEHABI.h"
44 #include "llvm/Support/Debug.h"
45 #include "llvm/Support/ELF.h"
46 #include "llvm/Support/FormattedStream.h"
47 #include "llvm/Support/LEB128.h"
48 #include "llvm/Support/raw_ostream.h"
49 #include <algorithm>
50 
51 using namespace llvm;
52 
53 static std::string GetAEABIUnwindPersonalityName(unsigned Index) {
54   assert(Index < ARM::EHABI::NUM_PERSONALITY_INDEX &&
55          "Invalid personality index");
56   return (Twine("__aeabi_unwind_cpp_pr") + Twine(Index)).str();
57 }
58 
59 static const char *GetFPUName(unsigned ID) {
60   switch (ID) {
61   default:
62     llvm_unreachable("Unknown FPU kind");
63     break;
64 #define ARM_FPU_NAME(NAME, ID) case ARM::ID: return NAME;
65 #include "ARMFPUName.def"
66   }
67   return nullptr;
68 }
69 
70 static const char *GetArchName(unsigned ID) {
71   switch (ID) {
72   default:
73     llvm_unreachable("Unknown ARCH kind");
74     break;
75 #define ARM_ARCH_NAME(NAME, ID, DEFAULT_CPU_NAME, DEFAULT_CPU_ARCH) \
76   case ARM::ID: return NAME;
77 #define ARM_ARCH_ALIAS(NAME, ID) /* empty */
78 #include "ARMArchName.def"
79   }
80   return nullptr;
81 }
82 
83 static const char *GetArchDefaultCPUName(unsigned ID) {
84   switch (ID) {
85   default:
86     llvm_unreachable("Unknown ARCH kind");
87     break;
88 #define ARM_ARCH_NAME(NAME, ID, DEFAULT_CPU_NAME, DEFAULT_CPU_ARCH) \
89   case ARM::ID: return DEFAULT_CPU_NAME;
90 #define ARM_ARCH_ALIAS(NAME, ID) /* empty */
91 #include "ARMArchName.def"
92   }
93   return nullptr;
94 }
95 
96 static unsigned GetArchDefaultCPUArch(unsigned ID) {
97   switch (ID) {
98   default:
99     llvm_unreachable("Unknown ARCH kind");
100     break;
101 #define ARM_ARCH_NAME(NAME, ID, DEFAULT_CPU_NAME, DEFAULT_CPU_ARCH) \
102   case ARM::ID: return ARMBuildAttrs::DEFAULT_CPU_ARCH;
103 #define ARM_ARCH_ALIAS(NAME, ID) /* empty */
104 #include "ARMArchName.def"
105   }
106   return 0;
107 }
108 
109 static const char *GetArchExtName(unsigned ID) {
110   switch (ID) {
111   default:
112     llvm_unreachable("Unknown ARCH Extension kind");
113     break;
114 #define ARM_ARCHEXT_NAME(NAME, ID)                                             \
115   case ARM::ID:                                                                \
116     return NAME;
117 #include "ARMArchExtName.def"
118   }
119   return nullptr;
120 }
121 
122 namespace {
123 
124 class ARMELFStreamer;
125 
126 class ARMTargetAsmStreamer : public ARMTargetStreamer {
127   formatted_raw_ostream &OS;
128   MCInstPrinter &InstPrinter;
129   bool IsVerboseAsm;
130 
131   void emitFnStart() override;
132   void emitFnEnd() override;
133   void emitCantUnwind() override;
134   void emitPersonality(const MCSymbol *Personality) override;
135   void emitPersonalityIndex(unsigned Index) override;
136   void emitHandlerData() override;
137   void emitSetFP(unsigned FpReg, unsigned SpReg, int64_t Offset = 0) override;
138   void emitMovSP(unsigned Reg, int64_t Offset = 0) override;
139   void emitPad(int64_t Offset) override;
140   void emitRegSave(const SmallVectorImpl<unsigned> &RegList,
141                    bool isVector) override;
142   void emitUnwindRaw(int64_t Offset,
143                      const SmallVectorImpl<uint8_t> &Opcodes) override;
144 
145   void switchVendor(StringRef Vendor) override;
146   void emitAttribute(unsigned Attribute, unsigned Value) override;
147   void emitTextAttribute(unsigned Attribute, StringRef String) override;
148   void emitIntTextAttribute(unsigned Attribute, unsigned IntValue,
149                             StringRef StrinValue) override;
150   void emitArch(unsigned Arch) override;
151   void emitArchExtension(unsigned ArchExt) override;
152   void emitObjectArch(unsigned Arch) override;
153   void emitFPU(unsigned FPU) override;
154   void emitInst(uint32_t Inst, char Suffix = '\0') override;
155   void finishAttributeSection() override;
156 
157   void AnnotateTLSDescriptorSequence(const MCSymbolRefExpr *SRE) override;
158   void emitThumbSet(MCSymbol *Symbol, const MCExpr *Value) override;
159 
160 public:
161   ARMTargetAsmStreamer(MCStreamer &S, formatted_raw_ostream &OS,
162                        MCInstPrinter &InstPrinter, bool VerboseAsm);
163 };
164 
165 ARMTargetAsmStreamer::ARMTargetAsmStreamer(MCStreamer &S,
166                                            formatted_raw_ostream &OS,
167                                            MCInstPrinter &InstPrinter,
168                                            bool VerboseAsm)
169     : ARMTargetStreamer(S), OS(OS), InstPrinter(InstPrinter),
170       IsVerboseAsm(VerboseAsm) {}
171 void ARMTargetAsmStreamer::emitFnStart() { OS << "\t.fnstart\n"; }
172 void ARMTargetAsmStreamer::emitFnEnd() { OS << "\t.fnend\n"; }
173 void ARMTargetAsmStreamer::emitCantUnwind() { OS << "\t.cantunwind\n"; }
174 void ARMTargetAsmStreamer::emitPersonality(const MCSymbol *Personality) {
175   OS << "\t.personality " << Personality->getName() << '\n';
176 }
177 void ARMTargetAsmStreamer::emitPersonalityIndex(unsigned Index) {
178   OS << "\t.personalityindex " << Index << '\n';
179 }
180 void ARMTargetAsmStreamer::emitHandlerData() { OS << "\t.handlerdata\n"; }
181 void ARMTargetAsmStreamer::emitSetFP(unsigned FpReg, unsigned SpReg,
182                                      int64_t Offset) {
183   OS << "\t.setfp\t";
184   InstPrinter.printRegName(OS, FpReg);
185   OS << ", ";
186   InstPrinter.printRegName(OS, SpReg);
187   if (Offset)
188     OS << ", #" << Offset;
189   OS << '\n';
190 }
191 void ARMTargetAsmStreamer::emitMovSP(unsigned Reg, int64_t Offset) {
192   assert((Reg != ARM::SP && Reg != ARM::PC) &&
193          "the operand of .movsp cannot be either sp or pc");
194 
195   OS << "\t.movsp\t";
196   InstPrinter.printRegName(OS, Reg);
197   if (Offset)
198     OS << ", #" << Offset;
199   OS << '\n';
200 }
201 void ARMTargetAsmStreamer::emitPad(int64_t Offset) {
202   OS << "\t.pad\t#" << Offset << '\n';
203 }
204 void ARMTargetAsmStreamer::emitRegSave(const SmallVectorImpl<unsigned> &RegList,
205                                        bool isVector) {
206   assert(RegList.size() && "RegList should not be empty");
207   if (isVector)
208     OS << "\t.vsave\t{";
209   else
210     OS << "\t.save\t{";
211 
212   InstPrinter.printRegName(OS, RegList[0]);
213 
214   for (unsigned i = 1, e = RegList.size(); i != e; ++i) {
215     OS << ", ";
216     InstPrinter.printRegName(OS, RegList[i]);
217   }
218 
219   OS << "}\n";
220 }
221 void ARMTargetAsmStreamer::switchVendor(StringRef Vendor) {
222 }
223 void ARMTargetAsmStreamer::emitAttribute(unsigned Attribute, unsigned Value) {
224   OS << "\t.eabi_attribute\t" << Attribute << ", " << Twine(Value);
225   if (IsVerboseAsm) {
226     StringRef Name = ARMBuildAttrs::AttrTypeAsString(Attribute);
227     if (!Name.empty())
228       OS << "\t@ " << Name;
229   }
230   OS << "\n";
231 }
232 void ARMTargetAsmStreamer::emitTextAttribute(unsigned Attribute,
233                                              StringRef String) {
234   switch (Attribute) {
235   case ARMBuildAttrs::CPU_name:
236     OS << "\t.cpu\t" << String.lower();
237     break;
238   default:
239     OS << "\t.eabi_attribute\t" << Attribute << ", \"" << String << "\"";
240     if (IsVerboseAsm) {
241       StringRef Name = ARMBuildAttrs::AttrTypeAsString(Attribute);
242       if (!Name.empty())
243         OS << "\t@ " << Name;
244     }
245     break;
246   }
247   OS << "\n";
248 }
249 void ARMTargetAsmStreamer::emitIntTextAttribute(unsigned Attribute,
250                                                 unsigned IntValue,
251                                                 StringRef StringValue) {
252   switch (Attribute) {
253   default: llvm_unreachable("unsupported multi-value attribute in asm mode");
254   case ARMBuildAttrs::compatibility:
255     OS << "\t.eabi_attribute\t" << Attribute << ", " << IntValue;
256     if (!StringValue.empty())
257       OS << ", \"" << StringValue << "\"";
258     if (IsVerboseAsm)
259       OS << "\t@ " << ARMBuildAttrs::AttrTypeAsString(Attribute);
260     break;
261   }
262   OS << "\n";
263 }
264 void ARMTargetAsmStreamer::emitArch(unsigned Arch) {
265   OS << "\t.arch\t" << GetArchName(Arch) << "\n";
266 }
267 void ARMTargetAsmStreamer::emitArchExtension(unsigned ArchExt) {
268   OS << "\t.arch_extension\t" << GetArchExtName(ArchExt) << "\n";
269 }
270 void ARMTargetAsmStreamer::emitObjectArch(unsigned Arch) {
271   OS << "\t.object_arch\t" << GetArchName(Arch) << '\n';
272 }
273 void ARMTargetAsmStreamer::emitFPU(unsigned FPU) {
274   OS << "\t.fpu\t" << GetFPUName(FPU) << "\n";
275 }
276 void ARMTargetAsmStreamer::finishAttributeSection() {
277 }
278 void
279 ARMTargetAsmStreamer::AnnotateTLSDescriptorSequence(const MCSymbolRefExpr *S) {
280   OS << "\t.tlsdescseq\t" << S->getSymbol().getName();
281 }
282 
283 void ARMTargetAsmStreamer::emitThumbSet(MCSymbol *Symbol, const MCExpr *Value) {
284   OS << "\t.thumb_set\t" << *Symbol << ", " << *Value << '\n';
285 }
286 
287 void ARMTargetAsmStreamer::emitInst(uint32_t Inst, char Suffix) {
288   OS << "\t.inst";
289   if (Suffix)
290     OS << "." << Suffix;
291   OS << "\t0x" << utohexstr(Inst) << "\n";
292 }
293 
294 void ARMTargetAsmStreamer::emitUnwindRaw(int64_t Offset,
295                                       const SmallVectorImpl<uint8_t> &Opcodes) {
296   OS << "\t.unwind_raw " << Offset;
297   for (SmallVectorImpl<uint8_t>::const_iterator OCI = Opcodes.begin(),
298                                                 OCE = Opcodes.end();
299        OCI != OCE; ++OCI)
300     OS << ", 0x" << utohexstr(*OCI);
301   OS << '\n';
302 }
303 
304 class ARMTargetELFStreamer : public ARMTargetStreamer {
305 private:
306   // This structure holds all attributes, accounting for
307   // their string/numeric value, so we can later emmit them
308   // in declaration order, keeping all in the same vector
309   struct AttributeItem {
310     enum {
311       HiddenAttribute = 0,
312       NumericAttribute,
313       TextAttribute,
314       NumericAndTextAttributes
315     } Type;
316     unsigned Tag;
317     unsigned IntValue;
318     StringRef StringValue;
319 
320     static bool LessTag(const AttributeItem &LHS, const AttributeItem &RHS) {
321       // The conformance tag must be emitted first when serialised
322       // into an object file. Specifically, the addenda to the ARM ABI
323       // states that (2.3.7.4):
324       //
325       // "To simplify recognition by consumers in the common case of
326       // claiming conformity for the whole file, this tag should be
327       // emitted first in a file-scope sub-subsection of the first
328       // public subsection of the attributes section."
329       //
330       // So it is special-cased in this comparison predicate when the
331       // attributes are sorted in finishAttributeSection().
332       return (RHS.Tag != ARMBuildAttrs::conformance) &&
333              ((LHS.Tag == ARMBuildAttrs::conformance) || (LHS.Tag < RHS.Tag));
334     }
335   };
336 
337   StringRef CurrentVendor;
338   unsigned FPU;
339   unsigned Arch;
340   unsigned EmittedArch;
341   SmallVector<AttributeItem, 64> Contents;
342 
343   const MCSection *AttributeSection;
344 
345   AttributeItem *getAttributeItem(unsigned Attribute) {
346     for (size_t i = 0; i < Contents.size(); ++i)
347       if (Contents[i].Tag == Attribute)
348         return &Contents[i];
349     return nullptr;
350   }
351 
352   void setAttributeItem(unsigned Attribute, unsigned Value,
353                         bool OverwriteExisting) {
354     // Look for existing attribute item
355     if (AttributeItem *Item = getAttributeItem(Attribute)) {
356       if (!OverwriteExisting)
357         return;
358       Item->Type = AttributeItem::NumericAttribute;
359       Item->IntValue = Value;
360       return;
361     }
362 
363     // Create new attribute item
364     AttributeItem Item = {
365       AttributeItem::NumericAttribute,
366       Attribute,
367       Value,
368       StringRef("")
369     };
370     Contents.push_back(Item);
371   }
372 
373   void setAttributeItem(unsigned Attribute, StringRef Value,
374                         bool OverwriteExisting) {
375     // Look for existing attribute item
376     if (AttributeItem *Item = getAttributeItem(Attribute)) {
377       if (!OverwriteExisting)
378         return;
379       Item->Type = AttributeItem::TextAttribute;
380       Item->StringValue = Value;
381       return;
382     }
383 
384     // Create new attribute item
385     AttributeItem Item = {
386       AttributeItem::TextAttribute,
387       Attribute,
388       0,
389       Value
390     };
391     Contents.push_back(Item);
392   }
393 
394   void setAttributeItems(unsigned Attribute, unsigned IntValue,
395                          StringRef StringValue, bool OverwriteExisting) {
396     // Look for existing attribute item
397     if (AttributeItem *Item = getAttributeItem(Attribute)) {
398       if (!OverwriteExisting)
399         return;
400       Item->Type = AttributeItem::NumericAndTextAttributes;
401       Item->IntValue = IntValue;
402       Item->StringValue = StringValue;
403       return;
404     }
405 
406     // Create new attribute item
407     AttributeItem Item = {
408       AttributeItem::NumericAndTextAttributes,
409       Attribute,
410       IntValue,
411       StringValue
412     };
413     Contents.push_back(Item);
414   }
415 
416   void emitArchDefaultAttributes();
417   void emitFPUDefaultAttributes();
418 
419   ARMELFStreamer &getStreamer();
420 
421   void emitFnStart() override;
422   void emitFnEnd() override;
423   void emitCantUnwind() override;
424   void emitPersonality(const MCSymbol *Personality) override;
425   void emitPersonalityIndex(unsigned Index) override;
426   void emitHandlerData() override;
427   void emitSetFP(unsigned FpReg, unsigned SpReg, int64_t Offset = 0) override;
428   void emitMovSP(unsigned Reg, int64_t Offset = 0) override;
429   void emitPad(int64_t Offset) override;
430   void emitRegSave(const SmallVectorImpl<unsigned> &RegList,
431                    bool isVector) override;
432   void emitUnwindRaw(int64_t Offset,
433                      const SmallVectorImpl<uint8_t> &Opcodes) override;
434 
435   void switchVendor(StringRef Vendor) override;
436   void emitAttribute(unsigned Attribute, unsigned Value) override;
437   void emitTextAttribute(unsigned Attribute, StringRef String) override;
438   void emitIntTextAttribute(unsigned Attribute, unsigned IntValue,
439                             StringRef StringValue) override;
440   void emitArch(unsigned Arch) override;
441   void emitObjectArch(unsigned Arch) override;
442   void emitFPU(unsigned FPU) override;
443   void emitInst(uint32_t Inst, char Suffix = '\0') override;
444   void finishAttributeSection() override;
445   void emitLabel(MCSymbol *Symbol) override;
446 
447   void AnnotateTLSDescriptorSequence(const MCSymbolRefExpr *SRE) override;
448   void emitThumbSet(MCSymbol *Symbol, const MCExpr *Value) override;
449 
450   size_t calculateContentSize() const;
451 
452 public:
453   ARMTargetELFStreamer(MCStreamer &S)
454     : ARMTargetStreamer(S), CurrentVendor("aeabi"), FPU(ARM::INVALID_FPU),
455       Arch(ARM::INVALID_ARCH), EmittedArch(ARM::INVALID_ARCH),
456       AttributeSection(nullptr) {}
457 };
458 
459 /// Extend the generic ELFStreamer class so that it can emit mapping symbols at
460 /// the appropriate points in the object files. These symbols are defined in the
461 /// ARM ELF ABI: infocenter.arm.com/help/topic/com.arm.../IHI0044D_aaelf.pdf.
462 ///
463 /// In brief: $a, $t or $d should be emitted at the start of each contiguous
464 /// region of ARM code, Thumb code or data in a section. In practice, this
465 /// emission does not rely on explicit assembler directives but on inherent
466 /// properties of the directives doing the emission (e.g. ".byte" is data, "add
467 /// r0, r0, r0" an instruction).
468 ///
469 /// As a result this system is orthogonal to the DataRegion infrastructure used
470 /// by MachO. Beware!
471 class ARMELFStreamer : public MCELFStreamer {
472 public:
473   friend class ARMTargetELFStreamer;
474 
475   ARMELFStreamer(MCContext &Context, MCAsmBackend &TAB, raw_pwrite_stream &OS,
476                  MCCodeEmitter *Emitter, bool IsThumb)
477       : MCELFStreamer(Context, TAB, OS, Emitter), IsThumb(IsThumb),
478         MappingSymbolCounter(0), LastEMS(EMS_None) {
479     Reset();
480   }
481 
482   ~ARMELFStreamer() {}
483 
484   void FinishImpl() override;
485 
486   // ARM exception handling directives
487   void emitFnStart();
488   void emitFnEnd();
489   void emitCantUnwind();
490   void emitPersonality(const MCSymbol *Per);
491   void emitPersonalityIndex(unsigned index);
492   void emitHandlerData();
493   void emitSetFP(unsigned NewFpReg, unsigned NewSpReg, int64_t Offset = 0);
494   void emitMovSP(unsigned Reg, int64_t Offset = 0);
495   void emitPad(int64_t Offset);
496   void emitRegSave(const SmallVectorImpl<unsigned> &RegList, bool isVector);
497   void emitUnwindRaw(int64_t Offset, const SmallVectorImpl<uint8_t> &Opcodes);
498 
499   void ChangeSection(const MCSection *Section,
500                      const MCExpr *Subsection) override {
501     // We have to keep track of the mapping symbol state of any sections we
502     // use. Each one should start off as EMS_None, which is provided as the
503     // default constructor by DenseMap::lookup.
504     LastMappingSymbols[getPreviousSection().first] = LastEMS;
505     LastEMS = LastMappingSymbols.lookup(Section);
506 
507     MCELFStreamer::ChangeSection(Section, Subsection);
508   }
509 
510   /// This function is the one used to emit instruction data into the ELF
511   /// streamer. We override it to add the appropriate mapping symbol if
512   /// necessary.
513   void EmitInstruction(const MCInst& Inst,
514                        const MCSubtargetInfo &STI) override {
515     if (IsThumb)
516       EmitThumbMappingSymbol();
517     else
518       EmitARMMappingSymbol();
519 
520     MCELFStreamer::EmitInstruction(Inst, STI);
521   }
522 
523   void emitInst(uint32_t Inst, char Suffix) {
524     unsigned Size;
525     char Buffer[4];
526     const bool LittleEndian = getContext().getAsmInfo()->isLittleEndian();
527 
528     switch (Suffix) {
529     case '\0':
530       Size = 4;
531 
532       assert(!IsThumb);
533       EmitARMMappingSymbol();
534       for (unsigned II = 0, IE = Size; II != IE; II++) {
535         const unsigned I = LittleEndian ? (Size - II - 1) : II;
536         Buffer[Size - II - 1] = uint8_t(Inst >> I * CHAR_BIT);
537       }
538 
539       break;
540     case 'n':
541     case 'w':
542       Size = (Suffix == 'n' ? 2 : 4);
543 
544       assert(IsThumb);
545       EmitThumbMappingSymbol();
546       for (unsigned II = 0, IE = Size; II != IE; II = II + 2) {
547         const unsigned I0 = LittleEndian ? II + 0 : (Size - II - 1);
548         const unsigned I1 = LittleEndian ? II + 1 : (Size - II - 2);
549         Buffer[Size - II - 2] = uint8_t(Inst >> I0 * CHAR_BIT);
550         Buffer[Size - II - 1] = uint8_t(Inst >> I1 * CHAR_BIT);
551       }
552 
553       break;
554     default:
555       llvm_unreachable("Invalid Suffix");
556     }
557 
558     MCELFStreamer::EmitBytes(StringRef(Buffer, Size));
559   }
560 
561   /// This is one of the functions used to emit data into an ELF section, so the
562   /// ARM streamer overrides it to add the appropriate mapping symbol ($d) if
563   /// necessary.
564   void EmitBytes(StringRef Data) override {
565     EmitDataMappingSymbol();
566     MCELFStreamer::EmitBytes(Data);
567   }
568 
569   /// This is one of the functions used to emit data into an ELF section, so the
570   /// ARM streamer overrides it to add the appropriate mapping symbol ($d) if
571   /// necessary.
572   void EmitValueImpl(const MCExpr *Value, unsigned Size,
573                      const SMLoc &Loc) override {
574     if (const MCSymbolRefExpr *SRE = dyn_cast_or_null<MCSymbolRefExpr>(Value))
575       if (SRE->getKind() == MCSymbolRefExpr::VK_ARM_SBREL && !(Size == 4))
576         getContext().FatalError(Loc, "relocated expression must be 32-bit");
577 
578     EmitDataMappingSymbol();
579     MCELFStreamer::EmitValueImpl(Value, Size);
580   }
581 
582   void EmitAssemblerFlag(MCAssemblerFlag Flag) override {
583     MCELFStreamer::EmitAssemblerFlag(Flag);
584 
585     switch (Flag) {
586     case MCAF_SyntaxUnified:
587       return; // no-op here.
588     case MCAF_Code16:
589       IsThumb = true;
590       return; // Change to Thumb mode
591     case MCAF_Code32:
592       IsThumb = false;
593       return; // Change to ARM mode
594     case MCAF_Code64:
595       return;
596     case MCAF_SubsectionsViaSymbols:
597       return;
598     }
599   }
600 
601 private:
602   enum ElfMappingSymbol {
603     EMS_None,
604     EMS_ARM,
605     EMS_Thumb,
606     EMS_Data
607   };
608 
609   void EmitDataMappingSymbol() {
610     if (LastEMS == EMS_Data) return;
611     EmitMappingSymbol("$d");
612     LastEMS = EMS_Data;
613   }
614 
615   void EmitThumbMappingSymbol() {
616     if (LastEMS == EMS_Thumb) return;
617     EmitMappingSymbol("$t");
618     LastEMS = EMS_Thumb;
619   }
620 
621   void EmitARMMappingSymbol() {
622     if (LastEMS == EMS_ARM) return;
623     EmitMappingSymbol("$a");
624     LastEMS = EMS_ARM;
625   }
626 
627   void EmitMappingSymbol(StringRef Name) {
628     MCSymbol *Start = getContext().CreateTempSymbol();
629     EmitLabel(Start);
630 
631     MCSymbol *Symbol =
632       getContext().GetOrCreateSymbol(Name + "." +
633                                      Twine(MappingSymbolCounter++));
634 
635     MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
636     MCELF::SetType(SD, ELF::STT_NOTYPE);
637     MCELF::SetBinding(SD, ELF::STB_LOCAL);
638     SD.setExternal(false);
639     AssignSection(Symbol, getCurrentSection().first);
640 
641     const MCExpr *Value = MCSymbolRefExpr::Create(Start, getContext());
642     Symbol->setVariableValue(Value);
643   }
644 
645   void EmitThumbFunc(MCSymbol *Func) override {
646     getAssembler().setIsThumbFunc(Func);
647     EmitSymbolAttribute(Func, MCSA_ELF_TypeFunction);
648   }
649 
650   // Helper functions for ARM exception handling directives
651   void Reset();
652 
653   void EmitPersonalityFixup(StringRef Name);
654   void FlushPendingOffset();
655   void FlushUnwindOpcodes(bool NoHandlerData);
656 
657   void SwitchToEHSection(const char *Prefix, unsigned Type, unsigned Flags,
658                          SectionKind Kind, const MCSymbol &Fn);
659   void SwitchToExTabSection(const MCSymbol &FnStart);
660   void SwitchToExIdxSection(const MCSymbol &FnStart);
661 
662   void EmitFixup(const MCExpr *Expr, MCFixupKind Kind);
663 
664   bool IsThumb;
665   int64_t MappingSymbolCounter;
666 
667   DenseMap<const MCSection *, ElfMappingSymbol> LastMappingSymbols;
668   ElfMappingSymbol LastEMS;
669 
670   // ARM Exception Handling Frame Information
671   MCSymbol *ExTab;
672   MCSymbol *FnStart;
673   const MCSymbol *Personality;
674   unsigned PersonalityIndex;
675   unsigned FPReg; // Frame pointer register
676   int64_t FPOffset; // Offset: (final frame pointer) - (initial $sp)
677   int64_t SPOffset; // Offset: (final $sp) - (initial $sp)
678   int64_t PendingOffset; // Offset: (final $sp) - (emitted $sp)
679   bool UsedFP;
680   bool CantUnwind;
681   SmallVector<uint8_t, 64> Opcodes;
682   UnwindOpcodeAssembler UnwindOpAsm;
683 };
684 } // end anonymous namespace
685 
686 ARMELFStreamer &ARMTargetELFStreamer::getStreamer() {
687   return static_cast<ARMELFStreamer &>(Streamer);
688 }
689 
690 void ARMTargetELFStreamer::emitFnStart() { getStreamer().emitFnStart(); }
691 void ARMTargetELFStreamer::emitFnEnd() { getStreamer().emitFnEnd(); }
692 void ARMTargetELFStreamer::emitCantUnwind() { getStreamer().emitCantUnwind(); }
693 void ARMTargetELFStreamer::emitPersonality(const MCSymbol *Personality) {
694   getStreamer().emitPersonality(Personality);
695 }
696 void ARMTargetELFStreamer::emitPersonalityIndex(unsigned Index) {
697   getStreamer().emitPersonalityIndex(Index);
698 }
699 void ARMTargetELFStreamer::emitHandlerData() {
700   getStreamer().emitHandlerData();
701 }
702 void ARMTargetELFStreamer::emitSetFP(unsigned FpReg, unsigned SpReg,
703                                      int64_t Offset) {
704   getStreamer().emitSetFP(FpReg, SpReg, Offset);
705 }
706 void ARMTargetELFStreamer::emitMovSP(unsigned Reg, int64_t Offset) {
707   getStreamer().emitMovSP(Reg, Offset);
708 }
709 void ARMTargetELFStreamer::emitPad(int64_t Offset) {
710   getStreamer().emitPad(Offset);
711 }
712 void ARMTargetELFStreamer::emitRegSave(const SmallVectorImpl<unsigned> &RegList,
713                                        bool isVector) {
714   getStreamer().emitRegSave(RegList, isVector);
715 }
716 void ARMTargetELFStreamer::emitUnwindRaw(int64_t Offset,
717                                       const SmallVectorImpl<uint8_t> &Opcodes) {
718   getStreamer().emitUnwindRaw(Offset, Opcodes);
719 }
720 void ARMTargetELFStreamer::switchVendor(StringRef Vendor) {
721   assert(!Vendor.empty() && "Vendor cannot be empty.");
722 
723   if (CurrentVendor == Vendor)
724     return;
725 
726   if (!CurrentVendor.empty())
727     finishAttributeSection();
728 
729   assert(Contents.empty() &&
730          ".ARM.attributes should be flushed before changing vendor");
731   CurrentVendor = Vendor;
732 
733 }
734 void ARMTargetELFStreamer::emitAttribute(unsigned Attribute, unsigned Value) {
735   setAttributeItem(Attribute, Value, /* OverwriteExisting= */ true);
736 }
737 void ARMTargetELFStreamer::emitTextAttribute(unsigned Attribute,
738                                              StringRef Value) {
739   setAttributeItem(Attribute, Value, /* OverwriteExisting= */ true);
740 }
741 void ARMTargetELFStreamer::emitIntTextAttribute(unsigned Attribute,
742                                                 unsigned IntValue,
743                                                 StringRef StringValue) {
744   setAttributeItems(Attribute, IntValue, StringValue,
745                     /* OverwriteExisting= */ true);
746 }
747 void ARMTargetELFStreamer::emitArch(unsigned Value) {
748   Arch = Value;
749 }
750 void ARMTargetELFStreamer::emitObjectArch(unsigned Value) {
751   EmittedArch = Value;
752 }
753 void ARMTargetELFStreamer::emitArchDefaultAttributes() {
754   using namespace ARMBuildAttrs;
755 
756   setAttributeItem(CPU_name, GetArchDefaultCPUName(Arch), false);
757   if (EmittedArch == ARM::INVALID_ARCH)
758     setAttributeItem(CPU_arch, GetArchDefaultCPUArch(Arch), false);
759   else
760     setAttributeItem(CPU_arch, GetArchDefaultCPUArch(EmittedArch), false);
761 
762   switch (Arch) {
763   case ARM::ARMV2:
764   case ARM::ARMV2A:
765   case ARM::ARMV3:
766   case ARM::ARMV3M:
767   case ARM::ARMV4:
768   case ARM::ARMV5:
769     setAttributeItem(ARM_ISA_use, Allowed, false);
770     break;
771 
772   case ARM::ARMV4T:
773   case ARM::ARMV5T:
774   case ARM::ARMV5TE:
775   case ARM::ARMV6:
776   case ARM::ARMV6J:
777     setAttributeItem(ARM_ISA_use, Allowed, false);
778     setAttributeItem(THUMB_ISA_use, Allowed, false);
779     break;
780 
781   case ARM::ARMV6T2:
782     setAttributeItem(ARM_ISA_use, Allowed, false);
783     setAttributeItem(THUMB_ISA_use, AllowThumb32, false);
784     break;
785 
786   case ARM::ARMV6K:
787   case ARM::ARMV6Z:
788   case ARM::ARMV6ZK:
789     setAttributeItem(ARM_ISA_use, Allowed, false);
790     setAttributeItem(THUMB_ISA_use, Allowed, false);
791     setAttributeItem(Virtualization_use, AllowTZ, false);
792     break;
793 
794   case ARM::ARMV6M:
795     setAttributeItem(THUMB_ISA_use, Allowed, false);
796     break;
797 
798   case ARM::ARMV7:
799     setAttributeItem(THUMB_ISA_use, AllowThumb32, false);
800     break;
801 
802   case ARM::ARMV7A:
803     setAttributeItem(CPU_arch_profile, ApplicationProfile, false);
804     setAttributeItem(ARM_ISA_use, Allowed, false);
805     setAttributeItem(THUMB_ISA_use, AllowThumb32, false);
806     break;
807 
808   case ARM::ARMV7R:
809     setAttributeItem(CPU_arch_profile, RealTimeProfile, false);
810     setAttributeItem(ARM_ISA_use, Allowed, false);
811     setAttributeItem(THUMB_ISA_use, AllowThumb32, false);
812     break;
813 
814   case ARM::ARMV7M:
815     setAttributeItem(CPU_arch_profile, MicroControllerProfile, false);
816     setAttributeItem(THUMB_ISA_use, AllowThumb32, false);
817     break;
818 
819   case ARM::ARMV8A:
820   case ARM::ARMV8_1A:
821     setAttributeItem(CPU_arch_profile, ApplicationProfile, false);
822     setAttributeItem(ARM_ISA_use, Allowed, false);
823     setAttributeItem(THUMB_ISA_use, AllowThumb32, false);
824     setAttributeItem(MPextension_use, Allowed, false);
825     setAttributeItem(Virtualization_use, AllowTZVirtualization, false);
826     break;
827 
828   case ARM::IWMMXT:
829     setAttributeItem(ARM_ISA_use, Allowed, false);
830     setAttributeItem(THUMB_ISA_use, Allowed, false);
831     setAttributeItem(WMMX_arch, AllowWMMXv1, false);
832     break;
833 
834   case ARM::IWMMXT2:
835     setAttributeItem(ARM_ISA_use, Allowed, false);
836     setAttributeItem(THUMB_ISA_use, Allowed, false);
837     setAttributeItem(WMMX_arch, AllowWMMXv2, false);
838     break;
839 
840   default:
841     report_fatal_error("Unknown Arch: " + Twine(Arch));
842     break;
843   }
844 }
845 void ARMTargetELFStreamer::emitFPU(unsigned Value) {
846   FPU = Value;
847 }
848 void ARMTargetELFStreamer::emitFPUDefaultAttributes() {
849   switch (FPU) {
850   case ARM::VFP:
851   case ARM::VFPV2:
852     setAttributeItem(ARMBuildAttrs::FP_arch,
853                      ARMBuildAttrs::AllowFPv2,
854                      /* OverwriteExisting= */ false);
855     break;
856 
857   case ARM::VFPV3:
858     setAttributeItem(ARMBuildAttrs::FP_arch,
859                      ARMBuildAttrs::AllowFPv3A,
860                      /* OverwriteExisting= */ false);
861     break;
862 
863   case ARM::VFPV3_D16:
864     setAttributeItem(ARMBuildAttrs::FP_arch,
865                      ARMBuildAttrs::AllowFPv3B,
866                      /* OverwriteExisting= */ false);
867     break;
868 
869   case ARM::VFPV4:
870     setAttributeItem(ARMBuildAttrs::FP_arch,
871                      ARMBuildAttrs::AllowFPv4A,
872                      /* OverwriteExisting= */ false);
873     break;
874 
875   case ARM::VFPV4_D16:
876     setAttributeItem(ARMBuildAttrs::FP_arch,
877                      ARMBuildAttrs::AllowFPv4B,
878                      /* OverwriteExisting= */ false);
879     break;
880 
881   case ARM::FP_ARMV8:
882     setAttributeItem(ARMBuildAttrs::FP_arch,
883                      ARMBuildAttrs::AllowFPARMv8A,
884                      /* OverwriteExisting= */ false);
885     break;
886 
887   // FPV5_D16 is identical to FP_ARMV8 except for the number of D registers, so
888   // uses the FP_ARMV8_D16 build attribute.
889   case ARM::FPV5_D16:
890     setAttributeItem(ARMBuildAttrs::FP_arch,
891                      ARMBuildAttrs::AllowFPARMv8B,
892                      /* OverwriteExisting= */ false);
893     break;
894 
895   case ARM::NEON:
896     setAttributeItem(ARMBuildAttrs::FP_arch,
897                      ARMBuildAttrs::AllowFPv3A,
898                      /* OverwriteExisting= */ false);
899     setAttributeItem(ARMBuildAttrs::Advanced_SIMD_arch,
900                      ARMBuildAttrs::AllowNeon,
901                      /* OverwriteExisting= */ false);
902     break;
903 
904   case ARM::NEON_VFPV4:
905     setAttributeItem(ARMBuildAttrs::FP_arch,
906                      ARMBuildAttrs::AllowFPv4A,
907                      /* OverwriteExisting= */ false);
908     setAttributeItem(ARMBuildAttrs::Advanced_SIMD_arch,
909                      ARMBuildAttrs::AllowNeon2,
910                      /* OverwriteExisting= */ false);
911     break;
912 
913   case ARM::NEON_FP_ARMV8:
914   case ARM::CRYPTO_NEON_FP_ARMV8:
915     setAttributeItem(ARMBuildAttrs::FP_arch,
916                      ARMBuildAttrs::AllowFPARMv8A,
917                      /* OverwriteExisting= */ false);
918     // 'Advanced_SIMD_arch' must be emitted not here, but within
919     // ARMAsmPrinter::emitAttributes(), depending on hasV8Ops() and hasV8_1a()
920     break;
921 
922   case ARM::SOFTVFP:
923     break;
924 
925   default:
926     report_fatal_error("Unknown FPU: " + Twine(FPU));
927     break;
928   }
929 }
930 size_t ARMTargetELFStreamer::calculateContentSize() const {
931   size_t Result = 0;
932   for (size_t i = 0; i < Contents.size(); ++i) {
933     AttributeItem item = Contents[i];
934     switch (item.Type) {
935     case AttributeItem::HiddenAttribute:
936       break;
937     case AttributeItem::NumericAttribute:
938       Result += getULEB128Size(item.Tag);
939       Result += getULEB128Size(item.IntValue);
940       break;
941     case AttributeItem::TextAttribute:
942       Result += getULEB128Size(item.Tag);
943       Result += item.StringValue.size() + 1; // string + '\0'
944       break;
945     case AttributeItem::NumericAndTextAttributes:
946       Result += getULEB128Size(item.Tag);
947       Result += getULEB128Size(item.IntValue);
948       Result += item.StringValue.size() + 1; // string + '\0';
949       break;
950     }
951   }
952   return Result;
953 }
954 void ARMTargetELFStreamer::finishAttributeSection() {
955   // <format-version>
956   // [ <section-length> "vendor-name"
957   // [ <file-tag> <size> <attribute>*
958   //   | <section-tag> <size> <section-number>* 0 <attribute>*
959   //   | <symbol-tag> <size> <symbol-number>* 0 <attribute>*
960   //   ]+
961   // ]*
962 
963   if (FPU != ARM::INVALID_FPU)
964     emitFPUDefaultAttributes();
965 
966   if (Arch != ARM::INVALID_ARCH)
967     emitArchDefaultAttributes();
968 
969   if (Contents.empty())
970     return;
971 
972   std::sort(Contents.begin(), Contents.end(), AttributeItem::LessTag);
973 
974   ARMELFStreamer &Streamer = getStreamer();
975 
976   // Switch to .ARM.attributes section
977   if (AttributeSection) {
978     Streamer.SwitchSection(AttributeSection);
979   } else {
980     AttributeSection = Streamer.getContext().getELFSection(
981         ".ARM.attributes", ELF::SHT_ARM_ATTRIBUTES, 0);
982     Streamer.SwitchSection(AttributeSection);
983 
984     // Format version
985     Streamer.EmitIntValue(0x41, 1);
986   }
987 
988   // Vendor size + Vendor name + '\0'
989   const size_t VendorHeaderSize = 4 + CurrentVendor.size() + 1;
990 
991   // Tag + Tag Size
992   const size_t TagHeaderSize = 1 + 4;
993 
994   const size_t ContentsSize = calculateContentSize();
995 
996   Streamer.EmitIntValue(VendorHeaderSize + TagHeaderSize + ContentsSize, 4);
997   Streamer.EmitBytes(CurrentVendor);
998   Streamer.EmitIntValue(0, 1); // '\0'
999 
1000   Streamer.EmitIntValue(ARMBuildAttrs::File, 1);
1001   Streamer.EmitIntValue(TagHeaderSize + ContentsSize, 4);
1002 
1003   // Size should have been accounted for already, now
1004   // emit each field as its type (ULEB or String)
1005   for (size_t i = 0; i < Contents.size(); ++i) {
1006     AttributeItem item = Contents[i];
1007     Streamer.EmitULEB128IntValue(item.Tag);
1008     switch (item.Type) {
1009     default: llvm_unreachable("Invalid attribute type");
1010     case AttributeItem::NumericAttribute:
1011       Streamer.EmitULEB128IntValue(item.IntValue);
1012       break;
1013     case AttributeItem::TextAttribute:
1014       Streamer.EmitBytes(item.StringValue);
1015       Streamer.EmitIntValue(0, 1); // '\0'
1016       break;
1017     case AttributeItem::NumericAndTextAttributes:
1018       Streamer.EmitULEB128IntValue(item.IntValue);
1019       Streamer.EmitBytes(item.StringValue);
1020       Streamer.EmitIntValue(0, 1); // '\0'
1021       break;
1022     }
1023   }
1024 
1025   Contents.clear();
1026   FPU = ARM::INVALID_FPU;
1027 }
1028 
1029 void ARMTargetELFStreamer::emitLabel(MCSymbol *Symbol) {
1030   ARMELFStreamer &Streamer = getStreamer();
1031   if (!Streamer.IsThumb)
1032     return;
1033 
1034   const MCSymbolData &SD = Streamer.getOrCreateSymbolData(Symbol);
1035   unsigned Type = MCELF::GetType(SD);
1036   if (Type == ELF_STT_Func || Type == ELF_STT_GnuIFunc)
1037     Streamer.EmitThumbFunc(Symbol);
1038 }
1039 
1040 void
1041 ARMTargetELFStreamer::AnnotateTLSDescriptorSequence(const MCSymbolRefExpr *S) {
1042   getStreamer().EmitFixup(S, FK_Data_4);
1043 }
1044 
1045 void ARMTargetELFStreamer::emitThumbSet(MCSymbol *Symbol, const MCExpr *Value) {
1046   if (const MCSymbolRefExpr *SRE = dyn_cast<MCSymbolRefExpr>(Value)) {
1047     const MCSymbol &Sym = SRE->getSymbol();
1048     if (!Sym.isDefined()) {
1049       getStreamer().EmitAssignment(Symbol, Value);
1050       return;
1051     }
1052   }
1053 
1054   getStreamer().EmitThumbFunc(Symbol);
1055   getStreamer().EmitAssignment(Symbol, Value);
1056 }
1057 
1058 void ARMTargetELFStreamer::emitInst(uint32_t Inst, char Suffix) {
1059   getStreamer().emitInst(Inst, Suffix);
1060 }
1061 
1062 void ARMELFStreamer::FinishImpl() {
1063   MCTargetStreamer &TS = *getTargetStreamer();
1064   ARMTargetStreamer &ATS = static_cast<ARMTargetStreamer &>(TS);
1065   ATS.finishAttributeSection();
1066 
1067   MCELFStreamer::FinishImpl();
1068 }
1069 
1070 inline void ARMELFStreamer::SwitchToEHSection(const char *Prefix,
1071                                               unsigned Type,
1072                                               unsigned Flags,
1073                                               SectionKind Kind,
1074                                               const MCSymbol &Fn) {
1075   const MCSectionELF &FnSection =
1076     static_cast<const MCSectionELF &>(Fn.getSection());
1077 
1078   // Create the name for new section
1079   StringRef FnSecName(FnSection.getSectionName());
1080   SmallString<128> EHSecName(Prefix);
1081   if (FnSecName != ".text") {
1082     EHSecName += FnSecName;
1083   }
1084 
1085   // Get .ARM.extab or .ARM.exidx section
1086   const MCSymbol *Group = FnSection.getGroup();
1087   if (Group)
1088     Flags |= ELF::SHF_GROUP;
1089   const MCSectionELF *EHSection =
1090       getContext().getELFSection(EHSecName, Type, Flags, 0, Group,
1091                                  FnSection.getUniqueID(), nullptr, &FnSection);
1092 
1093   assert(EHSection && "Failed to get the required EH section");
1094 
1095   // Switch to .ARM.extab or .ARM.exidx section
1096   SwitchSection(EHSection);
1097   EmitCodeAlignment(4);
1098 }
1099 
1100 inline void ARMELFStreamer::SwitchToExTabSection(const MCSymbol &FnStart) {
1101   SwitchToEHSection(".ARM.extab",
1102                     ELF::SHT_PROGBITS,
1103                     ELF::SHF_ALLOC,
1104                     SectionKind::getDataRel(),
1105                     FnStart);
1106 }
1107 
1108 inline void ARMELFStreamer::SwitchToExIdxSection(const MCSymbol &FnStart) {
1109   SwitchToEHSection(".ARM.exidx",
1110                     ELF::SHT_ARM_EXIDX,
1111                     ELF::SHF_ALLOC | ELF::SHF_LINK_ORDER,
1112                     SectionKind::getDataRel(),
1113                     FnStart);
1114 }
1115 void ARMELFStreamer::EmitFixup(const MCExpr *Expr, MCFixupKind Kind) {
1116   MCDataFragment *Frag = getOrCreateDataFragment();
1117   Frag->getFixups().push_back(MCFixup::Create(Frag->getContents().size(), Expr,
1118                                               Kind));
1119 }
1120 
1121 void ARMELFStreamer::Reset() {
1122   ExTab = nullptr;
1123   FnStart = nullptr;
1124   Personality = nullptr;
1125   PersonalityIndex = ARM::EHABI::NUM_PERSONALITY_INDEX;
1126   FPReg = ARM::SP;
1127   FPOffset = 0;
1128   SPOffset = 0;
1129   PendingOffset = 0;
1130   UsedFP = false;
1131   CantUnwind = false;
1132 
1133   Opcodes.clear();
1134   UnwindOpAsm.Reset();
1135 }
1136 
1137 void ARMELFStreamer::emitFnStart() {
1138   assert(FnStart == nullptr);
1139   FnStart = getContext().CreateTempSymbol();
1140   EmitLabel(FnStart);
1141 }
1142 
1143 void ARMELFStreamer::emitFnEnd() {
1144   assert(FnStart && ".fnstart must precedes .fnend");
1145 
1146   // Emit unwind opcodes if there is no .handlerdata directive
1147   if (!ExTab && !CantUnwind)
1148     FlushUnwindOpcodes(true);
1149 
1150   // Emit the exception index table entry
1151   SwitchToExIdxSection(*FnStart);
1152 
1153   if (PersonalityIndex < ARM::EHABI::NUM_PERSONALITY_INDEX)
1154     EmitPersonalityFixup(GetAEABIUnwindPersonalityName(PersonalityIndex));
1155 
1156   const MCSymbolRefExpr *FnStartRef =
1157     MCSymbolRefExpr::Create(FnStart,
1158                             MCSymbolRefExpr::VK_ARM_PREL31,
1159                             getContext());
1160 
1161   EmitValue(FnStartRef, 4);
1162 
1163   if (CantUnwind) {
1164     EmitIntValue(ARM::EHABI::EXIDX_CANTUNWIND, 4);
1165   } else if (ExTab) {
1166     // Emit a reference to the unwind opcodes in the ".ARM.extab" section.
1167     const MCSymbolRefExpr *ExTabEntryRef =
1168       MCSymbolRefExpr::Create(ExTab,
1169                               MCSymbolRefExpr::VK_ARM_PREL31,
1170                               getContext());
1171     EmitValue(ExTabEntryRef, 4);
1172   } else {
1173     // For the __aeabi_unwind_cpp_pr0, we have to emit the unwind opcodes in
1174     // the second word of exception index table entry.  The size of the unwind
1175     // opcodes should always be 4 bytes.
1176     assert(PersonalityIndex == ARM::EHABI::AEABI_UNWIND_CPP_PR0 &&
1177            "Compact model must use __aeabi_unwind_cpp_pr0 as personality");
1178     assert(Opcodes.size() == 4u &&
1179            "Unwind opcode size for __aeabi_unwind_cpp_pr0 must be equal to 4");
1180     uint64_t Intval = Opcodes[0] |
1181                       Opcodes[1] << 8 |
1182                       Opcodes[2] << 16 |
1183                       Opcodes[3] << 24;
1184     EmitIntValue(Intval, Opcodes.size());
1185   }
1186 
1187   // Switch to the section containing FnStart
1188   SwitchSection(&FnStart->getSection());
1189 
1190   // Clean exception handling frame information
1191   Reset();
1192 }
1193 
1194 void ARMELFStreamer::emitCantUnwind() { CantUnwind = true; }
1195 
1196 // Add the R_ARM_NONE fixup at the same position
1197 void ARMELFStreamer::EmitPersonalityFixup(StringRef Name) {
1198   const MCSymbol *PersonalitySym = getContext().GetOrCreateSymbol(Name);
1199 
1200   const MCSymbolRefExpr *PersonalityRef = MCSymbolRefExpr::Create(
1201       PersonalitySym, MCSymbolRefExpr::VK_ARM_NONE, getContext());
1202 
1203   visitUsedExpr(*PersonalityRef);
1204   MCDataFragment *DF = getOrCreateDataFragment();
1205   DF->getFixups().push_back(MCFixup::Create(DF->getContents().size(),
1206                                             PersonalityRef,
1207                                             MCFixup::getKindForSize(4, false)));
1208 }
1209 
1210 void ARMELFStreamer::FlushPendingOffset() {
1211   if (PendingOffset != 0) {
1212     UnwindOpAsm.EmitSPOffset(-PendingOffset);
1213     PendingOffset = 0;
1214   }
1215 }
1216 
1217 void ARMELFStreamer::FlushUnwindOpcodes(bool NoHandlerData) {
1218   // Emit the unwind opcode to restore $sp.
1219   if (UsedFP) {
1220     const MCRegisterInfo *MRI = getContext().getRegisterInfo();
1221     int64_t LastRegSaveSPOffset = SPOffset - PendingOffset;
1222     UnwindOpAsm.EmitSPOffset(LastRegSaveSPOffset - FPOffset);
1223     UnwindOpAsm.EmitSetSP(MRI->getEncodingValue(FPReg));
1224   } else {
1225     FlushPendingOffset();
1226   }
1227 
1228   // Finalize the unwind opcode sequence
1229   UnwindOpAsm.Finalize(PersonalityIndex, Opcodes);
1230 
1231   // For compact model 0, we have to emit the unwind opcodes in the .ARM.exidx
1232   // section.  Thus, we don't have to create an entry in the .ARM.extab
1233   // section.
1234   if (NoHandlerData && PersonalityIndex == ARM::EHABI::AEABI_UNWIND_CPP_PR0)
1235     return;
1236 
1237   // Switch to .ARM.extab section.
1238   SwitchToExTabSection(*FnStart);
1239 
1240   // Create .ARM.extab label for offset in .ARM.exidx
1241   assert(!ExTab);
1242   ExTab = getContext().CreateTempSymbol();
1243   EmitLabel(ExTab);
1244 
1245   // Emit personality
1246   if (Personality) {
1247     const MCSymbolRefExpr *PersonalityRef =
1248       MCSymbolRefExpr::Create(Personality,
1249                               MCSymbolRefExpr::VK_ARM_PREL31,
1250                               getContext());
1251 
1252     EmitValue(PersonalityRef, 4);
1253   }
1254 
1255   // Emit unwind opcodes
1256   assert((Opcodes.size() % 4) == 0 &&
1257          "Unwind opcode size for __aeabi_cpp_unwind_pr0 must be multiple of 4");
1258   for (unsigned I = 0; I != Opcodes.size(); I += 4) {
1259     uint64_t Intval = Opcodes[I] |
1260                       Opcodes[I + 1] << 8 |
1261                       Opcodes[I + 2] << 16 |
1262                       Opcodes[I + 3] << 24;
1263     EmitIntValue(Intval, 4);
1264   }
1265 
1266   // According to ARM EHABI section 9.2, if the __aeabi_unwind_cpp_pr1() or
1267   // __aeabi_unwind_cpp_pr2() is used, then the handler data must be emitted
1268   // after the unwind opcodes.  The handler data consists of several 32-bit
1269   // words, and should be terminated by zero.
1270   //
1271   // In case that the .handlerdata directive is not specified by the
1272   // programmer, we should emit zero to terminate the handler data.
1273   if (NoHandlerData && !Personality)
1274     EmitIntValue(0, 4);
1275 }
1276 
1277 void ARMELFStreamer::emitHandlerData() { FlushUnwindOpcodes(false); }
1278 
1279 void ARMELFStreamer::emitPersonality(const MCSymbol *Per) {
1280   Personality = Per;
1281   UnwindOpAsm.setPersonality(Per);
1282 }
1283 
1284 void ARMELFStreamer::emitPersonalityIndex(unsigned Index) {
1285   assert(Index < ARM::EHABI::NUM_PERSONALITY_INDEX && "invalid index");
1286   PersonalityIndex = Index;
1287 }
1288 
1289 void ARMELFStreamer::emitSetFP(unsigned NewFPReg, unsigned NewSPReg,
1290                                int64_t Offset) {
1291   assert((NewSPReg == ARM::SP || NewSPReg == FPReg) &&
1292          "the operand of .setfp directive should be either $sp or $fp");
1293 
1294   UsedFP = true;
1295   FPReg = NewFPReg;
1296 
1297   if (NewSPReg == ARM::SP)
1298     FPOffset = SPOffset + Offset;
1299   else
1300     FPOffset += Offset;
1301 }
1302 
1303 void ARMELFStreamer::emitMovSP(unsigned Reg, int64_t Offset) {
1304   assert((Reg != ARM::SP && Reg != ARM::PC) &&
1305          "the operand of .movsp cannot be either sp or pc");
1306   assert(FPReg == ARM::SP && "current FP must be SP");
1307 
1308   FlushPendingOffset();
1309 
1310   FPReg = Reg;
1311   FPOffset = SPOffset + Offset;
1312 
1313   const MCRegisterInfo *MRI = getContext().getRegisterInfo();
1314   UnwindOpAsm.EmitSetSP(MRI->getEncodingValue(FPReg));
1315 }
1316 
1317 void ARMELFStreamer::emitPad(int64_t Offset) {
1318   // Track the change of the $sp offset
1319   SPOffset -= Offset;
1320 
1321   // To squash multiple .pad directives, we should delay the unwind opcode
1322   // until the .save, .vsave, .handlerdata, or .fnend directives.
1323   PendingOffset -= Offset;
1324 }
1325 
1326 void ARMELFStreamer::emitRegSave(const SmallVectorImpl<unsigned> &RegList,
1327                                  bool IsVector) {
1328   // Collect the registers in the register list
1329   unsigned Count = 0;
1330   uint32_t Mask = 0;
1331   const MCRegisterInfo *MRI = getContext().getRegisterInfo();
1332   for (size_t i = 0; i < RegList.size(); ++i) {
1333     unsigned Reg = MRI->getEncodingValue(RegList[i]);
1334     assert(Reg < (IsVector ? 32U : 16U) && "Register out of range");
1335     unsigned Bit = (1u << Reg);
1336     if ((Mask & Bit) == 0) {
1337       Mask |= Bit;
1338       ++Count;
1339     }
1340   }
1341 
1342   // Track the change the $sp offset: For the .save directive, the
1343   // corresponding push instruction will decrease the $sp by (4 * Count).
1344   // For the .vsave directive, the corresponding vpush instruction will
1345   // decrease $sp by (8 * Count).
1346   SPOffset -= Count * (IsVector ? 8 : 4);
1347 
1348   // Emit the opcode
1349   FlushPendingOffset();
1350   if (IsVector)
1351     UnwindOpAsm.EmitVFPRegSave(Mask);
1352   else
1353     UnwindOpAsm.EmitRegSave(Mask);
1354 }
1355 
1356 void ARMELFStreamer::emitUnwindRaw(int64_t Offset,
1357                                    const SmallVectorImpl<uint8_t> &Opcodes) {
1358   FlushPendingOffset();
1359   SPOffset = SPOffset - Offset;
1360   UnwindOpAsm.EmitRaw(Opcodes);
1361 }
1362 
1363 namespace llvm {
1364 
1365 MCTargetStreamer *createARMTargetAsmStreamer(MCStreamer &S,
1366                                              formatted_raw_ostream &OS,
1367                                              MCInstPrinter *InstPrint,
1368                                              bool isVerboseAsm) {
1369   return new ARMTargetAsmStreamer(S, OS, *InstPrint, isVerboseAsm);
1370 }
1371 
1372 MCTargetStreamer *createARMNullTargetStreamer(MCStreamer &S) {
1373   return new ARMTargetStreamer(S);
1374 }
1375 
1376 MCTargetStreamer *createARMObjectTargetStreamer(MCStreamer &S,
1377                                                 const MCSubtargetInfo &STI) {
1378   Triple TT(STI.getTargetTriple());
1379   if (TT.getObjectFormat() == Triple::ELF)
1380     return new ARMTargetELFStreamer(S);
1381   return new ARMTargetStreamer(S);
1382 }
1383 
1384 MCELFStreamer *createARMELFStreamer(MCContext &Context, MCAsmBackend &TAB,
1385                                     raw_pwrite_stream &OS,
1386                                     MCCodeEmitter *Emitter, bool RelaxAll,
1387                                     bool IsThumb) {
1388     ARMELFStreamer *S = new ARMELFStreamer(Context, TAB, OS, Emitter, IsThumb);
1389     // FIXME: This should eventually end up somewhere else where more
1390     // intelligent flag decisions can be made. For now we are just maintaining
1391     // the status quo for ARM and setting EF_ARM_EABI_VER5 as the default.
1392     S->getAssembler().setELFHeaderEFlags(ELF::EF_ARM_EABI_VER5);
1393 
1394     if (RelaxAll)
1395       S->getAssembler().setRelaxAll(true);
1396     return S;
1397   }
1398 
1399 }
1400 
1401 
1402