Recommit R274836 Add Thunk support framework for ARM and Mips
The TinyPtrVector of const Thunk<ELFT>* in InputSections.h can cause
build failures on certain compiler/library combinations when Thunk<ELFT>
is not a complete type or is an abstract class. Fixed by making Thunk<ELFT>
non Abstract.
type or is an abstract class
llvm-svn: 274863
diff --git a/lld/ELF/Thunks.h b/lld/ELF/Thunks.h
new file mode 100644
index 0000000..754bcad
--- /dev/null
+++ b/lld/ELF/Thunks.h
@@ -0,0 +1,55 @@
+//===- Thunks.h --------------------------------------------------------===//
+//
+// The LLVM Linker
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLD_ELF_THUNKS_H
+#define LLD_ELF_THUNKS_H
+
+#include "Relocations.h"
+
+namespace lld {
+namespace elf {
+class SymbolBody;
+class InputFile;
+template <class ELFT> class InputSection;
+template <class ELFT> class InputSectionBase;
+
+// Class to describe an instance of a Thunk.
+// A Thunk is a code-sequence inserted by the linker in between a caller and
+// the callee. The relocation to the callee is redirected to the Thunk, which
+// after executing transfers control to the callee. Typical uses of Thunks
+// include transferring control from non-pi to pi and changing state on
+// targets like ARM.
+//
+// Thunks can be created for DefinedRegular and Shared Symbols. The Thunk
+// is stored in a field of the Symbol Destination.
+// Thunks to be written to an InputSection are recorded by the InputSection.
+template <class ELFT> class Thunk {
+public:
+ virtual uint32_t size() const { return 0; }
+ typename ELFT::uint getVA() const;
+ virtual void writeTo(uint8_t *Buf) const {};
+ Thunk(const SymbolBody &Destination, const InputSection<ELFT> &Owner);
+ virtual ~Thunk();
+
+protected:
+ const SymbolBody &Destination;
+ const InputSection<ELFT> &Owner;
+ uint64_t Offset;
+};
+
+// For a Relocation to symbol S from InputSection Src, create a Thunk and
+// update the fields of S and the InputSection that the Thunk body will be
+// written to. At present there are implementations for ARM and Mips Thunks.
+template <class ELFT>
+void addThunk(uint32_t RelocType, SymbolBody &S, InputSection<ELFT> &Src);
+
+} // namespace elf
+} // namespace lld
+
+#endif
