xref: /llvm-project/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp (revision fdbf0a5af805b764927bd8b38da89ddffc67f531)
1 //===--- Bitcode/Writer/BitcodeWriter.cpp - Bitcode Writer ----------------===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // Bitcode writer implementation.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "ValueEnumerator.h"
15 #include "llvm/ADT/STLExtras.h"
16 #include "llvm/ADT/Triple.h"
17 #include "llvm/Analysis/BlockFrequencyInfo.h"
18 #include "llvm/Analysis/BlockFrequencyInfoImpl.h"
19 #include "llvm/Analysis/BranchProbabilityInfo.h"
20 #include "llvm/Analysis/LoopInfo.h"
21 #include "llvm/Bitcode/BitstreamWriter.h"
22 #include "llvm/Bitcode/LLVMBitCodes.h"
23 #include "llvm/Bitcode/ReaderWriter.h"
24 #include "llvm/IR/CallSite.h"
25 #include "llvm/IR/Constants.h"
26 #include "llvm/IR/DebugInfoMetadata.h"
27 #include "llvm/IR/DerivedTypes.h"
28 #include "llvm/IR/Dominators.h"
29 #include "llvm/IR/InlineAsm.h"
30 #include "llvm/IR/Instructions.h"
31 #include "llvm/IR/IntrinsicInst.h"
32 #include "llvm/IR/LLVMContext.h"
33 #include "llvm/IR/Module.h"
34 #include "llvm/IR/Operator.h"
35 #include "llvm/IR/UseListOrder.h"
36 #include "llvm/IR/ValueSymbolTable.h"
37 #include "llvm/Support/CommandLine.h"
38 #include "llvm/Support/ErrorHandling.h"
39 #include "llvm/Support/MathExtras.h"
40 #include "llvm/Support/Program.h"
41 #include "llvm/Support/raw_ostream.h"
42 #include <cctype>
43 #include <map>
44 using namespace llvm;
45 
46 /// These are manifest constants used by the bitcode writer. They do not need to
47 /// be kept in sync with the reader, but need to be consistent within this file.
48 enum {
49   // VALUE_SYMTAB_BLOCK abbrev id's.
50   VST_ENTRY_8_ABBREV = bitc::FIRST_APPLICATION_ABBREV,
51   VST_ENTRY_7_ABBREV,
52   VST_ENTRY_6_ABBREV,
53   VST_BBENTRY_6_ABBREV,
54 
55   // CONSTANTS_BLOCK abbrev id's.
56   CONSTANTS_SETTYPE_ABBREV = bitc::FIRST_APPLICATION_ABBREV,
57   CONSTANTS_INTEGER_ABBREV,
58   CONSTANTS_CE_CAST_Abbrev,
59   CONSTANTS_NULL_Abbrev,
60 
61   // FUNCTION_BLOCK abbrev id's.
62   FUNCTION_INST_LOAD_ABBREV = bitc::FIRST_APPLICATION_ABBREV,
63   FUNCTION_INST_BINOP_ABBREV,
64   FUNCTION_INST_BINOP_FLAGS_ABBREV,
65   FUNCTION_INST_CAST_ABBREV,
66   FUNCTION_INST_RET_VOID_ABBREV,
67   FUNCTION_INST_RET_VAL_ABBREV,
68   FUNCTION_INST_UNREACHABLE_ABBREV,
69   FUNCTION_INST_GEP_ABBREV,
70 };
71 
72 static unsigned GetEncodedCastOpcode(unsigned Opcode) {
73   switch (Opcode) {
74   default: llvm_unreachable("Unknown cast instruction!");
75   case Instruction::Trunc   : return bitc::CAST_TRUNC;
76   case Instruction::ZExt    : return bitc::CAST_ZEXT;
77   case Instruction::SExt    : return bitc::CAST_SEXT;
78   case Instruction::FPToUI  : return bitc::CAST_FPTOUI;
79   case Instruction::FPToSI  : return bitc::CAST_FPTOSI;
80   case Instruction::UIToFP  : return bitc::CAST_UITOFP;
81   case Instruction::SIToFP  : return bitc::CAST_SITOFP;
82   case Instruction::FPTrunc : return bitc::CAST_FPTRUNC;
83   case Instruction::FPExt   : return bitc::CAST_FPEXT;
84   case Instruction::PtrToInt: return bitc::CAST_PTRTOINT;
85   case Instruction::IntToPtr: return bitc::CAST_INTTOPTR;
86   case Instruction::BitCast : return bitc::CAST_BITCAST;
87   case Instruction::AddrSpaceCast: return bitc::CAST_ADDRSPACECAST;
88   }
89 }
90 
91 static unsigned GetEncodedBinaryOpcode(unsigned Opcode) {
92   switch (Opcode) {
93   default: llvm_unreachable("Unknown binary instruction!");
94   case Instruction::Add:
95   case Instruction::FAdd: return bitc::BINOP_ADD;
96   case Instruction::Sub:
97   case Instruction::FSub: return bitc::BINOP_SUB;
98   case Instruction::Mul:
99   case Instruction::FMul: return bitc::BINOP_MUL;
100   case Instruction::UDiv: return bitc::BINOP_UDIV;
101   case Instruction::FDiv:
102   case Instruction::SDiv: return bitc::BINOP_SDIV;
103   case Instruction::URem: return bitc::BINOP_UREM;
104   case Instruction::FRem:
105   case Instruction::SRem: return bitc::BINOP_SREM;
106   case Instruction::Shl:  return bitc::BINOP_SHL;
107   case Instruction::LShr: return bitc::BINOP_LSHR;
108   case Instruction::AShr: return bitc::BINOP_ASHR;
109   case Instruction::And:  return bitc::BINOP_AND;
110   case Instruction::Or:   return bitc::BINOP_OR;
111   case Instruction::Xor:  return bitc::BINOP_XOR;
112   }
113 }
114 
115 static unsigned GetEncodedRMWOperation(AtomicRMWInst::BinOp Op) {
116   switch (Op) {
117   default: llvm_unreachable("Unknown RMW operation!");
118   case AtomicRMWInst::Xchg: return bitc::RMW_XCHG;
119   case AtomicRMWInst::Add: return bitc::RMW_ADD;
120   case AtomicRMWInst::Sub: return bitc::RMW_SUB;
121   case AtomicRMWInst::And: return bitc::RMW_AND;
122   case AtomicRMWInst::Nand: return bitc::RMW_NAND;
123   case AtomicRMWInst::Or: return bitc::RMW_OR;
124   case AtomicRMWInst::Xor: return bitc::RMW_XOR;
125   case AtomicRMWInst::Max: return bitc::RMW_MAX;
126   case AtomicRMWInst::Min: return bitc::RMW_MIN;
127   case AtomicRMWInst::UMax: return bitc::RMW_UMAX;
128   case AtomicRMWInst::UMin: return bitc::RMW_UMIN;
129   }
130 }
131 
132 static unsigned GetEncodedOrdering(AtomicOrdering Ordering) {
133   switch (Ordering) {
134   case NotAtomic: return bitc::ORDERING_NOTATOMIC;
135   case Unordered: return bitc::ORDERING_UNORDERED;
136   case Monotonic: return bitc::ORDERING_MONOTONIC;
137   case Acquire: return bitc::ORDERING_ACQUIRE;
138   case Release: return bitc::ORDERING_RELEASE;
139   case AcquireRelease: return bitc::ORDERING_ACQREL;
140   case SequentiallyConsistent: return bitc::ORDERING_SEQCST;
141   }
142   llvm_unreachable("Invalid ordering");
143 }
144 
145 static unsigned GetEncodedSynchScope(SynchronizationScope SynchScope) {
146   switch (SynchScope) {
147   case SingleThread: return bitc::SYNCHSCOPE_SINGLETHREAD;
148   case CrossThread: return bitc::SYNCHSCOPE_CROSSTHREAD;
149   }
150   llvm_unreachable("Invalid synch scope");
151 }
152 
153 static void WriteStringRecord(unsigned Code, StringRef Str,
154                               unsigned AbbrevToUse, BitstreamWriter &Stream) {
155   SmallVector<unsigned, 64> Vals;
156 
157   // Code: [strchar x N]
158   for (unsigned i = 0, e = Str.size(); i != e; ++i) {
159     if (AbbrevToUse && !BitCodeAbbrevOp::isChar6(Str[i]))
160       AbbrevToUse = 0;
161     Vals.push_back(Str[i]);
162   }
163 
164   // Emit the finished record.
165   Stream.EmitRecord(Code, Vals, AbbrevToUse);
166 }
167 
168 static uint64_t getAttrKindEncoding(Attribute::AttrKind Kind) {
169   switch (Kind) {
170   case Attribute::Alignment:
171     return bitc::ATTR_KIND_ALIGNMENT;
172   case Attribute::AlwaysInline:
173     return bitc::ATTR_KIND_ALWAYS_INLINE;
174   case Attribute::ArgMemOnly:
175     return bitc::ATTR_KIND_ARGMEMONLY;
176   case Attribute::Builtin:
177     return bitc::ATTR_KIND_BUILTIN;
178   case Attribute::ByVal:
179     return bitc::ATTR_KIND_BY_VAL;
180   case Attribute::Convergent:
181     return bitc::ATTR_KIND_CONVERGENT;
182   case Attribute::InAlloca:
183     return bitc::ATTR_KIND_IN_ALLOCA;
184   case Attribute::Cold:
185     return bitc::ATTR_KIND_COLD;
186   case Attribute::InaccessibleMemOnly:
187     return bitc::ATTR_KIND_INACCESSIBLEMEM_ONLY;
188   case Attribute::InaccessibleMemOrArgMemOnly:
189     return bitc::ATTR_KIND_INACCESSIBLEMEM_OR_ARGMEMONLY;
190   case Attribute::InlineHint:
191     return bitc::ATTR_KIND_INLINE_HINT;
192   case Attribute::InReg:
193     return bitc::ATTR_KIND_IN_REG;
194   case Attribute::JumpTable:
195     return bitc::ATTR_KIND_JUMP_TABLE;
196   case Attribute::MinSize:
197     return bitc::ATTR_KIND_MIN_SIZE;
198   case Attribute::Naked:
199     return bitc::ATTR_KIND_NAKED;
200   case Attribute::Nest:
201     return bitc::ATTR_KIND_NEST;
202   case Attribute::NoAlias:
203     return bitc::ATTR_KIND_NO_ALIAS;
204   case Attribute::NoBuiltin:
205     return bitc::ATTR_KIND_NO_BUILTIN;
206   case Attribute::NoCapture:
207     return bitc::ATTR_KIND_NO_CAPTURE;
208   case Attribute::NoDuplicate:
209     return bitc::ATTR_KIND_NO_DUPLICATE;
210   case Attribute::NoImplicitFloat:
211     return bitc::ATTR_KIND_NO_IMPLICIT_FLOAT;
212   case Attribute::NoInline:
213     return bitc::ATTR_KIND_NO_INLINE;
214   case Attribute::NoRecurse:
215     return bitc::ATTR_KIND_NO_RECURSE;
216   case Attribute::NonLazyBind:
217     return bitc::ATTR_KIND_NON_LAZY_BIND;
218   case Attribute::NonNull:
219     return bitc::ATTR_KIND_NON_NULL;
220   case Attribute::Dereferenceable:
221     return bitc::ATTR_KIND_DEREFERENCEABLE;
222   case Attribute::DereferenceableOrNull:
223     return bitc::ATTR_KIND_DEREFERENCEABLE_OR_NULL;
224   case Attribute::NoRedZone:
225     return bitc::ATTR_KIND_NO_RED_ZONE;
226   case Attribute::NoReturn:
227     return bitc::ATTR_KIND_NO_RETURN;
228   case Attribute::NoUnwind:
229     return bitc::ATTR_KIND_NO_UNWIND;
230   case Attribute::OptimizeForSize:
231     return bitc::ATTR_KIND_OPTIMIZE_FOR_SIZE;
232   case Attribute::OptimizeNone:
233     return bitc::ATTR_KIND_OPTIMIZE_NONE;
234   case Attribute::ReadNone:
235     return bitc::ATTR_KIND_READ_NONE;
236   case Attribute::ReadOnly:
237     return bitc::ATTR_KIND_READ_ONLY;
238   case Attribute::Returned:
239     return bitc::ATTR_KIND_RETURNED;
240   case Attribute::ReturnsTwice:
241     return bitc::ATTR_KIND_RETURNS_TWICE;
242   case Attribute::SExt:
243     return bitc::ATTR_KIND_S_EXT;
244   case Attribute::StackAlignment:
245     return bitc::ATTR_KIND_STACK_ALIGNMENT;
246   case Attribute::StackProtect:
247     return bitc::ATTR_KIND_STACK_PROTECT;
248   case Attribute::StackProtectReq:
249     return bitc::ATTR_KIND_STACK_PROTECT_REQ;
250   case Attribute::StackProtectStrong:
251     return bitc::ATTR_KIND_STACK_PROTECT_STRONG;
252   case Attribute::SafeStack:
253     return bitc::ATTR_KIND_SAFESTACK;
254   case Attribute::StructRet:
255     return bitc::ATTR_KIND_STRUCT_RET;
256   case Attribute::SanitizeAddress:
257     return bitc::ATTR_KIND_SANITIZE_ADDRESS;
258   case Attribute::SanitizeThread:
259     return bitc::ATTR_KIND_SANITIZE_THREAD;
260   case Attribute::SanitizeMemory:
261     return bitc::ATTR_KIND_SANITIZE_MEMORY;
262   case Attribute::UWTable:
263     return bitc::ATTR_KIND_UW_TABLE;
264   case Attribute::ZExt:
265     return bitc::ATTR_KIND_Z_EXT;
266   case Attribute::EndAttrKinds:
267     llvm_unreachable("Can not encode end-attribute kinds marker.");
268   case Attribute::None:
269     llvm_unreachable("Can not encode none-attribute.");
270   }
271 
272   llvm_unreachable("Trying to encode unknown attribute");
273 }
274 
275 static void WriteAttributeGroupTable(const ValueEnumerator &VE,
276                                      BitstreamWriter &Stream) {
277   const std::vector<AttributeSet> &AttrGrps = VE.getAttributeGroups();
278   if (AttrGrps.empty()) return;
279 
280   Stream.EnterSubblock(bitc::PARAMATTR_GROUP_BLOCK_ID, 3);
281 
282   SmallVector<uint64_t, 64> Record;
283   for (unsigned i = 0, e = AttrGrps.size(); i != e; ++i) {
284     AttributeSet AS = AttrGrps[i];
285     for (unsigned i = 0, e = AS.getNumSlots(); i != e; ++i) {
286       AttributeSet A = AS.getSlotAttributes(i);
287 
288       Record.push_back(VE.getAttributeGroupID(A));
289       Record.push_back(AS.getSlotIndex(i));
290 
291       for (AttributeSet::iterator I = AS.begin(0), E = AS.end(0);
292            I != E; ++I) {
293         Attribute Attr = *I;
294         if (Attr.isEnumAttribute()) {
295           Record.push_back(0);
296           Record.push_back(getAttrKindEncoding(Attr.getKindAsEnum()));
297         } else if (Attr.isIntAttribute()) {
298           Record.push_back(1);
299           Record.push_back(getAttrKindEncoding(Attr.getKindAsEnum()));
300           Record.push_back(Attr.getValueAsInt());
301         } else {
302           StringRef Kind = Attr.getKindAsString();
303           StringRef Val = Attr.getValueAsString();
304 
305           Record.push_back(Val.empty() ? 3 : 4);
306           Record.append(Kind.begin(), Kind.end());
307           Record.push_back(0);
308           if (!Val.empty()) {
309             Record.append(Val.begin(), Val.end());
310             Record.push_back(0);
311           }
312         }
313       }
314 
315       Stream.EmitRecord(bitc::PARAMATTR_GRP_CODE_ENTRY, Record);
316       Record.clear();
317     }
318   }
319 
320   Stream.ExitBlock();
321 }
322 
323 static void WriteAttributeTable(const ValueEnumerator &VE,
324                                 BitstreamWriter &Stream) {
325   const std::vector<AttributeSet> &Attrs = VE.getAttributes();
326   if (Attrs.empty()) return;
327 
328   Stream.EnterSubblock(bitc::PARAMATTR_BLOCK_ID, 3);
329 
330   SmallVector<uint64_t, 64> Record;
331   for (unsigned i = 0, e = Attrs.size(); i != e; ++i) {
332     const AttributeSet &A = Attrs[i];
333     for (unsigned i = 0, e = A.getNumSlots(); i != e; ++i)
334       Record.push_back(VE.getAttributeGroupID(A.getSlotAttributes(i)));
335 
336     Stream.EmitRecord(bitc::PARAMATTR_CODE_ENTRY, Record);
337     Record.clear();
338   }
339 
340   Stream.ExitBlock();
341 }
342 
343 /// WriteTypeTable - Write out the type table for a module.
344 static void WriteTypeTable(const ValueEnumerator &VE, BitstreamWriter &Stream) {
345   const ValueEnumerator::TypeList &TypeList = VE.getTypes();
346 
347   Stream.EnterSubblock(bitc::TYPE_BLOCK_ID_NEW, 4 /*count from # abbrevs */);
348   SmallVector<uint64_t, 64> TypeVals;
349 
350   uint64_t NumBits = VE.computeBitsRequiredForTypeIndicies();
351 
352   // Abbrev for TYPE_CODE_POINTER.
353   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
354   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_POINTER));
355   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
356   Abbv->Add(BitCodeAbbrevOp(0));  // Addrspace = 0
357   unsigned PtrAbbrev = Stream.EmitAbbrev(Abbv);
358 
359   // Abbrev for TYPE_CODE_FUNCTION.
360   Abbv = new BitCodeAbbrev();
361   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_FUNCTION));
362   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // isvararg
363   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
364   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
365 
366   unsigned FunctionAbbrev = Stream.EmitAbbrev(Abbv);
367 
368   // Abbrev for TYPE_CODE_STRUCT_ANON.
369   Abbv = new BitCodeAbbrev();
370   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_ANON));
371   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // ispacked
372   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
373   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
374 
375   unsigned StructAnonAbbrev = Stream.EmitAbbrev(Abbv);
376 
377   // Abbrev for TYPE_CODE_STRUCT_NAME.
378   Abbv = new BitCodeAbbrev();
379   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_NAME));
380   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
381   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
382   unsigned StructNameAbbrev = Stream.EmitAbbrev(Abbv);
383 
384   // Abbrev for TYPE_CODE_STRUCT_NAMED.
385   Abbv = new BitCodeAbbrev();
386   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_NAMED));
387   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // ispacked
388   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
389   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
390 
391   unsigned StructNamedAbbrev = Stream.EmitAbbrev(Abbv);
392 
393   // Abbrev for TYPE_CODE_ARRAY.
394   Abbv = new BitCodeAbbrev();
395   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_ARRAY));
396   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // size
397   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
398 
399   unsigned ArrayAbbrev = Stream.EmitAbbrev(Abbv);
400 
401   // Emit an entry count so the reader can reserve space.
402   TypeVals.push_back(TypeList.size());
403   Stream.EmitRecord(bitc::TYPE_CODE_NUMENTRY, TypeVals);
404   TypeVals.clear();
405 
406   // Loop over all of the types, emitting each in turn.
407   for (unsigned i = 0, e = TypeList.size(); i != e; ++i) {
408     Type *T = TypeList[i];
409     int AbbrevToUse = 0;
410     unsigned Code = 0;
411 
412     switch (T->getTypeID()) {
413     case Type::VoidTyID:      Code = bitc::TYPE_CODE_VOID;      break;
414     case Type::HalfTyID:      Code = bitc::TYPE_CODE_HALF;      break;
415     case Type::FloatTyID:     Code = bitc::TYPE_CODE_FLOAT;     break;
416     case Type::DoubleTyID:    Code = bitc::TYPE_CODE_DOUBLE;    break;
417     case Type::X86_FP80TyID:  Code = bitc::TYPE_CODE_X86_FP80;  break;
418     case Type::FP128TyID:     Code = bitc::TYPE_CODE_FP128;     break;
419     case Type::PPC_FP128TyID: Code = bitc::TYPE_CODE_PPC_FP128; break;
420     case Type::LabelTyID:     Code = bitc::TYPE_CODE_LABEL;     break;
421     case Type::MetadataTyID:  Code = bitc::TYPE_CODE_METADATA;  break;
422     case Type::X86_MMXTyID:   Code = bitc::TYPE_CODE_X86_MMX;   break;
423     case Type::TokenTyID:     Code = bitc::TYPE_CODE_TOKEN;     break;
424     case Type::IntegerTyID:
425       // INTEGER: [width]
426       Code = bitc::TYPE_CODE_INTEGER;
427       TypeVals.push_back(cast<IntegerType>(T)->getBitWidth());
428       break;
429     case Type::PointerTyID: {
430       PointerType *PTy = cast<PointerType>(T);
431       // POINTER: [pointee type, address space]
432       Code = bitc::TYPE_CODE_POINTER;
433       TypeVals.push_back(VE.getTypeID(PTy->getElementType()));
434       unsigned AddressSpace = PTy->getAddressSpace();
435       TypeVals.push_back(AddressSpace);
436       if (AddressSpace == 0) AbbrevToUse = PtrAbbrev;
437       break;
438     }
439     case Type::FunctionTyID: {
440       FunctionType *FT = cast<FunctionType>(T);
441       // FUNCTION: [isvararg, retty, paramty x N]
442       Code = bitc::TYPE_CODE_FUNCTION;
443       TypeVals.push_back(FT->isVarArg());
444       TypeVals.push_back(VE.getTypeID(FT->getReturnType()));
445       for (unsigned i = 0, e = FT->getNumParams(); i != e; ++i)
446         TypeVals.push_back(VE.getTypeID(FT->getParamType(i)));
447       AbbrevToUse = FunctionAbbrev;
448       break;
449     }
450     case Type::StructTyID: {
451       StructType *ST = cast<StructType>(T);
452       // STRUCT: [ispacked, eltty x N]
453       TypeVals.push_back(ST->isPacked());
454       // Output all of the element types.
455       for (StructType::element_iterator I = ST->element_begin(),
456            E = ST->element_end(); I != E; ++I)
457         TypeVals.push_back(VE.getTypeID(*I));
458 
459       if (ST->isLiteral()) {
460         Code = bitc::TYPE_CODE_STRUCT_ANON;
461         AbbrevToUse = StructAnonAbbrev;
462       } else {
463         if (ST->isOpaque()) {
464           Code = bitc::TYPE_CODE_OPAQUE;
465         } else {
466           Code = bitc::TYPE_CODE_STRUCT_NAMED;
467           AbbrevToUse = StructNamedAbbrev;
468         }
469 
470         // Emit the name if it is present.
471         if (!ST->getName().empty())
472           WriteStringRecord(bitc::TYPE_CODE_STRUCT_NAME, ST->getName(),
473                             StructNameAbbrev, Stream);
474       }
475       break;
476     }
477     case Type::ArrayTyID: {
478       ArrayType *AT = cast<ArrayType>(T);
479       // ARRAY: [numelts, eltty]
480       Code = bitc::TYPE_CODE_ARRAY;
481       TypeVals.push_back(AT->getNumElements());
482       TypeVals.push_back(VE.getTypeID(AT->getElementType()));
483       AbbrevToUse = ArrayAbbrev;
484       break;
485     }
486     case Type::VectorTyID: {
487       VectorType *VT = cast<VectorType>(T);
488       // VECTOR [numelts, eltty]
489       Code = bitc::TYPE_CODE_VECTOR;
490       TypeVals.push_back(VT->getNumElements());
491       TypeVals.push_back(VE.getTypeID(VT->getElementType()));
492       break;
493     }
494     }
495 
496     // Emit the finished record.
497     Stream.EmitRecord(Code, TypeVals, AbbrevToUse);
498     TypeVals.clear();
499   }
500 
501   Stream.ExitBlock();
502 }
503 
504 static unsigned getEncodedLinkage(const GlobalValue::LinkageTypes Linkage) {
505   switch (Linkage) {
506   case GlobalValue::ExternalLinkage:
507     return 0;
508   case GlobalValue::WeakAnyLinkage:
509     return 16;
510   case GlobalValue::AppendingLinkage:
511     return 2;
512   case GlobalValue::InternalLinkage:
513     return 3;
514   case GlobalValue::LinkOnceAnyLinkage:
515     return 18;
516   case GlobalValue::ExternalWeakLinkage:
517     return 7;
518   case GlobalValue::CommonLinkage:
519     return 8;
520   case GlobalValue::PrivateLinkage:
521     return 9;
522   case GlobalValue::WeakODRLinkage:
523     return 17;
524   case GlobalValue::LinkOnceODRLinkage:
525     return 19;
526   case GlobalValue::AvailableExternallyLinkage:
527     return 12;
528   }
529   llvm_unreachable("Invalid linkage");
530 }
531 
532 static unsigned getEncodedLinkage(const GlobalValue &GV) {
533   return getEncodedLinkage(GV.getLinkage());
534 }
535 
536 static unsigned getEncodedVisibility(const GlobalValue &GV) {
537   switch (GV.getVisibility()) {
538   case GlobalValue::DefaultVisibility:   return 0;
539   case GlobalValue::HiddenVisibility:    return 1;
540   case GlobalValue::ProtectedVisibility: return 2;
541   }
542   llvm_unreachable("Invalid visibility");
543 }
544 
545 static unsigned getEncodedDLLStorageClass(const GlobalValue &GV) {
546   switch (GV.getDLLStorageClass()) {
547   case GlobalValue::DefaultStorageClass:   return 0;
548   case GlobalValue::DLLImportStorageClass: return 1;
549   case GlobalValue::DLLExportStorageClass: return 2;
550   }
551   llvm_unreachable("Invalid DLL storage class");
552 }
553 
554 static unsigned getEncodedThreadLocalMode(const GlobalValue &GV) {
555   switch (GV.getThreadLocalMode()) {
556     case GlobalVariable::NotThreadLocal:         return 0;
557     case GlobalVariable::GeneralDynamicTLSModel: return 1;
558     case GlobalVariable::LocalDynamicTLSModel:   return 2;
559     case GlobalVariable::InitialExecTLSModel:    return 3;
560     case GlobalVariable::LocalExecTLSModel:      return 4;
561   }
562   llvm_unreachable("Invalid TLS model");
563 }
564 
565 static unsigned getEncodedComdatSelectionKind(const Comdat &C) {
566   switch (C.getSelectionKind()) {
567   case Comdat::Any:
568     return bitc::COMDAT_SELECTION_KIND_ANY;
569   case Comdat::ExactMatch:
570     return bitc::COMDAT_SELECTION_KIND_EXACT_MATCH;
571   case Comdat::Largest:
572     return bitc::COMDAT_SELECTION_KIND_LARGEST;
573   case Comdat::NoDuplicates:
574     return bitc::COMDAT_SELECTION_KIND_NO_DUPLICATES;
575   case Comdat::SameSize:
576     return bitc::COMDAT_SELECTION_KIND_SAME_SIZE;
577   }
578   llvm_unreachable("Invalid selection kind");
579 }
580 
581 static void writeComdats(const ValueEnumerator &VE, BitstreamWriter &Stream) {
582   SmallVector<unsigned, 64> Vals;
583   for (const Comdat *C : VE.getComdats()) {
584     // COMDAT: [selection_kind, name]
585     Vals.push_back(getEncodedComdatSelectionKind(*C));
586     size_t Size = C->getName().size();
587     assert(isUInt<32>(Size));
588     Vals.push_back(Size);
589     for (char Chr : C->getName())
590       Vals.push_back((unsigned char)Chr);
591     Stream.EmitRecord(bitc::MODULE_CODE_COMDAT, Vals, /*AbbrevToUse=*/0);
592     Vals.clear();
593   }
594 }
595 
596 /// Write a record that will eventually hold the word offset of the
597 /// module-level VST. For now the offset is 0, which will be backpatched
598 /// after the real VST is written. Returns the bit offset to backpatch.
599 static uint64_t WriteValueSymbolTableForwardDecl(BitstreamWriter &Stream) {
600   // Write a placeholder value in for the offset of the real VST,
601   // which is written after the function blocks so that it can include
602   // the offset of each function. The placeholder offset will be
603   // updated when the real VST is written.
604   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
605   Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_VSTOFFSET));
606   // Blocks are 32-bit aligned, so we can use a 32-bit word offset to
607   // hold the real VST offset. Must use fixed instead of VBR as we don't
608   // know how many VBR chunks to reserve ahead of time.
609   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
610   unsigned VSTOffsetAbbrev = Stream.EmitAbbrev(Abbv);
611 
612   // Emit the placeholder
613   uint64_t Vals[] = {bitc::MODULE_CODE_VSTOFFSET, 0};
614   Stream.EmitRecordWithAbbrev(VSTOffsetAbbrev, Vals);
615 
616   // Compute and return the bit offset to the placeholder, which will be
617   // patched when the real VST is written. We can simply subtract the 32-bit
618   // fixed size from the current bit number to get the location to backpatch.
619   return Stream.GetCurrentBitNo() - 32;
620 }
621 
622 enum StringEncoding { SE_Char6, SE_Fixed7, SE_Fixed8 };
623 
624 /// Determine the encoding to use for the given string name and length.
625 static StringEncoding getStringEncoding(const char *Str, unsigned StrLen) {
626   bool isChar6 = true;
627   for (const char *C = Str, *E = C + StrLen; C != E; ++C) {
628     if (isChar6)
629       isChar6 = BitCodeAbbrevOp::isChar6(*C);
630     if ((unsigned char)*C & 128)
631       // don't bother scanning the rest.
632       return SE_Fixed8;
633   }
634   if (isChar6)
635     return SE_Char6;
636   else
637     return SE_Fixed7;
638 }
639 
640 /// Emit top-level description of module, including target triple, inline asm,
641 /// descriptors for global variables, and function prototype info.
642 /// Returns the bit offset to backpatch with the location of the real VST.
643 static uint64_t WriteModuleInfo(const Module *M, const ValueEnumerator &VE,
644                                 BitstreamWriter &Stream) {
645   // Emit various pieces of data attached to a module.
646   if (!M->getTargetTriple().empty())
647     WriteStringRecord(bitc::MODULE_CODE_TRIPLE, M->getTargetTriple(),
648                       0/*TODO*/, Stream);
649   const std::string &DL = M->getDataLayoutStr();
650   if (!DL.empty())
651     WriteStringRecord(bitc::MODULE_CODE_DATALAYOUT, DL, 0 /*TODO*/, Stream);
652   if (!M->getModuleInlineAsm().empty())
653     WriteStringRecord(bitc::MODULE_CODE_ASM, M->getModuleInlineAsm(),
654                       0/*TODO*/, Stream);
655 
656   // Emit information about sections and GC, computing how many there are. Also
657   // compute the maximum alignment value.
658   std::map<std::string, unsigned> SectionMap;
659   std::map<std::string, unsigned> GCMap;
660   unsigned MaxAlignment = 0;
661   unsigned MaxGlobalType = 0;
662   for (const GlobalValue &GV : M->globals()) {
663     MaxAlignment = std::max(MaxAlignment, GV.getAlignment());
664     MaxGlobalType = std::max(MaxGlobalType, VE.getTypeID(GV.getValueType()));
665     if (GV.hasSection()) {
666       // Give section names unique ID's.
667       unsigned &Entry = SectionMap[GV.getSection()];
668       if (!Entry) {
669         WriteStringRecord(bitc::MODULE_CODE_SECTIONNAME, GV.getSection(),
670                           0/*TODO*/, Stream);
671         Entry = SectionMap.size();
672       }
673     }
674   }
675   for (const Function &F : *M) {
676     MaxAlignment = std::max(MaxAlignment, F.getAlignment());
677     if (F.hasSection()) {
678       // Give section names unique ID's.
679       unsigned &Entry = SectionMap[F.getSection()];
680       if (!Entry) {
681         WriteStringRecord(bitc::MODULE_CODE_SECTIONNAME, F.getSection(),
682                           0/*TODO*/, Stream);
683         Entry = SectionMap.size();
684       }
685     }
686     if (F.hasGC()) {
687       // Same for GC names.
688       unsigned &Entry = GCMap[F.getGC()];
689       if (!Entry) {
690         WriteStringRecord(bitc::MODULE_CODE_GCNAME, F.getGC(),
691                           0/*TODO*/, Stream);
692         Entry = GCMap.size();
693       }
694     }
695   }
696 
697   // Emit abbrev for globals, now that we know # sections and max alignment.
698   unsigned SimpleGVarAbbrev = 0;
699   if (!M->global_empty()) {
700     // Add an abbrev for common globals with no visibility or thread localness.
701     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
702     Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_GLOBALVAR));
703     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
704                               Log2_32_Ceil(MaxGlobalType+1)));
705     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // AddrSpace << 2
706                                                            //| explicitType << 1
707                                                            //| constant
708     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // Initializer.
709     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 5)); // Linkage.
710     if (MaxAlignment == 0)                                 // Alignment.
711       Abbv->Add(BitCodeAbbrevOp(0));
712     else {
713       unsigned MaxEncAlignment = Log2_32(MaxAlignment)+1;
714       Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
715                                Log2_32_Ceil(MaxEncAlignment+1)));
716     }
717     if (SectionMap.empty())                                    // Section.
718       Abbv->Add(BitCodeAbbrevOp(0));
719     else
720       Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
721                                Log2_32_Ceil(SectionMap.size()+1)));
722     // Don't bother emitting vis + thread local.
723     SimpleGVarAbbrev = Stream.EmitAbbrev(Abbv);
724   }
725 
726   // Emit the global variable information.
727   SmallVector<unsigned, 64> Vals;
728   for (const GlobalVariable &GV : M->globals()) {
729     unsigned AbbrevToUse = 0;
730 
731     // GLOBALVAR: [type, isconst, initid,
732     //             linkage, alignment, section, visibility, threadlocal,
733     //             unnamed_addr, externally_initialized, dllstorageclass,
734     //             comdat]
735     Vals.push_back(VE.getTypeID(GV.getValueType()));
736     Vals.push_back(GV.getType()->getAddressSpace() << 2 | 2 | GV.isConstant());
737     Vals.push_back(GV.isDeclaration() ? 0 :
738                    (VE.getValueID(GV.getInitializer()) + 1));
739     Vals.push_back(getEncodedLinkage(GV));
740     Vals.push_back(Log2_32(GV.getAlignment())+1);
741     Vals.push_back(GV.hasSection() ? SectionMap[GV.getSection()] : 0);
742     if (GV.isThreadLocal() ||
743         GV.getVisibility() != GlobalValue::DefaultVisibility ||
744         GV.hasUnnamedAddr() || GV.isExternallyInitialized() ||
745         GV.getDLLStorageClass() != GlobalValue::DefaultStorageClass ||
746         GV.hasComdat()) {
747       Vals.push_back(getEncodedVisibility(GV));
748       Vals.push_back(getEncodedThreadLocalMode(GV));
749       Vals.push_back(GV.hasUnnamedAddr());
750       Vals.push_back(GV.isExternallyInitialized());
751       Vals.push_back(getEncodedDLLStorageClass(GV));
752       Vals.push_back(GV.hasComdat() ? VE.getComdatID(GV.getComdat()) : 0);
753     } else {
754       AbbrevToUse = SimpleGVarAbbrev;
755     }
756 
757     Stream.EmitRecord(bitc::MODULE_CODE_GLOBALVAR, Vals, AbbrevToUse);
758     Vals.clear();
759   }
760 
761   // Emit the function proto information.
762   for (const Function &F : *M) {
763     // FUNCTION:  [type, callingconv, isproto, linkage, paramattrs, alignment,
764     //             section, visibility, gc, unnamed_addr, prologuedata,
765     //             dllstorageclass, comdat, prefixdata, personalityfn]
766     Vals.push_back(VE.getTypeID(F.getFunctionType()));
767     Vals.push_back(F.getCallingConv());
768     Vals.push_back(F.isDeclaration());
769     Vals.push_back(getEncodedLinkage(F));
770     Vals.push_back(VE.getAttributeID(F.getAttributes()));
771     Vals.push_back(Log2_32(F.getAlignment())+1);
772     Vals.push_back(F.hasSection() ? SectionMap[F.getSection()] : 0);
773     Vals.push_back(getEncodedVisibility(F));
774     Vals.push_back(F.hasGC() ? GCMap[F.getGC()] : 0);
775     Vals.push_back(F.hasUnnamedAddr());
776     Vals.push_back(F.hasPrologueData() ? (VE.getValueID(F.getPrologueData()) + 1)
777                                        : 0);
778     Vals.push_back(getEncodedDLLStorageClass(F));
779     Vals.push_back(F.hasComdat() ? VE.getComdatID(F.getComdat()) : 0);
780     Vals.push_back(F.hasPrefixData() ? (VE.getValueID(F.getPrefixData()) + 1)
781                                      : 0);
782     Vals.push_back(
783         F.hasPersonalityFn() ? (VE.getValueID(F.getPersonalityFn()) + 1) : 0);
784 
785     unsigned AbbrevToUse = 0;
786     Stream.EmitRecord(bitc::MODULE_CODE_FUNCTION, Vals, AbbrevToUse);
787     Vals.clear();
788   }
789 
790   // Emit the alias information.
791   for (const GlobalAlias &A : M->aliases()) {
792     // ALIAS: [alias type, aliasee val#, linkage, visibility]
793     Vals.push_back(VE.getTypeID(A.getValueType()));
794     Vals.push_back(A.getType()->getAddressSpace());
795     Vals.push_back(VE.getValueID(A.getAliasee()));
796     Vals.push_back(getEncodedLinkage(A));
797     Vals.push_back(getEncodedVisibility(A));
798     Vals.push_back(getEncodedDLLStorageClass(A));
799     Vals.push_back(getEncodedThreadLocalMode(A));
800     Vals.push_back(A.hasUnnamedAddr());
801     unsigned AbbrevToUse = 0;
802     Stream.EmitRecord(bitc::MODULE_CODE_ALIAS, Vals, AbbrevToUse);
803     Vals.clear();
804   }
805 
806   // Emit the module's source file name.
807   {
808     StringEncoding Bits = getStringEncoding(M->getSourceFileName().data(),
809                                             M->getSourceFileName().size());
810     BitCodeAbbrevOp AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8);
811     if (Bits == SE_Char6)
812       AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Char6);
813     else if (Bits == SE_Fixed7)
814       AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7);
815 
816     // MODULE_CODE_SOURCE_FILENAME: [namechar x N]
817     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
818     Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_SOURCE_FILENAME));
819     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
820     Abbv->Add(AbbrevOpToUse);
821     unsigned FilenameAbbrev = Stream.EmitAbbrev(Abbv);
822 
823     for (const auto P : M->getSourceFileName())
824       Vals.push_back((unsigned char)P);
825 
826     // Emit the finished record.
827     Stream.EmitRecord(bitc::MODULE_CODE_SOURCE_FILENAME, Vals, FilenameAbbrev);
828     Vals.clear();
829   }
830 
831   // If we have a VST, write the VSTOFFSET record placeholder and return
832   // its offset.
833   if (M->getValueSymbolTable().empty())
834     return 0;
835   return WriteValueSymbolTableForwardDecl(Stream);
836 }
837 
838 static uint64_t GetOptimizationFlags(const Value *V) {
839   uint64_t Flags = 0;
840 
841   if (const auto *OBO = dyn_cast<OverflowingBinaryOperator>(V)) {
842     if (OBO->hasNoSignedWrap())
843       Flags |= 1 << bitc::OBO_NO_SIGNED_WRAP;
844     if (OBO->hasNoUnsignedWrap())
845       Flags |= 1 << bitc::OBO_NO_UNSIGNED_WRAP;
846   } else if (const auto *PEO = dyn_cast<PossiblyExactOperator>(V)) {
847     if (PEO->isExact())
848       Flags |= 1 << bitc::PEO_EXACT;
849   } else if (const auto *FPMO = dyn_cast<FPMathOperator>(V)) {
850     if (FPMO->hasUnsafeAlgebra())
851       Flags |= FastMathFlags::UnsafeAlgebra;
852     if (FPMO->hasNoNaNs())
853       Flags |= FastMathFlags::NoNaNs;
854     if (FPMO->hasNoInfs())
855       Flags |= FastMathFlags::NoInfs;
856     if (FPMO->hasNoSignedZeros())
857       Flags |= FastMathFlags::NoSignedZeros;
858     if (FPMO->hasAllowReciprocal())
859       Flags |= FastMathFlags::AllowReciprocal;
860   }
861 
862   return Flags;
863 }
864 
865 static void WriteValueAsMetadata(const ValueAsMetadata *MD,
866                                  const ValueEnumerator &VE,
867                                  BitstreamWriter &Stream,
868                                  SmallVectorImpl<uint64_t> &Record) {
869   // Mimic an MDNode with a value as one operand.
870   Value *V = MD->getValue();
871   Record.push_back(VE.getTypeID(V->getType()));
872   Record.push_back(VE.getValueID(V));
873   Stream.EmitRecord(bitc::METADATA_VALUE, Record, 0);
874   Record.clear();
875 }
876 
877 static void WriteMDTuple(const MDTuple *N, const ValueEnumerator &VE,
878                          BitstreamWriter &Stream,
879                          SmallVectorImpl<uint64_t> &Record, unsigned Abbrev) {
880   for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i) {
881     Metadata *MD = N->getOperand(i);
882     assert(!(MD && isa<LocalAsMetadata>(MD)) &&
883            "Unexpected function-local metadata");
884     Record.push_back(VE.getMetadataOrNullID(MD));
885   }
886   Stream.EmitRecord(N->isDistinct() ? bitc::METADATA_DISTINCT_NODE
887                                     : bitc::METADATA_NODE,
888                     Record, Abbrev);
889   Record.clear();
890 }
891 
892 static unsigned createDILocationAbbrev(BitstreamWriter &Stream) {
893   // Assume the column is usually under 128, and always output the inlined-at
894   // location (it's never more expensive than building an array size 1).
895   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
896   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_LOCATION));
897   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
898   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
899   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
900   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
901   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
902   return Stream.EmitAbbrev(Abbv);
903 }
904 
905 static void WriteDILocation(const DILocation *N, const ValueEnumerator &VE,
906                             BitstreamWriter &Stream,
907                             SmallVectorImpl<uint64_t> &Record,
908                             unsigned &Abbrev) {
909   if (!Abbrev)
910     Abbrev = createDILocationAbbrev(Stream);
911 
912   Record.push_back(N->isDistinct());
913   Record.push_back(N->getLine());
914   Record.push_back(N->getColumn());
915   Record.push_back(VE.getMetadataID(N->getScope()));
916   Record.push_back(VE.getMetadataOrNullID(N->getInlinedAt()));
917 
918   Stream.EmitRecord(bitc::METADATA_LOCATION, Record, Abbrev);
919   Record.clear();
920 }
921 
922 static unsigned createGenericDINodeAbbrev(BitstreamWriter &Stream) {
923   // Assume the column is usually under 128, and always output the inlined-at
924   // location (it's never more expensive than building an array size 1).
925   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
926   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_GENERIC_DEBUG));
927   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
928   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
929   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
930   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
931   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
932   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
933   return Stream.EmitAbbrev(Abbv);
934 }
935 
936 static void WriteGenericDINode(const GenericDINode *N,
937                                const ValueEnumerator &VE,
938                                BitstreamWriter &Stream,
939                                SmallVectorImpl<uint64_t> &Record,
940                                unsigned &Abbrev) {
941   if (!Abbrev)
942     Abbrev = createGenericDINodeAbbrev(Stream);
943 
944   Record.push_back(N->isDistinct());
945   Record.push_back(N->getTag());
946   Record.push_back(0); // Per-tag version field; unused for now.
947 
948   for (auto &I : N->operands())
949     Record.push_back(VE.getMetadataOrNullID(I));
950 
951   Stream.EmitRecord(bitc::METADATA_GENERIC_DEBUG, Record, Abbrev);
952   Record.clear();
953 }
954 
955 static uint64_t rotateSign(int64_t I) {
956   uint64_t U = I;
957   return I < 0 ? ~(U << 1) : U << 1;
958 }
959 
960 static void WriteDISubrange(const DISubrange *N, const ValueEnumerator &,
961                             BitstreamWriter &Stream,
962                             SmallVectorImpl<uint64_t> &Record,
963                             unsigned Abbrev) {
964   Record.push_back(N->isDistinct());
965   Record.push_back(N->getCount());
966   Record.push_back(rotateSign(N->getLowerBound()));
967 
968   Stream.EmitRecord(bitc::METADATA_SUBRANGE, Record, Abbrev);
969   Record.clear();
970 }
971 
972 static void WriteDIEnumerator(const DIEnumerator *N, const ValueEnumerator &VE,
973                               BitstreamWriter &Stream,
974                               SmallVectorImpl<uint64_t> &Record,
975                               unsigned Abbrev) {
976   Record.push_back(N->isDistinct());
977   Record.push_back(rotateSign(N->getValue()));
978   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
979 
980   Stream.EmitRecord(bitc::METADATA_ENUMERATOR, Record, Abbrev);
981   Record.clear();
982 }
983 
984 static void WriteDIBasicType(const DIBasicType *N, const ValueEnumerator &VE,
985                              BitstreamWriter &Stream,
986                              SmallVectorImpl<uint64_t> &Record,
987                              unsigned Abbrev) {
988   Record.push_back(N->isDistinct());
989   Record.push_back(N->getTag());
990   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
991   Record.push_back(N->getSizeInBits());
992   Record.push_back(N->getAlignInBits());
993   Record.push_back(N->getEncoding());
994 
995   Stream.EmitRecord(bitc::METADATA_BASIC_TYPE, Record, Abbrev);
996   Record.clear();
997 }
998 
999 static void WriteDIDerivedType(const DIDerivedType *N,
1000                                const ValueEnumerator &VE,
1001                                BitstreamWriter &Stream,
1002                                SmallVectorImpl<uint64_t> &Record,
1003                                unsigned Abbrev) {
1004   Record.push_back(N->isDistinct());
1005   Record.push_back(N->getTag());
1006   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1007   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1008   Record.push_back(N->getLine());
1009   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1010   Record.push_back(VE.getMetadataOrNullID(N->getBaseType()));
1011   Record.push_back(N->getSizeInBits());
1012   Record.push_back(N->getAlignInBits());
1013   Record.push_back(N->getOffsetInBits());
1014   Record.push_back(N->getFlags());
1015   Record.push_back(VE.getMetadataOrNullID(N->getExtraData()));
1016 
1017   Stream.EmitRecord(bitc::METADATA_DERIVED_TYPE, Record, Abbrev);
1018   Record.clear();
1019 }
1020 
1021 static void WriteDICompositeType(const DICompositeType *N,
1022                                  const ValueEnumerator &VE,
1023                                  BitstreamWriter &Stream,
1024                                  SmallVectorImpl<uint64_t> &Record,
1025                                  unsigned Abbrev) {
1026   Record.push_back(N->isDistinct());
1027   Record.push_back(N->getTag());
1028   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1029   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1030   Record.push_back(N->getLine());
1031   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1032   Record.push_back(VE.getMetadataOrNullID(N->getBaseType()));
1033   Record.push_back(N->getSizeInBits());
1034   Record.push_back(N->getAlignInBits());
1035   Record.push_back(N->getOffsetInBits());
1036   Record.push_back(N->getFlags());
1037   Record.push_back(VE.getMetadataOrNullID(N->getElements().get()));
1038   Record.push_back(N->getRuntimeLang());
1039   Record.push_back(VE.getMetadataOrNullID(N->getVTableHolder()));
1040   Record.push_back(VE.getMetadataOrNullID(N->getTemplateParams().get()));
1041   Record.push_back(VE.getMetadataOrNullID(N->getRawIdentifier()));
1042 
1043   Stream.EmitRecord(bitc::METADATA_COMPOSITE_TYPE, Record, Abbrev);
1044   Record.clear();
1045 }
1046 
1047 static void WriteDISubroutineType(const DISubroutineType *N,
1048                                   const ValueEnumerator &VE,
1049                                   BitstreamWriter &Stream,
1050                                   SmallVectorImpl<uint64_t> &Record,
1051                                   unsigned Abbrev) {
1052   Record.push_back(N->isDistinct());
1053   Record.push_back(N->getFlags());
1054   Record.push_back(VE.getMetadataOrNullID(N->getTypeArray().get()));
1055 
1056   Stream.EmitRecord(bitc::METADATA_SUBROUTINE_TYPE, Record, Abbrev);
1057   Record.clear();
1058 }
1059 
1060 static void WriteDIFile(const DIFile *N, const ValueEnumerator &VE,
1061                         BitstreamWriter &Stream,
1062                         SmallVectorImpl<uint64_t> &Record, unsigned Abbrev) {
1063   Record.push_back(N->isDistinct());
1064   Record.push_back(VE.getMetadataOrNullID(N->getRawFilename()));
1065   Record.push_back(VE.getMetadataOrNullID(N->getRawDirectory()));
1066 
1067   Stream.EmitRecord(bitc::METADATA_FILE, Record, Abbrev);
1068   Record.clear();
1069 }
1070 
1071 static void WriteDICompileUnit(const DICompileUnit *N,
1072                                const ValueEnumerator &VE,
1073                                BitstreamWriter &Stream,
1074                                SmallVectorImpl<uint64_t> &Record,
1075                                unsigned Abbrev) {
1076   assert(N->isDistinct() && "Expected distinct compile units");
1077   Record.push_back(/* IsDistinct */ true);
1078   Record.push_back(N->getSourceLanguage());
1079   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1080   Record.push_back(VE.getMetadataOrNullID(N->getRawProducer()));
1081   Record.push_back(N->isOptimized());
1082   Record.push_back(VE.getMetadataOrNullID(N->getRawFlags()));
1083   Record.push_back(N->getRuntimeVersion());
1084   Record.push_back(VE.getMetadataOrNullID(N->getRawSplitDebugFilename()));
1085   Record.push_back(N->getEmissionKind());
1086   Record.push_back(VE.getMetadataOrNullID(N->getEnumTypes().get()));
1087   Record.push_back(VE.getMetadataOrNullID(N->getRetainedTypes().get()));
1088   Record.push_back(VE.getMetadataOrNullID(N->getSubprograms().get()));
1089   Record.push_back(VE.getMetadataOrNullID(N->getGlobalVariables().get()));
1090   Record.push_back(VE.getMetadataOrNullID(N->getImportedEntities().get()));
1091   Record.push_back(N->getDWOId());
1092   Record.push_back(VE.getMetadataOrNullID(N->getMacros().get()));
1093 
1094   Stream.EmitRecord(bitc::METADATA_COMPILE_UNIT, Record, Abbrev);
1095   Record.clear();
1096 }
1097 
1098 static void WriteDISubprogram(const DISubprogram *N, const ValueEnumerator &VE,
1099                               BitstreamWriter &Stream,
1100                               SmallVectorImpl<uint64_t> &Record,
1101                               unsigned Abbrev) {
1102   Record.push_back(N->isDistinct());
1103   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1104   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1105   Record.push_back(VE.getMetadataOrNullID(N->getRawLinkageName()));
1106   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1107   Record.push_back(N->getLine());
1108   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1109   Record.push_back(N->isLocalToUnit());
1110   Record.push_back(N->isDefinition());
1111   Record.push_back(N->getScopeLine());
1112   Record.push_back(VE.getMetadataOrNullID(N->getContainingType()));
1113   Record.push_back(N->getVirtuality());
1114   Record.push_back(N->getVirtualIndex());
1115   Record.push_back(N->getFlags());
1116   Record.push_back(N->isOptimized());
1117   Record.push_back(VE.getMetadataOrNullID(N->getTemplateParams().get()));
1118   Record.push_back(VE.getMetadataOrNullID(N->getDeclaration()));
1119   Record.push_back(VE.getMetadataOrNullID(N->getVariables().get()));
1120 
1121   Stream.EmitRecord(bitc::METADATA_SUBPROGRAM, Record, Abbrev);
1122   Record.clear();
1123 }
1124 
1125 static void WriteDILexicalBlock(const DILexicalBlock *N,
1126                                 const ValueEnumerator &VE,
1127                                 BitstreamWriter &Stream,
1128                                 SmallVectorImpl<uint64_t> &Record,
1129                                 unsigned Abbrev) {
1130   Record.push_back(N->isDistinct());
1131   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1132   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1133   Record.push_back(N->getLine());
1134   Record.push_back(N->getColumn());
1135 
1136   Stream.EmitRecord(bitc::METADATA_LEXICAL_BLOCK, Record, Abbrev);
1137   Record.clear();
1138 }
1139 
1140 static void WriteDILexicalBlockFile(const DILexicalBlockFile *N,
1141                                     const ValueEnumerator &VE,
1142                                     BitstreamWriter &Stream,
1143                                     SmallVectorImpl<uint64_t> &Record,
1144                                     unsigned Abbrev) {
1145   Record.push_back(N->isDistinct());
1146   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1147   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1148   Record.push_back(N->getDiscriminator());
1149 
1150   Stream.EmitRecord(bitc::METADATA_LEXICAL_BLOCK_FILE, Record, Abbrev);
1151   Record.clear();
1152 }
1153 
1154 static void WriteDINamespace(const DINamespace *N, const ValueEnumerator &VE,
1155                              BitstreamWriter &Stream,
1156                              SmallVectorImpl<uint64_t> &Record,
1157                              unsigned Abbrev) {
1158   Record.push_back(N->isDistinct());
1159   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1160   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1161   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1162   Record.push_back(N->getLine());
1163 
1164   Stream.EmitRecord(bitc::METADATA_NAMESPACE, Record, Abbrev);
1165   Record.clear();
1166 }
1167 
1168 static void WriteDIMacro(const DIMacro *N, const ValueEnumerator &VE,
1169                          BitstreamWriter &Stream,
1170                          SmallVectorImpl<uint64_t> &Record, unsigned Abbrev) {
1171   Record.push_back(N->isDistinct());
1172   Record.push_back(N->getMacinfoType());
1173   Record.push_back(N->getLine());
1174   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1175   Record.push_back(VE.getMetadataOrNullID(N->getRawValue()));
1176 
1177   Stream.EmitRecord(bitc::METADATA_MACRO, Record, Abbrev);
1178   Record.clear();
1179 }
1180 
1181 static void WriteDIMacroFile(const DIMacroFile *N, const ValueEnumerator &VE,
1182                              BitstreamWriter &Stream,
1183                              SmallVectorImpl<uint64_t> &Record,
1184                              unsigned Abbrev) {
1185   Record.push_back(N->isDistinct());
1186   Record.push_back(N->getMacinfoType());
1187   Record.push_back(N->getLine());
1188   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1189   Record.push_back(VE.getMetadataOrNullID(N->getElements().get()));
1190 
1191   Stream.EmitRecord(bitc::METADATA_MACRO_FILE, Record, Abbrev);
1192   Record.clear();
1193 }
1194 
1195 static void WriteDIModule(const DIModule *N, const ValueEnumerator &VE,
1196                           BitstreamWriter &Stream,
1197                           SmallVectorImpl<uint64_t> &Record, unsigned Abbrev) {
1198   Record.push_back(N->isDistinct());
1199   for (auto &I : N->operands())
1200     Record.push_back(VE.getMetadataOrNullID(I));
1201 
1202   Stream.EmitRecord(bitc::METADATA_MODULE, Record, Abbrev);
1203   Record.clear();
1204 }
1205 
1206 static void WriteDITemplateTypeParameter(const DITemplateTypeParameter *N,
1207                                          const ValueEnumerator &VE,
1208                                          BitstreamWriter &Stream,
1209                                          SmallVectorImpl<uint64_t> &Record,
1210                                          unsigned Abbrev) {
1211   Record.push_back(N->isDistinct());
1212   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1213   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1214 
1215   Stream.EmitRecord(bitc::METADATA_TEMPLATE_TYPE, Record, Abbrev);
1216   Record.clear();
1217 }
1218 
1219 static void WriteDITemplateValueParameter(const DITemplateValueParameter *N,
1220                                           const ValueEnumerator &VE,
1221                                           BitstreamWriter &Stream,
1222                                           SmallVectorImpl<uint64_t> &Record,
1223                                           unsigned Abbrev) {
1224   Record.push_back(N->isDistinct());
1225   Record.push_back(N->getTag());
1226   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1227   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1228   Record.push_back(VE.getMetadataOrNullID(N->getValue()));
1229 
1230   Stream.EmitRecord(bitc::METADATA_TEMPLATE_VALUE, Record, Abbrev);
1231   Record.clear();
1232 }
1233 
1234 static void WriteDIGlobalVariable(const DIGlobalVariable *N,
1235                                   const ValueEnumerator &VE,
1236                                   BitstreamWriter &Stream,
1237                                   SmallVectorImpl<uint64_t> &Record,
1238                                   unsigned Abbrev) {
1239   Record.push_back(N->isDistinct());
1240   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1241   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1242   Record.push_back(VE.getMetadataOrNullID(N->getRawLinkageName()));
1243   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1244   Record.push_back(N->getLine());
1245   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1246   Record.push_back(N->isLocalToUnit());
1247   Record.push_back(N->isDefinition());
1248   Record.push_back(VE.getMetadataOrNullID(N->getRawVariable()));
1249   Record.push_back(VE.getMetadataOrNullID(N->getStaticDataMemberDeclaration()));
1250 
1251   Stream.EmitRecord(bitc::METADATA_GLOBAL_VAR, Record, Abbrev);
1252   Record.clear();
1253 }
1254 
1255 static void WriteDILocalVariable(const DILocalVariable *N,
1256                                  const ValueEnumerator &VE,
1257                                  BitstreamWriter &Stream,
1258                                  SmallVectorImpl<uint64_t> &Record,
1259                                  unsigned Abbrev) {
1260   Record.push_back(N->isDistinct());
1261   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1262   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1263   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1264   Record.push_back(N->getLine());
1265   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1266   Record.push_back(N->getArg());
1267   Record.push_back(N->getFlags());
1268 
1269   Stream.EmitRecord(bitc::METADATA_LOCAL_VAR, Record, Abbrev);
1270   Record.clear();
1271 }
1272 
1273 static void WriteDIExpression(const DIExpression *N, const ValueEnumerator &,
1274                               BitstreamWriter &Stream,
1275                               SmallVectorImpl<uint64_t> &Record,
1276                               unsigned Abbrev) {
1277   Record.reserve(N->getElements().size() + 1);
1278 
1279   Record.push_back(N->isDistinct());
1280   Record.append(N->elements_begin(), N->elements_end());
1281 
1282   Stream.EmitRecord(bitc::METADATA_EXPRESSION, Record, Abbrev);
1283   Record.clear();
1284 }
1285 
1286 static void WriteDIObjCProperty(const DIObjCProperty *N,
1287                                 const ValueEnumerator &VE,
1288                                 BitstreamWriter &Stream,
1289                                 SmallVectorImpl<uint64_t> &Record,
1290                                 unsigned Abbrev) {
1291   Record.push_back(N->isDistinct());
1292   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1293   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1294   Record.push_back(N->getLine());
1295   Record.push_back(VE.getMetadataOrNullID(N->getRawSetterName()));
1296   Record.push_back(VE.getMetadataOrNullID(N->getRawGetterName()));
1297   Record.push_back(N->getAttributes());
1298   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1299 
1300   Stream.EmitRecord(bitc::METADATA_OBJC_PROPERTY, Record, Abbrev);
1301   Record.clear();
1302 }
1303 
1304 static void WriteDIImportedEntity(const DIImportedEntity *N,
1305                                   const ValueEnumerator &VE,
1306                                   BitstreamWriter &Stream,
1307                                   SmallVectorImpl<uint64_t> &Record,
1308                                   unsigned Abbrev) {
1309   Record.push_back(N->isDistinct());
1310   Record.push_back(N->getTag());
1311   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1312   Record.push_back(VE.getMetadataOrNullID(N->getEntity()));
1313   Record.push_back(N->getLine());
1314   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1315 
1316   Stream.EmitRecord(bitc::METADATA_IMPORTED_ENTITY, Record, Abbrev);
1317   Record.clear();
1318 }
1319 
1320 static unsigned createNamedMetadataAbbrev(BitstreamWriter &Stream) {
1321   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1322   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_NAME));
1323   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1324   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
1325   return Stream.EmitAbbrev(Abbv);
1326 }
1327 
1328 static void writeNamedMetadata(const Module &M, const ValueEnumerator &VE,
1329                                BitstreamWriter &Stream,
1330                                SmallVectorImpl<uint64_t> &Record) {
1331   if (M.named_metadata_empty())
1332     return;
1333 
1334   unsigned Abbrev = createNamedMetadataAbbrev(Stream);
1335   for (const NamedMDNode &NMD : M.named_metadata()) {
1336     // Write name.
1337     StringRef Str = NMD.getName();
1338     Record.append(Str.bytes_begin(), Str.bytes_end());
1339     Stream.EmitRecord(bitc::METADATA_NAME, Record, Abbrev);
1340     Record.clear();
1341 
1342     // Write named metadata operands.
1343     for (const MDNode *N : NMD.operands())
1344       Record.push_back(VE.getMetadataID(N));
1345     Stream.EmitRecord(bitc::METADATA_NAMED_NODE, Record, 0);
1346     Record.clear();
1347   }
1348 }
1349 
1350 static unsigned createMDStringDataAbbrev(BitstreamWriter &Stream) {
1351   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1352   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_BULK_STRING_DATA));
1353   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob));
1354   return Stream.EmitAbbrev(Abbv);
1355 }
1356 
1357 static void emitMDStringBlob(unsigned DataAbbrev,
1358                              ArrayRef<const Metadata *> Strings,
1359                              BitstreamWriter &Stream,
1360                              SmallVectorImpl<uint64_t> &Record,
1361                              SmallString<4096> &Blob) {
1362   for (const Metadata *MD : Strings) {
1363     StringRef S = cast<MDString>(MD)->getString();
1364     Record.push_back(S.size());
1365     Blob.append(S.begin(), S.end());
1366   }
1367 
1368   Stream.EmitRecord(bitc::METADATA_BULK_STRING_SIZES, Record);
1369   Record.clear();
1370 
1371   Record.push_back(bitc::METADATA_BULK_STRING_DATA);
1372   Stream.EmitRecordWithBlob(DataAbbrev, Record, Blob);
1373   Record.clear();
1374 }
1375 
1376 /// Write out a section of records for MDString.
1377 ///
1378 /// All the MDString elements in a metadata block are emitted in bulk.  They're
1379 /// grouped into blocks, and each block is emitted with pair of records:
1380 ///
1381 ///   - SIZES: a list of the sizes of the strings in the block.
1382 ///   - DATA: the blob itself.
1383 static void writeMetadataStrings(ArrayRef<const Metadata *> Strings,
1384                                  BitstreamWriter &Stream,
1385                                  SmallVectorImpl<uint64_t> &Record) {
1386   if (Strings.empty())
1387     return;
1388 
1389   // Emit strings in large blocks to reduce record overhead.  Somewhat
1390   // arbitrarily, limit this to 512 strings per blob:
1391   //   - big enough to eliminate overhead;
1392   //   - small enough that the reader's SIZES record will stay within a page.
1393   const size_t NumStringsPerBlob = 512;
1394   Record.reserve(std::min(NumStringsPerBlob, Strings.size()));
1395 
1396   unsigned DataAbbrev = createMDStringDataAbbrev(Stream);
1397   SmallString<4096> Blob;
1398   while (Strings.size() > NumStringsPerBlob) {
1399     emitMDStringBlob(DataAbbrev, Strings.slice(0, NumStringsPerBlob), Stream,
1400                      Record, Blob);
1401     Strings = Strings.slice(NumStringsPerBlob);
1402   }
1403   if (!Strings.empty())
1404     emitMDStringBlob(DataAbbrev, Strings, Stream, Record, Blob);
1405 }
1406 
1407 static void WriteModuleMetadata(const Module &M,
1408                                 const ValueEnumerator &VE,
1409                                 BitstreamWriter &Stream) {
1410   if (VE.getMDs().empty() && M.named_metadata_empty())
1411     return;
1412 
1413   Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
1414 
1415   // Initialize MDNode abbreviations.
1416 #define HANDLE_MDNODE_LEAF(CLASS) unsigned CLASS##Abbrev = 0;
1417 #include "llvm/IR/Metadata.def"
1418 
1419   SmallVector<uint64_t, 64> Record;
1420   writeMetadataStrings(VE.getMDStrings(), Stream, Record);
1421   for (const Metadata *MD : VE.getNonMDStrings()) {
1422     if (const MDNode *N = dyn_cast<MDNode>(MD)) {
1423       assert(N->isResolved() && "Expected forward references to be resolved");
1424 
1425       switch (N->getMetadataID()) {
1426       default:
1427         llvm_unreachable("Invalid MDNode subclass");
1428 #define HANDLE_MDNODE_LEAF(CLASS)                                              \
1429   case Metadata::CLASS##Kind:                                                  \
1430     Write##CLASS(cast<CLASS>(N), VE, Stream, Record, CLASS##Abbrev);           \
1431     continue;
1432 #include "llvm/IR/Metadata.def"
1433       }
1434     }
1435     WriteValueAsMetadata(cast<ConstantAsMetadata>(MD), VE, Stream, Record);
1436   }
1437 
1438   writeNamedMetadata(M, VE, Stream, Record);
1439   Stream.ExitBlock();
1440 }
1441 
1442 static void WriteFunctionLocalMetadata(const Function &F,
1443                                        const ValueEnumerator &VE,
1444                                        BitstreamWriter &Stream) {
1445   bool StartedMetadataBlock = false;
1446   SmallVector<uint64_t, 64> Record;
1447   const SmallVectorImpl<const LocalAsMetadata *> &MDs =
1448       VE.getFunctionLocalMDs();
1449   for (unsigned i = 0, e = MDs.size(); i != e; ++i) {
1450     assert(MDs[i] && "Expected valid function-local metadata");
1451     if (!StartedMetadataBlock) {
1452       Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
1453       StartedMetadataBlock = true;
1454     }
1455     WriteValueAsMetadata(MDs[i], VE, Stream, Record);
1456   }
1457 
1458   if (StartedMetadataBlock)
1459     Stream.ExitBlock();
1460 }
1461 
1462 static void WriteMetadataAttachment(const Function &F,
1463                                     const ValueEnumerator &VE,
1464                                     BitstreamWriter &Stream) {
1465   Stream.EnterSubblock(bitc::METADATA_ATTACHMENT_ID, 3);
1466 
1467   SmallVector<uint64_t, 64> Record;
1468 
1469   // Write metadata attachments
1470   // METADATA_ATTACHMENT - [m x [value, [n x [id, mdnode]]]
1471   SmallVector<std::pair<unsigned, MDNode *>, 4> MDs;
1472   F.getAllMetadata(MDs);
1473   if (!MDs.empty()) {
1474     for (const auto &I : MDs) {
1475       Record.push_back(I.first);
1476       Record.push_back(VE.getMetadataID(I.second));
1477     }
1478     Stream.EmitRecord(bitc::METADATA_ATTACHMENT, Record, 0);
1479     Record.clear();
1480   }
1481 
1482   for (const BasicBlock &BB : F)
1483     for (const Instruction &I : BB) {
1484       MDs.clear();
1485       I.getAllMetadataOtherThanDebugLoc(MDs);
1486 
1487       // If no metadata, ignore instruction.
1488       if (MDs.empty()) continue;
1489 
1490       Record.push_back(VE.getInstructionID(&I));
1491 
1492       for (unsigned i = 0, e = MDs.size(); i != e; ++i) {
1493         Record.push_back(MDs[i].first);
1494         Record.push_back(VE.getMetadataID(MDs[i].second));
1495       }
1496       Stream.EmitRecord(bitc::METADATA_ATTACHMENT, Record, 0);
1497       Record.clear();
1498     }
1499 
1500   Stream.ExitBlock();
1501 }
1502 
1503 static void WriteModuleMetadataStore(const Module *M, BitstreamWriter &Stream) {
1504   SmallVector<uint64_t, 64> Record;
1505 
1506   // Write metadata kinds
1507   // METADATA_KIND - [n x [id, name]]
1508   SmallVector<StringRef, 8> Names;
1509   M->getMDKindNames(Names);
1510 
1511   if (Names.empty()) return;
1512 
1513   Stream.EnterSubblock(bitc::METADATA_KIND_BLOCK_ID, 3);
1514 
1515   for (unsigned MDKindID = 0, e = Names.size(); MDKindID != e; ++MDKindID) {
1516     Record.push_back(MDKindID);
1517     StringRef KName = Names[MDKindID];
1518     Record.append(KName.begin(), KName.end());
1519 
1520     Stream.EmitRecord(bitc::METADATA_KIND, Record, 0);
1521     Record.clear();
1522   }
1523 
1524   Stream.ExitBlock();
1525 }
1526 
1527 static void WriteOperandBundleTags(const Module *M, BitstreamWriter &Stream) {
1528   // Write metadata kinds
1529   //
1530   // OPERAND_BUNDLE_TAGS_BLOCK_ID : N x OPERAND_BUNDLE_TAG
1531   //
1532   // OPERAND_BUNDLE_TAG - [strchr x N]
1533 
1534   SmallVector<StringRef, 8> Tags;
1535   M->getOperandBundleTags(Tags);
1536 
1537   if (Tags.empty())
1538     return;
1539 
1540   Stream.EnterSubblock(bitc::OPERAND_BUNDLE_TAGS_BLOCK_ID, 3);
1541 
1542   SmallVector<uint64_t, 64> Record;
1543 
1544   for (auto Tag : Tags) {
1545     Record.append(Tag.begin(), Tag.end());
1546 
1547     Stream.EmitRecord(bitc::OPERAND_BUNDLE_TAG, Record, 0);
1548     Record.clear();
1549   }
1550 
1551   Stream.ExitBlock();
1552 }
1553 
1554 static void emitSignedInt64(SmallVectorImpl<uint64_t> &Vals, uint64_t V) {
1555   if ((int64_t)V >= 0)
1556     Vals.push_back(V << 1);
1557   else
1558     Vals.push_back((-V << 1) | 1);
1559 }
1560 
1561 static void WriteConstants(unsigned FirstVal, unsigned LastVal,
1562                            const ValueEnumerator &VE,
1563                            BitstreamWriter &Stream, bool isGlobal) {
1564   if (FirstVal == LastVal) return;
1565 
1566   Stream.EnterSubblock(bitc::CONSTANTS_BLOCK_ID, 4);
1567 
1568   unsigned AggregateAbbrev = 0;
1569   unsigned String8Abbrev = 0;
1570   unsigned CString7Abbrev = 0;
1571   unsigned CString6Abbrev = 0;
1572   // If this is a constant pool for the module, emit module-specific abbrevs.
1573   if (isGlobal) {
1574     // Abbrev for CST_CODE_AGGREGATE.
1575     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1576     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_AGGREGATE));
1577     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1578     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, Log2_32_Ceil(LastVal+1)));
1579     AggregateAbbrev = Stream.EmitAbbrev(Abbv);
1580 
1581     // Abbrev for CST_CODE_STRING.
1582     Abbv = new BitCodeAbbrev();
1583     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_STRING));
1584     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1585     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
1586     String8Abbrev = Stream.EmitAbbrev(Abbv);
1587     // Abbrev for CST_CODE_CSTRING.
1588     Abbv = new BitCodeAbbrev();
1589     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
1590     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1591     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
1592     CString7Abbrev = Stream.EmitAbbrev(Abbv);
1593     // Abbrev for CST_CODE_CSTRING.
1594     Abbv = new BitCodeAbbrev();
1595     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
1596     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1597     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
1598     CString6Abbrev = Stream.EmitAbbrev(Abbv);
1599   }
1600 
1601   SmallVector<uint64_t, 64> Record;
1602 
1603   const ValueEnumerator::ValueList &Vals = VE.getValues();
1604   Type *LastTy = nullptr;
1605   for (unsigned i = FirstVal; i != LastVal; ++i) {
1606     const Value *V = Vals[i].first;
1607     // If we need to switch types, do so now.
1608     if (V->getType() != LastTy) {
1609       LastTy = V->getType();
1610       Record.push_back(VE.getTypeID(LastTy));
1611       Stream.EmitRecord(bitc::CST_CODE_SETTYPE, Record,
1612                         CONSTANTS_SETTYPE_ABBREV);
1613       Record.clear();
1614     }
1615 
1616     if (const InlineAsm *IA = dyn_cast<InlineAsm>(V)) {
1617       Record.push_back(unsigned(IA->hasSideEffects()) |
1618                        unsigned(IA->isAlignStack()) << 1 |
1619                        unsigned(IA->getDialect()&1) << 2);
1620 
1621       // Add the asm string.
1622       const std::string &AsmStr = IA->getAsmString();
1623       Record.push_back(AsmStr.size());
1624       Record.append(AsmStr.begin(), AsmStr.end());
1625 
1626       // Add the constraint string.
1627       const std::string &ConstraintStr = IA->getConstraintString();
1628       Record.push_back(ConstraintStr.size());
1629       Record.append(ConstraintStr.begin(), ConstraintStr.end());
1630       Stream.EmitRecord(bitc::CST_CODE_INLINEASM, Record);
1631       Record.clear();
1632       continue;
1633     }
1634     const Constant *C = cast<Constant>(V);
1635     unsigned Code = -1U;
1636     unsigned AbbrevToUse = 0;
1637     if (C->isNullValue()) {
1638       Code = bitc::CST_CODE_NULL;
1639     } else if (isa<UndefValue>(C)) {
1640       Code = bitc::CST_CODE_UNDEF;
1641     } else if (const ConstantInt *IV = dyn_cast<ConstantInt>(C)) {
1642       if (IV->getBitWidth() <= 64) {
1643         uint64_t V = IV->getSExtValue();
1644         emitSignedInt64(Record, V);
1645         Code = bitc::CST_CODE_INTEGER;
1646         AbbrevToUse = CONSTANTS_INTEGER_ABBREV;
1647       } else {                             // Wide integers, > 64 bits in size.
1648         // We have an arbitrary precision integer value to write whose
1649         // bit width is > 64. However, in canonical unsigned integer
1650         // format it is likely that the high bits are going to be zero.
1651         // So, we only write the number of active words.
1652         unsigned NWords = IV->getValue().getActiveWords();
1653         const uint64_t *RawWords = IV->getValue().getRawData();
1654         for (unsigned i = 0; i != NWords; ++i) {
1655           emitSignedInt64(Record, RawWords[i]);
1656         }
1657         Code = bitc::CST_CODE_WIDE_INTEGER;
1658       }
1659     } else if (const ConstantFP *CFP = dyn_cast<ConstantFP>(C)) {
1660       Code = bitc::CST_CODE_FLOAT;
1661       Type *Ty = CFP->getType();
1662       if (Ty->isHalfTy() || Ty->isFloatTy() || Ty->isDoubleTy()) {
1663         Record.push_back(CFP->getValueAPF().bitcastToAPInt().getZExtValue());
1664       } else if (Ty->isX86_FP80Ty()) {
1665         // api needed to prevent premature destruction
1666         // bits are not in the same order as a normal i80 APInt, compensate.
1667         APInt api = CFP->getValueAPF().bitcastToAPInt();
1668         const uint64_t *p = api.getRawData();
1669         Record.push_back((p[1] << 48) | (p[0] >> 16));
1670         Record.push_back(p[0] & 0xffffLL);
1671       } else if (Ty->isFP128Ty() || Ty->isPPC_FP128Ty()) {
1672         APInt api = CFP->getValueAPF().bitcastToAPInt();
1673         const uint64_t *p = api.getRawData();
1674         Record.push_back(p[0]);
1675         Record.push_back(p[1]);
1676       } else {
1677         assert (0 && "Unknown FP type!");
1678       }
1679     } else if (isa<ConstantDataSequential>(C) &&
1680                cast<ConstantDataSequential>(C)->isString()) {
1681       const ConstantDataSequential *Str = cast<ConstantDataSequential>(C);
1682       // Emit constant strings specially.
1683       unsigned NumElts = Str->getNumElements();
1684       // If this is a null-terminated string, use the denser CSTRING encoding.
1685       if (Str->isCString()) {
1686         Code = bitc::CST_CODE_CSTRING;
1687         --NumElts;  // Don't encode the null, which isn't allowed by char6.
1688       } else {
1689         Code = bitc::CST_CODE_STRING;
1690         AbbrevToUse = String8Abbrev;
1691       }
1692       bool isCStr7 = Code == bitc::CST_CODE_CSTRING;
1693       bool isCStrChar6 = Code == bitc::CST_CODE_CSTRING;
1694       for (unsigned i = 0; i != NumElts; ++i) {
1695         unsigned char V = Str->getElementAsInteger(i);
1696         Record.push_back(V);
1697         isCStr7 &= (V & 128) == 0;
1698         if (isCStrChar6)
1699           isCStrChar6 = BitCodeAbbrevOp::isChar6(V);
1700       }
1701 
1702       if (isCStrChar6)
1703         AbbrevToUse = CString6Abbrev;
1704       else if (isCStr7)
1705         AbbrevToUse = CString7Abbrev;
1706     } else if (const ConstantDataSequential *CDS =
1707                   dyn_cast<ConstantDataSequential>(C)) {
1708       Code = bitc::CST_CODE_DATA;
1709       Type *EltTy = CDS->getType()->getElementType();
1710       if (isa<IntegerType>(EltTy)) {
1711         for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i)
1712           Record.push_back(CDS->getElementAsInteger(i));
1713       } else {
1714         for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i)
1715           Record.push_back(
1716               CDS->getElementAsAPFloat(i).bitcastToAPInt().getLimitedValue());
1717       }
1718     } else if (isa<ConstantArray>(C) || isa<ConstantStruct>(C) ||
1719                isa<ConstantVector>(C)) {
1720       Code = bitc::CST_CODE_AGGREGATE;
1721       for (const Value *Op : C->operands())
1722         Record.push_back(VE.getValueID(Op));
1723       AbbrevToUse = AggregateAbbrev;
1724     } else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
1725       switch (CE->getOpcode()) {
1726       default:
1727         if (Instruction::isCast(CE->getOpcode())) {
1728           Code = bitc::CST_CODE_CE_CAST;
1729           Record.push_back(GetEncodedCastOpcode(CE->getOpcode()));
1730           Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
1731           Record.push_back(VE.getValueID(C->getOperand(0)));
1732           AbbrevToUse = CONSTANTS_CE_CAST_Abbrev;
1733         } else {
1734           assert(CE->getNumOperands() == 2 && "Unknown constant expr!");
1735           Code = bitc::CST_CODE_CE_BINOP;
1736           Record.push_back(GetEncodedBinaryOpcode(CE->getOpcode()));
1737           Record.push_back(VE.getValueID(C->getOperand(0)));
1738           Record.push_back(VE.getValueID(C->getOperand(1)));
1739           uint64_t Flags = GetOptimizationFlags(CE);
1740           if (Flags != 0)
1741             Record.push_back(Flags);
1742         }
1743         break;
1744       case Instruction::GetElementPtr: {
1745         Code = bitc::CST_CODE_CE_GEP;
1746         const auto *GO = cast<GEPOperator>(C);
1747         if (GO->isInBounds())
1748           Code = bitc::CST_CODE_CE_INBOUNDS_GEP;
1749         Record.push_back(VE.getTypeID(GO->getSourceElementType()));
1750         for (unsigned i = 0, e = CE->getNumOperands(); i != e; ++i) {
1751           Record.push_back(VE.getTypeID(C->getOperand(i)->getType()));
1752           Record.push_back(VE.getValueID(C->getOperand(i)));
1753         }
1754         break;
1755       }
1756       case Instruction::Select:
1757         Code = bitc::CST_CODE_CE_SELECT;
1758         Record.push_back(VE.getValueID(C->getOperand(0)));
1759         Record.push_back(VE.getValueID(C->getOperand(1)));
1760         Record.push_back(VE.getValueID(C->getOperand(2)));
1761         break;
1762       case Instruction::ExtractElement:
1763         Code = bitc::CST_CODE_CE_EXTRACTELT;
1764         Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
1765         Record.push_back(VE.getValueID(C->getOperand(0)));
1766         Record.push_back(VE.getTypeID(C->getOperand(1)->getType()));
1767         Record.push_back(VE.getValueID(C->getOperand(1)));
1768         break;
1769       case Instruction::InsertElement:
1770         Code = bitc::CST_CODE_CE_INSERTELT;
1771         Record.push_back(VE.getValueID(C->getOperand(0)));
1772         Record.push_back(VE.getValueID(C->getOperand(1)));
1773         Record.push_back(VE.getTypeID(C->getOperand(2)->getType()));
1774         Record.push_back(VE.getValueID(C->getOperand(2)));
1775         break;
1776       case Instruction::ShuffleVector:
1777         // If the return type and argument types are the same, this is a
1778         // standard shufflevector instruction.  If the types are different,
1779         // then the shuffle is widening or truncating the input vectors, and
1780         // the argument type must also be encoded.
1781         if (C->getType() == C->getOperand(0)->getType()) {
1782           Code = bitc::CST_CODE_CE_SHUFFLEVEC;
1783         } else {
1784           Code = bitc::CST_CODE_CE_SHUFVEC_EX;
1785           Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
1786         }
1787         Record.push_back(VE.getValueID(C->getOperand(0)));
1788         Record.push_back(VE.getValueID(C->getOperand(1)));
1789         Record.push_back(VE.getValueID(C->getOperand(2)));
1790         break;
1791       case Instruction::ICmp:
1792       case Instruction::FCmp:
1793         Code = bitc::CST_CODE_CE_CMP;
1794         Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
1795         Record.push_back(VE.getValueID(C->getOperand(0)));
1796         Record.push_back(VE.getValueID(C->getOperand(1)));
1797         Record.push_back(CE->getPredicate());
1798         break;
1799       }
1800     } else if (const BlockAddress *BA = dyn_cast<BlockAddress>(C)) {
1801       Code = bitc::CST_CODE_BLOCKADDRESS;
1802       Record.push_back(VE.getTypeID(BA->getFunction()->getType()));
1803       Record.push_back(VE.getValueID(BA->getFunction()));
1804       Record.push_back(VE.getGlobalBasicBlockID(BA->getBasicBlock()));
1805     } else {
1806 #ifndef NDEBUG
1807       C->dump();
1808 #endif
1809       llvm_unreachable("Unknown constant!");
1810     }
1811     Stream.EmitRecord(Code, Record, AbbrevToUse);
1812     Record.clear();
1813   }
1814 
1815   Stream.ExitBlock();
1816 }
1817 
1818 static void WriteModuleConstants(const ValueEnumerator &VE,
1819                                  BitstreamWriter &Stream) {
1820   const ValueEnumerator::ValueList &Vals = VE.getValues();
1821 
1822   // Find the first constant to emit, which is the first non-globalvalue value.
1823   // We know globalvalues have been emitted by WriteModuleInfo.
1824   for (unsigned i = 0, e = Vals.size(); i != e; ++i) {
1825     if (!isa<GlobalValue>(Vals[i].first)) {
1826       WriteConstants(i, Vals.size(), VE, Stream, true);
1827       return;
1828     }
1829   }
1830 }
1831 
1832 /// PushValueAndType - The file has to encode both the value and type id for
1833 /// many values, because we need to know what type to create for forward
1834 /// references.  However, most operands are not forward references, so this type
1835 /// field is not needed.
1836 ///
1837 /// This function adds V's value ID to Vals.  If the value ID is higher than the
1838 /// instruction ID, then it is a forward reference, and it also includes the
1839 /// type ID.  The value ID that is written is encoded relative to the InstID.
1840 static bool PushValueAndType(const Value *V, unsigned InstID,
1841                              SmallVectorImpl<unsigned> &Vals,
1842                              ValueEnumerator &VE) {
1843   unsigned ValID = VE.getValueID(V);
1844   // Make encoding relative to the InstID.
1845   Vals.push_back(InstID - ValID);
1846   if (ValID >= InstID) {
1847     Vals.push_back(VE.getTypeID(V->getType()));
1848     return true;
1849   }
1850   return false;
1851 }
1852 
1853 static void WriteOperandBundles(BitstreamWriter &Stream, ImmutableCallSite CS,
1854                                 unsigned InstID, ValueEnumerator &VE) {
1855   SmallVector<unsigned, 64> Record;
1856   LLVMContext &C = CS.getInstruction()->getContext();
1857 
1858   for (unsigned i = 0, e = CS.getNumOperandBundles(); i != e; ++i) {
1859     const auto &Bundle = CS.getOperandBundleAt(i);
1860     Record.push_back(C.getOperandBundleTagID(Bundle.getTagName()));
1861 
1862     for (auto &Input : Bundle.Inputs)
1863       PushValueAndType(Input, InstID, Record, VE);
1864 
1865     Stream.EmitRecord(bitc::FUNC_CODE_OPERAND_BUNDLE, Record);
1866     Record.clear();
1867   }
1868 }
1869 
1870 /// pushValue - Like PushValueAndType, but where the type of the value is
1871 /// omitted (perhaps it was already encoded in an earlier operand).
1872 static void pushValue(const Value *V, unsigned InstID,
1873                       SmallVectorImpl<unsigned> &Vals,
1874                       ValueEnumerator &VE) {
1875   unsigned ValID = VE.getValueID(V);
1876   Vals.push_back(InstID - ValID);
1877 }
1878 
1879 static void pushValueSigned(const Value *V, unsigned InstID,
1880                             SmallVectorImpl<uint64_t> &Vals,
1881                             ValueEnumerator &VE) {
1882   unsigned ValID = VE.getValueID(V);
1883   int64_t diff = ((int32_t)InstID - (int32_t)ValID);
1884   emitSignedInt64(Vals, diff);
1885 }
1886 
1887 /// WriteInstruction - Emit an instruction to the specified stream.
1888 static void WriteInstruction(const Instruction &I, unsigned InstID,
1889                              ValueEnumerator &VE, BitstreamWriter &Stream,
1890                              SmallVectorImpl<unsigned> &Vals) {
1891   unsigned Code = 0;
1892   unsigned AbbrevToUse = 0;
1893   VE.setInstructionID(&I);
1894   switch (I.getOpcode()) {
1895   default:
1896     if (Instruction::isCast(I.getOpcode())) {
1897       Code = bitc::FUNC_CODE_INST_CAST;
1898       if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
1899         AbbrevToUse = FUNCTION_INST_CAST_ABBREV;
1900       Vals.push_back(VE.getTypeID(I.getType()));
1901       Vals.push_back(GetEncodedCastOpcode(I.getOpcode()));
1902     } else {
1903       assert(isa<BinaryOperator>(I) && "Unknown instruction!");
1904       Code = bitc::FUNC_CODE_INST_BINOP;
1905       if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
1906         AbbrevToUse = FUNCTION_INST_BINOP_ABBREV;
1907       pushValue(I.getOperand(1), InstID, Vals, VE);
1908       Vals.push_back(GetEncodedBinaryOpcode(I.getOpcode()));
1909       uint64_t Flags = GetOptimizationFlags(&I);
1910       if (Flags != 0) {
1911         if (AbbrevToUse == FUNCTION_INST_BINOP_ABBREV)
1912           AbbrevToUse = FUNCTION_INST_BINOP_FLAGS_ABBREV;
1913         Vals.push_back(Flags);
1914       }
1915     }
1916     break;
1917 
1918   case Instruction::GetElementPtr: {
1919     Code = bitc::FUNC_CODE_INST_GEP;
1920     AbbrevToUse = FUNCTION_INST_GEP_ABBREV;
1921     auto &GEPInst = cast<GetElementPtrInst>(I);
1922     Vals.push_back(GEPInst.isInBounds());
1923     Vals.push_back(VE.getTypeID(GEPInst.getSourceElementType()));
1924     for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
1925       PushValueAndType(I.getOperand(i), InstID, Vals, VE);
1926     break;
1927   }
1928   case Instruction::ExtractValue: {
1929     Code = bitc::FUNC_CODE_INST_EXTRACTVAL;
1930     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1931     const ExtractValueInst *EVI = cast<ExtractValueInst>(&I);
1932     Vals.append(EVI->idx_begin(), EVI->idx_end());
1933     break;
1934   }
1935   case Instruction::InsertValue: {
1936     Code = bitc::FUNC_CODE_INST_INSERTVAL;
1937     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1938     PushValueAndType(I.getOperand(1), InstID, Vals, VE);
1939     const InsertValueInst *IVI = cast<InsertValueInst>(&I);
1940     Vals.append(IVI->idx_begin(), IVI->idx_end());
1941     break;
1942   }
1943   case Instruction::Select:
1944     Code = bitc::FUNC_CODE_INST_VSELECT;
1945     PushValueAndType(I.getOperand(1), InstID, Vals, VE);
1946     pushValue(I.getOperand(2), InstID, Vals, VE);
1947     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1948     break;
1949   case Instruction::ExtractElement:
1950     Code = bitc::FUNC_CODE_INST_EXTRACTELT;
1951     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1952     PushValueAndType(I.getOperand(1), InstID, Vals, VE);
1953     break;
1954   case Instruction::InsertElement:
1955     Code = bitc::FUNC_CODE_INST_INSERTELT;
1956     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1957     pushValue(I.getOperand(1), InstID, Vals, VE);
1958     PushValueAndType(I.getOperand(2), InstID, Vals, VE);
1959     break;
1960   case Instruction::ShuffleVector:
1961     Code = bitc::FUNC_CODE_INST_SHUFFLEVEC;
1962     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1963     pushValue(I.getOperand(1), InstID, Vals, VE);
1964     pushValue(I.getOperand(2), InstID, Vals, VE);
1965     break;
1966   case Instruction::ICmp:
1967   case Instruction::FCmp: {
1968     // compare returning Int1Ty or vector of Int1Ty
1969     Code = bitc::FUNC_CODE_INST_CMP2;
1970     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1971     pushValue(I.getOperand(1), InstID, Vals, VE);
1972     Vals.push_back(cast<CmpInst>(I).getPredicate());
1973     uint64_t Flags = GetOptimizationFlags(&I);
1974     if (Flags != 0)
1975       Vals.push_back(Flags);
1976     break;
1977   }
1978 
1979   case Instruction::Ret:
1980     {
1981       Code = bitc::FUNC_CODE_INST_RET;
1982       unsigned NumOperands = I.getNumOperands();
1983       if (NumOperands == 0)
1984         AbbrevToUse = FUNCTION_INST_RET_VOID_ABBREV;
1985       else if (NumOperands == 1) {
1986         if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
1987           AbbrevToUse = FUNCTION_INST_RET_VAL_ABBREV;
1988       } else {
1989         for (unsigned i = 0, e = NumOperands; i != e; ++i)
1990           PushValueAndType(I.getOperand(i), InstID, Vals, VE);
1991       }
1992     }
1993     break;
1994   case Instruction::Br:
1995     {
1996       Code = bitc::FUNC_CODE_INST_BR;
1997       const BranchInst &II = cast<BranchInst>(I);
1998       Vals.push_back(VE.getValueID(II.getSuccessor(0)));
1999       if (II.isConditional()) {
2000         Vals.push_back(VE.getValueID(II.getSuccessor(1)));
2001         pushValue(II.getCondition(), InstID, Vals, VE);
2002       }
2003     }
2004     break;
2005   case Instruction::Switch:
2006     {
2007       Code = bitc::FUNC_CODE_INST_SWITCH;
2008       const SwitchInst &SI = cast<SwitchInst>(I);
2009       Vals.push_back(VE.getTypeID(SI.getCondition()->getType()));
2010       pushValue(SI.getCondition(), InstID, Vals, VE);
2011       Vals.push_back(VE.getValueID(SI.getDefaultDest()));
2012       for (SwitchInst::ConstCaseIt Case : SI.cases()) {
2013         Vals.push_back(VE.getValueID(Case.getCaseValue()));
2014         Vals.push_back(VE.getValueID(Case.getCaseSuccessor()));
2015       }
2016     }
2017     break;
2018   case Instruction::IndirectBr:
2019     Code = bitc::FUNC_CODE_INST_INDIRECTBR;
2020     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));
2021     // Encode the address operand as relative, but not the basic blocks.
2022     pushValue(I.getOperand(0), InstID, Vals, VE);
2023     for (unsigned i = 1, e = I.getNumOperands(); i != e; ++i)
2024       Vals.push_back(VE.getValueID(I.getOperand(i)));
2025     break;
2026 
2027   case Instruction::Invoke: {
2028     const InvokeInst *II = cast<InvokeInst>(&I);
2029     const Value *Callee = II->getCalledValue();
2030     FunctionType *FTy = II->getFunctionType();
2031 
2032     if (II->hasOperandBundles())
2033       WriteOperandBundles(Stream, II, InstID, VE);
2034 
2035     Code = bitc::FUNC_CODE_INST_INVOKE;
2036 
2037     Vals.push_back(VE.getAttributeID(II->getAttributes()));
2038     Vals.push_back(II->getCallingConv() | 1 << 13);
2039     Vals.push_back(VE.getValueID(II->getNormalDest()));
2040     Vals.push_back(VE.getValueID(II->getUnwindDest()));
2041     Vals.push_back(VE.getTypeID(FTy));
2042     PushValueAndType(Callee, InstID, Vals, VE);
2043 
2044     // Emit value #'s for the fixed parameters.
2045     for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i)
2046       pushValue(I.getOperand(i), InstID, Vals, VE);  // fixed param.
2047 
2048     // Emit type/value pairs for varargs params.
2049     if (FTy->isVarArg()) {
2050       for (unsigned i = FTy->getNumParams(), e = I.getNumOperands()-3;
2051            i != e; ++i)
2052         PushValueAndType(I.getOperand(i), InstID, Vals, VE); // vararg
2053     }
2054     break;
2055   }
2056   case Instruction::Resume:
2057     Code = bitc::FUNC_CODE_INST_RESUME;
2058     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
2059     break;
2060   case Instruction::CleanupRet: {
2061     Code = bitc::FUNC_CODE_INST_CLEANUPRET;
2062     const auto &CRI = cast<CleanupReturnInst>(I);
2063     pushValue(CRI.getCleanupPad(), InstID, Vals, VE);
2064     if (CRI.hasUnwindDest())
2065       Vals.push_back(VE.getValueID(CRI.getUnwindDest()));
2066     break;
2067   }
2068   case Instruction::CatchRet: {
2069     Code = bitc::FUNC_CODE_INST_CATCHRET;
2070     const auto &CRI = cast<CatchReturnInst>(I);
2071     pushValue(CRI.getCatchPad(), InstID, Vals, VE);
2072     Vals.push_back(VE.getValueID(CRI.getSuccessor()));
2073     break;
2074   }
2075   case Instruction::CleanupPad:
2076   case Instruction::CatchPad: {
2077     const auto &FuncletPad = cast<FuncletPadInst>(I);
2078     Code = isa<CatchPadInst>(FuncletPad) ? bitc::FUNC_CODE_INST_CATCHPAD
2079                                          : bitc::FUNC_CODE_INST_CLEANUPPAD;
2080     pushValue(FuncletPad.getParentPad(), InstID, Vals, VE);
2081 
2082     unsigned NumArgOperands = FuncletPad.getNumArgOperands();
2083     Vals.push_back(NumArgOperands);
2084     for (unsigned Op = 0; Op != NumArgOperands; ++Op)
2085       PushValueAndType(FuncletPad.getArgOperand(Op), InstID, Vals, VE);
2086     break;
2087   }
2088   case Instruction::CatchSwitch: {
2089     Code = bitc::FUNC_CODE_INST_CATCHSWITCH;
2090     const auto &CatchSwitch = cast<CatchSwitchInst>(I);
2091 
2092     pushValue(CatchSwitch.getParentPad(), InstID, Vals, VE);
2093 
2094     unsigned NumHandlers = CatchSwitch.getNumHandlers();
2095     Vals.push_back(NumHandlers);
2096     for (const BasicBlock *CatchPadBB : CatchSwitch.handlers())
2097       Vals.push_back(VE.getValueID(CatchPadBB));
2098 
2099     if (CatchSwitch.hasUnwindDest())
2100       Vals.push_back(VE.getValueID(CatchSwitch.getUnwindDest()));
2101     break;
2102   }
2103   case Instruction::Unreachable:
2104     Code = bitc::FUNC_CODE_INST_UNREACHABLE;
2105     AbbrevToUse = FUNCTION_INST_UNREACHABLE_ABBREV;
2106     break;
2107 
2108   case Instruction::PHI: {
2109     const PHINode &PN = cast<PHINode>(I);
2110     Code = bitc::FUNC_CODE_INST_PHI;
2111     // With the newer instruction encoding, forward references could give
2112     // negative valued IDs.  This is most common for PHIs, so we use
2113     // signed VBRs.
2114     SmallVector<uint64_t, 128> Vals64;
2115     Vals64.push_back(VE.getTypeID(PN.getType()));
2116     for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) {
2117       pushValueSigned(PN.getIncomingValue(i), InstID, Vals64, VE);
2118       Vals64.push_back(VE.getValueID(PN.getIncomingBlock(i)));
2119     }
2120     // Emit a Vals64 vector and exit.
2121     Stream.EmitRecord(Code, Vals64, AbbrevToUse);
2122     Vals64.clear();
2123     return;
2124   }
2125 
2126   case Instruction::LandingPad: {
2127     const LandingPadInst &LP = cast<LandingPadInst>(I);
2128     Code = bitc::FUNC_CODE_INST_LANDINGPAD;
2129     Vals.push_back(VE.getTypeID(LP.getType()));
2130     Vals.push_back(LP.isCleanup());
2131     Vals.push_back(LP.getNumClauses());
2132     for (unsigned I = 0, E = LP.getNumClauses(); I != E; ++I) {
2133       if (LP.isCatch(I))
2134         Vals.push_back(LandingPadInst::Catch);
2135       else
2136         Vals.push_back(LandingPadInst::Filter);
2137       PushValueAndType(LP.getClause(I), InstID, Vals, VE);
2138     }
2139     break;
2140   }
2141 
2142   case Instruction::Alloca: {
2143     Code = bitc::FUNC_CODE_INST_ALLOCA;
2144     const AllocaInst &AI = cast<AllocaInst>(I);
2145     Vals.push_back(VE.getTypeID(AI.getAllocatedType()));
2146     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));
2147     Vals.push_back(VE.getValueID(I.getOperand(0))); // size.
2148     unsigned AlignRecord = Log2_32(AI.getAlignment()) + 1;
2149     assert(Log2_32(Value::MaximumAlignment) + 1 < 1 << 5 &&
2150            "not enough bits for maximum alignment");
2151     assert(AlignRecord < 1 << 5 && "alignment greater than 1 << 64");
2152     AlignRecord |= AI.isUsedWithInAlloca() << 5;
2153     AlignRecord |= 1 << 6;
2154     // Reserve bit 7 for SwiftError flag.
2155     // AlignRecord |= AI.isSwiftError() << 7;
2156     Vals.push_back(AlignRecord);
2157     break;
2158   }
2159 
2160   case Instruction::Load:
2161     if (cast<LoadInst>(I).isAtomic()) {
2162       Code = bitc::FUNC_CODE_INST_LOADATOMIC;
2163       PushValueAndType(I.getOperand(0), InstID, Vals, VE);
2164     } else {
2165       Code = bitc::FUNC_CODE_INST_LOAD;
2166       if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))  // ptr
2167         AbbrevToUse = FUNCTION_INST_LOAD_ABBREV;
2168     }
2169     Vals.push_back(VE.getTypeID(I.getType()));
2170     Vals.push_back(Log2_32(cast<LoadInst>(I).getAlignment())+1);
2171     Vals.push_back(cast<LoadInst>(I).isVolatile());
2172     if (cast<LoadInst>(I).isAtomic()) {
2173       Vals.push_back(GetEncodedOrdering(cast<LoadInst>(I).getOrdering()));
2174       Vals.push_back(GetEncodedSynchScope(cast<LoadInst>(I).getSynchScope()));
2175     }
2176     break;
2177   case Instruction::Store:
2178     if (cast<StoreInst>(I).isAtomic())
2179       Code = bitc::FUNC_CODE_INST_STOREATOMIC;
2180     else
2181       Code = bitc::FUNC_CODE_INST_STORE;
2182     PushValueAndType(I.getOperand(1), InstID, Vals, VE);  // ptrty + ptr
2183     PushValueAndType(I.getOperand(0), InstID, Vals, VE);  // valty + val
2184     Vals.push_back(Log2_32(cast<StoreInst>(I).getAlignment())+1);
2185     Vals.push_back(cast<StoreInst>(I).isVolatile());
2186     if (cast<StoreInst>(I).isAtomic()) {
2187       Vals.push_back(GetEncodedOrdering(cast<StoreInst>(I).getOrdering()));
2188       Vals.push_back(GetEncodedSynchScope(cast<StoreInst>(I).getSynchScope()));
2189     }
2190     break;
2191   case Instruction::AtomicCmpXchg:
2192     Code = bitc::FUNC_CODE_INST_CMPXCHG;
2193     PushValueAndType(I.getOperand(0), InstID, Vals, VE);  // ptrty + ptr
2194     PushValueAndType(I.getOperand(1), InstID, Vals, VE);  // cmp.
2195     pushValue(I.getOperand(2), InstID, Vals, VE);         // newval.
2196     Vals.push_back(cast<AtomicCmpXchgInst>(I).isVolatile());
2197     Vals.push_back(GetEncodedOrdering(
2198                      cast<AtomicCmpXchgInst>(I).getSuccessOrdering()));
2199     Vals.push_back(GetEncodedSynchScope(
2200                      cast<AtomicCmpXchgInst>(I).getSynchScope()));
2201     Vals.push_back(GetEncodedOrdering(
2202                      cast<AtomicCmpXchgInst>(I).getFailureOrdering()));
2203     Vals.push_back(cast<AtomicCmpXchgInst>(I).isWeak());
2204     break;
2205   case Instruction::AtomicRMW:
2206     Code = bitc::FUNC_CODE_INST_ATOMICRMW;
2207     PushValueAndType(I.getOperand(0), InstID, Vals, VE);  // ptrty + ptr
2208     pushValue(I.getOperand(1), InstID, Vals, VE);         // val.
2209     Vals.push_back(GetEncodedRMWOperation(
2210                      cast<AtomicRMWInst>(I).getOperation()));
2211     Vals.push_back(cast<AtomicRMWInst>(I).isVolatile());
2212     Vals.push_back(GetEncodedOrdering(cast<AtomicRMWInst>(I).getOrdering()));
2213     Vals.push_back(GetEncodedSynchScope(
2214                      cast<AtomicRMWInst>(I).getSynchScope()));
2215     break;
2216   case Instruction::Fence:
2217     Code = bitc::FUNC_CODE_INST_FENCE;
2218     Vals.push_back(GetEncodedOrdering(cast<FenceInst>(I).getOrdering()));
2219     Vals.push_back(GetEncodedSynchScope(cast<FenceInst>(I).getSynchScope()));
2220     break;
2221   case Instruction::Call: {
2222     const CallInst &CI = cast<CallInst>(I);
2223     FunctionType *FTy = CI.getFunctionType();
2224 
2225     if (CI.hasOperandBundles())
2226       WriteOperandBundles(Stream, &CI, InstID, VE);
2227 
2228     Code = bitc::FUNC_CODE_INST_CALL;
2229 
2230     Vals.push_back(VE.getAttributeID(CI.getAttributes()));
2231 
2232     unsigned Flags = GetOptimizationFlags(&I);
2233     Vals.push_back(CI.getCallingConv() << bitc::CALL_CCONV |
2234                    unsigned(CI.isTailCall()) << bitc::CALL_TAIL |
2235                    unsigned(CI.isMustTailCall()) << bitc::CALL_MUSTTAIL |
2236                    1 << bitc::CALL_EXPLICIT_TYPE |
2237                    unsigned(CI.isNoTailCall()) << bitc::CALL_NOTAIL |
2238                    unsigned(Flags != 0) << bitc::CALL_FMF);
2239     if (Flags != 0)
2240       Vals.push_back(Flags);
2241 
2242     Vals.push_back(VE.getTypeID(FTy));
2243     PushValueAndType(CI.getCalledValue(), InstID, Vals, VE);  // Callee
2244 
2245     // Emit value #'s for the fixed parameters.
2246     for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i) {
2247       // Check for labels (can happen with asm labels).
2248       if (FTy->getParamType(i)->isLabelTy())
2249         Vals.push_back(VE.getValueID(CI.getArgOperand(i)));
2250       else
2251         pushValue(CI.getArgOperand(i), InstID, Vals, VE);  // fixed param.
2252     }
2253 
2254     // Emit type/value pairs for varargs params.
2255     if (FTy->isVarArg()) {
2256       for (unsigned i = FTy->getNumParams(), e = CI.getNumArgOperands();
2257            i != e; ++i)
2258         PushValueAndType(CI.getArgOperand(i), InstID, Vals, VE);  // varargs
2259     }
2260     break;
2261   }
2262   case Instruction::VAArg:
2263     Code = bitc::FUNC_CODE_INST_VAARG;
2264     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));   // valistty
2265     pushValue(I.getOperand(0), InstID, Vals, VE); // valist.
2266     Vals.push_back(VE.getTypeID(I.getType())); // restype.
2267     break;
2268   }
2269 
2270   Stream.EmitRecord(Code, Vals, AbbrevToUse);
2271   Vals.clear();
2272 }
2273 
2274 /// Emit names for globals/functions etc. The VSTOffsetPlaceholder,
2275 /// BitcodeStartBit and ModuleSummaryIndex are only passed for the module-level
2276 /// VST, where we are including a function bitcode index and need to
2277 /// backpatch the VST forward declaration record.
2278 static void WriteValueSymbolTable(
2279     const ValueSymbolTable &VST, const ValueEnumerator &VE,
2280     BitstreamWriter &Stream, uint64_t VSTOffsetPlaceholder = 0,
2281     uint64_t BitcodeStartBit = 0,
2282     DenseMap<const Function *, std::unique_ptr<GlobalValueInfo>>
2283         *FunctionIndex = nullptr) {
2284   if (VST.empty()) {
2285     // WriteValueSymbolTableForwardDecl should have returned early as
2286     // well. Ensure this handling remains in sync by asserting that
2287     // the placeholder offset is not set.
2288     assert(VSTOffsetPlaceholder == 0);
2289     return;
2290   }
2291 
2292   if (VSTOffsetPlaceholder > 0) {
2293     // Get the offset of the VST we are writing, and backpatch it into
2294     // the VST forward declaration record.
2295     uint64_t VSTOffset = Stream.GetCurrentBitNo();
2296     // The BitcodeStartBit was the stream offset of the actual bitcode
2297     // (e.g. excluding any initial darwin header).
2298     VSTOffset -= BitcodeStartBit;
2299     assert((VSTOffset & 31) == 0 && "VST block not 32-bit aligned");
2300     Stream.BackpatchWord(VSTOffsetPlaceholder, VSTOffset / 32);
2301   }
2302 
2303   Stream.EnterSubblock(bitc::VALUE_SYMTAB_BLOCK_ID, 4);
2304 
2305   // For the module-level VST, add abbrev Ids for the VST_CODE_FNENTRY
2306   // records, which are not used in the per-function VSTs.
2307   unsigned FnEntry8BitAbbrev;
2308   unsigned FnEntry7BitAbbrev;
2309   unsigned FnEntry6BitAbbrev;
2310   if (VSTOffsetPlaceholder > 0) {
2311     // 8-bit fixed-width VST_CODE_FNENTRY function strings.
2312     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2313     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_FNENTRY));
2314     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // value id
2315     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // funcoffset
2316     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2317     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
2318     FnEntry8BitAbbrev = Stream.EmitAbbrev(Abbv);
2319 
2320     // 7-bit fixed width VST_CODE_FNENTRY function strings.
2321     Abbv = new BitCodeAbbrev();
2322     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_FNENTRY));
2323     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // value id
2324     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // funcoffset
2325     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2326     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
2327     FnEntry7BitAbbrev = Stream.EmitAbbrev(Abbv);
2328 
2329     // 6-bit char6 VST_CODE_FNENTRY function strings.
2330     Abbv = new BitCodeAbbrev();
2331     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_FNENTRY));
2332     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // value id
2333     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // funcoffset
2334     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2335     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
2336     FnEntry6BitAbbrev = Stream.EmitAbbrev(Abbv);
2337   }
2338 
2339   // FIXME: Set up the abbrev, we know how many values there are!
2340   // FIXME: We know if the type names can use 7-bit ascii.
2341   SmallVector<unsigned, 64> NameVals;
2342 
2343   for (const ValueName &Name : VST) {
2344     // Figure out the encoding to use for the name.
2345     StringEncoding Bits =
2346         getStringEncoding(Name.getKeyData(), Name.getKeyLength());
2347 
2348     unsigned AbbrevToUse = VST_ENTRY_8_ABBREV;
2349     NameVals.push_back(VE.getValueID(Name.getValue()));
2350 
2351     Function *F = dyn_cast<Function>(Name.getValue());
2352     if (!F) {
2353       // If value is an alias, need to get the aliased base object to
2354       // see if it is a function.
2355       auto *GA = dyn_cast<GlobalAlias>(Name.getValue());
2356       if (GA && GA->getBaseObject())
2357         F = dyn_cast<Function>(GA->getBaseObject());
2358     }
2359 
2360     // VST_CODE_ENTRY:   [valueid, namechar x N]
2361     // VST_CODE_FNENTRY: [valueid, funcoffset, namechar x N]
2362     // VST_CODE_BBENTRY: [bbid, namechar x N]
2363     unsigned Code;
2364     if (isa<BasicBlock>(Name.getValue())) {
2365       Code = bitc::VST_CODE_BBENTRY;
2366       if (Bits == SE_Char6)
2367         AbbrevToUse = VST_BBENTRY_6_ABBREV;
2368     } else if (F && !F->isDeclaration()) {
2369       // Must be the module-level VST, where we pass in the Index and
2370       // have a VSTOffsetPlaceholder. The function-level VST should not
2371       // contain any Function symbols.
2372       assert(FunctionIndex);
2373       assert(VSTOffsetPlaceholder > 0);
2374 
2375       // Save the word offset of the function (from the start of the
2376       // actual bitcode written to the stream).
2377       uint64_t BitcodeIndex =
2378           (*FunctionIndex)[F]->bitcodeIndex() - BitcodeStartBit;
2379       assert((BitcodeIndex & 31) == 0 && "function block not 32-bit aligned");
2380       NameVals.push_back(BitcodeIndex / 32);
2381 
2382       Code = bitc::VST_CODE_FNENTRY;
2383       AbbrevToUse = FnEntry8BitAbbrev;
2384       if (Bits == SE_Char6)
2385         AbbrevToUse = FnEntry6BitAbbrev;
2386       else if (Bits == SE_Fixed7)
2387         AbbrevToUse = FnEntry7BitAbbrev;
2388     } else {
2389       Code = bitc::VST_CODE_ENTRY;
2390       if (Bits == SE_Char6)
2391         AbbrevToUse = VST_ENTRY_6_ABBREV;
2392       else if (Bits == SE_Fixed7)
2393         AbbrevToUse = VST_ENTRY_7_ABBREV;
2394     }
2395 
2396     for (const auto P : Name.getKey())
2397       NameVals.push_back((unsigned char)P);
2398 
2399     // Emit the finished record.
2400     Stream.EmitRecord(Code, NameVals, AbbrevToUse);
2401     NameVals.clear();
2402   }
2403   Stream.ExitBlock();
2404 }
2405 
2406 /// Emit function names and summary offsets for the combined index
2407 /// used by ThinLTO.
2408 static void
2409 WriteCombinedValueSymbolTable(const ModuleSummaryIndex &Index,
2410                               BitstreamWriter &Stream,
2411                               std::map<uint64_t, unsigned> &GUIDToValueIdMap,
2412                               uint64_t VSTOffsetPlaceholder) {
2413   assert(VSTOffsetPlaceholder > 0 && "Expected non-zero VSTOffsetPlaceholder");
2414   // Get the offset of the VST we are writing, and backpatch it into
2415   // the VST forward declaration record.
2416   uint64_t VSTOffset = Stream.GetCurrentBitNo();
2417   assert((VSTOffset & 31) == 0 && "VST block not 32-bit aligned");
2418   Stream.BackpatchWord(VSTOffsetPlaceholder, VSTOffset / 32);
2419 
2420   Stream.EnterSubblock(bitc::VALUE_SYMTAB_BLOCK_ID, 4);
2421 
2422   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2423   Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_COMBINED_GVDEFENTRY));
2424   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // valueid
2425   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // sumoffset
2426   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // guid
2427   unsigned DefEntryAbbrev = Stream.EmitAbbrev(Abbv);
2428 
2429   Abbv = new BitCodeAbbrev();
2430   Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_COMBINED_ENTRY));
2431   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // valueid
2432   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // refguid
2433   unsigned EntryAbbrev = Stream.EmitAbbrev(Abbv);
2434 
2435   SmallVector<uint64_t, 64> NameVals;
2436 
2437   for (const auto &FII : Index) {
2438     uint64_t FuncGUID = FII.first;
2439     const auto &VMI = GUIDToValueIdMap.find(FuncGUID);
2440     assert(VMI != GUIDToValueIdMap.end());
2441 
2442     for (const auto &FI : FII.second) {
2443       // VST_CODE_COMBINED_GVDEFENTRY: [valueid, sumoffset, guid]
2444       NameVals.push_back(VMI->second);
2445       NameVals.push_back(FI->bitcodeIndex());
2446       NameVals.push_back(FuncGUID);
2447 
2448       // Emit the finished record.
2449       Stream.EmitRecord(bitc::VST_CODE_COMBINED_GVDEFENTRY, NameVals,
2450                         DefEntryAbbrev);
2451       NameVals.clear();
2452     }
2453     GUIDToValueIdMap.erase(VMI);
2454   }
2455   for (const auto &GVI : GUIDToValueIdMap) {
2456     // VST_CODE_COMBINED_ENTRY: [valueid, refguid]
2457     NameVals.push_back(GVI.second);
2458     NameVals.push_back(GVI.first);
2459 
2460     // Emit the finished record.
2461     Stream.EmitRecord(bitc::VST_CODE_COMBINED_ENTRY, NameVals, EntryAbbrev);
2462     NameVals.clear();
2463   }
2464   Stream.ExitBlock();
2465 }
2466 
2467 static void WriteUseList(ValueEnumerator &VE, UseListOrder &&Order,
2468                          BitstreamWriter &Stream) {
2469   assert(Order.Shuffle.size() >= 2 && "Shuffle too small");
2470   unsigned Code;
2471   if (isa<BasicBlock>(Order.V))
2472     Code = bitc::USELIST_CODE_BB;
2473   else
2474     Code = bitc::USELIST_CODE_DEFAULT;
2475 
2476   SmallVector<uint64_t, 64> Record(Order.Shuffle.begin(), Order.Shuffle.end());
2477   Record.push_back(VE.getValueID(Order.V));
2478   Stream.EmitRecord(Code, Record);
2479 }
2480 
2481 static void WriteUseListBlock(const Function *F, ValueEnumerator &VE,
2482                               BitstreamWriter &Stream) {
2483   assert(VE.shouldPreserveUseListOrder() &&
2484          "Expected to be preserving use-list order");
2485 
2486   auto hasMore = [&]() {
2487     return !VE.UseListOrders.empty() && VE.UseListOrders.back().F == F;
2488   };
2489   if (!hasMore())
2490     // Nothing to do.
2491     return;
2492 
2493   Stream.EnterSubblock(bitc::USELIST_BLOCK_ID, 3);
2494   while (hasMore()) {
2495     WriteUseList(VE, std::move(VE.UseListOrders.back()), Stream);
2496     VE.UseListOrders.pop_back();
2497   }
2498   Stream.ExitBlock();
2499 }
2500 
2501 // Walk through the operands of a given User via worklist iteration and populate
2502 // the set of GlobalValue references encountered. Invoked either on an
2503 // Instruction or a GlobalVariable (which walks its initializer).
2504 static void findRefEdges(const User *CurUser, const ValueEnumerator &VE,
2505                          DenseSet<unsigned> &RefEdges,
2506                          SmallPtrSet<const User *, 8> &Visited) {
2507   SmallVector<const User *, 32> Worklist;
2508   Worklist.push_back(CurUser);
2509 
2510   while (!Worklist.empty()) {
2511     const User *U = Worklist.pop_back_val();
2512 
2513     if (!Visited.insert(U).second)
2514       continue;
2515 
2516     ImmutableCallSite CS(U);
2517 
2518     for (const auto &OI : U->operands()) {
2519       const User *Operand = dyn_cast<User>(OI);
2520       if (!Operand)
2521         continue;
2522       if (isa<BlockAddress>(Operand))
2523         continue;
2524       if (isa<GlobalValue>(Operand)) {
2525         // We have a reference to a global value. This should be added to
2526         // the reference set unless it is a callee. Callees are handled
2527         // specially by WriteFunction and are added to a separate list.
2528         if (!(CS && CS.isCallee(&OI)))
2529           RefEdges.insert(VE.getValueID(Operand));
2530         continue;
2531       }
2532       Worklist.push_back(Operand);
2533     }
2534   }
2535 }
2536 
2537 /// Emit a function body to the module stream.
2538 static void WriteFunction(
2539     const Function &F, const Module *M, ValueEnumerator &VE,
2540     BitstreamWriter &Stream,
2541     DenseMap<const Function *, std::unique_ptr<GlobalValueInfo>> &FunctionIndex,
2542     bool EmitSummaryIndex) {
2543   // Save the bitcode index of the start of this function block for recording
2544   // in the VST.
2545   uint64_t BitcodeIndex = Stream.GetCurrentBitNo();
2546 
2547   bool HasProfileData = F.getEntryCount().hasValue();
2548   std::unique_ptr<BlockFrequencyInfo> BFI;
2549   if (EmitSummaryIndex && HasProfileData) {
2550     Function &Func = const_cast<Function &>(F);
2551     LoopInfo LI{DominatorTree(Func)};
2552     BranchProbabilityInfo BPI{Func, LI};
2553     BFI = llvm::make_unique<BlockFrequencyInfo>(Func, BPI, LI);
2554   }
2555 
2556   Stream.EnterSubblock(bitc::FUNCTION_BLOCK_ID, 4);
2557   VE.incorporateFunction(F);
2558 
2559   SmallVector<unsigned, 64> Vals;
2560 
2561   // Emit the number of basic blocks, so the reader can create them ahead of
2562   // time.
2563   Vals.push_back(VE.getBasicBlocks().size());
2564   Stream.EmitRecord(bitc::FUNC_CODE_DECLAREBLOCKS, Vals);
2565   Vals.clear();
2566 
2567   // If there are function-local constants, emit them now.
2568   unsigned CstStart, CstEnd;
2569   VE.getFunctionConstantRange(CstStart, CstEnd);
2570   WriteConstants(CstStart, CstEnd, VE, Stream, false);
2571 
2572   // If there is function-local metadata, emit it now.
2573   WriteFunctionLocalMetadata(F, VE, Stream);
2574 
2575   // Keep a running idea of what the instruction ID is.
2576   unsigned InstID = CstEnd;
2577 
2578   bool NeedsMetadataAttachment = F.hasMetadata();
2579 
2580   DILocation *LastDL = nullptr;
2581   unsigned NumInsts = 0;
2582   // Map from callee ValueId to profile count. Used to accumulate profile
2583   // counts for all static calls to a given callee.
2584   DenseMap<unsigned, CalleeInfo> CallGraphEdges;
2585   DenseSet<unsigned> RefEdges;
2586 
2587   SmallPtrSet<const User *, 8> Visited;
2588   // Finally, emit all the instructions, in order.
2589   for (Function::const_iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
2590     for (BasicBlock::const_iterator I = BB->begin(), E = BB->end();
2591          I != E; ++I) {
2592       WriteInstruction(*I, InstID, VE, Stream, Vals);
2593 
2594       if (!isa<DbgInfoIntrinsic>(I))
2595         ++NumInsts;
2596 
2597       if (!I->getType()->isVoidTy())
2598         ++InstID;
2599 
2600       if (EmitSummaryIndex) {
2601         if (auto CS = ImmutableCallSite(&*I)) {
2602           auto *CalledFunction = CS.getCalledFunction();
2603           if (CalledFunction && CalledFunction->hasName() &&
2604               !CalledFunction->isIntrinsic()) {
2605             auto ScaledCount = BFI ? BFI->getBlockProfileCount(&*BB) : None;
2606             unsigned CalleeId = VE.getValueID(
2607                 M->getValueSymbolTable().lookup(CalledFunction->getName()));
2608             CallGraphEdges[CalleeId] +=
2609                 (ScaledCount ? ScaledCount.getValue() : 0);
2610           }
2611         }
2612         findRefEdges(&*I, VE, RefEdges, Visited);
2613       }
2614 
2615       // If the instruction has metadata, write a metadata attachment later.
2616       NeedsMetadataAttachment |= I->hasMetadataOtherThanDebugLoc();
2617 
2618       // If the instruction has a debug location, emit it.
2619       DILocation *DL = I->getDebugLoc();
2620       if (!DL)
2621         continue;
2622 
2623       if (DL == LastDL) {
2624         // Just repeat the same debug loc as last time.
2625         Stream.EmitRecord(bitc::FUNC_CODE_DEBUG_LOC_AGAIN, Vals);
2626         continue;
2627       }
2628 
2629       Vals.push_back(DL->getLine());
2630       Vals.push_back(DL->getColumn());
2631       Vals.push_back(VE.getMetadataOrNullID(DL->getScope()));
2632       Vals.push_back(VE.getMetadataOrNullID(DL->getInlinedAt()));
2633       Stream.EmitRecord(bitc::FUNC_CODE_DEBUG_LOC, Vals);
2634       Vals.clear();
2635 
2636       LastDL = DL;
2637     }
2638 
2639   std::unique_ptr<FunctionSummary> FuncSummary;
2640   if (EmitSummaryIndex) {
2641     FuncSummary = llvm::make_unique<FunctionSummary>(F.getLinkage(), NumInsts);
2642     FuncSummary->addCallGraphEdges(CallGraphEdges);
2643     FuncSummary->addRefEdges(RefEdges);
2644   }
2645   FunctionIndex[&F] =
2646       llvm::make_unique<GlobalValueInfo>(BitcodeIndex, std::move(FuncSummary));
2647 
2648   // Emit names for all the instructions etc.
2649   WriteValueSymbolTable(F.getValueSymbolTable(), VE, Stream);
2650 
2651   if (NeedsMetadataAttachment)
2652     WriteMetadataAttachment(F, VE, Stream);
2653   if (VE.shouldPreserveUseListOrder())
2654     WriteUseListBlock(&F, VE, Stream);
2655   VE.purgeFunction();
2656   Stream.ExitBlock();
2657 }
2658 
2659 // Emit blockinfo, which defines the standard abbreviations etc.
2660 static void WriteBlockInfo(const ValueEnumerator &VE, BitstreamWriter &Stream) {
2661   // We only want to emit block info records for blocks that have multiple
2662   // instances: CONSTANTS_BLOCK, FUNCTION_BLOCK and VALUE_SYMTAB_BLOCK.
2663   // Other blocks can define their abbrevs inline.
2664   Stream.EnterBlockInfoBlock(2);
2665 
2666   { // 8-bit fixed-width VST_CODE_ENTRY/VST_CODE_BBENTRY strings.
2667     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2668     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 3));
2669     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
2670     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2671     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
2672     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
2673                                    Abbv) != VST_ENTRY_8_ABBREV)
2674       llvm_unreachable("Unexpected abbrev ordering!");
2675   }
2676 
2677   { // 7-bit fixed width VST_CODE_ENTRY strings.
2678     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2679     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
2680     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
2681     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2682     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
2683     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
2684                                    Abbv) != VST_ENTRY_7_ABBREV)
2685       llvm_unreachable("Unexpected abbrev ordering!");
2686   }
2687   { // 6-bit char6 VST_CODE_ENTRY strings.
2688     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2689     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
2690     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
2691     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2692     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
2693     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
2694                                    Abbv) != VST_ENTRY_6_ABBREV)
2695       llvm_unreachable("Unexpected abbrev ordering!");
2696   }
2697   { // 6-bit char6 VST_CODE_BBENTRY strings.
2698     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2699     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_BBENTRY));
2700     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
2701     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2702     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
2703     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
2704                                    Abbv) != VST_BBENTRY_6_ABBREV)
2705       llvm_unreachable("Unexpected abbrev ordering!");
2706   }
2707 
2708 
2709 
2710   { // SETTYPE abbrev for CONSTANTS_BLOCK.
2711     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2712     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_SETTYPE));
2713     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
2714                               VE.computeBitsRequiredForTypeIndicies()));
2715     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
2716                                    Abbv) != CONSTANTS_SETTYPE_ABBREV)
2717       llvm_unreachable("Unexpected abbrev ordering!");
2718   }
2719 
2720   { // INTEGER abbrev for CONSTANTS_BLOCK.
2721     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2722     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_INTEGER));
2723     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
2724     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
2725                                    Abbv) != CONSTANTS_INTEGER_ABBREV)
2726       llvm_unreachable("Unexpected abbrev ordering!");
2727   }
2728 
2729   { // CE_CAST abbrev for CONSTANTS_BLOCK.
2730     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2731     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CE_CAST));
2732     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // cast opc
2733     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // typeid
2734                               VE.computeBitsRequiredForTypeIndicies()));
2735     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));    // value id
2736 
2737     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
2738                                    Abbv) != CONSTANTS_CE_CAST_Abbrev)
2739       llvm_unreachable("Unexpected abbrev ordering!");
2740   }
2741   { // NULL abbrev for CONSTANTS_BLOCK.
2742     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2743     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_NULL));
2744     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
2745                                    Abbv) != CONSTANTS_NULL_Abbrev)
2746       llvm_unreachable("Unexpected abbrev ordering!");
2747   }
2748 
2749   // FIXME: This should only use space for first class types!
2750 
2751   { // INST_LOAD abbrev for FUNCTION_BLOCK.
2752     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2753     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_LOAD));
2754     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Ptr
2755     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,    // dest ty
2756                               VE.computeBitsRequiredForTypeIndicies()));
2757     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4)); // Align
2758     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // volatile
2759     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
2760                                    Abbv) != FUNCTION_INST_LOAD_ABBREV)
2761       llvm_unreachable("Unexpected abbrev ordering!");
2762   }
2763   { // INST_BINOP abbrev for FUNCTION_BLOCK.
2764     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2765     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
2766     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
2767     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
2768     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
2769     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
2770                                    Abbv) != FUNCTION_INST_BINOP_ABBREV)
2771       llvm_unreachable("Unexpected abbrev ordering!");
2772   }
2773   { // INST_BINOP_FLAGS abbrev for FUNCTION_BLOCK.
2774     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2775     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
2776     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
2777     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
2778     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
2779     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7)); // flags
2780     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
2781                                    Abbv) != FUNCTION_INST_BINOP_FLAGS_ABBREV)
2782       llvm_unreachable("Unexpected abbrev ordering!");
2783   }
2784   { // INST_CAST abbrev for FUNCTION_BLOCK.
2785     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2786     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_CAST));
2787     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));    // OpVal
2788     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // dest ty
2789                               VE.computeBitsRequiredForTypeIndicies()));
2790     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // opc
2791     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
2792                                    Abbv) != FUNCTION_INST_CAST_ABBREV)
2793       llvm_unreachable("Unexpected abbrev ordering!");
2794   }
2795 
2796   { // INST_RET abbrev for FUNCTION_BLOCK.
2797     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2798     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
2799     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
2800                                    Abbv) != FUNCTION_INST_RET_VOID_ABBREV)
2801       llvm_unreachable("Unexpected abbrev ordering!");
2802   }
2803   { // INST_RET abbrev for FUNCTION_BLOCK.
2804     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2805     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
2806     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // ValID
2807     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
2808                                    Abbv) != FUNCTION_INST_RET_VAL_ABBREV)
2809       llvm_unreachable("Unexpected abbrev ordering!");
2810   }
2811   { // INST_UNREACHABLE abbrev for FUNCTION_BLOCK.
2812     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2813     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_UNREACHABLE));
2814     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
2815                                    Abbv) != FUNCTION_INST_UNREACHABLE_ABBREV)
2816       llvm_unreachable("Unexpected abbrev ordering!");
2817   }
2818   {
2819     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2820     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_GEP));
2821     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
2822     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, // dest ty
2823                               Log2_32_Ceil(VE.getTypes().size() + 1)));
2824     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2825     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
2826     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
2827         FUNCTION_INST_GEP_ABBREV)
2828       llvm_unreachable("Unexpected abbrev ordering!");
2829   }
2830 
2831   Stream.ExitBlock();
2832 }
2833 
2834 /// Write the module path strings, currently only used when generating
2835 /// a combined index file.
2836 static void WriteModStrings(const ModuleSummaryIndex &I,
2837                             BitstreamWriter &Stream) {
2838   Stream.EnterSubblock(bitc::MODULE_STRTAB_BLOCK_ID, 3);
2839 
2840   // TODO: See which abbrev sizes we actually need to emit
2841 
2842   // 8-bit fixed-width MST_ENTRY strings.
2843   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2844   Abbv->Add(BitCodeAbbrevOp(bitc::MST_CODE_ENTRY));
2845   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
2846   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2847   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
2848   unsigned Abbrev8Bit = Stream.EmitAbbrev(Abbv);
2849 
2850   // 7-bit fixed width MST_ENTRY strings.
2851   Abbv = new BitCodeAbbrev();
2852   Abbv->Add(BitCodeAbbrevOp(bitc::MST_CODE_ENTRY));
2853   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
2854   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2855   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
2856   unsigned Abbrev7Bit = Stream.EmitAbbrev(Abbv);
2857 
2858   // 6-bit char6 MST_ENTRY strings.
2859   Abbv = new BitCodeAbbrev();
2860   Abbv->Add(BitCodeAbbrevOp(bitc::MST_CODE_ENTRY));
2861   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
2862   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2863   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
2864   unsigned Abbrev6Bit = Stream.EmitAbbrev(Abbv);
2865 
2866   SmallVector<unsigned, 64> NameVals;
2867   for (const StringMapEntry<uint64_t> &MPSE : I.modPathStringEntries()) {
2868     StringEncoding Bits =
2869         getStringEncoding(MPSE.getKey().data(), MPSE.getKey().size());
2870     unsigned AbbrevToUse = Abbrev8Bit;
2871     if (Bits == SE_Char6)
2872       AbbrevToUse = Abbrev6Bit;
2873     else if (Bits == SE_Fixed7)
2874       AbbrevToUse = Abbrev7Bit;
2875 
2876     NameVals.push_back(MPSE.getValue());
2877 
2878     for (const auto P : MPSE.getKey())
2879       NameVals.push_back((unsigned char)P);
2880 
2881     // Emit the finished record.
2882     Stream.EmitRecord(bitc::MST_CODE_ENTRY, NameVals, AbbrevToUse);
2883     NameVals.clear();
2884   }
2885   Stream.ExitBlock();
2886 }
2887 
2888 // Helper to emit a single function summary record.
2889 static void WritePerModuleFunctionSummaryRecord(
2890     SmallVector<uint64_t, 64> &NameVals, FunctionSummary *FS, unsigned ValueID,
2891     unsigned FSCallsAbbrev, unsigned FSCallsProfileAbbrev,
2892     BitstreamWriter &Stream, const Function &F) {
2893   assert(FS);
2894   NameVals.push_back(ValueID);
2895   NameVals.push_back(getEncodedLinkage(FS->linkage()));
2896   NameVals.push_back(FS->instCount());
2897   NameVals.push_back(FS->refs().size());
2898 
2899   for (auto &RI : FS->refs())
2900     NameVals.push_back(RI);
2901 
2902   bool HasProfileData = F.getEntryCount().hasValue();
2903   for (auto &ECI : FS->edges()) {
2904     NameVals.push_back(ECI.first);
2905     assert(ECI.second.CallsiteCount > 0 && "Expected at least one callsite");
2906     NameVals.push_back(ECI.second.CallsiteCount);
2907     if (HasProfileData)
2908       NameVals.push_back(ECI.second.ProfileCount);
2909   }
2910 
2911   unsigned FSAbbrev = (HasProfileData ? FSCallsProfileAbbrev : FSCallsAbbrev);
2912   unsigned Code =
2913       (HasProfileData ? bitc::FS_PERMODULE_PROFILE : bitc::FS_PERMODULE);
2914 
2915   // Emit the finished record.
2916   Stream.EmitRecord(Code, NameVals, FSAbbrev);
2917   NameVals.clear();
2918 }
2919 
2920 // Collect the global value references in the given variable's initializer,
2921 // and emit them in a summary record.
2922 static void WriteModuleLevelReferences(const GlobalVariable &V,
2923                                        const ValueEnumerator &VE,
2924                                        SmallVector<uint64_t, 64> &NameVals,
2925                                        unsigned FSModRefsAbbrev,
2926                                        BitstreamWriter &Stream) {
2927   // Only interested in recording variable defs in the summary.
2928   if (V.isDeclaration())
2929     return;
2930   DenseSet<unsigned> RefEdges;
2931   SmallPtrSet<const User *, 8> Visited;
2932   findRefEdges(&V, VE, RefEdges, Visited);
2933   NameVals.push_back(VE.getValueID(&V));
2934   NameVals.push_back(getEncodedLinkage(V.getLinkage()));
2935   for (auto RefId : RefEdges) {
2936     NameVals.push_back(RefId);
2937   }
2938   Stream.EmitRecord(bitc::FS_PERMODULE_GLOBALVAR_INIT_REFS, NameVals,
2939                     FSModRefsAbbrev);
2940   NameVals.clear();
2941 }
2942 
2943 /// Emit the per-module summary section alongside the rest of
2944 /// the module's bitcode.
2945 static void WritePerModuleGlobalValueSummary(
2946     DenseMap<const Function *, std::unique_ptr<GlobalValueInfo>> &FunctionIndex,
2947     const Module *M, const ValueEnumerator &VE, BitstreamWriter &Stream) {
2948   if (M->empty())
2949     return;
2950 
2951   Stream.EnterSubblock(bitc::GLOBALVAL_SUMMARY_BLOCK_ID, 3);
2952 
2953   // Abbrev for FS_PERMODULE.
2954   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2955   Abbv->Add(BitCodeAbbrevOp(bitc::FS_PERMODULE));
2956   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
2957   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 5)); // linkage
2958   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
2959   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
2960   // numrefs x valueid, n x (valueid, callsitecount)
2961   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2962   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
2963   unsigned FSCallsAbbrev = Stream.EmitAbbrev(Abbv);
2964 
2965   // Abbrev for FS_PERMODULE_PROFILE.
2966   Abbv = new BitCodeAbbrev();
2967   Abbv->Add(BitCodeAbbrevOp(bitc::FS_PERMODULE_PROFILE));
2968   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
2969   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 5)); // linkage
2970   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
2971   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
2972   // numrefs x valueid, n x (valueid, callsitecount, profilecount)
2973   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2974   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
2975   unsigned FSCallsProfileAbbrev = Stream.EmitAbbrev(Abbv);
2976 
2977   // Abbrev for FS_PERMODULE_GLOBALVAR_INIT_REFS.
2978   Abbv = new BitCodeAbbrev();
2979   Abbv->Add(BitCodeAbbrevOp(bitc::FS_PERMODULE_GLOBALVAR_INIT_REFS));
2980   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // valueid
2981   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 5)); // linkage
2982   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));  // valueids
2983   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
2984   unsigned FSModRefsAbbrev = Stream.EmitAbbrev(Abbv);
2985 
2986   SmallVector<uint64_t, 64> NameVals;
2987   // Iterate over the list of functions instead of the FunctionIndex map to
2988   // ensure the ordering is stable.
2989   for (const Function &F : *M) {
2990     if (F.isDeclaration())
2991       continue;
2992     // Skip anonymous functions. We will emit a function summary for
2993     // any aliases below.
2994     if (!F.hasName())
2995       continue;
2996 
2997     assert(FunctionIndex.count(&F) == 1);
2998 
2999     WritePerModuleFunctionSummaryRecord(
3000         NameVals, cast<FunctionSummary>(FunctionIndex[&F]->summary()),
3001         VE.getValueID(M->getValueSymbolTable().lookup(F.getName())),
3002         FSCallsAbbrev, FSCallsProfileAbbrev, Stream, F);
3003   }
3004 
3005   for (const GlobalAlias &A : M->aliases()) {
3006     if (!A.getBaseObject())
3007       continue;
3008     const Function *F = dyn_cast<Function>(A.getBaseObject());
3009     if (!F || F->isDeclaration())
3010       continue;
3011 
3012     assert(FunctionIndex.count(F) == 1);
3013     FunctionSummary *FS =
3014         cast<FunctionSummary>(FunctionIndex[F]->summary());
3015     // Add the alias to the reference list of aliasee function.
3016     FS->addRefEdge(
3017         VE.getValueID(M->getValueSymbolTable().lookup(A.getName())));
3018     WritePerModuleFunctionSummaryRecord(
3019         NameVals, FS,
3020         VE.getValueID(M->getValueSymbolTable().lookup(A.getName())),
3021         FSCallsAbbrev, FSCallsProfileAbbrev, Stream, *F);
3022   }
3023 
3024   // Capture references from GlobalVariable initializers, which are outside
3025   // of a function scope.
3026   for (const GlobalVariable &G : M->globals())
3027     WriteModuleLevelReferences(G, VE, NameVals, FSModRefsAbbrev, Stream);
3028   for (const GlobalAlias &A : M->aliases())
3029     if (auto *GV = dyn_cast<GlobalVariable>(A.getBaseObject()))
3030       WriteModuleLevelReferences(*GV, VE, NameVals, FSModRefsAbbrev, Stream);
3031 
3032   Stream.ExitBlock();
3033 }
3034 
3035 /// Emit the combined summary section into the combined index file.
3036 static void WriteCombinedGlobalValueSummary(
3037     const ModuleSummaryIndex &I, BitstreamWriter &Stream,
3038     std::map<uint64_t, unsigned> &GUIDToValueIdMap, unsigned GlobalValueId) {
3039   Stream.EnterSubblock(bitc::GLOBALVAL_SUMMARY_BLOCK_ID, 3);
3040 
3041   // Abbrev for FS_COMBINED.
3042   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
3043   Abbv->Add(BitCodeAbbrevOp(bitc::FS_COMBINED));
3044   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // modid
3045   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 5)); // linkage
3046   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
3047   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
3048   // numrefs x valueid, n x (valueid, callsitecount)
3049   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3050   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3051   unsigned FSCallsAbbrev = Stream.EmitAbbrev(Abbv);
3052 
3053   // Abbrev for FS_COMBINED_PROFILE.
3054   Abbv = new BitCodeAbbrev();
3055   Abbv->Add(BitCodeAbbrevOp(bitc::FS_COMBINED_PROFILE));
3056   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // modid
3057   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 5)); // linkage
3058   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
3059   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
3060   // numrefs x valueid, n x (valueid, callsitecount, profilecount)
3061   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3062   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3063   unsigned FSCallsProfileAbbrev = Stream.EmitAbbrev(Abbv);
3064 
3065   // Abbrev for FS_COMBINED_GLOBALVAR_INIT_REFS.
3066   Abbv = new BitCodeAbbrev();
3067   Abbv->Add(BitCodeAbbrevOp(bitc::FS_COMBINED_GLOBALVAR_INIT_REFS));
3068   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // modid
3069   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 5)); // linkage
3070   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));    // valueids
3071   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3072   unsigned FSModRefsAbbrev = Stream.EmitAbbrev(Abbv);
3073 
3074   SmallVector<uint64_t, 64> NameVals;
3075   for (const auto &FII : I) {
3076     for (auto &FI : FII.second) {
3077       GlobalValueSummary *S = FI->summary();
3078       assert(S);
3079 
3080       if (auto *VS = dyn_cast<GlobalVarSummary>(S)) {
3081         NameVals.push_back(I.getModuleId(VS->modulePath()));
3082         NameVals.push_back(getEncodedLinkage(VS->linkage()));
3083         for (auto &RI : VS->refs()) {
3084           const auto &VMI = GUIDToValueIdMap.find(RI);
3085           unsigned RefId;
3086           // If this GUID doesn't have an entry, assign one.
3087           if (VMI == GUIDToValueIdMap.end()) {
3088             GUIDToValueIdMap[RI] = ++GlobalValueId;
3089             RefId = GlobalValueId;
3090           } else {
3091             RefId = VMI->second;
3092           }
3093           NameVals.push_back(RefId);
3094         }
3095 
3096         // Record the starting offset of this summary entry for use
3097         // in the VST entry. Add the current code size since the
3098         // reader will invoke readRecord after the abbrev id read.
3099         FI->setBitcodeIndex(Stream.GetCurrentBitNo() +
3100                             Stream.GetAbbrevIDWidth());
3101 
3102         // Emit the finished record.
3103         Stream.EmitRecord(bitc::FS_COMBINED_GLOBALVAR_INIT_REFS, NameVals,
3104                           FSModRefsAbbrev);
3105         NameVals.clear();
3106         continue;
3107       }
3108 
3109       auto *FS = cast<FunctionSummary>(S);
3110       NameVals.push_back(I.getModuleId(FS->modulePath()));
3111       NameVals.push_back(getEncodedLinkage(FS->linkage()));
3112       NameVals.push_back(FS->instCount());
3113       NameVals.push_back(FS->refs().size());
3114 
3115       for (auto &RI : FS->refs()) {
3116         const auto &VMI = GUIDToValueIdMap.find(RI);
3117         unsigned RefId;
3118         // If this GUID doesn't have an entry, assign one.
3119         if (VMI == GUIDToValueIdMap.end()) {
3120           GUIDToValueIdMap[RI] = ++GlobalValueId;
3121           RefId = GlobalValueId;
3122         } else {
3123           RefId = VMI->second;
3124         }
3125         NameVals.push_back(RefId);
3126       }
3127 
3128       bool HasProfileData = false;
3129       for (auto &EI : FS->edges()) {
3130         HasProfileData |= EI.second.ProfileCount != 0;
3131         if (HasProfileData)
3132           break;
3133       }
3134 
3135       for (auto &EI : FS->edges()) {
3136         const auto &VMI = GUIDToValueIdMap.find(EI.first);
3137         // If this GUID doesn't have an entry, it doesn't have a function
3138         // summary and we don't need to record any calls to it.
3139         if (VMI == GUIDToValueIdMap.end())
3140           continue;
3141         NameVals.push_back(VMI->second);
3142         assert(EI.second.CallsiteCount > 0 && "Expected at least one callsite");
3143         NameVals.push_back(EI.second.CallsiteCount);
3144         if (HasProfileData)
3145           NameVals.push_back(EI.second.ProfileCount);
3146       }
3147 
3148       // Record the starting offset of this summary entry for use
3149       // in the VST entry. Add the current code size since the
3150       // reader will invoke readRecord after the abbrev id read.
3151       FI->setBitcodeIndex(Stream.GetCurrentBitNo() + Stream.GetAbbrevIDWidth());
3152 
3153       unsigned FSAbbrev =
3154           (HasProfileData ? FSCallsProfileAbbrev : FSCallsAbbrev);
3155       unsigned Code =
3156           (HasProfileData ? bitc::FS_COMBINED_PROFILE : bitc::FS_COMBINED);
3157 
3158       // Emit the finished record.
3159       Stream.EmitRecord(Code, NameVals, FSAbbrev);
3160       NameVals.clear();
3161     }
3162   }
3163 
3164   Stream.ExitBlock();
3165 }
3166 
3167 // Create the "IDENTIFICATION_BLOCK_ID" containing a single string with the
3168 // current llvm version, and a record for the epoch number.
3169 static void WriteIdentificationBlock(const Module *M, BitstreamWriter &Stream) {
3170   Stream.EnterSubblock(bitc::IDENTIFICATION_BLOCK_ID, 5);
3171 
3172   // Write the "user readable" string identifying the bitcode producer
3173   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
3174   Abbv->Add(BitCodeAbbrevOp(bitc::IDENTIFICATION_CODE_STRING));
3175   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3176   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
3177   auto StringAbbrev = Stream.EmitAbbrev(Abbv);
3178   WriteStringRecord(bitc::IDENTIFICATION_CODE_STRING,
3179                     "LLVM" LLVM_VERSION_STRING, StringAbbrev, Stream);
3180 
3181   // Write the epoch version
3182   Abbv = new BitCodeAbbrev();
3183   Abbv->Add(BitCodeAbbrevOp(bitc::IDENTIFICATION_CODE_EPOCH));
3184   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
3185   auto EpochAbbrev = Stream.EmitAbbrev(Abbv);
3186   SmallVector<unsigned, 1> Vals = {bitc::BITCODE_CURRENT_EPOCH};
3187   Stream.EmitRecord(bitc::IDENTIFICATION_CODE_EPOCH, Vals, EpochAbbrev);
3188   Stream.ExitBlock();
3189 }
3190 
3191 /// WriteModule - Emit the specified module to the bitstream.
3192 static void WriteModule(const Module *M, BitstreamWriter &Stream,
3193                         bool ShouldPreserveUseListOrder,
3194                         uint64_t BitcodeStartBit, bool EmitSummaryIndex) {
3195   Stream.EnterSubblock(bitc::MODULE_BLOCK_ID, 3);
3196 
3197   SmallVector<unsigned, 1> Vals;
3198   unsigned CurVersion = 1;
3199   Vals.push_back(CurVersion);
3200   Stream.EmitRecord(bitc::MODULE_CODE_VERSION, Vals);
3201 
3202   // Analyze the module, enumerating globals, functions, etc.
3203   ValueEnumerator VE(*M, ShouldPreserveUseListOrder);
3204 
3205   // Emit blockinfo, which defines the standard abbreviations etc.
3206   WriteBlockInfo(VE, Stream);
3207 
3208   // Emit information about attribute groups.
3209   WriteAttributeGroupTable(VE, Stream);
3210 
3211   // Emit information about parameter attributes.
3212   WriteAttributeTable(VE, Stream);
3213 
3214   // Emit information describing all of the types in the module.
3215   WriteTypeTable(VE, Stream);
3216 
3217   writeComdats(VE, Stream);
3218 
3219   // Emit top-level description of module, including target triple, inline asm,
3220   // descriptors for global variables, and function prototype info.
3221   uint64_t VSTOffsetPlaceholder = WriteModuleInfo(M, VE, Stream);
3222 
3223   // Emit constants.
3224   WriteModuleConstants(VE, Stream);
3225 
3226   // Emit metadata.
3227   WriteModuleMetadata(*M, VE, Stream);
3228 
3229   // Emit metadata.
3230   WriteModuleMetadataStore(M, Stream);
3231 
3232   // Emit module-level use-lists.
3233   if (VE.shouldPreserveUseListOrder())
3234     WriteUseListBlock(nullptr, VE, Stream);
3235 
3236   WriteOperandBundleTags(M, Stream);
3237 
3238   // Emit function bodies.
3239   DenseMap<const Function *, std::unique_ptr<GlobalValueInfo>> FunctionIndex;
3240   for (Module::const_iterator F = M->begin(), E = M->end(); F != E; ++F)
3241     if (!F->isDeclaration())
3242       WriteFunction(*F, M, VE, Stream, FunctionIndex, EmitSummaryIndex);
3243 
3244   // Need to write after the above call to WriteFunction which populates
3245   // the summary information in the index.
3246   if (EmitSummaryIndex)
3247     WritePerModuleGlobalValueSummary(FunctionIndex, M, VE, Stream);
3248 
3249   WriteValueSymbolTable(M->getValueSymbolTable(), VE, Stream,
3250                         VSTOffsetPlaceholder, BitcodeStartBit, &FunctionIndex);
3251 
3252   Stream.ExitBlock();
3253 }
3254 
3255 /// EmitDarwinBCHeader - If generating a bc file on darwin, we have to emit a
3256 /// header and trailer to make it compatible with the system archiver.  To do
3257 /// this we emit the following header, and then emit a trailer that pads the
3258 /// file out to be a multiple of 16 bytes.
3259 ///
3260 /// struct bc_header {
3261 ///   uint32_t Magic;         // 0x0B17C0DE
3262 ///   uint32_t Version;       // Version, currently always 0.
3263 ///   uint32_t BitcodeOffset; // Offset to traditional bitcode file.
3264 ///   uint32_t BitcodeSize;   // Size of traditional bitcode file.
3265 ///   uint32_t CPUType;       // CPU specifier.
3266 ///   ... potentially more later ...
3267 /// };
3268 
3269 static void WriteInt32ToBuffer(uint32_t Value, SmallVectorImpl<char> &Buffer,
3270                                uint32_t &Position) {
3271   support::endian::write32le(&Buffer[Position], Value);
3272   Position += 4;
3273 }
3274 
3275 static void EmitDarwinBCHeaderAndTrailer(SmallVectorImpl<char> &Buffer,
3276                                          const Triple &TT) {
3277   unsigned CPUType = ~0U;
3278 
3279   // Match x86_64-*, i[3-9]86-*, powerpc-*, powerpc64-*, arm-*, thumb-*,
3280   // armv[0-9]-*, thumbv[0-9]-*, armv5te-*, or armv6t2-*. The CPUType is a magic
3281   // number from /usr/include/mach/machine.h.  It is ok to reproduce the
3282   // specific constants here because they are implicitly part of the Darwin ABI.
3283   enum {
3284     DARWIN_CPU_ARCH_ABI64      = 0x01000000,
3285     DARWIN_CPU_TYPE_X86        = 7,
3286     DARWIN_CPU_TYPE_ARM        = 12,
3287     DARWIN_CPU_TYPE_POWERPC    = 18
3288   };
3289 
3290   Triple::ArchType Arch = TT.getArch();
3291   if (Arch == Triple::x86_64)
3292     CPUType = DARWIN_CPU_TYPE_X86 | DARWIN_CPU_ARCH_ABI64;
3293   else if (Arch == Triple::x86)
3294     CPUType = DARWIN_CPU_TYPE_X86;
3295   else if (Arch == Triple::ppc)
3296     CPUType = DARWIN_CPU_TYPE_POWERPC;
3297   else if (Arch == Triple::ppc64)
3298     CPUType = DARWIN_CPU_TYPE_POWERPC | DARWIN_CPU_ARCH_ABI64;
3299   else if (Arch == Triple::arm || Arch == Triple::thumb)
3300     CPUType = DARWIN_CPU_TYPE_ARM;
3301 
3302   // Traditional Bitcode starts after header.
3303   assert(Buffer.size() >= BWH_HeaderSize &&
3304          "Expected header size to be reserved");
3305   unsigned BCOffset = BWH_HeaderSize;
3306   unsigned BCSize = Buffer.size() - BWH_HeaderSize;
3307 
3308   // Write the magic and version.
3309   unsigned Position = 0;
3310   WriteInt32ToBuffer(0x0B17C0DE , Buffer, Position);
3311   WriteInt32ToBuffer(0          , Buffer, Position); // Version.
3312   WriteInt32ToBuffer(BCOffset   , Buffer, Position);
3313   WriteInt32ToBuffer(BCSize     , Buffer, Position);
3314   WriteInt32ToBuffer(CPUType    , Buffer, Position);
3315 
3316   // If the file is not a multiple of 16 bytes, insert dummy padding.
3317   while (Buffer.size() & 15)
3318     Buffer.push_back(0);
3319 }
3320 
3321 /// Helper to write the header common to all bitcode files.
3322 static void WriteBitcodeHeader(BitstreamWriter &Stream) {
3323   // Emit the file header.
3324   Stream.Emit((unsigned)'B', 8);
3325   Stream.Emit((unsigned)'C', 8);
3326   Stream.Emit(0x0, 4);
3327   Stream.Emit(0xC, 4);
3328   Stream.Emit(0xE, 4);
3329   Stream.Emit(0xD, 4);
3330 }
3331 
3332 /// WriteBitcodeToFile - Write the specified module to the specified output
3333 /// stream.
3334 void llvm::WriteBitcodeToFile(const Module *M, raw_ostream &Out,
3335                               bool ShouldPreserveUseListOrder,
3336                               bool EmitSummaryIndex) {
3337   SmallVector<char, 0> Buffer;
3338   Buffer.reserve(256*1024);
3339 
3340   // If this is darwin or another generic macho target, reserve space for the
3341   // header.
3342   Triple TT(M->getTargetTriple());
3343   if (TT.isOSDarwin() || TT.isOSBinFormatMachO())
3344     Buffer.insert(Buffer.begin(), BWH_HeaderSize, 0);
3345 
3346   // Emit the module into the buffer.
3347   {
3348     BitstreamWriter Stream(Buffer);
3349     // Save the start bit of the actual bitcode, in case there is space
3350     // saved at the start for the darwin header above. The reader stream
3351     // will start at the bitcode, and we need the offset of the VST
3352     // to line up.
3353     uint64_t BitcodeStartBit = Stream.GetCurrentBitNo();
3354 
3355     // Emit the file header.
3356     WriteBitcodeHeader(Stream);
3357 
3358     WriteIdentificationBlock(M, Stream);
3359 
3360     // Emit the module.
3361     WriteModule(M, Stream, ShouldPreserveUseListOrder, BitcodeStartBit,
3362                 EmitSummaryIndex);
3363   }
3364 
3365   if (TT.isOSDarwin() || TT.isOSBinFormatMachO())
3366     EmitDarwinBCHeaderAndTrailer(Buffer, TT);
3367 
3368   // Write the generated bitstream to "Out".
3369   Out.write((char*)&Buffer.front(), Buffer.size());
3370 }
3371 
3372 // Write the specified module summary index to the given raw output stream,
3373 // where it will be written in a new bitcode block. This is used when
3374 // writing the combined index file for ThinLTO.
3375 void llvm::WriteIndexToFile(const ModuleSummaryIndex &Index, raw_ostream &Out) {
3376   SmallVector<char, 0> Buffer;
3377   Buffer.reserve(256 * 1024);
3378 
3379   BitstreamWriter Stream(Buffer);
3380 
3381   // Emit the bitcode header.
3382   WriteBitcodeHeader(Stream);
3383 
3384   Stream.EnterSubblock(bitc::MODULE_BLOCK_ID, 3);
3385 
3386   SmallVector<unsigned, 1> Vals;
3387   unsigned CurVersion = 1;
3388   Vals.push_back(CurVersion);
3389   Stream.EmitRecord(bitc::MODULE_CODE_VERSION, Vals);
3390 
3391   // If we have a VST, write the VSTOFFSET record placeholder and record
3392   // its offset.
3393   uint64_t VSTOffsetPlaceholder = WriteValueSymbolTableForwardDecl(Stream);
3394 
3395   // Write the module paths in the combined index.
3396   WriteModStrings(Index, Stream);
3397 
3398   // Assign unique value ids to all functions in the index for use
3399   // in writing out the call graph edges. Save the mapping from GUID
3400   // to the new global value id to use when writing those edges, which
3401   // are currently saved in the index in terms of GUID.
3402   std::map<uint64_t, unsigned> GUIDToValueIdMap;
3403   unsigned GlobalValueId = 0;
3404   for (auto &II : Index)
3405     GUIDToValueIdMap[II.first] = ++GlobalValueId;
3406 
3407   // Write the summary combined index records.
3408   WriteCombinedGlobalValueSummary(Index, Stream, GUIDToValueIdMap,
3409                                   GlobalValueId);
3410 
3411   // Need a special VST writer for the combined index (we don't have a
3412   // real VST and real values when this is invoked).
3413   WriteCombinedValueSymbolTable(Index, Stream, GUIDToValueIdMap,
3414                                 VSTOffsetPlaceholder);
3415 
3416   Stream.ExitBlock();
3417 
3418   Out.write((char *)&Buffer.front(), Buffer.size());
3419 }
3420