* c-common.c (handle_used_attribute): Set DECL_PRESERVE_P.

    * c-common.c (handle_used_attribute): Set DECL_PRESERVE_P.
        * print-tree.c (print_node): Print DECL_PRESERVE_P.
        * target-def.h (TARGET_ASM_MARK_DECL_PRESERVED): New #define.
        (TARGET_ASM_OUT): New member, TARGET_ASM_MARK_DECL_PRESERVED
        * target.h (struct gcc_target): New member, mark_decl_preserved.
        * hooks.c (hook_void_charptr): Rename to ...
        (hook_void_constcharptr): ... new name.
        * hooks.h (hook_void_charptr): Rename to ..
        (hook_void_constcharptr): ... new name.
        * tree.h (DECL_PRESERVE_P): New #define.
        (struct tree_decl): New member, preserve_flag.
        * varasm.c (assemble_start_function): Mark decl preserved.
        (assemble_variable): Same.
        * darwin.c (darwin_mark_decl_preserved): New function.
        * darwin.h (TARGET_ASM_MARK_DECL_preserved): New #define.
        * darwin-protos.h (darwin_mark_decl_preserved): New decl.
        * doc/tm.texi (TARGET_ASM_MARK_DECL_PRESERVED): Document.

        testsuite:
        * gcc.dg/darwin-20040809-1.c: New test.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@86076 138bc75d-0d04-0410-961f-82ee72b054a4