+#ifndef LLVM_SYSTEM_INCLUDEFILE_H
+#define LLVM_SYSTEM_INCLUDEFILE_H
+
+/// This macro is the public interface that IncludeFile.h exports. This gives
+/// us the option to implement the "link the definition" capability in any
+/// manner that we choose. All header files that depend on a specific .cpp
+/// file being linked at run time should use this macro instead of the
+/// IncludeFile class directly.
+///
+/// For example, foo.h would use:<br/>
+/// <tt>FORCE_DEFINING_FILE_TO_BE_LINKED(foo)</tt><br/>
+///
+/// And, foo.cp would use:<br/>
+/// <tt>DEFINING_FILE_FOR(foo)</tt><br/>
+#ifdef __GNUC__
+// If the `used' attribute is available, use it to create a variable
+// with an initializer that will force the linking of the defining file.
+#define FORCE_DEFINING_FILE_TO_BE_LINKED(name) \
+ namespace llvm { \
+ extern const char name ## LinkVar; \
+ __attribute__((used)) static const char *const name ## LinkObj = \
+ &name ## LinkVar; \
+ }
+#else
+// Otherwise use a constructor call.
+#define FORCE_DEFINING_FILE_TO_BE_LINKED(name) \
+ namespace llvm { \
+ extern const char name ## LinkVar; \
+ static const IncludeFile name ## LinkObj ( &name ## LinkVar ); \
+ }
+#endif
+
+/// This macro is the counterpart to FORCE_DEFINING_FILE_TO_BE_LINKED. It should
+/// be used in a .cpp file to define the name referenced in a header file that
+/// will cause linkage of the .cpp file. It should only be used at extern level.
+#define DEFINING_FILE_FOR(name) \
+ namespace llvm { const char name ## LinkVar = 0; }
+
+namespace llvm {
+
+/// This class is used in the implementation of FORCE_DEFINING_FILE_TO_BE_LINKED
+/// macro to make sure that the implementation of a header file is included
+/// into a tool that uses the header. This is solely
+/// to overcome problems linking .a files and not getting the implementation