xref: /llvm-project/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp (revision fc8110041f55483631b9e6f11ea105d41708a512)
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 void WriteModuleMetadata(const Module &M,
1351                                 const ValueEnumerator &VE,
1352                                 BitstreamWriter &Stream) {
1353   const auto &MDs = VE.getMDs();
1354   if (MDs.empty() && M.named_metadata_empty())
1355     return;
1356 
1357   Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
1358 
1359   unsigned MDSAbbrev = 0;
1360   if (VE.hasMDString()) {
1361     // Abbrev for METADATA_STRING.
1362     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1363     Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_STRING));
1364     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1365     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
1366     MDSAbbrev = Stream.EmitAbbrev(Abbv);
1367   }
1368 
1369   // Initialize MDNode abbreviations.
1370 #define HANDLE_MDNODE_LEAF(CLASS) unsigned CLASS##Abbrev = 0;
1371 #include "llvm/IR/Metadata.def"
1372 
1373   SmallVector<uint64_t, 64> Record;
1374   for (const Metadata *MD : MDs) {
1375     if (const MDNode *N = dyn_cast<MDNode>(MD)) {
1376       assert(N->isResolved() && "Expected forward references to be resolved");
1377 
1378       switch (N->getMetadataID()) {
1379       default:
1380         llvm_unreachable("Invalid MDNode subclass");
1381 #define HANDLE_MDNODE_LEAF(CLASS)                                              \
1382   case Metadata::CLASS##Kind:                                                  \
1383     Write##CLASS(cast<CLASS>(N), VE, Stream, Record, CLASS##Abbrev);           \
1384     continue;
1385 #include "llvm/IR/Metadata.def"
1386       }
1387     }
1388     if (const auto *MDC = dyn_cast<ConstantAsMetadata>(MD)) {
1389       WriteValueAsMetadata(MDC, VE, Stream, Record);
1390       continue;
1391     }
1392     const MDString *MDS = cast<MDString>(MD);
1393     // Code: [strchar x N]
1394     Record.append(MDS->bytes_begin(), MDS->bytes_end());
1395 
1396     // Emit the finished record.
1397     Stream.EmitRecord(bitc::METADATA_STRING, Record, MDSAbbrev);
1398     Record.clear();
1399   }
1400 
1401   writeNamedMetadata(M, VE, Stream, Record);
1402   Stream.ExitBlock();
1403 }
1404 
1405 static void WriteFunctionLocalMetadata(const Function &F,
1406                                        const ValueEnumerator &VE,
1407                                        BitstreamWriter &Stream) {
1408   bool StartedMetadataBlock = false;
1409   SmallVector<uint64_t, 64> Record;
1410   const SmallVectorImpl<const LocalAsMetadata *> &MDs =
1411       VE.getFunctionLocalMDs();
1412   for (unsigned i = 0, e = MDs.size(); i != e; ++i) {
1413     assert(MDs[i] && "Expected valid function-local metadata");
1414     if (!StartedMetadataBlock) {
1415       Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
1416       StartedMetadataBlock = true;
1417     }
1418     WriteValueAsMetadata(MDs[i], VE, Stream, Record);
1419   }
1420 
1421   if (StartedMetadataBlock)
1422     Stream.ExitBlock();
1423 }
1424 
1425 static void WriteMetadataAttachment(const Function &F,
1426                                     const ValueEnumerator &VE,
1427                                     BitstreamWriter &Stream) {
1428   Stream.EnterSubblock(bitc::METADATA_ATTACHMENT_ID, 3);
1429 
1430   SmallVector<uint64_t, 64> Record;
1431 
1432   // Write metadata attachments
1433   // METADATA_ATTACHMENT - [m x [value, [n x [id, mdnode]]]
1434   SmallVector<std::pair<unsigned, MDNode *>, 4> MDs;
1435   F.getAllMetadata(MDs);
1436   if (!MDs.empty()) {
1437     for (const auto &I : MDs) {
1438       Record.push_back(I.first);
1439       Record.push_back(VE.getMetadataID(I.second));
1440     }
1441     Stream.EmitRecord(bitc::METADATA_ATTACHMENT, Record, 0);
1442     Record.clear();
1443   }
1444 
1445   for (const BasicBlock &BB : F)
1446     for (const Instruction &I : BB) {
1447       MDs.clear();
1448       I.getAllMetadataOtherThanDebugLoc(MDs);
1449 
1450       // If no metadata, ignore instruction.
1451       if (MDs.empty()) continue;
1452 
1453       Record.push_back(VE.getInstructionID(&I));
1454 
1455       for (unsigned i = 0, e = MDs.size(); i != e; ++i) {
1456         Record.push_back(MDs[i].first);
1457         Record.push_back(VE.getMetadataID(MDs[i].second));
1458       }
1459       Stream.EmitRecord(bitc::METADATA_ATTACHMENT, Record, 0);
1460       Record.clear();
1461     }
1462 
1463   Stream.ExitBlock();
1464 }
1465 
1466 static void WriteModuleMetadataStore(const Module *M, BitstreamWriter &Stream) {
1467   SmallVector<uint64_t, 64> Record;
1468 
1469   // Write metadata kinds
1470   // METADATA_KIND - [n x [id, name]]
1471   SmallVector<StringRef, 8> Names;
1472   M->getMDKindNames(Names);
1473 
1474   if (Names.empty()) return;
1475 
1476   Stream.EnterSubblock(bitc::METADATA_KIND_BLOCK_ID, 3);
1477 
1478   for (unsigned MDKindID = 0, e = Names.size(); MDKindID != e; ++MDKindID) {
1479     Record.push_back(MDKindID);
1480     StringRef KName = Names[MDKindID];
1481     Record.append(KName.begin(), KName.end());
1482 
1483     Stream.EmitRecord(bitc::METADATA_KIND, Record, 0);
1484     Record.clear();
1485   }
1486 
1487   Stream.ExitBlock();
1488 }
1489 
1490 static void WriteOperandBundleTags(const Module *M, BitstreamWriter &Stream) {
1491   // Write metadata kinds
1492   //
1493   // OPERAND_BUNDLE_TAGS_BLOCK_ID : N x OPERAND_BUNDLE_TAG
1494   //
1495   // OPERAND_BUNDLE_TAG - [strchr x N]
1496 
1497   SmallVector<StringRef, 8> Tags;
1498   M->getOperandBundleTags(Tags);
1499 
1500   if (Tags.empty())
1501     return;
1502 
1503   Stream.EnterSubblock(bitc::OPERAND_BUNDLE_TAGS_BLOCK_ID, 3);
1504 
1505   SmallVector<uint64_t, 64> Record;
1506 
1507   for (auto Tag : Tags) {
1508     Record.append(Tag.begin(), Tag.end());
1509 
1510     Stream.EmitRecord(bitc::OPERAND_BUNDLE_TAG, Record, 0);
1511     Record.clear();
1512   }
1513 
1514   Stream.ExitBlock();
1515 }
1516 
1517 static void emitSignedInt64(SmallVectorImpl<uint64_t> &Vals, uint64_t V) {
1518   if ((int64_t)V >= 0)
1519     Vals.push_back(V << 1);
1520   else
1521     Vals.push_back((-V << 1) | 1);
1522 }
1523 
1524 static void WriteConstants(unsigned FirstVal, unsigned LastVal,
1525                            const ValueEnumerator &VE,
1526                            BitstreamWriter &Stream, bool isGlobal) {
1527   if (FirstVal == LastVal) return;
1528 
1529   Stream.EnterSubblock(bitc::CONSTANTS_BLOCK_ID, 4);
1530 
1531   unsigned AggregateAbbrev = 0;
1532   unsigned String8Abbrev = 0;
1533   unsigned CString7Abbrev = 0;
1534   unsigned CString6Abbrev = 0;
1535   // If this is a constant pool for the module, emit module-specific abbrevs.
1536   if (isGlobal) {
1537     // Abbrev for CST_CODE_AGGREGATE.
1538     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1539     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_AGGREGATE));
1540     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1541     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, Log2_32_Ceil(LastVal+1)));
1542     AggregateAbbrev = Stream.EmitAbbrev(Abbv);
1543 
1544     // Abbrev for CST_CODE_STRING.
1545     Abbv = new BitCodeAbbrev();
1546     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_STRING));
1547     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1548     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
1549     String8Abbrev = Stream.EmitAbbrev(Abbv);
1550     // Abbrev for CST_CODE_CSTRING.
1551     Abbv = new BitCodeAbbrev();
1552     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
1553     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1554     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
1555     CString7Abbrev = Stream.EmitAbbrev(Abbv);
1556     // Abbrev for CST_CODE_CSTRING.
1557     Abbv = new BitCodeAbbrev();
1558     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
1559     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1560     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
1561     CString6Abbrev = Stream.EmitAbbrev(Abbv);
1562   }
1563 
1564   SmallVector<uint64_t, 64> Record;
1565 
1566   const ValueEnumerator::ValueList &Vals = VE.getValues();
1567   Type *LastTy = nullptr;
1568   for (unsigned i = FirstVal; i != LastVal; ++i) {
1569     const Value *V = Vals[i].first;
1570     // If we need to switch types, do so now.
1571     if (V->getType() != LastTy) {
1572       LastTy = V->getType();
1573       Record.push_back(VE.getTypeID(LastTy));
1574       Stream.EmitRecord(bitc::CST_CODE_SETTYPE, Record,
1575                         CONSTANTS_SETTYPE_ABBREV);
1576       Record.clear();
1577     }
1578 
1579     if (const InlineAsm *IA = dyn_cast<InlineAsm>(V)) {
1580       Record.push_back(unsigned(IA->hasSideEffects()) |
1581                        unsigned(IA->isAlignStack()) << 1 |
1582                        unsigned(IA->getDialect()&1) << 2);
1583 
1584       // Add the asm string.
1585       const std::string &AsmStr = IA->getAsmString();
1586       Record.push_back(AsmStr.size());
1587       Record.append(AsmStr.begin(), AsmStr.end());
1588 
1589       // Add the constraint string.
1590       const std::string &ConstraintStr = IA->getConstraintString();
1591       Record.push_back(ConstraintStr.size());
1592       Record.append(ConstraintStr.begin(), ConstraintStr.end());
1593       Stream.EmitRecord(bitc::CST_CODE_INLINEASM, Record);
1594       Record.clear();
1595       continue;
1596     }
1597     const Constant *C = cast<Constant>(V);
1598     unsigned Code = -1U;
1599     unsigned AbbrevToUse = 0;
1600     if (C->isNullValue()) {
1601       Code = bitc::CST_CODE_NULL;
1602     } else if (isa<UndefValue>(C)) {
1603       Code = bitc::CST_CODE_UNDEF;
1604     } else if (const ConstantInt *IV = dyn_cast<ConstantInt>(C)) {
1605       if (IV->getBitWidth() <= 64) {
1606         uint64_t V = IV->getSExtValue();
1607         emitSignedInt64(Record, V);
1608         Code = bitc::CST_CODE_INTEGER;
1609         AbbrevToUse = CONSTANTS_INTEGER_ABBREV;
1610       } else {                             // Wide integers, > 64 bits in size.
1611         // We have an arbitrary precision integer value to write whose
1612         // bit width is > 64. However, in canonical unsigned integer
1613         // format it is likely that the high bits are going to be zero.
1614         // So, we only write the number of active words.
1615         unsigned NWords = IV->getValue().getActiveWords();
1616         const uint64_t *RawWords = IV->getValue().getRawData();
1617         for (unsigned i = 0; i != NWords; ++i) {
1618           emitSignedInt64(Record, RawWords[i]);
1619         }
1620         Code = bitc::CST_CODE_WIDE_INTEGER;
1621       }
1622     } else if (const ConstantFP *CFP = dyn_cast<ConstantFP>(C)) {
1623       Code = bitc::CST_CODE_FLOAT;
1624       Type *Ty = CFP->getType();
1625       if (Ty->isHalfTy() || Ty->isFloatTy() || Ty->isDoubleTy()) {
1626         Record.push_back(CFP->getValueAPF().bitcastToAPInt().getZExtValue());
1627       } else if (Ty->isX86_FP80Ty()) {
1628         // api needed to prevent premature destruction
1629         // bits are not in the same order as a normal i80 APInt, compensate.
1630         APInt api = CFP->getValueAPF().bitcastToAPInt();
1631         const uint64_t *p = api.getRawData();
1632         Record.push_back((p[1] << 48) | (p[0] >> 16));
1633         Record.push_back(p[0] & 0xffffLL);
1634       } else if (Ty->isFP128Ty() || Ty->isPPC_FP128Ty()) {
1635         APInt api = CFP->getValueAPF().bitcastToAPInt();
1636         const uint64_t *p = api.getRawData();
1637         Record.push_back(p[0]);
1638         Record.push_back(p[1]);
1639       } else {
1640         assert (0 && "Unknown FP type!");
1641       }
1642     } else if (isa<ConstantDataSequential>(C) &&
1643                cast<ConstantDataSequential>(C)->isString()) {
1644       const ConstantDataSequential *Str = cast<ConstantDataSequential>(C);
1645       // Emit constant strings specially.
1646       unsigned NumElts = Str->getNumElements();
1647       // If this is a null-terminated string, use the denser CSTRING encoding.
1648       if (Str->isCString()) {
1649         Code = bitc::CST_CODE_CSTRING;
1650         --NumElts;  // Don't encode the null, which isn't allowed by char6.
1651       } else {
1652         Code = bitc::CST_CODE_STRING;
1653         AbbrevToUse = String8Abbrev;
1654       }
1655       bool isCStr7 = Code == bitc::CST_CODE_CSTRING;
1656       bool isCStrChar6 = Code == bitc::CST_CODE_CSTRING;
1657       for (unsigned i = 0; i != NumElts; ++i) {
1658         unsigned char V = Str->getElementAsInteger(i);
1659         Record.push_back(V);
1660         isCStr7 &= (V & 128) == 0;
1661         if (isCStrChar6)
1662           isCStrChar6 = BitCodeAbbrevOp::isChar6(V);
1663       }
1664 
1665       if (isCStrChar6)
1666         AbbrevToUse = CString6Abbrev;
1667       else if (isCStr7)
1668         AbbrevToUse = CString7Abbrev;
1669     } else if (const ConstantDataSequential *CDS =
1670                   dyn_cast<ConstantDataSequential>(C)) {
1671       Code = bitc::CST_CODE_DATA;
1672       Type *EltTy = CDS->getType()->getElementType();
1673       if (isa<IntegerType>(EltTy)) {
1674         for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i)
1675           Record.push_back(CDS->getElementAsInteger(i));
1676       } else {
1677         for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i)
1678           Record.push_back(
1679               CDS->getElementAsAPFloat(i).bitcastToAPInt().getLimitedValue());
1680       }
1681     } else if (isa<ConstantArray>(C) || isa<ConstantStruct>(C) ||
1682                isa<ConstantVector>(C)) {
1683       Code = bitc::CST_CODE_AGGREGATE;
1684       for (const Value *Op : C->operands())
1685         Record.push_back(VE.getValueID(Op));
1686       AbbrevToUse = AggregateAbbrev;
1687     } else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
1688       switch (CE->getOpcode()) {
1689       default:
1690         if (Instruction::isCast(CE->getOpcode())) {
1691           Code = bitc::CST_CODE_CE_CAST;
1692           Record.push_back(GetEncodedCastOpcode(CE->getOpcode()));
1693           Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
1694           Record.push_back(VE.getValueID(C->getOperand(0)));
1695           AbbrevToUse = CONSTANTS_CE_CAST_Abbrev;
1696         } else {
1697           assert(CE->getNumOperands() == 2 && "Unknown constant expr!");
1698           Code = bitc::CST_CODE_CE_BINOP;
1699           Record.push_back(GetEncodedBinaryOpcode(CE->getOpcode()));
1700           Record.push_back(VE.getValueID(C->getOperand(0)));
1701           Record.push_back(VE.getValueID(C->getOperand(1)));
1702           uint64_t Flags = GetOptimizationFlags(CE);
1703           if (Flags != 0)
1704             Record.push_back(Flags);
1705         }
1706         break;
1707       case Instruction::GetElementPtr: {
1708         Code = bitc::CST_CODE_CE_GEP;
1709         const auto *GO = cast<GEPOperator>(C);
1710         if (GO->isInBounds())
1711           Code = bitc::CST_CODE_CE_INBOUNDS_GEP;
1712         Record.push_back(VE.getTypeID(GO->getSourceElementType()));
1713         for (unsigned i = 0, e = CE->getNumOperands(); i != e; ++i) {
1714           Record.push_back(VE.getTypeID(C->getOperand(i)->getType()));
1715           Record.push_back(VE.getValueID(C->getOperand(i)));
1716         }
1717         break;
1718       }
1719       case Instruction::Select:
1720         Code = bitc::CST_CODE_CE_SELECT;
1721         Record.push_back(VE.getValueID(C->getOperand(0)));
1722         Record.push_back(VE.getValueID(C->getOperand(1)));
1723         Record.push_back(VE.getValueID(C->getOperand(2)));
1724         break;
1725       case Instruction::ExtractElement:
1726         Code = bitc::CST_CODE_CE_EXTRACTELT;
1727         Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
1728         Record.push_back(VE.getValueID(C->getOperand(0)));
1729         Record.push_back(VE.getTypeID(C->getOperand(1)->getType()));
1730         Record.push_back(VE.getValueID(C->getOperand(1)));
1731         break;
1732       case Instruction::InsertElement:
1733         Code = bitc::CST_CODE_CE_INSERTELT;
1734         Record.push_back(VE.getValueID(C->getOperand(0)));
1735         Record.push_back(VE.getValueID(C->getOperand(1)));
1736         Record.push_back(VE.getTypeID(C->getOperand(2)->getType()));
1737         Record.push_back(VE.getValueID(C->getOperand(2)));
1738         break;
1739       case Instruction::ShuffleVector:
1740         // If the return type and argument types are the same, this is a
1741         // standard shufflevector instruction.  If the types are different,
1742         // then the shuffle is widening or truncating the input vectors, and
1743         // the argument type must also be encoded.
1744         if (C->getType() == C->getOperand(0)->getType()) {
1745           Code = bitc::CST_CODE_CE_SHUFFLEVEC;
1746         } else {
1747           Code = bitc::CST_CODE_CE_SHUFVEC_EX;
1748           Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
1749         }
1750         Record.push_back(VE.getValueID(C->getOperand(0)));
1751         Record.push_back(VE.getValueID(C->getOperand(1)));
1752         Record.push_back(VE.getValueID(C->getOperand(2)));
1753         break;
1754       case Instruction::ICmp:
1755       case Instruction::FCmp:
1756         Code = bitc::CST_CODE_CE_CMP;
1757         Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
1758         Record.push_back(VE.getValueID(C->getOperand(0)));
1759         Record.push_back(VE.getValueID(C->getOperand(1)));
1760         Record.push_back(CE->getPredicate());
1761         break;
1762       }
1763     } else if (const BlockAddress *BA = dyn_cast<BlockAddress>(C)) {
1764       Code = bitc::CST_CODE_BLOCKADDRESS;
1765       Record.push_back(VE.getTypeID(BA->getFunction()->getType()));
1766       Record.push_back(VE.getValueID(BA->getFunction()));
1767       Record.push_back(VE.getGlobalBasicBlockID(BA->getBasicBlock()));
1768     } else {
1769 #ifndef NDEBUG
1770       C->dump();
1771 #endif
1772       llvm_unreachable("Unknown constant!");
1773     }
1774     Stream.EmitRecord(Code, Record, AbbrevToUse);
1775     Record.clear();
1776   }
1777 
1778   Stream.ExitBlock();
1779 }
1780 
1781 static void WriteModuleConstants(const ValueEnumerator &VE,
1782                                  BitstreamWriter &Stream) {
1783   const ValueEnumerator::ValueList &Vals = VE.getValues();
1784 
1785   // Find the first constant to emit, which is the first non-globalvalue value.
1786   // We know globalvalues have been emitted by WriteModuleInfo.
1787   for (unsigned i = 0, e = Vals.size(); i != e; ++i) {
1788     if (!isa<GlobalValue>(Vals[i].first)) {
1789       WriteConstants(i, Vals.size(), VE, Stream, true);
1790       return;
1791     }
1792   }
1793 }
1794 
1795 /// PushValueAndType - The file has to encode both the value and type id for
1796 /// many values, because we need to know what type to create for forward
1797 /// references.  However, most operands are not forward references, so this type
1798 /// field is not needed.
1799 ///
1800 /// This function adds V's value ID to Vals.  If the value ID is higher than the
1801 /// instruction ID, then it is a forward reference, and it also includes the
1802 /// type ID.  The value ID that is written is encoded relative to the InstID.
1803 static bool PushValueAndType(const Value *V, unsigned InstID,
1804                              SmallVectorImpl<unsigned> &Vals,
1805                              ValueEnumerator &VE) {
1806   unsigned ValID = VE.getValueID(V);
1807   // Make encoding relative to the InstID.
1808   Vals.push_back(InstID - ValID);
1809   if (ValID >= InstID) {
1810     Vals.push_back(VE.getTypeID(V->getType()));
1811     return true;
1812   }
1813   return false;
1814 }
1815 
1816 static void WriteOperandBundles(BitstreamWriter &Stream, ImmutableCallSite CS,
1817                                 unsigned InstID, ValueEnumerator &VE) {
1818   SmallVector<unsigned, 64> Record;
1819   LLVMContext &C = CS.getInstruction()->getContext();
1820 
1821   for (unsigned i = 0, e = CS.getNumOperandBundles(); i != e; ++i) {
1822     const auto &Bundle = CS.getOperandBundleAt(i);
1823     Record.push_back(C.getOperandBundleTagID(Bundle.getTagName()));
1824 
1825     for (auto &Input : Bundle.Inputs)
1826       PushValueAndType(Input, InstID, Record, VE);
1827 
1828     Stream.EmitRecord(bitc::FUNC_CODE_OPERAND_BUNDLE, Record);
1829     Record.clear();
1830   }
1831 }
1832 
1833 /// pushValue - Like PushValueAndType, but where the type of the value is
1834 /// omitted (perhaps it was already encoded in an earlier operand).
1835 static void pushValue(const Value *V, unsigned InstID,
1836                       SmallVectorImpl<unsigned> &Vals,
1837                       ValueEnumerator &VE) {
1838   unsigned ValID = VE.getValueID(V);
1839   Vals.push_back(InstID - ValID);
1840 }
1841 
1842 static void pushValueSigned(const Value *V, unsigned InstID,
1843                             SmallVectorImpl<uint64_t> &Vals,
1844                             ValueEnumerator &VE) {
1845   unsigned ValID = VE.getValueID(V);
1846   int64_t diff = ((int32_t)InstID - (int32_t)ValID);
1847   emitSignedInt64(Vals, diff);
1848 }
1849 
1850 /// WriteInstruction - Emit an instruction to the specified stream.
1851 static void WriteInstruction(const Instruction &I, unsigned InstID,
1852                              ValueEnumerator &VE, BitstreamWriter &Stream,
1853                              SmallVectorImpl<unsigned> &Vals) {
1854   unsigned Code = 0;
1855   unsigned AbbrevToUse = 0;
1856   VE.setInstructionID(&I);
1857   switch (I.getOpcode()) {
1858   default:
1859     if (Instruction::isCast(I.getOpcode())) {
1860       Code = bitc::FUNC_CODE_INST_CAST;
1861       if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
1862         AbbrevToUse = FUNCTION_INST_CAST_ABBREV;
1863       Vals.push_back(VE.getTypeID(I.getType()));
1864       Vals.push_back(GetEncodedCastOpcode(I.getOpcode()));
1865     } else {
1866       assert(isa<BinaryOperator>(I) && "Unknown instruction!");
1867       Code = bitc::FUNC_CODE_INST_BINOP;
1868       if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
1869         AbbrevToUse = FUNCTION_INST_BINOP_ABBREV;
1870       pushValue(I.getOperand(1), InstID, Vals, VE);
1871       Vals.push_back(GetEncodedBinaryOpcode(I.getOpcode()));
1872       uint64_t Flags = GetOptimizationFlags(&I);
1873       if (Flags != 0) {
1874         if (AbbrevToUse == FUNCTION_INST_BINOP_ABBREV)
1875           AbbrevToUse = FUNCTION_INST_BINOP_FLAGS_ABBREV;
1876         Vals.push_back(Flags);
1877       }
1878     }
1879     break;
1880 
1881   case Instruction::GetElementPtr: {
1882     Code = bitc::FUNC_CODE_INST_GEP;
1883     AbbrevToUse = FUNCTION_INST_GEP_ABBREV;
1884     auto &GEPInst = cast<GetElementPtrInst>(I);
1885     Vals.push_back(GEPInst.isInBounds());
1886     Vals.push_back(VE.getTypeID(GEPInst.getSourceElementType()));
1887     for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
1888       PushValueAndType(I.getOperand(i), InstID, Vals, VE);
1889     break;
1890   }
1891   case Instruction::ExtractValue: {
1892     Code = bitc::FUNC_CODE_INST_EXTRACTVAL;
1893     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1894     const ExtractValueInst *EVI = cast<ExtractValueInst>(&I);
1895     Vals.append(EVI->idx_begin(), EVI->idx_end());
1896     break;
1897   }
1898   case Instruction::InsertValue: {
1899     Code = bitc::FUNC_CODE_INST_INSERTVAL;
1900     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1901     PushValueAndType(I.getOperand(1), InstID, Vals, VE);
1902     const InsertValueInst *IVI = cast<InsertValueInst>(&I);
1903     Vals.append(IVI->idx_begin(), IVI->idx_end());
1904     break;
1905   }
1906   case Instruction::Select:
1907     Code = bitc::FUNC_CODE_INST_VSELECT;
1908     PushValueAndType(I.getOperand(1), InstID, Vals, VE);
1909     pushValue(I.getOperand(2), InstID, Vals, VE);
1910     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1911     break;
1912   case Instruction::ExtractElement:
1913     Code = bitc::FUNC_CODE_INST_EXTRACTELT;
1914     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1915     PushValueAndType(I.getOperand(1), InstID, Vals, VE);
1916     break;
1917   case Instruction::InsertElement:
1918     Code = bitc::FUNC_CODE_INST_INSERTELT;
1919     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1920     pushValue(I.getOperand(1), InstID, Vals, VE);
1921     PushValueAndType(I.getOperand(2), InstID, Vals, VE);
1922     break;
1923   case Instruction::ShuffleVector:
1924     Code = bitc::FUNC_CODE_INST_SHUFFLEVEC;
1925     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1926     pushValue(I.getOperand(1), InstID, Vals, VE);
1927     pushValue(I.getOperand(2), InstID, Vals, VE);
1928     break;
1929   case Instruction::ICmp:
1930   case Instruction::FCmp: {
1931     // compare returning Int1Ty or vector of Int1Ty
1932     Code = bitc::FUNC_CODE_INST_CMP2;
1933     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1934     pushValue(I.getOperand(1), InstID, Vals, VE);
1935     Vals.push_back(cast<CmpInst>(I).getPredicate());
1936     uint64_t Flags = GetOptimizationFlags(&I);
1937     if (Flags != 0)
1938       Vals.push_back(Flags);
1939     break;
1940   }
1941 
1942   case Instruction::Ret:
1943     {
1944       Code = bitc::FUNC_CODE_INST_RET;
1945       unsigned NumOperands = I.getNumOperands();
1946       if (NumOperands == 0)
1947         AbbrevToUse = FUNCTION_INST_RET_VOID_ABBREV;
1948       else if (NumOperands == 1) {
1949         if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
1950           AbbrevToUse = FUNCTION_INST_RET_VAL_ABBREV;
1951       } else {
1952         for (unsigned i = 0, e = NumOperands; i != e; ++i)
1953           PushValueAndType(I.getOperand(i), InstID, Vals, VE);
1954       }
1955     }
1956     break;
1957   case Instruction::Br:
1958     {
1959       Code = bitc::FUNC_CODE_INST_BR;
1960       const BranchInst &II = cast<BranchInst>(I);
1961       Vals.push_back(VE.getValueID(II.getSuccessor(0)));
1962       if (II.isConditional()) {
1963         Vals.push_back(VE.getValueID(II.getSuccessor(1)));
1964         pushValue(II.getCondition(), InstID, Vals, VE);
1965       }
1966     }
1967     break;
1968   case Instruction::Switch:
1969     {
1970       Code = bitc::FUNC_CODE_INST_SWITCH;
1971       const SwitchInst &SI = cast<SwitchInst>(I);
1972       Vals.push_back(VE.getTypeID(SI.getCondition()->getType()));
1973       pushValue(SI.getCondition(), InstID, Vals, VE);
1974       Vals.push_back(VE.getValueID(SI.getDefaultDest()));
1975       for (SwitchInst::ConstCaseIt Case : SI.cases()) {
1976         Vals.push_back(VE.getValueID(Case.getCaseValue()));
1977         Vals.push_back(VE.getValueID(Case.getCaseSuccessor()));
1978       }
1979     }
1980     break;
1981   case Instruction::IndirectBr:
1982     Code = bitc::FUNC_CODE_INST_INDIRECTBR;
1983     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));
1984     // Encode the address operand as relative, but not the basic blocks.
1985     pushValue(I.getOperand(0), InstID, Vals, VE);
1986     for (unsigned i = 1, e = I.getNumOperands(); i != e; ++i)
1987       Vals.push_back(VE.getValueID(I.getOperand(i)));
1988     break;
1989 
1990   case Instruction::Invoke: {
1991     const InvokeInst *II = cast<InvokeInst>(&I);
1992     const Value *Callee = II->getCalledValue();
1993     FunctionType *FTy = II->getFunctionType();
1994 
1995     if (II->hasOperandBundles())
1996       WriteOperandBundles(Stream, II, InstID, VE);
1997 
1998     Code = bitc::FUNC_CODE_INST_INVOKE;
1999 
2000     Vals.push_back(VE.getAttributeID(II->getAttributes()));
2001     Vals.push_back(II->getCallingConv() | 1 << 13);
2002     Vals.push_back(VE.getValueID(II->getNormalDest()));
2003     Vals.push_back(VE.getValueID(II->getUnwindDest()));
2004     Vals.push_back(VE.getTypeID(FTy));
2005     PushValueAndType(Callee, InstID, Vals, VE);
2006 
2007     // Emit value #'s for the fixed parameters.
2008     for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i)
2009       pushValue(I.getOperand(i), InstID, Vals, VE);  // fixed param.
2010 
2011     // Emit type/value pairs for varargs params.
2012     if (FTy->isVarArg()) {
2013       for (unsigned i = FTy->getNumParams(), e = I.getNumOperands()-3;
2014            i != e; ++i)
2015         PushValueAndType(I.getOperand(i), InstID, Vals, VE); // vararg
2016     }
2017     break;
2018   }
2019   case Instruction::Resume:
2020     Code = bitc::FUNC_CODE_INST_RESUME;
2021     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
2022     break;
2023   case Instruction::CleanupRet: {
2024     Code = bitc::FUNC_CODE_INST_CLEANUPRET;
2025     const auto &CRI = cast<CleanupReturnInst>(I);
2026     pushValue(CRI.getCleanupPad(), InstID, Vals, VE);
2027     if (CRI.hasUnwindDest())
2028       Vals.push_back(VE.getValueID(CRI.getUnwindDest()));
2029     break;
2030   }
2031   case Instruction::CatchRet: {
2032     Code = bitc::FUNC_CODE_INST_CATCHRET;
2033     const auto &CRI = cast<CatchReturnInst>(I);
2034     pushValue(CRI.getCatchPad(), InstID, Vals, VE);
2035     Vals.push_back(VE.getValueID(CRI.getSuccessor()));
2036     break;
2037   }
2038   case Instruction::CleanupPad:
2039   case Instruction::CatchPad: {
2040     const auto &FuncletPad = cast<FuncletPadInst>(I);
2041     Code = isa<CatchPadInst>(FuncletPad) ? bitc::FUNC_CODE_INST_CATCHPAD
2042                                          : bitc::FUNC_CODE_INST_CLEANUPPAD;
2043     pushValue(FuncletPad.getParentPad(), InstID, Vals, VE);
2044 
2045     unsigned NumArgOperands = FuncletPad.getNumArgOperands();
2046     Vals.push_back(NumArgOperands);
2047     for (unsigned Op = 0; Op != NumArgOperands; ++Op)
2048       PushValueAndType(FuncletPad.getArgOperand(Op), InstID, Vals, VE);
2049     break;
2050   }
2051   case Instruction::CatchSwitch: {
2052     Code = bitc::FUNC_CODE_INST_CATCHSWITCH;
2053     const auto &CatchSwitch = cast<CatchSwitchInst>(I);
2054 
2055     pushValue(CatchSwitch.getParentPad(), InstID, Vals, VE);
2056 
2057     unsigned NumHandlers = CatchSwitch.getNumHandlers();
2058     Vals.push_back(NumHandlers);
2059     for (const BasicBlock *CatchPadBB : CatchSwitch.handlers())
2060       Vals.push_back(VE.getValueID(CatchPadBB));
2061 
2062     if (CatchSwitch.hasUnwindDest())
2063       Vals.push_back(VE.getValueID(CatchSwitch.getUnwindDest()));
2064     break;
2065   }
2066   case Instruction::Unreachable:
2067     Code = bitc::FUNC_CODE_INST_UNREACHABLE;
2068     AbbrevToUse = FUNCTION_INST_UNREACHABLE_ABBREV;
2069     break;
2070 
2071   case Instruction::PHI: {
2072     const PHINode &PN = cast<PHINode>(I);
2073     Code = bitc::FUNC_CODE_INST_PHI;
2074     // With the newer instruction encoding, forward references could give
2075     // negative valued IDs.  This is most common for PHIs, so we use
2076     // signed VBRs.
2077     SmallVector<uint64_t, 128> Vals64;
2078     Vals64.push_back(VE.getTypeID(PN.getType()));
2079     for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) {
2080       pushValueSigned(PN.getIncomingValue(i), InstID, Vals64, VE);
2081       Vals64.push_back(VE.getValueID(PN.getIncomingBlock(i)));
2082     }
2083     // Emit a Vals64 vector and exit.
2084     Stream.EmitRecord(Code, Vals64, AbbrevToUse);
2085     Vals64.clear();
2086     return;
2087   }
2088 
2089   case Instruction::LandingPad: {
2090     const LandingPadInst &LP = cast<LandingPadInst>(I);
2091     Code = bitc::FUNC_CODE_INST_LANDINGPAD;
2092     Vals.push_back(VE.getTypeID(LP.getType()));
2093     Vals.push_back(LP.isCleanup());
2094     Vals.push_back(LP.getNumClauses());
2095     for (unsigned I = 0, E = LP.getNumClauses(); I != E; ++I) {
2096       if (LP.isCatch(I))
2097         Vals.push_back(LandingPadInst::Catch);
2098       else
2099         Vals.push_back(LandingPadInst::Filter);
2100       PushValueAndType(LP.getClause(I), InstID, Vals, VE);
2101     }
2102     break;
2103   }
2104 
2105   case Instruction::Alloca: {
2106     Code = bitc::FUNC_CODE_INST_ALLOCA;
2107     const AllocaInst &AI = cast<AllocaInst>(I);
2108     Vals.push_back(VE.getTypeID(AI.getAllocatedType()));
2109     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));
2110     Vals.push_back(VE.getValueID(I.getOperand(0))); // size.
2111     unsigned AlignRecord = Log2_32(AI.getAlignment()) + 1;
2112     assert(Log2_32(Value::MaximumAlignment) + 1 < 1 << 5 &&
2113            "not enough bits for maximum alignment");
2114     assert(AlignRecord < 1 << 5 && "alignment greater than 1 << 64");
2115     AlignRecord |= AI.isUsedWithInAlloca() << 5;
2116     AlignRecord |= 1 << 6;
2117     // Reserve bit 7 for SwiftError flag.
2118     // AlignRecord |= AI.isSwiftError() << 7;
2119     Vals.push_back(AlignRecord);
2120     break;
2121   }
2122 
2123   case Instruction::Load:
2124     if (cast<LoadInst>(I).isAtomic()) {
2125       Code = bitc::FUNC_CODE_INST_LOADATOMIC;
2126       PushValueAndType(I.getOperand(0), InstID, Vals, VE);
2127     } else {
2128       Code = bitc::FUNC_CODE_INST_LOAD;
2129       if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))  // ptr
2130         AbbrevToUse = FUNCTION_INST_LOAD_ABBREV;
2131     }
2132     Vals.push_back(VE.getTypeID(I.getType()));
2133     Vals.push_back(Log2_32(cast<LoadInst>(I).getAlignment())+1);
2134     Vals.push_back(cast<LoadInst>(I).isVolatile());
2135     if (cast<LoadInst>(I).isAtomic()) {
2136       Vals.push_back(GetEncodedOrdering(cast<LoadInst>(I).getOrdering()));
2137       Vals.push_back(GetEncodedSynchScope(cast<LoadInst>(I).getSynchScope()));
2138     }
2139     break;
2140   case Instruction::Store:
2141     if (cast<StoreInst>(I).isAtomic())
2142       Code = bitc::FUNC_CODE_INST_STOREATOMIC;
2143     else
2144       Code = bitc::FUNC_CODE_INST_STORE;
2145     PushValueAndType(I.getOperand(1), InstID, Vals, VE);  // ptrty + ptr
2146     PushValueAndType(I.getOperand(0), InstID, Vals, VE);  // valty + val
2147     Vals.push_back(Log2_32(cast<StoreInst>(I).getAlignment())+1);
2148     Vals.push_back(cast<StoreInst>(I).isVolatile());
2149     if (cast<StoreInst>(I).isAtomic()) {
2150       Vals.push_back(GetEncodedOrdering(cast<StoreInst>(I).getOrdering()));
2151       Vals.push_back(GetEncodedSynchScope(cast<StoreInst>(I).getSynchScope()));
2152     }
2153     break;
2154   case Instruction::AtomicCmpXchg:
2155     Code = bitc::FUNC_CODE_INST_CMPXCHG;
2156     PushValueAndType(I.getOperand(0), InstID, Vals, VE);  // ptrty + ptr
2157     PushValueAndType(I.getOperand(1), InstID, Vals, VE);  // cmp.
2158     pushValue(I.getOperand(2), InstID, Vals, VE);         // newval.
2159     Vals.push_back(cast<AtomicCmpXchgInst>(I).isVolatile());
2160     Vals.push_back(GetEncodedOrdering(
2161                      cast<AtomicCmpXchgInst>(I).getSuccessOrdering()));
2162     Vals.push_back(GetEncodedSynchScope(
2163                      cast<AtomicCmpXchgInst>(I).getSynchScope()));
2164     Vals.push_back(GetEncodedOrdering(
2165                      cast<AtomicCmpXchgInst>(I).getFailureOrdering()));
2166     Vals.push_back(cast<AtomicCmpXchgInst>(I).isWeak());
2167     break;
2168   case Instruction::AtomicRMW:
2169     Code = bitc::FUNC_CODE_INST_ATOMICRMW;
2170     PushValueAndType(I.getOperand(0), InstID, Vals, VE);  // ptrty + ptr
2171     pushValue(I.getOperand(1), InstID, Vals, VE);         // val.
2172     Vals.push_back(GetEncodedRMWOperation(
2173                      cast<AtomicRMWInst>(I).getOperation()));
2174     Vals.push_back(cast<AtomicRMWInst>(I).isVolatile());
2175     Vals.push_back(GetEncodedOrdering(cast<AtomicRMWInst>(I).getOrdering()));
2176     Vals.push_back(GetEncodedSynchScope(
2177                      cast<AtomicRMWInst>(I).getSynchScope()));
2178     break;
2179   case Instruction::Fence:
2180     Code = bitc::FUNC_CODE_INST_FENCE;
2181     Vals.push_back(GetEncodedOrdering(cast<FenceInst>(I).getOrdering()));
2182     Vals.push_back(GetEncodedSynchScope(cast<FenceInst>(I).getSynchScope()));
2183     break;
2184   case Instruction::Call: {
2185     const CallInst &CI = cast<CallInst>(I);
2186     FunctionType *FTy = CI.getFunctionType();
2187 
2188     if (CI.hasOperandBundles())
2189       WriteOperandBundles(Stream, &CI, InstID, VE);
2190 
2191     Code = bitc::FUNC_CODE_INST_CALL;
2192 
2193     Vals.push_back(VE.getAttributeID(CI.getAttributes()));
2194 
2195     unsigned Flags = GetOptimizationFlags(&I);
2196     Vals.push_back(CI.getCallingConv() << bitc::CALL_CCONV |
2197                    unsigned(CI.isTailCall()) << bitc::CALL_TAIL |
2198                    unsigned(CI.isMustTailCall()) << bitc::CALL_MUSTTAIL |
2199                    1 << bitc::CALL_EXPLICIT_TYPE |
2200                    unsigned(CI.isNoTailCall()) << bitc::CALL_NOTAIL |
2201                    unsigned(Flags != 0) << bitc::CALL_FMF);
2202     if (Flags != 0)
2203       Vals.push_back(Flags);
2204 
2205     Vals.push_back(VE.getTypeID(FTy));
2206     PushValueAndType(CI.getCalledValue(), InstID, Vals, VE);  // Callee
2207 
2208     // Emit value #'s for the fixed parameters.
2209     for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i) {
2210       // Check for labels (can happen with asm labels).
2211       if (FTy->getParamType(i)->isLabelTy())
2212         Vals.push_back(VE.getValueID(CI.getArgOperand(i)));
2213       else
2214         pushValue(CI.getArgOperand(i), InstID, Vals, VE);  // fixed param.
2215     }
2216 
2217     // Emit type/value pairs for varargs params.
2218     if (FTy->isVarArg()) {
2219       for (unsigned i = FTy->getNumParams(), e = CI.getNumArgOperands();
2220            i != e; ++i)
2221         PushValueAndType(CI.getArgOperand(i), InstID, Vals, VE);  // varargs
2222     }
2223     break;
2224   }
2225   case Instruction::VAArg:
2226     Code = bitc::FUNC_CODE_INST_VAARG;
2227     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));   // valistty
2228     pushValue(I.getOperand(0), InstID, Vals, VE); // valist.
2229     Vals.push_back(VE.getTypeID(I.getType())); // restype.
2230     break;
2231   }
2232 
2233   Stream.EmitRecord(Code, Vals, AbbrevToUse);
2234   Vals.clear();
2235 }
2236 
2237 /// Emit names for globals/functions etc. The VSTOffsetPlaceholder,
2238 /// BitcodeStartBit and ModuleSummaryIndex are only passed for the module-level
2239 /// VST, where we are including a function bitcode index and need to
2240 /// backpatch the VST forward declaration record.
2241 static void WriteValueSymbolTable(
2242     const ValueSymbolTable &VST, const ValueEnumerator &VE,
2243     BitstreamWriter &Stream, uint64_t VSTOffsetPlaceholder = 0,
2244     uint64_t BitcodeStartBit = 0,
2245     DenseMap<const Function *, std::unique_ptr<GlobalValueInfo>>
2246         *FunctionIndex = nullptr) {
2247   if (VST.empty()) {
2248     // WriteValueSymbolTableForwardDecl should have returned early as
2249     // well. Ensure this handling remains in sync by asserting that
2250     // the placeholder offset is not set.
2251     assert(VSTOffsetPlaceholder == 0);
2252     return;
2253   }
2254 
2255   if (VSTOffsetPlaceholder > 0) {
2256     // Get the offset of the VST we are writing, and backpatch it into
2257     // the VST forward declaration record.
2258     uint64_t VSTOffset = Stream.GetCurrentBitNo();
2259     // The BitcodeStartBit was the stream offset of the actual bitcode
2260     // (e.g. excluding any initial darwin header).
2261     VSTOffset -= BitcodeStartBit;
2262     assert((VSTOffset & 31) == 0 && "VST block not 32-bit aligned");
2263     Stream.BackpatchWord(VSTOffsetPlaceholder, VSTOffset / 32);
2264   }
2265 
2266   Stream.EnterSubblock(bitc::VALUE_SYMTAB_BLOCK_ID, 4);
2267 
2268   // For the module-level VST, add abbrev Ids for the VST_CODE_FNENTRY
2269   // records, which are not used in the per-function VSTs.
2270   unsigned FnEntry8BitAbbrev;
2271   unsigned FnEntry7BitAbbrev;
2272   unsigned FnEntry6BitAbbrev;
2273   if (VSTOffsetPlaceholder > 0) {
2274     // 8-bit fixed-width VST_CODE_FNENTRY function strings.
2275     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2276     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_FNENTRY));
2277     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // value id
2278     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // funcoffset
2279     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2280     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
2281     FnEntry8BitAbbrev = Stream.EmitAbbrev(Abbv);
2282 
2283     // 7-bit fixed width VST_CODE_FNENTRY function strings.
2284     Abbv = new BitCodeAbbrev();
2285     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_FNENTRY));
2286     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // value id
2287     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // funcoffset
2288     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2289     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
2290     FnEntry7BitAbbrev = Stream.EmitAbbrev(Abbv);
2291 
2292     // 6-bit char6 VST_CODE_FNENTRY function strings.
2293     Abbv = new BitCodeAbbrev();
2294     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_FNENTRY));
2295     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // value id
2296     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // funcoffset
2297     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2298     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
2299     FnEntry6BitAbbrev = Stream.EmitAbbrev(Abbv);
2300   }
2301 
2302   // FIXME: Set up the abbrev, we know how many values there are!
2303   // FIXME: We know if the type names can use 7-bit ascii.
2304   SmallVector<unsigned, 64> NameVals;
2305 
2306   for (const ValueName &Name : VST) {
2307     // Figure out the encoding to use for the name.
2308     StringEncoding Bits =
2309         getStringEncoding(Name.getKeyData(), Name.getKeyLength());
2310 
2311     unsigned AbbrevToUse = VST_ENTRY_8_ABBREV;
2312     NameVals.push_back(VE.getValueID(Name.getValue()));
2313 
2314     Function *F = dyn_cast<Function>(Name.getValue());
2315     if (!F) {
2316       // If value is an alias, need to get the aliased base object to
2317       // see if it is a function.
2318       auto *GA = dyn_cast<GlobalAlias>(Name.getValue());
2319       if (GA && GA->getBaseObject())
2320         F = dyn_cast<Function>(GA->getBaseObject());
2321     }
2322 
2323     // VST_CODE_ENTRY:   [valueid, namechar x N]
2324     // VST_CODE_FNENTRY: [valueid, funcoffset, namechar x N]
2325     // VST_CODE_BBENTRY: [bbid, namechar x N]
2326     unsigned Code;
2327     if (isa<BasicBlock>(Name.getValue())) {
2328       Code = bitc::VST_CODE_BBENTRY;
2329       if (Bits == SE_Char6)
2330         AbbrevToUse = VST_BBENTRY_6_ABBREV;
2331     } else if (F && !F->isDeclaration()) {
2332       // Must be the module-level VST, where we pass in the Index and
2333       // have a VSTOffsetPlaceholder. The function-level VST should not
2334       // contain any Function symbols.
2335       assert(FunctionIndex);
2336       assert(VSTOffsetPlaceholder > 0);
2337 
2338       // Save the word offset of the function (from the start of the
2339       // actual bitcode written to the stream).
2340       uint64_t BitcodeIndex =
2341           (*FunctionIndex)[F]->bitcodeIndex() - BitcodeStartBit;
2342       assert((BitcodeIndex & 31) == 0 && "function block not 32-bit aligned");
2343       NameVals.push_back(BitcodeIndex / 32);
2344 
2345       Code = bitc::VST_CODE_FNENTRY;
2346       AbbrevToUse = FnEntry8BitAbbrev;
2347       if (Bits == SE_Char6)
2348         AbbrevToUse = FnEntry6BitAbbrev;
2349       else if (Bits == SE_Fixed7)
2350         AbbrevToUse = FnEntry7BitAbbrev;
2351     } else {
2352       Code = bitc::VST_CODE_ENTRY;
2353       if (Bits == SE_Char6)
2354         AbbrevToUse = VST_ENTRY_6_ABBREV;
2355       else if (Bits == SE_Fixed7)
2356         AbbrevToUse = VST_ENTRY_7_ABBREV;
2357     }
2358 
2359     for (const auto P : Name.getKey())
2360       NameVals.push_back((unsigned char)P);
2361 
2362     // Emit the finished record.
2363     Stream.EmitRecord(Code, NameVals, AbbrevToUse);
2364     NameVals.clear();
2365   }
2366   Stream.ExitBlock();
2367 }
2368 
2369 /// Emit function names and summary offsets for the combined index
2370 /// used by ThinLTO.
2371 static void
2372 WriteCombinedValueSymbolTable(const ModuleSummaryIndex &Index,
2373                               BitstreamWriter &Stream,
2374                               std::map<uint64_t, unsigned> &GUIDToValueIdMap,
2375                               uint64_t VSTOffsetPlaceholder) {
2376   assert(VSTOffsetPlaceholder > 0 && "Expected non-zero VSTOffsetPlaceholder");
2377   // Get the offset of the VST we are writing, and backpatch it into
2378   // the VST forward declaration record.
2379   uint64_t VSTOffset = Stream.GetCurrentBitNo();
2380   assert((VSTOffset & 31) == 0 && "VST block not 32-bit aligned");
2381   Stream.BackpatchWord(VSTOffsetPlaceholder, VSTOffset / 32);
2382 
2383   Stream.EnterSubblock(bitc::VALUE_SYMTAB_BLOCK_ID, 4);
2384 
2385   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2386   Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_COMBINED_GVDEFENTRY));
2387   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // valueid
2388   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // sumoffset
2389   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // guid
2390   unsigned DefEntryAbbrev = Stream.EmitAbbrev(Abbv);
2391 
2392   Abbv = new BitCodeAbbrev();
2393   Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_COMBINED_ENTRY));
2394   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // valueid
2395   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // refguid
2396   unsigned EntryAbbrev = Stream.EmitAbbrev(Abbv);
2397 
2398   SmallVector<uint64_t, 64> NameVals;
2399 
2400   for (const auto &FII : Index) {
2401     uint64_t FuncGUID = FII.first;
2402     const auto &VMI = GUIDToValueIdMap.find(FuncGUID);
2403     assert(VMI != GUIDToValueIdMap.end());
2404 
2405     for (const auto &FI : FII.second) {
2406       // VST_CODE_COMBINED_GVDEFENTRY: [valueid, sumoffset, guid]
2407       NameVals.push_back(VMI->second);
2408       NameVals.push_back(FI->bitcodeIndex());
2409       NameVals.push_back(FuncGUID);
2410 
2411       // Emit the finished record.
2412       Stream.EmitRecord(bitc::VST_CODE_COMBINED_GVDEFENTRY, NameVals,
2413                         DefEntryAbbrev);
2414       NameVals.clear();
2415     }
2416     GUIDToValueIdMap.erase(VMI);
2417   }
2418   for (const auto &GVI : GUIDToValueIdMap) {
2419     // VST_CODE_COMBINED_ENTRY: [valueid, refguid]
2420     NameVals.push_back(GVI.second);
2421     NameVals.push_back(GVI.first);
2422 
2423     // Emit the finished record.
2424     Stream.EmitRecord(bitc::VST_CODE_COMBINED_ENTRY, NameVals, EntryAbbrev);
2425     NameVals.clear();
2426   }
2427   Stream.ExitBlock();
2428 }
2429 
2430 static void WriteUseList(ValueEnumerator &VE, UseListOrder &&Order,
2431                          BitstreamWriter &Stream) {
2432   assert(Order.Shuffle.size() >= 2 && "Shuffle too small");
2433   unsigned Code;
2434   if (isa<BasicBlock>(Order.V))
2435     Code = bitc::USELIST_CODE_BB;
2436   else
2437     Code = bitc::USELIST_CODE_DEFAULT;
2438 
2439   SmallVector<uint64_t, 64> Record(Order.Shuffle.begin(), Order.Shuffle.end());
2440   Record.push_back(VE.getValueID(Order.V));
2441   Stream.EmitRecord(Code, Record);
2442 }
2443 
2444 static void WriteUseListBlock(const Function *F, ValueEnumerator &VE,
2445                               BitstreamWriter &Stream) {
2446   assert(VE.shouldPreserveUseListOrder() &&
2447          "Expected to be preserving use-list order");
2448 
2449   auto hasMore = [&]() {
2450     return !VE.UseListOrders.empty() && VE.UseListOrders.back().F == F;
2451   };
2452   if (!hasMore())
2453     // Nothing to do.
2454     return;
2455 
2456   Stream.EnterSubblock(bitc::USELIST_BLOCK_ID, 3);
2457   while (hasMore()) {
2458     WriteUseList(VE, std::move(VE.UseListOrders.back()), Stream);
2459     VE.UseListOrders.pop_back();
2460   }
2461   Stream.ExitBlock();
2462 }
2463 
2464 // Walk through the operands of a given User via worklist iteration and populate
2465 // the set of GlobalValue references encountered. Invoked either on an
2466 // Instruction or a GlobalVariable (which walks its initializer).
2467 static void findRefEdges(const User *CurUser, const ValueEnumerator &VE,
2468                          DenseSet<unsigned> &RefEdges,
2469                          SmallPtrSet<const User *, 8> &Visited) {
2470   SmallVector<const User *, 32> Worklist;
2471   Worklist.push_back(CurUser);
2472 
2473   while (!Worklist.empty()) {
2474     const User *U = Worklist.pop_back_val();
2475 
2476     if (!Visited.insert(U).second)
2477       continue;
2478 
2479     ImmutableCallSite CS(U);
2480 
2481     for (const auto &OI : U->operands()) {
2482       const User *Operand = dyn_cast<User>(OI);
2483       if (!Operand)
2484         continue;
2485       if (isa<BlockAddress>(Operand))
2486         continue;
2487       if (isa<GlobalValue>(Operand)) {
2488         // We have a reference to a global value. This should be added to
2489         // the reference set unless it is a callee. Callees are handled
2490         // specially by WriteFunction and are added to a separate list.
2491         if (!(CS && CS.isCallee(&OI)))
2492           RefEdges.insert(VE.getValueID(Operand));
2493         continue;
2494       }
2495       Worklist.push_back(Operand);
2496     }
2497   }
2498 }
2499 
2500 /// Emit a function body to the module stream.
2501 static void WriteFunction(
2502     const Function &F, const Module *M, ValueEnumerator &VE,
2503     BitstreamWriter &Stream,
2504     DenseMap<const Function *, std::unique_ptr<GlobalValueInfo>> &FunctionIndex,
2505     bool EmitSummaryIndex) {
2506   // Save the bitcode index of the start of this function block for recording
2507   // in the VST.
2508   uint64_t BitcodeIndex = Stream.GetCurrentBitNo();
2509 
2510   bool HasProfileData = F.getEntryCount().hasValue();
2511   std::unique_ptr<BlockFrequencyInfo> BFI;
2512   if (EmitSummaryIndex && HasProfileData) {
2513     Function &Func = const_cast<Function &>(F);
2514     LoopInfo LI{DominatorTree(Func)};
2515     BranchProbabilityInfo BPI{Func, LI};
2516     BFI = llvm::make_unique<BlockFrequencyInfo>(Func, BPI, LI);
2517   }
2518 
2519   Stream.EnterSubblock(bitc::FUNCTION_BLOCK_ID, 4);
2520   VE.incorporateFunction(F);
2521 
2522   SmallVector<unsigned, 64> Vals;
2523 
2524   // Emit the number of basic blocks, so the reader can create them ahead of
2525   // time.
2526   Vals.push_back(VE.getBasicBlocks().size());
2527   Stream.EmitRecord(bitc::FUNC_CODE_DECLAREBLOCKS, Vals);
2528   Vals.clear();
2529 
2530   // If there are function-local constants, emit them now.
2531   unsigned CstStart, CstEnd;
2532   VE.getFunctionConstantRange(CstStart, CstEnd);
2533   WriteConstants(CstStart, CstEnd, VE, Stream, false);
2534 
2535   // If there is function-local metadata, emit it now.
2536   WriteFunctionLocalMetadata(F, VE, Stream);
2537 
2538   // Keep a running idea of what the instruction ID is.
2539   unsigned InstID = CstEnd;
2540 
2541   bool NeedsMetadataAttachment = F.hasMetadata();
2542 
2543   DILocation *LastDL = nullptr;
2544   unsigned NumInsts = 0;
2545   // Map from callee ValueId to profile count. Used to accumulate profile
2546   // counts for all static calls to a given callee.
2547   DenseMap<unsigned, CalleeInfo> CallGraphEdges;
2548   DenseSet<unsigned> RefEdges;
2549 
2550   SmallPtrSet<const User *, 8> Visited;
2551   // Finally, emit all the instructions, in order.
2552   for (Function::const_iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
2553     for (BasicBlock::const_iterator I = BB->begin(), E = BB->end();
2554          I != E; ++I) {
2555       WriteInstruction(*I, InstID, VE, Stream, Vals);
2556 
2557       if (!isa<DbgInfoIntrinsic>(I))
2558         ++NumInsts;
2559 
2560       if (!I->getType()->isVoidTy())
2561         ++InstID;
2562 
2563       if (EmitSummaryIndex) {
2564         if (auto CS = ImmutableCallSite(&*I)) {
2565           auto *CalledFunction = CS.getCalledFunction();
2566           if (CalledFunction && CalledFunction->hasName() &&
2567               !CalledFunction->isIntrinsic()) {
2568             auto ScaledCount = BFI ? BFI->getBlockProfileCount(&*BB) : None;
2569             unsigned CalleeId = VE.getValueID(
2570                 M->getValueSymbolTable().lookup(CalledFunction->getName()));
2571             CallGraphEdges[CalleeId] +=
2572                 (ScaledCount ? ScaledCount.getValue() : 0);
2573           }
2574         }
2575         findRefEdges(&*I, VE, RefEdges, Visited);
2576       }
2577 
2578       // If the instruction has metadata, write a metadata attachment later.
2579       NeedsMetadataAttachment |= I->hasMetadataOtherThanDebugLoc();
2580 
2581       // If the instruction has a debug location, emit it.
2582       DILocation *DL = I->getDebugLoc();
2583       if (!DL)
2584         continue;
2585 
2586       if (DL == LastDL) {
2587         // Just repeat the same debug loc as last time.
2588         Stream.EmitRecord(bitc::FUNC_CODE_DEBUG_LOC_AGAIN, Vals);
2589         continue;
2590       }
2591 
2592       Vals.push_back(DL->getLine());
2593       Vals.push_back(DL->getColumn());
2594       Vals.push_back(VE.getMetadataOrNullID(DL->getScope()));
2595       Vals.push_back(VE.getMetadataOrNullID(DL->getInlinedAt()));
2596       Stream.EmitRecord(bitc::FUNC_CODE_DEBUG_LOC, Vals);
2597       Vals.clear();
2598 
2599       LastDL = DL;
2600     }
2601 
2602   std::unique_ptr<FunctionSummary> FuncSummary;
2603   if (EmitSummaryIndex) {
2604     FuncSummary = llvm::make_unique<FunctionSummary>(F.getLinkage(), NumInsts);
2605     FuncSummary->addCallGraphEdges(CallGraphEdges);
2606     FuncSummary->addRefEdges(RefEdges);
2607   }
2608   FunctionIndex[&F] =
2609       llvm::make_unique<GlobalValueInfo>(BitcodeIndex, std::move(FuncSummary));
2610 
2611   // Emit names for all the instructions etc.
2612   WriteValueSymbolTable(F.getValueSymbolTable(), VE, Stream);
2613 
2614   if (NeedsMetadataAttachment)
2615     WriteMetadataAttachment(F, VE, Stream);
2616   if (VE.shouldPreserveUseListOrder())
2617     WriteUseListBlock(&F, VE, Stream);
2618   VE.purgeFunction();
2619   Stream.ExitBlock();
2620 }
2621 
2622 // Emit blockinfo, which defines the standard abbreviations etc.
2623 static void WriteBlockInfo(const ValueEnumerator &VE, BitstreamWriter &Stream) {
2624   // We only want to emit block info records for blocks that have multiple
2625   // instances: CONSTANTS_BLOCK, FUNCTION_BLOCK and VALUE_SYMTAB_BLOCK.
2626   // Other blocks can define their abbrevs inline.
2627   Stream.EnterBlockInfoBlock(2);
2628 
2629   { // 8-bit fixed-width VST_CODE_ENTRY/VST_CODE_BBENTRY strings.
2630     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2631     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 3));
2632     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
2633     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2634     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
2635     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
2636                                    Abbv) != VST_ENTRY_8_ABBREV)
2637       llvm_unreachable("Unexpected abbrev ordering!");
2638   }
2639 
2640   { // 7-bit fixed width VST_CODE_ENTRY strings.
2641     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2642     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
2643     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
2644     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2645     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
2646     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
2647                                    Abbv) != VST_ENTRY_7_ABBREV)
2648       llvm_unreachable("Unexpected abbrev ordering!");
2649   }
2650   { // 6-bit char6 VST_CODE_ENTRY strings.
2651     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2652     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
2653     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
2654     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2655     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
2656     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
2657                                    Abbv) != VST_ENTRY_6_ABBREV)
2658       llvm_unreachable("Unexpected abbrev ordering!");
2659   }
2660   { // 6-bit char6 VST_CODE_BBENTRY strings.
2661     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2662     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_BBENTRY));
2663     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
2664     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2665     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
2666     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
2667                                    Abbv) != VST_BBENTRY_6_ABBREV)
2668       llvm_unreachable("Unexpected abbrev ordering!");
2669   }
2670 
2671 
2672 
2673   { // SETTYPE abbrev for CONSTANTS_BLOCK.
2674     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2675     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_SETTYPE));
2676     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
2677                               VE.computeBitsRequiredForTypeIndicies()));
2678     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
2679                                    Abbv) != CONSTANTS_SETTYPE_ABBREV)
2680       llvm_unreachable("Unexpected abbrev ordering!");
2681   }
2682 
2683   { // INTEGER abbrev for CONSTANTS_BLOCK.
2684     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2685     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_INTEGER));
2686     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
2687     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
2688                                    Abbv) != CONSTANTS_INTEGER_ABBREV)
2689       llvm_unreachable("Unexpected abbrev ordering!");
2690   }
2691 
2692   { // CE_CAST abbrev for CONSTANTS_BLOCK.
2693     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2694     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CE_CAST));
2695     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // cast opc
2696     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // typeid
2697                               VE.computeBitsRequiredForTypeIndicies()));
2698     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));    // value id
2699 
2700     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
2701                                    Abbv) != CONSTANTS_CE_CAST_Abbrev)
2702       llvm_unreachable("Unexpected abbrev ordering!");
2703   }
2704   { // NULL abbrev for CONSTANTS_BLOCK.
2705     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2706     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_NULL));
2707     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
2708                                    Abbv) != CONSTANTS_NULL_Abbrev)
2709       llvm_unreachable("Unexpected abbrev ordering!");
2710   }
2711 
2712   // FIXME: This should only use space for first class types!
2713 
2714   { // INST_LOAD abbrev for FUNCTION_BLOCK.
2715     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2716     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_LOAD));
2717     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Ptr
2718     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,    // dest ty
2719                               VE.computeBitsRequiredForTypeIndicies()));
2720     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4)); // Align
2721     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // volatile
2722     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
2723                                    Abbv) != FUNCTION_INST_LOAD_ABBREV)
2724       llvm_unreachable("Unexpected abbrev ordering!");
2725   }
2726   { // INST_BINOP abbrev for FUNCTION_BLOCK.
2727     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2728     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
2729     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
2730     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
2731     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
2732     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
2733                                    Abbv) != FUNCTION_INST_BINOP_ABBREV)
2734       llvm_unreachable("Unexpected abbrev ordering!");
2735   }
2736   { // INST_BINOP_FLAGS abbrev for FUNCTION_BLOCK.
2737     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2738     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
2739     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
2740     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
2741     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
2742     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7)); // flags
2743     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
2744                                    Abbv) != FUNCTION_INST_BINOP_FLAGS_ABBREV)
2745       llvm_unreachable("Unexpected abbrev ordering!");
2746   }
2747   { // INST_CAST abbrev for FUNCTION_BLOCK.
2748     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2749     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_CAST));
2750     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));    // OpVal
2751     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // dest ty
2752                               VE.computeBitsRequiredForTypeIndicies()));
2753     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // opc
2754     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
2755                                    Abbv) != FUNCTION_INST_CAST_ABBREV)
2756       llvm_unreachable("Unexpected abbrev ordering!");
2757   }
2758 
2759   { // INST_RET abbrev for FUNCTION_BLOCK.
2760     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2761     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
2762     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
2763                                    Abbv) != FUNCTION_INST_RET_VOID_ABBREV)
2764       llvm_unreachable("Unexpected abbrev ordering!");
2765   }
2766   { // INST_RET abbrev for FUNCTION_BLOCK.
2767     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2768     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
2769     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // ValID
2770     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
2771                                    Abbv) != FUNCTION_INST_RET_VAL_ABBREV)
2772       llvm_unreachable("Unexpected abbrev ordering!");
2773   }
2774   { // INST_UNREACHABLE abbrev for FUNCTION_BLOCK.
2775     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2776     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_UNREACHABLE));
2777     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
2778                                    Abbv) != FUNCTION_INST_UNREACHABLE_ABBREV)
2779       llvm_unreachable("Unexpected abbrev ordering!");
2780   }
2781   {
2782     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2783     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_GEP));
2784     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
2785     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, // dest ty
2786                               Log2_32_Ceil(VE.getTypes().size() + 1)));
2787     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2788     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
2789     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
2790         FUNCTION_INST_GEP_ABBREV)
2791       llvm_unreachable("Unexpected abbrev ordering!");
2792   }
2793 
2794   Stream.ExitBlock();
2795 }
2796 
2797 /// Write the module path strings, currently only used when generating
2798 /// a combined index file.
2799 static void WriteModStrings(const ModuleSummaryIndex &I,
2800                             BitstreamWriter &Stream) {
2801   Stream.EnterSubblock(bitc::MODULE_STRTAB_BLOCK_ID, 3);
2802 
2803   // TODO: See which abbrev sizes we actually need to emit
2804 
2805   // 8-bit fixed-width MST_ENTRY strings.
2806   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2807   Abbv->Add(BitCodeAbbrevOp(bitc::MST_CODE_ENTRY));
2808   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
2809   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2810   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
2811   unsigned Abbrev8Bit = Stream.EmitAbbrev(Abbv);
2812 
2813   // 7-bit fixed width MST_ENTRY strings.
2814   Abbv = new BitCodeAbbrev();
2815   Abbv->Add(BitCodeAbbrevOp(bitc::MST_CODE_ENTRY));
2816   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
2817   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2818   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
2819   unsigned Abbrev7Bit = Stream.EmitAbbrev(Abbv);
2820 
2821   // 6-bit char6 MST_ENTRY strings.
2822   Abbv = new BitCodeAbbrev();
2823   Abbv->Add(BitCodeAbbrevOp(bitc::MST_CODE_ENTRY));
2824   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
2825   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2826   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
2827   unsigned Abbrev6Bit = Stream.EmitAbbrev(Abbv);
2828 
2829   SmallVector<unsigned, 64> NameVals;
2830   for (const StringMapEntry<uint64_t> &MPSE : I.modPathStringEntries()) {
2831     StringEncoding Bits =
2832         getStringEncoding(MPSE.getKey().data(), MPSE.getKey().size());
2833     unsigned AbbrevToUse = Abbrev8Bit;
2834     if (Bits == SE_Char6)
2835       AbbrevToUse = Abbrev6Bit;
2836     else if (Bits == SE_Fixed7)
2837       AbbrevToUse = Abbrev7Bit;
2838 
2839     NameVals.push_back(MPSE.getValue());
2840 
2841     for (const auto P : MPSE.getKey())
2842       NameVals.push_back((unsigned char)P);
2843 
2844     // Emit the finished record.
2845     Stream.EmitRecord(bitc::MST_CODE_ENTRY, NameVals, AbbrevToUse);
2846     NameVals.clear();
2847   }
2848   Stream.ExitBlock();
2849 }
2850 
2851 // Helper to emit a single function summary record.
2852 static void WritePerModuleFunctionSummaryRecord(
2853     SmallVector<uint64_t, 64> &NameVals, FunctionSummary *FS, unsigned ValueID,
2854     unsigned FSCallsAbbrev, unsigned FSCallsProfileAbbrev,
2855     BitstreamWriter &Stream, const Function &F) {
2856   assert(FS);
2857   NameVals.push_back(ValueID);
2858   NameVals.push_back(getEncodedLinkage(FS->linkage()));
2859   NameVals.push_back(FS->instCount());
2860   NameVals.push_back(FS->refs().size());
2861 
2862   for (auto &RI : FS->refs())
2863     NameVals.push_back(RI);
2864 
2865   bool HasProfileData = F.getEntryCount().hasValue();
2866   for (auto &ECI : FS->edges()) {
2867     NameVals.push_back(ECI.first);
2868     assert(ECI.second.CallsiteCount > 0 && "Expected at least one callsite");
2869     NameVals.push_back(ECI.second.CallsiteCount);
2870     if (HasProfileData)
2871       NameVals.push_back(ECI.second.ProfileCount);
2872   }
2873 
2874   unsigned FSAbbrev = (HasProfileData ? FSCallsProfileAbbrev : FSCallsAbbrev);
2875   unsigned Code =
2876       (HasProfileData ? bitc::FS_PERMODULE_PROFILE : bitc::FS_PERMODULE);
2877 
2878   // Emit the finished record.
2879   Stream.EmitRecord(Code, NameVals, FSAbbrev);
2880   NameVals.clear();
2881 }
2882 
2883 // Collect the global value references in the given variable's initializer,
2884 // and emit them in a summary record.
2885 static void WriteModuleLevelReferences(const GlobalVariable &V,
2886                                        const ValueEnumerator &VE,
2887                                        SmallVector<uint64_t, 64> &NameVals,
2888                                        unsigned FSModRefsAbbrev,
2889                                        BitstreamWriter &Stream) {
2890   // Only interested in recording variable defs in the summary.
2891   if (V.isDeclaration())
2892     return;
2893   DenseSet<unsigned> RefEdges;
2894   SmallPtrSet<const User *, 8> Visited;
2895   findRefEdges(&V, VE, RefEdges, Visited);
2896   NameVals.push_back(VE.getValueID(&V));
2897   NameVals.push_back(getEncodedLinkage(V.getLinkage()));
2898   for (auto RefId : RefEdges) {
2899     NameVals.push_back(RefId);
2900   }
2901   Stream.EmitRecord(bitc::FS_PERMODULE_GLOBALVAR_INIT_REFS, NameVals,
2902                     FSModRefsAbbrev);
2903   NameVals.clear();
2904 }
2905 
2906 /// Emit the per-module summary section alongside the rest of
2907 /// the module's bitcode.
2908 static void WritePerModuleGlobalValueSummary(
2909     DenseMap<const Function *, std::unique_ptr<GlobalValueInfo>> &FunctionIndex,
2910     const Module *M, const ValueEnumerator &VE, BitstreamWriter &Stream) {
2911   if (M->empty())
2912     return;
2913 
2914   Stream.EnterSubblock(bitc::GLOBALVAL_SUMMARY_BLOCK_ID, 3);
2915 
2916   // Abbrev for FS_PERMODULE.
2917   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2918   Abbv->Add(BitCodeAbbrevOp(bitc::FS_PERMODULE));
2919   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
2920   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 5)); // linkage
2921   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
2922   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
2923   // numrefs x valueid, n x (valueid, callsitecount)
2924   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2925   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
2926   unsigned FSCallsAbbrev = Stream.EmitAbbrev(Abbv);
2927 
2928   // Abbrev for FS_PERMODULE_PROFILE.
2929   Abbv = new BitCodeAbbrev();
2930   Abbv->Add(BitCodeAbbrevOp(bitc::FS_PERMODULE_PROFILE));
2931   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
2932   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 5)); // linkage
2933   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
2934   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
2935   // numrefs x valueid, n x (valueid, callsitecount, profilecount)
2936   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2937   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
2938   unsigned FSCallsProfileAbbrev = Stream.EmitAbbrev(Abbv);
2939 
2940   // Abbrev for FS_PERMODULE_GLOBALVAR_INIT_REFS.
2941   Abbv = new BitCodeAbbrev();
2942   Abbv->Add(BitCodeAbbrevOp(bitc::FS_PERMODULE_GLOBALVAR_INIT_REFS));
2943   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // valueid
2944   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 5)); // linkage
2945   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));  // valueids
2946   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
2947   unsigned FSModRefsAbbrev = Stream.EmitAbbrev(Abbv);
2948 
2949   SmallVector<uint64_t, 64> NameVals;
2950   // Iterate over the list of functions instead of the FunctionIndex map to
2951   // ensure the ordering is stable.
2952   for (const Function &F : *M) {
2953     if (F.isDeclaration())
2954       continue;
2955     // Skip anonymous functions. We will emit a function summary for
2956     // any aliases below.
2957     if (!F.hasName())
2958       continue;
2959 
2960     assert(FunctionIndex.count(&F) == 1);
2961 
2962     WritePerModuleFunctionSummaryRecord(
2963         NameVals, cast<FunctionSummary>(FunctionIndex[&F]->summary()),
2964         VE.getValueID(M->getValueSymbolTable().lookup(F.getName())),
2965         FSCallsAbbrev, FSCallsProfileAbbrev, Stream, F);
2966   }
2967 
2968   for (const GlobalAlias &A : M->aliases()) {
2969     if (!A.getBaseObject())
2970       continue;
2971     const Function *F = dyn_cast<Function>(A.getBaseObject());
2972     if (!F || F->isDeclaration())
2973       continue;
2974 
2975     assert(FunctionIndex.count(F) == 1);
2976     FunctionSummary *FS =
2977         cast<FunctionSummary>(FunctionIndex[F]->summary());
2978     // Add the alias to the reference list of aliasee function.
2979     FS->addRefEdge(
2980         VE.getValueID(M->getValueSymbolTable().lookup(A.getName())));
2981     WritePerModuleFunctionSummaryRecord(
2982         NameVals, FS,
2983         VE.getValueID(M->getValueSymbolTable().lookup(A.getName())),
2984         FSCallsAbbrev, FSCallsProfileAbbrev, Stream, *F);
2985   }
2986 
2987   // Capture references from GlobalVariable initializers, which are outside
2988   // of a function scope.
2989   for (const GlobalVariable &G : M->globals())
2990     WriteModuleLevelReferences(G, VE, NameVals, FSModRefsAbbrev, Stream);
2991   for (const GlobalAlias &A : M->aliases())
2992     if (auto *GV = dyn_cast<GlobalVariable>(A.getBaseObject()))
2993       WriteModuleLevelReferences(*GV, VE, NameVals, FSModRefsAbbrev, Stream);
2994 
2995   Stream.ExitBlock();
2996 }
2997 
2998 /// Emit the combined summary section into the combined index file.
2999 static void WriteCombinedGlobalValueSummary(
3000     const ModuleSummaryIndex &I, BitstreamWriter &Stream,
3001     std::map<uint64_t, unsigned> &GUIDToValueIdMap, unsigned GlobalValueId) {
3002   Stream.EnterSubblock(bitc::GLOBALVAL_SUMMARY_BLOCK_ID, 3);
3003 
3004   // Abbrev for FS_COMBINED.
3005   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
3006   Abbv->Add(BitCodeAbbrevOp(bitc::FS_COMBINED));
3007   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // modid
3008   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 5)); // linkage
3009   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
3010   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
3011   // numrefs x valueid, n x (valueid, callsitecount)
3012   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3013   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3014   unsigned FSCallsAbbrev = Stream.EmitAbbrev(Abbv);
3015 
3016   // Abbrev for FS_COMBINED_PROFILE.
3017   Abbv = new BitCodeAbbrev();
3018   Abbv->Add(BitCodeAbbrevOp(bitc::FS_COMBINED_PROFILE));
3019   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // modid
3020   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 5)); // linkage
3021   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
3022   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
3023   // numrefs x valueid, n x (valueid, callsitecount, profilecount)
3024   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3025   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3026   unsigned FSCallsProfileAbbrev = Stream.EmitAbbrev(Abbv);
3027 
3028   // Abbrev for FS_COMBINED_GLOBALVAR_INIT_REFS.
3029   Abbv = new BitCodeAbbrev();
3030   Abbv->Add(BitCodeAbbrevOp(bitc::FS_COMBINED_GLOBALVAR_INIT_REFS));
3031   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // modid
3032   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 5)); // linkage
3033   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));    // valueids
3034   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3035   unsigned FSModRefsAbbrev = Stream.EmitAbbrev(Abbv);
3036 
3037   SmallVector<uint64_t, 64> NameVals;
3038   for (const auto &FII : I) {
3039     for (auto &FI : FII.second) {
3040       GlobalValueSummary *S = FI->summary();
3041       assert(S);
3042 
3043       if (auto *VS = dyn_cast<GlobalVarSummary>(S)) {
3044         NameVals.push_back(I.getModuleId(VS->modulePath()));
3045         NameVals.push_back(getEncodedLinkage(VS->linkage()));
3046         for (auto &RI : VS->refs()) {
3047           const auto &VMI = GUIDToValueIdMap.find(RI);
3048           unsigned RefId;
3049           // If this GUID doesn't have an entry, assign one.
3050           if (VMI == GUIDToValueIdMap.end()) {
3051             GUIDToValueIdMap[RI] = ++GlobalValueId;
3052             RefId = GlobalValueId;
3053           } else {
3054             RefId = VMI->second;
3055           }
3056           NameVals.push_back(RefId);
3057         }
3058 
3059         // Record the starting offset of this summary entry for use
3060         // in the VST entry. Add the current code size since the
3061         // reader will invoke readRecord after the abbrev id read.
3062         FI->setBitcodeIndex(Stream.GetCurrentBitNo() +
3063                             Stream.GetAbbrevIDWidth());
3064 
3065         // Emit the finished record.
3066         Stream.EmitRecord(bitc::FS_COMBINED_GLOBALVAR_INIT_REFS, NameVals,
3067                           FSModRefsAbbrev);
3068         NameVals.clear();
3069         continue;
3070       }
3071 
3072       auto *FS = cast<FunctionSummary>(S);
3073       NameVals.push_back(I.getModuleId(FS->modulePath()));
3074       NameVals.push_back(getEncodedLinkage(FS->linkage()));
3075       NameVals.push_back(FS->instCount());
3076       NameVals.push_back(FS->refs().size());
3077 
3078       for (auto &RI : FS->refs()) {
3079         const auto &VMI = GUIDToValueIdMap.find(RI);
3080         unsigned RefId;
3081         // If this GUID doesn't have an entry, assign one.
3082         if (VMI == GUIDToValueIdMap.end()) {
3083           GUIDToValueIdMap[RI] = ++GlobalValueId;
3084           RefId = GlobalValueId;
3085         } else {
3086           RefId = VMI->second;
3087         }
3088         NameVals.push_back(RefId);
3089       }
3090 
3091       bool HasProfileData = false;
3092       for (auto &EI : FS->edges()) {
3093         HasProfileData |= EI.second.ProfileCount != 0;
3094         if (HasProfileData)
3095           break;
3096       }
3097 
3098       for (auto &EI : FS->edges()) {
3099         const auto &VMI = GUIDToValueIdMap.find(EI.first);
3100         // If this GUID doesn't have an entry, it doesn't have a function
3101         // summary and we don't need to record any calls to it.
3102         if (VMI == GUIDToValueIdMap.end())
3103           continue;
3104         NameVals.push_back(VMI->second);
3105         assert(EI.second.CallsiteCount > 0 && "Expected at least one callsite");
3106         NameVals.push_back(EI.second.CallsiteCount);
3107         if (HasProfileData)
3108           NameVals.push_back(EI.second.ProfileCount);
3109       }
3110 
3111       // Record the starting offset of this summary entry for use
3112       // in the VST entry. Add the current code size since the
3113       // reader will invoke readRecord after the abbrev id read.
3114       FI->setBitcodeIndex(Stream.GetCurrentBitNo() + Stream.GetAbbrevIDWidth());
3115 
3116       unsigned FSAbbrev =
3117           (HasProfileData ? FSCallsProfileAbbrev : FSCallsAbbrev);
3118       unsigned Code =
3119           (HasProfileData ? bitc::FS_COMBINED_PROFILE : bitc::FS_COMBINED);
3120 
3121       // Emit the finished record.
3122       Stream.EmitRecord(Code, NameVals, FSAbbrev);
3123       NameVals.clear();
3124     }
3125   }
3126 
3127   Stream.ExitBlock();
3128 }
3129 
3130 // Create the "IDENTIFICATION_BLOCK_ID" containing a single string with the
3131 // current llvm version, and a record for the epoch number.
3132 static void WriteIdentificationBlock(const Module *M, BitstreamWriter &Stream) {
3133   Stream.EnterSubblock(bitc::IDENTIFICATION_BLOCK_ID, 5);
3134 
3135   // Write the "user readable" string identifying the bitcode producer
3136   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
3137   Abbv->Add(BitCodeAbbrevOp(bitc::IDENTIFICATION_CODE_STRING));
3138   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3139   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
3140   auto StringAbbrev = Stream.EmitAbbrev(Abbv);
3141   WriteStringRecord(bitc::IDENTIFICATION_CODE_STRING,
3142                     "LLVM" LLVM_VERSION_STRING, StringAbbrev, Stream);
3143 
3144   // Write the epoch version
3145   Abbv = new BitCodeAbbrev();
3146   Abbv->Add(BitCodeAbbrevOp(bitc::IDENTIFICATION_CODE_EPOCH));
3147   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
3148   auto EpochAbbrev = Stream.EmitAbbrev(Abbv);
3149   SmallVector<unsigned, 1> Vals = {bitc::BITCODE_CURRENT_EPOCH};
3150   Stream.EmitRecord(bitc::IDENTIFICATION_CODE_EPOCH, Vals, EpochAbbrev);
3151   Stream.ExitBlock();
3152 }
3153 
3154 /// WriteModule - Emit the specified module to the bitstream.
3155 static void WriteModule(const Module *M, BitstreamWriter &Stream,
3156                         bool ShouldPreserveUseListOrder,
3157                         uint64_t BitcodeStartBit, bool EmitSummaryIndex) {
3158   Stream.EnterSubblock(bitc::MODULE_BLOCK_ID, 3);
3159 
3160   SmallVector<unsigned, 1> Vals;
3161   unsigned CurVersion = 1;
3162   Vals.push_back(CurVersion);
3163   Stream.EmitRecord(bitc::MODULE_CODE_VERSION, Vals);
3164 
3165   // Analyze the module, enumerating globals, functions, etc.
3166   ValueEnumerator VE(*M, ShouldPreserveUseListOrder);
3167 
3168   // Emit blockinfo, which defines the standard abbreviations etc.
3169   WriteBlockInfo(VE, Stream);
3170 
3171   // Emit information about attribute groups.
3172   WriteAttributeGroupTable(VE, Stream);
3173 
3174   // Emit information about parameter attributes.
3175   WriteAttributeTable(VE, Stream);
3176 
3177   // Emit information describing all of the types in the module.
3178   WriteTypeTable(VE, Stream);
3179 
3180   writeComdats(VE, Stream);
3181 
3182   // Emit top-level description of module, including target triple, inline asm,
3183   // descriptors for global variables, and function prototype info.
3184   uint64_t VSTOffsetPlaceholder = WriteModuleInfo(M, VE, Stream);
3185 
3186   // Emit constants.
3187   WriteModuleConstants(VE, Stream);
3188 
3189   // Emit metadata.
3190   WriteModuleMetadata(*M, VE, Stream);
3191 
3192   // Emit metadata.
3193   WriteModuleMetadataStore(M, Stream);
3194 
3195   // Emit module-level use-lists.
3196   if (VE.shouldPreserveUseListOrder())
3197     WriteUseListBlock(nullptr, VE, Stream);
3198 
3199   WriteOperandBundleTags(M, Stream);
3200 
3201   // Emit function bodies.
3202   DenseMap<const Function *, std::unique_ptr<GlobalValueInfo>> FunctionIndex;
3203   for (Module::const_iterator F = M->begin(), E = M->end(); F != E; ++F)
3204     if (!F->isDeclaration())
3205       WriteFunction(*F, M, VE, Stream, FunctionIndex, EmitSummaryIndex);
3206 
3207   // Need to write after the above call to WriteFunction which populates
3208   // the summary information in the index.
3209   if (EmitSummaryIndex)
3210     WritePerModuleGlobalValueSummary(FunctionIndex, M, VE, Stream);
3211 
3212   WriteValueSymbolTable(M->getValueSymbolTable(), VE, Stream,
3213                         VSTOffsetPlaceholder, BitcodeStartBit, &FunctionIndex);
3214 
3215   Stream.ExitBlock();
3216 }
3217 
3218 /// EmitDarwinBCHeader - If generating a bc file on darwin, we have to emit a
3219 /// header and trailer to make it compatible with the system archiver.  To do
3220 /// this we emit the following header, and then emit a trailer that pads the
3221 /// file out to be a multiple of 16 bytes.
3222 ///
3223 /// struct bc_header {
3224 ///   uint32_t Magic;         // 0x0B17C0DE
3225 ///   uint32_t Version;       // Version, currently always 0.
3226 ///   uint32_t BitcodeOffset; // Offset to traditional bitcode file.
3227 ///   uint32_t BitcodeSize;   // Size of traditional bitcode file.
3228 ///   uint32_t CPUType;       // CPU specifier.
3229 ///   ... potentially more later ...
3230 /// };
3231 
3232 static void WriteInt32ToBuffer(uint32_t Value, SmallVectorImpl<char> &Buffer,
3233                                uint32_t &Position) {
3234   support::endian::write32le(&Buffer[Position], Value);
3235   Position += 4;
3236 }
3237 
3238 static void EmitDarwinBCHeaderAndTrailer(SmallVectorImpl<char> &Buffer,
3239                                          const Triple &TT) {
3240   unsigned CPUType = ~0U;
3241 
3242   // Match x86_64-*, i[3-9]86-*, powerpc-*, powerpc64-*, arm-*, thumb-*,
3243   // armv[0-9]-*, thumbv[0-9]-*, armv5te-*, or armv6t2-*. The CPUType is a magic
3244   // number from /usr/include/mach/machine.h.  It is ok to reproduce the
3245   // specific constants here because they are implicitly part of the Darwin ABI.
3246   enum {
3247     DARWIN_CPU_ARCH_ABI64      = 0x01000000,
3248     DARWIN_CPU_TYPE_X86        = 7,
3249     DARWIN_CPU_TYPE_ARM        = 12,
3250     DARWIN_CPU_TYPE_POWERPC    = 18
3251   };
3252 
3253   Triple::ArchType Arch = TT.getArch();
3254   if (Arch == Triple::x86_64)
3255     CPUType = DARWIN_CPU_TYPE_X86 | DARWIN_CPU_ARCH_ABI64;
3256   else if (Arch == Triple::x86)
3257     CPUType = DARWIN_CPU_TYPE_X86;
3258   else if (Arch == Triple::ppc)
3259     CPUType = DARWIN_CPU_TYPE_POWERPC;
3260   else if (Arch == Triple::ppc64)
3261     CPUType = DARWIN_CPU_TYPE_POWERPC | DARWIN_CPU_ARCH_ABI64;
3262   else if (Arch == Triple::arm || Arch == Triple::thumb)
3263     CPUType = DARWIN_CPU_TYPE_ARM;
3264 
3265   // Traditional Bitcode starts after header.
3266   assert(Buffer.size() >= BWH_HeaderSize &&
3267          "Expected header size to be reserved");
3268   unsigned BCOffset = BWH_HeaderSize;
3269   unsigned BCSize = Buffer.size() - BWH_HeaderSize;
3270 
3271   // Write the magic and version.
3272   unsigned Position = 0;
3273   WriteInt32ToBuffer(0x0B17C0DE , Buffer, Position);
3274   WriteInt32ToBuffer(0          , Buffer, Position); // Version.
3275   WriteInt32ToBuffer(BCOffset   , Buffer, Position);
3276   WriteInt32ToBuffer(BCSize     , Buffer, Position);
3277   WriteInt32ToBuffer(CPUType    , Buffer, Position);
3278 
3279   // If the file is not a multiple of 16 bytes, insert dummy padding.
3280   while (Buffer.size() & 15)
3281     Buffer.push_back(0);
3282 }
3283 
3284 /// Helper to write the header common to all bitcode files.
3285 static void WriteBitcodeHeader(BitstreamWriter &Stream) {
3286   // Emit the file header.
3287   Stream.Emit((unsigned)'B', 8);
3288   Stream.Emit((unsigned)'C', 8);
3289   Stream.Emit(0x0, 4);
3290   Stream.Emit(0xC, 4);
3291   Stream.Emit(0xE, 4);
3292   Stream.Emit(0xD, 4);
3293 }
3294 
3295 /// WriteBitcodeToFile - Write the specified module to the specified output
3296 /// stream.
3297 void llvm::WriteBitcodeToFile(const Module *M, raw_ostream &Out,
3298                               bool ShouldPreserveUseListOrder,
3299                               bool EmitSummaryIndex) {
3300   SmallVector<char, 0> Buffer;
3301   Buffer.reserve(256*1024);
3302 
3303   // If this is darwin or another generic macho target, reserve space for the
3304   // header.
3305   Triple TT(M->getTargetTriple());
3306   if (TT.isOSDarwin() || TT.isOSBinFormatMachO())
3307     Buffer.insert(Buffer.begin(), BWH_HeaderSize, 0);
3308 
3309   // Emit the module into the buffer.
3310   {
3311     BitstreamWriter Stream(Buffer);
3312     // Save the start bit of the actual bitcode, in case there is space
3313     // saved at the start for the darwin header above. The reader stream
3314     // will start at the bitcode, and we need the offset of the VST
3315     // to line up.
3316     uint64_t BitcodeStartBit = Stream.GetCurrentBitNo();
3317 
3318     // Emit the file header.
3319     WriteBitcodeHeader(Stream);
3320 
3321     WriteIdentificationBlock(M, Stream);
3322 
3323     // Emit the module.
3324     WriteModule(M, Stream, ShouldPreserveUseListOrder, BitcodeStartBit,
3325                 EmitSummaryIndex);
3326   }
3327 
3328   if (TT.isOSDarwin() || TT.isOSBinFormatMachO())
3329     EmitDarwinBCHeaderAndTrailer(Buffer, TT);
3330 
3331   // Write the generated bitstream to "Out".
3332   Out.write((char*)&Buffer.front(), Buffer.size());
3333 }
3334 
3335 // Write the specified module summary index to the given raw output stream,
3336 // where it will be written in a new bitcode block. This is used when
3337 // writing the combined index file for ThinLTO.
3338 void llvm::WriteIndexToFile(const ModuleSummaryIndex &Index, raw_ostream &Out) {
3339   SmallVector<char, 0> Buffer;
3340   Buffer.reserve(256 * 1024);
3341 
3342   BitstreamWriter Stream(Buffer);
3343 
3344   // Emit the bitcode header.
3345   WriteBitcodeHeader(Stream);
3346 
3347   Stream.EnterSubblock(bitc::MODULE_BLOCK_ID, 3);
3348 
3349   SmallVector<unsigned, 1> Vals;
3350   unsigned CurVersion = 1;
3351   Vals.push_back(CurVersion);
3352   Stream.EmitRecord(bitc::MODULE_CODE_VERSION, Vals);
3353 
3354   // If we have a VST, write the VSTOFFSET record placeholder and record
3355   // its offset.
3356   uint64_t VSTOffsetPlaceholder = WriteValueSymbolTableForwardDecl(Stream);
3357 
3358   // Write the module paths in the combined index.
3359   WriteModStrings(Index, Stream);
3360 
3361   // Assign unique value ids to all functions in the index for use
3362   // in writing out the call graph edges. Save the mapping from GUID
3363   // to the new global value id to use when writing those edges, which
3364   // are currently saved in the index in terms of GUID.
3365   std::map<uint64_t, unsigned> GUIDToValueIdMap;
3366   unsigned GlobalValueId = 0;
3367   for (auto &II : Index)
3368     GUIDToValueIdMap[II.first] = ++GlobalValueId;
3369 
3370   // Write the summary combined index records.
3371   WriteCombinedGlobalValueSummary(Index, Stream, GUIDToValueIdMap,
3372                                   GlobalValueId);
3373 
3374   // Need a special VST writer for the combined index (we don't have a
3375   // real VST and real values when this is invoked).
3376   WriteCombinedValueSymbolTable(Index, Stream, GUIDToValueIdMap,
3377                                 VSTOffsetPlaceholder);
3378 
3379   Stream.ExitBlock();
3380 
3381   Out.write((char *)&Buffer.front(), Buffer.size());
3382 }
3383