forked from OSchip/llvm-project
410 lines
13 KiB
C++
410 lines
13 KiB
C++
//===- SymbolTable.cpp ----------------------------------------------------===//
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//
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// The LLVM Linker
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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#include "SymbolTable.h"
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#include "Config.h"
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#include "Driver.h"
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#include "Error.h"
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#include "Memory.h"
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#include "Symbols.h"
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#include "llvm/IR/LLVMContext.h"
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#include "llvm/LTO/legacy/LTOCodeGenerator.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Support/raw_ostream.h"
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#include <utility>
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using namespace llvm;
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namespace lld {
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namespace coff {
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SymbolTable *Symtab;
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void SymbolTable::addFile(InputFile *File) {
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if (Config->Verbose)
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outs() << "Reading " << toString(File) << "\n";
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File->parse();
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MachineTypes MT = File->getMachineType();
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if (Config->Machine == IMAGE_FILE_MACHINE_UNKNOWN) {
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Config->Machine = MT;
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} else if (MT != IMAGE_FILE_MACHINE_UNKNOWN && Config->Machine != MT) {
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fatal(toString(File) + ": machine type " + machineToStr(MT) +
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" conflicts with " + machineToStr(Config->Machine));
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}
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if (auto *F = dyn_cast<ObjectFile>(File)) {
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ObjectFiles.push_back(F);
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} else if (auto *F = dyn_cast<BitcodeFile>(File)) {
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BitcodeFiles.push_back(F);
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} else if (auto *F = dyn_cast<ImportFile>(File)) {
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ImportFiles.push_back(F);
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}
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StringRef S = File->getDirectives();
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if (S.empty())
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return;
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if (Config->Verbose)
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outs() << "Directives: " << toString(File) << ": " << S << "\n";
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Driver->parseDirectives(S);
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}
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void SymbolTable::reportRemainingUndefines() {
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SmallPtrSet<SymbolBody *, 8> Undefs;
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for (auto &I : Symtab) {
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Symbol *Sym = I.second;
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auto *Undef = dyn_cast<Undefined>(Sym->body());
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if (!Undef)
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continue;
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if (!Sym->IsUsedInRegularObj)
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continue;
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StringRef Name = Undef->getName();
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// A weak alias may have been resolved, so check for that.
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if (Defined *D = Undef->getWeakAlias()) {
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// We resolve weak aliases by replacing the alias's SymbolBody with the
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// target's SymbolBody. This causes all SymbolBody pointers referring to
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// the old symbol to instead refer to the new symbol. However, we can't
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// just blindly copy sizeof(Symbol::Body) bytes from D to Sym->Body
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// because D may be an internal symbol, and internal symbols are stored as
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// "unparented" SymbolBodies. For that reason we need to check which type
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// of symbol we are dealing with and copy the correct number of bytes.
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if (isa<DefinedRegular>(D))
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memcpy(Sym->Body.buffer, D, sizeof(DefinedRegular));
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else if (isa<DefinedAbsolute>(D))
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memcpy(Sym->Body.buffer, D, sizeof(DefinedAbsolute));
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else
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// No other internal symbols are possible.
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Sym->Body = D->symbol()->Body;
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continue;
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}
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// If we can resolve a symbol by removing __imp_ prefix, do that.
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// This odd rule is for compatibility with MSVC linker.
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if (Name.startswith("__imp_")) {
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Symbol *Imp = find(Name.substr(strlen("__imp_")));
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if (Imp && isa<Defined>(Imp->body())) {
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auto *D = cast<Defined>(Imp->body());
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replaceBody<DefinedLocalImport>(Sym, Name, D);
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LocalImportChunks.push_back(
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cast<DefinedLocalImport>(Sym->body())->getChunk());
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continue;
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}
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}
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// Remaining undefined symbols are not fatal if /force is specified.
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// They are replaced with dummy defined symbols.
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if (Config->Force)
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replaceBody<DefinedAbsolute>(Sym, Name, 0);
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Undefs.insert(Sym->body());
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}
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if (Undefs.empty())
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return;
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for (SymbolBody *B : Config->GCRoot)
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if (Undefs.count(B))
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errs() << "<root>: undefined symbol: " << B->getName() << "\n";
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for (ObjectFile *File : ObjectFiles)
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for (SymbolBody *Sym : File->getSymbols())
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if (Undefs.count(Sym))
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errs() << toString(File) << ": undefined symbol: " << Sym->getName()
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<< "\n";
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if (!Config->Force)
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fatal("link failed");
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}
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std::pair<Symbol *, bool> SymbolTable::insert(StringRef Name) {
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Symbol *&Sym = Symtab[CachedHashStringRef(Name)];
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if (Sym)
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return {Sym, false};
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Sym = make<Symbol>();
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Sym->IsUsedInRegularObj = false;
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Sym->PendingArchiveLoad = false;
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return {Sym, true};
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}
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Symbol *SymbolTable::addUndefined(StringRef Name, InputFile *F,
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bool IsWeakAlias) {
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Symbol *S;
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bool WasInserted;
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std::tie(S, WasInserted) = insert(Name);
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if (!F || !isa<BitcodeFile>(F))
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S->IsUsedInRegularObj = true;
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if (WasInserted || (isa<Lazy>(S->body()) && IsWeakAlias)) {
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replaceBody<Undefined>(S, Name);
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return S;
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}
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if (auto *L = dyn_cast<Lazy>(S->body())) {
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if (!S->PendingArchiveLoad) {
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S->PendingArchiveLoad = true;
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L->File->addMember(&L->Sym);
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}
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}
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return S;
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}
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void SymbolTable::addLazy(ArchiveFile *F, const Archive::Symbol Sym) {
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StringRef Name = Sym.getName();
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Symbol *S;
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bool WasInserted;
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std::tie(S, WasInserted) = insert(Name);
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if (WasInserted) {
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replaceBody<Lazy>(S, F, Sym);
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return;
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}
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auto *U = dyn_cast<Undefined>(S->body());
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if (!U || U->WeakAlias || S->PendingArchiveLoad)
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return;
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S->PendingArchiveLoad = true;
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F->addMember(&Sym);
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}
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void SymbolTable::reportDuplicate(Symbol *Existing, InputFile *NewFile) {
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fatal("duplicate symbol: " + toString(*Existing->body()) + " in " +
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toString(Existing->body()->getFile()) + " and in " +
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(NewFile ? toString(NewFile) : "(internal)"));
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}
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Symbol *SymbolTable::addAbsolute(StringRef N, COFFSymbolRef Sym) {
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Symbol *S;
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bool WasInserted;
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std::tie(S, WasInserted) = insert(N);
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S->IsUsedInRegularObj = true;
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if (WasInserted || isa<Undefined>(S->body()) || isa<Lazy>(S->body()))
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replaceBody<DefinedAbsolute>(S, N, Sym);
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else if (!isa<DefinedCOFF>(S->body()))
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reportDuplicate(S, nullptr);
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return S;
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}
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Symbol *SymbolTable::addAbsolute(StringRef N, uint64_t VA) {
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Symbol *S;
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bool WasInserted;
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std::tie(S, WasInserted) = insert(N);
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S->IsUsedInRegularObj = true;
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if (WasInserted || isa<Undefined>(S->body()) || isa<Lazy>(S->body()))
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replaceBody<DefinedAbsolute>(S, N, VA);
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else if (!isa<DefinedCOFF>(S->body()))
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reportDuplicate(S, nullptr);
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return S;
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}
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Symbol *SymbolTable::addRelative(StringRef N, uint64_t VA) {
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Symbol *S;
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bool WasInserted;
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std::tie(S, WasInserted) = insert(N);
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S->IsUsedInRegularObj = true;
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if (WasInserted || isa<Undefined>(S->body()) || isa<Lazy>(S->body()))
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replaceBody<DefinedRelative>(S, N, VA);
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else if (!isa<DefinedCOFF>(S->body()))
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reportDuplicate(S, nullptr);
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return S;
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}
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Symbol *SymbolTable::addRegular(ObjectFile *F, COFFSymbolRef Sym,
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SectionChunk *C) {
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StringRef Name;
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F->getCOFFObj()->getSymbolName(Sym, Name);
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Symbol *S;
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bool WasInserted;
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std::tie(S, WasInserted) = insert(Name);
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S->IsUsedInRegularObj = true;
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if (WasInserted || isa<Undefined>(S->body()) || isa<Lazy>(S->body()))
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replaceBody<DefinedRegular>(S, F, Sym, C);
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else if (auto *R = dyn_cast<DefinedRegular>(S->body())) {
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if (!C->isCOMDAT() || !R->isCOMDAT())
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reportDuplicate(S, F);
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} else if (auto *B = dyn_cast<DefinedBitcode>(S->body())) {
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if (B->IsReplaceable)
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replaceBody<DefinedRegular>(S, F, Sym, C);
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else if (!C->isCOMDAT())
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reportDuplicate(S, F);
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} else
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replaceBody<DefinedRegular>(S, F, Sym, C);
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return S;
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}
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Symbol *SymbolTable::addBitcode(BitcodeFile *F, StringRef N, bool IsReplaceable) {
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Symbol *S;
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bool WasInserted;
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std::tie(S, WasInserted) = insert(N);
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if (WasInserted || isa<Undefined>(S->body()) || isa<Lazy>(S->body())) {
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replaceBody<DefinedBitcode>(S, F, N, IsReplaceable);
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return S;
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}
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if (isa<DefinedCommon>(S->body()))
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return S;
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if (IsReplaceable)
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if (isa<DefinedRegular>(S->body()) || isa<DefinedBitcode>(S->body()))
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return S;
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reportDuplicate(S, F);
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return S;
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}
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Symbol *SymbolTable::addCommon(ObjectFile *F, COFFSymbolRef Sym,
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CommonChunk *C) {
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StringRef Name;
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F->getCOFFObj()->getSymbolName(Sym, Name);
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Symbol *S;
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bool WasInserted;
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std::tie(S, WasInserted) = insert(Name);
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S->IsUsedInRegularObj = true;
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if (WasInserted || !isa<DefinedCOFF>(S->body()))
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replaceBody<DefinedCommon>(S, F, Sym, C);
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else if (auto *DC = dyn_cast<DefinedCommon>(S->body()))
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if (Sym.getValue() > DC->getSize())
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replaceBody<DefinedCommon>(S, F, Sym, C);
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return S;
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}
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Symbol *SymbolTable::addImportData(StringRef N, ImportFile *F) {
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Symbol *S;
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bool WasInserted;
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std::tie(S, WasInserted) = insert(N);
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S->IsUsedInRegularObj = true;
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if (WasInserted || isa<Undefined>(S->body()) || isa<Lazy>(S->body()))
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replaceBody<DefinedImportData>(S, N, F);
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else if (!isa<DefinedCOFF>(S->body()))
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reportDuplicate(S, nullptr);
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return S;
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}
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Symbol *SymbolTable::addImportThunk(StringRef Name, DefinedImportData *ID,
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uint16_t Machine) {
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Symbol *S;
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bool WasInserted;
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std::tie(S, WasInserted) = insert(Name);
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S->IsUsedInRegularObj = true;
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if (WasInserted || isa<Undefined>(S->body()) || isa<Lazy>(S->body()))
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replaceBody<DefinedImportThunk>(S, Name, ID, Machine);
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else if (!isa<DefinedCOFF>(S->body()))
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reportDuplicate(S, nullptr);
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return S;
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}
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std::vector<Chunk *> SymbolTable::getChunks() {
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std::vector<Chunk *> Res;
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for (ObjectFile *File : ObjectFiles) {
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std::vector<Chunk *> &V = File->getChunks();
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Res.insert(Res.end(), V.begin(), V.end());
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}
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return Res;
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}
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Symbol *SymbolTable::find(StringRef Name) {
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auto It = Symtab.find(CachedHashStringRef(Name));
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if (It == Symtab.end())
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return nullptr;
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return It->second;
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}
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Symbol *SymbolTable::findUnderscore(StringRef Name) {
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if (Config->Machine == I386)
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return find(("_" + Name).str());
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return find(Name);
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}
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StringRef SymbolTable::findByPrefix(StringRef Prefix) {
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for (auto Pair : Symtab) {
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StringRef Name = Pair.first.val();
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if (Name.startswith(Prefix))
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return Name;
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}
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return "";
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}
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StringRef SymbolTable::findMangle(StringRef Name) {
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if (Symbol *Sym = find(Name))
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if (!isa<Undefined>(Sym->body()))
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return Name;
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if (Config->Machine != I386)
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return findByPrefix(("?" + Name + "@@Y").str());
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if (!Name.startswith("_"))
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return "";
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// Search for x86 C function.
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StringRef S = findByPrefix((Name + "@").str());
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if (!S.empty())
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return S;
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// Search for x86 C++ non-member function.
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return findByPrefix(("?" + Name.substr(1) + "@@Y").str());
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}
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void SymbolTable::mangleMaybe(SymbolBody *B) {
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auto *U = dyn_cast<Undefined>(B);
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if (!U || U->WeakAlias)
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return;
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StringRef Alias = findMangle(U->getName());
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if (!Alias.empty())
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U->WeakAlias = addUndefined(Alias);
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}
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SymbolBody *SymbolTable::addUndefined(StringRef Name) {
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return addUndefined(Name, nullptr, false)->body();
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}
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void SymbolTable::addCombinedLTOObjects() {
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if (BitcodeFiles.empty())
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return;
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// Create an object file and add it to the symbol table by replacing any
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// DefinedBitcode symbols with the definitions in the object file.
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LTOCodeGenerator CG(BitcodeFile::Context);
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CG.setOptLevel(Config->LTOOptLevel);
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for (ObjectFile *Obj : createLTOObjects(&CG))
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Obj->parse();
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}
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// Combine and compile bitcode files and then return the result
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// as a vector of regular COFF object files.
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std::vector<ObjectFile *> SymbolTable::createLTOObjects(LTOCodeGenerator *CG) {
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// All symbols referenced by non-bitcode objects, including GC roots, must be
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// preserved. We must also replace bitcode symbols with undefined symbols so
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// that they may be replaced with real definitions without conflicting.
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for (BitcodeFile *File : BitcodeFiles)
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for (SymbolBody *Body : File->getSymbols()) {
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if (!isa<DefinedBitcode>(Body))
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continue;
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if (Body->symbol()->IsUsedInRegularObj)
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CG->addMustPreserveSymbol(Body->getName());
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replaceBody<Undefined>(Body->symbol(), Body->getName());
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}
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CG->setModule(BitcodeFiles[0]->takeModule());
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for (unsigned I = 1, E = BitcodeFiles.size(); I != E; ++I)
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CG->addModule(BitcodeFiles[I]->takeModule().get());
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bool DisableVerify = true;
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#ifdef NDEBUG
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DisableVerify = false;
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#endif
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if (!CG->optimize(DisableVerify, false, false, false))
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fatal(""); // optimize() should have emitted any error message.
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Objs.resize(Config->LTOJobs);
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// Use std::list to avoid invalidation of pointers in OSPtrs.
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std::list<raw_svector_ostream> OSs;
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std::vector<raw_pwrite_stream *> OSPtrs;
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for (SmallString<0> &Obj : Objs) {
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OSs.emplace_back(Obj);
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OSPtrs.push_back(&OSs.back());
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}
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if (!CG->compileOptimized(OSPtrs))
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fatal(""); // compileOptimized() should have emitted any error message.
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std::vector<ObjectFile *> ObjFiles;
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for (SmallString<0> &Obj : Objs) {
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auto *ObjFile = make<ObjectFile>(MemoryBufferRef(Obj, "<LTO object>"));
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ObjectFiles.push_back(ObjFile);
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ObjFiles.push_back(ObjFile);
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}
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return ObjFiles;
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}
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} // namespace coff
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} // namespace lld
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