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-rw-r--r--contrib/llvm-project/lld/COFF/SymbolTable.cpp615
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diff --git a/contrib/llvm-project/lld/COFF/SymbolTable.cpp b/contrib/llvm-project/lld/COFF/SymbolTable.cpp
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+++ b/contrib/llvm-project/lld/COFF/SymbolTable.cpp
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+//===- SymbolTable.cpp ----------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "SymbolTable.h"
+#include "Config.h"
+#include "Driver.h"
+#include "LTO.h"
+#include "PDB.h"
+#include "Symbols.h"
+#include "lld/Common/ErrorHandler.h"
+#include "lld/Common/Memory.h"
+#include "lld/Common/Timer.h"
+#include "llvm/IR/LLVMContext.h"
+#include "llvm/Object/WindowsMachineFlag.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/raw_ostream.h"
+#include <utility>
+
+using namespace llvm;
+
+namespace lld {
+namespace coff {
+
+static Timer ltoTimer("LTO", Timer::root());
+
+SymbolTable *symtab;
+
+void SymbolTable::addFile(InputFile *file) {
+ log("Reading " + toString(file));
+ file->parse();
+
+ MachineTypes mt = file->getMachineType();
+ if (config->machine == IMAGE_FILE_MACHINE_UNKNOWN) {
+ config->machine = mt;
+ } else if (mt != IMAGE_FILE_MACHINE_UNKNOWN && config->machine != mt) {
+ error(toString(file) + ": machine type " + machineToStr(mt) +
+ " conflicts with " + machineToStr(config->machine));
+ return;
+ }
+
+ if (auto *f = dyn_cast<ObjFile>(file)) {
+ ObjFile::instances.push_back(f);
+ } else if (auto *f = dyn_cast<BitcodeFile>(file)) {
+ BitcodeFile::instances.push_back(f);
+ } else if (auto *f = dyn_cast<ImportFile>(file)) {
+ ImportFile::instances.push_back(f);
+ }
+
+ driver->parseDirectives(file);
+}
+
+static void errorOrWarn(const Twine &s) {
+ if (config->forceUnresolved)
+ warn(s);
+ else
+ error(s);
+}
+
+// Returns the symbol in SC whose value is <= Addr that is closest to Addr.
+// This is generally the global variable or function whose definition contains
+// Addr.
+static Symbol *getSymbol(SectionChunk *sc, uint32_t addr) {
+ DefinedRegular *candidate = nullptr;
+
+ for (Symbol *s : sc->file->getSymbols()) {
+ auto *d = dyn_cast_or_null<DefinedRegular>(s);
+ if (!d || !d->data || d->getChunk() != sc || d->getValue() > addr ||
+ (candidate && d->getValue() < candidate->getValue()))
+ continue;
+
+ candidate = d;
+ }
+
+ return candidate;
+}
+
+// Given a file and the index of a symbol in that file, returns a description
+// of all references to that symbol from that file. If no debug information is
+// available, returns just the name of the file, else one string per actual
+// reference as described in the debug info.
+std::vector<std::string> getSymbolLocations(ObjFile *file, uint32_t symIndex) {
+ struct Location {
+ Symbol *sym;
+ std::pair<StringRef, uint32_t> fileLine;
+ };
+ std::vector<Location> locations;
+
+ for (Chunk *c : file->getChunks()) {
+ auto *sc = dyn_cast<SectionChunk>(c);
+ if (!sc)
+ continue;
+ for (const coff_relocation &r : sc->getRelocs()) {
+ if (r.SymbolTableIndex != symIndex)
+ continue;
+ std::pair<StringRef, uint32_t> fileLine =
+ getFileLine(sc, r.VirtualAddress);
+ Symbol *sym = getSymbol(sc, r.VirtualAddress);
+ if (!fileLine.first.empty() || sym)
+ locations.push_back({sym, fileLine});
+ }
+ }
+
+ if (locations.empty())
+ return std::vector<std::string>({"\n>>> referenced by " + toString(file)});
+
+ std::vector<std::string> symbolLocations(locations.size());
+ size_t i = 0;
+ for (Location loc : locations) {
+ llvm::raw_string_ostream os(symbolLocations[i++]);
+ os << "\n>>> referenced by ";
+ if (!loc.fileLine.first.empty())
+ os << loc.fileLine.first << ":" << loc.fileLine.second
+ << "\n>>> ";
+ os << toString(file);
+ if (loc.sym)
+ os << ":(" << toString(*loc.sym) << ')';
+ }
+ return symbolLocations;
+}
+
+// For an undefined symbol, stores all files referencing it and the index of
+// the undefined symbol in each file.
+struct UndefinedDiag {
+ Symbol *sym;
+ struct File {
+ ObjFile *oFile;
+ uint64_t symIndex;
+ };
+ std::vector<File> files;
+};
+
+static void reportUndefinedSymbol(const UndefinedDiag &undefDiag) {
+ std::string out;
+ llvm::raw_string_ostream os(out);
+ os << "undefined symbol: " << toString(*undefDiag.sym);
+
+ const size_t maxUndefReferences = 10;
+ size_t i = 0, numRefs = 0;
+ for (const UndefinedDiag::File &ref : undefDiag.files) {
+ std::vector<std::string> symbolLocations =
+ getSymbolLocations(ref.oFile, ref.symIndex);
+ numRefs += symbolLocations.size();
+ for (const std::string &s : symbolLocations) {
+ if (i >= maxUndefReferences)
+ break;
+ os << s;
+ i++;
+ }
+ }
+ if (i < numRefs)
+ os << "\n>>> referenced " << numRefs - i << " more times";
+ errorOrWarn(os.str());
+}
+
+void SymbolTable::loadMinGWAutomaticImports() {
+ for (auto &i : symMap) {
+ Symbol *sym = i.second;
+ auto *undef = dyn_cast<Undefined>(sym);
+ if (!undef)
+ continue;
+ if (!sym->isUsedInRegularObj)
+ continue;
+
+ StringRef name = undef->getName();
+
+ if (name.startswith("__imp_"))
+ continue;
+ // If we have an undefined symbol, but we have a Lazy representing a
+ // symbol we could load from file, make sure to load that.
+ Lazy *l = dyn_cast_or_null<Lazy>(find(("__imp_" + name).str()));
+ if (!l || l->pendingArchiveLoad)
+ continue;
+
+ log("Loading lazy " + l->getName() + " from " + l->file->getName() +
+ " for automatic import");
+ l->pendingArchiveLoad = true;
+ l->file->addMember(l->sym);
+ }
+}
+
+bool SymbolTable::handleMinGWAutomaticImport(Symbol *sym, StringRef name) {
+ if (name.startswith("__imp_"))
+ return false;
+ Defined *imp = dyn_cast_or_null<Defined>(find(("__imp_" + name).str()));
+ if (!imp)
+ return false;
+
+ // Replace the reference directly to a variable with a reference
+ // to the import address table instead. This obviously isn't right,
+ // but we mark the symbol as isRuntimePseudoReloc, and a later pass
+ // will add runtime pseudo relocations for every relocation against
+ // this Symbol. The runtime pseudo relocation framework expects the
+ // reference itself to point at the IAT entry.
+ size_t impSize = 0;
+ if (isa<DefinedImportData>(imp)) {
+ log("Automatically importing " + name + " from " +
+ cast<DefinedImportData>(imp)->getDLLName());
+ impSize = sizeof(DefinedImportData);
+ } else if (isa<DefinedRegular>(imp)) {
+ log("Automatically importing " + name + " from " +
+ toString(cast<DefinedRegular>(imp)->file));
+ impSize = sizeof(DefinedRegular);
+ } else {
+ warn("unable to automatically import " + name + " from " + imp->getName() +
+ " from " + toString(cast<DefinedRegular>(imp)->file) +
+ "; unexpected symbol type");
+ return false;
+ }
+ sym->replaceKeepingName(imp, impSize);
+ sym->isRuntimePseudoReloc = true;
+
+ // There may exist symbols named .refptr.<name> which only consist
+ // of a single pointer to <name>. If it turns out <name> is
+ // automatically imported, we don't need to keep the .refptr.<name>
+ // pointer at all, but redirect all accesses to it to the IAT entry
+ // for __imp_<name> instead, and drop the whole .refptr.<name> chunk.
+ DefinedRegular *refptr =
+ dyn_cast_or_null<DefinedRegular>(find((".refptr." + name).str()));
+ if (refptr && refptr->getChunk()->getSize() == config->wordsize) {
+ SectionChunk *sc = dyn_cast_or_null<SectionChunk>(refptr->getChunk());
+ if (sc && sc->getRelocs().size() == 1 && *sc->symbols().begin() == sym) {
+ log("Replacing .refptr." + name + " with " + imp->getName());
+ refptr->getChunk()->live = false;
+ refptr->replaceKeepingName(imp, impSize);
+ }
+ }
+ return true;
+}
+
+void SymbolTable::reportRemainingUndefines() {
+ SmallPtrSet<Symbol *, 8> undefs;
+ DenseMap<Symbol *, Symbol *> localImports;
+
+ for (auto &i : symMap) {
+ Symbol *sym = i.second;
+ auto *undef = dyn_cast<Undefined>(sym);
+ if (!undef)
+ continue;
+ if (!sym->isUsedInRegularObj)
+ continue;
+
+ StringRef name = undef->getName();
+
+ // A weak alias may have been resolved, so check for that.
+ if (Defined *d = undef->getWeakAlias()) {
+ // We want to replace Sym with D. However, we can't just blindly
+ // copy sizeof(SymbolUnion) bytes from D to Sym because D may be an
+ // internal symbol, and internal symbols are stored as "unparented"
+ // Symbols. For that reason we need to check which type of symbol we
+ // are dealing with and copy the correct number of bytes.
+ if (isa<DefinedRegular>(d))
+ memcpy(sym, d, sizeof(DefinedRegular));
+ else if (isa<DefinedAbsolute>(d))
+ memcpy(sym, d, sizeof(DefinedAbsolute));
+ else
+ memcpy(sym, d, sizeof(SymbolUnion));
+ continue;
+ }
+
+ // If we can resolve a symbol by removing __imp_ prefix, do that.
+ // This odd rule is for compatibility with MSVC linker.
+ if (name.startswith("__imp_")) {
+ Symbol *imp = find(name.substr(strlen("__imp_")));
+ if (imp && isa<Defined>(imp)) {
+ auto *d = cast<Defined>(imp);
+ replaceSymbol<DefinedLocalImport>(sym, name, d);
+ localImportChunks.push_back(cast<DefinedLocalImport>(sym)->getChunk());
+ localImports[sym] = d;
+ continue;
+ }
+ }
+
+ // We don't want to report missing Microsoft precompiled headers symbols.
+ // A proper message will be emitted instead in PDBLinker::aquirePrecompObj
+ if (name.contains("_PchSym_"))
+ continue;
+
+ if (config->mingw && handleMinGWAutomaticImport(sym, name))
+ continue;
+
+ // Remaining undefined symbols are not fatal if /force is specified.
+ // They are replaced with dummy defined symbols.
+ if (config->forceUnresolved)
+ replaceSymbol<DefinedAbsolute>(sym, name, 0);
+ undefs.insert(sym);
+ }
+
+ if (undefs.empty() && localImports.empty())
+ return;
+
+ for (Symbol *b : config->gcroot) {
+ if (undefs.count(b))
+ errorOrWarn("<root>: undefined symbol: " + toString(*b));
+ if (config->warnLocallyDefinedImported)
+ if (Symbol *imp = localImports.lookup(b))
+ warn("<root>: locally defined symbol imported: " + toString(*imp) +
+ " (defined in " + toString(imp->getFile()) + ") [LNK4217]");
+ }
+
+ std::vector<UndefinedDiag> undefDiags;
+ DenseMap<Symbol *, int> firstDiag;
+
+ for (ObjFile *file : ObjFile::instances) {
+ size_t symIndex = (size_t)-1;
+ for (Symbol *sym : file->getSymbols()) {
+ ++symIndex;
+ if (!sym)
+ continue;
+ if (undefs.count(sym)) {
+ auto it = firstDiag.find(sym);
+ if (it == firstDiag.end()) {
+ firstDiag[sym] = undefDiags.size();
+ undefDiags.push_back({sym, {{file, symIndex}}});
+ } else {
+ undefDiags[it->second].files.push_back({file, symIndex});
+ }
+ }
+ if (config->warnLocallyDefinedImported)
+ if (Symbol *imp = localImports.lookup(sym))
+ warn(toString(file) +
+ ": locally defined symbol imported: " + toString(*imp) +
+ " (defined in " + toString(imp->getFile()) + ") [LNK4217]");
+ }
+ }
+
+ for (const UndefinedDiag& undefDiag : undefDiags)
+ reportUndefinedSymbol(undefDiag);
+}
+
+std::pair<Symbol *, bool> SymbolTable::insert(StringRef name) {
+ bool inserted = false;
+ Symbol *&sym = symMap[CachedHashStringRef(name)];
+ if (!sym) {
+ sym = reinterpret_cast<Symbol *>(make<SymbolUnion>());
+ sym->isUsedInRegularObj = false;
+ sym->pendingArchiveLoad = false;
+ inserted = true;
+ }
+ return {sym, inserted};
+}
+
+std::pair<Symbol *, bool> SymbolTable::insert(StringRef name, InputFile *file) {
+ std::pair<Symbol *, bool> result = insert(name);
+ if (!file || !isa<BitcodeFile>(file))
+ result.first->isUsedInRegularObj = true;
+ return result;
+}
+
+Symbol *SymbolTable::addUndefined(StringRef name, InputFile *f,
+ bool isWeakAlias) {
+ Symbol *s;
+ bool wasInserted;
+ std::tie(s, wasInserted) = insert(name, f);
+ if (wasInserted || (isa<Lazy>(s) && isWeakAlias)) {
+ replaceSymbol<Undefined>(s, name);
+ return s;
+ }
+ if (auto *l = dyn_cast<Lazy>(s)) {
+ if (!s->pendingArchiveLoad) {
+ s->pendingArchiveLoad = true;
+ l->file->addMember(l->sym);
+ }
+ }
+ return s;
+}
+
+void SymbolTable::addLazy(ArchiveFile *f, const Archive::Symbol &sym) {
+ StringRef name = sym.getName();
+ Symbol *s;
+ bool wasInserted;
+ std::tie(s, wasInserted) = insert(name);
+ if (wasInserted) {
+ replaceSymbol<Lazy>(s, f, sym);
+ return;
+ }
+ auto *u = dyn_cast<Undefined>(s);
+ if (!u || u->weakAlias || s->pendingArchiveLoad)
+ return;
+ s->pendingArchiveLoad = true;
+ f->addMember(sym);
+}
+
+void SymbolTable::reportDuplicate(Symbol *existing, InputFile *newFile) {
+ std::string msg = "duplicate symbol: " + toString(*existing) + " in " +
+ toString(existing->getFile()) + " and in " +
+ toString(newFile);
+
+ if (config->forceMultiple)
+ warn(msg);
+ else
+ error(msg);
+}
+
+Symbol *SymbolTable::addAbsolute(StringRef n, COFFSymbolRef sym) {
+ Symbol *s;
+ bool wasInserted;
+ std::tie(s, wasInserted) = insert(n, nullptr);
+ s->isUsedInRegularObj = true;
+ if (wasInserted || isa<Undefined>(s) || isa<Lazy>(s))
+ replaceSymbol<DefinedAbsolute>(s, n, sym);
+ else if (!isa<DefinedCOFF>(s))
+ reportDuplicate(s, nullptr);
+ return s;
+}
+
+Symbol *SymbolTable::addAbsolute(StringRef n, uint64_t va) {
+ Symbol *s;
+ bool wasInserted;
+ std::tie(s, wasInserted) = insert(n, nullptr);
+ s->isUsedInRegularObj = true;
+ if (wasInserted || isa<Undefined>(s) || isa<Lazy>(s))
+ replaceSymbol<DefinedAbsolute>(s, n, va);
+ else if (!isa<DefinedCOFF>(s))
+ reportDuplicate(s, nullptr);
+ return s;
+}
+
+Symbol *SymbolTable::addSynthetic(StringRef n, Chunk *c) {
+ Symbol *s;
+ bool wasInserted;
+ std::tie(s, wasInserted) = insert(n, nullptr);
+ s->isUsedInRegularObj = true;
+ if (wasInserted || isa<Undefined>(s) || isa<Lazy>(s))
+ replaceSymbol<DefinedSynthetic>(s, n, c);
+ else if (!isa<DefinedCOFF>(s))
+ reportDuplicate(s, nullptr);
+ return s;
+}
+
+Symbol *SymbolTable::addRegular(InputFile *f, StringRef n,
+ const coff_symbol_generic *sym,
+ SectionChunk *c) {
+ Symbol *s;
+ bool wasInserted;
+ std::tie(s, wasInserted) = insert(n, f);
+ if (wasInserted || !isa<DefinedRegular>(s))
+ replaceSymbol<DefinedRegular>(s, f, n, /*IsCOMDAT*/ false,
+ /*IsExternal*/ true, sym, c);
+ else
+ reportDuplicate(s, f);
+ return s;
+}
+
+std::pair<DefinedRegular *, bool>
+SymbolTable::addComdat(InputFile *f, StringRef n,
+ const coff_symbol_generic *sym) {
+ Symbol *s;
+ bool wasInserted;
+ std::tie(s, wasInserted) = insert(n, f);
+ if (wasInserted || !isa<DefinedRegular>(s)) {
+ replaceSymbol<DefinedRegular>(s, f, n, /*IsCOMDAT*/ true,
+ /*IsExternal*/ true, sym, nullptr);
+ return {cast<DefinedRegular>(s), true};
+ }
+ auto *existingSymbol = cast<DefinedRegular>(s);
+ if (!existingSymbol->isCOMDAT)
+ reportDuplicate(s, f);
+ return {existingSymbol, false};
+}
+
+Symbol *SymbolTable::addCommon(InputFile *f, StringRef n, uint64_t size,
+ const coff_symbol_generic *sym, CommonChunk *c) {
+ Symbol *s;
+ bool wasInserted;
+ std::tie(s, wasInserted) = insert(n, f);
+ if (wasInserted || !isa<DefinedCOFF>(s))
+ replaceSymbol<DefinedCommon>(s, f, n, size, sym, c);
+ else if (auto *dc = dyn_cast<DefinedCommon>(s))
+ if (size > dc->getSize())
+ replaceSymbol<DefinedCommon>(s, f, n, size, sym, c);
+ return s;
+}
+
+Symbol *SymbolTable::addImportData(StringRef n, ImportFile *f) {
+ Symbol *s;
+ bool wasInserted;
+ std::tie(s, wasInserted) = insert(n, nullptr);
+ s->isUsedInRegularObj = true;
+ if (wasInserted || isa<Undefined>(s) || isa<Lazy>(s)) {
+ replaceSymbol<DefinedImportData>(s, n, f);
+ return s;
+ }
+
+ reportDuplicate(s, f);
+ return nullptr;
+}
+
+Symbol *SymbolTable::addImportThunk(StringRef name, DefinedImportData *id,
+ uint16_t machine) {
+ Symbol *s;
+ bool wasInserted;
+ std::tie(s, wasInserted) = insert(name, nullptr);
+ s->isUsedInRegularObj = true;
+ if (wasInserted || isa<Undefined>(s) || isa<Lazy>(s)) {
+ replaceSymbol<DefinedImportThunk>(s, name, id, machine);
+ return s;
+ }
+
+ reportDuplicate(s, id->file);
+ return nullptr;
+}
+
+void SymbolTable::addLibcall(StringRef name) {
+ Symbol *sym = findUnderscore(name);
+ if (!sym)
+ return;
+
+ if (Lazy *l = dyn_cast<Lazy>(sym)) {
+ MemoryBufferRef mb = l->getMemberBuffer();
+ if (identify_magic(mb.getBuffer()) == llvm::file_magic::bitcode)
+ addUndefined(sym->getName());
+ }
+}
+
+std::vector<Chunk *> SymbolTable::getChunks() {
+ std::vector<Chunk *> res;
+ for (ObjFile *file : ObjFile::instances) {
+ ArrayRef<Chunk *> v = file->getChunks();
+ res.insert(res.end(), v.begin(), v.end());
+ }
+ return res;
+}
+
+Symbol *SymbolTable::find(StringRef name) {
+ return symMap.lookup(CachedHashStringRef(name));
+}
+
+Symbol *SymbolTable::findUnderscore(StringRef name) {
+ if (config->machine == I386)
+ return find(("_" + name).str());
+ return find(name);
+}
+
+// Return all symbols that start with Prefix, possibly ignoring the first
+// character of Prefix or the first character symbol.
+std::vector<Symbol *> SymbolTable::getSymsWithPrefix(StringRef prefix) {
+ std::vector<Symbol *> syms;
+ for (auto pair : symMap) {
+ StringRef name = pair.first.val();
+ if (name.startswith(prefix) || name.startswith(prefix.drop_front()) ||
+ name.drop_front().startswith(prefix) ||
+ name.drop_front().startswith(prefix.drop_front())) {
+ syms.push_back(pair.second);
+ }
+ }
+ return syms;
+}
+
+Symbol *SymbolTable::findMangle(StringRef name) {
+ if (Symbol *sym = find(name))
+ if (!isa<Undefined>(sym))
+ return sym;
+
+ // Efficient fuzzy string lookup is impossible with a hash table, so iterate
+ // the symbol table once and collect all possibly matching symbols into this
+ // vector. Then compare each possibly matching symbol with each possible
+ // mangling.
+ std::vector<Symbol *> syms = getSymsWithPrefix(name);
+ auto findByPrefix = [&syms](const Twine &t) -> Symbol * {
+ std::string prefix = t.str();
+ for (auto *s : syms)
+ if (s->getName().startswith(prefix))
+ return s;
+ return nullptr;
+ };
+
+ // For non-x86, just look for C++ functions.
+ if (config->machine != I386)
+ return findByPrefix("?" + name + "@@Y");
+
+ if (!name.startswith("_"))
+ return nullptr;
+ // Search for x86 stdcall function.
+ if (Symbol *s = findByPrefix(name + "@"))
+ return s;
+ // Search for x86 fastcall function.
+ if (Symbol *s = findByPrefix("@" + name.substr(1) + "@"))
+ return s;
+ // Search for x86 vectorcall function.
+ if (Symbol *s = findByPrefix(name.substr(1) + "@@"))
+ return s;
+ // Search for x86 C++ non-member function.
+ return findByPrefix("?" + name.substr(1) + "@@Y");
+}
+
+Symbol *SymbolTable::addUndefined(StringRef name) {
+ return addUndefined(name, nullptr, false);
+}
+
+std::vector<StringRef> SymbolTable::compileBitcodeFiles() {
+ lto.reset(new BitcodeCompiler);
+ for (BitcodeFile *f : BitcodeFile::instances)
+ lto->add(*f);
+ return lto->compile();
+}
+
+void SymbolTable::addCombinedLTOObjects() {
+ if (BitcodeFile::instances.empty())
+ return;
+
+ ScopedTimer t(ltoTimer);
+ for (StringRef object : compileBitcodeFiles()) {
+ auto *obj = make<ObjFile>(MemoryBufferRef(object, "lto.tmp"));
+ obj->parse();
+ ObjFile::instances.push_back(obj);
+ }
+}
+
+} // namespace coff
+} // namespace lld
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