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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 #include "llvm/MC/MCAssembler.h"
     11 #include "llvm/ADT/ArrayRef.h"
     12 #include "llvm/ADT/SmallString.h"
     13 #include "llvm/ADT/SmallVector.h"
     14 #include "llvm/ADT/Statistic.h"
     15 #include "llvm/ADT/StringRef.h"
     16 #include "llvm/ADT/Twine.h"
     17 #include "llvm/MC/MCAsmBackend.h"
     18 #include "llvm/MC/MCAsmInfo.h"
     19 #include "llvm/MC/MCAsmLayout.h"
     20 #include "llvm/MC/MCCodeEmitter.h"
     21 #include "llvm/MC/MCCodeView.h"
     22 #include "llvm/MC/MCContext.h"
     23 #include "llvm/MC/MCDwarf.h"
     24 #include "llvm/MC/MCExpr.h"
     25 #include "llvm/MC/MCFixup.h"
     26 #include "llvm/MC/MCFixupKindInfo.h"
     27 #include "llvm/MC/MCFragment.h"
     28 #include "llvm/MC/MCInst.h"
     29 #include "llvm/MC/MCObjectWriter.h"
     30 #include "llvm/MC/MCSection.h"
     31 #include "llvm/MC/MCSectionELF.h"
     32 #include "llvm/MC/MCSymbol.h"
     33 #include "llvm/MC/MCValue.h"
     34 #include "llvm/Support/Casting.h"
     35 #include "llvm/Support/Debug.h"
     36 #include "llvm/Support/ErrorHandling.h"
     37 #include "llvm/Support/LEB128.h"
     38 #include "llvm/Support/MathExtras.h"
     39 #include "llvm/Support/raw_ostream.h"
     40 #include <cassert>
     41 #include <cstdint>
     42 #include <cstring>
     43 #include <tuple>
     44 #include <utility>
     45 
     46 using namespace llvm;
     47 
     48 #define DEBUG_TYPE "assembler"
     49 
     50 namespace {
     51 namespace stats {
     52 
     53 STATISTIC(EmittedFragments, "Number of emitted assembler fragments - total");
     54 STATISTIC(EmittedRelaxableFragments,
     55           "Number of emitted assembler fragments - relaxable");
     56 STATISTIC(EmittedDataFragments,
     57           "Number of emitted assembler fragments - data");
     58 STATISTIC(EmittedCompactEncodedInstFragments,
     59           "Number of emitted assembler fragments - compact encoded inst");
     60 STATISTIC(EmittedAlignFragments,
     61           "Number of emitted assembler fragments - align");
     62 STATISTIC(EmittedFillFragments,
     63           "Number of emitted assembler fragments - fill");
     64 STATISTIC(EmittedOrgFragments,
     65           "Number of emitted assembler fragments - org");
     66 STATISTIC(evaluateFixup, "Number of evaluated fixups");
     67 STATISTIC(FragmentLayouts, "Number of fragment layouts");
     68 STATISTIC(ObjectBytes, "Number of emitted object file bytes");
     69 STATISTIC(RelaxationSteps, "Number of assembler layout and relaxation steps");
     70 STATISTIC(RelaxedInstructions, "Number of relaxed instructions");
     71 STATISTIC(PaddingFragmentsRelaxations,
     72           "Number of Padding Fragments relaxations");
     73 STATISTIC(PaddingFragmentsBytes,
     74           "Total size of all padding from adding Fragments");
     75 
     76 } // end namespace stats
     77 } // end anonymous namespace
     78 
     79 // FIXME FIXME FIXME: There are number of places in this file where we convert
     80 // what is a 64-bit assembler value used for computation into a value in the
     81 // object file, which may truncate it. We should detect that truncation where
     82 // invalid and report errors back.
     83 
     84 /* *** */
     85 
     86 MCAssembler::MCAssembler(MCContext &Context,
     87                          std::unique_ptr<MCAsmBackend> Backend,
     88                          std::unique_ptr<MCCodeEmitter> Emitter,
     89                          std::unique_ptr<MCObjectWriter> Writer)
     90     : Context(Context), Backend(std::move(Backend)),
     91       Emitter(std::move(Emitter)), Writer(std::move(Writer)),
     92       BundleAlignSize(0), RelaxAll(false), SubsectionsViaSymbols(false),
     93       IncrementalLinkerCompatible(false), ELFHeaderEFlags(0) {
     94   VersionInfo.Major = 0; // Major version == 0 for "none specified"
     95 }
     96 
     97 MCAssembler::~MCAssembler() = default;
     98 
     99 void MCAssembler::reset() {
    100   Sections.clear();
    101   Symbols.clear();
    102   IndirectSymbols.clear();
    103   DataRegions.clear();
    104   LinkerOptions.clear();
    105   FileNames.clear();
    106   ThumbFuncs.clear();
    107   BundleAlignSize = 0;
    108   RelaxAll = false;
    109   SubsectionsViaSymbols = false;
    110   IncrementalLinkerCompatible = false;
    111   ELFHeaderEFlags = 0;
    112   LOHContainer.reset();
    113   VersionInfo.Major = 0;
    114 
    115   // reset objects owned by us
    116   if (getBackendPtr())
    117     getBackendPtr()->reset();
    118   if (getEmitterPtr())
    119     getEmitterPtr()->reset();
    120   if (getWriterPtr())
    121     getWriterPtr()->reset();
    122   getLOHContainer().reset();
    123 }
    124 
    125 bool MCAssembler::registerSection(MCSection &Section) {
    126   if (Section.isRegistered())
    127     return false;
    128   Sections.push_back(&Section);
    129   Section.setIsRegistered(true);
    130   return true;
    131 }
    132 
    133 bool MCAssembler::isThumbFunc(const MCSymbol *Symbol) const {
    134   if (ThumbFuncs.count(Symbol))
    135     return true;
    136 
    137   if (!Symbol->isVariable())
    138     return false;
    139 
    140   const MCExpr *Expr = Symbol->getVariableValue();
    141 
    142   MCValue V;
    143   if (!Expr->evaluateAsRelocatable(V, nullptr, nullptr))
    144     return false;
    145 
    146   if (V.getSymB() || V.getRefKind() != MCSymbolRefExpr::VK_None)
    147     return false;
    148 
    149   const MCSymbolRefExpr *Ref = V.getSymA();
    150   if (!Ref)
    151     return false;
    152 
    153   if (Ref->getKind() != MCSymbolRefExpr::VK_None)
    154     return false;
    155 
    156   const MCSymbol &Sym = Ref->getSymbol();
    157   if (!isThumbFunc(&Sym))
    158     return false;
    159 
    160   ThumbFuncs.insert(Symbol); // Cache it.
    161   return true;
    162 }
    163 
    164 bool MCAssembler::isSymbolLinkerVisible(const MCSymbol &Symbol) const {
    165   // Non-temporary labels should always be visible to the linker.
    166   if (!Symbol.isTemporary())
    167     return true;
    168 
    169   // Absolute temporary labels are never visible.
    170   if (!Symbol.isInSection())
    171     return false;
    172 
    173   if (Symbol.isUsedInReloc())
    174     return true;
    175 
    176   return false;
    177 }
    178 
    179 const MCSymbol *MCAssembler::getAtom(const MCSymbol &S) const {
    180   // Linker visible symbols define atoms.
    181   if (isSymbolLinkerVisible(S))
    182     return &S;
    183 
    184   // Absolute and undefined symbols have no defining atom.
    185   if (!S.isInSection())
    186     return nullptr;
    187 
    188   // Non-linker visible symbols in sections which can't be atomized have no
    189   // defining atom.
    190   if (!getContext().getAsmInfo()->isSectionAtomizableBySymbols(
    191           *S.getFragment()->getParent()))
    192     return nullptr;
    193 
    194   // Otherwise, return the atom for the containing fragment.
    195   return S.getFragment()->getAtom();
    196 }
    197 
    198 bool MCAssembler::evaluateFixup(const MCAsmLayout &Layout,
    199                                 const MCFixup &Fixup, const MCFragment *DF,
    200                                 MCValue &Target, uint64_t &Value,
    201                                 bool &WasForced) const {
    202   ++stats::evaluateFixup;
    203 
    204   // FIXME: This code has some duplication with recordRelocation. We should
    205   // probably merge the two into a single callback that tries to evaluate a
    206   // fixup and records a relocation if one is needed.
    207 
    208   // On error claim to have completely evaluated the fixup, to prevent any
    209   // further processing from being done.
    210   const MCExpr *Expr = Fixup.getValue();
    211   MCContext &Ctx = getContext();
    212   Value = 0;
    213   WasForced = false;
    214   if (!Expr->evaluateAsRelocatable(Target, &Layout, &Fixup)) {
    215     Ctx.reportError(Fixup.getLoc(), "expected relocatable expression");
    216     return true;
    217   }
    218   if (const MCSymbolRefExpr *RefB = Target.getSymB()) {
    219     if (RefB->getKind() != MCSymbolRefExpr::VK_None) {
    220       Ctx.reportError(Fixup.getLoc(),
    221                       "unsupported subtraction of qualified symbol");
    222       return true;
    223     }
    224   }
    225 
    226   assert(getBackendPtr() && "Expected assembler backend");
    227   bool IsPCRel = getBackendPtr()->getFixupKindInfo(Fixup.getKind()).Flags &
    228                  MCFixupKindInfo::FKF_IsPCRel;
    229 
    230   bool IsResolved = false;
    231   if (IsPCRel) {
    232     if (Target.getSymB()) {
    233       IsResolved = false;
    234     } else if (!Target.getSymA()) {
    235       IsResolved = false;
    236     } else {
    237       const MCSymbolRefExpr *A = Target.getSymA();
    238       const MCSymbol &SA = A->getSymbol();
    239       if (A->getKind() != MCSymbolRefExpr::VK_None || SA.isUndefined()) {
    240         IsResolved = false;
    241       } else if (auto *Writer = getWriterPtr()) {
    242         IsResolved = Writer->isSymbolRefDifferenceFullyResolvedImpl(
    243             *this, SA, *DF, false, true);
    244       }
    245     }
    246   } else {
    247     IsResolved = Target.isAbsolute();
    248   }
    249 
    250   Value = Target.getConstant();
    251 
    252   if (const MCSymbolRefExpr *A = Target.getSymA()) {
    253     const MCSymbol &Sym = A->getSymbol();
    254     if (Sym.isDefined())
    255       Value += Layout.getSymbolOffset(Sym);
    256   }
    257   if (const MCSymbolRefExpr *B = Target.getSymB()) {
    258     const MCSymbol &Sym = B->getSymbol();
    259     if (Sym.isDefined())
    260       Value -= Layout.getSymbolOffset(Sym);
    261   }
    262 
    263   bool ShouldAlignPC = getBackend().getFixupKindInfo(Fixup.getKind()).Flags &
    264                        MCFixupKindInfo::FKF_IsAlignedDownTo32Bits;
    265   assert((ShouldAlignPC ? IsPCRel : true) &&
    266     "FKF_IsAlignedDownTo32Bits is only allowed on PC-relative fixups!");
    267 
    268   if (IsPCRel) {
    269     uint32_t Offset = Layout.getFragmentOffset(DF) + Fixup.getOffset();
    270 
    271     // A number of ARM fixups in Thumb mode require that the effective PC
    272     // address be determined as the 32-bit aligned version of the actual offset.
    273     if (ShouldAlignPC) Offset &= ~0x3;
    274     Value -= Offset;
    275   }
    276 
    277   // Let the backend force a relocation if needed.
    278   if (IsResolved && getBackend().shouldForceRelocation(*this, Fixup, Target)) {
    279     IsResolved = false;
    280     WasForced = true;
    281   }
    282 
    283   return IsResolved;
    284 }
    285 
    286 uint64_t MCAssembler::computeFragmentSize(const MCAsmLayout &Layout,
    287                                           const MCFragment &F) const {
    288   assert(getBackendPtr() && "Requires assembler backend");
    289   switch (F.getKind()) {
    290   case MCFragment::FT_Data:
    291     return cast<MCDataFragment>(F).getContents().size();
    292   case MCFragment::FT_Relaxable:
    293     return cast<MCRelaxableFragment>(F).getContents().size();
    294   case MCFragment::FT_CompactEncodedInst:
    295     return cast<MCCompactEncodedInstFragment>(F).getContents().size();
    296   case MCFragment::FT_Fill: {
    297     auto &FF = cast<MCFillFragment>(F);
    298     int64_t NumValues = 0;
    299     if (!FF.getNumValues().evaluateAsAbsolute(NumValues, Layout)) {
    300       getContext().reportError(FF.getLoc(),
    301                                "expected assembly-time absolute expression");
    302       return 0;
    303     }
    304     int64_t Size = NumValues * FF.getValueSize();
    305     if (Size < 0) {
    306       getContext().reportError(FF.getLoc(), "invalid number of bytes");
    307       return 0;
    308     }
    309     return Size;
    310   }
    311 
    312   case MCFragment::FT_LEB:
    313     return cast<MCLEBFragment>(F).getContents().size();
    314 
    315   case MCFragment::FT_Padding:
    316     return cast<MCPaddingFragment>(F).getSize();
    317 
    318   case MCFragment::FT_SymbolId:
    319     return 4;
    320 
    321   case MCFragment::FT_Align: {
    322     const MCAlignFragment &AF = cast<MCAlignFragment>(F);
    323     unsigned Offset = Layout.getFragmentOffset(&AF);
    324     unsigned Size = OffsetToAlignment(Offset, AF.getAlignment());
    325     // If we are padding with nops, force the padding to be larger than the
    326     // minimum nop size.
    327     if (Size > 0 && AF.hasEmitNops()) {
    328       while (Size % getBackend().getMinimumNopSize())
    329         Size += AF.getAlignment();
    330     }
    331     if (Size > AF.getMaxBytesToEmit())
    332       return 0;
    333     return Size;
    334   }
    335 
    336   case MCFragment::FT_Org: {
    337     const MCOrgFragment &OF = cast<MCOrgFragment>(F);
    338     MCValue Value;
    339     if (!OF.getOffset().evaluateAsValue(Value, Layout)) {
    340       getContext().reportError(OF.getLoc(),
    341                                "expected assembly-time absolute expression");
    342         return 0;
    343     }
    344 
    345     uint64_t FragmentOffset = Layout.getFragmentOffset(&OF);
    346     int64_t TargetLocation = Value.getConstant();
    347     if (const MCSymbolRefExpr *A = Value.getSymA()) {
    348       uint64_t Val;
    349       if (!Layout.getSymbolOffset(A->getSymbol(), Val)) {
    350         getContext().reportError(OF.getLoc(), "expected absolute expression");
    351         return 0;
    352       }
    353       TargetLocation += Val;
    354     }
    355     int64_t Size = TargetLocation - FragmentOffset;
    356     if (Size < 0 || Size >= 0x40000000) {
    357       getContext().reportError(
    358           OF.getLoc(), "invalid .org offset '" + Twine(TargetLocation) +
    359                            "' (at offset '" + Twine(FragmentOffset) + "')");
    360       return 0;
    361     }
    362     return Size;
    363   }
    364 
    365   case MCFragment::FT_Dwarf:
    366     return cast<MCDwarfLineAddrFragment>(F).getContents().size();
    367   case MCFragment::FT_DwarfFrame:
    368     return cast<MCDwarfCallFrameFragment>(F).getContents().size();
    369   case MCFragment::FT_CVInlineLines:
    370     return cast<MCCVInlineLineTableFragment>(F).getContents().size();
    371   case MCFragment::FT_CVDefRange:
    372     return cast<MCCVDefRangeFragment>(F).getContents().size();
    373   case MCFragment::FT_Dummy:
    374     llvm_unreachable("Should not have been added");
    375   }
    376 
    377   llvm_unreachable("invalid fragment kind");
    378 }
    379 
    380 void MCAsmLayout::layoutFragment(MCFragment *F) {
    381   MCFragment *Prev = F->getPrevNode();
    382 
    383   // We should never try to recompute something which is valid.
    384   assert(!isFragmentValid(F) && "Attempt to recompute a valid fragment!");
    385   // We should never try to compute the fragment layout if its predecessor
    386   // isn't valid.
    387   assert((!Prev || isFragmentValid(Prev)) &&
    388          "Attempt to compute fragment before its predecessor!");
    389 
    390   ++stats::FragmentLayouts;
    391 
    392   // Compute fragment offset and size.
    393   if (Prev)
    394     F->Offset = Prev->Offset + getAssembler().computeFragmentSize(*this, *Prev);
    395   else
    396     F->Offset = 0;
    397   LastValidFragment[F->getParent()] = F;
    398 
    399   // If bundling is enabled and this fragment has instructions in it, it has to
    400   // obey the bundling restrictions. With padding, we'll have:
    401   //
    402   //
    403   //        BundlePadding
    404   //             |||
    405   // -------------------------------------
    406   //   Prev  |##########|       F        |
    407   // -------------------------------------
    408   //                    ^
    409   //                    |
    410   //                    F->Offset
    411   //
    412   // The fragment's offset will point to after the padding, and its computed
    413   // size won't include the padding.
    414   //
    415   // When the -mc-relax-all flag is used, we optimize bundling by writting the
    416   // padding directly into fragments when the instructions are emitted inside
    417   // the streamer. When the fragment is larger than the bundle size, we need to
    418   // ensure that it's bundle aligned. This means that if we end up with
    419   // multiple fragments, we must emit bundle padding between fragments.
    420   //
    421   // ".align N" is an example of a directive that introduces multiple
    422   // fragments. We could add a special case to handle ".align N" by emitting
    423   // within-fragment padding (which would produce less padding when N is less
    424   // than the bundle size), but for now we don't.
    425   //
    426   if (Assembler.isBundlingEnabled() && F->hasInstructions()) {
    427     assert(isa<MCEncodedFragment>(F) &&
    428            "Only MCEncodedFragment implementations have instructions");
    429     MCEncodedFragment *EF = cast<MCEncodedFragment>(F);
    430     uint64_t FSize = Assembler.computeFragmentSize(*this, *EF);
    431 
    432     if (!Assembler.getRelaxAll() && FSize > Assembler.getBundleAlignSize())
    433       report_fatal_error("Fragment can't be larger than a bundle size");
    434 
    435     uint64_t RequiredBundlePadding =
    436         computeBundlePadding(Assembler, EF, EF->Offset, FSize);
    437     if (RequiredBundlePadding > UINT8_MAX)
    438       report_fatal_error("Padding cannot exceed 255 bytes");
    439     EF->setBundlePadding(static_cast<uint8_t>(RequiredBundlePadding));
    440     EF->Offset += RequiredBundlePadding;
    441   }
    442 }
    443 
    444 void MCAssembler::registerSymbol(const MCSymbol &Symbol, bool *Created) {
    445   bool New = !Symbol.isRegistered();
    446   if (Created)
    447     *Created = New;
    448   if (New) {
    449     Symbol.setIsRegistered(true);
    450     Symbols.push_back(&Symbol);
    451   }
    452 }
    453 
    454 void MCAssembler::writeFragmentPadding(raw_ostream &OS,
    455                                        const MCEncodedFragment &EF,
    456                                        uint64_t FSize) const {
    457   assert(getBackendPtr() && "Expected assembler backend");
    458   // Should NOP padding be written out before this fragment?
    459   unsigned BundlePadding = EF.getBundlePadding();
    460   if (BundlePadding > 0) {
    461     assert(isBundlingEnabled() &&
    462            "Writing bundle padding with disabled bundling");
    463     assert(EF.hasInstructions() &&
    464            "Writing bundle padding for a fragment without instructions");
    465 
    466     unsigned TotalLength = BundlePadding + static_cast<unsigned>(FSize);
    467     if (EF.alignToBundleEnd() && TotalLength > getBundleAlignSize()) {
    468       // If the padding itself crosses a bundle boundary, it must be emitted
    469       // in 2 pieces, since even nop instructions must not cross boundaries.
    470       //             v--------------v   <- BundleAlignSize
    471       //        v---------v             <- BundlePadding
    472       // ----------------------------
    473       // | Prev |####|####|    F    |
    474       // ----------------------------
    475       //        ^-------------------^   <- TotalLength
    476       unsigned DistanceToBoundary = TotalLength - getBundleAlignSize();
    477       if (!getBackend().writeNopData(OS, DistanceToBoundary))
    478         report_fatal_error("unable to write NOP sequence of " +
    479                            Twine(DistanceToBoundary) + " bytes");
    480       BundlePadding -= DistanceToBoundary;
    481     }
    482     if (!getBackend().writeNopData(OS, BundlePadding))
    483       report_fatal_error("unable to write NOP sequence of " +
    484                          Twine(BundlePadding) + " bytes");
    485   }
    486 }
    487 
    488 /// Write the fragment \p F to the output file.
    489 static void writeFragment(raw_ostream &OS, const MCAssembler &Asm,
    490                           const MCAsmLayout &Layout, const MCFragment &F) {
    491   // FIXME: Embed in fragments instead?
    492   uint64_t FragmentSize = Asm.computeFragmentSize(Layout, F);
    493 
    494   support::endianness Endian = Asm.getBackend().Endian;
    495 
    496   if (const MCEncodedFragment *EF = dyn_cast<MCEncodedFragment>(&F))
    497     Asm.writeFragmentPadding(OS, *EF, FragmentSize);
    498 
    499   // This variable (and its dummy usage) is to participate in the assert at
    500   // the end of the function.
    501   uint64_t Start = OS.tell();
    502   (void) Start;
    503 
    504   ++stats::EmittedFragments;
    505 
    506   switch (F.getKind()) {
    507   case MCFragment::FT_Align: {
    508     ++stats::EmittedAlignFragments;
    509     const MCAlignFragment &AF = cast<MCAlignFragment>(F);
    510     assert(AF.getValueSize() && "Invalid virtual align in concrete fragment!");
    511 
    512     uint64_t Count = FragmentSize / AF.getValueSize();
    513 
    514     // FIXME: This error shouldn't actually occur (the front end should emit
    515     // multiple .align directives to enforce the semantics it wants), but is
    516     // severe enough that we want to report it. How to handle this?
    517     if (Count * AF.getValueSize() != FragmentSize)
    518       report_fatal_error("undefined .align directive, value size '" +
    519                         Twine(AF.getValueSize()) +
    520                         "' is not a divisor of padding size '" +
    521                         Twine(FragmentSize) + "'");
    522 
    523     // See if we are aligning with nops, and if so do that first to try to fill
    524     // the Count bytes.  Then if that did not fill any bytes or there are any
    525     // bytes left to fill use the Value and ValueSize to fill the rest.
    526     // If we are aligning with nops, ask that target to emit the right data.
    527     if (AF.hasEmitNops()) {
    528       if (!Asm.getBackend().writeNopData(OS, Count))
    529         report_fatal_error("unable to write nop sequence of " +
    530                           Twine(Count) + " bytes");
    531       break;
    532     }
    533 
    534     // Otherwise, write out in multiples of the value size.
    535     for (uint64_t i = 0; i != Count; ++i) {
    536       switch (AF.getValueSize()) {
    537       default: llvm_unreachable("Invalid size!");
    538       case 1: OS << char(AF.getValue()); break;
    539       case 2:
    540         support::endian::write<uint16_t>(OS, AF.getValue(), Endian);
    541         break;
    542       case 4:
    543         support::endian::write<uint32_t>(OS, AF.getValue(), Endian);
    544         break;
    545       case 8:
    546         support::endian::write<uint64_t>(OS, AF.getValue(), Endian);
    547         break;
    548       }
    549     }
    550     break;
    551   }
    552 
    553   case MCFragment::FT_Data:
    554     ++stats::EmittedDataFragments;
    555     OS << cast<MCDataFragment>(F).getContents();
    556     break;
    557 
    558   case MCFragment::FT_Relaxable:
    559     ++stats::EmittedRelaxableFragments;
    560     OS << cast<MCRelaxableFragment>(F).getContents();
    561     break;
    562 
    563   case MCFragment::FT_CompactEncodedInst:
    564     ++stats::EmittedCompactEncodedInstFragments;
    565     OS << cast<MCCompactEncodedInstFragment>(F).getContents();
    566     break;
    567 
    568   case MCFragment::FT_Fill: {
    569     ++stats::EmittedFillFragments;
    570     const MCFillFragment &FF = cast<MCFillFragment>(F);
    571     uint64_t V = FF.getValue();
    572     unsigned VSize = FF.getValueSize();
    573     const unsigned MaxChunkSize = 16;
    574     char Data[MaxChunkSize];
    575     // Duplicate V into Data as byte vector to reduce number of
    576     // writes done. As such, do endian conversion here.
    577     for (unsigned I = 0; I != VSize; ++I) {
    578       unsigned index = Endian == support::little ? I : (VSize - I - 1);
    579       Data[I] = uint8_t(V >> (index * 8));
    580     }
    581     for (unsigned I = VSize; I < MaxChunkSize; ++I)
    582       Data[I] = Data[I - VSize];
    583 
    584     // Set to largest multiple of VSize in Data.
    585     const unsigned NumPerChunk = MaxChunkSize / VSize;
    586     // Set ChunkSize to largest multiple of VSize in Data
    587     const unsigned ChunkSize = VSize * NumPerChunk;
    588 
    589     // Do copies by chunk.
    590     StringRef Ref(Data, ChunkSize);
    591     for (uint64_t I = 0, E = FragmentSize / ChunkSize; I != E; ++I)
    592       OS << Ref;
    593 
    594     // do remainder if needed.
    595     unsigned TrailingCount = FragmentSize % ChunkSize;
    596     if (TrailingCount)
    597       OS.write(Data, TrailingCount);
    598     break;
    599   }
    600 
    601   case MCFragment::FT_LEB: {
    602     const MCLEBFragment &LF = cast<MCLEBFragment>(F);
    603     OS << LF.getContents();
    604     break;
    605   }
    606 
    607   case MCFragment::FT_Padding: {
    608     if (!Asm.getBackend().writeNopData(OS, FragmentSize))
    609       report_fatal_error("unable to write nop sequence of " +
    610                          Twine(FragmentSize) + " bytes");
    611     break;
    612   }
    613 
    614   case MCFragment::FT_SymbolId: {
    615     const MCSymbolIdFragment &SF = cast<MCSymbolIdFragment>(F);
    616     support::endian::write<uint32_t>(OS, SF.getSymbol()->getIndex(), Endian);
    617     break;
    618   }
    619 
    620   case MCFragment::FT_Org: {
    621     ++stats::EmittedOrgFragments;
    622     const MCOrgFragment &OF = cast<MCOrgFragment>(F);
    623 
    624     for (uint64_t i = 0, e = FragmentSize; i != e; ++i)
    625       OS << char(OF.getValue());
    626 
    627     break;
    628   }
    629 
    630   case MCFragment::FT_Dwarf: {
    631     const MCDwarfLineAddrFragment &OF = cast<MCDwarfLineAddrFragment>(F);
    632     OS << OF.getContents();
    633     break;
    634   }
    635   case MCFragment::FT_DwarfFrame: {
    636     const MCDwarfCallFrameFragment &CF = cast<MCDwarfCallFrameFragment>(F);
    637     OS << CF.getContents();
    638     break;
    639   }
    640   case MCFragment::FT_CVInlineLines: {
    641     const auto &OF = cast<MCCVInlineLineTableFragment>(F);
    642     OS << OF.getContents();
    643     break;
    644   }
    645   case MCFragment::FT_CVDefRange: {
    646     const auto &DRF = cast<MCCVDefRangeFragment>(F);
    647     OS << DRF.getContents();
    648     break;
    649   }
    650   case MCFragment::FT_Dummy:
    651     llvm_unreachable("Should not have been added");
    652   }
    653 
    654   assert(OS.tell() - Start == FragmentSize &&
    655          "The stream should advance by fragment size");
    656 }
    657 
    658 void MCAssembler::writeSectionData(raw_ostream &OS, const MCSection *Sec,
    659                                    const MCAsmLayout &Layout) const {
    660   assert(getBackendPtr() && "Expected assembler backend");
    661 
    662   // Ignore virtual sections.
    663   if (Sec->isVirtualSection()) {
    664     assert(Layout.getSectionFileSize(Sec) == 0 && "Invalid size for section!");
    665 
    666     // Check that contents are only things legal inside a virtual section.
    667     for (const MCFragment &F : *Sec) {
    668       switch (F.getKind()) {
    669       default: llvm_unreachable("Invalid fragment in virtual section!");
    670       case MCFragment::FT_Data: {
    671         // Check that we aren't trying to write a non-zero contents (or fixups)
    672         // into a virtual section. This is to support clients which use standard
    673         // directives to fill the contents of virtual sections.
    674         const MCDataFragment &DF = cast<MCDataFragment>(F);
    675         if (DF.fixup_begin() != DF.fixup_end())
    676           report_fatal_error("cannot have fixups in virtual section!");
    677         for (unsigned i = 0, e = DF.getContents().size(); i != e; ++i)
    678           if (DF.getContents()[i]) {
    679             if (auto *ELFSec = dyn_cast<const MCSectionELF>(Sec))
    680               report_fatal_error("non-zero initializer found in section '" +
    681                   ELFSec->getSectionName() + "'");
    682             else
    683               report_fatal_error("non-zero initializer found in virtual section");
    684           }
    685         break;
    686       }
    687       case MCFragment::FT_Align:
    688         // Check that we aren't trying to write a non-zero value into a virtual
    689         // section.
    690         assert((cast<MCAlignFragment>(F).getValueSize() == 0 ||
    691                 cast<MCAlignFragment>(F).getValue() == 0) &&
    692                "Invalid align in virtual section!");
    693         break;
    694       case MCFragment::FT_Fill:
    695         assert((cast<MCFillFragment>(F).getValue() == 0) &&
    696                "Invalid fill in virtual section!");
    697         break;
    698       }
    699     }
    700 
    701     return;
    702   }
    703 
    704   uint64_t Start = OS.tell();
    705   (void)Start;
    706 
    707   for (const MCFragment &F : *Sec)
    708     writeFragment(OS, *this, Layout, F);
    709 
    710   assert(OS.tell() - Start == Layout.getSectionAddressSize(Sec));
    711 }
    712 
    713 std::tuple<MCValue, uint64_t, bool>
    714 MCAssembler::handleFixup(const MCAsmLayout &Layout, MCFragment &F,
    715                          const MCFixup &Fixup) {
    716   // Evaluate the fixup.
    717   MCValue Target;
    718   uint64_t FixedValue;
    719   bool WasForced;
    720   bool IsResolved = evaluateFixup(Layout, Fixup, &F, Target, FixedValue,
    721                                   WasForced);
    722   if (!IsResolved) {
    723     // The fixup was unresolved, we need a relocation. Inform the object
    724     // writer of the relocation, and give it an opportunity to adjust the
    725     // fixup value if need be.
    726     if (Target.getSymA() && Target.getSymB() &&
    727         getBackend().requiresDiffExpressionRelocations()) {
    728       // The fixup represents the difference between two symbols, which the
    729       // backend has indicated must be resolved at link time. Split up the fixup
    730       // into two relocations, one for the add, and one for the sub, and emit
    731       // both of these. The constant will be associated with the add half of the
    732       // expression.
    733       MCFixup FixupAdd = MCFixup::createAddFor(Fixup);
    734       MCValue TargetAdd =
    735           MCValue::get(Target.getSymA(), nullptr, Target.getConstant());
    736       getWriter().recordRelocation(*this, Layout, &F, FixupAdd, TargetAdd,
    737                                    FixedValue);
    738       MCFixup FixupSub = MCFixup::createSubFor(Fixup);
    739       MCValue TargetSub = MCValue::get(Target.getSymB());
    740       getWriter().recordRelocation(*this, Layout, &F, FixupSub, TargetSub,
    741                                    FixedValue);
    742     } else {
    743       getWriter().recordRelocation(*this, Layout, &F, Fixup, Target,
    744                                    FixedValue);
    745     }
    746   }
    747   return std::make_tuple(Target, FixedValue, IsResolved);
    748 }
    749 
    750 void MCAssembler::layout(MCAsmLayout &Layout) {
    751   assert(getBackendPtr() && "Expected assembler backend");
    752   DEBUG_WITH_TYPE("mc-dump", {
    753       errs() << "assembler backend - pre-layout\n--\n";
    754       dump(); });
    755 
    756   // Create dummy fragments and assign section ordinals.
    757   unsigned SectionIndex = 0;
    758   for (MCSection &Sec : *this) {
    759     // Create dummy fragments to eliminate any empty sections, this simplifies
    760     // layout.
    761     if (Sec.getFragmentList().empty())
    762       new MCDataFragment(&Sec);
    763 
    764     Sec.setOrdinal(SectionIndex++);
    765   }
    766 
    767   // Assign layout order indices to sections and fragments.
    768   for (unsigned i = 0, e = Layout.getSectionOrder().size(); i != e; ++i) {
    769     MCSection *Sec = Layout.getSectionOrder()[i];
    770     Sec->setLayoutOrder(i);
    771 
    772     unsigned FragmentIndex = 0;
    773     for (MCFragment &Frag : *Sec)
    774       Frag.setLayoutOrder(FragmentIndex++);
    775   }
    776 
    777   // Layout until everything fits.
    778   while (layoutOnce(Layout))
    779     if (getContext().hadError())
    780       return;
    781 
    782   DEBUG_WITH_TYPE("mc-dump", {
    783       errs() << "assembler backend - post-relaxation\n--\n";
    784       dump(); });
    785 
    786   // Finalize the layout, including fragment lowering.
    787   finishLayout(Layout);
    788 
    789   DEBUG_WITH_TYPE("mc-dump", {
    790       errs() << "assembler backend - final-layout\n--\n";
    791       dump(); });
    792 
    793   // Allow the object writer a chance to perform post-layout binding (for
    794   // example, to set the index fields in the symbol data).
    795   getWriter().executePostLayoutBinding(*this, Layout);
    796 
    797   // Evaluate and apply the fixups, generating relocation entries as necessary.
    798   for (MCSection &Sec : *this) {
    799     for (MCFragment &Frag : Sec) {
    800       // Data and relaxable fragments both have fixups.  So only process
    801       // those here.
    802       // FIXME: Is there a better way to do this?  MCEncodedFragmentWithFixups
    803       // being templated makes this tricky.
    804       if (isa<MCEncodedFragment>(&Frag) &&
    805           isa<MCCompactEncodedInstFragment>(&Frag))
    806         continue;
    807       if (!isa<MCEncodedFragment>(&Frag) && !isa<MCCVDefRangeFragment>(&Frag))
    808         continue;
    809       ArrayRef<MCFixup> Fixups;
    810       MutableArrayRef<char> Contents;
    811       const MCSubtargetInfo *STI = nullptr;
    812       if (auto *FragWithFixups = dyn_cast<MCDataFragment>(&Frag)) {
    813         Fixups = FragWithFixups->getFixups();
    814         Contents = FragWithFixups->getContents();
    815         STI = FragWithFixups->getSubtargetInfo();
    816         assert(!FragWithFixups->hasInstructions() || STI != nullptr);
    817       } else if (auto *FragWithFixups = dyn_cast<MCRelaxableFragment>(&Frag)) {
    818         Fixups = FragWithFixups->getFixups();
    819         Contents = FragWithFixups->getContents();
    820         STI = FragWithFixups->getSubtargetInfo();
    821         assert(!FragWithFixups->hasInstructions() || STI != nullptr);
    822       } else if (auto *FragWithFixups = dyn_cast<MCCVDefRangeFragment>(&Frag)) {
    823         Fixups = FragWithFixups->getFixups();
    824         Contents = FragWithFixups->getContents();
    825       } else if (auto *FragWithFixups = dyn_cast<MCDwarfLineAddrFragment>(&Frag)) {
    826         Fixups = FragWithFixups->getFixups();
    827         Contents = FragWithFixups->getContents();
    828       } else
    829         llvm_unreachable("Unknown fragment with fixups!");
    830       for (const MCFixup &Fixup : Fixups) {
    831         uint64_t FixedValue;
    832         bool IsResolved;
    833         MCValue Target;
    834         std::tie(Target, FixedValue, IsResolved) =
    835             handleFixup(Layout, Frag, Fixup);
    836         getBackend().applyFixup(*this, Fixup, Target, Contents, FixedValue,
    837                                 IsResolved, STI);
    838       }
    839     }
    840   }
    841 }
    842 
    843 void MCAssembler::Finish() {
    844   // Create the layout object.
    845   MCAsmLayout Layout(*this);
    846   layout(Layout);
    847 
    848   // Write the object file.
    849   stats::ObjectBytes += getWriter().writeObject(*this, Layout);
    850 }
    851 
    852 bool MCAssembler::fixupNeedsRelaxation(const MCFixup &Fixup,
    853                                        const MCRelaxableFragment *DF,
    854                                        const MCAsmLayout &Layout) const {
    855   assert(getBackendPtr() && "Expected assembler backend");
    856   MCValue Target;
    857   uint64_t Value;
    858   bool WasForced;
    859   bool Resolved = evaluateFixup(Layout, Fixup, DF, Target, Value, WasForced);
    860   if (Target.getSymA() &&
    861       Target.getSymA()->getKind() == MCSymbolRefExpr::VK_X86_ABS8 &&
    862       Fixup.getKind() == FK_Data_1)
    863     return false;
    864   return getBackend().fixupNeedsRelaxationAdvanced(Fixup, Resolved, Value, DF,
    865                                                    Layout, WasForced);
    866 }
    867 
    868 bool MCAssembler::fragmentNeedsRelaxation(const MCRelaxableFragment *F,
    869                                           const MCAsmLayout &Layout) const {
    870   assert(getBackendPtr() && "Expected assembler backend");
    871   // If this inst doesn't ever need relaxation, ignore it. This occurs when we
    872   // are intentionally pushing out inst fragments, or because we relaxed a
    873   // previous instruction to one that doesn't need relaxation.
    874   if (!getBackend().mayNeedRelaxation(F->getInst(), *F->getSubtargetInfo()))
    875     return false;
    876 
    877   for (const MCFixup &Fixup : F->getFixups())
    878     if (fixupNeedsRelaxation(Fixup, F, Layout))
    879       return true;
    880 
    881   return false;
    882 }
    883 
    884 bool MCAssembler::relaxInstruction(MCAsmLayout &Layout,
    885                                    MCRelaxableFragment &F) {
    886   assert(getEmitterPtr() &&
    887          "Expected CodeEmitter defined for relaxInstruction");
    888   if (!fragmentNeedsRelaxation(&F, Layout))
    889     return false;
    890 
    891   ++stats::RelaxedInstructions;
    892 
    893   // FIXME-PERF: We could immediately lower out instructions if we can tell
    894   // they are fully resolved, to avoid retesting on later passes.
    895 
    896   // Relax the fragment.
    897 
    898   MCInst Relaxed;
    899   getBackend().relaxInstruction(F.getInst(), *F.getSubtargetInfo(), Relaxed);
    900 
    901   // Encode the new instruction.
    902   //
    903   // FIXME-PERF: If it matters, we could let the target do this. It can
    904   // probably do so more efficiently in many cases.
    905   SmallVector<MCFixup, 4> Fixups;
    906   SmallString<256> Code;
    907   raw_svector_ostream VecOS(Code);
    908   getEmitter().encodeInstruction(Relaxed, VecOS, Fixups, *F.getSubtargetInfo());
    909 
    910   // Update the fragment.
    911   F.setInst(Relaxed);
    912   F.getContents() = Code;
    913   F.getFixups() = Fixups;
    914 
    915   return true;
    916 }
    917 
    918 bool MCAssembler::relaxPaddingFragment(MCAsmLayout &Layout,
    919                                        MCPaddingFragment &PF) {
    920   assert(getBackendPtr() && "Expected assembler backend");
    921   uint64_t OldSize = PF.getSize();
    922   if (!getBackend().relaxFragment(&PF, Layout))
    923     return false;
    924   uint64_t NewSize = PF.getSize();
    925 
    926   ++stats::PaddingFragmentsRelaxations;
    927   stats::PaddingFragmentsBytes += NewSize;
    928   stats::PaddingFragmentsBytes -= OldSize;
    929   return true;
    930 }
    931 
    932 bool MCAssembler::relaxLEB(MCAsmLayout &Layout, MCLEBFragment &LF) {
    933   uint64_t OldSize = LF.getContents().size();
    934   int64_t Value;
    935   bool Abs = LF.getValue().evaluateKnownAbsolute(Value, Layout);
    936   if (!Abs)
    937     report_fatal_error("sleb128 and uleb128 expressions must be absolute");
    938   SmallString<8> &Data = LF.getContents();
    939   Data.clear();
    940   raw_svector_ostream OSE(Data);
    941   // The compiler can generate EH table assembly that is impossible to assemble
    942   // without either adding padding to an LEB fragment or adding extra padding
    943   // to a later alignment fragment. To accommodate such tables, relaxation can
    944   // only increase an LEB fragment size here, not decrease it. See PR35809.
    945   if (LF.isSigned())
    946     encodeSLEB128(Value, OSE, OldSize);
    947   else
    948     encodeULEB128(Value, OSE, OldSize);
    949   return OldSize != LF.getContents().size();
    950 }
    951 
    952 bool MCAssembler::relaxDwarfLineAddr(MCAsmLayout &Layout,
    953                                      MCDwarfLineAddrFragment &DF) {
    954   MCContext &Context = Layout.getAssembler().getContext();
    955   uint64_t OldSize = DF.getContents().size();
    956   int64_t AddrDelta;
    957   bool Abs;
    958   if (getBackend().requiresDiffExpressionRelocations())
    959     Abs = DF.getAddrDelta().evaluateAsAbsolute(AddrDelta, Layout);
    960   else {
    961     Abs = DF.getAddrDelta().evaluateKnownAbsolute(AddrDelta, Layout);
    962     assert(Abs && "We created a line delta with an invalid expression");
    963   }
    964   int64_t LineDelta;
    965   LineDelta = DF.getLineDelta();
    966   SmallVectorImpl<char> &Data = DF.getContents();
    967   Data.clear();
    968   raw_svector_ostream OSE(Data);
    969   DF.getFixups().clear();
    970 
    971   if (Abs) {
    972     MCDwarfLineAddr::Encode(Context, getDWARFLinetableParams(), LineDelta,
    973                             AddrDelta, OSE);
    974   } else {
    975     uint32_t Offset;
    976     uint32_t Size;
    977     bool SetDelta = MCDwarfLineAddr::FixedEncode(Context,
    978                                                  getDWARFLinetableParams(),
    979                                                  LineDelta, AddrDelta,
    980                                                  OSE, &Offset, &Size);
    981     // Add Fixups for address delta or new address.
    982     const MCExpr *FixupExpr;
    983     if (SetDelta) {
    984       FixupExpr = &DF.getAddrDelta();
    985     } else {
    986       const MCBinaryExpr *ABE = cast<MCBinaryExpr>(&DF.getAddrDelta());
    987       FixupExpr = ABE->getLHS();
    988     }
    989     DF.getFixups().push_back(
    990         MCFixup::create(Offset, FixupExpr,
    991                         MCFixup::getKindForSize(Size, false /*isPCRel*/)));
    992   }
    993 
    994   return OldSize != Data.size();
    995 }
    996 
    997 bool MCAssembler::relaxDwarfCallFrameFragment(MCAsmLayout &Layout,
    998                                               MCDwarfCallFrameFragment &DF) {
    999   MCContext &Context = Layout.getAssembler().getContext();
   1000   uint64_t OldSize = DF.getContents().size();
   1001   int64_t AddrDelta;
   1002   bool Abs = DF.getAddrDelta().evaluateKnownAbsolute(AddrDelta, Layout);
   1003   assert(Abs && "We created call frame with an invalid expression");
   1004   (void) Abs;
   1005   SmallString<8> &Data = DF.getContents();
   1006   Data.clear();
   1007   raw_svector_ostream OSE(Data);
   1008   MCDwarfFrameEmitter::EncodeAdvanceLoc(Context, AddrDelta, OSE);
   1009   return OldSize != Data.size();
   1010 }
   1011 
   1012 bool MCAssembler::relaxCVInlineLineTable(MCAsmLayout &Layout,
   1013                                          MCCVInlineLineTableFragment &F) {
   1014   unsigned OldSize = F.getContents().size();
   1015   getContext().getCVContext().encodeInlineLineTable(Layout, F);
   1016   return OldSize != F.getContents().size();
   1017 }
   1018 
   1019 bool MCAssembler::relaxCVDefRange(MCAsmLayout &Layout,
   1020                                   MCCVDefRangeFragment &F) {
   1021   unsigned OldSize = F.getContents().size();
   1022   getContext().getCVContext().encodeDefRange(Layout, F);
   1023   return OldSize != F.getContents().size();
   1024 }
   1025 
   1026 bool MCAssembler::layoutSectionOnce(MCAsmLayout &Layout, MCSection &Sec) {
   1027   // Holds the first fragment which needed relaxing during this layout. It will
   1028   // remain NULL if none were relaxed.
   1029   // When a fragment is relaxed, all the fragments following it should get
   1030   // invalidated because their offset is going to change.
   1031   MCFragment *FirstRelaxedFragment = nullptr;
   1032 
   1033   // Attempt to relax all the fragments in the section.
   1034   for (MCSection::iterator I = Sec.begin(), IE = Sec.end(); I != IE; ++I) {
   1035     // Check if this is a fragment that needs relaxation.
   1036     bool RelaxedFrag = false;
   1037     switch(I->getKind()) {
   1038     default:
   1039       break;
   1040     case MCFragment::FT_Relaxable:
   1041       assert(!getRelaxAll() &&
   1042              "Did not expect a MCRelaxableFragment in RelaxAll mode");
   1043       RelaxedFrag = relaxInstruction(Layout, *cast<MCRelaxableFragment>(I));
   1044       break;
   1045     case MCFragment::FT_Dwarf:
   1046       RelaxedFrag = relaxDwarfLineAddr(Layout,
   1047                                        *cast<MCDwarfLineAddrFragment>(I));
   1048       break;
   1049     case MCFragment::FT_DwarfFrame:
   1050       RelaxedFrag =
   1051         relaxDwarfCallFrameFragment(Layout,
   1052                                     *cast<MCDwarfCallFrameFragment>(I));
   1053       break;
   1054     case MCFragment::FT_LEB:
   1055       RelaxedFrag = relaxLEB(Layout, *cast<MCLEBFragment>(I));
   1056       break;
   1057     case MCFragment::FT_Padding:
   1058       RelaxedFrag = relaxPaddingFragment(Layout, *cast<MCPaddingFragment>(I));
   1059       break;
   1060     case MCFragment::FT_CVInlineLines:
   1061       RelaxedFrag =
   1062           relaxCVInlineLineTable(Layout, *cast<MCCVInlineLineTableFragment>(I));
   1063       break;
   1064     case MCFragment::FT_CVDefRange:
   1065       RelaxedFrag = relaxCVDefRange(Layout, *cast<MCCVDefRangeFragment>(I));
   1066       break;
   1067     }
   1068     if (RelaxedFrag && !FirstRelaxedFragment)
   1069       FirstRelaxedFragment = &*I;
   1070   }
   1071   if (FirstRelaxedFragment) {
   1072     Layout.invalidateFragmentsFrom(FirstRelaxedFragment);
   1073     return true;
   1074   }
   1075   return false;
   1076 }
   1077 
   1078 bool MCAssembler::layoutOnce(MCAsmLayout &Layout) {
   1079   ++stats::RelaxationSteps;
   1080 
   1081   bool WasRelaxed = false;
   1082   for (iterator it = begin(), ie = end(); it != ie; ++it) {
   1083     MCSection &Sec = *it;
   1084     while (layoutSectionOnce(Layout, Sec))
   1085       WasRelaxed = true;
   1086   }
   1087 
   1088   return WasRelaxed;
   1089 }
   1090 
   1091 void MCAssembler::finishLayout(MCAsmLayout &Layout) {
   1092   assert(getBackendPtr() && "Expected assembler backend");
   1093   // The layout is done. Mark every fragment as valid.
   1094   for (unsigned int i = 0, n = Layout.getSectionOrder().size(); i != n; ++i) {
   1095     MCSection &Section = *Layout.getSectionOrder()[i];
   1096     Layout.getFragmentOffset(&*Section.rbegin());
   1097     computeFragmentSize(Layout, *Section.rbegin());
   1098   }
   1099   getBackend().finishLayout(*this, Layout);
   1100 }
   1101 
   1102 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
   1103 LLVM_DUMP_METHOD void MCAssembler::dump() const{
   1104   raw_ostream &OS = errs();
   1105 
   1106   OS << "<MCAssembler\n";
   1107   OS << "  Sections:[\n    ";
   1108   for (const_iterator it = begin(), ie = end(); it != ie; ++it) {
   1109     if (it != begin()) OS << ",\n    ";
   1110     it->dump();
   1111   }
   1112   OS << "],\n";
   1113   OS << "  Symbols:[";
   1114 
   1115   for (const_symbol_iterator it = symbol_begin(), ie = symbol_end(); it != ie; ++it) {
   1116     if (it != symbol_begin()) OS << ",\n           ";
   1117     OS << "(";
   1118     it->dump();
   1119     OS << ", Index:" << it->getIndex() << ", ";
   1120     OS << ")";
   1121   }
   1122   OS << "]>\n";
   1123 }
   1124 #endif
   1125