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59f959ff33
When function signatures don't match and the undefined function is not called directly (i.e. only has its address taken) we don't issue a warning or create a runtime thunk for the undefined function. Instead in this case we simply use the defined version of the function. This is possible since checking signatures of dynamic calls happens at runtime so any invalid usage will still result in a runtime error. This is needed to allow C++ programs to link without generating warnings. Its not uncommon in C++ for vtables to be populated by function address whee the signature of the function is not known in the compilation unit. In this case clang declares the method as void(void) and relies on the vtable caller casting the data back to the correct signature. Fixes: https://bugs.llvm.org/show_bug.cgi?id=40412 Differential Revision: https://reviews.llvm.org/D62153 llvm-svn: 361678
128 lines
4.8 KiB
C++
128 lines
4.8 KiB
C++
//===- SymbolTable.h --------------------------------------------*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLD_WASM_SYMBOL_TABLE_H
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#define LLD_WASM_SYMBOL_TABLE_H
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#include "InputFiles.h"
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#include "LTO.h"
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#include "Symbols.h"
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#include "lld/Common/LLVM.h"
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#include "llvm/ADT/CachedHashString.h"
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#include "llvm/ADT/DenseSet.h"
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namespace lld {
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namespace wasm {
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class InputSegment;
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// SymbolTable is a bucket of all known symbols, including defined,
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// undefined, or lazy symbols (the last one is symbols in archive
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// files whose archive members are not yet loaded).
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//
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// We put all symbols of all files to a SymbolTable, and the
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// SymbolTable selects the "best" symbols if there are name
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// conflicts. For example, obviously, a defined symbol is better than
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// an undefined symbol. Or, if there's a conflict between a lazy and a
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// undefined, it'll read an archive member to read a real definition
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// to replace the lazy symbol. The logic is implemented in the
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// add*() functions, which are called by input files as they are parsed.
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// There is one add* function per symbol type.
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class SymbolTable {
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public:
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void wrap(Symbol *Sym, Symbol *Real, Symbol *Wrap);
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void addFile(InputFile *File);
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void addCombinedLTOObject();
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void reportRemainingUndefines();
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ArrayRef<Symbol *> getSymbols() const { return SymVector; }
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Symbol *find(StringRef Name);
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void replace(StringRef Name, Symbol* Sym);
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void trace(StringRef Name);
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Symbol *addDefinedFunction(StringRef Name, uint32_t Flags, InputFile *File,
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InputFunction *Function);
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Symbol *addDefinedData(StringRef Name, uint32_t Flags, InputFile *File,
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InputSegment *Segment, uint32_t Address,
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uint32_t Size);
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Symbol *addDefinedGlobal(StringRef Name, uint32_t Flags, InputFile *File,
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InputGlobal *G);
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Symbol *addDefinedEvent(StringRef Name, uint32_t Flags, InputFile *File,
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InputEvent *E);
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Symbol *addUndefinedFunction(StringRef Name, StringRef ImportName,
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StringRef ImportModule, uint32_t Flags,
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InputFile *File, const WasmSignature *Signature,
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bool IsCalledDirectly);
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Symbol *addUndefinedData(StringRef Name, uint32_t Flags, InputFile *File);
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Symbol *addUndefinedGlobal(StringRef Name, StringRef ImportName,
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StringRef ImportModule, uint32_t Flags,
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InputFile *File, const WasmGlobalType *Type);
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void addLazy(ArchiveFile *F, const llvm::object::Archive::Symbol *Sym);
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bool addComdat(StringRef Name);
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DefinedData *addSyntheticDataSymbol(StringRef Name, uint32_t Flags);
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DefinedGlobal *addSyntheticGlobal(StringRef Name, uint32_t Flags,
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InputGlobal *Global);
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DefinedFunction *addSyntheticFunction(StringRef Name, uint32_t Flags,
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InputFunction *Function);
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DefinedData *addOptionalDataSymbol(StringRef Name, uint32_t Value,
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uint32_t Flags);
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void handleSymbolVariants();
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void handleWeakUndefines();
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std::vector<ObjFile *> ObjectFiles;
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std::vector<SharedFile *> SharedFiles;
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std::vector<BitcodeFile *> BitcodeFiles;
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std::vector<InputFunction *> SyntheticFunctions;
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std::vector<InputGlobal *> SyntheticGlobals;
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private:
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std::pair<Symbol *, bool> insert(StringRef Name, const InputFile *File);
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std::pair<Symbol *, bool> insertName(StringRef Name);
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bool getFunctionVariant(Symbol* Sym, const WasmSignature *Sig,
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const InputFile *File, Symbol **Out);
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InputFunction *replaceWithUnreachable(Symbol *Sym, const WasmSignature &Sig,
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StringRef DebugName);
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// Maps symbol names to index into the SymVector. -1 means that symbols
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// is to not yet in the vector but it should have tracing enabled if it is
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// ever added.
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llvm::DenseMap<llvm::CachedHashStringRef, int> SymMap;
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std::vector<Symbol *> SymVector;
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// For certain symbols types, e.g. function symbols, we allow for muliple
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// variants of the same symbol with different signatures.
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llvm::DenseMap<llvm::CachedHashStringRef, std::vector<Symbol *>> SymVariants;
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// Comdat groups define "link once" sections. If two comdat groups have the
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// same name, only one of them is linked, and the other is ignored. This set
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// is used to uniquify them.
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llvm::DenseSet<llvm::CachedHashStringRef> ComdatGroups;
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// For LTO.
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std::unique_ptr<BitcodeCompiler> LTO;
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};
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extern SymbolTable *Symtab;
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} // namespace wasm
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} // namespace lld
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#endif
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