d26c8e3463
This adds an API to the LinkingContext for flavors to add Internal files containing atoms that need to appear in the YAML output as well, when -emit-yaml switch is used. Flavors can add more internal files for other options that are needed. llvm-svn: 189718
116 lines
3.7 KiB
C++
116 lines
3.7 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/InputFiles.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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// The symbol __ImageBase is a linker generated symbol. No standard library
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// files define it, but the linker is expected to prepare it as if it was read
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// from a file. The content of the atom is a 4-byte integer equal to the image
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// base address.
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//
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// Note that because the name is prefixed by an underscore on x86 Win32, the
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// actual symbol name becomes ___ImageBase (with three underscores). On other
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// architectures names are not mangled with an underscore. We need to handle
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// name mangling correctly when porting LLD Windows code to them.
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class ImageBaseAtom : public COFFLinkerInternalAtom {
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public:
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ImageBaseAtom(const File &file, uint32_t imageBase)
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: COFFLinkerInternalAtom(file, assembleRawContent(imageBase)) {}
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virtual StringRef name() const { return "___ImageBase"; }
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virtual uint64_t ordinal() const { return 0; }
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virtual ContentType contentType() const { return typeData; }
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virtual ContentPermissions permissions() const { return permRW_; }
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virtual DeadStripKind deadStrip() const { return deadStripAlways; }
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private:
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std::vector<uint8_t> assembleRawContent(uint32_t imageBase) {
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std::vector<uint8_t> data = std::vector<uint8_t>(4);
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*(reinterpret_cast<uint32_t *>(&data[0])) = imageBase;
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return data;
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}
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};
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// The file to wrap ImageBaseAtom. This is the only member file of
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// LinkerGeneratedSymbolFile.
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class MemberFile : public SimpleFile {
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public:
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MemberFile(const PECOFFLinkingContext &context)
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: SimpleFile(context, "Member of the Linker Internal File"),
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_atom(*this, context.getBaseAddress()) {
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addAtom(_atom);
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};
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private:
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ImageBaseAtom _atom;
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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 (name == "___ImageBase")
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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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