xref: /llvm-project/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp (revision b42fa2e5c60b5748aad360fae6810e9fdbe8b4d1)
1 //===--- Bitcode/Writer/BitcodeWriter.cpp - Bitcode Writer ----------------===//
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 // Bitcode writer implementation.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "ValueEnumerator.h"
15 #include "llvm/ADT/STLExtras.h"
16 #include "llvm/ADT/Triple.h"
17 #include "llvm/Analysis/BlockFrequencyInfo.h"
18 #include "llvm/Analysis/BlockFrequencyInfoImpl.h"
19 #include "llvm/Analysis/BranchProbabilityInfo.h"
20 #include "llvm/Analysis/LoopInfo.h"
21 #include "llvm/Bitcode/BitstreamWriter.h"
22 #include "llvm/Bitcode/LLVMBitCodes.h"
23 #include "llvm/Bitcode/ReaderWriter.h"
24 #include "llvm/IR/CallSite.h"
25 #include "llvm/IR/Constants.h"
26 #include "llvm/IR/DebugInfoMetadata.h"
27 #include "llvm/IR/DerivedTypes.h"
28 #include "llvm/IR/Dominators.h"
29 #include "llvm/IR/InlineAsm.h"
30 #include "llvm/IR/Instructions.h"
31 #include "llvm/IR/IntrinsicInst.h"
32 #include "llvm/IR/LLVMContext.h"
33 #include "llvm/IR/Module.h"
34 #include "llvm/IR/Operator.h"
35 #include "llvm/IR/UseListOrder.h"
36 #include "llvm/IR/ValueSymbolTable.h"
37 #include "llvm/Support/CommandLine.h"
38 #include "llvm/Support/ErrorHandling.h"
39 #include "llvm/Support/MathExtras.h"
40 #include "llvm/Support/Program.h"
41 #include "llvm/Support/raw_ostream.h"
42 #include <cctype>
43 #include <map>
44 using namespace llvm;
45 
46 /// These are manifest constants used by the bitcode writer. They do not need to
47 /// be kept in sync with the reader, but need to be consistent within this file.
48 enum {
49   // VALUE_SYMTAB_BLOCK abbrev id's.
50   VST_ENTRY_8_ABBREV = bitc::FIRST_APPLICATION_ABBREV,
51   VST_ENTRY_7_ABBREV,
52   VST_ENTRY_6_ABBREV,
53   VST_BBENTRY_6_ABBREV,
54 
55   // CONSTANTS_BLOCK abbrev id's.
56   CONSTANTS_SETTYPE_ABBREV = bitc::FIRST_APPLICATION_ABBREV,
57   CONSTANTS_INTEGER_ABBREV,
58   CONSTANTS_CE_CAST_Abbrev,
59   CONSTANTS_NULL_Abbrev,
60 
61   // FUNCTION_BLOCK abbrev id's.
62   FUNCTION_INST_LOAD_ABBREV = bitc::FIRST_APPLICATION_ABBREV,
63   FUNCTION_INST_BINOP_ABBREV,
64   FUNCTION_INST_BINOP_FLAGS_ABBREV,
65   FUNCTION_INST_CAST_ABBREV,
66   FUNCTION_INST_RET_VOID_ABBREV,
67   FUNCTION_INST_RET_VAL_ABBREV,
68   FUNCTION_INST_UNREACHABLE_ABBREV,
69   FUNCTION_INST_GEP_ABBREV,
70 };
71 
72 static unsigned GetEncodedCastOpcode(unsigned Opcode) {
73   switch (Opcode) {
74   default: llvm_unreachable("Unknown cast instruction!");
75   case Instruction::Trunc   : return bitc::CAST_TRUNC;
76   case Instruction::ZExt    : return bitc::CAST_ZEXT;
77   case Instruction::SExt    : return bitc::CAST_SEXT;
78   case Instruction::FPToUI  : return bitc::CAST_FPTOUI;
79   case Instruction::FPToSI  : return bitc::CAST_FPTOSI;
80   case Instruction::UIToFP  : return bitc::CAST_UITOFP;
81   case Instruction::SIToFP  : return bitc::CAST_SITOFP;
82   case Instruction::FPTrunc : return bitc::CAST_FPTRUNC;
83   case Instruction::FPExt   : return bitc::CAST_FPEXT;
84   case Instruction::PtrToInt: return bitc::CAST_PTRTOINT;
85   case Instruction::IntToPtr: return bitc::CAST_INTTOPTR;
86   case Instruction::BitCast : return bitc::CAST_BITCAST;
87   case Instruction::AddrSpaceCast: return bitc::CAST_ADDRSPACECAST;
88   }
89 }
90 
91 static unsigned GetEncodedBinaryOpcode(unsigned Opcode) {
92   switch (Opcode) {
93   default: llvm_unreachable("Unknown binary instruction!");
94   case Instruction::Add:
95   case Instruction::FAdd: return bitc::BINOP_ADD;
96   case Instruction::Sub:
97   case Instruction::FSub: return bitc::BINOP_SUB;
98   case Instruction::Mul:
99   case Instruction::FMul: return bitc::BINOP_MUL;
100   case Instruction::UDiv: return bitc::BINOP_UDIV;
101   case Instruction::FDiv:
102   case Instruction::SDiv: return bitc::BINOP_SDIV;
103   case Instruction::URem: return bitc::BINOP_UREM;
104   case Instruction::FRem:
105   case Instruction::SRem: return bitc::BINOP_SREM;
106   case Instruction::Shl:  return bitc::BINOP_SHL;
107   case Instruction::LShr: return bitc::BINOP_LSHR;
108   case Instruction::AShr: return bitc::BINOP_ASHR;
109   case Instruction::And:  return bitc::BINOP_AND;
110   case Instruction::Or:   return bitc::BINOP_OR;
111   case Instruction::Xor:  return bitc::BINOP_XOR;
112   }
113 }
114 
115 static unsigned GetEncodedRMWOperation(AtomicRMWInst::BinOp Op) {
116   switch (Op) {
117   default: llvm_unreachable("Unknown RMW operation!");
118   case AtomicRMWInst::Xchg: return bitc::RMW_XCHG;
119   case AtomicRMWInst::Add: return bitc::RMW_ADD;
120   case AtomicRMWInst::Sub: return bitc::RMW_SUB;
121   case AtomicRMWInst::And: return bitc::RMW_AND;
122   case AtomicRMWInst::Nand: return bitc::RMW_NAND;
123   case AtomicRMWInst::Or: return bitc::RMW_OR;
124   case AtomicRMWInst::Xor: return bitc::RMW_XOR;
125   case AtomicRMWInst::Max: return bitc::RMW_MAX;
126   case AtomicRMWInst::Min: return bitc::RMW_MIN;
127   case AtomicRMWInst::UMax: return bitc::RMW_UMAX;
128   case AtomicRMWInst::UMin: return bitc::RMW_UMIN;
129   }
130 }
131 
132 static unsigned GetEncodedOrdering(AtomicOrdering Ordering) {
133   switch (Ordering) {
134   case NotAtomic: return bitc::ORDERING_NOTATOMIC;
135   case Unordered: return bitc::ORDERING_UNORDERED;
136   case Monotonic: return bitc::ORDERING_MONOTONIC;
137   case Acquire: return bitc::ORDERING_ACQUIRE;
138   case Release: return bitc::ORDERING_RELEASE;
139   case AcquireRelease: return bitc::ORDERING_ACQREL;
140   case SequentiallyConsistent: return bitc::ORDERING_SEQCST;
141   }
142   llvm_unreachable("Invalid ordering");
143 }
144 
145 static unsigned GetEncodedSynchScope(SynchronizationScope SynchScope) {
146   switch (SynchScope) {
147   case SingleThread: return bitc::SYNCHSCOPE_SINGLETHREAD;
148   case CrossThread: return bitc::SYNCHSCOPE_CROSSTHREAD;
149   }
150   llvm_unreachable("Invalid synch scope");
151 }
152 
153 static void WriteStringRecord(unsigned Code, StringRef Str,
154                               unsigned AbbrevToUse, BitstreamWriter &Stream) {
155   SmallVector<unsigned, 64> Vals;
156 
157   // Code: [strchar x N]
158   for (unsigned i = 0, e = Str.size(); i != e; ++i) {
159     if (AbbrevToUse && !BitCodeAbbrevOp::isChar6(Str[i]))
160       AbbrevToUse = 0;
161     Vals.push_back(Str[i]);
162   }
163 
164   // Emit the finished record.
165   Stream.EmitRecord(Code, Vals, AbbrevToUse);
166 }
167 
168 static uint64_t getAttrKindEncoding(Attribute::AttrKind Kind) {
169   switch (Kind) {
170   case Attribute::Alignment:
171     return bitc::ATTR_KIND_ALIGNMENT;
172   case Attribute::AlwaysInline:
173     return bitc::ATTR_KIND_ALWAYS_INLINE;
174   case Attribute::ArgMemOnly:
175     return bitc::ATTR_KIND_ARGMEMONLY;
176   case Attribute::Builtin:
177     return bitc::ATTR_KIND_BUILTIN;
178   case Attribute::ByVal:
179     return bitc::ATTR_KIND_BY_VAL;
180   case Attribute::Convergent:
181     return bitc::ATTR_KIND_CONVERGENT;
182   case Attribute::InAlloca:
183     return bitc::ATTR_KIND_IN_ALLOCA;
184   case Attribute::Cold:
185     return bitc::ATTR_KIND_COLD;
186   case Attribute::InaccessibleMemOnly:
187     return bitc::ATTR_KIND_INACCESSIBLEMEM_ONLY;
188   case Attribute::InaccessibleMemOrArgMemOnly:
189     return bitc::ATTR_KIND_INACCESSIBLEMEM_OR_ARGMEMONLY;
190   case Attribute::InlineHint:
191     return bitc::ATTR_KIND_INLINE_HINT;
192   case Attribute::InReg:
193     return bitc::ATTR_KIND_IN_REG;
194   case Attribute::JumpTable:
195     return bitc::ATTR_KIND_JUMP_TABLE;
196   case Attribute::MinSize:
197     return bitc::ATTR_KIND_MIN_SIZE;
198   case Attribute::Naked:
199     return bitc::ATTR_KIND_NAKED;
200   case Attribute::Nest:
201     return bitc::ATTR_KIND_NEST;
202   case Attribute::NoAlias:
203     return bitc::ATTR_KIND_NO_ALIAS;
204   case Attribute::NoBuiltin:
205     return bitc::ATTR_KIND_NO_BUILTIN;
206   case Attribute::NoCapture:
207     return bitc::ATTR_KIND_NO_CAPTURE;
208   case Attribute::NoDuplicate:
209     return bitc::ATTR_KIND_NO_DUPLICATE;
210   case Attribute::NoImplicitFloat:
211     return bitc::ATTR_KIND_NO_IMPLICIT_FLOAT;
212   case Attribute::NoInline:
213     return bitc::ATTR_KIND_NO_INLINE;
214   case Attribute::NoRecurse:
215     return bitc::ATTR_KIND_NO_RECURSE;
216   case Attribute::NonLazyBind:
217     return bitc::ATTR_KIND_NON_LAZY_BIND;
218   case Attribute::NonNull:
219     return bitc::ATTR_KIND_NON_NULL;
220   case Attribute::Dereferenceable:
221     return bitc::ATTR_KIND_DEREFERENCEABLE;
222   case Attribute::DereferenceableOrNull:
223     return bitc::ATTR_KIND_DEREFERENCEABLE_OR_NULL;
224   case Attribute::NoRedZone:
225     return bitc::ATTR_KIND_NO_RED_ZONE;
226   case Attribute::NoReturn:
227     return bitc::ATTR_KIND_NO_RETURN;
228   case Attribute::NoUnwind:
229     return bitc::ATTR_KIND_NO_UNWIND;
230   case Attribute::OptimizeForSize:
231     return bitc::ATTR_KIND_OPTIMIZE_FOR_SIZE;
232   case Attribute::OptimizeNone:
233     return bitc::ATTR_KIND_OPTIMIZE_NONE;
234   case Attribute::ReadNone:
235     return bitc::ATTR_KIND_READ_NONE;
236   case Attribute::ReadOnly:
237     return bitc::ATTR_KIND_READ_ONLY;
238   case Attribute::Returned:
239     return bitc::ATTR_KIND_RETURNED;
240   case Attribute::ReturnsTwice:
241     return bitc::ATTR_KIND_RETURNS_TWICE;
242   case Attribute::SExt:
243     return bitc::ATTR_KIND_S_EXT;
244   case Attribute::StackAlignment:
245     return bitc::ATTR_KIND_STACK_ALIGNMENT;
246   case Attribute::StackProtect:
247     return bitc::ATTR_KIND_STACK_PROTECT;
248   case Attribute::StackProtectReq:
249     return bitc::ATTR_KIND_STACK_PROTECT_REQ;
250   case Attribute::StackProtectStrong:
251     return bitc::ATTR_KIND_STACK_PROTECT_STRONG;
252   case Attribute::SafeStack:
253     return bitc::ATTR_KIND_SAFESTACK;
254   case Attribute::StructRet:
255     return bitc::ATTR_KIND_STRUCT_RET;
256   case Attribute::SanitizeAddress:
257     return bitc::ATTR_KIND_SANITIZE_ADDRESS;
258   case Attribute::SanitizeThread:
259     return bitc::ATTR_KIND_SANITIZE_THREAD;
260   case Attribute::SanitizeMemory:
261     return bitc::ATTR_KIND_SANITIZE_MEMORY;
262   case Attribute::UWTable:
263     return bitc::ATTR_KIND_UW_TABLE;
264   case Attribute::ZExt:
265     return bitc::ATTR_KIND_Z_EXT;
266   case Attribute::EndAttrKinds:
267     llvm_unreachable("Can not encode end-attribute kinds marker.");
268   case Attribute::None:
269     llvm_unreachable("Can not encode none-attribute.");
270   }
271 
272   llvm_unreachable("Trying to encode unknown attribute");
273 }
274 
275 static void WriteAttributeGroupTable(const ValueEnumerator &VE,
276                                      BitstreamWriter &Stream) {
277   const std::vector<AttributeSet> &AttrGrps = VE.getAttributeGroups();
278   if (AttrGrps.empty()) return;
279 
280   Stream.EnterSubblock(bitc::PARAMATTR_GROUP_BLOCK_ID, 3);
281 
282   SmallVector<uint64_t, 64> Record;
283   for (unsigned i = 0, e = AttrGrps.size(); i != e; ++i) {
284     AttributeSet AS = AttrGrps[i];
285     for (unsigned i = 0, e = AS.getNumSlots(); i != e; ++i) {
286       AttributeSet A = AS.getSlotAttributes(i);
287 
288       Record.push_back(VE.getAttributeGroupID(A));
289       Record.push_back(AS.getSlotIndex(i));
290 
291       for (AttributeSet::iterator I = AS.begin(0), E = AS.end(0);
292            I != E; ++I) {
293         Attribute Attr = *I;
294         if (Attr.isEnumAttribute()) {
295           Record.push_back(0);
296           Record.push_back(getAttrKindEncoding(Attr.getKindAsEnum()));
297         } else if (Attr.isIntAttribute()) {
298           Record.push_back(1);
299           Record.push_back(getAttrKindEncoding(Attr.getKindAsEnum()));
300           Record.push_back(Attr.getValueAsInt());
301         } else {
302           StringRef Kind = Attr.getKindAsString();
303           StringRef Val = Attr.getValueAsString();
304 
305           Record.push_back(Val.empty() ? 3 : 4);
306           Record.append(Kind.begin(), Kind.end());
307           Record.push_back(0);
308           if (!Val.empty()) {
309             Record.append(Val.begin(), Val.end());
310             Record.push_back(0);
311           }
312         }
313       }
314 
315       Stream.EmitRecord(bitc::PARAMATTR_GRP_CODE_ENTRY, Record);
316       Record.clear();
317     }
318   }
319 
320   Stream.ExitBlock();
321 }
322 
323 static void WriteAttributeTable(const ValueEnumerator &VE,
324                                 BitstreamWriter &Stream) {
325   const std::vector<AttributeSet> &Attrs = VE.getAttributes();
326   if (Attrs.empty()) return;
327 
328   Stream.EnterSubblock(bitc::PARAMATTR_BLOCK_ID, 3);
329 
330   SmallVector<uint64_t, 64> Record;
331   for (unsigned i = 0, e = Attrs.size(); i != e; ++i) {
332     const AttributeSet &A = Attrs[i];
333     for (unsigned i = 0, e = A.getNumSlots(); i != e; ++i)
334       Record.push_back(VE.getAttributeGroupID(A.getSlotAttributes(i)));
335 
336     Stream.EmitRecord(bitc::PARAMATTR_CODE_ENTRY, Record);
337     Record.clear();
338   }
339 
340   Stream.ExitBlock();
341 }
342 
343 /// WriteTypeTable - Write out the type table for a module.
344 static void WriteTypeTable(const ValueEnumerator &VE, BitstreamWriter &Stream) {
345   const ValueEnumerator::TypeList &TypeList = VE.getTypes();
346 
347   Stream.EnterSubblock(bitc::TYPE_BLOCK_ID_NEW, 4 /*count from # abbrevs */);
348   SmallVector<uint64_t, 64> TypeVals;
349 
350   uint64_t NumBits = VE.computeBitsRequiredForTypeIndicies();
351 
352   // Abbrev for TYPE_CODE_POINTER.
353   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
354   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_POINTER));
355   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
356   Abbv->Add(BitCodeAbbrevOp(0));  // Addrspace = 0
357   unsigned PtrAbbrev = Stream.EmitAbbrev(Abbv);
358 
359   // Abbrev for TYPE_CODE_FUNCTION.
360   Abbv = new BitCodeAbbrev();
361   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_FUNCTION));
362   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // isvararg
363   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
364   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
365 
366   unsigned FunctionAbbrev = Stream.EmitAbbrev(Abbv);
367 
368   // Abbrev for TYPE_CODE_STRUCT_ANON.
369   Abbv = new BitCodeAbbrev();
370   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_ANON));
371   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // ispacked
372   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
373   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
374 
375   unsigned StructAnonAbbrev = Stream.EmitAbbrev(Abbv);
376 
377   // Abbrev for TYPE_CODE_STRUCT_NAME.
378   Abbv = new BitCodeAbbrev();
379   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_NAME));
380   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
381   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
382   unsigned StructNameAbbrev = Stream.EmitAbbrev(Abbv);
383 
384   // Abbrev for TYPE_CODE_STRUCT_NAMED.
385   Abbv = new BitCodeAbbrev();
386   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_NAMED));
387   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // ispacked
388   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
389   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
390 
391   unsigned StructNamedAbbrev = Stream.EmitAbbrev(Abbv);
392 
393   // Abbrev for TYPE_CODE_ARRAY.
394   Abbv = new BitCodeAbbrev();
395   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_ARRAY));
396   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // size
397   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
398 
399   unsigned ArrayAbbrev = Stream.EmitAbbrev(Abbv);
400 
401   // Emit an entry count so the reader can reserve space.
402   TypeVals.push_back(TypeList.size());
403   Stream.EmitRecord(bitc::TYPE_CODE_NUMENTRY, TypeVals);
404   TypeVals.clear();
405 
406   // Loop over all of the types, emitting each in turn.
407   for (unsigned i = 0, e = TypeList.size(); i != e; ++i) {
408     Type *T = TypeList[i];
409     int AbbrevToUse = 0;
410     unsigned Code = 0;
411 
412     switch (T->getTypeID()) {
413     case Type::VoidTyID:      Code = bitc::TYPE_CODE_VOID;      break;
414     case Type::HalfTyID:      Code = bitc::TYPE_CODE_HALF;      break;
415     case Type::FloatTyID:     Code = bitc::TYPE_CODE_FLOAT;     break;
416     case Type::DoubleTyID:    Code = bitc::TYPE_CODE_DOUBLE;    break;
417     case Type::X86_FP80TyID:  Code = bitc::TYPE_CODE_X86_FP80;  break;
418     case Type::FP128TyID:     Code = bitc::TYPE_CODE_FP128;     break;
419     case Type::PPC_FP128TyID: Code = bitc::TYPE_CODE_PPC_FP128; break;
420     case Type::LabelTyID:     Code = bitc::TYPE_CODE_LABEL;     break;
421     case Type::MetadataTyID:  Code = bitc::TYPE_CODE_METADATA;  break;
422     case Type::X86_MMXTyID:   Code = bitc::TYPE_CODE_X86_MMX;   break;
423     case Type::TokenTyID:     Code = bitc::TYPE_CODE_TOKEN;     break;
424     case Type::IntegerTyID:
425       // INTEGER: [width]
426       Code = bitc::TYPE_CODE_INTEGER;
427       TypeVals.push_back(cast<IntegerType>(T)->getBitWidth());
428       break;
429     case Type::PointerTyID: {
430       PointerType *PTy = cast<PointerType>(T);
431       // POINTER: [pointee type, address space]
432       Code = bitc::TYPE_CODE_POINTER;
433       TypeVals.push_back(VE.getTypeID(PTy->getElementType()));
434       unsigned AddressSpace = PTy->getAddressSpace();
435       TypeVals.push_back(AddressSpace);
436       if (AddressSpace == 0) AbbrevToUse = PtrAbbrev;
437       break;
438     }
439     case Type::FunctionTyID: {
440       FunctionType *FT = cast<FunctionType>(T);
441       // FUNCTION: [isvararg, retty, paramty x N]
442       Code = bitc::TYPE_CODE_FUNCTION;
443       TypeVals.push_back(FT->isVarArg());
444       TypeVals.push_back(VE.getTypeID(FT->getReturnType()));
445       for (unsigned i = 0, e = FT->getNumParams(); i != e; ++i)
446         TypeVals.push_back(VE.getTypeID(FT->getParamType(i)));
447       AbbrevToUse = FunctionAbbrev;
448       break;
449     }
450     case Type::StructTyID: {
451       StructType *ST = cast<StructType>(T);
452       // STRUCT: [ispacked, eltty x N]
453       TypeVals.push_back(ST->isPacked());
454       // Output all of the element types.
455       for (StructType::element_iterator I = ST->element_begin(),
456            E = ST->element_end(); I != E; ++I)
457         TypeVals.push_back(VE.getTypeID(*I));
458 
459       if (ST->isLiteral()) {
460         Code = bitc::TYPE_CODE_STRUCT_ANON;
461         AbbrevToUse = StructAnonAbbrev;
462       } else {
463         if (ST->isOpaque()) {
464           Code = bitc::TYPE_CODE_OPAQUE;
465         } else {
466           Code = bitc::TYPE_CODE_STRUCT_NAMED;
467           AbbrevToUse = StructNamedAbbrev;
468         }
469 
470         // Emit the name if it is present.
471         if (!ST->getName().empty())
472           WriteStringRecord(bitc::TYPE_CODE_STRUCT_NAME, ST->getName(),
473                             StructNameAbbrev, Stream);
474       }
475       break;
476     }
477     case Type::ArrayTyID: {
478       ArrayType *AT = cast<ArrayType>(T);
479       // ARRAY: [numelts, eltty]
480       Code = bitc::TYPE_CODE_ARRAY;
481       TypeVals.push_back(AT->getNumElements());
482       TypeVals.push_back(VE.getTypeID(AT->getElementType()));
483       AbbrevToUse = ArrayAbbrev;
484       break;
485     }
486     case Type::VectorTyID: {
487       VectorType *VT = cast<VectorType>(T);
488       // VECTOR [numelts, eltty]
489       Code = bitc::TYPE_CODE_VECTOR;
490       TypeVals.push_back(VT->getNumElements());
491       TypeVals.push_back(VE.getTypeID(VT->getElementType()));
492       break;
493     }
494     }
495 
496     // Emit the finished record.
497     Stream.EmitRecord(Code, TypeVals, AbbrevToUse);
498     TypeVals.clear();
499   }
500 
501   Stream.ExitBlock();
502 }
503 
504 static unsigned getEncodedLinkage(const GlobalValue::LinkageTypes Linkage) {
505   switch (Linkage) {
506   case GlobalValue::ExternalLinkage:
507     return 0;
508   case GlobalValue::WeakAnyLinkage:
509     return 16;
510   case GlobalValue::AppendingLinkage:
511     return 2;
512   case GlobalValue::InternalLinkage:
513     return 3;
514   case GlobalValue::LinkOnceAnyLinkage:
515     return 18;
516   case GlobalValue::ExternalWeakLinkage:
517     return 7;
518   case GlobalValue::CommonLinkage:
519     return 8;
520   case GlobalValue::PrivateLinkage:
521     return 9;
522   case GlobalValue::WeakODRLinkage:
523     return 17;
524   case GlobalValue::LinkOnceODRLinkage:
525     return 19;
526   case GlobalValue::AvailableExternallyLinkage:
527     return 12;
528   }
529   llvm_unreachable("Invalid linkage");
530 }
531 
532 static unsigned getEncodedLinkage(const GlobalValue &GV) {
533   return getEncodedLinkage(GV.getLinkage());
534 }
535 
536 static unsigned getEncodedVisibility(const GlobalValue &GV) {
537   switch (GV.getVisibility()) {
538   case GlobalValue::DefaultVisibility:   return 0;
539   case GlobalValue::HiddenVisibility:    return 1;
540   case GlobalValue::ProtectedVisibility: return 2;
541   }
542   llvm_unreachable("Invalid visibility");
543 }
544 
545 static unsigned getEncodedDLLStorageClass(const GlobalValue &GV) {
546   switch (GV.getDLLStorageClass()) {
547   case GlobalValue::DefaultStorageClass:   return 0;
548   case GlobalValue::DLLImportStorageClass: return 1;
549   case GlobalValue::DLLExportStorageClass: return 2;
550   }
551   llvm_unreachable("Invalid DLL storage class");
552 }
553 
554 static unsigned getEncodedThreadLocalMode(const GlobalValue &GV) {
555   switch (GV.getThreadLocalMode()) {
556     case GlobalVariable::NotThreadLocal:         return 0;
557     case GlobalVariable::GeneralDynamicTLSModel: return 1;
558     case GlobalVariable::LocalDynamicTLSModel:   return 2;
559     case GlobalVariable::InitialExecTLSModel:    return 3;
560     case GlobalVariable::LocalExecTLSModel:      return 4;
561   }
562   llvm_unreachable("Invalid TLS model");
563 }
564 
565 static unsigned getEncodedComdatSelectionKind(const Comdat &C) {
566   switch (C.getSelectionKind()) {
567   case Comdat::Any:
568     return bitc::COMDAT_SELECTION_KIND_ANY;
569   case Comdat::ExactMatch:
570     return bitc::COMDAT_SELECTION_KIND_EXACT_MATCH;
571   case Comdat::Largest:
572     return bitc::COMDAT_SELECTION_KIND_LARGEST;
573   case Comdat::NoDuplicates:
574     return bitc::COMDAT_SELECTION_KIND_NO_DUPLICATES;
575   case Comdat::SameSize:
576     return bitc::COMDAT_SELECTION_KIND_SAME_SIZE;
577   }
578   llvm_unreachable("Invalid selection kind");
579 }
580 
581 static void writeComdats(const ValueEnumerator &VE, BitstreamWriter &Stream) {
582   SmallVector<unsigned, 64> Vals;
583   for (const Comdat *C : VE.getComdats()) {
584     // COMDAT: [selection_kind, name]
585     Vals.push_back(getEncodedComdatSelectionKind(*C));
586     size_t Size = C->getName().size();
587     assert(isUInt<32>(Size));
588     Vals.push_back(Size);
589     for (char Chr : C->getName())
590       Vals.push_back((unsigned char)Chr);
591     Stream.EmitRecord(bitc::MODULE_CODE_COMDAT, Vals, /*AbbrevToUse=*/0);
592     Vals.clear();
593   }
594 }
595 
596 /// Write a record that will eventually hold the word offset of the
597 /// module-level VST. For now the offset is 0, which will be backpatched
598 /// after the real VST is written. Returns the bit offset to backpatch.
599 static uint64_t WriteValueSymbolTableForwardDecl(BitstreamWriter &Stream) {
600   // Write a placeholder value in for the offset of the real VST,
601   // which is written after the function blocks so that it can include
602   // the offset of each function. The placeholder offset will be
603   // updated when the real VST is written.
604   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
605   Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_VSTOFFSET));
606   // Blocks are 32-bit aligned, so we can use a 32-bit word offset to
607   // hold the real VST offset. Must use fixed instead of VBR as we don't
608   // know how many VBR chunks to reserve ahead of time.
609   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
610   unsigned VSTOffsetAbbrev = Stream.EmitAbbrev(Abbv);
611 
612   // Emit the placeholder
613   uint64_t Vals[] = {bitc::MODULE_CODE_VSTOFFSET, 0};
614   Stream.EmitRecordWithAbbrev(VSTOffsetAbbrev, Vals);
615 
616   // Compute and return the bit offset to the placeholder, which will be
617   // patched when the real VST is written. We can simply subtract the 32-bit
618   // fixed size from the current bit number to get the location to backpatch.
619   return Stream.GetCurrentBitNo() - 32;
620 }
621 
622 enum StringEncoding { SE_Char6, SE_Fixed7, SE_Fixed8 };
623 
624 /// Determine the encoding to use for the given string name and length.
625 static StringEncoding getStringEncoding(const char *Str, unsigned StrLen) {
626   bool isChar6 = true;
627   for (const char *C = Str, *E = C + StrLen; C != E; ++C) {
628     if (isChar6)
629       isChar6 = BitCodeAbbrevOp::isChar6(*C);
630     if ((unsigned char)*C & 128)
631       // don't bother scanning the rest.
632       return SE_Fixed8;
633   }
634   if (isChar6)
635     return SE_Char6;
636   else
637     return SE_Fixed7;
638 }
639 
640 /// Emit top-level description of module, including target triple, inline asm,
641 /// descriptors for global variables, and function prototype info.
642 /// Returns the bit offset to backpatch with the location of the real VST.
643 static uint64_t WriteModuleInfo(const Module *M, const ValueEnumerator &VE,
644                                 BitstreamWriter &Stream) {
645   // Emit various pieces of data attached to a module.
646   if (!M->getTargetTriple().empty())
647     WriteStringRecord(bitc::MODULE_CODE_TRIPLE, M->getTargetTriple(),
648                       0/*TODO*/, Stream);
649   const std::string &DL = M->getDataLayoutStr();
650   if (!DL.empty())
651     WriteStringRecord(bitc::MODULE_CODE_DATALAYOUT, DL, 0 /*TODO*/, Stream);
652   if (!M->getModuleInlineAsm().empty())
653     WriteStringRecord(bitc::MODULE_CODE_ASM, M->getModuleInlineAsm(),
654                       0/*TODO*/, Stream);
655 
656   // Emit information about sections and GC, computing how many there are. Also
657   // compute the maximum alignment value.
658   std::map<std::string, unsigned> SectionMap;
659   std::map<std::string, unsigned> GCMap;
660   unsigned MaxAlignment = 0;
661   unsigned MaxGlobalType = 0;
662   for (const GlobalValue &GV : M->globals()) {
663     MaxAlignment = std::max(MaxAlignment, GV.getAlignment());
664     MaxGlobalType = std::max(MaxGlobalType, VE.getTypeID(GV.getValueType()));
665     if (GV.hasSection()) {
666       // Give section names unique ID's.
667       unsigned &Entry = SectionMap[GV.getSection()];
668       if (!Entry) {
669         WriteStringRecord(bitc::MODULE_CODE_SECTIONNAME, GV.getSection(),
670                           0/*TODO*/, Stream);
671         Entry = SectionMap.size();
672       }
673     }
674   }
675   for (const Function &F : *M) {
676     MaxAlignment = std::max(MaxAlignment, F.getAlignment());
677     if (F.hasSection()) {
678       // Give section names unique ID's.
679       unsigned &Entry = SectionMap[F.getSection()];
680       if (!Entry) {
681         WriteStringRecord(bitc::MODULE_CODE_SECTIONNAME, F.getSection(),
682                           0/*TODO*/, Stream);
683         Entry = SectionMap.size();
684       }
685     }
686     if (F.hasGC()) {
687       // Same for GC names.
688       unsigned &Entry = GCMap[F.getGC()];
689       if (!Entry) {
690         WriteStringRecord(bitc::MODULE_CODE_GCNAME, F.getGC(),
691                           0/*TODO*/, Stream);
692         Entry = GCMap.size();
693       }
694     }
695   }
696 
697   // Emit abbrev for globals, now that we know # sections and max alignment.
698   unsigned SimpleGVarAbbrev = 0;
699   if (!M->global_empty()) {
700     // Add an abbrev for common globals with no visibility or thread localness.
701     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
702     Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_GLOBALVAR));
703     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
704                               Log2_32_Ceil(MaxGlobalType+1)));
705     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // AddrSpace << 2
706                                                            //| explicitType << 1
707                                                            //| constant
708     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // Initializer.
709     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 5)); // Linkage.
710     if (MaxAlignment == 0)                                 // Alignment.
711       Abbv->Add(BitCodeAbbrevOp(0));
712     else {
713       unsigned MaxEncAlignment = Log2_32(MaxAlignment)+1;
714       Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
715                                Log2_32_Ceil(MaxEncAlignment+1)));
716     }
717     if (SectionMap.empty())                                    // Section.
718       Abbv->Add(BitCodeAbbrevOp(0));
719     else
720       Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
721                                Log2_32_Ceil(SectionMap.size()+1)));
722     // Don't bother emitting vis + thread local.
723     SimpleGVarAbbrev = Stream.EmitAbbrev(Abbv);
724   }
725 
726   // Emit the global variable information.
727   SmallVector<unsigned, 64> Vals;
728   for (const GlobalVariable &GV : M->globals()) {
729     unsigned AbbrevToUse = 0;
730 
731     // GLOBALVAR: [type, isconst, initid,
732     //             linkage, alignment, section, visibility, threadlocal,
733     //             unnamed_addr, externally_initialized, dllstorageclass,
734     //             comdat]
735     Vals.push_back(VE.getTypeID(GV.getValueType()));
736     Vals.push_back(GV.getType()->getAddressSpace() << 2 | 2 | GV.isConstant());
737     Vals.push_back(GV.isDeclaration() ? 0 :
738                    (VE.getValueID(GV.getInitializer()) + 1));
739     Vals.push_back(getEncodedLinkage(GV));
740     Vals.push_back(Log2_32(GV.getAlignment())+1);
741     Vals.push_back(GV.hasSection() ? SectionMap[GV.getSection()] : 0);
742     if (GV.isThreadLocal() ||
743         GV.getVisibility() != GlobalValue::DefaultVisibility ||
744         GV.hasUnnamedAddr() || GV.isExternallyInitialized() ||
745         GV.getDLLStorageClass() != GlobalValue::DefaultStorageClass ||
746         GV.hasComdat()) {
747       Vals.push_back(getEncodedVisibility(GV));
748       Vals.push_back(getEncodedThreadLocalMode(GV));
749       Vals.push_back(GV.hasUnnamedAddr());
750       Vals.push_back(GV.isExternallyInitialized());
751       Vals.push_back(getEncodedDLLStorageClass(GV));
752       Vals.push_back(GV.hasComdat() ? VE.getComdatID(GV.getComdat()) : 0);
753     } else {
754       AbbrevToUse = SimpleGVarAbbrev;
755     }
756 
757     Stream.EmitRecord(bitc::MODULE_CODE_GLOBALVAR, Vals, AbbrevToUse);
758     Vals.clear();
759   }
760 
761   // Emit the function proto information.
762   for (const Function &F : *M) {
763     // FUNCTION:  [type, callingconv, isproto, linkage, paramattrs, alignment,
764     //             section, visibility, gc, unnamed_addr, prologuedata,
765     //             dllstorageclass, comdat, prefixdata, personalityfn]
766     Vals.push_back(VE.getTypeID(F.getFunctionType()));
767     Vals.push_back(F.getCallingConv());
768     Vals.push_back(F.isDeclaration());
769     Vals.push_back(getEncodedLinkage(F));
770     Vals.push_back(VE.getAttributeID(F.getAttributes()));
771     Vals.push_back(Log2_32(F.getAlignment())+1);
772     Vals.push_back(F.hasSection() ? SectionMap[F.getSection()] : 0);
773     Vals.push_back(getEncodedVisibility(F));
774     Vals.push_back(F.hasGC() ? GCMap[F.getGC()] : 0);
775     Vals.push_back(F.hasUnnamedAddr());
776     Vals.push_back(F.hasPrologueData() ? (VE.getValueID(F.getPrologueData()) + 1)
777                                        : 0);
778     Vals.push_back(getEncodedDLLStorageClass(F));
779     Vals.push_back(F.hasComdat() ? VE.getComdatID(F.getComdat()) : 0);
780     Vals.push_back(F.hasPrefixData() ? (VE.getValueID(F.getPrefixData()) + 1)
781                                      : 0);
782     Vals.push_back(
783         F.hasPersonalityFn() ? (VE.getValueID(F.getPersonalityFn()) + 1) : 0);
784 
785     unsigned AbbrevToUse = 0;
786     Stream.EmitRecord(bitc::MODULE_CODE_FUNCTION, Vals, AbbrevToUse);
787     Vals.clear();
788   }
789 
790   // Emit the alias information.
791   for (const GlobalAlias &A : M->aliases()) {
792     // ALIAS: [alias type, aliasee val#, linkage, visibility]
793     Vals.push_back(VE.getTypeID(A.getValueType()));
794     Vals.push_back(A.getType()->getAddressSpace());
795     Vals.push_back(VE.getValueID(A.getAliasee()));
796     Vals.push_back(getEncodedLinkage(A));
797     Vals.push_back(getEncodedVisibility(A));
798     Vals.push_back(getEncodedDLLStorageClass(A));
799     Vals.push_back(getEncodedThreadLocalMode(A));
800     Vals.push_back(A.hasUnnamedAddr());
801     unsigned AbbrevToUse = 0;
802     Stream.EmitRecord(bitc::MODULE_CODE_ALIAS, Vals, AbbrevToUse);
803     Vals.clear();
804   }
805 
806   // Emit the module's source file name.
807   {
808     StringEncoding Bits = getStringEncoding(M->getSourceFileName().data(),
809                                             M->getSourceFileName().size());
810     BitCodeAbbrevOp AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8);
811     if (Bits == SE_Char6)
812       AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Char6);
813     else if (Bits == SE_Fixed7)
814       AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7);
815 
816     // MODULE_CODE_SOURCE_FILENAME: [namechar x N]
817     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
818     Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_SOURCE_FILENAME));
819     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
820     Abbv->Add(AbbrevOpToUse);
821     unsigned FilenameAbbrev = Stream.EmitAbbrev(Abbv);
822 
823     for (const auto P : M->getSourceFileName())
824       Vals.push_back((unsigned char)P);
825 
826     // Emit the finished record.
827     Stream.EmitRecord(bitc::MODULE_CODE_SOURCE_FILENAME, Vals, FilenameAbbrev);
828     Vals.clear();
829   }
830 
831   // If we have a VST, write the VSTOFFSET record placeholder and return
832   // its offset.
833   if (M->getValueSymbolTable().empty())
834     return 0;
835   return WriteValueSymbolTableForwardDecl(Stream);
836 }
837 
838 static uint64_t GetOptimizationFlags(const Value *V) {
839   uint64_t Flags = 0;
840 
841   if (const auto *OBO = dyn_cast<OverflowingBinaryOperator>(V)) {
842     if (OBO->hasNoSignedWrap())
843       Flags |= 1 << bitc::OBO_NO_SIGNED_WRAP;
844     if (OBO->hasNoUnsignedWrap())
845       Flags |= 1 << bitc::OBO_NO_UNSIGNED_WRAP;
846   } else if (const auto *PEO = dyn_cast<PossiblyExactOperator>(V)) {
847     if (PEO->isExact())
848       Flags |= 1 << bitc::PEO_EXACT;
849   } else if (const auto *FPMO = dyn_cast<FPMathOperator>(V)) {
850     if (FPMO->hasUnsafeAlgebra())
851       Flags |= FastMathFlags::UnsafeAlgebra;
852     if (FPMO->hasNoNaNs())
853       Flags |= FastMathFlags::NoNaNs;
854     if (FPMO->hasNoInfs())
855       Flags |= FastMathFlags::NoInfs;
856     if (FPMO->hasNoSignedZeros())
857       Flags |= FastMathFlags::NoSignedZeros;
858     if (FPMO->hasAllowReciprocal())
859       Flags |= FastMathFlags::AllowReciprocal;
860   }
861 
862   return Flags;
863 }
864 
865 static void writeValueAsMetadata(const ValueAsMetadata *MD,
866                                  const ValueEnumerator &VE,
867                                  BitstreamWriter &Stream,
868                                  SmallVectorImpl<uint64_t> &Record) {
869   // Mimic an MDNode with a value as one operand.
870   Value *V = MD->getValue();
871   Record.push_back(VE.getTypeID(V->getType()));
872   Record.push_back(VE.getValueID(V));
873   Stream.EmitRecord(bitc::METADATA_VALUE, Record, 0);
874   Record.clear();
875 }
876 
877 static void writeMDTuple(const MDTuple *N, const ValueEnumerator &VE,
878                          BitstreamWriter &Stream,
879                          SmallVectorImpl<uint64_t> &Record, unsigned Abbrev) {
880   for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i) {
881     Metadata *MD = N->getOperand(i);
882     assert(!(MD && isa<LocalAsMetadata>(MD)) &&
883            "Unexpected function-local metadata");
884     Record.push_back(VE.getMetadataOrNullID(MD));
885   }
886   Stream.EmitRecord(N->isDistinct() ? bitc::METADATA_DISTINCT_NODE
887                                     : bitc::METADATA_NODE,
888                     Record, Abbrev);
889   Record.clear();
890 }
891 
892 static unsigned createDILocationAbbrev(BitstreamWriter &Stream) {
893   // Assume the column is usually under 128, and always output the inlined-at
894   // location (it's never more expensive than building an array size 1).
895   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
896   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_LOCATION));
897   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
898   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
899   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
900   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
901   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
902   return Stream.EmitAbbrev(Abbv);
903 }
904 
905 static void writeDILocation(const DILocation *N, const ValueEnumerator &VE,
906                             BitstreamWriter &Stream,
907                             SmallVectorImpl<uint64_t> &Record,
908                             unsigned &Abbrev) {
909   if (!Abbrev)
910     Abbrev = createDILocationAbbrev(Stream);
911 
912   Record.push_back(N->isDistinct());
913   Record.push_back(N->getLine());
914   Record.push_back(N->getColumn());
915   Record.push_back(VE.getMetadataID(N->getScope()));
916   Record.push_back(VE.getMetadataOrNullID(N->getInlinedAt()));
917 
918   Stream.EmitRecord(bitc::METADATA_LOCATION, Record, Abbrev);
919   Record.clear();
920 }
921 
922 static unsigned createGenericDINodeAbbrev(BitstreamWriter &Stream) {
923   // Assume the column is usually under 128, and always output the inlined-at
924   // location (it's never more expensive than building an array size 1).
925   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
926   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_GENERIC_DEBUG));
927   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
928   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
929   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
930   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
931   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
932   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
933   return Stream.EmitAbbrev(Abbv);
934 }
935 
936 static void writeGenericDINode(const GenericDINode *N,
937                                const ValueEnumerator &VE,
938                                BitstreamWriter &Stream,
939                                SmallVectorImpl<uint64_t> &Record,
940                                unsigned &Abbrev) {
941   if (!Abbrev)
942     Abbrev = createGenericDINodeAbbrev(Stream);
943 
944   Record.push_back(N->isDistinct());
945   Record.push_back(N->getTag());
946   Record.push_back(0); // Per-tag version field; unused for now.
947 
948   for (auto &I : N->operands())
949     Record.push_back(VE.getMetadataOrNullID(I));
950 
951   Stream.EmitRecord(bitc::METADATA_GENERIC_DEBUG, Record, Abbrev);
952   Record.clear();
953 }
954 
955 static uint64_t rotateSign(int64_t I) {
956   uint64_t U = I;
957   return I < 0 ? ~(U << 1) : U << 1;
958 }
959 
960 static void writeDISubrange(const DISubrange *N, const ValueEnumerator &,
961                             BitstreamWriter &Stream,
962                             SmallVectorImpl<uint64_t> &Record,
963                             unsigned Abbrev) {
964   Record.push_back(N->isDistinct());
965   Record.push_back(N->getCount());
966   Record.push_back(rotateSign(N->getLowerBound()));
967 
968   Stream.EmitRecord(bitc::METADATA_SUBRANGE, Record, Abbrev);
969   Record.clear();
970 }
971 
972 static void writeDIEnumerator(const DIEnumerator *N, const ValueEnumerator &VE,
973                               BitstreamWriter &Stream,
974                               SmallVectorImpl<uint64_t> &Record,
975                               unsigned Abbrev) {
976   Record.push_back(N->isDistinct());
977   Record.push_back(rotateSign(N->getValue()));
978   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
979 
980   Stream.EmitRecord(bitc::METADATA_ENUMERATOR, Record, Abbrev);
981   Record.clear();
982 }
983 
984 static void writeDIBasicType(const DIBasicType *N, const ValueEnumerator &VE,
985                              BitstreamWriter &Stream,
986                              SmallVectorImpl<uint64_t> &Record,
987                              unsigned Abbrev) {
988   Record.push_back(N->isDistinct());
989   Record.push_back(N->getTag());
990   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
991   Record.push_back(N->getSizeInBits());
992   Record.push_back(N->getAlignInBits());
993   Record.push_back(N->getEncoding());
994 
995   Stream.EmitRecord(bitc::METADATA_BASIC_TYPE, Record, Abbrev);
996   Record.clear();
997 }
998 
999 static void writeDIDerivedType(const DIDerivedType *N,
1000                                const ValueEnumerator &VE,
1001                                BitstreamWriter &Stream,
1002                                SmallVectorImpl<uint64_t> &Record,
1003                                unsigned Abbrev) {
1004   Record.push_back(N->isDistinct());
1005   Record.push_back(N->getTag());
1006   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1007   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1008   Record.push_back(N->getLine());
1009   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1010   Record.push_back(VE.getMetadataOrNullID(N->getBaseType()));
1011   Record.push_back(N->getSizeInBits());
1012   Record.push_back(N->getAlignInBits());
1013   Record.push_back(N->getOffsetInBits());
1014   Record.push_back(N->getFlags());
1015   Record.push_back(VE.getMetadataOrNullID(N->getExtraData()));
1016 
1017   Stream.EmitRecord(bitc::METADATA_DERIVED_TYPE, Record, Abbrev);
1018   Record.clear();
1019 }
1020 
1021 static void writeDICompositeType(const DICompositeType *N,
1022                                  const ValueEnumerator &VE,
1023                                  BitstreamWriter &Stream,
1024                                  SmallVectorImpl<uint64_t> &Record,
1025                                  unsigned Abbrev) {
1026   Record.push_back(N->isDistinct());
1027   Record.push_back(N->getTag());
1028   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1029   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1030   Record.push_back(N->getLine());
1031   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1032   Record.push_back(VE.getMetadataOrNullID(N->getBaseType()));
1033   Record.push_back(N->getSizeInBits());
1034   Record.push_back(N->getAlignInBits());
1035   Record.push_back(N->getOffsetInBits());
1036   Record.push_back(N->getFlags());
1037   Record.push_back(VE.getMetadataOrNullID(N->getElements().get()));
1038   Record.push_back(N->getRuntimeLang());
1039   Record.push_back(VE.getMetadataOrNullID(N->getVTableHolder()));
1040   Record.push_back(VE.getMetadataOrNullID(N->getTemplateParams().get()));
1041   Record.push_back(VE.getMetadataOrNullID(N->getRawIdentifier()));
1042 
1043   Stream.EmitRecord(bitc::METADATA_COMPOSITE_TYPE, Record, Abbrev);
1044   Record.clear();
1045 }
1046 
1047 static void writeDISubroutineType(const DISubroutineType *N,
1048                                   const ValueEnumerator &VE,
1049                                   BitstreamWriter &Stream,
1050                                   SmallVectorImpl<uint64_t> &Record,
1051                                   unsigned Abbrev) {
1052   Record.push_back(N->isDistinct());
1053   Record.push_back(N->getFlags());
1054   Record.push_back(VE.getMetadataOrNullID(N->getTypeArray().get()));
1055 
1056   Stream.EmitRecord(bitc::METADATA_SUBROUTINE_TYPE, Record, Abbrev);
1057   Record.clear();
1058 }
1059 
1060 static void writeDIFile(const DIFile *N, const ValueEnumerator &VE,
1061                         BitstreamWriter &Stream,
1062                         SmallVectorImpl<uint64_t> &Record, unsigned Abbrev) {
1063   Record.push_back(N->isDistinct());
1064   Record.push_back(VE.getMetadataOrNullID(N->getRawFilename()));
1065   Record.push_back(VE.getMetadataOrNullID(N->getRawDirectory()));
1066 
1067   Stream.EmitRecord(bitc::METADATA_FILE, Record, Abbrev);
1068   Record.clear();
1069 }
1070 
1071 static void writeDICompileUnit(const DICompileUnit *N,
1072                                const ValueEnumerator &VE,
1073                                BitstreamWriter &Stream,
1074                                SmallVectorImpl<uint64_t> &Record,
1075                                unsigned Abbrev) {
1076   assert(N->isDistinct() && "Expected distinct compile units");
1077   Record.push_back(/* IsDistinct */ true);
1078   Record.push_back(N->getSourceLanguage());
1079   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1080   Record.push_back(VE.getMetadataOrNullID(N->getRawProducer()));
1081   Record.push_back(N->isOptimized());
1082   Record.push_back(VE.getMetadataOrNullID(N->getRawFlags()));
1083   Record.push_back(N->getRuntimeVersion());
1084   Record.push_back(VE.getMetadataOrNullID(N->getRawSplitDebugFilename()));
1085   Record.push_back(N->getEmissionKind());
1086   Record.push_back(VE.getMetadataOrNullID(N->getEnumTypes().get()));
1087   Record.push_back(VE.getMetadataOrNullID(N->getRetainedTypes().get()));
1088   Record.push_back(VE.getMetadataOrNullID(N->getSubprograms().get()));
1089   Record.push_back(VE.getMetadataOrNullID(N->getGlobalVariables().get()));
1090   Record.push_back(VE.getMetadataOrNullID(N->getImportedEntities().get()));
1091   Record.push_back(N->getDWOId());
1092   Record.push_back(VE.getMetadataOrNullID(N->getMacros().get()));
1093 
1094   Stream.EmitRecord(bitc::METADATA_COMPILE_UNIT, Record, Abbrev);
1095   Record.clear();
1096 }
1097 
1098 static void writeDISubprogram(const DISubprogram *N, const ValueEnumerator &VE,
1099                               BitstreamWriter &Stream,
1100                               SmallVectorImpl<uint64_t> &Record,
1101                               unsigned Abbrev) {
1102   Record.push_back(N->isDistinct());
1103   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1104   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1105   Record.push_back(VE.getMetadataOrNullID(N->getRawLinkageName()));
1106   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1107   Record.push_back(N->getLine());
1108   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1109   Record.push_back(N->isLocalToUnit());
1110   Record.push_back(N->isDefinition());
1111   Record.push_back(N->getScopeLine());
1112   Record.push_back(VE.getMetadataOrNullID(N->getContainingType()));
1113   Record.push_back(N->getVirtuality());
1114   Record.push_back(N->getVirtualIndex());
1115   Record.push_back(N->getFlags());
1116   Record.push_back(N->isOptimized());
1117   Record.push_back(VE.getMetadataOrNullID(N->getTemplateParams().get()));
1118   Record.push_back(VE.getMetadataOrNullID(N->getDeclaration()));
1119   Record.push_back(VE.getMetadataOrNullID(N->getVariables().get()));
1120 
1121   Stream.EmitRecord(bitc::METADATA_SUBPROGRAM, Record, Abbrev);
1122   Record.clear();
1123 }
1124 
1125 static void writeDILexicalBlock(const DILexicalBlock *N,
1126                                 const ValueEnumerator &VE,
1127                                 BitstreamWriter &Stream,
1128                                 SmallVectorImpl<uint64_t> &Record,
1129                                 unsigned Abbrev) {
1130   Record.push_back(N->isDistinct());
1131   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1132   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1133   Record.push_back(N->getLine());
1134   Record.push_back(N->getColumn());
1135 
1136   Stream.EmitRecord(bitc::METADATA_LEXICAL_BLOCK, Record, Abbrev);
1137   Record.clear();
1138 }
1139 
1140 static void writeDILexicalBlockFile(const DILexicalBlockFile *N,
1141                                     const ValueEnumerator &VE,
1142                                     BitstreamWriter &Stream,
1143                                     SmallVectorImpl<uint64_t> &Record,
1144                                     unsigned Abbrev) {
1145   Record.push_back(N->isDistinct());
1146   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1147   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1148   Record.push_back(N->getDiscriminator());
1149 
1150   Stream.EmitRecord(bitc::METADATA_LEXICAL_BLOCK_FILE, Record, Abbrev);
1151   Record.clear();
1152 }
1153 
1154 static void writeDINamespace(const DINamespace *N, const ValueEnumerator &VE,
1155                              BitstreamWriter &Stream,
1156                              SmallVectorImpl<uint64_t> &Record,
1157                              unsigned Abbrev) {
1158   Record.push_back(N->isDistinct());
1159   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1160   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1161   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1162   Record.push_back(N->getLine());
1163 
1164   Stream.EmitRecord(bitc::METADATA_NAMESPACE, Record, Abbrev);
1165   Record.clear();
1166 }
1167 
1168 static void writeDIMacro(const DIMacro *N, const ValueEnumerator &VE,
1169                          BitstreamWriter &Stream,
1170                          SmallVectorImpl<uint64_t> &Record, unsigned Abbrev) {
1171   Record.push_back(N->isDistinct());
1172   Record.push_back(N->getMacinfoType());
1173   Record.push_back(N->getLine());
1174   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1175   Record.push_back(VE.getMetadataOrNullID(N->getRawValue()));
1176 
1177   Stream.EmitRecord(bitc::METADATA_MACRO, Record, Abbrev);
1178   Record.clear();
1179 }
1180 
1181 static void writeDIMacroFile(const DIMacroFile *N, const ValueEnumerator &VE,
1182                              BitstreamWriter &Stream,
1183                              SmallVectorImpl<uint64_t> &Record,
1184                              unsigned Abbrev) {
1185   Record.push_back(N->isDistinct());
1186   Record.push_back(N->getMacinfoType());
1187   Record.push_back(N->getLine());
1188   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1189   Record.push_back(VE.getMetadataOrNullID(N->getElements().get()));
1190 
1191   Stream.EmitRecord(bitc::METADATA_MACRO_FILE, Record, Abbrev);
1192   Record.clear();
1193 }
1194 
1195 static void writeDIModule(const DIModule *N, const ValueEnumerator &VE,
1196                           BitstreamWriter &Stream,
1197                           SmallVectorImpl<uint64_t> &Record, unsigned Abbrev) {
1198   Record.push_back(N->isDistinct());
1199   for (auto &I : N->operands())
1200     Record.push_back(VE.getMetadataOrNullID(I));
1201 
1202   Stream.EmitRecord(bitc::METADATA_MODULE, Record, Abbrev);
1203   Record.clear();
1204 }
1205 
1206 static void writeDITemplateTypeParameter(const DITemplateTypeParameter *N,
1207                                          const ValueEnumerator &VE,
1208                                          BitstreamWriter &Stream,
1209                                          SmallVectorImpl<uint64_t> &Record,
1210                                          unsigned Abbrev) {
1211   Record.push_back(N->isDistinct());
1212   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1213   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1214 
1215   Stream.EmitRecord(bitc::METADATA_TEMPLATE_TYPE, Record, Abbrev);
1216   Record.clear();
1217 }
1218 
1219 static void writeDITemplateValueParameter(const DITemplateValueParameter *N,
1220                                           const ValueEnumerator &VE,
1221                                           BitstreamWriter &Stream,
1222                                           SmallVectorImpl<uint64_t> &Record,
1223                                           unsigned Abbrev) {
1224   Record.push_back(N->isDistinct());
1225   Record.push_back(N->getTag());
1226   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1227   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1228   Record.push_back(VE.getMetadataOrNullID(N->getValue()));
1229 
1230   Stream.EmitRecord(bitc::METADATA_TEMPLATE_VALUE, Record, Abbrev);
1231   Record.clear();
1232 }
1233 
1234 static void writeDIGlobalVariable(const DIGlobalVariable *N,
1235                                   const ValueEnumerator &VE,
1236                                   BitstreamWriter &Stream,
1237                                   SmallVectorImpl<uint64_t> &Record,
1238                                   unsigned Abbrev) {
1239   Record.push_back(N->isDistinct());
1240   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1241   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1242   Record.push_back(VE.getMetadataOrNullID(N->getRawLinkageName()));
1243   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1244   Record.push_back(N->getLine());
1245   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1246   Record.push_back(N->isLocalToUnit());
1247   Record.push_back(N->isDefinition());
1248   Record.push_back(VE.getMetadataOrNullID(N->getRawVariable()));
1249   Record.push_back(VE.getMetadataOrNullID(N->getStaticDataMemberDeclaration()));
1250 
1251   Stream.EmitRecord(bitc::METADATA_GLOBAL_VAR, Record, Abbrev);
1252   Record.clear();
1253 }
1254 
1255 static void writeDILocalVariable(const DILocalVariable *N,
1256                                  const ValueEnumerator &VE,
1257                                  BitstreamWriter &Stream,
1258                                  SmallVectorImpl<uint64_t> &Record,
1259                                  unsigned Abbrev) {
1260   Record.push_back(N->isDistinct());
1261   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1262   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1263   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1264   Record.push_back(N->getLine());
1265   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1266   Record.push_back(N->getArg());
1267   Record.push_back(N->getFlags());
1268 
1269   Stream.EmitRecord(bitc::METADATA_LOCAL_VAR, Record, Abbrev);
1270   Record.clear();
1271 }
1272 
1273 static void writeDIExpression(const DIExpression *N, const ValueEnumerator &,
1274                               BitstreamWriter &Stream,
1275                               SmallVectorImpl<uint64_t> &Record,
1276                               unsigned Abbrev) {
1277   Record.reserve(N->getElements().size() + 1);
1278 
1279   Record.push_back(N->isDistinct());
1280   Record.append(N->elements_begin(), N->elements_end());
1281 
1282   Stream.EmitRecord(bitc::METADATA_EXPRESSION, Record, Abbrev);
1283   Record.clear();
1284 }
1285 
1286 static void writeDIObjCProperty(const DIObjCProperty *N,
1287                                 const ValueEnumerator &VE,
1288                                 BitstreamWriter &Stream,
1289                                 SmallVectorImpl<uint64_t> &Record,
1290                                 unsigned Abbrev) {
1291   Record.push_back(N->isDistinct());
1292   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1293   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1294   Record.push_back(N->getLine());
1295   Record.push_back(VE.getMetadataOrNullID(N->getRawSetterName()));
1296   Record.push_back(VE.getMetadataOrNullID(N->getRawGetterName()));
1297   Record.push_back(N->getAttributes());
1298   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1299 
1300   Stream.EmitRecord(bitc::METADATA_OBJC_PROPERTY, Record, Abbrev);
1301   Record.clear();
1302 }
1303 
1304 static void writeDIImportedEntity(const DIImportedEntity *N,
1305                                   const ValueEnumerator &VE,
1306                                   BitstreamWriter &Stream,
1307                                   SmallVectorImpl<uint64_t> &Record,
1308                                   unsigned Abbrev) {
1309   Record.push_back(N->isDistinct());
1310   Record.push_back(N->getTag());
1311   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1312   Record.push_back(VE.getMetadataOrNullID(N->getEntity()));
1313   Record.push_back(N->getLine());
1314   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1315 
1316   Stream.EmitRecord(bitc::METADATA_IMPORTED_ENTITY, Record, Abbrev);
1317   Record.clear();
1318 }
1319 
1320 static unsigned createNamedMetadataAbbrev(BitstreamWriter &Stream) {
1321   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1322   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_NAME));
1323   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1324   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
1325   return Stream.EmitAbbrev(Abbv);
1326 }
1327 
1328 static void writeNamedMetadata(const Module &M, const ValueEnumerator &VE,
1329                                BitstreamWriter &Stream,
1330                                SmallVectorImpl<uint64_t> &Record) {
1331   if (M.named_metadata_empty())
1332     return;
1333 
1334   unsigned Abbrev = createNamedMetadataAbbrev(Stream);
1335   for (const NamedMDNode &NMD : M.named_metadata()) {
1336     // Write name.
1337     StringRef Str = NMD.getName();
1338     Record.append(Str.bytes_begin(), Str.bytes_end());
1339     Stream.EmitRecord(bitc::METADATA_NAME, Record, Abbrev);
1340     Record.clear();
1341 
1342     // Write named metadata operands.
1343     for (const MDNode *N : NMD.operands())
1344       Record.push_back(VE.getMetadataID(N));
1345     Stream.EmitRecord(bitc::METADATA_NAMED_NODE, Record, 0);
1346     Record.clear();
1347   }
1348 }
1349 
1350 static unsigned createMetadataStringsAbbrev(BitstreamWriter &Stream) {
1351   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1352   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_STRINGS));
1353   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // # of strings
1354   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // offset to chars
1355   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob));
1356   return Stream.EmitAbbrev(Abbv);
1357 }
1358 
1359 /// Write out a record for MDString.
1360 ///
1361 /// All the metadata strings in a metadata block are emitted in a single
1362 /// record.  The sizes and strings themselves are shoved into a blob.
1363 static void writeMetadataStrings(ArrayRef<const Metadata *> Strings,
1364                                  BitstreamWriter &Stream,
1365                                  SmallVectorImpl<uint64_t> &Record) {
1366   if (Strings.empty())
1367     return;
1368 
1369   // Start the record with the number of strings.
1370   Record.push_back(bitc::METADATA_STRINGS);
1371   Record.push_back(Strings.size());
1372 
1373   // Emit the sizes of the strings in the blob.
1374   SmallString<256> Blob;
1375   {
1376     BitstreamWriter W(Blob);
1377     for (const Metadata *MD : Strings)
1378       W.EmitVBR(cast<MDString>(MD)->getLength(), 6);
1379     W.FlushToWord();
1380   }
1381 
1382   // Add the offset to the strings to the record.
1383   Record.push_back(Blob.size());
1384 
1385   // Add the strings to the blob.
1386   for (const Metadata *MD : Strings)
1387     Blob.append(cast<MDString>(MD)->getString());
1388 
1389   // Emit the final record.
1390   Stream.EmitRecordWithBlob(createMetadataStringsAbbrev(Stream), Record, Blob);
1391   Record.clear();
1392 }
1393 
1394 static void writeMetadataRecords(ArrayRef<const Metadata *> MDs,
1395                                  const ValueEnumerator &VE,
1396                                  BitstreamWriter &Stream,
1397                                  SmallVectorImpl<uint64_t> &Record) {
1398   if (MDs.empty())
1399     return;
1400 
1401   // Initialize MDNode abbreviations.
1402 #define HANDLE_MDNODE_LEAF(CLASS) unsigned CLASS##Abbrev = 0;
1403 #include "llvm/IR/Metadata.def"
1404 
1405   for (const Metadata *MD : MDs) {
1406     if (const MDNode *N = dyn_cast<MDNode>(MD)) {
1407       assert(N->isResolved() && "Expected forward references to be resolved");
1408 
1409       switch (N->getMetadataID()) {
1410       default:
1411         llvm_unreachable("Invalid MDNode subclass");
1412 #define HANDLE_MDNODE_LEAF(CLASS)                                              \
1413   case Metadata::CLASS##Kind:                                                  \
1414     write##CLASS(cast<CLASS>(N), VE, Stream, Record, CLASS##Abbrev);           \
1415     continue;
1416 #include "llvm/IR/Metadata.def"
1417       }
1418     }
1419     writeValueAsMetadata(cast<ValueAsMetadata>(MD), VE, Stream, Record);
1420   }
1421 }
1422 
1423 static void writeModuleMetadata(const Module &M,
1424                                 const ValueEnumerator &VE,
1425                                 BitstreamWriter &Stream) {
1426   if (VE.getMDs().empty() && M.named_metadata_empty())
1427     return;
1428 
1429   Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
1430   SmallVector<uint64_t, 64> Record;
1431   writeMetadataStrings(VE.getMDStrings(), Stream, Record);
1432   writeMetadataRecords(VE.getNonMDStrings(), VE, Stream, Record);
1433   writeNamedMetadata(M, VE, Stream, Record);
1434   Stream.ExitBlock();
1435 }
1436 
1437 static void writeFunctionMetadata(const Function &F, const ValueEnumerator &VE,
1438                                   BitstreamWriter &Stream) {
1439   ArrayRef<const Metadata *> MDs = VE.getFunctionMDs();
1440   if (MDs.empty())
1441     return;
1442 
1443   Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
1444   SmallVector<uint64_t, 64> Record;
1445   writeMetadataRecords(MDs, VE, Stream, Record);
1446   Stream.ExitBlock();
1447 }
1448 
1449 static void WriteMetadataAttachment(const Function &F,
1450                                     const ValueEnumerator &VE,
1451                                     BitstreamWriter &Stream) {
1452   Stream.EnterSubblock(bitc::METADATA_ATTACHMENT_ID, 3);
1453 
1454   SmallVector<uint64_t, 64> Record;
1455 
1456   // Write metadata attachments
1457   // METADATA_ATTACHMENT - [m x [value, [n x [id, mdnode]]]
1458   SmallVector<std::pair<unsigned, MDNode *>, 4> MDs;
1459   F.getAllMetadata(MDs);
1460   if (!MDs.empty()) {
1461     for (const auto &I : MDs) {
1462       Record.push_back(I.first);
1463       Record.push_back(VE.getMetadataID(I.second));
1464     }
1465     Stream.EmitRecord(bitc::METADATA_ATTACHMENT, Record, 0);
1466     Record.clear();
1467   }
1468 
1469   for (const BasicBlock &BB : F)
1470     for (const Instruction &I : BB) {
1471       MDs.clear();
1472       I.getAllMetadataOtherThanDebugLoc(MDs);
1473 
1474       // If no metadata, ignore instruction.
1475       if (MDs.empty()) continue;
1476 
1477       Record.push_back(VE.getInstructionID(&I));
1478 
1479       for (unsigned i = 0, e = MDs.size(); i != e; ++i) {
1480         Record.push_back(MDs[i].first);
1481         Record.push_back(VE.getMetadataID(MDs[i].second));
1482       }
1483       Stream.EmitRecord(bitc::METADATA_ATTACHMENT, Record, 0);
1484       Record.clear();
1485     }
1486 
1487   Stream.ExitBlock();
1488 }
1489 
1490 static void WriteModuleMetadataStore(const Module *M, BitstreamWriter &Stream) {
1491   SmallVector<uint64_t, 64> Record;
1492 
1493   // Write metadata kinds
1494   // METADATA_KIND - [n x [id, name]]
1495   SmallVector<StringRef, 8> Names;
1496   M->getMDKindNames(Names);
1497 
1498   if (Names.empty()) return;
1499 
1500   Stream.EnterSubblock(bitc::METADATA_KIND_BLOCK_ID, 3);
1501 
1502   for (unsigned MDKindID = 0, e = Names.size(); MDKindID != e; ++MDKindID) {
1503     Record.push_back(MDKindID);
1504     StringRef KName = Names[MDKindID];
1505     Record.append(KName.begin(), KName.end());
1506 
1507     Stream.EmitRecord(bitc::METADATA_KIND, Record, 0);
1508     Record.clear();
1509   }
1510 
1511   Stream.ExitBlock();
1512 }
1513 
1514 static void WriteOperandBundleTags(const Module *M, BitstreamWriter &Stream) {
1515   // Write metadata kinds
1516   //
1517   // OPERAND_BUNDLE_TAGS_BLOCK_ID : N x OPERAND_BUNDLE_TAG
1518   //
1519   // OPERAND_BUNDLE_TAG - [strchr x N]
1520 
1521   SmallVector<StringRef, 8> Tags;
1522   M->getOperandBundleTags(Tags);
1523 
1524   if (Tags.empty())
1525     return;
1526 
1527   Stream.EnterSubblock(bitc::OPERAND_BUNDLE_TAGS_BLOCK_ID, 3);
1528 
1529   SmallVector<uint64_t, 64> Record;
1530 
1531   for (auto Tag : Tags) {
1532     Record.append(Tag.begin(), Tag.end());
1533 
1534     Stream.EmitRecord(bitc::OPERAND_BUNDLE_TAG, Record, 0);
1535     Record.clear();
1536   }
1537 
1538   Stream.ExitBlock();
1539 }
1540 
1541 static void emitSignedInt64(SmallVectorImpl<uint64_t> &Vals, uint64_t V) {
1542   if ((int64_t)V >= 0)
1543     Vals.push_back(V << 1);
1544   else
1545     Vals.push_back((-V << 1) | 1);
1546 }
1547 
1548 static void WriteConstants(unsigned FirstVal, unsigned LastVal,
1549                            const ValueEnumerator &VE,
1550                            BitstreamWriter &Stream, bool isGlobal) {
1551   if (FirstVal == LastVal) return;
1552 
1553   Stream.EnterSubblock(bitc::CONSTANTS_BLOCK_ID, 4);
1554 
1555   unsigned AggregateAbbrev = 0;
1556   unsigned String8Abbrev = 0;
1557   unsigned CString7Abbrev = 0;
1558   unsigned CString6Abbrev = 0;
1559   // If this is a constant pool for the module, emit module-specific abbrevs.
1560   if (isGlobal) {
1561     // Abbrev for CST_CODE_AGGREGATE.
1562     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1563     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_AGGREGATE));
1564     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1565     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, Log2_32_Ceil(LastVal+1)));
1566     AggregateAbbrev = Stream.EmitAbbrev(Abbv);
1567 
1568     // Abbrev for CST_CODE_STRING.
1569     Abbv = new BitCodeAbbrev();
1570     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_STRING));
1571     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1572     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
1573     String8Abbrev = Stream.EmitAbbrev(Abbv);
1574     // Abbrev for CST_CODE_CSTRING.
1575     Abbv = new BitCodeAbbrev();
1576     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
1577     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1578     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
1579     CString7Abbrev = Stream.EmitAbbrev(Abbv);
1580     // Abbrev for CST_CODE_CSTRING.
1581     Abbv = new BitCodeAbbrev();
1582     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
1583     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1584     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
1585     CString6Abbrev = Stream.EmitAbbrev(Abbv);
1586   }
1587 
1588   SmallVector<uint64_t, 64> Record;
1589 
1590   const ValueEnumerator::ValueList &Vals = VE.getValues();
1591   Type *LastTy = nullptr;
1592   for (unsigned i = FirstVal; i != LastVal; ++i) {
1593     const Value *V = Vals[i].first;
1594     // If we need to switch types, do so now.
1595     if (V->getType() != LastTy) {
1596       LastTy = V->getType();
1597       Record.push_back(VE.getTypeID(LastTy));
1598       Stream.EmitRecord(bitc::CST_CODE_SETTYPE, Record,
1599                         CONSTANTS_SETTYPE_ABBREV);
1600       Record.clear();
1601     }
1602 
1603     if (const InlineAsm *IA = dyn_cast<InlineAsm>(V)) {
1604       Record.push_back(unsigned(IA->hasSideEffects()) |
1605                        unsigned(IA->isAlignStack()) << 1 |
1606                        unsigned(IA->getDialect()&1) << 2);
1607 
1608       // Add the asm string.
1609       const std::string &AsmStr = IA->getAsmString();
1610       Record.push_back(AsmStr.size());
1611       Record.append(AsmStr.begin(), AsmStr.end());
1612 
1613       // Add the constraint string.
1614       const std::string &ConstraintStr = IA->getConstraintString();
1615       Record.push_back(ConstraintStr.size());
1616       Record.append(ConstraintStr.begin(), ConstraintStr.end());
1617       Stream.EmitRecord(bitc::CST_CODE_INLINEASM, Record);
1618       Record.clear();
1619       continue;
1620     }
1621     const Constant *C = cast<Constant>(V);
1622     unsigned Code = -1U;
1623     unsigned AbbrevToUse = 0;
1624     if (C->isNullValue()) {
1625       Code = bitc::CST_CODE_NULL;
1626     } else if (isa<UndefValue>(C)) {
1627       Code = bitc::CST_CODE_UNDEF;
1628     } else if (const ConstantInt *IV = dyn_cast<ConstantInt>(C)) {
1629       if (IV->getBitWidth() <= 64) {
1630         uint64_t V = IV->getSExtValue();
1631         emitSignedInt64(Record, V);
1632         Code = bitc::CST_CODE_INTEGER;
1633         AbbrevToUse = CONSTANTS_INTEGER_ABBREV;
1634       } else {                             // Wide integers, > 64 bits in size.
1635         // We have an arbitrary precision integer value to write whose
1636         // bit width is > 64. However, in canonical unsigned integer
1637         // format it is likely that the high bits are going to be zero.
1638         // So, we only write the number of active words.
1639         unsigned NWords = IV->getValue().getActiveWords();
1640         const uint64_t *RawWords = IV->getValue().getRawData();
1641         for (unsigned i = 0; i != NWords; ++i) {
1642           emitSignedInt64(Record, RawWords[i]);
1643         }
1644         Code = bitc::CST_CODE_WIDE_INTEGER;
1645       }
1646     } else if (const ConstantFP *CFP = dyn_cast<ConstantFP>(C)) {
1647       Code = bitc::CST_CODE_FLOAT;
1648       Type *Ty = CFP->getType();
1649       if (Ty->isHalfTy() || Ty->isFloatTy() || Ty->isDoubleTy()) {
1650         Record.push_back(CFP->getValueAPF().bitcastToAPInt().getZExtValue());
1651       } else if (Ty->isX86_FP80Ty()) {
1652         // api needed to prevent premature destruction
1653         // bits are not in the same order as a normal i80 APInt, compensate.
1654         APInt api = CFP->getValueAPF().bitcastToAPInt();
1655         const uint64_t *p = api.getRawData();
1656         Record.push_back((p[1] << 48) | (p[0] >> 16));
1657         Record.push_back(p[0] & 0xffffLL);
1658       } else if (Ty->isFP128Ty() || Ty->isPPC_FP128Ty()) {
1659         APInt api = CFP->getValueAPF().bitcastToAPInt();
1660         const uint64_t *p = api.getRawData();
1661         Record.push_back(p[0]);
1662         Record.push_back(p[1]);
1663       } else {
1664         assert (0 && "Unknown FP type!");
1665       }
1666     } else if (isa<ConstantDataSequential>(C) &&
1667                cast<ConstantDataSequential>(C)->isString()) {
1668       const ConstantDataSequential *Str = cast<ConstantDataSequential>(C);
1669       // Emit constant strings specially.
1670       unsigned NumElts = Str->getNumElements();
1671       // If this is a null-terminated string, use the denser CSTRING encoding.
1672       if (Str->isCString()) {
1673         Code = bitc::CST_CODE_CSTRING;
1674         --NumElts;  // Don't encode the null, which isn't allowed by char6.
1675       } else {
1676         Code = bitc::CST_CODE_STRING;
1677         AbbrevToUse = String8Abbrev;
1678       }
1679       bool isCStr7 = Code == bitc::CST_CODE_CSTRING;
1680       bool isCStrChar6 = Code == bitc::CST_CODE_CSTRING;
1681       for (unsigned i = 0; i != NumElts; ++i) {
1682         unsigned char V = Str->getElementAsInteger(i);
1683         Record.push_back(V);
1684         isCStr7 &= (V & 128) == 0;
1685         if (isCStrChar6)
1686           isCStrChar6 = BitCodeAbbrevOp::isChar6(V);
1687       }
1688 
1689       if (isCStrChar6)
1690         AbbrevToUse = CString6Abbrev;
1691       else if (isCStr7)
1692         AbbrevToUse = CString7Abbrev;
1693     } else if (const ConstantDataSequential *CDS =
1694                   dyn_cast<ConstantDataSequential>(C)) {
1695       Code = bitc::CST_CODE_DATA;
1696       Type *EltTy = CDS->getType()->getElementType();
1697       if (isa<IntegerType>(EltTy)) {
1698         for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i)
1699           Record.push_back(CDS->getElementAsInteger(i));
1700       } else {
1701         for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i)
1702           Record.push_back(
1703               CDS->getElementAsAPFloat(i).bitcastToAPInt().getLimitedValue());
1704       }
1705     } else if (isa<ConstantArray>(C) || isa<ConstantStruct>(C) ||
1706                isa<ConstantVector>(C)) {
1707       Code = bitc::CST_CODE_AGGREGATE;
1708       for (const Value *Op : C->operands())
1709         Record.push_back(VE.getValueID(Op));
1710       AbbrevToUse = AggregateAbbrev;
1711     } else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
1712       switch (CE->getOpcode()) {
1713       default:
1714         if (Instruction::isCast(CE->getOpcode())) {
1715           Code = bitc::CST_CODE_CE_CAST;
1716           Record.push_back(GetEncodedCastOpcode(CE->getOpcode()));
1717           Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
1718           Record.push_back(VE.getValueID(C->getOperand(0)));
1719           AbbrevToUse = CONSTANTS_CE_CAST_Abbrev;
1720         } else {
1721           assert(CE->getNumOperands() == 2 && "Unknown constant expr!");
1722           Code = bitc::CST_CODE_CE_BINOP;
1723           Record.push_back(GetEncodedBinaryOpcode(CE->getOpcode()));
1724           Record.push_back(VE.getValueID(C->getOperand(0)));
1725           Record.push_back(VE.getValueID(C->getOperand(1)));
1726           uint64_t Flags = GetOptimizationFlags(CE);
1727           if (Flags != 0)
1728             Record.push_back(Flags);
1729         }
1730         break;
1731       case Instruction::GetElementPtr: {
1732         Code = bitc::CST_CODE_CE_GEP;
1733         const auto *GO = cast<GEPOperator>(C);
1734         if (GO->isInBounds())
1735           Code = bitc::CST_CODE_CE_INBOUNDS_GEP;
1736         Record.push_back(VE.getTypeID(GO->getSourceElementType()));
1737         for (unsigned i = 0, e = CE->getNumOperands(); i != e; ++i) {
1738           Record.push_back(VE.getTypeID(C->getOperand(i)->getType()));
1739           Record.push_back(VE.getValueID(C->getOperand(i)));
1740         }
1741         break;
1742       }
1743       case Instruction::Select:
1744         Code = bitc::CST_CODE_CE_SELECT;
1745         Record.push_back(VE.getValueID(C->getOperand(0)));
1746         Record.push_back(VE.getValueID(C->getOperand(1)));
1747         Record.push_back(VE.getValueID(C->getOperand(2)));
1748         break;
1749       case Instruction::ExtractElement:
1750         Code = bitc::CST_CODE_CE_EXTRACTELT;
1751         Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
1752         Record.push_back(VE.getValueID(C->getOperand(0)));
1753         Record.push_back(VE.getTypeID(C->getOperand(1)->getType()));
1754         Record.push_back(VE.getValueID(C->getOperand(1)));
1755         break;
1756       case Instruction::InsertElement:
1757         Code = bitc::CST_CODE_CE_INSERTELT;
1758         Record.push_back(VE.getValueID(C->getOperand(0)));
1759         Record.push_back(VE.getValueID(C->getOperand(1)));
1760         Record.push_back(VE.getTypeID(C->getOperand(2)->getType()));
1761         Record.push_back(VE.getValueID(C->getOperand(2)));
1762         break;
1763       case Instruction::ShuffleVector:
1764         // If the return type and argument types are the same, this is a
1765         // standard shufflevector instruction.  If the types are different,
1766         // then the shuffle is widening or truncating the input vectors, and
1767         // the argument type must also be encoded.
1768         if (C->getType() == C->getOperand(0)->getType()) {
1769           Code = bitc::CST_CODE_CE_SHUFFLEVEC;
1770         } else {
1771           Code = bitc::CST_CODE_CE_SHUFVEC_EX;
1772           Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
1773         }
1774         Record.push_back(VE.getValueID(C->getOperand(0)));
1775         Record.push_back(VE.getValueID(C->getOperand(1)));
1776         Record.push_back(VE.getValueID(C->getOperand(2)));
1777         break;
1778       case Instruction::ICmp:
1779       case Instruction::FCmp:
1780         Code = bitc::CST_CODE_CE_CMP;
1781         Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
1782         Record.push_back(VE.getValueID(C->getOperand(0)));
1783         Record.push_back(VE.getValueID(C->getOperand(1)));
1784         Record.push_back(CE->getPredicate());
1785         break;
1786       }
1787     } else if (const BlockAddress *BA = dyn_cast<BlockAddress>(C)) {
1788       Code = bitc::CST_CODE_BLOCKADDRESS;
1789       Record.push_back(VE.getTypeID(BA->getFunction()->getType()));
1790       Record.push_back(VE.getValueID(BA->getFunction()));
1791       Record.push_back(VE.getGlobalBasicBlockID(BA->getBasicBlock()));
1792     } else {
1793 #ifndef NDEBUG
1794       C->dump();
1795 #endif
1796       llvm_unreachable("Unknown constant!");
1797     }
1798     Stream.EmitRecord(Code, Record, AbbrevToUse);
1799     Record.clear();
1800   }
1801 
1802   Stream.ExitBlock();
1803 }
1804 
1805 static void WriteModuleConstants(const ValueEnumerator &VE,
1806                                  BitstreamWriter &Stream) {
1807   const ValueEnumerator::ValueList &Vals = VE.getValues();
1808 
1809   // Find the first constant to emit, which is the first non-globalvalue value.
1810   // We know globalvalues have been emitted by WriteModuleInfo.
1811   for (unsigned i = 0, e = Vals.size(); i != e; ++i) {
1812     if (!isa<GlobalValue>(Vals[i].first)) {
1813       WriteConstants(i, Vals.size(), VE, Stream, true);
1814       return;
1815     }
1816   }
1817 }
1818 
1819 /// PushValueAndType - The file has to encode both the value and type id for
1820 /// many values, because we need to know what type to create for forward
1821 /// references.  However, most operands are not forward references, so this type
1822 /// field is not needed.
1823 ///
1824 /// This function adds V's value ID to Vals.  If the value ID is higher than the
1825 /// instruction ID, then it is a forward reference, and it also includes the
1826 /// type ID.  The value ID that is written is encoded relative to the InstID.
1827 static bool PushValueAndType(const Value *V, unsigned InstID,
1828                              SmallVectorImpl<unsigned> &Vals,
1829                              ValueEnumerator &VE) {
1830   unsigned ValID = VE.getValueID(V);
1831   // Make encoding relative to the InstID.
1832   Vals.push_back(InstID - ValID);
1833   if (ValID >= InstID) {
1834     Vals.push_back(VE.getTypeID(V->getType()));
1835     return true;
1836   }
1837   return false;
1838 }
1839 
1840 static void WriteOperandBundles(BitstreamWriter &Stream, ImmutableCallSite CS,
1841                                 unsigned InstID, ValueEnumerator &VE) {
1842   SmallVector<unsigned, 64> Record;
1843   LLVMContext &C = CS.getInstruction()->getContext();
1844 
1845   for (unsigned i = 0, e = CS.getNumOperandBundles(); i != e; ++i) {
1846     const auto &Bundle = CS.getOperandBundleAt(i);
1847     Record.push_back(C.getOperandBundleTagID(Bundle.getTagName()));
1848 
1849     for (auto &Input : Bundle.Inputs)
1850       PushValueAndType(Input, InstID, Record, VE);
1851 
1852     Stream.EmitRecord(bitc::FUNC_CODE_OPERAND_BUNDLE, Record);
1853     Record.clear();
1854   }
1855 }
1856 
1857 /// pushValue - Like PushValueAndType, but where the type of the value is
1858 /// omitted (perhaps it was already encoded in an earlier operand).
1859 static void pushValue(const Value *V, unsigned InstID,
1860                       SmallVectorImpl<unsigned> &Vals,
1861                       ValueEnumerator &VE) {
1862   unsigned ValID = VE.getValueID(V);
1863   Vals.push_back(InstID - ValID);
1864 }
1865 
1866 static void pushValueSigned(const Value *V, unsigned InstID,
1867                             SmallVectorImpl<uint64_t> &Vals,
1868                             ValueEnumerator &VE) {
1869   unsigned ValID = VE.getValueID(V);
1870   int64_t diff = ((int32_t)InstID - (int32_t)ValID);
1871   emitSignedInt64(Vals, diff);
1872 }
1873 
1874 /// WriteInstruction - Emit an instruction to the specified stream.
1875 static void WriteInstruction(const Instruction &I, unsigned InstID,
1876                              ValueEnumerator &VE, BitstreamWriter &Stream,
1877                              SmallVectorImpl<unsigned> &Vals) {
1878   unsigned Code = 0;
1879   unsigned AbbrevToUse = 0;
1880   VE.setInstructionID(&I);
1881   switch (I.getOpcode()) {
1882   default:
1883     if (Instruction::isCast(I.getOpcode())) {
1884       Code = bitc::FUNC_CODE_INST_CAST;
1885       if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
1886         AbbrevToUse = FUNCTION_INST_CAST_ABBREV;
1887       Vals.push_back(VE.getTypeID(I.getType()));
1888       Vals.push_back(GetEncodedCastOpcode(I.getOpcode()));
1889     } else {
1890       assert(isa<BinaryOperator>(I) && "Unknown instruction!");
1891       Code = bitc::FUNC_CODE_INST_BINOP;
1892       if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
1893         AbbrevToUse = FUNCTION_INST_BINOP_ABBREV;
1894       pushValue(I.getOperand(1), InstID, Vals, VE);
1895       Vals.push_back(GetEncodedBinaryOpcode(I.getOpcode()));
1896       uint64_t Flags = GetOptimizationFlags(&I);
1897       if (Flags != 0) {
1898         if (AbbrevToUse == FUNCTION_INST_BINOP_ABBREV)
1899           AbbrevToUse = FUNCTION_INST_BINOP_FLAGS_ABBREV;
1900         Vals.push_back(Flags);
1901       }
1902     }
1903     break;
1904 
1905   case Instruction::GetElementPtr: {
1906     Code = bitc::FUNC_CODE_INST_GEP;
1907     AbbrevToUse = FUNCTION_INST_GEP_ABBREV;
1908     auto &GEPInst = cast<GetElementPtrInst>(I);
1909     Vals.push_back(GEPInst.isInBounds());
1910     Vals.push_back(VE.getTypeID(GEPInst.getSourceElementType()));
1911     for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
1912       PushValueAndType(I.getOperand(i), InstID, Vals, VE);
1913     break;
1914   }
1915   case Instruction::ExtractValue: {
1916     Code = bitc::FUNC_CODE_INST_EXTRACTVAL;
1917     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1918     const ExtractValueInst *EVI = cast<ExtractValueInst>(&I);
1919     Vals.append(EVI->idx_begin(), EVI->idx_end());
1920     break;
1921   }
1922   case Instruction::InsertValue: {
1923     Code = bitc::FUNC_CODE_INST_INSERTVAL;
1924     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1925     PushValueAndType(I.getOperand(1), InstID, Vals, VE);
1926     const InsertValueInst *IVI = cast<InsertValueInst>(&I);
1927     Vals.append(IVI->idx_begin(), IVI->idx_end());
1928     break;
1929   }
1930   case Instruction::Select:
1931     Code = bitc::FUNC_CODE_INST_VSELECT;
1932     PushValueAndType(I.getOperand(1), InstID, Vals, VE);
1933     pushValue(I.getOperand(2), InstID, Vals, VE);
1934     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1935     break;
1936   case Instruction::ExtractElement:
1937     Code = bitc::FUNC_CODE_INST_EXTRACTELT;
1938     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1939     PushValueAndType(I.getOperand(1), InstID, Vals, VE);
1940     break;
1941   case Instruction::InsertElement:
1942     Code = bitc::FUNC_CODE_INST_INSERTELT;
1943     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1944     pushValue(I.getOperand(1), InstID, Vals, VE);
1945     PushValueAndType(I.getOperand(2), InstID, Vals, VE);
1946     break;
1947   case Instruction::ShuffleVector:
1948     Code = bitc::FUNC_CODE_INST_SHUFFLEVEC;
1949     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1950     pushValue(I.getOperand(1), InstID, Vals, VE);
1951     pushValue(I.getOperand(2), InstID, Vals, VE);
1952     break;
1953   case Instruction::ICmp:
1954   case Instruction::FCmp: {
1955     // compare returning Int1Ty or vector of Int1Ty
1956     Code = bitc::FUNC_CODE_INST_CMP2;
1957     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1958     pushValue(I.getOperand(1), InstID, Vals, VE);
1959     Vals.push_back(cast<CmpInst>(I).getPredicate());
1960     uint64_t Flags = GetOptimizationFlags(&I);
1961     if (Flags != 0)
1962       Vals.push_back(Flags);
1963     break;
1964   }
1965 
1966   case Instruction::Ret:
1967     {
1968       Code = bitc::FUNC_CODE_INST_RET;
1969       unsigned NumOperands = I.getNumOperands();
1970       if (NumOperands == 0)
1971         AbbrevToUse = FUNCTION_INST_RET_VOID_ABBREV;
1972       else if (NumOperands == 1) {
1973         if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
1974           AbbrevToUse = FUNCTION_INST_RET_VAL_ABBREV;
1975       } else {
1976         for (unsigned i = 0, e = NumOperands; i != e; ++i)
1977           PushValueAndType(I.getOperand(i), InstID, Vals, VE);
1978       }
1979     }
1980     break;
1981   case Instruction::Br:
1982     {
1983       Code = bitc::FUNC_CODE_INST_BR;
1984       const BranchInst &II = cast<BranchInst>(I);
1985       Vals.push_back(VE.getValueID(II.getSuccessor(0)));
1986       if (II.isConditional()) {
1987         Vals.push_back(VE.getValueID(II.getSuccessor(1)));
1988         pushValue(II.getCondition(), InstID, Vals, VE);
1989       }
1990     }
1991     break;
1992   case Instruction::Switch:
1993     {
1994       Code = bitc::FUNC_CODE_INST_SWITCH;
1995       const SwitchInst &SI = cast<SwitchInst>(I);
1996       Vals.push_back(VE.getTypeID(SI.getCondition()->getType()));
1997       pushValue(SI.getCondition(), InstID, Vals, VE);
1998       Vals.push_back(VE.getValueID(SI.getDefaultDest()));
1999       for (SwitchInst::ConstCaseIt Case : SI.cases()) {
2000         Vals.push_back(VE.getValueID(Case.getCaseValue()));
2001         Vals.push_back(VE.getValueID(Case.getCaseSuccessor()));
2002       }
2003     }
2004     break;
2005   case Instruction::IndirectBr:
2006     Code = bitc::FUNC_CODE_INST_INDIRECTBR;
2007     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));
2008     // Encode the address operand as relative, but not the basic blocks.
2009     pushValue(I.getOperand(0), InstID, Vals, VE);
2010     for (unsigned i = 1, e = I.getNumOperands(); i != e; ++i)
2011       Vals.push_back(VE.getValueID(I.getOperand(i)));
2012     break;
2013 
2014   case Instruction::Invoke: {
2015     const InvokeInst *II = cast<InvokeInst>(&I);
2016     const Value *Callee = II->getCalledValue();
2017     FunctionType *FTy = II->getFunctionType();
2018 
2019     if (II->hasOperandBundles())
2020       WriteOperandBundles(Stream, II, InstID, VE);
2021 
2022     Code = bitc::FUNC_CODE_INST_INVOKE;
2023 
2024     Vals.push_back(VE.getAttributeID(II->getAttributes()));
2025     Vals.push_back(II->getCallingConv() | 1 << 13);
2026     Vals.push_back(VE.getValueID(II->getNormalDest()));
2027     Vals.push_back(VE.getValueID(II->getUnwindDest()));
2028     Vals.push_back(VE.getTypeID(FTy));
2029     PushValueAndType(Callee, InstID, Vals, VE);
2030 
2031     // Emit value #'s for the fixed parameters.
2032     for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i)
2033       pushValue(I.getOperand(i), InstID, Vals, VE);  // fixed param.
2034 
2035     // Emit type/value pairs for varargs params.
2036     if (FTy->isVarArg()) {
2037       for (unsigned i = FTy->getNumParams(), e = I.getNumOperands()-3;
2038            i != e; ++i)
2039         PushValueAndType(I.getOperand(i), InstID, Vals, VE); // vararg
2040     }
2041     break;
2042   }
2043   case Instruction::Resume:
2044     Code = bitc::FUNC_CODE_INST_RESUME;
2045     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
2046     break;
2047   case Instruction::CleanupRet: {
2048     Code = bitc::FUNC_CODE_INST_CLEANUPRET;
2049     const auto &CRI = cast<CleanupReturnInst>(I);
2050     pushValue(CRI.getCleanupPad(), InstID, Vals, VE);
2051     if (CRI.hasUnwindDest())
2052       Vals.push_back(VE.getValueID(CRI.getUnwindDest()));
2053     break;
2054   }
2055   case Instruction::CatchRet: {
2056     Code = bitc::FUNC_CODE_INST_CATCHRET;
2057     const auto &CRI = cast<CatchReturnInst>(I);
2058     pushValue(CRI.getCatchPad(), InstID, Vals, VE);
2059     Vals.push_back(VE.getValueID(CRI.getSuccessor()));
2060     break;
2061   }
2062   case Instruction::CleanupPad:
2063   case Instruction::CatchPad: {
2064     const auto &FuncletPad = cast<FuncletPadInst>(I);
2065     Code = isa<CatchPadInst>(FuncletPad) ? bitc::FUNC_CODE_INST_CATCHPAD
2066                                          : bitc::FUNC_CODE_INST_CLEANUPPAD;
2067     pushValue(FuncletPad.getParentPad(), InstID, Vals, VE);
2068 
2069     unsigned NumArgOperands = FuncletPad.getNumArgOperands();
2070     Vals.push_back(NumArgOperands);
2071     for (unsigned Op = 0; Op != NumArgOperands; ++Op)
2072       PushValueAndType(FuncletPad.getArgOperand(Op), InstID, Vals, VE);
2073     break;
2074   }
2075   case Instruction::CatchSwitch: {
2076     Code = bitc::FUNC_CODE_INST_CATCHSWITCH;
2077     const auto &CatchSwitch = cast<CatchSwitchInst>(I);
2078 
2079     pushValue(CatchSwitch.getParentPad(), InstID, Vals, VE);
2080 
2081     unsigned NumHandlers = CatchSwitch.getNumHandlers();
2082     Vals.push_back(NumHandlers);
2083     for (const BasicBlock *CatchPadBB : CatchSwitch.handlers())
2084       Vals.push_back(VE.getValueID(CatchPadBB));
2085 
2086     if (CatchSwitch.hasUnwindDest())
2087       Vals.push_back(VE.getValueID(CatchSwitch.getUnwindDest()));
2088     break;
2089   }
2090   case Instruction::Unreachable:
2091     Code = bitc::FUNC_CODE_INST_UNREACHABLE;
2092     AbbrevToUse = FUNCTION_INST_UNREACHABLE_ABBREV;
2093     break;
2094 
2095   case Instruction::PHI: {
2096     const PHINode &PN = cast<PHINode>(I);
2097     Code = bitc::FUNC_CODE_INST_PHI;
2098     // With the newer instruction encoding, forward references could give
2099     // negative valued IDs.  This is most common for PHIs, so we use
2100     // signed VBRs.
2101     SmallVector<uint64_t, 128> Vals64;
2102     Vals64.push_back(VE.getTypeID(PN.getType()));
2103     for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) {
2104       pushValueSigned(PN.getIncomingValue(i), InstID, Vals64, VE);
2105       Vals64.push_back(VE.getValueID(PN.getIncomingBlock(i)));
2106     }
2107     // Emit a Vals64 vector and exit.
2108     Stream.EmitRecord(Code, Vals64, AbbrevToUse);
2109     Vals64.clear();
2110     return;
2111   }
2112 
2113   case Instruction::LandingPad: {
2114     const LandingPadInst &LP = cast<LandingPadInst>(I);
2115     Code = bitc::FUNC_CODE_INST_LANDINGPAD;
2116     Vals.push_back(VE.getTypeID(LP.getType()));
2117     Vals.push_back(LP.isCleanup());
2118     Vals.push_back(LP.getNumClauses());
2119     for (unsigned I = 0, E = LP.getNumClauses(); I != E; ++I) {
2120       if (LP.isCatch(I))
2121         Vals.push_back(LandingPadInst::Catch);
2122       else
2123         Vals.push_back(LandingPadInst::Filter);
2124       PushValueAndType(LP.getClause(I), InstID, Vals, VE);
2125     }
2126     break;
2127   }
2128 
2129   case Instruction::Alloca: {
2130     Code = bitc::FUNC_CODE_INST_ALLOCA;
2131     const AllocaInst &AI = cast<AllocaInst>(I);
2132     Vals.push_back(VE.getTypeID(AI.getAllocatedType()));
2133     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));
2134     Vals.push_back(VE.getValueID(I.getOperand(0))); // size.
2135     unsigned AlignRecord = Log2_32(AI.getAlignment()) + 1;
2136     assert(Log2_32(Value::MaximumAlignment) + 1 < 1 << 5 &&
2137            "not enough bits for maximum alignment");
2138     assert(AlignRecord < 1 << 5 && "alignment greater than 1 << 64");
2139     AlignRecord |= AI.isUsedWithInAlloca() << 5;
2140     AlignRecord |= 1 << 6;
2141     // Reserve bit 7 for SwiftError flag.
2142     // AlignRecord |= AI.isSwiftError() << 7;
2143     Vals.push_back(AlignRecord);
2144     break;
2145   }
2146 
2147   case Instruction::Load:
2148     if (cast<LoadInst>(I).isAtomic()) {
2149       Code = bitc::FUNC_CODE_INST_LOADATOMIC;
2150       PushValueAndType(I.getOperand(0), InstID, Vals, VE);
2151     } else {
2152       Code = bitc::FUNC_CODE_INST_LOAD;
2153       if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))  // ptr
2154         AbbrevToUse = FUNCTION_INST_LOAD_ABBREV;
2155     }
2156     Vals.push_back(VE.getTypeID(I.getType()));
2157     Vals.push_back(Log2_32(cast<LoadInst>(I).getAlignment())+1);
2158     Vals.push_back(cast<LoadInst>(I).isVolatile());
2159     if (cast<LoadInst>(I).isAtomic()) {
2160       Vals.push_back(GetEncodedOrdering(cast<LoadInst>(I).getOrdering()));
2161       Vals.push_back(GetEncodedSynchScope(cast<LoadInst>(I).getSynchScope()));
2162     }
2163     break;
2164   case Instruction::Store:
2165     if (cast<StoreInst>(I).isAtomic())
2166       Code = bitc::FUNC_CODE_INST_STOREATOMIC;
2167     else
2168       Code = bitc::FUNC_CODE_INST_STORE;
2169     PushValueAndType(I.getOperand(1), InstID, Vals, VE);  // ptrty + ptr
2170     PushValueAndType(I.getOperand(0), InstID, Vals, VE);  // valty + val
2171     Vals.push_back(Log2_32(cast<StoreInst>(I).getAlignment())+1);
2172     Vals.push_back(cast<StoreInst>(I).isVolatile());
2173     if (cast<StoreInst>(I).isAtomic()) {
2174       Vals.push_back(GetEncodedOrdering(cast<StoreInst>(I).getOrdering()));
2175       Vals.push_back(GetEncodedSynchScope(cast<StoreInst>(I).getSynchScope()));
2176     }
2177     break;
2178   case Instruction::AtomicCmpXchg:
2179     Code = bitc::FUNC_CODE_INST_CMPXCHG;
2180     PushValueAndType(I.getOperand(0), InstID, Vals, VE);  // ptrty + ptr
2181     PushValueAndType(I.getOperand(1), InstID, Vals, VE);  // cmp.
2182     pushValue(I.getOperand(2), InstID, Vals, VE);         // newval.
2183     Vals.push_back(cast<AtomicCmpXchgInst>(I).isVolatile());
2184     Vals.push_back(GetEncodedOrdering(
2185                      cast<AtomicCmpXchgInst>(I).getSuccessOrdering()));
2186     Vals.push_back(GetEncodedSynchScope(
2187                      cast<AtomicCmpXchgInst>(I).getSynchScope()));
2188     Vals.push_back(GetEncodedOrdering(
2189                      cast<AtomicCmpXchgInst>(I).getFailureOrdering()));
2190     Vals.push_back(cast<AtomicCmpXchgInst>(I).isWeak());
2191     break;
2192   case Instruction::AtomicRMW:
2193     Code = bitc::FUNC_CODE_INST_ATOMICRMW;
2194     PushValueAndType(I.getOperand(0), InstID, Vals, VE);  // ptrty + ptr
2195     pushValue(I.getOperand(1), InstID, Vals, VE);         // val.
2196     Vals.push_back(GetEncodedRMWOperation(
2197                      cast<AtomicRMWInst>(I).getOperation()));
2198     Vals.push_back(cast<AtomicRMWInst>(I).isVolatile());
2199     Vals.push_back(GetEncodedOrdering(cast<AtomicRMWInst>(I).getOrdering()));
2200     Vals.push_back(GetEncodedSynchScope(
2201                      cast<AtomicRMWInst>(I).getSynchScope()));
2202     break;
2203   case Instruction::Fence:
2204     Code = bitc::FUNC_CODE_INST_FENCE;
2205     Vals.push_back(GetEncodedOrdering(cast<FenceInst>(I).getOrdering()));
2206     Vals.push_back(GetEncodedSynchScope(cast<FenceInst>(I).getSynchScope()));
2207     break;
2208   case Instruction::Call: {
2209     const CallInst &CI = cast<CallInst>(I);
2210     FunctionType *FTy = CI.getFunctionType();
2211 
2212     if (CI.hasOperandBundles())
2213       WriteOperandBundles(Stream, &CI, InstID, VE);
2214 
2215     Code = bitc::FUNC_CODE_INST_CALL;
2216 
2217     Vals.push_back(VE.getAttributeID(CI.getAttributes()));
2218 
2219     unsigned Flags = GetOptimizationFlags(&I);
2220     Vals.push_back(CI.getCallingConv() << bitc::CALL_CCONV |
2221                    unsigned(CI.isTailCall()) << bitc::CALL_TAIL |
2222                    unsigned(CI.isMustTailCall()) << bitc::CALL_MUSTTAIL |
2223                    1 << bitc::CALL_EXPLICIT_TYPE |
2224                    unsigned(CI.isNoTailCall()) << bitc::CALL_NOTAIL |
2225                    unsigned(Flags != 0) << bitc::CALL_FMF);
2226     if (Flags != 0)
2227       Vals.push_back(Flags);
2228 
2229     Vals.push_back(VE.getTypeID(FTy));
2230     PushValueAndType(CI.getCalledValue(), InstID, Vals, VE);  // Callee
2231 
2232     // Emit value #'s for the fixed parameters.
2233     for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i) {
2234       // Check for labels (can happen with asm labels).
2235       if (FTy->getParamType(i)->isLabelTy())
2236         Vals.push_back(VE.getValueID(CI.getArgOperand(i)));
2237       else
2238         pushValue(CI.getArgOperand(i), InstID, Vals, VE);  // fixed param.
2239     }
2240 
2241     // Emit type/value pairs for varargs params.
2242     if (FTy->isVarArg()) {
2243       for (unsigned i = FTy->getNumParams(), e = CI.getNumArgOperands();
2244            i != e; ++i)
2245         PushValueAndType(CI.getArgOperand(i), InstID, Vals, VE);  // varargs
2246     }
2247     break;
2248   }
2249   case Instruction::VAArg:
2250     Code = bitc::FUNC_CODE_INST_VAARG;
2251     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));   // valistty
2252     pushValue(I.getOperand(0), InstID, Vals, VE); // valist.
2253     Vals.push_back(VE.getTypeID(I.getType())); // restype.
2254     break;
2255   }
2256 
2257   Stream.EmitRecord(Code, Vals, AbbrevToUse);
2258   Vals.clear();
2259 }
2260 
2261 /// Emit names for globals/functions etc. The VSTOffsetPlaceholder,
2262 /// BitcodeStartBit and ModuleSummaryIndex are only passed for the module-level
2263 /// VST, where we are including a function bitcode index and need to
2264 /// backpatch the VST forward declaration record.
2265 static void WriteValueSymbolTable(
2266     const ValueSymbolTable &VST, const ValueEnumerator &VE,
2267     BitstreamWriter &Stream, uint64_t VSTOffsetPlaceholder = 0,
2268     uint64_t BitcodeStartBit = 0,
2269     DenseMap<const Function *, std::unique_ptr<GlobalValueInfo>>
2270         *FunctionIndex = nullptr) {
2271   if (VST.empty()) {
2272     // WriteValueSymbolTableForwardDecl should have returned early as
2273     // well. Ensure this handling remains in sync by asserting that
2274     // the placeholder offset is not set.
2275     assert(VSTOffsetPlaceholder == 0);
2276     return;
2277   }
2278 
2279   if (VSTOffsetPlaceholder > 0) {
2280     // Get the offset of the VST we are writing, and backpatch it into
2281     // the VST forward declaration record.
2282     uint64_t VSTOffset = Stream.GetCurrentBitNo();
2283     // The BitcodeStartBit was the stream offset of the actual bitcode
2284     // (e.g. excluding any initial darwin header).
2285     VSTOffset -= BitcodeStartBit;
2286     assert((VSTOffset & 31) == 0 && "VST block not 32-bit aligned");
2287     Stream.BackpatchWord(VSTOffsetPlaceholder, VSTOffset / 32);
2288   }
2289 
2290   Stream.EnterSubblock(bitc::VALUE_SYMTAB_BLOCK_ID, 4);
2291 
2292   // For the module-level VST, add abbrev Ids for the VST_CODE_FNENTRY
2293   // records, which are not used in the per-function VSTs.
2294   unsigned FnEntry8BitAbbrev;
2295   unsigned FnEntry7BitAbbrev;
2296   unsigned FnEntry6BitAbbrev;
2297   if (VSTOffsetPlaceholder > 0) {
2298     // 8-bit fixed-width VST_CODE_FNENTRY function strings.
2299     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2300     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_FNENTRY));
2301     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // value id
2302     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // funcoffset
2303     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2304     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
2305     FnEntry8BitAbbrev = Stream.EmitAbbrev(Abbv);
2306 
2307     // 7-bit fixed width VST_CODE_FNENTRY function strings.
2308     Abbv = new BitCodeAbbrev();
2309     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_FNENTRY));
2310     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // value id
2311     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // funcoffset
2312     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2313     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
2314     FnEntry7BitAbbrev = Stream.EmitAbbrev(Abbv);
2315 
2316     // 6-bit char6 VST_CODE_FNENTRY function strings.
2317     Abbv = new BitCodeAbbrev();
2318     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_FNENTRY));
2319     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // value id
2320     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // funcoffset
2321     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2322     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
2323     FnEntry6BitAbbrev = Stream.EmitAbbrev(Abbv);
2324   }
2325 
2326   // FIXME: Set up the abbrev, we know how many values there are!
2327   // FIXME: We know if the type names can use 7-bit ascii.
2328   SmallVector<unsigned, 64> NameVals;
2329 
2330   for (const ValueName &Name : VST) {
2331     // Figure out the encoding to use for the name.
2332     StringEncoding Bits =
2333         getStringEncoding(Name.getKeyData(), Name.getKeyLength());
2334 
2335     unsigned AbbrevToUse = VST_ENTRY_8_ABBREV;
2336     NameVals.push_back(VE.getValueID(Name.getValue()));
2337 
2338     Function *F = dyn_cast<Function>(Name.getValue());
2339     if (!F) {
2340       // If value is an alias, need to get the aliased base object to
2341       // see if it is a function.
2342       auto *GA = dyn_cast<GlobalAlias>(Name.getValue());
2343       if (GA && GA->getBaseObject())
2344         F = dyn_cast<Function>(GA->getBaseObject());
2345     }
2346 
2347     // VST_CODE_ENTRY:   [valueid, namechar x N]
2348     // VST_CODE_FNENTRY: [valueid, funcoffset, namechar x N]
2349     // VST_CODE_BBENTRY: [bbid, namechar x N]
2350     unsigned Code;
2351     if (isa<BasicBlock>(Name.getValue())) {
2352       Code = bitc::VST_CODE_BBENTRY;
2353       if (Bits == SE_Char6)
2354         AbbrevToUse = VST_BBENTRY_6_ABBREV;
2355     } else if (F && !F->isDeclaration()) {
2356       // Must be the module-level VST, where we pass in the Index and
2357       // have a VSTOffsetPlaceholder. The function-level VST should not
2358       // contain any Function symbols.
2359       assert(FunctionIndex);
2360       assert(VSTOffsetPlaceholder > 0);
2361 
2362       // Save the word offset of the function (from the start of the
2363       // actual bitcode written to the stream).
2364       uint64_t BitcodeIndex =
2365           (*FunctionIndex)[F]->bitcodeIndex() - BitcodeStartBit;
2366       assert((BitcodeIndex & 31) == 0 && "function block not 32-bit aligned");
2367       NameVals.push_back(BitcodeIndex / 32);
2368 
2369       Code = bitc::VST_CODE_FNENTRY;
2370       AbbrevToUse = FnEntry8BitAbbrev;
2371       if (Bits == SE_Char6)
2372         AbbrevToUse = FnEntry6BitAbbrev;
2373       else if (Bits == SE_Fixed7)
2374         AbbrevToUse = FnEntry7BitAbbrev;
2375     } else {
2376       Code = bitc::VST_CODE_ENTRY;
2377       if (Bits == SE_Char6)
2378         AbbrevToUse = VST_ENTRY_6_ABBREV;
2379       else if (Bits == SE_Fixed7)
2380         AbbrevToUse = VST_ENTRY_7_ABBREV;
2381     }
2382 
2383     for (const auto P : Name.getKey())
2384       NameVals.push_back((unsigned char)P);
2385 
2386     // Emit the finished record.
2387     Stream.EmitRecord(Code, NameVals, AbbrevToUse);
2388     NameVals.clear();
2389   }
2390   Stream.ExitBlock();
2391 }
2392 
2393 /// Emit function names and summary offsets for the combined index
2394 /// used by ThinLTO.
2395 static void
2396 WriteCombinedValueSymbolTable(const ModuleSummaryIndex &Index,
2397                               BitstreamWriter &Stream,
2398                               std::map<uint64_t, unsigned> &GUIDToValueIdMap,
2399                               uint64_t VSTOffsetPlaceholder) {
2400   assert(VSTOffsetPlaceholder > 0 && "Expected non-zero VSTOffsetPlaceholder");
2401   // Get the offset of the VST we are writing, and backpatch it into
2402   // the VST forward declaration record.
2403   uint64_t VSTOffset = Stream.GetCurrentBitNo();
2404   assert((VSTOffset & 31) == 0 && "VST block not 32-bit aligned");
2405   Stream.BackpatchWord(VSTOffsetPlaceholder, VSTOffset / 32);
2406 
2407   Stream.EnterSubblock(bitc::VALUE_SYMTAB_BLOCK_ID, 4);
2408 
2409   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2410   Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_COMBINED_GVDEFENTRY));
2411   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // valueid
2412   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // sumoffset
2413   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // guid
2414   unsigned DefEntryAbbrev = Stream.EmitAbbrev(Abbv);
2415 
2416   Abbv = new BitCodeAbbrev();
2417   Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_COMBINED_ENTRY));
2418   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // valueid
2419   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // refguid
2420   unsigned EntryAbbrev = Stream.EmitAbbrev(Abbv);
2421 
2422   SmallVector<uint64_t, 64> NameVals;
2423 
2424   for (const auto &FII : Index) {
2425     uint64_t FuncGUID = FII.first;
2426     const auto &VMI = GUIDToValueIdMap.find(FuncGUID);
2427     assert(VMI != GUIDToValueIdMap.end());
2428 
2429     for (const auto &FI : FII.second) {
2430       // VST_CODE_COMBINED_GVDEFENTRY: [valueid, sumoffset, guid]
2431       NameVals.push_back(VMI->second);
2432       NameVals.push_back(FI->bitcodeIndex());
2433       NameVals.push_back(FuncGUID);
2434 
2435       // Emit the finished record.
2436       Stream.EmitRecord(bitc::VST_CODE_COMBINED_GVDEFENTRY, NameVals,
2437                         DefEntryAbbrev);
2438       NameVals.clear();
2439     }
2440     GUIDToValueIdMap.erase(VMI);
2441   }
2442   for (const auto &GVI : GUIDToValueIdMap) {
2443     // VST_CODE_COMBINED_ENTRY: [valueid, refguid]
2444     NameVals.push_back(GVI.second);
2445     NameVals.push_back(GVI.first);
2446 
2447     // Emit the finished record.
2448     Stream.EmitRecord(bitc::VST_CODE_COMBINED_ENTRY, NameVals, EntryAbbrev);
2449     NameVals.clear();
2450   }
2451   Stream.ExitBlock();
2452 }
2453 
2454 static void WriteUseList(ValueEnumerator &VE, UseListOrder &&Order,
2455                          BitstreamWriter &Stream) {
2456   assert(Order.Shuffle.size() >= 2 && "Shuffle too small");
2457   unsigned Code;
2458   if (isa<BasicBlock>(Order.V))
2459     Code = bitc::USELIST_CODE_BB;
2460   else
2461     Code = bitc::USELIST_CODE_DEFAULT;
2462 
2463   SmallVector<uint64_t, 64> Record(Order.Shuffle.begin(), Order.Shuffle.end());
2464   Record.push_back(VE.getValueID(Order.V));
2465   Stream.EmitRecord(Code, Record);
2466 }
2467 
2468 static void WriteUseListBlock(const Function *F, ValueEnumerator &VE,
2469                               BitstreamWriter &Stream) {
2470   assert(VE.shouldPreserveUseListOrder() &&
2471          "Expected to be preserving use-list order");
2472 
2473   auto hasMore = [&]() {
2474     return !VE.UseListOrders.empty() && VE.UseListOrders.back().F == F;
2475   };
2476   if (!hasMore())
2477     // Nothing to do.
2478     return;
2479 
2480   Stream.EnterSubblock(bitc::USELIST_BLOCK_ID, 3);
2481   while (hasMore()) {
2482     WriteUseList(VE, std::move(VE.UseListOrders.back()), Stream);
2483     VE.UseListOrders.pop_back();
2484   }
2485   Stream.ExitBlock();
2486 }
2487 
2488 // Walk through the operands of a given User via worklist iteration and populate
2489 // the set of GlobalValue references encountered. Invoked either on an
2490 // Instruction or a GlobalVariable (which walks its initializer).
2491 static void findRefEdges(const User *CurUser, const ValueEnumerator &VE,
2492                          DenseSet<unsigned> &RefEdges,
2493                          SmallPtrSet<const User *, 8> &Visited) {
2494   SmallVector<const User *, 32> Worklist;
2495   Worklist.push_back(CurUser);
2496 
2497   while (!Worklist.empty()) {
2498     const User *U = Worklist.pop_back_val();
2499 
2500     if (!Visited.insert(U).second)
2501       continue;
2502 
2503     ImmutableCallSite CS(U);
2504 
2505     for (const auto &OI : U->operands()) {
2506       const User *Operand = dyn_cast<User>(OI);
2507       if (!Operand)
2508         continue;
2509       if (isa<BlockAddress>(Operand))
2510         continue;
2511       if (isa<GlobalValue>(Operand)) {
2512         // We have a reference to a global value. This should be added to
2513         // the reference set unless it is a callee. Callees are handled
2514         // specially by WriteFunction and are added to a separate list.
2515         if (!(CS && CS.isCallee(&OI)))
2516           RefEdges.insert(VE.getValueID(Operand));
2517         continue;
2518       }
2519       Worklist.push_back(Operand);
2520     }
2521   }
2522 }
2523 
2524 /// Emit a function body to the module stream.
2525 static void WriteFunction(
2526     const Function &F, const Module *M, ValueEnumerator &VE,
2527     BitstreamWriter &Stream,
2528     DenseMap<const Function *, std::unique_ptr<GlobalValueInfo>> &FunctionIndex,
2529     bool EmitSummaryIndex) {
2530   // Save the bitcode index of the start of this function block for recording
2531   // in the VST.
2532   uint64_t BitcodeIndex = Stream.GetCurrentBitNo();
2533 
2534   bool HasProfileData = F.getEntryCount().hasValue();
2535   std::unique_ptr<BlockFrequencyInfo> BFI;
2536   if (EmitSummaryIndex && HasProfileData) {
2537     Function &Func = const_cast<Function &>(F);
2538     LoopInfo LI{DominatorTree(Func)};
2539     BranchProbabilityInfo BPI{Func, LI};
2540     BFI = llvm::make_unique<BlockFrequencyInfo>(Func, BPI, LI);
2541   }
2542 
2543   Stream.EnterSubblock(bitc::FUNCTION_BLOCK_ID, 4);
2544   VE.incorporateFunction(F);
2545 
2546   SmallVector<unsigned, 64> Vals;
2547 
2548   // Emit the number of basic blocks, so the reader can create them ahead of
2549   // time.
2550   Vals.push_back(VE.getBasicBlocks().size());
2551   Stream.EmitRecord(bitc::FUNC_CODE_DECLAREBLOCKS, Vals);
2552   Vals.clear();
2553 
2554   // If there are function-local constants, emit them now.
2555   unsigned CstStart, CstEnd;
2556   VE.getFunctionConstantRange(CstStart, CstEnd);
2557   WriteConstants(CstStart, CstEnd, VE, Stream, false);
2558 
2559   // If there is function-local metadata, emit it now.
2560   writeFunctionMetadata(F, VE, Stream);
2561 
2562   // Keep a running idea of what the instruction ID is.
2563   unsigned InstID = CstEnd;
2564 
2565   bool NeedsMetadataAttachment = F.hasMetadata();
2566 
2567   DILocation *LastDL = nullptr;
2568   unsigned NumInsts = 0;
2569   // Map from callee ValueId to profile count. Used to accumulate profile
2570   // counts for all static calls to a given callee.
2571   DenseMap<unsigned, CalleeInfo> CallGraphEdges;
2572   DenseSet<unsigned> RefEdges;
2573 
2574   SmallPtrSet<const User *, 8> Visited;
2575   // Finally, emit all the instructions, in order.
2576   for (Function::const_iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
2577     for (BasicBlock::const_iterator I = BB->begin(), E = BB->end();
2578          I != E; ++I) {
2579       WriteInstruction(*I, InstID, VE, Stream, Vals);
2580 
2581       if (!isa<DbgInfoIntrinsic>(I))
2582         ++NumInsts;
2583 
2584       if (!I->getType()->isVoidTy())
2585         ++InstID;
2586 
2587       if (EmitSummaryIndex) {
2588         if (auto CS = ImmutableCallSite(&*I)) {
2589           auto *CalledFunction = CS.getCalledFunction();
2590           if (CalledFunction && CalledFunction->hasName() &&
2591               !CalledFunction->isIntrinsic()) {
2592             auto ScaledCount = BFI ? BFI->getBlockProfileCount(&*BB) : None;
2593             unsigned CalleeId = VE.getValueID(
2594                 M->getValueSymbolTable().lookup(CalledFunction->getName()));
2595             CallGraphEdges[CalleeId] +=
2596                 (ScaledCount ? ScaledCount.getValue() : 0);
2597           }
2598         }
2599         findRefEdges(&*I, VE, RefEdges, Visited);
2600       }
2601 
2602       // If the instruction has metadata, write a metadata attachment later.
2603       NeedsMetadataAttachment |= I->hasMetadataOtherThanDebugLoc();
2604 
2605       // If the instruction has a debug location, emit it.
2606       DILocation *DL = I->getDebugLoc();
2607       if (!DL)
2608         continue;
2609 
2610       if (DL == LastDL) {
2611         // Just repeat the same debug loc as last time.
2612         Stream.EmitRecord(bitc::FUNC_CODE_DEBUG_LOC_AGAIN, Vals);
2613         continue;
2614       }
2615 
2616       Vals.push_back(DL->getLine());
2617       Vals.push_back(DL->getColumn());
2618       Vals.push_back(VE.getMetadataOrNullID(DL->getScope()));
2619       Vals.push_back(VE.getMetadataOrNullID(DL->getInlinedAt()));
2620       Stream.EmitRecord(bitc::FUNC_CODE_DEBUG_LOC, Vals);
2621       Vals.clear();
2622 
2623       LastDL = DL;
2624     }
2625 
2626   std::unique_ptr<FunctionSummary> FuncSummary;
2627   if (EmitSummaryIndex) {
2628     FuncSummary = llvm::make_unique<FunctionSummary>(F.getLinkage(), NumInsts);
2629     FuncSummary->addCallGraphEdges(CallGraphEdges);
2630     FuncSummary->addRefEdges(RefEdges);
2631   }
2632   FunctionIndex[&F] =
2633       llvm::make_unique<GlobalValueInfo>(BitcodeIndex, std::move(FuncSummary));
2634 
2635   // Emit names for all the instructions etc.
2636   WriteValueSymbolTable(F.getValueSymbolTable(), VE, Stream);
2637 
2638   if (NeedsMetadataAttachment)
2639     WriteMetadataAttachment(F, VE, Stream);
2640   if (VE.shouldPreserveUseListOrder())
2641     WriteUseListBlock(&F, VE, Stream);
2642   VE.purgeFunction();
2643   Stream.ExitBlock();
2644 }
2645 
2646 // Emit blockinfo, which defines the standard abbreviations etc.
2647 static void WriteBlockInfo(const ValueEnumerator &VE, BitstreamWriter &Stream) {
2648   // We only want to emit block info records for blocks that have multiple
2649   // instances: CONSTANTS_BLOCK, FUNCTION_BLOCK and VALUE_SYMTAB_BLOCK.
2650   // Other blocks can define their abbrevs inline.
2651   Stream.EnterBlockInfoBlock(2);
2652 
2653   { // 8-bit fixed-width VST_CODE_ENTRY/VST_CODE_BBENTRY strings.
2654     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2655     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 3));
2656     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
2657     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2658     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
2659     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
2660                                    Abbv) != VST_ENTRY_8_ABBREV)
2661       llvm_unreachable("Unexpected abbrev ordering!");
2662   }
2663 
2664   { // 7-bit fixed width VST_CODE_ENTRY strings.
2665     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2666     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
2667     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
2668     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2669     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
2670     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
2671                                    Abbv) != VST_ENTRY_7_ABBREV)
2672       llvm_unreachable("Unexpected abbrev ordering!");
2673   }
2674   { // 6-bit char6 VST_CODE_ENTRY strings.
2675     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2676     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
2677     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
2678     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2679     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
2680     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
2681                                    Abbv) != VST_ENTRY_6_ABBREV)
2682       llvm_unreachable("Unexpected abbrev ordering!");
2683   }
2684   { // 6-bit char6 VST_CODE_BBENTRY strings.
2685     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2686     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_BBENTRY));
2687     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
2688     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2689     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
2690     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
2691                                    Abbv) != VST_BBENTRY_6_ABBREV)
2692       llvm_unreachable("Unexpected abbrev ordering!");
2693   }
2694 
2695 
2696 
2697   { // SETTYPE abbrev for CONSTANTS_BLOCK.
2698     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2699     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_SETTYPE));
2700     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
2701                               VE.computeBitsRequiredForTypeIndicies()));
2702     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
2703                                    Abbv) != CONSTANTS_SETTYPE_ABBREV)
2704       llvm_unreachable("Unexpected abbrev ordering!");
2705   }
2706 
2707   { // INTEGER abbrev for CONSTANTS_BLOCK.
2708     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2709     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_INTEGER));
2710     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
2711     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
2712                                    Abbv) != CONSTANTS_INTEGER_ABBREV)
2713       llvm_unreachable("Unexpected abbrev ordering!");
2714   }
2715 
2716   { // CE_CAST abbrev for CONSTANTS_BLOCK.
2717     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2718     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CE_CAST));
2719     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // cast opc
2720     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // typeid
2721                               VE.computeBitsRequiredForTypeIndicies()));
2722     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));    // value id
2723 
2724     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
2725                                    Abbv) != CONSTANTS_CE_CAST_Abbrev)
2726       llvm_unreachable("Unexpected abbrev ordering!");
2727   }
2728   { // NULL abbrev for CONSTANTS_BLOCK.
2729     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2730     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_NULL));
2731     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
2732                                    Abbv) != CONSTANTS_NULL_Abbrev)
2733       llvm_unreachable("Unexpected abbrev ordering!");
2734   }
2735 
2736   // FIXME: This should only use space for first class types!
2737 
2738   { // INST_LOAD abbrev for FUNCTION_BLOCK.
2739     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2740     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_LOAD));
2741     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Ptr
2742     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,    // dest ty
2743                               VE.computeBitsRequiredForTypeIndicies()));
2744     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4)); // Align
2745     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // volatile
2746     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
2747                                    Abbv) != FUNCTION_INST_LOAD_ABBREV)
2748       llvm_unreachable("Unexpected abbrev ordering!");
2749   }
2750   { // INST_BINOP abbrev for FUNCTION_BLOCK.
2751     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2752     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
2753     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
2754     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
2755     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
2756     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
2757                                    Abbv) != FUNCTION_INST_BINOP_ABBREV)
2758       llvm_unreachable("Unexpected abbrev ordering!");
2759   }
2760   { // INST_BINOP_FLAGS abbrev for FUNCTION_BLOCK.
2761     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2762     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
2763     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
2764     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
2765     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
2766     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7)); // flags
2767     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
2768                                    Abbv) != FUNCTION_INST_BINOP_FLAGS_ABBREV)
2769       llvm_unreachable("Unexpected abbrev ordering!");
2770   }
2771   { // INST_CAST abbrev for FUNCTION_BLOCK.
2772     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2773     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_CAST));
2774     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));    // OpVal
2775     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // dest ty
2776                               VE.computeBitsRequiredForTypeIndicies()));
2777     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // opc
2778     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
2779                                    Abbv) != FUNCTION_INST_CAST_ABBREV)
2780       llvm_unreachable("Unexpected abbrev ordering!");
2781   }
2782 
2783   { // INST_RET abbrev for FUNCTION_BLOCK.
2784     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2785     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
2786     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
2787                                    Abbv) != FUNCTION_INST_RET_VOID_ABBREV)
2788       llvm_unreachable("Unexpected abbrev ordering!");
2789   }
2790   { // INST_RET abbrev for FUNCTION_BLOCK.
2791     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2792     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
2793     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // ValID
2794     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
2795                                    Abbv) != FUNCTION_INST_RET_VAL_ABBREV)
2796       llvm_unreachable("Unexpected abbrev ordering!");
2797   }
2798   { // INST_UNREACHABLE abbrev for FUNCTION_BLOCK.
2799     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2800     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_UNREACHABLE));
2801     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
2802                                    Abbv) != FUNCTION_INST_UNREACHABLE_ABBREV)
2803       llvm_unreachable("Unexpected abbrev ordering!");
2804   }
2805   {
2806     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2807     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_GEP));
2808     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
2809     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, // dest ty
2810                               Log2_32_Ceil(VE.getTypes().size() + 1)));
2811     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2812     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
2813     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
2814         FUNCTION_INST_GEP_ABBREV)
2815       llvm_unreachable("Unexpected abbrev ordering!");
2816   }
2817 
2818   Stream.ExitBlock();
2819 }
2820 
2821 /// Write the module path strings, currently only used when generating
2822 /// a combined index file.
2823 static void WriteModStrings(const ModuleSummaryIndex &I,
2824                             BitstreamWriter &Stream) {
2825   Stream.EnterSubblock(bitc::MODULE_STRTAB_BLOCK_ID, 3);
2826 
2827   // TODO: See which abbrev sizes we actually need to emit
2828 
2829   // 8-bit fixed-width MST_ENTRY strings.
2830   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2831   Abbv->Add(BitCodeAbbrevOp(bitc::MST_CODE_ENTRY));
2832   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
2833   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2834   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
2835   unsigned Abbrev8Bit = Stream.EmitAbbrev(Abbv);
2836 
2837   // 7-bit fixed width MST_ENTRY strings.
2838   Abbv = new BitCodeAbbrev();
2839   Abbv->Add(BitCodeAbbrevOp(bitc::MST_CODE_ENTRY));
2840   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
2841   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2842   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
2843   unsigned Abbrev7Bit = Stream.EmitAbbrev(Abbv);
2844 
2845   // 6-bit char6 MST_ENTRY strings.
2846   Abbv = new BitCodeAbbrev();
2847   Abbv->Add(BitCodeAbbrevOp(bitc::MST_CODE_ENTRY));
2848   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
2849   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2850   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
2851   unsigned Abbrev6Bit = Stream.EmitAbbrev(Abbv);
2852 
2853   SmallVector<unsigned, 64> NameVals;
2854   for (const StringMapEntry<uint64_t> &MPSE : I.modulePaths()) {
2855     StringEncoding Bits =
2856         getStringEncoding(MPSE.getKey().data(), MPSE.getKey().size());
2857     unsigned AbbrevToUse = Abbrev8Bit;
2858     if (Bits == SE_Char6)
2859       AbbrevToUse = Abbrev6Bit;
2860     else if (Bits == SE_Fixed7)
2861       AbbrevToUse = Abbrev7Bit;
2862 
2863     NameVals.push_back(MPSE.getValue());
2864 
2865     for (const auto P : MPSE.getKey())
2866       NameVals.push_back((unsigned char)P);
2867 
2868     // Emit the finished record.
2869     Stream.EmitRecord(bitc::MST_CODE_ENTRY, NameVals, AbbrevToUse);
2870     NameVals.clear();
2871   }
2872   Stream.ExitBlock();
2873 }
2874 
2875 // Helper to emit a single function summary record.
2876 static void WritePerModuleFunctionSummaryRecord(
2877     SmallVector<uint64_t, 64> &NameVals, FunctionSummary *FS, unsigned ValueID,
2878     unsigned FSCallsAbbrev, unsigned FSCallsProfileAbbrev,
2879     BitstreamWriter &Stream, const Function &F) {
2880   assert(FS);
2881   NameVals.push_back(ValueID);
2882   NameVals.push_back(getEncodedLinkage(FS->linkage()));
2883   NameVals.push_back(FS->instCount());
2884   NameVals.push_back(FS->refs().size());
2885 
2886   for (auto &RI : FS->refs())
2887     NameVals.push_back(RI);
2888 
2889   bool HasProfileData = F.getEntryCount().hasValue();
2890   for (auto &ECI : FS->calls()) {
2891     NameVals.push_back(ECI.first);
2892     assert(ECI.second.CallsiteCount > 0 && "Expected at least one callsite");
2893     NameVals.push_back(ECI.second.CallsiteCount);
2894     if (HasProfileData)
2895       NameVals.push_back(ECI.second.ProfileCount);
2896   }
2897 
2898   unsigned FSAbbrev = (HasProfileData ? FSCallsProfileAbbrev : FSCallsAbbrev);
2899   unsigned Code =
2900       (HasProfileData ? bitc::FS_PERMODULE_PROFILE : bitc::FS_PERMODULE);
2901 
2902   // Emit the finished record.
2903   Stream.EmitRecord(Code, NameVals, FSAbbrev);
2904   NameVals.clear();
2905 }
2906 
2907 // Collect the global value references in the given variable's initializer,
2908 // and emit them in a summary record.
2909 static void WriteModuleLevelReferences(const GlobalVariable &V,
2910                                        const ValueEnumerator &VE,
2911                                        SmallVector<uint64_t, 64> &NameVals,
2912                                        unsigned FSModRefsAbbrev,
2913                                        BitstreamWriter &Stream) {
2914   // Only interested in recording variable defs in the summary.
2915   if (V.isDeclaration())
2916     return;
2917   DenseSet<unsigned> RefEdges;
2918   SmallPtrSet<const User *, 8> Visited;
2919   findRefEdges(&V, VE, RefEdges, Visited);
2920   NameVals.push_back(VE.getValueID(&V));
2921   NameVals.push_back(getEncodedLinkage(V.getLinkage()));
2922   for (auto RefId : RefEdges) {
2923     NameVals.push_back(RefId);
2924   }
2925   Stream.EmitRecord(bitc::FS_PERMODULE_GLOBALVAR_INIT_REFS, NameVals,
2926                     FSModRefsAbbrev);
2927   NameVals.clear();
2928 }
2929 
2930 /// Emit the per-module summary section alongside the rest of
2931 /// the module's bitcode.
2932 static void WritePerModuleGlobalValueSummary(
2933     DenseMap<const Function *, std::unique_ptr<GlobalValueInfo>> &FunctionIndex,
2934     const Module *M, const ValueEnumerator &VE, BitstreamWriter &Stream) {
2935   if (M->empty())
2936     return;
2937 
2938   Stream.EnterSubblock(bitc::GLOBALVAL_SUMMARY_BLOCK_ID, 3);
2939 
2940   // Abbrev for FS_PERMODULE.
2941   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2942   Abbv->Add(BitCodeAbbrevOp(bitc::FS_PERMODULE));
2943   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
2944   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 5)); // linkage
2945   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
2946   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
2947   // numrefs x valueid, n x (valueid, callsitecount)
2948   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2949   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
2950   unsigned FSCallsAbbrev = Stream.EmitAbbrev(Abbv);
2951 
2952   // Abbrev for FS_PERMODULE_PROFILE.
2953   Abbv = new BitCodeAbbrev();
2954   Abbv->Add(BitCodeAbbrevOp(bitc::FS_PERMODULE_PROFILE));
2955   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
2956   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 5)); // linkage
2957   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
2958   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
2959   // numrefs x valueid, n x (valueid, callsitecount, profilecount)
2960   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2961   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
2962   unsigned FSCallsProfileAbbrev = Stream.EmitAbbrev(Abbv);
2963 
2964   // Abbrev for FS_PERMODULE_GLOBALVAR_INIT_REFS.
2965   Abbv = new BitCodeAbbrev();
2966   Abbv->Add(BitCodeAbbrevOp(bitc::FS_PERMODULE_GLOBALVAR_INIT_REFS));
2967   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // valueid
2968   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 5)); // linkage
2969   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));  // valueids
2970   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
2971   unsigned FSModRefsAbbrev = Stream.EmitAbbrev(Abbv);
2972 
2973   SmallVector<uint64_t, 64> NameVals;
2974   // Iterate over the list of functions instead of the FunctionIndex map to
2975   // ensure the ordering is stable.
2976   for (const Function &F : *M) {
2977     if (F.isDeclaration())
2978       continue;
2979     // Skip anonymous functions. We will emit a function summary for
2980     // any aliases below.
2981     if (!F.hasName())
2982       continue;
2983 
2984     assert(FunctionIndex.count(&F) == 1);
2985 
2986     WritePerModuleFunctionSummaryRecord(
2987         NameVals, cast<FunctionSummary>(FunctionIndex[&F]->summary()),
2988         VE.getValueID(M->getValueSymbolTable().lookup(F.getName())),
2989         FSCallsAbbrev, FSCallsProfileAbbrev, Stream, F);
2990   }
2991 
2992   for (const GlobalAlias &A : M->aliases()) {
2993     if (!A.getBaseObject())
2994       continue;
2995     const Function *F = dyn_cast<Function>(A.getBaseObject());
2996     if (!F || F->isDeclaration())
2997       continue;
2998 
2999     assert(FunctionIndex.count(F) == 1);
3000     FunctionSummary *FS =
3001         cast<FunctionSummary>(FunctionIndex[F]->summary());
3002     // Add the alias to the reference list of aliasee function.
3003     FS->addRefEdge(
3004         VE.getValueID(M->getValueSymbolTable().lookup(A.getName())));
3005     WritePerModuleFunctionSummaryRecord(
3006         NameVals, FS,
3007         VE.getValueID(M->getValueSymbolTable().lookup(A.getName())),
3008         FSCallsAbbrev, FSCallsProfileAbbrev, Stream, *F);
3009   }
3010 
3011   // Capture references from GlobalVariable initializers, which are outside
3012   // of a function scope.
3013   for (const GlobalVariable &G : M->globals())
3014     WriteModuleLevelReferences(G, VE, NameVals, FSModRefsAbbrev, Stream);
3015   for (const GlobalAlias &A : M->aliases())
3016     if (auto *GV = dyn_cast<GlobalVariable>(A.getBaseObject()))
3017       WriteModuleLevelReferences(*GV, VE, NameVals, FSModRefsAbbrev, Stream);
3018 
3019   Stream.ExitBlock();
3020 }
3021 
3022 /// Emit the combined summary section into the combined index file.
3023 static void WriteCombinedGlobalValueSummary(
3024     const ModuleSummaryIndex &I, BitstreamWriter &Stream,
3025     std::map<uint64_t, unsigned> &GUIDToValueIdMap, unsigned GlobalValueId) {
3026   Stream.EnterSubblock(bitc::GLOBALVAL_SUMMARY_BLOCK_ID, 3);
3027 
3028   // Abbrev for FS_COMBINED.
3029   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
3030   Abbv->Add(BitCodeAbbrevOp(bitc::FS_COMBINED));
3031   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // modid
3032   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 5)); // linkage
3033   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
3034   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
3035   // numrefs x valueid, n x (valueid, callsitecount)
3036   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3037   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3038   unsigned FSCallsAbbrev = Stream.EmitAbbrev(Abbv);
3039 
3040   // Abbrev for FS_COMBINED_PROFILE.
3041   Abbv = new BitCodeAbbrev();
3042   Abbv->Add(BitCodeAbbrevOp(bitc::FS_COMBINED_PROFILE));
3043   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // modid
3044   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 5)); // linkage
3045   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
3046   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
3047   // numrefs x valueid, n x (valueid, callsitecount, profilecount)
3048   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3049   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3050   unsigned FSCallsProfileAbbrev = Stream.EmitAbbrev(Abbv);
3051 
3052   // Abbrev for FS_COMBINED_GLOBALVAR_INIT_REFS.
3053   Abbv = new BitCodeAbbrev();
3054   Abbv->Add(BitCodeAbbrevOp(bitc::FS_COMBINED_GLOBALVAR_INIT_REFS));
3055   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // modid
3056   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 5)); // linkage
3057   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));    // valueids
3058   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3059   unsigned FSModRefsAbbrev = Stream.EmitAbbrev(Abbv);
3060 
3061   SmallVector<uint64_t, 64> NameVals;
3062   for (const auto &FII : I) {
3063     for (auto &FI : FII.second) {
3064       GlobalValueSummary *S = FI->summary();
3065       assert(S);
3066 
3067       if (auto *VS = dyn_cast<GlobalVarSummary>(S)) {
3068         NameVals.push_back(I.getModuleId(VS->modulePath()));
3069         NameVals.push_back(getEncodedLinkage(VS->linkage()));
3070         for (auto &RI : VS->refs()) {
3071           const auto &VMI = GUIDToValueIdMap.find(RI);
3072           unsigned RefId;
3073           // If this GUID doesn't have an entry, assign one.
3074           if (VMI == GUIDToValueIdMap.end()) {
3075             GUIDToValueIdMap[RI] = ++GlobalValueId;
3076             RefId = GlobalValueId;
3077           } else {
3078             RefId = VMI->second;
3079           }
3080           NameVals.push_back(RefId);
3081         }
3082 
3083         // Record the starting offset of this summary entry for use
3084         // in the VST entry. Add the current code size since the
3085         // reader will invoke readRecord after the abbrev id read.
3086         FI->setBitcodeIndex(Stream.GetCurrentBitNo() +
3087                             Stream.GetAbbrevIDWidth());
3088 
3089         // Emit the finished record.
3090         Stream.EmitRecord(bitc::FS_COMBINED_GLOBALVAR_INIT_REFS, NameVals,
3091                           FSModRefsAbbrev);
3092         NameVals.clear();
3093         continue;
3094       }
3095 
3096       auto *FS = cast<FunctionSummary>(S);
3097       NameVals.push_back(I.getModuleId(FS->modulePath()));
3098       NameVals.push_back(getEncodedLinkage(FS->linkage()));
3099       NameVals.push_back(FS->instCount());
3100       NameVals.push_back(FS->refs().size());
3101 
3102       for (auto &RI : FS->refs()) {
3103         const auto &VMI = GUIDToValueIdMap.find(RI);
3104         unsigned RefId;
3105         // If this GUID doesn't have an entry, assign one.
3106         if (VMI == GUIDToValueIdMap.end()) {
3107           GUIDToValueIdMap[RI] = ++GlobalValueId;
3108           RefId = GlobalValueId;
3109         } else {
3110           RefId = VMI->second;
3111         }
3112         NameVals.push_back(RefId);
3113       }
3114 
3115       bool HasProfileData = false;
3116       for (auto &EI : FS->calls()) {
3117         HasProfileData |= EI.second.ProfileCount != 0;
3118         if (HasProfileData)
3119           break;
3120       }
3121 
3122       for (auto &EI : FS->calls()) {
3123         const auto &VMI = GUIDToValueIdMap.find(EI.first);
3124         // If this GUID doesn't have an entry, it doesn't have a function
3125         // summary and we don't need to record any calls to it.
3126         if (VMI == GUIDToValueIdMap.end())
3127           continue;
3128         NameVals.push_back(VMI->second);
3129         assert(EI.second.CallsiteCount > 0 && "Expected at least one callsite");
3130         NameVals.push_back(EI.second.CallsiteCount);
3131         if (HasProfileData)
3132           NameVals.push_back(EI.second.ProfileCount);
3133       }
3134 
3135       // Record the starting offset of this summary entry for use
3136       // in the VST entry. Add the current code size since the
3137       // reader will invoke readRecord after the abbrev id read.
3138       FI->setBitcodeIndex(Stream.GetCurrentBitNo() + Stream.GetAbbrevIDWidth());
3139 
3140       unsigned FSAbbrev =
3141           (HasProfileData ? FSCallsProfileAbbrev : FSCallsAbbrev);
3142       unsigned Code =
3143           (HasProfileData ? bitc::FS_COMBINED_PROFILE : bitc::FS_COMBINED);
3144 
3145       // Emit the finished record.
3146       Stream.EmitRecord(Code, NameVals, FSAbbrev);
3147       NameVals.clear();
3148     }
3149   }
3150 
3151   Stream.ExitBlock();
3152 }
3153 
3154 // Create the "IDENTIFICATION_BLOCK_ID" containing a single string with the
3155 // current llvm version, and a record for the epoch number.
3156 static void WriteIdentificationBlock(const Module *M, BitstreamWriter &Stream) {
3157   Stream.EnterSubblock(bitc::IDENTIFICATION_BLOCK_ID, 5);
3158 
3159   // Write the "user readable" string identifying the bitcode producer
3160   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
3161   Abbv->Add(BitCodeAbbrevOp(bitc::IDENTIFICATION_CODE_STRING));
3162   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3163   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
3164   auto StringAbbrev = Stream.EmitAbbrev(Abbv);
3165   WriteStringRecord(bitc::IDENTIFICATION_CODE_STRING,
3166                     "LLVM" LLVM_VERSION_STRING, StringAbbrev, Stream);
3167 
3168   // Write the epoch version
3169   Abbv = new BitCodeAbbrev();
3170   Abbv->Add(BitCodeAbbrevOp(bitc::IDENTIFICATION_CODE_EPOCH));
3171   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
3172   auto EpochAbbrev = Stream.EmitAbbrev(Abbv);
3173   SmallVector<unsigned, 1> Vals = {bitc::BITCODE_CURRENT_EPOCH};
3174   Stream.EmitRecord(bitc::IDENTIFICATION_CODE_EPOCH, Vals, EpochAbbrev);
3175   Stream.ExitBlock();
3176 }
3177 
3178 /// WriteModule - Emit the specified module to the bitstream.
3179 static void WriteModule(const Module *M, BitstreamWriter &Stream,
3180                         bool ShouldPreserveUseListOrder,
3181                         uint64_t BitcodeStartBit, bool EmitSummaryIndex) {
3182   Stream.EnterSubblock(bitc::MODULE_BLOCK_ID, 3);
3183 
3184   SmallVector<unsigned, 1> Vals;
3185   unsigned CurVersion = 1;
3186   Vals.push_back(CurVersion);
3187   Stream.EmitRecord(bitc::MODULE_CODE_VERSION, Vals);
3188 
3189   // Analyze the module, enumerating globals, functions, etc.
3190   ValueEnumerator VE(*M, ShouldPreserveUseListOrder);
3191 
3192   // Emit blockinfo, which defines the standard abbreviations etc.
3193   WriteBlockInfo(VE, Stream);
3194 
3195   // Emit information about attribute groups.
3196   WriteAttributeGroupTable(VE, Stream);
3197 
3198   // Emit information about parameter attributes.
3199   WriteAttributeTable(VE, Stream);
3200 
3201   // Emit information describing all of the types in the module.
3202   WriteTypeTable(VE, Stream);
3203 
3204   writeComdats(VE, Stream);
3205 
3206   // Emit top-level description of module, including target triple, inline asm,
3207   // descriptors for global variables, and function prototype info.
3208   uint64_t VSTOffsetPlaceholder = WriteModuleInfo(M, VE, Stream);
3209 
3210   // Emit constants.
3211   WriteModuleConstants(VE, Stream);
3212 
3213   // Emit metadata.
3214   writeModuleMetadata(*M, VE, Stream);
3215 
3216   // Emit metadata.
3217   WriteModuleMetadataStore(M, Stream);
3218 
3219   // Emit module-level use-lists.
3220   if (VE.shouldPreserveUseListOrder())
3221     WriteUseListBlock(nullptr, VE, Stream);
3222 
3223   WriteOperandBundleTags(M, Stream);
3224 
3225   // Emit function bodies.
3226   DenseMap<const Function *, std::unique_ptr<GlobalValueInfo>> FunctionIndex;
3227   for (Module::const_iterator F = M->begin(), E = M->end(); F != E; ++F)
3228     if (!F->isDeclaration())
3229       WriteFunction(*F, M, VE, Stream, FunctionIndex, EmitSummaryIndex);
3230 
3231   // Need to write after the above call to WriteFunction which populates
3232   // the summary information in the index.
3233   if (EmitSummaryIndex)
3234     WritePerModuleGlobalValueSummary(FunctionIndex, M, VE, Stream);
3235 
3236   WriteValueSymbolTable(M->getValueSymbolTable(), VE, Stream,
3237                         VSTOffsetPlaceholder, BitcodeStartBit, &FunctionIndex);
3238 
3239   Stream.ExitBlock();
3240 }
3241 
3242 /// EmitDarwinBCHeader - If generating a bc file on darwin, we have to emit a
3243 /// header and trailer to make it compatible with the system archiver.  To do
3244 /// this we emit the following header, and then emit a trailer that pads the
3245 /// file out to be a multiple of 16 bytes.
3246 ///
3247 /// struct bc_header {
3248 ///   uint32_t Magic;         // 0x0B17C0DE
3249 ///   uint32_t Version;       // Version, currently always 0.
3250 ///   uint32_t BitcodeOffset; // Offset to traditional bitcode file.
3251 ///   uint32_t BitcodeSize;   // Size of traditional bitcode file.
3252 ///   uint32_t CPUType;       // CPU specifier.
3253 ///   ... potentially more later ...
3254 /// };
3255 
3256 static void WriteInt32ToBuffer(uint32_t Value, SmallVectorImpl<char> &Buffer,
3257                                uint32_t &Position) {
3258   support::endian::write32le(&Buffer[Position], Value);
3259   Position += 4;
3260 }
3261 
3262 static void EmitDarwinBCHeaderAndTrailer(SmallVectorImpl<char> &Buffer,
3263                                          const Triple &TT) {
3264   unsigned CPUType = ~0U;
3265 
3266   // Match x86_64-*, i[3-9]86-*, powerpc-*, powerpc64-*, arm-*, thumb-*,
3267   // armv[0-9]-*, thumbv[0-9]-*, armv5te-*, or armv6t2-*. The CPUType is a magic
3268   // number from /usr/include/mach/machine.h.  It is ok to reproduce the
3269   // specific constants here because they are implicitly part of the Darwin ABI.
3270   enum {
3271     DARWIN_CPU_ARCH_ABI64      = 0x01000000,
3272     DARWIN_CPU_TYPE_X86        = 7,
3273     DARWIN_CPU_TYPE_ARM        = 12,
3274     DARWIN_CPU_TYPE_POWERPC    = 18
3275   };
3276 
3277   Triple::ArchType Arch = TT.getArch();
3278   if (Arch == Triple::x86_64)
3279     CPUType = DARWIN_CPU_TYPE_X86 | DARWIN_CPU_ARCH_ABI64;
3280   else if (Arch == Triple::x86)
3281     CPUType = DARWIN_CPU_TYPE_X86;
3282   else if (Arch == Triple::ppc)
3283     CPUType = DARWIN_CPU_TYPE_POWERPC;
3284   else if (Arch == Triple::ppc64)
3285     CPUType = DARWIN_CPU_TYPE_POWERPC | DARWIN_CPU_ARCH_ABI64;
3286   else if (Arch == Triple::arm || Arch == Triple::thumb)
3287     CPUType = DARWIN_CPU_TYPE_ARM;
3288 
3289   // Traditional Bitcode starts after header.
3290   assert(Buffer.size() >= BWH_HeaderSize &&
3291          "Expected header size to be reserved");
3292   unsigned BCOffset = BWH_HeaderSize;
3293   unsigned BCSize = Buffer.size() - BWH_HeaderSize;
3294 
3295   // Write the magic and version.
3296   unsigned Position = 0;
3297   WriteInt32ToBuffer(0x0B17C0DE , Buffer, Position);
3298   WriteInt32ToBuffer(0          , Buffer, Position); // Version.
3299   WriteInt32ToBuffer(BCOffset   , Buffer, Position);
3300   WriteInt32ToBuffer(BCSize     , Buffer, Position);
3301   WriteInt32ToBuffer(CPUType    , Buffer, Position);
3302 
3303   // If the file is not a multiple of 16 bytes, insert dummy padding.
3304   while (Buffer.size() & 15)
3305     Buffer.push_back(0);
3306 }
3307 
3308 /// Helper to write the header common to all bitcode files.
3309 static void WriteBitcodeHeader(BitstreamWriter &Stream) {
3310   // Emit the file header.
3311   Stream.Emit((unsigned)'B', 8);
3312   Stream.Emit((unsigned)'C', 8);
3313   Stream.Emit(0x0, 4);
3314   Stream.Emit(0xC, 4);
3315   Stream.Emit(0xE, 4);
3316   Stream.Emit(0xD, 4);
3317 }
3318 
3319 /// WriteBitcodeToFile - Write the specified module to the specified output
3320 /// stream.
3321 void llvm::WriteBitcodeToFile(const Module *M, raw_ostream &Out,
3322                               bool ShouldPreserveUseListOrder,
3323                               bool EmitSummaryIndex) {
3324   SmallVector<char, 0> Buffer;
3325   Buffer.reserve(256*1024);
3326 
3327   // If this is darwin or another generic macho target, reserve space for the
3328   // header.
3329   Triple TT(M->getTargetTriple());
3330   if (TT.isOSDarwin() || TT.isOSBinFormatMachO())
3331     Buffer.insert(Buffer.begin(), BWH_HeaderSize, 0);
3332 
3333   // Emit the module into the buffer.
3334   {
3335     BitstreamWriter Stream(Buffer);
3336     // Save the start bit of the actual bitcode, in case there is space
3337     // saved at the start for the darwin header above. The reader stream
3338     // will start at the bitcode, and we need the offset of the VST
3339     // to line up.
3340     uint64_t BitcodeStartBit = Stream.GetCurrentBitNo();
3341 
3342     // Emit the file header.
3343     WriteBitcodeHeader(Stream);
3344 
3345     WriteIdentificationBlock(M, Stream);
3346 
3347     // Emit the module.
3348     WriteModule(M, Stream, ShouldPreserveUseListOrder, BitcodeStartBit,
3349                 EmitSummaryIndex);
3350   }
3351 
3352   if (TT.isOSDarwin() || TT.isOSBinFormatMachO())
3353     EmitDarwinBCHeaderAndTrailer(Buffer, TT);
3354 
3355   // Write the generated bitstream to "Out".
3356   Out.write((char*)&Buffer.front(), Buffer.size());
3357 }
3358 
3359 // Write the specified module summary index to the given raw output stream,
3360 // where it will be written in a new bitcode block. This is used when
3361 // writing the combined index file for ThinLTO.
3362 void llvm::WriteIndexToFile(const ModuleSummaryIndex &Index, raw_ostream &Out) {
3363   SmallVector<char, 0> Buffer;
3364   Buffer.reserve(256 * 1024);
3365 
3366   BitstreamWriter Stream(Buffer);
3367 
3368   // Emit the bitcode header.
3369   WriteBitcodeHeader(Stream);
3370 
3371   Stream.EnterSubblock(bitc::MODULE_BLOCK_ID, 3);
3372 
3373   SmallVector<unsigned, 1> Vals;
3374   unsigned CurVersion = 1;
3375   Vals.push_back(CurVersion);
3376   Stream.EmitRecord(bitc::MODULE_CODE_VERSION, Vals);
3377 
3378   // If we have a VST, write the VSTOFFSET record placeholder and record
3379   // its offset.
3380   uint64_t VSTOffsetPlaceholder = WriteValueSymbolTableForwardDecl(Stream);
3381 
3382   // Write the module paths in the combined index.
3383   WriteModStrings(Index, Stream);
3384 
3385   // Assign unique value ids to all functions in the index for use
3386   // in writing out the call graph edges. Save the mapping from GUID
3387   // to the new global value id to use when writing those edges, which
3388   // are currently saved in the index in terms of GUID.
3389   std::map<uint64_t, unsigned> GUIDToValueIdMap;
3390   unsigned GlobalValueId = 0;
3391   for (auto &II : Index)
3392     GUIDToValueIdMap[II.first] = ++GlobalValueId;
3393 
3394   // Write the summary combined index records.
3395   WriteCombinedGlobalValueSummary(Index, Stream, GUIDToValueIdMap,
3396                                   GlobalValueId);
3397 
3398   // Need a special VST writer for the combined index (we don't have a
3399   // real VST and real values when this is invoked).
3400   WriteCombinedValueSymbolTable(Index, Stream, GUIDToValueIdMap,
3401                                 VSTOffsetPlaceholder);
3402 
3403   Stream.ExitBlock();
3404 
3405   Out.write((char *)&Buffer.front(), Buffer.size());
3406 }
3407