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//===- lib/ReaderWriter/MachO/MachOPasses.h -------------------------------===//
//
// The LLVM Linker
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#ifndef LLD_READER_WRITER_MACHO_PASSES_H
#define LLD_READER_WRITER_MACHO_PASSES_H
#include "lld/Core/Atom.h"
#include "lld/Core/File.h"
#include "lld/Core/Pass.h"
#include "lld/Core/range.h"
#include "lld/Core/Reference.h"
#include <vector>
namespace lld {
class DefinedAtom;
class MutableFile;
/// Pass for adding stubs (PLT entries) for calls to functions
/// outside the linkage unit. This class is subclassed by each
/// file format Writer which implements the pure virtual methods.
class StubsPass : public Pass {
public:
StubsPass() : Pass() {}
/// Scans all Atoms looking for call-site uses of SharedLibraryAtoms
/// and transfroms the call-site to call a stub instead using the
/// helper methods below.
void perform(std::unique_ptr<MutableFile> &mergedFile) override;
/// If true, the pass should use stubs for references
/// to shared library symbols. If false, the pass
/// will generate relocations on the text segment which the
/// runtime loader will use to patch the program at runtime.
virtual bool noTextRelocs() = 0;
/// Returns whether the Reference kind is for a call site. The pass
/// uses this to find calls that need to be indirected through a stub.
virtual bool isCallSite(const Reference &) = 0;
/// Returns a file format specific atom for a stub/PLT entry which contains
/// instructions which jump to the specified atom. May be called multiple
/// times for the same target atom, in which case this method should return
/// the same stub atom.
virtual const DefinedAtom *getStub(const Atom &target) = 0;
/// After the default implementation of perform() is done calling getStub(),
/// it will call this method to add all the stub (and support) atoms to the
/// master file object.
virtual void addStubAtoms(MutableFile &masterFile) = 0;
private:
void replaceCalleeWithStub(const Atom *target, const Reference *ref);
};
/// Pass for adding GOT entries for pointers to functions/data
/// outside the linkage unit. This class is subclassed by each
/// file format Writer which implements the pure virtual methods.
class GOTPass : public Pass {
public:
GOTPass() : Pass() {}
/// Scans all Atoms looking for pointer to SharedLibraryAtoms
/// and transfroms them to a pointer to a GOT entry using the
/// helper methods below.
void perform(std::unique_ptr<MutableFile> &mergedFile) override;
/// If true, the pass will use GOT entries for references
/// to shared library symbols. If false, the pass
/// will generate relocations on the text segment which the
/// runtime loader will use to patch the program at runtime.
virtual bool noTextRelocs() = 0;
/// Returns whether the Reference kind is a pre-instantiated GOT access.
/// The default implementation of perform() uses this to figure out
/// what GOT entries to instantiate.
virtual bool isGOTAccess(const Reference &, bool &canBypassGOT) = 0;
/// The file format Writer needs to alter the reference kind from a
/// pre-instantiated GOT access to an actual access. If targetIsNowGOT is
/// true, the pass has instantiated a GOT atom and altered the reference's
/// target to point to that atom. If targetIsNowGOT is false, the pass
/// determined a GOT entry is not needed because the reference site can
/// directly access the target.
virtual void updateReferenceToGOT(const Reference*, bool targetIsNowGOT) = 0;
/// Returns a file format specific atom for a GOT entry targeting
/// the specified atom.
virtual const DefinedAtom *makeGOTEntry(const Atom &target) = 0;
};
} // namespace lld
#endif // LLD_READER_WRITER_MACHO_PASSES_H
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