8b0b48f343
With LTO when and undefined function (with a known signature) in replaced by a defined bitcode function we were loosing the signature information (since bitcode functions don't have signatures). With this change we preserve the original signature from the undefined function and verify that the post LTO compiled function has the correct signature. This change improves the error handling in the case where there is a signature mismatch with a function defined in a bitcode file. Differential Revision: https://reviews.llvm.org/D50721 llvm-svn: 343340
351 lines
12 KiB
C++
351 lines
12 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 "InputChunks.h"
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#include "InputGlobal.h"
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#include "WriterUtils.h"
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#include "lld/Common/ErrorHandler.h"
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#include "lld/Common/Memory.h"
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#include "llvm/ADT/SetVector.h"
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#define DEBUG_TYPE "lld"
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using namespace llvm;
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using namespace llvm::wasm;
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using namespace lld;
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using namespace lld::wasm;
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SymbolTable *lld::wasm::Symtab;
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void SymbolTable::addFile(InputFile *File) {
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log("Processing: " + toString(File));
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File->parse();
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// LLVM bitcode file
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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<ObjFile>(File))
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ObjectFiles.push_back(F);
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}
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// This function is where all the optimizations of link-time
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// optimization happens. When LTO is in use, some input files are
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// not in native object file format but in the LLVM bitcode format.
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// This function compiles bitcode files into a few big native files
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// using LLVM functions and replaces bitcode symbols with the results.
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// Because all bitcode files that the program consists of are passed
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// to the compiler at once, it can do whole-program optimization.
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void SymbolTable::addCombinedLTOObject() {
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if (BitcodeFiles.empty())
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return;
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// Compile bitcode files and replace bitcode symbols.
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LTO.reset(new BitcodeCompiler);
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for (BitcodeFile *F : BitcodeFiles)
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LTO->add(*F);
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for (StringRef Filename : LTO->compile()) {
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auto *Obj = make<ObjFile>(MemoryBufferRef(Filename, "lto.tmp"));
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Obj->parse();
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ObjectFiles.push_back(Obj);
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}
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}
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void SymbolTable::reportRemainingUndefines() {
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for (Symbol *Sym : SymVector) {
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if (!Sym->isUndefined() || Sym->isWeak())
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continue;
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if (Config->AllowUndefinedSymbols.count(Sym->getName()) != 0)
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continue;
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if (!Sym->IsUsedInRegularObj)
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continue;
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error(toString(Sym->getFile()) + ": undefined symbol: " + toString(*Sym));
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}
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}
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Symbol *SymbolTable::find(StringRef Name) {
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return SymMap.lookup(CachedHashStringRef(Name));
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}
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std::pair<Symbol *, bool> SymbolTable::insert(StringRef Name, InputFile *File) {
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bool Inserted = false;
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Symbol *&Sym = SymMap[CachedHashStringRef(Name)];
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if (!Sym) {
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Sym = reinterpret_cast<Symbol *>(make<SymbolUnion>());
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Sym->IsUsedInRegularObj = false;
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SymVector.emplace_back(Sym);
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Inserted = true;
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}
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if (!File || File->kind() == InputFile::ObjectKind)
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Sym->IsUsedInRegularObj = true;
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return {Sym, Inserted};
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}
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static void reportTypeError(const Symbol *Existing, const InputFile *File,
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llvm::wasm::WasmSymbolType Type) {
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error("symbol type mismatch: " + toString(*Existing) + "\n>>> defined as " +
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toString(Existing->getWasmType()) + " in " +
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toString(Existing->getFile()) + "\n>>> defined as " + toString(Type) +
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" in " + toString(File));
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}
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static void checkFunctionType(Symbol *Existing, const InputFile *File,
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const WasmSignature *NewSig) {
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auto ExistingFunction = dyn_cast<FunctionSymbol>(Existing);
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if (!ExistingFunction) {
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reportTypeError(Existing, File, WASM_SYMBOL_TYPE_FUNCTION);
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return;
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}
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if (!NewSig)
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return;
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const WasmSignature *OldSig = ExistingFunction->FunctionType;
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if (!OldSig) {
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ExistingFunction->FunctionType = NewSig;
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return;
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}
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if (*NewSig != *OldSig)
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warn("function signature mismatch: " + Existing->getName() +
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"\n>>> defined as " + toString(*OldSig) + " in " +
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toString(Existing->getFile()) + "\n>>> defined as " +
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toString(*NewSig) + " in " + toString(File));
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}
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// Check the type of new symbol matches that of the symbol is replacing.
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// For functions this can also involve verifying that the signatures match.
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static void checkGlobalType(const Symbol *Existing, const InputFile *File,
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const WasmGlobalType *NewType) {
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if (!isa<GlobalSymbol>(Existing)) {
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reportTypeError(Existing, File, WASM_SYMBOL_TYPE_GLOBAL);
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return;
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}
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const WasmGlobalType *OldType = cast<GlobalSymbol>(Existing)->getGlobalType();
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if (*NewType != *OldType) {
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error("Global type mismatch: " + Existing->getName() + "\n>>> defined as " +
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toString(*OldType) + " in " + toString(Existing->getFile()) +
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"\n>>> defined as " + toString(*NewType) + " in " + toString(File));
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}
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}
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static void checkDataType(const Symbol *Existing, const InputFile *File) {
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if (!isa<DataSymbol>(Existing))
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reportTypeError(Existing, File, WASM_SYMBOL_TYPE_DATA);
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}
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DefinedFunction *SymbolTable::addSyntheticFunction(StringRef Name,
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uint32_t Flags,
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InputFunction *Function) {
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LLVM_DEBUG(dbgs() << "addSyntheticFunction: " << Name << "\n");
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assert(!find(Name));
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SyntheticFunctions.emplace_back(Function);
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return replaceSymbol<DefinedFunction>(insert(Name, nullptr).first, Name,
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Flags, nullptr, Function);
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}
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DefinedData *SymbolTable::addSyntheticDataSymbol(StringRef Name,
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uint32_t Flags) {
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LLVM_DEBUG(dbgs() << "addSyntheticDataSymbol: " << Name << "\n");
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assert(!find(Name));
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return replaceSymbol<DefinedData>(insert(Name, nullptr).first, Name, Flags);
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}
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DefinedGlobal *SymbolTable::addSyntheticGlobal(StringRef Name, uint32_t Flags,
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InputGlobal *Global) {
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LLVM_DEBUG(dbgs() << "addSyntheticGlobal: " << Name << " -> " << Global
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<< "\n");
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assert(!find(Name));
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SyntheticGlobals.emplace_back(Global);
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return replaceSymbol<DefinedGlobal>(insert(Name, nullptr).first, Name, Flags,
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nullptr, Global);
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}
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static bool shouldReplace(const Symbol *Existing, InputFile *NewFile,
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uint32_t NewFlags) {
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// If existing symbol is undefined, replace it.
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if (!Existing->isDefined()) {
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LLVM_DEBUG(dbgs() << "resolving existing undefined symbol: "
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<< Existing->getName() << "\n");
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return true;
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}
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// Now we have two defined symbols. If the new one is weak, we can ignore it.
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if ((NewFlags & WASM_SYMBOL_BINDING_MASK) == WASM_SYMBOL_BINDING_WEAK) {
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LLVM_DEBUG(dbgs() << "existing symbol takes precedence\n");
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return false;
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}
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// If the existing symbol is weak, we should replace it.
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if (Existing->isWeak()) {
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LLVM_DEBUG(dbgs() << "replacing existing weak symbol\n");
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return true;
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}
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// Neither symbol is week. They conflict.
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error("duplicate symbol: " + toString(*Existing) + "\n>>> defined in " +
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toString(Existing->getFile()) + "\n>>> defined in " +
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toString(NewFile));
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return true;
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}
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Symbol *SymbolTable::addDefinedFunction(StringRef Name, uint32_t Flags,
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InputFile *File,
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InputFunction *Function) {
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LLVM_DEBUG(dbgs() << "addDefinedFunction: " << Name << " ["
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<< (Function ? toString(Function->Signature) : "none")
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<< "]\n");
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Symbol *S;
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bool WasInserted;
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std::tie(S, WasInserted) = insert(Name, File);
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if (WasInserted || S->isLazy()) {
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replaceSymbol<DefinedFunction>(S, Name, Flags, File, Function);
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return S;
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}
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if (Function)
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checkFunctionType(S, File, &Function->Signature);
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if (shouldReplace(S, File, Flags)) {
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// If the new defined function doesn't have signture (i.e. bitcode
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// functions) but the old symbols does then preserve the old signature
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const WasmSignature *OldSig = nullptr;
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if (auto* F = dyn_cast<FunctionSymbol>(S))
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OldSig = F->FunctionType;
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auto NewSym = replaceSymbol<DefinedFunction>(S, Name, Flags, File, Function);
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if (!NewSym->FunctionType)
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NewSym->FunctionType = OldSig;
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}
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return S;
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}
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Symbol *SymbolTable::addDefinedData(StringRef Name, uint32_t Flags,
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InputFile *File, InputSegment *Segment,
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uint32_t Address, uint32_t Size) {
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LLVM_DEBUG(dbgs() << "addDefinedData:" << Name << " addr:" << Address
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<< "\n");
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Symbol *S;
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bool WasInserted;
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std::tie(S, WasInserted) = insert(Name, File);
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if (WasInserted || S->isLazy()) {
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replaceSymbol<DefinedData>(S, Name, Flags, File, Segment, Address, Size);
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return S;
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}
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checkDataType(S, File);
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if (shouldReplace(S, File, Flags))
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replaceSymbol<DefinedData>(S, Name, Flags, File, Segment, Address, Size);
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return S;
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}
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Symbol *SymbolTable::addDefinedGlobal(StringRef Name, uint32_t Flags,
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InputFile *File, InputGlobal *Global) {
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LLVM_DEBUG(dbgs() << "addDefinedGlobal:" << Name << "\n");
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Symbol *S;
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bool WasInserted;
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std::tie(S, WasInserted) = insert(Name, File);
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if (WasInserted || S->isLazy()) {
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replaceSymbol<DefinedGlobal>(S, Name, Flags, File, Global);
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return S;
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}
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checkGlobalType(S, File, &Global->getType());
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if (shouldReplace(S, File, Flags))
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replaceSymbol<DefinedGlobal>(S, Name, Flags, File, Global);
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return S;
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}
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Symbol *SymbolTable::addUndefinedFunction(StringRef Name, uint32_t Flags,
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InputFile *File,
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const WasmSignature *Sig) {
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LLVM_DEBUG(dbgs() << "addUndefinedFunction: " << Name <<
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" [" << (Sig ? toString(*Sig) : "none") << "]\n");
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Symbol *S;
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bool WasInserted;
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std::tie(S, WasInserted) = insert(Name, File);
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if (WasInserted)
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replaceSymbol<UndefinedFunction>(S, Name, Flags, File, Sig);
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else if (auto *Lazy = dyn_cast<LazySymbol>(S))
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Lazy->fetch();
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else
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checkFunctionType(S, File, Sig);
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return S;
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}
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Symbol *SymbolTable::addUndefinedData(StringRef Name, uint32_t Flags,
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InputFile *File) {
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LLVM_DEBUG(dbgs() << "addUndefinedData: " << Name << "\n");
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Symbol *S;
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bool WasInserted;
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std::tie(S, WasInserted) = insert(Name, File);
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if (WasInserted)
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replaceSymbol<UndefinedData>(S, Name, Flags, File);
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else if (auto *Lazy = dyn_cast<LazySymbol>(S))
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Lazy->fetch();
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else if (S->isDefined())
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checkDataType(S, File);
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return S;
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}
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Symbol *SymbolTable::addUndefinedGlobal(StringRef Name, uint32_t Flags,
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InputFile *File,
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const WasmGlobalType *Type) {
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LLVM_DEBUG(dbgs() << "addUndefinedGlobal: " << Name << "\n");
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Symbol *S;
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bool WasInserted;
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std::tie(S, WasInserted) = insert(Name, File);
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if (WasInserted)
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replaceSymbol<UndefinedGlobal>(S, Name, Flags, File, Type);
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else if (auto *Lazy = dyn_cast<LazySymbol>(S))
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Lazy->fetch();
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else if (S->isDefined())
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checkGlobalType(S, File, Type);
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return S;
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}
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void SymbolTable::addLazy(ArchiveFile *File, const Archive::Symbol *Sym) {
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LLVM_DEBUG(dbgs() << "addLazy: " << Sym->getName() << "\n");
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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, nullptr);
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if (WasInserted) {
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replaceSymbol<LazySymbol>(S, Name, File, *Sym);
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return;
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}
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// If there is an existing undefined symbol, load a new one from the archive.
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if (S->isUndefined()) {
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LLVM_DEBUG(dbgs() << "replacing existing undefined\n");
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File->addMember(Sym);
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}
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}
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bool SymbolTable::addComdat(StringRef Name) {
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return Comdats.insert(CachedHashStringRef(Name)).second;
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}
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