ARMELFStreamer.cpp revision 263508 
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 "ARMBuildAttrs.h"
17#include "ARMFPUName.h"
18#include "ARMRegisterInfo.h"
19#include "ARMUnwindOp.h"
20#include "ARMUnwindOpAsm.h"
21#include "llvm/ADT/SmallPtrSet.h"
22#include "llvm/ADT/Twine.h"
23#include "llvm/MC/MCAsmBackend.h"
24#include "llvm/MC/MCAssembler.h"
25#include "llvm/MC/MCCodeEmitter.h"
26#include "llvm/MC/MCContext.h"
27#include "llvm/MC/MCELF.h"
28#include "llvm/MC/MCELFStreamer.h"
29#include "llvm/MC/MCELFSymbolFlags.h"
30#include "llvm/MC/MCExpr.h"
31#include "llvm/MC/MCInst.h"
32#include "llvm/MC/MCInstPrinter.h"
33#include "llvm/MC/MCObjectStreamer.h"
34#include "llvm/MC/MCRegisterInfo.h"
35#include "llvm/MC/MCSection.h"
36#include "llvm/MC/MCSectionELF.h"
37#include "llvm/MC/MCStreamer.h"
38#include "llvm/MC/MCSymbol.h"
39#include "llvm/MC/MCValue.h"
40#include "llvm/Support/Debug.h"
41#include "llvm/Support/ELF.h"
42#include "llvm/Support/FormattedStream.h"
43#include "llvm/Support/raw_ostream.h"
44#include <algorithm>
45
46using namespace llvm;
47
48static std::string GetAEABIUnwindPersonalityName(unsigned Index) {
49  assert(Index < NUM_PERSONALITY_INDEX && "Invalid personality index");
50  return (Twine("__aeabi_unwind_cpp_pr") + Twine(Index)).str();
51}
52
53static const char *GetFPUName(unsigned ID) {
54  switch (ID) {
55  default:
56    llvm_unreachable("Unknown FPU kind");
57    break;
58#define ARM_FPU_NAME(NAME, ID) case ARM::ID: return NAME;
59#include "ARMFPUName.def"
60  }
61  return NULL;
62}
63
64namespace {
65
66class ARMELFStreamer;
67
68class ARMTargetAsmStreamer : public ARMTargetStreamer {
69  formatted_raw_ostream &OS;
70  MCInstPrinter &InstPrinter;
71
72  virtual void emitFnStart();
73  virtual void emitFnEnd();
74  virtual void emitCantUnwind();
75  virtual void emitPersonality(const MCSymbol *Personality);
76  virtual void emitHandlerData();
77  virtual void emitSetFP(unsigned FpReg, unsigned SpReg, int64_t Offset = 0);
78  virtual void emitPad(int64_t Offset);
79  virtual void emitRegSave(const SmallVectorImpl<unsigned> &RegList,
80                           bool isVector);
81
82  virtual void switchVendor(StringRef Vendor);
83  virtual void emitAttribute(unsigned Attribute, unsigned Value);
84  virtual void emitTextAttribute(unsigned Attribute, StringRef String);
85  virtual void emitFPU(unsigned FPU);
86  virtual void finishAttributeSection();
87
88public:
89  ARMTargetAsmStreamer(formatted_raw_ostream &OS, MCInstPrinter &InstPrinter);
90};
91
92ARMTargetAsmStreamer::ARMTargetAsmStreamer(formatted_raw_ostream &OS,
93                                           MCInstPrinter &InstPrinter)
94    : OS(OS), InstPrinter(InstPrinter) {}
95void ARMTargetAsmStreamer::emitFnStart() { OS << "\t.fnstart\n"; }
96void ARMTargetAsmStreamer::emitFnEnd() { OS << "\t.fnend\n"; }
97void ARMTargetAsmStreamer::emitCantUnwind() { OS << "\t.cantunwind\n"; }
98void ARMTargetAsmStreamer::emitPersonality(const MCSymbol *Personality) {
99  OS << "\t.personality " << Personality->getName() << '\n';
100}
101void ARMTargetAsmStreamer::emitHandlerData() { OS << "\t.handlerdata\n"; }
102void ARMTargetAsmStreamer::emitSetFP(unsigned FpReg, unsigned SpReg,
103                                     int64_t Offset) {
104  OS << "\t.setfp\t";
105  InstPrinter.printRegName(OS, FpReg);
106  OS << ", ";
107  InstPrinter.printRegName(OS, SpReg);
108  if (Offset)
109    OS << ", #" << Offset;
110  OS << '\n';
111}
112void ARMTargetAsmStreamer::emitPad(int64_t Offset) {
113  OS << "\t.pad\t#" << Offset << '\n';
114}
115void ARMTargetAsmStreamer::emitRegSave(const SmallVectorImpl<unsigned> &RegList,
116                                       bool isVector) {
117  assert(RegList.size() && "RegList should not be empty");
118  if (isVector)
119    OS << "\t.vsave\t{";
120  else
121    OS << "\t.save\t{";
122
123  InstPrinter.printRegName(OS, RegList[0]);
124
125  for (unsigned i = 1, e = RegList.size(); i != e; ++i) {
126    OS << ", ";
127    InstPrinter.printRegName(OS, RegList[i]);
128  }
129
130  OS << "}\n";
131}
132void ARMTargetAsmStreamer::switchVendor(StringRef Vendor) {
133}
134void ARMTargetAsmStreamer::emitAttribute(unsigned Attribute, unsigned Value) {
135  OS << "\t.eabi_attribute\t" << Attribute << ", " << Twine(Value) << "\n";
136}
137void ARMTargetAsmStreamer::emitTextAttribute(unsigned Attribute,
138                                             StringRef String) {
139  switch (Attribute) {
140  default: llvm_unreachable("Unsupported Text attribute in ASM Mode");
141  case ARMBuildAttrs::CPU_name:
142    OS << "\t.cpu\t" << String.lower() << "\n";
143    break;
144  }
145}
146void ARMTargetAsmStreamer::emitFPU(unsigned FPU) {
147  OS << "\t.fpu\t" << GetFPUName(FPU) << "\n";
148}
149void ARMTargetAsmStreamer::finishAttributeSection() {
150}
151
152class ARMTargetELFStreamer : public ARMTargetStreamer {
153private:
154  // This structure holds all attributes, accounting for
155  // their string/numeric value, so we can later emmit them
156  // in declaration order, keeping all in the same vector
157  struct AttributeItem {
158    enum {
159      HiddenAttribute = 0,
160      NumericAttribute,
161      TextAttribute
162    } Type;
163    unsigned Tag;
164    unsigned IntValue;
165    StringRef StringValue;
166
167    static bool LessTag(const AttributeItem &LHS, const AttributeItem &RHS) {
168      return (LHS.Tag < RHS.Tag);
169    }
170  };
171
172  StringRef CurrentVendor;
173  unsigned FPU;
174  SmallVector<AttributeItem, 64> Contents;
175
176  const MCSection *AttributeSection;
177
178  // FIXME: this should be in a more generic place, but
179  // getULEBSize() is in MCAsmInfo and will be moved to MCDwarf
180  static size_t getULEBSize(int Value) {
181    size_t Size = 0;
182    do {
183      Value >>= 7;
184      Size += sizeof(int8_t); // Is this really necessary?
185    } while (Value);
186    return Size;
187  }
188
189  AttributeItem *getAttributeItem(unsigned Attribute) {
190    for (size_t i = 0; i < Contents.size(); ++i)
191      if (Contents[i].Tag == Attribute)
192        return &Contents[i];
193    return 0;
194  }
195
196  void setAttributeItem(unsigned Attribute, unsigned Value,
197                        bool OverwriteExisting) {
198    // Look for existing attribute item
199    if (AttributeItem *Item = getAttributeItem(Attribute)) {
200      if (!OverwriteExisting)
201        return;
202      Item->IntValue = Value;
203      return;
204    }
205
206    // Create new attribute item
207    AttributeItem Item = {
208      AttributeItem::NumericAttribute,
209      Attribute,
210      Value,
211      StringRef("")
212    };
213    Contents.push_back(Item);
214  }
215
216  void setAttributeItem(unsigned Attribute, StringRef Value,
217                        bool OverwriteExisting) {
218    // Look for existing attribute item
219    if (AttributeItem *Item = getAttributeItem(Attribute)) {
220      if (!OverwriteExisting)
221        return;
222      Item->StringValue = Value;
223      return;
224    }
225
226    // Create new attribute item
227    AttributeItem Item = {
228      AttributeItem::TextAttribute,
229      Attribute,
230      0,
231      Value
232    };
233    Contents.push_back(Item);
234  }
235
236  void emitFPUDefaultAttributes();
237
238  ARMELFStreamer &getStreamer();
239
240  virtual void emitFnStart();
241  virtual void emitFnEnd();
242  virtual void emitCantUnwind();
243  virtual void emitPersonality(const MCSymbol *Personality);
244  virtual void emitHandlerData();
245  virtual void emitSetFP(unsigned FpReg, unsigned SpReg, int64_t Offset = 0);
246  virtual void emitPad(int64_t Offset);
247  virtual void emitRegSave(const SmallVectorImpl<unsigned> &RegList,
248                           bool isVector);
249
250  virtual void switchVendor(StringRef Vendor);
251  virtual void emitAttribute(unsigned Attribute, unsigned Value);
252  virtual void emitTextAttribute(unsigned Attribute, StringRef String);
253  virtual void emitFPU(unsigned FPU);
254  virtual void finishAttributeSection();
255
256  size_t calculateContentSize() const;
257
258public:
259  ARMTargetELFStreamer()
260    : ARMTargetStreamer(), CurrentVendor("aeabi"), FPU(ARM::INVALID_FPU),
261      AttributeSection(0) {
262  }
263};
264
265/// Extend the generic ELFStreamer class so that it can emit mapping symbols at
266/// the appropriate points in the object files. These symbols are defined in the
267/// ARM ELF ABI: infocenter.arm.com/help/topic/com.arm.../IHI0044D_aaelf.pdf.
268///
269/// In brief: $a, $t or $d should be emitted at the start of each contiguous
270/// region of ARM code, Thumb code or data in a section. In practice, this
271/// emission does not rely on explicit assembler directives but on inherent
272/// properties of the directives doing the emission (e.g. ".byte" is data, "add
273/// r0, r0, r0" an instruction).
274///
275/// As a result this system is orthogonal to the DataRegion infrastructure used
276/// by MachO. Beware!
277class ARMELFStreamer : public MCELFStreamer {
278public:
279  friend class ARMTargetELFStreamer;
280
281  ARMELFStreamer(MCContext &Context, MCTargetStreamer *TargetStreamer,
282                 MCAsmBackend &TAB, raw_ostream &OS, MCCodeEmitter *Emitter,
283                 bool IsThumb)
284      : MCELFStreamer(Context, TargetStreamer, TAB, OS, Emitter),
285        IsThumb(IsThumb), MappingSymbolCounter(0), LastEMS(EMS_None) {
286    Reset();
287  }
288
289  ~ARMELFStreamer() {}
290
291  virtual void FinishImpl();
292
293  // ARM exception handling directives
294  void emitFnStart();
295  void emitFnEnd();
296  void emitCantUnwind();
297  void emitPersonality(const MCSymbol *Per);
298  void emitHandlerData();
299  void emitSetFP(unsigned NewFpReg, unsigned NewSpReg, int64_t Offset = 0);
300  void emitPad(int64_t Offset);
301  void emitRegSave(const SmallVectorImpl<unsigned> &RegList, bool isVector);
302
303  virtual void ChangeSection(const MCSection *Section,
304                             const MCExpr *Subsection) {
305    // We have to keep track of the mapping symbol state of any sections we
306    // use. Each one should start off as EMS_None, which is provided as the
307    // default constructor by DenseMap::lookup.
308    LastMappingSymbols[getPreviousSection().first] = LastEMS;
309    LastEMS = LastMappingSymbols.lookup(Section);
310
311    MCELFStreamer::ChangeSection(Section, Subsection);
312  }
313
314  /// This function is the one used to emit instruction data into the ELF
315  /// streamer. We override it to add the appropriate mapping symbol if
316  /// necessary.
317  virtual void EmitInstruction(const MCInst& Inst) {
318    if (IsThumb)
319      EmitThumbMappingSymbol();
320    else
321      EmitARMMappingSymbol();
322
323    MCELFStreamer::EmitInstruction(Inst);
324  }
325
326  /// This is one of the functions used to emit data into an ELF section, so the
327  /// ARM streamer overrides it to add the appropriate mapping symbol ($d) if
328  /// necessary.
329  virtual void EmitBytes(StringRef Data) {
330    EmitDataMappingSymbol();
331    MCELFStreamer::EmitBytes(Data);
332  }
333
334  /// This is one of the functions used to emit data into an ELF section, so the
335  /// ARM streamer overrides it to add the appropriate mapping symbol ($d) if
336  /// necessary.
337  virtual void EmitValueImpl(const MCExpr *Value, unsigned Size) {
338    EmitDataMappingSymbol();
339    MCELFStreamer::EmitValueImpl(Value, Size);
340  }
341
342  virtual void EmitAssemblerFlag(MCAssemblerFlag Flag) {
343    MCELFStreamer::EmitAssemblerFlag(Flag);
344
345    switch (Flag) {
346    case MCAF_SyntaxUnified:
347      return; // no-op here.
348    case MCAF_Code16:
349      IsThumb = true;
350      return; // Change to Thumb mode
351    case MCAF_Code32:
352      IsThumb = false;
353      return; // Change to ARM mode
354    case MCAF_Code64:
355      return;
356    case MCAF_SubsectionsViaSymbols:
357      return;
358    }
359  }
360
361private:
362  enum ElfMappingSymbol {
363    EMS_None,
364    EMS_ARM,
365    EMS_Thumb,
366    EMS_Data
367  };
368
369  void EmitDataMappingSymbol() {
370    if (LastEMS == EMS_Data) return;
371    EmitMappingSymbol("$d");
372    LastEMS = EMS_Data;
373  }
374
375  void EmitThumbMappingSymbol() {
376    if (LastEMS == EMS_Thumb) return;
377    EmitMappingSymbol("$t");
378    LastEMS = EMS_Thumb;
379  }
380
381  void EmitARMMappingSymbol() {
382    if (LastEMS == EMS_ARM) return;
383    EmitMappingSymbol("$a");
384    LastEMS = EMS_ARM;
385  }
386
387  void EmitMappingSymbol(StringRef Name) {
388    MCSymbol *Start = getContext().CreateTempSymbol();
389    EmitLabel(Start);
390
391    MCSymbol *Symbol =
392      getContext().GetOrCreateSymbol(Name + "." +
393                                     Twine(MappingSymbolCounter++));
394
395    MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
396    MCELF::SetType(SD, ELF::STT_NOTYPE);
397    MCELF::SetBinding(SD, ELF::STB_LOCAL);
398    SD.setExternal(false);
399    AssignSection(Symbol, getCurrentSection().first);
400
401    const MCExpr *Value = MCSymbolRefExpr::Create(Start, getContext());
402    Symbol->setVariableValue(Value);
403  }
404
405  void EmitThumbFunc(MCSymbol *Func) {
406    // FIXME: Anything needed here to flag the function as thumb?
407
408    getAssembler().setIsThumbFunc(Func);
409
410    MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Func);
411    SD.setFlags(SD.getFlags() | ELF_Other_ThumbFunc);
412  }
413
414  // Helper functions for ARM exception handling directives
415  void Reset();
416
417  void EmitPersonalityFixup(StringRef Name);
418  void FlushPendingOffset();
419  void FlushUnwindOpcodes(bool NoHandlerData);
420
421  void SwitchToEHSection(const char *Prefix, unsigned Type, unsigned Flags,
422                         SectionKind Kind, const MCSymbol &Fn);
423  void SwitchToExTabSection(const MCSymbol &FnStart);
424  void SwitchToExIdxSection(const MCSymbol &FnStart);
425
426  bool IsThumb;
427  int64_t MappingSymbolCounter;
428
429  DenseMap<const MCSection *, ElfMappingSymbol> LastMappingSymbols;
430  ElfMappingSymbol LastEMS;
431
432  // ARM Exception Handling Frame Information
433  MCSymbol *ExTab;
434  MCSymbol *FnStart;
435  const MCSymbol *Personality;
436  unsigned PersonalityIndex;
437  unsigned FPReg; // Frame pointer register
438  int64_t FPOffset; // Offset: (final frame pointer) - (initial $sp)
439  int64_t SPOffset; // Offset: (final $sp) - (initial $sp)
440  int64_t PendingOffset; // Offset: (final $sp) - (emitted $sp)
441  bool UsedFP;
442  bool CantUnwind;
443  SmallVector<uint8_t, 64> Opcodes;
444  UnwindOpcodeAssembler UnwindOpAsm;
445};
446} // end anonymous namespace
447
448ARMELFStreamer &ARMTargetELFStreamer::getStreamer() {
449  ARMELFStreamer *S = static_cast<ARMELFStreamer *>(Streamer);
450  return *S;
451}
452
453void ARMTargetELFStreamer::emitFnStart() { getStreamer().emitFnStart(); }
454void ARMTargetELFStreamer::emitFnEnd() { getStreamer().emitFnEnd(); }
455void ARMTargetELFStreamer::emitCantUnwind() { getStreamer().emitCantUnwind(); }
456void ARMTargetELFStreamer::emitPersonality(const MCSymbol *Personality) {
457  getStreamer().emitPersonality(Personality);
458}
459void ARMTargetELFStreamer::emitHandlerData() {
460  getStreamer().emitHandlerData();
461}
462void ARMTargetELFStreamer::emitSetFP(unsigned FpReg, unsigned SpReg,
463                                     int64_t Offset) {
464  getStreamer().emitSetFP(FpReg, SpReg, Offset);
465}
466void ARMTargetELFStreamer::emitPad(int64_t Offset) {
467  getStreamer().emitPad(Offset);
468}
469void ARMTargetELFStreamer::emitRegSave(const SmallVectorImpl<unsigned> &RegList,
470                                       bool isVector) {
471  getStreamer().emitRegSave(RegList, isVector);
472}
473void ARMTargetELFStreamer::switchVendor(StringRef Vendor) {
474  assert(!Vendor.empty() && "Vendor cannot be empty.");
475
476  if (CurrentVendor == Vendor)
477    return;
478
479  if (!CurrentVendor.empty())
480    finishAttributeSection();
481
482  assert(Contents.empty() &&
483         ".ARM.attributes should be flushed before changing vendor");
484  CurrentVendor = Vendor;
485
486}
487void ARMTargetELFStreamer::emitAttribute(unsigned Attribute, unsigned Value) {
488  setAttributeItem(Attribute, Value, /* OverwriteExisting= */ true);
489}
490void ARMTargetELFStreamer::emitTextAttribute(unsigned Attribute,
491                                             StringRef Value) {
492  setAttributeItem(Attribute, Value, /* OverwriteExisting= */ true);
493}
494void ARMTargetELFStreamer::emitFPU(unsigned Value) {
495  FPU = Value;
496}
497void ARMTargetELFStreamer::emitFPUDefaultAttributes() {
498  switch (FPU) {
499  case ARM::VFP:
500  case ARM::VFPV2:
501    setAttributeItem(ARMBuildAttrs::VFP_arch,
502                     ARMBuildAttrs::AllowFPv2,
503                     /* OverwriteExisting= */ false);
504    break;
505
506  case ARM::VFPV3:
507    setAttributeItem(ARMBuildAttrs::VFP_arch,
508                     ARMBuildAttrs::AllowFPv3A,
509                     /* OverwriteExisting= */ false);
510    break;
511
512  case ARM::VFPV3_D16:
513    setAttributeItem(ARMBuildAttrs::VFP_arch,
514                     ARMBuildAttrs::AllowFPv3B,
515                     /* OverwriteExisting= */ false);
516    break;
517
518  case ARM::VFPV4:
519    setAttributeItem(ARMBuildAttrs::VFP_arch,
520                     ARMBuildAttrs::AllowFPv4A,
521                     /* OverwriteExisting= */ false);
522    break;
523
524  case ARM::VFPV4_D16:
525    setAttributeItem(ARMBuildAttrs::VFP_arch,
526                     ARMBuildAttrs::AllowFPv4B,
527                     /* OverwriteExisting= */ false);
528    break;
529
530  case ARM::FP_ARMV8:
531    setAttributeItem(ARMBuildAttrs::VFP_arch,
532                     ARMBuildAttrs::AllowFPARMv8A,
533                     /* OverwriteExisting= */ false);
534    break;
535
536  case ARM::NEON:
537    setAttributeItem(ARMBuildAttrs::VFP_arch,
538                     ARMBuildAttrs::AllowFPv3A,
539                     /* OverwriteExisting= */ false);
540    setAttributeItem(ARMBuildAttrs::Advanced_SIMD_arch,
541                     ARMBuildAttrs::AllowNeon,
542                     /* OverwriteExisting= */ false);
543    break;
544
545  case ARM::NEON_VFPV4:
546    setAttributeItem(ARMBuildAttrs::VFP_arch,
547                     ARMBuildAttrs::AllowFPv4A,
548                     /* OverwriteExisting= */ false);
549    setAttributeItem(ARMBuildAttrs::Advanced_SIMD_arch,
550                     ARMBuildAttrs::AllowNeon2,
551                     /* OverwriteExisting= */ false);
552    break;
553
554  case ARM::NEON_FP_ARMV8:
555  case ARM::CRYPTO_NEON_FP_ARMV8:
556    setAttributeItem(ARMBuildAttrs::VFP_arch,
557                     ARMBuildAttrs::AllowFPARMv8A,
558                     /* OverwriteExisting= */ false);
559    setAttributeItem(ARMBuildAttrs::Advanced_SIMD_arch,
560                     ARMBuildAttrs::AllowNeonARMv8,
561                     /* OverwriteExisting= */ false);
562    break;
563
564  default:
565    report_fatal_error("Unknown FPU: " + Twine(FPU));
566    break;
567  }
568}
569size_t ARMTargetELFStreamer::calculateContentSize() const {
570  size_t Result = 0;
571  for (size_t i = 0; i < Contents.size(); ++i) {
572    AttributeItem item = Contents[i];
573    switch (item.Type) {
574    case AttributeItem::HiddenAttribute:
575      break;
576    case AttributeItem::NumericAttribute:
577      Result += getULEBSize(item.Tag);
578      Result += getULEBSize(item.IntValue);
579      break;
580    case AttributeItem::TextAttribute:
581      Result += getULEBSize(item.Tag);
582      Result += item.StringValue.size() + 1; // string + '\0'
583      break;
584    }
585  }
586  return Result;
587}
588void ARMTargetELFStreamer::finishAttributeSection() {
589  // <format-version>
590  // [ <section-length> "vendor-name"
591  // [ <file-tag> <size> <attribute>*
592  //   | <section-tag> <size> <section-number>* 0 <attribute>*
593  //   | <symbol-tag> <size> <symbol-number>* 0 <attribute>*
594  //   ]+
595  // ]*
596
597  if (FPU != ARM::INVALID_FPU)
598    emitFPUDefaultAttributes();
599
600  if (Contents.empty())
601    return;
602
603  std::sort(Contents.begin(), Contents.end(), AttributeItem::LessTag);
604
605  ARMELFStreamer &Streamer = getStreamer();
606
607  // Switch to .ARM.attributes section
608  if (AttributeSection) {
609    Streamer.SwitchSection(AttributeSection);
610  } else {
611    AttributeSection =
612      Streamer.getContext().getELFSection(".ARM.attributes",
613                                          ELF::SHT_ARM_ATTRIBUTES,
614                                          0,
615                                          SectionKind::getMetadata());
616    Streamer.SwitchSection(AttributeSection);
617
618    // Format version
619    Streamer.EmitIntValue(0x41, 1);
620  }
621
622  // Vendor size + Vendor name + '\0'
623  const size_t VendorHeaderSize = 4 + CurrentVendor.size() + 1;
624
625  // Tag + Tag Size
626  const size_t TagHeaderSize = 1 + 4;
627
628  const size_t ContentsSize = calculateContentSize();
629
630  Streamer.EmitIntValue(VendorHeaderSize + TagHeaderSize + ContentsSize, 4);
631  Streamer.EmitBytes(CurrentVendor);
632  Streamer.EmitIntValue(0, 1); // '\0'
633
634  Streamer.EmitIntValue(ARMBuildAttrs::File, 1);
635  Streamer.EmitIntValue(TagHeaderSize + ContentsSize, 4);
636
637  // Size should have been accounted for already, now
638  // emit each field as its type (ULEB or String)
639  for (size_t i = 0; i < Contents.size(); ++i) {
640    AttributeItem item = Contents[i];
641    Streamer.EmitULEB128IntValue(item.Tag);
642    switch (item.Type) {
643    default: llvm_unreachable("Invalid attribute type");
644    case AttributeItem::NumericAttribute:
645      Streamer.EmitULEB128IntValue(item.IntValue);
646      break;
647    case AttributeItem::TextAttribute:
648      Streamer.EmitBytes(item.StringValue.upper());
649      Streamer.EmitIntValue(0, 1); // '\0'
650      break;
651    }
652  }
653
654  Contents.clear();
655  FPU = ARM::INVALID_FPU;
656}
657
658void ARMELFStreamer::FinishImpl() {
659  MCTargetStreamer &TS = getTargetStreamer();
660  ARMTargetStreamer &ATS = static_cast<ARMTargetStreamer &>(TS);
661  ATS.finishAttributeSection();
662
663  MCELFStreamer::FinishImpl();
664}
665
666inline void ARMELFStreamer::SwitchToEHSection(const char *Prefix,
667                                              unsigned Type,
668                                              unsigned Flags,
669                                              SectionKind Kind,
670                                              const MCSymbol &Fn) {
671  const MCSectionELF &FnSection =
672    static_cast<const MCSectionELF &>(Fn.getSection());
673
674  // Create the name for new section
675  StringRef FnSecName(FnSection.getSectionName());
676  SmallString<128> EHSecName(Prefix);
677  if (FnSecName != ".text") {
678    EHSecName += FnSecName;
679  }
680
681  // Get .ARM.extab or .ARM.exidx section
682  const MCSectionELF *EHSection = NULL;
683  if (const MCSymbol *Group = FnSection.getGroup()) {
684    EHSection = getContext().getELFSection(
685      EHSecName, Type, Flags | ELF::SHF_GROUP, Kind,
686      FnSection.getEntrySize(), Group->getName());
687  } else {
688    EHSection = getContext().getELFSection(EHSecName, Type, Flags, Kind);
689  }
690  assert(EHSection && "Failed to get the required EH section");
691
692  // Switch to .ARM.extab or .ARM.exidx section
693  SwitchSection(EHSection);
694  EmitCodeAlignment(4, 0);
695}
696
697inline void ARMELFStreamer::SwitchToExTabSection(const MCSymbol &FnStart) {
698  SwitchToEHSection(".ARM.extab",
699                    ELF::SHT_PROGBITS,
700                    ELF::SHF_ALLOC,
701                    SectionKind::getDataRel(),
702                    FnStart);
703}
704
705inline void ARMELFStreamer::SwitchToExIdxSection(const MCSymbol &FnStart) {
706  SwitchToEHSection(".ARM.exidx",
707                    ELF::SHT_ARM_EXIDX,
708                    ELF::SHF_ALLOC | ELF::SHF_LINK_ORDER,
709                    SectionKind::getDataRel(),
710                    FnStart);
711}
712
713void ARMELFStreamer::Reset() {
714  ExTab = NULL;
715  FnStart = NULL;
716  Personality = NULL;
717  PersonalityIndex = NUM_PERSONALITY_INDEX;
718  FPReg = ARM::SP;
719  FPOffset = 0;
720  SPOffset = 0;
721  PendingOffset = 0;
722  UsedFP = false;
723  CantUnwind = false;
724
725  Opcodes.clear();
726  UnwindOpAsm.Reset();
727}
728
729void ARMELFStreamer::emitFnStart() {
730  assert(FnStart == 0);
731  FnStart = getContext().CreateTempSymbol();
732  EmitLabel(FnStart);
733}
734
735void ARMELFStreamer::emitFnEnd() {
736  assert(FnStart && ".fnstart must preceeds .fnend");
737
738  // Emit unwind opcodes if there is no .handlerdata directive
739  if (!ExTab && !CantUnwind)
740    FlushUnwindOpcodes(true);
741
742  // Emit the exception index table entry
743  SwitchToExIdxSection(*FnStart);
744
745  if (PersonalityIndex < NUM_PERSONALITY_INDEX)
746    EmitPersonalityFixup(GetAEABIUnwindPersonalityName(PersonalityIndex));
747
748  const MCSymbolRefExpr *FnStartRef =
749    MCSymbolRefExpr::Create(FnStart,
750                            MCSymbolRefExpr::VK_ARM_PREL31,
751                            getContext());
752
753  EmitValue(FnStartRef, 4);
754
755  if (CantUnwind) {
756    EmitIntValue(EXIDX_CANTUNWIND, 4);
757  } else if (ExTab) {
758    // Emit a reference to the unwind opcodes in the ".ARM.extab" section.
759    const MCSymbolRefExpr *ExTabEntryRef =
760      MCSymbolRefExpr::Create(ExTab,
761                              MCSymbolRefExpr::VK_ARM_PREL31,
762                              getContext());
763    EmitValue(ExTabEntryRef, 4);
764  } else {
765    // For the __aeabi_unwind_cpp_pr0, we have to emit the unwind opcodes in
766    // the second word of exception index table entry.  The size of the unwind
767    // opcodes should always be 4 bytes.
768    assert(PersonalityIndex == AEABI_UNWIND_CPP_PR0 &&
769           "Compact model must use __aeabi_cpp_unwind_pr0 as personality");
770    assert(Opcodes.size() == 4u &&
771           "Unwind opcode size for __aeabi_cpp_unwind_pr0 must be equal to 4");
772    EmitBytes(StringRef(reinterpret_cast<const char*>(Opcodes.data()),
773                        Opcodes.size()));
774  }
775
776  // Switch to the section containing FnStart
777  SwitchSection(&FnStart->getSection());
778
779  // Clean exception handling frame information
780  Reset();
781}
782
783void ARMELFStreamer::emitCantUnwind() { CantUnwind = true; }
784
785// Add the R_ARM_NONE fixup at the same position
786void ARMELFStreamer::EmitPersonalityFixup(StringRef Name) {
787  const MCSymbol *PersonalitySym = getContext().GetOrCreateSymbol(Name);
788
789  const MCSymbolRefExpr *PersonalityRef = MCSymbolRefExpr::Create(
790      PersonalitySym, MCSymbolRefExpr::VK_ARM_NONE, getContext());
791
792  AddValueSymbols(PersonalityRef);
793  MCDataFragment *DF = getOrCreateDataFragment();
794  DF->getFixups().push_back(MCFixup::Create(DF->getContents().size(),
795                                            PersonalityRef,
796                                            MCFixup::getKindForSize(4, false)));
797}
798
799void ARMELFStreamer::FlushPendingOffset() {
800  if (PendingOffset != 0) {
801    UnwindOpAsm.EmitSPOffset(-PendingOffset);
802    PendingOffset = 0;
803  }
804}
805
806void ARMELFStreamer::FlushUnwindOpcodes(bool NoHandlerData) {
807  // Emit the unwind opcode to restore $sp.
808  if (UsedFP) {
809    const MCRegisterInfo *MRI = getContext().getRegisterInfo();
810    int64_t LastRegSaveSPOffset = SPOffset - PendingOffset;
811    UnwindOpAsm.EmitSPOffset(LastRegSaveSPOffset - FPOffset);
812    UnwindOpAsm.EmitSetSP(MRI->getEncodingValue(FPReg));
813  } else {
814    FlushPendingOffset();
815  }
816
817  // Finalize the unwind opcode sequence
818  UnwindOpAsm.Finalize(PersonalityIndex, Opcodes);
819
820  // For compact model 0, we have to emit the unwind opcodes in the .ARM.exidx
821  // section.  Thus, we don't have to create an entry in the .ARM.extab
822  // section.
823  if (NoHandlerData && PersonalityIndex == AEABI_UNWIND_CPP_PR0)
824    return;
825
826  // Switch to .ARM.extab section.
827  SwitchToExTabSection(*FnStart);
828
829  // Create .ARM.extab label for offset in .ARM.exidx
830  assert(!ExTab);
831  ExTab = getContext().CreateTempSymbol();
832  EmitLabel(ExTab);
833
834  // Emit personality
835  if (Personality) {
836    const MCSymbolRefExpr *PersonalityRef =
837      MCSymbolRefExpr::Create(Personality,
838                              MCSymbolRefExpr::VK_ARM_PREL31,
839                              getContext());
840
841    EmitValue(PersonalityRef, 4);
842  }
843
844  // Emit unwind opcodes
845  EmitBytes(StringRef(reinterpret_cast<const char *>(Opcodes.data()),
846                      Opcodes.size()));
847
848  // According to ARM EHABI section 9.2, if the __aeabi_unwind_cpp_pr1() or
849  // __aeabi_unwind_cpp_pr2() is used, then the handler data must be emitted
850  // after the unwind opcodes.  The handler data consists of several 32-bit
851  // words, and should be terminated by zero.
852  //
853  // In case that the .handlerdata directive is not specified by the
854  // programmer, we should emit zero to terminate the handler data.
855  if (NoHandlerData && !Personality)
856    EmitIntValue(0, 4);
857}
858
859void ARMELFStreamer::emitHandlerData() { FlushUnwindOpcodes(false); }
860
861void ARMELFStreamer::emitPersonality(const MCSymbol *Per) {
862  Personality = Per;
863  UnwindOpAsm.setPersonality(Per);
864}
865
866void ARMELFStreamer::emitSetFP(unsigned NewFPReg, unsigned NewSPReg,
867                               int64_t Offset) {
868  assert((NewSPReg == ARM::SP || NewSPReg == FPReg) &&
869         "the operand of .setfp directive should be either $sp or $fp");
870
871  UsedFP = true;
872  FPReg = NewFPReg;
873
874  if (NewSPReg == ARM::SP)
875    FPOffset = SPOffset + Offset;
876  else
877    FPOffset += Offset;
878}
879
880void ARMELFStreamer::emitPad(int64_t Offset) {
881  // Track the change of the $sp offset
882  SPOffset -= Offset;
883
884  // To squash multiple .pad directives, we should delay the unwind opcode
885  // until the .save, .vsave, .handlerdata, or .fnend directives.
886  PendingOffset -= Offset;
887}
888
889void ARMELFStreamer::emitRegSave(const SmallVectorImpl<unsigned> &RegList,
890                                 bool IsVector) {
891  // Collect the registers in the register list
892  unsigned Count = 0;
893  uint32_t Mask = 0;
894  const MCRegisterInfo *MRI = getContext().getRegisterInfo();
895  for (size_t i = 0; i < RegList.size(); ++i) {
896    unsigned Reg = MRI->getEncodingValue(RegList[i]);
897    assert(Reg < (IsVector ? 32U : 16U) && "Register out of range");
898    unsigned Bit = (1u << Reg);
899    if ((Mask & Bit) == 0) {
900      Mask |= Bit;
901      ++Count;
902    }
903  }
904
905  // Track the change the $sp offset: For the .save directive, the
906  // corresponding push instruction will decrease the $sp by (4 * Count).
907  // For the .vsave directive, the corresponding vpush instruction will
908  // decrease $sp by (8 * Count).
909  SPOffset -= Count * (IsVector ? 8 : 4);
910
911  // Emit the opcode
912  FlushPendingOffset();
913  if (IsVector)
914    UnwindOpAsm.EmitVFPRegSave(Mask);
915  else
916    UnwindOpAsm.EmitRegSave(Mask);
917}
918
919namespace llvm {
920
921MCStreamer *createMCAsmStreamer(MCContext &Ctx, formatted_raw_ostream &OS,
922                                bool isVerboseAsm, bool useLoc, bool useCFI,
923                                bool useDwarfDirectory,
924                                MCInstPrinter *InstPrint, MCCodeEmitter *CE,
925                                MCAsmBackend *TAB, bool ShowInst) {
926  ARMTargetAsmStreamer *S = new ARMTargetAsmStreamer(OS, *InstPrint);
927
928  return llvm::createAsmStreamer(Ctx, S, OS, isVerboseAsm, useLoc, useCFI,
929                                 useDwarfDirectory, InstPrint, CE, TAB,
930                                 ShowInst);
931}
932
933  MCELFStreamer* createARMELFStreamer(MCContext &Context, MCAsmBackend &TAB,
934                                      raw_ostream &OS, MCCodeEmitter *Emitter,
935                                      bool RelaxAll, bool NoExecStack,
936                                      bool IsThumb) {
937    ARMTargetELFStreamer *TS = new ARMTargetELFStreamer();
938    ARMELFStreamer *S =
939        new ARMELFStreamer(Context, TS, TAB, OS, Emitter, IsThumb);
940    // FIXME: This should eventually end up somewhere else where more
941    // intelligent flag decisions can be made. For now we are just maintaining
942    // the status quo for ARM and setting EF_ARM_EABI_VER5 as the default.
943    S->getAssembler().setELFHeaderEFlags(ELF::EF_ARM_EABI_VER5);
944
945    if (RelaxAll)
946      S->getAssembler().setRelaxAll(true);
947    if (NoExecStack)
948      S->getAssembler().setNoExecStack(true);
949    return S;
950  }
951
952}
953
954
955