1 //===- lib/MC/ARMELFStreamer.cpp - ELF Object Output for ARM --------------===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file assembles .s files and emits ARM ELF .o object files. Different
11 // from generic ELF streamer in emitting mapping symbols ($a, $t and $d) to
12 // delimit regions of data and code.
13 //
14 //===----------------------------------------------------------------------===//
15 
16 #include "ARMRegisterInfo.h"
17 #include "ARMUnwindOpAsm.h"
18 #include "llvm/ADT/DenseMap.h"
19 #include "llvm/ADT/SmallString.h"
20 #include "llvm/ADT/SmallVector.h"
21 #include "llvm/ADT/StringRef.h"
22 #include "llvm/ADT/Triple.h"
23 #include "llvm/ADT/Twine.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/MCRegisterInfo.h"
36 #include "llvm/MC/MCSection.h"
37 #include "llvm/MC/MCSectionELF.h"
38 #include "llvm/MC/MCStreamer.h"
39 #include "llvm/MC/MCSubtargetInfo.h"
40 #include "llvm/MC/MCSymbol.h"
41 #include "llvm/MC/MCSymbolELF.h"
42 #include "llvm/MC/SectionKind.h"
43 #include "llvm/Support/ARMBuildAttributes.h"
44 #include "llvm/Support/ARMEHABI.h"
45 #include "llvm/Support/Casting.h"
46 #include "llvm/Support/ELF.h"
47 #include "llvm/Support/ErrorHandling.h"
48 #include "llvm/Support/FormattedStream.h"
49 #include "llvm/Support/LEB128.h"
50 #include "llvm/Support/raw_ostream.h"
51 #include "llvm/Support/TargetParser.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(unsigned Arch) override;
96   void emitArchExtension(unsigned ArchExt) override;
97   void emitObjectArch(unsigned 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(unsigned Arch) {
222   OS << "\t.arch\t" << ARM::getArchName(Arch) << "\n";
223 }
224 
225 void ARMTargetAsmStreamer::emitArchExtension(unsigned ArchExt) {
226   OS << "\t.arch_extension\t" << ARM::getArchExtName(ArchExt) << "\n";
227 }
228 
229 void ARMTargetAsmStreamer::emitObjectArch(unsigned Arch) {
230   OS << "\t.object_arch\t" << ARM::getArchName(Arch) << '\n';
231 }
232 
233 void ARMTargetAsmStreamer::emitFPU(unsigned FPU) {
234   OS << "\t.fpu\t" << ARM::getFPUName(FPU) << "\n";
235 }
236 
237 void ARMTargetAsmStreamer::finishAttributeSection() {}
238 
239 void
240 ARMTargetAsmStreamer::AnnotateTLSDescriptorSequence(const MCSymbolRefExpr *S) {
241   OS << "\t.tlsdescseq\t" << S->getSymbol().getName();
242 }
243 
244 void ARMTargetAsmStreamer::emitThumbSet(MCSymbol *Symbol, const MCExpr *Value) {
245   const MCAsmInfo *MAI = Streamer.getContext().getAsmInfo();
246 
247   OS << "\t.thumb_set\t";
248   Symbol->print(OS, MAI);
249   OS << ", ";
250   Value->print(OS, MAI);
251   OS << '\n';
252 }
253 
254 void ARMTargetAsmStreamer::emitInst(uint32_t Inst, char Suffix) {
255   OS << "\t.inst";
256   if (Suffix)
257     OS << "." << Suffix;
258   OS << "\t0x" << Twine::utohexstr(Inst) << "\n";
259 }
260 
261 void ARMTargetAsmStreamer::emitUnwindRaw(int64_t Offset,
262                                       const SmallVectorImpl<uint8_t> &Opcodes) {
263   OS << "\t.unwind_raw " << Offset;
264   for (SmallVectorImpl<uint8_t>::const_iterator OCI = Opcodes.begin(),
265                                                 OCE = Opcodes.end();
266        OCI != OCE; ++OCI)
267     OS << ", 0x" << Twine::utohexstr(*OCI);
268   OS << '\n';
269 }
270 
271 class ARMTargetELFStreamer : public ARMTargetStreamer {
272 private:
273   // This structure holds all attributes, accounting for
274   // their string/numeric value, so we can later emit them
275   // in declaration order, keeping all in the same vector
276   struct AttributeItem {
277     enum {
278       HiddenAttribute = 0,
279       NumericAttribute,
280       TextAttribute,
281       NumericAndTextAttributes
282     } Type;
283     unsigned Tag;
284     unsigned IntValue;
285     std::string StringValue;
286 
287     static bool LessTag(const AttributeItem &LHS, const AttributeItem &RHS) {
288       // The conformance tag must be emitted first when serialised
289       // into an object file. Specifically, the addenda to the ARM ABI
290       // states that (2.3.7.4):
291       //
292       // "To simplify recognition by consumers in the common case of
293       // claiming conformity for the whole file, this tag should be
294       // emitted first in a file-scope sub-subsection of the first
295       // public subsection of the attributes section."
296       //
297       // So it is special-cased in this comparison predicate when the
298       // attributes are sorted in finishAttributeSection().
299       return (RHS.Tag != ARMBuildAttrs::conformance) &&
300              ((LHS.Tag == ARMBuildAttrs::conformance) || (LHS.Tag < RHS.Tag));
301     }
302   };
303 
304   StringRef CurrentVendor;
305   unsigned FPU = ARM::FK_INVALID;
306   unsigned Arch = ARM::AK_INVALID;
307   unsigned EmittedArch = ARM::AK_INVALID;
308   SmallVector<AttributeItem, 64> Contents;
309 
310   MCSection *AttributeSection = nullptr;
311 
312   AttributeItem *getAttributeItem(unsigned Attribute) {
313     for (size_t i = 0; i < Contents.size(); ++i)
314       if (Contents[i].Tag == Attribute)
315         return &Contents[i];
316     return nullptr;
317   }
318 
319   void setAttributeItem(unsigned Attribute, unsigned Value,
320                         bool OverwriteExisting) {
321     // Look for existing attribute item
322     if (AttributeItem *Item = getAttributeItem(Attribute)) {
323       if (!OverwriteExisting)
324         return;
325       Item->Type = AttributeItem::NumericAttribute;
326       Item->IntValue = Value;
327       return;
328     }
329 
330     // Create new attribute item
331     AttributeItem Item = {
332       AttributeItem::NumericAttribute,
333       Attribute,
334       Value,
335       StringRef("")
336     };
337     Contents.push_back(Item);
338   }
339 
340   void setAttributeItem(unsigned Attribute, StringRef Value,
341                         bool OverwriteExisting) {
342     // Look for existing attribute item
343     if (AttributeItem *Item = getAttributeItem(Attribute)) {
344       if (!OverwriteExisting)
345         return;
346       Item->Type = AttributeItem::TextAttribute;
347       Item->StringValue = Value;
348       return;
349     }
350 
351     // Create new attribute item
352     AttributeItem Item = {
353       AttributeItem::TextAttribute,
354       Attribute,
355       0,
356       Value
357     };
358     Contents.push_back(Item);
359   }
360 
361   void setAttributeItems(unsigned Attribute, unsigned IntValue,
362                          StringRef StringValue, bool OverwriteExisting) {
363     // Look for existing attribute item
364     if (AttributeItem *Item = getAttributeItem(Attribute)) {
365       if (!OverwriteExisting)
366         return;
367       Item->Type = AttributeItem::NumericAndTextAttributes;
368       Item->IntValue = IntValue;
369       Item->StringValue = StringValue;
370       return;
371     }
372 
373     // Create new attribute item
374     AttributeItem Item = {
375       AttributeItem::NumericAndTextAttributes,
376       Attribute,
377       IntValue,
378       StringValue
379     };
380     Contents.push_back(Item);
381   }
382 
383   void emitArchDefaultAttributes();
384   void emitFPUDefaultAttributes();
385 
386   ARMELFStreamer &getStreamer();
387 
388   void emitFnStart() override;
389   void emitFnEnd() override;
390   void emitCantUnwind() override;
391   void emitPersonality(const MCSymbol *Personality) override;
392   void emitPersonalityIndex(unsigned Index) override;
393   void emitHandlerData() override;
394   void emitSetFP(unsigned FpReg, unsigned SpReg, int64_t Offset = 0) override;
395   void emitMovSP(unsigned Reg, int64_t Offset = 0) override;
396   void emitPad(int64_t Offset) override;
397   void emitRegSave(const SmallVectorImpl<unsigned> &RegList,
398                    bool isVector) override;
399   void emitUnwindRaw(int64_t Offset,
400                      const SmallVectorImpl<uint8_t> &Opcodes) override;
401 
402   void switchVendor(StringRef Vendor) override;
403   void emitAttribute(unsigned Attribute, unsigned Value) override;
404   void emitTextAttribute(unsigned Attribute, StringRef String) override;
405   void emitIntTextAttribute(unsigned Attribute, unsigned IntValue,
406                             StringRef StringValue) override;
407   void emitArch(unsigned Arch) override;
408   void emitObjectArch(unsigned Arch) override;
409   void emitFPU(unsigned FPU) override;
410   void emitInst(uint32_t Inst, char Suffix = '\0') override;
411   void finishAttributeSection() override;
412   void emitLabel(MCSymbol *Symbol) override;
413 
414   void AnnotateTLSDescriptorSequence(const MCSymbolRefExpr *SRE) override;
415   void emitThumbSet(MCSymbol *Symbol, const MCExpr *Value) override;
416 
417   size_t calculateContentSize() const;
418 
419   // Reset state between object emissions
420   void reset() override;
421 
422 public:
423   ARMTargetELFStreamer(MCStreamer &S)
424     : ARMTargetStreamer(S), CurrentVendor("aeabi") {}
425 };
426 
427 /// Extend the generic ELFStreamer class so that it can emit mapping symbols at
428 /// the appropriate points in the object files. These symbols are defined in the
429 /// ARM ELF ABI: infocenter.arm.com/help/topic/com.arm.../IHI0044D_aaelf.pdf.
430 ///
431 /// In brief: $a, $t or $d should be emitted at the start of each contiguous
432 /// region of ARM code, Thumb code or data in a section. In practice, this
433 /// emission does not rely on explicit assembler directives but on inherent
434 /// properties of the directives doing the emission (e.g. ".byte" is data, "add
435 /// r0, r0, r0" an instruction).
436 ///
437 /// As a result this system is orthogonal to the DataRegion infrastructure used
438 /// by MachO. Beware!
439 class ARMELFStreamer : public MCELFStreamer {
440 public:
441   friend class ARMTargetELFStreamer;
442 
443   ARMELFStreamer(MCContext &Context, MCAsmBackend &TAB, raw_pwrite_stream &OS,
444                  MCCodeEmitter *Emitter, bool IsThumb)
445       : MCELFStreamer(Context, TAB, OS, Emitter), IsThumb(IsThumb) {
446     EHReset();
447   }
448 
449   ~ARMELFStreamer() override = default;
450 
451   void FinishImpl() override;
452 
453   // ARM exception handling directives
454   void emitFnStart();
455   void emitFnEnd();
456   void emitCantUnwind();
457   void emitPersonality(const MCSymbol *Per);
458   void emitPersonalityIndex(unsigned index);
459   void emitHandlerData();
460   void emitSetFP(unsigned NewFpReg, unsigned NewSpReg, int64_t Offset = 0);
461   void emitMovSP(unsigned Reg, int64_t Offset = 0);
462   void emitPad(int64_t Offset);
463   void emitRegSave(const SmallVectorImpl<unsigned> &RegList, bool isVector);
464   void emitUnwindRaw(int64_t Offset, const SmallVectorImpl<uint8_t> &Opcodes);
465 
466   void ChangeSection(MCSection *Section, const MCExpr *Subsection) override {
467     // We have to keep track of the mapping symbol state of any sections we
468     // use. Each one should start off as EMS_None, which is provided as the
469     // default constructor by DenseMap::lookup.
470     LastMappingSymbols[getPreviousSection().first] = LastEMS;
471     LastEMS = LastMappingSymbols.lookup(Section);
472 
473     MCELFStreamer::ChangeSection(Section, Subsection);
474   }
475 
476   /// This function is the one used to emit instruction data into the ELF
477   /// streamer. We override it to add the appropriate mapping symbol if
478   /// necessary.
479   void EmitInstruction(const MCInst& Inst,
480                        const MCSubtargetInfo &STI) override {
481     if (IsThumb)
482       EmitThumbMappingSymbol();
483     else
484       EmitARMMappingSymbol();
485 
486     MCELFStreamer::EmitInstruction(Inst, STI);
487   }
488 
489   void emitInst(uint32_t Inst, char Suffix) {
490     unsigned Size;
491     char Buffer[4];
492     const bool LittleEndian = getContext().getAsmInfo()->isLittleEndian();
493 
494     switch (Suffix) {
495     case '\0':
496       Size = 4;
497 
498       assert(!IsThumb);
499       EmitARMMappingSymbol();
500       for (unsigned II = 0, IE = Size; II != IE; II++) {
501         const unsigned I = LittleEndian ? (Size - II - 1) : II;
502         Buffer[Size - II - 1] = uint8_t(Inst >> I * CHAR_BIT);
503       }
504 
505       break;
506     case 'n':
507     case 'w':
508       Size = (Suffix == 'n' ? 2 : 4);
509 
510       assert(IsThumb);
511       EmitThumbMappingSymbol();
512       for (unsigned II = 0, IE = Size; II != IE; II = II + 2) {
513         const unsigned I0 = LittleEndian ? II + 0 : (Size - II - 1);
514         const unsigned I1 = LittleEndian ? II + 1 : (Size - II - 2);
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   /// This is one of the functions used to emit data into an ELF section, so the
536   /// ARM streamer overrides it to add the appropriate mapping symbol ($d) if
537   /// necessary.
538   void EmitValueImpl(const MCExpr *Value, unsigned Size, SMLoc Loc) override {
539     if (const MCSymbolRefExpr *SRE = dyn_cast_or_null<MCSymbolRefExpr>(Value))
540       if (SRE->getKind() == MCSymbolRefExpr::VK_ARM_SBREL && !(Size == 4)) {
541         getContext().reportError(Loc, "relocated expression must be 32-bit");
542         return;
543       }
544 
545     EmitDataMappingSymbol();
546     MCELFStreamer::EmitValueImpl(Value, Size, Loc);
547   }
548 
549   void EmitAssemblerFlag(MCAssemblerFlag Flag) override {
550     MCELFStreamer::EmitAssemblerFlag(Flag);
551 
552     switch (Flag) {
553     case MCAF_SyntaxUnified:
554       return; // no-op here.
555     case MCAF_Code16:
556       IsThumb = true;
557       return; // Change to Thumb mode
558     case MCAF_Code32:
559       IsThumb = false;
560       return; // Change to ARM mode
561     case MCAF_Code64:
562       return;
563     case MCAF_SubsectionsViaSymbols:
564       return;
565     }
566   }
567 
568 private:
569   enum ElfMappingSymbol {
570     EMS_None,
571     EMS_ARM,
572     EMS_Thumb,
573     EMS_Data
574   };
575 
576   void EmitDataMappingSymbol() {
577     if (LastEMS == EMS_Data) return;
578     EmitMappingSymbol("$d");
579     LastEMS = EMS_Data;
580   }
581 
582   void EmitThumbMappingSymbol() {
583     if (LastEMS == EMS_Thumb) return;
584     EmitMappingSymbol("$t");
585     LastEMS = EMS_Thumb;
586   }
587 
588   void EmitARMMappingSymbol() {
589     if (LastEMS == EMS_ARM) return;
590     EmitMappingSymbol("$a");
591     LastEMS = EMS_ARM;
592   }
593 
594   void EmitMappingSymbol(StringRef Name) {
595     auto *Symbol = cast<MCSymbolELF>(getContext().getOrCreateSymbol(
596         Name + "." + Twine(MappingSymbolCounter++)));
597     EmitLabel(Symbol);
598 
599     Symbol->setType(ELF::STT_NOTYPE);
600     Symbol->setBinding(ELF::STB_LOCAL);
601     Symbol->setExternal(false);
602   }
603 
604   void EmitThumbFunc(MCSymbol *Func) override {
605     getAssembler().setIsThumbFunc(Func);
606     EmitSymbolAttribute(Func, MCSA_ELF_TypeFunction);
607   }
608 
609   // Helper functions for ARM exception handling directives
610   void EHReset();
611 
612   // Reset state between object emissions
613   void reset() override;
614 
615   void EmitPersonalityFixup(StringRef Name);
616   void FlushPendingOffset();
617   void FlushUnwindOpcodes(bool NoHandlerData);
618 
619   void SwitchToEHSection(StringRef Prefix, unsigned Type, unsigned Flags,
620                          SectionKind Kind, const MCSymbol &Fn);
621   void SwitchToExTabSection(const MCSymbol &FnStart);
622   void SwitchToExIdxSection(const MCSymbol &FnStart);
623 
624   void EmitFixup(const MCExpr *Expr, MCFixupKind Kind);
625 
626   bool IsThumb;
627   int64_t MappingSymbolCounter = 0;
628 
629   DenseMap<const MCSection *, ElfMappingSymbol> LastMappingSymbols;
630   ElfMappingSymbol LastEMS = EMS_None;
631 
632   // ARM Exception Handling Frame Information
633   MCSymbol *ExTab;
634   MCSymbol *FnStart;
635   const MCSymbol *Personality;
636   unsigned PersonalityIndex;
637   unsigned FPReg; // Frame pointer register
638   int64_t FPOffset; // Offset: (final frame pointer) - (initial $sp)
639   int64_t SPOffset; // Offset: (final $sp) - (initial $sp)
640   int64_t PendingOffset; // Offset: (final $sp) - (emitted $sp)
641   bool UsedFP;
642   bool CantUnwind;
643   SmallVector<uint8_t, 64> Opcodes;
644   UnwindOpcodeAssembler UnwindOpAsm;
645 };
646 
647 } // end anonymous namespace
648 
649 ARMELFStreamer &ARMTargetELFStreamer::getStreamer() {
650   return static_cast<ARMELFStreamer &>(Streamer);
651 }
652 
653 void ARMTargetELFStreamer::emitFnStart() { getStreamer().emitFnStart(); }
654 void ARMTargetELFStreamer::emitFnEnd() { getStreamer().emitFnEnd(); }
655 void ARMTargetELFStreamer::emitCantUnwind() { getStreamer().emitCantUnwind(); }
656 
657 void ARMTargetELFStreamer::emitPersonality(const MCSymbol *Personality) {
658   getStreamer().emitPersonality(Personality);
659 }
660 
661 void ARMTargetELFStreamer::emitPersonalityIndex(unsigned Index) {
662   getStreamer().emitPersonalityIndex(Index);
663 }
664 
665 void ARMTargetELFStreamer::emitHandlerData() {
666   getStreamer().emitHandlerData();
667 }
668 
669 void ARMTargetELFStreamer::emitSetFP(unsigned FpReg, unsigned SpReg,
670                                      int64_t Offset) {
671   getStreamer().emitSetFP(FpReg, SpReg, Offset);
672 }
673 
674 void ARMTargetELFStreamer::emitMovSP(unsigned Reg, int64_t Offset) {
675   getStreamer().emitMovSP(Reg, Offset);
676 }
677 
678 void ARMTargetELFStreamer::emitPad(int64_t Offset) {
679   getStreamer().emitPad(Offset);
680 }
681 
682 void ARMTargetELFStreamer::emitRegSave(const SmallVectorImpl<unsigned> &RegList,
683                                        bool isVector) {
684   getStreamer().emitRegSave(RegList, isVector);
685 }
686 
687 void ARMTargetELFStreamer::emitUnwindRaw(int64_t Offset,
688                                       const SmallVectorImpl<uint8_t> &Opcodes) {
689   getStreamer().emitUnwindRaw(Offset, Opcodes);
690 }
691 
692 void ARMTargetELFStreamer::switchVendor(StringRef Vendor) {
693   assert(!Vendor.empty() && "Vendor cannot be empty.");
694 
695   if (CurrentVendor == Vendor)
696     return;
697 
698   if (!CurrentVendor.empty())
699     finishAttributeSection();
700 
701   assert(Contents.empty() &&
702          ".ARM.attributes should be flushed before changing vendor");
703   CurrentVendor = Vendor;
704 
705 }
706 
707 void ARMTargetELFStreamer::emitAttribute(unsigned Attribute, unsigned Value) {
708   setAttributeItem(Attribute, Value, /* OverwriteExisting= */ true);
709 }
710 
711 void ARMTargetELFStreamer::emitTextAttribute(unsigned Attribute,
712                                              StringRef Value) {
713   setAttributeItem(Attribute, Value, /* OverwriteExisting= */ true);
714 }
715 
716 void ARMTargetELFStreamer::emitIntTextAttribute(unsigned Attribute,
717                                                 unsigned IntValue,
718                                                 StringRef StringValue) {
719   setAttributeItems(Attribute, IntValue, StringValue,
720                     /* OverwriteExisting= */ true);
721 }
722 
723 void ARMTargetELFStreamer::emitArch(unsigned Value) {
724   Arch = Value;
725 }
726 
727 void ARMTargetELFStreamer::emitObjectArch(unsigned Value) {
728   EmittedArch = Value;
729 }
730 
731 void ARMTargetELFStreamer::emitArchDefaultAttributes() {
732   using namespace ARMBuildAttrs;
733 
734   setAttributeItem(CPU_name,
735                    ARM::getCPUAttr(Arch),
736                    false);
737 
738   if (EmittedArch == ARM::AK_INVALID)
739     setAttributeItem(CPU_arch,
740                      ARM::getArchAttr(Arch),
741                      false);
742   else
743     setAttributeItem(CPU_arch,
744                      ARM::getArchAttr(EmittedArch),
745                      false);
746 
747   switch (Arch) {
748   case ARM::AK_ARMV2:
749   case ARM::AK_ARMV2A:
750   case ARM::AK_ARMV3:
751   case ARM::AK_ARMV3M:
752   case ARM::AK_ARMV4:
753     setAttributeItem(ARM_ISA_use, Allowed, false);
754     break;
755 
756   case ARM::AK_ARMV4T:
757   case ARM::AK_ARMV5T:
758   case ARM::AK_ARMV5TE:
759   case ARM::AK_ARMV6:
760     setAttributeItem(ARM_ISA_use, Allowed, false);
761     setAttributeItem(THUMB_ISA_use, Allowed, false);
762     break;
763 
764   case ARM::AK_ARMV6T2:
765     setAttributeItem(ARM_ISA_use, Allowed, false);
766     setAttributeItem(THUMB_ISA_use, AllowThumb32, false);
767     break;
768 
769   case ARM::AK_ARMV6K:
770   case ARM::AK_ARMV6KZ:
771     setAttributeItem(ARM_ISA_use, Allowed, false);
772     setAttributeItem(THUMB_ISA_use, Allowed, false);
773     setAttributeItem(Virtualization_use, AllowTZ, false);
774     break;
775 
776   case ARM::AK_ARMV6M:
777     setAttributeItem(THUMB_ISA_use, Allowed, false);
778     break;
779 
780   case ARM::AK_ARMV7A:
781     setAttributeItem(CPU_arch_profile, ApplicationProfile, false);
782     setAttributeItem(ARM_ISA_use, Allowed, false);
783     setAttributeItem(THUMB_ISA_use, AllowThumb32, false);
784     break;
785 
786   case ARM::AK_ARMV7R:
787     setAttributeItem(CPU_arch_profile, RealTimeProfile, false);
788     setAttributeItem(ARM_ISA_use, Allowed, false);
789     setAttributeItem(THUMB_ISA_use, AllowThumb32, false);
790     break;
791 
792   case ARM::AK_ARMV7M:
793     setAttributeItem(CPU_arch_profile, MicroControllerProfile, false);
794     setAttributeItem(THUMB_ISA_use, AllowThumb32, false);
795     break;
796 
797   case ARM::AK_ARMV8A:
798   case ARM::AK_ARMV8_1A:
799   case ARM::AK_ARMV8_2A:
800     setAttributeItem(CPU_arch_profile, ApplicationProfile, false);
801     setAttributeItem(ARM_ISA_use, Allowed, false);
802     setAttributeItem(THUMB_ISA_use, AllowThumb32, false);
803     setAttributeItem(MPextension_use, Allowed, false);
804     setAttributeItem(Virtualization_use, AllowTZVirtualization, false);
805     break;
806 
807   case ARM::AK_ARMV8MBaseline:
808   case ARM::AK_ARMV8MMainline:
809     setAttributeItem(THUMB_ISA_use, AllowThumbDerived, false);
810     setAttributeItem(CPU_arch_profile, MicroControllerProfile, false);
811     break;
812 
813   case ARM::AK_IWMMXT:
814     setAttributeItem(ARM_ISA_use, Allowed, false);
815     setAttributeItem(THUMB_ISA_use, Allowed, false);
816     setAttributeItem(WMMX_arch, AllowWMMXv1, false);
817     break;
818 
819   case ARM::AK_IWMMXT2:
820     setAttributeItem(ARM_ISA_use, Allowed, false);
821     setAttributeItem(THUMB_ISA_use, Allowed, false);
822     setAttributeItem(WMMX_arch, AllowWMMXv2, false);
823     break;
824 
825   default:
826     report_fatal_error("Unknown Arch: " + Twine(Arch));
827     break;
828   }
829 }
830 
831 void ARMTargetELFStreamer::emitFPU(unsigned Value) {
832   FPU = Value;
833 }
834 
835 void ARMTargetELFStreamer::emitFPUDefaultAttributes() {
836   switch (FPU) {
837   case ARM::FK_VFP:
838   case ARM::FK_VFPV2:
839     setAttributeItem(ARMBuildAttrs::FP_arch,
840                      ARMBuildAttrs::AllowFPv2,
841                      /* OverwriteExisting= */ false);
842     break;
843 
844   case ARM::FK_VFPV3:
845     setAttributeItem(ARMBuildAttrs::FP_arch,
846                      ARMBuildAttrs::AllowFPv3A,
847                      /* OverwriteExisting= */ false);
848     break;
849 
850   case ARM::FK_VFPV3_FP16:
851     setAttributeItem(ARMBuildAttrs::FP_arch,
852                      ARMBuildAttrs::AllowFPv3A,
853                      /* OverwriteExisting= */ false);
854     setAttributeItem(ARMBuildAttrs::FP_HP_extension,
855                      ARMBuildAttrs::AllowHPFP,
856                      /* OverwriteExisting= */ false);
857     break;
858 
859   case ARM::FK_VFPV3_D16:
860     setAttributeItem(ARMBuildAttrs::FP_arch,
861                      ARMBuildAttrs::AllowFPv3B,
862                      /* OverwriteExisting= */ false);
863     break;
864 
865   case ARM::FK_VFPV3_D16_FP16:
866     setAttributeItem(ARMBuildAttrs::FP_arch,
867                      ARMBuildAttrs::AllowFPv3B,
868                      /* OverwriteExisting= */ false);
869     setAttributeItem(ARMBuildAttrs::FP_HP_extension,
870                      ARMBuildAttrs::AllowHPFP,
871                      /* OverwriteExisting= */ false);
872     break;
873 
874   case ARM::FK_VFPV3XD:
875     setAttributeItem(ARMBuildAttrs::FP_arch,
876                      ARMBuildAttrs::AllowFPv3B,
877                      /* OverwriteExisting= */ false);
878     break;
879   case ARM::FK_VFPV3XD_FP16:
880     setAttributeItem(ARMBuildAttrs::FP_arch,
881                      ARMBuildAttrs::AllowFPv3B,
882                      /* OverwriteExisting= */ false);
883     setAttributeItem(ARMBuildAttrs::FP_HP_extension,
884                      ARMBuildAttrs::AllowHPFP,
885                      /* OverwriteExisting= */ false);
886     break;
887 
888   case ARM::FK_VFPV4:
889     setAttributeItem(ARMBuildAttrs::FP_arch,
890                      ARMBuildAttrs::AllowFPv4A,
891                      /* OverwriteExisting= */ false);
892     break;
893 
894   // ABI_HardFP_use is handled in ARMAsmPrinter, so _SP_D16 is treated the same
895   // as _D16 here.
896   case ARM::FK_FPV4_SP_D16:
897   case ARM::FK_VFPV4_D16:
898     setAttributeItem(ARMBuildAttrs::FP_arch,
899                      ARMBuildAttrs::AllowFPv4B,
900                      /* OverwriteExisting= */ false);
901     break;
902 
903   case ARM::FK_FP_ARMV8:
904     setAttributeItem(ARMBuildAttrs::FP_arch,
905                      ARMBuildAttrs::AllowFPARMv8A,
906                      /* OverwriteExisting= */ false);
907     break;
908 
909   // FPV5_D16 is identical to FP_ARMV8 except for the number of D registers, so
910   // uses the FP_ARMV8_D16 build attribute.
911   case ARM::FK_FPV5_SP_D16:
912   case ARM::FK_FPV5_D16:
913     setAttributeItem(ARMBuildAttrs::FP_arch,
914                      ARMBuildAttrs::AllowFPARMv8B,
915                      /* OverwriteExisting= */ false);
916     break;
917 
918   case ARM::FK_NEON:
919     setAttributeItem(ARMBuildAttrs::FP_arch,
920                      ARMBuildAttrs::AllowFPv3A,
921                      /* OverwriteExisting= */ false);
922     setAttributeItem(ARMBuildAttrs::Advanced_SIMD_arch,
923                      ARMBuildAttrs::AllowNeon,
924                      /* OverwriteExisting= */ false);
925     break;
926 
927   case ARM::FK_NEON_FP16:
928     setAttributeItem(ARMBuildAttrs::FP_arch,
929                      ARMBuildAttrs::AllowFPv3A,
930                      /* OverwriteExisting= */ false);
931     setAttributeItem(ARMBuildAttrs::Advanced_SIMD_arch,
932                      ARMBuildAttrs::AllowNeon,
933                      /* OverwriteExisting= */ false);
934     setAttributeItem(ARMBuildAttrs::FP_HP_extension,
935                      ARMBuildAttrs::AllowHPFP,
936                      /* OverwriteExisting= */ false);
937     break;
938 
939   case ARM::FK_NEON_VFPV4:
940     setAttributeItem(ARMBuildAttrs::FP_arch,
941                      ARMBuildAttrs::AllowFPv4A,
942                      /* OverwriteExisting= */ false);
943     setAttributeItem(ARMBuildAttrs::Advanced_SIMD_arch,
944                      ARMBuildAttrs::AllowNeon2,
945                      /* OverwriteExisting= */ false);
946     break;
947 
948   case ARM::FK_NEON_FP_ARMV8:
949   case ARM::FK_CRYPTO_NEON_FP_ARMV8:
950     setAttributeItem(ARMBuildAttrs::FP_arch,
951                      ARMBuildAttrs::AllowFPARMv8A,
952                      /* OverwriteExisting= */ false);
953     // 'Advanced_SIMD_arch' must be emitted not here, but within
954     // ARMAsmPrinter::emitAttributes(), depending on hasV8Ops() and hasV8_1a()
955     break;
956 
957   case ARM::FK_SOFTVFP:
958   case ARM::FK_NONE:
959     break;
960 
961   default:
962     report_fatal_error("Unknown FPU: " + Twine(FPU));
963     break;
964   }
965 }
966 
967 size_t ARMTargetELFStreamer::calculateContentSize() const {
968   size_t Result = 0;
969   for (size_t i = 0; i < Contents.size(); ++i) {
970     AttributeItem item = Contents[i];
971     switch (item.Type) {
972     case AttributeItem::HiddenAttribute:
973       break;
974     case AttributeItem::NumericAttribute:
975       Result += getULEB128Size(item.Tag);
976       Result += getULEB128Size(item.IntValue);
977       break;
978     case AttributeItem::TextAttribute:
979       Result += getULEB128Size(item.Tag);
980       Result += item.StringValue.size() + 1; // string + '\0'
981       break;
982     case AttributeItem::NumericAndTextAttributes:
983       Result += getULEB128Size(item.Tag);
984       Result += getULEB128Size(item.IntValue);
985       Result += item.StringValue.size() + 1; // string + '\0';
986       break;
987     }
988   }
989   return Result;
990 }
991 
992 void ARMTargetELFStreamer::finishAttributeSection() {
993   // <format-version>
994   // [ <section-length> "vendor-name"
995   // [ <file-tag> <size> <attribute>*
996   //   | <section-tag> <size> <section-number>* 0 <attribute>*
997   //   | <symbol-tag> <size> <symbol-number>* 0 <attribute>*
998   //   ]+
999   // ]*
1000 
1001   if (FPU != ARM::FK_INVALID)
1002     emitFPUDefaultAttributes();
1003 
1004   if (Arch != ARM::AK_INVALID)
1005     emitArchDefaultAttributes();
1006 
1007   if (Contents.empty())
1008     return;
1009 
1010   std::sort(Contents.begin(), Contents.end(), AttributeItem::LessTag);
1011 
1012   ARMELFStreamer &Streamer = getStreamer();
1013 
1014   // Switch to .ARM.attributes section
1015   if (AttributeSection) {
1016     Streamer.SwitchSection(AttributeSection);
1017   } else {
1018     AttributeSection = Streamer.getContext().getELFSection(
1019         ".ARM.attributes", ELF::SHT_ARM_ATTRIBUTES, 0);
1020     Streamer.SwitchSection(AttributeSection);
1021 
1022     // Format version
1023     Streamer.EmitIntValue(0x41, 1);
1024   }
1025 
1026   // Vendor size + Vendor name + '\0'
1027   const size_t VendorHeaderSize = 4 + CurrentVendor.size() + 1;
1028 
1029   // Tag + Tag Size
1030   const size_t TagHeaderSize = 1 + 4;
1031 
1032   const size_t ContentsSize = calculateContentSize();
1033 
1034   Streamer.EmitIntValue(VendorHeaderSize + TagHeaderSize + ContentsSize, 4);
1035   Streamer.EmitBytes(CurrentVendor);
1036   Streamer.EmitIntValue(0, 1); // '\0'
1037 
1038   Streamer.EmitIntValue(ARMBuildAttrs::File, 1);
1039   Streamer.EmitIntValue(TagHeaderSize + ContentsSize, 4);
1040 
1041   // Size should have been accounted for already, now
1042   // emit each field as its type (ULEB or String)
1043   for (size_t i = 0; i < Contents.size(); ++i) {
1044     AttributeItem item = Contents[i];
1045     Streamer.EmitULEB128IntValue(item.Tag);
1046     switch (item.Type) {
1047     default: llvm_unreachable("Invalid attribute type");
1048     case AttributeItem::NumericAttribute:
1049       Streamer.EmitULEB128IntValue(item.IntValue);
1050       break;
1051     case AttributeItem::TextAttribute:
1052       Streamer.EmitBytes(item.StringValue);
1053       Streamer.EmitIntValue(0, 1); // '\0'
1054       break;
1055     case AttributeItem::NumericAndTextAttributes:
1056       Streamer.EmitULEB128IntValue(item.IntValue);
1057       Streamer.EmitBytes(item.StringValue);
1058       Streamer.EmitIntValue(0, 1); // '\0'
1059       break;
1060     }
1061   }
1062 
1063   Contents.clear();
1064   FPU = ARM::FK_INVALID;
1065 }
1066 
1067 void ARMTargetELFStreamer::emitLabel(MCSymbol *Symbol) {
1068   ARMELFStreamer &Streamer = getStreamer();
1069   if (!Streamer.IsThumb)
1070     return;
1071 
1072   Streamer.getAssembler().registerSymbol(*Symbol);
1073   unsigned Type = cast<MCSymbolELF>(Symbol)->getType();
1074   if (Type == ELF::STT_FUNC || Type == ELF::STT_GNU_IFUNC)
1075     Streamer.EmitThumbFunc(Symbol);
1076 }
1077 
1078 void
1079 ARMTargetELFStreamer::AnnotateTLSDescriptorSequence(const MCSymbolRefExpr *S) {
1080   getStreamer().EmitFixup(S, FK_Data_4);
1081 }
1082 
1083 void ARMTargetELFStreamer::emitThumbSet(MCSymbol *Symbol, const MCExpr *Value) {
1084   if (const MCSymbolRefExpr *SRE = dyn_cast<MCSymbolRefExpr>(Value)) {
1085     const MCSymbol &Sym = SRE->getSymbol();
1086     if (!Sym.isDefined()) {
1087       getStreamer().EmitAssignment(Symbol, Value);
1088       return;
1089     }
1090   }
1091 
1092   getStreamer().EmitThumbFunc(Symbol);
1093   getStreamer().EmitAssignment(Symbol, Value);
1094 }
1095 
1096 void ARMTargetELFStreamer::emitInst(uint32_t Inst, char Suffix) {
1097   getStreamer().emitInst(Inst, Suffix);
1098 }
1099 
1100 void ARMTargetELFStreamer::reset() { AttributeSection = nullptr; }
1101 
1102 void ARMELFStreamer::FinishImpl() {
1103   MCTargetStreamer &TS = *getTargetStreamer();
1104   ARMTargetStreamer &ATS = static_cast<ARMTargetStreamer &>(TS);
1105   ATS.finishAttributeSection();
1106 
1107   MCELFStreamer::FinishImpl();
1108 }
1109 
1110 void ARMELFStreamer::reset() {
1111   MCTargetStreamer &TS = *getTargetStreamer();
1112   ARMTargetStreamer &ATS = static_cast<ARMTargetStreamer &>(TS);
1113   ATS.reset();
1114   MappingSymbolCounter = 0;
1115   MCELFStreamer::reset();
1116   // MCELFStreamer clear's the assembler's e_flags. However, for
1117   // arm we manually set the ABI version on streamer creation, so
1118   // do the same here
1119   getAssembler().setELFHeaderEFlags(ELF::EF_ARM_EABI_VER5);
1120 }
1121 
1122 inline void ARMELFStreamer::SwitchToEHSection(StringRef Prefix,
1123                                               unsigned Type,
1124                                               unsigned Flags,
1125                                               SectionKind Kind,
1126                                               const MCSymbol &Fn) {
1127   const MCSectionELF &FnSection =
1128     static_cast<const MCSectionELF &>(Fn.getSection());
1129 
1130   // Create the name for new section
1131   StringRef FnSecName(FnSection.getSectionName());
1132   SmallString<128> EHSecName(Prefix);
1133   if (FnSecName != ".text") {
1134     EHSecName += FnSecName;
1135   }
1136 
1137   // Get .ARM.extab or .ARM.exidx section
1138   const MCSymbolELF *Group = FnSection.getGroup();
1139   if (Group)
1140     Flags |= ELF::SHF_GROUP;
1141   MCSectionELF *EHSection = getContext().getELFSection(
1142       EHSecName, Type, Flags, 0, Group, FnSection.getUniqueID(), &FnSection);
1143 
1144   assert(EHSection && "Failed to get the required EH section");
1145 
1146   // Switch to .ARM.extab or .ARM.exidx section
1147   SwitchSection(EHSection);
1148   EmitCodeAlignment(4);
1149 }
1150 
1151 inline void ARMELFStreamer::SwitchToExTabSection(const MCSymbol &FnStart) {
1152   SwitchToEHSection(".ARM.extab", ELF::SHT_PROGBITS, ELF::SHF_ALLOC,
1153                     SectionKind::getData(), FnStart);
1154 }
1155 
1156 inline void ARMELFStreamer::SwitchToExIdxSection(const MCSymbol &FnStart) {
1157   SwitchToEHSection(".ARM.exidx", ELF::SHT_ARM_EXIDX,
1158                     ELF::SHF_ALLOC | ELF::SHF_LINK_ORDER,
1159                     SectionKind::getData(), FnStart);
1160 }
1161 
1162 void ARMELFStreamer::EmitFixup(const MCExpr *Expr, MCFixupKind Kind) {
1163   MCDataFragment *Frag = getOrCreateDataFragment();
1164   Frag->getFixups().push_back(MCFixup::create(Frag->getContents().size(), Expr,
1165                                               Kind));
1166 }
1167 
1168 void ARMELFStreamer::EHReset() {
1169   ExTab = nullptr;
1170   FnStart = nullptr;
1171   Personality = nullptr;
1172   PersonalityIndex = ARM::EHABI::NUM_PERSONALITY_INDEX;
1173   FPReg = ARM::SP;
1174   FPOffset = 0;
1175   SPOffset = 0;
1176   PendingOffset = 0;
1177   UsedFP = false;
1178   CantUnwind = false;
1179 
1180   Opcodes.clear();
1181   UnwindOpAsm.Reset();
1182 }
1183 
1184 void ARMELFStreamer::emitFnStart() {
1185   assert(FnStart == nullptr);
1186   FnStart = getContext().createTempSymbol();
1187   EmitLabel(FnStart);
1188 }
1189 
1190 void ARMELFStreamer::emitFnEnd() {
1191   assert(FnStart && ".fnstart must precedes .fnend");
1192 
1193   // Emit unwind opcodes if there is no .handlerdata directive
1194   if (!ExTab && !CantUnwind)
1195     FlushUnwindOpcodes(true);
1196 
1197   // Emit the exception index table entry
1198   SwitchToExIdxSection(*FnStart);
1199 
1200   if (PersonalityIndex < ARM::EHABI::NUM_PERSONALITY_INDEX)
1201     EmitPersonalityFixup(GetAEABIUnwindPersonalityName(PersonalityIndex));
1202 
1203   const MCSymbolRefExpr *FnStartRef =
1204     MCSymbolRefExpr::create(FnStart,
1205                             MCSymbolRefExpr::VK_ARM_PREL31,
1206                             getContext());
1207 
1208   EmitValue(FnStartRef, 4);
1209 
1210   if (CantUnwind) {
1211     EmitIntValue(ARM::EHABI::EXIDX_CANTUNWIND, 4);
1212   } else if (ExTab) {
1213     // Emit a reference to the unwind opcodes in the ".ARM.extab" section.
1214     const MCSymbolRefExpr *ExTabEntryRef =
1215       MCSymbolRefExpr::create(ExTab,
1216                               MCSymbolRefExpr::VK_ARM_PREL31,
1217                               getContext());
1218     EmitValue(ExTabEntryRef, 4);
1219   } else {
1220     // For the __aeabi_unwind_cpp_pr0, we have to emit the unwind opcodes in
1221     // the second word of exception index table entry.  The size of the unwind
1222     // opcodes should always be 4 bytes.
1223     assert(PersonalityIndex == ARM::EHABI::AEABI_UNWIND_CPP_PR0 &&
1224            "Compact model must use __aeabi_unwind_cpp_pr0 as personality");
1225     assert(Opcodes.size() == 4u &&
1226            "Unwind opcode size for __aeabi_unwind_cpp_pr0 must be equal to 4");
1227     uint64_t Intval = Opcodes[0] |
1228                       Opcodes[1] << 8 |
1229                       Opcodes[2] << 16 |
1230                       Opcodes[3] << 24;
1231     EmitIntValue(Intval, Opcodes.size());
1232   }
1233 
1234   // Switch to the section containing FnStart
1235   SwitchSection(&FnStart->getSection());
1236 
1237   // Clean exception handling frame information
1238   EHReset();
1239 }
1240 
1241 void ARMELFStreamer::emitCantUnwind() { CantUnwind = true; }
1242 
1243 // Add the R_ARM_NONE fixup at the same position
1244 void ARMELFStreamer::EmitPersonalityFixup(StringRef Name) {
1245   const MCSymbol *PersonalitySym = getContext().getOrCreateSymbol(Name);
1246 
1247   const MCSymbolRefExpr *PersonalityRef = MCSymbolRefExpr::create(
1248       PersonalitySym, MCSymbolRefExpr::VK_ARM_NONE, getContext());
1249 
1250   visitUsedExpr(*PersonalityRef);
1251   MCDataFragment *DF = getOrCreateDataFragment();
1252   DF->getFixups().push_back(MCFixup::create(DF->getContents().size(),
1253                                             PersonalityRef,
1254                                             MCFixup::getKindForSize(4, false)));
1255 }
1256 
1257 void ARMELFStreamer::FlushPendingOffset() {
1258   if (PendingOffset != 0) {
1259     UnwindOpAsm.EmitSPOffset(-PendingOffset);
1260     PendingOffset = 0;
1261   }
1262 }
1263 
1264 void ARMELFStreamer::FlushUnwindOpcodes(bool NoHandlerData) {
1265   // Emit the unwind opcode to restore $sp.
1266   if (UsedFP) {
1267     const MCRegisterInfo *MRI = getContext().getRegisterInfo();
1268     int64_t LastRegSaveSPOffset = SPOffset - PendingOffset;
1269     UnwindOpAsm.EmitSPOffset(LastRegSaveSPOffset - FPOffset);
1270     UnwindOpAsm.EmitSetSP(MRI->getEncodingValue(FPReg));
1271   } else {
1272     FlushPendingOffset();
1273   }
1274 
1275   // Finalize the unwind opcode sequence
1276   UnwindOpAsm.Finalize(PersonalityIndex, Opcodes);
1277 
1278   // For compact model 0, we have to emit the unwind opcodes in the .ARM.exidx
1279   // section.  Thus, we don't have to create an entry in the .ARM.extab
1280   // section.
1281   if (NoHandlerData && PersonalityIndex == ARM::EHABI::AEABI_UNWIND_CPP_PR0)
1282     return;
1283 
1284   // Switch to .ARM.extab section.
1285   SwitchToExTabSection(*FnStart);
1286 
1287   // Create .ARM.extab label for offset in .ARM.exidx
1288   assert(!ExTab);
1289   ExTab = getContext().createTempSymbol();
1290   EmitLabel(ExTab);
1291 
1292   // Emit personality
1293   if (Personality) {
1294     const MCSymbolRefExpr *PersonalityRef =
1295       MCSymbolRefExpr::create(Personality,
1296                               MCSymbolRefExpr::VK_ARM_PREL31,
1297                               getContext());
1298 
1299     EmitValue(PersonalityRef, 4);
1300   }
1301 
1302   // Emit unwind opcodes
1303   assert((Opcodes.size() % 4) == 0 &&
1304          "Unwind opcode size for __aeabi_cpp_unwind_pr0 must be multiple of 4");
1305   for (unsigned I = 0; I != Opcodes.size(); I += 4) {
1306     uint64_t Intval = Opcodes[I] |
1307                       Opcodes[I + 1] << 8 |
1308                       Opcodes[I + 2] << 16 |
1309                       Opcodes[I + 3] << 24;
1310     EmitIntValue(Intval, 4);
1311   }
1312 
1313   // According to ARM EHABI section 9.2, if the __aeabi_unwind_cpp_pr1() or
1314   // __aeabi_unwind_cpp_pr2() is used, then the handler data must be emitted
1315   // after the unwind opcodes.  The handler data consists of several 32-bit
1316   // words, and should be terminated by zero.
1317   //
1318   // In case that the .handlerdata directive is not specified by the
1319   // programmer, we should emit zero to terminate the handler data.
1320   if (NoHandlerData && !Personality)
1321     EmitIntValue(0, 4);
1322 }
1323 
1324 void ARMELFStreamer::emitHandlerData() { FlushUnwindOpcodes(false); }
1325 
1326 void ARMELFStreamer::emitPersonality(const MCSymbol *Per) {
1327   Personality = Per;
1328   UnwindOpAsm.setPersonality(Per);
1329 }
1330 
1331 void ARMELFStreamer::emitPersonalityIndex(unsigned Index) {
1332   assert(Index < ARM::EHABI::NUM_PERSONALITY_INDEX && "invalid index");
1333   PersonalityIndex = Index;
1334 }
1335 
1336 void ARMELFStreamer::emitSetFP(unsigned NewFPReg, unsigned NewSPReg,
1337                                int64_t Offset) {
1338   assert((NewSPReg == ARM::SP || NewSPReg == FPReg) &&
1339          "the operand of .setfp directive should be either $sp or $fp");
1340 
1341   UsedFP = true;
1342   FPReg = NewFPReg;
1343 
1344   if (NewSPReg == ARM::SP)
1345     FPOffset = SPOffset + Offset;
1346   else
1347     FPOffset += Offset;
1348 }
1349 
1350 void ARMELFStreamer::emitMovSP(unsigned Reg, int64_t Offset) {
1351   assert((Reg != ARM::SP && Reg != ARM::PC) &&
1352          "the operand of .movsp cannot be either sp or pc");
1353   assert(FPReg == ARM::SP && "current FP must be SP");
1354 
1355   FlushPendingOffset();
1356 
1357   FPReg = Reg;
1358   FPOffset = SPOffset + Offset;
1359 
1360   const MCRegisterInfo *MRI = getContext().getRegisterInfo();
1361   UnwindOpAsm.EmitSetSP(MRI->getEncodingValue(FPReg));
1362 }
1363 
1364 void ARMELFStreamer::emitPad(int64_t Offset) {
1365   // Track the change of the $sp offset
1366   SPOffset -= Offset;
1367 
1368   // To squash multiple .pad directives, we should delay the unwind opcode
1369   // until the .save, .vsave, .handlerdata, or .fnend directives.
1370   PendingOffset -= Offset;
1371 }
1372 
1373 void ARMELFStreamer::emitRegSave(const SmallVectorImpl<unsigned> &RegList,
1374                                  bool IsVector) {
1375   // Collect the registers in the register list
1376   unsigned Count = 0;
1377   uint32_t Mask = 0;
1378   const MCRegisterInfo *MRI = getContext().getRegisterInfo();
1379   for (size_t i = 0; i < RegList.size(); ++i) {
1380     unsigned Reg = MRI->getEncodingValue(RegList[i]);
1381     assert(Reg < (IsVector ? 32U : 16U) && "Register out of range");
1382     unsigned Bit = (1u << Reg);
1383     if ((Mask & Bit) == 0) {
1384       Mask |= Bit;
1385       ++Count;
1386     }
1387   }
1388 
1389   // Track the change the $sp offset: For the .save directive, the
1390   // corresponding push instruction will decrease the $sp by (4 * Count).
1391   // For the .vsave directive, the corresponding vpush instruction will
1392   // decrease $sp by (8 * Count).
1393   SPOffset -= Count * (IsVector ? 8 : 4);
1394 
1395   // Emit the opcode
1396   FlushPendingOffset();
1397   if (IsVector)
1398     UnwindOpAsm.EmitVFPRegSave(Mask);
1399   else
1400     UnwindOpAsm.EmitRegSave(Mask);
1401 }
1402 
1403 void ARMELFStreamer::emitUnwindRaw(int64_t Offset,
1404                                    const SmallVectorImpl<uint8_t> &Opcodes) {
1405   FlushPendingOffset();
1406   SPOffset = SPOffset - Offset;
1407   UnwindOpAsm.EmitRaw(Opcodes);
1408 }
1409 
1410 namespace llvm {
1411 
1412 MCTargetStreamer *createARMTargetAsmStreamer(MCStreamer &S,
1413                                              formatted_raw_ostream &OS,
1414                                              MCInstPrinter *InstPrint,
1415                                              bool isVerboseAsm) {
1416   return new ARMTargetAsmStreamer(S, OS, *InstPrint, isVerboseAsm);
1417 }
1418 
1419 MCTargetStreamer *createARMNullTargetStreamer(MCStreamer &S) {
1420   return new ARMTargetStreamer(S);
1421 }
1422 
1423 MCTargetStreamer *createARMObjectTargetStreamer(MCStreamer &S,
1424                                                 const MCSubtargetInfo &STI) {
1425   const Triple &TT = STI.getTargetTriple();
1426   if (TT.isOSBinFormatELF())
1427     return new ARMTargetELFStreamer(S);
1428   return new ARMTargetStreamer(S);
1429 }
1430 
1431 MCELFStreamer *createARMELFStreamer(MCContext &Context, MCAsmBackend &TAB,
1432                                     raw_pwrite_stream &OS,
1433                                     MCCodeEmitter *Emitter, bool RelaxAll,
1434                                     bool IsThumb) {
1435     ARMELFStreamer *S = new ARMELFStreamer(Context, TAB, OS, Emitter, IsThumb);
1436     // FIXME: This should eventually end up somewhere else where more
1437     // intelligent flag decisions can be made. For now we are just maintaining
1438     // the status quo for ARM and setting EF_ARM_EABI_VER5 as the default.
1439     S->getAssembler().setELFHeaderEFlags(ELF::EF_ARM_EABI_VER5);
1440 
1441     if (RelaxAll)
1442       S->getAssembler().setRelaxAll(true);
1443     return S;
1444 }
1445 
1446 } // end namespace llvm
1447