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-rw-r--r--wasm/SymbolTable.cpp245
1 files changed, 245 insertions, 0 deletions
diff --git a/wasm/SymbolTable.cpp b/wasm/SymbolTable.cpp
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+++ b/wasm/SymbolTable.cpp
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+//===- SymbolTable.cpp ----------------------------------------------------===//
+//
+// The LLVM Linker
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "SymbolTable.h"
+
+#include "Config.h"
+#include "WriterUtils.h"
+#include "lld/Common/ErrorHandler.h"
+#include "lld/Common/Memory.h"
+
+#include <unordered_set>
+
+#define DEBUG_TYPE "lld"
+
+using namespace llvm;
+using namespace lld;
+using namespace lld::wasm;
+
+SymbolTable *lld::wasm::Symtab;
+
+void SymbolTable::addFile(InputFile *File) {
+ log("Processing: " + toString(File));
+ File->parse();
+
+ if (auto *F = dyn_cast<ObjFile>(File))
+ ObjectFiles.push_back(F);
+}
+
+void SymbolTable::reportRemainingUndefines() {
+ std::unordered_set<Symbol *> Undefs;
+ for (Symbol *Sym : SymVector) {
+ if (Sym->isUndefined() && !Sym->isWeak() &&
+ Config->AllowUndefinedSymbols.count(Sym->getName()) == 0) {
+ Undefs.insert(Sym);
+ }
+ }
+
+ if (Undefs.empty())
+ return;
+
+ for (ObjFile *File : ObjectFiles)
+ for (Symbol *Sym : File->getSymbols())
+ if (Undefs.count(Sym))
+ error(toString(File) + ": undefined symbol: " + toString(*Sym));
+
+ for (Symbol *Sym : Undefs)
+ if (!Sym->getFile())
+ error("undefined symbol: " + toString(*Sym));
+}
+
+Symbol *SymbolTable::find(StringRef Name) {
+ auto It = SymMap.find(CachedHashStringRef(Name));
+ if (It == SymMap.end())
+ return nullptr;
+ return It->second;
+}
+
+std::pair<Symbol *, bool> SymbolTable::insert(StringRef Name) {
+ Symbol *&Sym = SymMap[CachedHashStringRef(Name)];
+ if (Sym)
+ return {Sym, false};
+ Sym = make<Symbol>(Name, false);
+ SymVector.emplace_back(Sym);
+ return {Sym, true};
+}
+
+void SymbolTable::reportDuplicate(Symbol *Existing, InputFile *NewFile) {
+ error("duplicate symbol: " + toString(*Existing) + "\n>>> defined in " +
+ toString(Existing->getFile()) + "\n>>> defined in " +
+ toString(NewFile));
+}
+
+// Get the signature for a given function symbol, either by looking
+// it up in function sections (for defined functions), of the imports section
+// (for imported functions).
+static const WasmSignature *getFunctionSig(const ObjFile &Obj,
+ const WasmSymbol &Sym) {
+ DEBUG(dbgs() << "getFunctionSig: " << Sym.Name << "\n");
+ const WasmObjectFile *WasmObj = Obj.getWasmObj();
+ uint32_t FunctionType;
+ if (Obj.isImportedFunction(Sym.ElementIndex)) {
+ const WasmImport &Import = WasmObj->imports()[Sym.ImportIndex];
+ FunctionType = Import.SigIndex;
+ } else {
+ uint32_t FuntionIndex = Sym.ElementIndex - Obj.NumFunctionImports();
+ FunctionType = WasmObj->functionTypes()[FuntionIndex];
+ }
+ return &WasmObj->types()[FunctionType];
+}
+
+// Check the type of new symbol matches that of the symbol is replacing.
+// For functions this can also involve verifying that the signatures match.
+static void checkSymbolTypes(const Symbol &Existing, const InputFile &F,
+ const WasmSymbol &New,
+ const WasmSignature *NewSig) {
+ if (Existing.isLazy())
+ return;
+
+ bool NewIsFunction = New.Type == WasmSymbol::SymbolType::FUNCTION_EXPORT ||
+ New.Type == WasmSymbol::SymbolType::FUNCTION_IMPORT;
+
+ // First check the symbol types match (i.e. either both are function
+ // symbols or both are data symbols).
+ if (Existing.isFunction() != NewIsFunction) {
+ error("symbol type mismatch: " + New.Name + "\n>>> defined as " +
+ (Existing.isFunction() ? "Function" : "Global") + " in " +
+ toString(Existing.getFile()) + "\n>>> defined as " +
+ (NewIsFunction ? "Function" : "Global") + " in " + F.getName());
+ return;
+ }
+
+ // For function symbols, optionally check the function signature matches too.
+ if (!NewIsFunction || !Config->CheckSignatures)
+ return;
+ // Skip the signature check if the existing function has no signature (e.g.
+ // if it is an undefined symbol generated by --undefined command line flag).
+ if (!Existing.hasFunctionType())
+ return;
+
+ DEBUG(dbgs() << "checkSymbolTypes: " << New.Name << "\n");
+ assert(NewSig);
+
+ const WasmSignature &OldSig = Existing.getFunctionType();
+ if (*NewSig == OldSig)
+ return;
+
+ error("function signature mismatch: " + New.Name + "\n>>> defined as " +
+ toString(OldSig) + " in " + toString(Existing.getFile()) +
+ "\n>>> defined as " + toString(*NewSig) + " in " + F.getName());
+}
+
+Symbol *SymbolTable::addDefinedGlobal(StringRef Name) {
+ DEBUG(dbgs() << "addDefinedGlobal: " << Name << "\n");
+ Symbol *S;
+ bool WasInserted;
+ std::tie(S, WasInserted) = insert(Name);
+ if (WasInserted)
+ S->update(Symbol::DefinedGlobalKind);
+ else if (!S->isGlobal())
+ error("symbol type mismatch: " + Name);
+ return S;
+}
+
+Symbol *SymbolTable::addDefined(InputFile *F, const WasmSymbol *Sym,
+ const InputSegment *Segment) {
+ DEBUG(dbgs() << "addDefined: " << Sym->Name << "\n");
+ Symbol *S;
+ bool WasInserted;
+ Symbol::Kind Kind = Symbol::DefinedFunctionKind;
+ const WasmSignature *NewSig = nullptr;
+ if (Sym->Type == WasmSymbol::SymbolType::GLOBAL_EXPORT)
+ Kind = Symbol::DefinedGlobalKind;
+ else
+ NewSig = getFunctionSig(*cast<ObjFile>(F), *Sym);
+
+ std::tie(S, WasInserted) = insert(Sym->Name);
+ if (WasInserted) {
+ S->update(Kind, F, Sym, Segment, NewSig);
+ } else if (S->isLazy()) {
+ // The existing symbol is lazy. Replace it without checking types since
+ // lazy symbols don't have any type information.
+ DEBUG(dbgs() << "replacing existing lazy symbol: " << Sym->Name << "\n");
+ S->update(Kind, F, Sym, Segment, NewSig);
+ } else if (!S->isDefined()) {
+ // The existing symbol table entry is undefined. The new symbol replaces
+ // it, after checking the type matches
+ DEBUG(dbgs() << "resolving existing undefined symbol: " << Sym->Name
+ << "\n");
+ checkSymbolTypes(*S, *F, *Sym, NewSig);
+ S->update(Kind, F, Sym, Segment, NewSig);
+ } else if (Sym->isWeak()) {
+ // the new symbol is weak we can ignore it
+ DEBUG(dbgs() << "existing symbol takes precedence\n");
+ } else if (S->isWeak()) {
+ // the new symbol is not weak and the existing symbol is, so we replace
+ // it
+ DEBUG(dbgs() << "replacing existing weak symbol\n");
+ checkSymbolTypes(*S, *F, *Sym, NewSig);
+ S->update(Kind, F, Sym, Segment, NewSig);
+ } else {
+ // neither symbol is week. They conflict.
+ reportDuplicate(S, F);
+ }
+ return S;
+}
+
+Symbol *SymbolTable::addUndefinedFunction(StringRef Name,
+ const WasmSignature *Type) {
+ Symbol *S;
+ bool WasInserted;
+ std::tie(S, WasInserted) = insert(Name);
+ if (WasInserted) {
+ S->update(Symbol::UndefinedFunctionKind, nullptr, nullptr, nullptr, Type);
+ } else if (!S->isFunction()) {
+ error("symbol type mismatch: " + Name);
+ }
+ return S;
+}
+
+Symbol *SymbolTable::addUndefined(InputFile *F, const WasmSymbol *Sym) {
+ DEBUG(dbgs() << "addUndefined: " << Sym->Name << "\n");
+ Symbol *S;
+ bool WasInserted;
+ Symbol::Kind Kind = Symbol::UndefinedFunctionKind;
+ const WasmSignature *NewSig = nullptr;
+ if (Sym->Type == WasmSymbol::SymbolType::GLOBAL_IMPORT)
+ Kind = Symbol::UndefinedGlobalKind;
+ else
+ NewSig = getFunctionSig(*cast<ObjFile>(F), *Sym);
+ std::tie(S, WasInserted) = insert(Sym->Name);
+ if (WasInserted) {
+ S->update(Kind, F, Sym, nullptr, NewSig);
+ } else if (S->isLazy()) {
+ DEBUG(dbgs() << "resolved by existing lazy\n");
+ auto *AF = cast<ArchiveFile>(S->getFile());
+ AF->addMember(&S->getArchiveSymbol());
+ } else if (S->isDefined()) {
+ DEBUG(dbgs() << "resolved by existing\n");
+ checkSymbolTypes(*S, *F, *Sym, NewSig);
+ }
+ return S;
+}
+
+void SymbolTable::addLazy(ArchiveFile *F, const Archive::Symbol *Sym) {
+ DEBUG(dbgs() << "addLazy: " << Sym->getName() << "\n");
+ StringRef Name = Sym->getName();
+ Symbol *S;
+ bool WasInserted;
+ std::tie(S, WasInserted) = insert(Name);
+ if (WasInserted) {
+ S->update(Symbol::LazyKind, F);
+ S->setArchiveSymbol(*Sym);
+ } else if (S->isUndefined()) {
+ // There is an existing undefined symbol. The can load from the
+ // archive.
+ DEBUG(dbgs() << "replacing existing undefined\n");
+ F->addMember(Sym);
+ }
+}
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