76 lines
2.6 KiB
C++
76 lines
2.6 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 "lld/ReaderWriter/PECOFFLinkingContext.h"
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#include "lld/ReaderWriter/Simple.h"
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#include "llvm/Support/Allocator.h"
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namespace lld {
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namespace pecoff {
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/// The defined atom for dllexported symbols with __imp_ prefix.
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class ImpPointerAtom : public COFFLinkerInternalAtom {
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public:
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ImpPointerAtom(const File &file, StringRef symbolName, uint64_t ordinal)
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: COFFLinkerInternalAtom(file, /*oridnal*/ 0, std::vector<uint8_t>(4),
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symbolName),
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_ordinal(ordinal) {}
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uint64_t ordinal() const override { return _ordinal; }
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Scope scope() const override { return scopeGlobal; }
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ContentType contentType() const override { return typeData; }
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Alignment alignment() const override { return Alignment(4); }
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ContentPermissions permissions() const override { return permR__; }
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private:
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uint64_t _ordinal;
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};
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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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class LinkerGeneratedSymbolFile : public SimpleFile {
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public:
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LinkerGeneratedSymbolFile(const PECOFFLinkingContext &ctx)
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: SimpleFile("<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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_ordinal = 1;
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// Create implciit symbols for exported symbols.
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for (const PECOFFLinkingContext::ExportDesc &exp : ctx.getDllExports()) {
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UndefinedAtom *target = new (_alloc) SimpleUndefinedAtom(*this, exp.name);
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COFFLinkerInternalAtom *imp = createImpPointerAtom(ctx, exp.name);
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imp->addReference(std::unique_ptr<COFFReference>(
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new COFFReference(target, 0, llvm::COFF::IMAGE_REL_I386_DIR32)));
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addAtom(*target);
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addAtom(*imp);
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}
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};
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private:
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COFFLinkerInternalAtom *createImpPointerAtom(const PECOFFLinkingContext &ctx,
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StringRef name) {
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std::string sym = "_imp_";
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sym.append(name);
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sym = ctx.decorateSymbol(sym);
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return new (_alloc) ImpPointerAtom(*this, ctx.allocate(sym), _ordinal++);
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}
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COFFAbsoluteAtom _imageBaseAtom;
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uint64_t _ordinal;
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llvm::BumpPtrAllocator _alloc;
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};
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} // end namespace pecoff
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} // end namespace lld
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