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     EmitLabel(Symbol, Loc, F);
663     Symbol->setType(ELF::STT_NOTYPE);
664     Symbol->setBinding(ELF::STB_LOCAL);
665     Symbol->setExternal(false);
666     Symbol->setOffset(Offset);
667   }
668 
669   void EmitThumbFunc(MCSymbol *Func) override {
670     getAssembler().setIsThumbFunc(Func);
671     EmitSymbolAttribute(Func, MCSA_ELF_TypeFunction);
672   }
673 
674   // Helper functions for ARM exception handling directives
675   void EHReset();
676 
677   // Reset state between object emissions
678   void reset() override;
679 
680   void EmitPersonalityFixup(StringRef Name);
681   void FlushPendingOffset();
682   void FlushUnwindOpcodes(bool NoHandlerData);
683 
684   void SwitchToEHSection(StringRef Prefix, unsigned Type, unsigned Flags,
685                          SectionKind Kind, const MCSymbol &Fn);
686   void SwitchToExTabSection(const MCSymbol &FnStart);
687   void SwitchToExIdxSection(const MCSymbol &FnStart);
688 
689   void EmitFixup(const MCExpr *Expr, MCFixupKind Kind);
690 
691   bool IsThumb;
692   bool IsAndroid;
693   int64_t MappingSymbolCounter = 0;
694 
695   DenseMap<const MCSection *, std::unique_ptr<ElfMappingSymbolInfo>>
696       LastMappingSymbols;
697 
698   std::unique_ptr<ElfMappingSymbolInfo> LastEMSInfo;
699 
700   // ARM Exception Handling Frame Information
701   MCSymbol *ExTab;
702   MCSymbol *FnStart;
703   const MCSymbol *Personality;
704   unsigned PersonalityIndex;
705   unsigned FPReg; // Frame pointer register
706   int64_t FPOffset; // Offset: (final frame pointer) - (initial $sp)
707   int64_t SPOffset; // Offset: (final $sp) - (initial $sp)
708   int64_t PendingOffset; // Offset: (final $sp) - (emitted $sp)
709   bool UsedFP;
710   bool CantUnwind;
711   SmallVector<uint8_t, 64> Opcodes;
712   UnwindOpcodeAssembler UnwindOpAsm;
713 };
714 
715 } // end anonymous namespace
716 
717 ARMELFStreamer &ARMTargetELFStreamer::getStreamer() {
718   return static_cast<ARMELFStreamer &>(Streamer);
719 }
720 
721 void ARMTargetELFStreamer::emitFnStart() { getStreamer().emitFnStart(); }
722 void ARMTargetELFStreamer::emitFnEnd() { getStreamer().emitFnEnd(); }
723 void ARMTargetELFStreamer::emitCantUnwind() { getStreamer().emitCantUnwind(); }
724 
725 void ARMTargetELFStreamer::emitPersonality(const MCSymbol *Personality) {
726   getStreamer().emitPersonality(Personality);
727 }
728 
729 void ARMTargetELFStreamer::emitPersonalityIndex(unsigned Index) {
730   getStreamer().emitPersonalityIndex(Index);
731 }
732 
733 void ARMTargetELFStreamer::emitHandlerData() {
734   getStreamer().emitHandlerData();
735 }
736 
737 void ARMTargetELFStreamer::emitSetFP(unsigned FpReg, unsigned SpReg,
738                                      int64_t Offset) {
739   getStreamer().emitSetFP(FpReg, SpReg, Offset);
740 }
741 
742 void ARMTargetELFStreamer::emitMovSP(unsigned Reg, int64_t Offset) {
743   getStreamer().emitMovSP(Reg, Offset);
744 }
745 
746 void ARMTargetELFStreamer::emitPad(int64_t Offset) {
747   getStreamer().emitPad(Offset);
748 }
749 
750 void ARMTargetELFStreamer::emitRegSave(const SmallVectorImpl<unsigned> &RegList,
751                                        bool isVector) {
752   getStreamer().emitRegSave(RegList, isVector);
753 }
754 
755 void ARMTargetELFStreamer::emitUnwindRaw(int64_t Offset,
756                                       const SmallVectorImpl<uint8_t> &Opcodes) {
757   getStreamer().emitUnwindRaw(Offset, Opcodes);
758 }
759 
760 void ARMTargetELFStreamer::switchVendor(StringRef Vendor) {
761   assert(!Vendor.empty() && "Vendor cannot be empty.");
762 
763   if (CurrentVendor == Vendor)
764     return;
765 
766   if (!CurrentVendor.empty())
767     finishAttributeSection();
768 
769   assert(Contents.empty() &&
770          ".ARM.attributes should be flushed before changing vendor");
771   CurrentVendor = Vendor;
772 
773 }
774 
775 void ARMTargetELFStreamer::emitAttribute(unsigned Attribute, unsigned Value) {
776   setAttributeItem(Attribute, Value, /* OverwriteExisting= */ true);
777 }
778 
779 void ARMTargetELFStreamer::emitTextAttribute(unsigned Attribute,
780                                              StringRef Value) {
781   setAttributeItem(Attribute, Value, /* OverwriteExisting= */ true);
782 }
783 
784 void ARMTargetELFStreamer::emitIntTextAttribute(unsigned Attribute,
785                                                 unsigned IntValue,
786                                                 StringRef StringValue) {
787   setAttributeItems(Attribute, IntValue, StringValue,
788                     /* OverwriteExisting= */ true);
789 }
790 
791 void ARMTargetELFStreamer::emitArch(ARM::ArchKind Value) {
792   Arch = Value;
793 }
794 
795 void ARMTargetELFStreamer::emitObjectArch(ARM::ArchKind Value) {
796   EmittedArch = Value;
797 }
798 
799 void ARMTargetELFStreamer::emitArchDefaultAttributes() {
800   using namespace ARMBuildAttrs;
801 
802   setAttributeItem(CPU_name,
803                    ARM::getCPUAttr(Arch),
804                    false);
805 
806   if (EmittedArch == ARM::ArchKind::INVALID)
807     setAttributeItem(CPU_arch,
808                      ARM::getArchAttr(Arch),
809                      false);
810   else
811     setAttributeItem(CPU_arch,
812                      ARM::getArchAttr(EmittedArch),
813                      false);
814 
815   switch (Arch) {
816   case ARM::ArchKind::ARMV2:
817   case ARM::ArchKind::ARMV2A:
818   case ARM::ArchKind::ARMV3:
819   case ARM::ArchKind::ARMV3M:
820   case ARM::ArchKind::ARMV4:
821     setAttributeItem(ARM_ISA_use, Allowed, false);
822     break;
823 
824   case ARM::ArchKind::ARMV4T:
825   case ARM::ArchKind::ARMV5T:
826   case ARM::ArchKind::ARMV5TE:
827   case ARM::ArchKind::ARMV6:
828     setAttributeItem(ARM_ISA_use, Allowed, false);
829     setAttributeItem(THUMB_ISA_use, Allowed, false);
830     break;
831 
832   case ARM::ArchKind::ARMV6T2:
833     setAttributeItem(ARM_ISA_use, Allowed, false);
834     setAttributeItem(THUMB_ISA_use, AllowThumb32, false);
835     break;
836 
837   case ARM::ArchKind::ARMV6K:
838   case ARM::ArchKind::ARMV6KZ:
839     setAttributeItem(ARM_ISA_use, Allowed, false);
840     setAttributeItem(THUMB_ISA_use, Allowed, false);
841     setAttributeItem(Virtualization_use, AllowTZ, false);
842     break;
843 
844   case ARM::ArchKind::ARMV6M:
845     setAttributeItem(THUMB_ISA_use, Allowed, false);
846     break;
847 
848   case ARM::ArchKind::ARMV7A:
849     setAttributeItem(CPU_arch_profile, ApplicationProfile, false);
850     setAttributeItem(ARM_ISA_use, Allowed, false);
851     setAttributeItem(THUMB_ISA_use, AllowThumb32, false);
852     break;
853 
854   case ARM::ArchKind::ARMV7R:
855     setAttributeItem(CPU_arch_profile, RealTimeProfile, false);
856     setAttributeItem(ARM_ISA_use, Allowed, false);
857     setAttributeItem(THUMB_ISA_use, AllowThumb32, false);
858     break;
859 
860   case ARM::ArchKind::ARMV7EM:
861   case ARM::ArchKind::ARMV7M:
862     setAttributeItem(CPU_arch_profile, MicroControllerProfile, false);
863     setAttributeItem(THUMB_ISA_use, AllowThumb32, false);
864     break;
865 
866   case ARM::ArchKind::ARMV8A:
867   case ARM::ArchKind::ARMV8_1A:
868   case ARM::ArchKind::ARMV8_2A:
869   case ARM::ArchKind::ARMV8_3A:
870   case ARM::ArchKind::ARMV8_4A:
871   case ARM::ArchKind::ARMV8_5A:
872     setAttributeItem(CPU_arch_profile, ApplicationProfile, false);
873     setAttributeItem(ARM_ISA_use, Allowed, false);
874     setAttributeItem(THUMB_ISA_use, AllowThumb32, false);
875     setAttributeItem(MPextension_use, Allowed, false);
876     setAttributeItem(Virtualization_use, AllowTZVirtualization, false);
877     break;
878 
879   case ARM::ArchKind::ARMV8MBaseline:
880   case ARM::ArchKind::ARMV8MMainline:
881     setAttributeItem(THUMB_ISA_use, AllowThumbDerived, false);
882     setAttributeItem(CPU_arch_profile, MicroControllerProfile, false);
883     break;
884 
885   case ARM::ArchKind::IWMMXT:
886     setAttributeItem(ARM_ISA_use, Allowed, false);
887     setAttributeItem(THUMB_ISA_use, Allowed, false);
888     setAttributeItem(WMMX_arch, AllowWMMXv1, false);
889     break;
890 
891   case ARM::ArchKind::IWMMXT2:
892     setAttributeItem(ARM_ISA_use, Allowed, false);
893     setAttributeItem(THUMB_ISA_use, Allowed, false);
894     setAttributeItem(WMMX_arch, AllowWMMXv2, false);
895     break;
896 
897   default:
898     report_fatal_error("Unknown Arch: " + Twine(ARM::getArchName(Arch)));
899     break;
900   }
901 }
902 
903 void ARMTargetELFStreamer::emitFPU(unsigned Value) {
904   FPU = Value;
905 }
906 
907 void ARMTargetELFStreamer::emitFPUDefaultAttributes() {
908   switch (FPU) {
909   case ARM::FK_VFP:
910   case ARM::FK_VFPV2:
911     setAttributeItem(ARMBuildAttrs::FP_arch,
912                      ARMBuildAttrs::AllowFPv2,
913                      /* OverwriteExisting= */ false);
914     break;
915 
916   case ARM::FK_VFPV3:
917     setAttributeItem(ARMBuildAttrs::FP_arch,
918                      ARMBuildAttrs::AllowFPv3A,
919                      /* OverwriteExisting= */ false);
920     break;
921 
922   case ARM::FK_VFPV3_FP16:
923     setAttributeItem(ARMBuildAttrs::FP_arch,
924                      ARMBuildAttrs::AllowFPv3A,
925                      /* OverwriteExisting= */ false);
926     setAttributeItem(ARMBuildAttrs::FP_HP_extension,
927                      ARMBuildAttrs::AllowHPFP,
928                      /* OverwriteExisting= */ false);
929     break;
930 
931   case ARM::FK_VFPV3_D16:
932     setAttributeItem(ARMBuildAttrs::FP_arch,
933                      ARMBuildAttrs::AllowFPv3B,
934                      /* OverwriteExisting= */ false);
935     break;
936 
937   case ARM::FK_VFPV3_D16_FP16:
938     setAttributeItem(ARMBuildAttrs::FP_arch,
939                      ARMBuildAttrs::AllowFPv3B,
940                      /* OverwriteExisting= */ false);
941     setAttributeItem(ARMBuildAttrs::FP_HP_extension,
942                      ARMBuildAttrs::AllowHPFP,
943                      /* OverwriteExisting= */ false);
944     break;
945 
946   case ARM::FK_VFPV3XD:
947     setAttributeItem(ARMBuildAttrs::FP_arch,
948                      ARMBuildAttrs::AllowFPv3B,
949                      /* OverwriteExisting= */ false);
950     break;
951   case ARM::FK_VFPV3XD_FP16:
952     setAttributeItem(ARMBuildAttrs::FP_arch,
953                      ARMBuildAttrs::AllowFPv3B,
954                      /* OverwriteExisting= */ false);
955     setAttributeItem(ARMBuildAttrs::FP_HP_extension,
956                      ARMBuildAttrs::AllowHPFP,
957                      /* OverwriteExisting= */ false);
958     break;
959 
960   case ARM::FK_VFPV4:
961     setAttributeItem(ARMBuildAttrs::FP_arch,
962                      ARMBuildAttrs::AllowFPv4A,
963                      /* OverwriteExisting= */ false);
964     break;
965 
966   // ABI_HardFP_use is handled in ARMAsmPrinter, so _SP_D16 is treated the same
967   // as _D16 here.
968   case ARM::FK_FPV4_SP_D16:
969   case ARM::FK_VFPV4_D16:
970     setAttributeItem(ARMBuildAttrs::FP_arch,
971                      ARMBuildAttrs::AllowFPv4B,
972                      /* OverwriteExisting= */ false);
973     break;
974 
975   case ARM::FK_FP_ARMV8:
976     setAttributeItem(ARMBuildAttrs::FP_arch,
977                      ARMBuildAttrs::AllowFPARMv8A,
978                      /* OverwriteExisting= */ false);
979     break;
980 
981   // FPV5_D16 is identical to FP_ARMV8 except for the number of D registers, so
982   // uses the FP_ARMV8_D16 build attribute.
983   case ARM::FK_FPV5_SP_D16:
984   case ARM::FK_FPV5_D16:
985     setAttributeItem(ARMBuildAttrs::FP_arch,
986                      ARMBuildAttrs::AllowFPARMv8B,
987                      /* OverwriteExisting= */ false);
988     break;
989 
990   case ARM::FK_NEON:
991     setAttributeItem(ARMBuildAttrs::FP_arch,
992                      ARMBuildAttrs::AllowFPv3A,
993                      /* OverwriteExisting= */ false);
994     setAttributeItem(ARMBuildAttrs::Advanced_SIMD_arch,
995                      ARMBuildAttrs::AllowNeon,
996                      /* OverwriteExisting= */ false);
997     break;
998 
999   case ARM::FK_NEON_FP16:
1000     setAttributeItem(ARMBuildAttrs::FP_arch,
1001                      ARMBuildAttrs::AllowFPv3A,
1002                      /* OverwriteExisting= */ false);
1003     setAttributeItem(ARMBuildAttrs::Advanced_SIMD_arch,
1004                      ARMBuildAttrs::AllowNeon,
1005                      /* OverwriteExisting= */ false);
1006     setAttributeItem(ARMBuildAttrs::FP_HP_extension,
1007                      ARMBuildAttrs::AllowHPFP,
1008                      /* OverwriteExisting= */ false);
1009     break;
1010 
1011   case ARM::FK_NEON_VFPV4:
1012     setAttributeItem(ARMBuildAttrs::FP_arch,
1013                      ARMBuildAttrs::AllowFPv4A,
1014                      /* OverwriteExisting= */ false);
1015     setAttributeItem(ARMBuildAttrs::Advanced_SIMD_arch,
1016                      ARMBuildAttrs::AllowNeon2,
1017                      /* OverwriteExisting= */ false);
1018     break;
1019 
1020   case ARM::FK_NEON_FP_ARMV8:
1021   case ARM::FK_CRYPTO_NEON_FP_ARMV8:
1022     setAttributeItem(ARMBuildAttrs::FP_arch,
1023                      ARMBuildAttrs::AllowFPARMv8A,
1024                      /* OverwriteExisting= */ false);
1025     // 'Advanced_SIMD_arch' must be emitted not here, but within
1026     // ARMAsmPrinter::emitAttributes(), depending on hasV8Ops() and hasV8_1a()
1027     break;
1028 
1029   case ARM::FK_SOFTVFP:
1030   case ARM::FK_NONE:
1031     break;
1032 
1033   default:
1034     report_fatal_error("Unknown FPU: " + Twine(FPU));
1035     break;
1036   }
1037 }
1038 
1039 size_t ARMTargetELFStreamer::calculateContentSize() const {
1040   size_t Result = 0;
1041   for (size_t i = 0; i < Contents.size(); ++i) {
1042     AttributeItem item = Contents[i];
1043     switch (item.Type) {
1044     case AttributeItem::HiddenAttribute:
1045       break;
1046     case AttributeItem::NumericAttribute:
1047       Result += getULEB128Size(item.Tag);
1048       Result += getULEB128Size(item.IntValue);
1049       break;
1050     case AttributeItem::TextAttribute:
1051       Result += getULEB128Size(item.Tag);
1052       Result += item.StringValue.size() + 1; // string + '\0'
1053       break;
1054     case AttributeItem::NumericAndTextAttributes:
1055       Result += getULEB128Size(item.Tag);
1056       Result += getULEB128Size(item.IntValue);
1057       Result += item.StringValue.size() + 1; // string + '\0';
1058       break;
1059     }
1060   }
1061   return Result;
1062 }
1063 
1064 void ARMTargetELFStreamer::finishAttributeSection() {
1065   // <format-version>
1066   // [ <section-length> "vendor-name"
1067   // [ <file-tag> <size> <attribute>*
1068   //   | <section-tag> <size> <section-number>* 0 <attribute>*
1069   //   | <symbol-tag> <size> <symbol-number>* 0 <attribute>*
1070   //   ]+
1071   // ]*
1072 
1073   if (FPU != ARM::FK_INVALID)
1074     emitFPUDefaultAttributes();
1075 
1076   if (Arch != ARM::ArchKind::INVALID)
1077     emitArchDefaultAttributes();
1078 
1079   if (Contents.empty())
1080     return;
1081 
1082   llvm::sort(Contents, AttributeItem::LessTag);
1083 
1084   ARMELFStreamer &Streamer = getStreamer();
1085 
1086   // Switch to .ARM.attributes section
1087   if (AttributeSection) {
1088     Streamer.SwitchSection(AttributeSection);
1089   } else {
1090     AttributeSection = Streamer.getContext().getELFSection(
1091         ".ARM.attributes", ELF::SHT_ARM_ATTRIBUTES, 0);
1092     Streamer.SwitchSection(AttributeSection);
1093 
1094     // Format version
1095     Streamer.EmitIntValue(0x41, 1);
1096   }
1097 
1098   // Vendor size + Vendor name + '\0'
1099   const size_t VendorHeaderSize = 4 + CurrentVendor.size() + 1;
1100 
1101   // Tag + Tag Size
1102   const size_t TagHeaderSize = 1 + 4;
1103 
1104   const size_t ContentsSize = calculateContentSize();
1105 
1106   Streamer.EmitIntValue(VendorHeaderSize + TagHeaderSize + ContentsSize, 4);
1107   Streamer.EmitBytes(CurrentVendor);
1108   Streamer.EmitIntValue(0, 1); // '\0'
1109 
1110   Streamer.EmitIntValue(ARMBuildAttrs::File, 1);
1111   Streamer.EmitIntValue(TagHeaderSize + ContentsSize, 4);
1112 
1113   // Size should have been accounted for already, now
1114   // emit each field as its type (ULEB or String)
1115   for (size_t i = 0; i < Contents.size(); ++i) {
1116     AttributeItem item = Contents[i];
1117     Streamer.EmitULEB128IntValue(item.Tag);
1118     switch (item.Type) {
1119     default: llvm_unreachable("Invalid attribute type");
1120     case AttributeItem::NumericAttribute:
1121       Streamer.EmitULEB128IntValue(item.IntValue);
1122       break;
1123     case AttributeItem::TextAttribute:
1124       Streamer.EmitBytes(item.StringValue);
1125       Streamer.EmitIntValue(0, 1); // '\0'
1126       break;
1127     case AttributeItem::NumericAndTextAttributes:
1128       Streamer.EmitULEB128IntValue(item.IntValue);
1129       Streamer.EmitBytes(item.StringValue);
1130       Streamer.EmitIntValue(0, 1); // '\0'
1131       break;
1132     }
1133   }
1134 
1135   Contents.clear();
1136   FPU = ARM::FK_INVALID;
1137 }
1138 
1139 void ARMTargetELFStreamer::emitLabel(MCSymbol *Symbol) {
1140   ARMELFStreamer &Streamer = getStreamer();
1141   if (!Streamer.IsThumb)
1142     return;
1143 
1144   Streamer.getAssembler().registerSymbol(*Symbol);
1145   unsigned Type = cast<MCSymbolELF>(Symbol)->getType();
1146   if (Type == ELF::STT_FUNC || Type == ELF::STT_GNU_IFUNC)
1147     Streamer.EmitThumbFunc(Symbol);
1148 }
1149 
1150 void
1151 ARMTargetELFStreamer::AnnotateTLSDescriptorSequence(const MCSymbolRefExpr *S) {
1152   getStreamer().EmitFixup(S, FK_Data_4);
1153 }
1154 
1155 void ARMTargetELFStreamer::emitThumbSet(MCSymbol *Symbol, const MCExpr *Value) {
1156   if (const MCSymbolRefExpr *SRE = dyn_cast<MCSymbolRefExpr>(Value)) {
1157     const MCSymbol &Sym = SRE->getSymbol();
1158     if (!Sym.isDefined()) {
1159       getStreamer().EmitAssignment(Symbol, Value);
1160       return;
1161     }
1162   }
1163 
1164   getStreamer().EmitThumbFunc(Symbol);
1165   getStreamer().EmitAssignment(Symbol, Value);
1166 }
1167 
1168 void ARMTargetELFStreamer::emitInst(uint32_t Inst, char Suffix) {
1169   getStreamer().emitInst(Inst, Suffix);
1170 }
1171 
1172 void ARMTargetELFStreamer::reset() { AttributeSection = nullptr; }
1173 
1174 void ARMELFStreamer::FinishImpl() {
1175   MCTargetStreamer &TS = *getTargetStreamer();
1176   ARMTargetStreamer &ATS = static_cast<ARMTargetStreamer &>(TS);
1177   ATS.finishAttributeSection();
1178 
1179   MCELFStreamer::FinishImpl();
1180 }
1181 
1182 void ARMELFStreamer::reset() {
1183   MCTargetStreamer &TS = *getTargetStreamer();
1184   ARMTargetStreamer &ATS = static_cast<ARMTargetStreamer &>(TS);
1185   ATS.reset();
1186   MappingSymbolCounter = 0;
1187   MCELFStreamer::reset();
1188   LastMappingSymbols.clear();
1189   LastEMSInfo.reset();
1190   // MCELFStreamer clear's the assembler's e_flags. However, for
1191   // arm we manually set the ABI version on streamer creation, so
1192   // do the same here
1193   getAssembler().setELFHeaderEFlags(ELF::EF_ARM_EABI_VER5);
1194 }
1195 
1196 inline void ARMELFStreamer::SwitchToEHSection(StringRef Prefix,
1197                                               unsigned Type,
1198                                               unsigned Flags,
1199                                               SectionKind Kind,
1200                                               const MCSymbol &Fn) {
1201   const MCSectionELF &FnSection =
1202     static_cast<const MCSectionELF &>(Fn.getSection());
1203 
1204   // Create the name for new section
1205   StringRef FnSecName(FnSection.getSectionName());
1206   SmallString<128> EHSecName(Prefix);
1207   if (FnSecName != ".text") {
1208     EHSecName += FnSecName;
1209   }
1210 
1211   // Get .ARM.extab or .ARM.exidx section
1212   const MCSymbolELF *Group = FnSection.getGroup();
1213   if (Group)
1214     Flags |= ELF::SHF_GROUP;
1215   MCSectionELF *EHSection = getContext().getELFSection(
1216       EHSecName, Type, Flags, 0, Group, FnSection.getUniqueID(),
1217       static_cast<const MCSymbolELF *>(&Fn));
1218 
1219   assert(EHSection && "Failed to get the required EH section");
1220 
1221   // Switch to .ARM.extab or .ARM.exidx section
1222   SwitchSection(EHSection);
1223   EmitCodeAlignment(4);
1224 }
1225 
1226 inline void ARMELFStreamer::SwitchToExTabSection(const MCSymbol &FnStart) {
1227   SwitchToEHSection(".ARM.extab", ELF::SHT_PROGBITS, ELF::SHF_ALLOC,
1228                     SectionKind::getData(), FnStart);
1229 }
1230 
1231 inline void ARMELFStreamer::SwitchToExIdxSection(const MCSymbol &FnStart) {
1232   SwitchToEHSection(".ARM.exidx", ELF::SHT_ARM_EXIDX,
1233                     ELF::SHF_ALLOC | ELF::SHF_LINK_ORDER,
1234                     SectionKind::getData(), FnStart);
1235 }
1236 
1237 void ARMELFStreamer::EmitFixup(const MCExpr *Expr, MCFixupKind Kind) {
1238   MCDataFragment *Frag = getOrCreateDataFragment();
1239   Frag->getFixups().push_back(MCFixup::create(Frag->getContents().size(), Expr,
1240                                               Kind));
1241 }
1242 
1243 void ARMELFStreamer::EHReset() {
1244   ExTab = nullptr;
1245   FnStart = nullptr;
1246   Personality = nullptr;
1247   PersonalityIndex = ARM::EHABI::NUM_PERSONALITY_INDEX;
1248   FPReg = ARM::SP;
1249   FPOffset = 0;
1250   SPOffset = 0;
1251   PendingOffset = 0;
1252   UsedFP = false;
1253   CantUnwind = false;
1254 
1255   Opcodes.clear();
1256   UnwindOpAsm.Reset();
1257 }
1258 
1259 void ARMELFStreamer::emitFnStart() {
1260   assert(FnStart == nullptr);
1261   FnStart = getContext().createTempSymbol();
1262   EmitLabel(FnStart);
1263 }
1264 
1265 void ARMELFStreamer::emitFnEnd() {
1266   assert(FnStart && ".fnstart must precedes .fnend");
1267 
1268   // Emit unwind opcodes if there is no .handlerdata directive
1269   if (!ExTab && !CantUnwind)
1270     FlushUnwindOpcodes(true);
1271 
1272   // Emit the exception index table entry
1273   SwitchToExIdxSection(*FnStart);
1274 
1275   // The EHABI requires a dependency preserving R_ARM_NONE relocation to the
1276   // personality routine to protect it from an arbitrary platform's static
1277   // linker garbage collection. We disable this for Android where the unwinder
1278   // is either dynamically linked or directly references the personality
1279   // routine.
1280   if (PersonalityIndex < ARM::EHABI::NUM_PERSONALITY_INDEX && !IsAndroid)
1281     EmitPersonalityFixup(GetAEABIUnwindPersonalityName(PersonalityIndex));
1282 
1283   const MCSymbolRefExpr *FnStartRef =
1284     MCSymbolRefExpr::create(FnStart,
1285                             MCSymbolRefExpr::VK_ARM_PREL31,
1286                             getContext());
1287 
1288   EmitValue(FnStartRef, 4);
1289 
1290   if (CantUnwind) {
1291     EmitIntValue(ARM::EHABI::EXIDX_CANTUNWIND, 4);
1292   } else if (ExTab) {
1293     // Emit a reference to the unwind opcodes in the ".ARM.extab" section.
1294     const MCSymbolRefExpr *ExTabEntryRef =
1295       MCSymbolRefExpr::create(ExTab,
1296                               MCSymbolRefExpr::VK_ARM_PREL31,
1297                               getContext());
1298     EmitValue(ExTabEntryRef, 4);
1299   } else {
1300     // For the __aeabi_unwind_cpp_pr0, we have to emit the unwind opcodes in
1301     // the second word of exception index table entry.  The size of the unwind
1302     // opcodes should always be 4 bytes.
1303     assert(PersonalityIndex == ARM::EHABI::AEABI_UNWIND_CPP_PR0 &&
1304            "Compact model must use __aeabi_unwind_cpp_pr0 as personality");
1305     assert(Opcodes.size() == 4u &&
1306            "Unwind opcode size for __aeabi_unwind_cpp_pr0 must be equal to 4");
1307     uint64_t Intval = Opcodes[0] |
1308                       Opcodes[1] << 8 |
1309                       Opcodes[2] << 16 |
1310                       Opcodes[3] << 24;
1311     EmitIntValue(Intval, Opcodes.size());
1312   }
1313 
1314   // Switch to the section containing FnStart
1315   SwitchSection(&FnStart->getSection());
1316 
1317   // Clean exception handling frame information
1318   EHReset();
1319 }
1320 
1321 void ARMELFStreamer::emitCantUnwind() { CantUnwind = true; }
1322 
1323 // Add the R_ARM_NONE fixup at the same position
1324 void ARMELFStreamer::EmitPersonalityFixup(StringRef Name) {
1325   const MCSymbol *PersonalitySym = getContext().getOrCreateSymbol(Name);
1326 
1327   const MCSymbolRefExpr *PersonalityRef = MCSymbolRefExpr::create(
1328       PersonalitySym, MCSymbolRefExpr::VK_ARM_NONE, getContext());
1329 
1330   visitUsedExpr(*PersonalityRef);
1331   MCDataFragment *DF = getOrCreateDataFragment();
1332   DF->getFixups().push_back(MCFixup::create(DF->getContents().size(),
1333                                             PersonalityRef,
1334                                             MCFixup::getKindForSize(4, false)));
1335 }
1336 
1337 void ARMELFStreamer::FlushPendingOffset() {
1338   if (PendingOffset != 0) {
1339     UnwindOpAsm.EmitSPOffset(-PendingOffset);
1340     PendingOffset = 0;
1341   }
1342 }
1343 
1344 void ARMELFStreamer::FlushUnwindOpcodes(bool NoHandlerData) {
1345   // Emit the unwind opcode to restore $sp.
1346   if (UsedFP) {
1347     const MCRegisterInfo *MRI = getContext().getRegisterInfo();
1348     int64_t LastRegSaveSPOffset = SPOffset - PendingOffset;
1349     UnwindOpAsm.EmitSPOffset(LastRegSaveSPOffset - FPOffset);
1350     UnwindOpAsm.EmitSetSP(MRI->getEncodingValue(FPReg));
1351   } else {
1352     FlushPendingOffset();
1353   }
1354 
1355   // Finalize the unwind opcode sequence
1356   UnwindOpAsm.Finalize(PersonalityIndex, Opcodes);
1357 
1358   // For compact model 0, we have to emit the unwind opcodes in the .ARM.exidx
1359   // section.  Thus, we don't have to create an entry in the .ARM.extab
1360   // section.
1361   if (NoHandlerData && PersonalityIndex == ARM::EHABI::AEABI_UNWIND_CPP_PR0)
1362     return;
1363 
1364   // Switch to .ARM.extab section.
1365   SwitchToExTabSection(*FnStart);
1366 
1367   // Create .ARM.extab label for offset in .ARM.exidx
1368   assert(!ExTab);
1369   ExTab = getContext().createTempSymbol();
1370   EmitLabel(ExTab);
1371 
1372   // Emit personality
1373   if (Personality) {
1374     const MCSymbolRefExpr *PersonalityRef =
1375       MCSymbolRefExpr::create(Personality,
1376                               MCSymbolRefExpr::VK_ARM_PREL31,
1377                               getContext());
1378 
1379     EmitValue(PersonalityRef, 4);
1380   }
1381 
1382   // Emit unwind opcodes
1383   assert((Opcodes.size() % 4) == 0 &&
1384          "Unwind opcode size for __aeabi_cpp_unwind_pr0 must be multiple of 4");
1385   for (unsigned I = 0; I != Opcodes.size(); I += 4) {
1386     uint64_t Intval = Opcodes[I] |
1387                       Opcodes[I + 1] << 8 |
1388                       Opcodes[I + 2] << 16 |
1389                       Opcodes[I + 3] << 24;
1390     EmitIntValue(Intval, 4);
1391   }
1392 
1393   // According to ARM EHABI section 9.2, if the __aeabi_unwind_cpp_pr1() or
1394   // __aeabi_unwind_cpp_pr2() is used, then the handler data must be emitted
1395   // after the unwind opcodes.  The handler data consists of several 32-bit
1396   // words, and should be terminated by zero.
1397   //
1398   // In case that the .handlerdata directive is not specified by the
1399   // programmer, we should emit zero to terminate the handler data.
1400   if (NoHandlerData && !Personality)
1401     EmitIntValue(0, 4);
1402 }
1403 
1404 void ARMELFStreamer::emitHandlerData() { FlushUnwindOpcodes(false); }
1405 
1406 void ARMELFStreamer::emitPersonality(const MCSymbol *Per) {
1407   Personality = Per;
1408   UnwindOpAsm.setPersonality(Per);
1409 }
1410 
1411 void ARMELFStreamer::emitPersonalityIndex(unsigned Index) {
1412   assert(Index < ARM::EHABI::NUM_PERSONALITY_INDEX && "invalid index");
1413   PersonalityIndex = Index;
1414 }
1415 
1416 void ARMELFStreamer::emitSetFP(unsigned NewFPReg, unsigned NewSPReg,
1417                                int64_t Offset) {
1418   assert((NewSPReg == ARM::SP || NewSPReg == FPReg) &&
1419          "the operand of .setfp directive should be either $sp or $fp");
1420 
1421   UsedFP = true;
1422   FPReg = NewFPReg;
1423 
1424   if (NewSPReg == ARM::SP)
1425     FPOffset = SPOffset + Offset;
1426   else
1427     FPOffset += Offset;
1428 }
1429 
1430 void ARMELFStreamer::emitMovSP(unsigned Reg, int64_t Offset) {
1431   assert((Reg != ARM::SP && Reg != ARM::PC) &&
1432          "the operand of .movsp cannot be either sp or pc");
1433   assert(FPReg == ARM::SP && "current FP must be SP");
1434 
1435   FlushPendingOffset();
1436 
1437   FPReg = Reg;
1438   FPOffset = SPOffset + Offset;
1439 
1440   const MCRegisterInfo *MRI = getContext().getRegisterInfo();
1441   UnwindOpAsm.EmitSetSP(MRI->getEncodingValue(FPReg));
1442 }
1443 
1444 void ARMELFStreamer::emitPad(int64_t Offset) {
1445   // Track the change of the $sp offset
1446   SPOffset -= Offset;
1447 
1448   // To squash multiple .pad directives, we should delay the unwind opcode
1449   // until the .save, .vsave, .handlerdata, or .fnend directives.
1450   PendingOffset -= Offset;
1451 }
1452 
1453 void ARMELFStreamer::emitRegSave(const SmallVectorImpl<unsigned> &RegList,
1454                                  bool IsVector) {
1455   // Collect the registers in the register list
1456   unsigned Count = 0;
1457   uint32_t Mask = 0;
1458   const MCRegisterInfo *MRI = getContext().getRegisterInfo();
1459   for (size_t i = 0; i < RegList.size(); ++i) {
1460     unsigned Reg = MRI->getEncodingValue(RegList[i]);
1461     assert(Reg < (IsVector ? 32U : 16U) && "Register out of range");
1462     unsigned Bit = (1u << Reg);
1463     if ((Mask & Bit) == 0) {
1464       Mask |= Bit;
1465       ++Count;
1466     }
1467   }
1468 
1469   // Track the change the $sp offset: For the .save directive, the
1470   // corresponding push instruction will decrease the $sp by (4 * Count).
1471   // For the .vsave directive, the corresponding vpush instruction will
1472   // decrease $sp by (8 * Count).
1473   SPOffset -= Count * (IsVector ? 8 : 4);
1474 
1475   // Emit the opcode
1476   FlushPendingOffset();
1477   if (IsVector)
1478     UnwindOpAsm.EmitVFPRegSave(Mask);
1479   else
1480     UnwindOpAsm.EmitRegSave(Mask);
1481 }
1482 
1483 void ARMELFStreamer::emitUnwindRaw(int64_t Offset,
1484                                    const SmallVectorImpl<uint8_t> &Opcodes) {
1485   FlushPendingOffset();
1486   SPOffset = SPOffset - Offset;
1487   UnwindOpAsm.EmitRaw(Opcodes);
1488 }
1489 
1490 namespace llvm {
1491 
1492 MCTargetStreamer *createARMTargetAsmStreamer(MCStreamer &S,
1493                                              formatted_raw_ostream &OS,
1494                                              MCInstPrinter *InstPrint,
1495                                              bool isVerboseAsm) {
1496   return new ARMTargetAsmStreamer(S, OS, *InstPrint, isVerboseAsm);
1497 }
1498 
1499 MCTargetStreamer *createARMNullTargetStreamer(MCStreamer &S) {
1500   return new ARMTargetStreamer(S);
1501 }
1502 
1503 MCTargetStreamer *createARMObjectTargetStreamer(MCStreamer &S,
1504                                                 const MCSubtargetInfo &STI) {
1505   const Triple &TT = STI.getTargetTriple();
1506   if (TT.isOSBinFormatELF())
1507     return new ARMTargetELFStreamer(S);
1508   return new ARMTargetStreamer(S);
1509 }
1510 
1511 MCELFStreamer *createARMELFStreamer(MCContext &Context,
1512                                     std::unique_ptr<MCAsmBackend> TAB,
1513                                     std::unique_ptr<MCObjectWriter> OW,
1514                                     std::unique_ptr<MCCodeEmitter> Emitter,
1515                                     bool RelaxAll, bool IsThumb,
1516                                     bool IsAndroid) {
1517   ARMELFStreamer *S =
1518       new ARMELFStreamer(Context, std::move(TAB), std::move(OW),
1519                          std::move(Emitter), IsThumb, IsAndroid);
1520   // FIXME: This should eventually end up somewhere else where more
1521   // intelligent flag decisions can be made. For now we are just maintaining
1522   // the status quo for ARM and setting EF_ARM_EABI_VER5 as the default.
1523   S->getAssembler().setELFHeaderEFlags(ELF::EF_ARM_EABI_VER5);
1524 
1525   if (RelaxAll)
1526     S->getAssembler().setRelaxAll(true);
1527   return S;
1528 }
1529 
1530 } // end namespace llvm
1531