xref: /llvm-project/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp (revision 625fda2714acd03ea7c38887e827735d2af3102f)
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   // Write a record indicating the number of module-level metadata IDs
807   // This is needed because the ids of metadata are assigned implicitly
808   // based on their ordering in the bitcode, with the function-level
809   // metadata ids starting after the module-level metadata ids. For
810   // function importing where we lazy load the metadata as a postpass,
811   // we want to avoid parsing the module-level metadata before parsing
812   // the imported functions.
813   {
814     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
815     Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_METADATA_VALUES));
816     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
817     unsigned MDValsAbbrev = Stream.EmitAbbrev(Abbv);
818     Vals.push_back(VE.numMDs());
819     Stream.EmitRecord(bitc::MODULE_CODE_METADATA_VALUES, Vals, MDValsAbbrev);
820     Vals.clear();
821   }
822 
823   // Emit the module's source file name.
824   {
825     StringEncoding Bits = getStringEncoding(M->getSourceFileName().data(),
826                                             M->getSourceFileName().size());
827     BitCodeAbbrevOp AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8);
828     if (Bits == SE_Char6)
829       AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Char6);
830     else if (Bits == SE_Fixed7)
831       AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7);
832 
833     // MODULE_CODE_SOURCE_FILENAME: [namechar x N]
834     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
835     Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_SOURCE_FILENAME));
836     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
837     Abbv->Add(AbbrevOpToUse);
838     unsigned FilenameAbbrev = Stream.EmitAbbrev(Abbv);
839 
840     for (const auto P : M->getSourceFileName())
841       Vals.push_back((unsigned char)P);
842 
843     // Emit the finished record.
844     Stream.EmitRecord(bitc::MODULE_CODE_SOURCE_FILENAME, Vals, FilenameAbbrev);
845     Vals.clear();
846   }
847 
848   // If we have a VST, write the VSTOFFSET record placeholder and return
849   // its offset.
850   if (M->getValueSymbolTable().empty())
851     return 0;
852   return WriteValueSymbolTableForwardDecl(Stream);
853 }
854 
855 static uint64_t GetOptimizationFlags(const Value *V) {
856   uint64_t Flags = 0;
857 
858   if (const auto *OBO = dyn_cast<OverflowingBinaryOperator>(V)) {
859     if (OBO->hasNoSignedWrap())
860       Flags |= 1 << bitc::OBO_NO_SIGNED_WRAP;
861     if (OBO->hasNoUnsignedWrap())
862       Flags |= 1 << bitc::OBO_NO_UNSIGNED_WRAP;
863   } else if (const auto *PEO = dyn_cast<PossiblyExactOperator>(V)) {
864     if (PEO->isExact())
865       Flags |= 1 << bitc::PEO_EXACT;
866   } else if (const auto *FPMO = dyn_cast<FPMathOperator>(V)) {
867     if (FPMO->hasUnsafeAlgebra())
868       Flags |= FastMathFlags::UnsafeAlgebra;
869     if (FPMO->hasNoNaNs())
870       Flags |= FastMathFlags::NoNaNs;
871     if (FPMO->hasNoInfs())
872       Flags |= FastMathFlags::NoInfs;
873     if (FPMO->hasNoSignedZeros())
874       Flags |= FastMathFlags::NoSignedZeros;
875     if (FPMO->hasAllowReciprocal())
876       Flags |= FastMathFlags::AllowReciprocal;
877   }
878 
879   return Flags;
880 }
881 
882 static void WriteValueAsMetadata(const ValueAsMetadata *MD,
883                                  const ValueEnumerator &VE,
884                                  BitstreamWriter &Stream,
885                                  SmallVectorImpl<uint64_t> &Record) {
886   // Mimic an MDNode with a value as one operand.
887   Value *V = MD->getValue();
888   Record.push_back(VE.getTypeID(V->getType()));
889   Record.push_back(VE.getValueID(V));
890   Stream.EmitRecord(bitc::METADATA_VALUE, Record, 0);
891   Record.clear();
892 }
893 
894 static void WriteMDTuple(const MDTuple *N, const ValueEnumerator &VE,
895                          BitstreamWriter &Stream,
896                          SmallVectorImpl<uint64_t> &Record, unsigned Abbrev) {
897   for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i) {
898     Metadata *MD = N->getOperand(i);
899     assert(!(MD && isa<LocalAsMetadata>(MD)) &&
900            "Unexpected function-local metadata");
901     Record.push_back(VE.getMetadataOrNullID(MD));
902   }
903   Stream.EmitRecord(N->isDistinct() ? bitc::METADATA_DISTINCT_NODE
904                                     : bitc::METADATA_NODE,
905                     Record, Abbrev);
906   Record.clear();
907 }
908 
909 static unsigned createDILocationAbbrev(BitstreamWriter &Stream) {
910   // Assume the column is usually under 128, and always output the inlined-at
911   // location (it's never more expensive than building an array size 1).
912   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
913   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_LOCATION));
914   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
915   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
916   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
917   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
918   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
919   return Stream.EmitAbbrev(Abbv);
920 }
921 
922 static void WriteDILocation(const DILocation *N, const ValueEnumerator &VE,
923                             BitstreamWriter &Stream,
924                             SmallVectorImpl<uint64_t> &Record,
925                             unsigned &Abbrev) {
926   if (!Abbrev)
927     Abbrev = createDILocationAbbrev(Stream);
928 
929   Record.push_back(N->isDistinct());
930   Record.push_back(N->getLine());
931   Record.push_back(N->getColumn());
932   Record.push_back(VE.getMetadataID(N->getScope()));
933   Record.push_back(VE.getMetadataOrNullID(N->getInlinedAt()));
934 
935   Stream.EmitRecord(bitc::METADATA_LOCATION, Record, Abbrev);
936   Record.clear();
937 }
938 
939 static void WriteGenericDINode(const GenericDINode *N,
940                                const ValueEnumerator &VE,
941                                BitstreamWriter &Stream,
942                                SmallVectorImpl<uint64_t> &Record,
943                                unsigned Abbrev) {
944   Record.push_back(N->isDistinct());
945   Record.push_back(N->getTag());
946   Record.push_back(0); // Per-tag version field; unused for now.
947 
948   for (auto &I : N->operands())
949     Record.push_back(VE.getMetadataOrNullID(I));
950 
951   Stream.EmitRecord(bitc::METADATA_GENERIC_DEBUG, Record, Abbrev);
952   Record.clear();
953 }
954 
955 static uint64_t rotateSign(int64_t I) {
956   uint64_t U = I;
957   return I < 0 ? ~(U << 1) : U << 1;
958 }
959 
960 static void WriteDISubrange(const DISubrange *N, const ValueEnumerator &,
961                             BitstreamWriter &Stream,
962                             SmallVectorImpl<uint64_t> &Record,
963                             unsigned Abbrev) {
964   Record.push_back(N->isDistinct());
965   Record.push_back(N->getCount());
966   Record.push_back(rotateSign(N->getLowerBound()));
967 
968   Stream.EmitRecord(bitc::METADATA_SUBRANGE, Record, Abbrev);
969   Record.clear();
970 }
971 
972 static void WriteDIEnumerator(const DIEnumerator *N, const ValueEnumerator &VE,
973                               BitstreamWriter &Stream,
974                               SmallVectorImpl<uint64_t> &Record,
975                               unsigned Abbrev) {
976   Record.push_back(N->isDistinct());
977   Record.push_back(rotateSign(N->getValue()));
978   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
979 
980   Stream.EmitRecord(bitc::METADATA_ENUMERATOR, Record, Abbrev);
981   Record.clear();
982 }
983 
984 static void WriteDIBasicType(const DIBasicType *N, const ValueEnumerator &VE,
985                              BitstreamWriter &Stream,
986                              SmallVectorImpl<uint64_t> &Record,
987                              unsigned Abbrev) {
988   Record.push_back(N->isDistinct());
989   Record.push_back(N->getTag());
990   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
991   Record.push_back(N->getSizeInBits());
992   Record.push_back(N->getAlignInBits());
993   Record.push_back(N->getEncoding());
994 
995   Stream.EmitRecord(bitc::METADATA_BASIC_TYPE, Record, Abbrev);
996   Record.clear();
997 }
998 
999 static void WriteDIDerivedType(const DIDerivedType *N,
1000                                const ValueEnumerator &VE,
1001                                BitstreamWriter &Stream,
1002                                SmallVectorImpl<uint64_t> &Record,
1003                                unsigned Abbrev) {
1004   Record.push_back(N->isDistinct());
1005   Record.push_back(N->getTag());
1006   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1007   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1008   Record.push_back(N->getLine());
1009   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1010   Record.push_back(VE.getMetadataOrNullID(N->getBaseType()));
1011   Record.push_back(N->getSizeInBits());
1012   Record.push_back(N->getAlignInBits());
1013   Record.push_back(N->getOffsetInBits());
1014   Record.push_back(N->getFlags());
1015   Record.push_back(VE.getMetadataOrNullID(N->getExtraData()));
1016 
1017   Stream.EmitRecord(bitc::METADATA_DERIVED_TYPE, Record, Abbrev);
1018   Record.clear();
1019 }
1020 
1021 static void WriteDICompositeType(const DICompositeType *N,
1022                                  const ValueEnumerator &VE,
1023                                  BitstreamWriter &Stream,
1024                                  SmallVectorImpl<uint64_t> &Record,
1025                                  unsigned Abbrev) {
1026   Record.push_back(N->isDistinct());
1027   Record.push_back(N->getTag());
1028   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1029   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1030   Record.push_back(N->getLine());
1031   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1032   Record.push_back(VE.getMetadataOrNullID(N->getBaseType()));
1033   Record.push_back(N->getSizeInBits());
1034   Record.push_back(N->getAlignInBits());
1035   Record.push_back(N->getOffsetInBits());
1036   Record.push_back(N->getFlags());
1037   Record.push_back(VE.getMetadataOrNullID(N->getElements().get()));
1038   Record.push_back(N->getRuntimeLang());
1039   Record.push_back(VE.getMetadataOrNullID(N->getVTableHolder()));
1040   Record.push_back(VE.getMetadataOrNullID(N->getTemplateParams().get()));
1041   Record.push_back(VE.getMetadataOrNullID(N->getRawIdentifier()));
1042 
1043   Stream.EmitRecord(bitc::METADATA_COMPOSITE_TYPE, Record, Abbrev);
1044   Record.clear();
1045 }
1046 
1047 static void WriteDISubroutineType(const DISubroutineType *N,
1048                                   const ValueEnumerator &VE,
1049                                   BitstreamWriter &Stream,
1050                                   SmallVectorImpl<uint64_t> &Record,
1051                                   unsigned Abbrev) {
1052   Record.push_back(N->isDistinct());
1053   Record.push_back(N->getFlags());
1054   Record.push_back(VE.getMetadataOrNullID(N->getTypeArray().get()));
1055 
1056   Stream.EmitRecord(bitc::METADATA_SUBROUTINE_TYPE, Record, Abbrev);
1057   Record.clear();
1058 }
1059 
1060 static void WriteDIFile(const DIFile *N, const ValueEnumerator &VE,
1061                         BitstreamWriter &Stream,
1062                         SmallVectorImpl<uint64_t> &Record, unsigned Abbrev) {
1063   Record.push_back(N->isDistinct());
1064   Record.push_back(VE.getMetadataOrNullID(N->getRawFilename()));
1065   Record.push_back(VE.getMetadataOrNullID(N->getRawDirectory()));
1066 
1067   Stream.EmitRecord(bitc::METADATA_FILE, Record, Abbrev);
1068   Record.clear();
1069 }
1070 
1071 static void WriteDICompileUnit(const DICompileUnit *N,
1072                                const ValueEnumerator &VE,
1073                                BitstreamWriter &Stream,
1074                                SmallVectorImpl<uint64_t> &Record,
1075                                unsigned Abbrev) {
1076   assert(N->isDistinct() && "Expected distinct compile units");
1077   Record.push_back(/* IsDistinct */ true);
1078   Record.push_back(N->getSourceLanguage());
1079   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1080   Record.push_back(VE.getMetadataOrNullID(N->getRawProducer()));
1081   Record.push_back(N->isOptimized());
1082   Record.push_back(VE.getMetadataOrNullID(N->getRawFlags()));
1083   Record.push_back(N->getRuntimeVersion());
1084   Record.push_back(VE.getMetadataOrNullID(N->getRawSplitDebugFilename()));
1085   Record.push_back(N->getEmissionKind());
1086   Record.push_back(VE.getMetadataOrNullID(N->getEnumTypes().get()));
1087   Record.push_back(VE.getMetadataOrNullID(N->getRetainedTypes().get()));
1088   Record.push_back(VE.getMetadataOrNullID(N->getSubprograms().get()));
1089   Record.push_back(VE.getMetadataOrNullID(N->getGlobalVariables().get()));
1090   Record.push_back(VE.getMetadataOrNullID(N->getImportedEntities().get()));
1091   Record.push_back(N->getDWOId());
1092   Record.push_back(VE.getMetadataOrNullID(N->getMacros().get()));
1093 
1094   Stream.EmitRecord(bitc::METADATA_COMPILE_UNIT, Record, Abbrev);
1095   Record.clear();
1096 }
1097 
1098 static void WriteDISubprogram(const DISubprogram *N, const ValueEnumerator &VE,
1099                               BitstreamWriter &Stream,
1100                               SmallVectorImpl<uint64_t> &Record,
1101                               unsigned Abbrev) {
1102   Record.push_back(N->isDistinct());
1103   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1104   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1105   Record.push_back(VE.getMetadataOrNullID(N->getRawLinkageName()));
1106   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1107   Record.push_back(N->getLine());
1108   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1109   Record.push_back(N->isLocalToUnit());
1110   Record.push_back(N->isDefinition());
1111   Record.push_back(N->getScopeLine());
1112   Record.push_back(VE.getMetadataOrNullID(N->getContainingType()));
1113   Record.push_back(N->getVirtuality());
1114   Record.push_back(N->getVirtualIndex());
1115   Record.push_back(N->getFlags());
1116   Record.push_back(N->isOptimized());
1117   Record.push_back(VE.getMetadataOrNullID(N->getTemplateParams().get()));
1118   Record.push_back(VE.getMetadataOrNullID(N->getDeclaration()));
1119   Record.push_back(VE.getMetadataOrNullID(N->getVariables().get()));
1120 
1121   Stream.EmitRecord(bitc::METADATA_SUBPROGRAM, Record, Abbrev);
1122   Record.clear();
1123 }
1124 
1125 static void WriteDILexicalBlock(const DILexicalBlock *N,
1126                                 const ValueEnumerator &VE,
1127                                 BitstreamWriter &Stream,
1128                                 SmallVectorImpl<uint64_t> &Record,
1129                                 unsigned Abbrev) {
1130   Record.push_back(N->isDistinct());
1131   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1132   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1133   Record.push_back(N->getLine());
1134   Record.push_back(N->getColumn());
1135 
1136   Stream.EmitRecord(bitc::METADATA_LEXICAL_BLOCK, Record, Abbrev);
1137   Record.clear();
1138 }
1139 
1140 static void WriteDILexicalBlockFile(const DILexicalBlockFile *N,
1141                                     const ValueEnumerator &VE,
1142                                     BitstreamWriter &Stream,
1143                                     SmallVectorImpl<uint64_t> &Record,
1144                                     unsigned Abbrev) {
1145   Record.push_back(N->isDistinct());
1146   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1147   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1148   Record.push_back(N->getDiscriminator());
1149 
1150   Stream.EmitRecord(bitc::METADATA_LEXICAL_BLOCK_FILE, Record, Abbrev);
1151   Record.clear();
1152 }
1153 
1154 static void WriteDINamespace(const DINamespace *N, const ValueEnumerator &VE,
1155                              BitstreamWriter &Stream,
1156                              SmallVectorImpl<uint64_t> &Record,
1157                              unsigned Abbrev) {
1158   Record.push_back(N->isDistinct());
1159   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1160   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1161   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1162   Record.push_back(N->getLine());
1163 
1164   Stream.EmitRecord(bitc::METADATA_NAMESPACE, Record, Abbrev);
1165   Record.clear();
1166 }
1167 
1168 static void WriteDIMacro(const DIMacro *N, const ValueEnumerator &VE,
1169                          BitstreamWriter &Stream,
1170                          SmallVectorImpl<uint64_t> &Record, unsigned Abbrev) {
1171   Record.push_back(N->isDistinct());
1172   Record.push_back(N->getMacinfoType());
1173   Record.push_back(N->getLine());
1174   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1175   Record.push_back(VE.getMetadataOrNullID(N->getRawValue()));
1176 
1177   Stream.EmitRecord(bitc::METADATA_MACRO, Record, Abbrev);
1178   Record.clear();
1179 }
1180 
1181 static void WriteDIMacroFile(const DIMacroFile *N, const ValueEnumerator &VE,
1182                              BitstreamWriter &Stream,
1183                              SmallVectorImpl<uint64_t> &Record,
1184                              unsigned Abbrev) {
1185   Record.push_back(N->isDistinct());
1186   Record.push_back(N->getMacinfoType());
1187   Record.push_back(N->getLine());
1188   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1189   Record.push_back(VE.getMetadataOrNullID(N->getElements().get()));
1190 
1191   Stream.EmitRecord(bitc::METADATA_MACRO_FILE, Record, Abbrev);
1192   Record.clear();
1193 }
1194 
1195 static void WriteDIModule(const DIModule *N, const ValueEnumerator &VE,
1196                           BitstreamWriter &Stream,
1197                           SmallVectorImpl<uint64_t> &Record, unsigned Abbrev) {
1198   Record.push_back(N->isDistinct());
1199   for (auto &I : N->operands())
1200     Record.push_back(VE.getMetadataOrNullID(I));
1201 
1202   Stream.EmitRecord(bitc::METADATA_MODULE, Record, Abbrev);
1203   Record.clear();
1204 }
1205 
1206 static void WriteDITemplateTypeParameter(const DITemplateTypeParameter *N,
1207                                          const ValueEnumerator &VE,
1208                                          BitstreamWriter &Stream,
1209                                          SmallVectorImpl<uint64_t> &Record,
1210                                          unsigned Abbrev) {
1211   Record.push_back(N->isDistinct());
1212   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1213   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1214 
1215   Stream.EmitRecord(bitc::METADATA_TEMPLATE_TYPE, Record, Abbrev);
1216   Record.clear();
1217 }
1218 
1219 static void WriteDITemplateValueParameter(const DITemplateValueParameter *N,
1220                                           const ValueEnumerator &VE,
1221                                           BitstreamWriter &Stream,
1222                                           SmallVectorImpl<uint64_t> &Record,
1223                                           unsigned Abbrev) {
1224   Record.push_back(N->isDistinct());
1225   Record.push_back(N->getTag());
1226   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1227   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1228   Record.push_back(VE.getMetadataOrNullID(N->getValue()));
1229 
1230   Stream.EmitRecord(bitc::METADATA_TEMPLATE_VALUE, Record, Abbrev);
1231   Record.clear();
1232 }
1233 
1234 static void WriteDIGlobalVariable(const DIGlobalVariable *N,
1235                                   const ValueEnumerator &VE,
1236                                   BitstreamWriter &Stream,
1237                                   SmallVectorImpl<uint64_t> &Record,
1238                                   unsigned Abbrev) {
1239   Record.push_back(N->isDistinct());
1240   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1241   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1242   Record.push_back(VE.getMetadataOrNullID(N->getRawLinkageName()));
1243   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1244   Record.push_back(N->getLine());
1245   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1246   Record.push_back(N->isLocalToUnit());
1247   Record.push_back(N->isDefinition());
1248   Record.push_back(VE.getMetadataOrNullID(N->getRawVariable()));
1249   Record.push_back(VE.getMetadataOrNullID(N->getStaticDataMemberDeclaration()));
1250 
1251   Stream.EmitRecord(bitc::METADATA_GLOBAL_VAR, Record, Abbrev);
1252   Record.clear();
1253 }
1254 
1255 static void WriteDILocalVariable(const DILocalVariable *N,
1256                                  const ValueEnumerator &VE,
1257                                  BitstreamWriter &Stream,
1258                                  SmallVectorImpl<uint64_t> &Record,
1259                                  unsigned Abbrev) {
1260   Record.push_back(N->isDistinct());
1261   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1262   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1263   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1264   Record.push_back(N->getLine());
1265   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1266   Record.push_back(N->getArg());
1267   Record.push_back(N->getFlags());
1268 
1269   Stream.EmitRecord(bitc::METADATA_LOCAL_VAR, Record, Abbrev);
1270   Record.clear();
1271 }
1272 
1273 static void WriteDIExpression(const DIExpression *N, const ValueEnumerator &,
1274                               BitstreamWriter &Stream,
1275                               SmallVectorImpl<uint64_t> &Record,
1276                               unsigned Abbrev) {
1277   Record.reserve(N->getElements().size() + 1);
1278 
1279   Record.push_back(N->isDistinct());
1280   Record.append(N->elements_begin(), N->elements_end());
1281 
1282   Stream.EmitRecord(bitc::METADATA_EXPRESSION, Record, Abbrev);
1283   Record.clear();
1284 }
1285 
1286 static void WriteDIObjCProperty(const DIObjCProperty *N,
1287                                 const ValueEnumerator &VE,
1288                                 BitstreamWriter &Stream,
1289                                 SmallVectorImpl<uint64_t> &Record,
1290                                 unsigned Abbrev) {
1291   Record.push_back(N->isDistinct());
1292   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1293   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
1294   Record.push_back(N->getLine());
1295   Record.push_back(VE.getMetadataOrNullID(N->getRawSetterName()));
1296   Record.push_back(VE.getMetadataOrNullID(N->getRawGetterName()));
1297   Record.push_back(N->getAttributes());
1298   Record.push_back(VE.getMetadataOrNullID(N->getType()));
1299 
1300   Stream.EmitRecord(bitc::METADATA_OBJC_PROPERTY, Record, Abbrev);
1301   Record.clear();
1302 }
1303 
1304 static void WriteDIImportedEntity(const DIImportedEntity *N,
1305                                   const ValueEnumerator &VE,
1306                                   BitstreamWriter &Stream,
1307                                   SmallVectorImpl<uint64_t> &Record,
1308                                   unsigned Abbrev) {
1309   Record.push_back(N->isDistinct());
1310   Record.push_back(N->getTag());
1311   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
1312   Record.push_back(VE.getMetadataOrNullID(N->getEntity()));
1313   Record.push_back(N->getLine());
1314   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
1315 
1316   Stream.EmitRecord(bitc::METADATA_IMPORTED_ENTITY, Record, Abbrev);
1317   Record.clear();
1318 }
1319 
1320 static unsigned createNamedMetadataAbbrev(BitstreamWriter &Stream) {
1321   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1322   Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_NAME));
1323   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1324   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
1325   return Stream.EmitAbbrev(Abbv);
1326 }
1327 
1328 static void writeNamedMetadata(const Module &M, const ValueEnumerator &VE,
1329                                BitstreamWriter &Stream,
1330                                SmallVectorImpl<uint64_t> &Record) {
1331   if (M.named_metadata_empty())
1332     return;
1333 
1334   unsigned Abbrev = createNamedMetadataAbbrev(Stream);
1335   for (const NamedMDNode &NMD : M.named_metadata()) {
1336     // Write name.
1337     StringRef Str = NMD.getName();
1338     Record.append(Str.bytes_begin(), Str.bytes_end());
1339     Stream.EmitRecord(bitc::METADATA_NAME, Record, Abbrev);
1340     Record.clear();
1341 
1342     // Write named metadata operands.
1343     for (const MDNode *N : NMD.operands())
1344       Record.push_back(VE.getMetadataID(N));
1345     Stream.EmitRecord(bitc::METADATA_NAMED_NODE, Record, 0);
1346     Record.clear();
1347   }
1348 }
1349 
1350 static void WriteModuleMetadata(const Module &M,
1351                                 const ValueEnumerator &VE,
1352                                 BitstreamWriter &Stream) {
1353   const auto &MDs = VE.getMDs();
1354   if (MDs.empty() && M.named_metadata_empty())
1355     return;
1356 
1357   Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
1358 
1359   unsigned MDSAbbrev = 0;
1360   if (VE.hasMDString()) {
1361     // Abbrev for METADATA_STRING.
1362     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1363     Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_STRING));
1364     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1365     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
1366     MDSAbbrev = Stream.EmitAbbrev(Abbv);
1367   }
1368 
1369   // Initialize MDNode abbreviations.
1370 #define HANDLE_MDNODE_LEAF(CLASS) unsigned CLASS##Abbrev = 0;
1371 #include "llvm/IR/Metadata.def"
1372 
1373   if (VE.hasGenericDINode()) {
1374     // Abbrev for METADATA_GENERIC_DEBUG.
1375     //
1376     // Assume the column is usually under 128, and always output the inlined-at
1377     // location (it's never more expensive than building an array size 1).
1378     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1379     Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_GENERIC_DEBUG));
1380     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
1381     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1382     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
1383     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1384     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1385     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
1386     GenericDINodeAbbrev = Stream.EmitAbbrev(Abbv);
1387   }
1388 
1389   SmallVector<uint64_t, 64> Record;
1390   for (const Metadata *MD : MDs) {
1391     if (const MDNode *N = dyn_cast<MDNode>(MD)) {
1392       assert(N->isResolved() && "Expected forward references to be resolved");
1393 
1394       switch (N->getMetadataID()) {
1395       default:
1396         llvm_unreachable("Invalid MDNode subclass");
1397 #define HANDLE_MDNODE_LEAF(CLASS)                                              \
1398   case Metadata::CLASS##Kind:                                                  \
1399     Write##CLASS(cast<CLASS>(N), VE, Stream, Record, CLASS##Abbrev);           \
1400     continue;
1401 #include "llvm/IR/Metadata.def"
1402       }
1403     }
1404     if (const auto *MDC = dyn_cast<ConstantAsMetadata>(MD)) {
1405       WriteValueAsMetadata(MDC, VE, Stream, Record);
1406       continue;
1407     }
1408     const MDString *MDS = cast<MDString>(MD);
1409     // Code: [strchar x N]
1410     Record.append(MDS->bytes_begin(), MDS->bytes_end());
1411 
1412     // Emit the finished record.
1413     Stream.EmitRecord(bitc::METADATA_STRING, Record, MDSAbbrev);
1414     Record.clear();
1415   }
1416 
1417   writeNamedMetadata(M, VE, Stream, Record);
1418   Stream.ExitBlock();
1419 }
1420 
1421 static void WriteFunctionLocalMetadata(const Function &F,
1422                                        const ValueEnumerator &VE,
1423                                        BitstreamWriter &Stream) {
1424   bool StartedMetadataBlock = false;
1425   SmallVector<uint64_t, 64> Record;
1426   const SmallVectorImpl<const LocalAsMetadata *> &MDs =
1427       VE.getFunctionLocalMDs();
1428   for (unsigned i = 0, e = MDs.size(); i != e; ++i) {
1429     assert(MDs[i] && "Expected valid function-local metadata");
1430     if (!StartedMetadataBlock) {
1431       Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
1432       StartedMetadataBlock = true;
1433     }
1434     WriteValueAsMetadata(MDs[i], VE, Stream, Record);
1435   }
1436 
1437   if (StartedMetadataBlock)
1438     Stream.ExitBlock();
1439 }
1440 
1441 static void WriteMetadataAttachment(const Function &F,
1442                                     const ValueEnumerator &VE,
1443                                     BitstreamWriter &Stream) {
1444   Stream.EnterSubblock(bitc::METADATA_ATTACHMENT_ID, 3);
1445 
1446   SmallVector<uint64_t, 64> Record;
1447 
1448   // Write metadata attachments
1449   // METADATA_ATTACHMENT - [m x [value, [n x [id, mdnode]]]
1450   SmallVector<std::pair<unsigned, MDNode *>, 4> MDs;
1451   F.getAllMetadata(MDs);
1452   if (!MDs.empty()) {
1453     for (const auto &I : MDs) {
1454       Record.push_back(I.first);
1455       Record.push_back(VE.getMetadataID(I.second));
1456     }
1457     Stream.EmitRecord(bitc::METADATA_ATTACHMENT, Record, 0);
1458     Record.clear();
1459   }
1460 
1461   for (const BasicBlock &BB : F)
1462     for (const Instruction &I : BB) {
1463       MDs.clear();
1464       I.getAllMetadataOtherThanDebugLoc(MDs);
1465 
1466       // If no metadata, ignore instruction.
1467       if (MDs.empty()) continue;
1468 
1469       Record.push_back(VE.getInstructionID(&I));
1470 
1471       for (unsigned i = 0, e = MDs.size(); i != e; ++i) {
1472         Record.push_back(MDs[i].first);
1473         Record.push_back(VE.getMetadataID(MDs[i].second));
1474       }
1475       Stream.EmitRecord(bitc::METADATA_ATTACHMENT, Record, 0);
1476       Record.clear();
1477     }
1478 
1479   Stream.ExitBlock();
1480 }
1481 
1482 static void WriteModuleMetadataStore(const Module *M, BitstreamWriter &Stream) {
1483   SmallVector<uint64_t, 64> Record;
1484 
1485   // Write metadata kinds
1486   // METADATA_KIND - [n x [id, name]]
1487   SmallVector<StringRef, 8> Names;
1488   M->getMDKindNames(Names);
1489 
1490   if (Names.empty()) return;
1491 
1492   Stream.EnterSubblock(bitc::METADATA_KIND_BLOCK_ID, 3);
1493 
1494   for (unsigned MDKindID = 0, e = Names.size(); MDKindID != e; ++MDKindID) {
1495     Record.push_back(MDKindID);
1496     StringRef KName = Names[MDKindID];
1497     Record.append(KName.begin(), KName.end());
1498 
1499     Stream.EmitRecord(bitc::METADATA_KIND, Record, 0);
1500     Record.clear();
1501   }
1502 
1503   Stream.ExitBlock();
1504 }
1505 
1506 static void WriteOperandBundleTags(const Module *M, BitstreamWriter &Stream) {
1507   // Write metadata kinds
1508   //
1509   // OPERAND_BUNDLE_TAGS_BLOCK_ID : N x OPERAND_BUNDLE_TAG
1510   //
1511   // OPERAND_BUNDLE_TAG - [strchr x N]
1512 
1513   SmallVector<StringRef, 8> Tags;
1514   M->getOperandBundleTags(Tags);
1515 
1516   if (Tags.empty())
1517     return;
1518 
1519   Stream.EnterSubblock(bitc::OPERAND_BUNDLE_TAGS_BLOCK_ID, 3);
1520 
1521   SmallVector<uint64_t, 64> Record;
1522 
1523   for (auto Tag : Tags) {
1524     Record.append(Tag.begin(), Tag.end());
1525 
1526     Stream.EmitRecord(bitc::OPERAND_BUNDLE_TAG, Record, 0);
1527     Record.clear();
1528   }
1529 
1530   Stream.ExitBlock();
1531 }
1532 
1533 static void emitSignedInt64(SmallVectorImpl<uint64_t> &Vals, uint64_t V) {
1534   if ((int64_t)V >= 0)
1535     Vals.push_back(V << 1);
1536   else
1537     Vals.push_back((-V << 1) | 1);
1538 }
1539 
1540 static void WriteConstants(unsigned FirstVal, unsigned LastVal,
1541                            const ValueEnumerator &VE,
1542                            BitstreamWriter &Stream, bool isGlobal) {
1543   if (FirstVal == LastVal) return;
1544 
1545   Stream.EnterSubblock(bitc::CONSTANTS_BLOCK_ID, 4);
1546 
1547   unsigned AggregateAbbrev = 0;
1548   unsigned String8Abbrev = 0;
1549   unsigned CString7Abbrev = 0;
1550   unsigned CString6Abbrev = 0;
1551   // If this is a constant pool for the module, emit module-specific abbrevs.
1552   if (isGlobal) {
1553     // Abbrev for CST_CODE_AGGREGATE.
1554     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
1555     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_AGGREGATE));
1556     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1557     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, Log2_32_Ceil(LastVal+1)));
1558     AggregateAbbrev = Stream.EmitAbbrev(Abbv);
1559 
1560     // Abbrev for CST_CODE_STRING.
1561     Abbv = new BitCodeAbbrev();
1562     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_STRING));
1563     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1564     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
1565     String8Abbrev = Stream.EmitAbbrev(Abbv);
1566     // Abbrev for CST_CODE_CSTRING.
1567     Abbv = new BitCodeAbbrev();
1568     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
1569     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1570     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
1571     CString7Abbrev = Stream.EmitAbbrev(Abbv);
1572     // Abbrev for CST_CODE_CSTRING.
1573     Abbv = new BitCodeAbbrev();
1574     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CSTRING));
1575     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
1576     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
1577     CString6Abbrev = Stream.EmitAbbrev(Abbv);
1578   }
1579 
1580   SmallVector<uint64_t, 64> Record;
1581 
1582   const ValueEnumerator::ValueList &Vals = VE.getValues();
1583   Type *LastTy = nullptr;
1584   for (unsigned i = FirstVal; i != LastVal; ++i) {
1585     const Value *V = Vals[i].first;
1586     // If we need to switch types, do so now.
1587     if (V->getType() != LastTy) {
1588       LastTy = V->getType();
1589       Record.push_back(VE.getTypeID(LastTy));
1590       Stream.EmitRecord(bitc::CST_CODE_SETTYPE, Record,
1591                         CONSTANTS_SETTYPE_ABBREV);
1592       Record.clear();
1593     }
1594 
1595     if (const InlineAsm *IA = dyn_cast<InlineAsm>(V)) {
1596       Record.push_back(unsigned(IA->hasSideEffects()) |
1597                        unsigned(IA->isAlignStack()) << 1 |
1598                        unsigned(IA->getDialect()&1) << 2);
1599 
1600       // Add the asm string.
1601       const std::string &AsmStr = IA->getAsmString();
1602       Record.push_back(AsmStr.size());
1603       Record.append(AsmStr.begin(), AsmStr.end());
1604 
1605       // Add the constraint string.
1606       const std::string &ConstraintStr = IA->getConstraintString();
1607       Record.push_back(ConstraintStr.size());
1608       Record.append(ConstraintStr.begin(), ConstraintStr.end());
1609       Stream.EmitRecord(bitc::CST_CODE_INLINEASM, Record);
1610       Record.clear();
1611       continue;
1612     }
1613     const Constant *C = cast<Constant>(V);
1614     unsigned Code = -1U;
1615     unsigned AbbrevToUse = 0;
1616     if (C->isNullValue()) {
1617       Code = bitc::CST_CODE_NULL;
1618     } else if (isa<UndefValue>(C)) {
1619       Code = bitc::CST_CODE_UNDEF;
1620     } else if (const ConstantInt *IV = dyn_cast<ConstantInt>(C)) {
1621       if (IV->getBitWidth() <= 64) {
1622         uint64_t V = IV->getSExtValue();
1623         emitSignedInt64(Record, V);
1624         Code = bitc::CST_CODE_INTEGER;
1625         AbbrevToUse = CONSTANTS_INTEGER_ABBREV;
1626       } else {                             // Wide integers, > 64 bits in size.
1627         // We have an arbitrary precision integer value to write whose
1628         // bit width is > 64. However, in canonical unsigned integer
1629         // format it is likely that the high bits are going to be zero.
1630         // So, we only write the number of active words.
1631         unsigned NWords = IV->getValue().getActiveWords();
1632         const uint64_t *RawWords = IV->getValue().getRawData();
1633         for (unsigned i = 0; i != NWords; ++i) {
1634           emitSignedInt64(Record, RawWords[i]);
1635         }
1636         Code = bitc::CST_CODE_WIDE_INTEGER;
1637       }
1638     } else if (const ConstantFP *CFP = dyn_cast<ConstantFP>(C)) {
1639       Code = bitc::CST_CODE_FLOAT;
1640       Type *Ty = CFP->getType();
1641       if (Ty->isHalfTy() || Ty->isFloatTy() || Ty->isDoubleTy()) {
1642         Record.push_back(CFP->getValueAPF().bitcastToAPInt().getZExtValue());
1643       } else if (Ty->isX86_FP80Ty()) {
1644         // api needed to prevent premature destruction
1645         // bits are not in the same order as a normal i80 APInt, compensate.
1646         APInt api = CFP->getValueAPF().bitcastToAPInt();
1647         const uint64_t *p = api.getRawData();
1648         Record.push_back((p[1] << 48) | (p[0] >> 16));
1649         Record.push_back(p[0] & 0xffffLL);
1650       } else if (Ty->isFP128Ty() || Ty->isPPC_FP128Ty()) {
1651         APInt api = CFP->getValueAPF().bitcastToAPInt();
1652         const uint64_t *p = api.getRawData();
1653         Record.push_back(p[0]);
1654         Record.push_back(p[1]);
1655       } else {
1656         assert (0 && "Unknown FP type!");
1657       }
1658     } else if (isa<ConstantDataSequential>(C) &&
1659                cast<ConstantDataSequential>(C)->isString()) {
1660       const ConstantDataSequential *Str = cast<ConstantDataSequential>(C);
1661       // Emit constant strings specially.
1662       unsigned NumElts = Str->getNumElements();
1663       // If this is a null-terminated string, use the denser CSTRING encoding.
1664       if (Str->isCString()) {
1665         Code = bitc::CST_CODE_CSTRING;
1666         --NumElts;  // Don't encode the null, which isn't allowed by char6.
1667       } else {
1668         Code = bitc::CST_CODE_STRING;
1669         AbbrevToUse = String8Abbrev;
1670       }
1671       bool isCStr7 = Code == bitc::CST_CODE_CSTRING;
1672       bool isCStrChar6 = Code == bitc::CST_CODE_CSTRING;
1673       for (unsigned i = 0; i != NumElts; ++i) {
1674         unsigned char V = Str->getElementAsInteger(i);
1675         Record.push_back(V);
1676         isCStr7 &= (V & 128) == 0;
1677         if (isCStrChar6)
1678           isCStrChar6 = BitCodeAbbrevOp::isChar6(V);
1679       }
1680 
1681       if (isCStrChar6)
1682         AbbrevToUse = CString6Abbrev;
1683       else if (isCStr7)
1684         AbbrevToUse = CString7Abbrev;
1685     } else if (const ConstantDataSequential *CDS =
1686                   dyn_cast<ConstantDataSequential>(C)) {
1687       Code = bitc::CST_CODE_DATA;
1688       Type *EltTy = CDS->getType()->getElementType();
1689       if (isa<IntegerType>(EltTy)) {
1690         for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i)
1691           Record.push_back(CDS->getElementAsInteger(i));
1692       } else {
1693         for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i)
1694           Record.push_back(
1695               CDS->getElementAsAPFloat(i).bitcastToAPInt().getLimitedValue());
1696       }
1697     } else if (isa<ConstantArray>(C) || isa<ConstantStruct>(C) ||
1698                isa<ConstantVector>(C)) {
1699       Code = bitc::CST_CODE_AGGREGATE;
1700       for (const Value *Op : C->operands())
1701         Record.push_back(VE.getValueID(Op));
1702       AbbrevToUse = AggregateAbbrev;
1703     } else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
1704       switch (CE->getOpcode()) {
1705       default:
1706         if (Instruction::isCast(CE->getOpcode())) {
1707           Code = bitc::CST_CODE_CE_CAST;
1708           Record.push_back(GetEncodedCastOpcode(CE->getOpcode()));
1709           Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
1710           Record.push_back(VE.getValueID(C->getOperand(0)));
1711           AbbrevToUse = CONSTANTS_CE_CAST_Abbrev;
1712         } else {
1713           assert(CE->getNumOperands() == 2 && "Unknown constant expr!");
1714           Code = bitc::CST_CODE_CE_BINOP;
1715           Record.push_back(GetEncodedBinaryOpcode(CE->getOpcode()));
1716           Record.push_back(VE.getValueID(C->getOperand(0)));
1717           Record.push_back(VE.getValueID(C->getOperand(1)));
1718           uint64_t Flags = GetOptimizationFlags(CE);
1719           if (Flags != 0)
1720             Record.push_back(Flags);
1721         }
1722         break;
1723       case Instruction::GetElementPtr: {
1724         Code = bitc::CST_CODE_CE_GEP;
1725         const auto *GO = cast<GEPOperator>(C);
1726         if (GO->isInBounds())
1727           Code = bitc::CST_CODE_CE_INBOUNDS_GEP;
1728         Record.push_back(VE.getTypeID(GO->getSourceElementType()));
1729         for (unsigned i = 0, e = CE->getNumOperands(); i != e; ++i) {
1730           Record.push_back(VE.getTypeID(C->getOperand(i)->getType()));
1731           Record.push_back(VE.getValueID(C->getOperand(i)));
1732         }
1733         break;
1734       }
1735       case Instruction::Select:
1736         Code = bitc::CST_CODE_CE_SELECT;
1737         Record.push_back(VE.getValueID(C->getOperand(0)));
1738         Record.push_back(VE.getValueID(C->getOperand(1)));
1739         Record.push_back(VE.getValueID(C->getOperand(2)));
1740         break;
1741       case Instruction::ExtractElement:
1742         Code = bitc::CST_CODE_CE_EXTRACTELT;
1743         Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
1744         Record.push_back(VE.getValueID(C->getOperand(0)));
1745         Record.push_back(VE.getTypeID(C->getOperand(1)->getType()));
1746         Record.push_back(VE.getValueID(C->getOperand(1)));
1747         break;
1748       case Instruction::InsertElement:
1749         Code = bitc::CST_CODE_CE_INSERTELT;
1750         Record.push_back(VE.getValueID(C->getOperand(0)));
1751         Record.push_back(VE.getValueID(C->getOperand(1)));
1752         Record.push_back(VE.getTypeID(C->getOperand(2)->getType()));
1753         Record.push_back(VE.getValueID(C->getOperand(2)));
1754         break;
1755       case Instruction::ShuffleVector:
1756         // If the return type and argument types are the same, this is a
1757         // standard shufflevector instruction.  If the types are different,
1758         // then the shuffle is widening or truncating the input vectors, and
1759         // the argument type must also be encoded.
1760         if (C->getType() == C->getOperand(0)->getType()) {
1761           Code = bitc::CST_CODE_CE_SHUFFLEVEC;
1762         } else {
1763           Code = bitc::CST_CODE_CE_SHUFVEC_EX;
1764           Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
1765         }
1766         Record.push_back(VE.getValueID(C->getOperand(0)));
1767         Record.push_back(VE.getValueID(C->getOperand(1)));
1768         Record.push_back(VE.getValueID(C->getOperand(2)));
1769         break;
1770       case Instruction::ICmp:
1771       case Instruction::FCmp:
1772         Code = bitc::CST_CODE_CE_CMP;
1773         Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
1774         Record.push_back(VE.getValueID(C->getOperand(0)));
1775         Record.push_back(VE.getValueID(C->getOperand(1)));
1776         Record.push_back(CE->getPredicate());
1777         break;
1778       }
1779     } else if (const BlockAddress *BA = dyn_cast<BlockAddress>(C)) {
1780       Code = bitc::CST_CODE_BLOCKADDRESS;
1781       Record.push_back(VE.getTypeID(BA->getFunction()->getType()));
1782       Record.push_back(VE.getValueID(BA->getFunction()));
1783       Record.push_back(VE.getGlobalBasicBlockID(BA->getBasicBlock()));
1784     } else {
1785 #ifndef NDEBUG
1786       C->dump();
1787 #endif
1788       llvm_unreachable("Unknown constant!");
1789     }
1790     Stream.EmitRecord(Code, Record, AbbrevToUse);
1791     Record.clear();
1792   }
1793 
1794   Stream.ExitBlock();
1795 }
1796 
1797 static void WriteModuleConstants(const ValueEnumerator &VE,
1798                                  BitstreamWriter &Stream) {
1799   const ValueEnumerator::ValueList &Vals = VE.getValues();
1800 
1801   // Find the first constant to emit, which is the first non-globalvalue value.
1802   // We know globalvalues have been emitted by WriteModuleInfo.
1803   for (unsigned i = 0, e = Vals.size(); i != e; ++i) {
1804     if (!isa<GlobalValue>(Vals[i].first)) {
1805       WriteConstants(i, Vals.size(), VE, Stream, true);
1806       return;
1807     }
1808   }
1809 }
1810 
1811 /// PushValueAndType - The file has to encode both the value and type id for
1812 /// many values, because we need to know what type to create for forward
1813 /// references.  However, most operands are not forward references, so this type
1814 /// field is not needed.
1815 ///
1816 /// This function adds V's value ID to Vals.  If the value ID is higher than the
1817 /// instruction ID, then it is a forward reference, and it also includes the
1818 /// type ID.  The value ID that is written is encoded relative to the InstID.
1819 static bool PushValueAndType(const Value *V, unsigned InstID,
1820                              SmallVectorImpl<unsigned> &Vals,
1821                              ValueEnumerator &VE) {
1822   unsigned ValID = VE.getValueID(V);
1823   // Make encoding relative to the InstID.
1824   Vals.push_back(InstID - ValID);
1825   if (ValID >= InstID) {
1826     Vals.push_back(VE.getTypeID(V->getType()));
1827     return true;
1828   }
1829   return false;
1830 }
1831 
1832 static void WriteOperandBundles(BitstreamWriter &Stream, ImmutableCallSite CS,
1833                                 unsigned InstID, ValueEnumerator &VE) {
1834   SmallVector<unsigned, 64> Record;
1835   LLVMContext &C = CS.getInstruction()->getContext();
1836 
1837   for (unsigned i = 0, e = CS.getNumOperandBundles(); i != e; ++i) {
1838     const auto &Bundle = CS.getOperandBundleAt(i);
1839     Record.push_back(C.getOperandBundleTagID(Bundle.getTagName()));
1840 
1841     for (auto &Input : Bundle.Inputs)
1842       PushValueAndType(Input, InstID, Record, VE);
1843 
1844     Stream.EmitRecord(bitc::FUNC_CODE_OPERAND_BUNDLE, Record);
1845     Record.clear();
1846   }
1847 }
1848 
1849 /// pushValue - Like PushValueAndType, but where the type of the value is
1850 /// omitted (perhaps it was already encoded in an earlier operand).
1851 static void pushValue(const Value *V, unsigned InstID,
1852                       SmallVectorImpl<unsigned> &Vals,
1853                       ValueEnumerator &VE) {
1854   unsigned ValID = VE.getValueID(V);
1855   Vals.push_back(InstID - ValID);
1856 }
1857 
1858 static void pushValueSigned(const Value *V, unsigned InstID,
1859                             SmallVectorImpl<uint64_t> &Vals,
1860                             ValueEnumerator &VE) {
1861   unsigned ValID = VE.getValueID(V);
1862   int64_t diff = ((int32_t)InstID - (int32_t)ValID);
1863   emitSignedInt64(Vals, diff);
1864 }
1865 
1866 /// WriteInstruction - Emit an instruction to the specified stream.
1867 static void WriteInstruction(const Instruction &I, unsigned InstID,
1868                              ValueEnumerator &VE, BitstreamWriter &Stream,
1869                              SmallVectorImpl<unsigned> &Vals) {
1870   unsigned Code = 0;
1871   unsigned AbbrevToUse = 0;
1872   VE.setInstructionID(&I);
1873   switch (I.getOpcode()) {
1874   default:
1875     if (Instruction::isCast(I.getOpcode())) {
1876       Code = bitc::FUNC_CODE_INST_CAST;
1877       if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
1878         AbbrevToUse = FUNCTION_INST_CAST_ABBREV;
1879       Vals.push_back(VE.getTypeID(I.getType()));
1880       Vals.push_back(GetEncodedCastOpcode(I.getOpcode()));
1881     } else {
1882       assert(isa<BinaryOperator>(I) && "Unknown instruction!");
1883       Code = bitc::FUNC_CODE_INST_BINOP;
1884       if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
1885         AbbrevToUse = FUNCTION_INST_BINOP_ABBREV;
1886       pushValue(I.getOperand(1), InstID, Vals, VE);
1887       Vals.push_back(GetEncodedBinaryOpcode(I.getOpcode()));
1888       uint64_t Flags = GetOptimizationFlags(&I);
1889       if (Flags != 0) {
1890         if (AbbrevToUse == FUNCTION_INST_BINOP_ABBREV)
1891           AbbrevToUse = FUNCTION_INST_BINOP_FLAGS_ABBREV;
1892         Vals.push_back(Flags);
1893       }
1894     }
1895     break;
1896 
1897   case Instruction::GetElementPtr: {
1898     Code = bitc::FUNC_CODE_INST_GEP;
1899     AbbrevToUse = FUNCTION_INST_GEP_ABBREV;
1900     auto &GEPInst = cast<GetElementPtrInst>(I);
1901     Vals.push_back(GEPInst.isInBounds());
1902     Vals.push_back(VE.getTypeID(GEPInst.getSourceElementType()));
1903     for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
1904       PushValueAndType(I.getOperand(i), InstID, Vals, VE);
1905     break;
1906   }
1907   case Instruction::ExtractValue: {
1908     Code = bitc::FUNC_CODE_INST_EXTRACTVAL;
1909     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1910     const ExtractValueInst *EVI = cast<ExtractValueInst>(&I);
1911     Vals.append(EVI->idx_begin(), EVI->idx_end());
1912     break;
1913   }
1914   case Instruction::InsertValue: {
1915     Code = bitc::FUNC_CODE_INST_INSERTVAL;
1916     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1917     PushValueAndType(I.getOperand(1), InstID, Vals, VE);
1918     const InsertValueInst *IVI = cast<InsertValueInst>(&I);
1919     Vals.append(IVI->idx_begin(), IVI->idx_end());
1920     break;
1921   }
1922   case Instruction::Select:
1923     Code = bitc::FUNC_CODE_INST_VSELECT;
1924     PushValueAndType(I.getOperand(1), InstID, Vals, VE);
1925     pushValue(I.getOperand(2), InstID, Vals, VE);
1926     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1927     break;
1928   case Instruction::ExtractElement:
1929     Code = bitc::FUNC_CODE_INST_EXTRACTELT;
1930     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1931     PushValueAndType(I.getOperand(1), InstID, Vals, VE);
1932     break;
1933   case Instruction::InsertElement:
1934     Code = bitc::FUNC_CODE_INST_INSERTELT;
1935     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1936     pushValue(I.getOperand(1), InstID, Vals, VE);
1937     PushValueAndType(I.getOperand(2), InstID, Vals, VE);
1938     break;
1939   case Instruction::ShuffleVector:
1940     Code = bitc::FUNC_CODE_INST_SHUFFLEVEC;
1941     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1942     pushValue(I.getOperand(1), InstID, Vals, VE);
1943     pushValue(I.getOperand(2), InstID, Vals, VE);
1944     break;
1945   case Instruction::ICmp:
1946   case Instruction::FCmp: {
1947     // compare returning Int1Ty or vector of Int1Ty
1948     Code = bitc::FUNC_CODE_INST_CMP2;
1949     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
1950     pushValue(I.getOperand(1), InstID, Vals, VE);
1951     Vals.push_back(cast<CmpInst>(I).getPredicate());
1952     uint64_t Flags = GetOptimizationFlags(&I);
1953     if (Flags != 0)
1954       Vals.push_back(Flags);
1955     break;
1956   }
1957 
1958   case Instruction::Ret:
1959     {
1960       Code = bitc::FUNC_CODE_INST_RET;
1961       unsigned NumOperands = I.getNumOperands();
1962       if (NumOperands == 0)
1963         AbbrevToUse = FUNCTION_INST_RET_VOID_ABBREV;
1964       else if (NumOperands == 1) {
1965         if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))
1966           AbbrevToUse = FUNCTION_INST_RET_VAL_ABBREV;
1967       } else {
1968         for (unsigned i = 0, e = NumOperands; i != e; ++i)
1969           PushValueAndType(I.getOperand(i), InstID, Vals, VE);
1970       }
1971     }
1972     break;
1973   case Instruction::Br:
1974     {
1975       Code = bitc::FUNC_CODE_INST_BR;
1976       const BranchInst &II = cast<BranchInst>(I);
1977       Vals.push_back(VE.getValueID(II.getSuccessor(0)));
1978       if (II.isConditional()) {
1979         Vals.push_back(VE.getValueID(II.getSuccessor(1)));
1980         pushValue(II.getCondition(), InstID, Vals, VE);
1981       }
1982     }
1983     break;
1984   case Instruction::Switch:
1985     {
1986       Code = bitc::FUNC_CODE_INST_SWITCH;
1987       const SwitchInst &SI = cast<SwitchInst>(I);
1988       Vals.push_back(VE.getTypeID(SI.getCondition()->getType()));
1989       pushValue(SI.getCondition(), InstID, Vals, VE);
1990       Vals.push_back(VE.getValueID(SI.getDefaultDest()));
1991       for (SwitchInst::ConstCaseIt Case : SI.cases()) {
1992         Vals.push_back(VE.getValueID(Case.getCaseValue()));
1993         Vals.push_back(VE.getValueID(Case.getCaseSuccessor()));
1994       }
1995     }
1996     break;
1997   case Instruction::IndirectBr:
1998     Code = bitc::FUNC_CODE_INST_INDIRECTBR;
1999     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));
2000     // Encode the address operand as relative, but not the basic blocks.
2001     pushValue(I.getOperand(0), InstID, Vals, VE);
2002     for (unsigned i = 1, e = I.getNumOperands(); i != e; ++i)
2003       Vals.push_back(VE.getValueID(I.getOperand(i)));
2004     break;
2005 
2006   case Instruction::Invoke: {
2007     const InvokeInst *II = cast<InvokeInst>(&I);
2008     const Value *Callee = II->getCalledValue();
2009     FunctionType *FTy = II->getFunctionType();
2010 
2011     if (II->hasOperandBundles())
2012       WriteOperandBundles(Stream, II, InstID, VE);
2013 
2014     Code = bitc::FUNC_CODE_INST_INVOKE;
2015 
2016     Vals.push_back(VE.getAttributeID(II->getAttributes()));
2017     Vals.push_back(II->getCallingConv() | 1 << 13);
2018     Vals.push_back(VE.getValueID(II->getNormalDest()));
2019     Vals.push_back(VE.getValueID(II->getUnwindDest()));
2020     Vals.push_back(VE.getTypeID(FTy));
2021     PushValueAndType(Callee, InstID, Vals, VE);
2022 
2023     // Emit value #'s for the fixed parameters.
2024     for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i)
2025       pushValue(I.getOperand(i), InstID, Vals, VE);  // fixed param.
2026 
2027     // Emit type/value pairs for varargs params.
2028     if (FTy->isVarArg()) {
2029       for (unsigned i = FTy->getNumParams(), e = I.getNumOperands()-3;
2030            i != e; ++i)
2031         PushValueAndType(I.getOperand(i), InstID, Vals, VE); // vararg
2032     }
2033     break;
2034   }
2035   case Instruction::Resume:
2036     Code = bitc::FUNC_CODE_INST_RESUME;
2037     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
2038     break;
2039   case Instruction::CleanupRet: {
2040     Code = bitc::FUNC_CODE_INST_CLEANUPRET;
2041     const auto &CRI = cast<CleanupReturnInst>(I);
2042     pushValue(CRI.getCleanupPad(), InstID, Vals, VE);
2043     if (CRI.hasUnwindDest())
2044       Vals.push_back(VE.getValueID(CRI.getUnwindDest()));
2045     break;
2046   }
2047   case Instruction::CatchRet: {
2048     Code = bitc::FUNC_CODE_INST_CATCHRET;
2049     const auto &CRI = cast<CatchReturnInst>(I);
2050     pushValue(CRI.getCatchPad(), InstID, Vals, VE);
2051     Vals.push_back(VE.getValueID(CRI.getSuccessor()));
2052     break;
2053   }
2054   case Instruction::CleanupPad:
2055   case Instruction::CatchPad: {
2056     const auto &FuncletPad = cast<FuncletPadInst>(I);
2057     Code = isa<CatchPadInst>(FuncletPad) ? bitc::FUNC_CODE_INST_CATCHPAD
2058                                          : bitc::FUNC_CODE_INST_CLEANUPPAD;
2059     pushValue(FuncletPad.getParentPad(), InstID, Vals, VE);
2060 
2061     unsigned NumArgOperands = FuncletPad.getNumArgOperands();
2062     Vals.push_back(NumArgOperands);
2063     for (unsigned Op = 0; Op != NumArgOperands; ++Op)
2064       PushValueAndType(FuncletPad.getArgOperand(Op), InstID, Vals, VE);
2065     break;
2066   }
2067   case Instruction::CatchSwitch: {
2068     Code = bitc::FUNC_CODE_INST_CATCHSWITCH;
2069     const auto &CatchSwitch = cast<CatchSwitchInst>(I);
2070 
2071     pushValue(CatchSwitch.getParentPad(), InstID, Vals, VE);
2072 
2073     unsigned NumHandlers = CatchSwitch.getNumHandlers();
2074     Vals.push_back(NumHandlers);
2075     for (const BasicBlock *CatchPadBB : CatchSwitch.handlers())
2076       Vals.push_back(VE.getValueID(CatchPadBB));
2077 
2078     if (CatchSwitch.hasUnwindDest())
2079       Vals.push_back(VE.getValueID(CatchSwitch.getUnwindDest()));
2080     break;
2081   }
2082   case Instruction::Unreachable:
2083     Code = bitc::FUNC_CODE_INST_UNREACHABLE;
2084     AbbrevToUse = FUNCTION_INST_UNREACHABLE_ABBREV;
2085     break;
2086 
2087   case Instruction::PHI: {
2088     const PHINode &PN = cast<PHINode>(I);
2089     Code = bitc::FUNC_CODE_INST_PHI;
2090     // With the newer instruction encoding, forward references could give
2091     // negative valued IDs.  This is most common for PHIs, so we use
2092     // signed VBRs.
2093     SmallVector<uint64_t, 128> Vals64;
2094     Vals64.push_back(VE.getTypeID(PN.getType()));
2095     for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) {
2096       pushValueSigned(PN.getIncomingValue(i), InstID, Vals64, VE);
2097       Vals64.push_back(VE.getValueID(PN.getIncomingBlock(i)));
2098     }
2099     // Emit a Vals64 vector and exit.
2100     Stream.EmitRecord(Code, Vals64, AbbrevToUse);
2101     Vals64.clear();
2102     return;
2103   }
2104 
2105   case Instruction::LandingPad: {
2106     const LandingPadInst &LP = cast<LandingPadInst>(I);
2107     Code = bitc::FUNC_CODE_INST_LANDINGPAD;
2108     Vals.push_back(VE.getTypeID(LP.getType()));
2109     Vals.push_back(LP.isCleanup());
2110     Vals.push_back(LP.getNumClauses());
2111     for (unsigned I = 0, E = LP.getNumClauses(); I != E; ++I) {
2112       if (LP.isCatch(I))
2113         Vals.push_back(LandingPadInst::Catch);
2114       else
2115         Vals.push_back(LandingPadInst::Filter);
2116       PushValueAndType(LP.getClause(I), InstID, Vals, VE);
2117     }
2118     break;
2119   }
2120 
2121   case Instruction::Alloca: {
2122     Code = bitc::FUNC_CODE_INST_ALLOCA;
2123     const AllocaInst &AI = cast<AllocaInst>(I);
2124     Vals.push_back(VE.getTypeID(AI.getAllocatedType()));
2125     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));
2126     Vals.push_back(VE.getValueID(I.getOperand(0))); // size.
2127     unsigned AlignRecord = Log2_32(AI.getAlignment()) + 1;
2128     assert(Log2_32(Value::MaximumAlignment) + 1 < 1 << 5 &&
2129            "not enough bits for maximum alignment");
2130     assert(AlignRecord < 1 << 5 && "alignment greater than 1 << 64");
2131     AlignRecord |= AI.isUsedWithInAlloca() << 5;
2132     AlignRecord |= 1 << 6;
2133     // Reserve bit 7 for SwiftError flag.
2134     // AlignRecord |= AI.isSwiftError() << 7;
2135     Vals.push_back(AlignRecord);
2136     break;
2137   }
2138 
2139   case Instruction::Load:
2140     if (cast<LoadInst>(I).isAtomic()) {
2141       Code = bitc::FUNC_CODE_INST_LOADATOMIC;
2142       PushValueAndType(I.getOperand(0), InstID, Vals, VE);
2143     } else {
2144       Code = bitc::FUNC_CODE_INST_LOAD;
2145       if (!PushValueAndType(I.getOperand(0), InstID, Vals, VE))  // ptr
2146         AbbrevToUse = FUNCTION_INST_LOAD_ABBREV;
2147     }
2148     Vals.push_back(VE.getTypeID(I.getType()));
2149     Vals.push_back(Log2_32(cast<LoadInst>(I).getAlignment())+1);
2150     Vals.push_back(cast<LoadInst>(I).isVolatile());
2151     if (cast<LoadInst>(I).isAtomic()) {
2152       Vals.push_back(GetEncodedOrdering(cast<LoadInst>(I).getOrdering()));
2153       Vals.push_back(GetEncodedSynchScope(cast<LoadInst>(I).getSynchScope()));
2154     }
2155     break;
2156   case Instruction::Store:
2157     if (cast<StoreInst>(I).isAtomic())
2158       Code = bitc::FUNC_CODE_INST_STOREATOMIC;
2159     else
2160       Code = bitc::FUNC_CODE_INST_STORE;
2161     PushValueAndType(I.getOperand(1), InstID, Vals, VE);  // ptrty + ptr
2162     PushValueAndType(I.getOperand(0), InstID, Vals, VE);  // valty + val
2163     Vals.push_back(Log2_32(cast<StoreInst>(I).getAlignment())+1);
2164     Vals.push_back(cast<StoreInst>(I).isVolatile());
2165     if (cast<StoreInst>(I).isAtomic()) {
2166       Vals.push_back(GetEncodedOrdering(cast<StoreInst>(I).getOrdering()));
2167       Vals.push_back(GetEncodedSynchScope(cast<StoreInst>(I).getSynchScope()));
2168     }
2169     break;
2170   case Instruction::AtomicCmpXchg:
2171     Code = bitc::FUNC_CODE_INST_CMPXCHG;
2172     PushValueAndType(I.getOperand(0), InstID, Vals, VE);  // ptrty + ptr
2173     PushValueAndType(I.getOperand(1), InstID, Vals, VE);  // cmp.
2174     pushValue(I.getOperand(2), InstID, Vals, VE);         // newval.
2175     Vals.push_back(cast<AtomicCmpXchgInst>(I).isVolatile());
2176     Vals.push_back(GetEncodedOrdering(
2177                      cast<AtomicCmpXchgInst>(I).getSuccessOrdering()));
2178     Vals.push_back(GetEncodedSynchScope(
2179                      cast<AtomicCmpXchgInst>(I).getSynchScope()));
2180     Vals.push_back(GetEncodedOrdering(
2181                      cast<AtomicCmpXchgInst>(I).getFailureOrdering()));
2182     Vals.push_back(cast<AtomicCmpXchgInst>(I).isWeak());
2183     break;
2184   case Instruction::AtomicRMW:
2185     Code = bitc::FUNC_CODE_INST_ATOMICRMW;
2186     PushValueAndType(I.getOperand(0), InstID, Vals, VE);  // ptrty + ptr
2187     pushValue(I.getOperand(1), InstID, Vals, VE);         // val.
2188     Vals.push_back(GetEncodedRMWOperation(
2189                      cast<AtomicRMWInst>(I).getOperation()));
2190     Vals.push_back(cast<AtomicRMWInst>(I).isVolatile());
2191     Vals.push_back(GetEncodedOrdering(cast<AtomicRMWInst>(I).getOrdering()));
2192     Vals.push_back(GetEncodedSynchScope(
2193                      cast<AtomicRMWInst>(I).getSynchScope()));
2194     break;
2195   case Instruction::Fence:
2196     Code = bitc::FUNC_CODE_INST_FENCE;
2197     Vals.push_back(GetEncodedOrdering(cast<FenceInst>(I).getOrdering()));
2198     Vals.push_back(GetEncodedSynchScope(cast<FenceInst>(I).getSynchScope()));
2199     break;
2200   case Instruction::Call: {
2201     const CallInst &CI = cast<CallInst>(I);
2202     FunctionType *FTy = CI.getFunctionType();
2203 
2204     if (CI.hasOperandBundles())
2205       WriteOperandBundles(Stream, &CI, InstID, VE);
2206 
2207     Code = bitc::FUNC_CODE_INST_CALL;
2208 
2209     Vals.push_back(VE.getAttributeID(CI.getAttributes()));
2210 
2211     unsigned Flags = GetOptimizationFlags(&I);
2212     Vals.push_back(CI.getCallingConv() << bitc::CALL_CCONV |
2213                    unsigned(CI.isTailCall()) << bitc::CALL_TAIL |
2214                    unsigned(CI.isMustTailCall()) << bitc::CALL_MUSTTAIL |
2215                    1 << bitc::CALL_EXPLICIT_TYPE |
2216                    unsigned(CI.isNoTailCall()) << bitc::CALL_NOTAIL |
2217                    unsigned(Flags != 0) << bitc::CALL_FMF);
2218     if (Flags != 0)
2219       Vals.push_back(Flags);
2220 
2221     Vals.push_back(VE.getTypeID(FTy));
2222     PushValueAndType(CI.getCalledValue(), InstID, Vals, VE);  // Callee
2223 
2224     // Emit value #'s for the fixed parameters.
2225     for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i) {
2226       // Check for labels (can happen with asm labels).
2227       if (FTy->getParamType(i)->isLabelTy())
2228         Vals.push_back(VE.getValueID(CI.getArgOperand(i)));
2229       else
2230         pushValue(CI.getArgOperand(i), InstID, Vals, VE);  // fixed param.
2231     }
2232 
2233     // Emit type/value pairs for varargs params.
2234     if (FTy->isVarArg()) {
2235       for (unsigned i = FTy->getNumParams(), e = CI.getNumArgOperands();
2236            i != e; ++i)
2237         PushValueAndType(CI.getArgOperand(i), InstID, Vals, VE);  // varargs
2238     }
2239     break;
2240   }
2241   case Instruction::VAArg:
2242     Code = bitc::FUNC_CODE_INST_VAARG;
2243     Vals.push_back(VE.getTypeID(I.getOperand(0)->getType()));   // valistty
2244     pushValue(I.getOperand(0), InstID, Vals, VE); // valist.
2245     Vals.push_back(VE.getTypeID(I.getType())); // restype.
2246     break;
2247   }
2248 
2249   Stream.EmitRecord(Code, Vals, AbbrevToUse);
2250   Vals.clear();
2251 }
2252 
2253 /// Emit names for globals/functions etc. The VSTOffsetPlaceholder,
2254 /// BitcodeStartBit and ModuleSummaryIndex are only passed for the module-level
2255 /// VST, where we are including a function bitcode index and need to
2256 /// backpatch the VST forward declaration record.
2257 static void WriteValueSymbolTable(
2258     const ValueSymbolTable &VST, const ValueEnumerator &VE,
2259     BitstreamWriter &Stream, uint64_t VSTOffsetPlaceholder = 0,
2260     uint64_t BitcodeStartBit = 0,
2261     DenseMap<const Function *, std::unique_ptr<GlobalValueInfo>>
2262         *FunctionIndex = nullptr) {
2263   if (VST.empty()) {
2264     // WriteValueSymbolTableForwardDecl should have returned early as
2265     // well. Ensure this handling remains in sync by asserting that
2266     // the placeholder offset is not set.
2267     assert(VSTOffsetPlaceholder == 0);
2268     return;
2269   }
2270 
2271   if (VSTOffsetPlaceholder > 0) {
2272     // Get the offset of the VST we are writing, and backpatch it into
2273     // the VST forward declaration record.
2274     uint64_t VSTOffset = Stream.GetCurrentBitNo();
2275     // The BitcodeStartBit was the stream offset of the actual bitcode
2276     // (e.g. excluding any initial darwin header).
2277     VSTOffset -= BitcodeStartBit;
2278     assert((VSTOffset & 31) == 0 && "VST block not 32-bit aligned");
2279     Stream.BackpatchWord(VSTOffsetPlaceholder, VSTOffset / 32);
2280   }
2281 
2282   Stream.EnterSubblock(bitc::VALUE_SYMTAB_BLOCK_ID, 4);
2283 
2284   // For the module-level VST, add abbrev Ids for the VST_CODE_FNENTRY
2285   // records, which are not used in the per-function VSTs.
2286   unsigned FnEntry8BitAbbrev;
2287   unsigned FnEntry7BitAbbrev;
2288   unsigned FnEntry6BitAbbrev;
2289   if (VSTOffsetPlaceholder > 0) {
2290     // 8-bit fixed-width VST_CODE_FNENTRY function strings.
2291     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2292     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_FNENTRY));
2293     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // value id
2294     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // funcoffset
2295     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2296     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
2297     FnEntry8BitAbbrev = Stream.EmitAbbrev(Abbv);
2298 
2299     // 7-bit fixed width VST_CODE_FNENTRY function strings.
2300     Abbv = new BitCodeAbbrev();
2301     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_FNENTRY));
2302     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // value id
2303     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // funcoffset
2304     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2305     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
2306     FnEntry7BitAbbrev = Stream.EmitAbbrev(Abbv);
2307 
2308     // 6-bit char6 VST_CODE_FNENTRY function strings.
2309     Abbv = new BitCodeAbbrev();
2310     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_FNENTRY));
2311     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // value id
2312     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // funcoffset
2313     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2314     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
2315     FnEntry6BitAbbrev = Stream.EmitAbbrev(Abbv);
2316   }
2317 
2318   // FIXME: Set up the abbrev, we know how many values there are!
2319   // FIXME: We know if the type names can use 7-bit ascii.
2320   SmallVector<unsigned, 64> NameVals;
2321 
2322   for (const ValueName &Name : VST) {
2323     // Figure out the encoding to use for the name.
2324     StringEncoding Bits =
2325         getStringEncoding(Name.getKeyData(), Name.getKeyLength());
2326 
2327     unsigned AbbrevToUse = VST_ENTRY_8_ABBREV;
2328     NameVals.push_back(VE.getValueID(Name.getValue()));
2329 
2330     Function *F = dyn_cast<Function>(Name.getValue());
2331     if (!F) {
2332       // If value is an alias, need to get the aliased base object to
2333       // see if it is a function.
2334       auto *GA = dyn_cast<GlobalAlias>(Name.getValue());
2335       if (GA && GA->getBaseObject())
2336         F = dyn_cast<Function>(GA->getBaseObject());
2337     }
2338 
2339     // VST_CODE_ENTRY:   [valueid, namechar x N]
2340     // VST_CODE_FNENTRY: [valueid, funcoffset, namechar x N]
2341     // VST_CODE_BBENTRY: [bbid, namechar x N]
2342     unsigned Code;
2343     if (isa<BasicBlock>(Name.getValue())) {
2344       Code = bitc::VST_CODE_BBENTRY;
2345       if (Bits == SE_Char6)
2346         AbbrevToUse = VST_BBENTRY_6_ABBREV;
2347     } else if (F && !F->isDeclaration()) {
2348       // Must be the module-level VST, where we pass in the Index and
2349       // have a VSTOffsetPlaceholder. The function-level VST should not
2350       // contain any Function symbols.
2351       assert(FunctionIndex);
2352       assert(VSTOffsetPlaceholder > 0);
2353 
2354       // Save the word offset of the function (from the start of the
2355       // actual bitcode written to the stream).
2356       uint64_t BitcodeIndex =
2357           (*FunctionIndex)[F]->bitcodeIndex() - BitcodeStartBit;
2358       assert((BitcodeIndex & 31) == 0 && "function block not 32-bit aligned");
2359       NameVals.push_back(BitcodeIndex / 32);
2360 
2361       Code = bitc::VST_CODE_FNENTRY;
2362       AbbrevToUse = FnEntry8BitAbbrev;
2363       if (Bits == SE_Char6)
2364         AbbrevToUse = FnEntry6BitAbbrev;
2365       else if (Bits == SE_Fixed7)
2366         AbbrevToUse = FnEntry7BitAbbrev;
2367     } else {
2368       Code = bitc::VST_CODE_ENTRY;
2369       if (Bits == SE_Char6)
2370         AbbrevToUse = VST_ENTRY_6_ABBREV;
2371       else if (Bits == SE_Fixed7)
2372         AbbrevToUse = VST_ENTRY_7_ABBREV;
2373     }
2374 
2375     for (const auto P : Name.getKey())
2376       NameVals.push_back((unsigned char)P);
2377 
2378     // Emit the finished record.
2379     Stream.EmitRecord(Code, NameVals, AbbrevToUse);
2380     NameVals.clear();
2381   }
2382   Stream.ExitBlock();
2383 }
2384 
2385 /// Emit function names and summary offsets for the combined index
2386 /// used by ThinLTO.
2387 static void
2388 WriteCombinedValueSymbolTable(const ModuleSummaryIndex &Index,
2389                               BitstreamWriter &Stream,
2390                               std::map<uint64_t, unsigned> &GUIDToValueIdMap,
2391                               uint64_t VSTOffsetPlaceholder) {
2392   assert(VSTOffsetPlaceholder > 0 && "Expected non-zero VSTOffsetPlaceholder");
2393   // Get the offset of the VST we are writing, and backpatch it into
2394   // the VST forward declaration record.
2395   uint64_t VSTOffset = Stream.GetCurrentBitNo();
2396   assert((VSTOffset & 31) == 0 && "VST block not 32-bit aligned");
2397   Stream.BackpatchWord(VSTOffsetPlaceholder, VSTOffset / 32);
2398 
2399   Stream.EnterSubblock(bitc::VALUE_SYMTAB_BLOCK_ID, 4);
2400 
2401   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2402   Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_COMBINED_GVDEFENTRY));
2403   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // valueid
2404   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // sumoffset
2405   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // guid
2406   unsigned DefEntryAbbrev = Stream.EmitAbbrev(Abbv);
2407 
2408   Abbv = new BitCodeAbbrev();
2409   Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_COMBINED_ENTRY));
2410   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // valueid
2411   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // refguid
2412   unsigned EntryAbbrev = Stream.EmitAbbrev(Abbv);
2413 
2414   SmallVector<uint64_t, 64> NameVals;
2415 
2416   for (const auto &FII : Index) {
2417     uint64_t FuncGUID = FII.first;
2418     const auto &VMI = GUIDToValueIdMap.find(FuncGUID);
2419     assert(VMI != GUIDToValueIdMap.end());
2420 
2421     for (const auto &FI : FII.second) {
2422       // VST_CODE_COMBINED_GVDEFENTRY: [valueid, sumoffset, guid]
2423       NameVals.push_back(VMI->second);
2424       NameVals.push_back(FI->bitcodeIndex());
2425       NameVals.push_back(FuncGUID);
2426 
2427       // Emit the finished record.
2428       Stream.EmitRecord(bitc::VST_CODE_COMBINED_GVDEFENTRY, NameVals,
2429                         DefEntryAbbrev);
2430       NameVals.clear();
2431     }
2432     GUIDToValueIdMap.erase(VMI);
2433   }
2434   for (const auto &GVI : GUIDToValueIdMap) {
2435     // VST_CODE_COMBINED_ENTRY: [valueid, refguid]
2436     NameVals.push_back(GVI.second);
2437     NameVals.push_back(GVI.first);
2438 
2439     // Emit the finished record.
2440     Stream.EmitRecord(bitc::VST_CODE_COMBINED_ENTRY, NameVals, EntryAbbrev);
2441     NameVals.clear();
2442   }
2443   Stream.ExitBlock();
2444 }
2445 
2446 static void WriteUseList(ValueEnumerator &VE, UseListOrder &&Order,
2447                          BitstreamWriter &Stream) {
2448   assert(Order.Shuffle.size() >= 2 && "Shuffle too small");
2449   unsigned Code;
2450   if (isa<BasicBlock>(Order.V))
2451     Code = bitc::USELIST_CODE_BB;
2452   else
2453     Code = bitc::USELIST_CODE_DEFAULT;
2454 
2455   SmallVector<uint64_t, 64> Record(Order.Shuffle.begin(), Order.Shuffle.end());
2456   Record.push_back(VE.getValueID(Order.V));
2457   Stream.EmitRecord(Code, Record);
2458 }
2459 
2460 static void WriteUseListBlock(const Function *F, ValueEnumerator &VE,
2461                               BitstreamWriter &Stream) {
2462   assert(VE.shouldPreserveUseListOrder() &&
2463          "Expected to be preserving use-list order");
2464 
2465   auto hasMore = [&]() {
2466     return !VE.UseListOrders.empty() && VE.UseListOrders.back().F == F;
2467   };
2468   if (!hasMore())
2469     // Nothing to do.
2470     return;
2471 
2472   Stream.EnterSubblock(bitc::USELIST_BLOCK_ID, 3);
2473   while (hasMore()) {
2474     WriteUseList(VE, std::move(VE.UseListOrders.back()), Stream);
2475     VE.UseListOrders.pop_back();
2476   }
2477   Stream.ExitBlock();
2478 }
2479 
2480 // Walk through the operands of a given User via worklist iteration and populate
2481 // the set of GlobalValue references encountered. Invoked either on an
2482 // Instruction or a GlobalVariable (which walks its initializer).
2483 static void findRefEdges(const User *CurUser, const ValueEnumerator &VE,
2484                          DenseSet<unsigned> &RefEdges,
2485                          SmallPtrSet<const User *, 8> &Visited) {
2486   SmallVector<const User *, 32> Worklist;
2487   Worklist.push_back(CurUser);
2488 
2489   while (!Worklist.empty()) {
2490     const User *U = Worklist.pop_back_val();
2491 
2492     if (!Visited.insert(U).second)
2493       continue;
2494 
2495     ImmutableCallSite CS(U);
2496 
2497     for (const auto &OI : U->operands()) {
2498       const User *Operand = dyn_cast<User>(OI);
2499       if (!Operand)
2500         continue;
2501       if (isa<BlockAddress>(Operand))
2502         continue;
2503       if (isa<GlobalValue>(Operand)) {
2504         // We have a reference to a global value. This should be added to
2505         // the reference set unless it is a callee. Callees are handled
2506         // specially by WriteFunction and are added to a separate list.
2507         if (!(CS && CS.isCallee(&OI)))
2508           RefEdges.insert(VE.getValueID(Operand));
2509         continue;
2510       }
2511       Worklist.push_back(Operand);
2512     }
2513   }
2514 }
2515 
2516 /// Emit a function body to the module stream.
2517 static void WriteFunction(
2518     const Function &F, const Module *M, ValueEnumerator &VE,
2519     BitstreamWriter &Stream,
2520     DenseMap<const Function *, std::unique_ptr<GlobalValueInfo>> &FunctionIndex,
2521     bool EmitSummaryIndex) {
2522   // Save the bitcode index of the start of this function block for recording
2523   // in the VST.
2524   uint64_t BitcodeIndex = Stream.GetCurrentBitNo();
2525 
2526   bool HasProfileData = F.getEntryCount().hasValue();
2527   std::unique_ptr<BlockFrequencyInfo> BFI;
2528   if (EmitSummaryIndex && HasProfileData) {
2529     Function &Func = const_cast<Function &>(F);
2530     LoopInfo LI{DominatorTree(Func)};
2531     BranchProbabilityInfo BPI{Func, LI};
2532     BFI = llvm::make_unique<BlockFrequencyInfo>(Func, BPI, LI);
2533   }
2534 
2535   Stream.EnterSubblock(bitc::FUNCTION_BLOCK_ID, 4);
2536   VE.incorporateFunction(F);
2537 
2538   SmallVector<unsigned, 64> Vals;
2539 
2540   // Emit the number of basic blocks, so the reader can create them ahead of
2541   // time.
2542   Vals.push_back(VE.getBasicBlocks().size());
2543   Stream.EmitRecord(bitc::FUNC_CODE_DECLAREBLOCKS, Vals);
2544   Vals.clear();
2545 
2546   // If there are function-local constants, emit them now.
2547   unsigned CstStart, CstEnd;
2548   VE.getFunctionConstantRange(CstStart, CstEnd);
2549   WriteConstants(CstStart, CstEnd, VE, Stream, false);
2550 
2551   // If there is function-local metadata, emit it now.
2552   WriteFunctionLocalMetadata(F, VE, Stream);
2553 
2554   // Keep a running idea of what the instruction ID is.
2555   unsigned InstID = CstEnd;
2556 
2557   bool NeedsMetadataAttachment = F.hasMetadata();
2558 
2559   DILocation *LastDL = nullptr;
2560   unsigned NumInsts = 0;
2561   // Map from callee ValueId to profile count. Used to accumulate profile
2562   // counts for all static calls to a given callee.
2563   DenseMap<unsigned, CalleeInfo> CallGraphEdges;
2564   DenseSet<unsigned> RefEdges;
2565 
2566   SmallPtrSet<const User *, 8> Visited;
2567   // Finally, emit all the instructions, in order.
2568   for (Function::const_iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
2569     for (BasicBlock::const_iterator I = BB->begin(), E = BB->end();
2570          I != E; ++I) {
2571       WriteInstruction(*I, InstID, VE, Stream, Vals);
2572 
2573       if (!isa<DbgInfoIntrinsic>(I))
2574         ++NumInsts;
2575 
2576       if (!I->getType()->isVoidTy())
2577         ++InstID;
2578 
2579       if (EmitSummaryIndex) {
2580         if (auto CS = ImmutableCallSite(&*I)) {
2581           auto *CalledFunction = CS.getCalledFunction();
2582           if (CalledFunction && CalledFunction->hasName() &&
2583               !CalledFunction->isIntrinsic()) {
2584             auto ScaledCount = BFI ? BFI->getBlockProfileCount(&*BB) : None;
2585             unsigned CalleeId = VE.getValueID(
2586                 M->getValueSymbolTable().lookup(CalledFunction->getName()));
2587             CallGraphEdges[CalleeId] +=
2588                 (ScaledCount ? ScaledCount.getValue() : 0);
2589           }
2590         }
2591         findRefEdges(&*I, VE, RefEdges, Visited);
2592       }
2593 
2594       // If the instruction has metadata, write a metadata attachment later.
2595       NeedsMetadataAttachment |= I->hasMetadataOtherThanDebugLoc();
2596 
2597       // If the instruction has a debug location, emit it.
2598       DILocation *DL = I->getDebugLoc();
2599       if (!DL)
2600         continue;
2601 
2602       if (DL == LastDL) {
2603         // Just repeat the same debug loc as last time.
2604         Stream.EmitRecord(bitc::FUNC_CODE_DEBUG_LOC_AGAIN, Vals);
2605         continue;
2606       }
2607 
2608       Vals.push_back(DL->getLine());
2609       Vals.push_back(DL->getColumn());
2610       Vals.push_back(VE.getMetadataOrNullID(DL->getScope()));
2611       Vals.push_back(VE.getMetadataOrNullID(DL->getInlinedAt()));
2612       Stream.EmitRecord(bitc::FUNC_CODE_DEBUG_LOC, Vals);
2613       Vals.clear();
2614 
2615       LastDL = DL;
2616     }
2617 
2618   std::unique_ptr<FunctionSummary> FuncSummary;
2619   if (EmitSummaryIndex) {
2620     FuncSummary = llvm::make_unique<FunctionSummary>(F.getLinkage(), NumInsts);
2621     FuncSummary->addCallGraphEdges(CallGraphEdges);
2622     FuncSummary->addRefEdges(RefEdges);
2623   }
2624   FunctionIndex[&F] =
2625       llvm::make_unique<GlobalValueInfo>(BitcodeIndex, std::move(FuncSummary));
2626 
2627   // Emit names for all the instructions etc.
2628   WriteValueSymbolTable(F.getValueSymbolTable(), VE, Stream);
2629 
2630   if (NeedsMetadataAttachment)
2631     WriteMetadataAttachment(F, VE, Stream);
2632   if (VE.shouldPreserveUseListOrder())
2633     WriteUseListBlock(&F, VE, Stream);
2634   VE.purgeFunction();
2635   Stream.ExitBlock();
2636 }
2637 
2638 // Emit blockinfo, which defines the standard abbreviations etc.
2639 static void WriteBlockInfo(const ValueEnumerator &VE, BitstreamWriter &Stream) {
2640   // We only want to emit block info records for blocks that have multiple
2641   // instances: CONSTANTS_BLOCK, FUNCTION_BLOCK and VALUE_SYMTAB_BLOCK.
2642   // Other blocks can define their abbrevs inline.
2643   Stream.EnterBlockInfoBlock(2);
2644 
2645   { // 8-bit fixed-width VST_CODE_ENTRY/VST_CODE_BBENTRY strings.
2646     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2647     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 3));
2648     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
2649     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2650     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
2651     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
2652                                    Abbv) != VST_ENTRY_8_ABBREV)
2653       llvm_unreachable("Unexpected abbrev ordering!");
2654   }
2655 
2656   { // 7-bit fixed width VST_CODE_ENTRY strings.
2657     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2658     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
2659     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
2660     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2661     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
2662     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
2663                                    Abbv) != VST_ENTRY_7_ABBREV)
2664       llvm_unreachable("Unexpected abbrev ordering!");
2665   }
2666   { // 6-bit char6 VST_CODE_ENTRY strings.
2667     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2668     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
2669     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
2670     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2671     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
2672     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
2673                                    Abbv) != VST_ENTRY_6_ABBREV)
2674       llvm_unreachable("Unexpected abbrev ordering!");
2675   }
2676   { // 6-bit char6 VST_CODE_BBENTRY strings.
2677     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2678     Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_BBENTRY));
2679     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
2680     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2681     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
2682     if (Stream.EmitBlockInfoAbbrev(bitc::VALUE_SYMTAB_BLOCK_ID,
2683                                    Abbv) != VST_BBENTRY_6_ABBREV)
2684       llvm_unreachable("Unexpected abbrev ordering!");
2685   }
2686 
2687 
2688 
2689   { // SETTYPE abbrev for CONSTANTS_BLOCK.
2690     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2691     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_SETTYPE));
2692     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
2693                               VE.computeBitsRequiredForTypeIndicies()));
2694     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
2695                                    Abbv) != CONSTANTS_SETTYPE_ABBREV)
2696       llvm_unreachable("Unexpected abbrev ordering!");
2697   }
2698 
2699   { // INTEGER abbrev for CONSTANTS_BLOCK.
2700     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2701     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_INTEGER));
2702     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
2703     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
2704                                    Abbv) != CONSTANTS_INTEGER_ABBREV)
2705       llvm_unreachable("Unexpected abbrev ordering!");
2706   }
2707 
2708   { // CE_CAST abbrev for CONSTANTS_BLOCK.
2709     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2710     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CE_CAST));
2711     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // cast opc
2712     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // typeid
2713                               VE.computeBitsRequiredForTypeIndicies()));
2714     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));    // value id
2715 
2716     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
2717                                    Abbv) != CONSTANTS_CE_CAST_Abbrev)
2718       llvm_unreachable("Unexpected abbrev ordering!");
2719   }
2720   { // NULL abbrev for CONSTANTS_BLOCK.
2721     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2722     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_NULL));
2723     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
2724                                    Abbv) != CONSTANTS_NULL_Abbrev)
2725       llvm_unreachable("Unexpected abbrev ordering!");
2726   }
2727 
2728   // FIXME: This should only use space for first class types!
2729 
2730   { // INST_LOAD abbrev for FUNCTION_BLOCK.
2731     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2732     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_LOAD));
2733     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Ptr
2734     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,    // dest ty
2735                               VE.computeBitsRequiredForTypeIndicies()));
2736     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4)); // Align
2737     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // volatile
2738     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
2739                                    Abbv) != FUNCTION_INST_LOAD_ABBREV)
2740       llvm_unreachable("Unexpected abbrev ordering!");
2741   }
2742   { // INST_BINOP abbrev for FUNCTION_BLOCK.
2743     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2744     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
2745     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
2746     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
2747     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
2748     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
2749                                    Abbv) != FUNCTION_INST_BINOP_ABBREV)
2750       llvm_unreachable("Unexpected abbrev ordering!");
2751   }
2752   { // INST_BINOP_FLAGS abbrev for FUNCTION_BLOCK.
2753     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2754     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_BINOP));
2755     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LHS
2756     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // RHS
2757     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // opc
2758     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7)); // flags
2759     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
2760                                    Abbv) != FUNCTION_INST_BINOP_FLAGS_ABBREV)
2761       llvm_unreachable("Unexpected abbrev ordering!");
2762   }
2763   { // INST_CAST abbrev for FUNCTION_BLOCK.
2764     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2765     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_CAST));
2766     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));    // OpVal
2767     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // dest ty
2768                               VE.computeBitsRequiredForTypeIndicies()));
2769     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // opc
2770     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
2771                                    Abbv) != FUNCTION_INST_CAST_ABBREV)
2772       llvm_unreachable("Unexpected abbrev ordering!");
2773   }
2774 
2775   { // INST_RET abbrev for FUNCTION_BLOCK.
2776     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2777     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
2778     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
2779                                    Abbv) != FUNCTION_INST_RET_VOID_ABBREV)
2780       llvm_unreachable("Unexpected abbrev ordering!");
2781   }
2782   { // INST_RET abbrev for FUNCTION_BLOCK.
2783     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2784     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_RET));
2785     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // ValID
2786     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
2787                                    Abbv) != FUNCTION_INST_RET_VAL_ABBREV)
2788       llvm_unreachable("Unexpected abbrev ordering!");
2789   }
2790   { // INST_UNREACHABLE abbrev for FUNCTION_BLOCK.
2791     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2792     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_UNREACHABLE));
2793     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
2794                                    Abbv) != FUNCTION_INST_UNREACHABLE_ABBREV)
2795       llvm_unreachable("Unexpected abbrev ordering!");
2796   }
2797   {
2798     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2799     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_GEP));
2800     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
2801     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, // dest ty
2802                               Log2_32_Ceil(VE.getTypes().size() + 1)));
2803     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2804     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
2805     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
2806         FUNCTION_INST_GEP_ABBREV)
2807       llvm_unreachable("Unexpected abbrev ordering!");
2808   }
2809 
2810   Stream.ExitBlock();
2811 }
2812 
2813 /// Write the module path strings, currently only used when generating
2814 /// a combined index file.
2815 static void WriteModStrings(const ModuleSummaryIndex &I,
2816                             BitstreamWriter &Stream) {
2817   Stream.EnterSubblock(bitc::MODULE_STRTAB_BLOCK_ID, 3);
2818 
2819   // TODO: See which abbrev sizes we actually need to emit
2820 
2821   // 8-bit fixed-width MST_ENTRY strings.
2822   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2823   Abbv->Add(BitCodeAbbrevOp(bitc::MST_CODE_ENTRY));
2824   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
2825   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2826   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
2827   unsigned Abbrev8Bit = Stream.EmitAbbrev(Abbv);
2828 
2829   // 7-bit fixed width MST_ENTRY strings.
2830   Abbv = new BitCodeAbbrev();
2831   Abbv->Add(BitCodeAbbrevOp(bitc::MST_CODE_ENTRY));
2832   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
2833   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2834   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
2835   unsigned Abbrev7Bit = Stream.EmitAbbrev(Abbv);
2836 
2837   // 6-bit char6 MST_ENTRY strings.
2838   Abbv = new BitCodeAbbrev();
2839   Abbv->Add(BitCodeAbbrevOp(bitc::MST_CODE_ENTRY));
2840   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
2841   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2842   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
2843   unsigned Abbrev6Bit = Stream.EmitAbbrev(Abbv);
2844 
2845   SmallVector<unsigned, 64> NameVals;
2846   for (const StringMapEntry<uint64_t> &MPSE : I.modPathStringEntries()) {
2847     StringEncoding Bits =
2848         getStringEncoding(MPSE.getKey().data(), MPSE.getKey().size());
2849     unsigned AbbrevToUse = Abbrev8Bit;
2850     if (Bits == SE_Char6)
2851       AbbrevToUse = Abbrev6Bit;
2852     else if (Bits == SE_Fixed7)
2853       AbbrevToUse = Abbrev7Bit;
2854 
2855     NameVals.push_back(MPSE.getValue());
2856 
2857     for (const auto P : MPSE.getKey())
2858       NameVals.push_back((unsigned char)P);
2859 
2860     // Emit the finished record.
2861     Stream.EmitRecord(bitc::MST_CODE_ENTRY, NameVals, AbbrevToUse);
2862     NameVals.clear();
2863   }
2864   Stream.ExitBlock();
2865 }
2866 
2867 // Helper to emit a single function summary record.
2868 static void WritePerModuleFunctionSummaryRecord(
2869     SmallVector<uint64_t, 64> &NameVals, FunctionSummary *FS, unsigned ValueID,
2870     unsigned FSCallsAbbrev, unsigned FSCallsProfileAbbrev,
2871     BitstreamWriter &Stream, const Function &F) {
2872   assert(FS);
2873   NameVals.push_back(ValueID);
2874   NameVals.push_back(getEncodedLinkage(FS->linkage()));
2875   NameVals.push_back(FS->instCount());
2876   NameVals.push_back(FS->refs().size());
2877 
2878   for (auto &RI : FS->refs())
2879     NameVals.push_back(RI);
2880 
2881   bool HasProfileData = F.getEntryCount().hasValue();
2882   for (auto &ECI : FS->edges()) {
2883     NameVals.push_back(ECI.first);
2884     assert(ECI.second.CallsiteCount > 0 && "Expected at least one callsite");
2885     NameVals.push_back(ECI.second.CallsiteCount);
2886     if (HasProfileData)
2887       NameVals.push_back(ECI.second.ProfileCount);
2888   }
2889 
2890   unsigned FSAbbrev = (HasProfileData ? FSCallsProfileAbbrev : FSCallsAbbrev);
2891   unsigned Code =
2892       (HasProfileData ? bitc::FS_PERMODULE_PROFILE : bitc::FS_PERMODULE);
2893 
2894   // Emit the finished record.
2895   Stream.EmitRecord(Code, NameVals, FSAbbrev);
2896   NameVals.clear();
2897 }
2898 
2899 // Collect the global value references in the given variable's initializer,
2900 // and emit them in a summary record.
2901 static void WriteModuleLevelReferences(const GlobalVariable &V,
2902                                        const ValueEnumerator &VE,
2903                                        SmallVector<uint64_t, 64> &NameVals,
2904                                        unsigned FSModRefsAbbrev,
2905                                        BitstreamWriter &Stream) {
2906   // Only interested in recording variable defs in the summary.
2907   if (V.isDeclaration())
2908     return;
2909   DenseSet<unsigned> RefEdges;
2910   SmallPtrSet<const User *, 8> Visited;
2911   findRefEdges(&V, VE, RefEdges, Visited);
2912   NameVals.push_back(VE.getValueID(&V));
2913   NameVals.push_back(getEncodedLinkage(V.getLinkage()));
2914   for (auto RefId : RefEdges) {
2915     NameVals.push_back(RefId);
2916   }
2917   Stream.EmitRecord(bitc::FS_PERMODULE_GLOBALVAR_INIT_REFS, NameVals,
2918                     FSModRefsAbbrev);
2919   NameVals.clear();
2920 }
2921 
2922 /// Emit the per-module summary section alongside the rest of
2923 /// the module's bitcode.
2924 static void WritePerModuleGlobalValueSummary(
2925     DenseMap<const Function *, std::unique_ptr<GlobalValueInfo>> &FunctionIndex,
2926     const Module *M, const ValueEnumerator &VE, BitstreamWriter &Stream) {
2927   if (M->empty())
2928     return;
2929 
2930   Stream.EnterSubblock(bitc::GLOBALVAL_SUMMARY_BLOCK_ID, 3);
2931 
2932   // Abbrev for FS_PERMODULE.
2933   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
2934   Abbv->Add(BitCodeAbbrevOp(bitc::FS_PERMODULE));
2935   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
2936   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 5)); // linkage
2937   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
2938   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
2939   // numrefs x valueid, n x (valueid, callsitecount)
2940   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2941   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
2942   unsigned FSCallsAbbrev = Stream.EmitAbbrev(Abbv);
2943 
2944   // Abbrev for FS_PERMODULE_PROFILE.
2945   Abbv = new BitCodeAbbrev();
2946   Abbv->Add(BitCodeAbbrevOp(bitc::FS_PERMODULE_PROFILE));
2947   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
2948   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 5)); // linkage
2949   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
2950   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
2951   // numrefs x valueid, n x (valueid, callsitecount, profilecount)
2952   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
2953   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
2954   unsigned FSCallsProfileAbbrev = Stream.EmitAbbrev(Abbv);
2955 
2956   // Abbrev for FS_PERMODULE_GLOBALVAR_INIT_REFS.
2957   Abbv = new BitCodeAbbrev();
2958   Abbv->Add(BitCodeAbbrevOp(bitc::FS_PERMODULE_GLOBALVAR_INIT_REFS));
2959   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // valueid
2960   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 5)); // linkage
2961   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));  // valueids
2962   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
2963   unsigned FSModRefsAbbrev = Stream.EmitAbbrev(Abbv);
2964 
2965   SmallVector<uint64_t, 64> NameVals;
2966   // Iterate over the list of functions instead of the FunctionIndex map to
2967   // ensure the ordering is stable.
2968   for (const Function &F : *M) {
2969     if (F.isDeclaration())
2970       continue;
2971     // Skip anonymous functions. We will emit a function summary for
2972     // any aliases below.
2973     if (!F.hasName())
2974       continue;
2975 
2976     assert(FunctionIndex.count(&F) == 1);
2977 
2978     WritePerModuleFunctionSummaryRecord(
2979         NameVals, cast<FunctionSummary>(FunctionIndex[&F]->summary()),
2980         VE.getValueID(M->getValueSymbolTable().lookup(F.getName())),
2981         FSCallsAbbrev, FSCallsProfileAbbrev, Stream, F);
2982   }
2983 
2984   for (const GlobalAlias &A : M->aliases()) {
2985     if (!A.getBaseObject())
2986       continue;
2987     const Function *F = dyn_cast<Function>(A.getBaseObject());
2988     if (!F || F->isDeclaration())
2989       continue;
2990 
2991     assert(FunctionIndex.count(F) == 1);
2992     FunctionSummary *FS =
2993         cast<FunctionSummary>(FunctionIndex[F]->summary());
2994     // Add the alias to the reference list of aliasee function.
2995     FS->addRefEdge(
2996         VE.getValueID(M->getValueSymbolTable().lookup(A.getName())));
2997     WritePerModuleFunctionSummaryRecord(
2998         NameVals, FS,
2999         VE.getValueID(M->getValueSymbolTable().lookup(A.getName())),
3000         FSCallsAbbrev, FSCallsProfileAbbrev, Stream, *F);
3001   }
3002 
3003   // Capture references from GlobalVariable initializers, which are outside
3004   // of a function scope.
3005   for (const GlobalVariable &G : M->globals())
3006     WriteModuleLevelReferences(G, VE, NameVals, FSModRefsAbbrev, Stream);
3007   for (const GlobalAlias &A : M->aliases())
3008     if (auto *GV = dyn_cast<GlobalVariable>(A.getBaseObject()))
3009       WriteModuleLevelReferences(*GV, VE, NameVals, FSModRefsAbbrev, Stream);
3010 
3011   Stream.ExitBlock();
3012 }
3013 
3014 /// Emit the combined summary section into the combined index file.
3015 static void WriteCombinedGlobalValueSummary(
3016     const ModuleSummaryIndex &I, BitstreamWriter &Stream,
3017     std::map<uint64_t, unsigned> &GUIDToValueIdMap, unsigned GlobalValueId) {
3018   Stream.EnterSubblock(bitc::GLOBALVAL_SUMMARY_BLOCK_ID, 3);
3019 
3020   // Abbrev for FS_COMBINED.
3021   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
3022   Abbv->Add(BitCodeAbbrevOp(bitc::FS_COMBINED));
3023   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // modid
3024   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 5)); // linkage
3025   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
3026   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
3027   // numrefs x valueid, n x (valueid, callsitecount)
3028   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3029   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3030   unsigned FSCallsAbbrev = Stream.EmitAbbrev(Abbv);
3031 
3032   // Abbrev for FS_COMBINED_PROFILE.
3033   Abbv = new BitCodeAbbrev();
3034   Abbv->Add(BitCodeAbbrevOp(bitc::FS_COMBINED_PROFILE));
3035   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // modid
3036   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 5)); // linkage
3037   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
3038   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
3039   // numrefs x valueid, n x (valueid, callsitecount, profilecount)
3040   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3041   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3042   unsigned FSCallsProfileAbbrev = Stream.EmitAbbrev(Abbv);
3043 
3044   // Abbrev for FS_COMBINED_GLOBALVAR_INIT_REFS.
3045   Abbv = new BitCodeAbbrev();
3046   Abbv->Add(BitCodeAbbrevOp(bitc::FS_COMBINED_GLOBALVAR_INIT_REFS));
3047   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // modid
3048   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 5)); // linkage
3049   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));    // valueids
3050   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
3051   unsigned FSModRefsAbbrev = Stream.EmitAbbrev(Abbv);
3052 
3053   SmallVector<uint64_t, 64> NameVals;
3054   for (const auto &FII : I) {
3055     for (auto &FI : FII.second) {
3056       GlobalValueSummary *S = FI->summary();
3057       assert(S);
3058 
3059       if (auto *VS = dyn_cast<GlobalVarSummary>(S)) {
3060         NameVals.push_back(I.getModuleId(VS->modulePath()));
3061         NameVals.push_back(getEncodedLinkage(VS->linkage()));
3062         for (auto &RI : VS->refs()) {
3063           const auto &VMI = GUIDToValueIdMap.find(RI);
3064           unsigned RefId;
3065           // If this GUID doesn't have an entry, assign one.
3066           if (VMI == GUIDToValueIdMap.end()) {
3067             GUIDToValueIdMap[RI] = ++GlobalValueId;
3068             RefId = GlobalValueId;
3069           } else {
3070             RefId = VMI->second;
3071           }
3072           NameVals.push_back(RefId);
3073         }
3074 
3075         // Record the starting offset of this summary entry for use
3076         // in the VST entry. Add the current code size since the
3077         // reader will invoke readRecord after the abbrev id read.
3078         FI->setBitcodeIndex(Stream.GetCurrentBitNo() +
3079                             Stream.GetAbbrevIDWidth());
3080 
3081         // Emit the finished record.
3082         Stream.EmitRecord(bitc::FS_COMBINED_GLOBALVAR_INIT_REFS, NameVals,
3083                           FSModRefsAbbrev);
3084         NameVals.clear();
3085         continue;
3086       }
3087 
3088       auto *FS = cast<FunctionSummary>(S);
3089       NameVals.push_back(I.getModuleId(FS->modulePath()));
3090       NameVals.push_back(getEncodedLinkage(FS->linkage()));
3091       NameVals.push_back(FS->instCount());
3092       NameVals.push_back(FS->refs().size());
3093 
3094       for (auto &RI : FS->refs()) {
3095         const auto &VMI = GUIDToValueIdMap.find(RI);
3096         unsigned RefId;
3097         // If this GUID doesn't have an entry, assign one.
3098         if (VMI == GUIDToValueIdMap.end()) {
3099           GUIDToValueIdMap[RI] = ++GlobalValueId;
3100           RefId = GlobalValueId;
3101         } else {
3102           RefId = VMI->second;
3103         }
3104         NameVals.push_back(RefId);
3105       }
3106 
3107       bool HasProfileData = false;
3108       for (auto &EI : FS->edges()) {
3109         HasProfileData |= EI.second.ProfileCount != 0;
3110         if (HasProfileData)
3111           break;
3112       }
3113 
3114       for (auto &EI : FS->edges()) {
3115         const auto &VMI = GUIDToValueIdMap.find(EI.first);
3116         // If this GUID doesn't have an entry, it doesn't have a function
3117         // summary and we don't need to record any calls to it.
3118         if (VMI == GUIDToValueIdMap.end())
3119           continue;
3120         NameVals.push_back(VMI->second);
3121         assert(EI.second.CallsiteCount > 0 && "Expected at least one callsite");
3122         NameVals.push_back(EI.second.CallsiteCount);
3123         if (HasProfileData)
3124           NameVals.push_back(EI.second.ProfileCount);
3125       }
3126 
3127       // Record the starting offset of this summary entry for use
3128       // in the VST entry. Add the current code size since the
3129       // reader will invoke readRecord after the abbrev id read.
3130       FI->setBitcodeIndex(Stream.GetCurrentBitNo() + Stream.GetAbbrevIDWidth());
3131 
3132       unsigned FSAbbrev =
3133           (HasProfileData ? FSCallsProfileAbbrev : FSCallsAbbrev);
3134       unsigned Code =
3135           (HasProfileData ? bitc::FS_COMBINED_PROFILE : bitc::FS_COMBINED);
3136 
3137       // Emit the finished record.
3138       Stream.EmitRecord(Code, NameVals, FSAbbrev);
3139       NameVals.clear();
3140     }
3141   }
3142 
3143   Stream.ExitBlock();
3144 }
3145 
3146 // Create the "IDENTIFICATION_BLOCK_ID" containing a single string with the
3147 // current llvm version, and a record for the epoch number.
3148 static void WriteIdentificationBlock(const Module *M, BitstreamWriter &Stream) {
3149   Stream.EnterSubblock(bitc::IDENTIFICATION_BLOCK_ID, 5);
3150 
3151   // Write the "user readable" string identifying the bitcode producer
3152   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
3153   Abbv->Add(BitCodeAbbrevOp(bitc::IDENTIFICATION_CODE_STRING));
3154   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
3155   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
3156   auto StringAbbrev = Stream.EmitAbbrev(Abbv);
3157   WriteStringRecord(bitc::IDENTIFICATION_CODE_STRING,
3158                     "LLVM" LLVM_VERSION_STRING, StringAbbrev, Stream);
3159 
3160   // Write the epoch version
3161   Abbv = new BitCodeAbbrev();
3162   Abbv->Add(BitCodeAbbrevOp(bitc::IDENTIFICATION_CODE_EPOCH));
3163   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
3164   auto EpochAbbrev = Stream.EmitAbbrev(Abbv);
3165   SmallVector<unsigned, 1> Vals = {bitc::BITCODE_CURRENT_EPOCH};
3166   Stream.EmitRecord(bitc::IDENTIFICATION_CODE_EPOCH, Vals, EpochAbbrev);
3167   Stream.ExitBlock();
3168 }
3169 
3170 /// WriteModule - Emit the specified module to the bitstream.
3171 static void WriteModule(const Module *M, BitstreamWriter &Stream,
3172                         bool ShouldPreserveUseListOrder,
3173                         uint64_t BitcodeStartBit, bool EmitSummaryIndex) {
3174   Stream.EnterSubblock(bitc::MODULE_BLOCK_ID, 3);
3175 
3176   SmallVector<unsigned, 1> Vals;
3177   unsigned CurVersion = 1;
3178   Vals.push_back(CurVersion);
3179   Stream.EmitRecord(bitc::MODULE_CODE_VERSION, Vals);
3180 
3181   // Analyze the module, enumerating globals, functions, etc.
3182   ValueEnumerator VE(*M, ShouldPreserveUseListOrder);
3183 
3184   // Emit blockinfo, which defines the standard abbreviations etc.
3185   WriteBlockInfo(VE, Stream);
3186 
3187   // Emit information about attribute groups.
3188   WriteAttributeGroupTable(VE, Stream);
3189 
3190   // Emit information about parameter attributes.
3191   WriteAttributeTable(VE, Stream);
3192 
3193   // Emit information describing all of the types in the module.
3194   WriteTypeTable(VE, Stream);
3195 
3196   writeComdats(VE, Stream);
3197 
3198   // Emit top-level description of module, including target triple, inline asm,
3199   // descriptors for global variables, and function prototype info.
3200   uint64_t VSTOffsetPlaceholder = WriteModuleInfo(M, VE, Stream);
3201 
3202   // Emit constants.
3203   WriteModuleConstants(VE, Stream);
3204 
3205   // Emit metadata.
3206   WriteModuleMetadata(*M, VE, Stream);
3207 
3208   // Emit metadata.
3209   WriteModuleMetadataStore(M, Stream);
3210 
3211   // Emit module-level use-lists.
3212   if (VE.shouldPreserveUseListOrder())
3213     WriteUseListBlock(nullptr, VE, Stream);
3214 
3215   WriteOperandBundleTags(M, Stream);
3216 
3217   // Emit function bodies.
3218   DenseMap<const Function *, std::unique_ptr<GlobalValueInfo>> FunctionIndex;
3219   for (Module::const_iterator F = M->begin(), E = M->end(); F != E; ++F)
3220     if (!F->isDeclaration())
3221       WriteFunction(*F, M, VE, Stream, FunctionIndex, EmitSummaryIndex);
3222 
3223   // Need to write after the above call to WriteFunction which populates
3224   // the summary information in the index.
3225   if (EmitSummaryIndex)
3226     WritePerModuleGlobalValueSummary(FunctionIndex, M, VE, Stream);
3227 
3228   WriteValueSymbolTable(M->getValueSymbolTable(), VE, Stream,
3229                         VSTOffsetPlaceholder, BitcodeStartBit, &FunctionIndex);
3230 
3231   Stream.ExitBlock();
3232 }
3233 
3234 /// EmitDarwinBCHeader - If generating a bc file on darwin, we have to emit a
3235 /// header and trailer to make it compatible with the system archiver.  To do
3236 /// this we emit the following header, and then emit a trailer that pads the
3237 /// file out to be a multiple of 16 bytes.
3238 ///
3239 /// struct bc_header {
3240 ///   uint32_t Magic;         // 0x0B17C0DE
3241 ///   uint32_t Version;       // Version, currently always 0.
3242 ///   uint32_t BitcodeOffset; // Offset to traditional bitcode file.
3243 ///   uint32_t BitcodeSize;   // Size of traditional bitcode file.
3244 ///   uint32_t CPUType;       // CPU specifier.
3245 ///   ... potentially more later ...
3246 /// };
3247 
3248 static void WriteInt32ToBuffer(uint32_t Value, SmallVectorImpl<char> &Buffer,
3249                                uint32_t &Position) {
3250   support::endian::write32le(&Buffer[Position], Value);
3251   Position += 4;
3252 }
3253 
3254 static void EmitDarwinBCHeaderAndTrailer(SmallVectorImpl<char> &Buffer,
3255                                          const Triple &TT) {
3256   unsigned CPUType = ~0U;
3257 
3258   // Match x86_64-*, i[3-9]86-*, powerpc-*, powerpc64-*, arm-*, thumb-*,
3259   // armv[0-9]-*, thumbv[0-9]-*, armv5te-*, or armv6t2-*. The CPUType is a magic
3260   // number from /usr/include/mach/machine.h.  It is ok to reproduce the
3261   // specific constants here because they are implicitly part of the Darwin ABI.
3262   enum {
3263     DARWIN_CPU_ARCH_ABI64      = 0x01000000,
3264     DARWIN_CPU_TYPE_X86        = 7,
3265     DARWIN_CPU_TYPE_ARM        = 12,
3266     DARWIN_CPU_TYPE_POWERPC    = 18
3267   };
3268 
3269   Triple::ArchType Arch = TT.getArch();
3270   if (Arch == Triple::x86_64)
3271     CPUType = DARWIN_CPU_TYPE_X86 | DARWIN_CPU_ARCH_ABI64;
3272   else if (Arch == Triple::x86)
3273     CPUType = DARWIN_CPU_TYPE_X86;
3274   else if (Arch == Triple::ppc)
3275     CPUType = DARWIN_CPU_TYPE_POWERPC;
3276   else if (Arch == Triple::ppc64)
3277     CPUType = DARWIN_CPU_TYPE_POWERPC | DARWIN_CPU_ARCH_ABI64;
3278   else if (Arch == Triple::arm || Arch == Triple::thumb)
3279     CPUType = DARWIN_CPU_TYPE_ARM;
3280 
3281   // Traditional Bitcode starts after header.
3282   assert(Buffer.size() >= BWH_HeaderSize &&
3283          "Expected header size to be reserved");
3284   unsigned BCOffset = BWH_HeaderSize;
3285   unsigned BCSize = Buffer.size() - BWH_HeaderSize;
3286 
3287   // Write the magic and version.
3288   unsigned Position = 0;
3289   WriteInt32ToBuffer(0x0B17C0DE , Buffer, Position);
3290   WriteInt32ToBuffer(0          , Buffer, Position); // Version.
3291   WriteInt32ToBuffer(BCOffset   , Buffer, Position);
3292   WriteInt32ToBuffer(BCSize     , Buffer, Position);
3293   WriteInt32ToBuffer(CPUType    , Buffer, Position);
3294 
3295   // If the file is not a multiple of 16 bytes, insert dummy padding.
3296   while (Buffer.size() & 15)
3297     Buffer.push_back(0);
3298 }
3299 
3300 /// Helper to write the header common to all bitcode files.
3301 static void WriteBitcodeHeader(BitstreamWriter &Stream) {
3302   // Emit the file header.
3303   Stream.Emit((unsigned)'B', 8);
3304   Stream.Emit((unsigned)'C', 8);
3305   Stream.Emit(0x0, 4);
3306   Stream.Emit(0xC, 4);
3307   Stream.Emit(0xE, 4);
3308   Stream.Emit(0xD, 4);
3309 }
3310 
3311 /// WriteBitcodeToFile - Write the specified module to the specified output
3312 /// stream.
3313 void llvm::WriteBitcodeToFile(const Module *M, raw_ostream &Out,
3314                               bool ShouldPreserveUseListOrder,
3315                               bool EmitSummaryIndex) {
3316   SmallVector<char, 0> Buffer;
3317   Buffer.reserve(256*1024);
3318 
3319   // If this is darwin or another generic macho target, reserve space for the
3320   // header.
3321   Triple TT(M->getTargetTriple());
3322   if (TT.isOSDarwin() || TT.isOSBinFormatMachO())
3323     Buffer.insert(Buffer.begin(), BWH_HeaderSize, 0);
3324 
3325   // Emit the module into the buffer.
3326   {
3327     BitstreamWriter Stream(Buffer);
3328     // Save the start bit of the actual bitcode, in case there is space
3329     // saved at the start for the darwin header above. The reader stream
3330     // will start at the bitcode, and we need the offset of the VST
3331     // to line up.
3332     uint64_t BitcodeStartBit = Stream.GetCurrentBitNo();
3333 
3334     // Emit the file header.
3335     WriteBitcodeHeader(Stream);
3336 
3337     WriteIdentificationBlock(M, Stream);
3338 
3339     // Emit the module.
3340     WriteModule(M, Stream, ShouldPreserveUseListOrder, BitcodeStartBit,
3341                 EmitSummaryIndex);
3342   }
3343 
3344   if (TT.isOSDarwin() || TT.isOSBinFormatMachO())
3345     EmitDarwinBCHeaderAndTrailer(Buffer, TT);
3346 
3347   // Write the generated bitstream to "Out".
3348   Out.write((char*)&Buffer.front(), Buffer.size());
3349 }
3350 
3351 // Write the specified module summary index to the given raw output stream,
3352 // where it will be written in a new bitcode block. This is used when
3353 // writing the combined index file for ThinLTO.
3354 void llvm::WriteIndexToFile(const ModuleSummaryIndex &Index, raw_ostream &Out) {
3355   SmallVector<char, 0> Buffer;
3356   Buffer.reserve(256 * 1024);
3357 
3358   BitstreamWriter Stream(Buffer);
3359 
3360   // Emit the bitcode header.
3361   WriteBitcodeHeader(Stream);
3362 
3363   Stream.EnterSubblock(bitc::MODULE_BLOCK_ID, 3);
3364 
3365   SmallVector<unsigned, 1> Vals;
3366   unsigned CurVersion = 1;
3367   Vals.push_back(CurVersion);
3368   Stream.EmitRecord(bitc::MODULE_CODE_VERSION, Vals);
3369 
3370   // If we have a VST, write the VSTOFFSET record placeholder and record
3371   // its offset.
3372   uint64_t VSTOffsetPlaceholder = WriteValueSymbolTableForwardDecl(Stream);
3373 
3374   // Write the module paths in the combined index.
3375   WriteModStrings(Index, Stream);
3376 
3377   // Assign unique value ids to all functions in the index for use
3378   // in writing out the call graph edges. Save the mapping from GUID
3379   // to the new global value id to use when writing those edges, which
3380   // are currently saved in the index in terms of GUID.
3381   std::map<uint64_t, unsigned> GUIDToValueIdMap;
3382   unsigned GlobalValueId = 0;
3383   for (auto &II : Index)
3384     GUIDToValueIdMap[II.first] = ++GlobalValueId;
3385 
3386   // Write the summary combined index records.
3387   WriteCombinedGlobalValueSummary(Index, Stream, GUIDToValueIdMap,
3388                                   GlobalValueId);
3389 
3390   // Need a special VST writer for the combined index (we don't have a
3391   // real VST and real values when this is invoked).
3392   WriteCombinedValueSymbolTable(Index, Stream, GUIDToValueIdMap,
3393                                 VSTOffsetPlaceholder);
3394 
3395   Stream.ExitBlock();
3396 
3397   Out.write((char *)&Buffer.front(), Buffer.size());
3398 }
3399