1//===- lib/MC/MCELFStreamer.cpp - ELF Object Output -----------------------===//
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 ELF .o object files.
11//
12//===----------------------------------------------------------------------===//
13
14#include "llvm/MC/MCELFStreamer.h"
15#include "llvm/ADT/STLExtras.h"
16#include "llvm/ADT/SmallPtrSet.h"
17#include "llvm/MC/MCAsmBackend.h"
18#include "llvm/MC/MCAsmLayout.h"
19#include "llvm/MC/MCAsmInfo.h"
20#include "llvm/MC/MCAssembler.h"
21#include "llvm/MC/MCCodeEmitter.h"
22#include "llvm/MC/MCContext.h"
23#include "llvm/MC/MCExpr.h"
24#include "llvm/MC/MCInst.h"
25#include "llvm/MC/MCObjectFileInfo.h"
26#include "llvm/MC/MCObjectStreamer.h"
27#include "llvm/MC/MCSection.h"
28#include "llvm/MC/MCSectionELF.h"
29#include "llvm/MC/MCSymbolELF.h"
30#include "llvm/MC/MCSymbol.h"
31#include "llvm/MC/MCValue.h"
32#include "llvm/Support/Debug.h"
33#include "llvm/Support/ELF.h"
34#include "llvm/Support/ErrorHandling.h"
35#include "llvm/Support/TargetRegistry.h"
36#include "llvm/Support/raw_ostream.h"
37
38using namespace llvm;
39
40bool MCELFStreamer::isBundleLocked() const {
41  return getCurrentSectionOnly()->isBundleLocked();
42}
43
44MCELFStreamer::~MCELFStreamer() {
45}
46
47void MCELFStreamer::mergeFragment(MCDataFragment *DF,
48                                  MCDataFragment *EF) {
49  MCAssembler &Assembler = getAssembler();
50
51  if (Assembler.isBundlingEnabled() && Assembler.getRelaxAll()) {
52    uint64_t FSize = EF->getContents().size();
53
54    if (FSize > Assembler.getBundleAlignSize())
55      report_fatal_error("Fragment can't be larger than a bundle size");
56
57    uint64_t RequiredBundlePadding = computeBundlePadding(
58        Assembler, EF, DF->getContents().size(), FSize);
59
60    if (RequiredBundlePadding > UINT8_MAX)
61      report_fatal_error("Padding cannot exceed 255 bytes");
62
63    if (RequiredBundlePadding > 0) {
64      SmallString<256> Code;
65      raw_svector_ostream VecOS(Code);
66      MCObjectWriter *OW = Assembler.getBackend().createObjectWriter(VecOS);
67
68      EF->setBundlePadding(static_cast<uint8_t>(RequiredBundlePadding));
69
70      Assembler.writeFragmentPadding(*EF, FSize, OW);
71      delete OW;
72
73      DF->getContents().append(Code.begin(), Code.end());
74    }
75  }
76
77  flushPendingLabels(DF, DF->getContents().size());
78
79  for (unsigned i = 0, e = EF->getFixups().size(); i != e; ++i) {
80    EF->getFixups()[i].setOffset(EF->getFixups()[i].getOffset() +
81                                 DF->getContents().size());
82    DF->getFixups().push_back(EF->getFixups()[i]);
83  }
84  DF->setHasInstructions(true);
85  DF->getContents().append(EF->getContents().begin(), EF->getContents().end());
86}
87
88void MCELFStreamer::InitSections(bool NoExecStack) {
89  MCContext &Ctx = getContext();
90  SwitchSection(Ctx.getObjectFileInfo()->getTextSection());
91  EmitCodeAlignment(4);
92
93  if (NoExecStack)
94    SwitchSection(Ctx.getAsmInfo()->getNonexecutableStackSection(Ctx));
95}
96
97void MCELFStreamer::EmitLabel(MCSymbol *S) {
98  auto *Symbol = cast<MCSymbolELF>(S);
99  assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
100
101  MCObjectStreamer::EmitLabel(Symbol);
102
103  const MCSectionELF &Section =
104      static_cast<const MCSectionELF &>(*getCurrentSectionOnly());
105  if (Section.getFlags() & ELF::SHF_TLS)
106    Symbol->setType(ELF::STT_TLS);
107}
108
109void MCELFStreamer::EmitAssemblerFlag(MCAssemblerFlag Flag) {
110  // Let the target do whatever target specific stuff it needs to do.
111  getAssembler().getBackend().handleAssemblerFlag(Flag);
112  // Do any generic stuff we need to do.
113  switch (Flag) {
114  case MCAF_SyntaxUnified: return; // no-op here.
115  case MCAF_Code16: return; // Change parsing mode; no-op here.
116  case MCAF_Code32: return; // Change parsing mode; no-op here.
117  case MCAF_Code64: return; // Change parsing mode; no-op here.
118  case MCAF_SubsectionsViaSymbols:
119    getAssembler().setSubsectionsViaSymbols(true);
120    return;
121  }
122
123  llvm_unreachable("invalid assembler flag!");
124}
125
126// If bundle alignment is used and there are any instructions in the section, it
127// needs to be aligned to at least the bundle size.
128static void setSectionAlignmentForBundling(const MCAssembler &Assembler,
129                                           MCSection *Section) {
130  if (Section && Assembler.isBundlingEnabled() && Section->hasInstructions() &&
131      Section->getAlignment() < Assembler.getBundleAlignSize())
132    Section->setAlignment(Assembler.getBundleAlignSize());
133}
134
135void MCELFStreamer::ChangeSection(MCSection *Section,
136                                  const MCExpr *Subsection) {
137  MCSection *CurSection = getCurrentSectionOnly();
138  if (CurSection && isBundleLocked())
139    report_fatal_error("Unterminated .bundle_lock when changing a section");
140
141  MCAssembler &Asm = getAssembler();
142  // Ensure the previous section gets aligned if necessary.
143  setSectionAlignmentForBundling(Asm, CurSection);
144  auto *SectionELF = static_cast<const MCSectionELF *>(Section);
145  const MCSymbol *Grp = SectionELF->getGroup();
146  if (Grp)
147    Asm.registerSymbol(*Grp);
148
149  this->MCObjectStreamer::ChangeSection(Section, Subsection);
150  MCContext &Ctx = getContext();
151  auto *Begin = cast_or_null<MCSymbolELF>(Section->getBeginSymbol());
152  if (!Begin) {
153    Begin = Ctx.getOrCreateSectionSymbol(*SectionELF);
154    Section->setBeginSymbol(Begin);
155  }
156  if (Begin->isUndefined()) {
157    Asm.registerSymbol(*Begin);
158    Begin->setType(ELF::STT_SECTION);
159  }
160}
161
162void MCELFStreamer::EmitWeakReference(MCSymbol *Alias, const MCSymbol *Symbol) {
163  getAssembler().registerSymbol(*Symbol);
164  const MCExpr *Value = MCSymbolRefExpr::create(
165      Symbol, MCSymbolRefExpr::VK_WEAKREF, getContext());
166  Alias->setVariableValue(Value);
167}
168
169// When GNU as encounters more than one .type declaration for an object it seems
170// to use a mechanism similar to the one below to decide which type is actually
171// used in the object file.  The greater of T1 and T2 is selected based on the
172// following ordering:
173//  STT_NOTYPE < STT_OBJECT < STT_FUNC < STT_GNU_IFUNC < STT_TLS < anything else
174// If neither T1 < T2 nor T2 < T1 according to this ordering, use T2 (the user
175// provided type).
176static unsigned CombineSymbolTypes(unsigned T1, unsigned T2) {
177  for (unsigned Type : {ELF::STT_NOTYPE, ELF::STT_OBJECT, ELF::STT_FUNC,
178                        ELF::STT_GNU_IFUNC, ELF::STT_TLS}) {
179    if (T1 == Type)
180      return T2;
181    if (T2 == Type)
182      return T1;
183  }
184
185  return T2;
186}
187
188bool MCELFStreamer::EmitSymbolAttribute(MCSymbol *S, MCSymbolAttr Attribute) {
189  auto *Symbol = cast<MCSymbolELF>(S);
190  // Indirect symbols are handled differently, to match how 'as' handles
191  // them. This makes writing matching .o files easier.
192  if (Attribute == MCSA_IndirectSymbol) {
193    // Note that we intentionally cannot use the symbol data here; this is
194    // important for matching the string table that 'as' generates.
195    IndirectSymbolData ISD;
196    ISD.Symbol = Symbol;
197    ISD.Section = getCurrentSectionOnly();
198    getAssembler().getIndirectSymbols().push_back(ISD);
199    return true;
200  }
201
202  // Adding a symbol attribute always introduces the symbol, note that an
203  // important side effect of calling registerSymbol here is to register
204  // the symbol with the assembler.
205  getAssembler().registerSymbol(*Symbol);
206
207  // The implementation of symbol attributes is designed to match 'as', but it
208  // leaves much to desired. It doesn't really make sense to arbitrarily add and
209  // remove flags, but 'as' allows this (in particular, see .desc).
210  //
211  // In the future it might be worth trying to make these operations more well
212  // defined.
213  switch (Attribute) {
214  case MCSA_LazyReference:
215  case MCSA_Reference:
216  case MCSA_SymbolResolver:
217  case MCSA_PrivateExtern:
218  case MCSA_WeakDefinition:
219  case MCSA_WeakDefAutoPrivate:
220  case MCSA_Invalid:
221  case MCSA_IndirectSymbol:
222    return false;
223
224  case MCSA_NoDeadStrip:
225    // Ignore for now.
226    break;
227
228  case MCSA_ELF_TypeGnuUniqueObject:
229    Symbol->setType(CombineSymbolTypes(Symbol->getType(), ELF::STT_OBJECT));
230    Symbol->setBinding(ELF::STB_GNU_UNIQUE);
231    Symbol->setExternal(true);
232    break;
233
234  case MCSA_Global:
235    Symbol->setBinding(ELF::STB_GLOBAL);
236    Symbol->setExternal(true);
237    break;
238
239  case MCSA_WeakReference:
240  case MCSA_Weak:
241    Symbol->setBinding(ELF::STB_WEAK);
242    Symbol->setExternal(true);
243    break;
244
245  case MCSA_Local:
246    Symbol->setBinding(ELF::STB_LOCAL);
247    Symbol->setExternal(false);
248    break;
249
250  case MCSA_ELF_TypeFunction:
251    Symbol->setType(CombineSymbolTypes(Symbol->getType(), ELF::STT_FUNC));
252    break;
253
254  case MCSA_ELF_TypeIndFunction:
255    Symbol->setType(CombineSymbolTypes(Symbol->getType(), ELF::STT_GNU_IFUNC));
256    break;
257
258  case MCSA_ELF_TypeObject:
259    Symbol->setType(CombineSymbolTypes(Symbol->getType(), ELF::STT_OBJECT));
260    break;
261
262  case MCSA_ELF_TypeTLS:
263    Symbol->setType(CombineSymbolTypes(Symbol->getType(), ELF::STT_TLS));
264    break;
265
266  case MCSA_ELF_TypeCommon:
267    // TODO: Emit these as a common symbol.
268    Symbol->setType(CombineSymbolTypes(Symbol->getType(), ELF::STT_OBJECT));
269    break;
270
271  case MCSA_ELF_TypeNoType:
272    Symbol->setType(CombineSymbolTypes(Symbol->getType(), ELF::STT_NOTYPE));
273    break;
274
275  case MCSA_Protected:
276    Symbol->setVisibility(ELF::STV_PROTECTED);
277    break;
278
279  case MCSA_Hidden:
280    Symbol->setVisibility(ELF::STV_HIDDEN);
281    break;
282
283  case MCSA_Internal:
284    Symbol->setVisibility(ELF::STV_INTERNAL);
285    break;
286  }
287
288  return true;
289}
290
291void MCELFStreamer::EmitCommonSymbol(MCSymbol *S, uint64_t Size,
292                                     unsigned ByteAlignment) {
293  auto *Symbol = cast<MCSymbolELF>(S);
294  getAssembler().registerSymbol(*Symbol);
295
296  if (!Symbol->isBindingSet()) {
297    Symbol->setBinding(ELF::STB_GLOBAL);
298    Symbol->setExternal(true);
299  }
300
301  Symbol->setType(ELF::STT_OBJECT);
302
303  if (Symbol->getBinding() == ELF::STB_LOCAL) {
304    MCSection &Section = *getAssembler().getContext().getELFSection(
305        ".bss", ELF::SHT_NOBITS, ELF::SHF_WRITE | ELF::SHF_ALLOC);
306    MCSectionSubPair P = getCurrentSection();
307    SwitchSection(&Section);
308
309    EmitValueToAlignment(ByteAlignment, 0, 1, 0);
310    EmitLabel(Symbol);
311    EmitZeros(Size);
312
313    // Update the maximum alignment of the section if necessary.
314    if (ByteAlignment > Section.getAlignment())
315      Section.setAlignment(ByteAlignment);
316
317    SwitchSection(P.first, P.second);
318  } else {
319    if(Symbol->declareCommon(Size, ByteAlignment))
320      report_fatal_error("Symbol: " + Symbol->getName() +
321                         " redeclared as different type");
322  }
323
324  cast<MCSymbolELF>(Symbol)
325      ->setSize(MCConstantExpr::create(Size, getContext()));
326}
327
328void MCELFStreamer::emitELFSize(MCSymbolELF *Symbol, const MCExpr *Value) {
329  Symbol->setSize(Value);
330}
331
332void MCELFStreamer::EmitLocalCommonSymbol(MCSymbol *S, uint64_t Size,
333                                          unsigned ByteAlignment) {
334  auto *Symbol = cast<MCSymbolELF>(S);
335  // FIXME: Should this be caught and done earlier?
336  getAssembler().registerSymbol(*Symbol);
337  Symbol->setBinding(ELF::STB_LOCAL);
338  Symbol->setExternal(false);
339  EmitCommonSymbol(Symbol, Size, ByteAlignment);
340}
341
342void MCELFStreamer::EmitValueImpl(const MCExpr *Value, unsigned Size,
343                                  SMLoc Loc) {
344  if (isBundleLocked())
345    report_fatal_error("Emitting values inside a locked bundle is forbidden");
346  fixSymbolsInTLSFixups(Value);
347  MCObjectStreamer::EmitValueImpl(Value, Size, Loc);
348}
349
350void MCELFStreamer::EmitValueToAlignment(unsigned ByteAlignment,
351                                         int64_t Value,
352                                         unsigned ValueSize,
353                                         unsigned MaxBytesToEmit) {
354  if (isBundleLocked())
355    report_fatal_error("Emitting values inside a locked bundle is forbidden");
356  MCObjectStreamer::EmitValueToAlignment(ByteAlignment, Value,
357                                         ValueSize, MaxBytesToEmit);
358}
359
360// Add a symbol for the file name of this module. They start after the
361// null symbol and don't count as normal symbol, i.e. a non-STT_FILE symbol
362// with the same name may appear.
363void MCELFStreamer::EmitFileDirective(StringRef Filename) {
364  getAssembler().addFileName(Filename);
365}
366
367void MCELFStreamer::EmitIdent(StringRef IdentString) {
368  MCSection *Comment = getAssembler().getContext().getELFSection(
369      ".comment", ELF::SHT_PROGBITS, ELF::SHF_MERGE | ELF::SHF_STRINGS, 1, "");
370  PushSection();
371  SwitchSection(Comment);
372  if (!SeenIdent) {
373    EmitIntValue(0, 1);
374    SeenIdent = true;
375  }
376  EmitBytes(IdentString);
377  EmitIntValue(0, 1);
378  PopSection();
379}
380
381void MCELFStreamer::fixSymbolsInTLSFixups(const MCExpr *expr) {
382  switch (expr->getKind()) {
383  case MCExpr::Target:
384    cast<MCTargetExpr>(expr)->fixELFSymbolsInTLSFixups(getAssembler());
385    break;
386  case MCExpr::Constant:
387    break;
388
389  case MCExpr::Binary: {
390    const MCBinaryExpr *be = cast<MCBinaryExpr>(expr);
391    fixSymbolsInTLSFixups(be->getLHS());
392    fixSymbolsInTLSFixups(be->getRHS());
393    break;
394  }
395
396  case MCExpr::SymbolRef: {
397    const MCSymbolRefExpr &symRef = *cast<MCSymbolRefExpr>(expr);
398    switch (symRef.getKind()) {
399    default:
400      return;
401    case MCSymbolRefExpr::VK_GOTTPOFF:
402    case MCSymbolRefExpr::VK_INDNTPOFF:
403    case MCSymbolRefExpr::VK_NTPOFF:
404    case MCSymbolRefExpr::VK_GOTNTPOFF:
405    case MCSymbolRefExpr::VK_TLSGD:
406    case MCSymbolRefExpr::VK_TLSLD:
407    case MCSymbolRefExpr::VK_TLSLDM:
408    case MCSymbolRefExpr::VK_TPOFF:
409    case MCSymbolRefExpr::VK_DTPOFF:
410    case MCSymbolRefExpr::VK_Mips_TLSGD:
411    case MCSymbolRefExpr::VK_Mips_GOTTPREL:
412    case MCSymbolRefExpr::VK_Mips_TPREL_HI:
413    case MCSymbolRefExpr::VK_Mips_TPREL_LO:
414    case MCSymbolRefExpr::VK_PPC_DTPMOD:
415    case MCSymbolRefExpr::VK_PPC_TPREL:
416    case MCSymbolRefExpr::VK_PPC_TPREL_LO:
417    case MCSymbolRefExpr::VK_PPC_TPREL_HI:
418    case MCSymbolRefExpr::VK_PPC_TPREL_HA:
419    case MCSymbolRefExpr::VK_PPC_TPREL_HIGHER:
420    case MCSymbolRefExpr::VK_PPC_TPREL_HIGHERA:
421    case MCSymbolRefExpr::VK_PPC_TPREL_HIGHEST:
422    case MCSymbolRefExpr::VK_PPC_TPREL_HIGHESTA:
423    case MCSymbolRefExpr::VK_PPC_DTPREL:
424    case MCSymbolRefExpr::VK_PPC_DTPREL_LO:
425    case MCSymbolRefExpr::VK_PPC_DTPREL_HI:
426    case MCSymbolRefExpr::VK_PPC_DTPREL_HA:
427    case MCSymbolRefExpr::VK_PPC_DTPREL_HIGHER:
428    case MCSymbolRefExpr::VK_PPC_DTPREL_HIGHERA:
429    case MCSymbolRefExpr::VK_PPC_DTPREL_HIGHEST:
430    case MCSymbolRefExpr::VK_PPC_DTPREL_HIGHESTA:
431    case MCSymbolRefExpr::VK_PPC_GOT_TPREL:
432    case MCSymbolRefExpr::VK_PPC_GOT_TPREL_LO:
433    case MCSymbolRefExpr::VK_PPC_GOT_TPREL_HI:
434    case MCSymbolRefExpr::VK_PPC_GOT_TPREL_HA:
435    case MCSymbolRefExpr::VK_PPC_GOT_DTPREL:
436    case MCSymbolRefExpr::VK_PPC_GOT_DTPREL_LO:
437    case MCSymbolRefExpr::VK_PPC_GOT_DTPREL_HI:
438    case MCSymbolRefExpr::VK_PPC_GOT_DTPREL_HA:
439    case MCSymbolRefExpr::VK_PPC_TLS:
440    case MCSymbolRefExpr::VK_PPC_GOT_TLSGD:
441    case MCSymbolRefExpr::VK_PPC_GOT_TLSGD_LO:
442    case MCSymbolRefExpr::VK_PPC_GOT_TLSGD_HI:
443    case MCSymbolRefExpr::VK_PPC_GOT_TLSGD_HA:
444    case MCSymbolRefExpr::VK_PPC_TLSGD:
445    case MCSymbolRefExpr::VK_PPC_GOT_TLSLD:
446    case MCSymbolRefExpr::VK_PPC_GOT_TLSLD_LO:
447    case MCSymbolRefExpr::VK_PPC_GOT_TLSLD_HI:
448    case MCSymbolRefExpr::VK_PPC_GOT_TLSLD_HA:
449    case MCSymbolRefExpr::VK_PPC_TLSLD:
450      break;
451    }
452    getAssembler().registerSymbol(symRef.getSymbol());
453    cast<MCSymbolELF>(symRef.getSymbol()).setType(ELF::STT_TLS);
454    break;
455  }
456
457  case MCExpr::Unary:
458    fixSymbolsInTLSFixups(cast<MCUnaryExpr>(expr)->getSubExpr());
459    break;
460  }
461}
462
463void MCELFStreamer::EmitInstToFragment(const MCInst &Inst,
464                                       const MCSubtargetInfo &STI) {
465  this->MCObjectStreamer::EmitInstToFragment(Inst, STI);
466  MCRelaxableFragment &F = *cast<MCRelaxableFragment>(getCurrentFragment());
467
468  for (unsigned i = 0, e = F.getFixups().size(); i != e; ++i)
469    fixSymbolsInTLSFixups(F.getFixups()[i].getValue());
470}
471
472void MCELFStreamer::EmitInstToData(const MCInst &Inst,
473                                   const MCSubtargetInfo &STI) {
474  MCAssembler &Assembler = getAssembler();
475  SmallVector<MCFixup, 4> Fixups;
476  SmallString<256> Code;
477  raw_svector_ostream VecOS(Code);
478  Assembler.getEmitter().encodeInstruction(Inst, VecOS, Fixups, STI);
479
480  for (unsigned i = 0, e = Fixups.size(); i != e; ++i)
481    fixSymbolsInTLSFixups(Fixups[i].getValue());
482
483  // There are several possibilities here:
484  //
485  // If bundling is disabled, append the encoded instruction to the current data
486  // fragment (or create a new such fragment if the current fragment is not a
487  // data fragment).
488  //
489  // If bundling is enabled:
490  // - If we're not in a bundle-locked group, emit the instruction into a
491  //   fragment of its own. If there are no fixups registered for the
492  //   instruction, emit a MCCompactEncodedInstFragment. Otherwise, emit a
493  //   MCDataFragment.
494  // - If we're in a bundle-locked group, append the instruction to the current
495  //   data fragment because we want all the instructions in a group to get into
496  //   the same fragment. Be careful not to do that for the first instruction in
497  //   the group, though.
498  MCDataFragment *DF;
499
500  if (Assembler.isBundlingEnabled()) {
501    MCSection &Sec = *getCurrentSectionOnly();
502    if (Assembler.getRelaxAll() && isBundleLocked())
503      // If the -mc-relax-all flag is used and we are bundle-locked, we re-use
504      // the current bundle group.
505      DF = BundleGroups.back();
506    else if (Assembler.getRelaxAll() && !isBundleLocked())
507      // When not in a bundle-locked group and the -mc-relax-all flag is used,
508      // we create a new temporary fragment which will be later merged into
509      // the current fragment.
510      DF = new MCDataFragment();
511    else if (isBundleLocked() && !Sec.isBundleGroupBeforeFirstInst())
512      // If we are bundle-locked, we re-use the current fragment.
513      // The bundle-locking directive ensures this is a new data fragment.
514      DF = cast<MCDataFragment>(getCurrentFragment());
515    else if (!isBundleLocked() && Fixups.size() == 0) {
516      // Optimize memory usage by emitting the instruction to a
517      // MCCompactEncodedInstFragment when not in a bundle-locked group and
518      // there are no fixups registered.
519      MCCompactEncodedInstFragment *CEIF = new MCCompactEncodedInstFragment();
520      insert(CEIF);
521      CEIF->getContents().append(Code.begin(), Code.end());
522      return;
523    } else {
524      DF = new MCDataFragment();
525      insert(DF);
526    }
527    if (Sec.getBundleLockState() == MCSection::BundleLockedAlignToEnd) {
528      // If this fragment is for a group marked "align_to_end", set a flag
529      // in the fragment. This can happen after the fragment has already been
530      // created if there are nested bundle_align groups and an inner one
531      // is the one marked align_to_end.
532      DF->setAlignToBundleEnd(true);
533    }
534
535    // We're now emitting an instruction in a bundle group, so this flag has
536    // to be turned off.
537    Sec.setBundleGroupBeforeFirstInst(false);
538  } else {
539    DF = getOrCreateDataFragment();
540  }
541
542  // Add the fixups and data.
543  for (unsigned i = 0, e = Fixups.size(); i != e; ++i) {
544    Fixups[i].setOffset(Fixups[i].getOffset() + DF->getContents().size());
545    DF->getFixups().push_back(Fixups[i]);
546  }
547  DF->setHasInstructions(true);
548  DF->getContents().append(Code.begin(), Code.end());
549
550  if (Assembler.isBundlingEnabled() && Assembler.getRelaxAll()) {
551    if (!isBundleLocked()) {
552      mergeFragment(getOrCreateDataFragment(), DF);
553      delete DF;
554    }
555  }
556}
557
558void MCELFStreamer::EmitBundleAlignMode(unsigned AlignPow2) {
559  assert(AlignPow2 <= 30 && "Invalid bundle alignment");
560  MCAssembler &Assembler = getAssembler();
561  if (AlignPow2 > 0 && (Assembler.getBundleAlignSize() == 0 ||
562                        Assembler.getBundleAlignSize() == 1U << AlignPow2))
563    Assembler.setBundleAlignSize(1U << AlignPow2);
564  else
565    report_fatal_error(".bundle_align_mode cannot be changed once set");
566}
567
568void MCELFStreamer::EmitBundleLock(bool AlignToEnd) {
569  MCSection &Sec = *getCurrentSectionOnly();
570
571  // Sanity checks
572  //
573  if (!getAssembler().isBundlingEnabled())
574    report_fatal_error(".bundle_lock forbidden when bundling is disabled");
575
576  if (!isBundleLocked())
577    Sec.setBundleGroupBeforeFirstInst(true);
578
579  if (getAssembler().getRelaxAll() && !isBundleLocked()) {
580    // TODO: drop the lock state and set directly in the fragment
581    MCDataFragment *DF = new MCDataFragment();
582    BundleGroups.push_back(DF);
583  }
584
585  Sec.setBundleLockState(AlignToEnd ? MCSection::BundleLockedAlignToEnd
586                                    : MCSection::BundleLocked);
587}
588
589void MCELFStreamer::EmitBundleUnlock() {
590  MCSection &Sec = *getCurrentSectionOnly();
591
592  // Sanity checks
593  if (!getAssembler().isBundlingEnabled())
594    report_fatal_error(".bundle_unlock forbidden when bundling is disabled");
595  else if (!isBundleLocked())
596    report_fatal_error(".bundle_unlock without matching lock");
597  else if (Sec.isBundleGroupBeforeFirstInst())
598    report_fatal_error("Empty bundle-locked group is forbidden");
599
600  // When the -mc-relax-all flag is used, we emit instructions to fragments
601  // stored on a stack. When the bundle unlock is emitted, we pop a fragment
602  // from the stack a merge it to the one below.
603  if (getAssembler().getRelaxAll()) {
604    assert(!BundleGroups.empty() && "There are no bundle groups");
605    MCDataFragment *DF = BundleGroups.back();
606
607    // FIXME: Use BundleGroups to track the lock state instead.
608    Sec.setBundleLockState(MCSection::NotBundleLocked);
609
610    // FIXME: Use more separate fragments for nested groups.
611    if (!isBundleLocked()) {
612      mergeFragment(getOrCreateDataFragment(), DF);
613      BundleGroups.pop_back();
614      delete DF;
615    }
616
617    if (Sec.getBundleLockState() != MCSection::BundleLockedAlignToEnd)
618      getOrCreateDataFragment()->setAlignToBundleEnd(false);
619  } else
620    Sec.setBundleLockState(MCSection::NotBundleLocked);
621}
622
623void MCELFStreamer::FinishImpl() {
624  // Ensure the last section gets aligned if necessary.
625  MCSection *CurSection = getCurrentSectionOnly();
626  setSectionAlignmentForBundling(getAssembler(), CurSection);
627
628  EmitFrames(nullptr);
629
630  this->MCObjectStreamer::FinishImpl();
631}
632
633MCStreamer *llvm::createELFStreamer(MCContext &Context, MCAsmBackend &MAB,
634                                    raw_pwrite_stream &OS, MCCodeEmitter *CE,
635                                    bool RelaxAll) {
636  MCELFStreamer *S = new MCELFStreamer(Context, MAB, OS, CE);
637  if (RelaxAll)
638    S->getAssembler().setRelaxAll(true);
639  return S;
640}
641
642void MCELFStreamer::EmitThumbFunc(MCSymbol *Func) {
643  llvm_unreachable("Generic ELF doesn't support this directive");
644}
645
646void MCELFStreamer::EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {
647  llvm_unreachable("ELF doesn't support this directive");
648}
649
650void MCELFStreamer::BeginCOFFSymbolDef(const MCSymbol *Symbol) {
651  llvm_unreachable("ELF doesn't support this directive");
652}
653
654void MCELFStreamer::EmitCOFFSymbolStorageClass(int StorageClass) {
655  llvm_unreachable("ELF doesn't support this directive");
656}
657
658void MCELFStreamer::EmitCOFFSymbolType(int Type) {
659  llvm_unreachable("ELF doesn't support this directive");
660}
661
662void MCELFStreamer::EndCOFFSymbolDef() {
663  llvm_unreachable("ELF doesn't support this directive");
664}
665
666void MCELFStreamer::EmitZerofill(MCSection *Section, MCSymbol *Symbol,
667                                 uint64_t Size, unsigned ByteAlignment) {
668  llvm_unreachable("ELF doesn't support this directive");
669}
670
671void MCELFStreamer::EmitTBSSSymbol(MCSection *Section, MCSymbol *Symbol,
672                                   uint64_t Size, unsigned ByteAlignment) {
673  llvm_unreachable("ELF doesn't support this directive");
674}
675