xref: /llvm-project/llvm/lib/Target/ARM/MCTargetDesc/ARMELFStreamer.cpp (revision 5be43db9b17e7cfc9e987f257221b0926551eb6e) 
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 "ARMMCTargetDesc.h"
16 #include "ARMUnwindOpAsm.h"
17 #include "Utils/ARMBaseInfo.h"
18 #include "llvm/ADT/DenseMap.h"
19 #include "llvm/ADT/SmallString.h"
20 #include "llvm/ADT/SmallVector.h"
21 #include "llvm/ADT/StringExtras.h"
22 #include "llvm/ADT/StringRef.h"
23 #include "llvm/ADT/Twine.h"
24 #include "llvm/BinaryFormat/ELF.h"
25 #include "llvm/MC/MCAsmBackend.h"
26 #include "llvm/MC/MCAsmInfo.h"
27 #include "llvm/MC/MCAssembler.h"
28 #include "llvm/MC/MCCodeEmitter.h"
29 #include "llvm/MC/MCContext.h"
30 #include "llvm/MC/MCELFObjectWriter.h"
31 #include "llvm/MC/MCELFStreamer.h"
32 #include "llvm/MC/MCExpr.h"
33 #include "llvm/MC/MCFixup.h"
34 #include "llvm/MC/MCFragment.h"
35 #include "llvm/MC/MCInst.h"
36 #include "llvm/MC/MCInstPrinter.h"
37 #include "llvm/MC/MCObjectFileInfo.h"
38 #include "llvm/MC/MCObjectWriter.h"
39 #include "llvm/MC/MCRegisterInfo.h"
40 #include "llvm/MC/MCSection.h"
41 #include "llvm/MC/MCSectionELF.h"
42 #include "llvm/MC/MCStreamer.h"
43 #include "llvm/MC/MCSubtargetInfo.h"
44 #include "llvm/MC/MCSymbol.h"
45 #include "llvm/MC/MCSymbolELF.h"
46 #include "llvm/MC/SectionKind.h"
47 #include "llvm/Support/ARMBuildAttributes.h"
48 #include "llvm/Support/ARMEHABI.h"
49 #include "llvm/Support/Casting.h"
50 #include "llvm/Support/ErrorHandling.h"
51 #include "llvm/Support/FormattedStream.h"
52 #include "llvm/Support/raw_ostream.h"
53 #include <cassert>
54 #include <climits>
55 #include <cstdint>
56 #include <string>
57 
58 using namespace llvm;
59 
60 static std::string GetAEABIUnwindPersonalityName(unsigned Index) {
61   assert(Index < ARM::EHABI::NUM_PERSONALITY_INDEX &&
62          "Invalid personality index");
63   return (Twine("__aeabi_unwind_cpp_pr") + Twine(Index)).str();
64 }
65 
66 namespace {
67 
68 class ARMELFStreamer;
69 
70 class ARMTargetAsmStreamer : public ARMTargetStreamer {
71   formatted_raw_ostream &OS;
72   MCInstPrinter &InstPrinter;
73   bool IsVerboseAsm;
74 
75   void emitFnStart() override;
76   void emitFnEnd() override;
77   void emitCantUnwind() override;
78   void emitPersonality(const MCSymbol *Personality) override;
79   void emitPersonalityIndex(unsigned Index) override;
80   void emitHandlerData() override;
81   void emitSetFP(MCRegister FpReg, MCRegister SpReg,
82                  int64_t Offset = 0) override;
83   void emitMovSP(MCRegister Reg, int64_t Offset = 0) override;
84   void emitPad(int64_t Offset) override;
85   void emitRegSave(const SmallVectorImpl<MCRegister> &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(ARM::FPUKind 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   void emitARMWinCFIAllocStack(unsigned Size, bool Wide) override;
106   void emitARMWinCFISaveRegMask(unsigned Mask, bool Wide) override;
107   void emitARMWinCFISaveSP(unsigned Reg) override;
108   void emitARMWinCFISaveFRegs(unsigned First, unsigned Last) override;
109   void emitARMWinCFISaveLR(unsigned Offset) override;
110   void emitARMWinCFIPrologEnd(bool Fragment) override;
111   void emitARMWinCFINop(bool Wide) override;
112   void emitARMWinCFIEpilogStart(unsigned Condition) override;
113   void emitARMWinCFIEpilogEnd() override;
114   void emitARMWinCFICustom(unsigned Opcode) override;
115 
116 public:
117   ARMTargetAsmStreamer(MCStreamer &S, formatted_raw_ostream &OS,
118                        MCInstPrinter &InstPrinter);
119 };
120 
121 ARMTargetAsmStreamer::ARMTargetAsmStreamer(MCStreamer &S,
122                                            formatted_raw_ostream &OS,
123                                            MCInstPrinter &InstPrinter)
124     : ARMTargetStreamer(S), OS(OS), InstPrinter(InstPrinter),
125       IsVerboseAsm(S.isVerboseAsm()) {}
126 
127 void ARMTargetAsmStreamer::emitFnStart() { OS << "\t.fnstart\n"; }
128 void ARMTargetAsmStreamer::emitFnEnd() { OS << "\t.fnend\n"; }
129 void ARMTargetAsmStreamer::emitCantUnwind() { OS << "\t.cantunwind\n"; }
130 
131 void ARMTargetAsmStreamer::emitPersonality(const MCSymbol *Personality) {
132   OS << "\t.personality " << Personality->getName() << '\n';
133 }
134 
135 void ARMTargetAsmStreamer::emitPersonalityIndex(unsigned Index) {
136   OS << "\t.personalityindex " << Index << '\n';
137 }
138 
139 void ARMTargetAsmStreamer::emitHandlerData() { OS << "\t.handlerdata\n"; }
140 
141 void ARMTargetAsmStreamer::emitSetFP(MCRegister FpReg, MCRegister SpReg,
142                                      int64_t Offset) {
143   OS << "\t.setfp\t";
144   InstPrinter.printRegName(OS, FpReg);
145   OS << ", ";
146   InstPrinter.printRegName(OS, SpReg);
147   if (Offset)
148     OS << ", #" << Offset;
149   OS << '\n';
150 }
151 
152 void ARMTargetAsmStreamer::emitMovSP(MCRegister Reg, int64_t Offset) {
153   assert((Reg != ARM::SP && Reg != ARM::PC) &&
154          "the operand of .movsp cannot be either sp or pc");
155 
156   OS << "\t.movsp\t";
157   InstPrinter.printRegName(OS, Reg);
158   if (Offset)
159     OS << ", #" << Offset;
160   OS << '\n';
161 }
162 
163 void ARMTargetAsmStreamer::emitPad(int64_t Offset) {
164   OS << "\t.pad\t#" << Offset << '\n';
165 }
166 
167 void ARMTargetAsmStreamer::emitRegSave(
168     const SmallVectorImpl<MCRegister> &RegList, bool isVector) {
169   assert(RegList.size() && "RegList should not be empty");
170   if (isVector)
171     OS << "\t.vsave\t{";
172   else
173     OS << "\t.save\t{";
174 
175   InstPrinter.printRegName(OS, RegList[0]);
176 
177   for (unsigned i = 1, e = RegList.size(); i != e; ++i) {
178     OS << ", ";
179     InstPrinter.printRegName(OS, RegList[i]);
180   }
181 
182   OS << "}\n";
183 }
184 
185 void ARMTargetAsmStreamer::switchVendor(StringRef Vendor) {}
186 
187 void ARMTargetAsmStreamer::emitAttribute(unsigned Attribute, unsigned Value) {
188   OS << "\t.eabi_attribute\t" << Attribute << ", " << Twine(Value);
189   if (IsVerboseAsm) {
190     StringRef Name = ELFAttrs::attrTypeAsString(
191         Attribute, ARMBuildAttrs::getARMAttributeTags());
192     if (!Name.empty())
193       OS << "\t@ " << Name;
194   }
195   OS << "\n";
196 }
197 
198 void ARMTargetAsmStreamer::emitTextAttribute(unsigned Attribute,
199                                              StringRef String) {
200   switch (Attribute) {
201   case ARMBuildAttrs::CPU_name:
202     OS << "\t.cpu\t" << String.lower();
203     break;
204   default:
205     OS << "\t.eabi_attribute\t" << Attribute << ", \"";
206     if (Attribute == ARMBuildAttrs::also_compatible_with)
207       OS.write_escaped(String);
208     else
209       OS << String;
210     OS << "\"";
211     if (IsVerboseAsm) {
212       StringRef Name = ELFAttrs::attrTypeAsString(
213           Attribute, ARMBuildAttrs::getARMAttributeTags());
214       if (!Name.empty())
215         OS << "\t@ " << Name;
216     }
217     break;
218   }
219   OS << "\n";
220 }
221 
222 void ARMTargetAsmStreamer::emitIntTextAttribute(unsigned Attribute,
223                                                 unsigned IntValue,
224                                                 StringRef StringValue) {
225   switch (Attribute) {
226   default: llvm_unreachable("unsupported multi-value attribute in asm mode");
227   case ARMBuildAttrs::compatibility:
228     OS << "\t.eabi_attribute\t" << Attribute << ", " << IntValue;
229     if (!StringValue.empty())
230       OS << ", \"" << StringValue << "\"";
231     if (IsVerboseAsm)
232       OS << "\t@ "
233          << ELFAttrs::attrTypeAsString(Attribute,
234                                        ARMBuildAttrs::getARMAttributeTags());
235     break;
236   }
237   OS << "\n";
238 }
239 
240 void ARMTargetAsmStreamer::emitArch(ARM::ArchKind Arch) {
241   OS << "\t.arch\t" << ARM::getArchName(Arch) << "\n";
242 }
243 
244 void ARMTargetAsmStreamer::emitArchExtension(uint64_t ArchExt) {
245   OS << "\t.arch_extension\t" << ARM::getArchExtName(ArchExt) << "\n";
246 }
247 
248 void ARMTargetAsmStreamer::emitObjectArch(ARM::ArchKind Arch) {
249   OS << "\t.object_arch\t" << ARM::getArchName(Arch) << '\n';
250 }
251 
252 void ARMTargetAsmStreamer::emitFPU(ARM::FPUKind FPU) {
253   OS << "\t.fpu\t" << ARM::getFPUName(FPU) << "\n";
254 }
255 
256 void ARMTargetAsmStreamer::finishAttributeSection() {}
257 
258 void ARMTargetAsmStreamer::annotateTLSDescriptorSequence(
259     const MCSymbolRefExpr *S) {
260   OS << "\t.tlsdescseq\t" << S->getSymbol().getName() << "\n";
261 }
262 
263 void ARMTargetAsmStreamer::emitThumbSet(MCSymbol *Symbol, const MCExpr *Value) {
264   const MCAsmInfo *MAI = Streamer.getContext().getAsmInfo();
265 
266   OS << "\t.thumb_set\t";
267   Symbol->print(OS, MAI);
268   OS << ", ";
269   Value->print(OS, MAI);
270   OS << '\n';
271 }
272 
273 void ARMTargetAsmStreamer::emitInst(uint32_t Inst, char Suffix) {
274   OS << "\t.inst";
275   if (Suffix)
276     OS << "." << Suffix;
277   OS << "\t0x" << Twine::utohexstr(Inst) << "\n";
278 }
279 
280 void ARMTargetAsmStreamer::emitUnwindRaw(int64_t Offset,
281                                       const SmallVectorImpl<uint8_t> &Opcodes) {
282   OS << "\t.unwind_raw " << Offset;
283   for (uint8_t Opcode : Opcodes)
284     OS << ", 0x" << Twine::utohexstr(Opcode);
285   OS << '\n';
286 }
287 
288 void ARMTargetAsmStreamer::emitARMWinCFIAllocStack(unsigned Size, bool Wide) {
289   if (Wide)
290     OS << "\t.seh_stackalloc_w\t" << Size << "\n";
291   else
292     OS << "\t.seh_stackalloc\t" << Size << "\n";
293 }
294 
295 static void printRegs(formatted_raw_ostream &OS, ListSeparator &LS, int First,
296                       int Last) {
297   if (First != Last)
298     OS << LS << "r" << First << "-r" << Last;
299   else
300     OS << LS << "r" << First;
301 }
302 
303 void ARMTargetAsmStreamer::emitARMWinCFISaveRegMask(unsigned Mask, bool Wide) {
304   if (Wide)
305     OS << "\t.seh_save_regs_w\t";
306   else
307     OS << "\t.seh_save_regs\t";
308   ListSeparator LS;
309   int First = -1;
310   OS << "{";
311   for (int I = 0; I <= 12; I++) {
312     if (Mask & (1 << I)) {
313       if (First < 0)
314         First = I;
315     } else {
316       if (First >= 0) {
317         printRegs(OS, LS, First, I - 1);
318         First = -1;
319       }
320     }
321   }
322   if (First >= 0)
323     printRegs(OS, LS, First, 12);
324   if (Mask & (1 << 14))
325     OS << LS << "lr";
326   OS << "}\n";
327 }
328 
329 void ARMTargetAsmStreamer::emitARMWinCFISaveSP(unsigned Reg) {
330   OS << "\t.seh_save_sp\tr" << Reg << "\n";
331 }
332 
333 void ARMTargetAsmStreamer::emitARMWinCFISaveFRegs(unsigned First,
334                                                   unsigned Last) {
335   if (First != Last)
336     OS << "\t.seh_save_fregs\t{d" << First << "-d" << Last << "}\n";
337   else
338     OS << "\t.seh_save_fregs\t{d" << First << "}\n";
339 }
340 
341 void ARMTargetAsmStreamer::emitARMWinCFISaveLR(unsigned Offset) {
342   OS << "\t.seh_save_lr\t" << Offset << "\n";
343 }
344 
345 void ARMTargetAsmStreamer::emitARMWinCFIPrologEnd(bool Fragment) {
346   if (Fragment)
347     OS << "\t.seh_endprologue_fragment\n";
348   else
349     OS << "\t.seh_endprologue\n";
350 }
351 
352 void ARMTargetAsmStreamer::emitARMWinCFINop(bool Wide) {
353   if (Wide)
354     OS << "\t.seh_nop_w\n";
355   else
356     OS << "\t.seh_nop\n";
357 }
358 
359 void ARMTargetAsmStreamer::emitARMWinCFIEpilogStart(unsigned Condition) {
360   if (Condition == ARMCC::AL)
361     OS << "\t.seh_startepilogue\n";
362   else
363     OS << "\t.seh_startepilogue_cond\t"
364        << ARMCondCodeToString(static_cast<ARMCC::CondCodes>(Condition)) << "\n";
365 }
366 
367 void ARMTargetAsmStreamer::emitARMWinCFIEpilogEnd() {
368   OS << "\t.seh_endepilogue\n";
369 }
370 
371 void ARMTargetAsmStreamer::emitARMWinCFICustom(unsigned Opcode) {
372   int I;
373   for (I = 3; I > 0; I--)
374     if (Opcode & (0xffu << (8 * I)))
375       break;
376   ListSeparator LS;
377   OS << "\t.seh_custom\t";
378   for (; I >= 0; I--)
379     OS << LS << ((Opcode >> (8 * I)) & 0xff);
380   OS << "\n";
381 }
382 
383 class ARMTargetELFStreamer : public ARMTargetStreamer {
384 private:
385   StringRef CurrentVendor;
386   ARM::FPUKind FPU = ARM::FK_INVALID;
387   ARM::ArchKind Arch = ARM::ArchKind::INVALID;
388   ARM::ArchKind EmittedArch = ARM::ArchKind::INVALID;
389 
390   MCSection *AttributeSection = nullptr;
391 
392   void emitArchDefaultAttributes();
393   void emitFPUDefaultAttributes();
394 
395   ARMELFStreamer &getStreamer();
396 
397   void emitFnStart() override;
398   void emitFnEnd() override;
399   void emitCantUnwind() override;
400   void emitPersonality(const MCSymbol *Personality) override;
401   void emitPersonalityIndex(unsigned Index) override;
402   void emitHandlerData() override;
403   void emitSetFP(MCRegister FpReg, MCRegister SpReg,
404                  int64_t Offset = 0) override;
405   void emitMovSP(MCRegister Reg, int64_t Offset = 0) override;
406   void emitPad(int64_t Offset) override;
407   void emitRegSave(const SmallVectorImpl<MCRegister> &RegList,
408                    bool isVector) override;
409   void emitUnwindRaw(int64_t Offset,
410                      const SmallVectorImpl<uint8_t> &Opcodes) override;
411 
412   void switchVendor(StringRef Vendor) override;
413   void emitAttribute(unsigned Attribute, unsigned Value) override;
414   void emitTextAttribute(unsigned Attribute, StringRef String) override;
415   void emitIntTextAttribute(unsigned Attribute, unsigned IntValue,
416                             StringRef StringValue) override;
417   void emitArch(ARM::ArchKind Arch) override;
418   void emitObjectArch(ARM::ArchKind Arch) override;
419   void emitFPU(ARM::FPUKind FPU) override;
420   void emitInst(uint32_t Inst, char Suffix = '\0') override;
421   void finishAttributeSection() override;
422   void emitLabel(MCSymbol *Symbol) override;
423 
424   void annotateTLSDescriptorSequence(const MCSymbolRefExpr *SRE) override;
425   void emitThumbSet(MCSymbol *Symbol, const MCExpr *Value) override;
426 
427   // Reset state between object emissions
428   void reset() override;
429 
430   void finish() override;
431 
432 public:
433   ARMTargetELFStreamer(MCStreamer &S)
434     : ARMTargetStreamer(S), CurrentVendor("aeabi") {}
435 };
436 
437 /// Extend the generic ELFStreamer class so that it can emit mapping symbols at
438 /// the appropriate points in the object files. These symbols are defined in the
439 /// ARM ELF ABI: infocenter.arm.com/help/topic/com.arm.../IHI0044D_aaelf.pdf.
440 ///
441 /// In brief: $a, $t or $d should be emitted at the start of each contiguous
442 /// region of ARM code, Thumb code or data in a section. In practice, this
443 /// emission does not rely on explicit assembler directives but on inherent
444 /// properties of the directives doing the emission (e.g. ".byte" is data, "add
445 /// r0, r0, r0" an instruction).
446 ///
447 /// As a result this system is orthogonal to the DataRegion infrastructure used
448 /// by MachO. Beware!
449 class ARMELFStreamer : public MCELFStreamer {
450 public:
451   friend class ARMTargetELFStreamer;
452 
453   ARMELFStreamer(MCContext &Context, std::unique_ptr<MCAsmBackend> TAB,
454                  std::unique_ptr<MCObjectWriter> OW,
455                  std::unique_ptr<MCCodeEmitter> Emitter, bool IsThumb,
456                  bool IsAndroid)
457       : MCELFStreamer(Context, std::move(TAB), std::move(OW),
458                       std::move(Emitter)),
459         IsThumb(IsThumb), IsAndroid(IsAndroid) {
460     EHReset();
461   }
462 
463   ~ARMELFStreamer() override = default;
464 
465   // ARM exception handling directives
466   void emitFnStart();
467   void emitFnEnd();
468   void emitCantUnwind();
469   void emitPersonality(const MCSymbol *Per);
470   void emitPersonalityIndex(unsigned index);
471   void emitHandlerData();
472   void emitSetFP(MCRegister NewFpReg, MCRegister NewSpReg, int64_t Offset = 0);
473   void emitMovSP(MCRegister Reg, int64_t Offset = 0);
474   void emitPad(int64_t Offset);
475   void emitRegSave(const SmallVectorImpl<MCRegister> &RegList, bool isVector);
476   void emitUnwindRaw(int64_t Offset, const SmallVectorImpl<uint8_t> &Opcodes);
477   void emitFill(const MCExpr &NumBytes, uint64_t FillValue,
478                 SMLoc Loc) override {
479     emitDataMappingSymbol();
480     MCObjectStreamer::emitFill(NumBytes, FillValue, Loc);
481   }
482 
483   void changeSection(MCSection *Section, uint32_t Subsection) override {
484     LastMappingSymbols[getCurrentSection().first] = std::move(LastEMSInfo);
485     MCELFStreamer::changeSection(Section, Subsection);
486     auto LastMappingSymbol = LastMappingSymbols.find(Section);
487     if (LastMappingSymbol != LastMappingSymbols.end()) {
488       LastEMSInfo = std::move(LastMappingSymbol->second);
489       return;
490     }
491     LastEMSInfo.reset(new ElfMappingSymbolInfo);
492   }
493 
494   /// This function is the one used to emit instruction data into the ELF
495   /// streamer. We override it to add the appropriate mapping symbol if
496   /// necessary.
497   void emitInstruction(const MCInst &Inst,
498                        const MCSubtargetInfo &STI) override {
499     if (IsThumb)
500       EmitThumbMappingSymbol();
501     else
502       EmitARMMappingSymbol();
503 
504     MCELFStreamer::emitInstruction(Inst, STI);
505   }
506 
507   void emitInst(uint32_t Inst, char Suffix) {
508     unsigned Size;
509     char Buffer[4];
510     const bool LittleEndian = getContext().getAsmInfo()->isLittleEndian();
511 
512     switch (Suffix) {
513     case '\0':
514       Size = 4;
515 
516       assert(!IsThumb);
517       EmitARMMappingSymbol();
518       for (unsigned II = 0, IE = Size; II != IE; II++) {
519         const unsigned I = LittleEndian ? (Size - II - 1) : II;
520         Buffer[Size - II - 1] = uint8_t(Inst >> I * CHAR_BIT);
521       }
522 
523       break;
524     case 'n':
525     case 'w':
526       Size = (Suffix == 'n' ? 2 : 4);
527 
528       assert(IsThumb);
529       EmitThumbMappingSymbol();
530       // Thumb wide instructions are emitted as a pair of 16-bit words of the
531       // appropriate endianness.
532       for (unsigned II = 0, IE = Size; II != IE; II = II + 2) {
533         const unsigned I0 = LittleEndian ? II + 0 : II + 1;
534         const unsigned I1 = LittleEndian ? II + 1 : II + 0;
535         Buffer[Size - II - 2] = uint8_t(Inst >> I0 * CHAR_BIT);
536         Buffer[Size - II - 1] = uint8_t(Inst >> I1 * CHAR_BIT);
537       }
538 
539       break;
540     default:
541       llvm_unreachable("Invalid Suffix");
542     }
543 
544     MCELFStreamer::emitBytes(StringRef(Buffer, Size));
545   }
546 
547   /// This is one of the functions used to emit data into an ELF section, so the
548   /// ARM streamer overrides it to add the appropriate mapping symbol ($d) if
549   /// necessary.
550   void emitBytes(StringRef Data) override {
551     emitDataMappingSymbol();
552     MCELFStreamer::emitBytes(Data);
553   }
554 
555   void FlushPendingMappingSymbol() {
556     if (!LastEMSInfo->hasInfo())
557       return;
558     ElfMappingSymbolInfo *EMS = LastEMSInfo.get();
559     emitMappingSymbol("$d", *EMS->F, EMS->Offset);
560     EMS->resetInfo();
561   }
562 
563   /// This is one of the functions used to emit data into an ELF section, so the
564   /// ARM streamer overrides it to add the appropriate mapping symbol ($d) if
565   /// necessary.
566   void emitValueImpl(const MCExpr *Value, unsigned Size, SMLoc Loc) override {
567     if (const MCSymbolRefExpr *SRE = dyn_cast_or_null<MCSymbolRefExpr>(Value)) {
568       if (SRE->getKind() == MCSymbolRefExpr::VK_ARM_SBREL && !(Size == 4)) {
569         getContext().reportError(Loc, "relocated expression must be 32-bit");
570         return;
571       }
572       getOrCreateDataFragment();
573     }
574 
575     emitDataMappingSymbol();
576     MCELFStreamer::emitValueImpl(Value, Size, Loc);
577   }
578 
579   void emitAssemblerFlag(MCAssemblerFlag Flag) override {
580     MCELFStreamer::emitAssemblerFlag(Flag);
581 
582     switch (Flag) {
583     case MCAF_SyntaxUnified:
584       return; // no-op here.
585     case MCAF_Code16:
586       IsThumb = true;
587       return; // Change to Thumb mode
588     case MCAF_Code32:
589       IsThumb = false;
590       return; // Change to ARM mode
591     case MCAF_Code64:
592       return;
593     case MCAF_SubsectionsViaSymbols:
594       return;
595     }
596   }
597 
598   /// If a label is defined before the .type directive sets the label's type
599   /// then the label can't be recorded as thumb function when the label is
600   /// defined. We override emitSymbolAttribute() which is called as part of the
601   /// parsing of .type so that if the symbol has already been defined we can
602   /// record the label as Thumb. FIXME: there is a corner case where the state
603   /// is changed in between the label definition and the .type directive, this
604   /// is not expected to occur in practice and handling it would require the
605   /// backend to track IsThumb for every label.
606   bool emitSymbolAttribute(MCSymbol *Symbol, MCSymbolAttr Attribute) override {
607     bool Val = MCELFStreamer::emitSymbolAttribute(Symbol, Attribute);
608 
609     if (!IsThumb)
610       return Val;
611 
612     unsigned Type = cast<MCSymbolELF>(Symbol)->getType();
613     if ((Type == ELF::STT_FUNC || Type == ELF::STT_GNU_IFUNC) &&
614         Symbol->isDefined())
615       getAssembler().setIsThumbFunc(Symbol);
616 
617     return Val;
618   };
619 
620 private:
621   enum ElfMappingSymbol {
622     EMS_None,
623     EMS_ARM,
624     EMS_Thumb,
625     EMS_Data
626   };
627 
628   struct ElfMappingSymbolInfo {
629     void resetInfo() {
630       F = nullptr;
631       Offset = 0;
632     }
633     bool hasInfo() { return F != nullptr; }
634     MCDataFragment *F = nullptr;
635     uint64_t Offset = 0;
636     ElfMappingSymbol State = EMS_None;
637   };
638 
639   void emitDataMappingSymbol() {
640     if (LastEMSInfo->State == EMS_Data)
641       return;
642     else if (LastEMSInfo->State == EMS_None) {
643       // This is a tentative symbol, it won't really be emitted until it's
644       // actually needed.
645       ElfMappingSymbolInfo *EMS = LastEMSInfo.get();
646       auto *DF = dyn_cast_or_null<MCDataFragment>(getCurrentFragment());
647       if (!DF)
648         return;
649       EMS->F = DF;
650       EMS->Offset = DF->getContents().size();
651       LastEMSInfo->State = EMS_Data;
652       return;
653     }
654     EmitMappingSymbol("$d");
655     LastEMSInfo->State = EMS_Data;
656   }
657 
658   void EmitThumbMappingSymbol() {
659     if (LastEMSInfo->State == EMS_Thumb)
660       return;
661     FlushPendingMappingSymbol();
662     EmitMappingSymbol("$t");
663     LastEMSInfo->State = EMS_Thumb;
664   }
665 
666   void EmitARMMappingSymbol() {
667     if (LastEMSInfo->State == EMS_ARM)
668       return;
669     FlushPendingMappingSymbol();
670     EmitMappingSymbol("$a");
671     LastEMSInfo->State = EMS_ARM;
672   }
673 
674   void EmitMappingSymbol(StringRef Name) {
675     auto *Symbol = cast<MCSymbolELF>(getContext().createLocalSymbol(Name));
676     emitLabel(Symbol);
677 
678     Symbol->setType(ELF::STT_NOTYPE);
679     Symbol->setBinding(ELF::STB_LOCAL);
680   }
681 
682   void emitMappingSymbol(StringRef Name, MCDataFragment &F, uint64_t Offset) {
683     auto *Symbol = cast<MCSymbolELF>(getContext().createLocalSymbol(Name));
684     emitLabelAtPos(Symbol, SMLoc(), F, Offset);
685     Symbol->setType(ELF::STT_NOTYPE);
686     Symbol->setBinding(ELF::STB_LOCAL);
687   }
688 
689   void emitThumbFunc(MCSymbol *Func) override {
690     getAssembler().setIsThumbFunc(Func);
691     emitSymbolAttribute(Func, MCSA_ELF_TypeFunction);
692   }
693 
694   // Helper functions for ARM exception handling directives
695   void EHReset();
696 
697   // Reset state between object emissions
698   void reset() override;
699 
700   void EmitPersonalityFixup(StringRef Name);
701   void FlushPendingOffset();
702   void FlushUnwindOpcodes(bool NoHandlerData);
703 
704   void SwitchToEHSection(StringRef Prefix, unsigned Type, unsigned Flags,
705                          SectionKind Kind, const MCSymbol &Fn);
706   void SwitchToExTabSection(const MCSymbol &FnStart);
707   void SwitchToExIdxSection(const MCSymbol &FnStart);
708 
709   void EmitFixup(const MCExpr *Expr, MCFixupKind Kind);
710 
711   bool IsThumb;
712   bool IsAndroid;
713 
714   DenseMap<const MCSection *, std::unique_ptr<ElfMappingSymbolInfo>>
715       LastMappingSymbols;
716 
717   std::unique_ptr<ElfMappingSymbolInfo> LastEMSInfo;
718 
719   // ARM Exception Handling Frame Information
720   MCSymbol *ExTab;
721   MCSymbol *FnStart;
722   const MCSymbol *Personality;
723   unsigned PersonalityIndex;
724   MCRegister FPReg; // Frame pointer register
725   int64_t FPOffset; // Offset: (final frame pointer) - (initial $sp)
726   int64_t SPOffset; // Offset: (final $sp) - (initial $sp)
727   int64_t PendingOffset; // Offset: (final $sp) - (emitted $sp)
728   bool UsedFP;
729   bool CantUnwind;
730   SmallVector<uint8_t, 64> Opcodes;
731   UnwindOpcodeAssembler UnwindOpAsm;
732 };
733 
734 } // end anonymous namespace
735 
736 ARMELFStreamer &ARMTargetELFStreamer::getStreamer() {
737   return static_cast<ARMELFStreamer &>(Streamer);
738 }
739 
740 void ARMTargetELFStreamer::emitFnStart() { getStreamer().emitFnStart(); }
741 void ARMTargetELFStreamer::emitFnEnd() { getStreamer().emitFnEnd(); }
742 void ARMTargetELFStreamer::emitCantUnwind() { getStreamer().emitCantUnwind(); }
743 
744 void ARMTargetELFStreamer::emitPersonality(const MCSymbol *Personality) {
745   getStreamer().emitPersonality(Personality);
746 }
747 
748 void ARMTargetELFStreamer::emitPersonalityIndex(unsigned Index) {
749   getStreamer().emitPersonalityIndex(Index);
750 }
751 
752 void ARMTargetELFStreamer::emitHandlerData() {
753   getStreamer().emitHandlerData();
754 }
755 
756 void ARMTargetELFStreamer::emitSetFP(MCRegister FpReg, MCRegister SpReg,
757                                      int64_t Offset) {
758   getStreamer().emitSetFP(FpReg, SpReg, Offset);
759 }
760 
761 void ARMTargetELFStreamer::emitMovSP(MCRegister Reg, int64_t Offset) {
762   getStreamer().emitMovSP(Reg, Offset);
763 }
764 
765 void ARMTargetELFStreamer::emitPad(int64_t Offset) {
766   getStreamer().emitPad(Offset);
767 }
768 
769 void ARMTargetELFStreamer::emitRegSave(
770     const SmallVectorImpl<MCRegister> &RegList, bool isVector) {
771   getStreamer().emitRegSave(RegList, isVector);
772 }
773 
774 void ARMTargetELFStreamer::emitUnwindRaw(int64_t Offset,
775                                       const SmallVectorImpl<uint8_t> &Opcodes) {
776   getStreamer().emitUnwindRaw(Offset, Opcodes);
777 }
778 
779 void ARMTargetELFStreamer::switchVendor(StringRef Vendor) {
780   assert(!Vendor.empty() && "Vendor cannot be empty.");
781 
782   if (CurrentVendor == Vendor)
783     return;
784 
785   if (!CurrentVendor.empty())
786     finishAttributeSection();
787 
788   assert(getStreamer().Contents.empty() &&
789          ".ARM.attributes should be flushed before changing vendor");
790   CurrentVendor = Vendor;
791 
792 }
793 
794 void ARMTargetELFStreamer::emitAttribute(unsigned Attribute, unsigned Value) {
795   getStreamer().setAttributeItem(Attribute, Value,
796                                  /* OverwriteExisting= */ true);
797 }
798 
799 void ARMTargetELFStreamer::emitTextAttribute(unsigned Attribute,
800                                              StringRef Value) {
801   getStreamer().setAttributeItem(Attribute, Value,
802                                  /* OverwriteExisting= */ true);
803 }
804 
805 void ARMTargetELFStreamer::emitIntTextAttribute(unsigned Attribute,
806                                                 unsigned IntValue,
807                                                 StringRef StringValue) {
808   getStreamer().setAttributeItems(Attribute, IntValue, StringValue,
809                                   /* OverwriteExisting= */ true);
810 }
811 
812 void ARMTargetELFStreamer::emitArch(ARM::ArchKind Value) {
813   Arch = Value;
814 }
815 
816 void ARMTargetELFStreamer::emitObjectArch(ARM::ArchKind Value) {
817   EmittedArch = Value;
818 }
819 
820 void ARMTargetELFStreamer::emitArchDefaultAttributes() {
821   using namespace ARMBuildAttrs;
822   ARMELFStreamer &S = getStreamer();
823 
824   S.setAttributeItem(CPU_name, ARM::getCPUAttr(Arch), false);
825 
826   if (EmittedArch == ARM::ArchKind::INVALID)
827     S.setAttributeItem(CPU_arch, ARM::getArchAttr(Arch), false);
828   else
829     S.setAttributeItem(CPU_arch, ARM::getArchAttr(EmittedArch), false);
830 
831   switch (Arch) {
832   case ARM::ArchKind::ARMV4:
833     S.setAttributeItem(ARM_ISA_use, Allowed, false);
834     break;
835 
836   case ARM::ArchKind::ARMV4T:
837   case ARM::ArchKind::ARMV5T:
838   case ARM::ArchKind::XSCALE:
839   case ARM::ArchKind::ARMV5TE:
840   case ARM::ArchKind::ARMV6:
841     S.setAttributeItem(ARM_ISA_use, Allowed, false);
842     S.setAttributeItem(THUMB_ISA_use, Allowed, false);
843     break;
844 
845   case ARM::ArchKind::ARMV6T2:
846     S.setAttributeItem(ARM_ISA_use, Allowed, false);
847     S.setAttributeItem(THUMB_ISA_use, AllowThumb32, false);
848     break;
849 
850   case ARM::ArchKind::ARMV6K:
851   case ARM::ArchKind::ARMV6KZ:
852     S.setAttributeItem(ARM_ISA_use, Allowed, false);
853     S.setAttributeItem(THUMB_ISA_use, Allowed, false);
854     S.setAttributeItem(Virtualization_use, AllowTZ, false);
855     break;
856 
857   case ARM::ArchKind::ARMV6M:
858     S.setAttributeItem(THUMB_ISA_use, Allowed, false);
859     break;
860 
861   case ARM::ArchKind::ARMV7A:
862     S.setAttributeItem(CPU_arch_profile, ApplicationProfile, false);
863     S.setAttributeItem(ARM_ISA_use, Allowed, false);
864     S.setAttributeItem(THUMB_ISA_use, AllowThumb32, false);
865     break;
866 
867   case ARM::ArchKind::ARMV7R:
868     S.setAttributeItem(CPU_arch_profile, RealTimeProfile, false);
869     S.setAttributeItem(ARM_ISA_use, Allowed, false);
870     S.setAttributeItem(THUMB_ISA_use, AllowThumb32, false);
871     break;
872 
873   case ARM::ArchKind::ARMV7EM:
874   case ARM::ArchKind::ARMV7M:
875     S.setAttributeItem(CPU_arch_profile, MicroControllerProfile, false);
876     S.setAttributeItem(THUMB_ISA_use, AllowThumb32, false);
877     break;
878 
879   case ARM::ArchKind::ARMV8A:
880   case ARM::ArchKind::ARMV8_1A:
881   case ARM::ArchKind::ARMV8_2A:
882   case ARM::ArchKind::ARMV8_3A:
883   case ARM::ArchKind::ARMV8_4A:
884   case ARM::ArchKind::ARMV8_5A:
885   case ARM::ArchKind::ARMV8_6A:
886   case ARM::ArchKind::ARMV8_7A:
887   case ARM::ArchKind::ARMV8_8A:
888   case ARM::ArchKind::ARMV8_9A:
889   case ARM::ArchKind::ARMV9A:
890   case ARM::ArchKind::ARMV9_1A:
891   case ARM::ArchKind::ARMV9_2A:
892   case ARM::ArchKind::ARMV9_3A:
893   case ARM::ArchKind::ARMV9_4A:
894   case ARM::ArchKind::ARMV9_5A:
895   case ARM::ArchKind::ARMV9_6A:
896     S.setAttributeItem(CPU_arch_profile, ApplicationProfile, false);
897     S.setAttributeItem(ARM_ISA_use, Allowed, false);
898     S.setAttributeItem(THUMB_ISA_use, AllowThumb32, false);
899     S.setAttributeItem(MPextension_use, Allowed, false);
900     S.setAttributeItem(Virtualization_use, AllowTZVirtualization, false);
901     break;
902 
903   case ARM::ArchKind::ARMV8MBaseline:
904   case ARM::ArchKind::ARMV8MMainline:
905     S.setAttributeItem(THUMB_ISA_use, AllowThumbDerived, false);
906     S.setAttributeItem(CPU_arch_profile, MicroControllerProfile, false);
907     break;
908 
909   case ARM::ArchKind::IWMMXT:
910     S.setAttributeItem(ARM_ISA_use, Allowed, false);
911     S.setAttributeItem(THUMB_ISA_use, Allowed, false);
912     S.setAttributeItem(WMMX_arch, AllowWMMXv1, false);
913     break;
914 
915   case ARM::ArchKind::IWMMXT2:
916     S.setAttributeItem(ARM_ISA_use, Allowed, false);
917     S.setAttributeItem(THUMB_ISA_use, Allowed, false);
918     S.setAttributeItem(WMMX_arch, AllowWMMXv2, false);
919     break;
920 
921   default:
922     report_fatal_error("Unknown Arch: " + Twine(ARM::getArchName(Arch)));
923     break;
924   }
925 }
926 
927 void ARMTargetELFStreamer::emitFPU(ARM::FPUKind Value) { FPU = Value; }
928 
929 void ARMTargetELFStreamer::emitFPUDefaultAttributes() {
930   ARMELFStreamer &S = getStreamer();
931 
932   switch (FPU) {
933   case ARM::FK_VFP:
934   case ARM::FK_VFPV2:
935     S.setAttributeItem(ARMBuildAttrs::FP_arch, ARMBuildAttrs::AllowFPv2,
936                        /* OverwriteExisting= */ false);
937     break;
938 
939   case ARM::FK_VFPV3:
940     S.setAttributeItem(ARMBuildAttrs::FP_arch, ARMBuildAttrs::AllowFPv3A,
941                        /* OverwriteExisting= */ false);
942     break;
943 
944   case ARM::FK_VFPV3_FP16:
945     S.setAttributeItem(ARMBuildAttrs::FP_arch, ARMBuildAttrs::AllowFPv3A,
946                        /* OverwriteExisting= */ false);
947     S.setAttributeItem(ARMBuildAttrs::FP_HP_extension, ARMBuildAttrs::AllowHPFP,
948                        /* OverwriteExisting= */ false);
949     break;
950 
951   case ARM::FK_VFPV3_D16:
952     S.setAttributeItem(ARMBuildAttrs::FP_arch, ARMBuildAttrs::AllowFPv3B,
953                        /* OverwriteExisting= */ false);
954     break;
955 
956   case ARM::FK_VFPV3_D16_FP16:
957     S.setAttributeItem(ARMBuildAttrs::FP_arch, ARMBuildAttrs::AllowFPv3B,
958                        /* OverwriteExisting= */ false);
959     S.setAttributeItem(ARMBuildAttrs::FP_HP_extension, ARMBuildAttrs::AllowHPFP,
960                        /* OverwriteExisting= */ false);
961     break;
962 
963   case ARM::FK_VFPV3XD:
964     S.setAttributeItem(ARMBuildAttrs::FP_arch, ARMBuildAttrs::AllowFPv3B,
965                        /* OverwriteExisting= */ false);
966     break;
967   case ARM::FK_VFPV3XD_FP16:
968     S.setAttributeItem(ARMBuildAttrs::FP_arch, ARMBuildAttrs::AllowFPv3B,
969                        /* OverwriteExisting= */ false);
970     S.setAttributeItem(ARMBuildAttrs::FP_HP_extension, ARMBuildAttrs::AllowHPFP,
971                        /* OverwriteExisting= */ false);
972     break;
973 
974   case ARM::FK_VFPV4:
975     S.setAttributeItem(ARMBuildAttrs::FP_arch, ARMBuildAttrs::AllowFPv4A,
976                        /* OverwriteExisting= */ false);
977     break;
978 
979   // ABI_HardFP_use is handled in ARMAsmPrinter, so _SP_D16 is treated the same
980   // as _D16 here.
981   case ARM::FK_FPV4_SP_D16:
982   case ARM::FK_VFPV4_D16:
983     S.setAttributeItem(ARMBuildAttrs::FP_arch, ARMBuildAttrs::AllowFPv4B,
984                        /* OverwriteExisting= */ false);
985     break;
986 
987   case ARM::FK_FP_ARMV8:
988     S.setAttributeItem(ARMBuildAttrs::FP_arch, ARMBuildAttrs::AllowFPARMv8A,
989                        /* OverwriteExisting= */ false);
990     break;
991 
992   // FPV5_D16 is identical to FP_ARMV8 except for the number of D registers, so
993   // uses the FP_ARMV8_D16 build attribute.
994   case ARM::FK_FPV5_SP_D16:
995   case ARM::FK_FPV5_D16:
996   // FPv5 and FP-ARMv8 have the same instructions, so are modeled as one
997   // FPU, but there are two different names for it depending on the CPU.
998   case ARM::FK_FP_ARMV8_FULLFP16_SP_D16:
999   case ARM::FK_FP_ARMV8_FULLFP16_D16:
1000     S.setAttributeItem(ARMBuildAttrs::FP_arch, ARMBuildAttrs::AllowFPARMv8B,
1001                        /* OverwriteExisting= */ false);
1002     break;
1003 
1004   case ARM::FK_NEON:
1005     S.setAttributeItem(ARMBuildAttrs::FP_arch, ARMBuildAttrs::AllowFPv3A,
1006                        /* OverwriteExisting= */ false);
1007     S.setAttributeItem(ARMBuildAttrs::Advanced_SIMD_arch,
1008                        ARMBuildAttrs::AllowNeon,
1009                        /* OverwriteExisting= */ false);
1010     break;
1011 
1012   case ARM::FK_NEON_FP16:
1013     S.setAttributeItem(ARMBuildAttrs::FP_arch, ARMBuildAttrs::AllowFPv3A,
1014                        /* OverwriteExisting= */ false);
1015     S.setAttributeItem(ARMBuildAttrs::Advanced_SIMD_arch,
1016                        ARMBuildAttrs::AllowNeon,
1017                        /* OverwriteExisting= */ false);
1018     S.setAttributeItem(ARMBuildAttrs::FP_HP_extension, ARMBuildAttrs::AllowHPFP,
1019                        /* OverwriteExisting= */ false);
1020     break;
1021 
1022   case ARM::FK_NEON_VFPV4:
1023     S.setAttributeItem(ARMBuildAttrs::FP_arch, ARMBuildAttrs::AllowFPv4A,
1024                        /* OverwriteExisting= */ false);
1025     S.setAttributeItem(ARMBuildAttrs::Advanced_SIMD_arch,
1026                        ARMBuildAttrs::AllowNeon2,
1027                        /* OverwriteExisting= */ false);
1028     break;
1029 
1030   case ARM::FK_NEON_FP_ARMV8:
1031   case ARM::FK_CRYPTO_NEON_FP_ARMV8:
1032     S.setAttributeItem(ARMBuildAttrs::FP_arch, ARMBuildAttrs::AllowFPARMv8A,
1033                        /* OverwriteExisting= */ false);
1034     // 'Advanced_SIMD_arch' must be emitted not here, but within
1035     // ARMAsmPrinter::emitAttributes(), depending on hasV8Ops() and hasV8_1a()
1036     break;
1037 
1038   case ARM::FK_SOFTVFP:
1039   case ARM::FK_NONE:
1040     break;
1041 
1042   default:
1043     report_fatal_error("Unknown FPU: " + Twine(FPU));
1044     break;
1045   }
1046 }
1047 
1048 void ARMTargetELFStreamer::finishAttributeSection() {
1049   ARMELFStreamer &S = getStreamer();
1050 
1051   if (FPU != ARM::FK_INVALID)
1052     emitFPUDefaultAttributes();
1053 
1054   if (Arch != ARM::ArchKind::INVALID)
1055     emitArchDefaultAttributes();
1056 
1057   if (S.Contents.empty())
1058     return;
1059 
1060   auto LessTag = [](const MCELFStreamer::AttributeItem &LHS,
1061                     const MCELFStreamer::AttributeItem &RHS) -> bool {
1062     // The conformance tag must be emitted first when serialised into an
1063     // object file. Specifically, the addenda to the ARM ABI states that
1064     // (2.3.7.4):
1065     //
1066     // "To simplify recognition by consumers in the common case of claiming
1067     // conformity for the whole file, this tag should be emitted first in a
1068     // file-scope sub-subsection of the first public subsection of the
1069     // attributes section."
1070     //
1071     // So it is special-cased in this comparison predicate when the
1072     // attributes are sorted in finishAttributeSection().
1073     return (RHS.Tag != ARMBuildAttrs::conformance) &&
1074            ((LHS.Tag == ARMBuildAttrs::conformance) || (LHS.Tag < RHS.Tag));
1075   };
1076   llvm::sort(S.Contents, LessTag);
1077 
1078   S.emitAttributesSection(CurrentVendor, ".ARM.attributes",
1079                           ELF::SHT_ARM_ATTRIBUTES, AttributeSection);
1080 
1081   FPU = ARM::FK_INVALID;
1082 }
1083 
1084 void ARMTargetELFStreamer::emitLabel(MCSymbol *Symbol) {
1085   ARMELFStreamer &Streamer = getStreamer();
1086   if (!Streamer.IsThumb)
1087     return;
1088 
1089   Streamer.getAssembler().registerSymbol(*Symbol);
1090   unsigned Type = cast<MCSymbolELF>(Symbol)->getType();
1091   if (Type == ELF::STT_FUNC || Type == ELF::STT_GNU_IFUNC)
1092     Streamer.emitThumbFunc(Symbol);
1093 }
1094 
1095 void ARMTargetELFStreamer::annotateTLSDescriptorSequence(
1096     const MCSymbolRefExpr *S) {
1097   getStreamer().EmitFixup(S, FK_Data_4);
1098 }
1099 
1100 void ARMTargetELFStreamer::emitThumbSet(MCSymbol *Symbol, const MCExpr *Value) {
1101   if (const MCSymbolRefExpr *SRE = dyn_cast<MCSymbolRefExpr>(Value)) {
1102     const MCSymbol &Sym = SRE->getSymbol();
1103     if (!Sym.isDefined()) {
1104       getStreamer().emitAssignment(Symbol, Value);
1105       return;
1106     }
1107   }
1108 
1109   getStreamer().emitThumbFunc(Symbol);
1110   getStreamer().emitAssignment(Symbol, Value);
1111 }
1112 
1113 void ARMTargetELFStreamer::emitInst(uint32_t Inst, char Suffix) {
1114   getStreamer().emitInst(Inst, Suffix);
1115 }
1116 
1117 void ARMTargetELFStreamer::reset() { AttributeSection = nullptr; }
1118 
1119 void ARMTargetELFStreamer::finish() {
1120   ARMTargetStreamer::finish();
1121   finishAttributeSection();
1122 
1123   // The mix of execute-only and non-execute-only at link time is
1124   // non-execute-only. To avoid the empty implicitly created .text
1125   // section from making the whole .text section non-execute-only, we
1126   // mark it execute-only if it is empty and there is at least one
1127   // execute-only section in the object.
1128   MCContext &Ctx = getStreamer().getContext();
1129   auto &Asm = getStreamer().getAssembler();
1130   if (any_of(Asm, [](const MCSection &Sec) {
1131         return cast<MCSectionELF>(Sec).getFlags() & ELF::SHF_ARM_PURECODE;
1132       })) {
1133     auto *Text =
1134         static_cast<MCSectionELF *>(Ctx.getObjectFileInfo()->getTextSection());
1135     for (auto &F : *Text)
1136       if (auto *DF = dyn_cast<MCDataFragment>(&F))
1137         if (!DF->getContents().empty())
1138           return;
1139     Text->setFlags(Text->getFlags() | ELF::SHF_ARM_PURECODE);
1140   }
1141 }
1142 
1143 void ARMELFStreamer::reset() {
1144   MCTargetStreamer &TS = *getTargetStreamer();
1145   ARMTargetStreamer &ATS = static_cast<ARMTargetStreamer &>(TS);
1146   ATS.reset();
1147   MCELFStreamer::reset();
1148   LastMappingSymbols.clear();
1149   LastEMSInfo.reset();
1150   // MCELFStreamer clear's the assembler's e_flags. However, for
1151   // arm we manually set the ABI version on streamer creation, so
1152   // do the same here
1153   getWriter().setELFHeaderEFlags(ELF::EF_ARM_EABI_VER5);
1154 }
1155 
1156 inline void ARMELFStreamer::SwitchToEHSection(StringRef Prefix,
1157                                               unsigned Type,
1158                                               unsigned Flags,
1159                                               SectionKind Kind,
1160                                               const MCSymbol &Fn) {
1161   const MCSectionELF &FnSection =
1162     static_cast<const MCSectionELF &>(Fn.getSection());
1163 
1164   // Create the name for new section
1165   StringRef FnSecName(FnSection.getName());
1166   SmallString<128> EHSecName(Prefix);
1167   if (FnSecName != ".text") {
1168     EHSecName += FnSecName;
1169   }
1170 
1171   // Get .ARM.extab or .ARM.exidx section
1172   const MCSymbolELF *Group = FnSection.getGroup();
1173   if (Group)
1174     Flags |= ELF::SHF_GROUP;
1175   MCSectionELF *EHSection = getContext().getELFSection(
1176       EHSecName, Type, Flags, 0, Group, /*IsComdat=*/true,
1177       FnSection.getUniqueID(),
1178       static_cast<const MCSymbolELF *>(FnSection.getBeginSymbol()));
1179 
1180   assert(EHSection && "Failed to get the required EH section");
1181 
1182   // Switch to .ARM.extab or .ARM.exidx section
1183   switchSection(EHSection);
1184   emitValueToAlignment(Align(4), 0, 1, 0);
1185 }
1186 
1187 inline void ARMELFStreamer::SwitchToExTabSection(const MCSymbol &FnStart) {
1188   SwitchToEHSection(".ARM.extab", ELF::SHT_PROGBITS, ELF::SHF_ALLOC,
1189                     SectionKind::getData(), FnStart);
1190 }
1191 
1192 inline void ARMELFStreamer::SwitchToExIdxSection(const MCSymbol &FnStart) {
1193   SwitchToEHSection(".ARM.exidx", ELF::SHT_ARM_EXIDX,
1194                     ELF::SHF_ALLOC | ELF::SHF_LINK_ORDER,
1195                     SectionKind::getData(), FnStart);
1196 }
1197 
1198 void ARMELFStreamer::EmitFixup(const MCExpr *Expr, MCFixupKind Kind) {
1199   MCDataFragment *Frag = getOrCreateDataFragment();
1200   Frag->getFixups().push_back(MCFixup::create(Frag->getContents().size(), Expr,
1201                                               Kind));
1202 }
1203 
1204 void ARMELFStreamer::EHReset() {
1205   ExTab = nullptr;
1206   FnStart = nullptr;
1207   Personality = nullptr;
1208   PersonalityIndex = ARM::EHABI::NUM_PERSONALITY_INDEX;
1209   FPReg = ARM::SP;
1210   FPOffset = 0;
1211   SPOffset = 0;
1212   PendingOffset = 0;
1213   UsedFP = false;
1214   CantUnwind = false;
1215 
1216   Opcodes.clear();
1217   UnwindOpAsm.Reset();
1218 }
1219 
1220 void ARMELFStreamer::emitFnStart() {
1221   assert(FnStart == nullptr);
1222   FnStart = getContext().createTempSymbol();
1223   emitLabel(FnStart);
1224 }
1225 
1226 void ARMELFStreamer::emitFnEnd() {
1227   assert(FnStart && ".fnstart must precedes .fnend");
1228 
1229   // Emit unwind opcodes if there is no .handlerdata directive
1230   if (!ExTab && !CantUnwind)
1231     FlushUnwindOpcodes(true);
1232 
1233   // Emit the exception index table entry
1234   SwitchToExIdxSection(*FnStart);
1235 
1236   // The EHABI requires a dependency preserving R_ARM_NONE relocation to the
1237   // personality routine to protect it from an arbitrary platform's static
1238   // linker garbage collection. We disable this for Android where the unwinder
1239   // is either dynamically linked or directly references the personality
1240   // routine.
1241   if (PersonalityIndex < ARM::EHABI::NUM_PERSONALITY_INDEX && !IsAndroid)
1242     EmitPersonalityFixup(GetAEABIUnwindPersonalityName(PersonalityIndex));
1243 
1244   const MCSymbolRefExpr *FnStartRef =
1245     MCSymbolRefExpr::create(FnStart,
1246                             MCSymbolRefExpr::VK_ARM_PREL31,
1247                             getContext());
1248 
1249   emitValue(FnStartRef, 4);
1250 
1251   if (CantUnwind) {
1252     emitInt32(ARM::EHABI::EXIDX_CANTUNWIND);
1253   } else if (ExTab) {
1254     // Emit a reference to the unwind opcodes in the ".ARM.extab" section.
1255     const MCSymbolRefExpr *ExTabEntryRef =
1256       MCSymbolRefExpr::create(ExTab,
1257                               MCSymbolRefExpr::VK_ARM_PREL31,
1258                               getContext());
1259     emitValue(ExTabEntryRef, 4);
1260   } else {
1261     // For the __aeabi_unwind_cpp_pr0, we have to emit the unwind opcodes in
1262     // the second word of exception index table entry.  The size of the unwind
1263     // opcodes should always be 4 bytes.
1264     assert(PersonalityIndex == ARM::EHABI::AEABI_UNWIND_CPP_PR0 &&
1265            "Compact model must use __aeabi_unwind_cpp_pr0 as personality");
1266     assert(Opcodes.size() == 4u &&
1267            "Unwind opcode size for __aeabi_unwind_cpp_pr0 must be equal to 4");
1268     uint64_t Intval = Opcodes[0] |
1269                       Opcodes[1] << 8 |
1270                       Opcodes[2] << 16 |
1271                       Opcodes[3] << 24;
1272     emitIntValue(Intval, Opcodes.size());
1273   }
1274 
1275   // Switch to the section containing FnStart
1276   switchSection(&FnStart->getSection());
1277 
1278   // Clean exception handling frame information
1279   EHReset();
1280 }
1281 
1282 void ARMELFStreamer::emitCantUnwind() { CantUnwind = true; }
1283 
1284 // Add the R_ARM_NONE fixup at the same position
1285 void ARMELFStreamer::EmitPersonalityFixup(StringRef Name) {
1286   const MCSymbol *PersonalitySym = getContext().getOrCreateSymbol(Name);
1287 
1288   const MCSymbolRefExpr *PersonalityRef = MCSymbolRefExpr::create(
1289       PersonalitySym, MCSymbolRefExpr::VK_ARM_NONE, getContext());
1290 
1291   visitUsedExpr(*PersonalityRef);
1292   MCDataFragment *DF = getOrCreateDataFragment();
1293   DF->getFixups().push_back(MCFixup::create(DF->getContents().size(),
1294                                             PersonalityRef,
1295                                             MCFixup::getKindForSize(4, false)));
1296 }
1297 
1298 void ARMELFStreamer::FlushPendingOffset() {
1299   if (PendingOffset != 0) {
1300     UnwindOpAsm.EmitSPOffset(-PendingOffset);
1301     PendingOffset = 0;
1302   }
1303 }
1304 
1305 void ARMELFStreamer::FlushUnwindOpcodes(bool NoHandlerData) {
1306   // Emit the unwind opcode to restore $sp.
1307   if (UsedFP) {
1308     const MCRegisterInfo *MRI = getContext().getRegisterInfo();
1309     int64_t LastRegSaveSPOffset = SPOffset - PendingOffset;
1310     UnwindOpAsm.EmitSPOffset(LastRegSaveSPOffset - FPOffset);
1311     UnwindOpAsm.EmitSetSP(MRI->getEncodingValue(FPReg));
1312   } else {
1313     FlushPendingOffset();
1314   }
1315 
1316   // Finalize the unwind opcode sequence
1317   UnwindOpAsm.Finalize(PersonalityIndex, Opcodes);
1318 
1319   // For compact model 0, we have to emit the unwind opcodes in the .ARM.exidx
1320   // section.  Thus, we don't have to create an entry in the .ARM.extab
1321   // section.
1322   if (NoHandlerData && PersonalityIndex == ARM::EHABI::AEABI_UNWIND_CPP_PR0)
1323     return;
1324 
1325   // Switch to .ARM.extab section.
1326   SwitchToExTabSection(*FnStart);
1327 
1328   // Create .ARM.extab label for offset in .ARM.exidx
1329   assert(!ExTab);
1330   ExTab = getContext().createTempSymbol();
1331   emitLabel(ExTab);
1332 
1333   // Emit personality
1334   if (Personality) {
1335     const MCSymbolRefExpr *PersonalityRef =
1336       MCSymbolRefExpr::create(Personality,
1337                               MCSymbolRefExpr::VK_ARM_PREL31,
1338                               getContext());
1339 
1340     emitValue(PersonalityRef, 4);
1341   }
1342 
1343   // Emit unwind opcodes
1344   assert((Opcodes.size() % 4) == 0 &&
1345          "Unwind opcode size for __aeabi_cpp_unwind_pr0 must be multiple of 4");
1346   for (unsigned I = 0; I != Opcodes.size(); I += 4) {
1347     uint64_t Intval = Opcodes[I] |
1348                       Opcodes[I + 1] << 8 |
1349                       Opcodes[I + 2] << 16 |
1350                       Opcodes[I + 3] << 24;
1351     emitInt32(Intval);
1352   }
1353 
1354   // According to ARM EHABI section 9.2, if the __aeabi_unwind_cpp_pr1() or
1355   // __aeabi_unwind_cpp_pr2() is used, then the handler data must be emitted
1356   // after the unwind opcodes.  The handler data consists of several 32-bit
1357   // words, and should be terminated by zero.
1358   //
1359   // In case that the .handlerdata directive is not specified by the
1360   // programmer, we should emit zero to terminate the handler data.
1361   if (NoHandlerData && !Personality)
1362     emitInt32(0);
1363 }
1364 
1365 void ARMELFStreamer::emitHandlerData() { FlushUnwindOpcodes(false); }
1366 
1367 void ARMELFStreamer::emitPersonality(const MCSymbol *Per) {
1368   Personality = Per;
1369   UnwindOpAsm.setPersonality(Per);
1370 }
1371 
1372 void ARMELFStreamer::emitPersonalityIndex(unsigned Index) {
1373   assert(Index < ARM::EHABI::NUM_PERSONALITY_INDEX && "invalid index");
1374   PersonalityIndex = Index;
1375 }
1376 
1377 void ARMELFStreamer::emitSetFP(MCRegister NewFPReg, MCRegister NewSPReg,
1378                                int64_t Offset) {
1379   assert((NewSPReg == ARM::SP || NewSPReg == FPReg) &&
1380          "the operand of .setfp directive should be either $sp or $fp");
1381 
1382   UsedFP = true;
1383   FPReg = NewFPReg;
1384 
1385   if (NewSPReg == ARM::SP)
1386     FPOffset = SPOffset + Offset;
1387   else
1388     FPOffset += Offset;
1389 }
1390 
1391 void ARMELFStreamer::emitMovSP(MCRegister Reg, int64_t Offset) {
1392   assert((Reg != ARM::SP && Reg != ARM::PC) &&
1393          "the operand of .movsp cannot be either sp or pc");
1394   assert(FPReg == ARM::SP && "current FP must be SP");
1395 
1396   FlushPendingOffset();
1397 
1398   FPReg = Reg;
1399   FPOffset = SPOffset + Offset;
1400 
1401   const MCRegisterInfo *MRI = getContext().getRegisterInfo();
1402   UnwindOpAsm.EmitSetSP(MRI->getEncodingValue(FPReg));
1403 }
1404 
1405 void ARMELFStreamer::emitPad(int64_t Offset) {
1406   // Track the change of the $sp offset
1407   SPOffset -= Offset;
1408 
1409   // To squash multiple .pad directives, we should delay the unwind opcode
1410   // until the .save, .vsave, .handlerdata, or .fnend directives.
1411   PendingOffset -= Offset;
1412 }
1413 
1414 static std::pair<unsigned, unsigned>
1415 collectHWRegs(const MCRegisterInfo &MRI, unsigned Idx,
1416               const SmallVectorImpl<MCRegister> &RegList, bool IsVector,
1417               uint32_t &Mask_) {
1418   uint32_t Mask = 0;
1419   unsigned Count = 0;
1420   while (Idx > 0) {
1421     MCRegister Reg = RegList[Idx - 1];
1422     if (Reg == ARM::RA_AUTH_CODE)
1423       break;
1424     unsigned RegEnc = MRI.getEncodingValue(Reg);
1425     assert(RegEnc < (IsVector ? 32U : 16U) && "Register out of range");
1426     unsigned Bit = (1u << RegEnc);
1427     if ((Mask & Bit) == 0) {
1428       Mask |= Bit;
1429       ++Count;
1430     }
1431     --Idx;
1432   }
1433 
1434   Mask_ = Mask;
1435   return {Idx, Count};
1436 }
1437 
1438 void ARMELFStreamer::emitRegSave(const SmallVectorImpl<MCRegister> &RegList,
1439                                  bool IsVector) {
1440   uint32_t Mask;
1441   unsigned Idx, Count;
1442   const MCRegisterInfo &MRI = *getContext().getRegisterInfo();
1443 
1444   // Collect the registers in the register list. Issue unwinding instructions in
1445   // three parts: ordinary hardware registers, return address authentication
1446   // code pseudo register, the rest of the registers. The RA PAC is kept in an
1447   // architectural register (usually r12), but we treat it as a special case in
1448   // order to distinguish between that register containing RA PAC or a general
1449   // value.
1450   Idx = RegList.size();
1451   while (Idx > 0) {
1452     std::tie(Idx, Count) = collectHWRegs(MRI, Idx, RegList, IsVector, Mask);
1453     if (Count) {
1454       // Track the change the $sp offset: For the .save directive, the
1455       // corresponding push instruction will decrease the $sp by (4 * Count).
1456       // For the .vsave directive, the corresponding vpush instruction will
1457       // decrease $sp by (8 * Count).
1458       SPOffset -= Count * (IsVector ? 8 : 4);
1459 
1460       // Emit the opcode
1461       FlushPendingOffset();
1462       if (IsVector)
1463         UnwindOpAsm.EmitVFPRegSave(Mask);
1464       else
1465         UnwindOpAsm.EmitRegSave(Mask);
1466     } else if (Idx > 0 && RegList[Idx - 1] == ARM::RA_AUTH_CODE) {
1467       --Idx;
1468       SPOffset -= 4;
1469       FlushPendingOffset();
1470       UnwindOpAsm.EmitRegSave(0);
1471     }
1472   }
1473 }
1474 
1475 void ARMELFStreamer::emitUnwindRaw(int64_t Offset,
1476                                    const SmallVectorImpl<uint8_t> &Opcodes) {
1477   FlushPendingOffset();
1478   SPOffset = SPOffset - Offset;
1479   UnwindOpAsm.EmitRaw(Opcodes);
1480 }
1481 
1482 namespace llvm {
1483 
1484 MCTargetStreamer *createARMTargetAsmStreamer(MCStreamer &S,
1485                                              formatted_raw_ostream &OS,
1486                                              MCInstPrinter *InstPrint) {
1487   return new ARMTargetAsmStreamer(S, OS, *InstPrint);
1488 }
1489 
1490 MCTargetStreamer *createARMNullTargetStreamer(MCStreamer &S) {
1491   return new ARMTargetStreamer(S);
1492 }
1493 
1494 MCTargetStreamer *createARMObjectTargetELFStreamer(MCStreamer &S) {
1495   return new ARMTargetELFStreamer(S);
1496 }
1497 
1498 MCELFStreamer *createARMELFStreamer(MCContext &Context,
1499                                     std::unique_ptr<MCAsmBackend> TAB,
1500                                     std::unique_ptr<MCObjectWriter> OW,
1501                                     std::unique_ptr<MCCodeEmitter> Emitter,
1502                                     bool IsThumb, bool IsAndroid) {
1503   ARMELFStreamer *S =
1504       new ARMELFStreamer(Context, std::move(TAB), std::move(OW),
1505                          std::move(Emitter), IsThumb, IsAndroid);
1506   // FIXME: This should eventually end up somewhere else where more
1507   // intelligent flag decisions can be made. For now we are just maintaining
1508   // the status quo for ARM and setting EF_ARM_EABI_VER5 as the default.
1509   S->getWriter().setELFHeaderEFlags(ELF::EF_ARM_EABI_VER5);
1510 
1511   return S;
1512 }
1513 
1514 } // end namespace llvm
1515