1 //===- lib/MC/ARMELFStreamer.cpp - ELF Object Output for ARM --------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file assembles .s files and emits ARM ELF .o object files. Different
10 // from generic ELF streamer in emitting mapping symbols ($a, $t and $d) to
11 // delimit regions of data and code.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #include "ARMRegisterInfo.h"
16 #include "ARMUnwindOpAsm.h"
17 #include "llvm/ADT/DenseMap.h"
18 #include "llvm/ADT/SmallString.h"
19 #include "llvm/ADT/SmallVector.h"
20 #include "llvm/ADT/StringRef.h"
21 #include "llvm/ADT/Triple.h"
22 #include "llvm/ADT/Twine.h"
23 #include "llvm/BinaryFormat/ELF.h"
24 #include "llvm/MC/MCAsmBackend.h"
25 #include "llvm/MC/MCAsmInfo.h"
26 #include "llvm/MC/MCAssembler.h"
27 #include "llvm/MC/MCCodeEmitter.h"
28 #include "llvm/MC/MCContext.h"
29 #include "llvm/MC/MCELFStreamer.h"
30 #include "llvm/MC/MCExpr.h"
31 #include "llvm/MC/MCFixup.h"
32 #include "llvm/MC/MCFragment.h"
33 #include "llvm/MC/MCInst.h"
34 #include "llvm/MC/MCInstPrinter.h"
35 #include "llvm/MC/MCObjectWriter.h"
36 #include "llvm/MC/MCRegisterInfo.h"
37 #include "llvm/MC/MCSection.h"
38 #include "llvm/MC/MCSectionELF.h"
39 #include "llvm/MC/MCStreamer.h"
40 #include "llvm/MC/MCSubtargetInfo.h"
41 #include "llvm/MC/MCSymbol.h"
42 #include "llvm/MC/MCSymbolELF.h"
43 #include "llvm/MC/SectionKind.h"
44 #include "llvm/Support/ARMBuildAttributes.h"
45 #include "llvm/Support/ARMEHABI.h"
46 #include "llvm/Support/Casting.h"
47 #include "llvm/Support/ErrorHandling.h"
48 #include "llvm/Support/FormattedStream.h"
49 #include "llvm/Support/LEB128.h"
50 #include "llvm/Support/TargetParser.h"
51 #include "llvm/Support/raw_ostream.h"
52 #include <algorithm>
53 #include <cassert>
54 #include <climits>
55 #include <cstddef>
56 #include <cstdint>
57 #include <string>
58 
59 using namespace llvm;
60 
61 static std::string GetAEABIUnwindPersonalityName(unsigned Index) {
62   assert(Index < ARM::EHABI::NUM_PERSONALITY_INDEX &&
63          "Invalid personality index");
64   return (Twine("__aeabi_unwind_cpp_pr") + Twine(Index)).str();
65 }
66 
67 namespace {
68 
69 class ARMELFStreamer;
70 
71 class ARMTargetAsmStreamer : public ARMTargetStreamer {
72   formatted_raw_ostream &OS;
73   MCInstPrinter &InstPrinter;
74   bool IsVerboseAsm;
75 
76   void emitFnStart() override;
77   void emitFnEnd() override;
78   void emitCantUnwind() override;
79   void emitPersonality(const MCSymbol *Personality) override;
80   void emitPersonalityIndex(unsigned Index) override;
81   void emitHandlerData() override;
82   void emitSetFP(unsigned FpReg, unsigned SpReg, int64_t Offset = 0) override;
83   void emitMovSP(unsigned Reg, int64_t Offset = 0) override;
84   void emitPad(int64_t Offset) override;
85   void emitRegSave(const SmallVectorImpl<unsigned> &RegList,
86                    bool isVector) override;
87   void emitUnwindRaw(int64_t Offset,
88                      const SmallVectorImpl<uint8_t> &Opcodes) override;
89 
90   void switchVendor(StringRef Vendor) override;
91   void emitAttribute(unsigned Attribute, unsigned Value) override;
92   void emitTextAttribute(unsigned Attribute, StringRef String) override;
93   void emitIntTextAttribute(unsigned Attribute, unsigned IntValue,
94                             StringRef StringValue) override;
95   void emitArch(ARM::ArchKind Arch) override;
96   void emitArchExtension(uint64_t ArchExt) override;
97   void emitObjectArch(ARM::ArchKind Arch) override;
98   void emitFPU(unsigned FPU) override;
99   void emitInst(uint32_t Inst, char Suffix = '\0') override;
100   void finishAttributeSection() override;
101 
102   void AnnotateTLSDescriptorSequence(const MCSymbolRefExpr *SRE) override;
103   void emitThumbSet(MCSymbol *Symbol, const MCExpr *Value) override;
104 
105 public:
106   ARMTargetAsmStreamer(MCStreamer &S, formatted_raw_ostream &OS,
107                        MCInstPrinter &InstPrinter, bool VerboseAsm);
108 };
109 
110 ARMTargetAsmStreamer::ARMTargetAsmStreamer(MCStreamer &S,
111                                            formatted_raw_ostream &OS,
112                                            MCInstPrinter &InstPrinter,
113                                            bool VerboseAsm)
114     : ARMTargetStreamer(S), OS(OS), InstPrinter(InstPrinter),
115       IsVerboseAsm(VerboseAsm) {}
116 
117 void ARMTargetAsmStreamer::emitFnStart() { OS << "\t.fnstart\n"; }
118 void ARMTargetAsmStreamer::emitFnEnd() { OS << "\t.fnend\n"; }
119 void ARMTargetAsmStreamer::emitCantUnwind() { OS << "\t.cantunwind\n"; }
120 
121 void ARMTargetAsmStreamer::emitPersonality(const MCSymbol *Personality) {
122   OS << "\t.personality " << Personality->getName() << '\n';
123 }
124 
125 void ARMTargetAsmStreamer::emitPersonalityIndex(unsigned Index) {
126   OS << "\t.personalityindex " << Index << '\n';
127 }
128 
129 void ARMTargetAsmStreamer::emitHandlerData() { OS << "\t.handlerdata\n"; }
130 
131 void ARMTargetAsmStreamer::emitSetFP(unsigned FpReg, unsigned SpReg,
132                                      int64_t Offset) {
133   OS << "\t.setfp\t";
134   InstPrinter.printRegName(OS, FpReg);
135   OS << ", ";
136   InstPrinter.printRegName(OS, SpReg);
137   if (Offset)
138     OS << ", #" << Offset;
139   OS << '\n';
140 }
141 
142 void ARMTargetAsmStreamer::emitMovSP(unsigned Reg, int64_t Offset) {
143   assert((Reg != ARM::SP && Reg != ARM::PC) &&
144          "the operand of .movsp cannot be either sp or pc");
145 
146   OS << "\t.movsp\t";
147   InstPrinter.printRegName(OS, Reg);
148   if (Offset)
149     OS << ", #" << Offset;
150   OS << '\n';
151 }
152 
153 void ARMTargetAsmStreamer::emitPad(int64_t Offset) {
154   OS << "\t.pad\t#" << Offset << '\n';
155 }
156 
157 void ARMTargetAsmStreamer::emitRegSave(const SmallVectorImpl<unsigned> &RegList,
158                                        bool isVector) {
159   assert(RegList.size() && "RegList should not be empty");
160   if (isVector)
161     OS << "\t.vsave\t{";
162   else
163     OS << "\t.save\t{";
164 
165   InstPrinter.printRegName(OS, RegList[0]);
166 
167   for (unsigned i = 1, e = RegList.size(); i != e; ++i) {
168     OS << ", ";
169     InstPrinter.printRegName(OS, RegList[i]);
170   }
171 
172   OS << "}\n";
173 }
174 
175 void ARMTargetAsmStreamer::switchVendor(StringRef Vendor) {}
176 
177 void ARMTargetAsmStreamer::emitAttribute(unsigned Attribute, unsigned Value) {
178   OS << "\t.eabi_attribute\t" << Attribute << ", " << Twine(Value);
179   if (IsVerboseAsm) {
180     StringRef Name = 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(uint64_t 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() << "\n";
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 = {AttributeItem::NumericAttribute, Attribute, Value,
332                           std::string(StringRef(""))};
333     Contents.push_back(Item);
334   }
335 
336   void setAttributeItem(unsigned Attribute, StringRef Value,
337                         bool OverwriteExisting) {
338     // Look for existing attribute item
339     if (AttributeItem *Item = getAttributeItem(Attribute)) {
340       if (!OverwriteExisting)
341         return;
342       Item->Type = AttributeItem::TextAttribute;
343       Item->StringValue = std::string(Value);
344       return;
345     }
346 
347     // Create new attribute item
348     AttributeItem Item = {AttributeItem::TextAttribute, Attribute, 0,
349                           std::string(Value)};
350     Contents.push_back(Item);
351   }
352 
353   void setAttributeItems(unsigned Attribute, unsigned IntValue,
354                          StringRef StringValue, bool OverwriteExisting) {
355     // Look for existing attribute item
356     if (AttributeItem *Item = getAttributeItem(Attribute)) {
357       if (!OverwriteExisting)
358         return;
359       Item->Type = AttributeItem::NumericAndTextAttributes;
360       Item->IntValue = IntValue;
361       Item->StringValue = std::string(StringValue);
362       return;
363     }
364 
365     // Create new attribute item
366     AttributeItem Item = {AttributeItem::NumericAndTextAttributes, Attribute,
367                           IntValue, std::string(StringValue)};
368     Contents.push_back(Item);
369   }
370 
371   void emitArchDefaultAttributes();
372   void emitFPUDefaultAttributes();
373 
374   ARMELFStreamer &getStreamer();
375 
376   void emitFnStart() override;
377   void emitFnEnd() override;
378   void emitCantUnwind() override;
379   void emitPersonality(const MCSymbol *Personality) override;
380   void emitPersonalityIndex(unsigned Index) override;
381   void emitHandlerData() override;
382   void emitSetFP(unsigned FpReg, unsigned SpReg, int64_t Offset = 0) override;
383   void emitMovSP(unsigned Reg, int64_t Offset = 0) override;
384   void emitPad(int64_t Offset) override;
385   void emitRegSave(const SmallVectorImpl<unsigned> &RegList,
386                    bool isVector) override;
387   void emitUnwindRaw(int64_t Offset,
388                      const SmallVectorImpl<uint8_t> &Opcodes) override;
389 
390   void switchVendor(StringRef Vendor) override;
391   void emitAttribute(unsigned Attribute, unsigned Value) override;
392   void emitTextAttribute(unsigned Attribute, StringRef String) override;
393   void emitIntTextAttribute(unsigned Attribute, unsigned IntValue,
394                             StringRef StringValue) override;
395   void emitArch(ARM::ArchKind Arch) override;
396   void emitObjectArch(ARM::ArchKind Arch) override;
397   void emitFPU(unsigned FPU) override;
398   void emitInst(uint32_t Inst, char Suffix = '\0') override;
399   void finishAttributeSection() override;
400   void emitLabel(MCSymbol *Symbol) override;
401 
402   void AnnotateTLSDescriptorSequence(const MCSymbolRefExpr *SRE) override;
403   void emitThumbSet(MCSymbol *Symbol, const MCExpr *Value) override;
404 
405   size_t calculateContentSize() const;
406 
407   // Reset state between object emissions
408   void reset() override;
409 
410 public:
411   ARMTargetELFStreamer(MCStreamer &S)
412     : ARMTargetStreamer(S), CurrentVendor("aeabi") {}
413 };
414 
415 /// Extend the generic ELFStreamer class so that it can emit mapping symbols at
416 /// the appropriate points in the object files. These symbols are defined in the
417 /// ARM ELF ABI: infocenter.arm.com/help/topic/com.arm.../IHI0044D_aaelf.pdf.
418 ///
419 /// In brief: $a, $t or $d should be emitted at the start of each contiguous
420 /// region of ARM code, Thumb code or data in a section. In practice, this
421 /// emission does not rely on explicit assembler directives but on inherent
422 /// properties of the directives doing the emission (e.g. ".byte" is data, "add
423 /// r0, r0, r0" an instruction).
424 ///
425 /// As a result this system is orthogonal to the DataRegion infrastructure used
426 /// by MachO. Beware!
427 class ARMELFStreamer : public MCELFStreamer {
428 public:
429   friend class ARMTargetELFStreamer;
430 
431   ARMELFStreamer(MCContext &Context, std::unique_ptr<MCAsmBackend> TAB,
432                  std::unique_ptr<MCObjectWriter> OW,
433                  std::unique_ptr<MCCodeEmitter> Emitter, bool IsThumb,
434                  bool IsAndroid)
435       : MCELFStreamer(Context, std::move(TAB), std::move(OW),
436                       std::move(Emitter)),
437         IsThumb(IsThumb), IsAndroid(IsAndroid) {
438     EHReset();
439   }
440 
441   ~ARMELFStreamer() override = default;
442 
443   void FinishImpl() override;
444 
445   // ARM exception handling directives
446   void emitFnStart();
447   void emitFnEnd();
448   void emitCantUnwind();
449   void emitPersonality(const MCSymbol *Per);
450   void emitPersonalityIndex(unsigned index);
451   void emitHandlerData();
452   void emitSetFP(unsigned NewFpReg, unsigned NewSpReg, int64_t Offset = 0);
453   void emitMovSP(unsigned Reg, int64_t Offset = 0);
454   void emitPad(int64_t Offset);
455   void emitRegSave(const SmallVectorImpl<unsigned> &RegList, bool isVector);
456   void emitUnwindRaw(int64_t Offset, const SmallVectorImpl<uint8_t> &Opcodes);
457   void emitFill(const MCExpr &NumBytes, uint64_t FillValue,
458                 SMLoc Loc) override {
459     emitDataMappingSymbol();
460     MCObjectStreamer::emitFill(NumBytes, FillValue, Loc);
461   }
462 
463   void ChangeSection(MCSection *Section, const MCExpr *Subsection) override {
464     LastMappingSymbols[getCurrentSection().first] = std::move(LastEMSInfo);
465     MCELFStreamer::ChangeSection(Section, Subsection);
466     auto LastMappingSymbol = LastMappingSymbols.find(Section);
467     if (LastMappingSymbol != LastMappingSymbols.end()) {
468       LastEMSInfo = std::move(LastMappingSymbol->second);
469       return;
470     }
471     LastEMSInfo.reset(new ElfMappingSymbolInfo(SMLoc(), nullptr, 0));
472   }
473 
474   /// This function is the one used to emit instruction data into the ELF
475   /// streamer. We override it to add the appropriate mapping symbol if
476   /// necessary.
477   void emitInstruction(const MCInst &Inst,
478                        const MCSubtargetInfo &STI) override {
479     if (IsThumb)
480       EmitThumbMappingSymbol();
481     else
482       EmitARMMappingSymbol();
483 
484     MCELFStreamer::emitInstruction(Inst, STI);
485   }
486 
487   void emitInst(uint32_t Inst, char Suffix) {
488     unsigned Size;
489     char Buffer[4];
490     const bool LittleEndian = getContext().getAsmInfo()->isLittleEndian();
491 
492     switch (Suffix) {
493     case '\0':
494       Size = 4;
495 
496       assert(!IsThumb);
497       EmitARMMappingSymbol();
498       for (unsigned II = 0, IE = Size; II != IE; II++) {
499         const unsigned I = LittleEndian ? (Size - II - 1) : II;
500         Buffer[Size - II - 1] = uint8_t(Inst >> I * CHAR_BIT);
501       }
502 
503       break;
504     case 'n':
505     case 'w':
506       Size = (Suffix == 'n' ? 2 : 4);
507 
508       assert(IsThumb);
509       EmitThumbMappingSymbol();
510       // Thumb wide instructions are emitted as a pair of 16-bit words of the
511       // appropriate endianness.
512       for (unsigned II = 0, IE = Size; II != IE; II = II + 2) {
513         const unsigned I0 = LittleEndian ? II + 0 : II + 1;
514         const unsigned I1 = LittleEndian ? II + 1 : II + 0;
515         Buffer[Size - II - 2] = uint8_t(Inst >> I0 * CHAR_BIT);
516         Buffer[Size - II - 1] = uint8_t(Inst >> I1 * CHAR_BIT);
517       }
518 
519       break;
520     default:
521       llvm_unreachable("Invalid Suffix");
522     }
523 
524     MCELFStreamer::emitBytes(StringRef(Buffer, Size));
525   }
526 
527   /// This is one of the functions used to emit data into an ELF section, so the
528   /// ARM streamer overrides it to add the appropriate mapping symbol ($d) if
529   /// necessary.
530   void emitBytes(StringRef Data) override {
531     emitDataMappingSymbol();
532     MCELFStreamer::emitBytes(Data);
533   }
534 
535   void FlushPendingMappingSymbol() {
536     if (!LastEMSInfo->hasInfo())
537       return;
538     ElfMappingSymbolInfo *EMS = LastEMSInfo.get();
539     EmitMappingSymbol("$d", EMS->Loc, EMS->F, EMS->Offset);
540     EMS->resetInfo();
541   }
542 
543   /// This is one of the functions used to emit data into an ELF section, so the
544   /// ARM streamer overrides it to add the appropriate mapping symbol ($d) if
545   /// necessary.
546   void emitValueImpl(const MCExpr *Value, unsigned Size, SMLoc Loc) override {
547     if (const MCSymbolRefExpr *SRE = dyn_cast_or_null<MCSymbolRefExpr>(Value)) {
548       if (SRE->getKind() == MCSymbolRefExpr::VK_ARM_SBREL && !(Size == 4)) {
549         getContext().reportError(Loc, "relocated expression must be 32-bit");
550         return;
551       }
552       getOrCreateDataFragment();
553     }
554 
555     emitDataMappingSymbol();
556     MCELFStreamer::emitValueImpl(Value, Size, Loc);
557   }
558 
559   void emitAssemblerFlag(MCAssemblerFlag Flag) override {
560     MCELFStreamer::emitAssemblerFlag(Flag);
561 
562     switch (Flag) {
563     case MCAF_SyntaxUnified:
564       return; // no-op here.
565     case MCAF_Code16:
566       IsThumb = true;
567       return; // Change to Thumb mode
568     case MCAF_Code32:
569       IsThumb = false;
570       return; // Change to ARM mode
571     case MCAF_Code64:
572       return;
573     case MCAF_SubsectionsViaSymbols:
574       return;
575     }
576   }
577 
578 private:
579   enum ElfMappingSymbol {
580     EMS_None,
581     EMS_ARM,
582     EMS_Thumb,
583     EMS_Data
584   };
585 
586   struct ElfMappingSymbolInfo {
587     explicit ElfMappingSymbolInfo(SMLoc Loc, MCFragment *F, uint64_t O)
588         : Loc(Loc), F(F), Offset(O), State(EMS_None) {}
589     void resetInfo() {
590       F = nullptr;
591       Offset = 0;
592     }
593     bool hasInfo() { return F != nullptr; }
594     SMLoc Loc;
595     MCFragment *F;
596     uint64_t Offset;
597     ElfMappingSymbol State;
598   };
599 
600   void emitDataMappingSymbol() {
601     if (LastEMSInfo->State == EMS_Data)
602       return;
603     else if (LastEMSInfo->State == EMS_None) {
604       // This is a tentative symbol, it won't really be emitted until it's
605       // actually needed.
606       ElfMappingSymbolInfo *EMS = LastEMSInfo.get();
607       auto *DF = dyn_cast_or_null<MCDataFragment>(getCurrentFragment());
608       if (!DF)
609         return;
610       EMS->Loc = SMLoc();
611       EMS->F = getCurrentFragment();
612       EMS->Offset = DF->getContents().size();
613       LastEMSInfo->State = EMS_Data;
614       return;
615     }
616     EmitMappingSymbol("$d");
617     LastEMSInfo->State = EMS_Data;
618   }
619 
620   void EmitThumbMappingSymbol() {
621     if (LastEMSInfo->State == EMS_Thumb)
622       return;
623     FlushPendingMappingSymbol();
624     EmitMappingSymbol("$t");
625     LastEMSInfo->State = EMS_Thumb;
626   }
627 
628   void EmitARMMappingSymbol() {
629     if (LastEMSInfo->State == EMS_ARM)
630       return;
631     FlushPendingMappingSymbol();
632     EmitMappingSymbol("$a");
633     LastEMSInfo->State = EMS_ARM;
634   }
635 
636   void EmitMappingSymbol(StringRef Name) {
637     auto *Symbol = cast<MCSymbolELF>(getContext().getOrCreateSymbol(
638         Name + "." + Twine(MappingSymbolCounter++)));
639     emitLabel(Symbol);
640 
641     Symbol->setType(ELF::STT_NOTYPE);
642     Symbol->setBinding(ELF::STB_LOCAL);
643     Symbol->setExternal(false);
644   }
645 
646   void EmitMappingSymbol(StringRef Name, SMLoc Loc, MCFragment *F,
647                          uint64_t Offset) {
648     auto *Symbol = cast<MCSymbolELF>(getContext().getOrCreateSymbol(
649         Name + "." + Twine(MappingSymbolCounter++)));
650     emitLabelAtPos(Symbol, Loc, F, Offset);
651     Symbol->setType(ELF::STT_NOTYPE);
652     Symbol->setBinding(ELF::STB_LOCAL);
653     Symbol->setExternal(false);
654   }
655 
656   void emitThumbFunc(MCSymbol *Func) override {
657     getAssembler().setIsThumbFunc(Func);
658     emitSymbolAttribute(Func, MCSA_ELF_TypeFunction);
659   }
660 
661   // Helper functions for ARM exception handling directives
662   void EHReset();
663 
664   // Reset state between object emissions
665   void reset() override;
666 
667   void EmitPersonalityFixup(StringRef Name);
668   void FlushPendingOffset();
669   void FlushUnwindOpcodes(bool NoHandlerData);
670 
671   void SwitchToEHSection(StringRef Prefix, unsigned Type, unsigned Flags,
672                          SectionKind Kind, const MCSymbol &Fn);
673   void SwitchToExTabSection(const MCSymbol &FnStart);
674   void SwitchToExIdxSection(const MCSymbol &FnStart);
675 
676   void EmitFixup(const MCExpr *Expr, MCFixupKind Kind);
677 
678   bool IsThumb;
679   bool IsAndroid;
680   int64_t MappingSymbolCounter = 0;
681 
682   DenseMap<const MCSection *, std::unique_ptr<ElfMappingSymbolInfo>>
683       LastMappingSymbols;
684 
685   std::unique_ptr<ElfMappingSymbolInfo> LastEMSInfo;
686 
687   // ARM Exception Handling Frame Information
688   MCSymbol *ExTab;
689   MCSymbol *FnStart;
690   const MCSymbol *Personality;
691   unsigned PersonalityIndex;
692   unsigned FPReg; // Frame pointer register
693   int64_t FPOffset; // Offset: (final frame pointer) - (initial $sp)
694   int64_t SPOffset; // Offset: (final $sp) - (initial $sp)
695   int64_t PendingOffset; // Offset: (final $sp) - (emitted $sp)
696   bool UsedFP;
697   bool CantUnwind;
698   SmallVector<uint8_t, 64> Opcodes;
699   UnwindOpcodeAssembler UnwindOpAsm;
700 };
701 
702 } // end anonymous namespace
703 
704 ARMELFStreamer &ARMTargetELFStreamer::getStreamer() {
705   return static_cast<ARMELFStreamer &>(Streamer);
706 }
707 
708 void ARMTargetELFStreamer::emitFnStart() { getStreamer().emitFnStart(); }
709 void ARMTargetELFStreamer::emitFnEnd() { getStreamer().emitFnEnd(); }
710 void ARMTargetELFStreamer::emitCantUnwind() { getStreamer().emitCantUnwind(); }
711 
712 void ARMTargetELFStreamer::emitPersonality(const MCSymbol *Personality) {
713   getStreamer().emitPersonality(Personality);
714 }
715 
716 void ARMTargetELFStreamer::emitPersonalityIndex(unsigned Index) {
717   getStreamer().emitPersonalityIndex(Index);
718 }
719 
720 void ARMTargetELFStreamer::emitHandlerData() {
721   getStreamer().emitHandlerData();
722 }
723 
724 void ARMTargetELFStreamer::emitSetFP(unsigned FpReg, unsigned SpReg,
725                                      int64_t Offset) {
726   getStreamer().emitSetFP(FpReg, SpReg, Offset);
727 }
728 
729 void ARMTargetELFStreamer::emitMovSP(unsigned Reg, int64_t Offset) {
730   getStreamer().emitMovSP(Reg, Offset);
731 }
732 
733 void ARMTargetELFStreamer::emitPad(int64_t Offset) {
734   getStreamer().emitPad(Offset);
735 }
736 
737 void ARMTargetELFStreamer::emitRegSave(const SmallVectorImpl<unsigned> &RegList,
738                                        bool isVector) {
739   getStreamer().emitRegSave(RegList, isVector);
740 }
741 
742 void ARMTargetELFStreamer::emitUnwindRaw(int64_t Offset,
743                                       const SmallVectorImpl<uint8_t> &Opcodes) {
744   getStreamer().emitUnwindRaw(Offset, Opcodes);
745 }
746 
747 void ARMTargetELFStreamer::switchVendor(StringRef Vendor) {
748   assert(!Vendor.empty() && "Vendor cannot be empty.");
749 
750   if (CurrentVendor == Vendor)
751     return;
752 
753   if (!CurrentVendor.empty())
754     finishAttributeSection();
755 
756   assert(Contents.empty() &&
757          ".ARM.attributes should be flushed before changing vendor");
758   CurrentVendor = Vendor;
759 
760 }
761 
762 void ARMTargetELFStreamer::emitAttribute(unsigned Attribute, unsigned Value) {
763   setAttributeItem(Attribute, Value, /* OverwriteExisting= */ true);
764 }
765 
766 void ARMTargetELFStreamer::emitTextAttribute(unsigned Attribute,
767                                              StringRef Value) {
768   setAttributeItem(Attribute, Value, /* OverwriteExisting= */ true);
769 }
770 
771 void ARMTargetELFStreamer::emitIntTextAttribute(unsigned Attribute,
772                                                 unsigned IntValue,
773                                                 StringRef StringValue) {
774   setAttributeItems(Attribute, IntValue, StringValue,
775                     /* OverwriteExisting= */ true);
776 }
777 
778 void ARMTargetELFStreamer::emitArch(ARM::ArchKind Value) {
779   Arch = Value;
780 }
781 
782 void ARMTargetELFStreamer::emitObjectArch(ARM::ArchKind Value) {
783   EmittedArch = Value;
784 }
785 
786 void ARMTargetELFStreamer::emitArchDefaultAttributes() {
787   using namespace ARMBuildAttrs;
788 
789   setAttributeItem(CPU_name,
790                    ARM::getCPUAttr(Arch),
791                    false);
792 
793   if (EmittedArch == ARM::ArchKind::INVALID)
794     setAttributeItem(CPU_arch,
795                      ARM::getArchAttr(Arch),
796                      false);
797   else
798     setAttributeItem(CPU_arch,
799                      ARM::getArchAttr(EmittedArch),
800                      false);
801 
802   switch (Arch) {
803   case ARM::ArchKind::ARMV2:
804   case ARM::ArchKind::ARMV2A:
805   case ARM::ArchKind::ARMV3:
806   case ARM::ArchKind::ARMV3M:
807   case ARM::ArchKind::ARMV4:
808     setAttributeItem(ARM_ISA_use, Allowed, false);
809     break;
810 
811   case ARM::ArchKind::ARMV4T:
812   case ARM::ArchKind::ARMV5T:
813   case ARM::ArchKind::ARMV5TE:
814   case ARM::ArchKind::ARMV6:
815     setAttributeItem(ARM_ISA_use, Allowed, false);
816     setAttributeItem(THUMB_ISA_use, Allowed, false);
817     break;
818 
819   case ARM::ArchKind::ARMV6T2:
820     setAttributeItem(ARM_ISA_use, Allowed, false);
821     setAttributeItem(THUMB_ISA_use, AllowThumb32, false);
822     break;
823 
824   case ARM::ArchKind::ARMV6K:
825   case ARM::ArchKind::ARMV6KZ:
826     setAttributeItem(ARM_ISA_use, Allowed, false);
827     setAttributeItem(THUMB_ISA_use, Allowed, false);
828     setAttributeItem(Virtualization_use, AllowTZ, false);
829     break;
830 
831   case ARM::ArchKind::ARMV6M:
832     setAttributeItem(THUMB_ISA_use, Allowed, false);
833     break;
834 
835   case ARM::ArchKind::ARMV7A:
836     setAttributeItem(CPU_arch_profile, ApplicationProfile, false);
837     setAttributeItem(ARM_ISA_use, Allowed, false);
838     setAttributeItem(THUMB_ISA_use, AllowThumb32, false);
839     break;
840 
841   case ARM::ArchKind::ARMV7R:
842     setAttributeItem(CPU_arch_profile, RealTimeProfile, false);
843     setAttributeItem(ARM_ISA_use, Allowed, false);
844     setAttributeItem(THUMB_ISA_use, AllowThumb32, false);
845     break;
846 
847   case ARM::ArchKind::ARMV7EM:
848   case ARM::ArchKind::ARMV7M:
849     setAttributeItem(CPU_arch_profile, MicroControllerProfile, false);
850     setAttributeItem(THUMB_ISA_use, AllowThumb32, false);
851     break;
852 
853   case ARM::ArchKind::ARMV8A:
854   case ARM::ArchKind::ARMV8_1A:
855   case ARM::ArchKind::ARMV8_2A:
856   case ARM::ArchKind::ARMV8_3A:
857   case ARM::ArchKind::ARMV8_4A:
858   case ARM::ArchKind::ARMV8_5A:
859   case ARM::ArchKind::ARMV8_6A:
860     setAttributeItem(CPU_arch_profile, ApplicationProfile, false);
861     setAttributeItem(ARM_ISA_use, Allowed, false);
862     setAttributeItem(THUMB_ISA_use, AllowThumb32, false);
863     setAttributeItem(MPextension_use, Allowed, false);
864     setAttributeItem(Virtualization_use, AllowTZVirtualization, false);
865     break;
866 
867   case ARM::ArchKind::ARMV8MBaseline:
868   case ARM::ArchKind::ARMV8MMainline:
869     setAttributeItem(THUMB_ISA_use, AllowThumbDerived, false);
870     setAttributeItem(CPU_arch_profile, MicroControllerProfile, false);
871     break;
872 
873   case ARM::ArchKind::IWMMXT:
874     setAttributeItem(ARM_ISA_use, Allowed, false);
875     setAttributeItem(THUMB_ISA_use, Allowed, false);
876     setAttributeItem(WMMX_arch, AllowWMMXv1, false);
877     break;
878 
879   case ARM::ArchKind::IWMMXT2:
880     setAttributeItem(ARM_ISA_use, Allowed, false);
881     setAttributeItem(THUMB_ISA_use, Allowed, false);
882     setAttributeItem(WMMX_arch, AllowWMMXv2, false);
883     break;
884 
885   default:
886     report_fatal_error("Unknown Arch: " + Twine(ARM::getArchName(Arch)));
887     break;
888   }
889 }
890 
891 void ARMTargetELFStreamer::emitFPU(unsigned Value) {
892   FPU = Value;
893 }
894 
895 void ARMTargetELFStreamer::emitFPUDefaultAttributes() {
896   switch (FPU) {
897   case ARM::FK_VFP:
898   case ARM::FK_VFPV2:
899     setAttributeItem(ARMBuildAttrs::FP_arch,
900                      ARMBuildAttrs::AllowFPv2,
901                      /* OverwriteExisting= */ false);
902     break;
903 
904   case ARM::FK_VFPV3:
905     setAttributeItem(ARMBuildAttrs::FP_arch,
906                      ARMBuildAttrs::AllowFPv3A,
907                      /* OverwriteExisting= */ false);
908     break;
909 
910   case ARM::FK_VFPV3_FP16:
911     setAttributeItem(ARMBuildAttrs::FP_arch,
912                      ARMBuildAttrs::AllowFPv3A,
913                      /* OverwriteExisting= */ false);
914     setAttributeItem(ARMBuildAttrs::FP_HP_extension,
915                      ARMBuildAttrs::AllowHPFP,
916                      /* OverwriteExisting= */ false);
917     break;
918 
919   case ARM::FK_VFPV3_D16:
920     setAttributeItem(ARMBuildAttrs::FP_arch,
921                      ARMBuildAttrs::AllowFPv3B,
922                      /* OverwriteExisting= */ false);
923     break;
924 
925   case ARM::FK_VFPV3_D16_FP16:
926     setAttributeItem(ARMBuildAttrs::FP_arch,
927                      ARMBuildAttrs::AllowFPv3B,
928                      /* OverwriteExisting= */ false);
929     setAttributeItem(ARMBuildAttrs::FP_HP_extension,
930                      ARMBuildAttrs::AllowHPFP,
931                      /* OverwriteExisting= */ false);
932     break;
933 
934   case ARM::FK_VFPV3XD:
935     setAttributeItem(ARMBuildAttrs::FP_arch,
936                      ARMBuildAttrs::AllowFPv3B,
937                      /* OverwriteExisting= */ false);
938     break;
939   case ARM::FK_VFPV3XD_FP16:
940     setAttributeItem(ARMBuildAttrs::FP_arch,
941                      ARMBuildAttrs::AllowFPv3B,
942                      /* OverwriteExisting= */ false);
943     setAttributeItem(ARMBuildAttrs::FP_HP_extension,
944                      ARMBuildAttrs::AllowHPFP,
945                      /* OverwriteExisting= */ false);
946     break;
947 
948   case ARM::FK_VFPV4:
949     setAttributeItem(ARMBuildAttrs::FP_arch,
950                      ARMBuildAttrs::AllowFPv4A,
951                      /* OverwriteExisting= */ false);
952     break;
953 
954   // ABI_HardFP_use is handled in ARMAsmPrinter, so _SP_D16 is treated the same
955   // as _D16 here.
956   case ARM::FK_FPV4_SP_D16:
957   case ARM::FK_VFPV4_D16:
958     setAttributeItem(ARMBuildAttrs::FP_arch,
959                      ARMBuildAttrs::AllowFPv4B,
960                      /* OverwriteExisting= */ false);
961     break;
962 
963   case ARM::FK_FP_ARMV8:
964     setAttributeItem(ARMBuildAttrs::FP_arch,
965                      ARMBuildAttrs::AllowFPARMv8A,
966                      /* OverwriteExisting= */ false);
967     break;
968 
969   // FPV5_D16 is identical to FP_ARMV8 except for the number of D registers, so
970   // uses the FP_ARMV8_D16 build attribute.
971   case ARM::FK_FPV5_SP_D16:
972   case ARM::FK_FPV5_D16:
973     setAttributeItem(ARMBuildAttrs::FP_arch,
974                      ARMBuildAttrs::AllowFPARMv8B,
975                      /* OverwriteExisting= */ false);
976     break;
977 
978   case ARM::FK_NEON:
979     setAttributeItem(ARMBuildAttrs::FP_arch,
980                      ARMBuildAttrs::AllowFPv3A,
981                      /* OverwriteExisting= */ false);
982     setAttributeItem(ARMBuildAttrs::Advanced_SIMD_arch,
983                      ARMBuildAttrs::AllowNeon,
984                      /* OverwriteExisting= */ false);
985     break;
986 
987   case ARM::FK_NEON_FP16:
988     setAttributeItem(ARMBuildAttrs::FP_arch,
989                      ARMBuildAttrs::AllowFPv3A,
990                      /* OverwriteExisting= */ false);
991     setAttributeItem(ARMBuildAttrs::Advanced_SIMD_arch,
992                      ARMBuildAttrs::AllowNeon,
993                      /* OverwriteExisting= */ false);
994     setAttributeItem(ARMBuildAttrs::FP_HP_extension,
995                      ARMBuildAttrs::AllowHPFP,
996                      /* OverwriteExisting= */ false);
997     break;
998 
999   case ARM::FK_NEON_VFPV4:
1000     setAttributeItem(ARMBuildAttrs::FP_arch,
1001                      ARMBuildAttrs::AllowFPv4A,
1002                      /* OverwriteExisting= */ false);
1003     setAttributeItem(ARMBuildAttrs::Advanced_SIMD_arch,
1004                      ARMBuildAttrs::AllowNeon2,
1005                      /* OverwriteExisting= */ false);
1006     break;
1007 
1008   case ARM::FK_NEON_FP_ARMV8:
1009   case ARM::FK_CRYPTO_NEON_FP_ARMV8:
1010     setAttributeItem(ARMBuildAttrs::FP_arch,
1011                      ARMBuildAttrs::AllowFPARMv8A,
1012                      /* OverwriteExisting= */ false);
1013     // 'Advanced_SIMD_arch' must be emitted not here, but within
1014     // ARMAsmPrinter::emitAttributes(), depending on hasV8Ops() and hasV8_1a()
1015     break;
1016 
1017   case ARM::FK_SOFTVFP:
1018   case ARM::FK_NONE:
1019     break;
1020 
1021   default:
1022     report_fatal_error("Unknown FPU: " + Twine(FPU));
1023     break;
1024   }
1025 }
1026 
1027 size_t ARMTargetELFStreamer::calculateContentSize() const {
1028   size_t Result = 0;
1029   for (size_t i = 0; i < Contents.size(); ++i) {
1030     AttributeItem item = Contents[i];
1031     switch (item.Type) {
1032     case AttributeItem::HiddenAttribute:
1033       break;
1034     case AttributeItem::NumericAttribute:
1035       Result += getULEB128Size(item.Tag);
1036       Result += getULEB128Size(item.IntValue);
1037       break;
1038     case AttributeItem::TextAttribute:
1039       Result += getULEB128Size(item.Tag);
1040       Result += item.StringValue.size() + 1; // string + '\0'
1041       break;
1042     case AttributeItem::NumericAndTextAttributes:
1043       Result += getULEB128Size(item.Tag);
1044       Result += getULEB128Size(item.IntValue);
1045       Result += item.StringValue.size() + 1; // string + '\0';
1046       break;
1047     }
1048   }
1049   return Result;
1050 }
1051 
1052 void ARMTargetELFStreamer::finishAttributeSection() {
1053   // <format-version>
1054   // [ <section-length> "vendor-name"
1055   // [ <file-tag> <size> <attribute>*
1056   //   | <section-tag> <size> <section-number>* 0 <attribute>*
1057   //   | <symbol-tag> <size> <symbol-number>* 0 <attribute>*
1058   //   ]+
1059   // ]*
1060 
1061   if (FPU != ARM::FK_INVALID)
1062     emitFPUDefaultAttributes();
1063 
1064   if (Arch != ARM::ArchKind::INVALID)
1065     emitArchDefaultAttributes();
1066 
1067   if (Contents.empty())
1068     return;
1069 
1070   llvm::sort(Contents, AttributeItem::LessTag);
1071 
1072   ARMELFStreamer &Streamer = getStreamer();
1073 
1074   // Switch to .ARM.attributes section
1075   if (AttributeSection) {
1076     Streamer.SwitchSection(AttributeSection);
1077   } else {
1078     AttributeSection = Streamer.getContext().getELFSection(
1079         ".ARM.attributes", ELF::SHT_ARM_ATTRIBUTES, 0);
1080     Streamer.SwitchSection(AttributeSection);
1081 
1082     // Format version
1083     Streamer.emitInt8(0x41);
1084   }
1085 
1086   // Vendor size + Vendor name + '\0'
1087   const size_t VendorHeaderSize = 4 + CurrentVendor.size() + 1;
1088 
1089   // Tag + Tag Size
1090   const size_t TagHeaderSize = 1 + 4;
1091 
1092   const size_t ContentsSize = calculateContentSize();
1093 
1094   Streamer.emitInt32(VendorHeaderSize + TagHeaderSize + ContentsSize);
1095   Streamer.emitBytes(CurrentVendor);
1096   Streamer.emitInt8(0); // '\0'
1097 
1098   Streamer.emitInt8(ARMBuildAttrs::File);
1099   Streamer.emitInt32(TagHeaderSize + ContentsSize);
1100 
1101   // Size should have been accounted for already, now
1102   // emit each field as its type (ULEB or String)
1103   for (size_t i = 0; i < Contents.size(); ++i) {
1104     AttributeItem item = Contents[i];
1105     Streamer.emitULEB128IntValue(item.Tag);
1106     switch (item.Type) {
1107     default: llvm_unreachable("Invalid attribute type");
1108     case AttributeItem::NumericAttribute:
1109       Streamer.emitULEB128IntValue(item.IntValue);
1110       break;
1111     case AttributeItem::TextAttribute:
1112       Streamer.emitBytes(item.StringValue);
1113       Streamer.emitInt8(0); // '\0'
1114       break;
1115     case AttributeItem::NumericAndTextAttributes:
1116       Streamer.emitULEB128IntValue(item.IntValue);
1117       Streamer.emitBytes(item.StringValue);
1118       Streamer.emitInt8(0); // '\0'
1119       break;
1120     }
1121   }
1122 
1123   Contents.clear();
1124   FPU = ARM::FK_INVALID;
1125 }
1126 
1127 void ARMTargetELFStreamer::emitLabel(MCSymbol *Symbol) {
1128   ARMELFStreamer &Streamer = getStreamer();
1129   if (!Streamer.IsThumb)
1130     return;
1131 
1132   Streamer.getAssembler().registerSymbol(*Symbol);
1133   unsigned Type = cast<MCSymbolELF>(Symbol)->getType();
1134   if (Type == ELF::STT_FUNC || Type == ELF::STT_GNU_IFUNC)
1135     Streamer.emitThumbFunc(Symbol);
1136 }
1137 
1138 void
1139 ARMTargetELFStreamer::AnnotateTLSDescriptorSequence(const MCSymbolRefExpr *S) {
1140   getStreamer().EmitFixup(S, FK_Data_4);
1141 }
1142 
1143 void ARMTargetELFStreamer::emitThumbSet(MCSymbol *Symbol, const MCExpr *Value) {
1144   if (const MCSymbolRefExpr *SRE = dyn_cast<MCSymbolRefExpr>(Value)) {
1145     const MCSymbol &Sym = SRE->getSymbol();
1146     if (!Sym.isDefined()) {
1147       getStreamer().emitAssignment(Symbol, Value);
1148       return;
1149     }
1150   }
1151 
1152   getStreamer().emitThumbFunc(Symbol);
1153   getStreamer().emitAssignment(Symbol, Value);
1154 }
1155 
1156 void ARMTargetELFStreamer::emitInst(uint32_t Inst, char Suffix) {
1157   getStreamer().emitInst(Inst, Suffix);
1158 }
1159 
1160 void ARMTargetELFStreamer::reset() { AttributeSection = nullptr; }
1161 
1162 void ARMELFStreamer::FinishImpl() {
1163   MCTargetStreamer &TS = *getTargetStreamer();
1164   ARMTargetStreamer &ATS = static_cast<ARMTargetStreamer &>(TS);
1165   ATS.finishAttributeSection();
1166 
1167   MCELFStreamer::FinishImpl();
1168 }
1169 
1170 void ARMELFStreamer::reset() {
1171   MCTargetStreamer &TS = *getTargetStreamer();
1172   ARMTargetStreamer &ATS = static_cast<ARMTargetStreamer &>(TS);
1173   ATS.reset();
1174   MappingSymbolCounter = 0;
1175   MCELFStreamer::reset();
1176   LastMappingSymbols.clear();
1177   LastEMSInfo.reset();
1178   // MCELFStreamer clear's the assembler's e_flags. However, for
1179   // arm we manually set the ABI version on streamer creation, so
1180   // do the same here
1181   getAssembler().setELFHeaderEFlags(ELF::EF_ARM_EABI_VER5);
1182 }
1183 
1184 inline void ARMELFStreamer::SwitchToEHSection(StringRef Prefix,
1185                                               unsigned Type,
1186                                               unsigned Flags,
1187                                               SectionKind Kind,
1188                                               const MCSymbol &Fn) {
1189   const MCSectionELF &FnSection =
1190     static_cast<const MCSectionELF &>(Fn.getSection());
1191 
1192   // Create the name for new section
1193   StringRef FnSecName(FnSection.getSectionName());
1194   SmallString<128> EHSecName(Prefix);
1195   if (FnSecName != ".text") {
1196     EHSecName += FnSecName;
1197   }
1198 
1199   // Get .ARM.extab or .ARM.exidx section
1200   const MCSymbolELF *Group = FnSection.getGroup();
1201   if (Group)
1202     Flags |= ELF::SHF_GROUP;
1203   MCSectionELF *EHSection = getContext().getELFSection(
1204       EHSecName, Type, Flags, 0, Group, FnSection.getUniqueID(),
1205       static_cast<const MCSymbolELF *>(FnSection.getBeginSymbol()));
1206 
1207   assert(EHSection && "Failed to get the required EH section");
1208 
1209   // Switch to .ARM.extab or .ARM.exidx section
1210   SwitchSection(EHSection);
1211   emitCodeAlignment(4);
1212 }
1213 
1214 inline void ARMELFStreamer::SwitchToExTabSection(const MCSymbol &FnStart) {
1215   SwitchToEHSection(".ARM.extab", ELF::SHT_PROGBITS, ELF::SHF_ALLOC,
1216                     SectionKind::getData(), FnStart);
1217 }
1218 
1219 inline void ARMELFStreamer::SwitchToExIdxSection(const MCSymbol &FnStart) {
1220   SwitchToEHSection(".ARM.exidx", ELF::SHT_ARM_EXIDX,
1221                     ELF::SHF_ALLOC | ELF::SHF_LINK_ORDER,
1222                     SectionKind::getData(), FnStart);
1223 }
1224 
1225 void ARMELFStreamer::EmitFixup(const MCExpr *Expr, MCFixupKind Kind) {
1226   MCDataFragment *Frag = getOrCreateDataFragment();
1227   Frag->getFixups().push_back(MCFixup::create(Frag->getContents().size(), Expr,
1228                                               Kind));
1229 }
1230 
1231 void ARMELFStreamer::EHReset() {
1232   ExTab = nullptr;
1233   FnStart = nullptr;
1234   Personality = nullptr;
1235   PersonalityIndex = ARM::EHABI::NUM_PERSONALITY_INDEX;
1236   FPReg = ARM::SP;
1237   FPOffset = 0;
1238   SPOffset = 0;
1239   PendingOffset = 0;
1240   UsedFP = false;
1241   CantUnwind = false;
1242 
1243   Opcodes.clear();
1244   UnwindOpAsm.Reset();
1245 }
1246 
1247 void ARMELFStreamer::emitFnStart() {
1248   assert(FnStart == nullptr);
1249   FnStart = getContext().createTempSymbol();
1250   emitLabel(FnStart);
1251 }
1252 
1253 void ARMELFStreamer::emitFnEnd() {
1254   assert(FnStart && ".fnstart must precedes .fnend");
1255 
1256   // Emit unwind opcodes if there is no .handlerdata directive
1257   if (!ExTab && !CantUnwind)
1258     FlushUnwindOpcodes(true);
1259 
1260   // Emit the exception index table entry
1261   SwitchToExIdxSection(*FnStart);
1262 
1263   // The EHABI requires a dependency preserving R_ARM_NONE relocation to the
1264   // personality routine to protect it from an arbitrary platform's static
1265   // linker garbage collection. We disable this for Android where the unwinder
1266   // is either dynamically linked or directly references the personality
1267   // routine.
1268   if (PersonalityIndex < ARM::EHABI::NUM_PERSONALITY_INDEX && !IsAndroid)
1269     EmitPersonalityFixup(GetAEABIUnwindPersonalityName(PersonalityIndex));
1270 
1271   const MCSymbolRefExpr *FnStartRef =
1272     MCSymbolRefExpr::create(FnStart,
1273                             MCSymbolRefExpr::VK_ARM_PREL31,
1274                             getContext());
1275 
1276   emitValue(FnStartRef, 4);
1277 
1278   if (CantUnwind) {
1279     emitInt32(ARM::EHABI::EXIDX_CANTUNWIND);
1280   } else if (ExTab) {
1281     // Emit a reference to the unwind opcodes in the ".ARM.extab" section.
1282     const MCSymbolRefExpr *ExTabEntryRef =
1283       MCSymbolRefExpr::create(ExTab,
1284                               MCSymbolRefExpr::VK_ARM_PREL31,
1285                               getContext());
1286     emitValue(ExTabEntryRef, 4);
1287   } else {
1288     // For the __aeabi_unwind_cpp_pr0, we have to emit the unwind opcodes in
1289     // the second word of exception index table entry.  The size of the unwind
1290     // opcodes should always be 4 bytes.
1291     assert(PersonalityIndex == ARM::EHABI::AEABI_UNWIND_CPP_PR0 &&
1292            "Compact model must use __aeabi_unwind_cpp_pr0 as personality");
1293     assert(Opcodes.size() == 4u &&
1294            "Unwind opcode size for __aeabi_unwind_cpp_pr0 must be equal to 4");
1295     uint64_t Intval = Opcodes[0] |
1296                       Opcodes[1] << 8 |
1297                       Opcodes[2] << 16 |
1298                       Opcodes[3] << 24;
1299     emitIntValue(Intval, Opcodes.size());
1300   }
1301 
1302   // Switch to the section containing FnStart
1303   SwitchSection(&FnStart->getSection());
1304 
1305   // Clean exception handling frame information
1306   EHReset();
1307 }
1308 
1309 void ARMELFStreamer::emitCantUnwind() { CantUnwind = true; }
1310 
1311 // Add the R_ARM_NONE fixup at the same position
1312 void ARMELFStreamer::EmitPersonalityFixup(StringRef Name) {
1313   const MCSymbol *PersonalitySym = getContext().getOrCreateSymbol(Name);
1314 
1315   const MCSymbolRefExpr *PersonalityRef = MCSymbolRefExpr::create(
1316       PersonalitySym, MCSymbolRefExpr::VK_ARM_NONE, getContext());
1317 
1318   visitUsedExpr(*PersonalityRef);
1319   MCDataFragment *DF = getOrCreateDataFragment();
1320   DF->getFixups().push_back(MCFixup::create(DF->getContents().size(),
1321                                             PersonalityRef,
1322                                             MCFixup::getKindForSize(4, false)));
1323 }
1324 
1325 void ARMELFStreamer::FlushPendingOffset() {
1326   if (PendingOffset != 0) {
1327     UnwindOpAsm.EmitSPOffset(-PendingOffset);
1328     PendingOffset = 0;
1329   }
1330 }
1331 
1332 void ARMELFStreamer::FlushUnwindOpcodes(bool NoHandlerData) {
1333   // Emit the unwind opcode to restore $sp.
1334   if (UsedFP) {
1335     const MCRegisterInfo *MRI = getContext().getRegisterInfo();
1336     int64_t LastRegSaveSPOffset = SPOffset - PendingOffset;
1337     UnwindOpAsm.EmitSPOffset(LastRegSaveSPOffset - FPOffset);
1338     UnwindOpAsm.EmitSetSP(MRI->getEncodingValue(FPReg));
1339   } else {
1340     FlushPendingOffset();
1341   }
1342 
1343   // Finalize the unwind opcode sequence
1344   UnwindOpAsm.Finalize(PersonalityIndex, Opcodes);
1345 
1346   // For compact model 0, we have to emit the unwind opcodes in the .ARM.exidx
1347   // section.  Thus, we don't have to create an entry in the .ARM.extab
1348   // section.
1349   if (NoHandlerData && PersonalityIndex == ARM::EHABI::AEABI_UNWIND_CPP_PR0)
1350     return;
1351 
1352   // Switch to .ARM.extab section.
1353   SwitchToExTabSection(*FnStart);
1354 
1355   // Create .ARM.extab label for offset in .ARM.exidx
1356   assert(!ExTab);
1357   ExTab = getContext().createTempSymbol();
1358   emitLabel(ExTab);
1359 
1360   // Emit personality
1361   if (Personality) {
1362     const MCSymbolRefExpr *PersonalityRef =
1363       MCSymbolRefExpr::create(Personality,
1364                               MCSymbolRefExpr::VK_ARM_PREL31,
1365                               getContext());
1366 
1367     emitValue(PersonalityRef, 4);
1368   }
1369 
1370   // Emit unwind opcodes
1371   assert((Opcodes.size() % 4) == 0 &&
1372          "Unwind opcode size for __aeabi_cpp_unwind_pr0 must be multiple of 4");
1373   for (unsigned I = 0; I != Opcodes.size(); I += 4) {
1374     uint64_t Intval = Opcodes[I] |
1375                       Opcodes[I + 1] << 8 |
1376                       Opcodes[I + 2] << 16 |
1377                       Opcodes[I + 3] << 24;
1378     emitInt32(Intval);
1379   }
1380 
1381   // According to ARM EHABI section 9.2, if the __aeabi_unwind_cpp_pr1() or
1382   // __aeabi_unwind_cpp_pr2() is used, then the handler data must be emitted
1383   // after the unwind opcodes.  The handler data consists of several 32-bit
1384   // words, and should be terminated by zero.
1385   //
1386   // In case that the .handlerdata directive is not specified by the
1387   // programmer, we should emit zero to terminate the handler data.
1388   if (NoHandlerData && !Personality)
1389     emitInt32(0);
1390 }
1391 
1392 void ARMELFStreamer::emitHandlerData() { FlushUnwindOpcodes(false); }
1393 
1394 void ARMELFStreamer::emitPersonality(const MCSymbol *Per) {
1395   Personality = Per;
1396   UnwindOpAsm.setPersonality(Per);
1397 }
1398 
1399 void ARMELFStreamer::emitPersonalityIndex(unsigned Index) {
1400   assert(Index < ARM::EHABI::NUM_PERSONALITY_INDEX && "invalid index");
1401   PersonalityIndex = Index;
1402 }
1403 
1404 void ARMELFStreamer::emitSetFP(unsigned NewFPReg, unsigned NewSPReg,
1405                                int64_t Offset) {
1406   assert((NewSPReg == ARM::SP || NewSPReg == FPReg) &&
1407          "the operand of .setfp directive should be either $sp or $fp");
1408 
1409   UsedFP = true;
1410   FPReg = NewFPReg;
1411 
1412   if (NewSPReg == ARM::SP)
1413     FPOffset = SPOffset + Offset;
1414   else
1415     FPOffset += Offset;
1416 }
1417 
1418 void ARMELFStreamer::emitMovSP(unsigned Reg, int64_t Offset) {
1419   assert((Reg != ARM::SP && Reg != ARM::PC) &&
1420          "the operand of .movsp cannot be either sp or pc");
1421   assert(FPReg == ARM::SP && "current FP must be SP");
1422 
1423   FlushPendingOffset();
1424 
1425   FPReg = Reg;
1426   FPOffset = SPOffset + Offset;
1427 
1428   const MCRegisterInfo *MRI = getContext().getRegisterInfo();
1429   UnwindOpAsm.EmitSetSP(MRI->getEncodingValue(FPReg));
1430 }
1431 
1432 void ARMELFStreamer::emitPad(int64_t Offset) {
1433   // Track the change of the $sp offset
1434   SPOffset -= Offset;
1435 
1436   // To squash multiple .pad directives, we should delay the unwind opcode
1437   // until the .save, .vsave, .handlerdata, or .fnend directives.
1438   PendingOffset -= Offset;
1439 }
1440 
1441 void ARMELFStreamer::emitRegSave(const SmallVectorImpl<unsigned> &RegList,
1442                                  bool IsVector) {
1443   // Collect the registers in the register list
1444   unsigned Count = 0;
1445   uint32_t Mask = 0;
1446   const MCRegisterInfo *MRI = getContext().getRegisterInfo();
1447   for (size_t i = 0; i < RegList.size(); ++i) {
1448     unsigned Reg = MRI->getEncodingValue(RegList[i]);
1449     assert(Reg < (IsVector ? 32U : 16U) && "Register out of range");
1450     unsigned Bit = (1u << Reg);
1451     if ((Mask & Bit) == 0) {
1452       Mask |= Bit;
1453       ++Count;
1454     }
1455   }
1456 
1457   // Track the change the $sp offset: For the .save directive, the
1458   // corresponding push instruction will decrease the $sp by (4 * Count).
1459   // For the .vsave directive, the corresponding vpush instruction will
1460   // decrease $sp by (8 * Count).
1461   SPOffset -= Count * (IsVector ? 8 : 4);
1462 
1463   // Emit the opcode
1464   FlushPendingOffset();
1465   if (IsVector)
1466     UnwindOpAsm.EmitVFPRegSave(Mask);
1467   else
1468     UnwindOpAsm.EmitRegSave(Mask);
1469 }
1470 
1471 void ARMELFStreamer::emitUnwindRaw(int64_t Offset,
1472                                    const SmallVectorImpl<uint8_t> &Opcodes) {
1473   FlushPendingOffset();
1474   SPOffset = SPOffset - Offset;
1475   UnwindOpAsm.EmitRaw(Opcodes);
1476 }
1477 
1478 namespace llvm {
1479 
1480 MCTargetStreamer *createARMTargetAsmStreamer(MCStreamer &S,
1481                                              formatted_raw_ostream &OS,
1482                                              MCInstPrinter *InstPrint,
1483                                              bool isVerboseAsm) {
1484   return new ARMTargetAsmStreamer(S, OS, *InstPrint, isVerboseAsm);
1485 }
1486 
1487 MCTargetStreamer *createARMNullTargetStreamer(MCStreamer &S) {
1488   return new ARMTargetStreamer(S);
1489 }
1490 
1491 MCTargetStreamer *createARMObjectTargetStreamer(MCStreamer &S,
1492                                                 const MCSubtargetInfo &STI) {
1493   const Triple &TT = STI.getTargetTriple();
1494   if (TT.isOSBinFormatELF())
1495     return new ARMTargetELFStreamer(S);
1496   return new ARMTargetStreamer(S);
1497 }
1498 
1499 MCELFStreamer *createARMELFStreamer(MCContext &Context,
1500                                     std::unique_ptr<MCAsmBackend> TAB,
1501                                     std::unique_ptr<MCObjectWriter> OW,
1502                                     std::unique_ptr<MCCodeEmitter> Emitter,
1503                                     bool RelaxAll, bool IsThumb,
1504                                     bool IsAndroid) {
1505   ARMELFStreamer *S =
1506       new ARMELFStreamer(Context, std::move(TAB), std::move(OW),
1507                          std::move(Emitter), IsThumb, IsAndroid);
1508   // FIXME: This should eventually end up somewhere else where more
1509   // intelligent flag decisions can be made. For now we are just maintaining
1510   // the status quo for ARM and setting EF_ARM_EABI_VER5 as the default.
1511   S->getAssembler().setELFHeaderEFlags(ELF::EF_ARM_EABI_VER5);
1512 
1513   if (RelaxAll)
1514     S->getAssembler().setRelaxAll(true);
1515   return S;
1516 }
1517 
1518 } // end namespace llvm
1519