xref: /llvm-project/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp (revision f46262e0b7a183c22b9384cd729c5fb0f05e5d38)
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::SwiftSelf:
263     return bitc::ATTR_KIND_SWIFT_SELF;
264   case Attribute::UWTable:
265     return bitc::ATTR_KIND_UW_TABLE;
266   case Attribute::ZExt:
267     return bitc::ATTR_KIND_Z_EXT;
268   case Attribute::EndAttrKinds:
269     llvm_unreachable("Can not encode end-attribute kinds marker.");
270   case Attribute::None:
271     llvm_unreachable("Can not encode none-attribute.");
272   }
273 
274   llvm_unreachable("Trying to encode unknown attribute");
275 }
276 
277 static void WriteAttributeGroupTable(const ValueEnumerator &VE,
278                                      BitstreamWriter &Stream) {
279   const std::vector<AttributeSet> &AttrGrps = VE.getAttributeGroups();
280   if (AttrGrps.empty()) return;
281 
282   Stream.EnterSubblock(bitc::PARAMATTR_GROUP_BLOCK_ID, 3);
283 
284   SmallVector<uint64_t, 64> Record;
285   for (unsigned i = 0, e = AttrGrps.size(); i != e; ++i) {
286     AttributeSet AS = AttrGrps[i];
287     for (unsigned i = 0, e = AS.getNumSlots(); i != e; ++i) {
288       AttributeSet A = AS.getSlotAttributes(i);
289 
290       Record.push_back(VE.getAttributeGroupID(A));
291       Record.push_back(AS.getSlotIndex(i));
292 
293       for (AttributeSet::iterator I = AS.begin(0), E = AS.end(0);
294            I != E; ++I) {
295         Attribute Attr = *I;
296         if (Attr.isEnumAttribute()) {
297           Record.push_back(0);
298           Record.push_back(getAttrKindEncoding(Attr.getKindAsEnum()));
299         } else if (Attr.isIntAttribute()) {
300           Record.push_back(1);
301           Record.push_back(getAttrKindEncoding(Attr.getKindAsEnum()));
302           Record.push_back(Attr.getValueAsInt());
303         } else {
304           StringRef Kind = Attr.getKindAsString();
305           StringRef Val = Attr.getValueAsString();
306 
307           Record.push_back(Val.empty() ? 3 : 4);
308           Record.append(Kind.begin(), Kind.end());
309           Record.push_back(0);
310           if (!Val.empty()) {
311             Record.append(Val.begin(), Val.end());
312             Record.push_back(0);
313           }
314         }
315       }
316 
317       Stream.EmitRecord(bitc::PARAMATTR_GRP_CODE_ENTRY, Record);
318       Record.clear();
319     }
320   }
321 
322   Stream.ExitBlock();
323 }
324 
325 static void WriteAttributeTable(const ValueEnumerator &VE,
326                                 BitstreamWriter &Stream) {
327   const std::vector<AttributeSet> &Attrs = VE.getAttributes();
328   if (Attrs.empty()) return;
329 
330   Stream.EnterSubblock(bitc::PARAMATTR_BLOCK_ID, 3);
331 
332   SmallVector<uint64_t, 64> Record;
333   for (unsigned i = 0, e = Attrs.size(); i != e; ++i) {
334     const AttributeSet &A = Attrs[i];
335     for (unsigned i = 0, e = A.getNumSlots(); i != e; ++i)
336       Record.push_back(VE.getAttributeGroupID(A.getSlotAttributes(i)));
337 
338     Stream.EmitRecord(bitc::PARAMATTR_CODE_ENTRY, Record);
339     Record.clear();
340   }
341 
342   Stream.ExitBlock();
343 }
344 
345 /// WriteTypeTable - Write out the type table for a module.
346 static void WriteTypeTable(const ValueEnumerator &VE, BitstreamWriter &Stream) {
347   const ValueEnumerator::TypeList &TypeList = VE.getTypes();
348 
349   Stream.EnterSubblock(bitc::TYPE_BLOCK_ID_NEW, 4 /*count from # abbrevs */);
350   SmallVector<uint64_t, 64> TypeVals;
351 
352   uint64_t NumBits = VE.computeBitsRequiredForTypeIndicies();
353 
354   // Abbrev for TYPE_CODE_POINTER.
355   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
356   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_POINTER));
357   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
358   Abbv->Add(BitCodeAbbrevOp(0));  // Addrspace = 0
359   unsigned PtrAbbrev = Stream.EmitAbbrev(Abbv);
360 
361   // Abbrev for TYPE_CODE_FUNCTION.
362   Abbv = new BitCodeAbbrev();
363   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_FUNCTION));
364   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // isvararg
365   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
366   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
367 
368   unsigned FunctionAbbrev = Stream.EmitAbbrev(Abbv);
369 
370   // Abbrev for TYPE_CODE_STRUCT_ANON.
371   Abbv = new BitCodeAbbrev();
372   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_ANON));
373   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // ispacked
374   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
375   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
376 
377   unsigned StructAnonAbbrev = Stream.EmitAbbrev(Abbv);
378 
379   // Abbrev for TYPE_CODE_STRUCT_NAME.
380   Abbv = new BitCodeAbbrev();
381   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_NAME));
382   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
383   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
384   unsigned StructNameAbbrev = Stream.EmitAbbrev(Abbv);
385 
386   // Abbrev for TYPE_CODE_STRUCT_NAMED.
387   Abbv = new BitCodeAbbrev();
388   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_NAMED));
389   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // ispacked
390   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
391   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
392 
393   unsigned StructNamedAbbrev = Stream.EmitAbbrev(Abbv);
394 
395   // Abbrev for TYPE_CODE_ARRAY.
396   Abbv = new BitCodeAbbrev();
397   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_ARRAY));
398   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // size
399   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
400 
401   unsigned ArrayAbbrev = Stream.EmitAbbrev(Abbv);
402 
403   // Emit an entry count so the reader can reserve space.
404   TypeVals.push_back(TypeList.size());
405   Stream.EmitRecord(bitc::TYPE_CODE_NUMENTRY, TypeVals);
406   TypeVals.clear();
407 
408   // Loop over all of the types, emitting each in turn.
409   for (unsigned i = 0, e = TypeList.size(); i != e; ++i) {
410     Type *T = TypeList[i];
411     int AbbrevToUse = 0;
412     unsigned Code = 0;
413 
414     switch (T->getTypeID()) {
415     case Type::VoidTyID:      Code = bitc::TYPE_CODE_VOID;      break;
416     case Type::HalfTyID:      Code = bitc::TYPE_CODE_HALF;      break;
417     case Type::FloatTyID:     Code = bitc::TYPE_CODE_FLOAT;     break;
418     case Type::DoubleTyID:    Code = bitc::TYPE_CODE_DOUBLE;    break;
419     case Type::X86_FP80TyID:  Code = bitc::TYPE_CODE_X86_FP80;  break;
420     case Type::FP128TyID:     Code = bitc::TYPE_CODE_FP128;     break;
421     case Type::PPC_FP128TyID: Code = bitc::TYPE_CODE_PPC_FP128; break;
422     case Type::LabelTyID:     Code = bitc::TYPE_CODE_LABEL;     break;
423     case Type::MetadataTyID:  Code = bitc::TYPE_CODE_METADATA;  break;
424     case Type::X86_MMXTyID:   Code = bitc::TYPE_CODE_X86_MMX;   break;
425     case Type::TokenTyID:     Code = bitc::TYPE_CODE_TOKEN;     break;
426     case Type::IntegerTyID:
427       // INTEGER: [width]
428       Code = bitc::TYPE_CODE_INTEGER;
429       TypeVals.push_back(cast<IntegerType>(T)->getBitWidth());
430       break;
431     case Type::PointerTyID: {
432       PointerType *PTy = cast<PointerType>(T);
433       // POINTER: [pointee type, address space]
434       Code = bitc::TYPE_CODE_POINTER;
435       TypeVals.push_back(VE.getTypeID(PTy->getElementType()));
436       unsigned AddressSpace = PTy->getAddressSpace();
437       TypeVals.push_back(AddressSpace);
438       if (AddressSpace == 0) AbbrevToUse = PtrAbbrev;
439       break;
440     }
441     case Type::FunctionTyID: {
442       FunctionType *FT = cast<FunctionType>(T);
443       // FUNCTION: [isvararg, retty, paramty x N]
444       Code = bitc::TYPE_CODE_FUNCTION;
445       TypeVals.push_back(FT->isVarArg());
446       TypeVals.push_back(VE.getTypeID(FT->getReturnType()));
447       for (unsigned i = 0, e = FT->getNumParams(); i != e; ++i)
448         TypeVals.push_back(VE.getTypeID(FT->getParamType(i)));
449       AbbrevToUse = FunctionAbbrev;
450       break;
451     }
452     case Type::StructTyID: {
453       StructType *ST = cast<StructType>(T);
454       // STRUCT: [ispacked, eltty x N]
455       TypeVals.push_back(ST->isPacked());
456       // Output all of the element types.
457       for (StructType::element_iterator I = ST->element_begin(),
458            E = ST->element_end(); I != E; ++I)
459         TypeVals.push_back(VE.getTypeID(*I));
460 
461       if (ST->isLiteral()) {
462         Code = bitc::TYPE_CODE_STRUCT_ANON;
463         AbbrevToUse = StructAnonAbbrev;
464       } else {
465         if (ST->isOpaque()) {
466           Code = bitc::TYPE_CODE_OPAQUE;
467         } else {
468           Code = bitc::TYPE_CODE_STRUCT_NAMED;
469           AbbrevToUse = StructNamedAbbrev;
470         }
471 
472         // Emit the name if it is present.
473         if (!ST->getName().empty())
474           WriteStringRecord(bitc::TYPE_CODE_STRUCT_NAME, ST->getName(),
475                             StructNameAbbrev, Stream);
476       }
477       break;
478     }
479     case Type::ArrayTyID: {
480       ArrayType *AT = cast<ArrayType>(T);
481       // ARRAY: [numelts, eltty]
482       Code = bitc::TYPE_CODE_ARRAY;
483       TypeVals.push_back(AT->getNumElements());
484       TypeVals.push_back(VE.getTypeID(AT->getElementType()));
485       AbbrevToUse = ArrayAbbrev;
486       break;
487     }
488     case Type::VectorTyID: {
489       VectorType *VT = cast<VectorType>(T);
490       // VECTOR [numelts, eltty]
491       Code = bitc::TYPE_CODE_VECTOR;
492       TypeVals.push_back(VT->getNumElements());
493       TypeVals.push_back(VE.getTypeID(VT->getElementType()));
494       break;
495     }
496     }
497 
498     // Emit the finished record.
499     Stream.EmitRecord(Code, TypeVals, AbbrevToUse);
500     TypeVals.clear();
501   }
502 
503   Stream.ExitBlock();
504 }
505 
506 static unsigned getEncodedLinkage(const GlobalValue::LinkageTypes Linkage) {
507   switch (Linkage) {
508   case GlobalValue::ExternalLinkage:
509     return 0;
510   case GlobalValue::WeakAnyLinkage:
511     return 16;
512   case GlobalValue::AppendingLinkage:
513     return 2;
514   case GlobalValue::InternalLinkage:
515     return 3;
516   case GlobalValue::LinkOnceAnyLinkage:
517     return 18;
518   case GlobalValue::ExternalWeakLinkage:
519     return 7;
520   case GlobalValue::CommonLinkage:
521     return 8;
522   case GlobalValue::PrivateLinkage:
523     return 9;
524   case GlobalValue::WeakODRLinkage:
525     return 17;
526   case GlobalValue::LinkOnceODRLinkage:
527     return 19;
528   case GlobalValue::AvailableExternallyLinkage:
529     return 12;
530   }
531   llvm_unreachable("Invalid linkage");
532 }
533 
534 static unsigned getEncodedLinkage(const GlobalValue &GV) {
535   return getEncodedLinkage(GV.getLinkage());
536 }
537 
538 static unsigned getEncodedVisibility(const GlobalValue &GV) {
539   switch (GV.getVisibility()) {
540   case GlobalValue::DefaultVisibility:   return 0;
541   case GlobalValue::HiddenVisibility:    return 1;
542   case GlobalValue::ProtectedVisibility: return 2;
543   }
544   llvm_unreachable("Invalid visibility");
545 }
546 
547 static unsigned getEncodedDLLStorageClass(const GlobalValue &GV) {
548   switch (GV.getDLLStorageClass()) {
549   case GlobalValue::DefaultStorageClass:   return 0;
550   case GlobalValue::DLLImportStorageClass: return 1;
551   case GlobalValue::DLLExportStorageClass: return 2;
552   }
553   llvm_unreachable("Invalid DLL storage class");
554 }
555 
556 static unsigned getEncodedThreadLocalMode(const GlobalValue &GV) {
557   switch (GV.getThreadLocalMode()) {
558     case GlobalVariable::NotThreadLocal:         return 0;
559     case GlobalVariable::GeneralDynamicTLSModel: return 1;
560     case GlobalVariable::LocalDynamicTLSModel:   return 2;
561     case GlobalVariable::InitialExecTLSModel:    return 3;
562     case GlobalVariable::LocalExecTLSModel:      return 4;
563   }
564   llvm_unreachable("Invalid TLS model");
565 }
566 
567 static unsigned getEncodedComdatSelectionKind(const Comdat &C) {
568   switch (C.getSelectionKind()) {
569   case Comdat::Any:
570     return bitc::COMDAT_SELECTION_KIND_ANY;
571   case Comdat::ExactMatch:
572     return bitc::COMDAT_SELECTION_KIND_EXACT_MATCH;
573   case Comdat::Largest:
574     return bitc::COMDAT_SELECTION_KIND_LARGEST;
575   case Comdat::NoDuplicates:
576     return bitc::COMDAT_SELECTION_KIND_NO_DUPLICATES;
577   case Comdat::SameSize:
578     return bitc::COMDAT_SELECTION_KIND_SAME_SIZE;
579   }
580   llvm_unreachable("Invalid selection kind");
581 }
582 
583 static void writeComdats(const ValueEnumerator &VE, BitstreamWriter &Stream) {
584   SmallVector<unsigned, 64> Vals;
585   for (const Comdat *C : VE.getComdats()) {
586     // COMDAT: [selection_kind, name]
587     Vals.push_back(getEncodedComdatSelectionKind(*C));
588     size_t Size = C->getName().size();
589     assert(isUInt<32>(Size));
590     Vals.push_back(Size);
591     for (char Chr : C->getName())
592       Vals.push_back((unsigned char)Chr);
593     Stream.EmitRecord(bitc::MODULE_CODE_COMDAT, Vals, /*AbbrevToUse=*/0);
594     Vals.clear();
595   }
596 }
597 
598 /// Write a record that will eventually hold the word offset of the
599 /// module-level VST. For now the offset is 0, which will be backpatched
600 /// after the real VST is written. Returns the bit offset to backpatch.
601 static uint64_t WriteValueSymbolTableForwardDecl(BitstreamWriter &Stream) {
602   // Write a placeholder value in for the offset of the real VST,
603   // which is written after the function blocks so that it can include
604   // the offset of each function. The placeholder offset will be
605   // updated when the real VST is written.
606   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
607   Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_VSTOFFSET));
608   // Blocks are 32-bit aligned, so we can use a 32-bit word offset to
609   // hold the real VST offset. Must use fixed instead of VBR as we don't
610   // know how many VBR chunks to reserve ahead of time.
611   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
612   unsigned VSTOffsetAbbrev = Stream.EmitAbbrev(Abbv);
613 
614   // Emit the placeholder
615   uint64_t Vals[] = {bitc::MODULE_CODE_VSTOFFSET, 0};
616   Stream.EmitRecordWithAbbrev(VSTOffsetAbbrev, Vals);
617 
618   // Compute and return the bit offset to the placeholder, which will be
619   // patched when the real VST is written. We can simply subtract the 32-bit
620   // fixed size from the current bit number to get the location to backpatch.
621   return Stream.GetCurrentBitNo() - 32;
622 }
623 
624 enum StringEncoding { SE_Char6, SE_Fixed7, SE_Fixed8 };
625 
626 /// Determine the encoding to use for the given string name and length.
627 static StringEncoding getStringEncoding(const char *Str, unsigned StrLen) {
628   bool isChar6 = true;
629   for (const char *C = Str, *E = C + StrLen; C != E; ++C) {
630     if (isChar6)
631       isChar6 = BitCodeAbbrevOp::isChar6(*C);
632     if ((unsigned char)*C & 128)
633       // don't bother scanning the rest.
634       return SE_Fixed8;
635   }
636   if (isChar6)
637     return SE_Char6;
638   else
639     return SE_Fixed7;
640 }
641 
642 /// Emit top-level description of module, including target triple, inline asm,
643 /// descriptors for global variables, and function prototype info.
644 /// Returns the bit offset to backpatch with the location of the real VST.
645 static uint64_t WriteModuleInfo(const Module *M, const ValueEnumerator &VE,
646                                 BitstreamWriter &Stream) {
647   // Emit various pieces of data attached to a module.
648   if (!M->getTargetTriple().empty())
649     WriteStringRecord(bitc::MODULE_CODE_TRIPLE, M->getTargetTriple(),
650                       0/*TODO*/, Stream);
651   const std::string &DL = M->getDataLayoutStr();
652   if (!DL.empty())
653     WriteStringRecord(bitc::MODULE_CODE_DATALAYOUT, DL, 0 /*TODO*/, Stream);
654   if (!M->getModuleInlineAsm().empty())
655     WriteStringRecord(bitc::MODULE_CODE_ASM, M->getModuleInlineAsm(),
656                       0/*TODO*/, Stream);
657 
658   // Emit information about sections and GC, computing how many there are. Also
659   // compute the maximum alignment value.
660   std::map<std::string, unsigned> SectionMap;
661   std::map<std::string, unsigned> GCMap;
662   unsigned MaxAlignment = 0;
663   unsigned MaxGlobalType = 0;
664   for (const GlobalValue &GV : M->globals()) {
665     MaxAlignment = std::max(MaxAlignment, GV.getAlignment());
666     MaxGlobalType = std::max(MaxGlobalType, VE.getTypeID(GV.getValueType()));
667     if (GV.hasSection()) {
668       // Give section names unique ID's.
669       unsigned &Entry = SectionMap[GV.getSection()];
670       if (!Entry) {
671         WriteStringRecord(bitc::MODULE_CODE_SECTIONNAME, GV.getSection(),
672                           0/*TODO*/, Stream);
673         Entry = SectionMap.size();
674       }
675     }
676   }
677   for (const Function &F : *M) {
678     MaxAlignment = std::max(MaxAlignment, F.getAlignment());
679     if (F.hasSection()) {
680       // Give section names unique ID's.
681       unsigned &Entry = SectionMap[F.getSection()];
682       if (!Entry) {
683         WriteStringRecord(bitc::MODULE_CODE_SECTIONNAME, F.getSection(),
684                           0/*TODO*/, Stream);
685         Entry = SectionMap.size();
686       }
687     }
688     if (F.hasGC()) {
689       // Same for GC names.
690       unsigned &Entry = GCMap[F.getGC()];
691       if (!Entry) {
692         WriteStringRecord(bitc::MODULE_CODE_GCNAME, F.getGC(),
693                           0/*TODO*/, Stream);
694         Entry = GCMap.size();
695       }
696     }
697   }
698 
699   // Emit abbrev for globals, now that we know # sections and max alignment.
700   unsigned SimpleGVarAbbrev = 0;
701   if (!M->global_empty()) {
702     // Add an abbrev for common globals with no visibility or thread localness.
703     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
704     Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_GLOBALVAR));
705     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
706                               Log2_32_Ceil(MaxGlobalType+1)));
707     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // AddrSpace << 2
708                                                            //| explicitType << 1
709                                                            //| constant
710     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // Initializer.
711     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 5)); // Linkage.
712     if (MaxAlignment == 0)                                 // Alignment.
713       Abbv->Add(BitCodeAbbrevOp(0));
714     else {
715       unsigned MaxEncAlignment = Log2_32(MaxAlignment)+1;
716       Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
717                                Log2_32_Ceil(MaxEncAlignment+1)));
718     }
719     if (SectionMap.empty())                                    // Section.
720       Abbv->Add(BitCodeAbbrevOp(0));
721     else
722       Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
723                                Log2_32_Ceil(SectionMap.size()+1)));
724     // Don't bother emitting vis + thread local.
725     SimpleGVarAbbrev = Stream.EmitAbbrev(Abbv);
726   }
727 
728   // Emit the global variable information.
729   SmallVector<unsigned, 64> Vals;
730   for (const GlobalVariable &GV : M->globals()) {
731     unsigned AbbrevToUse = 0;
732 
733     // GLOBALVAR: [type, isconst, initid,
734     //             linkage, alignment, section, visibility, threadlocal,
735     //             unnamed_addr, externally_initialized, dllstorageclass,
736     //             comdat]
737     Vals.push_back(VE.getTypeID(GV.getValueType()));
738     Vals.push_back(GV.getType()->getAddressSpace() << 2 | 2 | GV.isConstant());
739     Vals.push_back(GV.isDeclaration() ? 0 :
740                    (VE.getValueID(GV.getInitializer()) + 1));
741     Vals.push_back(getEncodedLinkage(GV));
742     Vals.push_back(Log2_32(GV.getAlignment())+1);
743     Vals.push_back(GV.hasSection() ? SectionMap[GV.getSection()] : 0);
744     if (GV.isThreadLocal() ||
745         GV.getVisibility() != GlobalValue::DefaultVisibility ||
746         GV.hasUnnamedAddr() || GV.isExternallyInitialized() ||
747         GV.getDLLStorageClass() != GlobalValue::DefaultStorageClass ||
748         GV.hasComdat()) {
749       Vals.push_back(getEncodedVisibility(GV));
750       Vals.push_back(getEncodedThreadLocalMode(GV));
751       Vals.push_back(GV.hasUnnamedAddr());
752       Vals.push_back(GV.isExternallyInitialized());
753       Vals.push_back(getEncodedDLLStorageClass(GV));
754       Vals.push_back(GV.hasComdat() ? VE.getComdatID(GV.getComdat()) : 0);
755     } else {
756       AbbrevToUse = SimpleGVarAbbrev;
757     }
758 
759     Stream.EmitRecord(bitc::MODULE_CODE_GLOBALVAR, Vals, AbbrevToUse);
760     Vals.clear();
761   }
762 
763   // Emit the function proto information.
764   for (const Function &F : *M) {
765     // FUNCTION:  [type, callingconv, isproto, linkage, paramattrs, alignment,
766     //             section, visibility, gc, unnamed_addr, prologuedata,
767     //             dllstorageclass, comdat, prefixdata, personalityfn]
768     Vals.push_back(VE.getTypeID(F.getFunctionType()));
769     Vals.push_back(F.getCallingConv());
770     Vals.push_back(F.isDeclaration());
771     Vals.push_back(getEncodedLinkage(F));
772     Vals.push_back(VE.getAttributeID(F.getAttributes()));
773     Vals.push_back(Log2_32(F.getAlignment())+1);
774     Vals.push_back(F.hasSection() ? SectionMap[F.getSection()] : 0);
775     Vals.push_back(getEncodedVisibility(F));
776     Vals.push_back(F.hasGC() ? GCMap[F.getGC()] : 0);
777     Vals.push_back(F.hasUnnamedAddr());
778     Vals.push_back(F.hasPrologueData() ? (VE.getValueID(F.getPrologueData()) + 1)
779                                        : 0);
780     Vals.push_back(getEncodedDLLStorageClass(F));
781     Vals.push_back(F.hasComdat() ? VE.getComdatID(F.getComdat()) : 0);
782     Vals.push_back(F.hasPrefixData() ? (VE.getValueID(F.getPrefixData()) + 1)
783                                      : 0);
784     Vals.push_back(
785         F.hasPersonalityFn() ? (VE.getValueID(F.getPersonalityFn()) + 1) : 0);
786 
787     unsigned AbbrevToUse = 0;
788     Stream.EmitRecord(bitc::MODULE_CODE_FUNCTION, Vals, AbbrevToUse);
789     Vals.clear();
790   }
791 
792   // Emit the alias information.
793   for (const GlobalAlias &A : M->aliases()) {
794     // ALIAS: [alias type, aliasee val#, linkage, visibility]
795     Vals.push_back(VE.getTypeID(A.getValueType()));
796     Vals.push_back(A.getType()->getAddressSpace());
797     Vals.push_back(VE.getValueID(A.getAliasee()));
798     Vals.push_back(getEncodedLinkage(A));
799     Vals.push_back(getEncodedVisibility(A));
800     Vals.push_back(getEncodedDLLStorageClass(A));
801     Vals.push_back(getEncodedThreadLocalMode(A));
802     Vals.push_back(A.hasUnnamedAddr());
803     unsigned AbbrevToUse = 0;
804     Stream.EmitRecord(bitc::MODULE_CODE_ALIAS, Vals, AbbrevToUse);
805     Vals.clear();
806   }
807 
808   // Emit the module's source file name.
809   {
810     StringEncoding Bits = getStringEncoding(M->getSourceFileName().data(),
811                                             M->getSourceFileName().size());
812     BitCodeAbbrevOp AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8);
813     if (Bits == SE_Char6)
814       AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Char6);
815     else if (Bits == SE_Fixed7)
816       AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7);
817 
818     // MODULE_CODE_SOURCE_FILENAME: [namechar x N]
819     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
820     Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_SOURCE_FILENAME));
821     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
822     Abbv->Add(AbbrevOpToUse);
823     unsigned FilenameAbbrev = Stream.EmitAbbrev(Abbv);
824 
825     for (const auto P : M->getSourceFileName())
826       Vals.push_back((unsigned char)P);
827 
828     // Emit the finished record.
829     Stream.EmitRecord(bitc::MODULE_CODE_SOURCE_FILENAME, Vals, FilenameAbbrev);
830     Vals.clear();
831   }
832 
833   // If we have a VST, write the VSTOFFSET record placeholder and return
834   // its offset.
835   if (M->getValueSymbolTable().empty())
836     return 0;
837   return WriteValueSymbolTableForwardDecl(Stream);
838 }
839 
840 static uint64_t GetOptimizationFlags(const Value *V) {
841   uint64_t Flags = 0;
842 
843   if (const auto *OBO = dyn_cast<OverflowingBinaryOperator>(V)) {
844     if (OBO->hasNoSignedWrap())
845       Flags |= 1 << bitc::OBO_NO_SIGNED_WRAP;
846     if (OBO->hasNoUnsignedWrap())
847       Flags |= 1 << bitc::OBO_NO_UNSIGNED_WRAP;
848   } else if (const auto *PEO = dyn_cast<PossiblyExactOperator>(V)) {
849     if (PEO->isExact())
850       Flags |= 1 << bitc::PEO_EXACT;
851   } else if (const auto *FPMO = dyn_cast<FPMathOperator>(V)) {
852     if (FPMO->hasUnsafeAlgebra())
853       Flags |= FastMathFlags::UnsafeAlgebra;
854     if (FPMO->hasNoNaNs())
855       Flags |= FastMathFlags::NoNaNs;
856     if (FPMO->hasNoInfs())
857       Flags |= FastMathFlags::NoInfs;
858     if (FPMO->hasNoSignedZeros())
859       Flags |= FastMathFlags::NoSignedZeros;
860     if (FPMO->hasAllowReciprocal())
861       Flags |= FastMathFlags::AllowReciprocal;
862   }
863 
864   return Flags;
865 }
866 
867 static void writeValueAsMetadata(const ValueAsMetadata *MD,
868                                  const ValueEnumerator &VE,
869                                  BitstreamWriter &Stream,
870                                  SmallVectorImpl<uint64_t> &Record) {
871   // Mimic an MDNode with a value as one operand.
872   Value *V = MD->getValue();
873   Record.push_back(VE.getTypeID(V->getType()));
874   Record.push_back(VE.getValueID(V));
875   Stream.EmitRecord(bitc::METADATA_VALUE, Record, 0);
876   Record.clear();
877 }
878 
879 static void writeMDTuple(const MDTuple *N, const ValueEnumerator &VE,
880                          BitstreamWriter &Stream,
881                          SmallVectorImpl<uint64_t> &Record, unsigned Abbrev) {
882   for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i) {
883     Metadata *MD = N->getOperand(i);
884     assert(!(MD && isa<LocalAsMetadata>(MD)) &&
885            "Unexpected function-local metadata");
886     Record.push_back(VE.getMetadataOrNullID(MD));
887   }
888   Stream.EmitRecord(N->isDistinct() ? bitc::METADATA_DISTINCT_NODE
889                                     : bitc::METADATA_NODE,
890                     Record, Abbrev);
891   Record.clear();
892 }
893 
894 static unsigned createDILocationAbbrev(BitstreamWriter &Stream) {
895   // Assume the column is usually under 128, and always output the inlined-at
896   // location (it's never more expensive than building an array size 1).
897   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
898   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_LOCATION));
899   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
900   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
901   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
902   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
903   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
904   return Stream.EmitAbbrev(Abbv);
905 }
906 
907 static void writeDILocation(const DILocation *N, const ValueEnumerator &VE,
908                             BitstreamWriter &Stream,
909                             SmallVectorImpl<uint64_t> &Record,
910                             unsigned &Abbrev) {
911   if (!Abbrev)
912     Abbrev = createDILocationAbbrev(Stream);
913 
914   Record.push_back(N->isDistinct());
915   Record.push_back(N->getLine());
916   Record.push_back(N->getColumn());
917   Record.push_back(VE.getMetadataID(N->getScope()));
918   Record.push_back(VE.getMetadataOrNullID(N->getInlinedAt()));
919 
920   Stream.EmitRecord(bitc::METADATA_LOCATION, Record, Abbrev);
921   Record.clear();
922 }
923 
924 static unsigned createGenericDINodeAbbrev(BitstreamWriter &Stream) {
925   // Assume the column is usually under 128, and always output the inlined-at
926   // location (it's never more expensive than building an array size 1).
927   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
928   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_GENERIC_DEBUG));
929   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
930   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
931   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
932   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
933   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
934   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
935   return Stream.EmitAbbrev(Abbv);
936 }
937 
938 static void writeGenericDINode(const GenericDINode *N,
939                                const ValueEnumerator &VE,
940                                BitstreamWriter &Stream,
941                                SmallVectorImpl<uint64_t> &Record,
942                                unsigned &Abbrev) {
943   if (!Abbrev)
944     Abbrev = createGenericDINodeAbbrev(Stream);
945 
946   Record.push_back(N->isDistinct());
947   Record.push_back(N->getTag());
948   Record.push_back(0); // Per-tag version field; unused for now.
949 
950   for (auto &I : N->operands())
951     Record.push_back(VE.getMetadataOrNullID(I));
952 
953   Stream.EmitRecord(bitc::METADATA_GENERIC_DEBUG, Record, Abbrev);
954   Record.clear();
955 }
956 
957 static uint64_t rotateSign(int64_t I) {
958   uint64_t U = I;
959   return I < 0 ? ~(U << 1) : U << 1;
960 }
961 
962 static void writeDISubrange(const DISubrange *N, const ValueEnumerator &,
963                             BitstreamWriter &Stream,
964                             SmallVectorImpl<uint64_t> &Record,
965                             unsigned Abbrev) {
966   Record.push_back(N->isDistinct());
967   Record.push_back(N->getCount());
968   Record.push_back(rotateSign(N->getLowerBound()));
969 
970   Stream.EmitRecord(bitc::METADATA_SUBRANGE, Record, Abbrev);
971   Record.clear();
972 }
973 
974 static void writeDIEnumerator(const DIEnumerator *N, const ValueEnumerator &VE,
975                               BitstreamWriter &Stream,
976                               SmallVectorImpl<uint64_t> &Record,
977                               unsigned Abbrev) {
978   Record.push_back(N->isDistinct());
979   Record.push_back(rotateSign(N->getValue()));
980   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
981 
982   Stream.EmitRecord(bitc::METADATA_ENUMERATOR, Record, Abbrev);
983   Record.clear();
984 }
985 
986 static void writeDIBasicType(const DIBasicType *N, const ValueEnumerator &VE,
987                              BitstreamWriter &Stream,
988                              SmallVectorImpl<uint64_t> &Record,
989                              unsigned Abbrev) {
990   Record.push_back(N->isDistinct());
991   Record.push_back(N->getTag());
992   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
993   Record.push_back(N->getSizeInBits());
994   Record.push_back(N->getAlignInBits());
995   Record.push_back(N->getEncoding());
996 
997   Stream.EmitRecord(bitc::METADATA_BASIC_TYPE, Record, Abbrev);
998   Record.clear();
999 }
1000 
1001 static void writeDIDerivedType(const DIDerivedType *N,
1002                                const ValueEnumerator &VE,
1003                                BitstreamWriter &Stream,
1004                                SmallVectorImpl<uint64_t> &Record,
1005                                unsigned Abbrev) {
1006   Record.push_back(N->isDistinct());
1007   Record.push_back(N->getTag());
1008   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1009   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1010   Record.push_back(N->getLine());
1011   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1012   Record.push_back(VE.getMetadataOrNullID(N->getBaseType()));
1013   Record.push_back(N->getSizeInBits());
1014   Record.push_back(N->getAlignInBits());
1015   Record.push_back(N->getOffsetInBits());
1016   Record.push_back(N->getFlags());
1017   Record.push_back(VE.getMetadataOrNullID(N->getExtraData()));
1018 
1019   Stream.EmitRecord(bitc::METADATA_DERIVED_TYPE, Record, Abbrev);
1020   Record.clear();
1021 }
1022 
1023 static void writeDICompositeType(const DICompositeType *N,
1024                                  const ValueEnumerator &VE,
1025                                  BitstreamWriter &Stream,
1026                                  SmallVectorImpl<uint64_t> &Record,
1027                                  unsigned Abbrev) {
1028   Record.push_back(N->isDistinct());
1029   Record.push_back(N->getTag());
1030   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1031   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1032   Record.push_back(N->getLine());
1033   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1034   Record.push_back(VE.getMetadataOrNullID(N->getBaseType()));
1035   Record.push_back(N->getSizeInBits());
1036   Record.push_back(N->getAlignInBits());
1037   Record.push_back(N->getOffsetInBits());
1038   Record.push_back(N->getFlags());
1039   Record.push_back(VE.getMetadataOrNullID(N->getElements().get()));
1040   Record.push_back(N->getRuntimeLang());
1041   Record.push_back(VE.getMetadataOrNullID(N->getVTableHolder()));
1042   Record.push_back(VE.getMetadataOrNullID(N->getTemplateParams().get()));
1043   Record.push_back(VE.getMetadataOrNullID(N->getRawIdentifier()));
1044 
1045   Stream.EmitRecord(bitc::METADATA_COMPOSITE_TYPE, Record, Abbrev);
1046   Record.clear();
1047 }
1048 
1049 static void writeDISubroutineType(const DISubroutineType *N,
1050                                   const ValueEnumerator &VE,
1051                                   BitstreamWriter &Stream,
1052                                   SmallVectorImpl<uint64_t> &Record,
1053                                   unsigned Abbrev) {
1054   Record.push_back(N->isDistinct());
1055   Record.push_back(N->getFlags());
1056   Record.push_back(VE.getMetadataOrNullID(N->getTypeArray().get()));
1057 
1058   Stream.EmitRecord(bitc::METADATA_SUBROUTINE_TYPE, Record, Abbrev);
1059   Record.clear();
1060 }
1061 
1062 static void writeDIFile(const DIFile *N, const ValueEnumerator &VE,
1063                         BitstreamWriter &Stream,
1064                         SmallVectorImpl<uint64_t> &Record, unsigned Abbrev) {
1065   Record.push_back(N->isDistinct());
1066   Record.push_back(VE.getMetadataOrNullID(N->getRawFilename()));
1067   Record.push_back(VE.getMetadataOrNullID(N->getRawDirectory()));
1068 
1069   Stream.EmitRecord(bitc::METADATA_FILE, Record, Abbrev);
1070   Record.clear();
1071 }
1072 
1073 static void writeDICompileUnit(const DICompileUnit *N,
1074                                const ValueEnumerator &VE,
1075                                BitstreamWriter &Stream,
1076                                SmallVectorImpl<uint64_t> &Record,
1077                                unsigned Abbrev) {
1078   assert(N->isDistinct() && "Expected distinct compile units");
1079   Record.push_back(/* IsDistinct */ true);
1080   Record.push_back(N->getSourceLanguage());
1081   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1082   Record.push_back(VE.getMetadataOrNullID(N->getRawProducer()));
1083   Record.push_back(N->isOptimized());
1084   Record.push_back(VE.getMetadataOrNullID(N->getRawFlags()));
1085   Record.push_back(N->getRuntimeVersion());
1086   Record.push_back(VE.getMetadataOrNullID(N->getRawSplitDebugFilename()));
1087   Record.push_back(N->getEmissionKind());
1088   Record.push_back(VE.getMetadataOrNullID(N->getEnumTypes().get()));
1089   Record.push_back(VE.getMetadataOrNullID(N->getRetainedTypes().get()));
1090   Record.push_back(VE.getMetadataOrNullID(N->getSubprograms().get()));
1091   Record.push_back(VE.getMetadataOrNullID(N->getGlobalVariables().get()));
1092   Record.push_back(VE.getMetadataOrNullID(N->getImportedEntities().get()));
1093   Record.push_back(N->getDWOId());
1094   Record.push_back(VE.getMetadataOrNullID(N->getMacros().get()));
1095 
1096   Stream.EmitRecord(bitc::METADATA_COMPILE_UNIT, Record, Abbrev);
1097   Record.clear();
1098 }
1099 
1100 static void writeDISubprogram(const DISubprogram *N, const ValueEnumerator &VE,
1101                               BitstreamWriter &Stream,
1102                               SmallVectorImpl<uint64_t> &Record,
1103                               unsigned Abbrev) {
1104   Record.push_back(N->isDistinct());
1105   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1106   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1107   Record.push_back(VE.getMetadataOrNullID(N->getRawLinkageName()));
1108   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1109   Record.push_back(N->getLine());
1110   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1111   Record.push_back(N->isLocalToUnit());
1112   Record.push_back(N->isDefinition());
1113   Record.push_back(N->getScopeLine());
1114   Record.push_back(VE.getMetadataOrNullID(N->getContainingType()));
1115   Record.push_back(N->getVirtuality());
1116   Record.push_back(N->getVirtualIndex());
1117   Record.push_back(N->getFlags());
1118   Record.push_back(N->isOptimized());
1119   Record.push_back(VE.getMetadataOrNullID(N->getTemplateParams().get()));
1120   Record.push_back(VE.getMetadataOrNullID(N->getDeclaration()));
1121   Record.push_back(VE.getMetadataOrNullID(N->getVariables().get()));
1122 
1123   Stream.EmitRecord(bitc::METADATA_SUBPROGRAM, Record, Abbrev);
1124   Record.clear();
1125 }
1126 
1127 static void writeDILexicalBlock(const DILexicalBlock *N,
1128                                 const ValueEnumerator &VE,
1129                                 BitstreamWriter &Stream,
1130                                 SmallVectorImpl<uint64_t> &Record,
1131                                 unsigned Abbrev) {
1132   Record.push_back(N->isDistinct());
1133   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1134   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1135   Record.push_back(N->getLine());
1136   Record.push_back(N->getColumn());
1137 
1138   Stream.EmitRecord(bitc::METADATA_LEXICAL_BLOCK, Record, Abbrev);
1139   Record.clear();
1140 }
1141 
1142 static void writeDILexicalBlockFile(const DILexicalBlockFile *N,
1143                                     const ValueEnumerator &VE,
1144                                     BitstreamWriter &Stream,
1145                                     SmallVectorImpl<uint64_t> &Record,
1146                                     unsigned Abbrev) {
1147   Record.push_back(N->isDistinct());
1148   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1149   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1150   Record.push_back(N->getDiscriminator());
1151 
1152   Stream.EmitRecord(bitc::METADATA_LEXICAL_BLOCK_FILE, Record, Abbrev);
1153   Record.clear();
1154 }
1155 
1156 static void writeDINamespace(const DINamespace *N, const ValueEnumerator &VE,
1157                              BitstreamWriter &Stream,
1158                              SmallVectorImpl<uint64_t> &Record,
1159                              unsigned Abbrev) {
1160   Record.push_back(N->isDistinct());
1161   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1162   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1163   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1164   Record.push_back(N->getLine());
1165 
1166   Stream.EmitRecord(bitc::METADATA_NAMESPACE, Record, Abbrev);
1167   Record.clear();
1168 }
1169 
1170 static void writeDIMacro(const DIMacro *N, const ValueEnumerator &VE,
1171                          BitstreamWriter &Stream,
1172                          SmallVectorImpl<uint64_t> &Record, unsigned Abbrev) {
1173   Record.push_back(N->isDistinct());
1174   Record.push_back(N->getMacinfoType());
1175   Record.push_back(N->getLine());
1176   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1177   Record.push_back(VE.getMetadataOrNullID(N->getRawValue()));
1178 
1179   Stream.EmitRecord(bitc::METADATA_MACRO, Record, Abbrev);
1180   Record.clear();
1181 }
1182 
1183 static void writeDIMacroFile(const DIMacroFile *N, const ValueEnumerator &VE,
1184                              BitstreamWriter &Stream,
1185                              SmallVectorImpl<uint64_t> &Record,
1186                              unsigned Abbrev) {
1187   Record.push_back(N->isDistinct());
1188   Record.push_back(N->getMacinfoType());
1189   Record.push_back(N->getLine());
1190   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1191   Record.push_back(VE.getMetadataOrNullID(N->getElements().get()));
1192 
1193   Stream.EmitRecord(bitc::METADATA_MACRO_FILE, Record, Abbrev);
1194   Record.clear();
1195 }
1196 
1197 static void writeDIModule(const DIModule *N, const ValueEnumerator &VE,
1198                           BitstreamWriter &Stream,
1199                           SmallVectorImpl<uint64_t> &Record, unsigned Abbrev) {
1200   Record.push_back(N->isDistinct());
1201   for (auto &I : N->operands())
1202     Record.push_back(VE.getMetadataOrNullID(I));
1203 
1204   Stream.EmitRecord(bitc::METADATA_MODULE, Record, Abbrev);
1205   Record.clear();
1206 }
1207 
1208 static void writeDITemplateTypeParameter(const DITemplateTypeParameter *N,
1209                                          const ValueEnumerator &VE,
1210                                          BitstreamWriter &Stream,
1211                                          SmallVectorImpl<uint64_t> &Record,
1212                                          unsigned Abbrev) {
1213   Record.push_back(N->isDistinct());
1214   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1215   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1216 
1217   Stream.EmitRecord(bitc::METADATA_TEMPLATE_TYPE, Record, Abbrev);
1218   Record.clear();
1219 }
1220 
1221 static void writeDITemplateValueParameter(const DITemplateValueParameter *N,
1222                                           const ValueEnumerator &VE,
1223                                           BitstreamWriter &Stream,
1224                                           SmallVectorImpl<uint64_t> &Record,
1225                                           unsigned Abbrev) {
1226   Record.push_back(N->isDistinct());
1227   Record.push_back(N->getTag());
1228   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1229   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1230   Record.push_back(VE.getMetadataOrNullID(N->getValue()));
1231 
1232   Stream.EmitRecord(bitc::METADATA_TEMPLATE_VALUE, Record, Abbrev);
1233   Record.clear();
1234 }
1235 
1236 static void writeDIGlobalVariable(const DIGlobalVariable *N,
1237                                   const ValueEnumerator &VE,
1238                                   BitstreamWriter &Stream,
1239                                   SmallVectorImpl<uint64_t> &Record,
1240                                   unsigned Abbrev) {
1241   Record.push_back(N->isDistinct());
1242   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1243   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1244   Record.push_back(VE.getMetadataOrNullID(N->getRawLinkageName()));
1245   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1246   Record.push_back(N->getLine());
1247   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1248   Record.push_back(N->isLocalToUnit());
1249   Record.push_back(N->isDefinition());
1250   Record.push_back(VE.getMetadataOrNullID(N->getRawVariable()));
1251   Record.push_back(VE.getMetadataOrNullID(N->getStaticDataMemberDeclaration()));
1252 
1253   Stream.EmitRecord(bitc::METADATA_GLOBAL_VAR, Record, Abbrev);
1254   Record.clear();
1255 }
1256 
1257 static void writeDILocalVariable(const DILocalVariable *N,
1258                                  const ValueEnumerator &VE,
1259                                  BitstreamWriter &Stream,
1260                                  SmallVectorImpl<uint64_t> &Record,
1261                                  unsigned Abbrev) {
1262   Record.push_back(N->isDistinct());
1263   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1264   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1265   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1266   Record.push_back(N->getLine());
1267   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1268   Record.push_back(N->getArg());
1269   Record.push_back(N->getFlags());
1270 
1271   Stream.EmitRecord(bitc::METADATA_LOCAL_VAR, Record, Abbrev);
1272   Record.clear();
1273 }
1274 
1275 static void writeDIExpression(const DIExpression *N, const ValueEnumerator &,
1276                               BitstreamWriter &Stream,
1277                               SmallVectorImpl<uint64_t> &Record,
1278                               unsigned Abbrev) {
1279   Record.reserve(N->getElements().size() + 1);
1280 
1281   Record.push_back(N->isDistinct());
1282   Record.append(N->elements_begin(), N->elements_end());
1283 
1284   Stream.EmitRecord(bitc::METADATA_EXPRESSION, Record, Abbrev);
1285   Record.clear();
1286 }
1287 
1288 static void writeDIObjCProperty(const DIObjCProperty *N,
1289                                 const ValueEnumerator &VE,
1290                                 BitstreamWriter &Stream,
1291                                 SmallVectorImpl<uint64_t> &Record,
1292                                 unsigned Abbrev) {
1293   Record.push_back(N->isDistinct());
1294   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1295   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1296   Record.push_back(N->getLine());
1297   Record.push_back(VE.getMetadataOrNullID(N->getRawSetterName()));
1298   Record.push_back(VE.getMetadataOrNullID(N->getRawGetterName()));
1299   Record.push_back(N->getAttributes());
1300   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1301 
1302   Stream.EmitRecord(bitc::METADATA_OBJC_PROPERTY, Record, Abbrev);
1303   Record.clear();
1304 }
1305 
1306 static void writeDIImportedEntity(const DIImportedEntity *N,
1307                                   const ValueEnumerator &VE,
1308                                   BitstreamWriter &Stream,
1309                                   SmallVectorImpl<uint64_t> &Record,
1310                                   unsigned Abbrev) {
1311   Record.push_back(N->isDistinct());
1312   Record.push_back(N->getTag());
1313   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1314   Record.push_back(VE.getMetadataOrNullID(N->getEntity()));
1315   Record.push_back(N->getLine());
1316   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1317 
1318   Stream.EmitRecord(bitc::METADATA_IMPORTED_ENTITY, Record, Abbrev);
1319   Record.clear();
1320 }
1321 
1322 static unsigned createNamedMetadataAbbrev(BitstreamWriter &Stream) {
1323   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1324   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_NAME));
1325   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1326   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
1327   return Stream.EmitAbbrev(Abbv);
1328 }
1329 
1330 static void writeNamedMetadata(const Module &M, const ValueEnumerator &VE,
1331                                BitstreamWriter &Stream,
1332                                SmallVectorImpl<uint64_t> &Record) {
1333   if (M.named_metadata_empty())
1334     return;
1335 
1336   unsigned Abbrev = createNamedMetadataAbbrev(Stream);
1337   for (const NamedMDNode &NMD : M.named_metadata()) {
1338     // Write name.
1339     StringRef Str = NMD.getName();
1340     Record.append(Str.bytes_begin(), Str.bytes_end());
1341     Stream.EmitRecord(bitc::METADATA_NAME, Record, Abbrev);
1342     Record.clear();
1343 
1344     // Write named metadata operands.
1345     for (const MDNode *N : NMD.operands())
1346       Record.push_back(VE.getMetadataID(N));
1347     Stream.EmitRecord(bitc::METADATA_NAMED_NODE, Record, 0);
1348     Record.clear();
1349   }
1350 }
1351 
1352 static unsigned createMetadataStringsAbbrev(BitstreamWriter &Stream) {
1353   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1354   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_STRINGS));
1355   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // # of strings
1356   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // offset to chars
1357   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob));
1358   return Stream.EmitAbbrev(Abbv);
1359 }
1360 
1361 /// Write out a record for MDString.
1362 ///
1363 /// All the metadata strings in a metadata block are emitted in a single
1364 /// record.  The sizes and strings themselves are shoved into a blob.
1365 static void writeMetadataStrings(ArrayRef<const Metadata *> Strings,
1366                                  BitstreamWriter &Stream,
1367                                  SmallVectorImpl<uint64_t> &Record) {
1368   if (Strings.empty())
1369     return;
1370 
1371   // Start the record with the number of strings.
1372   Record.push_back(bitc::METADATA_STRINGS);
1373   Record.push_back(Strings.size());
1374 
1375   // Emit the sizes of the strings in the blob.
1376   SmallString<256> Blob;
1377   {
1378     BitstreamWriter W(Blob);
1379     for (const Metadata *MD : Strings)
1380       W.EmitVBR(cast<MDString>(MD)->getLength(), 6);
1381     W.FlushToWord();
1382   }
1383 
1384   // Add the offset to the strings to the record.
1385   Record.push_back(Blob.size());
1386 
1387   // Add the strings to the blob.
1388   for (const Metadata *MD : Strings)
1389     Blob.append(cast<MDString>(MD)->getString());
1390 
1391   // Emit the final record.
1392   Stream.EmitRecordWithBlob(createMetadataStringsAbbrev(Stream), Record, Blob);
1393   Record.clear();
1394 }
1395 
1396 static void writeMetadataRecords(ArrayRef<const Metadata *> MDs,
1397                                  const ValueEnumerator &VE,
1398                                  BitstreamWriter &Stream,
1399                                  SmallVectorImpl<uint64_t> &Record) {
1400   if (MDs.empty())
1401     return;
1402 
1403   // Initialize MDNode abbreviations.
1404 #define HANDLE_MDNODE_LEAF(CLASS) unsigned CLASS##Abbrev = 0;
1405 #include "llvm/IR/Metadata.def"
1406 
1407   for (const Metadata *MD : MDs) {
1408     if (const MDNode *N = dyn_cast<MDNode>(MD)) {
1409       assert(N->isResolved() && "Expected forward references to be resolved");
1410 
1411       switch (N->getMetadataID()) {
1412       default:
1413         llvm_unreachable("Invalid MDNode subclass");
1414 #define HANDLE_MDNODE_LEAF(CLASS)                                              \
1415   case Metadata::CLASS##Kind:                                                  \
1416     write##CLASS(cast<CLASS>(N), VE, Stream, Record, CLASS##Abbrev);           \
1417     continue;
1418 #include "llvm/IR/Metadata.def"
1419       }
1420     }
1421     writeValueAsMetadata(cast<ValueAsMetadata>(MD), VE, Stream, Record);
1422   }
1423 }
1424 
1425 static void writeModuleMetadata(const Module &M,
1426                                 const ValueEnumerator &VE,
1427                                 BitstreamWriter &Stream) {
1428   if (VE.getMDs().empty() && M.named_metadata_empty())
1429     return;
1430 
1431   Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
1432   SmallVector<uint64_t, 64> Record;
1433   writeMetadataStrings(VE.getMDStrings(), Stream, Record);
1434   writeMetadataRecords(VE.getNonMDStrings(), VE, Stream, Record);
1435   writeNamedMetadata(M, VE, Stream, Record);
1436   Stream.ExitBlock();
1437 }
1438 
1439 static void writeFunctionMetadata(const Function &F, const ValueEnumerator &VE,
1440                                   BitstreamWriter &Stream) {
1441   ArrayRef<const Metadata *> MDs = VE.getFunctionMDs();
1442   if (MDs.empty())
1443     return;
1444 
1445   Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
1446   SmallVector<uint64_t, 64> Record;
1447   writeMetadataRecords(MDs, VE, Stream, Record);
1448   Stream.ExitBlock();
1449 }
1450 
1451 static void WriteMetadataAttachment(const Function &F,
1452                                     const ValueEnumerator &VE,
1453                                     BitstreamWriter &Stream) {
1454   Stream.EnterSubblock(bitc::METADATA_ATTACHMENT_ID, 3);
1455 
1456   SmallVector<uint64_t, 64> Record;
1457 
1458   // Write metadata attachments
1459   // METADATA_ATTACHMENT - [m x [value, [n x [id, mdnode]]]
1460   SmallVector<std::pair<unsigned, MDNode *>, 4> MDs;
1461   F.getAllMetadata(MDs);
1462   if (!MDs.empty()) {
1463     for (const auto &I : MDs) {
1464       Record.push_back(I.first);
1465       Record.push_back(VE.getMetadataID(I.second));
1466     }
1467     Stream.EmitRecord(bitc::METADATA_ATTACHMENT, Record, 0);
1468     Record.clear();
1469   }
1470 
1471   for (const BasicBlock &BB : F)
1472     for (const Instruction &I : BB) {
1473       MDs.clear();
1474       I.getAllMetadataOtherThanDebugLoc(MDs);
1475 
1476       // If no metadata, ignore instruction.
1477       if (MDs.empty()) continue;
1478 
1479       Record.push_back(VE.getInstructionID(&I));
1480 
1481       for (unsigned i = 0, e = MDs.size(); i != e; ++i) {
1482         Record.push_back(MDs[i].first);
1483         Record.push_back(VE.getMetadataID(MDs[i].second));
1484       }
1485       Stream.EmitRecord(bitc::METADATA_ATTACHMENT, Record, 0);
1486       Record.clear();
1487     }
1488 
1489   Stream.ExitBlock();
1490 }
1491 
1492 static void WriteModuleMetadataStore(const Module *M, BitstreamWriter &Stream) {
1493   SmallVector<uint64_t, 64> Record;
1494 
1495   // Write metadata kinds
1496   // METADATA_KIND - [n x [id, name]]
1497   SmallVector<StringRef, 8> Names;
1498   M->getMDKindNames(Names);
1499 
1500   if (Names.empty()) return;
1501 
1502   Stream.EnterSubblock(bitc::METADATA_KIND_BLOCK_ID, 3);
1503 
1504   for (unsigned MDKindID = 0, e = Names.size(); MDKindID != e; ++MDKindID) {
1505     Record.push_back(MDKindID);
1506     StringRef KName = Names[MDKindID];
1507     Record.append(KName.begin(), KName.end());
1508 
1509     Stream.EmitRecord(bitc::METADATA_KIND, Record, 0);
1510     Record.clear();
1511   }
1512 
1513   Stream.ExitBlock();
1514 }
1515 
1516 static void WriteOperandBundleTags(const Module *M, BitstreamWriter &Stream) {
1517   // Write metadata kinds
1518   //
1519   // OPERAND_BUNDLE_TAGS_BLOCK_ID : N x OPERAND_BUNDLE_TAG
1520   //
1521   // OPERAND_BUNDLE_TAG - [strchr x N]
1522 
1523   SmallVector<StringRef, 8> Tags;
1524   M->getOperandBundleTags(Tags);
1525 
1526   if (Tags.empty())
1527     return;
1528 
1529   Stream.EnterSubblock(bitc::OPERAND_BUNDLE_TAGS_BLOCK_ID, 3);
1530 
1531   SmallVector<uint64_t, 64> Record;
1532 
1533   for (auto Tag : Tags) {
1534     Record.append(Tag.begin(), Tag.end());
1535 
1536     Stream.EmitRecord(bitc::OPERAND_BUNDLE_TAG, Record, 0);
1537     Record.clear();
1538   }
1539 
1540   Stream.ExitBlock();
1541 }
1542 
1543 static void emitSignedInt64(SmallVectorImpl<uint64_t> &Vals, uint64_t V) {
1544   if ((int64_t)V >= 0)
1545     Vals.push_back(V << 1);
1546   else
1547     Vals.push_back((-V << 1) | 1);
1548 }
1549 
1550 static void WriteConstants(unsigned FirstVal, unsigned LastVal,
1551                            const ValueEnumerator &VE,
1552                            BitstreamWriter &Stream, bool isGlobal) {
1553   if (FirstVal == LastVal) return;
1554 
1555   Stream.EnterSubblock(bitc::CONSTANTS_BLOCK_ID, 4);
1556 
1557   unsigned AggregateAbbrev = 0;
1558   unsigned String8Abbrev = 0;
1559   unsigned CString7Abbrev = 0;
1560   unsigned CString6Abbrev = 0;
1561   // If this is a constant pool for the module, emit module-specific abbrevs.
1562   if (isGlobal) {
1563     // Abbrev for CST_CODE_AGGREGATE.
1564     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1565     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_AGGREGATE));
1566     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1567     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, Log2_32_Ceil(LastVal+1)));
1568     AggregateAbbrev = Stream.EmitAbbrev(Abbv);
1569 
1570     // Abbrev for CST_CODE_STRING.
1571     Abbv = new BitCodeAbbrev();
1572     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_STRING));
1573     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1574     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
1575     String8Abbrev = Stream.EmitAbbrev(Abbv);
1576     // Abbrev for CST_CODE_CSTRING.
1577     Abbv = new BitCodeAbbrev();
1578     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
1579     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1580     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
1581     CString7Abbrev = Stream.EmitAbbrev(Abbv);
1582     // Abbrev for CST_CODE_CSTRING.
1583     Abbv = new BitCodeAbbrev();
1584     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
1585     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1586     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
1587     CString6Abbrev = Stream.EmitAbbrev(Abbv);
1588   }
1589 
1590   SmallVector<uint64_t, 64> Record;
1591 
1592   const ValueEnumerator::ValueList &Vals = VE.getValues();
1593   Type *LastTy = nullptr;
1594   for (unsigned i = FirstVal; i != LastVal; ++i) {
1595     const Value *V = Vals[i].first;
1596     // If we need to switch types, do so now.
1597     if (V->getType() != LastTy) {
1598       LastTy = V->getType();
1599       Record.push_back(VE.getTypeID(LastTy));
1600       Stream.EmitRecord(bitc::CST_CODE_SETTYPE, Record,
1601                         CONSTANTS_SETTYPE_ABBREV);
1602       Record.clear();
1603     }
1604 
1605     if (const InlineAsm *IA = dyn_cast<InlineAsm>(V)) {
1606       Record.push_back(unsigned(IA->hasSideEffects()) |
1607                        unsigned(IA->isAlignStack()) << 1 |
1608                        unsigned(IA->getDialect()&1) << 2);
1609 
1610       // Add the asm string.
1611       const std::string &AsmStr = IA->getAsmString();
1612       Record.push_back(AsmStr.size());
1613       Record.append(AsmStr.begin(), AsmStr.end());
1614 
1615       // Add the constraint string.
1616       const std::string &ConstraintStr = IA->getConstraintString();
1617       Record.push_back(ConstraintStr.size());
1618       Record.append(ConstraintStr.begin(), ConstraintStr.end());
1619       Stream.EmitRecord(bitc::CST_CODE_INLINEASM, Record);
1620       Record.clear();
1621       continue;
1622     }
1623     const Constant *C = cast<Constant>(V);
1624     unsigned Code = -1U;
1625     unsigned AbbrevToUse = 0;
1626     if (C->isNullValue()) {
1627       Code = bitc::CST_CODE_NULL;
1628     } else if (isa<UndefValue>(C)) {
1629       Code = bitc::CST_CODE_UNDEF;
1630     } else if (const ConstantInt *IV = dyn_cast<ConstantInt>(C)) {
1631       if (IV->getBitWidth() <= 64) {
1632         uint64_t V = IV->getSExtValue();
1633         emitSignedInt64(Record, V);
1634         Code = bitc::CST_CODE_INTEGER;
1635         AbbrevToUse = CONSTANTS_INTEGER_ABBREV;
1636       } else {                             // Wide integers, > 64 bits in size.
1637         // We have an arbitrary precision integer value to write whose
1638         // bit width is > 64. However, in canonical unsigned integer
1639         // format it is likely that the high bits are going to be zero.
1640         // So, we only write the number of active words.
1641         unsigned NWords = IV->getValue().getActiveWords();
1642         const uint64_t *RawWords = IV->getValue().getRawData();
1643         for (unsigned i = 0; i != NWords; ++i) {
1644           emitSignedInt64(Record, RawWords[i]);
1645         }
1646         Code = bitc::CST_CODE_WIDE_INTEGER;
1647       }
1648     } else if (const ConstantFP *CFP = dyn_cast<ConstantFP>(C)) {
1649       Code = bitc::CST_CODE_FLOAT;
1650       Type *Ty = CFP->getType();
1651       if (Ty->isHalfTy() || Ty->isFloatTy() || Ty->isDoubleTy()) {
1652         Record.push_back(CFP->getValueAPF().bitcastToAPInt().getZExtValue());
1653       } else if (Ty->isX86_FP80Ty()) {
1654         // api needed to prevent premature destruction
1655         // bits are not in the same order as a normal i80 APInt, compensate.
1656         APInt api = CFP->getValueAPF().bitcastToAPInt();
1657         const uint64_t *p = api.getRawData();
1658         Record.push_back((p[1] << 48) | (p[0] >> 16));
1659         Record.push_back(p[0] & 0xffffLL);
1660       } else if (Ty->isFP128Ty() || Ty->isPPC_FP128Ty()) {
1661         APInt api = CFP->getValueAPF().bitcastToAPInt();
1662         const uint64_t *p = api.getRawData();
1663         Record.push_back(p[0]);
1664         Record.push_back(p[1]);
1665       } else {
1666         assert (0 && "Unknown FP type!");
1667       }
1668     } else if (isa<ConstantDataSequential>(C) &&
1669                cast<ConstantDataSequential>(C)->isString()) {
1670       const ConstantDataSequential *Str = cast<ConstantDataSequential>(C);
1671       // Emit constant strings specially.
1672       unsigned NumElts = Str->getNumElements();
1673       // If this is a null-terminated string, use the denser CSTRING encoding.
1674       if (Str->isCString()) {
1675         Code = bitc::CST_CODE_CSTRING;
1676         --NumElts;  // Don't encode the null, which isn't allowed by char6.
1677       } else {
1678         Code = bitc::CST_CODE_STRING;
1679         AbbrevToUse = String8Abbrev;
1680       }
1681       bool isCStr7 = Code == bitc::CST_CODE_CSTRING;
1682       bool isCStrChar6 = Code == bitc::CST_CODE_CSTRING;
1683       for (unsigned i = 0; i != NumElts; ++i) {
1684         unsigned char V = Str->getElementAsInteger(i);
1685         Record.push_back(V);
1686         isCStr7 &= (V & 128) == 0;
1687         if (isCStrChar6)
1688           isCStrChar6 = BitCodeAbbrevOp::isChar6(V);
1689       }
1690 
1691       if (isCStrChar6)
1692         AbbrevToUse = CString6Abbrev;
1693       else if (isCStr7)
1694         AbbrevToUse = CString7Abbrev;
1695     } else if (const ConstantDataSequential *CDS =
1696                   dyn_cast<ConstantDataSequential>(C)) {
1697       Code = bitc::CST_CODE_DATA;
1698       Type *EltTy = CDS->getType()->getElementType();
1699       if (isa<IntegerType>(EltTy)) {
1700         for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i)
1701           Record.push_back(CDS->getElementAsInteger(i));
1702       } else {
1703         for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i)
1704           Record.push_back(
1705               CDS->getElementAsAPFloat(i).bitcastToAPInt().getLimitedValue());
1706       }
1707     } else if (isa<ConstantArray>(C) || isa<ConstantStruct>(C) ||
1708                isa<ConstantVector>(C)) {
1709       Code = bitc::CST_CODE_AGGREGATE;
1710       for (const Value *Op : C->operands())
1711         Record.push_back(VE.getValueID(Op));
1712       AbbrevToUse = AggregateAbbrev;
1713     } else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
1714       switch (CE->getOpcode()) {
1715       default:
1716         if (Instruction::isCast(CE->getOpcode())) {
1717           Code = bitc::CST_CODE_CE_CAST;
1718           Record.push_back(GetEncodedCastOpcode(CE->getOpcode()));
1719           Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
1720           Record.push_back(VE.getValueID(C->getOperand(0)));
1721           AbbrevToUse = CONSTANTS_CE_CAST_Abbrev;
1722         } else {
1723           assert(CE->getNumOperands() == 2 && "Unknown constant expr!");
1724           Code = bitc::CST_CODE_CE_BINOP;
1725           Record.push_back(GetEncodedBinaryOpcode(CE->getOpcode()));
1726           Record.push_back(VE.getValueID(C->getOperand(0)));
1727           Record.push_back(VE.getValueID(C->getOperand(1)));
1728           uint64_t Flags = GetOptimizationFlags(CE);
1729           if (Flags != 0)
1730             Record.push_back(Flags);
1731         }
1732         break;
1733       case Instruction::GetElementPtr: {
1734         Code = bitc::CST_CODE_CE_GEP;
1735         const auto *GO = cast<GEPOperator>(C);
1736         if (GO->isInBounds())
1737           Code = bitc::CST_CODE_CE_INBOUNDS_GEP;
1738         Record.push_back(VE.getTypeID(GO->getSourceElementType()));
1739         for (unsigned i = 0, e = CE->getNumOperands(); i != e; ++i) {
1740           Record.push_back(VE.getTypeID(C->getOperand(i)->getType()));
1741           Record.push_back(VE.getValueID(C->getOperand(i)));
1742         }
1743         break;
1744       }
1745       case Instruction::Select:
1746         Code = bitc::CST_CODE_CE_SELECT;
1747         Record.push_back(VE.getValueID(C->getOperand(0)));
1748         Record.push_back(VE.getValueID(C->getOperand(1)));
1749         Record.push_back(VE.getValueID(C->getOperand(2)));
1750         break;
1751       case Instruction::ExtractElement:
1752         Code = bitc::CST_CODE_CE_EXTRACTELT;
1753         Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
1754         Record.push_back(VE.getValueID(C->getOperand(0)));
1755         Record.push_back(VE.getTypeID(C->getOperand(1)->getType()));
1756         Record.push_back(VE.getValueID(C->getOperand(1)));
1757         break;
1758       case Instruction::InsertElement:
1759         Code = bitc::CST_CODE_CE_INSERTELT;
1760         Record.push_back(VE.getValueID(C->getOperand(0)));
1761         Record.push_back(VE.getValueID(C->getOperand(1)));
1762         Record.push_back(VE.getTypeID(C->getOperand(2)->getType()));
1763         Record.push_back(VE.getValueID(C->getOperand(2)));
1764         break;
1765       case Instruction::ShuffleVector:
1766         // If the return type and argument types are the same, this is a
1767         // standard shufflevector instruction.  If the types are different,
1768         // then the shuffle is widening or truncating the input vectors, and
1769         // the argument type must also be encoded.
1770         if (C->getType() == C->getOperand(0)->getType()) {
1771           Code = bitc::CST_CODE_CE_SHUFFLEVEC;
1772         } else {
1773           Code = bitc::CST_CODE_CE_SHUFVEC_EX;
1774           Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
1775         }
1776         Record.push_back(VE.getValueID(C->getOperand(0)));
1777         Record.push_back(VE.getValueID(C->getOperand(1)));
1778         Record.push_back(VE.getValueID(C->getOperand(2)));
1779         break;
1780       case Instruction::ICmp:
1781       case Instruction::FCmp:
1782         Code = bitc::CST_CODE_CE_CMP;
1783         Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
1784         Record.push_back(VE.getValueID(C->getOperand(0)));
1785         Record.push_back(VE.getValueID(C->getOperand(1)));
1786         Record.push_back(CE->getPredicate());
1787         break;
1788       }
1789     } else if (const BlockAddress *BA = dyn_cast<BlockAddress>(C)) {
1790       Code = bitc::CST_CODE_BLOCKADDRESS;
1791       Record.push_back(VE.getTypeID(BA->getFunction()->getType()));
1792       Record.push_back(VE.getValueID(BA->getFunction()));
1793       Record.push_back(VE.getGlobalBasicBlockID(BA->getBasicBlock()));
1794     } else {
1795 #ifndef NDEBUG
1796       C->dump();
1797 #endif
1798       llvm_unreachable("Unknown constant!");
1799     }
1800     Stream.EmitRecord(Code, Record, AbbrevToUse);
1801     Record.clear();
1802   }
1803 
1804   Stream.ExitBlock();
1805 }
1806 
1807 static void WriteModuleConstants(const ValueEnumerator &VE,
1808                                  BitstreamWriter &Stream) {
1809   const ValueEnumerator::ValueList &Vals = VE.getValues();
1810 
1811   // Find the first constant to emit, which is the first non-globalvalue value.
1812   // We know globalvalues have been emitted by WriteModuleInfo.
1813   for (unsigned i = 0, e = Vals.size(); i != e; ++i) {
1814     if (!isa<GlobalValue>(Vals[i].first)) {
1815       WriteConstants(i, Vals.size(), VE, Stream, true);
1816       return;
1817     }
1818   }
1819 }
1820 
1821 /// PushValueAndType - The file has to encode both the value and type id for
1822 /// many values, because we need to know what type to create for forward
1823 /// references.  However, most operands are not forward references, so this type
1824 /// field is not needed.
1825 ///
1826 /// This function adds V's value ID to Vals.  If the value ID is higher than the
1827 /// instruction ID, then it is a forward reference, and it also includes the
1828 /// type ID.  The value ID that is written is encoded relative to the InstID.
1829 static bool PushValueAndType(const Value *V, unsigned InstID,
1830                              SmallVectorImpl<unsigned> &Vals,
1831                              ValueEnumerator &VE) {
1832   unsigned ValID = VE.getValueID(V);
1833   // Make encoding relative to the InstID.
1834   Vals.push_back(InstID - ValID);
1835   if (ValID >= InstID) {
1836     Vals.push_back(VE.getTypeID(V->getType()));
1837     return true;
1838   }
1839   return false;
1840 }
1841 
1842 static void WriteOperandBundles(BitstreamWriter &Stream, ImmutableCallSite CS,
1843                                 unsigned InstID, ValueEnumerator &VE) {
1844   SmallVector<unsigned, 64> Record;
1845   LLVMContext &C = CS.getInstruction()->getContext();
1846 
1847   for (unsigned i = 0, e = CS.getNumOperandBundles(); i != e; ++i) {
1848     const auto &Bundle = CS.getOperandBundleAt(i);
1849     Record.push_back(C.getOperandBundleTagID(Bundle.getTagName()));
1850 
1851     for (auto &Input : Bundle.Inputs)
1852       PushValueAndType(Input, InstID, Record, VE);
1853 
1854     Stream.EmitRecord(bitc::FUNC_CODE_OPERAND_BUNDLE, Record);
1855     Record.clear();
1856   }
1857 }
1858 
1859 /// pushValue - Like PushValueAndType, but where the type of the value is
1860 /// omitted (perhaps it was already encoded in an earlier operand).
1861 static void pushValue(const Value *V, unsigned InstID,
1862                       SmallVectorImpl<unsigned> &Vals,
1863                       ValueEnumerator &VE) {
1864   unsigned ValID = VE.getValueID(V);
1865   Vals.push_back(InstID - ValID);
1866 }
1867 
1868 static void pushValueSigned(const Value *V, unsigned InstID,
1869                             SmallVectorImpl<uint64_t> &Vals,
1870                             ValueEnumerator &VE) {
1871   unsigned ValID = VE.getValueID(V);
1872   int64_t diff = ((int32_t)InstID - (int32_t)ValID);
1873   emitSignedInt64(Vals, diff);
1874 }
1875 
1876 /// WriteInstruction - Emit an instruction to the specified stream.
1877 static void WriteInstruction(const Instruction &I, unsigned InstID,
1878                              ValueEnumerator &VE, BitstreamWriter &Stream,
1879                              SmallVectorImpl<unsigned> &Vals) {
1880   unsigned Code = 0;
1881   unsigned AbbrevToUse = 0;
1882   VE.setInstructionID(&I);
1883   switch (I.getOpcode()) {
1884   default:
1885     if (Instruction::isCast(I.getOpcode())) {
1886       Code = bitc::FUNC_CODE_INST_CAST;
1887       if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
1888         AbbrevToUse = FUNCTION_INST_CAST_ABBREV;
1889       Vals.push_back(VE.getTypeID(I.getType()));
1890       Vals.push_back(GetEncodedCastOpcode(I.getOpcode()));
1891     } else {
1892       assert(isa<BinaryOperator>(I) && "Unknown instruction!");
1893       Code = bitc::FUNC_CODE_INST_BINOP;
1894       if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
1895         AbbrevToUse = FUNCTION_INST_BINOP_ABBREV;
1896       pushValue(I.getOperand(1), InstID, Vals, VE);
1897       Vals.push_back(GetEncodedBinaryOpcode(I.getOpcode()));
1898       uint64_t Flags = GetOptimizationFlags(&I);
1899       if (Flags != 0) {
1900         if (AbbrevToUse == FUNCTION_INST_BINOP_ABBREV)
1901           AbbrevToUse = FUNCTION_INST_BINOP_FLAGS_ABBREV;
1902         Vals.push_back(Flags);
1903       }
1904     }
1905     break;
1906 
1907   case Instruction::GetElementPtr: {
1908     Code = bitc::FUNC_CODE_INST_GEP;
1909     AbbrevToUse = FUNCTION_INST_GEP_ABBREV;
1910     auto &GEPInst = cast<GetElementPtrInst>(I);
1911     Vals.push_back(GEPInst.isInBounds());
1912     Vals.push_back(VE.getTypeID(GEPInst.getSourceElementType()));
1913     for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
1914       PushValueAndType(I.getOperand(i), InstID, Vals, VE);
1915     break;
1916   }
1917   case Instruction::ExtractValue: {
1918     Code = bitc::FUNC_CODE_INST_EXTRACTVAL;
1919     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1920     const ExtractValueInst *EVI = cast<ExtractValueInst>(&I);
1921     Vals.append(EVI->idx_begin(), EVI->idx_end());
1922     break;
1923   }
1924   case Instruction::InsertValue: {
1925     Code = bitc::FUNC_CODE_INST_INSERTVAL;
1926     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1927     PushValueAndType(I.getOperand(1), InstID, Vals, VE);
1928     const InsertValueInst *IVI = cast<InsertValueInst>(&I);
1929     Vals.append(IVI->idx_begin(), IVI->idx_end());
1930     break;
1931   }
1932   case Instruction::Select:
1933     Code = bitc::FUNC_CODE_INST_VSELECT;
1934     PushValueAndType(I.getOperand(1), InstID, Vals, VE);
1935     pushValue(I.getOperand(2), InstID, Vals, VE);
1936     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1937     break;
1938   case Instruction::ExtractElement:
1939     Code = bitc::FUNC_CODE_INST_EXTRACTELT;
1940     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1941     PushValueAndType(I.getOperand(1), InstID, Vals, VE);
1942     break;
1943   case Instruction::InsertElement:
1944     Code = bitc::FUNC_CODE_INST_INSERTELT;
1945     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1946     pushValue(I.getOperand(1), InstID, Vals, VE);
1947     PushValueAndType(I.getOperand(2), InstID, Vals, VE);
1948     break;
1949   case Instruction::ShuffleVector:
1950     Code = bitc::FUNC_CODE_INST_SHUFFLEVEC;
1951     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1952     pushValue(I.getOperand(1), InstID, Vals, VE);
1953     pushValue(I.getOperand(2), InstID, Vals, VE);
1954     break;
1955   case Instruction::ICmp:
1956   case Instruction::FCmp: {
1957     // compare returning Int1Ty or vector of Int1Ty
1958     Code = bitc::FUNC_CODE_INST_CMP2;
1959     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1960     pushValue(I.getOperand(1), InstID, Vals, VE);
1961     Vals.push_back(cast<CmpInst>(I).getPredicate());
1962     uint64_t Flags = GetOptimizationFlags(&I);
1963     if (Flags != 0)
1964       Vals.push_back(Flags);
1965     break;
1966   }
1967 
1968   case Instruction::Ret:
1969     {
1970       Code = bitc::FUNC_CODE_INST_RET;
1971       unsigned NumOperands = I.getNumOperands();
1972       if (NumOperands == 0)
1973         AbbrevToUse = FUNCTION_INST_RET_VOID_ABBREV;
1974       else if (NumOperands == 1) {
1975         if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
1976           AbbrevToUse = FUNCTION_INST_RET_VAL_ABBREV;
1977       } else {
1978         for (unsigned i = 0, e = NumOperands; i != e; ++i)
1979           PushValueAndType(I.getOperand(i), InstID, Vals, VE);
1980       }
1981     }
1982     break;
1983   case Instruction::Br:
1984     {
1985       Code = bitc::FUNC_CODE_INST_BR;
1986       const BranchInst &II = cast<BranchInst>(I);
1987       Vals.push_back(VE.getValueID(II.getSuccessor(0)));
1988       if (II.isConditional()) {
1989         Vals.push_back(VE.getValueID(II.getSuccessor(1)));
1990         pushValue(II.getCondition(), InstID, Vals, VE);
1991       }
1992     }
1993     break;
1994   case Instruction::Switch:
1995     {
1996       Code = bitc::FUNC_CODE_INST_SWITCH;
1997       const SwitchInst &SI = cast<SwitchInst>(I);
1998       Vals.push_back(VE.getTypeID(SI.getCondition()->getType()));
1999       pushValue(SI.getCondition(), InstID, Vals, VE);
2000       Vals.push_back(VE.getValueID(SI.getDefaultDest()));
2001       for (SwitchInst::ConstCaseIt Case : SI.cases()) {
2002         Vals.push_back(VE.getValueID(Case.getCaseValue()));
2003         Vals.push_back(VE.getValueID(Case.getCaseSuccessor()));
2004       }
2005     }
2006     break;
2007   case Instruction::IndirectBr:
2008     Code = bitc::FUNC_CODE_INST_INDIRECTBR;
2009     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));
2010     // Encode the address operand as relative, but not the basic blocks.
2011     pushValue(I.getOperand(0), InstID, Vals, VE);
2012     for (unsigned i = 1, e = I.getNumOperands(); i != e; ++i)
2013       Vals.push_back(VE.getValueID(I.getOperand(i)));
2014     break;
2015 
2016   case Instruction::Invoke: {
2017     const InvokeInst *II = cast<InvokeInst>(&I);
2018     const Value *Callee = II->getCalledValue();
2019     FunctionType *FTy = II->getFunctionType();
2020 
2021     if (II->hasOperandBundles())
2022       WriteOperandBundles(Stream, II, InstID, VE);
2023 
2024     Code = bitc::FUNC_CODE_INST_INVOKE;
2025 
2026     Vals.push_back(VE.getAttributeID(II->getAttributes()));
2027     Vals.push_back(II->getCallingConv() | 1 << 13);
2028     Vals.push_back(VE.getValueID(II->getNormalDest()));
2029     Vals.push_back(VE.getValueID(II->getUnwindDest()));
2030     Vals.push_back(VE.getTypeID(FTy));
2031     PushValueAndType(Callee, InstID, Vals, VE);
2032 
2033     // Emit value #'s for the fixed parameters.
2034     for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i)
2035       pushValue(I.getOperand(i), InstID, Vals, VE);  // fixed param.
2036 
2037     // Emit type/value pairs for varargs params.
2038     if (FTy->isVarArg()) {
2039       for (unsigned i = FTy->getNumParams(), e = I.getNumOperands()-3;
2040            i != e; ++i)
2041         PushValueAndType(I.getOperand(i), InstID, Vals, VE); // vararg
2042     }
2043     break;
2044   }
2045   case Instruction::Resume:
2046     Code = bitc::FUNC_CODE_INST_RESUME;
2047     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
2048     break;
2049   case Instruction::CleanupRet: {
2050     Code = bitc::FUNC_CODE_INST_CLEANUPRET;
2051     const auto &CRI = cast<CleanupReturnInst>(I);
2052     pushValue(CRI.getCleanupPad(), InstID, Vals, VE);
2053     if (CRI.hasUnwindDest())
2054       Vals.push_back(VE.getValueID(CRI.getUnwindDest()));
2055     break;
2056   }
2057   case Instruction::CatchRet: {
2058     Code = bitc::FUNC_CODE_INST_CATCHRET;
2059     const auto &CRI = cast<CatchReturnInst>(I);
2060     pushValue(CRI.getCatchPad(), InstID, Vals, VE);
2061     Vals.push_back(VE.getValueID(CRI.getSuccessor()));
2062     break;
2063   }
2064   case Instruction::CleanupPad:
2065   case Instruction::CatchPad: {
2066     const auto &FuncletPad = cast<FuncletPadInst>(I);
2067     Code = isa<CatchPadInst>(FuncletPad) ? bitc::FUNC_CODE_INST_CATCHPAD
2068                                          : bitc::FUNC_CODE_INST_CLEANUPPAD;
2069     pushValue(FuncletPad.getParentPad(), InstID, Vals, VE);
2070 
2071     unsigned NumArgOperands = FuncletPad.getNumArgOperands();
2072     Vals.push_back(NumArgOperands);
2073     for (unsigned Op = 0; Op != NumArgOperands; ++Op)
2074       PushValueAndType(FuncletPad.getArgOperand(Op), InstID, Vals, VE);
2075     break;
2076   }
2077   case Instruction::CatchSwitch: {
2078     Code = bitc::FUNC_CODE_INST_CATCHSWITCH;
2079     const auto &CatchSwitch = cast<CatchSwitchInst>(I);
2080 
2081     pushValue(CatchSwitch.getParentPad(), InstID, Vals, VE);
2082 
2083     unsigned NumHandlers = CatchSwitch.getNumHandlers();
2084     Vals.push_back(NumHandlers);
2085     for (const BasicBlock *CatchPadBB : CatchSwitch.handlers())
2086       Vals.push_back(VE.getValueID(CatchPadBB));
2087 
2088     if (CatchSwitch.hasUnwindDest())
2089       Vals.push_back(VE.getValueID(CatchSwitch.getUnwindDest()));
2090     break;
2091   }
2092   case Instruction::Unreachable:
2093     Code = bitc::FUNC_CODE_INST_UNREACHABLE;
2094     AbbrevToUse = FUNCTION_INST_UNREACHABLE_ABBREV;
2095     break;
2096 
2097   case Instruction::PHI: {
2098     const PHINode &PN = cast<PHINode>(I);
2099     Code = bitc::FUNC_CODE_INST_PHI;
2100     // With the newer instruction encoding, forward references could give
2101     // negative valued IDs.  This is most common for PHIs, so we use
2102     // signed VBRs.
2103     SmallVector<uint64_t, 128> Vals64;
2104     Vals64.push_back(VE.getTypeID(PN.getType()));
2105     for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) {
2106       pushValueSigned(PN.getIncomingValue(i), InstID, Vals64, VE);
2107       Vals64.push_back(VE.getValueID(PN.getIncomingBlock(i)));
2108     }
2109     // Emit a Vals64 vector and exit.
2110     Stream.EmitRecord(Code, Vals64, AbbrevToUse);
2111     Vals64.clear();
2112     return;
2113   }
2114 
2115   case Instruction::LandingPad: {
2116     const LandingPadInst &LP = cast<LandingPadInst>(I);
2117     Code = bitc::FUNC_CODE_INST_LANDINGPAD;
2118     Vals.push_back(VE.getTypeID(LP.getType()));
2119     Vals.push_back(LP.isCleanup());
2120     Vals.push_back(LP.getNumClauses());
2121     for (unsigned I = 0, E = LP.getNumClauses(); I != E; ++I) {
2122       if (LP.isCatch(I))
2123         Vals.push_back(LandingPadInst::Catch);
2124       else
2125         Vals.push_back(LandingPadInst::Filter);
2126       PushValueAndType(LP.getClause(I), InstID, Vals, VE);
2127     }
2128     break;
2129   }
2130 
2131   case Instruction::Alloca: {
2132     Code = bitc::FUNC_CODE_INST_ALLOCA;
2133     const AllocaInst &AI = cast<AllocaInst>(I);
2134     Vals.push_back(VE.getTypeID(AI.getAllocatedType()));
2135     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));
2136     Vals.push_back(VE.getValueID(I.getOperand(0))); // size.
2137     unsigned AlignRecord = Log2_32(AI.getAlignment()) + 1;
2138     assert(Log2_32(Value::MaximumAlignment) + 1 < 1 << 5 &&
2139            "not enough bits for maximum alignment");
2140     assert(AlignRecord < 1 << 5 && "alignment greater than 1 << 64");
2141     AlignRecord |= AI.isUsedWithInAlloca() << 5;
2142     AlignRecord |= 1 << 6;
2143     // Reserve bit 7 for SwiftError flag.
2144     // AlignRecord |= AI.isSwiftError() << 7;
2145     Vals.push_back(AlignRecord);
2146     break;
2147   }
2148 
2149   case Instruction::Load:
2150     if (cast<LoadInst>(I).isAtomic()) {
2151       Code = bitc::FUNC_CODE_INST_LOADATOMIC;
2152       PushValueAndType(I.getOperand(0), InstID, Vals, VE);
2153     } else {
2154       Code = bitc::FUNC_CODE_INST_LOAD;
2155       if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))  // ptr
2156         AbbrevToUse = FUNCTION_INST_LOAD_ABBREV;
2157     }
2158     Vals.push_back(VE.getTypeID(I.getType()));
2159     Vals.push_back(Log2_32(cast<LoadInst>(I).getAlignment())+1);
2160     Vals.push_back(cast<LoadInst>(I).isVolatile());
2161     if (cast<LoadInst>(I).isAtomic()) {
2162       Vals.push_back(GetEncodedOrdering(cast<LoadInst>(I).getOrdering()));
2163       Vals.push_back(GetEncodedSynchScope(cast<LoadInst>(I).getSynchScope()));
2164     }
2165     break;
2166   case Instruction::Store:
2167     if (cast<StoreInst>(I).isAtomic())
2168       Code = bitc::FUNC_CODE_INST_STOREATOMIC;
2169     else
2170       Code = bitc::FUNC_CODE_INST_STORE;
2171     PushValueAndType(I.getOperand(1), InstID, Vals, VE);  // ptrty + ptr
2172     PushValueAndType(I.getOperand(0), InstID, Vals, VE);  // valty + val
2173     Vals.push_back(Log2_32(cast<StoreInst>(I).getAlignment())+1);
2174     Vals.push_back(cast<StoreInst>(I).isVolatile());
2175     if (cast<StoreInst>(I).isAtomic()) {
2176       Vals.push_back(GetEncodedOrdering(cast<StoreInst>(I).getOrdering()));
2177       Vals.push_back(GetEncodedSynchScope(cast<StoreInst>(I).getSynchScope()));
2178     }
2179     break;
2180   case Instruction::AtomicCmpXchg:
2181     Code = bitc::FUNC_CODE_INST_CMPXCHG;
2182     PushValueAndType(I.getOperand(0), InstID, Vals, VE);  // ptrty + ptr
2183     PushValueAndType(I.getOperand(1), InstID, Vals, VE);  // cmp.
2184     pushValue(I.getOperand(2), InstID, Vals, VE);         // newval.
2185     Vals.push_back(cast<AtomicCmpXchgInst>(I).isVolatile());
2186     Vals.push_back(GetEncodedOrdering(
2187                      cast<AtomicCmpXchgInst>(I).getSuccessOrdering()));
2188     Vals.push_back(GetEncodedSynchScope(
2189                      cast<AtomicCmpXchgInst>(I).getSynchScope()));
2190     Vals.push_back(GetEncodedOrdering(
2191                      cast<AtomicCmpXchgInst>(I).getFailureOrdering()));
2192     Vals.push_back(cast<AtomicCmpXchgInst>(I).isWeak());
2193     break;
2194   case Instruction::AtomicRMW:
2195     Code = bitc::FUNC_CODE_INST_ATOMICRMW;
2196     PushValueAndType(I.getOperand(0), InstID, Vals, VE);  // ptrty + ptr
2197     pushValue(I.getOperand(1), InstID, Vals, VE);         // val.
2198     Vals.push_back(GetEncodedRMWOperation(
2199                      cast<AtomicRMWInst>(I).getOperation()));
2200     Vals.push_back(cast<AtomicRMWInst>(I).isVolatile());
2201     Vals.push_back(GetEncodedOrdering(cast<AtomicRMWInst>(I).getOrdering()));
2202     Vals.push_back(GetEncodedSynchScope(
2203                      cast<AtomicRMWInst>(I).getSynchScope()));
2204     break;
2205   case Instruction::Fence:
2206     Code = bitc::FUNC_CODE_INST_FENCE;
2207     Vals.push_back(GetEncodedOrdering(cast<FenceInst>(I).getOrdering()));
2208     Vals.push_back(GetEncodedSynchScope(cast<FenceInst>(I).getSynchScope()));
2209     break;
2210   case Instruction::Call: {
2211     const CallInst &CI = cast<CallInst>(I);
2212     FunctionType *FTy = CI.getFunctionType();
2213 
2214     if (CI.hasOperandBundles())
2215       WriteOperandBundles(Stream, &CI, InstID, VE);
2216 
2217     Code = bitc::FUNC_CODE_INST_CALL;
2218 
2219     Vals.push_back(VE.getAttributeID(CI.getAttributes()));
2220 
2221     unsigned Flags = GetOptimizationFlags(&I);
2222     Vals.push_back(CI.getCallingConv() << bitc::CALL_CCONV |
2223                    unsigned(CI.isTailCall()) << bitc::CALL_TAIL |
2224                    unsigned(CI.isMustTailCall()) << bitc::CALL_MUSTTAIL |
2225                    1 << bitc::CALL_EXPLICIT_TYPE |
2226                    unsigned(CI.isNoTailCall()) << bitc::CALL_NOTAIL |
2227                    unsigned(Flags != 0) << bitc::CALL_FMF);
2228     if (Flags != 0)
2229       Vals.push_back(Flags);
2230 
2231     Vals.push_back(VE.getTypeID(FTy));
2232     PushValueAndType(CI.getCalledValue(), InstID, Vals, VE);  // Callee
2233 
2234     // Emit value #'s for the fixed parameters.
2235     for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i) {
2236       // Check for labels (can happen with asm labels).
2237       if (FTy->getParamType(i)->isLabelTy())
2238         Vals.push_back(VE.getValueID(CI.getArgOperand(i)));
2239       else
2240         pushValue(CI.getArgOperand(i), InstID, Vals, VE);  // fixed param.
2241     }
2242 
2243     // Emit type/value pairs for varargs params.
2244     if (FTy->isVarArg()) {
2245       for (unsigned i = FTy->getNumParams(), e = CI.getNumArgOperands();
2246            i != e; ++i)
2247         PushValueAndType(CI.getArgOperand(i), InstID, Vals, VE);  // varargs
2248     }
2249     break;
2250   }
2251   case Instruction::VAArg:
2252     Code = bitc::FUNC_CODE_INST_VAARG;
2253     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));   // valistty
2254     pushValue(I.getOperand(0), InstID, Vals, VE); // valist.
2255     Vals.push_back(VE.getTypeID(I.getType())); // restype.
2256     break;
2257   }
2258 
2259   Stream.EmitRecord(Code, Vals, AbbrevToUse);
2260   Vals.clear();
2261 }
2262 
2263 /// Emit names for globals/functions etc. The VSTOffsetPlaceholder,
2264 /// BitcodeStartBit and ModuleSummaryIndex are only passed for the module-level
2265 /// VST, where we are including a function bitcode index and need to
2266 /// backpatch the VST forward declaration record.
2267 static void WriteValueSymbolTable(
2268     const ValueSymbolTable &VST, const ValueEnumerator &VE,
2269     BitstreamWriter &Stream, uint64_t VSTOffsetPlaceholder = 0,
2270     uint64_t BitcodeStartBit = 0,
2271     DenseMap<const Function *, std::unique_ptr<GlobalValueInfo>>
2272         *FunctionIndex = nullptr) {
2273   if (VST.empty()) {
2274     // WriteValueSymbolTableForwardDecl should have returned early as
2275     // well. Ensure this handling remains in sync by asserting that
2276     // the placeholder offset is not set.
2277     assert(VSTOffsetPlaceholder == 0);
2278     return;
2279   }
2280 
2281   if (VSTOffsetPlaceholder > 0) {
2282     // Get the offset of the VST we are writing, and backpatch it into
2283     // the VST forward declaration record.
2284     uint64_t VSTOffset = Stream.GetCurrentBitNo();
2285     // The BitcodeStartBit was the stream offset of the actual bitcode
2286     // (e.g. excluding any initial darwin header).
2287     VSTOffset -= BitcodeStartBit;
2288     assert((VSTOffset & 31) == 0 && "VST block not 32-bit aligned");
2289     Stream.BackpatchWord(VSTOffsetPlaceholder, VSTOffset / 32);
2290   }
2291 
2292   Stream.EnterSubblock(bitc::VALUE_SYMTAB_BLOCK_ID, 4);
2293 
2294   // For the module-level VST, add abbrev Ids for the VST_CODE_FNENTRY
2295   // records, which are not used in the per-function VSTs.
2296   unsigned FnEntry8BitAbbrev;
2297   unsigned FnEntry7BitAbbrev;
2298   unsigned FnEntry6BitAbbrev;
2299   if (VSTOffsetPlaceholder > 0) {
2300     // 8-bit fixed-width VST_CODE_FNENTRY function strings.
2301     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2302     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_FNENTRY));
2303     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // value id
2304     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // funcoffset
2305     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2306     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
2307     FnEntry8BitAbbrev = Stream.EmitAbbrev(Abbv);
2308 
2309     // 7-bit fixed width VST_CODE_FNENTRY function strings.
2310     Abbv = new BitCodeAbbrev();
2311     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_FNENTRY));
2312     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // value id
2313     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // funcoffset
2314     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2315     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
2316     FnEntry7BitAbbrev = Stream.EmitAbbrev(Abbv);
2317 
2318     // 6-bit char6 VST_CODE_FNENTRY function strings.
2319     Abbv = new BitCodeAbbrev();
2320     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_FNENTRY));
2321     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // value id
2322     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // funcoffset
2323     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2324     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
2325     FnEntry6BitAbbrev = Stream.EmitAbbrev(Abbv);
2326   }
2327 
2328   // FIXME: Set up the abbrev, we know how many values there are!
2329   // FIXME: We know if the type names can use 7-bit ascii.
2330   SmallVector<unsigned, 64> NameVals;
2331 
2332   for (const ValueName &Name : VST) {
2333     // Figure out the encoding to use for the name.
2334     StringEncoding Bits =
2335         getStringEncoding(Name.getKeyData(), Name.getKeyLength());
2336 
2337     unsigned AbbrevToUse = VST_ENTRY_8_ABBREV;
2338     NameVals.push_back(VE.getValueID(Name.getValue()));
2339 
2340     Function *F = dyn_cast<Function>(Name.getValue());
2341     if (!F) {
2342       // If value is an alias, need to get the aliased base object to
2343       // see if it is a function.
2344       auto *GA = dyn_cast<GlobalAlias>(Name.getValue());
2345       if (GA && GA->getBaseObject())
2346         F = dyn_cast<Function>(GA->getBaseObject());
2347     }
2348 
2349     // VST_CODE_ENTRY:   [valueid, namechar x N]
2350     // VST_CODE_FNENTRY: [valueid, funcoffset, namechar x N]
2351     // VST_CODE_BBENTRY: [bbid, namechar x N]
2352     unsigned Code;
2353     if (isa<BasicBlock>(Name.getValue())) {
2354       Code = bitc::VST_CODE_BBENTRY;
2355       if (Bits == SE_Char6)
2356         AbbrevToUse = VST_BBENTRY_6_ABBREV;
2357     } else if (F && !F->isDeclaration()) {
2358       // Must be the module-level VST, where we pass in the Index and
2359       // have a VSTOffsetPlaceholder. The function-level VST should not
2360       // contain any Function symbols.
2361       assert(FunctionIndex);
2362       assert(VSTOffsetPlaceholder > 0);
2363 
2364       // Save the word offset of the function (from the start of the
2365       // actual bitcode written to the stream).
2366       uint64_t BitcodeIndex =
2367           (*FunctionIndex)[F]->bitcodeIndex() - BitcodeStartBit;
2368       assert((BitcodeIndex & 31) == 0 && "function block not 32-bit aligned");
2369       NameVals.push_back(BitcodeIndex / 32);
2370 
2371       Code = bitc::VST_CODE_FNENTRY;
2372       AbbrevToUse = FnEntry8BitAbbrev;
2373       if (Bits == SE_Char6)
2374         AbbrevToUse = FnEntry6BitAbbrev;
2375       else if (Bits == SE_Fixed7)
2376         AbbrevToUse = FnEntry7BitAbbrev;
2377     } else {
2378       Code = bitc::VST_CODE_ENTRY;
2379       if (Bits == SE_Char6)
2380         AbbrevToUse = VST_ENTRY_6_ABBREV;
2381       else if (Bits == SE_Fixed7)
2382         AbbrevToUse = VST_ENTRY_7_ABBREV;
2383     }
2384 
2385     for (const auto P : Name.getKey())
2386       NameVals.push_back((unsigned char)P);
2387 
2388     // Emit the finished record.
2389     Stream.EmitRecord(Code, NameVals, AbbrevToUse);
2390     NameVals.clear();
2391   }
2392   Stream.ExitBlock();
2393 }
2394 
2395 /// Emit function names and summary offsets for the combined index
2396 /// used by ThinLTO.
2397 static void
2398 WriteCombinedValueSymbolTable(const ModuleSummaryIndex &Index,
2399                               BitstreamWriter &Stream,
2400                               std::map<uint64_t, unsigned> &GUIDToValueIdMap,
2401                               uint64_t VSTOffsetPlaceholder) {
2402   assert(VSTOffsetPlaceholder > 0 && "Expected non-zero VSTOffsetPlaceholder");
2403   // Get the offset of the VST we are writing, and backpatch it into
2404   // the VST forward declaration record.
2405   uint64_t VSTOffset = Stream.GetCurrentBitNo();
2406   assert((VSTOffset & 31) == 0 && "VST block not 32-bit aligned");
2407   Stream.BackpatchWord(VSTOffsetPlaceholder, VSTOffset / 32);
2408 
2409   Stream.EnterSubblock(bitc::VALUE_SYMTAB_BLOCK_ID, 4);
2410 
2411   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2412   Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_COMBINED_GVDEFENTRY));
2413   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // valueid
2414   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // sumoffset
2415   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // guid
2416   unsigned DefEntryAbbrev = Stream.EmitAbbrev(Abbv);
2417 
2418   Abbv = new BitCodeAbbrev();
2419   Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_COMBINED_ENTRY));
2420   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // valueid
2421   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // refguid
2422   unsigned EntryAbbrev = Stream.EmitAbbrev(Abbv);
2423 
2424   SmallVector<uint64_t, 64> NameVals;
2425 
2426   for (const auto &FII : Index) {
2427     uint64_t FuncGUID = FII.first;
2428     const auto &VMI = GUIDToValueIdMap.find(FuncGUID);
2429     assert(VMI != GUIDToValueIdMap.end());
2430 
2431     for (const auto &FI : FII.second) {
2432       // VST_CODE_COMBINED_GVDEFENTRY: [valueid, sumoffset, guid]
2433       NameVals.push_back(VMI->second);
2434       NameVals.push_back(FI->bitcodeIndex());
2435       NameVals.push_back(FuncGUID);
2436 
2437       // Emit the finished record.
2438       Stream.EmitRecord(bitc::VST_CODE_COMBINED_GVDEFENTRY, NameVals,
2439                         DefEntryAbbrev);
2440       NameVals.clear();
2441     }
2442     GUIDToValueIdMap.erase(VMI);
2443   }
2444   for (const auto &GVI : GUIDToValueIdMap) {
2445     // VST_CODE_COMBINED_ENTRY: [valueid, refguid]
2446     NameVals.push_back(GVI.second);
2447     NameVals.push_back(GVI.first);
2448 
2449     // Emit the finished record.
2450     Stream.EmitRecord(bitc::VST_CODE_COMBINED_ENTRY, NameVals, EntryAbbrev);
2451     NameVals.clear();
2452   }
2453   Stream.ExitBlock();
2454 }
2455 
2456 static void WriteUseList(ValueEnumerator &VE, UseListOrder &&Order,
2457                          BitstreamWriter &Stream) {
2458   assert(Order.Shuffle.size() >= 2 && "Shuffle too small");
2459   unsigned Code;
2460   if (isa<BasicBlock>(Order.V))
2461     Code = bitc::USELIST_CODE_BB;
2462   else
2463     Code = bitc::USELIST_CODE_DEFAULT;
2464 
2465   SmallVector<uint64_t, 64> Record(Order.Shuffle.begin(), Order.Shuffle.end());
2466   Record.push_back(VE.getValueID(Order.V));
2467   Stream.EmitRecord(Code, Record);
2468 }
2469 
2470 static void WriteUseListBlock(const Function *F, ValueEnumerator &VE,
2471                               BitstreamWriter &Stream) {
2472   assert(VE.shouldPreserveUseListOrder() &&
2473          "Expected to be preserving use-list order");
2474 
2475   auto hasMore = [&]() {
2476     return !VE.UseListOrders.empty() && VE.UseListOrders.back().F == F;
2477   };
2478   if (!hasMore())
2479     // Nothing to do.
2480     return;
2481 
2482   Stream.EnterSubblock(bitc::USELIST_BLOCK_ID, 3);
2483   while (hasMore()) {
2484     WriteUseList(VE, std::move(VE.UseListOrders.back()), Stream);
2485     VE.UseListOrders.pop_back();
2486   }
2487   Stream.ExitBlock();
2488 }
2489 
2490 // Walk through the operands of a given User via worklist iteration and populate
2491 // the set of GlobalValue references encountered. Invoked either on an
2492 // Instruction or a GlobalVariable (which walks its initializer).
2493 static void findRefEdges(const User *CurUser, const ValueEnumerator &VE,
2494                          DenseSet<unsigned> &RefEdges,
2495                          SmallPtrSet<const User *, 8> &Visited) {
2496   SmallVector<const User *, 32> Worklist;
2497   Worklist.push_back(CurUser);
2498 
2499   while (!Worklist.empty()) {
2500     const User *U = Worklist.pop_back_val();
2501 
2502     if (!Visited.insert(U).second)
2503       continue;
2504 
2505     ImmutableCallSite CS(U);
2506 
2507     for (const auto &OI : U->operands()) {
2508       const User *Operand = dyn_cast<User>(OI);
2509       if (!Operand)
2510         continue;
2511       if (isa<BlockAddress>(Operand))
2512         continue;
2513       if (isa<GlobalValue>(Operand)) {
2514         // We have a reference to a global value. This should be added to
2515         // the reference set unless it is a callee. Callees are handled
2516         // specially by WriteFunction and are added to a separate list.
2517         if (!(CS && CS.isCallee(&OI)))
2518           RefEdges.insert(VE.getValueID(Operand));
2519         continue;
2520       }
2521       Worklist.push_back(Operand);
2522     }
2523   }
2524 }
2525 
2526 /// Emit a function body to the module stream.
2527 static void WriteFunction(
2528     const Function &F, const Module *M, ValueEnumerator &VE,
2529     BitstreamWriter &Stream,
2530     DenseMap<const Function *, std::unique_ptr<GlobalValueInfo>> &FunctionIndex,
2531     bool EmitSummaryIndex) {
2532   // Save the bitcode index of the start of this function block for recording
2533   // in the VST.
2534   uint64_t BitcodeIndex = Stream.GetCurrentBitNo();
2535 
2536   bool HasProfileData = F.getEntryCount().hasValue();
2537   std::unique_ptr<BlockFrequencyInfo> BFI;
2538   if (EmitSummaryIndex && HasProfileData) {
2539     Function &Func = const_cast<Function &>(F);
2540     LoopInfo LI{DominatorTree(Func)};
2541     BranchProbabilityInfo BPI{Func, LI};
2542     BFI = llvm::make_unique<BlockFrequencyInfo>(Func, BPI, LI);
2543   }
2544 
2545   Stream.EnterSubblock(bitc::FUNCTION_BLOCK_ID, 4);
2546   VE.incorporateFunction(F);
2547 
2548   SmallVector<unsigned, 64> Vals;
2549 
2550   // Emit the number of basic blocks, so the reader can create them ahead of
2551   // time.
2552   Vals.push_back(VE.getBasicBlocks().size());
2553   Stream.EmitRecord(bitc::FUNC_CODE_DECLAREBLOCKS, Vals);
2554   Vals.clear();
2555 
2556   // If there are function-local constants, emit them now.
2557   unsigned CstStart, CstEnd;
2558   VE.getFunctionConstantRange(CstStart, CstEnd);
2559   WriteConstants(CstStart, CstEnd, VE, Stream, false);
2560 
2561   // If there is function-local metadata, emit it now.
2562   writeFunctionMetadata(F, VE, Stream);
2563 
2564   // Keep a running idea of what the instruction ID is.
2565   unsigned InstID = CstEnd;
2566 
2567   bool NeedsMetadataAttachment = F.hasMetadata();
2568 
2569   DILocation *LastDL = nullptr;
2570   unsigned NumInsts = 0;
2571   // Map from callee ValueId to profile count. Used to accumulate profile
2572   // counts for all static calls to a given callee.
2573   DenseMap<unsigned, CalleeInfo> CallGraphEdges;
2574   DenseSet<unsigned> RefEdges;
2575 
2576   SmallPtrSet<const User *, 8> Visited;
2577   // Finally, emit all the instructions, in order.
2578   for (Function::const_iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
2579     for (BasicBlock::const_iterator I = BB->begin(), E = BB->end();
2580          I != E; ++I) {
2581       WriteInstruction(*I, InstID, VE, Stream, Vals);
2582 
2583       if (!isa<DbgInfoIntrinsic>(I))
2584         ++NumInsts;
2585 
2586       if (!I->getType()->isVoidTy())
2587         ++InstID;
2588 
2589       if (EmitSummaryIndex) {
2590         if (auto CS = ImmutableCallSite(&*I)) {
2591           auto *CalledFunction = CS.getCalledFunction();
2592           if (CalledFunction && CalledFunction->hasName() &&
2593               !CalledFunction->isIntrinsic()) {
2594             auto ScaledCount = BFI ? BFI->getBlockProfileCount(&*BB) : None;
2595             unsigned CalleeId = VE.getValueID(
2596                 M->getValueSymbolTable().lookup(CalledFunction->getName()));
2597             CallGraphEdges[CalleeId] +=
2598                 (ScaledCount ? ScaledCount.getValue() : 0);
2599           }
2600         }
2601         findRefEdges(&*I, VE, RefEdges, Visited);
2602       }
2603 
2604       // If the instruction has metadata, write a metadata attachment later.
2605       NeedsMetadataAttachment |= I->hasMetadataOtherThanDebugLoc();
2606 
2607       // If the instruction has a debug location, emit it.
2608       DILocation *DL = I->getDebugLoc();
2609       if (!DL)
2610         continue;
2611 
2612       if (DL == LastDL) {
2613         // Just repeat the same debug loc as last time.
2614         Stream.EmitRecord(bitc::FUNC_CODE_DEBUG_LOC_AGAIN, Vals);
2615         continue;
2616       }
2617 
2618       Vals.push_back(DL->getLine());
2619       Vals.push_back(DL->getColumn());
2620       Vals.push_back(VE.getMetadataOrNullID(DL->getScope()));
2621       Vals.push_back(VE.getMetadataOrNullID(DL->getInlinedAt()));
2622       Stream.EmitRecord(bitc::FUNC_CODE_DEBUG_LOC, Vals);
2623       Vals.clear();
2624 
2625       LastDL = DL;
2626     }
2627 
2628   std::unique_ptr<FunctionSummary> FuncSummary;
2629   if (EmitSummaryIndex) {
2630     FuncSummary = llvm::make_unique<FunctionSummary>(F.getLinkage(), NumInsts);
2631     FuncSummary->addCallGraphEdges(CallGraphEdges);
2632     FuncSummary->addRefEdges(RefEdges);
2633   }
2634   FunctionIndex[&F] =
2635       llvm::make_unique<GlobalValueInfo>(BitcodeIndex, std::move(FuncSummary));
2636 
2637   // Emit names for all the instructions etc.
2638   WriteValueSymbolTable(F.getValueSymbolTable(), VE, Stream);
2639 
2640   if (NeedsMetadataAttachment)
2641     WriteMetadataAttachment(F, VE, Stream);
2642   if (VE.shouldPreserveUseListOrder())
2643     WriteUseListBlock(&F, VE, Stream);
2644   VE.purgeFunction();
2645   Stream.ExitBlock();
2646 }
2647 
2648 // Emit blockinfo, which defines the standard abbreviations etc.
2649 static void WriteBlockInfo(const ValueEnumerator &VE, BitstreamWriter &Stream) {
2650   // We only want to emit block info records for blocks that have multiple
2651   // instances: CONSTANTS_BLOCK, FUNCTION_BLOCK and VALUE_SYMTAB_BLOCK.
2652   // Other blocks can define their abbrevs inline.
2653   Stream.EnterBlockInfoBlock(2);
2654 
2655   { // 8-bit fixed-width VST_CODE_ENTRY/VST_CODE_BBENTRY strings.
2656     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2657     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 3));
2658     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
2659     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2660     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
2661     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
2662                                    Abbv) != VST_ENTRY_8_ABBREV)
2663       llvm_unreachable("Unexpected abbrev ordering!");
2664   }
2665 
2666   { // 7-bit fixed width VST_CODE_ENTRY strings.
2667     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2668     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
2669     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
2670     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2671     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
2672     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
2673                                    Abbv) != VST_ENTRY_7_ABBREV)
2674       llvm_unreachable("Unexpected abbrev ordering!");
2675   }
2676   { // 6-bit char6 VST_CODE_ENTRY strings.
2677     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2678     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
2679     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
2680     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2681     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
2682     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
2683                                    Abbv) != VST_ENTRY_6_ABBREV)
2684       llvm_unreachable("Unexpected abbrev ordering!");
2685   }
2686   { // 6-bit char6 VST_CODE_BBENTRY strings.
2687     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2688     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_BBENTRY));
2689     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
2690     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2691     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
2692     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
2693                                    Abbv) != VST_BBENTRY_6_ABBREV)
2694       llvm_unreachable("Unexpected abbrev ordering!");
2695   }
2696 
2697 
2698 
2699   { // SETTYPE abbrev for CONSTANTS_BLOCK.
2700     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2701     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_SETTYPE));
2702     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
2703                               VE.computeBitsRequiredForTypeIndicies()));
2704     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
2705                                    Abbv) != CONSTANTS_SETTYPE_ABBREV)
2706       llvm_unreachable("Unexpected abbrev ordering!");
2707   }
2708 
2709   { // INTEGER abbrev for CONSTANTS_BLOCK.
2710     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2711     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_INTEGER));
2712     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
2713     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
2714                                    Abbv) != CONSTANTS_INTEGER_ABBREV)
2715       llvm_unreachable("Unexpected abbrev ordering!");
2716   }
2717 
2718   { // CE_CAST abbrev for CONSTANTS_BLOCK.
2719     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2720     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CE_CAST));
2721     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // cast opc
2722     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // typeid
2723                               VE.computeBitsRequiredForTypeIndicies()));
2724     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));    // value id
2725 
2726     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
2727                                    Abbv) != CONSTANTS_CE_CAST_Abbrev)
2728       llvm_unreachable("Unexpected abbrev ordering!");
2729   }
2730   { // NULL abbrev for CONSTANTS_BLOCK.
2731     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2732     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_NULL));
2733     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
2734                                    Abbv) != CONSTANTS_NULL_Abbrev)
2735       llvm_unreachable("Unexpected abbrev ordering!");
2736   }
2737 
2738   // FIXME: This should only use space for first class types!
2739 
2740   { // INST_LOAD abbrev for FUNCTION_BLOCK.
2741     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2742     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_LOAD));
2743     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Ptr
2744     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,    // dest ty
2745                               VE.computeBitsRequiredForTypeIndicies()));
2746     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4)); // Align
2747     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // volatile
2748     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
2749                                    Abbv) != FUNCTION_INST_LOAD_ABBREV)
2750       llvm_unreachable("Unexpected abbrev ordering!");
2751   }
2752   { // INST_BINOP abbrev for FUNCTION_BLOCK.
2753     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2754     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
2755     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
2756     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
2757     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
2758     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
2759                                    Abbv) != FUNCTION_INST_BINOP_ABBREV)
2760       llvm_unreachable("Unexpected abbrev ordering!");
2761   }
2762   { // INST_BINOP_FLAGS abbrev for FUNCTION_BLOCK.
2763     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2764     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
2765     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
2766     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
2767     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
2768     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7)); // flags
2769     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
2770                                    Abbv) != FUNCTION_INST_BINOP_FLAGS_ABBREV)
2771       llvm_unreachable("Unexpected abbrev ordering!");
2772   }
2773   { // INST_CAST abbrev for FUNCTION_BLOCK.
2774     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2775     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_CAST));
2776     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));    // OpVal
2777     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // dest ty
2778                               VE.computeBitsRequiredForTypeIndicies()));
2779     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // opc
2780     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
2781                                    Abbv) != FUNCTION_INST_CAST_ABBREV)
2782       llvm_unreachable("Unexpected abbrev ordering!");
2783   }
2784 
2785   { // INST_RET abbrev for FUNCTION_BLOCK.
2786     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2787     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
2788     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
2789                                    Abbv) != FUNCTION_INST_RET_VOID_ABBREV)
2790       llvm_unreachable("Unexpected abbrev ordering!");
2791   }
2792   { // INST_RET abbrev for FUNCTION_BLOCK.
2793     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2794     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
2795     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // ValID
2796     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
2797                                    Abbv) != FUNCTION_INST_RET_VAL_ABBREV)
2798       llvm_unreachable("Unexpected abbrev ordering!");
2799   }
2800   { // INST_UNREACHABLE abbrev for FUNCTION_BLOCK.
2801     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2802     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_UNREACHABLE));
2803     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
2804                                    Abbv) != FUNCTION_INST_UNREACHABLE_ABBREV)
2805       llvm_unreachable("Unexpected abbrev ordering!");
2806   }
2807   {
2808     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2809     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_GEP));
2810     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
2811     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, // dest ty
2812                               Log2_32_Ceil(VE.getTypes().size() + 1)));
2813     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2814     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
2815     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
2816         FUNCTION_INST_GEP_ABBREV)
2817       llvm_unreachable("Unexpected abbrev ordering!");
2818   }
2819 
2820   Stream.ExitBlock();
2821 }
2822 
2823 /// Write the module path strings, currently only used when generating
2824 /// a combined index file.
2825 static void WriteModStrings(const ModuleSummaryIndex &I,
2826                             BitstreamWriter &Stream) {
2827   Stream.EnterSubblock(bitc::MODULE_STRTAB_BLOCK_ID, 3);
2828 
2829   // TODO: See which abbrev sizes we actually need to emit
2830 
2831   // 8-bit fixed-width MST_ENTRY strings.
2832   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2833   Abbv->Add(BitCodeAbbrevOp(bitc::MST_CODE_ENTRY));
2834   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
2835   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2836   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
2837   unsigned Abbrev8Bit = Stream.EmitAbbrev(Abbv);
2838 
2839   // 7-bit fixed width MST_ENTRY strings.
2840   Abbv = new BitCodeAbbrev();
2841   Abbv->Add(BitCodeAbbrevOp(bitc::MST_CODE_ENTRY));
2842   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
2843   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2844   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
2845   unsigned Abbrev7Bit = Stream.EmitAbbrev(Abbv);
2846 
2847   // 6-bit char6 MST_ENTRY strings.
2848   Abbv = new BitCodeAbbrev();
2849   Abbv->Add(BitCodeAbbrevOp(bitc::MST_CODE_ENTRY));
2850   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
2851   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2852   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
2853   unsigned Abbrev6Bit = Stream.EmitAbbrev(Abbv);
2854 
2855   SmallVector<unsigned, 64> NameVals;
2856   for (const StringMapEntry<uint64_t> &MPSE : I.modulePaths()) {
2857     StringEncoding Bits =
2858         getStringEncoding(MPSE.getKey().data(), MPSE.getKey().size());
2859     unsigned AbbrevToUse = Abbrev8Bit;
2860     if (Bits == SE_Char6)
2861       AbbrevToUse = Abbrev6Bit;
2862     else if (Bits == SE_Fixed7)
2863       AbbrevToUse = Abbrev7Bit;
2864 
2865     NameVals.push_back(MPSE.getValue());
2866 
2867     for (const auto P : MPSE.getKey())
2868       NameVals.push_back((unsigned char)P);
2869 
2870     // Emit the finished record.
2871     Stream.EmitRecord(bitc::MST_CODE_ENTRY, NameVals, AbbrevToUse);
2872     NameVals.clear();
2873   }
2874   Stream.ExitBlock();
2875 }
2876 
2877 // Helper to emit a single function summary record.
2878 static void WritePerModuleFunctionSummaryRecord(
2879     SmallVector<uint64_t, 64> &NameVals, FunctionSummary *FS, unsigned ValueID,
2880     unsigned FSCallsAbbrev, unsigned FSCallsProfileAbbrev,
2881     BitstreamWriter &Stream, const Function &F) {
2882   assert(FS);
2883   NameVals.push_back(ValueID);
2884   NameVals.push_back(getEncodedLinkage(FS->linkage()));
2885   NameVals.push_back(FS->instCount());
2886   NameVals.push_back(FS->refs().size());
2887 
2888   for (auto &RI : FS->refs())
2889     NameVals.push_back(RI);
2890 
2891   bool HasProfileData = F.getEntryCount().hasValue();
2892   for (auto &ECI : FS->calls()) {
2893     NameVals.push_back(ECI.first);
2894     assert(ECI.second.CallsiteCount > 0 && "Expected at least one callsite");
2895     NameVals.push_back(ECI.second.CallsiteCount);
2896     if (HasProfileData)
2897       NameVals.push_back(ECI.second.ProfileCount);
2898   }
2899 
2900   unsigned FSAbbrev = (HasProfileData ? FSCallsProfileAbbrev : FSCallsAbbrev);
2901   unsigned Code =
2902       (HasProfileData ? bitc::FS_PERMODULE_PROFILE : bitc::FS_PERMODULE);
2903 
2904   // Emit the finished record.
2905   Stream.EmitRecord(Code, NameVals, FSAbbrev);
2906   NameVals.clear();
2907 }
2908 
2909 // Collect the global value references in the given variable's initializer,
2910 // and emit them in a summary record.
2911 static void WriteModuleLevelReferences(const GlobalVariable &V,
2912                                        const ValueEnumerator &VE,
2913                                        SmallVector<uint64_t, 64> &NameVals,
2914                                        unsigned FSModRefsAbbrev,
2915                                        BitstreamWriter &Stream) {
2916   // Only interested in recording variable defs in the summary.
2917   if (V.isDeclaration())
2918     return;
2919   DenseSet<unsigned> RefEdges;
2920   SmallPtrSet<const User *, 8> Visited;
2921   findRefEdges(&V, VE, RefEdges, Visited);
2922   NameVals.push_back(VE.getValueID(&V));
2923   NameVals.push_back(getEncodedLinkage(V.getLinkage()));
2924   for (auto RefId : RefEdges) {
2925     NameVals.push_back(RefId);
2926   }
2927   Stream.EmitRecord(bitc::FS_PERMODULE_GLOBALVAR_INIT_REFS, NameVals,
2928                     FSModRefsAbbrev);
2929   NameVals.clear();
2930 }
2931 
2932 /// Emit the per-module summary section alongside the rest of
2933 /// the module's bitcode.
2934 static void WritePerModuleGlobalValueSummary(
2935     DenseMap<const Function *, std::unique_ptr<GlobalValueInfo>> &FunctionIndex,
2936     const Module *M, const ValueEnumerator &VE, BitstreamWriter &Stream) {
2937   if (M->empty())
2938     return;
2939 
2940   Stream.EnterSubblock(bitc::GLOBALVAL_SUMMARY_BLOCK_ID, 3);
2941 
2942   // Abbrev for FS_PERMODULE.
2943   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2944   Abbv->Add(BitCodeAbbrevOp(bitc::FS_PERMODULE));
2945   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
2946   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 5)); // linkage
2947   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
2948   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
2949   // numrefs x valueid, n x (valueid, callsitecount)
2950   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2951   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
2952   unsigned FSCallsAbbrev = Stream.EmitAbbrev(Abbv);
2953 
2954   // Abbrev for FS_PERMODULE_PROFILE.
2955   Abbv = new BitCodeAbbrev();
2956   Abbv->Add(BitCodeAbbrevOp(bitc::FS_PERMODULE_PROFILE));
2957   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
2958   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 5)); // linkage
2959   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
2960   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
2961   // numrefs x valueid, n x (valueid, callsitecount, profilecount)
2962   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2963   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
2964   unsigned FSCallsProfileAbbrev = Stream.EmitAbbrev(Abbv);
2965 
2966   // Abbrev for FS_PERMODULE_GLOBALVAR_INIT_REFS.
2967   Abbv = new BitCodeAbbrev();
2968   Abbv->Add(BitCodeAbbrevOp(bitc::FS_PERMODULE_GLOBALVAR_INIT_REFS));
2969   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // valueid
2970   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 5)); // linkage
2971   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));  // valueids
2972   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
2973   unsigned FSModRefsAbbrev = Stream.EmitAbbrev(Abbv);
2974 
2975   SmallVector<uint64_t, 64> NameVals;
2976   // Iterate over the list of functions instead of the FunctionIndex map to
2977   // ensure the ordering is stable.
2978   for (const Function &F : *M) {
2979     if (F.isDeclaration())
2980       continue;
2981     // Skip anonymous functions. We will emit a function summary for
2982     // any aliases below.
2983     if (!F.hasName())
2984       continue;
2985 
2986     assert(FunctionIndex.count(&F) == 1);
2987 
2988     WritePerModuleFunctionSummaryRecord(
2989         NameVals, cast<FunctionSummary>(FunctionIndex[&F]->summary()),
2990         VE.getValueID(M->getValueSymbolTable().lookup(F.getName())),
2991         FSCallsAbbrev, FSCallsProfileAbbrev, Stream, F);
2992   }
2993 
2994   for (const GlobalAlias &A : M->aliases()) {
2995     if (!A.getBaseObject())
2996       continue;
2997     const Function *F = dyn_cast<Function>(A.getBaseObject());
2998     if (!F || F->isDeclaration())
2999       continue;
3000 
3001     assert(FunctionIndex.count(F) == 1);
3002     FunctionSummary *FS =
3003         cast<FunctionSummary>(FunctionIndex[F]->summary());
3004     // Add the alias to the reference list of aliasee function.
3005     FS->addRefEdge(
3006         VE.getValueID(M->getValueSymbolTable().lookup(A.getName())));
3007     WritePerModuleFunctionSummaryRecord(
3008         NameVals, FS,
3009         VE.getValueID(M->getValueSymbolTable().lookup(A.getName())),
3010         FSCallsAbbrev, FSCallsProfileAbbrev, Stream, *F);
3011   }
3012 
3013   // Capture references from GlobalVariable initializers, which are outside
3014   // of a function scope.
3015   for (const GlobalVariable &G : M->globals())
3016     WriteModuleLevelReferences(G, VE, NameVals, FSModRefsAbbrev, Stream);
3017   for (const GlobalAlias &A : M->aliases())
3018     if (auto *GV = dyn_cast<GlobalVariable>(A.getBaseObject()))
3019       WriteModuleLevelReferences(*GV, VE, NameVals, FSModRefsAbbrev, Stream);
3020 
3021   Stream.ExitBlock();
3022 }
3023 
3024 /// Emit the combined summary section into the combined index file.
3025 static void WriteCombinedGlobalValueSummary(
3026     const ModuleSummaryIndex &I, BitstreamWriter &Stream,
3027     std::map<uint64_t, unsigned> &GUIDToValueIdMap, unsigned GlobalValueId) {
3028   Stream.EnterSubblock(bitc::GLOBALVAL_SUMMARY_BLOCK_ID, 3);
3029 
3030   // Abbrev for FS_COMBINED.
3031   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
3032   Abbv->Add(BitCodeAbbrevOp(bitc::FS_COMBINED));
3033   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // modid
3034   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 5)); // linkage
3035   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
3036   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
3037   // numrefs x valueid, n x (valueid, callsitecount)
3038   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3039   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3040   unsigned FSCallsAbbrev = Stream.EmitAbbrev(Abbv);
3041 
3042   // Abbrev for FS_COMBINED_PROFILE.
3043   Abbv = new BitCodeAbbrev();
3044   Abbv->Add(BitCodeAbbrevOp(bitc::FS_COMBINED_PROFILE));
3045   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // modid
3046   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 5)); // linkage
3047   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
3048   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
3049   // numrefs x valueid, n x (valueid, callsitecount, profilecount)
3050   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3051   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3052   unsigned FSCallsProfileAbbrev = Stream.EmitAbbrev(Abbv);
3053 
3054   // Abbrev for FS_COMBINED_GLOBALVAR_INIT_REFS.
3055   Abbv = new BitCodeAbbrev();
3056   Abbv->Add(BitCodeAbbrevOp(bitc::FS_COMBINED_GLOBALVAR_INIT_REFS));
3057   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // modid
3058   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 5)); // linkage
3059   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));    // valueids
3060   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3061   unsigned FSModRefsAbbrev = Stream.EmitAbbrev(Abbv);
3062 
3063   SmallVector<uint64_t, 64> NameVals;
3064   for (const auto &FII : I) {
3065     for (auto &FI : FII.second) {
3066       GlobalValueSummary *S = FI->summary();
3067       assert(S);
3068 
3069       if (auto *VS = dyn_cast<GlobalVarSummary>(S)) {
3070         NameVals.push_back(I.getModuleId(VS->modulePath()));
3071         NameVals.push_back(getEncodedLinkage(VS->linkage()));
3072         for (auto &RI : VS->refs()) {
3073           const auto &VMI = GUIDToValueIdMap.find(RI);
3074           unsigned RefId;
3075           // If this GUID doesn't have an entry, assign one.
3076           if (VMI == GUIDToValueIdMap.end()) {
3077             GUIDToValueIdMap[RI] = ++GlobalValueId;
3078             RefId = GlobalValueId;
3079           } else {
3080             RefId = VMI->second;
3081           }
3082           NameVals.push_back(RefId);
3083         }
3084 
3085         // Record the starting offset of this summary entry for use
3086         // in the VST entry. Add the current code size since the
3087         // reader will invoke readRecord after the abbrev id read.
3088         FI->setBitcodeIndex(Stream.GetCurrentBitNo() +
3089                             Stream.GetAbbrevIDWidth());
3090 
3091         // Emit the finished record.
3092         Stream.EmitRecord(bitc::FS_COMBINED_GLOBALVAR_INIT_REFS, NameVals,
3093                           FSModRefsAbbrev);
3094         NameVals.clear();
3095         continue;
3096       }
3097 
3098       auto *FS = cast<FunctionSummary>(S);
3099       NameVals.push_back(I.getModuleId(FS->modulePath()));
3100       NameVals.push_back(getEncodedLinkage(FS->linkage()));
3101       NameVals.push_back(FS->instCount());
3102       NameVals.push_back(FS->refs().size());
3103 
3104       for (auto &RI : FS->refs()) {
3105         const auto &VMI = GUIDToValueIdMap.find(RI);
3106         unsigned RefId;
3107         // If this GUID doesn't have an entry, assign one.
3108         if (VMI == GUIDToValueIdMap.end()) {
3109           GUIDToValueIdMap[RI] = ++GlobalValueId;
3110           RefId = GlobalValueId;
3111         } else {
3112           RefId = VMI->second;
3113         }
3114         NameVals.push_back(RefId);
3115       }
3116 
3117       bool HasProfileData = false;
3118       for (auto &EI : FS->calls()) {
3119         HasProfileData |= EI.second.ProfileCount != 0;
3120         if (HasProfileData)
3121           break;
3122       }
3123 
3124       for (auto &EI : FS->calls()) {
3125         const auto &VMI = GUIDToValueIdMap.find(EI.first);
3126         // If this GUID doesn't have an entry, it doesn't have a function
3127         // summary and we don't need to record any calls to it.
3128         if (VMI == GUIDToValueIdMap.end())
3129           continue;
3130         NameVals.push_back(VMI->second);
3131         assert(EI.second.CallsiteCount > 0 && "Expected at least one callsite");
3132         NameVals.push_back(EI.second.CallsiteCount);
3133         if (HasProfileData)
3134           NameVals.push_back(EI.second.ProfileCount);
3135       }
3136 
3137       // Record the starting offset of this summary entry for use
3138       // in the VST entry. Add the current code size since the
3139       // reader will invoke readRecord after the abbrev id read.
3140       FI->setBitcodeIndex(Stream.GetCurrentBitNo() + Stream.GetAbbrevIDWidth());
3141 
3142       unsigned FSAbbrev =
3143           (HasProfileData ? FSCallsProfileAbbrev : FSCallsAbbrev);
3144       unsigned Code =
3145           (HasProfileData ? bitc::FS_COMBINED_PROFILE : bitc::FS_COMBINED);
3146 
3147       // Emit the finished record.
3148       Stream.EmitRecord(Code, NameVals, FSAbbrev);
3149       NameVals.clear();
3150     }
3151   }
3152 
3153   Stream.ExitBlock();
3154 }
3155 
3156 // Create the "IDENTIFICATION_BLOCK_ID" containing a single string with the
3157 // current llvm version, and a record for the epoch number.
3158 static void WriteIdentificationBlock(const Module *M, BitstreamWriter &Stream) {
3159   Stream.EnterSubblock(bitc::IDENTIFICATION_BLOCK_ID, 5);
3160 
3161   // Write the "user readable" string identifying the bitcode producer
3162   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
3163   Abbv->Add(BitCodeAbbrevOp(bitc::IDENTIFICATION_CODE_STRING));
3164   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3165   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
3166   auto StringAbbrev = Stream.EmitAbbrev(Abbv);
3167   WriteStringRecord(bitc::IDENTIFICATION_CODE_STRING,
3168                     "LLVM" LLVM_VERSION_STRING, StringAbbrev, Stream);
3169 
3170   // Write the epoch version
3171   Abbv = new BitCodeAbbrev();
3172   Abbv->Add(BitCodeAbbrevOp(bitc::IDENTIFICATION_CODE_EPOCH));
3173   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
3174   auto EpochAbbrev = Stream.EmitAbbrev(Abbv);
3175   SmallVector<unsigned, 1> Vals = {bitc::BITCODE_CURRENT_EPOCH};
3176   Stream.EmitRecord(bitc::IDENTIFICATION_CODE_EPOCH, Vals, EpochAbbrev);
3177   Stream.ExitBlock();
3178 }
3179 
3180 /// WriteModule - Emit the specified module to the bitstream.
3181 static void WriteModule(const Module *M, BitstreamWriter &Stream,
3182                         bool ShouldPreserveUseListOrder,
3183                         uint64_t BitcodeStartBit, bool EmitSummaryIndex) {
3184   Stream.EnterSubblock(bitc::MODULE_BLOCK_ID, 3);
3185 
3186   SmallVector<unsigned, 1> Vals;
3187   unsigned CurVersion = 1;
3188   Vals.push_back(CurVersion);
3189   Stream.EmitRecord(bitc::MODULE_CODE_VERSION, Vals);
3190 
3191   // Analyze the module, enumerating globals, functions, etc.
3192   ValueEnumerator VE(*M, ShouldPreserveUseListOrder);
3193 
3194   // Emit blockinfo, which defines the standard abbreviations etc.
3195   WriteBlockInfo(VE, Stream);
3196 
3197   // Emit information about attribute groups.
3198   WriteAttributeGroupTable(VE, Stream);
3199 
3200   // Emit information about parameter attributes.
3201   WriteAttributeTable(VE, Stream);
3202 
3203   // Emit information describing all of the types in the module.
3204   WriteTypeTable(VE, Stream);
3205 
3206   writeComdats(VE, Stream);
3207 
3208   // Emit top-level description of module, including target triple, inline asm,
3209   // descriptors for global variables, and function prototype info.
3210   uint64_t VSTOffsetPlaceholder = WriteModuleInfo(M, VE, Stream);
3211 
3212   // Emit constants.
3213   WriteModuleConstants(VE, Stream);
3214 
3215   // Emit metadata.
3216   writeModuleMetadata(*M, VE, Stream);
3217 
3218   // Emit metadata.
3219   WriteModuleMetadataStore(M, Stream);
3220 
3221   // Emit module-level use-lists.
3222   if (VE.shouldPreserveUseListOrder())
3223     WriteUseListBlock(nullptr, VE, Stream);
3224 
3225   WriteOperandBundleTags(M, Stream);
3226 
3227   // Emit function bodies.
3228   DenseMap<const Function *, std::unique_ptr<GlobalValueInfo>> FunctionIndex;
3229   for (Module::const_iterator F = M->begin(), E = M->end(); F != E; ++F)
3230     if (!F->isDeclaration())
3231       WriteFunction(*F, M, VE, Stream, FunctionIndex, EmitSummaryIndex);
3232 
3233   // Need to write after the above call to WriteFunction which populates
3234   // the summary information in the index.
3235   if (EmitSummaryIndex)
3236     WritePerModuleGlobalValueSummary(FunctionIndex, M, VE, Stream);
3237 
3238   WriteValueSymbolTable(M->getValueSymbolTable(), VE, Stream,
3239                         VSTOffsetPlaceholder, BitcodeStartBit, &FunctionIndex);
3240 
3241   Stream.ExitBlock();
3242 }
3243 
3244 /// EmitDarwinBCHeader - If generating a bc file on darwin, we have to emit a
3245 /// header and trailer to make it compatible with the system archiver.  To do
3246 /// this we emit the following header, and then emit a trailer that pads the
3247 /// file out to be a multiple of 16 bytes.
3248 ///
3249 /// struct bc_header {
3250 ///   uint32_t Magic;         // 0x0B17C0DE
3251 ///   uint32_t Version;       // Version, currently always 0.
3252 ///   uint32_t BitcodeOffset; // Offset to traditional bitcode file.
3253 ///   uint32_t BitcodeSize;   // Size of traditional bitcode file.
3254 ///   uint32_t CPUType;       // CPU specifier.
3255 ///   ... potentially more later ...
3256 /// };
3257 
3258 static void WriteInt32ToBuffer(uint32_t Value, SmallVectorImpl<char> &Buffer,
3259                                uint32_t &Position) {
3260   support::endian::write32le(&Buffer[Position], Value);
3261   Position += 4;
3262 }
3263 
3264 static void EmitDarwinBCHeaderAndTrailer(SmallVectorImpl<char> &Buffer,
3265                                          const Triple &TT) {
3266   unsigned CPUType = ~0U;
3267 
3268   // Match x86_64-*, i[3-9]86-*, powerpc-*, powerpc64-*, arm-*, thumb-*,
3269   // armv[0-9]-*, thumbv[0-9]-*, armv5te-*, or armv6t2-*. The CPUType is a magic
3270   // number from /usr/include/mach/machine.h.  It is ok to reproduce the
3271   // specific constants here because they are implicitly part of the Darwin ABI.
3272   enum {
3273     DARWIN_CPU_ARCH_ABI64      = 0x01000000,
3274     DARWIN_CPU_TYPE_X86        = 7,
3275     DARWIN_CPU_TYPE_ARM        = 12,
3276     DARWIN_CPU_TYPE_POWERPC    = 18
3277   };
3278 
3279   Triple::ArchType Arch = TT.getArch();
3280   if (Arch == Triple::x86_64)
3281     CPUType = DARWIN_CPU_TYPE_X86 | DARWIN_CPU_ARCH_ABI64;
3282   else if (Arch == Triple::x86)
3283     CPUType = DARWIN_CPU_TYPE_X86;
3284   else if (Arch == Triple::ppc)
3285     CPUType = DARWIN_CPU_TYPE_POWERPC;
3286   else if (Arch == Triple::ppc64)
3287     CPUType = DARWIN_CPU_TYPE_POWERPC | DARWIN_CPU_ARCH_ABI64;
3288   else if (Arch == Triple::arm || Arch == Triple::thumb)
3289     CPUType = DARWIN_CPU_TYPE_ARM;
3290 
3291   // Traditional Bitcode starts after header.
3292   assert(Buffer.size() >= BWH_HeaderSize &&
3293          "Expected header size to be reserved");
3294   unsigned BCOffset = BWH_HeaderSize;
3295   unsigned BCSize = Buffer.size() - BWH_HeaderSize;
3296 
3297   // Write the magic and version.
3298   unsigned Position = 0;
3299   WriteInt32ToBuffer(0x0B17C0DE , Buffer, Position);
3300   WriteInt32ToBuffer(0          , Buffer, Position); // Version.
3301   WriteInt32ToBuffer(BCOffset   , Buffer, Position);
3302   WriteInt32ToBuffer(BCSize     , Buffer, Position);
3303   WriteInt32ToBuffer(CPUType    , Buffer, Position);
3304 
3305   // If the file is not a multiple of 16 bytes, insert dummy padding.
3306   while (Buffer.size() & 15)
3307     Buffer.push_back(0);
3308 }
3309 
3310 /// Helper to write the header common to all bitcode files.
3311 static void WriteBitcodeHeader(BitstreamWriter &Stream) {
3312   // Emit the file header.
3313   Stream.Emit((unsigned)'B', 8);
3314   Stream.Emit((unsigned)'C', 8);
3315   Stream.Emit(0x0, 4);
3316   Stream.Emit(0xC, 4);
3317   Stream.Emit(0xE, 4);
3318   Stream.Emit(0xD, 4);
3319 }
3320 
3321 /// WriteBitcodeToFile - Write the specified module to the specified output
3322 /// stream.
3323 void llvm::WriteBitcodeToFile(const Module *M, raw_ostream &Out,
3324                               bool ShouldPreserveUseListOrder,
3325                               bool EmitSummaryIndex) {
3326   SmallVector<char, 0> Buffer;
3327   Buffer.reserve(256*1024);
3328 
3329   // If this is darwin or another generic macho target, reserve space for the
3330   // header.
3331   Triple TT(M->getTargetTriple());
3332   if (TT.isOSDarwin() || TT.isOSBinFormatMachO())
3333     Buffer.insert(Buffer.begin(), BWH_HeaderSize, 0);
3334 
3335   // Emit the module into the buffer.
3336   {
3337     BitstreamWriter Stream(Buffer);
3338     // Save the start bit of the actual bitcode, in case there is space
3339     // saved at the start for the darwin header above. The reader stream
3340     // will start at the bitcode, and we need the offset of the VST
3341     // to line up.
3342     uint64_t BitcodeStartBit = Stream.GetCurrentBitNo();
3343 
3344     // Emit the file header.
3345     WriteBitcodeHeader(Stream);
3346 
3347     WriteIdentificationBlock(M, Stream);
3348 
3349     // Emit the module.
3350     WriteModule(M, Stream, ShouldPreserveUseListOrder, BitcodeStartBit,
3351                 EmitSummaryIndex);
3352   }
3353 
3354   if (TT.isOSDarwin() || TT.isOSBinFormatMachO())
3355     EmitDarwinBCHeaderAndTrailer(Buffer, TT);
3356 
3357   // Write the generated bitstream to "Out".
3358   Out.write((char*)&Buffer.front(), Buffer.size());
3359 }
3360 
3361 // Write the specified module summary index to the given raw output stream,
3362 // where it will be written in a new bitcode block. This is used when
3363 // writing the combined index file for ThinLTO.
3364 void llvm::WriteIndexToFile(const ModuleSummaryIndex &Index, raw_ostream &Out) {
3365   SmallVector<char, 0> Buffer;
3366   Buffer.reserve(256 * 1024);
3367 
3368   BitstreamWriter Stream(Buffer);
3369 
3370   // Emit the bitcode header.
3371   WriteBitcodeHeader(Stream);
3372 
3373   Stream.EnterSubblock(bitc::MODULE_BLOCK_ID, 3);
3374 
3375   SmallVector<unsigned, 1> Vals;
3376   unsigned CurVersion = 1;
3377   Vals.push_back(CurVersion);
3378   Stream.EmitRecord(bitc::MODULE_CODE_VERSION, Vals);
3379 
3380   // If we have a VST, write the VSTOFFSET record placeholder and record
3381   // its offset.
3382   uint64_t VSTOffsetPlaceholder = WriteValueSymbolTableForwardDecl(Stream);
3383 
3384   // Write the module paths in the combined index.
3385   WriteModStrings(Index, Stream);
3386 
3387   // Assign unique value ids to all functions in the index for use
3388   // in writing out the call graph edges. Save the mapping from GUID
3389   // to the new global value id to use when writing those edges, which
3390   // are currently saved in the index in terms of GUID.
3391   std::map<uint64_t, unsigned> GUIDToValueIdMap;
3392   unsigned GlobalValueId = 0;
3393   for (auto &II : Index)
3394     GUIDToValueIdMap[II.first] = ++GlobalValueId;
3395 
3396   // Write the summary combined index records.
3397   WriteCombinedGlobalValueSummary(Index, Stream, GUIDToValueIdMap,
3398                                   GlobalValueId);
3399 
3400   // Need a special VST writer for the combined index (we don't have a
3401   // real VST and real values when this is invoked).
3402   WriteCombinedValueSymbolTable(Index, Stream, GUIDToValueIdMap,
3403                                 VSTOffsetPlaceholder);
3404 
3405   Stream.ExitBlock();
3406 
3407   Out.write((char *)&Buffer.front(), Buffer.size());
3408 }
3409