forked from OSchip/llvm-project
95 lines
2.8 KiB
C++
95 lines
2.8 KiB
C++
//===- lib/ReaderWriter/PECOFF/LinkerGeneratedSymbolFile.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 "Atoms.h"
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#include "GroupedSectionsPass.h"
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#include "IdataPass.h"
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#include "llvm/ADT/SmallString.h"
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#include "llvm/Support/Allocator.h"
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#include "llvm/Support/Path.h"
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#include "lld/Core/ArchiveLibraryFile.h"
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#include "lld/Core/PassManager.h"
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#include "lld/Passes/LayoutPass.h"
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#include "lld/ReaderWriter/PECOFFLinkingContext.h"
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#include "lld/ReaderWriter/Reader.h"
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#include "lld/ReaderWriter/Simple.h"
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#include "lld/ReaderWriter/Writer.h"
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namespace lld {
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namespace coff {
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namespace {
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// A virtual file containing absolute symbol __ImageBase. __ImageBase (or
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// ___ImageBase on x86) is a linker-generated symbol whose address is the same
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// as the image base address.
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//
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// This is the only member file of LinkerGeneratedSymbolFile.
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class MemberFile : public SimpleFile {
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public:
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MemberFile(const PECOFFLinkingContext &ctx)
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: SimpleFile(ctx, "Member of the Linker Internal File"),
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_imageBaseAtom(*this, ctx.decorateSymbol("__ImageBase"),
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Atom::scopeGlobal, ctx.getBaseAddress()) {
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addAtom(_imageBaseAtom);
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};
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bool contains(StringRef name) const {
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return _imageBaseAtom.name() == name;
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}
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private:
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COFFAbsoluteAtom _imageBaseAtom;
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};
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} // anonymous namespace
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// A pseudo library file to wrap MemberFile, which in turn wraps ImageBaseAtom.
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// The file the core linker handle is this.
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//
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// The reason why we don't pass MemberFile to the core linker is because, if we
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// did so, ImageBaseAtom would always be emit to the resultant executable. By
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// wrapping the file by a library file, we made it to emit ImageBaseAtom only
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// when the atom is really referenced.
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class LinkerGeneratedSymbolFile : public ArchiveLibraryFile {
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public:
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LinkerGeneratedSymbolFile(const PECOFFLinkingContext &context)
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: ArchiveLibraryFile(context, "Linker Internal File"),
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_memberFile(context) {};
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virtual const File *find(StringRef name, bool dataSymbolOnly) const {
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if (_memberFile.contains(name))
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return &_memberFile;
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return nullptr;
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}
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virtual const atom_collection<DefinedAtom> &defined() const {
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return _noDefinedAtoms;
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}
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virtual const atom_collection<UndefinedAtom> &undefined() const {
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return _noUndefinedAtoms;
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}
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virtual const atom_collection<SharedLibraryAtom> &sharedLibrary() const {
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return _noSharedLibraryAtoms;
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}
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virtual const atom_collection<AbsoluteAtom> &absolute() const {
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return _noAbsoluteAtoms;
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}
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private:
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MemberFile _memberFile;
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};
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} // end namespace coff
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} // end namespace lld
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