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1 //===- lib/MC/MCAssembler.cpp - Assembler Backend Implementation ----------===//
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 #define DEBUG_TYPE "assembler"
11 #include "llvm/MC/MCAssembler.h"
12 #include "llvm/ADT/Statistic.h"
13 #include "llvm/ADT/StringExtras.h"
14 #include "llvm/ADT/Twine.h"
15 #include "llvm/MC/MCAsmBackend.h"
16 #include "llvm/MC/MCAsmLayout.h"
17 #include "llvm/MC/MCCodeEmitter.h"
18 #include "llvm/MC/MCContext.h"
19 #include "llvm/MC/MCDwarf.h"
20 #include "llvm/MC/MCExpr.h"
21 #include "llvm/MC/MCFixupKindInfo.h"
22 #include "llvm/MC/MCObjectWriter.h"
23 #include "llvm/MC/MCSection.h"
24 #include "llvm/MC/MCSymbol.h"
25 #include "llvm/MC/MCValue.h"
26 #include "llvm/Support/Debug.h"
27 #include "llvm/Support/ErrorHandling.h"
28 #include "llvm/Support/LEB128.h"
29 #include "llvm/Support/TargetRegistry.h"
30 #include "llvm/Support/raw_ostream.h"
31 
32 using namespace llvm;
33 
34 namespace {
35 namespace stats {
36 STATISTIC(EmittedFragments, "Number of emitted assembler fragments - total");
37 STATISTIC(EmittedRelaxableFragments,
38           "Number of emitted assembler fragments - relaxable");
39 STATISTIC(EmittedDataFragments,
40           "Number of emitted assembler fragments - data");
41 STATISTIC(EmittedCompactEncodedInstFragments,
42           "Number of emitted assembler fragments - compact encoded inst");
43 STATISTIC(EmittedAlignFragments,
44           "Number of emitted assembler fragments - align");
45 STATISTIC(EmittedFillFragments,
46           "Number of emitted assembler fragments - fill");
47 STATISTIC(EmittedOrgFragments,
48           "Number of emitted assembler fragments - org");
49 STATISTIC(evaluateFixup, "Number of evaluated fixups");
50 STATISTIC(FragmentLayouts, "Number of fragment layouts");
51 STATISTIC(ObjectBytes, "Number of emitted object file bytes");
52 STATISTIC(RelaxationSteps, "Number of assembler layout and relaxation steps");
53 STATISTIC(RelaxedInstructions, "Number of relaxed instructions");
54 }
55 }
56 
57 // FIXME FIXME FIXME: There are number of places in this file where we convert
58 // what is a 64-bit assembler value used for computation into a value in the
59 // object file, which may truncate it. We should detect that truncation where
60 // invalid and report errors back.
61 
62 /* *** */
63 
MCAsmLayout(MCAssembler & Asm)64 MCAsmLayout::MCAsmLayout(MCAssembler &Asm)
65   : Assembler(Asm), LastValidFragment()
66  {
67   // Compute the section layout order. Virtual sections must go last.
68   for (MCAssembler::iterator it = Asm.begin(), ie = Asm.end(); it != ie; ++it)
69     if (!it->getSection().isVirtualSection())
70       SectionOrder.push_back(&*it);
71   for (MCAssembler::iterator it = Asm.begin(), ie = Asm.end(); it != ie; ++it)
72     if (it->getSection().isVirtualSection())
73       SectionOrder.push_back(&*it);
74 }
75 
isFragmentValid(const MCFragment * F) const76 bool MCAsmLayout::isFragmentValid(const MCFragment *F) const {
77   const MCSectionData &SD = *F->getParent();
78   const MCFragment *LastValid = LastValidFragment.lookup(&SD);
79   if (!LastValid)
80     return false;
81   assert(LastValid->getParent() == F->getParent());
82   return F->getLayoutOrder() <= LastValid->getLayoutOrder();
83 }
84 
invalidateFragmentsFrom(MCFragment * F)85 void MCAsmLayout::invalidateFragmentsFrom(MCFragment *F) {
86   // If this fragment wasn't already valid, we don't need to do anything.
87   if (!isFragmentValid(F))
88     return;
89 
90   // Otherwise, reset the last valid fragment to the previous fragment
91   // (if this is the first fragment, it will be NULL).
92   const MCSectionData &SD = *F->getParent();
93   LastValidFragment[&SD] = F->getPrevNode();
94 }
95 
ensureValid(const MCFragment * F) const96 void MCAsmLayout::ensureValid(const MCFragment *F) const {
97   MCSectionData &SD = *F->getParent();
98 
99   MCFragment *Cur = LastValidFragment[&SD];
100   if (!Cur)
101     Cur = &*SD.begin();
102   else
103     Cur = Cur->getNextNode();
104 
105   // Advance the layout position until the fragment is valid.
106   while (!isFragmentValid(F)) {
107     assert(Cur && "Layout bookkeeping error");
108     const_cast<MCAsmLayout*>(this)->layoutFragment(Cur);
109     Cur = Cur->getNextNode();
110   }
111 }
112 
getFragmentOffset(const MCFragment * F) const113 uint64_t MCAsmLayout::getFragmentOffset(const MCFragment *F) const {
114   ensureValid(F);
115   assert(F->Offset != ~UINT64_C(0) && "Address not set!");
116   return F->Offset;
117 }
118 
getSymbolOffset(const MCSymbolData * SD) const119 uint64_t MCAsmLayout::getSymbolOffset(const MCSymbolData *SD) const {
120   const MCSymbol &S = SD->getSymbol();
121 
122   // If this is a variable, then recursively evaluate now.
123   if (S.isVariable()) {
124     MCValue Target;
125     if (!S.getVariableValue()->EvaluateAsRelocatable(Target, *this))
126       report_fatal_error("unable to evaluate offset for variable '" +
127                          S.getName() + "'");
128 
129     // Verify that any used symbols are defined.
130     if (Target.getSymA() && Target.getSymA()->getSymbol().isUndefined())
131       report_fatal_error("unable to evaluate offset to undefined symbol '" +
132                          Target.getSymA()->getSymbol().getName() + "'");
133     if (Target.getSymB() && Target.getSymB()->getSymbol().isUndefined())
134       report_fatal_error("unable to evaluate offset to undefined symbol '" +
135                          Target.getSymB()->getSymbol().getName() + "'");
136 
137     uint64_t Offset = Target.getConstant();
138     if (Target.getSymA())
139       Offset += getSymbolOffset(&Assembler.getSymbolData(
140                                   Target.getSymA()->getSymbol()));
141     if (Target.getSymB())
142       Offset -= getSymbolOffset(&Assembler.getSymbolData(
143                                   Target.getSymB()->getSymbol()));
144     return Offset;
145   }
146 
147   assert(SD->getFragment() && "Invalid getOffset() on undefined symbol!");
148   return getFragmentOffset(SD->getFragment()) + SD->getOffset();
149 }
150 
getSectionAddressSize(const MCSectionData * SD) const151 uint64_t MCAsmLayout::getSectionAddressSize(const MCSectionData *SD) const {
152   // The size is the last fragment's end offset.
153   const MCFragment &F = SD->getFragmentList().back();
154   return getFragmentOffset(&F) + getAssembler().computeFragmentSize(*this, F);
155 }
156 
getSectionFileSize(const MCSectionData * SD) const157 uint64_t MCAsmLayout::getSectionFileSize(const MCSectionData *SD) const {
158   // Virtual sections have no file size.
159   if (SD->getSection().isVirtualSection())
160     return 0;
161 
162   // Otherwise, the file size is the same as the address space size.
163   return getSectionAddressSize(SD);
164 }
165 
computeBundlePadding(const MCFragment * F,uint64_t FOffset,uint64_t FSize)166 uint64_t MCAsmLayout::computeBundlePadding(const MCFragment *F,
167                                            uint64_t FOffset, uint64_t FSize) {
168   uint64_t BundleSize = Assembler.getBundleAlignSize();
169   assert(BundleSize > 0 &&
170          "computeBundlePadding should only be called if bundling is enabled");
171   uint64_t BundleMask = BundleSize - 1;
172   uint64_t OffsetInBundle = FOffset & BundleMask;
173   uint64_t EndOfFragment = OffsetInBundle + FSize;
174 
175   // There are two kinds of bundling restrictions:
176   //
177   // 1) For alignToBundleEnd(), add padding to ensure that the fragment will
178   //    *end* on a bundle boundary.
179   // 2) Otherwise, check if the fragment would cross a bundle boundary. If it
180   //    would, add padding until the end of the bundle so that the fragment
181   //    will start in a new one.
182   if (F->alignToBundleEnd()) {
183     // Three possibilities here:
184     //
185     // A) The fragment just happens to end at a bundle boundary, so we're good.
186     // B) The fragment ends before the current bundle boundary: pad it just
187     //    enough to reach the boundary.
188     // C) The fragment ends after the current bundle boundary: pad it until it
189     //    reaches the end of the next bundle boundary.
190     //
191     // Note: this code could be made shorter with some modulo trickery, but it's
192     // intentionally kept in its more explicit form for simplicity.
193     if (EndOfFragment == BundleSize)
194       return 0;
195     else if (EndOfFragment < BundleSize)
196       return BundleSize - EndOfFragment;
197     else { // EndOfFragment > BundleSize
198       return 2 * BundleSize - EndOfFragment;
199     }
200   } else if (EndOfFragment > BundleSize)
201     return BundleSize - OffsetInBundle;
202   else
203     return 0;
204 }
205 
206 /* *** */
207 
MCFragment()208 MCFragment::MCFragment() : Kind(FragmentType(~0)) {
209 }
210 
~MCFragment()211 MCFragment::~MCFragment() {
212 }
213 
MCFragment(FragmentType _Kind,MCSectionData * _Parent)214 MCFragment::MCFragment(FragmentType _Kind, MCSectionData *_Parent)
215   : Kind(_Kind), Parent(_Parent), Atom(0), Offset(~UINT64_C(0)),
216     LayoutOrder(~(0U))
217 {
218   if (Parent)
219     Parent->getFragmentList().push_back(this);
220 }
221 
222 /* *** */
223 
~MCEncodedFragment()224 MCEncodedFragment::~MCEncodedFragment() {
225 }
226 
227 /* *** */
228 
~MCEncodedFragmentWithFixups()229 MCEncodedFragmentWithFixups::~MCEncodedFragmentWithFixups() {
230 }
231 
232 /* *** */
233 
MCSectionData()234 MCSectionData::MCSectionData() : Section(0) {}
235 
MCSectionData(const MCSection & _Section,MCAssembler * A)236 MCSectionData::MCSectionData(const MCSection &_Section, MCAssembler *A)
237   : Section(&_Section),
238     Ordinal(~UINT32_C(0)),
239     Alignment(1),
240     BundleLockState(NotBundleLocked), BundleGroupBeforeFirstInst(false),
241     HasInstructions(false)
242 {
243   if (A)
244     A->getSectionList().push_back(this);
245 }
246 
247 MCSectionData::iterator
getSubsectionInsertionPoint(unsigned Subsection)248 MCSectionData::getSubsectionInsertionPoint(unsigned Subsection) {
249   if (Subsection == 0 && SubsectionFragmentMap.empty())
250     return end();
251 
252   SmallVectorImpl<std::pair<unsigned, MCFragment *> >::iterator MI =
253     std::lower_bound(SubsectionFragmentMap.begin(), SubsectionFragmentMap.end(),
254                      std::make_pair(Subsection, (MCFragment *)0));
255   bool ExactMatch = false;
256   if (MI != SubsectionFragmentMap.end()) {
257     ExactMatch = MI->first == Subsection;
258     if (ExactMatch)
259       ++MI;
260   }
261   iterator IP;
262   if (MI == SubsectionFragmentMap.end())
263     IP = end();
264   else
265     IP = MI->second;
266   if (!ExactMatch && Subsection != 0) {
267     // The GNU as documentation claims that subsections have an alignment of 4,
268     // although this appears not to be the case.
269     MCFragment *F = new MCDataFragment();
270     SubsectionFragmentMap.insert(MI, std::make_pair(Subsection, F));
271     getFragmentList().insert(IP, F);
272     F->setParent(this);
273   }
274   return IP;
275 }
276 
277 /* *** */
278 
MCSymbolData()279 MCSymbolData::MCSymbolData() : Symbol(0) {}
280 
MCSymbolData(const MCSymbol & _Symbol,MCFragment * _Fragment,uint64_t _Offset,MCAssembler * A)281 MCSymbolData::MCSymbolData(const MCSymbol &_Symbol, MCFragment *_Fragment,
282                            uint64_t _Offset, MCAssembler *A)
283   : Symbol(&_Symbol), Fragment(_Fragment), Offset(_Offset),
284     IsExternal(false), IsPrivateExtern(false),
285     CommonSize(0), SymbolSize(0), CommonAlign(0),
286     Flags(0), Index(0)
287 {
288   if (A)
289     A->getSymbolList().push_back(this);
290 }
291 
292 /* *** */
293 
MCAssembler(MCContext & Context_,MCAsmBackend & Backend_,MCCodeEmitter & Emitter_,MCObjectWriter & Writer_,raw_ostream & OS_)294 MCAssembler::MCAssembler(MCContext &Context_, MCAsmBackend &Backend_,
295                          MCCodeEmitter &Emitter_, MCObjectWriter &Writer_,
296                          raw_ostream &OS_)
297   : Context(Context_), Backend(Backend_), Emitter(Emitter_), Writer(&Writer_),
298     OS(OS_), BundleAlignSize(0), RelaxAll(false), NoExecStack(false),
299     SubsectionsViaSymbols(false), ELFHeaderEFlags(0) {
300 }
301 
~MCAssembler()302 MCAssembler::~MCAssembler() {
303 }
304 
setWriter(MCObjectWriter & ObjectWriter)305 void MCAssembler::setWriter(MCObjectWriter &ObjectWriter) {
306   delete Writer;
307   Writer = &ObjectWriter;
308 }
309 
reset()310 void MCAssembler::reset() {
311   Sections.clear();
312   Symbols.clear();
313   SectionMap.clear();
314   SymbolMap.clear();
315   IndirectSymbols.clear();
316   DataRegions.clear();
317   ThumbFuncs.clear();
318   RelaxAll = false;
319   NoExecStack = false;
320   SubsectionsViaSymbols = false;
321   ELFHeaderEFlags = 0;
322 
323   // reset objects owned by us
324   getBackend().reset();
325   getEmitter().reset();
326   getWriter().reset();
327 }
328 
isSymbolLinkerVisible(const MCSymbol & Symbol) const329 bool MCAssembler::isSymbolLinkerVisible(const MCSymbol &Symbol) const {
330   // Non-temporary labels should always be visible to the linker.
331   if (!Symbol.isTemporary())
332     return true;
333 
334   // Absolute temporary labels are never visible.
335   if (!Symbol.isInSection())
336     return false;
337 
338   // Otherwise, check if the section requires symbols even for temporary labels.
339   return getBackend().doesSectionRequireSymbols(Symbol.getSection());
340 }
341 
getAtom(const MCSymbolData * SD) const342 const MCSymbolData *MCAssembler::getAtom(const MCSymbolData *SD) const {
343   // Linker visible symbols define atoms.
344   if (isSymbolLinkerVisible(SD->getSymbol()))
345     return SD;
346 
347   // Absolute and undefined symbols have no defining atom.
348   if (!SD->getFragment())
349     return 0;
350 
351   // Non-linker visible symbols in sections which can't be atomized have no
352   // defining atom.
353   if (!getBackend().isSectionAtomizable(
354         SD->getFragment()->getParent()->getSection()))
355     return 0;
356 
357   // Otherwise, return the atom for the containing fragment.
358   return SD->getFragment()->getAtom();
359 }
360 
evaluateFixup(const MCAsmLayout & Layout,const MCFixup & Fixup,const MCFragment * DF,MCValue & Target,uint64_t & Value) const361 bool MCAssembler::evaluateFixup(const MCAsmLayout &Layout,
362                                 const MCFixup &Fixup, const MCFragment *DF,
363                                 MCValue &Target, uint64_t &Value) const {
364   ++stats::evaluateFixup;
365 
366   if (!Fixup.getValue()->EvaluateAsRelocatable(Target, Layout))
367     getContext().FatalError(Fixup.getLoc(), "expected relocatable expression");
368 
369   bool IsPCRel = Backend.getFixupKindInfo(
370     Fixup.getKind()).Flags & MCFixupKindInfo::FKF_IsPCRel;
371 
372   bool IsResolved;
373   if (IsPCRel) {
374     if (Target.getSymB()) {
375       IsResolved = false;
376     } else if (!Target.getSymA()) {
377       IsResolved = false;
378     } else {
379       const MCSymbolRefExpr *A = Target.getSymA();
380       const MCSymbol &SA = A->getSymbol();
381       if (A->getKind() != MCSymbolRefExpr::VK_None ||
382           SA.AliasedSymbol().isUndefined()) {
383         IsResolved = false;
384       } else {
385         const MCSymbolData &DataA = getSymbolData(SA);
386         IsResolved =
387           getWriter().IsSymbolRefDifferenceFullyResolvedImpl(*this, DataA,
388                                                              *DF, false, true);
389       }
390     }
391   } else {
392     IsResolved = Target.isAbsolute();
393   }
394 
395   Value = Target.getConstant();
396 
397   if (const MCSymbolRefExpr *A = Target.getSymA()) {
398     const MCSymbol &Sym = A->getSymbol().AliasedSymbol();
399     if (Sym.isDefined())
400       Value += Layout.getSymbolOffset(&getSymbolData(Sym));
401   }
402   if (const MCSymbolRefExpr *B = Target.getSymB()) {
403     const MCSymbol &Sym = B->getSymbol().AliasedSymbol();
404     if (Sym.isDefined())
405       Value -= Layout.getSymbolOffset(&getSymbolData(Sym));
406   }
407 
408 
409   bool ShouldAlignPC = Backend.getFixupKindInfo(Fixup.getKind()).Flags &
410                          MCFixupKindInfo::FKF_IsAlignedDownTo32Bits;
411   assert((ShouldAlignPC ? IsPCRel : true) &&
412     "FKF_IsAlignedDownTo32Bits is only allowed on PC-relative fixups!");
413 
414   if (IsPCRel) {
415     uint32_t Offset = Layout.getFragmentOffset(DF) + Fixup.getOffset();
416 
417     // A number of ARM fixups in Thumb mode require that the effective PC
418     // address be determined as the 32-bit aligned version of the actual offset.
419     if (ShouldAlignPC) Offset &= ~0x3;
420     Value -= Offset;
421   }
422 
423   // Let the backend adjust the fixup value if necessary, including whether
424   // we need a relocation.
425   Backend.processFixupValue(*this, Layout, Fixup, DF, Target, Value,
426                             IsResolved);
427 
428   return IsResolved;
429 }
430 
computeFragmentSize(const MCAsmLayout & Layout,const MCFragment & F) const431 uint64_t MCAssembler::computeFragmentSize(const MCAsmLayout &Layout,
432                                           const MCFragment &F) const {
433   switch (F.getKind()) {
434   case MCFragment::FT_Data:
435   case MCFragment::FT_Relaxable:
436   case MCFragment::FT_CompactEncodedInst:
437     return cast<MCEncodedFragment>(F).getContents().size();
438   case MCFragment::FT_Fill:
439     return cast<MCFillFragment>(F).getSize();
440 
441   case MCFragment::FT_LEB:
442     return cast<MCLEBFragment>(F).getContents().size();
443 
444   case MCFragment::FT_Align: {
445     const MCAlignFragment &AF = cast<MCAlignFragment>(F);
446     unsigned Offset = Layout.getFragmentOffset(&AF);
447     unsigned Size = OffsetToAlignment(Offset, AF.getAlignment());
448     // If we are padding with nops, force the padding to be larger than the
449     // minimum nop size.
450     if (Size > 0 && AF.hasEmitNops()) {
451       while (Size % getBackend().getMinimumNopSize())
452         Size += AF.getAlignment();
453     }
454     if (Size > AF.getMaxBytesToEmit())
455       return 0;
456     return Size;
457   }
458 
459   case MCFragment::FT_Org: {
460     const MCOrgFragment &OF = cast<MCOrgFragment>(F);
461     int64_t TargetLocation;
462     if (!OF.getOffset().EvaluateAsAbsolute(TargetLocation, Layout))
463       report_fatal_error("expected assembly-time absolute expression");
464 
465     // FIXME: We need a way to communicate this error.
466     uint64_t FragmentOffset = Layout.getFragmentOffset(&OF);
467     int64_t Size = TargetLocation - FragmentOffset;
468     if (Size < 0 || Size >= 0x40000000)
469       report_fatal_error("invalid .org offset '" + Twine(TargetLocation) +
470                          "' (at offset '" + Twine(FragmentOffset) + "')");
471     return Size;
472   }
473 
474   case MCFragment::FT_Dwarf:
475     return cast<MCDwarfLineAddrFragment>(F).getContents().size();
476   case MCFragment::FT_DwarfFrame:
477     return cast<MCDwarfCallFrameFragment>(F).getContents().size();
478   }
479 
480   llvm_unreachable("invalid fragment kind");
481 }
482 
layoutFragment(MCFragment * F)483 void MCAsmLayout::layoutFragment(MCFragment *F) {
484   MCFragment *Prev = F->getPrevNode();
485 
486   // We should never try to recompute something which is valid.
487   assert(!isFragmentValid(F) && "Attempt to recompute a valid fragment!");
488   // We should never try to compute the fragment layout if its predecessor
489   // isn't valid.
490   assert((!Prev || isFragmentValid(Prev)) &&
491          "Attempt to compute fragment before its predecessor!");
492 
493   ++stats::FragmentLayouts;
494 
495   // Compute fragment offset and size.
496   if (Prev)
497     F->Offset = Prev->Offset + getAssembler().computeFragmentSize(*this, *Prev);
498   else
499     F->Offset = 0;
500   LastValidFragment[F->getParent()] = F;
501 
502   // If bundling is enabled and this fragment has instructions in it, it has to
503   // obey the bundling restrictions. With padding, we'll have:
504   //
505   //
506   //        BundlePadding
507   //             |||
508   // -------------------------------------
509   //   Prev  |##########|       F        |
510   // -------------------------------------
511   //                    ^
512   //                    |
513   //                    F->Offset
514   //
515   // The fragment's offset will point to after the padding, and its computed
516   // size won't include the padding.
517   //
518   if (Assembler.isBundlingEnabled() && F->hasInstructions()) {
519     assert(isa<MCEncodedFragment>(F) &&
520            "Only MCEncodedFragment implementations have instructions");
521     uint64_t FSize = Assembler.computeFragmentSize(*this, *F);
522 
523     if (FSize > Assembler.getBundleAlignSize())
524       report_fatal_error("Fragment can't be larger than a bundle size");
525 
526     uint64_t RequiredBundlePadding = computeBundlePadding(F, F->Offset, FSize);
527     if (RequiredBundlePadding > UINT8_MAX)
528       report_fatal_error("Padding cannot exceed 255 bytes");
529     F->setBundlePadding(static_cast<uint8_t>(RequiredBundlePadding));
530     F->Offset += RequiredBundlePadding;
531   }
532 }
533 
534 /// \brief Write the contents of a fragment to the given object writer. Expects
535 ///        a MCEncodedFragment.
writeFragmentContents(const MCFragment & F,MCObjectWriter * OW)536 static void writeFragmentContents(const MCFragment &F, MCObjectWriter *OW) {
537   const MCEncodedFragment &EF = cast<MCEncodedFragment>(F);
538   OW->WriteBytes(EF.getContents());
539 }
540 
541 /// \brief Write the fragment \p F to the output file.
writeFragment(const MCAssembler & Asm,const MCAsmLayout & Layout,const MCFragment & F)542 static void writeFragment(const MCAssembler &Asm, const MCAsmLayout &Layout,
543                           const MCFragment &F) {
544   MCObjectWriter *OW = &Asm.getWriter();
545 
546   // FIXME: Embed in fragments instead?
547   uint64_t FragmentSize = Asm.computeFragmentSize(Layout, F);
548 
549   // Should NOP padding be written out before this fragment?
550   unsigned BundlePadding = F.getBundlePadding();
551   if (BundlePadding > 0) {
552     assert(Asm.isBundlingEnabled() &&
553            "Writing bundle padding with disabled bundling");
554     assert(F.hasInstructions() &&
555            "Writing bundle padding for a fragment without instructions");
556 
557     unsigned TotalLength = BundlePadding + static_cast<unsigned>(FragmentSize);
558     if (F.alignToBundleEnd() && TotalLength > Asm.getBundleAlignSize()) {
559       // If the padding itself crosses a bundle boundary, it must be emitted
560       // in 2 pieces, since even nop instructions must not cross boundaries.
561       //             v--------------v   <- BundleAlignSize
562       //        v---------v             <- BundlePadding
563       // ----------------------------
564       // | Prev |####|####|    F    |
565       // ----------------------------
566       //        ^-------------------^   <- TotalLength
567       unsigned DistanceToBoundary = TotalLength - Asm.getBundleAlignSize();
568       if (!Asm.getBackend().writeNopData(DistanceToBoundary, OW))
569           report_fatal_error("unable to write NOP sequence of " +
570                              Twine(DistanceToBoundary) + " bytes");
571       BundlePadding -= DistanceToBoundary;
572     }
573     if (!Asm.getBackend().writeNopData(BundlePadding, OW))
574       report_fatal_error("unable to write NOP sequence of " +
575                          Twine(BundlePadding) + " bytes");
576   }
577 
578   // This variable (and its dummy usage) is to participate in the assert at
579   // the end of the function.
580   uint64_t Start = OW->getStream().tell();
581   (void) Start;
582 
583   ++stats::EmittedFragments;
584 
585   switch (F.getKind()) {
586   case MCFragment::FT_Align: {
587     ++stats::EmittedAlignFragments;
588     const MCAlignFragment &AF = cast<MCAlignFragment>(F);
589     assert(AF.getValueSize() && "Invalid virtual align in concrete fragment!");
590 
591     uint64_t Count = FragmentSize / AF.getValueSize();
592 
593     // FIXME: This error shouldn't actually occur (the front end should emit
594     // multiple .align directives to enforce the semantics it wants), but is
595     // severe enough that we want to report it. How to handle this?
596     if (Count * AF.getValueSize() != FragmentSize)
597       report_fatal_error("undefined .align directive, value size '" +
598                         Twine(AF.getValueSize()) +
599                         "' is not a divisor of padding size '" +
600                         Twine(FragmentSize) + "'");
601 
602     // See if we are aligning with nops, and if so do that first to try to fill
603     // the Count bytes.  Then if that did not fill any bytes or there are any
604     // bytes left to fill use the Value and ValueSize to fill the rest.
605     // If we are aligning with nops, ask that target to emit the right data.
606     if (AF.hasEmitNops()) {
607       if (!Asm.getBackend().writeNopData(Count, OW))
608         report_fatal_error("unable to write nop sequence of " +
609                           Twine(Count) + " bytes");
610       break;
611     }
612 
613     // Otherwise, write out in multiples of the value size.
614     for (uint64_t i = 0; i != Count; ++i) {
615       switch (AF.getValueSize()) {
616       default: llvm_unreachable("Invalid size!");
617       case 1: OW->Write8 (uint8_t (AF.getValue())); break;
618       case 2: OW->Write16(uint16_t(AF.getValue())); break;
619       case 4: OW->Write32(uint32_t(AF.getValue())); break;
620       case 8: OW->Write64(uint64_t(AF.getValue())); break;
621       }
622     }
623     break;
624   }
625 
626   case MCFragment::FT_Data:
627     ++stats::EmittedDataFragments;
628     writeFragmentContents(F, OW);
629     break;
630 
631   case MCFragment::FT_Relaxable:
632     ++stats::EmittedRelaxableFragments;
633     writeFragmentContents(F, OW);
634     break;
635 
636   case MCFragment::FT_CompactEncodedInst:
637     ++stats::EmittedCompactEncodedInstFragments;
638     writeFragmentContents(F, OW);
639     break;
640 
641   case MCFragment::FT_Fill: {
642     ++stats::EmittedFillFragments;
643     const MCFillFragment &FF = cast<MCFillFragment>(F);
644 
645     assert(FF.getValueSize() && "Invalid virtual align in concrete fragment!");
646 
647     for (uint64_t i = 0, e = FF.getSize() / FF.getValueSize(); i != e; ++i) {
648       switch (FF.getValueSize()) {
649       default: llvm_unreachable("Invalid size!");
650       case 1: OW->Write8 (uint8_t (FF.getValue())); break;
651       case 2: OW->Write16(uint16_t(FF.getValue())); break;
652       case 4: OW->Write32(uint32_t(FF.getValue())); break;
653       case 8: OW->Write64(uint64_t(FF.getValue())); break;
654       }
655     }
656     break;
657   }
658 
659   case MCFragment::FT_LEB: {
660     const MCLEBFragment &LF = cast<MCLEBFragment>(F);
661     OW->WriteBytes(LF.getContents().str());
662     break;
663   }
664 
665   case MCFragment::FT_Org: {
666     ++stats::EmittedOrgFragments;
667     const MCOrgFragment &OF = cast<MCOrgFragment>(F);
668 
669     for (uint64_t i = 0, e = FragmentSize; i != e; ++i)
670       OW->Write8(uint8_t(OF.getValue()));
671 
672     break;
673   }
674 
675   case MCFragment::FT_Dwarf: {
676     const MCDwarfLineAddrFragment &OF = cast<MCDwarfLineAddrFragment>(F);
677     OW->WriteBytes(OF.getContents().str());
678     break;
679   }
680   case MCFragment::FT_DwarfFrame: {
681     const MCDwarfCallFrameFragment &CF = cast<MCDwarfCallFrameFragment>(F);
682     OW->WriteBytes(CF.getContents().str());
683     break;
684   }
685   }
686 
687   assert(OW->getStream().tell() - Start == FragmentSize &&
688          "The stream should advance by fragment size");
689 }
690 
writeSectionData(const MCSectionData * SD,const MCAsmLayout & Layout) const691 void MCAssembler::writeSectionData(const MCSectionData *SD,
692                                    const MCAsmLayout &Layout) const {
693   // Ignore virtual sections.
694   if (SD->getSection().isVirtualSection()) {
695     assert(Layout.getSectionFileSize(SD) == 0 && "Invalid size for section!");
696 
697     // Check that contents are only things legal inside a virtual section.
698     for (MCSectionData::const_iterator it = SD->begin(),
699            ie = SD->end(); it != ie; ++it) {
700       switch (it->getKind()) {
701       default: llvm_unreachable("Invalid fragment in virtual section!");
702       case MCFragment::FT_Data: {
703         // Check that we aren't trying to write a non-zero contents (or fixups)
704         // into a virtual section. This is to support clients which use standard
705         // directives to fill the contents of virtual sections.
706         const MCDataFragment &DF = cast<MCDataFragment>(*it);
707         assert(DF.fixup_begin() == DF.fixup_end() &&
708                "Cannot have fixups in virtual section!");
709         for (unsigned i = 0, e = DF.getContents().size(); i != e; ++i)
710           assert(DF.getContents()[i] == 0 &&
711                  "Invalid data value for virtual section!");
712         break;
713       }
714       case MCFragment::FT_Align:
715         // Check that we aren't trying to write a non-zero value into a virtual
716         // section.
717         assert((cast<MCAlignFragment>(it)->getValueSize() == 0 ||
718                 cast<MCAlignFragment>(it)->getValue() == 0) &&
719                "Invalid align in virtual section!");
720         break;
721       case MCFragment::FT_Fill:
722         assert((cast<MCFillFragment>(it)->getValueSize() == 0 ||
723                 cast<MCFillFragment>(it)->getValue() == 0) &&
724                "Invalid fill in virtual section!");
725         break;
726       }
727     }
728 
729     return;
730   }
731 
732   uint64_t Start = getWriter().getStream().tell();
733   (void)Start;
734 
735   for (MCSectionData::const_iterator it = SD->begin(), ie = SD->end();
736        it != ie; ++it)
737     writeFragment(*this, Layout, *it);
738 
739   assert(getWriter().getStream().tell() - Start ==
740          Layout.getSectionAddressSize(SD));
741 }
742 
743 
handleFixup(const MCAsmLayout & Layout,MCFragment & F,const MCFixup & Fixup)744 uint64_t MCAssembler::handleFixup(const MCAsmLayout &Layout,
745                                   MCFragment &F,
746                                   const MCFixup &Fixup) {
747    // Evaluate the fixup.
748    MCValue Target;
749    uint64_t FixedValue;
750    if (!evaluateFixup(Layout, Fixup, &F, Target, FixedValue)) {
751      // The fixup was unresolved, we need a relocation. Inform the object
752      // writer of the relocation, and give it an opportunity to adjust the
753      // fixup value if need be.
754      getWriter().RecordRelocation(*this, Layout, &F, Fixup, Target, FixedValue);
755    }
756    return FixedValue;
757  }
758 
Finish()759 void MCAssembler::Finish() {
760   DEBUG_WITH_TYPE("mc-dump", {
761       llvm::errs() << "assembler backend - pre-layout\n--\n";
762       dump(); });
763 
764   // Create the layout object.
765   MCAsmLayout Layout(*this);
766 
767   // Create dummy fragments and assign section ordinals.
768   unsigned SectionIndex = 0;
769   for (MCAssembler::iterator it = begin(), ie = end(); it != ie; ++it) {
770     // Create dummy fragments to eliminate any empty sections, this simplifies
771     // layout.
772     if (it->getFragmentList().empty())
773       new MCDataFragment(it);
774 
775     it->setOrdinal(SectionIndex++);
776   }
777 
778   // Assign layout order indices to sections and fragments.
779   for (unsigned i = 0, e = Layout.getSectionOrder().size(); i != e; ++i) {
780     MCSectionData *SD = Layout.getSectionOrder()[i];
781     SD->setLayoutOrder(i);
782 
783     unsigned FragmentIndex = 0;
784     for (MCSectionData::iterator iFrag = SD->begin(), iFragEnd = SD->end();
785          iFrag != iFragEnd; ++iFrag)
786       iFrag->setLayoutOrder(FragmentIndex++);
787   }
788 
789   // Layout until everything fits.
790   while (layoutOnce(Layout))
791     continue;
792 
793   DEBUG_WITH_TYPE("mc-dump", {
794       llvm::errs() << "assembler backend - post-relaxation\n--\n";
795       dump(); });
796 
797   // Finalize the layout, including fragment lowering.
798   finishLayout(Layout);
799 
800   DEBUG_WITH_TYPE("mc-dump", {
801       llvm::errs() << "assembler backend - final-layout\n--\n";
802       dump(); });
803 
804   uint64_t StartOffset = OS.tell();
805 
806   // Allow the object writer a chance to perform post-layout binding (for
807   // example, to set the index fields in the symbol data).
808   getWriter().ExecutePostLayoutBinding(*this, Layout);
809 
810   // Evaluate and apply the fixups, generating relocation entries as necessary.
811   for (MCAssembler::iterator it = begin(), ie = end(); it != ie; ++it) {
812     for (MCSectionData::iterator it2 = it->begin(),
813            ie2 = it->end(); it2 != ie2; ++it2) {
814       MCEncodedFragmentWithFixups *F =
815         dyn_cast<MCEncodedFragmentWithFixups>(it2);
816       if (F) {
817         for (MCEncodedFragmentWithFixups::fixup_iterator it3 = F->fixup_begin(),
818              ie3 = F->fixup_end(); it3 != ie3; ++it3) {
819           MCFixup &Fixup = *it3;
820           uint64_t FixedValue = handleFixup(Layout, *F, Fixup);
821           getBackend().applyFixup(Fixup, F->getContents().data(),
822                                   F->getContents().size(), FixedValue);
823         }
824       }
825     }
826   }
827 
828   // Write the object file.
829   getWriter().WriteObject(*this, Layout);
830 
831   stats::ObjectBytes += OS.tell() - StartOffset;
832 }
833 
fixupNeedsRelaxation(const MCFixup & Fixup,const MCRelaxableFragment * DF,const MCAsmLayout & Layout) const834 bool MCAssembler::fixupNeedsRelaxation(const MCFixup &Fixup,
835                                        const MCRelaxableFragment *DF,
836                                        const MCAsmLayout &Layout) const {
837   // If we cannot resolve the fixup value, it requires relaxation.
838   MCValue Target;
839   uint64_t Value;
840   if (!evaluateFixup(Layout, Fixup, DF, Target, Value))
841     return true;
842 
843   return getBackend().fixupNeedsRelaxation(Fixup, Value, DF, Layout);
844 }
845 
fragmentNeedsRelaxation(const MCRelaxableFragment * F,const MCAsmLayout & Layout) const846 bool MCAssembler::fragmentNeedsRelaxation(const MCRelaxableFragment *F,
847                                           const MCAsmLayout &Layout) const {
848   // If this inst doesn't ever need relaxation, ignore it. This occurs when we
849   // are intentionally pushing out inst fragments, or because we relaxed a
850   // previous instruction to one that doesn't need relaxation.
851   if (!getBackend().mayNeedRelaxation(F->getInst()))
852     return false;
853 
854   for (MCRelaxableFragment::const_fixup_iterator it = F->fixup_begin(),
855        ie = F->fixup_end(); it != ie; ++it)
856     if (fixupNeedsRelaxation(*it, F, Layout))
857       return true;
858 
859   return false;
860 }
861 
relaxInstruction(MCAsmLayout & Layout,MCRelaxableFragment & F)862 bool MCAssembler::relaxInstruction(MCAsmLayout &Layout,
863                                    MCRelaxableFragment &F) {
864   if (!fragmentNeedsRelaxation(&F, Layout))
865     return false;
866 
867   ++stats::RelaxedInstructions;
868 
869   // FIXME-PERF: We could immediately lower out instructions if we can tell
870   // they are fully resolved, to avoid retesting on later passes.
871 
872   // Relax the fragment.
873 
874   MCInst Relaxed;
875   getBackend().relaxInstruction(F.getInst(), Relaxed);
876 
877   // Encode the new instruction.
878   //
879   // FIXME-PERF: If it matters, we could let the target do this. It can
880   // probably do so more efficiently in many cases.
881   SmallVector<MCFixup, 4> Fixups;
882   SmallString<256> Code;
883   raw_svector_ostream VecOS(Code);
884   getEmitter().EncodeInstruction(Relaxed, VecOS, Fixups);
885   VecOS.flush();
886 
887   // Update the fragment.
888   F.setInst(Relaxed);
889   F.getContents() = Code;
890   F.getFixups() = Fixups;
891 
892   return true;
893 }
894 
relaxLEB(MCAsmLayout & Layout,MCLEBFragment & LF)895 bool MCAssembler::relaxLEB(MCAsmLayout &Layout, MCLEBFragment &LF) {
896   int64_t Value = 0;
897   uint64_t OldSize = LF.getContents().size();
898   bool IsAbs = LF.getValue().EvaluateAsAbsolute(Value, Layout);
899   (void)IsAbs;
900   assert(IsAbs);
901   SmallString<8> &Data = LF.getContents();
902   Data.clear();
903   raw_svector_ostream OSE(Data);
904   if (LF.isSigned())
905     encodeSLEB128(Value, OSE);
906   else
907     encodeULEB128(Value, OSE);
908   OSE.flush();
909   return OldSize != LF.getContents().size();
910 }
911 
relaxDwarfLineAddr(MCAsmLayout & Layout,MCDwarfLineAddrFragment & DF)912 bool MCAssembler::relaxDwarfLineAddr(MCAsmLayout &Layout,
913                                      MCDwarfLineAddrFragment &DF) {
914   MCContext &Context = Layout.getAssembler().getContext();
915   int64_t AddrDelta = 0;
916   uint64_t OldSize = DF.getContents().size();
917   bool IsAbs = DF.getAddrDelta().EvaluateAsAbsolute(AddrDelta, Layout);
918   (void)IsAbs;
919   assert(IsAbs);
920   int64_t LineDelta;
921   LineDelta = DF.getLineDelta();
922   SmallString<8> &Data = DF.getContents();
923   Data.clear();
924   raw_svector_ostream OSE(Data);
925   MCDwarfLineAddr::Encode(Context, LineDelta, AddrDelta, OSE);
926   OSE.flush();
927   return OldSize != Data.size();
928 }
929 
relaxDwarfCallFrameFragment(MCAsmLayout & Layout,MCDwarfCallFrameFragment & DF)930 bool MCAssembler::relaxDwarfCallFrameFragment(MCAsmLayout &Layout,
931                                               MCDwarfCallFrameFragment &DF) {
932   MCContext &Context = Layout.getAssembler().getContext();
933   int64_t AddrDelta = 0;
934   uint64_t OldSize = DF.getContents().size();
935   bool IsAbs = DF.getAddrDelta().EvaluateAsAbsolute(AddrDelta, Layout);
936   (void)IsAbs;
937   assert(IsAbs);
938   SmallString<8> &Data = DF.getContents();
939   Data.clear();
940   raw_svector_ostream OSE(Data);
941   MCDwarfFrameEmitter::EncodeAdvanceLoc(Context, AddrDelta, OSE);
942   OSE.flush();
943   return OldSize != Data.size();
944 }
945 
layoutSectionOnce(MCAsmLayout & Layout,MCSectionData & SD)946 bool MCAssembler::layoutSectionOnce(MCAsmLayout &Layout, MCSectionData &SD) {
947   // Holds the first fragment which needed relaxing during this layout. It will
948   // remain NULL if none were relaxed.
949   // When a fragment is relaxed, all the fragments following it should get
950   // invalidated because their offset is going to change.
951   MCFragment *FirstRelaxedFragment = NULL;
952 
953   // Attempt to relax all the fragments in the section.
954   for (MCSectionData::iterator I = SD.begin(), IE = SD.end(); I != IE; ++I) {
955     // Check if this is a fragment that needs relaxation.
956     bool RelaxedFrag = false;
957     switch(I->getKind()) {
958     default:
959       break;
960     case MCFragment::FT_Relaxable:
961       assert(!getRelaxAll() &&
962              "Did not expect a MCRelaxableFragment in RelaxAll mode");
963       RelaxedFrag = relaxInstruction(Layout, *cast<MCRelaxableFragment>(I));
964       break;
965     case MCFragment::FT_Dwarf:
966       RelaxedFrag = relaxDwarfLineAddr(Layout,
967                                        *cast<MCDwarfLineAddrFragment>(I));
968       break;
969     case MCFragment::FT_DwarfFrame:
970       RelaxedFrag =
971         relaxDwarfCallFrameFragment(Layout,
972                                     *cast<MCDwarfCallFrameFragment>(I));
973       break;
974     case MCFragment::FT_LEB:
975       RelaxedFrag = relaxLEB(Layout, *cast<MCLEBFragment>(I));
976       break;
977     }
978     if (RelaxedFrag && !FirstRelaxedFragment)
979       FirstRelaxedFragment = I;
980   }
981   if (FirstRelaxedFragment) {
982     Layout.invalidateFragmentsFrom(FirstRelaxedFragment);
983     return true;
984   }
985   return false;
986 }
987 
layoutOnce(MCAsmLayout & Layout)988 bool MCAssembler::layoutOnce(MCAsmLayout &Layout) {
989   ++stats::RelaxationSteps;
990 
991   bool WasRelaxed = false;
992   for (iterator it = begin(), ie = end(); it != ie; ++it) {
993     MCSectionData &SD = *it;
994     while (layoutSectionOnce(Layout, SD))
995       WasRelaxed = true;
996   }
997 
998   return WasRelaxed;
999 }
1000 
finishLayout(MCAsmLayout & Layout)1001 void MCAssembler::finishLayout(MCAsmLayout &Layout) {
1002   // The layout is done. Mark every fragment as valid.
1003   for (unsigned int i = 0, n = Layout.getSectionOrder().size(); i != n; ++i) {
1004     Layout.getFragmentOffset(&*Layout.getSectionOrder()[i]->rbegin());
1005   }
1006 }
1007 
1008 // Debugging methods
1009 
1010 namespace llvm {
1011 
operator <<(raw_ostream & OS,const MCFixup & AF)1012 raw_ostream &operator<<(raw_ostream &OS, const MCFixup &AF) {
1013   OS << "<MCFixup" << " Offset:" << AF.getOffset()
1014      << " Value:" << *AF.getValue()
1015      << " Kind:" << AF.getKind() << ">";
1016   return OS;
1017 }
1018 
1019 }
1020 
1021 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
dump()1022 void MCFragment::dump() {
1023   raw_ostream &OS = llvm::errs();
1024 
1025   OS << "<";
1026   switch (getKind()) {
1027   case MCFragment::FT_Align: OS << "MCAlignFragment"; break;
1028   case MCFragment::FT_Data:  OS << "MCDataFragment"; break;
1029   case MCFragment::FT_CompactEncodedInst:
1030     OS << "MCCompactEncodedInstFragment"; break;
1031   case MCFragment::FT_Fill:  OS << "MCFillFragment"; break;
1032   case MCFragment::FT_Relaxable:  OS << "MCRelaxableFragment"; break;
1033   case MCFragment::FT_Org:   OS << "MCOrgFragment"; break;
1034   case MCFragment::FT_Dwarf: OS << "MCDwarfFragment"; break;
1035   case MCFragment::FT_DwarfFrame: OS << "MCDwarfCallFrameFragment"; break;
1036   case MCFragment::FT_LEB:   OS << "MCLEBFragment"; break;
1037   }
1038 
1039   OS << "<MCFragment " << (void*) this << " LayoutOrder:" << LayoutOrder
1040      << " Offset:" << Offset
1041      << " HasInstructions:" << hasInstructions()
1042      << " BundlePadding:" << static_cast<unsigned>(getBundlePadding()) << ">";
1043 
1044   switch (getKind()) {
1045   case MCFragment::FT_Align: {
1046     const MCAlignFragment *AF = cast<MCAlignFragment>(this);
1047     if (AF->hasEmitNops())
1048       OS << " (emit nops)";
1049     OS << "\n       ";
1050     OS << " Alignment:" << AF->getAlignment()
1051        << " Value:" << AF->getValue() << " ValueSize:" << AF->getValueSize()
1052        << " MaxBytesToEmit:" << AF->getMaxBytesToEmit() << ">";
1053     break;
1054   }
1055   case MCFragment::FT_Data:  {
1056     const MCDataFragment *DF = cast<MCDataFragment>(this);
1057     OS << "\n       ";
1058     OS << " Contents:[";
1059     const SmallVectorImpl<char> &Contents = DF->getContents();
1060     for (unsigned i = 0, e = Contents.size(); i != e; ++i) {
1061       if (i) OS << ",";
1062       OS << hexdigit((Contents[i] >> 4) & 0xF) << hexdigit(Contents[i] & 0xF);
1063     }
1064     OS << "] (" << Contents.size() << " bytes)";
1065 
1066     if (DF->fixup_begin() != DF->fixup_end()) {
1067       OS << ",\n       ";
1068       OS << " Fixups:[";
1069       for (MCDataFragment::const_fixup_iterator it = DF->fixup_begin(),
1070              ie = DF->fixup_end(); it != ie; ++it) {
1071         if (it != DF->fixup_begin()) OS << ",\n                ";
1072         OS << *it;
1073       }
1074       OS << "]";
1075     }
1076     break;
1077   }
1078   case MCFragment::FT_CompactEncodedInst: {
1079     const MCCompactEncodedInstFragment *CEIF =
1080       cast<MCCompactEncodedInstFragment>(this);
1081     OS << "\n       ";
1082     OS << " Contents:[";
1083     const SmallVectorImpl<char> &Contents = CEIF->getContents();
1084     for (unsigned i = 0, e = Contents.size(); i != e; ++i) {
1085       if (i) OS << ",";
1086       OS << hexdigit((Contents[i] >> 4) & 0xF) << hexdigit(Contents[i] & 0xF);
1087     }
1088     OS << "] (" << Contents.size() << " bytes)";
1089     break;
1090   }
1091   case MCFragment::FT_Fill:  {
1092     const MCFillFragment *FF = cast<MCFillFragment>(this);
1093     OS << " Value:" << FF->getValue() << " ValueSize:" << FF->getValueSize()
1094        << " Size:" << FF->getSize();
1095     break;
1096   }
1097   case MCFragment::FT_Relaxable:  {
1098     const MCRelaxableFragment *F = cast<MCRelaxableFragment>(this);
1099     OS << "\n       ";
1100     OS << " Inst:";
1101     F->getInst().dump_pretty(OS);
1102     break;
1103   }
1104   case MCFragment::FT_Org:  {
1105     const MCOrgFragment *OF = cast<MCOrgFragment>(this);
1106     OS << "\n       ";
1107     OS << " Offset:" << OF->getOffset() << " Value:" << OF->getValue();
1108     break;
1109   }
1110   case MCFragment::FT_Dwarf:  {
1111     const MCDwarfLineAddrFragment *OF = cast<MCDwarfLineAddrFragment>(this);
1112     OS << "\n       ";
1113     OS << " AddrDelta:" << OF->getAddrDelta()
1114        << " LineDelta:" << OF->getLineDelta();
1115     break;
1116   }
1117   case MCFragment::FT_DwarfFrame:  {
1118     const MCDwarfCallFrameFragment *CF = cast<MCDwarfCallFrameFragment>(this);
1119     OS << "\n       ";
1120     OS << " AddrDelta:" << CF->getAddrDelta();
1121     break;
1122   }
1123   case MCFragment::FT_LEB: {
1124     const MCLEBFragment *LF = cast<MCLEBFragment>(this);
1125     OS << "\n       ";
1126     OS << " Value:" << LF->getValue() << " Signed:" << LF->isSigned();
1127     break;
1128   }
1129   }
1130   OS << ">";
1131 }
1132 
dump()1133 void MCSectionData::dump() {
1134   raw_ostream &OS = llvm::errs();
1135 
1136   OS << "<MCSectionData";
1137   OS << " Alignment:" << getAlignment()
1138      << " Fragments:[\n      ";
1139   for (iterator it = begin(), ie = end(); it != ie; ++it) {
1140     if (it != begin()) OS << ",\n      ";
1141     it->dump();
1142   }
1143   OS << "]>";
1144 }
1145 
dump()1146 void MCSymbolData::dump() {
1147   raw_ostream &OS = llvm::errs();
1148 
1149   OS << "<MCSymbolData Symbol:" << getSymbol()
1150      << " Fragment:" << getFragment() << " Offset:" << getOffset()
1151      << " Flags:" << getFlags() << " Index:" << getIndex();
1152   if (isCommon())
1153     OS << " (common, size:" << getCommonSize()
1154        << " align: " << getCommonAlignment() << ")";
1155   if (isExternal())
1156     OS << " (external)";
1157   if (isPrivateExtern())
1158     OS << " (private extern)";
1159   OS << ">";
1160 }
1161 
dump()1162 void MCAssembler::dump() {
1163   raw_ostream &OS = llvm::errs();
1164 
1165   OS << "<MCAssembler\n";
1166   OS << "  Sections:[\n    ";
1167   for (iterator it = begin(), ie = end(); it != ie; ++it) {
1168     if (it != begin()) OS << ",\n    ";
1169     it->dump();
1170   }
1171   OS << "],\n";
1172   OS << "  Symbols:[";
1173 
1174   for (symbol_iterator it = symbol_begin(), ie = symbol_end(); it != ie; ++it) {
1175     if (it != symbol_begin()) OS << ",\n           ";
1176     it->dump();
1177   }
1178   OS << "]>\n";
1179 }
1180 #endif
1181 
1182 // anchors for MC*Fragment vtables
anchor()1183 void MCEncodedFragment::anchor() { }
anchor()1184 void MCEncodedFragmentWithFixups::anchor() { }
anchor()1185 void MCDataFragment::anchor() { }
anchor()1186 void MCCompactEncodedInstFragment::anchor() { }
anchor()1187 void MCRelaxableFragment::anchor() { }
anchor()1188 void MCAlignFragment::anchor() { }
anchor()1189 void MCFillFragment::anchor() { }
anchor()1190 void MCOrgFragment::anchor() { }
anchor()1191 void MCLEBFragment::anchor() { }
anchor()1192 void MCDwarfLineAddrFragment::anchor() { }
anchor()1193 void MCDwarfCallFrameFragment::anchor() { }
1194